Download or read book The Cryogenic Dark Matter Search and Background Rejection with Event Position Information written by Gensheng Wang and published by . This book was released on 2005 with total page 345 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Cryogenic Dark Matter Search and Background Rejection with Event Position Information written by and published by . This book was released on 2005 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt: Evidence from observational cosmology and astrophysics indicates that about one third of the universe is matter, but that the known baryonic matter only contributes to the universe at 4%. A large fraction of the universe is cold and non-baryonic matter, which has important role in the universe structure formation and its evolution. The leading candidate for the non-baryonic dark matter is Weakly Interacting Massive Particles (WIMPs), which naturally occurs in the supersymmetry theory in particle physics. The Cryogenic Dark Matter Search (CDMS) experiment is searching for evidence of a WIMP interaction off an atomic nucleus in crystals of Ge and Si by measuring simultaneously the phonon energy and ionization energy of the interaction in the CDMS detectors. The WIMP interaction energy is from a few keV to tens of keV with a rate less than 0.1 events/kg/day. To reach the goal of WIMP detection, the CDMS experiment has been conducted in the Soudan mine with an active muon veto and multistage passive background shields. The CDMS detectors have a low energy threshold and background rejection capabilities based on ionization yield. However, betas from contamination and other radioactive sources produce surface interactions, which have low ionization yield, comparable to that of bulk nuclear interactions. The low-ionization surface electron recoils must be removed in the WIMP search data analysis. An emphasis of this thesis is on developing the method of the surface-interaction rejection using location information of the interactions, phonon energy distributions and phonon timing parameters. The result of the CDMS Soudan run118 92.3 live day WIMP search data analysis is presented, and represents the most sensitive search yet performed.

Download or read book First Results from the Cryogenic Dark Matter Search Experiment at the Deep Site written by Vuk Mandic and published by . This book was released on 2004 with total page 922 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book First Results from the Cryogenic Dark Matter Search Experiment at the Deep Site written by and published by . This book was released on 2004 with total page 454 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Cryogenic Dark Matter Search (CDMS) experiment is designed to search for dark matter in the form of the Weakly Interacting Massive Particles (WIMPs). For this purpose, CDMS uses detectors based on crystals of Ge and Si, operated at the temperature of 20 mK, and providing a two-fold signature of an interaction: the ionization and the athermal phonon signals. The two signals, along with the passive and active shielding of the experimental setup, and with the underground experimental sites, allow very effective suppression and rejection of different types of backgrounds. This dissertation presents the commissioning and the results of the first WIMP-search run performed by the CDMS collaboration at the deep underground site at the Soudan mine in Minnesota. We develop different methods of suppressing the dominant background due to the electron-recoil events taking place at the detector surface and we apply these algorithms to the data set. These results place the world's most sensitive limits on the WIMP-nucleon spin-independent elastic-scattering cross-section. Finally, they examine the compatibility of the supersymmetric WIMP-models with the direct-detection experiments (such as CDMS) and discuss the implications of the new CDMS result on these models.

Download or read book The Cryogenic Dark Matter Search CDMS written by Peter David Barnes and published by . This book was released on 1996 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Results from the Two tower Run of the Cryogenic Dark Matter Search written by Angela Jean Reisetter and published by . This book was released on 2005 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of New Cryogenic Low threshold Detectors for the Search of Light Dark Matter and Low energy Neutrino Physics written by Dimitri Misiak and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Coherent Elastic Neutrino-Nucleus Scattering (CENNS) is a process predicted nearly 40 years ago. In August 2017, the COHERENT experiment reported the first keV-scale detection at the 6.7 sigma level of this process, which is a probe for the new low energy physics, opening a window on a myriad of new physics opportunities. The RICOCHET experiment aims at measuring with high accuracy the CENNS process in order to probe various exotic physics scenarios in the electroweak sector. Using cryogenic bolometers operated in a cryostat 8 meters away from the core of the ILL research nuclear reactor, the experiment will benefit from an intense neutrino flux, allowing the results of COHERENT to be reproduced in a single week. The objective of an accurate measurement will be achieved after one year of data collection, by 2024. The CRYOCUBE is a compact cubic array of cryogenic detectors with the following specifications: a very low energy threshold of O(10) eV on the thermal signal, an electromagnetic background rejection of at least 10^3 and a total target mass of 1 kg distributed among 27 germanium crystals of about 30 g each. The objective of this thesis is to propose an optimized detector design for the CRYOCUBE, inspired by the cryogenic germanium detectors equipped with charge and temperature readings of the direct dark matter search experiment EDELWEISS. This joint R&D program is based on event discrimination realized in germanium semiconductor crystals. The recoil energy of an incident particle is derived either from the increase of the crystal temperature measured by a GeNTD thermistor (heat channel) or from the excited electric charges collected by electrodes on its surface (ionization channel). This double energy measurement makes it possible to distinguish the nuclear recoils produced by the CENNS or the dark matter from the electronic radioactive background. As these recoils are of the order of O(100) eV, this thesis work is focused on the development of a new generation of cryogenic low threshold germanium detectors with particle identification. It explores how to improve the resolution in heat and ionization energy up to O(10) eV while maintaining a good rejection of background events. This study is based on the testing of prototype detectors in the IP2I cryostat, which are compared to theoretical predictions from electro-thermal and electrostatic modeling of the detectors. This manuscript begins with the definition of the CENNS process, its scientific importance and the objectives of the RICOCHET experiment. It then presents the cryogenic installation allowing the surface operation of the detectors at 20 mK in optimal conditions. An electro-thermal model of the bolometers, compared with experimental data, is developed and applied to the simulation of the noise associated with the electronics of the heat signal. The thesis then formalizes the generation of the ionization signals arising from excited charge carriers drifting in the germanium crystal under the influence of the applied electric field. The expected resolution from a future low-noise electronics is modeled based on two detector designs. They are optimized by their electrostatic simulation in a finite element calculation software. A comparison of the theoretical and experimental performance of ionization is performed on the basis of the RED80 and REDN1 prototype detectors. This work ends with the characterization of the radioactive background in the cryogenic laboratory with the analysis of the data from RED80, and in particular its neutron component, used to estimate the expected background at the ILL site for RICOCHET.

Download or read book A Time Domain Phonon Pulse Fitting Analysis for the Cryogenic Dark Matter Search Experiment written by Chandler Schlupf and published by . This book was released on 2014 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dark matter makes up 85% of the known matter in the Universe, but the exact nature of dark matter remains unknown. The Cryogenic Dark Matter Search experiment, CDMS, attempts to directly detect the leading candidate dark matter particle, the Weakly Interacting Massive Particle (WIMP), recoiling off of cold germanium crystals. When particles interact with the crystals' atoms, they produce two measurable signals: phonons and ionization. The phonon signal contains information about the event such as its type, energy, and position, and has a much better resolution for lower energy events than does the ionization, especially for nuclear recoils from WIMPs. Because of this, there is a strong motivation for extracting as much information as possible from the phonon signal. For my thesis, the raw phonon pulse signal in the time domain was fit to a functional form based on phonon physics within the crystal. The functional form was carefully checked using the Markov chain Monte Carlo method. A Boosted Decision Tree (BDT) was then used to analyze the parameters from the fits to determine how well the parameters could distinguish between event types such as nuclear versus electron recoil events, and surface versus bulk events. Cuts made on the data, from results of the BDTs that were analyzed with parameters from this time-domain fitting algorithm, yielded better descrimination power than ones that were analyzed with the parameters currently used by CDMS. Applying this method to data mimicking a 15 GeV WIMP distribution produced a 34.4% signal efficiency improvement over the values currently used by CDMS.

Download or read book A Search for Low mass Dark Matter with the Cryogenic Dark Matter Search and the Development of Highly Multiplexed Phonon mediated Particle Detectors written by and published by . This book was released on 2012 with total page 263 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Cryogenic Dark Matter Search written by and published by . This book was released on 2010 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Cryogenic Dark Matter Search (CDMS) is searching for Weakly Interacting Massive Particles (WIMPs) with cryogenic particle detectors. These detectors have the ability to discriminate between nuclear recoil candidate and electron recoil background events by collecting both phonon and ionization energy from recoils in the detector crystals. The CDMS-II experiment has completed analysis of the first data runs with 30 semiconductor detectors at the Soudan Underground Laboratory, resulting in a world leading WIMP-nucleon spin-independent cross section limit for WIMP masses above 44 GeV/c2. As CDMS aims to achieve greater WIMP sensitivity, it is necessary to increase the detector mass and discrimination between signal and background events. Incomplete ionization collection results in the largest background in the CDMS detectors as this causes electron recoil background interactions to appear as false candidate events. Two primary causes of incomplete ionization collection are surface and bulk trapping. Recent work has been focused on reducing surface trapping through the modification of fabrication methods for future detectors. Analyzing data taken with test devices has shown that hydrogen passivation of the amorphous silicon blocking layer worsens surface trapping. Additional data has shown that the iron-ion implantation used to lower the critical temperature of the tungsten transition-edge sensors causes a degradation of the ionization collection. Using selective implantation on future detectors may improve ionization collection for events near the phonon side detector surface. Bulk trapping is minimized by neutralizing ionized lattice impurities. Detector investigations at testing facilities and in situ at the experimental site have provided methods to optimize the neutralization process and monitor running conditions to maintain full ionization collection. This work details my contribution to the 5-tower data taking, monitoring, and analysis effort as well as the SuperCDMS detector development with the focus on monitoring and improving ionization collection in the detectors.

Download or read book Low Mass Dark Matter Search Results and Radiogenic Backgrounds for the Cryogenic Dark Matter Search written by and published by . This book was released on 2016 with total page 437 pages. Available in PDF, EPUB and Kindle. Book excerpt: An ever-increasing amount of evidence suggests that approximately one quarter of the energy in the universe is composed of some non-luminous, and hitherto unknown, "dark matter". Physicists from numerous sub-fields have been working on and trying to solve the dark matter problem for decades. The common solution is the existence of some new type of elementary particle with particular focus on weakly interacting massive particles (WIMPs). One avenue of dark matter research is to create an extremely sensitive particle detector with the goal of directly observing the interaction of WIMPs with standard matter. The Cryogenic Dark Matter Search (CDMS) project operated at the Soudan Underground Laboratory from 2003-2015, under the CDMS II and SuperCDMS Soudan experiments, with this goal of directly detecting dark matter. The next installation, SuperCDMS SNOLAB, is planned for near-future operation. The reason the dark-matter particle has not yet been observed in traditional particle physics experiments is that it must have very small cross sections, thus making such interactions extremely rare. In order to identify these rare events in the presence of a background of known particles and interactions, direct detection experiments employ various types and amounts of shielding to prevent known backgrounds from reaching the instrumented detector(s). CDMS utilized various gamma and neutron shielding to such an effect that the shielding, and other experimental components, themselves were sources of background. These radiogenic backgrounds must be understood to have confidence in any WIMP-search result. For this dissertation, radiogenic background studies and estimates were performed for various analyses covering CDMS II, SuperCDMS Soudan, and SuperCDMS SNOLAB. Lower-mass dark matter t c2 inent in the past few years. The CDMS detectors can be operated in an alternative, higher-biased, mode v to decrease their energy thresholds and correspondingly increase their sensitivity to low-mass WIMPs. This is the CDMS low ionization threshold experiment (CDMSlite), which has pushed the frontier at lower WIMP masses. This dissertation describes the second run of CDMSlite at Soudan: its hardware, operations, analysis, and results. The results include new WIMP mass-cross section upper limits on the spin-independent and spin-dependent WIMP-nucleon interactions. Thanks to the lower background and threshold in this run compared to the first CDMSlite run, these limits are the most sensitive in the world below WIMP masses of ~4 GeV/c2. This demonstrates also the great promise and utility of the high-voltage operating mode in the SuperCDMS SNOLAB experiment.

Download or read book Background Reduction in Cryogenic Detectors written by Daniel A. Bauer and published by . This book was released on 2005 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper discusses the background reduction and rejection strategy of the Cryogenic Dark Matter Search (CDMS) experiment. Recent measurements of background levels from CDMS II at Soudan are presented, along with estimates for future improvements in sensitivity expected for a proposed SuperCDMS experiment at SNOLAB.

Download or read book Exclusion Limits on the WIMP nucleon Cross Section from the First Run of the Cryogenic Dark Matter Search in the Soudan Underground Laboratory written by and published by . This book was released on 2005 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Cryogenic Dark Matter Search (CDMS-II) employs low-temperature Ge and Si detectors to seek Weakly Interacting Massive Particles (WIMPs) via their elastic scattering interactions with nuclei. Simultaneous measurements of both ionization and phonon energy provide discrimination against interactions of background particles. For recoil energies above 10 keV, events due to background photons are rejected with> 99.99% efficiency. Electromagnetic events very near the detector surface can mimic nuclear recoils because of reduced charge collection, but these surface events are rejected with> 96% efficiency by using additional information from the phonon pulse shape. Efficient use of active and passive shielding, combined with the 2090 m.w.e. overburden at the experimental site in the Soudan mine, makes the background from neutrons negligible for this first exposure. All cuts are determined in a blind manner from in situ calibrations with external radioactive sources without any prior knowledge of the event distribution in the signal region. Resulting efficiencies are known to (almost equal to)10%. A single event with a recoil of 64 keV passes all of the cuts and is consistent with the expected misidentification rate of surface-electron recoils. Under the assumptions for a standard dark matter halo, these data exclude previously unexplored parameter space for both spin-independent and spin-dependent WIMP-nucleon elastic scattering. The resulting limit on the spin-independent WIMP-nucleon elastic-scattering cross-section has a minimum of 4 x 10−43 cm2 at a WIMP mass of 60 GeV c−2. The minimum of the limit for the spin-dependent WIMP-neutron elastic-scattering cross-section is 2 x 10−37 cm2 at a WIMP mass of 50 GeV c−2.

Download or read book Huguenot Society of America Membership Application of Joseph N Wright of Trenton New Jersey Descendant of Isaac Garnee written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Cryogenic Phonon Detector to Search for Dark Matter Particles written by Ning Wang and published by . This book was released on 1991 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Cryogenic Dark Matter Search First 5 Tower Data and Improved Understanding of Ionization Collection written by Catherine N. Bailey and published by . This book was released on 2010 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Cryogenic Dark Matter Search (CDMS) is searching for Weakly Interacting Massive Particles (WIMPs) with cryogenic particle detectors. These detectors have the ability to discriminate between nuclear recoil candidate and electron recoil background events by collecting both phonon and ionization energy from recoils in the detector crystals. The CDMS-II experiment has completed analysis of the Ơ̐1rst data runs with 30 semiconductor detectors at the Soudan Underground Laboratory, resulting in a world leading WIMP-nucleon spin-independent cross section limit for WIMP masses above 44 GeV/c^2. As CDMS aims to achieve greater WIMP sensitivity, it is necessary to increase the detector mass and discrimination between signal and background events. Incomplete ionization collection results in the largest background in the CDMS detectors as this causes electron recoil background interactions to appear as false candidate events. Two primary causes of incomplete ionization collection are surface and bulk trapping. Recent work has been focused on reducing surface trapping through the modiƠ̐1cation of fabrication methods for future detectors. Analyzing data taken with test devices has shown that hydrogen passivation of the amorphous silicon blocking layer worsens surface trapping. Additional data has shown that the iron-ion implantation used to lower the critical temperature of the tungsten transition-edge sensors causes a degradation of the ionization collection. Using selective implantation on future detectors may improve ionization collection for events near the phonon side detector surface. Bulk trapping is minimized by neutralizing ionized lattice impurities. Detector investigations at testing facilities and in situ at the experimental site have provided methods to optimize the neutralization process and monitor running conditions to maintain full ionization collection. This work details my contribution to the 5-tower data taking, monitoring, and analysis eƠ̐0ort as well as the SuperCDMS detector development with the focus on monitoring and improving ionization collection in the detectors.

Download or read book A Search for Particle Dark Matter Using Cryogenic Germanium and Silicon Detectors in the One and Two Tower Runs of CDMS II at Soudan written by and published by . This book was released on 2008 with total page 333 pages. Available in PDF, EPUB and Kindle. Book excerpt: Images of the Bullet Cluster of galaxies in visible light, X-rays, and through gravitational lensing confirm that most of the matter in the universe is not composed of any known form of matter. The combined evidence from the dynamics of galaxies and clusters of galaxies, the cosmic microwave background, big bang nucleosynthesis, and other observations indicates that 80% of the universe's matter is dark, nearly collisionless, and cold. The identify of the dar, matter remains unknown, but weakly interacting massive particles (WIMPs) are a very good candidate. They are a natural part of many supersymmetric extensions to the standard model, and could be produced as a nonrelativistic, thermal relic in the early universe with about the right density to account for the missing mass. The dark matter of a galaxy should exist as a spherical or ellipsoidal cloud, called a 'halo' because it extends well past the edge of the visible galaxy. The Cryogenic Dark Matter Search (CDMS) seeks to directly detect interactions between WIMPs in the Milky Way's galactic dark matter halo using crystals of germanium and silicon. Our Z-sensitive ionization and phonon ('ZIP') detectors simultaneously measure both phonons and ionization produced by particle interactions. In order to find very rare, low-energy WIMP interactions, they must identify and reject background events caused by environmental radioactivity, radioactive contaminants on the detector, s and cosmic rays. In particular, sophisticated analysis of the timing of phonon signals is needed to eliminate signals caused by beta decays at the detector surfaces. This thesis presents the firs two dark matter data sets from the deep underground experimental site at the Soudan Underground Laboratory in Minnesota. These are known as 'Run 118', with six detectors (1 kg Ge, 65.2 live days before cuts) and 'Run 119', with twelve detectors (1.5 kg Ge, 74.5 live days before cuts). They have analyzed all data from the two runs together in a single, combined analysis, with sensitivity to lower-energy interactions, careful control of data quality and stability, and further development of techniques for reconstructing event location and rejecting near-surface interactions from beta decays. They also present a revision to the previously published Run 119 analysis, a demonstration of the feasibility of a low-threshold (1 or 2 keV) analysis of Soudan data, and a review of the literature on charge generation and quenching relevant to the ionization signal.