The field of dark matter detection is a highly visible and highly competitive one. In this paper, we propose recommendations for presenting dark matter direct detection results particularly suited ...for weak-scale dark matter searches, although we believe the spirit of the recommendations can apply more broadly to searches for other dark matter candidates, such as very light dark matter or axions. To translate experimental data into a final published result, direct detection collaborations must make a series of choices in their analysis, ranging from how to model astrophysical parameters to how to make statistical inferences based on observed data. While many collaborations follow a standard set of recommendations in some areas, for example the expected flux of dark matter particles (to a large degree based on a paper from Lewin and Smith in 1995), in other areas, particularly in statistical inference, they have taken different approaches, often from result to result by the same collaboration. We set out a number of recommendations on how to apply the now commonly used Profile Likelihood Ratio method to direct detection data. In addition, updated recommendations for the Standard Halo Model astrophysical parameters and relevant neutrino fluxes are provided. The authors of this note include members of the DAMIC, DarkSide, DARWIN, DEAP, LZ, NEWS-G, PandaX, PICO, SBC, SENSEI, SuperCDMS, and XENON collaborations, and these collaborations provided input to the recommendations laid out here. Wide-spread adoption of these recommendations will make it easier to compare and combine future dark matter results.
Dual-phase xenon detectors are widely used in dark matter direct detection experiments, and have demonstrated the highest sensitivities to a variety of dark matter interactions. However, a key ...component of the dual-phase detector technology-the efficiency of charge extraction from liquid xenon into gas-has not been well characterized. In this paper, we report a new measurement of the electron extraction efficiency (EEE) in a small xenon detector using two monoenergetic decay features of Ar37. By achieving stable operation at very high voltages, we measured the EEE values at the highest extraction electric field strength reported to date. For the first time, an apparent saturation of the EEE is observed over a large range of electric field; between 7.5 and 10.4 kV/cm extraction field in the liquid xenon the EEE stays stable at the level of 1% (kV/cm)−1. In the context of electron transport models developed for xenon, we discuss how the observed saturation may help calibrate this relative EEE measurement to the absolute EEE values. In addition, we present the implications of this result not only to current and future xenon-based dark matter searches, but also to xenon-based searches for coherent elastic neutrino-nucleus scatters.
Abstract
Small epipelagic and migratory,
Eutynnus affinis
(kawakawa) is one of the commercially significant tunas of Indo-Pacific’s tropical and subtropical waters. Consequently, successful ...management must ensure its sustainability. Unfortunately, the management and stock structure of certain migratory species in the area are not clear. The current study aimed to discriminate the E. affinis through body shape variations and to evaluate the variations among seven populations of E. affinis. A total of 114 individuals of E. affinis collected from two main geographic area, Straits of Malacca and South China Sea. Multivariate analyses, such as discriminant function analyses (DFA) of 12 morphometric characters was carried out to discriminate seven populations of E. affinis. The results revealed there is a significant variation among the body shape and seven populations of E. affinis. The average shapes of populations from Terengganu, Kelantan, and Johor were approximately similar to each other. In contrast, the average shapes of populations from Selangor were separated. This present study is the first report using morphometric method conducted on E. affinis from Peninsular Malaysian waters.
Dual-phase xenon detectors lead the search for keV-scale nuclear recoil signals expected from the scattering of weakly interacting massive particle (WIMP) dark matter, and can potentially be used to ...study the coherent nuclear scattering of MeV-scale neutrinos. New capabilities of such experiments can be enabled by extending their nuclear recoil searches down to the lowest measurable energy. The response of the liquid xenon target medium to nuclear recoils, however, is not well characterized below a few keV, leading to large uncertainties in projected sensitivities. In this work, we report a new measurement of ionization signals from nuclear recoils in liquid xenon down to the lowest energy reported to date. At 0.3 keV, we find that the average recoil produces approximately one ionization electron; this is the first measurement of nuclear recoil signals at the single-ionization-electron level, approaching the physical limit of liquid xenon ionization detectors. We discuss the implications of these measurements on the physics reach of xenon detectors for nuclear-recoil-based WIMP dark matter searches and the detection of coherent elastic neutrino-nucleus scattering.
Plants have been used throughout human history for food and medicine. However, many plants are toxic, and cannot easily be morphologically distinguished from non-toxic plants. DNA identification ...solves this problem and is widely used. Nonetheless, plant DNA barcode identification faces a number of challenges, and many studies have been conducted to find suitable barcodes. The present study was conducted to test the efficiency of commonly used primers, namely ITS2, rpoC1, and trnH-psbA, in order to find the best DNA barcode markers for the identification of medicinal plants in Malaysia. Fresh leaves from 12 medicinal plants that are commonly used by Malay traditional healers were collected from the Tropical Spice Garden, Pulau Pinang, and subjected to polymerase chain reaction amplification using ITS2, rpoC1, and trnH-psbA DNA markers. We found that trnH-psbA is the best DNA marker for the species-level identification of medicinal plants in Malaysia.
The LUX-ZEPLIN experiment is a dark matter detector centered on a dual-phase xenon time projection chamber operating at the Sanford Underground Research Facility in Lead, South Dakota, USA. This ...Letter reports results from LUX-ZEPLIN's first search for weakly interacting massive particles (WIMPs) with an exposure of 60 live days using a fiducial mass of 5.5 t. A profile-likelihood ratio analysis shows the data to be consistent with a background-only hypothesis, setting new limits on spin-independent WIMP-nucleon, spin-dependent WIMP-neutron, and spin-dependent WIMP-proton cross sections for WIMP masses above 9 GeV/c^{2}. The most stringent limit is set for spin-independent scattering at 36 GeV/c^{2}, rejecting cross sections above 9.2×10^{-48} cm at the 90% confidence level.
Species distribution, virulence traits and vancomycin resistance gene profiles of Enterococcus isolated from 43 home‐made artisan cheese samples collected from open markets, located in Aydin region ...of Turkey, were investigated. Of the 129 isolates, 95 were identified as Enterococcus sp.; Enterococcus faecium being the most prevalent species (82.1%), followed by Enterococcus faecalis (13.6%) and Enterococcus durans (1.0%). None of the enterococci were harbouring vanA or vanC, while seven isolates (7.3%) were shown to harbour vanB gene by multiplex PCR. gelE (49.4%) being the most prevalent virulence factor was followed by asa1 (27.3%), esp (22.1%), cylA (4.2%) and hyl (3.1%).
Movement is an important life history trait that can have an impact on local adaptation, and other evolutionary phenomena. We used a combination of nestbox survey data and genetic techniques ...(genotyping at 10 microsatellite loci) to quantify patterns of movement in common dormice Muscardinus avellanarius at two distinct sites in the UK: 1) Bontuchel (a natural population) and 2) Wych (captive-bred individuals that were reintroduced to this site), over three consecutive years (2006-2008). Both methods revealed a consistent pattern of sex-biased movement (movements by adult males and females) in both populations that allowed isolation-by-distance genetic structure to develop within 1 km. The similarity of data from captive-bred and natural individuals indicated that ex situ programing has not significantly altered the natural movement behavior of common dormice; consequently, the two populations could be managed with the same conservation strategies. We also found that the reintroduced dormice in Wych maintained relatively high levels of genetic diversity. This first report of movement patterns in reintroduced and natural populations of M. avellanarius combining genetic and field-survey data highlights the role of genetic studies in the investigation of ecological behaviour and for conservation management.
The LUX-ZEPLIN (LZ) experiment Akimov, D.Yu; Angelides, N.; Araújo, H.M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2020, Letnik:
953, Številka:
C
Journal Article
Recenzirano
Odprti dostop
We describe the design and assembly of the LUX-ZEPLIN experiment, a direct detection search for cosmic WIMP dark matter particles. The centerpiece of the experiment is a large liquid xenon time ...projection chamber sensitive to low energy nuclear recoils. Rejection of backgrounds is enhanced by a Xe skin veto detector and by a liquid scintillator Outer Detector loaded with gadolinium for efficient neutron capture and tagging. LZ is located in the Davis Cavern at the 4850’ level of the Sanford Underground Research Facility in Lead, South Dakota, USA. We describe the major subsystems of the experiment and its key design features and requirements.
PDF
