Read Books Online and Download eBooks, EPub, PDF, Mobi, Kindle, Text Full Free.
Signal Yields And Detector Modeling In Xenon Time Projection Chambers And Results Of An Effective Field Theory Dark Matter Search Using Lux Data
Download Signal Yields And Detector Modeling In Xenon Time Projection Chambers And Results Of An Effective Field Theory Dark Matter Search Using Lux Data full books in PDF, epub, and Kindle. Read online Signal Yields And Detector Modeling In Xenon Time Projection Chambers And Results Of An Effective Field Theory Dark Matter Search Using Lux Data ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
Book Synopsis Signal Yields and Detector Modeling in Xenon Time Projection Chambers, and Results of an Effective Field Theory Dark Matter Search Using LUX Data by : Gregory R. C. Rischbieter
Download or read book Signal Yields and Detector Modeling in Xenon Time Projection Chambers, and Results of an Effective Field Theory Dark Matter Search Using LUX Data written by Gregory R. C. Rischbieter and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Characterizing the Peripheral Dynamics of Xenon Dark Matter Detectors by : Jacob Edward Cutter
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.
Book Synopsis Effective Field Theory Search Results from the LUX Run 4 Data Set, and Construction of the LZ System Test Platforms by : Shaun Kenneth Alsum
Download or read book Effective Field Theory Search Results from the LUX Run 4 Data Set, and Construction of the LZ System Test Platforms written by Shaun Kenneth Alsum and published by . This book was released on 2020 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astrophysical evidence suggests that roughly 26% of the energy density of the universe is composed of non-baryonic dark matter. Although the presence of dark matter has been confirmed, its precise particle nature remains unknown. A strong candidate for what makes up the majority of dark matter is a class of particles referred to as Weakly Interacting Massive Particles (WIMPs). The Large Underground Xenon (LUX) experiment and the LUX-ZEPPLIN (LZ) experiment are dual-phase xenon Time Projection Chambers (TPCs) designed to detect the direct scattering of one of these WIMPs off of an atomic nucleus. The LUX collaboration uses confidence intervals determined via hypothesis test inversion to set limits on WIMP-nucleon couplings. These hypothesis tests are done using a profile likelihood ratio test statistic. This technique resulted in the LUX 2014 - 2016 (Run 4) data set yielding a world-leading limit on the WIMP-nucleon spin-independent interaction at WIMP masses of ~ 10s of GeV. A model-independent way of investigating WIMP-nucleon interactions is introduced utilizing Effective Field Theory. This framework introduces 14 possible allowed WIMP-nucleon couplings in the non-relativistic regime. Many of these couplings produce signals whose recoil spectra peak at energies above the threshold of our previous spin-independent search, and as such, an all-new analysis was developed to extend LUX's energy range and search for these couplings. Comparison of the LUX Run 4 data set to the models developed in this analysis yielded results that are inconsistent with the background-only model. However, inspection of the data suggests that this is due to an incomplete modeling of the electron recoil background, not due to the presence of a WIMP signal, and therefore only upper limits are reported. Additionally, efforts have been made to improve upon the LUX detector's technology for LZ via the construction of prototype detectors at the SLAC National Accelerator Laboratory.
Book Synopsis Background Modeling and First Searches for Low Energy Signals in The LUX-ZEPLIN (LZ) Dark Matter Experiment by : Daniel Kodroff
Download or read book Background Modeling and First Searches for Low Energy Signals in The LUX-ZEPLIN (LZ) Dark Matter Experiment written by Daniel Kodroff and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past half-century overwhelming evidence has mounted indicating the existence of a non-baryonic and enigmatic dark matter that constitutes approximately 85% of the total matter in the universe. Among the potential dark matter detection methods, dual- phase time projection chambers (TPCs) have emerged as the leading detector technology. LUX-ZEPLIN (LZ) is a direct detection dark matter experiment located at the 4850-ft depth level of the Sanford Underground Research Facility in South Dakota, USA, employing a 7 tonne active volume of liquid xenon in a dual-phase TPC. It's surrounded by an instrumented xenon "Skin" region and gadolinium-loaded liquid-scintillator outer detector, primarily serving as active vetoes for gamma-ray and neutron backgrounds, respectively, and contained within an ultra-pure water tank. The LZ detector began its first science run in December of 2021 and released its first results in the Summer of 2022. In order to ensure a low-background environment, a comprehensive material assay and selection campaign, for detector components, along with a xenon-purification campaign were pursued prior to and during construction. These mitigations have allowed LZ to achieve a background rate of 63.0 ± 4.5 x 10-6 events/keVee/kg/day in the low- energy region, approximately 60 times lower than that of its predecessor, the LUX experiment. LZ performed comprehensive measurements to constrain backgrounds in situ and construct a well-constrained time-dependent background model to use in searches for novel physics signals within this low-energy (
Book Synopsis Search for Dark Matter Interactions Using Ionization Yield in Liquid Xenon by : Sergey Uvarov
Download or read book Search for Dark Matter Interactions Using Ionization Yield in Liquid Xenon written by Sergey Uvarov and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cosmological observations overwhelmingly support the existence of dark matter which constitutes 87% of the universe's total mass. Weakly Interacting Massive Particles (WIMPs) are a prime candidate for dark matter, and the Large Underground Xenon (LUX) experiment aims to a direct-detection of a WIMP-nucleon interaction. The LUX detector is a dual-phase xenon time-projection chamber housed 4,850 feet underground at Sanford Underground Research Facility in Lead, South Dakota. We present the ionization-only analysis of the LUX 2013 WIMP search data. In the 1.04 x 104 kg-days exposure, thirty events were observed out of the 24.8 expected from radioactive backgrounds. We employ a cut-and-count method to set a 1-sided 90% C.L. upper limit for spin-independent WIMP-nucleon cross-sections. A zero charge yield for nuclear-recoils below 0.7 keV is included upper limit calculation. This ionization-only analysis excludes an unexplored region of WIMP-nucleon cross-section for low-mass WIMPs achieving 1.56 x 10−43 cm2 WIMP-nucleon cross-section exclusion for a 5.1 GeV/c2 WIMP.
Book Synopsis A Search for Dark Matter with the Large Underground Xenon Detector by : Jeremy Allen Mock
Download or read book A Search for Dark Matter with the Large Underground Xenon Detector written by Jeremy Allen Mock and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Weakly Interacting Massive Particles (WIMP) has been postulated as a candidate that constitutes dark matter, which dominates the matter density in the universe. The Large Underground Xenon (LUX) detector is a 370 kg (112 kg fiducial) dual-phase xenon time projection chamber operating 4,850 feet underground at the Sanford Underground Research Facility in Lead, South Dakota with the goal of detecting WIMPs. A refined understanding of detector response is required in order to make such searches more sophisticated. The LUX simulation includes a new physics model, the Noble Element Simulation Technique, which accurately predicts the scintillation and ionization yields as well as the prompt and electroluminescence pulse shapes in xenon. These models, combined with a new technique for in-situ, low-energy neutron calibration, allow for the extension of the WIMP detection regime into a lower-energy region. A novel analysis technique for the removal of spurious, high-rate background events facilitates the reduction of conservative analysis thresholds. Both of these improvements, which lead to an increased sensitivity of LUX to low-mass WIMPs, are described in this thesis. While no discovery is reported, this work establishes the most stringent 90% confidence level upper limit on the WIMP-nucleon cross-section of 7.43 x 10−46 cm2 for a WIMP with mass 33 GeV/c2.
Book Synopsis Mitigation of Backgrounds for the Large Underground Xenon Dark Matter Experiment by : Chang Lee
Download or read book Mitigation of Backgrounds for the Large Underground Xenon Dark Matter Experiment written by Chang Lee and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: While the existence of particle dark matter is widely accepted through multitude of astrophysics evidence, its exact nature remains mysterious. It is expected to comprise the local galactic halo, and one of the most favored candidates, weakly interacting massive particle (WIMP), is hypothesized to interact with baryonic matter. Such an interaction can be detected in a radio-quiet low-threshold detector such as the large underground xenon (LUX) detector. The LUX is a dual-phase xenon time projection chamber (TPC), and it operates at Sanford Underground Research Facility in Lead, SD. Analysis of the first science data with a 86.3 days live-time from LUX yielded the best spin-independent WIMP-nucleon cross-section exclusion limit to date, with the lower limit of $7.6\times10^{-46}$~cm$^2$ at 33~GeV/c$^2$ with a 90\% confidence level. This thesis consists the following chapters. The case for cold dark matter from the current cosmological observations is reviewed. The natures of the expected WIMP-nucleon scattering signal and the techniques to discriminate the background events are discussed. Principles of the dual-phase TPC are explained, with details of the LUX hardware. The original works for this thesis follows. A campaign to remove radioactive noble impurities from the target xenon is described in depth. A position reconstruction algorithm based on comparison of observed data to simulation is developed. Background events from the detector's internal walls are studied and modeled for the profile likelihood ratio test of the second analysis. Finally, the first published results are reviewed in detail.
Book Synopsis Digital Advances in Triggering and Data Acquisition Systems for Large Scale Dark Matter Search Experiments by : Eryk Filip Druszkiewicz
Download or read book Digital Advances in Triggering and Data Acquisition Systems for Large Scale Dark Matter Search Experiments written by Eryk Filip Druszkiewicz and published by . This book was released on 2017 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: "With a wealth of astrophysical evidence that confirms that the baryonic matter we understand accounts for only 5% of the matter and energy in the universe, the search is on for the mysterious dark matter, that is said to account for 25% of the universe composition. The leading candidate for dark matter is the Weakly Interacting Massive Particle (WIMP). Large Underground Xenon (LUX), a 370 kg two-phase (liquid/gas) xenon time projection chamber operating at 4850 feet underground at the Sanford Underground Research Facility (SURF), has recently completed its operation, setting the world's best limit on the WIMP-nucleon cross section. This thesis presents the author's research and development of a novel, FPGA-based, triggering system. This system has operated at SURF since 2011 and through digital signal processing techniques identified events of interest in real-time. The system processes the incoming data at its filter stages with a rate of 5,100 MB/s and does so consuming a total of only 15 W. The firmware and software were entirely developed by the author, while the custom-built hardware was developed in close collaboration with the author. The system offers great flexibility through the reconfigurability feature of FPGAs, which was exercised often during the course of the experiment. The system allows for fully remote operation, minimizing the personnel needs one mile underground. For this type of detectors, this triggering system has shown to offer the highest efficiency in detecting signals as small as few liquid electrons. An FIR digital filter implementation is presented, that has been tailored for this application and offers an up to 99% and 97% savings in scalars and summers utilization, respectively. LUX-Zepplin (LZ) is a next-generation dark matter detector, that is scheduled to start probing the remainder of the uncharted WIMP-nucleon cross section in 2020. It is a significantly larger successor of LUX, with a total xenon mass of 10 tonne. It will be instrumented with 745 photomultipliers, totaling 1,359 digitizing channels. The author is developing the LZ Data Acquisition and Data Sparsification system. This system is going to handle a continuous input rate of over 200 GB/s and its key elements have already been shown to meet and exceed the LZ requirements. Techniques are presented for allowing data volume footprint reduction, such as efficient digitized pulse storage, offering up to 45% reduction in the effective pulse storage size."--Pages xi-xii.
Book Synopsis Pulse Shape Discrimination in the LUX Dark Matter Detector by : Dev Ashish Khaitan
Download or read book Pulse Shape Discrimination in the LUX Dark Matter Detector written by Dev Ashish Khaitan and published by . This book was released on 2019 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Abundant evidence from astrophysical and cosmological observations suggests 80% of the total matter density in the Universe is in the form of dark matter (DM). This matter is not described by the Standard Model (SM) and numerous candidates have been proposed. Weakly Interacting Massive Particles (WIMPs) are one of the leading DM candidates. The Large Underground Xenon (LUX) experiment was built to directly observe the interaction of DM with xenon target nuclei. LUX acquired data between April 2013 until August 2016 at Sanford Underground Research Facility (SURF) in Lead, South Dakota. The analysis of this data led to the publication of numerous world-leading upper limits on the WIMP-nucleon scattering cross-section. WIMPs are expected to produce nuclear recoil (NR) events within liquid xenon time-projection chambers. We present a measurement of the scintillation timing characteristics of liquid xenon in the LUX dark matter detector and develop a pulse shape discriminant to be used for particle identification. To accurately measure the timing characteristics, we develop a template-fitting method to reconstruct the detection times of photons. Analyzing calibration data collected during the 2013-16 LUX WIMP search, we provide a new measurement of the singlet-to-triplet scintillation ratio for electron recoils (ER) below 46 keV, and we make a first-ever measurement of the NR singlet-to-triplet ratio at recoil energies below 74 keV. We exploit the difference of the photon time spectra for NR and ER events by using a prompt fraction discrimination parameter, which is optimized using calibration data to have the least number of ER events that occur in the 50% NR acceptance region. We then demonstrate how this discriminant can be used in conjunction with the charge-to-light discrimination to improve the signal-to-noise ratio for NRs"--Pages xii-xiii.
Book Synopsis Dark Matter Directionality Revisited with a High Pressure Xenon Gas Detector by :
Download or read book Dark Matter Directionality Revisited with a High Pressure Xenon Gas Detector written by and published by . This book was released on 2015 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: An observation of the anisotropy of dark matter interactions in a direction-sensitive detector would provide decisive evidence for the discovery of galactic dark matter. Directional information would also provide a crucial input to understanding its distribution in the local Universe. Most of the existing directional dark matter detectors utilize particle tracking methods in a low-pressure gas time projection chamber. These low pressure detectors require excessively large volumes in order to be competitive in the search for physics beyond the current limit. In order to avoid these volume limitations, we consider a novel proposal, which exploits a columnar recombination effect in a high-pressure gas time projection chamber. The ratio of scintillation to ionization signals observed in the detector carries the angular information of the particle interactions. In this paper, we investigate the sensitivity of a future directional detector focused on the proposed high-pressure Xenon gas time projection chamber. We study the prospect of detecting an anisotropy in the dark matter velocity distribution. We find that tens of events are needed to exclude an isotropic distribution of dark matter interactions at 95% confidence level in the most optimistic case with head-to-tail information. However, one needs at least 10-20 times more events without head-to-tail information for light dark matter below ~50 GeV. For an intermediate mass range, we find it challenging to observe an anisotropy of the dark matter distribution. Our results also show that the directional information significantly improves precision measurements of dark matter mass and the elastic scattering cross section for a heavy dark matter.
Book Synopsis An Effective Field Theory Analysis of the First LUX Dark Matter Search by : Nicole A. Larsen
Download or read book An Effective Field Theory Analysis of the First LUX Dark Matter Search written by Nicole A. Larsen and published by . This book was released on 2016 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Searching for Dark Matter with the ATLAS Detector by : Steven Schramm
Download or read book Searching for Dark Matter with the ATLAS Detector written by Steven Schramm and published by Springer. This book was released on 2018-07-07 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes the search for Dark Matter at the LHC in the mono-jet plus missing transverse momentum final state, using the full dataset recorded in 2012 by the ATLAS Experiment. It is the first time that the number of jets is not explicitly restricted to one or two, thus increasing the sensitivity to new signals. Instead, a balance between the most energetic jet and the missing transverse momentum is required, thus selecting mono-jet-like final states. Collider searches for Dark Matter have typically used signal models employing effective field theories (EFTs), even when comparing to results from direct and indirect detection experiments, where the difference in energy scale renders many such comparisons invalid. The thesis features the first robust and comprehensive treatment of the validity of EFTs in collider searches, and provides a means by which the different classifications of Dark Matter experiments can be compared on a sound and fair basis.
Book Synopsis Direct Search for Dark Matter by Using Dual-phase Liquid Xenon Detector and Measurement of Nuclear Recoils in Liquid Argon by : Yixiong Meng
Download or read book Direct Search for Dark Matter by Using Dual-phase Liquid Xenon Detector and Measurement of Nuclear Recoils in Liquid Argon written by Yixiong Meng and published by . This book was released on 2015 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cosmological and Astrophysical observations provide compelling evidences for the existence of dark matter in the universe. One class of dark matter candidates, the Weakly Interacting Massive Particles (WIMPs), has been predicted in many particle physics theories. Direct detection experiments using dual- phase liquid noble element detectors report the best sensitivities to the detection of the dark matter particles. The next generation direct detection experiments using the same technology, are actively been built and expected to give a factor of 100 improvement on the current best sensitivity. This thesis discusses the measurement of nuclear recoils in a dual-phase liquid argon detector using a bunched neutron beam generated by linear accelerator facility at accelerator laboratory in Notre Dame University. Nuclear recoils of en- ergy ranging from 10.8 keVnr to 49.9 keVnr are measured under different drift field configurations. An electric field quenching on nuclear recoils in liquid argon is dis- covered and quantified for the first time. This quenching effect is also found to be drift field and recoil energy dependent. By varying the drift field amplitude from 100 V/cm to 1000 V/cm for each nuclear recoil energy, the quenching effect are measured as a function of nuclear recoil energy and drift field amplitude. Results from this measurement is used in the direct dark matter detection experiment to calculate the final sensitivity of direct dark matter search. A separate work on the optimization of detector design for the XENON1T detector is also discussed in detail. Finite element simulation tool is used to design and optimize the electric field in XENON1T time projection chamber. As part of the design of XENON1T detector, electron transparency across metal grids of different geometrical configurations are also studied.
Book Synopsis Estimating LUX-ZEPLIN's Sensitivity to Sub-GeV Dark Matter Scattering Off Electrons in Xenon by : Gus Eberlein
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.
Book Synopsis Dark Matter Effective Field Theory Scattering in Direct Detection Experiments by :
Download or read book Dark Matter Effective Field Theory Scattering in Direct Detection Experiments written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We examine the consequences of the effective field theory (EFT) of dark matter-nucleon scattering for current and proposed direct detection experiments. Exclusion limits on EFT coupling constants computed using the optimum interval method are presented for SuperCDMS Soudan, CDMS II, and LUX, and the necessity of combining results from multiple experiments in order to determine dark matter parameters is discussed. We demonstrate that spectral differences between the standard dark matter model and a general EFT interaction can produce a bias when calculating exclusion limits and when developing signal models for likelihood and machine learning techniques. We also discuss the implications of the EFT for the next-generation (G2) direct detection experiments and point out regions of complementarity in the EFT parameter space.
Book Synopsis Calibrations for the Improved Search for Dark Matter with the LZ (LUX-ZEPLIN) Experiment by : Madan K. Sharma Timalsina
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.
Book Synopsis Particle Detectors by : Hermann Kolanoski
Download or read book Particle Detectors written by Hermann Kolanoski and published by Oxford University Press. This book was released on 2020-06-30 with total page 949 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the fundamentals of particle detectors as well as their applications. Detector development is an important part of nuclear, particle and astroparticle physics, and through its applications in radiation imaging, it paves the way for advancements in the biomedical and materials sciences. Knowledge in detector physics is one of the required skills of an experimental physicist in these fields. The breadth of knowledge required for detector development comprises many areas of physics and technology, starting from interactions of particles with matter, gas- and solid-state physics, over charge transport and signal development, to elements of microelectronics. The book's aim is to describe the fundamentals of detectors and their different variants and implementations as clearly as possible and as deeply as needed for a thorough understanding. While this comprehensive opus contains all the materials taught in experimental particle physics lectures or modules addressing detector physics at the Master's level, it also goes well beyond these basic requirements. This is an essential text for students who want to deepen their knowledge in this field. It is also a highly useful guide for lecturers and scientists looking for a starting point for detector development work.
