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Direct Search For Dark Matter By Using Dual Phase Liquid Xenon Detector And Measurement Of Nuclear Recoils In Liquid Argon
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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 Measurements and Modeling of Low Energy Nuclear Recoils in Liquid Xenon for Dark Matter and Neutrino Detection by : Brian Gregory Lenardo
Download or read book Measurements and Modeling of Low Energy Nuclear Recoils in Liquid Xenon for Dark Matter and Neutrino Detection written by Brian Gregory Lenardo and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation focuses on the characterization of xenon as a detection medium for low energy particle physics. In particular, there are two signals that we are interested in exploring: the interactions of WIMP dark matter inside an earth-bound detector, and the coherent elastic scattering of neutrinos off of nuclei. Both are predicted to produce low energy (10−1--102 keV) nuclear recoils, which can be measured in a low-threshold detector. One well-established technique for measuring these signals is the dual-phase xenon emission detector, which measures primary scintillation light and electroluminescence from ionized electrons to reconstruct information about each interaction inside the target volume. To understand the data produced in an experiment, one must understand how the scintillation and ionization signals relate to the incident particle type and energy deposited. Calibrating the response of the detector medium is of crucial importance for both interpreting existing data and calculating the physics reach of current or future experiments. The ultimate goal of this dissertation is to provide a set of robust models of xenon ionization and scintillation emission which can can be used to calculate signals and simulate the response of liquid xenon detectors in experiments searching for low energy nuclear recoil signatures. In the work below, I begin with a detailed description of the physics of interest. Chapter 2 introduces the dual-phase xenon TPC and discuss its benefits for these types of experiments. In Chapter 3, we draw upon previous literature to develop a model of xenon scintillation and ionization yields. This model is fitted simultaneously to a compilation of available data to allow it to incorporate differences in operating conditions, such as applied electric field, across different experiments. Chapter 4 extends this modeling effort to work within the LUX collaboration, which operated a 300 kg liquid xenon TPC with world-leading sensitivity to dark matter WIMP interactions. LUX performed the lowest-energy nuclear recoil calibration measurements to date, allowing us to extend our model to lower energies and establishing the sensitivity of LUX to a broader range of WIMP models. Chapter 5 delves in greater detail into the time structure of scintillation in liquid xenon. We provide new data on scintillation pulse shapes for low energy nuclear recoils, and use the differences between electron- and nuclear-recoil pulse shapes to establish a new background discriminant for use in LUX data analysis. Finally, in Chapter 6 we describe an ongoing project at LLNL to provide new data of ionization yields at lower energies than the LUX measurements. These experiments will have direct implications on the sensitivity of liquid xenon detectors in general to both low-mass WIMPs and nuclear reactor neutrino scattering. Here we describe the development of the xenon detector system and the preliminary characterization and calibration work that was performed in preparation for the main experiments.
Book Synopsis Understanding Low-Energy Nuclear Recoils in Liquid Xenon for Dark Matter Searches and the First Results of XENON1T by : Matthew Anthony
Download or read book Understanding Low-Energy Nuclear Recoils in Liquid Xenon for Dark Matter Searches and the First Results of XENON1T written by Matthew Anthony and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An abundance of cosmological evidence suggests that cold dark matter exists and makes up 83% of the matter in the universe. At the same time, this dark matter has eluded direct detection and its identity remains a mystery. Many large international collaborations are actively searching for dark matter through its potential annihilation in high-density regions of the universe, its creation in particle accelerators, and its interaction with Standard Model particles in low-background detectors. One of the most promising dark matter candidates is the weakly interacting massive particle (WIMP) which falls naturally out of extensions of the Standard Model. A variety of detectors have been employed in the search for WIMPs, which are expected to scatter with atomic nuclei, yet none have been more successful than dual-phase liquid xenon time projection chambers (TPCs). The first ton-scale liquid xenon TPC, XENON1T, began operating in 2016 and with only 34.2 days of data has set the most strict limits on the WIMP-nucleon interaction cross sections for WIMP masses above 10 GeV/c^2, with a minimum of 7.7 × 10−47 cm^2 for 35 GeV/c^2 WIMPs.
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 Two-phase Emission Detectors by : Dmitry Yu Akimov
Download or read book Two-phase Emission Detectors written by Dmitry Yu Akimov and published by World Scientific. This book was released on 2021-07-15 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the rapidly developing areas of modern experimental nuclear physics is non-accelerator experiments using low-background detectors. Such experiments, as a rule, are aimed at solving problems that are of fundamental importance for understanding the structure of the Universe, checking the Standard Model of elementary particles, and looking for new physics behind the observable world. The most interesting tasks include the search for dark matter in the form of new weakly interacting particles, the search for neutrinoless double beta decay, the determination of the magnetic moment of the neutrino, the study of neutrino oscillation and new types of interaction of elementary particles, such as coherent neutrino scattering off heavy nuclei.All these processes, occurring with extremely low cross sections, require the development of efficient large-mass detectors capable of detecting small energy releases down to individual ionization electrons. An effective method to do this is the emission method of detecting ionizing particles in two-phase media, which has been proposed at Moscow Engineering Physics Institute (MEPhI) 50 years ago. The origin of this technique can be traced to the research headed by Prof. Boris A Dolgoshein, whose study focus on the properties of condensed noble gases as a means to develop a tracking streamer chamber with a high-density working medium.This monograph, devoted exclusively to two-phase emission detectors, considers the technology's basic features while taking into account new developments introduced into experimental practice in the last ten years since the publication of its predecessor, Emission Detectors (Bolozdynya, 2010).
Book Synopsis Design of Single Phase Liquid Argon Detectors for Dark Matter Searches by : Daniel E. Gastler
Download or read book Design of Single Phase Liquid Argon Detectors for Dark Matter Searches written by Daniel E. Gastler and published by . This book was released on 2012 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Within our current understanding of the makeup of the universe, dark matter makes up 25% of the total energy and over 80% of the matter in the universe. Little is known about the makeup of dark matter, but its existence has been indirectly measured using the rotation curves of galaxies, clusters of galaxies, and the Cosmic Microwave Background. To gain a greater understanding of this component of the universe, direct detection of dark matter is a major objective in particle astrophysics. One popular candidate for dark matter is the weakly interacting massive particle, or WIMP. The allowed rate of interaction between a WIMP and normal matter is extremely low, requiring new detection technologies with greater sensitivity to be explored. Though several experiments have already been conducted, no direct detection experiment has unambiguously identified a dark matter signal. This work explores the use of noble liquids, in a single liquid phase design, to detect single scatters of dark matter particles. The goal of current experiments is to investigate matter-dark-matter interaction cross-sections down to 10–45cm2. With that in mind, the MiniCLEAN detector has been designed with a 500 kg liquid argon detector volume and will be viewed by a spherical tt configuration of 92 photo-multiplier tubes. In order to determine the ability for single phase noble liquid to detect nuclear recoils from dark matter, several R&D experiments have been performed. These experiments undertook the measurement of how dark-matter-like nuclear recoils and background-like electronic recoils behave in liquid argon. In addition to reviewing the measurements of pulse shape discrimination and other noble liquid properties, my measurement of the scintillation efficiency is described. The scintillation efficiency characterizes the differing energy responses for nuclear and electron recoils. This was the first measurement of the scintillation efficiency in liquid argon for nuclear recoils over a wide energy range. Additionally, this work covers the design and testing of the front-end electronics and data acquisition software I developed for the MiniCLEAN experiment. This system has been designed to record and process thousands of physics events per second and has been tested using novel simulators, that I developed, that approximately represent the expected PMT signals of the MiniCLEAN detector.
Book Synopsis Direct Dark Matter Search with the DarkSide Experiment by : Anyssa Navrer-Agasson
Download or read book Direct Dark Matter Search with the DarkSide Experiment written by Anyssa Navrer-Agasson and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The existence of dark matter is known because of its gravitational effects, and although its nature remains undisclosed, one of the leading candidate is the weakly interacting massive particle (WIMP) with mass of the order of 100 GeV/c2 and coupling with ordinary matter at or below the weak scale. In this context, DarkSide-50 aims to direct observe WIMP-nucleon collisions in a liquid argon dual phase time-projection chamber located deep underground at Gran Sasso National Laboratory, in Italy. This work first details the argon calibration realised by the ARIS experiment. ARIS characterised the argon response to low energy nuclear and electronic recoils, down to unprecedented energies. The nuclear quenching was measured with the best precision to this date, and the recombination probability extracted was compared to different models describing the behaviour of argon in presence of an electric field. A search for low mass WIMPs performed with DarkSide-50 data is also presented. This search focuses on the ionisation signal from the TPC, leading much to much lower detection threshold. The achieved exclusion limits are amongst the leading ones, and the most stringent for a liquid argon target. Finally a preliminary search for axions is presented. Axions are an alternative candidate to dark matter, proposed as a solution to the strong CP problem. They are detectable in DarkSide via their coupling to electrons. This search required the improvement of the modelling of the background sources, by taking into account atomic effects in beta emission spectra, as well as a redefinition of the energy scale converting the energy deposited into a number of extracted electrons. The results presented show an encouraging sensitivity to both solar and galactic axions.
Book Synopsis Noble Gas Detectors by : Elena Aprile
Download or read book Noble Gas Detectors written by Elena Aprile and published by John Wiley & Sons. This book was released on 2007-02-27 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses the physical properties of noble fluids, operational principles of detectors based on these media, and the best technical solutions to the design of these detectors. Essential attention is given to detector technology: purification methods and monitoring of purity, information readout methods, electronics, detection of hard ultra-violet light emission, selection of materials, cryogenics etc. The book is mostly addressed to physicists and graduate students involved in the preparation of fundamental next generation experiments, nuclear engineers developing instrumentation for national nuclear security and for monitoring nuclear materials.
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 Identification Of Dark Matter, The - Proceedings Of The Fifth International Workshop by : Neil J C Spooner
Download or read book Identification Of Dark Matter, The - Proceedings Of The Fifth International Workshop written by Neil J C Spooner and published by World Scientific. This book was released on 2005-05-12 with total page 685 pages. Available in PDF, EPUB and Kindle. Book excerpt: The prestigious Identification of Dark Matter workshop series was initiated to assess the status of work that attempts to identify the constitution of dark matter. In particular, it aims to review the success of current methods that are used in the search for dark matter, as well as the new techniques that are likely to improve prospects for detecting possible dark matter candidates in the future. In the 5th International Workshop, special emphasis was placed on the recent results obtained in experiments searching for baryonic and non-baryonic dark matter. This volume comprises the high-quality review articles and papers contributed by leaders and promising young physicists who attended the conference. It provides the most recent updates on dark matter searches from both experimental and theoretical points of view.The proceedings have been selected for coverage in:• Index to Scientific & Technical Proceedings® (ISTP® / ISI Proceedings)• Index to Scientific & Technical Proceedings (ISTP CDROM version / ISI Proceedings)• CC Proceedings — Engineering & Physical Sciences
Book Synopsis Gamma Background Studies for the Xenon Experiment Using a High Purity Germanium Detector by : Jesse Isaac Angle
Download or read book Gamma Background Studies for the Xenon Experiment Using a High Purity Germanium Detector written by Jesse Isaac Angle and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: The XENON Dark Matter Experiment, deployed at the Gran Sasso National Laboratory in Italy on March 2006, is a liquid noble gas detector designed to directly detect dark matter. The detector uses a dual-phase (gas/liquid) Xenon target to search for nuclear recoils associated with nucleus-WIMP interactions. Due to the high sensitivity needed in such an experiment, it is vital to not only reduce the background but to also understand the remaining background so as to aid in the understanding of the data as well as to facilitate upgrades beyond the early Research and Development phases. Many of the components of the XENON10 detector have been screened using a High Purity Germanium Detector known as the GATOR detector. Full analysis of the screening data requires Monte Carlo simulations of the GATOR detector and the sample. Results from this screening will be presented. Using the information obtained from the screening operation, Monte Carlo simulations of the XENON10 electron recoil background will be examined and compared to the actual detector data. The success of this simulation to data comparison indicates that we have a good understanding of the XENON10 gamma background and will be able to make more informed decisions regarding the next stage of detector development. This type of analysis has aided in the selection and design of many of the materials and components being incorporated into the new XENON100 detector, the next generation detector which will be capable of improving the limit set by XENON10 by at least an order of magnitude.
Book Synopsis A Search for Dark Matter with the ZEPLIN II Detector by : Jianting Gao
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.
Book Synopsis The XENON100 Dark Matter Experiment by : Guillaume Plante
Download or read book The XENON100 Dark Matter Experiment written by Guillaume Plante and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes the research conducted in the context of the XENON100 dark matter search experiment. I describe the initial simulation results and ideas that influenced the design of the XENON100 detector, the construction and assembly steps that lead into its concrete realization, the detector and its subsystems, a subset of the calibration results of the detector, and finally dark matter exclusion limits. I also describe in detail the new improved measurement of the important quantity for the interpretation of results from LXe dark matter searches, the scintillation efficiency of low-energy nuclear recoils in LXe.
Book Synopsis The LZ Dark Matter Search and Development of a New Gas Phase Technique to Characterize Low Level Electron Emission from Electrode Grids by : Wei Ji
Download or read book The LZ Dark Matter Search and Development of a New Gas Phase Technique to Characterize Low Level Electron Emission from Electrode Grids written by Wei Ji and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Dark Matter is needed to explain many cosmological observations and therefore has been proposed for many decades, but it awaits direct detection. One of the most popular classes of dark matter candidates is Weakly Interacting Massive Particles (WIMPs), which have masses in the order of 100 GeV and couple to ordinary matter at weak scale. In WIMP direct detection experiments, we look for WIMPs being scattered by nuclei, a process which produces low energy (smaller than 100 keV) recoiling nuclei that can be observed. We are building LZ, a detector looking for WIMPs using liquid xenon in a dual-phase time projection chamber (TPC), at 4850 feet underground at the Sanford Underground Research Facility (SURF) in Lead, South Dakota, USA. LZ aims to achieve the world's highest sensitivity to find WIMPs via WIMP-nucleon interactions. After a brief discussion of dark matter and the LZ experiment, this dissertation presents the details of my study to solve the electron emission problem. The LZ TPC will consist of electrode grids and other metallic surfaces that can emit electrons when operated under voltage. Because the charge measurement in the LZ detector is sensitive to single electrons, electrons from the grids can be both a significant nuisance for data collection and a source of background at low-energies, limiting the sensitivity of the experiment for low-mass WIMPs. This has motivated us to develop a test detector to study how to reduce this background. The test detector consists of a pair of grids biased to high voltage and operated in xenon gas. The electric field between the grid causes the electrons to produce electroluminescence scintillation light that is measured by PMTs. This new technique is sensitive to single electrons emitted by the grids, allowing a measurement of emission currents as low as atto-amperes. We used this detector to study the properties of different grids and to determine what treatments can be done to reduce their electron emission. We found that passivation with citric acid reduces electron emission from stainless steel surfaces. This work was supervised by Professor Thomas Shutt and was completed in collaboration with members of the LZ collaboration and the SLAC LZ group.
Book Synopsis Production Yield of Muon-Induced Neutrons in Lead by : Holger Kluck
Download or read book Production Yield of Muon-Induced Neutrons in Lead written by Holger Kluck and published by Springer. This book was released on 2015-07-28 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work presented in this book is a major step towards understanding and eventually suppressing background in the direct search for dark matter particles scattering off germanium detectors. Although the flux of cosmic muons is reduced by many orders of magnitude in underground laboratories, the remaining energetic muons induce neutrons through various processes, neutrons that can potentially mimic a dark matter signal. This thesis describes the measurement of muon-induced neutrons over more than 3 years in the Modane underground laboratory. The data are complemented by a thorough modeling of the neutron signal using the GEANT4 simulation package, demonstrating the appropriateness of this tool to model these rare processes. As a result, a precise neutron production yield can be presented. Thus, future underground experiments will be able to reliably model the expected rate of muon-induced neutrons, making it possible to develop the necessary shielding concept to suppress this background component.
Book Synopsis Direct Search for Dark Matter with the DarkSide Experiment by : Paolo Agnes
Download or read book Direct Search for Dark Matter with the DarkSide Experiment written by Paolo Agnes and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A wide range of observational evidence suggests that the matter content of the Universe is dominated by a non-baryonic and non-luminous component: dark matter. One of the most favored candidate for dark matter is a big-bang relic population of Weakly Interacting Massive Particles (WIMPs). The DarkSide program aims to the direct detection of WIMPs with a dual-phase liquid argon TPC and a background free exposure. The first phase of the experiment, DarkSide-50, is running since Oct 2013 and has (46 ± 0.7) kg active mass. A first run, with an atmospheric argon fill (AAr), provided the most sensitive limit ever obtained by an argon-based experiment. The current run, with an underground argon fill (UAr, depleted in Ar-39), represents a milestone towards the construction of DarkSide-20k, a low-background dual-phase TPC with a fiducial mass of 20 t. This work is been mainly devoted to the description of G4DS, the DarkSide Monte Carlo simulation, and to its applications. G4DS is a GEANT4-based simulation, it provides the geometry description of each detector of the DarkSide program, it is tuned to reproduce the DarkSide-50 response at the percent level and incorporates a custom model for ionization and scintillation mechanisms in liquid argon, tuned on real data. The principal applications of the simulation include the estimate of the neutron and gamma backgrounds for DarkSide-50, the measurement of the Ar-39 depletion factor in UAr with respect to AAr and the design studies for DarkSide-20k.
Book Synopsis The XENON1T Spin-Independent WIMP Dark Matter Search Results and a Model to Characterize the Reduction of Electronegative Impurities in Its 3.2 Tonne Liquid Xenon Detector by : Zachary Greene
Download or read book The XENON1T Spin-Independent WIMP Dark Matter Search Results and a Model to Characterize the Reduction of Electronegative Impurities in Its 3.2 Tonne Liquid Xenon Detector written by Zachary Greene and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: XENON1T is the first tonne-scale TPC, and with 278.8 days of dark matter data has set the strictest limits on WIMP-nucleon interaction cross sections above WIMP masses of 6 GeV/c^2, with a minimum of 4.1 x10^{-47} cm^2 at 30 GeV/c^2. XENON1T and the analysis that led to this result are discussed, with an emphasis on electronic and nuclear recoil calibration fits, which help discriminate between background and WIMP-like events. Interactions in liquid xenon produce light and charge that are measured in TPCs. These signals are attenuated by electronegative impurities including O_2 and H_2O, which are homogeneously distributed throughout the liquid xenon. The decrease in observables enlarges the uncertainty in our analysis, and can decrease our sensitivity. Methods on measuring the charge loss are presented, and a physics model that describes the behavior of the electronegative impurity concentration over the lifetime of XENON1T is derived. The model is shown to successfully explain the more than two years of data.
