A Search For Wimp Dark Matter Using An Optimized Chi Square Technique On The Final Data From The Cryogenic Dark Matter Search Experiment Cdms Ii

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A Search for WIMP Dark Matter Using an Optimized Chi-square Technique on the Final Data from the Cryogenic Dark Matter Search Experiment (CDMS II).

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ISBN 13 :
Total Pages : 447 pages
Book Rating : 4.:/5 (953 download)

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Book Synopsis A Search for WIMP Dark Matter Using an Optimized Chi-square Technique on the Final Data from the Cryogenic Dark Matter Search Experiment (CDMS II). by :

Download or read book A Search for WIMP Dark Matter Using an Optimized Chi-square Technique on the Final Data from the Cryogenic Dark Matter Search Experiment (CDMS II). written by and published by . This book was released on 2012 with total page 447 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation describes the results of a WIMP search using CDMS II data sets accumulated at the Soudan Underground Laboratory in Minnesota. Results from the original analysis of these data were published in 2009; two events were observed in the signal region with an expected leakage of 0.9 events. Further investigation revealed an issue with the ionization-pulse reconstruction algorithm leading to a software upgrade and a subsequent reanalysis of the data. As part of the reanalysis, I performed an advanced discrimination technique to better distinguish (potential) signal events from backgrounds using a 5-dimensional chi-square method. This dataanalysis technique combines the event information recorded for each WIMP-search event to derive a backgrounddiscrimination parameter capable of reducing the expected background to less than one event, while maintaining high efficiency for signal events. Furthermore, optimizing the cut positions of this 5-dimensional chi-square parameter for the 14 viable germanium detectors yields an improved expected sensitivity to WIMP interactions relative to previous CDMS results. This dissertation describes my improved (and optimized) discrimination technique and the results obtained from a blind application to the reanalyzed CDMS II WIMP-search data.

The Cryogenic Dark Matter Search

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ISBN 13 :
Total Pages : 286 pages
Book Rating : 4.:/5 (16 download)

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Book Synopsis The Cryogenic Dark Matter Search by :

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.

The Cryogenic Dark Matter Search: First 5-Tower Data and Improved Understanding of Ionization Collection

Author : Catherine N. Bailey
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ISBN 13 :
Total Pages : 286 pages
Book Rating : 4.:/5 (495 download)

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Book Synopsis The Cryogenic Dark Matter Search: First 5-Tower Data and Improved Understanding of Ionization Collection by : Catherine N. Bailey

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.

First Results from the Cryogenic Dark Matter Search Experiment at the Deep Site

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ISBN 13 :
Total Pages : 454 pages
Book Rating : 4.:/5 (16 download)

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Book Synopsis First Results from the Cryogenic Dark Matter Search Experiment at the Deep Site by :

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.

A Dark-matter Search Using the Final CDMS II Dataset and a Novel Detector of Surface Radiocontamination

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ISBN 13 :
Total Pages : 252 pages
Book Rating : 4.:/5 (951 download)

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Book Synopsis A Dark-matter Search Using the Final CDMS II Dataset and a Novel Detector of Surface Radiocontamination by :

Download or read book A Dark-matter Search Using the Final CDMS II Dataset and a Novel Detector of Surface Radiocontamination written by and published by . This book was released on 2012 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: Substantial evidence from galaxies, galaxy clusters, and cosmological scales suggests that ~85% of the matter of our universe is invisible. The missing matter, or "dark matter" is likely composed of non-relativistic, non-baryonic particles, which have very rare interactions with baryonic matter and with one another. Among dark matter candidates, Weakly Interacting Massive Particles (WIMPs) are particularly well motivated. In the early universe, thermally produced particles with weak-scale mass and interactions would `freeze out' at the correct density to be dark matter today. Extensions to the Standard Model of particle physics, such as Supersymmetry, which solve gauge hierarchy and coupling unification problems, naturally provide such particles. Interactions of WIMPs with baryons are expected to be rare, but might be detectable in low-noise detectors. The Cryogenic Dark Matter Search (CDMS) experiment uses ionization- and phonon- sensitive germanium particle detectors to search for such interactions. CDMS detectors are operated at the Soudan Underground Laboratory in Minnesota, within a shielded environment to lower cosmogenic and radioactive background. The combination of phonon and ionization signatures from the detectors provides excellent residual-background rejection. This dissertation presents improved techniques for phonon calibration of CDMS II detectors and the analysis of the final CDMS II dataset with 612 kg-days of exposure. We set a limit of 3.8x10$^{-}$44 cm$^{2}$ on WIMP-nucleon spin-independent scattering cross section for a WIMP mass of 70 GeV/c$^{2}$. At the time this analysis was published, these data presented the most stringent limits on WIMP scattering for WIMP masses over 42 GeV/c$^{2}$, ruling out previously unexplored parameter space. Next-generation rare-event searches such as SuperCDMS, COUPP, and CLEAN will be limited in sensitivity, unless they achieve stringent control of the surface radioactive contamination on their detectors. Low-penetrating radiation, such as alpha and beta particles, will mimic signal in these experiments. This dissertation also presents the design and prototyping of a novel detector for surface radiocontaminants, called the BetaCage -- a neon-gas time projection chamber built from radiopure materials and operated underground with shielding similar to CDMS II. The BetaCage will enable beta screening of materials at world-best sensitivity of 10$^{-5}$/cm$^{2}$/keV/day, providing a valuable tool to the physics community.

A Search for Low-mass Dark Matter with the Cryogenic Dark Matter Search and the Development of Highly Multiplexed Phonon-mediated Particle Detectors

Download A Search for Low-mass Dark Matter with the Cryogenic Dark Matter Search and the Development of Highly Multiplexed Phonon-mediated Particle Detectors PDF Online Free

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ISBN 13 :
Total Pages : 263 pages
Book Rating : 4.:/5 (951 download)

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Book Synopsis A Search for Low-mass Dark Matter with the Cryogenic Dark Matter Search and the Development of Highly Multiplexed Phonon-mediated Particle Detectors by :

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:

Detector Simulation and WIMP Search Analysis for the Cryogenic Dark Matter Search Experiment

Author : Kevin Ahmad McCarthy
Publisher :
ISBN 13 :
Total Pages : 388 pages
Book Rating : 4.:/5 (865 download)

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Book Synopsis Detector Simulation and WIMP Search Analysis for the Cryogenic Dark Matter Search Experiment by : Kevin Ahmad McCarthy

Download or read book Detector Simulation and WIMP Search Analysis for the Cryogenic Dark Matter Search Experiment written by Kevin Ahmad McCarthy and published by . This book was released on 2013 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astrophysical and cosmological measurements on the scales of galaxies, galaxy clusters, and the universe indicate that ~85% of the matter in the universe is composed of dark matter, made up of non-baryonic particles that interact with cross-sections on the weak scale or lower. Hypothetical Weakly Interacting Massive Particles, or WIMPs, represent a potential solution to the dark matter problem, and naturally arise in certain Standard Model extensions. The Cryogenic Dark Matter Search (CDMS) collaboration aims to detect the scattering of WIMP particles from nuclei in terrestrial detectors. Germanium and silicon particle detectors are deployed in the Soudan Underground Laboratory in Minnesota. These detectors are instrumented with phonon and ionization sensors, which allows for discrimination against electromagnetic backgrounds, which strike the detector at rates orders of magnitude higher than the expected WIMP signal. This dissertation presents the development of numerical models of the physics of the CDMS detectors, implemented in a computational package collectively known as the CDMS Detector Monte Carlo (DMC). After substantial validation of the models against data, the DMC is used to investigate potential backgrounds to the next iteration of the CDMS experiment, known as SuperCDMS. Finally, an investigation of using the DMC in a reverse Monte Carlo analysis of WIMP search data is presented. 140.23 kg-days of WIMP search data from the silicon detectors in the CDMSII experiment is also analyzed. The resulting upper limits on the WIMP-nucleon crosssection are higher than those published by other experiments at all WIMP masses, and the lowest limit on the WIMP-nucleon cross-section is 1.07*10-42 cm2 at a mass of 60 GeV/c2. These results do provide new and interesting constraints at WIMP masses

The Cryogenic Dark Matter Search (CDMS-II) Experiment - First Results from the Soudan Mine

Author : Clarence Leeder Chang
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ISBN 13 :
Total Pages : 137 pages
Book Rating : 4.:/5 (786 download)

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Book Synopsis The Cryogenic Dark Matter Search (CDMS-II) Experiment - First Results from the Soudan Mine by : Clarence Leeder Chang

Download or read book The Cryogenic Dark Matter Search (CDMS-II) Experiment - First Results from the Soudan Mine written by Clarence Leeder Chang and published by . This book was released on 2004 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Detector Simulation and WIMP Search Analysis for the Cryogenic Dark Matter Search Experiment

Author :
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ISBN 13 :
Total Pages : 388 pages
Book Rating : 4.:/5 (953 download)

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Book Synopsis Detector Simulation and WIMP Search Analysis for the Cryogenic Dark Matter Search Experiment by :

Download or read book Detector Simulation and WIMP Search Analysis for the Cryogenic Dark Matter Search Experiment written by and published by . This book was released on 2013 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astrophysical and cosmological measurements on the scales of galaxies, galaxy clusters, and the universe indicate that 85% of the matter in the universe is composed of dark matter, made up of non-baryonic particles that interact with cross-sections on the weak scale or lower. Hypothetical Weakly Interacting Massive Particles, or WIMPs, represent a potential solution to the dark matter problem, and naturally arise in certain Standard Model extensions. The Cryogenic Dark Matter Search (CDMS) collaboration aims to detect the scattering of WIMP particles from nuclei in terrestrial detectors. Germanium and silicon particle detectors are deployed in the Soudan Underground Laboratory in Minnesota. These detectors are instrumented with phonon and ionization sensors, which allows for discrimination against electromagnetic backgrounds, which strike the detector at rates orders of magnitude higher than the expected WIMP signal. This dissertation presents the development of numerical models of the physics of the CDMS detectors, implemented in a computational package collectively known as the CDMS Detector Monte Carlo (DMC). After substantial validation of the models against data, the DMC is used to investigate potential backgrounds to the next iteration of the CDMS experiment, known as SuperCDMS. Finally, an investigation of using the DMC in a reverse Monte Carlo analysis of WIMP search data is presented.

First Results from the Cryogenic Dark Matter Search Experiment at the Deep Site

Author : Vuk Mandic
Publisher :
ISBN 13 :
Total Pages : 922 pages
Book Rating : 4.:/5 (34 download)

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Book Synopsis First Results from the Cryogenic Dark Matter Search Experiment at the Deep Site by : Vuk Mandic

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:

Cryogenic Dark Matter Search (CDMS)

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ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (94 download)

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Book Synopsis Cryogenic Dark Matter Search (CDMS) by :

Download or read book Cryogenic Dark Matter Search (CDMS) written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Deciphering the nature of dark matter has great scientific importance. A leading hypothesis is that dark matter is made of Weakly Interactive Massive Particles (WIMPs), which may result from supersymmetry or additional spatial dimensions. The underground search for elastic scattering of WIMPs on suitable targets (the so-called 'direct detection') is currently led by the Cryogenic Dark Matter Search II (CDMS II) experiment. Its sensitivity is ten times better than any other experiment and we hope to obtain another factor ten in the coming two years. After a brief recall of our recent results, I will describe the complementarity between direct detection experiments, the LHC and the ILC and I will outline the role that SLAC could play in this SuperCDMS program.

A Low-Threshold Analysis of Data from the Cryogenic Dark Matter Search Experiment

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ISBN 13 :
Total Pages : 584 pages
Book Rating : 4.:/5 (957 download)

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Download or read book A Low-Threshold Analysis of Data from the Cryogenic Dark Matter Search Experiment written by and published by . This book was released on 2011 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt: Although dark matter appears to constitute over 80% of the matter in the Universe, its composition is a mystery. Astrophysical observations suggest that the luminous portions of the Galaxy are embedded in a halo of darkmatter particles. Weakly Interacting Massive Particles (WIMPs) are the most studied class of dark-matter candidates and arise naturally within the context of many weak-scale supersymmetric theories. Direct-detection experiments like the Cryogenic Dark Matter Search (CDMS) strive to discern the kinetic energy of recoiling nuclei resulting from WIMP interactions with terrestrial matter. This is a considerable challenge in which the low (expected) rate of WIMP interactions must be distinguished from an overwhelming rate due to known types of radiation. An incontrovertible positive detection has remained elusive. However, a few experiments have recorded data that appear consistent with a low-mass WIMP. This thesis describes an attempt to probe the favored parameter space. To increase sensitivity to low-mass WIMPs, a low-threshold technique with improved sensitivity to small energy depositions is applied to CDMS shallowsite data. Four germanium and two silicon detectors were operated between December 2001 and June 2002, yielding 118 days of exposure. By sacrificing some of the CDMS detectors' ability to discriminate signal from background, energy thresholds of ~1 and ~2 keV were achieved for three of the germanium and both silicon detectors, respectively. A large number of WIMP candidate events are observed, most of which can be accounted for by misidentification of background sources. No conclusive evidence for a low-mass WIMP signal is found. The observed event rates are used to set upper limits on the WIMPnucleon scattering cross section as a function of WIMP mass. Interesting parameter space is excluded for WIMPs with masses below ~9GeV/c2. Under standard assumptions, the parameter space favored by interpretations of other experiments' data as low-mass WIMP signals is partially excluded, and new parameter space is excluded for WIMP masses between 3 and 4GeV/c2.

A Low-threshold Analysis of Data from the Cryogenic Dark Matter Search Experiment

Author : Raymond Adelbert Bunker
Publisher :
ISBN 13 : 9781267193988
Total Pages : 702 pages
Book Rating : 4.1/5 (939 download)

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Book Synopsis A Low-threshold Analysis of Data from the Cryogenic Dark Matter Search Experiment by : Raymond Adelbert Bunker

Download or read book A Low-threshold Analysis of Data from the Cryogenic Dark Matter Search Experiment written by Raymond Adelbert Bunker and published by . This book was released on 2011 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt: Under standard assumptions, the parameter space favored by interpretations of other experiments' data as low-mass WIMP signals is partially excluded, and new parameter space is excluded for WIMP masses between 3 and 4 GeV/c2.

Results from the Two-tower Run of the Cryogenic Dark Matter Search

Author : Angela Jean Reisetter
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ISBN 13 :
Total Pages : 250 pages
Book Rating : 4.:/5 (319 download)

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Book Synopsis Results from the Two-tower Run of the Cryogenic Dark Matter Search by : Angela Jean Reisetter

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:

Low-Mass Dark Matter Search Results and Radiogenic Backgrounds for the Cryogenic Dark Matter Search

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ISBN 13 :
Total Pages : 437 pages
Book Rating : 4.:/5 (982 download)

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Book Synopsis Low-Mass Dark Matter Search Results and Radiogenic Backgrounds for the Cryogenic Dark Matter Search by :

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.

A Search for WIMP Dark Matter Using the First Five-tower Run of the Cryogenic Dark Matter Search

Author : Jeffrey Peter Filippini
Publisher :
ISBN 13 :
Total Pages : 782 pages
Book Rating : 4.:/5 (754 download)

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Book Synopsis A Search for WIMP Dark Matter Using the First Five-tower Run of the Cryogenic Dark Matter Search by : Jeffrey Peter Filippini

Download or read book A Search for WIMP Dark Matter Using the First Five-tower Run of the Cryogenic Dark Matter Search written by Jeffrey Peter Filippini and published by . This book was released on 2008 with total page 782 pages. Available in PDF, EPUB and Kindle. Book excerpt:

A Search for Particle Dark Matter Using Cryogenic Germanium and Silicon Detectors in the One- and Two- Tower Runs of CDMS-II at Soudan

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ISBN 13 :
Total Pages : 333 pages
Book Rating : 4.:/5 (727 download)

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Book Synopsis A Search for Particle Dark Matter Using Cryogenic Germanium and Silicon Detectors in the One- and Two- Tower Runs of CDMS-II at Soudan by :

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.