Read Books Online and Download eBooks, EPub, PDF, Mobi, Kindle, Text Full Free.
A Study Of Nuclear Recoil Backgrounds In Dark Matter Detectors
Download A Study Of Nuclear Recoil Backgrounds In Dark Matter Detectors full books in PDF, epub, and Kindle. Read online A Study Of Nuclear Recoil Backgrounds In Dark Matter Detectors ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
Book Synopsis A Study of Nuclear Recoil Backgrounds in Dark Matter Detectors by :
Download or read book A Study of Nuclear Recoil Backgrounds in Dark Matter Detectors written by and published by . This book was released on 2016 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt: Despite the great success of the Standard Model of particle physics, a preponderance of astrophysical evidence suggests that it cannot explain most of the matter in the universe. This so-called dark matter has eluded direct detection, though many theoretical extensions to the Standard Model predict the existence of particles with a mass on the $1-1000$ GeV scale that interact only via the weak nuclear force. Particles in this class are referred to as Weakly Interacting Massive Particles (WIMPs), and their high masses and low scattering cross sections make them viable dark matter candidates. The rarity of WIMP-nucleus interactions makes them challenging to detect: any background can mask the signal they produce. Background rejection is therefore a major problem in dark matter detection. Many experiments greatly reduce their backgrounds by employing techniques to reject electron recoils. However, nuclear recoil backgrounds, which produce signals similar to what we expect from WIMPs, remain problematic. There are two primary sources of such backgrounds: surface backgrounds and neutron recoils. Surface backgrounds result from radioactivity on the inner surfaces of the detector sending recoiling nuclei into the detector. These backgrounds can be removed with fiducial cuts, at some cost to the experiment's exposure. In this dissertation we briefly discuss a novel technique for rejecting these events based on signals they make in the wavelength shifter coating on the inner surfaces of some detectors. Neutron recoils result from neutrons scattering from nuclei in the detector. These backgrounds may produce a signal identical to what we expect from WIMPs and are extensively discussed here. We additionally present a new tool for calculating ($\alpha$, n)yields in various materials. We introduce the concept of a neutron veto system designed to shield against, measure, and provide an anti-coincidence veto signal for background neutrons. We discuss the research and development that informed the design of the DarkSide-50 boron-loaded liquid scintillator neutron veto. We describe the specific implementation of this veto system in DarkSide-50, including a description of its performance, and show that it can reject neutrons with a high enough e_ciency to allow DarkSide-50 to run background-free for three years.
Book Synopsis First Results from a Twenty-liter Prototype Dark Matter Detector with Directional Sensitivity by : Jeremy Paul Lopez
Download or read book First Results from a Twenty-liter Prototype Dark Matter Detector with Directional Sensitivity written by Jeremy Paul Lopez and published by . This book was released on 2014 with total page 199 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astronomical and cosmological evidence suggests that 27% of the energy content of the universe is in the form of non-baryonic matter referred to as "dark matter." Weakly interacting massive particles have long been considered attractive candidates for this dark matter and can be found in a wide variety of models of physics beyond the Standard Model. The Dark Matter Time Projection Chamber experiment uses low-pressure gas time projection chambers to search for nuclear recoils caused by interactions between nuclei inside a detector and weakly interacting massive particles in the dark matter halo of the Milky Way galaxy. These detectors are also able to reconstruct the directions of these nuclear recoils, allowing for better rejection of possible background events. This thesis describes the design of a small prototype detector and the strategies used by the DMTPC collaboration to reconstruct events, reject backgrounds, and identify nuclear recoil candidate events. It presents the results of several studies aimed at understanding background events in DMTPC detectors. Finally, this work will present the first results from a nuclear recoil search taken with this detector in a surface laboratory at MIT.
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 Study of Excess Electronic Recoil Events in XENON1T by : Evan Shockley
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.
Book Synopsis Optimizing the Design and Analysis of Cryogenic Semiconductor Dark Matter Detectors for Maximum Sensitivity by : Matt Christopher Pyle
Download or read book Optimizing the Design and Analysis of Cryogenic Semiconductor Dark Matter Detectors for Maximum Sensitivity written by Matt Christopher Pyle and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: For the past 15 years, the Cryogenic Dark Matter Search or CDMS has searched for Weekly Interacting Massive Particle dark matter (WIMPs) using Ge and Si semiconductor crystals instrumented with both ionization and athermal phonon sensors so that the much more common electron recoil leakage caused by photons and [beta]s from naturally present radioactive elements can be easily distinguished from elastic WIMP nucleon interactions by looking at the fraction of total recoil energy which ends up as potential energy of e/h pairs. Due to electronic carrier trapping at the surface of our semiconductor crystals, electron recoils which occur near the surface have suppressed ionization measurements and can not be distinguished from WIMP induced nuclear recoils and thus sensitivity to the WIMP nucleon interaction cross section was driven in CDMS II by our ability to define a full 3D fiducial volume in which all events had full collection. To remain background free and maximally sensitive to the WIMPnucleus interaction cross section, we must improve our 3D fiducial volume definition at the same rate as we scale the mass of the detector, and thus proposed next generation experiments with an order of magnitude increase in active mass were unfortunately not possible with our previous CDMS II detector design, and a new design with significantly improved fiducialization performance is required. In this thesis, we illustrate how the complex E-field geometry produced by interdigitated electrodes at alternating voltage biases naturally encodes 3D fiducial volume information into the charge and phonon signals and thus is a natural geometry for our next generation dark matter detectors. Secondly, we will study in depth the physics of import to our devices including transition edge sensor dynamics, quasi- particle dynamics in our Al collection fins, and phonon physics in the crystal itself so that we can both understand the performance of our previous CDMS II device as well as optimize the design of our future devices. Of interest to the broader physics community is the derivation of the ideal athermal phonon detector resolution and it's cubic temperature scaling behavior which suggests that the athermal phonon detector technology developed by CDMS could also be used to discover coherent neutrino scattering and search for non-standard neutrino interaction and sterile neutrinos. These proposed resolution optimized devices can also be used in searches for exotic MeV-GeV dark matter as well as novel background free searches for 8GeV light WIMPs. Initial performance studies of our first two next generation iZIP detectors at the University of California Berkeley CDMS test facility indicate that electron recoil surface event misidentification is 2x10-5 ±2.5x10-5 (90%CL) for a recoil energy range of 8keVr-60keVr strongly indicating that z fiducial volume performance will not limit our WIMP sensitivity in next generation experiments. Furthermore, phonon only fiducial volume selections were created for nuclear recoil energies 2keVr suggesting that phonon only background free or background subtracting light WIMP mass experiments are potentially viable.
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 Muon-induced Backgrounds in the DM-Ice17 NaI(TI) Dark Matter Detector by :
Download or read book Muon-induced Backgrounds in the DM-Ice17 NaI(TI) Dark Matter Detector written by and published by . This book was released on 2015 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt: The DM-Ice experiment uses NaI(Tl) to directly search for the annual modulation expected from a WIMP dark matter signal. The DAMA NaI(Tl) experiment has observed a modulation, consistent with dark matter, that has been excluded by other experiments. No background model has been able to successfully explain the DAMA signal. To definitely confirm or deny the dark matter interpretation of this modulation, a NaI(Tl) experiment with different backgrounds must be run. Detecting this modulation requires the observation of rare, single-keV nuclear recoil signals. DM-Ice17, the first of three generations of detectors in the DM-Ice experiment, has run with 17 kg of NaI(Tl) in the South Pole ice since December 2010. DM-Ice17 has proved the feasibility of running such an experiment in the South Pole ice. DM-Ice17 continues to take data while R&D is underway with the second-generation DM-Ice37 detector. Once background levels ideal for a WIMP search are achieved, the full-scale, 250kg DM-Ice250 detector will be commissioned. As a direct detection dark matter experiment in the Southern Hemisphere, the full-scale experiment will have a unique capability to disentangle the WIMP modulation from seasonal variations. This work focuses on the data analysis of the DM-Ice17 detector, with particular emphasis on muon- induced backgrounds. Muons, identified by their energy deposition and pulse shape, are observed by DM- Ice17 to modulate annually with a 14% fractional amplitude. The highest energy muon events in the crystal induce a long-lived phosphorescence. When this occurs, the detector rate rises significantly, and a cascade of low energy events appears over tens of seconds. The possible contribution of these events to dark matter searches in NaI(Tl) is explored. DM-Ice17 is located within the volume of the IceCube Neutrino Observatory, allowing the analysis of events coincident between the two detectors. These events validate the DM-Ice17 muon tag and provide a novel confirmation of the reported resolution of IceCube reconstructions. They provide additional information that is particularly useful for low energy events in IceCube. This study is particularly relevant given the growing interest in the deployment of scintillators with PINGU. In this thesis, I present an overview of dark matter theory (Chapter 1) and candidates (Chapter 2), followed by the current status of the experimental dark matter field (Chapter 3). Special emphasis is given to NaI(Tl) dark matter experiments and their development. The mechanics of scintillation are discussed (Chapter 4), including the nature of long-lived phosphorescence, followed by a description of DM-Ice (Chapter 5). The data analysis of DM-Ice17 is discussed (Chapter 6), with particular attention given to the energy calibration. The muon and muon-induced backgrounds in DM-Ice17 are presented (Chapter 7), including details of the observed modulation and muon-induced phosphorescence in the low energy region. The observation of muon events coincident with IceCube is discussed (Chapter 8), and finally the status of DM-Ice37 detector (Chapter 9) and the conclusions from the DM-Ice17 detector (Chapter 10) are presented.
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.
Download or read book Dark Matter written by Debasish Majumdar and published by CRC Press. This book was released on 2014-08-27 with total page 271 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dark Matter: An Introduction tackles the rather recent but fast-growing subject of astroparticle physics, encompassing three main areas of fundamental physics: cosmology, particle physics, and astrophysics. Accordingly, the book discusses symmetries, conservation laws, relativity, and cosmological parameters and measurements, as well as the astrophysical behaviors of galaxies and galaxy clusters that indicate the presence of dark matter and the possible nature of dark matter distribution. This succinct yet comprehensive volume: Addresses all aspects essential to the study of dark matter Explores particle candidates for cold dark matter beyond the theory of the standard model, providing examples of basic extensions and introducing theories such as supersymmetry and extra dimensions Explains—in simple text and mathematical formulations—calculation of the freeze-out temperature of a dark matter species and its relic density Provides theoretical background for dark matter scattering off a target, event rate calculation, and dark matter annihilation essential to study direct and indirect detection of dark matter Complete with a detailed review of the latest dark matter experiments and techniques, Dark Matter: An Introduction is an ideal text for beginning researchers in the field as well as for general readers with an inquisitive mind, as the important topic of astroparticle physics is treated both pedagogically and with deeper insight.
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 Update on the MiniCLEAN Dark Matter Experiment by :
Download or read book Update on the MiniCLEAN Dark Matter Experiment written by and published by . This book was released on 2015 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The direct search for dark matter is entering a period of increased sensitivity to the hypothetical Weakly Interacting Massive Particle (WIMP). One such technology that is being examined is a scintillation only noble liquid experiment, MiniCLEAN. MiniCLEAN utilizes over 500 kg of liquid cryogen to detect nuclear recoils from WIMP dark matter and serves as a demonstration for a future detector of order 50 to 100 tonnes. The liquid cryogen is interchangeable between argon and neon to study the A2 dependence of the potential signal and examine backgrounds. MiniCLEAN utilizes a unique modular design with spherical geometry to maximize the light yield using cold photomultiplier tubes in a single-phase detector. Pulse shape discrimination techniques are used to separate nuclear recoil signals from electron recoil backgrounds. MiniCLEAN will be spiked with additional 39Ar to demonstrate the effective reach of the pulse shape discrimination capability. Assembly of the experiment is underway at SNOLAB and an update on the project is given.
Book Synopsis Reconstructing Nuclear Recoil Tracks in the Dark Matter Time Projection Chamber by : William Bradley Fedus
Download or read book Reconstructing Nuclear Recoil Tracks in the Dark Matter Time Projection Chamber written by William Bradley Fedus and published by . This book was released on 2010 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astrophysical evidence indicates that 23% of our universe's energy density is in the form of nonluminous, nonbaryonic matter referred to as dark matter. One theoretically appealing dark matter candidate is the Weakly Interacting Massive Particle (WIMP). Because of astrophysical dynamics, the detectable signal from the expected WIMP dark matter halo should exhibit a unique daily directional modulation for which experiments can search . The Dark Matter Time Projection Chamber (DMTPC) group aims to provide an unequivocal detection of WIMP particles through the anisotropy in the angular recoil spectrum. DMTPC uses a low-pressure time projection chamber filled with CF 4 gas to search for WIMPs via elastic collisions. Crucial to this experiment is the fidelity of nuclear recoil track reconstruction. By extracting parameters such as the angle and vector direction of nuclear recoils, DMTPC has sensitivity to the anisotropic WIMP signal. This thesis develops a new track reconstruction algorithm motivated by the physics of nuclear energy loss in a diffuse gas medium. The algorithm is applied to simulated nuclear recoils and is compared to the existing track reconstruction algorithm. The new fitting algorithm outperforms the old algorithm in determining vector direction of nuclear recoils for recoil energies between 20 and 300 keV. The algorithm shows little sensitivity to CCD read noise. The length reconstruction of the new algorithm, however, fails to outperform the old algorithm below 100 keV.
Book Synopsis The Coherent Photon Scattering Background in Sub-GeV/$c^2$ Direct Dark Matter Searches by :
Download or read book The Coherent Photon Scattering Background in Sub-GeV/$c^2$ Direct Dark Matter Searches written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Proposed dark matter detectors with eV-scale sensitivities will detect a large background of atomic (nuclear) recoils from coherent photon scattering. This background climbs steeply below $\sim10$~eVnr, far exceeding the declining rate of low-energy Compton recoils. The upcoming generation of dark matter detectors will not be limited by this background, but further development of eV-scale and sub-eV detectors will require the use of low-$Z$ target materials, such as helium, to avoid a large rate of coherent photon scattering.
Book Synopsis Analysis of the First Underground Run and Background Studies of the Argon Dark Matter Experiment by : Bárbara Rosario Montes Núñez
Download or read book Analysis of the First Underground Run and Background Studies of the Argon Dark Matter Experiment written by Bárbara Rosario Montes Núñez and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Dark Matter is a collisionless and non-luminous kind of matter, whose existence is inferred through its gravitational e ects at the galactic, cluster and large scales in the Universe. From the analysis of the PLANCK latest data, Dark Matter accounts for the 26.6% of the composition of the energy density of the Universe, while ordinary matter only represents 4.9% [1]. Revealing the nature of Dark Matter has become one of the most challenging problems in modern physics. A possible explanation comes from particle physics in the form of Weakly Interacting Massive Particles (WIMPs), a particularly interesting class of new particle that can naturally account for the measured abundance of Dark Matter. WIMPs would be produced thermally in the early Universe and, since they interact only weakly, their annihilation rate would become insigni cant as the Universe expands, thus freezing out with a relic abundance. Supersymmetry, an extension of the Standard Model of particle physics, foresees interesting possible WIMP candidates in the form of the Lightest Supersymmetric Particle (LSP), which is neutral, stable and massive. A great experimental e ort has been undertaken in the last years to detect Dark Matter in underground and space-based detectors or produce it in accelerators. This Thesis is focused on the analysis of the rst underground run and background studies of the Argon Dark Matter (ArDM) experiment, which aims to detect WIMPs via the nuclear recoils produced by their elastic scattering o argon nuclei. The detector is a ton-scale double-phase (liquid-gas) TPC, which is currently installed at the Canfranc Underground Laboratory (LSC) under the Pyrenees in Spain and it is the rst ton-scale argon detector for Dark Matter to take data underground...
Book Synopsis The Low-mass Limit by : Noah Kurinsky
Download or read book The Low-mass Limit written by Noah Kurinsky and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The SuperCDMS SNOLAB experiment will be a 20-kg scale Si and Ge direct dark matter detection experiment designed to probe down to 300 MeV in dark matter (DM) mass through DM-nucleus scattering and 500 keV in DM electron scattering. In order to reach these low masses with appreciable sensitivity to dark matter, it needs to achieve very low energy resolution (≤ 10 ev) for nuclear recoils in both detector materials, which will be achieved using a new detector design and operating mode, CDMS HV. This detector is designed to operate at a bias of 100V to convert charges liberated in our detector targets to into phonon energy in order to resolve individual electron-hole pairs. This has never before been achieved in a kg-scale detector. In this thesis, I cover three elements of the design of the CDMS HV detectors. I discuss the detector physics controlling how charges and phonons are generated in our detector crystals, com- paring theory to results of recent experiments carried out at Stanford. I move on to describe the operating principles of our phonon-mediated charge readout, as well as the design of the CDMS HV detector. I then describe the performance tests of early CDMS HV prototypes in conjunction with the SuperCDMS SNOLAB electronics, and discuss the path towards achieving single electron-hole pair resolving detectors at the kg-scale given the performance obtained thus far. As a result of these tests, we were able to refine our noise and sensor dynamics models, and develop new metrics for diagnosing non-ideal sources of noise to aid in reducing coupling of the external environment to our detectors. In order to study the microphysics of phonon and charge production in our target crystals, we fabricated a number of gram-scale devices with various sensor designs in order to separate sensor and environmental effects from intrinsic crystal properties. These devices provided the first successful demonstrating of using voltage to amplify charge energy by production of phonons (the Neganov-Trofimov-Luke effect) in order to resolve electron-hole pairs, and opened up a new regime of dark matter and photon science at the gram-scale that we are just beginning to explore. A first dark matter search was carried out with one of these gram-scale devices, producing world-leading limits on electron-recoiling dark matter between 0.5 and 5 MeV in dark matter mass for multiple form factors. This device achieved a phonon resolution of 10 eV, allowing a single gram-day of exposure to rival kg-days of exposure in the competing liquid-noble based electron-recoil search.
Book Synopsis Directional Detection of Dark Matter in Universal Bound States by :
Download or read book Directional Detection of Dark Matter in Universal Bound States written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: It has been suggested that several small-scale structure anomalies in ? CDM cosmology can be solved by strong self-interaction between dark matter particles. It was shown in Ref. [1] that the presence of a near threshold S-wave resonance can make the scattering cross section at nonrelativistic speeds come close to saturating the unitarity bound. This can result in the formation of a stable bound state of two asymmetric dark matter particles (which we call darkonium). Ref. [2] studied the nuclear recoil energy spectrum in dark matter direct detection experiments due to this incident bound state. Here we study the angular recoil spectrum, and show that it is uniquely determined up to normalization by the S-wave scattering length. Furthermore, observing this angular recoil spectrum in a dark matter directional detection experiment will uniquely determine many of the low-energy properties of dark matter independent of the underlying dark matter microphysics.
Book Synopsis Measurement of the Low Energy Nuclear Response in NaI(T1) Crystals for Use in Dark Matter Direct Detection Experiments by : Tyana Michele Stiegler
Download or read book Measurement of the Low Energy Nuclear Response in NaI(T1) Crystals for Use in Dark Matter Direct Detection Experiments written by Tyana Michele Stiegler and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The response of low energy nuclear recoil in NaI(T1) is investigated in the following experiment. Such detectors have been used recently to search for evidence of dark matter in the form of weakly interacting massive particles (WIMPs). NaI(T1) crystal response to nuclear recoil energy deposition is a key element in these searches. I discuss the cosmological and experimental motivations for these experiments, followed by an overview of the physics of direct detection and current relevant WIMP search experiments. With the experiment motivations covered, the details of NaI(T1) detectors are reviewed. The specifics of our experiment are laid out including the neutron production, neutron beam calibration, shielding optimization, experimental design and setup. Then the crystal response calibration studies and Geant4 simulations are discussed followed by the final quenching factor values and uncertainties. This experiment measured quenching factors for sodium recoils in the energy range of (9 keV-40 keV) of 19%-27% QF. These results are similar to current published measurements. Interesting features of the QF measurements include an increase at low energies and a dip in the values at 30 keV, the iodine K-shell absorption edge. The goal of this experiment was to add valuable measurements of nuclear recoils at low energies that are relevant to low-mass WIMP experiments. Future plans will improve and expand on these measurements in order to better understand the response of NaI(T1) at low energies. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151303
