A
bstract
Studying atmospheric neutrino oscillations in the few-GeV range with a multi-megaton detector promises to determine the neutrino mass hierarchy. This is the main science goal pursued by the ...future KM3NeT/ORCA water Cherenkov detector in the Mediterranean Sea. In this paper, the processes that limit the obtainable resolution in both energy and direction in charged-current neutrino events in the ORCA detector are investigated. These processes include the composition of the hadronic fragmentation products, the subsequent particle propagation and the photon-sampling fraction of the detector. GEANT simulations of neutrino interactions in seawater produced by GENIE are used to study the effects in the 1-20 GeV range. It is found that fluctuations in the hadronic cascade in conjunction with the variation of the inelasticity
y
are most detrimental to the resolutions. The effect of limited photon sampling in the detector is of significantly less importance. These results will therefore also be applicable to similar detectors/media, such as those in ice.
LUX-ZEPLIN (LZ) is a second-generation direct dark matter experiment with spin-independent WIMP-nucleon scattering sensitivity above 1.4 × 10-48 cm2 for a WIMP mass of 40 GeV/c 2 and a 1000 d ...exposure. LZ achieves this sensitivity through a combination of a large 5.6 t fiducial volume, active inner and outer veto systems, and radio-pure construction using materials with inherently low radioactivity content. The LZ collaboration performed an extensive radioassay campaign over a period of six years to inform material selection for construction and provide an input to the experimental background model against which any possible signal excess may be evaluated. The campaign and its results are described in this paper. We present assays of dust and radon daughters depositing on the surface of components as well as cleanliness controls necessary to maintain background expectations through detector construction and assembly. Finally, examples from the campaign to highlight fixed contaminant radioassays for the LZ photomultiplier tubes, quality control and quality assurance procedures through fabrication, radon emanation measurements of major sub-systems, and be spoke detector systems to assay scintillator are presented.
Maintaining the electric fields necessary for the current generation of noble liquid time projection chambers (TPCs), with drift lengths exceeding one meter, requires a large negative voltage applied ...to their cathode. Delivering such high voltage is associated with an elevated risk of electrostatic discharge and electroluminescence, which would be detrimental to the performance of the experiment. The Xenon Breakdown Apparatus (XeBrA) is a five-liter, high voltage test chamber built to investigate the contributing factors to electrical breakdown in noble liquids. In this work, we present the main findings after conducting scans over stressed electrode areas, surface finish, pressure, and high voltage ramp speed in the medium of liquid xenon. Area scaling and surface finish were observed to be the dominant factors affecting breakdown, whereas no significant changes were observed with varying pressure or ramp speed. A general rise in both anode current and photon rate was observed in the last 30 seconds leading up to a breakdown, with a marked increase in the last couple of seconds. In addition, the position of breakdowns was reconstructed with a system of high-speed cameras and a moderate correlation with the Fowler-Nordheim field emission model was found. Tentative evidence for bubble nucleation being the originating mechanism of breakdown in the liquid was also observed. We deem the results presented in this work to be of particular interest for the design of future, large TPCs, and practical recommendations are provided.
These proceedings summarize the program and discussions of the ``Workshop on
Xenon Detector $0\nu\beta\beta$ Searches: Steps Towards the Kilotonne Scale''
held on October 25-27 2023 at SLAC National ...Accelerator Laboratory. This
workshop brought together experts from the communities of neutrinoless
double-beta decay and dark matter detection, to discuss paths forward for the
realization of monolithic experiments with xenon approaching the kilotonne
scale.
Knowledge of the ionization and scintillation responses of liquid xenon (LXe) to nuclear recoils is crucial for LXe-based dark matter experiments. Current calibrations carry large uncertainties in ...the low-energy region below \(\sim3\) keV\(_nr\) where signals from dark matter particles of \(<\)10 GeV/c\(^2\) masses are expected. The coherent elastic neutrino-nucleus scattering (CE\(\nu\)NS) by solar \(^8\)B neutrinos also results in a continuum of nuclear recoil events below 3.0 keV\(_{nr}\) (99\% of events), which further complicates low-mass dark matter searches in LXe experiments. In this paper, we describe a method to quantify the uncertainties of low-energy LXe responses using published calibration data, followed by case studies to evaluate the impact of yield uncertainties on \({^8}\)B searches and low-mass dark matter sensitivity in a typical ton-scale LXe experiment. We conclude that naively omitting yield uncertainties leads to overly optimistic limits by factor \(\sim2\) for a 6 GeV/c\(^2\) WIMP mass. Future nuclear recoil light yield calibrations could allow experiments to recover this sensitivity and also improve the accuracy of solar \({^8}\)B flux measurements.
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.
Large detectors employing xenon are a leading technology in existing and planned searches for new physics, including searches for neutrinoless double beta decay (\(0\nu\beta\beta\)) and dark matter. ...While upcoming detectors will employ target masses of a ton or more, further extending gas or liquid phase Xe detectors to the kton scale would enable extremely sensitive next-generation searches for rare phenomena. The key challenge to extending this technology to detectors well beyond the ton scale is the acquisition of the Xe itself. We describe the motivation for extending Xe time projection chambers (TPCs) to the kton scale and possible avenues for Xe acquisition that avoid existing supply chains. If acquisition of Xe in the required quantities is successful, kton-scale detectors of this type could enable a new generation of experiments, including searches for \(0\nu\beta\beta\) at half-life sensitivities as long as \(10^{30}\) yr.
L’objectiu és determinar què era l’església del monestir de Sant Pere de Rodes en el seu primer estatacabat per a qui la vagi concebre i dirigir. N’hem manejat la historiografia i les dificultats de ...veure’n la forma, aixecat plànols, trobat la unitat de mesura, estudiat les dimensions en relació amb els coneixements de proporció del moment i les descripcions dels edificis bíblics, seguit les variacions durant la construcció, contextualitzat el vocabulari, descrit l’estructura espacial i el programa iconològic.
En resulta que per haver concebut, elaborat i construït l’església calien el quadrivi, la Bíblia, la idea dels sentits múltiples establerta per l’exegesi i un coneixement poc o molt analític d’arquitectura romana i d’arrel romana; i la capacitat de treure’n criteris de decisió de rang equivalent; les columnes superposades de la nau són el moment fort de la constitució de l’edifici en lloc.
The aim is to establish what the nature was of the church of the monastery of Sant Pere de Rodes for those in charge of its conception and actual construction when the building was first considered complete. We have examined the historiography and the difficulties encountered in describing the form of the church, measured the building, drawn new plans, found the unit used, related the dimensions to contemporary knowledge on proportion and biblical descriptions, followed changes during the building process, put the vocabulary in context and described both the spatial structure and the iconological program. The church could neither have been conceived, developed nor built without the quadrivium, the Bible, the exegetical idea of multiplicity of senses and an analytical knowledge of Roman or Romanbased
architecture; nor without the ability to get equivalent decision criteria from all of them. The superimposed columns make the building into a place.
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