Tag Archives: Applied Physics

An evolutionary model for V404 Cyg system [SSA]

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http://arxiv.org/abs/2304.12894


V404 Cyg is a Low Mass X-Ray Binary (LMXB) system that has undergone outbursts in 1938, 1989, and 2015. During these events, it has been possible to determine relevant data of the system; such as the masses of the compact object (a black hole, BH) and its companion, the orbital period, the companion spectral type, and luminosity class, among others. Remarkably, the companion star has a metallicity appreciably higher than solar. All these data allow us to construct theoretical models to account for its structure, looking for its initial configuration and predicting its final fate. Assuming that the BH is already formed when the primary star reaches the Zero Age Main Sequence, we used our binary evolution code for such a purpose. We obtained that the present characteristics of the system are nicely accounted for by a model with initial masses of 9 solar masses for the BH, 1.5 solar masses for the companion star, an initial orbital period of 1.5 d and considering that at most 30% of the mass transferred by the donor is accreted by the BH. The metallicity of the donor for our best fit was Z = 0.028 (twice solar metallicity). We also studied the evolution of the BH spin parameter assuming that initially, it is not rotating. Remarkably, the spin of the BHs in our models is far from reaching the available observational determination. This may indicate that the BH in V404 Cyg is initially spinning, a result that may be relevant for understanding the formation BHs in the context of LMXB systems.

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L. Koninckx, M. Vito and O. Benvenuto
Wed, 26 Apr 23
21/62

Comments: 10 pages, 12 figures

A superconducting nanowire photon number resolving four-quadrant detector-based Gigabit deep-space laser communication receiver prototype [CL]

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http://arxiv.org/abs/2212.04927


Deep space explorations require transferring huge amounts of data quickly from very distant targets. Laser communication is a promising technology that can offer a data rate of magnitude faster than conventional microwave communication due to the fundamentally narrow divergence of light. This study demonstrated a photon-sensitive receiver prototype with over Gigabit data rate, immunity to strong background photon noise, and simultaneous tracking ability. The advantages are inherited from a joint-optimized superconducting nanowire single-photon detector (SNSPD) array, designed into a four-quadrant structure with each quadrant capable of resolving six photons. Installed in a free-space coupled and low-vibration cryostat, the system detection efficiency reached 72.7%, the detector efficiency was 97.5%, and the total photon counting rate was 1.6 Gcps. Additionally, communication performance was tested for pulse position modulation (PPM) format. A series of signal processing methods were introduced to maximize the performance of the forward error correction (FEC) code. Consequently, the receiver exhibits a faster data rate and better sensitivity by about twofold (1.76 photons/bit at 800 Mbps and 3.40 photons/bit at 1.2 Gbps) compared to previously reported results (3.18 photon/bit at 622 Mbps for the Lunar Laser Communication Demonstration). Furthermore, communications in strong background noise and with simultaneous tracking ability were demonstrated aimed at the challenges of daylight operation and accurate tracking of dim beacon light in deep space scenarios.

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H. Hao, Q. Zhao, Y. Huang, et. al.
Mon, 12 Dec 22
2/52

Comments: N/A

Electron polarization in ultrarelativistic plasma current filamentation instabilities [CL]

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http://arxiv.org/abs/2212.03303


Plasma current filamentation of an ultrarelativistic electron beam impinging on an overdense plasma is investigated, with emphasis on radiation-induced electron polarization. Particle-in-cell simulations provide the classification and in-depth analysis of three different regimes of the current filaments, namely, the normal filament, abnormal filament, and quenching regimes. We show that electron radiative polarization emerges during the instability along the azimuthal direction in the momentum space, which significantly varies across the regimes. We put forward an intuitive Hamiltonian model to trace the origin of the electron polarization dynamics. In particular, we discern the role of nonlinear transverse motion of plasma filaments, which induces asymmetry in radiative spin flips, yielding an accumulation of electron polarization. Our results break the conventional perception that quasi-symmetric fields are inefficient for generating radiative spin-polarized beams, suggesting the potential of electron polarization as a source of new information on laboratory and astrophysical plasma instabilities.

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Z. Gong, K. Hatsagortsyan and C. Keitel
Thu, 8 Dec 22
11/63

Comments: 7 pages, 5 figures

Design of The Kinetic Inductance Detector Based Focal Plane Assembly for The Terahertz Intensity Mapper [IMA]

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http://arxiv.org/abs/2211.09351


We report on the kinetic inductance detector (KID) array focal plane assembly design for the Terahertz Intensity Mapper (TIM). Each of the 2 arrays consists of 4 wafer-sized dies (quadrants), and the overall assembly must satisfy thermal and mechanical requirements, while maintaining high optical efficiency and a suitable electromagnetic environment for the KIDs. In particular, our design manages to strictly maintain a 50 $\mathrm{\mu m}$ air gap between the array and the horn block. We have prototyped and are now testing a sub-scale assembly which houses a single quadrant for characterization before integration into the full array. The initial test result shows a $>$95\% yield, indicating a good performance of our TIM detector packaging design.

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L. Liu, R. Janssen, C. Bradford, et. al.
Fri, 18 Nov 22
35/70

Comments: 8 pages, 6 figures, accepted for publication in Journal of Low Temperature Physics

Design and testing of Kinetic Inductance Detector package for the Terahertz Intensity Mapper [IMA]

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http://arxiv.org/abs/2211.09308


The Terahertz Intensity Mapper (TIM) is designed to probe the star formation history in dust-obscured star-forming galaxies around the peak of cosmic star formation. This will be done via measurements of the redshifted 157.7 um line of singly ionized carbon ([CII]). TIM employs two R $\sim 250$ long-slit grating spectrometers covering 240-420 um. Each is equipped with a focal plane unit containing 4 wafer-sized subarrays of horn-coupled aluminum kinetic inductance detectors (KIDs). We present the design and performance of a prototype focal plane assembly for one of TIM’s KID-based subarrays. Our design strictly maintain high optical efficiency and a suitable electromagnetic environment for the KIDs. The prototype detector housing in combination with the first flight-like quadrant are tested at 250 mK. Initial frequency scan shows that many resonances are affected by collisions and/or very shallow transmission dips as a result of a degraded internal quality factor (Q factor). This is attributed to the presence of an external magnetic field during cooldown. We report on a study of magnetic field dependence of the Q factor of our quadrant array. We implement a Helmholtz coil to vary the magnetic field at the detectors by (partially) nulling earth’s. Our investigation shows that the earth magnetic field can significantly affect our KIDs’ performance by degrading the Q factor by a factor of 2-5, well below those expected from the operational temperature or optical loading. We find that we can sufficiently recover our detectors’ quality factor by tuning the current in the coils to generate a field that matches earth’s magnetic field in magnitude to within a few uT. Therefore, it is necessary to employ a properly designed magnetic shield enclosing the TIM focal plane unit. Based on the results presented in this paper, we set a shielding requirement of |B| < 3 uT.

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L. Liu, R. Janssen, C. Bradford, et. al.
Fri, 18 Nov 22
40/70

Comments: 8 pages, 5 figures, to be published in conference proceedings of SPIE Astronomical Telescopes + Instrumentation 2022

GENESIS: Co-location of Geodetic Techniques in Space [CL]

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http://arxiv.org/abs/2209.15298


Improving and homogenizing time and space reference systems on Earth and, more directly, realizing the Terrestrial Reference Frame (TRF) with an accuracy of 1mm and a long-term stability of 0.1mm/year are relevant for many scientific and societal endeavors. The knowledge of the TRF is fundamental for Earth and navigation sciences. For instance, quantifying sea level change strongly depends on an accurate determination of the geocenter motion but also of the positions of continental and island reference stations, as well as the ground stations of tracking networks. Also, numerous applications in geophysics require absolute millimeter precision from the reference frame, as for example monitoring tectonic motion or crustal deformation for predicting natural hazards. The TRF accuracy to be achieved represents the consensus of various authorities which has enunciated geodesy requirements for Earth sciences.
Today we are still far from these ambitious accuracy and stability goals for the realization of the TRF. However, a combination and co-location of all four space geodetic techniques on one satellite platform can significantly contribute to achieving these goals. This is the purpose of the GENESIS mission, proposed as a component of the FutureNAV program of the European Space Agency. The GENESIS platform will be a dynamic space geodetic observatory carrying all the geodetic instruments referenced to one another through carefully calibrated space ties. The co-location of the techniques in space will solve the inconsistencies and biases between the different geodetic techniques in order to reach the TRF accuracy and stability goals endorsed by the various international authorities and the scientific community. The purpose of this white paper is to review the state-of-the-art and explain the benefits of the GENESIS mission in Earth sciences, navigation sciences and metrology.

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P. Delva, Z. Altamimi, A. Blazquez, et. al.
Mon, 3 Oct 22
38/55

Comments: 31 pages, 9 figures, submitted to Earth, Planets and Space (EPS)

Towards photophoretically levitating macroscopic sensors in the stratosphere [CL]

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http://arxiv.org/abs/2209.08093


Photophoretic forces could levitate thin 10 centimeter-scale structures in Earth$’$s stratosphere indefinitely. We develop models of the thermal transpiration lofting force on a bilayer sandwich structure under stratospheric conditions driven by radiative fluxes in the thermal-infrared and solar-band. Similar structures have been levitated in the laboratory. Lofting is maximized when the layers are separated by an air gap equal to the mean free path (MFP), when about half of the layers$’$ surface area consists of holes with radii < MFP, and when the top layer is solar-transmissive and infrared-emissive while the bottom layer is solar-absorptive and infrared-transmissive. We describe a preliminary design of a 10 cm diameter device that combines a levitating structure made of two membranes 2 $\mu$m apart with the support structure required for stiffness and orientation control. We limit the design to components that could be fabricated with available methods. Structural analysis suggests that the device would have sufficient strength to withstand forces that might be encountered in transport, deployment, and flight. Our models predict a payload capacity of about 300 mg at 25 km altitude and our analysis suggests it could support bidirectional radio communication at over 10 Mb/s and could have limited navigational abilities. Such devices could be useful for atmospheric science or telecommunications, and similar devices might be useful on Mars. Structures a few times larger might have payloads of a few grams.

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B. Schafer, J. Kim, J. Vlassak, et. al.
Tue, 20 Sep 22
4/81

Comments: Main: 14 pages, 4 figures. Supporting information: 7 pages, 13 figures

Swarm of lightsail nanosatellites for Solar System exploration [CL]

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http://arxiv.org/abs/2208.10980


This paper presents a study for the realization of a space mission which employs nanosatellites driven by an external laser source impinging on an optimized lightsail, as a valuable technology to launch swarms of spacecrafts into the Solar System. Nanosatellites propelled by laser can be useful for the heliosphere exploration and for planetary observation, if suitably equipped with sensors, or be adopted for the establishment of network systems when placed into specific orbits. By varying the area-to-mass ratio (i.e., the ratio between the sail area and the payload weight) and the laser power, it is possible to insert the spacecraft into different hyperbolic orbits with respect to Earth, thus reaching the target by means of controlled trajectories in a relatively short amount of time. A mission involving nanosatellites of the order of 1 kg of mass is envisioned, by describing all the on-board subsystems and satisfying all the requirements in term of power and mass budget. Particular attention is paid to the telecommunication subsystem, which must offer all the necessary functionalities. To fabricate the lightsail, the thin films technology has been considered, by verifying the sail thermal stability during the thrust phase. Moreover, the problem of mechanical stability of the lightsail has been tackled, showing that the distance between the ligthsail structure and the payload plays a pivotal role. Some potential applications of the proposed technology are discussed, such as the mapping of the heliospheric environment.

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G. Santi, A. Corso, D. Garoli, et. al.
Wed, 24 Aug 22
62/67

Comments: N/A

LeXInt: Package for Exponential Integrators employing Leja interpolation [CL]

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http://arxiv.org/abs/2208.08269


We present a publicly available software for exponential integrators that computes the $\varphi_l(z)$ functions using polynomial interpolation. The interpolation method at Leja points have recently been shown to be competitive with the traditionally-used Krylov subspace method. The developed framework facilitates easy adaptation into any Python software package for time integration.

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P. Deka, L. Einkemmer and M. Tokman
Thu, 18 Aug 22
19/45

Comments: Publicly available software available at this https URL, in submission

Model for Nitric oxide and its dayglow emission in the Martian upper atmosphere using NGIMS/MAVEN measured neutral and ion densities [EPA]

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http://arxiv.org/abs/2203.15403


A comprehensive study of Nitric oxide (NO) chemistry in the Martian upper atmosphere is restricted due to the lack of requisite measurements. NO is an abundant form of odd nitrogen species in the Martian lower atmosphere and its density depends on several photochemical processes. We have developed a photochemical model to study the NO density in the dayside of Martian upper atmosphere by accounting for various production and loss mechanisms. By utilizing the Neutral Gas and Ion Mass Spectrometer (NGIMS) on-board Mars Atmosphere and Volatile Evolution (MAVEN) mission measured neutral and ion densities during deep dip 8 and 9 campaigns, we modelled NO number density in the Martian sunlit upper atmosphere for the altitudes between 120 and 200 km. The modelled NO densities are employed to calculate NO (1,0) gamma band emission intensity profiles in the dayside upper atmosphere of Mars. The calculated NO density and its gamma band intensity profiles are found to be consistent with Imaging Ultraviolet Spectrograph (IUVS) onboard MAVEN observations and also with other modelling studies. We found that the local CO2 and N2 density variations can lead to a change in NO density and consequently its dayglow intensity by a factor of 2 to 5. Since NO is a trace constituent and also its dayglow emissions are strongly obscured by CO Cameron band emissions, we suggest that the derivation of NO number density based on our approach can constrain its abundance in the dayside upper atmosphere of Mars. More observations of (1-0) gamma band emission along with modelling will help to study the global distribution of NO in the Martian atmosphere.

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S. Raghuram, A. Bhardwaj and M. Dharwan
Wed, 30 Mar 22
5/77

Comments: 13 pages, 10 Figures, 2 Tables

Generating Realistic Two-Line Elements for Notional Space Vehicles and Constellations [EPA]

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http://arxiv.org/abs/2203.04204


As space becomes increasingly populated with new satellites and systems, modeling and simulating existing and future systems becomes more important. The two-line element set has been a standard format for sharing data about a satellite’s orbit since the 1960s, and well-developed algorithms can predict the future location of satellites based on this data. In order to simulate potential future systems, especially when mixed with existing systems, data must be generated to represent the desired orbits. We present a means to create two-line element sets with parameters that closely resemble real satellite behavior, and rely on a novel approach to calculate the mean motion for even greater accuracy.

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T. Rockwood, G. Steeger and M. Stein
Wed, 9 Mar 22
67/68

Comments: 8 pages, 4 figures

Measuring Electric Dipole Moments of Trapped Sub-mm Particles [CL]

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http://arxiv.org/abs/2202.01979


We present a method for measurements of electric dipole moments on (sub)-mm size (basalt) particles levitated in an acoustic trap and centered within a plate capacitor. If an electric field is applied the particles oscillate with specific frequencies due to their permanent dipole moments. We observe dipole moments on the order of $D_P = 10^{-15} … 10^{-14} \rm \, C \, m $. The dipole moment increases in small aggregates with the number of grains and is larger for samples vibrated (tribocharged) before trapping. The basalt grains show no sign of change in their dipole moment during measurements, implying a timescale for charge mobility being at least larger than minutes.

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F. Onyeagusi, J. Teiser, N. Schneider, et. al.
Mon, 7 Feb 22
1/46

Comments: N/A

MICROSCOPE Mission scenario, ground segment and data processing [IMA]

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http://arxiv.org/abs/2201.10841


Testing the Weak Equivalence Principle (WEP) to a precision of $10^{-15}$ requires a quantity of data that give enough confidence on the final result: ideally, the longer the measurement the better the rejection of thestatistical noise. The science sessions had a duration of 120 orbits maximum and were regularly repeated and spaced out to accommodate operational constraints but also in order to repeat the experiment in different conditions and to allow time to calibrate the instrument. Several science sessions were performed over the 2.5 year duration of the experiment. This paper aims to describe how the data have been produced on the basis of a mission scenario and a data flow process, driven by a tradeoff between the science objectives and the operational constraints. The mission was led by the Centre National d’Etudes Spatiales (CNES) which provided the satellite, the launch and the ground operations. The ground segment was distributed between CNES and Office National d’Etudes et de Recherches A\’erospatiales (ONERA). CNES provided the raw data through the Centre d’Expertise de Compensation de Tra\^{i}n\'{e}e (CECT: Drag-free expertise centre). The science was led by the Observatoire de la C\^ote d{‘}Azur (OCA) and ONERA was in charge of the data process. The latter also provided the instrument and the Science Mission Centre of MICROSCOPE (CMSM).

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M. Rodrigues, P. Touboul, G. Métris, et. al.
Thu, 27 Jan 22
17/44

Comments: To be released in special MICROSCOPE edition of CQG

MICROSCOPE: systematic errors [IMA]

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http://arxiv.org/abs/2112.10559


The MICROSCOPE mission aims to test the Weak Equivalence Principle (WEP) in orbit with an unprecedented precision of 10$^{-15}$ on the E\”otv\”os parameter thanks to electrostatic accelerometers on board a drag-free micro-satellite. The precision of the test is determined by statistical errors, due to the environment and instrument noises, and by systematic errors to which this paper is devoted. Systematic error sources can be divided into three categories: external perturbations, such as the residual atmospheric drag or the gravity gradient at the satellite altitude, perturbations linked to the satellite design, such as thermal or magnetic perturbations, and perturbations from the instrument internal sources. Each systematic error is evaluated or bounded in order to set a reliable upper bound on the WEP parameter estimation uncertainty.

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M. Rodrigues, P. Touboul1, G. Metris, et. al.
Tue, 21 Dec 21
7/86

Comments: To be released in CQG MICROSCOPE Special Edition

Daily monitoring of scattered light noise due to microseismic variability at the Virgo interferometer [IMA]

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http://arxiv.org/abs/2112.06046


Data acquired by the Virgo interferometer during the second part of the O3 scientific run, referred to as O3b, were analysed with the aim of characterising the onset and time evolution of scattered light noise in connection with the variability of microseismic noise in the environment surrounding the detector. The adaptive algorithm used, called pytvfemd, is suitable for the analysis of time series which are both nonlinear and nonstationary. It allowed to obtain the first oscillatory mode of the differential arm motion degree of freedom of the detector during days affected by scattered light noise. The mode’s envelope i.e., its instantaneous amplitude, is then correlated with the motion of the West end bench, a known source of scattered light during O3. The relative velocity between the West end test mass and the West end optical bench is used as a predictor of scattered light noise. Higher values of correlation are obtained in periods of higher seismic noise in the microseismic frequency band. This is also confirmed by the signal-to-noise ratio (SNR) of scattered light glitches from GravitySpy for the January-March 2020 period. Obtained results suggest that the adopted methodology is suited for scattered light noise characterisation and monitoring in gravitational wave interferometers.

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A. Longo, S. Bianchi, G. Valdes, et. al.
Tue, 14 Dec 21
29/98

Comments: N/A

Deciphering in situ electron dynamics of ultrarelativistic plasma via polarization pattern of emitted gamma photons [CL]

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http://arxiv.org/abs/2111.00563


Understanding and interpretation of the dynamics of ultrarelativistic plasma is a challenge, which calls for the development of methods for in situ probing the plasma dynamical characteristics. We put forward a new probing method, harnessing polarization properties of $\gamma$-photons spontaneously emitted from a non-prepolarized plasma irradiated by a circularly polarized strong laser pulse. We show that the temporal and angular pattern of $\gamma$-photon linear polarization is explicitly correlated with the instantaneous dynamics of the radiating electrons, which provides information on the laser-plasma interaction regime. Furthermore, with the $\gamma$-photon circular polarization originated from the electron radiative spin-flips, the plasma susceptibility to quantum electrodynamical processes is gauged. Our study demonstrates that the polarization signal of emitted $\gamma$-photons from ultrarelativistic plasma can be a versatile information source, which would be beneficial for the research fields of laser-driven plasma, accelerator science, and laboratory astrophysics.

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Z. Gong, K. Hatsagortsyan and C. Keitel
Tue, 2 Nov 21
7/93

Comments: N/A

Dodgeball — Can a Satellite Avoid Being Hit by Debris? [EPA]

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http://arxiv.org/abs/2110.03113


Can a satellite dodge a collision with untracked orbiting debris? Can a satellite dodge collision with a tracked object, making only the avoidance man{\oe}uvers actually required to avoid collision, despite the uncertainties of predicted conjunctions? Satellite-borne radar may distinguish actual collision threats from the much greater number of near misses because an object on a collision course has constant bearing, which may be determined by interferometric detection of the radar return. A large constellation of such radars may enable the determination of the ephemerides of all cm-sized debris in LEO.

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J. Katz
Fri, 8 Oct 21
41/70

Comments: 14 pp., 2 figs

Piezo-deformable Mirrors for Active Mode Matching in Advanced LIGO [IMA]

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http://arxiv.org/abs/2110.00674


The detectors of the laser interferometer gravitational-wave observatory (LIGO) are broadly limited by the quantum noise and rely on the injection of squeezed states of light to achieve their full sensitivity. Squeezing improvement is limited by mode mismatch between the elements of the squeezer and the interferometer. In the current LIGO detectors, there is no way to actively mitigate this mode mismatch. This paper presents a new deformable mirror for wavefront control that meets the active mode matching requirements of advanced LIGO. The active element is a piezo-electric transducer, which actuates on the radius of curvature of a 5 mm thick mirror via an axisymmetric flexure. The operating range of the deformable mirror is 120+-8 mD in vacuum, with an additional 200 mD adjustment range accessible out of vacuum. The scattering into higher-order modes is measured to be <0.2% over the nominal beam radius. These piezo-deformable mirrors meet the stringent noise and vacuum requirements of advanced LIGO and will be used for the next observing run (O4) to control the mode-matching between the squeezer and the interferometer.

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V. Srivastava, G. Mansell, C. Makarem, et. al.
Tue, 5 Oct 21
60/72

Comments: N/A

Colour remote sensing of the impact of artificial light at night (II): Calibration of DSLR-based images from the International Space Station [IMA]

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http://arxiv.org/abs/2108.07050


Nighttime images taken with DSLR cameras from the International Space Station (ISS) can provide valuable information on the spatial and temporal variation of artificial nighttime lighting on Earth. In particular, this is the only source of historical and current visible multispectral data across the world (DMSP/OLS and SNPP/VIIRS-DNB data are panchromatic and multispectral in the infrared but not at visible wavelengths). The ISS images require substantial processing and proper calibration to exploit intensities and ratios from the RGB channels. Here we describe the different calibration steps, addressing in turn Decodification, Linearity correction (ISO dependent), Flat field/Vignetting, Spectral characterization of the channels, Astrometric calibration/georeferencing, Photometric calibration (stars)/Radiometric correction (settings correction – by exposure time, ISO, lens transmittance, etc) and Transmittance correction (window transmittance, atmospheric correction). We provide an example of the application of this processing method to an image of Spain.

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A. Miguel, J. Zamorano, M. Aubé, et. al.
Tue, 17 Aug 21
47/56

Comments: N/A

Clean energy from dark matter? [CL]

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http://arxiv.org/abs/2107.14300


A contribution to Frank Wilczek’s 70th birthday’s festschrift, this brief note considers how much power can be extracted from dark matter.

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P. Sikivie
Mon, 2 Aug 21
10/82

Comments: 5 pages, no figures

Fibre Fabry-Pérot Astrophotonic Correlation Spectroscopy for Remote Gas Identification and Radial Velocity Measurements [IMA]

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http://arxiv.org/abs/2107.04494


We present a novel remote gas detection and identification technique based on correlation spectroscopy with a piezoelectric tunable fibre-optic Fabry-P\’erot filter. We show that the spectral correlation amplitude between the filter transmission window and gas absorption features is related to the gas absorption optical depth, and that different gases can be distinguished from one another using their correlation signal phase. Using an observed telluric-corrected, high-resolution near-infrared spectrum of Venus, we show via simulation that the Doppler shift of gases lines can be extracted from the phase of the lock-in signal using low-cost, compact, and lightweight fibre-optic components with lock-in amplification to improve the signal-to-noise ratio. This correlation spectroscopy technique has applications in the detection and radial velocity determination of faint spectral features in astronomy and remote sensing. We experimentally demonstrate remote CO2 detection system using a lock-in amplifier, fibre-optic Fabry-P\’erot filter, and single channel photodiode.

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R. Cheriton, A. Densmore, S. Sivanandam, et. al.
Mon, 12 Jul 21
49/49

Comments: N/A

CONCERTO at APEX: installation and technical commissioning [IMA]

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http://arxiv.org/abs/2106.14028


We describe the deployment and first tests on Sky of CONCERTO, a large field-of-view (18.6arc-min) spectral-imaging instrument. The instrument operates in the range 130-310GHz from the APEX 12-meters telescope located at 5100m a.s.l. on the Chajnantor plateau. Spectra with R=1-300 are obtained using a fast (2.5Hz mechanical frequency) Fourier Transform Spectrometer (FTS), coupled to a continuous dilution cryostat with a base temperature of 60mK. Two 2152-pixels arrays of Lumped Element Kinetic Inductance Detectors (LEKID) are installed in the cryostat that also contains the cold optics and the front-end electronics. CONCERTO, installed in April 2021, generates more than 20k spectra per second during observations. We describe the final development phases, the installation and the first results obtained on Sky.

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A. Monfardini, A. Beelen, A. Benoit, et. al.
Tue, 29 Jun 21
77/101

Comments: Submitted to JLTP, Proceedings if the Low Temperature Detectors 19 conference, NIST, 2021

An analytic solution for evaluating the magnetic field induced from an arbitrary, asymmetric ocean world [EPA]

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http://arxiv.org/abs/2106.10878


Magnetic investigations of icy moons have provided some of the most compelling evidence available confirming the presence of subsurface, liquid water oceans. In the exploration of ocean moons, especially Europa, there is a need for mathematical models capable of predicting the magnetic fields induced under a variety of conditions, including in the case of asymmetric oceans. Existing models are limited to either spherical symmetry or assume an ocean with infinite conductivity. In this work, we derive an analytic result capable of determining the induced magnetic moments for an arbitrary, layered body. Crucially, we find that degree-2 tidal deformation results in changes to the induced dipole moments. We demonstrate application of our results to models of plausible asymmetry from the literature within the oceans of Europa and Miranda and the ionospheres of Callisto and Triton. For the models we consider, we find that in the asymmetric case, the induced magnetic field differs by more than 2 nT near the surface of Europa, 0.25$-$0.5 nT at 1 $R$ above Miranda and Triton, and is essentially unchanged for Callisto. For Miranda and Triton, this difference is as much as 20$-$30% of the induced field magnitude. If measurements near the moons can be made precisely to better than a few tenths of a nT, these values may be used by future spacecraft investigations to characterize asymmetry within the interior of icy moons.

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M. Styczinski, S. Vance, E. Harnett, et. al.
Tue, 22 Jun 21
54/71

Comments: Submitted to Icarus. Supplemental Material available at: this https URL (software), this https URL (animations)

Efficient Computation of $N$-point Correlation Functions in $D$ Dimensions [IMA]

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http://arxiv.org/abs/2106.10278


We present efficient algorithms for computing the $N$-point correlation functions (NPCFs) of random fields in arbitrary $D$-dimensional homogeneous and isotropic spaces. Such statistics appear throughout the physical sciences, and provide a natural tool to describe a range of stochastic processes. Typically, NPCF estimators have $\mathcal{O}(n^N)$ complexity (for a data set containing $n$ particles); their application is thus computationally infeasible unless $N$ is small. By projecting onto a suitably-defined angular basis, we show that the estimators can be written in separable form, with complexity $\mathcal{O}(n^2)$, or $\mathcal{O}(n_{\rm g}\log n_{\rm g})$ if evaluated using a Fast Fourier Transform on a grid of size $n_{\rm g}$. Our decomposition is built upon the $D$-dimensional hyperspherical harmonics; these form a complete basis on the $(D-1)$-sphere and are intrinsically related to angular momentum operators. Concatenation of $(N-1)$ such harmonics gives states of definite combined angular momentum, forming a natural separable basis for the NPCF. In particular, isotropic correlation functions require only states with zero combined angular momentum. We provide explicit expressions for the NPCF estimators as applied to both discrete and gridded data, and discuss a number of applications within cosmology and fluid dynamics. The efficiency of such estimators will allow higher-order correlators to become a standard tool in the analysis of random fields.

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O. Philcox and Z. Slepian
Tue, 22 Jun 21
62/71

Comments: 12 pages, 2 figures, submitted to PNAS. Comments welcome!

Quasiballistic electron transport in cryogenic SiGe HBTs studied using an exact, semi-analytic solution to the Boltzmann equation [CL]

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http://arxiv.org/abs/2106.05374


Silicon-germanium heterojunction bipolar transistors (HBTs) are of interest as low-noise microwave amplifiers due to their competitive noise performance and low cost relative to III-V devices. The fundamental noise performance limits of HBTs are thus of interest, and several studies report that quasiballistic electron transport across the base is a mechanism leading to cryogenic non-ideal IV characteristics that affects these limits. However, this conclusion has not been rigorously tested against theoretical predictions because prior studies modeled electron transport with empirical approaches or approximate solutions of the Boltzmann equation. Here, we study non-diffusive transport in narrow-base SiGe HBTs using an exact, semi-analytic solution of the Boltzmann equation based on an asymptotic expansion approach. We find that the computed transport characteristics are inconsistent with experiment, implying that quasiballistic electron transport is unlikely to be the origin of cryogenic non-ideal IV characteristics. Our work helps to identify the mechanisms governing the lower limits of the microwave noise figure of cryogenic HBT amplifiers.

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N. Naik and A. Minnich
Mon, 14 Jun 21
37/58

Comments: N/A

Picosecond Laser Ablation of Millimeter-Wave Subwavelength Structures on Alumina and Sapphire [CL]

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http://arxiv.org/abs/2103.06974


We use a 1030 nm laser with 7 ps pulse duration and average power up to 100 W to ablate pyramid-shape subwavelength structures (SWS) on alumina and sapphire. The SWS give an effective and cryogenically robust anti-reflection coating in the millimeter-wave band. We demonstrate average ablation rate of up to 34 mm$^3$/min and 20 mm$^3$/min for structure heights of 900 $\mu$m and 750 $\mu$m on alumina and sapphire, respectively. These rates are a factor of 34 and 9 higher than reported previously on similar structures. We propose a model that relates structure height to cumulative laser fluence. The model depends on the absorption length $\delta$, which is assumed to depend on peak fluence, and on the threshold fluence $\phi_{th}$. Using a best-fit procedure we find an average $\delta = 630$ nm and 650 nm, and $\phi_{th} = 2.0^{+0.5}{-0.5}$ J/cm$^2$ and $2.3^{+0.1}{-0.1}$ J/cm$^2$ for alumina and sapphire, respectively, for peak fluence values between 30 and 70 J/cm$^{2}$. With the best fit values, the model and data values for cumulative fluence agree to within 10%. Given inputs for $\delta$ and $\phi_{th}$ the model is used to predict average ablation rates as a function of SWS height and average laser power.

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Q. Wen, E. Fadeeva, S. Hanany, et. al.
Mon, 15 Mar 21
31/36

Comments: 15 pages, 11 figures, submitted to Optics & Laser Technology

X-ray verification of sol-gel resist shrinkage in substrate-conformal imprint lithography for a replicated blazed reflection grating [CL]

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http://arxiv.org/abs/2011.14771


Surface-relief gratings fabricated through nanoimprint lithography (NIL) are prone to topographic distortion induced by resist shrinkage. Characterizing the impact of this effect on blazed diffraction efficiency is particularly important for applications in astrophysical spectroscopy at soft x-ray wavelengths ($\lambda \approx 0.5 – 5$~nm) that call for the mass-production of large-area grating replicas with sub-micron, sawtooth surface-relief profiles. A variant of NIL that lends itself well for this task is substrate-conformal imprint lithography (SCIL), which uses a flexible, composite stamp formed from a rigid master template to imprint nanoscale features in an inorganic resist that cures thermodynamically through a silica sol-gel process. While SCIL enables the production of several hundred imprints before stamp degradation and avoids many of the detriments associated with large-area imprinting in NIL, the sol-gel resist suffers shrinkage dependent on the post-imprint cure temperature. Through atomic force microscopy and diffraction-efficiency testing at beamline 6.3.2 of the Advanced Light Source, the impact of this effect on blaze response is constrained for a $\sim$160-nm-period grating replica cured at 90$^{\circ}$C. Results demonstrate a $\sim$2$^{\circ}$ reduction in blaze angle relative to the master grating, which was fabricated by anisotropic wet etching in $\langle 311 \rangle$-oriented silicon to yield a facet angle close to 30$^{\circ}$.

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J. McCoy, M. Verschuuren, D. Miles, et. al.
Tue, 1 Dec 20
7/108

Comments: 17 pages, 11 figures

Wide Field Spectral Imaging with Shifted Excitation Raman Difference Spectroscopy Using the Nod and Shuffle Technique [CL]

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http://arxiv.org/abs/2011.13736


Wide field Raman imaging using the integral field spectroscopy approach was used as a fast, one shot imaging method for the simultaneous collection of all spectra composing a Raman image. For the suppression of autofluorescence and background signals such as room light, shifted excitation Raman difference spectroscopy (SERDS) was applied to remove background artifacts in Raman spectra. To reduce acquisition times in wide field SERDS imaging, we adapted the nod and shuffle technique from astrophysics and implemented it into a wide field SERDS imaging setup. In our adapted version, the nod corresponds to the change in excitation wavelength, whereas the shuffle corresponds to the shifting of charges up and down on a Charge-Coupled Device (CCD) chip synchronous to the change in excitation wavelength. We coupled this improved wide field SERDS imaging setup to diode lasers with 784.4/785.5 and 457.7/458.9 nm excitation and applied it to samples such as paracetamol and aspirin tablets, polystyrene and polymethyl methacrylate beads, as well as pork meat using multiple accumulations with acquisition times in the range of 50 to 200 ms. The results tackle two main challenges of SERDS imaging: gradual photobleaching changes the autofluorescence background, and multiple readouts of CCD detector prolong the acquisition time.

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F. Korinth, E. Schmälzlin, C. Stiebing, et. al.
Mon, 30 Nov 20
116/117

Comments: Accepted and Published by “Sensors” Journal, 19 pages, 8 figures

Event Selection and Background Rejection in Time Projection Chambers Using Convolutional Neural Networks and a Specific Application to the AdEPT Gamma-ray Polarimeter Mission [IMA]

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http://arxiv.org/abs/2011.07136


The Advanced Energetic Pair Telescope gamma-ray polarimeter uses a time projection chamber for measuring pair production events and is expected to generate a raw instrument data rate four orders of magnitude greater than is transmittable with typical satellite data communications. GammaNet, a convolutional neural network, proposes to solve this problem by performing event classification on-board for pair production and background events, reducing the data rate to a level that can be accommodated by typical satellite communication systems. In order to train GammaNet, a set of 1.1×10^6 pair production events and 10^6 background events were simulated for the Advanced Energetic Pair Telescope using the Geant4 Monte Carlo code. An additional set of 10^3 pair production and 10^5 background events were simulated to test GammaNet’s capability for background discrimination. With optimization, GammaNet has achieved the proposed background rejection requirements for Galactic Cosmic Ray proton events. Given the best case assumption for downlink speeds, signal sensitivity for pair production ranged between 1.1 +/- 0.5% to 69 +/- 2% for 5 and 250 MeV incident gamma rays. This range became 0.1 +/- 0.1% to 17 +/- 2% for the worst case scenario of downlink speeds. The application of a feature visualization algorithm to GammaNet demonstrated decreased response to electronic noise and events exiting or entering the frame and increased response to parallel tracks that are close in proximity. GammaNet has been successfully implemented and shows promising results.

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R. Garnett, S. Byun, A. Hanu, et. al.
Tue, 17 Nov 20
23/83

Comments: Citation: Richard L. Garnett, Soo Hyun Byun, Andrei R. Hanu, Stanley D. Hunter, Event selection and background rejection in time projection chambers using convolutional neural networks and a specific application to the AdEPT gamma-ray polarimeter mission, NIM A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2020, 164860, ISSN 0168-9002, 10.1016/j.nima.2020.164860

Mid-infrared single photon detector with superconductor Mo$_{80}$Si$_{20}$ nanowire [CL]

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http://arxiv.org/abs/2011.06699


A mid-infrared single photon detector (MIR-SNSPD) was reported based on 30 nm-wide superconductor molybdenum silicide nanowires in this work. Saturated quantum efficiencies (QEs) were achieved at the wavelength ranging from 1.55 to 5.07 micrometer in experiments. At the same time, the intrinsic dark count rate (DCR) was below 100 cps. Thus, this device produced a noise equivalent power (NEP) of 4.5 * 10-19 W/sqrt(Hz). The results provide the foundation of developing 10 micrometer-SNSPD for the applications of infrared astronomy observation.

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Q. Chen, R. Ge, L. Zhang, et. al.
Mon, 16 Nov 20
20/57

Comments: N/A

Modeling light-controlled actuation of flexible magnetic composite structures using the finite element method (FEM) [CL]

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http://arxiv.org/abs/2009.01510


Photoactive materials hold great promise for a variety of applications. We present a finite element model of light-controlled flexible magnetic composite structure composed of 33.3% Chromium dioxide (CrO2) and 66.7% Polydimethylsiloxane (PDMS) by weight. The structure has a dimension of 8 mm x 2 mm x 100 um and has been previously experimentally studied. Due to the low Curie temperature, the structure acts as an actuator, shows significant deflection under the external magnetic field and relaxation due to laser heating. Thermal and magnetic deflection analysis has been performed using the FEM model. The simulation results show a maximum structural deflection of 6.08 mm (76% of the length of the structure) when subjected to 30 mT magnetic flux density and 160 mW laser power at 303 K (room temperature). We will present the results of the simulation model and comparison to experimental data reproducing the previously observed motion of the (CrO2+PDMS). This model will enable future fracture and fatigue analysis as well as extension to new photoactive geometries.

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A. Jha, M. Li, E. Douglas, et. al.
Fri, 4 Sep 20
-1396/65

Comments: 12 pages, 10 figures, published in Proceedings Volume 11477, Molecular and Nano Machines III; 1147704 (2020), Event: SPIE Organic Photonics + Electronics, 2020, Online Only

Modeling Aerial Gamma-Ray Backgrounds using Non-negative Matrix Factorization [IMA]

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http://arxiv.org/abs/2002.10440


Airborne gamma-ray surveys are useful for many applications, ranging from geology and mining to public health and nuclear security. In all these contexts, the ability to decompose a measured spectrum into a linear combination of background source terms can provide useful insights into the data and lead to improvements over techniques that use spectral energy windows. Multiple methods for the linear decomposition of spectra exist but are subject to various drawbacks, such as allowing negative photon fluxes or requiring detailed Monte Carlo modeling. We propose using Non-negative Matrix Factorization (NMF) as a data-driven approach to spectral decomposition. Using aerial surveys that include flights over water, we demonstrate that the mathematical approach of NMF finds physically relevant structure in aerial gamma-ray background, namely that measured spectra can be expressed as the sum of nearby terrestrial emission, distant terrestrial emission, and radon and cosmic emission. These NMF background components are compared to the background components obtained using Noise-Adjusted Singular Value Decomposition (NASVD), which contain negative photon fluxes and thus do not represent emission spectra in as straightforward a way. Finally, we comment on potential areas of research that are enabled by NMF decompositions, such as new approaches to spectral anomaly detection and data fusion.

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M. Bandstra, T. Joshi, K. Bilton, et. al.
Tue, 25 Feb 20
26/76

Comments: 14 pages, 12 figures, accepted for publication in IEEE Transactions on Nuclear Science

Suppressed-gap millimetre wave kinetic inductance detectors using DC-bias current [IMA]

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http://arxiv.org/abs/2001.09089


In this study, we evaluate the suitability of using DC-biased aluminium resonators as low-frequency kinetic inductance detectors capable of operating in the frequency range of 50 – 120 GHz. Our analysis routine for supercurrent-biased resonators is based on the Usadel equations and gives outputs including density of states, complex conductivities, transmission line properties, and quasiparticle lifetimes. Results from our analysis confirm previous experimental observations on resonant frequency tuneability and retention of high quality factor. Crucially, our analysis suggests that DC-biased resonators demonstrate significantly suppressed superconducting density of states gap. Consequently these resonators have lower frequency detection threshold and are suitable materials for low-frequency kinetic inductance detectors.

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S. Zhao, S. Withington, D. Goldie, et. al.
Mon, 27 Jan 20
40/54

Comments: N/A

Multi-line single point coronal magnetometry [SSA]

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http://arxiv.org/abs/2001.06123


Polarized magnetic dipole (M1) emission lines provide important diagnostics for the magnetic field dominating the evolution of the solar corona. This paper advances a multi-line technique using specific combinations of M1 lines to infer the full vector magnetic field for regions of optically thin emission that can be localized along a given line of sight. Our analytical formalism is a generalization of the “single-point inversion” approach introduced by Plowman. We show that combinations of M1 transitions for which each is either a $J=1\rightarrow0$ transition or has equal Land\’e g-factors for the upper and lower levels contain degenerate spectropolarimetric information that prohibits the application of the single-point inversion technique. This may include the pair of infrared Fe XIII lines discussed by Plowman. We identify the Fe XIII 1074.7 nm and Si X 1430.1 nm lines as one alternative combination for implementing this technique. Our sensitivity analysis, based on coronal loop properties, suggests that for photon noise levels around $10^{-4}$ of the line intensity, which will be achievable with the National Science Foundation’s Daniel K. Inouye Solar Telescope, magnetic fields with sufficient strength (${\sim}10$ G) and not severely inclined to the line-of-sight ($\lesssim 35^{\circ}$) can be recovered with this method. Degenerate solutions exist; though, we discuss how added constraints may help resolve them or reduce their number.

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G. Dima and T. Schad
Mon, 20 Jan 20
13/60

Comments: N/A

Multi-line single point coronal magnetometry [SSA]

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http://arxiv.org/abs/2001.06123


Polarized magnetic dipole (M1) emission lines provide important diagnostics for the magnetic field dominating the evolution of the solar corona. This paper advances a multi-line technique using specific combinations of M1 lines to infer the full vector magnetic field for regions of optically thin emission that can be localized along a given line of sight. Our analytical formalism is a generalization of the “single-point inversion” approach introduced by Plowman. We show that combinations of M1 transitions for which each is either a $J=1\rightarrow0$ transition or has equal Land\’e g-factors for the upper and lower levels contain degenerate spectropolarimetric information that prohibits the application of the single-point inversion technique. This may include the pair of infrared Fe XIII lines discussed by Plowman. We identify the Fe XIII 1074.7 nm and Si X 1430.1 nm lines as one alternative combination for implementing this technique. Our sensitivity analysis, based on coronal loop properties, suggests that for photon noise levels around $10^{-4}$ of the line intensity, which will be achievable with the National Science Foundation’s Daniel K. Inouye Solar Telescope, magnetic fields with sufficient strength (${\sim}10$ G) and not severely inclined to the line-of-sight ($\lesssim 35^{\circ}$) can be recovered with this method. Degenerate solutions exist; though, we discuss how added constraints may help resolve them or reduce their number.

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G. Dima and T. Schad
Mon, 20 Jan 20
33/60

Comments: N/A

Permittivity and permeability of epoxy-magnetite powder composites at microwave frequencies [CL]

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http://arxiv.org/abs/2001.02336


Radio, millimetre and sub-millimetre astronomy experiments as well as remote sensing applications often require castable absorbers with well known electromagnetic properties to design and realize calibration targets. In this context, we fabricated and characterized two samples using different ratios of two easily commercially available materials: epoxy (Stycast 2850FT) and magnetite ($\mathrm{Fe_{3}O_{4}}$) powder. We performed transmission and reflection measurements from 7 GHz up to 170 GHz with a VNA equipped with a series of standard horn antennas. Using an empirical model we analysed the data to extract complex permittivity and permeability from transmission data; then we used reflection data to validate the results. In this paper we present the sample fabrication procedure, analysis method, parameter extraction pipeline, and results for two samples with different epoxy-powder mass ratios.

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T. Ghigna, M. Zannoni, M. Jones, et. al.
Thu, 9 Jan 20
52/61

Comments: 7 pages, 18 figures, submitted to the Journal of Applied Physics (AIP)

Production Method of Millimeter-Wave Absorber with 3D-Printed Mold [IMA]

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http://arxiv.org/abs/2001.00517


We established a production method of a good millimeter-wave absorber by using a 3D-printed mold. The mold has a periodic pyramid shape, and an absorptive material is filled into the mold. This shape reduces the surface reflection. The 3D-printed mold is made from a transparent material in the millimeter-wave range. Therefore, unmolding is not necessary. A significant benefit of this production method is easy prototyping with various shapes and various absorptive materials. We produced a test model and used a two-component epoxy encapsulant as the absorptive material. The test model achieved a low reflectance: $\sim 1\%$ at 100 GHz. The absorber is sometimes maintained at a low temperature condition for cases in which superconducting detectors are used. Therefore, cryogenic performance is required in terms of a mechanical strength for the thermal cycles, an adhesive strength, and a sufficient thermal conductivity. We confirmed the test-model strength by immersing the model into a liquid-nitrogen bath.

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S. Adachi, M. Hattori, F. Kanno, et. al.
Fri, 3 Jan 20
34/45

Comments: 3 pages, 8 figures

Laser-Driven High-Velocity Microparticle Launcher In Atmosphere And Under Vacuum [IMA]

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http://arxiv.org/abs/1911.11572


This paper presents a novel approach to launch single microparticles at high velocities under low vacuum conditions. In an all-optical table-top method, microparticles with sizes ranging from a few microns to tens of microns are accelerated to supersonic velocities depending on the particle mass. The acceleration is performed through a laser ablation process and the particles are monitored in free space using an ultra-high-speed multi-frame camera with nanosecond time resolution. Under low vacuum, we evaluate the current platform performance by measuring particle velocities for a range of particle types and sizes, and demonstrate blast wave suppression and drag reduction under vacuum. Showing an impact on polyethylene, we demonstrate the capability of the experimental setup to study materials behavior under high-velocity impact. The present method is relevant to space applications, particularly to rendezvous missions where velocities range from tens of m/s to a few km/s, as well as to a wide range of terrestrial applications including impact bonding and impact-induced erosion.

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D. Veysset, Y. Sun, S. Kooi, et. al.
Wed, 27 Nov 19
50/59

Comments: 13 pages, 9 figures, keywords: high-velocity launcher; microparticle impact; high-speed imaging; low vacuum; laser-based method; table-top system; ejecta; drag; blast; ballistic limit

NIEL Dose Analysis on triple and single junction InGaP/GaAs/Ge solar cells irradiated with electrons, protons and neutrons [CL]

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http://arxiv.org/abs/1911.08900


Triple junction (InGaP/GaAs/Ge) and single junction (SJ) solar cells were irradiated with electrons, protons and neutrons. The degradation of remaining factors was analyzed as function of the induced Displacement Damage Dose (DDD) calculated by means of the SR-NIEL (Screened Relativistic Non Ionizing\ Energy Loss) approach. In particular, the aim of this work is to analyze the variation of the solar cells remaining factors due to neutron irradiation with respect to those previously obtained with electrons and protons. The current analysis confirms that the degradation of the $P_{max}$ electrical parameter is related by means of the usual semi-empirical expression to the displacement dose, independently of type of the incoming particle. $I_{sc}$ and $V_{oc}$ parameters were also measured as a function of the displacement damage dose. Furthermore, a DLTS analysis was carried out on diodes – with the same epitaxial structure as the middle sub-cell – irradiated with neutrons.

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R. Campesato, C. Baur, M. Carta, et. al.
Thu, 21 Nov 19
11/57

Comments: N/A

Convection-Caused Symmetry Breaking of Azimuthal Magnetorotational Instability in a Liquid Metal Taylor-Couette Flow [CL]

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http://arxiv.org/abs/1910.11640


We report the results of a liquid metal Taylor-Couette experiment in the Rayleigh-stable regime under the influence of an azimuthal magnetic field. We observe that the resulting azimuthal magnetorotational instability (AMRI) from our experimental setup is significantly influenced by the thermal boundary conditions. Even a minimal radial heat flux leads to a symmetry breaking, which results in the AMRI waves traveling either upwards or downwards. We identify the thermal radiation by the central axial current as the heat source responsible for vertical convection in the liquid. Preliminary numerical investigations point towards an interaction between AMRI and thermal convection, which supports our experimental findings.

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M. Seilmayer, J. Ogbonna and F. Stefani
Mon, 28 Oct 19
40/40

Comments: N/A

Initial Assessment of Monocrystalline Silicon Solar Cells as Large-Area Sensors for Precise Flux Calibration [IMA]

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http://arxiv.org/abs/1909.13346


As the precision frontier of large-area survey astrophysics advances towards the one millimagnitude level, flux calibration of astronomical instrumentation remains an ongoing challenge. We describe initial testing of silicon solar cells as large-aperture precise calibration photodiodes. We present measurements of dark current, linearity, frequency response, spatial response uniformity, and noise characteristics of the Sunpower C60 solar cells, an interdigitated back-contact 125mm x 125mm monocrystalline solar cell. We find that these devices hold considerable promise as large-area flux calibration sensors and warrant further characterization.

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S. Brownsberger, N. Mondrik and C. Stubbs
Tue, 1 Oct 19
73/90

Comments: N/A

Suppressing parametric instabilities in LIGO using low-noise acoustic mode dampers [CL]

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http://arxiv.org/abs/1909.07805


Interferometric gravitational-wave detectors like LIGO need to be able to measure changes in their arm lengths of order $10^{-18}~$m or smaller. This requires very high laser power in order to raise the signal above shot noise. One significant limitation to increased laser power is an opto-mechanical interaction between the laser field and the detector’s test masses that can form an unstable feedback loop. Such parametric instabilities have long been studied as a limiting effect at high power, and were first observed to occur in LIGO in 2014. Since then, passive and active means have been used to avoid these instabilities, though at power levels well below the final design value. Here we report on the successful implementation of tuned, passive dampers to tame parametric instabilities in LIGO. These dampers are applied directly to all interferometer test masses to reduce the quality factors of their internal vibrational modes, while adding a negligible amount of noise to the gravitational-wave output. In accordance with our model, the measured mode quality factors have been reduced by at least a factor of ten with no visible increase in the interferometer’s thermal noise level. We project that these dampers should remove most of the parametric instabilities in LIGO when operating at full power, while limiting the concomitant increase in thermal noise to approximately 1%.

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S. Biscans, S. Gras, C. Blair, et. al.
Wed, 18 Sep 19
4/64

Comments: 11 pages, 8 figures

Atomic Layer Deposition Niobium Nitride Films for High-Q Resonators [IMA]

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http://arxiv.org/abs/1908.07146


Niobium nitride (NbN) is a useful material for fabricating detectors because of its high critical temperature and relatively high kinetic inductance. In particular, NbN can be used to fabricate nanowire detectors and mm-wave transmission lines. When deposited, NbN is usually sputtered, leaving room for concern about uniformity at small thicknesses. We present Atomic Layer Deposition niobium nitride (ALD NbN) as an alternative technique that allows for precision control of deposition parameters such as film thickness, stage temperature, and nitrogen flow. Atomic-scale control over film thickness admits wafer-scale uniformity for films 4-30 nm thick; control over deposition temperature gives rise to growth rate changes, which can be used to optimize film thickness and critical temperature. In order to characterize ALD NbN in the radio-frequency regime, we construct single-layer microwave resonators and test their performance as a function of stage temperature and input power. ALD processes can admit high resonator quality factors, which in turn increase detector multiplexing capabilities. We present measurements of the critical temperature and internal quality factor of ALD NbN resonators under the variation of ALD parameters.

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C. Sheagren, A. Anferov, P. Barry, et. al.
Wed, 21 Aug 19
36/78

Comments: N/A

Experimental Study of a Planar-integrated Dual-Polarization Balanced SIS Mixer [IMA]

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http://arxiv.org/abs/1908.06564


A dual-polarization balanced superconductor-insulator-superconductor mixer operating at 2 mm wavelength is realized in form of a monolithic planar integrated circuit. Planar orthomode transducers and LO couplers are enabled by using silicon membranes that are locally formed on the silicon-on-insulator substrate. The performance of the balanced mixer is experimentally investigated. Over the entire RF band (125-163 GHz), the balanced mixer shows an LO noise rejection ratio about 15 dB, an overall receiver noise about 40 K, and a cross-polarization <-20 dB. The demonstrated compactness and the performance of the integrated circuit indicate that this approach is feasible in developing heterodyne focal plane arrays.

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W. Shan, S. Ezaki, K. Kaneko, et. al.
Tue, 20 Aug 19
39/86

Comments: Accepted for publication in IEEE Transactions on Terahertz Science and Technology

Response to 'Room Temperature, Quantum-Limited THz Heterodyne Detection? Not Yet' [IMA]

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http://arxiv.org/abs/1908.05140


This commentary is written in response to arXiv:1907.13198. In this article, Zmuidzinas et al. raise questions about the results reported by our group in Nature Astronomy (DOI: 10.1038/s41550-019-0828-6) regarding our experimental methodology and our device performance metrics. As described in this Response, Zmuidzinas et al. have unfortunately missed some basic principles on impedance matching and the physics of photomixers and plasmonics that are at the heart of their categorical conclusions. Here, we correct these misunderstandings and discharge all of their flawed conclusions. Therefore, all of the results and conclusions reported in our Nature Astronomy manuscript remain correct, as before.

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M. Jarrahi and Y. Lin
Thu, 15 Aug 19
68/69

Comments: 7 pages, 2 figures. arXiv admin note: text overlap with arXiv:1907.13198

Application Usability Levels: A Framework for Tracking Project Product Progress [IMA]

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http://arxiv.org/abs/1907.08663


The space physics community continues to grow and become both more interdisciplinary and more intertwined with commercial and government operations. This has created a need for a framework to easily identify what projects can be used for specific applications and how close the tool is to routine autonomous or on-demand implementation and operation. We propose the Application Usability Level (AUL) framework and publicizing AULs to help the community quantify the progress of successful applications, metrics, and validation efforts. This framework will also aid the scientific community by supplying the type of information needed to build off of previously published work and publicizing the applications and requirements needed by the user communities. In this paper, we define the AUL framework, outline the milestones required for progression to higher AULs, and provide example projects utilizing the AUL framework. This work has been completed as part of the activities of the Assessment of Understanding and Quantifying Progress working group which is part of the International Forum for Space Weather Capabilities Assessment.

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A. Halford, A. Kellerman, K. Garcia-Sage, et. al.
Tue, 23 Jul 19
70/72

Comments: N/A

The $Iκεα$ model of feedback-regulated galaxy formation [GA]

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http://arxiv.org/abs/1906.10135


We present the $I\kappa\epsilon\alpha$ model of galaxy formation, in which a galaxy’s star formation rate is set by the balance between energy injected by feedback from massive stars and energy lost by the deepening of the potential of its host dark matter halo due to cosmological accretion. Such a balance is secularly stable provided that the star formation rate increases with the pressure in the star forming gas. The $I\kappa\epsilon\alpha$ model has four parameters that together control the feedback from star formation and the cosmological accretion rate onto a halo. $I\kappa\epsilon\alpha$ reproduces accurately the star formation rate as a function of halo mass and redshift in the EAGLE hydrodynamical simulation, even when all four parameters are held constant. It predicts the emergence of a star forming main sequence along which the specific star formation rate depends weakly on stellar mass with an amplitude that increases rapidly with redshift. We briefly discuss the emerging mass-metallicity relation, the evolution of the galaxy stellar mass function, and an extension of the model that includes feedback from active galactic nuclei (AGN). These self-regulation results are independent of the star formation law and the galaxy’s gas content. Instead, star forming galaxies are shaped by the balance between stellar feedback and cosmological accretion, with accurately accounting for energy losses associated with feedback a crucial ingredient.

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M. Sharma and T. Theuns
Wed, 26 Jun 19
59/68

Comments: 20 pages, 16 figures, submitted to MNRAS, comments welcome

Design of Near Infrared and Visible Kinetic Inductance Detectors Using MIM Capacitors [IMA]

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http://arxiv.org/abs/1901.10193


We are developing superconducting Microwave Kinetic Inductance Detectors to operate at near infrared and optical wavelengths for astronomy. In order to efficiently meet with the requirements of astronomical applications, we propose to replace the interdigitated capacitor by a metal, insulator, metal capacitor which has the advantage of presenting a larger capacitance value within a much smaller space. The pixel will occupy a space of typically 100 micrometers by 85 micrometers which is nine times less than a typical pixel size using the interdigitated capacitor operating at the same frequency, below 2 GHz.

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S. Beldi, F. Boussaha, C. Chaumont, et. al.
Wed, 30 Jan 19
24/54

Comments: N/A

Perspectives on Astrophysics Based on Atomic, Molecular, and Optical (AMO) Techniques [CL]

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http://arxiv.org/abs/1811.06157


About two generations ago, a large part of AMO science was dominated by experimental high energy collision studies and perturbative theoretical methods. Since then, AMO science has undergone a transition and is now dominated by quantum, ultracold, and ultrafast studies. But in the process, the field has passed over the complexity that lies between these two extremes. Most of the Universe resides in this intermediate region. We put forward that the next frontier for AMO science is to explore the AMO complexity that describes most of the Cosmos.

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D. Savin, J. Babb, P. Bellan, et. al.
Fri, 16 Nov 18
2/78

Comments: White paper submission to the Decadal Assessment and Outlook Report on Atomic, Molecular, and Optical (AMO) Science (AMO 2020)

Extreme background-rejection techniques for the ELROI optical satellite license plate [IMA]

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http://arxiv.org/abs/1810.01438


The Extremely Low-Resource Optical Identifier (ELROI) is a concept for an autonomous, low-power optical “license plate” that can be attached to anything that goes into space. ELROI uses short, omnidirectional flashes of laser light to encode a unique ID number which can be read by a small ground telescope using a photon-counting sensor and innovative extreme background-rejection techniques. ELROI is smaller and lighter than a typical radio beacon, low-power enough to run on its own small solar cell, and can safely operate for the entire orbital lifetime of a satellite or debris object. The concept has been validated in ground tests, and orbital prototypes are scheduled for launch in 2018 and beyond. In this paper we focus on the details of the encoding scheme and data analysis that allow a milliwatt optical signal to be read from orbit. We describe the techniques of extreme background-rejection needed to achieve this, including spectral filtering and temporal filtering using a period- and phase-recovery algorithm, and discuss the requirements for an error-correcting code to encode the ID number. Worked examples with both simulated and experimental (long-range ground test) data illustrate the methods used. We present these techniques to describe a new optical communication concept, and to encourage others to consider observing and analyzing our upcoming test flights.

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R. Holmes and D. Palmer
Thu, 4 Oct 18
22/72

Comments: 29 pages, 15 figures, in submission to Applied Optics

Visible-spanning flat supercontinuum for astronomical applications [IMA]

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http://arxiv.org/abs/1807.07857


We demonstrate a broad, flat visible supercontinuum spectrum that is generated by a dispersion-engineered tapered photonic crystal fiber pumped by a 1 GHz repetition rate turn-key Ti:sapphire laser outputting $\sim$ 30 fs pulses at 800 nm. At a pulse energy of 100 pJ, we obtain an output spectrum that is flat to within 3 dB over the range 490-690 nm with a blue tail extending below 450 nm. The mode-locked laser combined with the photonic crystal fiber forms a simple visible frequency comb system that is extremely well-suited to the precise calibration of astrophysical spectrographs, among other applications.

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A. Ravi, M. Beck, D. Phillips, et. al.
Mon, 23 Jul 18
33/48

Comments: 7 pages, 5 figures

Addressing environmental and atmospheric challenges for capturing high-precision thermal infrared data in the field of astro-ecology [IMA]

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http://arxiv.org/abs/1807.03157


Using thermal infrared detectors mounted on drones, and applying techniques from astrophysics, we hope to support the field of conservation ecology by creating an automated pipeline for the detection and identification of certain endangered species and poachers from thermal infrared data. We test part of our system by attempting to detect simulated poachers in the field. Whilst we find that we can detect humans hiding in the field in some types of terrain, we also find several environmental factors that prevent accurate detection, such as ambient heat from the ground, absorption of infrared emission by the atmosphere, obscuring vegetation and spurious sources from the terrain. We discuss the effect of these issues, and potential solutions which will be required for our future vision for a fully automated drone-based global conservation monitoring system.

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C. Burke, M. Rashman, O. McAree, et. al.
Tue, 10 Jul 18
61/79

Comments: Published in Proceedings of SPIE Astronomical Telescopes and Instrumentation 2018. 8 pages, 3 figures

Dynamics of supernova bounce in laboratory [CL]

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http://arxiv.org/abs/1806.05398


We draw attention to recent High Explosive (HE) experiments which provide compression of macroscopic amount of matter to high, even record, values of pressure in comparison with other HE experiments. The observed bounce after the compression corresponds to processes in core-collapse supernova explosions after neutrino trapping. Conditions provided in the experiments resemble those in core-collapse supernovae, permitting to use them for laboratory astrophysics. A unique feature of the experiments is compression at low entropy. The values of specific entropy are close to those obtained in numerical simulations during the process of collapse in supernovae explosions, and much lower than obtained at laser ignition facilities, another type of high-compression experiments. Both in supernovae and HE experiments the bounce undergoes at low entropy, so the HE experiments provide a new platform to realize some supernova collapse effects in laboratory, especially to study hydrodynamics of collapsing flows and the bounce. Due to good resolution of diagnostics in the compression of macroscopic amounts of material with essential effects of non-ideal plasma in EOS, and observed development of 3D instabilities, these experiments may serve as a useful benchmark for astrophysical hydrodynamic codes.

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S. S.I.Blinnikov, R. R.I.Ilkaev, M. M.A.Mochalov, et. al.
Fri, 15 Jun 18
21/54

Comments: 13 pages, 8 figures, submitted to Phys.Rev.E

Theoretical compensation of static deformations of freeform multi mirror substrates [CL]

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http://arxiv.org/abs/1805.12036


Varying temperatures influence the figure errors of freeform metal mirrors by thermal expansion. Furthermore, different materials lead to thermo-elastic bending effects. The article presents a derivation of a compensation approach for general static loads. Utilizing perturbation theory this approach works for shape compensation of substrates which operate in various temperature environments. Verification is made using a finite element analysis which is further used to produce manufacturable CAD models. The remaining low spatial frequency errors are deterministically correctable using diamond turning or polishing techniques.

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J. Hartung, H. Lukowicz and J. Kinast
Thu, 31 May 18
24/45

Comments: 16 pages, published version

Energy Loss Due to Defect Formation from $^{206}$Pb Recoils in SuperCDMS Germanium Detectors [CL]

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http://arxiv.org/abs/1805.09942


The Super Cryogenic Dark Matter Search experiment (SuperCDMS) at the Soudan Underground Laboratory studied energy loss associated with Frenkel defect formation in germanium crystals at mK temperatures using in situ $^{210}$Pb sources. We examine the spectrum of $^{206}$Pb nuclear recoils near its expected 103 keV endpoint energy and determine an energy loss of $\left(6.08\pm0.18\right)$ %, which we attribute to defect formation. From this result and using TRIM simulations, we extract the first experimentally determined average displacement threshold energy of $\left(19.7^{+0.6}_{-0.5}\right)$ eV for germanium. This has implications for the analysis thresholds of future germanium-based dark matter searches.

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R. Agnese, T. Aralis, T. Aramaki, et. al.
Mon, 28 May 18
30/47

Comments: 4 Figures

Tunable sub-gap radiation detection with superconducting resonators [CL]

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http://arxiv.org/abs/1802.10379


We have fabricated planar amorphous Indium Oxide superconducting resonators ($T_c\sim2.8$ K) that are sensitive to frequency-selective radiation in the range of 7 to 10 GHz. Those values lay far below twice the superconducting gap that worths about 200 GHz. The photons detection consists in a shift of the fundamental resonance frequency. We show that the detected frequency can be adjusted by modulating the total length of the superconducting resonator. We attribute those observations to the excitation of higher-order resonance modes. The coupling between the fundamental lumped and the higher order distributed resonance is due to the kinetic inductance non-linearity with current. These devices, that we have called Sub-gap Kinetic Inductance Detectors (SKIDs), are to be distinguished from the standard Kinetic Inductance Detectors (KIDs) in which quasi-particles are generated when incident light breaks down Cooper pairs.

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O. Dupre, A. Calvo, A. Catalano, et. al.
Thu, 1 Mar 18
43/66

Comments: article: 6 pages, 4 figures supplementary: 1 page, 2 figures

Accuracy of Flight Altitude Measured with Low-Cost GNSS, Radar and Barometer Sensors: Implications for Airborne Radiometric Surveys [CL]

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http://arxiv.org/abs/1802.00327


Flight height is a fundamental parameter for correcting the gamma signal produced by terrestrial radionuclides measured during airborne surveys. The frontiers of radiometric measurements with UAV require light and accurate altimeters flying at some 10 m from the ground. We equipped an aircraft with seven altimetric sensors (three low-cost GNSS receivers, one inertial measurement unit, one radar altimeter and two barometers) and analyzed $\sim$ 3 h of data collected over the sea in the (35-2194) m altitude range. At low altitudes (H $<$ 70 m) radar and barometric altimeters provide the best performances, while GNSS data are used only for barometer calibration as they are affected by a large noise due to the multipath from the sea. The $\sim$ 1 m median standard deviation at 50 m altitude affects the estimation of the ground radioisotope abundances with an uncertainty less than 1.3%. The GNSS double-difference post-processing enhanced significantly the data quality for H $>$ 80 m in terms of both altitude median standard deviation and agreement between the reconstructed and measured GPS antennas distances. Flying at 100 m the estimated uncertainty on the ground total activity due to the uncertainty on the flight height is of the order of 2%.

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M. Alberi, M. Baldoncini, C. Bottardi, et. al.
Fri, 2 Feb 18
2/48

Comments: N/A

Performance of 20:1 multiplexer for large area charge readouts in directional dark matter TPC detectors [CL]

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http://arxiv.org/abs/1711.00943


More target mass is required in current TPC based directional dark matter detectors for improved detector sensitivity. This can be achieved by scaling up the detector volumes, but this results in the need for more analogue signal channels. A possible solution to reducing the overall cost of the charge readout electronics is to multiplex the signal readout channels. Here, we present work on an expanded LMH6574 multiplexer system with a capability of reducing the number of readouts in such TPC detectors by a factor of 20. Results indicate that the important charge distribution asymmetry along an ionization track is retained after multiplexed signals are demultiplexed.

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A. Ezeribe, M. Robinson, N. Robinson, et. al.
Mon, 6 Nov 17
50/53

Comments: 12 pages, 9 figures

Engineering physics of superconducting hot-electron bolometer mixers [IMA]

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http://arxiv.org/abs/1710.09136


Superconducting hot-electron bolometers are presently the best performing mixing devices for the frequency range beyond 1.2 THz, where good quality superconductor-insulator-superconductor (SIS) devices do not exist. Their physical appearance is very simple: an antenna consisting of a normal metal, sometimes a normal metal-superconductor bilayer, connected to a thin film of a narrow, short superconductor with a high resistivity in the normal state. The device is brought into an optimal operating regime by applying a dc current and a certain amount of local- oscillator power. Despite this technological simplicity its operation has been found to be controlled by many different aspects of superconductivity, all occurring simultaneously. A core ingredient is the understanding that there are two sources of resistance in a superconductor: a charge conversion resistance occurring at an normal-metal-superconductor interface and a resistance due to time- dependent changes of the superconducting phase. The latter is responsible for the actual mixing process in a non-uniform superconducting environment set up by the bias-conditions and the geometry. The present understanding indicates that further improvement needs to be found in the use of other materials with a faster energy-relaxation rate. Meanwhile several empirical parameters have become physically meaningful indicators of the devices, which will facilitate the technological developments.

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T. Klapwijk and A. Semenov
Thu, 26 Oct 17
17/49

Comments: This is an author-processed copy of an Invited contribution to the Special Issue of the IEEE Transactions on Terahertz Science and Technology dedicated to the 28th IEEE International Symposium on Space Terahertz Technology (ISSTT2017)

Stabilized Modulated Photonic Signal Transfer Over 186 km of Aerial Fiber [CL]

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http://arxiv.org/abs/1706.04244


Aerial suspended optical-fiber links are being considered as economical alternatives to buried links for long-distance transfer of coherent time and frequency signals. We present stability measurements of an actively stabilized 20 MHz photonic signal over aerial fiber links up to 186.2 km in length. Absolute frequency stabilities of 2.7×10^-3 Hz at 1 s of integration, and 2.5×10^-5 Hz at 8×10^3 s of integration are achieved over this longest link. This stability is compared to that achieved over buried links for both radio and microwave frequencies. The results show that aerial fiber links are a suitable alternative to buried links for a wide range of frequency transfer applications.

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D. Gozzard, S. Schediwy, B. Wallace, et. al.
Thu, 15 Jun 17
13/68

Comments: 9 pages, submitted