Tag Archives: Nuclear Experiment

Production of $p$-nuclei from $r$-process seeds: the $νr$-process [HEAP]

Posted on by

http://arxiv.org/abs/2305.11050


We present a new nucleosynthesis process that may take place on neutron-rich ejecta experiencing an intensive neutrino flux. The nucleosynthesis proceeds similarly to the standard $r$-process, a sequence of neutron-captures and beta-decays, however with charged-current neutrino absorption reactions on nuclei operating much faster than beta-decays. Once neutron capture reactions freeze-out the produced $r$-process neutron-rich nuclei undergo a fast conversion of neutrons into protons and are pushed even beyond the $\beta$-stability line producing the neutron-deficient $p$-nuclei. This scenario, which we denote as the $\nu r$-process, provides an alternative channel for the production of $p$-nuclei and the short-lived nucleus $^{92}$Nb. We discuss the necessary conditions posed on the astrophysical site for the $\nu r$-process to be realized in nature. While these conditions are not fulfilled by current neutrino-hydrodynamic models of $r$-process sites, future models, including more complex physics and a larger variety of outflow conditions, may achieve the necessary conditions in some regions of the ejecta.

Read this paper on arXiv…

Z. Xiong, G. Martínez-Pinedo, O. Just, et. al.
Fri, 19 May 23
42/46

Comments: 8 pages, 5 figures, submitted to PRL

Phase Transition Phenomenology with Nonparametric Representations of the Neutron Star Equation of State [HEAP]

Posted on by

http://arxiv.org/abs/2305.07411


Astrophysical observations of neutron stars probe the structure of dense nuclear matter and have the potential to reveal phase transitions at high densities. Most recent analyses are based on parametrized models of the equation of state with a finite number of parameters and occasionally include extra parameters intended to capture phase transition phenomenology. However, such models restrict the types of behavior allowed and may not match the true equation of state. We introduce a complementary approach that extracts phase transitions directly from the equation of state without relying on, and thus being restricted by, an underlying parametrization. We then constrain the presence of phase transitions in neutron stars with astrophysical data. Current pulsar mass, tidal deformability, and mass-radius measurements disfavor only the strongest of possible phase transitions (latent energy per particle $\gtrsim 100\,\mathrm{MeV}$). Weaker phase transitions are consistent with observations. We further investigate the prospects for measuring phase transitions with future gravitational-wave observations and find that catalogs of \result{$O(100)$} events will (at best) yield Bayes factors of $\sim 10:1$ in favor of phase transitions even when the true equation of state contains very strong phase transitions. Our results reinforce the idea that neutron star observations will primarily constrain trends in macroscopic properties rather than detailed microscopic behavior. Fine-tuned equation of state models will likely remain unconstrained in the near future.

Read this paper on arXiv…

R. Essick, I. Legred, K. Chatziioannou, et. al.
Mon, 15 May 23
53/53

Comments: 18 pages (+12 pages of references and appendix), 17 figures, 5 tables

Evidence of Space weather in Radon Decay [CL]

Posted on by

http://arxiv.org/abs/2305.06882


The Electron, Proton and Alpha Monitor, EPAM, located at the L1 Position approximately 1-million miles from the earth in the direction of the sun, was designed to detect fluctuations in solar output through counting the numbers of various particles hitting the detector. The EPAM detector is part of an early warning system that can alert the earth to coronal mass ejection events that can damage our electronic grids and satellite equipment. EPAM gives a real-time estimate of changes in the local solar magnetic field directed towards the earth, recorded in the fluctuations of solar particles being ejected. This paper presents an analysis of fluctuations in data taken by the Geological Survey of Israel, GSI, compared to the changes in detected numbers of protons as seen by EPAM. Surprisingly, the GSI and EPAM detectors show an unexpected correlation between the variation in count rate detected by the GSI detectors and an increased numbers of protons seen at EPAM; well above statistical significance of 5-sigma, indicating a non-random connection between the data sets. The statistically significant overlap between data taken by these two detectors, subject to very different conditions, may hint at a Primakoff mechanism whereby exotic particles, e.g. galactic Dark Matter, couple through magnetic fields to both photons and even nuclei. This work builds on an earlier paper on the observations of Radon decay and their implications for particle physics.

Read this paper on arXiv…

C. Scarlett, E. Fischbach, B. Freeman, et. al.
Fri, 12 May 23
51/53

Comments: N/A

Search for astrophysical electron antineutrinos in Super-Kamiokande with 0.01wt% gadolinium loaded water [HEAP]

Posted on by

http://arxiv.org/abs/2305.05135


We report the first search result for the flux of astrophysical electron antineutrinos for energies O(10) MeV in the gadolinium-loaded Super-Kamiokande (SK) detector. In June 2020, gadolinium was introduced to the ultra-pure water of the SK detector in order to detect neutrons more efficiently. In this new experimental phase, SK-Gd, we can search for electron antineutrinos via inverse beta decay with efficient background rejection and higher signal efficiency thanks to the high efficiency of the neutron tagging technique. In this paper, we report the result for the initial stage of SK-Gd with a $22.5\times552$ $\rm kton\cdot day$ exposure at 0.01% Gd mass concentration. No significant excess over the expected background in the observed events is found for the neutrino energies below 31.3 MeV. Thus, the flux upper limits are placed at the 90% confidence level. The limits and sensitivities are already comparable with the previous SK result with pure-water ($22.5 \times 2970 \rm kton\cdot day$) owing to the enhanced neutron tagging.

Read this paper on arXiv…

M. Harada, K. Abe, C. Bronner, et. al.
Wed, 10 May 23
22/65

Comments: N/A

Analytical Fitting of Gamma-ray Photopeaks in Germanium Cross Strip Detectors [IMA]

Posted on by

http://arxiv.org/abs/2305.01544


In an ideal germanium detector, fully-absorbed monoenergetic gamma-rays will appear in the measured spectrum as a narrow peak, broadened into a Gaussian of width determined only by the statistical properties of charge cloud generation and the electronic noise of the readout electronics. Multielectrode detectors complicate this picture. Broadening of the charge clouds as they drift through the detector will lead to charge sharing between neighboring electrodes and, inevitably, low-energy tails on the photopeak spectra. We simulate charge sharing in our germanium cross strip detectors in order to reproduce the low-energy tails due to charge sharing. Our goal is to utilize these simulated spectra to develop an analytical fit (shape function) for the spectral lines that provides a robust and high-quality fit to the spectral profile, reliably reproduces the interaction energy, noise width, and the number of counts in both the true photopeak and the low-energy tail, and minimizes the number of additional parameters. Accurate modeling of the detailed line profiles is crucial for both calibration of the detectors as well as scientific interpretation of measured spectra.

Read this paper on arXiv…

S. Boggs and S. Pike
Wed, 3 May 23
8/67

Comments: Submitted to NIM A

DT fusion through the $^5$He $3/2+$ "Bretscher state" accounts for $\ge 25\%$ of our existence via nucleosynthesis and for the possibility of fusion energy [CL]

Posted on by

http://arxiv.org/abs/2305.00647


In big bang nucleosynthesis (BBN), the deuterium-tritium (DT) fusion reaction, D(T,n)$\alpha$, enhanced by the 3/2$^+$ resonance, is responsible for 99% of primordial $^4$He. This has been known for decades and has been well documented in the scientific literature. However, following the tradition adopted by authors of learned articles, it was stated in a matter-of-fact manner and not emphasized; for most people, it has remained unknown. This helium became a source for the subsequent creation of $\geq$25\% of the carbon and other heavier elements and, thus, a substantial fraction of our human bodies. (To be more precise than $\geq$25\% will require future simulation studies on stellar nucleosynthesis.)
Also, without this resonance, controlled fusion energy would be beyond reach. For example, for inertial confinement fusion (ICF), laser energy delivery for the National Ignition Facility (NIF) would have to be approximately 70 times larger for ignition.
Because the resonance enhances the DT fusion cross section a hundredfold, we propose that the 3/2$^+$ $^5$He excited state be referred to as the “Bretscher state” in honor of the Manhattan Project scientist who discovered it, in analogy with the well-known 7.6 MeV “Hoyle state” in $^{12}$C that allows for the resonant 3$\alpha$ formation.

Read this paper on arXiv…

M. Chadwick, M. Paris and B. Haines
Tue, 2 May 23
4/57

Comments: 4 pages, 4 figures

Determination of the neutron skin of $^{208}$Pb from ultrarelativistic nuclear collisions [CL]

Posted on by

http://arxiv.org/abs/2305.00015


Emergent bulk properties of matter governed by the strong nuclear force give rise to physical phenomena across vastly different scales, ranging from the shape of atomic nuclei to the masses and radii of neutron stars. They can be accessed on Earth by measuring the spatial extent of the outer skin made of neutrons that characterises the surface of heavy nuclei. The isotope $^{208}$Pb, owing to its simple structure and neutron excess, has been in this context the target of many dedicated efforts. Here, we determine the neutron skin from measurements of particle distributions and their collective flow in $^{208}$Pb+$^{208}$Pb collisions at ultrarelativistic energy performed at the Large Hadron Collider, which are sensitive to the overall size of the colliding $^{208}$Pb ions. By means of state-of-the-art global analysis tools within the hydrodynamic model of heavy-ion collisions, we infer a neutron skin $\Delta r_{np}=0.217\pm0.058$ fm, consistent with nuclear theory predictions, and competitive in accuracy with a recent determination from parity-violating asymmetries in polarised electron scattering. We establish thus a new experimental method to systematically measure neutron distributions in the ground state of atomic nuclei.

Read this paper on arXiv…

G. Giacalone, G. Nijs and W. Schee
Tue, 2 May 23
47/57

Comments: 8 pages, 6 figures. The Trajectum code can be found at this https URL Plotting routines can be found at this http URL

A New Momentum-Integrated Muon Tomography Imaging Algorithm [CL]

Posted on by

http://arxiv.org/abs/2304.14427


For decades, the application of muon tomography to spent nuclear fuel (SNF) cask imaging has been theoretically evaluated and experimentally verified by many research groups around the world, including Los Alamos National Laboratory in the United States, Canadian Nuclear Laboratory in Canada, the National Institute for Nuclear Physics in Italy, and Toshiba in Japan. Although monitoring of SNF using cosmic ray muons has attracted significant attention as a promising nontraditional nondestructive radiographic technique, the wide application of muon tomography is often limited because of the natural low cosmic ray muon flux at sea level: 100 m-2min-1sr-1. Recent studies suggest measuring muon momentum in muon scattering tomography (MST) applications to address this challenge. Some techniques have been discussed; however, an imaging algorithm for momentum-coupled MST had not been developed. This paper presents a new imaging algorithm for MST which integrates muon scattering angle and momentum in a single M-value. To develop a relationship between muon momentum and scattering angle distribution, various material samples (Al, Fe, Pb, and U) were thoroughly investigated using a Monte Carlo particle transport code GEANT4 simulation. Reconstructed images of an SNF cask using the new algorithm are presented herein to demonstrate the benefit of measuring muon momentum in MST. In this analysis a missing fuel assembly (FA) was located in the dry storage cask.

Read this paper on arXiv…

J. Bae, R. Montgomery and S. Chatzidakis
Mon, 1 May 23
47/51

Comments: Transactions of American Nuclear Society

Modeling Charge Cloud Dynamics in Cross Strip Semiconductor Detectors [IMA]

Posted on by

http://arxiv.org/abs/2304.09713


When a $\gamma$-ray interacts in a semiconductor detector, the resulting electron-hole charge clouds drift towards their respective electrodes for signal collection. These charge clouds will expand over time due to both thermal diffusion and mutual electrostatic repulsion. Solutions to the resulting charge profiles are well understood for the limiting cases accounting for only diffusion and only repulsion, but the general solution including both effects can only be solved numerically. Previous attempts to model these effects have taken into account the broadening of the charge profile due to both effects, but have simplified the shape of the profile by assuming Gaussian distributions. However, the detailed charge profile can have important impacts on charge sharing in multi-electrode strip detectors. In this work, we derive an analytical approximation to the general solution, including both diffusion and repulsion, that closely replicates both the width and the detailed shape of the charge profiles. This analytical solution simplifies the modeling of charge clouds in semiconductor strip detectors.

Read this paper on arXiv…

S. Boggs
Thu, 20 Apr 23
4/57

Comments: Accepted for publication in Nuclear Instruments and Methods in Physics Research A

Properties of First-Order Hadron-Quark Phase Transition from Directly Inverting Neutron Star Observables [CL]

Posted on by

http://arxiv.org/abs/2304.07381


By directly inverting the observational data of several neutron star observables in the three dimensional parameter space of the constant speed of sound (CSS) model while fixing all hadronic Equation of State parameters at their currently known most probable values, we constrain the three parameters of the CSS model and their correlations. Using two lower radius limits of $R_{2.01}=11.41$ km and $R_{2.01}=12.2$ km for PSR J0740+6620 obtained from two independent analyses using different approaches by the Neutron Star Interior Composition Explorer (NICER) Collaboration, the speed of sound squared $c_{\rm QM}^2$ in quark matter is found to have a lower limit of $0.35$ and $0.43$ in unit of $c^2$, respectively, above its conformal limit of $c_{\rm QM}^2<1/3$. Moreover, an approximately linear correlation between the first-order hadron-quark transition density $\rho_t$ and its strength $\Delta\varepsilon$ is found.

Read this paper on arXiv…

N. Zhang and B. Li
Tue, 18 Apr 23
75/80

Comments: 7 pages with 4 figures

Building an Equation of State Density Ladder [CL]

Posted on by

http://arxiv.org/abs/2304.05441


The confluence of major theoretical, experimental, and observational advances are providing a unique perspective on the equation of state of dense neutron-rich matter — particularly its symmetry energy — and its imprint on the mass-radius relation for neutron stars. In this contribution we organize these developments in an equation of state density ladder. Of particular relevance to this discussion is the impact of the various rungs on the equation of state and the identification of possible discrepancies among the various methods. A preliminary analysis identifies a possible tension between laboratory measurements and gravitational-wave detections that could indicate the emergence of a phase transition in the stellar core.

Read this paper on arXiv…

M. Salinas and J. Piekarewicz
Thu, 13 Apr 23
54/59

Comments: N/A

Asymptotic normalization coefficients of alpha-particle removal from $^{16}$O($3^-,2^+,1^-$) [CL]

Posted on by

http://arxiv.org/abs/2304.02821


Asymptotic normalization coefficients (ANC) determine the overall normalization of cross sections of peripheral radiative capture reactions. In a recent paper [Blokhintsev {\em et al.}, Eur. Phys. J. A {\bf 58}, 257 (2022)], we considered the ANC $C_0$ for the virtual decay $^{16}$O$(0^+; 6.05$ MeV)$\to \alpha+^{12}$C(g.s.). In the present paper, which can be regarded as a continuation of the previous, we treat the ANCs $C_l$ for the vertices $^{16}$O$(J^\pi)\to \alpha+^{12}$C(g.s.) corresponding to the other three bound excited states of $^{16}$O ($J^\pi=3^-$, $2^+$, $1^-$, $l=J$). ANCs $C_l$ ($l=3,\,2,\,1$) are found by analytic continuation in energy of the $\alpha^{12}$C $l$-wave partial scattering amplitudes, known from the phase-shift analysis of experimental data, to the pole corresponding to the $^{16}$O bound state and lying in the unphysical region of negative energies. To determine $C_l$, the scattering data are approximated by the sum of polynomials in energy in the physical region and then extrapolated to the pole. For a more reliable determination of the ANCs, various forms of functions expressed in terms of phase shifts were used in analytical approximation and subsequent extrapolation.

Read this paper on arXiv…

L. Blokhintsev, A. Kadyrov, A. Mukhamedzhanov, et. al.
Fri, 7 Apr 23
30/50

Comments: arXiv admin note: substantial text overlap with arXiv:2208.09587

Polaronic Proton and Diproton Clustering in Neutron-Rich Matter [CL]

Posted on by

http://arxiv.org/abs/2304.00535


We show that strong spin-triplet neutron-proton interaction causes polaronic protons to occur in neutron matter at subnuclear densities and nonzero temperature. As the neutron density increases, proton spectra exhibit a smooth crossover from a bare impurity to a repulsive polaron branch; this branch coexists with an attractive polaron branch. With the neutron density increased further, the attractive polarons become stable with respect to deuteron formation. For two adjacent protons, we find that the polaron effects and the neutron-mediated attraction are sufficient to induce a bound diproton, which leads possibly to diproton formation in the surface region of neutron-rich nuclei in laboratories as well as in neutron stars.

Read this paper on arXiv…

H. Tajima, H. Moriya, W. Horiuchi, et. al.
Tue, 4 Apr 23
20/111

Comments: 6 pages, 4 figures (8 pages, 6 figures in the supplement)

Energy flow in Ultra High Energy Cosmic Ray interactions as a probe of thermalization and potential solution to the Muon puzzle [CL]

Posted on by

http://arxiv.org/abs/2304.00294


Indicators that illustrate the formation of a strongly interacting thermalized matter of partons have been observed in high-multiplicity proton-proton, proton-nucleus, and nucleus-nucleus collisions at RHIC and LHC energies. Strangeness enhancement in such ultra-relativistic heavy-ion collisions is considered to be a consequence of this thermalized phase, known as quark-gluon plasma (QGP). Simultaneously, proper modeling of hadronic energy fraction in interactions of ultra-high energy cosmic rays (UHECR) has been proposed as a solution for the muon puzzle. These interactions have center-of-mass collision energies in the order of LHC or higher, indicating that the possibility of a thermalized partonic state cannot be overlooked in UHECR-air interactions. This work investigates the hadronic energy fraction and strangeness enhancement to explore QGP-like phenomena in UHECR-air interactions using various high-energy hadronic models. A thermalized system with statistical hadronization is considered through the EPOS LHC model, while PYTHIA 8, QGSJET II-04, and SYBILL 2.3d consider string fragmentation in the absence of any thermalization. We have found that EPOS LHC gives a better description of strangeness enhancement as compared to other models. We conclude that adequately treating all the relevant effects and further retuning the models is necessary to explain the observed effects.

Read this paper on arXiv…

R. Scaria, S. Deb, C. Singh, et. al.
Tue, 4 Apr 23
109/111

Comments: 7 pages and 6 figures. Submitted for publication

Theoretical and Experimental Constraints for the Equation of State of Dense and Hot Matter [CL]

Posted on by

http://arxiv.org/abs/2303.17021


This review aims at providing an extensive discussion of modern constraints relevant for dense and hot strongly interacting matter. It includes theoretical first-principle results from lattice and perturbative QCD, as well as chiral effective field theory results. From the experimental side, it includes heavy-ion collision and low-energy nuclear physics results, as well as observations from neutron stars and their mergers. The validity of different constraints, concerning specific conditions and ranges of applicability, is also provided.

Read this paper on arXiv…

R. Kumar, V. Dexheimer, J. Jahan, et. al.
Fri, 31 Mar 23
20/70

Comments: N/A

A Deep Learning Approach to Extracting Nuclear Matter Properties from Neutron Star Observations [CL]

Posted on by

http://arxiv.org/abs/2303.17146


Understanding the equation of state of dense QCD matter remains a major challenge in both nuclear physics and astrophysics. Neutron star observations from electromagnetic and gravitational wave spectra provide critical insights into the behavior of dense neutron-rich matter. The next generation of telescopes and gravitational wave observatories will offer even more detailed observations of neutron stars. Utilizing deep learning techniques to map neutron star mass and radius observations to the equation of state allows for its accurate and reliable determination. This work demonstrates the feasibility of using deep learning to extract the equation of state directly from neutron star observational data, and to also obtain related nuclear matter properties such as the slope, curvature, and skewness of the nuclear symmetry energy at saturation density. Most importantly, we show that this deep learning approach is able to reconstruct \textit{realistic} equations of state, and deduce \textit{realistic} nuclear matter properties. This highlights the potential of artificial neural networks in providing a reliable and efficient means to extract crucial information about the equation of state and related properties of dense neutron-rich matter in the era of multi-messenger astrophysics.

Read this paper on arXiv…

P. Krastev
Fri, 31 Mar 23
40/70

Comments: 22 pages, 12 figures, 4 tables. Invited article for Symmetry for the Special Issue “Symmetries and Ultra Dense Matter of Compact Stars”

Cross Sections of the $^{83}$Rb(p,$γ)^{84}$Sr and $^{84}$Kr(p,$γ)^{85}$Rb Reactions at Energies Characteristic of the Astrophysical $γ$ Process [CL]

Posted on by

http://arxiv.org/abs/2303.10282


We have measured the cross section of the $^{83}$Rb(p,$\gamma)^{84}$Sr radiative capture reaction in inverse kinematics using a radioactive beam of $^{83}$Rb at incident energies of 2.4 and $2.7 A$ MeV. Prior to the radioactive beam measurement, the $^{84}$Kr(p,$\gamma)^{85}$Rb radiative capture reaction was measured in inverse kinematics using a stable beam of $^{84}$Kr at an incident energy of $2.7 A$ MeV. The effective relative kinetic energies of these measurements lie within the relevant energy window for the $\gamma$ process in supernovae. The central values of the measured partial cross sections of both reactions were found to be $0.17-0.42$ times the predictions of statistical model calculations. Assuming the predicted cross section at other energies is reduced by the same factor leads to a slightly higher calculated abundance of the $p$ nucleus $^{84}$Sr, caused by the reduced rate of the $^{84}$Sr($\gamma$,p)$^{83}$Rb reaction derived from the present measurement.

Read this paper on arXiv…

M. Williams, B. Davids, G. Lotay, et. al.
Tue, 21 Mar 23
61/68

Comments: 11 pages, 11 figures. arXiv admin note: text overlap with arXiv:2109.06775

Performance of an ultra-pure NaI(Tl) detector produced by an indigenously-developed purification method and crystal growth for the COSINE-200 experiment [CL]

Posted on by

http://arxiv.org/abs/2301.04884


The COSINE-100 experiment has been operating with 106 kg of low-background NaI(Tl) detectors to test the results from the DAMA/LIBRA experiment, which claims to have observed dark matter. However, since the background of the NaI(Tl) crystals used in the COSINE-100 experiment is 2-3 times higher than that in the DAMA detectors, no conclusion regarding the claimed observation from the DAMA/LIBRA experiment could be reached. Therefore, we plan to upgrade the current COSINE-100 experiment to the next phase, COSINE-200, by using ultra-low background NaI(Tl) detectors. The basic principle was already proved with the commercially available Astro-grade NaI powder from Sigma-Aldrich company. However, we have developed a mass production process of ultra-pure NaI powder at the Center for Underground Physics (CUP) of the Institute for Basic Science (IBS), Korea, using the direct purification of the raw NaI powder. We plan to produce more than 1,000 kg of ultra-pure powder for the COSINE200 experiment. With our crystal grower installed at CUP, we have successfully grown a low-background crystal using our purification technique for the NaI powder. We have assembled a low-background NaI(Tl) detector. In this article, we report the performance of this ultra-pure NaI(Tl) crystal detector produced at IBS, Korea.

Read this paper on arXiv…

H. Lee, B. Park, J. Choi, et. al.
Fri, 13 Jan 23
52/72

Comments: N/A

Relativistic approach to the nuclear breathing mode [CL]

Posted on by

http://arxiv.org/abs/2212.14766


Microscopic theory of the nuclear response based on the relativistic meson-nucleon Lagrangian is applied to the description of the isoscalar giant monopole resonance (ISGMR) in a variety of nuclear systems. It is shown that the inclusion of beyond-mean-field correlations of the quasiparticle-vibration coupling (qPVC) type in the leading approximation allows for a simultaneous realistic description of the ISGMR in nuclei of led, tin and nickel mass regions, which is difficult on the mean-field level. The calculations are based on the NL3* parametrization of the relativistic finite-range meson-nucleon Lagrangian, which, in combination with the qPVC, have consistently demonstrated the ability to reliably describe many other nuclear structure phenomena. Systematic ISGMR calculations for nickel isotopes help reveal the central role of its coupling to the low-energy quadrupole states in the placement of the ISGMR centroids.

Read this paper on arXiv…

E. Litvinova
Mon, 2 Jan 23
4/44

Comments: N/A

MFV approach to robust estimate of neutron lifetime [CL]

Posted on by

http://arxiv.org/abs/2212.05890


Aiming at evaluating the lifetime of the neutron, we introduce a novel statistical method to analyse the updated compilation of precise measurements including the 2022 dataset of Particle Data Group (PDG). Based on the minimization for the information loss principle, unlike the median statistics method, we apply the most frequent value (MFV) procedure to estimate the neutron lifetime, irrespective of the Gaussian or non-Gaussian distributions. Providing a more robust way, the calculated result of the MFV is $\tau_n=881.16^{+2.25}{-2.35}$ s with statistical bootstrap errors, while the result of median statistics is $\tau_n=881.5^{+5.5}{-3}$ s according to the binomial distribution. Using the different central estimates, we also construct the error distributions of neutron lifetime measurements and find the non-Gaussianity, which is still meaningful.

Read this paper on arXiv…

J. Zhang, S. Zhang, Z. Zhang, et. al.
Tue, 13 Dec 22
14/105

Comments: N/A

Alpha decay of thermally excited nuclei [CL]

Posted on by

http://arxiv.org/abs/2212.03983


One of the prominent decay modes of heavy nuclei which are produced in astrophysical environments at temperatures of the order of $10^9$ K is the $\alpha$ ($^4$He) decay. Thermally enhanced $\alpha$ decay rates are evaluated within the standard scheme of a tunneling decay where the $\alpha$ particle tunnels through the potential barrier formed by its interaction with the daughter nucleus. Following the observation that there exist several excited levels with the possibility of an $\alpha$ decay when the daughter nucleus is at a shell closure, we focus in particular on decays producing daughter nuclei with the neutron number, N = 126. Within a statistical approach we find that the half-lives, $t_{1/2}(T)$, for temperatures ranging from $T$ = 0 to 2.4 GK can decrease by 1 – 2 orders of magnitude with the exception of the decay of $^{212}$Po which decays to the doubly magic daughter $^{208}$Pb, where $t_{1/2}(T)$ decreases by 5 orders of magnitude. The effect of these thermally enhanced $\alpha$ decays on the $r$-process nucleosynthesis can be significant in view of the mass build up at the waiting point nuclei with closed neutron shells.

Read this paper on arXiv…

J. Velasquez, O. Caballero and N. Kelkar
Fri, 9 Dec 22
34/75

Comments: 18 pages, 1 figure

Understanding globular cluster abundances through nuclear reactions [CL]

Posted on by

http://arxiv.org/abs/2212.03648


Globular clusters contain multiple stellar populations, with some previous generation of stars polluting the current stars with heavier elements. Understanding the history of globular clusters is helpful in understanding how galaxies merged and evolved and therefore constraining the site or sites of this historic pollution is a priority. The acceptable temperature and density conditions of these polluting sites depend on critical reaction rates. In this paper, three experimental studies helping to constrain astrophysically important reaction rates are briefly discussed.

Read this paper on arXiv…

P. Adsley, M. Williams, D. Harrouz, et. al.
Thu, 8 Dec 22
23/63

Comments: Submission to conference proceedings of INPC2022 in Cape Town

Measurement of the $^{159}$Tb(n, $γ$) cross section at the CSNS Back-n facility [CL]

Posted on by

http://arxiv.org/abs/2212.01820


The stellar (n, $\gamma$) cross section data for the mass numbers around A $\approx$ 160 are of key importance to nucleosynthesis in the main component of the slow neutron capture process, which occur in the thermally pulsing asymptotic giant branch (TP–AGB). The new measurement of (n, $\gamma$) cross sections for $^{159}$Tb was performed using the C$_6$D$_6$ detector system at the back streaming white neutron beam line (Back-n) of the China spallation neutron source (CSNS) with neutron energies ranging from 1 eV to 1 MeV. Experimental resonance capture kernels were reported up to 1.2 keV neutron energy with this capture measurement. Maxwellian-averaged cross sections (MACS) were derived from the measured $^{159}$Tb (n, $\gamma$) cross sections at $kT$ = 5 $\sim$ 100 keV and are in good agreement with the recommended data of KADoNiS-v0.3 and JEFF-3.3, while KADoNiS-v1.0 and ENDF-VIII.0 significantly overestimate the present MACS up to 40$\%$ and 20$\%$, respectively. A sensitive test of the s-process nucleosynthesis was also performed with the stellar evolution code MESA. Significant changes in abundances around A $\approx$ 160 were observed between the ENDF/B-VIII.0 and present measured rate of $^{159}$Tb(n, $\gamma$)$^{160}$Tb in the MESA simulation.

Read this paper on arXiv…

S. Zhang, G. Li, W. Jiang, et. al.
Tue, 6 Dec 22
4/87

Comments: 13 pages, 7 figures

Progress in Nuclear Astrophysics: a multi-disciplinary field with still many open questions [CL]

Posted on by

http://arxiv.org/abs/2212.02156


Nuclear astrophysics is a multi-disciplinary field with a huge demand for nuclear data. Among its various fields, stellar evolution and nucleosynthesis are clearly the most closely related to nuclear physics. The need for nuclear data for astrophysics applications challenges experimental techniques as well as the robustness and predictive power of present nuclear models. Despite impressive progress for the last years, major problems and puzzles remain. In the present contribution, only a few nuclear astrophysics specific aspects are discussed. These concern some experimental progress related to the measurement of key reactions of relevance for the so-called s-and p-processes of nucleosynthesis, the theoretical effort in predicting nuclear properties of exotic neutron-rich nuclei of interest for the r-process nucleosynthesis, and the recent introduction of machine learning techniques in nuclear astrophysics applications.

Read this paper on arXiv…

S. Goriely, A. Choplin, W. Ryssens, et. al.
Tue, 6 Dec 22
80/87

Comments: 8 pages, 4 figures; Contribution to the proceedings of INPC 2022, Cape Town, South Africa

Multi-Petawatt Physics Prioritization (MP3) Workshop Report [CL]

Posted on by

http://arxiv.org/abs/2211.13187


This Multi-Petawatt Physics Prioritization (MP3) Workshop Report captures the outcomes from a community-initiated workshop held April 20-22, 2022 at Sorbonne University in Paris, France. The MP3 workshop aimed at developing science questions to guide research and future experiments in four areas identified by corresponding MP3 working groups: high-field physics and quantum electrodynamics (HFP/QED), laboratory astrophysics and planetary physics (LAPP), laser-driven nuclear physics (LDNP), and particle acceleration and advanced light sources (PAALS).

Read this paper on arXiv…

A. Piazza, L. Willingale and J. Zuegel
Thu, 24 Nov 22
17/71

Comments: 113 pages

Probing the size and binding energy of the hypertriton in heavy ion collisions [CL]

Posted on by

http://arxiv.org/abs/2211.12643


The hypertriton is predicted to have a small binding energy (a weighted average of about 170 keV), consistent with a large matter radius (~ 10 fm), large than the historical11Li halo discovered more than 35 years ago. But the reported experimental values of the binding energy of the hypertriton range from 50 to 500 keV. In this work I discuss the electromagnetic response and interaction radius of the hypertriton and how high energy heavy ion collisions (~ 1 – 2 GeV/nucleon) can help achieving a higher accuracy for the determination of its size and binding energy.

Read this paper on arXiv…

C. Bertulani
Thu, 24 Nov 22
44/71

Comments: 8 pages, 9 figures

Probing the size and binding energy of the hypertriton in heavy ion collisions [CL]

Posted on by

http://arxiv.org/abs/2211.12643


The hypertriton is predicted to have a small binding energy (a weighted average of about 170 keV), consistent with a large matter radius (~ 10 fm), large than the historical11Li halo discovered more than 35 years ago. But the reported experimental values of the binding energy of the hypertriton range from 50 to 500 keV. In this work I discuss the electromagnetic response and interaction radius of the hypertriton and how high energy heavy ion collisions (~ 1 – 2 GeV/nucleon) can help achieving a higher accuracy for the determination of its size and binding energy.

Read this paper on arXiv…

C. Bertulani
Thu, 24 Nov 22
20/71

Comments: 8 pages, 9 figures

Multi-Petawatt Physics Prioritization (MP3) Workshop Report [CL]

Posted on by

http://arxiv.org/abs/2211.13187


This Multi-Petawatt Physics Prioritization (MP3) Workshop Report captures the outcomes from a community-initiated workshop held April 20-22, 2022 at Sorbonne University in Paris, France. The MP3 workshop aimed at developing science questions to guide research and future experiments in four areas identified by corresponding MP3 working groups: high-field physics and quantum electrodynamics (HFP/QED), laboratory astrophysics and planetary physics (LAPP), laser-driven nuclear physics (LDNP), and particle acceleration and advanced light sources (PAALS).

Read this paper on arXiv…

A. Piazza, L. Willingale and J. Zuegel
Thu, 24 Nov 22
45/71

Comments: 113 pages

A Review of NEST Models, and Their Application to Improvement of Particle Identification in Liquid Xenon Experiments [CL]

Posted on by

http://arxiv.org/abs/2211.10726


Liquid xenon is a leader in rare-event physics searches. Accurate modeling of charge and light production is key for simulating signals and backgrounds in this medium. The signal- and background-production models in the Noble Element Simulation Technique (NEST) are presented. NEST is a simulation toolkit based on experimental data, fit using simple, empirical formulae for the average charge and light yields and their variations. NEST also simulates the final scintillation pulses and exhibits the correct energy resolution as a function of the particle type, the energy, and the electric fields. After vetting of NEST against raw data, with several specific examples pulled from XENON, ZEPLIN, LUX/LZ, and PandaX, we interpolate and extrapolate its models to draw new conclusions on the properties of future detectors (e.g., XLZD’s), in terms of the best possible discrimination of electron(ic) recoil backgrounds from a potential nuclear recoil signal, especially WIMP dark matter. We discover that the oft-quoted value of 99.5% discrimination is overly conservative, demonstrating that another order of magnitude improvement (99.95% discrimination) can be achieved with a high photon detection efficiency (g1 ~ 15-20%) at reasonably achievable drift fields of 200-350 V/cm.

Read this paper on arXiv…

M. Szydagis, J. Balajthy, G. Block, et. al.
Tue, 22 Nov 22
48/83

Comments: 24 Pages, 6 Tables, 15 Figures, and 15 Equations

Isotopic dependence of $(n,α)$ reaction cross sections for Fe and Sn nuclei [CL]

Posted on by

http://arxiv.org/abs/2211.09411


The $(n,\alpha)$ reactions play an important role for the energy generation and the synthesis of chemical elements in the stars, as well as for nuclear engineering and medical applications. The aim of this study is to explore the evolution of $(n,\alpha)$ reactions in Fe and Sn isotope chains in order to assess their properties with the increase of neutrons in target nucleus, and compare with other relevant neutron induced reactions. Model calculations of the cross sections are based on the statistical Hauser-Feshbach model in TALYS implementation, using global optical model potential that is additionally adjusted by the $(n,\alpha)$ cross section data for $^{54}$Fe and $^{118}$Sn. The calculations of $(n,\alpha)$ reactions in Fe and Sn isotopes provide the insight into their isospin dependence and properties over the complete relevant range of neutron energies. The results show the evolution of the cross sections with pronounced maxima at low-mass isotopes, and rather strong decrease for neutron-rich nuclei consistent with the reduction of the reaction $Q$-value and increased contributions from other exit channels from compound nucleus. The analysis of the Maxwellian averaged cross sections at temperatures in stellar environment shows that while the $(n,\alpha)$ reactions contribute for the low-mass isotopes, in neutron induced reactions with nuclei with neutron excess, $\gamma$ and neutron emission dominate.

Read this paper on arXiv…

S. Kucuksucu, M. Yigit and N. Paar
Fri, 18 Nov 22
19/70

Comments: 12 pages, 12 figures

Snowmass Neutrino Frontier Report [CL]

Posted on by

http://arxiv.org/abs/2211.08641


This report summarizes the current status of neutrino physics and the broad and exciting future prospects identified for the Neutrino Frontier as part of the 2021 Snowmass Process.

Read this paper on arXiv…

P. Huber, K. Scholberg, E. Worcester, et. al.
Thu, 17 Nov 22
61/63

Comments: 49 pages, contribution to: 2021 Snowmass Summer Study

Direct dark matter searches with the full data set of XMASS-I [CEA]

Posted on by

http://arxiv.org/abs/2211.06204


Various WIMP dark matter searches using the full data set of XMASS-I, a single-phase liquid xenon detector, are reported in this paper. Stable XMASS-I data taking accumulated a total live time of 1590.9 days between November 20, 2013 and February 1, 2019 with an analysis threshold of ${\rm 1.0\,keV_{ee}}$. In the latter half of data taking a lower analysis threshold of ${\rm 0.5\,keV_{ee}}$ was also available through a new low threshold trigger. Searching for a WIMP signal in the detector’s 97~kg fiducial volume yielded a limit on the WIMP-nucleon scattering cross section of ${\rm 1.4\times 10^{-44}\, cm^{2}}$ for a ${\rm 60\,GeV/c^{2}}$ WIMP at the 90$\%$ confidence level. We also searched for WIMP induced annual modulation signatures in the detector’s whole target volume, containing 832~kg of liquid xenon. For nuclear recoils of a ${\rm 8\,GeV/c^{2}}$ WIMP this analysis yielded a 90\% CL cross section limit of ${\rm 2.3\times 10^{-42}\, cm^{2}}$. At a WIMP mass of ${\rm 0.5\, GeV/c^{2}}$ the Migdal effect and Bremsstrahlung signatures were evaluated and lead to 90\% CL cross section limits of ${\rm 1.4\times 10^{-35}\, cm^{2}}$ and ${\rm 1.1\times 10^{-33}\, cm^{2}}$ respectively.

Read this paper on arXiv…

X. Collaboration, K. Abe, K. Hiraide, et. al.
Mon, 14 Nov 22
29/69

Comments: N/A

Testing the phase transition parameters inside neutron stars with the production of protons and lambdas in relativistic heavy-ion collisions [CL]

Posted on by

http://arxiv.org/abs/2211.04978


We demonstrate the consistency of the quark deconfinement phase transition parameters in the beta-stable neutron star matter and in the nearly symmetric nuclear matter formed in heavy-ion collisions (HICs). We investigate the proton and $\Lambda$ flow in Au+Au collisions at 3 and 4.5 GeV/nucleon incident beam energies with the pure hadron cascade version of a multi-phase transport model. The phase transition in HICs and neutron stars is described based on a class of hybrid equations of state from the quark mean-field model for the hadronic phase and a constant-speed-of-sound parametrization for the high-density quark phase. The measurements of the anisotropic proton flow at 3 GeV/nucleon by the STAR collaboration favor a relatively low phase transition density lower than $\sim 2.5$ times saturation density indicated by the gravitational wave and electromagnetic observations of neutron stars. And the proton flow data at the higher energy of 4.5 GeV/nucleon can be used to effectively constrain the softness of high-density quark matter equations of state. Finally, compared to the proton flow, the $\Lambda$ flow is found to be less sensitive and not constraining to the equations of state.

Read this paper on arXiv…

A. Li, G. Yong and Y. Zhang
Thu, 10 Nov 22
23/78

Comments: 7 pages, 7 figures

PANDORA project: photo-nuclear reactions below $A=60$ [CL]

Posted on by

http://arxiv.org/abs/2211.03986


Photo-nuclear reactions of light nuclei below a mass of $A=60$ are studied experimentally and theoretically by the PANDORA (Photo-Absorption of Nuclei and Decay Observation for Reactions in Astrophysics) project. Two experimental methods, virtual-photon excitation by proton scattering and real-photo absorption by a high-brilliance gamma-ray beam produced by laser Compton scattering, will be applied to measure the photo-absorption cross sections and the decay branching ratio of each decay channel as a function of the photon energy. Several nuclear models, {\em e.g.} anti-symmetrized molecular dynamics, mean-field type models, a large-scale shell model, and {\em ab initio} models, will be employed to predict the photo-nuclear reactions. The uncertainty in the model predictions will be evaluated from the discrepancies between the model predictions and the experimental data. The data and the predictions will be implemented in a general reaction calculation code \talys . The results will be applied to the simulation of the photo-disintegration process of ultra-high-energy cosmic rays in inter-galactic propagation.

Read this paper on arXiv…

A. Tamii, L. Pellegri, P. Söderström, et. al.
Wed, 9 Nov 22
33/76

Comments: N/A

Understanding the cosmic abundance of $^{22}$Na: lifetime measurements in $^{23}$Mg [CL]

Posted on by

http://arxiv.org/abs/2210.14336


Simulations of explosive nucleosynthesis in novae predict the production of $^{22}$Na, a key astronomical observable to constrain nova models. Its gamma-ray line at 1.275 MeV has not yet been observed by the gamma-ray space telescopes. The $^{20}$Ne/$^{22}$Ne ratio in presolar grains, a possible tool to identify nova grains, also depends on $^{22}$Na produced. Uncertainties on its yield in classical novae currently originate from the rate of the $^{22}$Na(p, $\gamma$)$^{23}$Mg reaction. At peak novae temperatures, this reaction is dominated by a resonance at E${\text{R}}$=0.204 MeV, corresponding to the $E_x$=7.785 MeV excited state in $^{23}$Mg. The resonance strengths measured so far disagree by one order of magnitude. An experiment has been performed at GANIL to measure the lifetime and the proton branching ratio of this key state, with a femtosecond resolution for the former. The reactions populating states in $^{23}$Mg have been studied with a high resolution detection set-up, i.e. the particle VAMOS, SPIDER and gamma tracking AGATA spectrometers, allowing the measurements of lifetimes and proton branchings. We present here a comparison between experimental results and shell-model calculations, that allowed us to assign the spin and parity of the key state. Rather small values obtained for reduced $M1$ matrix elements, $|M(M1)|\lesssim 0.5$ $\mu_N$, and proton spectroscopic factors, $C^{2}S{\text{p}}$<10$^{-2}$, seem to be beyond the accuracy of the shell model. With the reevaluated $^{22}$Na(p, $\gamma$)$^{23}$Mg rate, the $^{22}$Na detectability limit and its observation frequency from novae are found promising for the future space telescopes.

Read this paper on arXiv…

C. Fougères, F. Santos, N. Smirnova, et. al.
Thu, 27 Oct 22
34/55

Comments: 6 pages, 4 figures, proceedings of the conference Nuclear Physics in Astrophysics – X (NPA-X, Cern 2022), submitted in EPJ Web of Conferences

Bayesian Estimation of the $S$ Factor and Thermonuclear Reaction Rate for $^{16}$O(p,$γ$)$^{17}$F [CL]

Posted on by

http://arxiv.org/abs/2210.14354


The $^{16}$O(p,$\gamma$)$^{17}$F reaction is the slowest hydrogen-burning process in the CNO mass region. Its thermonuclear rate sensitively impacts predictions of oxygen isotopic ratios in a number of astrophysical sites, including AGB stars. The reaction has been measured several times at low bombarding energies using a variety of techniques. The most recent evaluated experimental rates have a reported uncertainty of about 7.5\% below $1$~GK. However, the previous rate estimate represents a best guess only and was not based on rigorous statistical methods. We apply a Bayesian model to fit all reliable $^{16}$O(p,$\gamma$)$^{17}$F cross section data, and take into account independent contributions of statistical and systematic uncertainties. The nuclear reaction model employed is a single-particle potential model involving a Woods-Saxon potential for generating the radial bound state wave function. The model has three physical parameters, the radius and diffuseness of the Woods-Saxon potential, and the asymptotic normalization coefficients (ANCs) of the final bound state in $^{17}$F. We find that performing the Bayesian $S$ factor fit using ANCs as scaling parameters has a distinct advantage over adopting spectroscopic factors instead. Based on these results, we present the first statistically rigorous estimation of experimental $^{16}$O(p,$\gamma$)$^{17}$F reaction rates, with uncertainties ($\pm 4.2$\%) of about half the previously reported values.

Read this paper on arXiv…

C. Iliadis, V. Palanivelrajan and R. Souza
Thu, 27 Oct 22
47/55

Comments: 3 figures

The DAMIC-M Experiment: Status and First Results [CL]

Posted on by

http://arxiv.org/abs/2210.12070


The DAMIC-M (DArk Matter In CCDs at Modane) experiment employs thick, fully depleted silicon charged-coupled devices (CCDs) to search for dark matter particles with a target exposure of 1 kg-year. A novel skipper readout implemented in the CCDs provides single electron resolution through multiple non-destructive measurements of the individual pixel charge, pushing the detection threshold to the eV-scale. DAMIC-M will advance by several orders of magnitude the exploration of the dark matter particle hypothesis, in particular of candidates pertaining to the so-called “hidden sector.” A prototype, the Low Background Chamber (LBC), with 20g of low background Skipper CCDs, has been recently installed at Laboratoire Souterrain de Modane and is currently taking data. We will report the status of the DAMIC-M experiment and first results obtained with LBC commissioning data.

Read this paper on arXiv…

I. Arnquist, N. Avalos, P. Bailly, et. al.
Mon, 24 Oct 22
12/56

Comments: 8 pages, 6 figures, Submission to SciPost Physics Proceedings: 14th International Conference on Identification of Dark Matter (IDM) 2022

Spatial Structure of the $^{12}$C Nucleus in a 3$α$ Model with Deep Potentials Containing Forbidden States [CL]

Posted on by

http://arxiv.org/abs/2210.11763


The spatial structure of the lowest 0$_1^+$, 0$_2^+$, 2$_1^+$ and 2$_2^+$ states of the $^{12}$C nucleus is studied within the 3$\alpha$ model with the Buck, Friedrich, and Wheatley $\alpha \alpha$ potential with Pauli forbidden states in the $S$ and $D$ waves. The Pauli forbidden states in the three-body system are treated by the exact orthogonalization method. The largest contributions to the ground and excited 2$_1^+$ bound states energies come from the partial waves $(\lambda, \ell)=(2,2)$ and $(\lambda, \ell)=(4,4)$. In contrast to the bound states, for the Hoyle resonance 0$_2^+$ and its analog state 2$_2^+$, dominant contributions come from the $(\lambda, \ell)=(0,0)$ and $(\lambda, \ell)=(2,2)$ configurations, respectively. The estimated probability density functions for the $^{12}$C(0$_1^+$) ground and 2$_1^+$ excited bound states show mostly a triangular structure, where the $\alpha$ particles move at a distance of about 2.5 fm from each other. However, the spatial structure of the Hoyle resonance and its analog state have a strongly different structure, like $^8$Be + $\alpha$. In the Hoyle state, the last $\alpha$ particle moves far from the doublet at the distance between $R=3.0$ fm and $R=5.0$ fm. In the Hoyle analog 2$_2^+$ state the two alpha particles move at a distance of about 15 fm, but the last $\alpha$ particle can move far from the doublet at the distance up to $R=30.0$ fm.

Read this paper on arXiv…

E. Tursunov, M. Saidov and M. Begijonov
Mon, 24 Oct 22
32/56

Comments: 12 pages, 4 figures, 2 tables

Nuclear Equation of State and Single-nucleon Potential from Gogny-like Energy Density Functionals Encapsulating Effects of Nucleon-nucleon Short-range Correlations [CL]

Posted on by

http://arxiv.org/abs/2210.10924


Nucleon-nucleon short-range correlations (SRCs) induce a high momentum tail (HMT) in the single-nucleon momentum distribution function $n_{\v{k}}^J(\rho,\delta)$ in cold neutron-rich matter. While there are clear experimental evidences that the SRC/HMT effects are different for neutrons and protons and their strengths depend strongly on the isospin asymmetry of finite nuclei mostly based on electron-nucleus scattering experiments, much less is known experimentally about the SRC/HMT effects in the dense neutron-rich matter. To facilitate further explorations of SRC/HMT effects in dense neutron-rich matter especially with heavy-ion reactions involving high-energy radioactive beams as well as multimessenger observations of neutron stars and their mergers, by incorporating the SRC-induced HMT in $n_{\v{k}}^J(\rho,\delta)$ into a Gogny-like energy density functional we study SRC/HMT effects on the equation of state (EOS) especially its symmetry energy term and single-nucleon potential in the dense asymmetric nucleonic matter (ANM). Using a parametrization as a surrogate for the momentum-dependent kernel in the Gogny-like energy density functional (EDF) we derive analytical expressions for all components of the ANM EOS and their characteristics (e.g., magnitude, slope and curvature as well as nucleon effective mass) at saturation density $\rho_0$ as well as the momentum-dependent single-nucleon optical potential in neutron-rich matter using parameters characterizing nuclear interactions as well as the size, shape and isospin dependence of the HMT at $\rho_0$. Some consequences of the SRC/HMT effects on properties of neutron stars are also studied.

Read this paper on arXiv…

B. Cai and B. Li
Fri, 21 Oct 22
73/76

Comments: 35 pages including 16 figures

pynucastro: A Python Library for Nuclear Astrophysics [IMA]

Posted on by

http://arxiv.org/abs/2210.09965


We describe pynucastro 2.0, an open source library for interactively creating and exploring astrophysical nuclear reaction networks. We demonstrate new methods for approximating rates and using detailed balance to create reverse rates, show how to build networks and determine whether they are appropriate for a particular science application, and discuss the changes made to the library over the past few years. Finally, we demonstrate the validity of the networks produced and share how we use pynucastro networks in simulation codes.

Read this paper on arXiv…

A. Clark, E. Johnson, Z. Chen, et. al.
Wed, 19 Oct 22
56/87

Comments: Submitted to Astrophysical Journal notebooks to reproduce all figures are available via Zenodo DOI: this https URL

Model Independent Approach of the JUNO $^8$B Solar Neutrino Program [CL]

Posted on by

http://arxiv.org/abs/2210.08437


The physics potential of detecting $^8$B solar neutrinos is exploited at the Jiangmen Underground Neutrino Observatory (JUNO), in a model independent manner by using three distinct channels of the charged-current (CC), neutral-current (NC) and elastic scattering (ES) interactions. Due to the largest-ever mass of $^{13}$C nuclei in the liquid-scintillator detectors and the potential low background level, $^8$B solar neutrinos would be observable in the CC and NC interactions on $^{13}$C for the first time. By virtue of optimized event selections and muon veto strategies, backgrounds from the accidental coincidence, muon-induced isotopes, and external backgrounds can be greatly suppressed. Excellent signal-to-background ratios can be achieved in the CC, NC and ES channels to guarantee the $^8$B solar neutrino observation. From the sensitivity studies performed in this work, we show that one can reach the precision levels of 5%, 8% and 20% for the $^8$B neutrino flux, $\sin^2\theta_{12}$, and $\Delta m^2_{21}$, respectively, using ten years of JUNO data. It would be unique and helpful to probe the details of both solar physics and neutrino physics. In addition, when combined with SNO, the world-best precision of 3% is expected for the $^8$B neutrino flux measurement.

Read this paper on arXiv…

J. Collaboration, J. Zhao, B. Yue, et. al.
Tue, 18 Oct 22
7/99

Comments: 24 pages, 7 figures

Estimation of the number of counts on a particle counter detector with full time resolution [CL]

Posted on by

http://arxiv.org/abs/2210.09005


We present a general method for estimating the number of particles impinging on a segmented counter or, in general, on a counter with sub-units. We account for unresolved particles, i.e., the effect of two or more particles hitting the same sub-unit almost simultaneously. To achieve full time resolution we account for the dead time that occurs after the first time-bin of a particle signal. This general counting method can be applied to counting muons in existing detectors like the Underground Muon Detector of the Pierre Auger Observatory. We therefore use the latter as a study case to test the performance of our method and to compare it to other methods from literature. Our method proves to perform with little bias, and also provides an estimate of the number of particles as a function of time (as seen by the detector) to a single time-bin resolution. In this context, the new method can be useful for reconstructing parameters sensitive to cosmic ray mass, which are key to unveiling the origin of cosmic rays.

Read this paper on arXiv…

F. Gesualdi and A. Supanitsky
Tue, 18 Oct 22
45/99

Comments: Accepted for publication in EPJ C

Supernova Neutrinos as a Precise Probe of Nuclear Neutron Skin [CL]

Posted on by

http://arxiv.org/abs/2210.04534


A precise and model-independent determination of the neutron distribution radius $R_{\rm n}$ and thus the neutron skin thickness $R_{\rm skin}$ of atomic nuclei is of fundamental importance in nuclear physics, particle physics and astrophysics but remains a big challenge in terrestrial labs. We argue that the nearby core-collapse supernova (CCSN) in our Galaxy may render a neutrino flux with unprecedentedly high luminosity, offering perfect opportunity to determine the $R_{\rm n}$ and $R_{\rm skin}$ through the coherent elastic neutrino-nucleus scattering (CE$\nu$NS). We evaluate the potential of determining the $R_{\rm n}$ of lead (Pb) via CE$\nu$NS with the nearby CCSN neutrinos in the RES-NOVA project which is designed to hunt CCSN neutrinos using an array of archaeological Pb based cryogenic detectors. We find that an ultimate precision of $\sim 0.1 \%$ for the $R_{\rm n}$ ($\sim 0.006$ fm for the $R_{\rm skin}$) of Pb can be achieved via RES-NOVA if the CCSN explosion were to occur at a distance of $\sim 1$ kpc from the Earth.

Read this paper on arXiv…

X. Huang and L. Chen
Tue, 11 Oct 22
74/92

Comments: 6 pages, 3 figures, 1 table

X-ray performance of a customized large-format scientifc CMOS detector [IMA]

Posted on by

http://arxiv.org/abs/2209.15295


In recent years, the performance of Scientifc Complementary Metal Oxide Semiconductor (sCMOS) sensors has been improved signifcantly. Compared with CCD sensors, sCMOS sensors have various advantages, making them potentially better devices for optical and X-ray detection, especially in time-domain astronomy. After a series of tests of sCMOS sensors, we proposed a new dedicated high-speed, large-format X-ray detector in 2016 cooperating with Gpixel Inc. This new sCMOS sensor has a physical size of 6 cm by 6 cm, with an array of 4096 by 4096 pixels and a pixel size of 15 um. The frame rate is 20.1 fps under current condition and can be boosted to a maximum value around 100 fps. The epitaxial thickness is increased to 10 um compared to the previous sCMOS product. We show the results of its frst taped-out product in this work. The dark current of this sCMOS is lower than 10 e/pixel/s at 20C, and lower than 0.02 e/pixel/s at -30C. The Fixed Pattern Noise (FPN) and the readout noise are lower than 5 e in high-gain situation and show a small increase at low temperature. The energy resolution reaches 180.1 eV (3.1%) at 5.90 keV for single-pixel events and 212.3 eV (3.6%) for all split events. The continuous X-ray spectrum measurement shows that this sensor is able to response to X-ray photons from 500 eV to 37 keV. The excellent performance, as demonstrated from these test results, makes sCMOS sensor an ideal detector for X-ray imaging and spectroscopic application.

Read this paper on arXiv…

Q. Wu, Z. Jia, W. Wang, et. al.
Mon, 3 Oct 22
43/55

Comments: 20 pages. published in PASP

The Nuclear Physics of Neutron Stars [CL]

Posted on by

http://arxiv.org/abs/2209.14877


Neutron stars — compact objects with masses similar to that of our Sun but radii comparable to the size of a city — contain the densest form of matter in the universe that can be probed in terrestrial laboratories as well as in earth- and space-based observatories. The historical detection of gravitational waves from a binary neutron star merger has opened the brand new era of multimessenger astronomy and has propelled neutron stars to the center of a variety of disciplines, such as astrophysics, general relativity, nuclear physics, and particle physics. The main input required to study the structure of neutron stars is the pressure support generated by its constituents against gravitational collapse. These include neutrons, protons, electrons, and perhaps even more exotic constituents. As such, nuclear physics plays a prominent role in elucidating the fascinating structure, dynamics, and composition of neutron stars.

Read this paper on arXiv…

J. Piekarewicz
Fri, 30 Sep 22
65/71

Comments: 15 pages, 6 figures, submitted to Oxford Research Encyclopedia of Physics

Design and test results of scientific X-ray CMOS cameras [IMA]

Posted on by

http://arxiv.org/abs/2209.13163


In recent years, scientific CMOS (sCMOS) sensors have found increasing applications to X-ray detection, including X-ray astronomical observations. In order to examine the performance of sCMOS sensors, we have developed X-ray cameras based on sCMOS sensors. Two cameras, CNX22 and CNX 66, have been developed using sCMOS sensors with a photosensitive area of 2 cm * 2 cm and 6 cm * 6 cm, respectively. The designs of the cameras are presented in this paper. The CNX22 camera has a frame rate of 48 fps, whereas CNX66 has a frame rate of currently 20 fps, that can be boosted to 100 fps in the future. The operating temperature of the sCMOS sensor can reach to -20C for CNX22 and -30C for CNX66 with a peltier cooler device. In addition to the commonly used mode of saving original images, the cameras provide a mode of real-time extraction of X-ray events and storage their information, which significantly reduces the requirement for data storage and offline analysis work. For both cameras, the energy resolutions can reach less than 200 eV at 5.9 keV using single-pixel events. These cameras are suitable for X-ray spectroscopy applications in laboratories and calibration for the space X-ray telescopes.

Read this paper on arXiv…

W. Wang, Z. Ling, C. Zhang, et. al.
Wed, 28 Sep 22
63/89

Comments: 7 pages, 5 figures, published by Proc SPIE 2022

Measurement of Hadron Production in $π^-$-C Interactions at 158 and 350 GeV/c with NA61/SHINE at the CERN SPS [CL]

Posted on by

http://arxiv.org/abs/2209.10561


We present a measurement of the momentum spectra of $\pi^\pm$, K$^\pm$, p$^\pm$, $\Lambda$, $\bar{\Lambda}$ and K$^{0}_{S}$ produced in interactions of negatively charged pions with carbon nuclei at beam momenta of 158 and 350 GeV/c. The total production cross sections are measured as well. The data were collected with the large-acceptance spectrometer of the fixed target experiment NA61/SHINE at the CERN SPS. The obtained double-differential $p$-$p_T$ spectra provide a unique reference data set with unprecedented precision and large phase-space coverage to tune models used for the simulation of particle production in extensive air showers in which pions are the most numerous projectiles.

Read this paper on arXiv…

N. Collaboration, H. Adhikary, K. Allison, et. al.
Fri, 23 Sep 22
49/70

Comments: N/A

dmscatter: A Fast Program for WIMP-Nucleus Scattering [CL]

Posted on by

http://arxiv.org/abs/2209.09187


Recent work, using an effective field theory framework, has shown the number of possible couplings between nucleons and the dark-matter-candidate Weakly Interacting Massive Particles (WIMPs) is larger than previously thought. Inspired by an existing Mathematica script that computes the target response, we have developed a fast, modern Fortran code, including optional OpenMP parallelization, along with a user-friendly Python wrapper, to swiftly and efficiently explore many scenarios, with output aligned with practices of current dark matter searches. A library of most of the important target nuclides is included; users may also import their own nuclear structure data, in the form of reduced one-body density matrices. The main output is the differential event rate as a function of recoil energy, needed for modeling detector response rates, but intermediate results such as nuclear form factors can be readily accessed.

Read this paper on arXiv…

O. Gorton, C. Johnson, C. Jiao, et. al.
Tue, 20 Sep 22
27/81

Comments: 15 pages, 6 figures, preprint submitted to Computer Physics Communications, code available at this https URL

Snowmass 2021 Cosmic Frontier White Paper: The Dense Matter Equation of State and QCD Phase Transitions [HEAP]

Posted on by

http://arxiv.org/abs/2209.07412


Our limited understanding of the physical properties of matter at ultra-high density, high proton/neutron number asymmetry, and low temperature is presently one of the major outstanding problems in physics. As matter in this extreme state is known to only exist stably in the cores of neutron stars (NSs), complementary measurements from electromagnetic and gravitational wave astrophysical observations of NSs, combined with terrestrial laboratory constraints and further theoretical investigations, hold the promise to provide important insight into the properties of matter in a region of the quantum chromodynamics phase space that is otherwise inaccessible. This multidisciplinary endeavor imposes the following requirements for facilities and resources in the upcoming decade and beyond:
* A next generation of gravitational wave detectors to uncover more double NS and neutron star-black hole mergers;
* Sensitive radio telescopes to find the most massive and fastest spinning NSs;
* Large-area, high-time-resolution and/or high angular resolution X-ray telescopes to constrain the NS mass-radius relation;
* Suitable laboratory facilities for nuclear physics experiments to constrain the dense matter equation of state;
* Funding resources for theoretical studies of matter in this regime;
* The availability of modern large-scale high performance computing infrastructure.
The same facilities and resources would also enable significant advances in other high-profile fields of inquiry in modern physics such as the nature of dark matter, alternative theories of gravity, nucleon superfluidity and superconductivity, as well as an array of astrophysics, including but not limited to stellar evolution, nucleosynthesis, and primordial black holes.

Read this paper on arXiv…

S. Bogdanov, E. Fonseca, R. Kashyap, et. al.
Fri, 16 Sep 22
6/84

Comments: Submitted to the Proceedings of the US Community Study on the Future of Particle Physics (Snowmass 2021) under Cosmic Frontier (CF07: Cosmic probes of fundamental physics); 30 pages, 8 figures

Direct measurement of resonances in $^7$Be($α,γ$)$^{11}$C relevant to $νp$-process nucleosynthesis [CL]

Posted on by

http://arxiv.org/abs/2209.06465


We have performed the first direct measurement of two resonances of the $^7$Be($\alpha,\gamma$)$^{11}$C reaction with unknown strengths using an intense radioactive $^7$Be beam and the DRAGON recoil separator. We report on the first measurement of the 1155 and 1110 keV resonance strengths of $1.73 \pm 0.25(stat.) \pm 0.40(syst.)$ eV and $125 ^{+27}_{-25}(stat.) \pm 15(syst.)$ meV, respectively. The present results have reduced the uncertainty in the $^7$Be($\alpha,\gamma$)$^{11}$C reaction rate to $\sim$ 9.4-10.7% over T = 1.5-3 GK, which is relevant for nucleosynthesis in the neutrino-driven outflows of core-collapse supernovae ($\nu p$-process). We find no effect of the new, constrained reaction rate on $\nu p$-process nucleosynthesis.

Read this paper on arXiv…

A. Psaltis, A. Chen, R. Longland, et. al.
Thu, 15 Sep 22
5/67

Comments: 5 pages, 3 figures. Accepted for publication in Phys. Rev. Lett

First inverse kinematics measurement of resonances in $^7$Be($α,γ$)$^{11}$C relevant to neutrino-driven wind nucleosynthesis using DRAGON [CL]

Posted on by

http://arxiv.org/abs/2209.06472


A possible mechanism to explain the origin of the light $p$-nuclei in the Galaxy is the nucleosynthesis in the proton-rich neutrino-driven wind ejecta of core-collapse supernovae via the $\nu p$-process. However this production scenario is very sensitive to the underlying supernova dynamics and the nuclear physics input. As far as the nuclear uncertainties are concerned, the breakout from the $pp$-chains via the $^7$Be($\alpha,\gamma$)$^{11}$C reaction has been identified as an important link which can influence the nuclear flow and therefore the efficiency of the $\nu p$-process. However its reaction rate is poorly known over the relevant temperature range, T = 1.5-3 GK. We report on the first direct measurement of two resonances of the $^7$Be($\alpha,\gamma$)$^{11}$C reaction with previously unknown strengths using an intense radioactive $^7$Be beam from the ISAC facility and the DRAGON recoil separator in inverse kinematics. We have decreased the $^7$Be($\alpha,\gamma$)$^{11}$C reaction rate uncertainty to $\sim$ 9.4-10.7% over the relevant temperature region.

Read this paper on arXiv…

A. Psaltis, A. Chen, R. Longland, et. al.
Thu, 15 Sep 22
53/67

Comments: 15 pages, 12 figures. Accepted for publication in Phys. Rev. C

The CERN n TOF NEAR station for astrophysics- and application-related neutron activation measurements [CL]

Posted on by

http://arxiv.org/abs/2209.04443


A new experimental area, the NEAR station, has recently been built at the CERN n TOF facility, at a short distance from the spallation target (1.5 m). The new area, characterized by a neutron beam of very high flux, has been designed with the purpose of performing activation measurements of interest for astrophysics and various applications. The beam is transported from the spallation target to the NEAR station through a hole in the shielding wall of the target, inside which a collimator is inserted. The new area is complemented with a {\gamma}-ray spectroscopy laboratory, the GEAR station, equipped with a high efficiency HPGe detector, for the measurement of the activity resulting from irradiation of a sample in the NEAR station. The use of a moderator/filter assembly is envisaged, in order to produce a neutron beam of Maxwellian shape at different thermal energies, necessary for the measurement of Maxwellian Averaged Cross Sections of astrophysical interest. A new fast-cycling activation technique is also being investigated, for measurements of reactions leading to isotopes of very short half life.

Read this paper on arXiv…

N. Patronis, A. Mengoni, N. Colonna, et. al.
Tue, 13 Sep 22
39/85

Comments: N/A

Nucleonic metamodelling in light of multimessenger, PREX-II and CREX data [CL]

Posted on by

http://arxiv.org/abs/2209.05177


The need of reconciling our understanding of the behavior of hadronic matter across a wide range of densities, especially at the time when data from multimessenger observations and novel experimental facilities are flooding in, has provided new challenges to the nuclear models. Particularly, the density dependence of the isovector channel of the nuclear energy functionals seems hard to pin down if experiments like PREX-II (or PREX) and CREX are required to be taken on the same footing. We put to test this anomaly in a semi-agnostic modelling technique, by performing a full Bayesian analysis of static properties of neutron stars, together with global properties of nuclei as binding energy, charge radii and neutron skin calculated at the semi-classical level. Our results show that the interplay between bulk and surface properties, and the importance of high order empirical parameters that effectively decouple the subsaturation and the supersaturation density regime, might partially explain the tension between the different measurements and observations. If the surface behaviors, however, are decoupled from the bulk properties, we found a rather harmonious situation among experimental and observational data.

Read this paper on arXiv…

C. Mondal and F. Gulminelli
Tue, 13 Sep 22
60/85

Comments: 13 pages, 12 figures

Micro-Pattern Gaseous Detectors [CL]

Posted on by

http://arxiv.org/abs/2209.05202


This is a summary of White Papers on micro-pattern gaseous detectors, submitted to Instrumentation Frontier Group ‘IF5’, as part of the Snowmass 2021 decadal survey of particle physics.

Read this paper on arXiv…

B. Surrow, M. Titov, S. Vahsen, et. al.
Tue, 13 Sep 22
70/85

Comments: contribution to Snowmass 2021

Determination of asymptotic normalization coefficients for the channel $^{16}$O$\to α+^{12}$C. Excited state $^{16}$O($0^+; 6.05$ MeV) [CL]

Posted on by

http://arxiv.org/abs/2208.09587


Asymptotic normalization coefficients (ANC) determine the overall normalization of cross sections of peripheral radiative capture reactions. In the present paper, we treat the ANC $C$ for the virtual decay $^{16}$O$(0^+; 6.05$ MeV)$\to \alpha+^{12}$C(g.s.), the known values of which are characterized by a large spread $(0.29-1.65)\times 10^3$ fm$^{-1/2}$. The ANC $C$ is found by analytic continuation in the energy of the $\alpha^{12}$C $s$-wave scattering amplitude, known from the phase-shift analysis of experimental data, to the pole corresponding to the $^{16}$O bound state and lying in the unphysical region of negative energies. To determine $C$, two different methods of analytic continuation are used. In the first method, the scattering data are approximated by the sum of polynomials in energy in the physical region and then extrapolated to the pole. The best way of extrapolation is chosen on the basis of the exactly solvable model. Within the second approach, the ANC $C$ is found by solving the Schr\”odinger equation for the two-body $\alpha^{12}$C potential, the parameters of which are selected from the requirement of the best description of the phase-shift analysis data at a fixed experimental binding energy of $^{16}$O$(0^+; 6.05$ MeV) in the $\alpha+^{12}$C channel. The values of the ANC $C$ obtained within these two methods lie in the interval (886–1139) fm$^{-1/2}$.

Read this paper on arXiv…

L. Blokhintsev, A. Kadyrov, A. Mukhamedzhanov, et. al.
Tue, 23 Aug 22
47/79

Comments: arXiv admin note: text overlap with arXiv:1710.10767

High-order isospin-dependent surface tension contribution to the fourth-order symmetry energy of finite nuclei [CL]

Posted on by

http://arxiv.org/abs/2208.10438


The relation between the fourth-order symmetry energy $E_{\rm{sym,4}}(\rho_0)$ of nuclear matter at saturation density $\rho_0$ and its counterpart $a_{\rm{sym,4}}(A)$ of finite nuclei in a semi-empirical nuclear mass formula is revisited by considering the high-order isospin-dependent surface tension contribution to the latter. We derive the full expression of $a_{\rm{sym,4}}(A)$ which includes explicitly the high-order isospin-dependent surface tension effects, and find that the value of $E_{\rm{sym,4}}(\rho_0)$ cannot be extracted from the measured $a_{\rm{sym,4}}(A)$ before the high-order surface tension is well constrained. Our results imply that a large $a_{\rm{sym,4}}(A)$ value of several MeVs obtained from analyzing nuclear masses can nicely agree with the empirical constraint of $E_{\rm{sym,4}}(\rho_0)\lesssim 2$ MeV from mean-field models and does not necessarily lead to a large $E_{\rm{sym,4}}(\rho_0)$ value of $\sim 20$ MeV obtained previously without considering the high-order surface tension. Furthermore, we also give the expression for the sixth-order symmetry energy $a_{\rm{sym,6}}(A)$ of finite nuclei, which involves more nuclear matter bulk parameters and the higher-order isospin-dependent surface tension.

Read this paper on arXiv…

B. Cai, R. Wang, Z. Zhang, et. al.
Tue, 23 Aug 22
70/79

Comments: 7 pages, 2 figures

Neutrinos in Stellar Astrophysics [CL]

Posted on by

http://arxiv.org/abs/2208.08050


The physics of the mysterious and stealthy neutrino is at the heart of many phenomena in the cosmos. These particles interact with matter and with each other through the aptly named weak interaction. At typical astrophysical energies the weak interaction is some twenty orders of magnitude weaker than the electromagnetic interaction. However, in the early universe and in collapsing stars neutrinos can more than make up for their feeble interaction strength with huge numbers. Neutrinos can dominate the dynamics in these sites and set the conditions that govern the synthesis of the elements. Here we journey through the history of the discovery of these particles and describe their role in stellar evolution and collapse, the big bang, and multi-messenger astrophysics. Neutrino physics is at the frontier of elementary particle physics, nuclear physics, astrophysics and cosmology. All of these fields overlap in the neutrino story.

Read this paper on arXiv…

G. Fuller and W. Haxton
Thu, 18 Aug 22
26/45

Comments: 45 pages, 14 figures; To be published in Neutrino Physics and Astrophysics, edited by F. W. Stecker, in the Encyclopedia of Cosmology II, edited by G. G. Fazio, World Scientific Publishing Company, Singapore, 2022. arXiv admin note: text overlap with arXiv:1209.3743, arXiv:0808.0735

The Influence of Beta Decay Rates on r-Process Observables [HEAP]

Posted on by

http://arxiv.org/abs/2208.06373


The rapid neutron capture process (r-process) is one of the main mechanisms whereby elements heavier than iron are synthesized, and is entirely responsible for the natural production of the actinides. Kilonova emissions are modeled as being largely powered by the radioactive decay of species synthesized via the r -process. Given that the r -process occurs far from nuclear stability, unmeasured beta decay rates play an essential role in setting the time scale for the r -process. In an effort to better understand the sensitivity of kilonova modeling to different theoretical global beta-decay descriptions, we incorporate these into nucleosynthesis calculations. We compare the results of these calculations and highlight differences in kilonova nuclear energy generation and light curve predictions, as well as final abundances and their implications for nuclear cosmochronometry. We investigate scenarios where differences in beta decay rates are responsible for increased nuclear heating on time scales of days that propagates into a significantly increased average bolometric luminosity between 1-10 days post-merger. We identify key nuclei, both measured and unmeasured, whose decay rates are directly impact nuclear heating generation on timescales responsible for light curve evolution. We also find that uncertainties in beta decay rates significantly impact ages estimates from cosmochronometry.

Read this paper on arXiv…

K. Lund, J. Engel, G. McLaughlin, et. al.
Mon, 15 Aug 22
45/54

Comments: N/A

An induced annual modulation signature in COSINE-100 data by DAMA/LIBRA's analysis method [CL]

Posted on by

http://arxiv.org/abs/2208.05158


The DAMA/LIBRA collaboration has reported the observation of an annual modulation in the event rate that has been attributed to dark matter interactions over the last two decades. However, even though tremendous efforts to detect similar dark matter interactions were pursued, no definitive evidence has been observed to corroborate the DAMA/LIBRA signal. Many studies assuming various dark matter models have attempted to reconcile DAMA/LIBRA’s modulation signals and null results from other experiments, however no clear conclusion can be drawn. Apart from the dark matter hypothesis, several studies have examined the possibility that the modulation is induced by variations in their detector’s environment or their specific analysis methods. In particular, a recent study presents a possible cause of the annual modulation from an analysis method adopted by the DAMA/LIBRA experiment in which the observed annual modulation could be reproduced by a slowly varying time-dependent background. Here, we study the COSINE-100 data using an analysis method similar to the one adopted by the DAMA/LIBRA experiment and observe a significant annual modulation, although the modulation phase is almost opposite to that of the DAMA/LIBRA data. Assuming the same background composition for COSINE-100 and DAMA/LIBRA, simulated experiments for the DAMA/LIBRA without dark matter signals also provide significant annual modulation with an amplitude similar to DAMA/LIBRA with opposite phase. Even though this observation does not explain the DAMA/LIBRA’s results directly, this interesting phenomenon motivates deeper studies of the time-dependent DAMA/LIBRA background data.

Read this paper on arXiv…

G. Adhikari, N. Carlin, J. Choi, et. al.
Thu, 11 Aug 22
47/68

Comments: N/A

Nuclear mass predictions with machine learning reaching the accuracy required by $r$-process studies [CL]

Posted on by

http://arxiv.org/abs/2208.04783


Nuclear masses are predicted with the Bayesian neural networks by learning the mass surface of even-even nuclei and the correlation energies to their neighbouring nuclei. By keeping the known physics in various sophisticated mass models and performing the delicate design of neural networks, the proposed Bayesian machine learning (BML) mass model achieves an accuracy of $84$~keV, which crosses the accuracy threshold of the $100$~keV in the experimentally known region. It is also demonstrated the corresponding uncertainties of mass predictions are properly evaluated, while the uncertainties increase by about $50$~keV each step along the isotopic chains towards the unknown region. The shell structures in the known region are well described and several important features in the unknown region are predicted, such as the new magic numbers around $N = 40$, the robustness of $N = 82$ shell, the quenching of $N = 126$ shell, and the smooth separation energies around $N = 104$.

Read this paper on arXiv…

Z. Niu and H. Liang
Wed, 10 Aug 22
56/66

Comments: 14 pages, 5 figures

Spin symmetry energy and equation of state of spin-polarized neutron star matter [CL]

Posted on by

http://arxiv.org/abs/2206.00218


Equation of states (EOS) of the spin-polarized nuclear matter (NM) is studied within the Hartree-Fock (HF) formalism using the realistic density dependent nucleon-nucleon interaction. With a nonzero fraction $\Delta$ of spin-polarized baryons in NM, the spin- and spin-isospin dependent parts of the HF energy density give rise to the \emph{spin symmetry} energy that behaves in about the same manner as the \emph{isospin symmetry} energy, widely discussed in literature as the nuclear symmetry energy. The present HF study shows a strong correlation between the spin symmetry energy and nuclear symmetry energy over the whole range of baryon densities. The important contribution of the spin symmetry energy to the EOS of the spin-polarized NM is found to be comparable with that of the nuclear symmetry energy to the EOS of the isospin-polarized or asymmetric (neutron-rich) NM. Based on the HF energy density, the EOS of the spin-polarized ($\beta$-stable) np$e\mu$ matter is obtained for the determination of the macroscopic properties of neutron star (NS). A realistic density dependence of the spin-polarized fraction $\Delta$ have been suggested to explore the impact of the spin symmetry energy to the gravitational mass $M$ and radius $R$, as well as the tidal deformability of NS. Given the empirical constrains inferred from a coherent Bayesian analysis of gravitational wave signals of the NS merger GW170817 and the observed masses of the heaviest pulsars, the strong impacts of the spin symmetry energy $W$, nuclear symmetry energy $S$, and nuclear incompressibility $K$ to the EOS of nucleonic matter in magnetar were revealed.

Read this paper on arXiv…

N. Khoa, N. Tan and D. Khoa
Thu, 2 Jun 22
33/57

Comments: Accepted for publication in Phys. Rev. C. arXiv admin note: text overlap with arXiv:2010.00869

Feasibility of studying astrophysically important charged-particle emission with the variable energy $γ$-ray system at the Extreme Light Infrastructure — Nuclear Physics facility [CL]

Posted on by

http://arxiv.org/abs/2205.09599


In the environment of a hot plasma, as achieved in stellar explosions, capture and photodisintegration reactions proceeding on excited states in the nucleus can considerably contribute to the astrophysical reaction rate. Such reaction rates including the excited-state contribution are obtained from theoretical calculations as the direct experimental determination of these astrophysical rates is currently unfeasible. In the present study, ($\gamma$,p) and ($\gamma$,$\alpha$) reactions in the mass and energy range relevant to the astrophysical $p$ process are considered and the feasibility of measuring them with the ELISSA detector system at the future Variable Energy $\gamma$-ray (VEGA) facility at ELI-NP is investigated. The simulation results reveal that, for the ($\gamma$,p) reaction on twelve targets of $^{29}$Si, $^{56}$Fe, $^{74}$Se, $^{84}$Sr, $^{91}$Zr, $^{96,98}$Ru, $^{102}$Pd, $^{106}$Cd, and $^{115, 117, 119}$Sn, and the ($\gamma$,$\alpha$) reaction on five targets of $^{50}$V, $^{87}$Sr, $^{123,125}$Te, and $^{149}$Sm, the yields of the reaction channels with the transitions to the excited states in the residual nucleus are relevant and even dominant. It is further found that for each considered reaction, the total yields of the charged-particle $X$ may be dominantly contributed from one, two or three ($\gamma$,$X_{i}$) channels within a specific, narrow energy range of the incident $\gamma$-beam. Furthermore, the energy spectra of the ($\gamma$,$X_{i}$) channels with $0\leq i\leq 10$ are simulated for each considered reaction, with the incident $\gamma$-beam energies in the respective energy range as derived before. It becomes evident that measurements of the photon-induced reactions with charged-particle emissions considered in this work are feasible with the VEGA+ELISSA system and will provide knowledge useful for nuclear astrophysics.

Read this paper on arXiv…

H. Lan, W. Luo, Y. Xu, et. al.
Fri, 20 May 22
46/65

Comments: 11 figures, 17 pages

Horizons: Nuclear Astrophysics in the 2020s and Beyond [CL]

Posted on by

http://arxiv.org/abs/2205.07996


Nuclear Astrophysics is a field at the intersection of nuclear physics and astrophysics, which seeks to understand the nuclear engines of astronomical objects and the origin of the chemical elements. This white paper summarizes progress and status of the field, the new open questions that have emerged, and the tremendous scientific opportunities that have opened up with major advances in capabilities across an ever growing number of disciplines and subfields that need to be integrated. We take a holistic view of the field discussing the unique challenges and opportunities in nuclear astrophysics in regards to science, diversity, education, and the interdisciplinarity and breadth of the field. Clearly nuclear astrophysics is a dynamic field with a bright future that is entering a new era of discovery opportunities.

Read this paper on arXiv…

H. Schatz, A. Reyes, A. Best, et. al.
Wed, 18 May 22
15/66

Comments: 96 pages. Submitted to Journal of Physics G

Inverse Tritium Beta Decay with Relic Neutrinos, Solar Neutrinos, and a 51Cr Source [CL]

Posted on by

http://arxiv.org/abs/2205.02363


The inverse tritium beta decay (ITBD) reaction, $\nu_e + ^3$H $\to e^- + ^3$He, is a promising experimental tool for observing relic neutrinos created in the early Universe. This reaction has been selected by the PTOLEMY experiment for the search of relic neutrinos. Despite its potential, the ITBD reaction induced by any sources of neutrinos has yet to be observed. We show that an intense $^{51}$Cr radioactive neutrino source is suitable for observing the ITBD reaction for the first time. As the Sun is another source of intense electron neutrinos, we also examine the ITBD reaction rate from solar neutrinos. Based on our recent studies on the evolution of the helicity of relic neutrinos, we further present the ITBD rate for capturing relic neutrinos as a function of neutrino mass hierarchy, the Dirac versus Majorana nature of neutrino, and the mass of the lightest neutrino.

Read this paper on arXiv…

J. Peng and G. Baym
Fri, 6 May 22
25/55

Comments: 5 pages, 4 figures

Investigating Possible Existence of Hyper-Heavy Nuclei in Neutron Star Environment [CL]

Posted on by

http://arxiv.org/abs/2205.00478


The synthesis of hyper-heavy elements is investigated under conditions simulating neutron star environment. The Constrained Molecular Dynamics (CoMD) approach is used to simulate low energy collisions of extremely n-rich nuclei. A new type of the fusion barrier due to a “neutron wind” is observed when the effect of neutron star environment (screening of Coulomb interaction) is introduced implicitly. When introducing also a background of surrounding nuclei, the nuclear fusion becomes possible down to temperatures of 10$^{8}$ K and synthesis of extremely heavy and n-rich nuclei appears feasible. A possible existence of hyper-heavy nuclei in a neutron star environment could provide a mechanism of extra coherent neutrino scattering or an additional mechanism, resulting in X-ray burst or a gravitational wave signal and, thus, becoming another crucial process adding new information to the suggested models on neutron star evolution.

Read this paper on arXiv…

M. Veselsky, V. Petousis, C. Moustakidis, et. al.
Tue, 3 May 22
74/82

Comments: 10 pages, 5 figures

Nuclear equation of state for arbitrary proton fraction and temperature based on chiral effective field theory and a Gaussian process emulator [CL]

Posted on by

http://arxiv.org/abs/2204.14016


We calculate the equation of state of asymmetric nuclear matter at finite temperature based on chiral effective field theory interactions to next-to-next-to-next-to-leading order. Our results assess the theoretical uncertainties from the many-body calculation and the chiral expansion. Using a Gaussian process emulator for the free energy, we derive the thermodynamic properties of matter through consistent derivatives and use the Gaussian process to access arbitrary proton fraction and temperature. This enables a first nonparametric calculation of the equation of state in beta equilibrium, and of the speed of sound and the symmetry energy at finite temperature. Moreover, our results show that the thermal part of the pressure decreases with increasing densities.

Read this paper on arXiv…

J. Keller, K. Hebeler and A. Schwenk
Mon, 2 May 22
12/52

Comments: 6 pages, 5 figures

Constraining nucleosynthesis in neutrino-driven winds: observations, simulations and nuclear physics [HEAP]

Posted on by

http://arxiv.org/abs/2204.07136


A promising astrophysical site to produce the lighter heavy elements of the first $r$-process peak ($Z = 38-47$) is the moderately neutron rich ($0.4 < Y_e < 0.5$) neutrino-driven ejecta of explosive environments, such as core-collapse supernovae and neutron star mergers, where the weak $r$-process operates. This nucleosynthesis exhibits uncertainties from the absence of experimental data from $(\alpha,xn)$ reactions on neutron-rich nuclei, which are currently based on statistical model estimates. In this work, we report on a new study of the nuclear reaction impact using a Monte Carlo approach and improved $(\alpha,xn)$ rates based on the Atomki-V2 $\alpha$ Optical Model Potential ($\alpha$OMP). We compare our results with observations from an up-to-date list of metal-poor stars with [Fe/H] $<$ -1.5 to find conditions of the neutrino-driven wind where the lighter heavy elements can be synthesized. We identified a list of $(\alpha,xn)$ reaction rates that affect key elemental ratios in different astrophysical conditions. Our study aims on motivating more nuclear physics experiments on $(\alpha, xn)$ reactions using current and the new generation of radioactive beam facilities and also more observational studies of metal-poor stars.

Read this paper on arXiv…

A. Psaltis, A. Arcones, F. Montes, et. al.
Fri, 15 Apr 22
21/50

Comments: 16 pages, 8 figures, submitted to ApJ

$^{57}$Zn $β$-delayed proton emission establishes the $^{56}$Ni $rp$-process waiting point bypass [CL]

Posted on by

http://arxiv.org/abs/2204.01621


We measured the $^{57}$Zn $\beta$-delayed proton ($\beta$p) and $\gamma$ emission at the National Superconducting Cyclotron Laboratory. We find a $^{57}$Zn half-life of 43.6 $\pm$ 0.2 ms, $\beta$p branching ratio of (84.7 $\pm$ 1.4)%, and identify four transitions corresponding to the exotic $\beta$-$\gamma$-$p$ decay mode, the second such identification in the $f p$-shell. The $p/\gamma$ ratio was used to correct for isospin mixing while determining the $^{57}$Zn mass via the isobaric multiplet mass equation. Previously, it was uncertain as to whether the rp-process flow could bypass the textbook waiting point $^{56}$Ni for astrophysical conditions relevant to Type-I X-ray bursts. Our results definitively establish the existence of the $^{56}$Ni bypass, with 14-17% of the $rp$-process flow taking this route.

Read this paper on arXiv…

M. Saxena, W. Ong, Z. Meisel, et. al.
Tue, 5 Apr 22
1/83

Comments: N/A

Astrophysical reaction rates with realistic nuclear level densities [CL]

Posted on by

http://arxiv.org/abs/2203.14220


Realistic nuclear level densities (NLDs) obtained within the spectral distribution method (SDM) are employed to study nuclear processes of astrophysical interest. The merit of SDM lies in the fact that the NLDs corresponding to many body shell model Hamiltonian consisting of residual interaction can be obtained for the full configurational space without recourse to the exact diagnolization of huge matrices. We calculate NLDs and s-wave neutron resonance spacings which agree reasonably well with the available experimental data. By employing these NLDs, we compute reaction cross-sections and astrophysical reaction rates for radiative neutron capture in few Fe-group nuclei, and compare them with experimental data as well as with those obtained with NLDs from phenomenological and microscopic mean-field models. The results obtained for the NLDs from SDM are able to explain the experimental data quite well. These results are of particular importance since the configuration mixing through the residual interaction naturally accounts for the collective excitations. In the mean-field models, the collective effects are included through the vibrational and rotational enhancement factors and their NLDs are further normalized at low energies with neutron resonance data.

Read this paper on arXiv…

S. Sangeeta, T. Ghosh, B. Maheshwari, et. al.
Tue, 29 Mar 22
21/73

Comments: Accepted in Physical Review C (2022)

Deciphering Effects of Relativistic Kinematics, Dimensionality, Interactions and Short-Range Correlations on the Ratio of Quartic over Quadratic Nuclear Symmetry Energies [CL]

Posted on by

http://arxiv.org/abs/2203.12773


While ample evidence for the so-called empirical parabolic law of the Equation of State (EOS) of isospin asymmetric nuclear matter (ANM) has been obtained in many studies within both non-relativistic and relativistic nuclear many-body theories using various interactions, it has been unclear if there is any fundamental physics reason for the small quartic symmetry energy compared to the quadratic one even as the ANM approaches pure neutron matter. Within both relativistic and non-relativistic Free Fermi Gas (FFG) models in coordinate spaces of arbitrary dimension $d$ with and without considering Short-Range Correlations (SRC) as well as non-linear Relativistic Mean Field (RMF) models, we study effects of relativistic kinematics, dimensionality, interactions and SRC on the ratio $\Psi(\rho)$ of quartic over quadratic symmetry energies in ANM EOSs. We found that the ratio $\Psi(\rho)$ in the FFG model depends strongly on the dimension $d$. While it is very small already in the normal 3D space, it could be even smaller in spaces with reduced dimensions for sub-systems of particles in heavy-ion reactions and/or whole neutron stars due to constraints, collectivities and/or symmetries. We also found that the ratio $\Psi(\rho)$ could theoretically become very large only at the ultra-relativistic limit far above the density reachable in neutron stars. On the other hand, nuclear interaction directly and/or indirectly through SRC-induced high-momentum nucleons affect significantly the density dependence of $\Psi(\rho)$ compared to the relativistic FFG model prediction. The SRC affects significantly not only the kinetic energy of symmetric nuclear matter but also the ratio $\Psi(\rho)$ while the relativistic corrections are found negligible. The results may help better understand the EOS of dense neutron-rich matter.

Read this paper on arXiv…

B. Cai and B. Li
Fri, 25 Mar 22
29/46

Comments: 11 pages with 3 figures

A Strategy for Low-Mass Dark Matter Searches with Cryogenic Detectors in the SuperCDMS SNOLAB Facility [CL]

Posted on by

http://arxiv.org/abs/2203.08463


The SuperCDMS Collaboration is currently building SuperCDMS SNOLAB, a dark matter search focused on nucleon-coupled dark matter in the 1-5 GeV mass range. Looking to the future, the Collaboration has developed a set of experience-based upgrade scenarios, as well as novel directions, to extend the search for dark matter using the SuperCDMS technology in the SNOLAB facility. The experienced-based scenarios are forecasted to probe many square decades of unexplored dark matter parameter space below 5 GeV, covering over 6 decades in mass: 1-100 eV for dark photons and axion-like particles, 1-100 MeV for dark-photon-coupled light dark matter, and 0.05-5 GeV for nucleon-coupled dark matter. They will reach the neutrino fog in the 0.5-5 GeV mass range and test a variety of benchmark models and sharp targets. The novel directions involve greater departures from current SuperCDMS technology but promise even greater reach in the long run, and their development must begin now for them to be available in a timely fashion.
The experienced-based upgrade scenarios rely mainly on dramatic improvements in detector performance based on demonstrated scaling laws and reasonable extrapolations of current performance. Importantly, these improvements in detector performance obviate significant reductions in background levels beyond current expectations for the SuperCDMS SNOLAB experiment. Given that the dominant limiting backgrounds for SuperCDMS SNOLAB are cosmogenically created radioisotopes in the detectors, likely amenable only to isotopic purification and an underground detector life-cycle from before crystal growth to detector testing, the potential cost and time savings are enormous and the necessary improvements much easier to prototype.

Read this paper on arXiv…

S. Collaboration, M. Albakry, I. Alkhatib, et. al.
Thu, 17 Mar 22
26/66

Comments: contribution to Snowmass 2021

The Sanford Underground Research Facility [CL]

Posted on by

http://arxiv.org/abs/2203.08293


The Sanford Underground Research Facility (SURF) has been operating since 2007 supporting underground research in rare-process physics, as well as offering research opportunities in other disciplines. SURF laboratory facilities include a Surface Campus as well as campuses at the 4850-foot level (1500 m, 4300 m.w.e.) that host a range of significant physics experiments, including those studying dark matter, neutrino properties, and nuclear astrophysics topics. SURF is also home to the Long-Baseline Neutrino Facility (LBNF) that will host the international Deep Underground Neutrino Experiment (DUNE). SURF offers an ultra-low background environment, low-background assay capabilities, and electroformed copper is produced at the facility. SURF is proposing additional underground space on the 4850L and 7400L (2300 m, 6500 m.w.e.), and initial engineering designs have been completed. SURF is a dedicated research facility with significant expansion capability, and applications from new experiments are welcome.

Read this paper on arXiv…

J. Heise
Thu, 17 Mar 22
40/66

Comments: Contribution to Snowmass 2021

Neutrino-Flux Variability, Nuclear-Decay Variability, and Their Apparent Relationship [SSA]

Posted on by

http://arxiv.org/abs/2203.05069


Homestake, Gallex and GNO data reveal variability of the solar neutrino flux. Kamiokande records for 1996-2001 reveal oscillations at 9.43 and 12.6 yr$^{-1}$, well within a range (6-16 yr$^{-1}$) that, according to helioseismology, may be related to internal solar rotation. A nuclear-decay experiment at Brookhaven National Laboratory (for 1982-86) reveals strong oscillations at 11.2 and 13.2 yr$^{-1}$. Similar oscillations are found in nuclear-decay measurements conducted by A. Parkhomov. By contrast, S. Pomme points out that nuclear-decay experiments at standards laboratories tend not to exhibit variability. The most extensive series of nuclear-decay measurements comes from an experiment initiated by G. Steinitz at the Geological Survey of Israel (2007-16), which recorded 340,000 radon-related measurements from each of 3 gamma detectors and 3 environmental sensors. Analysis of a subset of 85,000 hourly gamma measurements reveals a number of oscillation frequencies compatible with influences of internal solar rotation. There is no correlation between the gamma and environmental measurements. The solar internal magnetic field may lead to neutrino modulation by the RSFP (Resonant Spin-Flavor Precession) mechanism. A triplet of oscillations (7.43, 8.43 and 9.43 yr$^{-1}$) may be attributed to an internal region (presumably the core) with a sidereal rotation rate of 8.43 yr$^{-1}$ and a rotation axis roughly orthogonal to that of the photosphere. This suggests that the Sun had its origin in more than one stage of condensation of interplanetary material (one on top of another), which could lead to present-day layers with different metallicities, rotation rates and axes. The peak modulation occurs near local midnight in early June, suggestive of a role of cosmic neutrinos. These neutrinos could provide the mass attributed to dark matter for a neutrino mass of order 0.1 eV.

Read this paper on arXiv…

P. Sturrock
Fri, 11 Mar 22
29/59

Comments: 60 pages, 4 tables, 13 figures

New constraints on the neutron-star mass and radius relation from the terrestrial nuclear experiments [CL]

Posted on by

http://arxiv.org/abs/2203.05410


The study of the equation of state (EOS) for nuclear matter has been still a challenging problem, although the EOS is essential for determining the properties of neutron stars. In order to constrain the EOS, several studies have been based on astronomical observations with the X-ray and gravitational waves, which mainly cover the higher density of neutron star matter. In this study, focusing on the relatively lower density region, we show an allowed area in the neutron-star mass and radius relation by using the constraints on the density-dependence of the nuclear symmetry energy obtained via the recent nuclear experiments with different projects (i.e., S$\pi$RIT and PREX-II) together with the experiment at RCNP. Each region predicted by these experiments is still consistent with the area in the higher density allowed by the various astronomical observations. Our results show that terrestrial nuclear experiments must provide further constraints on the EOS for neutron stars, complementing astronomical observations.

Read this paper on arXiv…

H. Sotani, N. Nishimura and T. Naito
Fri, 11 Mar 22
53/59

Comments: 10 pages, 2 figures, submitted

Status of deep subbarrier $\mathbf{{}^{12}{\rm C}+{}^{12}{\rm C}}$ fusion and advancing the Trojan horse method [CL]

Posted on by

http://arxiv.org/abs/2203.04094


In this paper, I will update the current status of the carbon-carbon fusion research taking into account that after the latest analysis [Beck {\it et al.} Eur. Phys. J. A {\bf 56}, 97 (2020), Letter to the Editor] new important experimental and theoretical results had been published and will discuss how to advance new THM measurements to extract the low-energy astrophysical $S$-factors.

Read this paper on arXiv…

A. Mukhamedzhanov
Wed, 9 Mar 22
63/68

Comments: 13 pages, 7 figures

A Next-Generation Liquid Xenon Observatory for Dark Matter and Neutrino Physics [CL]

Posted on by

http://arxiv.org/abs/2203.02309


The nature of dark matter and properties of neutrinos are among the most pressing issues in contemporary particle physics. The dual-phase xenon time-projection chamber is the leading technology to cover the available parameter space for Weakly Interacting Massive Particles (WIMPs), while featuring extensive sensitivity to many alternative dark matter candidates. These detectors can also study neutrinos through neutrinoless double-beta decay and through a variety of astrophysical sources. A next-generation xenon-based detector will therefore be a true multi-purpose observatory to significantly advance particle physics, nuclear physics, astrophysics, solar physics, and cosmology. This review article presents the science cases for such a detector.

Read this paper on arXiv…

J. Aalbers, K. Abe, V. Aerne, et. al.
Mon, 7 Mar 22
37/64

Comments: 77 pages, 40 figures, 1262 references

Optimization study of the electrode design of a 5 mm thick orthogonal-strip CdZnTe detector system [CL]

Posted on by

http://arxiv.org/abs/2203.02332


The geometry of electrodes is one of the most important factors in determining the performance of orthogonal-strip detectors. The aim of this work is to study the performance of a 5 mm thick cross-strip CdZnTe detector with different electrode widths. Our study consists of two main parts, simulations and experiments. We utilized four different anode sizes ranging from 0.1 mm to 0.6 mm. The anodes were interspersed with steering electrodes with varying sizes from 0.3 mm to 0.85 mm. The maximum gap size between the anodes and steering electrode strips was set to 0.3 mm, while the minimum gap size was 0.125 mm. The performance of the detector was investigated in terms of the steering electrode bias voltage, the energy resolution, and the charge sharing effect. For simulations, we developed a C++ based simulation program for charge transport inside the CdZnTe detector and charge collection at the electrodes. For photon interactions we used GEANT4 toolkit and for electric field and weighting potential simulations we used COMSOL software. The results demonstrated that -50 V is the optimal steering electrode bias for our detector when -500 V was applied to the cathodes and that the energy resolution performance drops with increasing steering electrode width. Also, the charge sharing effect becomes more dominant for larger steering electrode sizes. The experimental result are further compared with the simulations. The results are in a good agreement and the comparison validates our simulation model. Although, our simulation framework has need of better estimation for the intrinsic noise of CdZnTe. These results suggest that an optimization study between electrode widths and steering electrode bias is required to obtain the best performance in orthogonal-strip CdZnTe detectors.

Read this paper on arXiv…

A. Altingun and E. Kalemci
Mon, 7 Mar 22
39/64

Comments: N/A

On the importance of Fe fragmentation for LiBeB analyses: Do we need a Li primary source to explain AMS-02 data? [HEAP]

Posted on by

http://arxiv.org/abs/2203.00522


Li, Be, and B high-precision data from AMS-02 provide the best constraints on Galactic cosmic-ray transport parameters. We re-evaluate the impact of Fe fragmentation on the Li, Be, and B modelling. We discuss the consequences on the transport parameter determination and reassess whether a primary source of Li is needed to match AMS-02 data. We renormalise several cross-section parametrisations to existing data for the most important reactions producing Li, Be, and B. We use the \usine{} code with these new cross-section sets to re-analyse Li/C, Be/C, and B/C AMS-02 data. We build three equally plausible cross-section sets. Compared to the use of the initial cross-section sets, they lead to an average enhanced production of Li ($\sim20-50\%$) and Be ($\sim5-15\%$), while leaving the B flux mostly unchanged. In particular, Fe fragmentation is found to contribute to up to 10\% of the Li and Be fluxes. Used in the combined analysis of AMS-02 Li/C, Be/C, and B/C data, the fit is significantly improved, with an enhanced diffusion coefficient ($\sim 20\%)$. The three updated cross-section sets are found to either slightly undershoot or overshoot the Li/C and B/C ratios: this strongly disfavours evidences for a primary source of Li in cosmic rays. We stress that isotopic cosmic-ray ratios of Li (and to a lesser extent Be), soon to be released by AMS-02, are also impacted by the use of these updated sets. Almost no nuclear data exist for the production of Li and B isotopes from Ne, Mg, Si, and Fe, whereas these reactions are estimated to account for $\sim 20\%$ of the total production. Some new nuclear measurements are clearly desired to better exploit the high-precision AMS-02 cosmic-ray data.

Read this paper on arXiv…

D. Maurin, E. Bueno, Y. Génolini, et. al.
Wed, 2 Mar 22
25/54

Comments: 20 pages, 16 figures, 2 tables (submitted to A&A)

Non-iterative finite amplitude methods for E1 and M1 giant resonances [CL]

Posted on by

http://arxiv.org/abs/2202.13214


The finite amplitude method (FAM) is a very efficient approach for solving the fully self-consistent random-phase approximation (RPA) equations. We use FAM to rederive the RPA matrices for general Skyrme-like functionals, calculate the electric dipole (E1) and the magnetic dipole (M1) giant resonances, and compare the results with available experimental and evaluated data. For the E1 transitions in heavy nuclei, the calculations reproduce well the resonance energy of the photoabsorption cross sections. In the case of M1 transitions, we show that the residual interaction does not affect the transition strength of double-magic nuclei, which suggests that the spin terms in the Skyrme force currently neglected in the present computation could improve the agreement between FAM and experimental data.

Read this paper on arXiv…

H. Sasaki, T. Kawano and I. Stetcu
Tue, 1 Mar 22
58/80

Comments: 15 pages, 6 figures

Theia: Summary of physics program. Snowmass White Paper Submission [CL]

Posted on by

http://arxiv.org/abs/2202.12839


Theia would be a novel, “hybrid” optical neutrino detector, with a rich physics program. This paper is intended to provide a brief overview of the concepts and physics reach of Theia. Full details can be found in the Theia white paper [1].

Read this paper on arXiv…

M. Askins, Z. Bagdasarian, N. Barros, et. al.
Mon, 28 Feb 22
12/38

Comments: Contribution to Snowmass 2021

Benchmark calculations of infinite neutron matter with realistic two- and three-nucleon potentials [CL]

Posted on by

http://arxiv.org/abs/2202.10293


We present the equation of state of infinite neutron matter as obtained from highly-realistic Hamiltonians that include nucleon-nucleon and three-nucleon coordinate-space potentials. We benchmark three independent many-body methods: Brueckner-Bethe-Goldstone (BBG), Fermi hypernetted chain/single-operator chain (FHNC/SOC), and auxiliary-field diffusion Monte Carlo (AFDMC). We find them to provide similar equations of state when the Argonne $v_{18}$ and the Argonne $v_{6}^\prime$ nucleon-nucleon potentials are used in combination with the Urbana IX three-body force. Only at densities larger than about 1.5 the nuclear saturation density ($\rho_0 = 0.16\,\rm{fm}^{-3}$) the FHNC/SOC energies are appreciably lower than the other two approaches. The AFDMC calculations carried out with all of the Norfolk potentials fitted to reproduce the experimental trinucleon ground-state energies and $nd$ doublet scattering length yield unphysically bound neutron matter, associated with the formation of neutron droplets. Including tritium $\beta$-decay in the fitting procedure, as in the second family of Norfolk potentials, mitigates but does not completely resolve this problem. An excellent agreement between the BBG and AFDMC results is found for the subset of Norfolk interactions that do not make neutron-matter collapse, while the FHNC/SOC equations of state are moderately softer.

Read this paper on arXiv…

A. Lovato, I. Bombaci, D. Logoteta, et. al.
Tue, 22 Feb 22
47/77

Comments: 15 pages, 3 figures. arXiv admin note: text overlap with arXiv:1908.04426

Effects of isoscalar- and isovector-scalar meson mixing on neutron star structure [CL]

Posted on by

http://arxiv.org/abs/2202.08705


Based on the accurately calibrated interaction FSUGold, we show that including isovector scalar $\delta$ meson and its coupling to isoscalar scalar $\sigma$ meson in the relativistic mean field (RMF) model can soften the symmetry energy $E_{\rm{sym}}(n)$ at intermediate density while stiffen the $E_{\rm{sym}}(n)$ at high densities. We find this new RMF model can be simultaneously compatible with (1) the constraints on the equation of state of symmetric nuclear matter at suprasaturation densities from flow data in heavy-ion collisions, (2) the neutron skin thickness of $^{208}$Pb from the PREX-II experiment, (3) the largest mass of neutron star (NS) reported so far from PSR J0740+6620, (4) the limit of $\Lambda_{1.4}\leq580$ for the dimensionless tidal deformability of the canonical 1.4$M_{\odot}$ NS from the gravitational wave signal GW170817, (5) the mass-radius of PSR J0030+0451 and PSR J0740+6620 measured by NICER, and thus remove the tension between PREX-II and GW170817 observed in the conventional RMF model.

Read this paper on arXiv…

F. Li, B. Cai, Y. Zhou, et. al.
Fri, 18 Feb 22
48/63

Comments: 7 pages, 2 figures, 2 tables

Asymmetric nuclear matter in relativistic mean-field models with isoscalar- and isovector-meson mixing [CL]

Posted on by

http://arxiv.org/abs/2202.06468


Using the relativistic mean-field model with nonlinear couplings between the isoscalar and isovector mesons, we study the properties of isospin-asymmetric nuclear matter. Not only the vector mixing, $\omega_{\mu}\omega^{\mu}\mathbf{\rho}{\nu}\mathbf{\rho}^{\nu}$, but also the quartic interaction due to the scalar mesons, $\sigma^{2}\mathbf{\delta}^{2}$, is taken into account to investigate the density dependence of nuclear symmetry energy, $E{\rm sym}$, and the neutron-star properties. It is found that the $\delta$ meson increases $E_{\rm sym}$ at high densities, whereas the $\sigma$-$\delta$ mixing makes $E_{\rm sym}$ soft above the saturation density. Furthermore, the $\delta$ meson and its mixing have a large influence on the radius and tidal deformability of a neutron star. In particular, the $\sigma$-$\delta$ mixing reduces the neutron-star radius, and, thus, the present calculation can simultaneously reproduce the dimensionless tidal deformabilities of a canonical $1.4M_{\odot}$ neutron star observed from the binary neutron star merger, GW170817, and from the compact binary coalescence, GW190814.

Read this paper on arXiv…

T. Miyatsu, M. Cheoun and K. Saito
Tue, 15 Feb 22
68/75

Comments: 11 pages, 14 figures, 2 tables

New Constraint on the Local Relic Neutrino Background Overdensity with the First KATRIN Data Runs [CL]

Posted on by

http://arxiv.org/abs/2202.04587


We report on the direct cosmic relic neutrino background search from the first two science runs of the KATRIN experiment in 2019. Beta-decay electrons from a high-purity molecular tritium gas source are analyzed by a high-resolution MAC-E filter around the kinematic endpoint at 18.57 keV. The analysis is sensitive to a local relic neutrino overdensity of 9.7e10 (1.1e11) at a 90% (95%) confidence level. A fit of the integrated electron spectrum over a narrow interval around the kinematic endpoint accounting for relic neutrino captures in the Tritium source reveals no significant overdensity. This work improves the results obtained by the previous kinematic neutrino mass experiments at Los Alamos and Troitsk. We furthermore update the projected final sensitivity of the KATRIN experiment to <1e10 at 90% confidence level, by relying on updated operational conditions.

Read this paper on arXiv…

M. Aker, D. Batzler, A. Beglarian, et. al.
Thu, 10 Feb 22
37/66

Comments: 7 pages, 7 figures

First measurement of the absorption of $^{3}\overline{\rm He}$ nuclei in matter and impact on their propagation in the galaxy [CL]

Posted on by

http://arxiv.org/abs/2202.01549


Antimatter particles such as positrons and antiprotons abound in the cosmos. Much less common are light antinuclei, composed of antiprotons and antineutrons, which can be produced in our galaxy via high-energy cosmic-ray collisions with the interstellar medium or could also originate from the annihilation of the still undiscovered dark-matter particles. On Earth, the only way to produce and study antinuclei with high precision is to create them at high-energy particle accelerators like the Large Hadron Collider (LHC). Though the properties of elementary antiparticles have been studied in detail, knowledge of the interaction of light antinuclei with matter is rather limited. This work focuses on the determination of the disappearance probability of \ahe\ when it encounters matter particles and annihilates or disintegrates. The material of the ALICE detector at the LHC serves as a target to extract the inelastic cross section for \ahe\ in the momentum range of $1.17 \leq p < 10$ GeV/$c$. This inelastic cross section is measured for the first time and is used as an essential input to calculations of the transparency of our galaxy to the propagation of $^{3}\overline{\rm He}$ stemming from dark-matter decays and cosmic-ray interactions within the interstellar medium. A transparency of about 50% is estimated using the GALPROP program for a specific dark-matter profile and a standard set of propagation parameters. For cosmic-ray sources, the obtained transparency with the same propagation scheme varies with increasing $^{3}\overline{\rm He}$ momentum from 25% to 90%. The absolute uncertainties associated to the $^{3}\overline{\rm He}$ inelastic cross section measurements are of the order of 10%$-$15%. The reported results indicate that $^{3}\overline{\rm He}$ nuclei can travel long distances in the galaxy, and can be used to study cosmic-ray interactions and dark-matter decays.

Read this paper on arXiv…

A. Collaboration
Fri, 4 Feb 22
52/65

Comments: 26 pages, 5 captioned figures, authors from page 21, figures at this http URL

Neutrino Astronomy with IMB, Kamiokande and Super Kamiokande [HEAP]

Posted on by

http://arxiv.org/abs/2202.01676


Some of the earliest work on neutrino astronomy was accomplished by a class of underground detectors primarily designed for particle physics goals . These detectors used inexpensive water to obtain the large masses needed to observe the very low interaction rates expected from neutrinos. They exploited the relatively large light attenuation length and the index of refraction of the water to get a very inexpensive cost per thousand tons of detector.
The results obtained from these pioneering neutrino detectors have included real time observation of solar neutrinos, supernova neutrinos, and atmospheric neutrinos. Searches for neutrino point sources, dark matter and primordial magnetic monopoles were also made using them.

Read this paper on arXiv…

J. LoSecco
Fri, 4 Feb 22
65/65

Comments: To be published in Neutrino Physics and Astrophysics, edited by F. W. Stecker, in the Encyclopedia of Cosmology II, edited by G. G. Fazio, World Scientific Publishing Company, Singapore, 2022. 41 pages, 31 figures

Effect of Magnetic Field Dissipation on Primordial Li Abundance [CEA]

Posted on by

http://arxiv.org/abs/2201.13039


The dissipation effects of primordial magnetic fields on the primordial elemental abundances were investigated. When a magnetic field reconnects, its energy is converted to the kinetic energy of charged particles, as observed for solar energetic particles arriving on earth. This accelerates the cosmic background nuclei, and energetic nuclei induce nonthermal reactions. A constraint on the dissipation is derived from a theoretical calculation of the nonthermal reactions during Big Bang nucleosynthesis. We found that observations of the Li and D abundances can be explained if 0.01–0.1 % of the cosmic energy density was utilized for nuclear acceleration after the electron–positron annihilation epoch. Reconnections of such amplitudes of magnetic fields generate outgoing jets, the bulk velocity of which evolves to values appropriate for cosmic ray (CR) nuclear energies of 0.1–1 MeV necessary for successful CR nucleosynthesis. Therefore, acceleration of cosmic background nuclei during the dissipation of primordial magnetic fields is a possible generation mechanism of soft CRs that has been suggested as a solution to the cosmic Li problem. Among the solutions suggested without exotic physics, only the dissipating magnetic field model suggested here explains observations of both low Li and high D abundances. Our results demonstrate that signatures of strong magnetic fields in the early universe have been observed in primordial elemental abundances.

Read this paper on arXiv…

Y. Lu and M. Kusakabe
Tue, 1 Feb 22
12/73

Comments: 15 pages, 5 figures, ApJL, in press

Activation cross section measurement of the 14N(p,gamma)15O astrophysical key reaction [CL]

Posted on by

http://arxiv.org/abs/2201.10176


14N(p,gamma)15O is one of the key reactions of nuclear astrophysics playing a role in various stellar processes and influencing energy generation of stars, stellar evolution and nucleosynthesis. For a reliable reaction rate calculation the low energy cross section of 14N(p,gamma)15O must be known with high accuracy. Owing to the unmeasurable low cross sections, theoretical calculations are unavoidable. High precision experimental cross section data are needed in a wide energy range in order to provide the necessary basis for low energy extrapolations. In the present work the total 14N(p,gamma)15O cross section was measured with a method complementary to the available data sets. The cross section was measured with activation, based on the detection of the annihilation radiation following the beta+ decay of the reaction product 15O. This method, which provides directly the astrophysically important total cross section, was never used for the 14N(p,gamma)15O cross section measurement in the studied energy range. The non-resonant cross section was measured between 550 keV and 1400 keV center-of-mass energies with total uncertainty of about 10%. The results were compared with literature data using an R-matrix analysis. It is found that the cross sections measured in this work are in acceptable agreement with the two recent measurements only if the weak transitions – not measured in those works – are included. The present data set, being largely independent from the other available data, can be used to constrain the extrapolated cross sections to astrophysical energies and helps to make the astrophysical model calculations more reliable.

Read this paper on arXiv…

G. Gyürky, Z. Halász, G. Kiss, et. al.
Wed, 26 Jan 22
24/53

Comments: Accepted for publication in Phys. Rev. C as a letter

A theoretical overview of isospin and EOS effects in heavy-ion reactions at intermediate energies [CL]

Posted on by

http://arxiv.org/abs/2201.09133


The isospin dependence of in-medium nuclear effective interactions is a fundamental issue in nuclear physics and has broad ramifications in astrophysics. Its uncertainties, especially the difference of neutron-proton interactions in the isosinglet and isotriplet channels, affect significantly the density and momentum dependence of the isovector single-nucleon potential and nucleon-nucleon short-range correlation in neutron-rich matter. Consequently, the neutron-proton effective mass splitting and the density dependence of nuclear symmetry energy are still rather uncertain. Heavy-ion reactions especially those involving rare isotopes is a useful tool for probing the isospin dependence of nuclear effective interactions through (1) the neutron-skin in coordinate and proton-skin in momentum of the initial state of colliding nuclei, (2) the density and momentum dependence of especially the isovector nuclear mean-field as well as (3) the isospin dependence of in-medium nucleon-nucleon cross sections. Observations of neutron stars especially since GW1710817 have also helped us significantly in understanding the isospin dependence of nuclear effective interactions. {\it We summarize here a review talk on these issues given at the 2021 International Workshop on multi-facets of EOS and Clustering. For details we refer the readers to the original publications and references therein}.

Read this paper on arXiv…

B. Li, B. Cai, L. Chen, et. al.
Tue, 25 Jan 22
24/78

Comments: Proc. of the International Workshop on Multi-facets of EoS and Clustering, Caen, France, Nov. 23-26th, 2021

A feasibility study of extruded plastic scintillator embedding WLS fiber for AMoRE-II muon veto [CL]

Posted on by

http://arxiv.org/abs/2201.08034


AMoRE-II is the second phase of the Advanced Molybdenum-based Rare process Experiment aiming to search for the neutrino-less double beta decay of 100Mo isotopes using ~ 200 kg of molybdenum-containing cryogenic detectors. The AMoRE-II needs to keep the background level below 10-5 counts/keV/kg/year with various methods to maximize the sensitivity. One of the methods is to have the experiment be carried out in a deep underground free from the cosmic ray backgrounds. The AMoRE-II will run at Yemilab with ~ 1,000 m depth. Even in such a deep underground environment, however, there are still survived cosmic muons which can affect the measurement and should be excluded as much as possible. A muon veto detector is necessary to reject muon-induced particles coming to the inner detector where the molybdate cryogenic detectors are located. We have studied the possibility of using an extruded plastic scintillator and wavelength shifting fiber together with SiPM as a muon veto system. We obtained a muon flux of 428.4 events/m2/day at Yangyang underground laboratory using a prototype muon detector, in agreement with a COSINE-100 measurement. The estimated event rate in the AMoRE-II muon veto system for a 135 m2 total veto area is 2.04 events/s.

Read this paper on arXiv…

J. Seo, W. Kim, Y. Kim, et. al.
Fri, 21 Jan 22
45/60

Comments: 9 pages, 8 figures, 2 tables

Experimental study of the $^{30}$Si($^{3}$He,$d$)$^{31}$P reaction and thermonuclear reaction rate of $^{30}$Si($p$,$γ$)$^{31}$P [CL]

Posted on by

http://arxiv.org/abs/2201.03411


[Background] Abundance anomalies in some globular clusters, such as the enhancement of potassium and the depletion of magnesium, can be explained in terms of an earlier generation of stars polluting the presently observed ones. It was shown that the potential range of temperatures and densities of the polluting sites depends on the strength of a few number of critical reaction rates. The reaction has been identified as one of these important reactions. [Purpose] The key ingredient for evaluating the thermonuclear reaction rate is the strength of the resonances which, at low energy, are proportional to their proton width. Therefore the goal of this work is to determine the proton widths of unbound 31P states. [Method] States in 31P were studied at the Maier-Leibnitz-Laboratorium using the one-proton transfer reaction. Deuterons were detected with the Q3D magnetic spectrometer. Angular distribution and spectroscopic factors were extracted for 27 states, and proton widths and resonance strengths were calculated for the unbound states. [Results] Several unbound states have been observed for the first time in a one-proton transfer reaction. Above 20 MK, the reaction rate is now entirely estimated from the observed properties of states. The reaction rate uncertainty from all resonances other than the resonance has been reduced down to less than a factor of two above that temperature. The unknown spin and parity of the resonance dominates the uncertainty in the rate in the relevant temperature range. [Conclusion] The remaining source of uncertainty on the reaction rate comes from the unknown spin and parity of the resonance which can change the reaction rate by a factor of ten in the temperature range of interest.

Read this paper on arXiv…

D. Harrouz, N. Séréville, P. Adsley, et. al.
Tue, 11 Jan 22
37/95

Comments: N/A

Nuclear mass table in deformed relativistic Hartree-Bogoliubov theory in continuum: I. even-even nuclei [CL]

Posted on by

http://arxiv.org/abs/2201.03216


Ground-state properties of even-even nuclei with $8\le Z\le120$ from the proton drip line to the neutron drip line have been investigated using the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) with the density functional PC-PK1. With the effects of deformation and continuum included simultaneously, 2583 even-even nuclei are predicted to be bound. The calculated binding energies, two-nucleon separation energies, root-mean-square (rms) radii of neutron, proton, matter, and charge distributions, quadrupole deformations, and neutron and proton Fermi surfaces are tabulated and compared with available experimental data. The rms deviation from the 637 mass data is 1.518 MeV, providing one of the best microscopic descriptions for nuclear masses. The drip lines obtained from DRHBc calculations are compared with other calculations, including the spherical relativistic continuum Hartree-Bogoliubov (RCHB) and triaxial relativistic Hartree-Bogoliubov (TRHB) calculations with PC-PK1. The deformation and continuum effects on the limits of the nuclear landscape are discussed. Possible peninsulas consisting of bound nuclei beyond the two-neutron drip line are predicted. The systematics of the two-nucleon separation energies, two-nucleon gaps, rms radii, quadrupole deformations, potential energy curves, neutron densities, neutron mean-field potentials, and pairing energies in the DRHBc calculations are also discussed. In addition, the $\alpha$ decay energies extracted are in good agreement with available data.

Read this paper on arXiv…

D. Collaboration, K. Zhang, M. Cheoun, et. al.
Tue, 11 Jan 22
79/95

Comments: 217 pages, 15 figures, 2 tables, accepted for publication in Atomic Data and Nuclear Data Tables, data file in the TXT form is available for download under “Ancillary files”

Fieldable Muon Momentum Measurement using Coupled Pressurized Gaseous Cherenkov Detectors [CL]

Posted on by

http://arxiv.org/abs/2201.02591


Cosmic ray muons present a large part of the radiation background and depending on the application of interest muons can be seen as background noise, e.g., radiation mapping, radiation protection, dosimetry, or as a useful interrogation probe such as cosmic ray muon tomography. It is worth noting recent developments on muon scattering tomography which has emerged as a prospective noninvasive monitoring method for many applications including spent nuclear fuel cask monitoring and geotomography. However, it is still very challenging to measure muon momentum in the field, despite the apparent benefits, without resorting to large and expensive calorimeters, ring imagers, or time of flight detectors. Recent efforts at CNL and INFN have developed large prototypes based on multiple Coulomb scattering coupled with the muon momentum reconstruction algorithms. While these efforts show promise, no portable detectors exist that can measure muon momentum in the field. In this work, we present a new concept for measuring muon momentum using coupled pressurized gaseous Cherenkov radiators. By carefully selecting the gas pressure at each radiator we can optimize the muon momentum threshold for which a muon signal will be detected. This way, a muon passing through the radiators will only trigger those radiators with momentum threshold less than the actual muon momentum. By measuring the presence of Cherenkov signals in each radiator, our system can then estimate the muon momentum. The primary benefit of such a concept is that it can be compact and portable enough so that it can be deployed in the field separately or in combination with existing tomography systems.

Read this paper on arXiv…

J. Bae and S. Chatzidakis
Mon, 10 Jan 22
16/49

Comments: Transactions of American Nuclear Society Winter meeting, 125 (1), 400-403, 2021

Fieldable muon spectrometer using multi-layer pressurized gas Cherenkov radiators and its applications [CL]

Posted on by

http://arxiv.org/abs/2201.00253


Cosmic ray muons have been considered as a non-conventional radiation probe in various applications. To utilize cosmic ray muons in engineering applications, two important quantities, trajectory and momentum, must be known. The muon trajectories are easily reconstructed using two-fold detector arrays with a high spatial resolution. However, precise measurement of muon momentum is difficult to be achieved without deploying large and expensive spectrometers such as solenoid magnets. Here, we propose a new method to estimate muon momentum using multi-layer pressurized gas Cherenkov radiators. This is accurate, portable, compact (< 1m3), and easily coupled with existing muon detectors without the need of neither bulky magnetic nor time-of-flight spectrometers. The results show that not only our new muon spectrometer can measure muon momentum with a resolution of +-0.5 GeV/c in a momentum range of 0.1 to 10.0 GeV/c, but also we can reconstruct cosmic muon spectrum with high accuracy (~90%).

Read this paper on arXiv…

J. Bae and S. Chatzidakis
Tue, 4 Jan 22
3/58

Comments: N/A

Future radioisotope measurements to clarify the origin of deep-ocean 244Pu [HEAP]

Posted on by

http://arxiv.org/abs/2112.09607


244Pu has been discovered in deep-ocean deposits spanning the past 10 Myr, a period that includes two 60Fe pulses from nearby supernovae. 244Pu is among the heaviest $r$-process products, and we consider whether the 244Pu was created in the supernovae, which is disfavored by model calculations, or in an earlier kilonova that seeded 244Pu in the nearby interstellar medium, which was subsequently swept up by the supernova debris. We propose probing these possibilities by measuring other $r$-process radioisotopes such as 129I and 182Hf in deep-ocean deposits and in lunar regolith.

Read this paper on arXiv…

X. Wang, A. Clark, J. Ellis, et. al.
Mon, 20 Dec 21
13/59

Comments: 7 pages, 3 figures, 1 table, comments welcome

First application of mass measurement with the Rare-RI Ring reveals the solar r-process abundance trend at A=122 and A=123 [CL]

Posted on by

http://arxiv.org/abs/2112.05312


The Rare-RI Ring (R3) is a recently commissioned cyclotron-like storage ring mass spectrometer dedicated to mass measurements of exotic nuclei far from stability at Radioactive Isotope Beam Factory (RIBF) in RIKEN. The first application of mass measurement using the R3 mass spectrometer at RIBF is reported. Rare isotopes produced at RIBF, $^{127}$Sn, $^{126}$In, $^{125}$Cd, $^{124}$Ag, $^{123}$Pd, were injected in R3. Masses of $^{126}$In, $^{125}$Cd, and $^{123}$Pd were measured and the mass uncertainty of $^{123}$Pd was improved. The impact of the new $^{123}$Pd result on the solar $r$-process abundances in a neutron star merger event is investigated by performing reaction network calculations of 20 trajectories with varying electron fraction $Y_e$. It is found that the neutron capture cross section on $^{123}$Pd increases by a factor of 2.2 and $\beta$-delayed neutron emission probability, $P_{1n}$, of $^{123}$Rh increases by 14\%. The neutron capture cross section on $^{122}$Pd decreases by a factor of 2.6 leading to pileup of material at $A=122$, thus reproducing the trend of the solar $r$-process abundances. Furthermore, the nuclear deformation predicted to reach its maximum before $N=82$ in the Pd isotopic chain is examined. The new mass measurement shows no evidence of such large deformation, though, experimental uncertainty should be further improved to draw a definitive conclusion. This is the first reported measurement with a new storage ring mass spectrometery technique realized at a heavy-ion cyclotron and employing individual injection of the pre-identified rare nuclei. The latter is essential for the future mass measurements of the rarest isotopes produced at RIBF.

Read this paper on arXiv…

H. Li, S. Naimi, T. Sprouse, et. al.
Mon, 13 Dec 21
20/70

Comments: N/A

Translating neutron star observations to nuclear symmetry energy via artificial neural networks [CL]

Posted on by

http://arxiv.org/abs/2112.04089


One of the most significant challenges involved in efforts to understand the equation of state of dense neutron-rich matter is the uncertain density dependence of the nuclear symmetry energy. Because of its broad impact, pinning down the density dependence of the nuclear symmetry energy has been a longstanding goal of both nuclear physics and astrophysics. Recent observations of neutron stars, in both electromagnetic and gravitational-wave spectra, have already constrained significantly the nuclear symmetry energy at high densities. Training deep neural networks to learn a computationally efficient representation of the mapping between astrophysical observables of neutron stars, such as masses, radii, and tidal deformabilities, and the nuclear symmetry energy allows its density dependence to be determined reliably and accurately. In this work we use a deep learning approach to determine the nuclear symmetry energy as a function of density directly from observational neutron star data. We show for the first time that artificial neural networks can precisely reconstruct the nuclear symmetry energy from a set of available neutron star observables, such as, masses and radii as those measured by, e.g., the NICER mission, or masses and tidal deformabilities as measured by the LIGO/VIRGO/KAGRA gravitational-wave detectors. These results demonstrate the potential of artificial neural networks to reconstruct the symmetry energy, and the equation of state, directly from neutron star observational data, and emphasize the importance of the deep learning approach in the era of Multi-Messenger Astrophysics.

Read this paper on arXiv…

P. Krastev
Thu, 9 Dec 21
16/63

Comments: 16 pages, 6 figures. Invited article for Galaxies for the Special Issue “Neutron Stars and Hadrons in the Era of Gravitational Wave Astrophysics”

Ab initio predictions link the neutron skin of ${}^{208}$Pb to nuclear forces [CL]

Posted on by

http://arxiv.org/abs/2112.01125


Heavy atomic nuclei have an excess of neutrons over protons. This leads to the formation of a neutron skin whose thickness, $R_\mathrm{skin}$, is sensitive to details of the nuclear force — linking atomic nuclei to properties of neutron stars, thereby relating objects that differ in size by 18 orders of magnitude [1, 2]. ${}^{208}$Pb is of particular interest here because it exhibits a simple structure and is accessible to experiment. However, computing such a heavy nucleus has been out of reach for ab initio theory. By combining advances in quantum many-body methods, statistical tools, and emulator technology, we make quantitative predictions for the properties of ${}^{208}$Pb starting from nuclear forces that are consistent with symmetries of low-energy quantum chromodynamics. We explore $10^9$ different nuclear-force parameterisations via history matching, confront them with data in select light nuclei, and arrive at an importance-weighted ensemble of interactions. We accurately reproduce bulk properties of ${}^{208}$Pb and find $R_\mathrm{skin}({}^{208}\mathrm{Pb}) = 0.14-0.20$ fm which is smaller than a recent extraction from parity-violating electron scattering [3] but in agreement with other experimental probes. The allowable range of $R_\mathrm{skin}({}^{208}\mathrm{Pb})$ is significantly constrained by nucleon-nucleon scattering data, ruling out very thick skins. This work demonstrates that nuclear forces constrained to light systems extrapolate reliably to even the heaviest nuclei, and that we can make quantitative predictions across the nuclear landscape.

Read this paper on arXiv…

B. Hu, W. Jiang, T. Miyagi, et. al.
Fri, 3 Dec 21
33/81

Comments: N/A

Perturbative and non-perturbative effects in ultraperipheral production of lepton pairs [CL]

Posted on by

http://arxiv.org/abs/2112.00358


Perturbative and non-perturbative terms of the cross sections of ultraperipheral production of lepton pairs in ion collisions are taken into account. It is shown that production of low-mass $e^+e^-$ pairs is strongly enhanced (compared to perturbative estimates) due to the non-perturbative Sommerfeld-Gamow-Sakharov (SGS) factor. Coulomb attraction of the non-relativistic components of those pairs leads to the finite value of their mass distribution at lowest relative velocities. Their annihilation can result in the increased intensity of 511 keV photons. It can be recorded at the NICA collider and is especially crucial in astrophysical implications regarding the 511 keV line emitted from the Galactic center. The analogous effect can be observed in lepton pairs production at LHC. Energy spectra of lepton pairs created in ultraperipheral nuclear collisions and their transverse momenta are calculated.

Read this paper on arXiv…

I. Dremin
Fri, 3 Dec 21
60/81

Comments: 9 p., 2 Figs. arXiv admin note: text overlap with arXiv:2008.13184, arXiv:2101.04679

Statistical Hauser-Feshbach model description of $(n,α)$ reaction cross sections for s-process nuclei [CL]

Posted on by

http://arxiv.org/abs/2111.14980


The $(n,\alpha)$ reaction contributes in many processes of energy generation and nucleosynthesis in stellar environment. Since experimental data are available for a limited number of nuclei and in restricted energy ranges, at present only theoretical studies can provide predictions for all astrophysically relevant $(n,\alpha)$ reaction cross sections. The purpose of this work is to study $(n,\alpha)$ reaction cross sections for a set of nuclei contributing in the s-process nucleosynthesis. Theory framework is based on the statistical Hauser-Feshbach model implemented in TALYS code and supplemented with nuclear properties based on Skyrme energy density functional. In addition to the analysis of the properties of calculated $(n,\alpha)$ cross sections, the Mawellian averaged cross sections are described and analyzed for the range of temperatures in stellar environment. Model calculations determined astrophysically relevant energy windows in which $(n,\alpha)$ reactions occur in massive stars. In order to reduce the uncertainties in modeling $(n,\alpha)$ reaction cross sections for the s-process, novel experimental studies are called for. The results on the predicted relevant $(n,\alpha)$ reaction energy windows for the s-process nuclei provide a guidance for the priority energy ranges for the future experimental studies.

Read this paper on arXiv…

S. Küçüksucu, M. Yiğit and N. Paar
Wed, 1 Dec 21
59/110

Comments: 25 pages, 9 figures