Study of Negative-Ion TPC Using μ-PIC for Directional Dark Matter Search [IMA]

Negative-ion time projection chambers(TPCs) have been studied for low-rate and high-resolution applications such as dark matter search experiments. Recently, a full volume fiducialization in a self-triggering TPC was realized. This innovative technology demonstrated a significant reduction in the background with MWPC-TPCs. We studied negative-ion TPC using the {\mu}-PIC+GEM system and obtained sufficient gas gain with CS${2}$gas and SF${6}$ gas at low pressures. We expect an improvement in detector sensitivity and angular resolution with better electronics.

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T. Ikeda, K. Miuchi, A. Ochi, et. al.
Wed, 20 Sep 17

Comments: N/A

Towards the LISA Backlink: Experiment design for comparing optical phase reference distribution systems [CL]

LISA is a space-based laser interferometer that will detect gravitational waves by using three satellites in a triangular constellation with laser links in-between. Each satellite houses two optical benches that are articulated by moving optical subassemblies for compensating the breathing angle in the constellation. An optical phase reference distribution system, also known as backlink, is required to form an optical path for bi-directional light exchange between the intra-satellite benches.
In this article we present potential backlink candidates with a target non-reciprocity of at most $2\pi\,\mathrm{\mu rad/\sqrt{Hz}}$, equivalent to $1\,\mathrm{pm/\sqrt{Hz}}$ for an assumed wavelength of $1064\,$nm. The candidates are a previously demonstrated direct fiber, a frequency separated fiber and a steered free beam backlink. They are all to be compared in a single experimental set-up. We show the results of an IfoCAD simulation of the interferometer which includes the component alignment together with ray tracing and a ghost beam analysis, a power budget calculation and a noise estimation. First experimental results of a free beam laser link between two optical set-ups that are rotating by $\pm 1\,^\circ$ relative to each other are demonstrated, achieving closed-loop operation. The experiment demonstrated the readiness and analyzed the thermal behavior of our laboratory infrastructure.

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K. Isleif, L. Bischof, S. Ast, et. al.
Wed, 20 Sep 17

Comments: 29 pages, 18 figures, submitted to Classical Quantum Gravity

A study of temperature effects on MIP of BGO calorimetersof DAMPE [CL]

In this paper, we presented a study of temperature effects on BGO calorimeters using proton MIP’s collected in the first year operation of DAMPE. By directly comparing MIP calibration constants used by DAMPE data production pipe line, we found an experimental relation between temperature and signal amplitudes of each BGO bar: a general deviation of -1.162%/$^{\circ}$C,and -0.47%/$^{\circ}$C to -1.60%/$^{\circ}$C statistically for each detector element. During 2016, DAMPE’s temperature changed by about 7 degrees due to solar elevation angle and the corresponding energy scale bias is about 8%. By frequent MIP calibration operation, this kind of bias is eliminated to an acceptable value.

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Y. Wang, S. Wen, W. Jiang, et. al.
Wed, 13 Sep 17

Comments: N/A

Ultra-Low Energy Calibration of LUX Detector using $^{127}$Xe Electron Capture [CL]

We report an absolute calibration of the ionization yields($\textit{Q$_y$})$ and fluctuations for electronic recoil events in liquid xenon at discrete energies between 186 eV and 33.2 keV. The average electric field applied across the liquid xenon target is 180 V/cm. The data are obtained using low energy $^{127}$Xe electron capture decay events from the 95.0-day first run from LUX (WS2013) in search of Weakly Interacting Massive Particles (WIMPs). The sequence of gamma-ray and X-ray cascades associated with $^{127}$I de-excitations produces clearly identified 2-vertex events in the LUX detector. We observe the K- (binding energy, 33.2 keV), L- (5.2 keV), M- (1.1 keV), and N- (186 eV) shell cascade events and verify that the relative ratio of observed events for each shell agrees with calculations. The N-shell cascade analysis includes single extracted electron (SE) events and represents the lowest-energy electronic recoil $\textit{in situ}$ measurements that have been explored in liquid xenon.

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LUX. Collaboration, D. Akerib, S. Alsum, et. al.
Wed, 13 Sep 17

Comments: 10 pages, 10 figures, 2 tables

Review: Far-Infrared Instrumentation and Technology Development for the Next Decade [IMA]

Originating in the late 1950’s, far-infrared astronomy has advanced rapidly over the last three decades, driven by a rapidly maturing technology base and an expanding community of astronomers. This advancement has shown that observations at far-infrared wavelengths are of fundamental importance to all areas of astrophysics, from the search for habitable planets and the origin of life, to the very earliest stages of galaxy assembly in the first few million years of cosmic history. The combination of a still developing portfolio of technologies, particularly in the field of detectors, and a widening ensemble of platforms within which these technologies can be implemented, means that far-infrared astronomy currently holds even greater potential for paradigm-shifting advances. In this review, we examine current and potential far-infrared observing platforms, including ground-based, sub-orbital, and space-based facilities, and discuss the technology development pathways that will enable and enhance these platforms to best address the forefront challenges facing far-infrared astronomy in the 21st century.

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D. Farrah, K. Smith, D. Ardila, et. al.
Mon, 11 Sep 17

Comments: Invited review article, submitted to the Journal of Astronomical Telescopes, Instruments, and Systems. Comments and suggestions welcome

Spectral Calibration of the Fluorescence Telescopes of the Pierre Auger Observatory [IMA]

We present a novel method to measure precisely the relative spectral response of the fluorescence telescopes of the Pierre Auger Observatory. We used a portable light source based on a xenon flasher and a monochromator to measure the relative spectral efficiencies of eight telescopes in steps of 5 nm from 280 nm to 440 nm. Each point in a scan had approximately 2 nm FWHM out of the monochromator. Different sets of telescopes in the observatory have different optical components, and the eight telescopes measured represent two each of the four combinations of components represented in the observatory. We made an end-to-end measurement of the response from different combinations of optical components, and the monochromator setup allowed for more precise and complete measurements than our previous multi-wavelength calibrations. We find an overall uncertainty in the calibration of the spectral response of most of the telescopes of 1.5% for all wavelengths; the six oldest telescopes have larger overall uncertainties of about 2.2%. We also report changes in physics measureables due to the change in calibration, which are generally small.

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Pierre Auger Collaboration et. al.
Thu, 7 Sep 17

Comments: Accepted for publication in Astroparticle Physics

Current status of direct dark matter detection experiments [CEA]

Much like ordinary matter, dark matter might consist of elementary particles, and weakly interacting massive particles are one of the prime suspects. During the past decade, the sensitivity of experiments trying to directly detect them has improved by three to four orders of magnitude, but solid evidence for their existence is yet to come. We overview the recent progress in direct dark matter detection experiments and discuss future directions.

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J. Liu, X. Chen and X. Ji
Tue, 5 Sep 17

Comments: 6 pages, 4 figures, version accepted by Nature Physics