Download or read book Calibrations for the Improved Search for Dark Matter with the LZ LUX ZEPLIN Experiment written by Madan K. Sharma Timalsina and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A hypothetical non-luminous existence of matter is known as dark matter, inferred by the convincing collection of astrophysical and cosmological indirect evidence. In spite of compelling indirect observations, the physical nature of dark matter remains one of the most profound questions in the field of modern physics. A Weakly Interacting Massive Particle (WIMP) is historically the most favored candidate particle for dark matter, which could nicely explain the observed indirect measurements with the direct detection of WIMPs for the first time. The new second-generation direct detection dark matter experiment LZ (LUXZEPLIN), designed for direct detection of WIMP dark matter, has performed the most sensitive search for spin-independent WIMP-nucleon interactions. LZ is located 4850 feet underground at the Sanford Underground Research Facility (SURF) in Lead, South Dakota, USA. LZ is employing a two-phase xenon detector with an active mass of 7 tonnes. With LZ we have recently managed in the summer of 2022 to provide the most rigorous exclusion limit for spin-independent WIMP-nucleon scattering with an upper limit on the cross-section of 6.5×10−48 cm2 (90 % confidence level) for a WIMP mass of 30 GeV/c2 . The first WIMP search result of LZ utilizes a fiducial mass of 5.5 tonnes of liquid xenon and an exposure time of 60 live days. WIMPs could interact in the cryogenic liquid xenon of the detector’s core by scattering off xenon nuclei, which would then recoil and produce both scintillation light and electric charge. The ratio of the immediately detected scintillation light (S1) and the delayed charge detection (S2) is characteristic for such a nuclear recoil (NR) from hypothesized dark matter, e.g. a WIMP, and differs significantly from an electron recoil (ER) produced by undesired background reactions. However, the precise knowledge of the energy-dependent ratio S1/S2, for which the ER-dominated regime transitions into the NR-dominated regime, is key hereby to separate WIMP dark matter signals from unwanted background signals. We performed calibrations with neutron sources to map out the NR signal region for the WIMP search. Instead, gamma- and beta-ray calibration sources were utilized to map out the ER region, characteristic for background signals to be discriminated against. In this thesis, the calibration data to map out the NR signal region has been extensively studied and compared to the results of a full LZ detector simulation. In addition, another crucial detector calibration, for which all LZ data has to be corrected, is the purity monitoring of the liquid xenon. The chemical purity determines the lifetime of signal electrons against the absorption on impurities during their drift within the liquid xenon time projection chamber of the LZ detector. This electron lifetime analysis has been performed on a daily basis within the framework of this thesis and results have been applied by every data evaluator within the large LZ collaboration and for obtaining the current world’s best exclusion limit on WIMP dark matter.
Download or read book LUX ZEPLIN Dark Matter Searches written by Billy Boxer and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Estimating LUX ZEPLIN s Sensitivity to Sub GeV Dark Matter Scattering Off Electrons in Xenon written by Gus Eberlein and published by . This book was released on 2024 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprising 85% of the mass of the universe, dark matter is one of the most pressing outstanding questions of physics. When it comes to directly detecting dark matter, the LUX-ZEPLIN (LZ) experiment has unparalleled sensitivity. We examine the detector's capability to detect sub-GeV dark matter scattering off the electrons in xenon, LZ's scintillation medium. We develop a signal model by calculating the expected DM-electron event rates as a function of electron recoil energy and as a function of the number of freed electrons. Alongside an established backgrounds model, this signal model is used to simulate events in the LZ detector. With this simulated data and a cut-and-count analysis, we are able to estimate cross sections of dark matter-electron scattering down to which LZ can detect the signal over the background. We find that LUX-ZEPLIN will be able to detect certain light dark matter models at a much greater sensitivity than previous direct detection experiments.
Download or read book The LUX Dark Matter Experiment written by Patrick Phelps and published by . This book was released on 2014 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dark matter, the mysterious substance that seems to make up most of the mass of the universe, has never been detected in the laboratory. In this document I outline the current world's leading experiment, LUX, to look for a class of dark matter, the Weakly Interacting Massive Particle. I outline the general principles of searching for dark matter through low background detectors and event rejection, I move on to a description of the LUX experiment and its performance, reviewing its internal structure and subsystems including a novel heat exchange system that expedited system readiness and resulted in a stable platform for WIMP searching. The LUX energy reconstruction is then examined, followed by a breakdown of signal fluctuations as a function of energy as part of our understanding of back- ground discrimination in this class of detectors. Finally, I review the first LUX WIMP search result, culminating in the world's most sensitive limit on the spin- independent WIMP-nucleon cross section, before moving to a discussion of next steps in the search for dark matter for LUX and next generational experiments.
Download or read book The LZ Dark Matter Experiment written by Kelly M Stifter and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to a compelling body of astrophysical and cosmological evidence, dark matter has come to be accepted as a crucial ingredient of modern cosmology, yet its physical nature remains one of the most pressing questions in the field of physics. One historically favored model of dark matter is weakly interacting massive particles, or WIMPs. LUX-ZEPLIN (LZ) is a next-generation dark matter detector designed to achieve field-leading sensitivity to much of the remaining accessible parameter space within the WIMP dark matter paradigm. To help realize the full-scale LZ detector, the System Test R&D platform was constructed at SLAC National Accelerator Laboratory to validate the performance of critical LZ subsystems at scales approaching or comparable to the LZ design. In this dissertation, I present results showing that the passivation of the high voltage electrodes in citric acid leads to a significant reduction in spontaneous emission of single electrons, potentially limiting a major instrumental background by up to several orders of magnitude and enabling a more sensitive dark matter search. The LZ detector has now been assembled at the Sanford Underground Research Facility (SURF) in Lead, South Dakota and is taking early data. I also give a first look at commissioning data that captured the first light from electrons in the LZ detector, and share methods to validate the in situ performance of the high voltage electrodes.
Download or read book Novel Fitting Techniques for Dark Matter Searches with the LUX ZEPLIN Experiment written by Jordan Palmer and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dark Matter Searches with the LUX and LZ Experiments written by Sally Shaw and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Study of Excess Electronic Recoil Events in XENON1T written by Evan Shockley and published by Springer Nature. This book was released on 2021-10-30 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis summarizes the original analysis work performed by the author on data from XENON1T, a search for dark matter with a ton-size noble liquid detector operated at Gran Sasso Underground Laboratory in Italy. The nature of dark matter is one of the most open and pressing questions of modern physics, and the unique data acquired with this detector allows the exploration and investigation of several potential scenarios. The analysis of Dr. Shockley searches for a class of elusive elementary particles that interact with the electrons of ordinary atoms, instead of the nucleus. Results of the analysis present, with high confidence, an excess with respect to the expected background. Beyond more mundane explanations, this additional rate of electron-mediated interactions might be a first hint of physics beyond the standard model. This accessible thesis provides details on the detector, the data, and the theory, delivering to the reader an in-depth and coherent picture of the search for physics beyond the standard model.
Download or read book Dark Matter Searches with the LUX and LZ Experiments written by S. Shaw and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Characterizing the Peripheral Dynamics of Xenon Dark Matter Detectors written by Jacob Edward Cutter and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the most important fundamental problems in physics today is to understand the nature of dark matter. The landscape of explanations for observed dark matter phenomena is vast and still expanding, and an impressive number of experiments have been built to probe the dark sector of the universe. A prominent class of detectors is aimed at discovering (or excluding) a particular kind of dark matter: the Weakly Interacting Massive Particle (WIMP). Searching for this popular dark matter candidate requires an ultra-sensitive, low-background target; xenon detectors serve as such a target for dark matter interactions. The Large Underground Xenon (LUX) detector is a dual-phase xenon time-projection chamber (TPC) which was operated underground at the Homestake Mine in Lead, South Dakota from 2013 to 2016, and was able to achieve the world's leading WIMP exclusion limit. However, successful reconstruction of WIMP-nucleus scatters in such detectors requires thorough understanding of the detection medium, which is made difficult by various confounding effects near the detector walls. Field-fringing is a major component of confusion in the periphery, and the large electric field non-uniformities in Run 4 of LUX provided a significant challenge in the dark matter analysis. Here is presented an algorithm to bijectively map between reconstructed event positions and true spatial coordinates, which serves as an important tool for studying field effects and fiducialization in LUX. Additionally, a successful dark matter search must model interfering background events in the WIMP search region which can't be directly vetoed. One class of unavoidable backgrounds comes from nuclear decay chain daughters in detector materials themselves, which may produce WIMP-like signals (an effect which is amplified due to various detector effects). The Davis Xenon (DAX) test bed system and a dual-phase TPC have been assembled and operated at UC Davis to characterize these common "wall backgrounds", as well as perform other R&D studies for the next-generation LUX-ZEPLIN (LZ) experiment. The DAX TPC specifically measures the xenon response to heavy nuclei produced by custom [alpha] decay sources created using novel chemical deposition procedures. In this thesis, results will be presented for the light and charge yields of immersed localized sources of 206Pb ions in liquid xenon, as well as a method for tagging such recoil events in situ by using PIN diodes as charged particle detectors to capture the correlated [alpha] particles. We also compare our isolated 206Pb events with previous WIMP search data from LUX, and discuss the significance of 206Pb as a WIMP background. Such information is most useful to future experiments if it can improve existing background models and simulations. The Noble Element Simulation Technique (NEST) is the ultimate software package for calculating expected signal yields in xenon detectors, but is an empirical framework that relies on experimental data to inform the models. We discuss the development of current NEST v2 models, specifically the heavy nuclear recoil models, as well as our current understanding of the xenon microphysics. We also show NEST predictions for mono-energetic 206Pb recoils, and discuss how our most recent DAX 206Pb measurements may inform NEST models in future work.
Download or read book Background and Sensitivity Studies for the LUX ZEPLIN Dark Matter Experiment written by Umit Utku and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Results from the ZEPLIN III Dark Matter Search Experiment written by Paul Robert Scovell and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for Dark Matter with the LUX ZEPLIN Detector written by Cees Carels and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct Searches for WIMP Dark Matter with ZEPLIN III written by Alastair Edward Currie and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Work contributing to experimental limits on WIMP dark matter scattering in a liquid xenon target is presented. The ZEPLIN-III detector at Boulby completed 83 days' continuous operation in 2008 and, following a hardware upgrade, a further 319 days in 2010-11. Inelastic dark matter hypotheses to explain the DAMA/LIBRA modulation as scattering from iodine are excluded with ≥ 87% confidence using 2008 data. Upper limits on the elastic WIMP-nucleon cross section are set from the combined exposure, with a minimum of 3.9 × 10−8 pb for 50 GeVc−2 WIMP mass at 90% CL, in addition to competitive limits on the WIMP-neutron spin-dependent cross section. The detector responses to scintillation and ionisation--throughout the fiducial volume and over the duration of the run -- are characterised via calibration with 57Co and 137Cs sources, as well as sidebands in search data. Signal spectra are modeled using these responses and an in situ measurement of the energy-dependent light and charge yields of nuclear recoils. Analysis software, event selection and background estimation are all described. Confidence intervals based on sparse regions of parameter space (Yellin limits) and the likelihood ratios are implemented for ZEPLIN-III and discussed in the context of rare-event searches with significant background uncertainty.
Download or read book A Search for Dark Matter with the ZEPLIN II Detector written by Jianting Gao and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Galaxies and clusters of galaxies are believed to be dominated by non-luminous non-baryonic dark matter. A favored candidate is a new type of Weakly Interacting Massive Particle (WIMP) with a mass of order 100 GeV/c^2. The ZEPLIN II experiment is a WIMP search experiment that attempts to directly detect WIMP interactions using the two-phase xenon approach. The detector measures both scintillation and ionization generated by interactions in a 31 kg liquid xenon target. This approach provides a powerful discrimination between nuclear recoils, as expected from WIMPs, and background electron recoils. In this work, we develop a new [chi]^2 approach to determine the three dimensional event positions in an attempt to improve the background rejection. The optical properties of the PTFE reflectors and the grids of the detector were determined using the Geant4 simulation, and event positions were obtained by finding the best match to the amount of light in each photomultiplier. This was found to greatly improve the position resolution. The approach was then applied to the WIMP search data. It was found that one of the dominating background sources was events from the gas above the anode grid and not from the PTFE walls caused by the small signals as previously thought. WIMP search results were then obtained from the first 31 days of stable ZEPLIN II data using two methods. Although the [chi]^2 method greatly improved position resolution, the number of background events was not significantly altered and the new limit agreed well with the limit published by the collaboration.
Download or read book Dark Matter Searches and Study of Electrode Design in LUX and LZ written by Adam Bailey and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Calibration of B tagging and Search for Dark Matter written by Anna Shcherbakova and published by . This book was released on 2017 with total page 215 pages. Available in PDF, EPUB and Kindle. Book excerpt:
