A 6D interferometric inertial isolation system [IMA]


We present a novel inertial-isolation scheme based on six degree-of-freedom (6D) interferometric readout of a single reference mass. It is capable of reducing inertial motion by more than two orders of magnitude at 100\,mHz compared with what is achievable with state-of-the-art seismometers. This would in turn dramatically improve the low-frequency sensitivity of gravitational-wave detectors. The scheme is inherently two-stage, the reference mass is softly suspended within the platform to be isolated, which is itself suspended from the ground. The platform is held constant relative to the reference mass and this closed-loop control effectively transfers the low force-noise of the reference mass to the platform. The loop gain also reduces non-linear couplings and dynamic range requirements in the soft-suspension mechanics and the interferometric readout.

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C. Mow-Lowry and D. Martynov
Mon, 8 Jan 18

Comments: N/A

First results from the HAYSTAC axion search [CEA]


The axion is a well-motivated cold dark matter (CDM) candidate first postulated to explain the absence of $CP$ violation in the strong interactions. CDM axions may be detected via their resonant conversion into photons in a “haloscope” detector: a tunable high-$Q$ microwave cavity maintained at cryogenic temperature, immersed a strong magnetic field, and coupled to a low-noise receiver.
This dissertation reports on the design, commissioning, and first operation of the Haloscope at Yale Sensitive to Axion CDM (HAYSTAC), a new detector designed to search for CDM axions with masses above $20$ $\mu\mathrm{eV}$. I also describe the analysis procedure developed to derive limits on axion CDM from the first HAYSTAC data run, which excluded axion models with two-photon coupling $g_{a\gamma\gamma} \gtrsim 2\times10^{-14}$ $\mathrm{GeV}^{-1}$, a factor of 2.3 above the benchmark KSVZ model, over the mass range $23.55 < m_a < 24.0$ $\mu\mathrm{eV}$.
This result represents two important achievements. First, it demonstrates cosmologically relevant sensitivity an order of magnitude higher in mass than any existing direct limits. Second, by incorporating a dilution refrigerator and Josephson parametric amplifier, HAYSTAC has demonstrated total noise approaching the standard quantum limit for the first time in a haloscope axion search.

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B. Brubaker
Thu, 4 Jan 2018

Comments: Ph.D. thesis. 346 pages, 58 figures. A few typos corrected relative to the version submitted to ProQuest

MARTA: A high-energy cosmic-ray detector concept with high-accuracy muon measurement [CL]


A new concept for the direct measurement of muons in air showers is presented. The concept is based on resistive plate chambers (RPCs), which can directly measure muons with very good space and time resolution. The muon detector is shielded by placing it under another detector able to absorb and measure the electromagnetic component of the showers such as a water-Cherenkov detector, commonly used in air shower arrays. The combination of the two detectors in a single, compact detector unit provides a unique measurement that opens rich possibilities in the study of air showers.

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P. Abreu, S. Andringa, P. Assis, et. al.
Fri, 22 Dec 17

Comments: N/A

A new charge reconstruction algorithm for the DAMPE silicon microstrip detector [IMA]


The DArk Matter Particle Explorer (DAMPE) is one of the four satellites within the Strategic Pioneer Research Program in Space Science of the Chinese Academy of Science (CAS). The Silicon-Tungsten Tracker (STK), which is composed of 768 singled-sided silicon microstrip detectors, is one of the four subdetectors in DAMPE, providing track reconstruction and charge identification for relativistic charged particles. The charge response of DAMPE silicon microstrip detectors is complicated, depending on the incident angle and impact position. A new charge reconstruction algorithm for the DAMPE silicon microstrip detector is introduced in this paper. This algorithm can correct the complicated charge response, and was proved applicable by the ion test beam.

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R. Qiao, W. Peng, D. Guo, et. al.
Fri, 22 Dec 17

Comments: 7 pages, 8 figures

Impact of the positive ion current on large size neutrino detectors and delayed photon emission [CL]


Given their small mobility coefficient in liquid argon with respect to the electrons, the ions spend a considerably longer time in the active volume. We studied the effects of the positive ion current in a liquid argon time projection chamber, in the context of massive argon experiments for neutrino physics. The constant recombination between free ions and electrons produces a quenching of the charge signal and a constant emission of photons, uncorrelated in time and space to the physical interactions. The predictions evidence some potential concerns for multi-ton argon detectors, particularly when operated on surface

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R. Santorelli, S. Luise, E. Garcia, et. al.
Fri, 22 Dec 17

Comments: Proceedings of the Lidine 2017 conference

Radon background in liquid xenon detectors [CL]


The radioactive daughters isotope of 222Rn are one of the highest risk contaminants in liquid xenon detectors aiming for a small signal rate. The noble gas is permanently emanated from the detector surfaces and mixed with the xenon target. Because of its long half-life 222Rn is homogeneously distributed in the target and its subsequent decays can mimic signal events. Since no shielding is possible this background source can be the dominant one in future large scale experiments. This article provides an overview of strategies used to mitigate this source of background by means of material selection and on-line radon removal techniques.

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N. Rupp
Thu, 21 Dec 17

Comments: N/A

New prototype scintillator detector for the Tibet AS$γ$ Experiment [IMA]


The hybrid Tibet AS array was successfully constructed in 2014. It has 4500 m$^{2}$ underground water Cherenkov pools used as the muon detector (MD) and 789 scintillator detectors covering 36900 m$^{2}$ as the surface array. At 100 TeV, cosmic-ray background events can be rejected by approximately 99.99\%, according to the full Monte Carlo (MC) simulation for $\gamma$-ray observations. In order to use the muon detector efficiently, we propose to extend the surface array area to 72900 m$^{2}$ by adding 120 scintillator detectors around the current array to increase the effective detection area. A new prototype scintillator detector is developed via optimizing the detector geometry and its optical surface, by selecting the reflective material and adopting dynode readout. This detector can meet our physics requirements with a positional non-uniformity of the output charge within 10\% (with reference to the center of the scintillator), time resolution FWHM of $\sim$2.2 ns, and dynamic range from 1 to 500 minimum ionization particles.

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Y. Zhang, Q. Gou, H. Cai, et. al.
Wed, 20 Dec 17

Comments: 13 pages, 9 figures, published in JINST