158 research outputs found
The Thermal Conductance of Sapphire Ball Based Detector Clamps
In order to provide secure clamping with a low thermal conductance, some low
temperature detectors are held with point contact sapphire ball clamps. While
this method is increasingly common, the thermal conductance across this
interface has not been well studied. We present a direct measurement of the
thermal conductance of such clamps between 200 and 600~mK, with a clamping
force of approximately 2.7~~N/clamp. The thermal conductance of a
single sapphire-on-copper clamp was found to be
660~~[nW/K]. For a sapphire-on-silicon clamp the
conductance was found to be 380~~[nW/K]. The
conductance measured is consistent with thermal boundary resistance.Comment: 8 pages, 4 figures, Proceedings for the 19th International Workshop
on Low Temperature Detectors (LTD19). J Low Temp Phys (2022
Nuclear Recoil Scintillation Linearity of a High Pressure He Gas Detector
We investigate scintillation linearity of a commercial high pressure He
gas detector using monoenergetic 2.8 MeV neutrons from a deuterium-deuterium
fusion neutron generator. The scintillation response of the detector was
measured for a range of recoil energies between 83 keV and 626 keV by tagging
neutrons scattering into fixed angles with a far-side organic scintillator
detector. Detailed Monte Carlo simulations were compared to experimental data
to determine the linearity of the detector response by comparing the scaling of
the energy deposits in the simulations to the detector output. In this
analysis, a linear scintillation response corresponds to a consistent value for
the scaling factor between simulated energy deposits and experimental data for
several different scattering angles. We demonstrate that the detector can be
used to detect fast neutron interactions down to 83 keV recoil energies and can
be used to characterize low-energy neutron sources, one of its potential
applications
Modeling and characterization of TES-based detectors for the Ricochet experiment
Coherent elastic neutrino-nucleus scattering (CENS) offers a valuable
approach in searching for physics beyond the Standard Model. The Ricochet
experiment aims to perform a precision measurement of the CENS spectrum at
the Institut Laue-Langevin nuclear reactor with cryogenic solid-state
detectors. The experiment plans to employ an array of cryogenic thermal
detectors, each with a mass around 30 g and an energy threshold of sub-100 eV.
The array includes nine detectors read out by Transition-Edge Sensors (TES).
These TES based detectors will also serve as demonstrators for future neutrino
experiments with thousands of detectors. In this article we present an update
in the characterization and modeling of a prototype TES detector.Comment: Submitted to LTD20 proceedin
Applying Superfluid Helium to Light Dark Matter Searches: Demonstration of the HeRALD Detector Concept
The SPICE/HeRALD collaboration is performing R&D to enable studies of sub-GeV
dark matter models using a variety of target materials. Here we report our
recent progress on instrumenting a superfluid He target mass with a
transition-edge sensor based calorimeter to detect both atomic signals (e.g.
scintillation) and He quasiparticle (phonon and roton) excitations. The
sensitivity of HeRALD to the critical "quantum evaporation" signal from He
quasiparticles requires us to block the superfluid film flow to the
calorimeter. We have developed a heat-free film-blocking method employing an
unoxidized Cs film, which we implemented in a prototype "HeRALD v0.1" detector
of 10~g target mass. This article reports initial studies of the atomic
and quasiparticle signal channels. A key result of this work is the measurement
of the quantum evaporation channel's gain of , which will
enable He-based dark matter experiments in the near term. With this gain
the HeRALD detector reported here has an energy threshold of 145~eV at 5 sigma,
which would be sensitive to dark matter masses down to 220~MeV/c.Comment: 14 pages, 9 figure
Fast neutron background characterization of the future Ricochet experiment at the ILL research nuclear reactor
The future Ricochet experiment aims at searching for new physics in the
electroweak sector by providing a high precision measurement of the Coherent
Elastic Neutrino-Nucleus Scattering (CENNS) process down to the sub-100 eV
nuclear recoil energy range. The experiment will deploy a kg-scale
low-energy-threshold detector array combining Ge and Zn target crystals 8.8
meters away from the 58 MW research nuclear reactor core of the Institut Laue
Langevin (ILL) in Grenoble, France. Currently, the Ricochet collaboration is
characterizing the backgrounds at its future experimental site in order to
optimize the experiment's shielding design. The most threatening background
component, which cannot be actively rejected by particle identification,
consists of keV-scale neutron-induced nuclear recoils. These initial fast
neutrons are generated by the reactor core and surrounding experiments
(reactogenics), and by the cosmic rays producing primary neutrons and
muon-induced neutrons in the surrounding materials. In this paper, we present
the Ricochet neutron background characterization using He proportional
counters which exhibit a high sensitivity to thermal, epithermal and fast
neutrons. We compare these measurements to the Ricochet Geant4 simulations to
validate our reactogenic and cosmogenic neutron background estimations.
Eventually, we present our estimated neutron background for the future Ricochet
experiment and the resulting CENNS detection significance.Comment: 14 pages, 14 figures, 1 tabl
First demonstration of 30 eVee ionization energy resolution with Ricochet germanium cryogenic bolometers
The future Ricochet experiment aims to search for new physics in the
electroweak sector by measuring the Coherent Elastic Neutrino-Nucleus
Scattering process from reactor antineutrinos with high precision down to the
sub-100 eV nuclear recoil energy range. While the Ricochet collaboration is
currently building the experimental setup at the reactor site, it is also
finalizing the cryogenic detector arrays that will be integrated into the
cryostat at the Institut Laue Langevin in early 2024. In this paper, we report
on recent progress from the Ge cryogenic detector technology, called the
CryoCube. More specifically, we present the first demonstration of a 30~eVee
(electron equivalent) baseline ionization resolution (RMS) achieved with an
early design of the detector assembly and its dedicated High Electron Mobility
Transistor (HEMT) based front-end electronics. This represents an order of
magnitude improvement over the best ionization resolutions obtained on similar
heat-and-ionization germanium cryogenic detectors from the EDELWEISS and
SuperCDMS dark matter experiments, and a factor of three improvement compared
to the first fully-cryogenic HEMT-based preamplifier coupled to a CDMS-II
germanium detector. Additionally, we discuss the implications of these results
in the context of the future Ricochet experiment and its expected background
mitigation performance.Comment: 10 pages, 5 figures, 1 tabl
Variable responses within epiphytic and benthic microalgal communities to nutrient enrichment
Coherent elastic neutrino-nucleus scattering: Terrestrial and astrophysical applications
Coherent elastic neutrino-nucleus scattering (CENS) is a process in which neutrinos scatter on a nucleus which acts as a single particle. Though the total cross section is large by neutrino standards, CENS has long proven difficult to detect, since the deposited energy into the nucleus is keV. In 2017, the COHERENT collaboration announced the detection of CENS using a stopped-pion source with CsI detectors, followed up the detection of CENS using an Ar target. The detection of CENS has spawned a flurry of activities in high-energy physics, inspiring new constraints on beyond the Standard Model (BSM) physics, and new experimental methods. The CENS process has important implications for not only high-energy physics, but also astrophysics, nuclear physics, and beyond. This whitepaper discusses the scientific importance of CENS, highlighting how present experiments such as COHERENT are informing theory, and also how future experiments will provide a wealth of information across the aforementioned fields of physics
Coherent elastic neutrino-nucleus scattering: Terrestrial and astrophysical applications
Coherent elastic neutrino-nucleus scattering (CENS) is a process inwhich neutrinos scatter on a nucleus which acts as a single particle. Thoughthe total cross section is large by neutrino standards, CENS has longproven difficult to detect, since the deposited energy into the nucleus is keV. In 2017, the COHERENT collaboration announced the detection ofCENS using a stopped-pion source with CsI detectors, followed up thedetection of CENS using an Ar target. The detection of CENS hasspawned a flurry of activities in high-energy physics, inspiring newconstraints on beyond the Standard Model (BSM) physics, and new experimentalmethods. The CENS process has important implications for not onlyhigh-energy physics, but also astrophysics, nuclear physics, and beyond. Thiswhitepaper discusses the scientific importance of CENS, highlighting howpresent experiments such as COHERENT are informing theory, and also how futureexperiments will provide a wealth of information across the aforementionedfields of physics.<br
Metagenomic and Metabolic Profiling of Nonlithifying and Lithifying Stromatolitic Mats of Highborne Cay, The Bahamas
BACKGROUND: Stromatolites are laminated carbonate build-ups formed by the metabolic activity of microbial mats and represent one of the oldest known ecosystems on Earth. In this study, we examined a living stromatolite located within the Exuma Sound, The Bahamas and profiled the metagenome and metabolic potential underlying these complex microbial communities. METHODOLOGY/PRINCIPAL FINDINGS: The metagenomes of the two dominant stromatolitic mat types, a nonlithifying (Type 1) and lithifying (Type 3) microbial mat, were partially sequenced and compared. This deep-sequencing approach was complemented by profiling the substrate utilization patterns of the mats using metabolic microarrays. Taxonomic assessment of the protein-encoding genes confirmed previous SSU rRNA analyses that bacteria dominate the metagenome of both mat types. Eukaryotes comprised less than 13% of the metagenomes and were rich in sequences associated with nematodes and heterotrophic protists. Comparative genomic analyses of the functional genes revealed extensive similarities in most of the subsystems between the nonlithifying and lithifying mat types. The one exception was an increase in the relative abundance of certain genes associated with carbohydrate metabolism in the lithifying Type 3 mats. Specifically, genes associated with the degradation of carbohydrates commonly found in exopolymeric substances, such as hexoses, deoxy- and acidic sugars were found. The genetic differences in carbohydrate metabolisms between the two mat types were confirmed using metabolic microarrays. Lithifying mats had a significant increase in diversity and utilization of carbon, nitrogen, phosphorus and sulfur substrates. CONCLUSION/SIGNIFICANCE: The two stromatolitic mat types retained similar microbial communities, functional diversity and many genetic components within their metagenomes. However, there were major differences detected in the activity and genetic pathways of organic carbon utilization. These differences provide a strong link between the metagenome and the physiology of the mats, as well as new insights into the biological processes associated with carbonate precipitation in modern marine stromatolites
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