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Searches for New Physics at the Tevatron and LHC

Description: This is an auspicious moment in experimental particle physics - there are large data samples at the Tevatron and a new energy regime being explored at the Large Hadron Collider with ever larger data samples. The coincidence of these two events suggests that we will soon be able to address the question, what lies beyond the standard model? Particle physics's current understanding of the universe is embodied in it. The model has been tested to extreme precision - better than a part in ten thousand - but we suspect that it is only an approximation, and that physics beyond this standard model will appear in the data of the Tevatron and LHC in the near future. This brief review touches on the status of searches for new physics at the time of the conference.
Date: November 1, 2011
Creator: Wittich, Peter & /Cornell U., LEPP
Partner: UNT Libraries Government Documents Department

Charting the Course for Elementary Particle Physics

Description: ''It was the best of times; it was the worst of times'' is the way Dickens begins the Tale of Two Cities. The line is appropriate to our time in particle physics. It is the best of times because we are in the midst of a revolution in understanding, the third to occur during my career. It is the worst of times because accelerator facilities are shutting down before new ones are opening, restricting the opportunity for experiments, and because of great uncertainty about future funding. My task today is to give you a view of the most important opportunities for our field under a scenario that is constrained by a tight budget. It is a time when we cannot afford the merely good, but must give first priority to the really important. The defining theme of particle physics is to learn what the universe is made of and how it all works. This definition spans the full range of size from the largest things to the smallest things. This particle physics revolution has its origins in experiments that look at both.
Date: February 20, 2007
Creator: Richter, Burton
Partner: UNT Libraries Government Documents Department

A Search for B+ ---> tau+ neutrino(tau) recoiling against B- ---> D0 l- anti-nu(l) X

Description: The fundamental pursuit of physics has always been a deeper understanding of nature's workings. In the last fifty years this pursuit has culminated in a view of the universe as a complex tapestry woven from only a few fundamental particles and interactions. This description of the universe, the Standard Model of Particle Physics, has been highly successful at predicting the behavior of these particles and interactions. However, the model leaves many questions unanswered and the hope is that many precise tests of its predictions will yield inconsistencies, windows into new physical principles. The search for processes that are allowed by the Standard Model but inherently rare provides fruitful ground for such a test. The large sample of B mesons available from the PEP-II/BABAR B-factory furnishes an opportunity to test Standard Model predictions via rare B meson decay modes.
Date: May 6, 2005
Creator: Sekula, Stephen Jacob
Partner: UNT Libraries Government Documents Department

The BigBOSS Experiment

Description: BigBOSS will obtain observational constraints that will bear on three of the four 'science frontier' questions identified by the Astro2010 Cosmology and Fundamental Phyics Panel of the Decadal Survey: Why is the universe accelerating; what is dark matter and what are the properties of neutrinos? Indeed, the BigBOSS project was recommended for substantial immediate R and D support the PASAG report. The second highest ground-based priority from the Astro2010 Decadal Survey was the creation of a funding line within the NSF to support a 'Mid-Scale Innovations' program, and it used BigBOSS as a 'compelling' example for support. This choice was the result of the Decadal Survey's Program Priorization panels reviewing 29 mid-scale projects and recommending BigBOSS 'very highly'.
Date: January 1, 2011
Creator: Schelgel, D.; Abdalla, F.; Abraham, T.; Ahn, C.; Allende Prieto, C.; Annis, J. et al.
Partner: UNT Libraries Government Documents Department

Searches for new physics at the Tevatron

Description: The Tevatron collider has provided the CDF and D0 experiences with large datasets as input to a rich program of searches for physics beyond the standard model. The results presented here are a partial survey of recent searches conducted by the two collaborations using up to 6 fb{sup -1} of data. The standard model (SM) of particles, despite its remarkable description of experimental data at the elementary particle level, has some deficiencies to explain what is observed in the universe: lack of anti-matter, existence of dark matter, etc. Working at the energy frontier, as was the case at the Tevatron for so many years, gives experimentalists the hope to discover new non-SM particles which would indicate some direction to follow at explaining these SM deficiencies. Over the years, the CDF and D0 experiments have gained experience in the detector responses to all particle types. It allows to look at a large number of different final states searching for deviations from the SM expectations. As the knowledge of detector particle responses becomes more accurate, the complexity of final states can increase. For a given final state signature, the non-observation of deviations from the SM prediction allows to constrain several models at once.
Date: May 1, 2011
Creator: Jaffre, Michel
Partner: UNT Libraries Government Documents Department

Direct CP Violation in Charmless Hadronic B-Meson Decays at the PEP-II Asymmetric B-Meson Factory

Description: The study of the quark transition b {yields} s{bar s}s, which is a pure loop-level (''penguin'') process leading to several B-meson-decay final states, most notably {phi}K, is arguably the hottest topic in B-meson physics today. The reason is the sensitivity of the amplitudes and the CP-violating asymmetries in such processes to physics beyond the Standard Model. By performing these measurements, we improve our understanding of the phenomenon of combined-parity (CP) violation, which is believed to be responsible for the dominance of matter over antimatter in our Universe. Here, we present measurements of branching fractions and charge asymmetries in the decays B{sup +} {yields} {phi}K{sup +} and B{sup 0} {yields} {phi}K{sup 0} in a sample of approximately 89 million B{bar B} pairs collected by the BABAR detector at the PEP-II asymmetric-energy B-meson Factory at SLAC. We determine {Beta}(B{sup +} {yields} {phi}K{sup +}) = (10.0{sub -0.8}{sup +0.9} {+-} 0.5) x 10{sup -6} and {Beta}(B{sup 0} {yields} {phi}K{sup 0}) = (8.4{sub -1.3}{sup +1.5} {+-} 0.5) x 10{sup -6}, where the first error is statistical and the second is systematic. Additionally, we measure the CP-violating charge asymmetry {Alpha}{sub CP}(B{sup {+-}} {yields} {phi}K{sup {+-}}) = 0.04 {+-} 0.09 {+-} 0.01, with a 90% confidence-level interval of [-0.10, 0.18], and set an upper limit on the CKM- and color-suppressed decay B{sup +} {yields} {phi}{pi}{sup +}, {Beta}(B{sup +} {yields} {phi}{pi}{sup +}) < 0.41 x 10{sup -6} (at the 90% confidence level). Our results are consistent with the Standard Model, which predicts {Alpha}{sub CP}(B{sup {+-}} {yields} {phi}K{sup {+-}}) {approx}< 1% and {Beta}(B {yields} {phi}{tau}) << 10{sup -7}. Since many models of physics beyond the Standard Model introduce additional loop diagrams with new heavy particles and new CP-violating phases that would contribute to these decays, potentially making {Alpha}{sub CP} (B{sup {+-}} {yields} {phi}K{sup {+-}}) and {Beta}(B {yields} {phi}{pi}) quite ...
Date: May 6, 2005
Creator: Telnov, Alexandre Valerievich & /UC, Berkeley
Partner: UNT Libraries Government Documents Department

A Monte Carlo Study of the Momentum Dependence on the Results of Tracking Unknown Particle Species in the BaBar Detector

Description: The BABAR experiment is composed of an international collaboration that will test the Standard Model prediction of CP violation. To accomplish this a new detector was constructed at the asymmetric B Factory, located at the Stanford Linear Accelerator Center. The tests will shed some light on the origins of CP violation, which is an important aspect in explaining the matter/antimatter asymmetry in the universe. In particular, the BABAR experiment will measure CP violation in the neutral B meson system. In order to succeed, the BABAR experiment requires excellent track fitting and particle species identification. Prior to the current study, track fitting was done using only one particle species--the pion. But given the momentum dependence on the accuracy of the results from this choice of particle species, a better algorithm needed to be developed. Monte Carlo simulations were carried out and a new algorithm utilizing all five particle species present in the BABAR detector was created.
Date: April 6, 2007
Creator: Sewerynek, Stephen & U., /British Columbia
Partner: UNT Libraries Government Documents Department

Study of Rare Radiative B Decay to K*(1430) Meson Using the BABAR Detector

Description: Radiative B Meson decay through the b {yields} s{gamma} process has been one of the most sensitive probe of new physics beyond the Standard Model, because of its importance in understanding the phenomenon of CP violation, which is believed to be necessary to explain the excess of matter over anti-matter in our universe. The inclusive picture of the b {yields} s{gamma} process is well established; however, our knowledge of the exclusive final states in radiative B meson decays is rather limited. We have investigated one of them, the exclusive, radiative B decay to the charmless K*{sub 2}(1430) meson, in a sample of 88.5 x 10{sup 6} B{bar B} events with the BABAR detector at the PEP-II storage ring. We present a measurement of the branching fractions {Beta}(B{sup 0} {yields} K*{sub 2}(1430){sup 0}{gamma}) = (1.22 {+-} 0.25 {+-} 0.10) x 10{sup -5} and {Beta}(B{sup +} {yields} K*{sub 2}(1430){sup +}){gamma} = (1.45 {+-} 0.40 {+-} 0.15) x 10{sup -5}, where the first error is statistical and the second systematic. In addition, we have performed the first search for direct CP violation in this decay with the measured asymmetry in B{sup 0} {yields} K*{sub 2}(1430){sup 0}{gamma} of {Alpha}{sub CP} = -0.08 {+-} 0.15 {+-} 0.01.
Date: September 14, 2005
Creator: Guo, Qinghua & U., /Pennsylvania
Partner: UNT Libraries Government Documents Department

Study of CP violation in Bx to J/psi phi decays at DZero

Description: In a universe dominated by matter, the source of CP violation may explain one of the greatest mysteries in particle physics: what happened to the antimatter? The Standard Model successfully describes CP violation in the B{sup +} and B{sub d}{sup 0} systems, yet insufficiently accounts for the observed matter-antimatter asymmetry. The Standard Model predicts a small value of CP violation in the B{sub s}{sup 0} meson system, which has only recently been experimentally tested. A measurement of large, anomalous CP violation in the B{sub s}{sup 0} system would be a clear indication of new physics sources beyond the Standard Model. This dissertation describes a study of CP violation in approximately 2000 B{sub s}{sup 0} {yields} J/{psi}{phi} decays reconstructed in a 2.8 fb{sup -1} data sample collected by the D0 Run II detector at Fermi National Accelerator Laboratory in Batavia, Illinois. This data was provided by p{bar p} collisions at {radical}s = 1.96 TeV delivered by the Tevatron accelerator between April 2002 and August 2007. Flavor-tagged B{sub s}{sup 0} {yields} J/{psi}({mu}{sup +}{mu}{sup -}){phi}(K{sup +}K{sup -}) decays and an angular analysis are used to study the time evolution of the final state angular distributions. From this analysis, we measure the width difference between the heavy and light mass eigenstates, B{sub s}{sup L} and B{sub s}{sup H}, to be {Delta}{Lambda}{sub s} = 0.19 {+-} 0.07 and the CP-violating phase {phi}{sub s} = -0.57{sub -0.30}{sup +0.24}.
Date: December 1, 2008
Creator: Strom, Derek A.
Partner: UNT Libraries Government Documents Department

Challenging the standard model at the Tevatron collider

Description: Even at a time where the world's eyes are focused on the Large Hadron Collider at CERN, which has reached the energy frontier in 2010, many important results are still being obtained from data analyses performed at the Tevatron collider at Fermilab. This contribution discusses recent highlights in the areas of B hadron, electroweak, top quark, and Higgs boson physics. The standard model (SM) of particle physics forms the cornerstone of our understanding of elementary particles and their interactions, and many of its aspects have been investigated in great detail. Yet it is generally suspected to be incomplete (e.g. by not allowing for the incorporation of gravity in a field theoretical setting) and un-natural (e.g. the mass of the Higgs boson is not well protected against radiative corrections). In addition, it does not explain the dark matter and dark energy content of the Universe. It is therefore of eminent importance to test the limits of validity of the SM. In the decade since its upgrade to a centre-of-mass energy {radical}s = 1.96 TeV, the Tevatron p{bar p} collider has delivered an integrated luminosity of about 10 fb{sup -1}, up to 9 fb{sup -1} of which are available for analysis by its CDF and D0 collaborations. These large datasets allow for stringent tests of the SM in two areas: direct searches for particles or final states that are not very heavy but that suffer from small production cross sections (e.g. the Higgs boson), and searches for indirect manifestations of beyond-the-standard-model (BSM) effects through virtual effects. The latter searches can often be carried out by precise measurements of otherwise known processes. This contribution describes such tests of the SM carried out by the CDF and D0 collaborations. In particular, recent highlights in the areas of B hadron physics, electroweak physics, top quark ...
Date: March 1, 2011
Creator: Filthaut, Frank & U., /Nijmegen
Partner: UNT Libraries Government Documents Department

Search for New Physics at the Tevatron

Description: We report on selected recent results from the CDF and D0 experiments on searches for physics beyond the Standard Model using data from the Tevatron collider running p{bar p} collisions at {radical}s = 1960 GeV. Over the past decades the Standard Model (SM) of particle physics has been surprisingly successful. Although the precision of experimental tests improved by orders of magnitude no significant deviation from the SM predictions has been observed so far. Still, there are many questions that the Standard Model does not answer and problems it can not solve. Among the most important ones are the origin of the electro-weak symmetry breaking, hierarchy of scales, unification of fundamental forces and the nature of gravity. Recent cosmological observations indicates that the SM particles only account for 4% of the matter of the Universe. Many extensions of the SM (Beyond the Standard Model, BSM) have been proposed to make the theory more complete and solve some of the above puzzles. Some of these extension includes SuperSymmetry (SUSY), Grand Unification Theory (GUT) and Extra Dimensions. At CDF and D0 we search for evidence of such processes in proton-antiproton collisions at {radical}(s) = 1960 GeV. The phenomenology of these models is very rich, although the cross sections for most of these exotic processes is often very small compared to those of SM processes at hadron colliders. It is then necessary to devise analysis strategies that would allow to disentangle the small interesting signals, often buried under heavy instrumental and/or physics background. Two main approaches to search for physics beyond the Standard Model are used in a complementary fashion: model-based analyses and signature based studies. In the more traditional model-driven approach, one picks a favorite theoretical model and/or a process, and the best signature is chosen. The selection cuts are optimized based on ...
Date: May 1, 2011
Creator: Rolli, Simona
Partner: UNT Libraries Government Documents Department

Analysis of the charmed semileptonic decay D+ ---> rho0 mu+ nu

Description: The search for the fundamental constituents of matter has been pursued and studied since the dawn of civilization. As early as the fourth century BCE, Democritus, expanding the teachings of Leucippus, proposed small, indivisible entities called atoms, interacting with each other to form the Universe. Democritus was convinced of this by observing the environment around him. He observed, for example, how a collection of tiny grains of sand can make out smooth beaches. Today, following the lead set by Democritus more than 2500 years ago, at the heart of particle physics is the hypothesis that everything we can observe in the Universe is made of a small number of fundamental particles interacting with each other. In contrast to Democritus, for the last hundred years we have been able to perform experiments that probe deeper and deeper into matter in the search for the fundamental particles of nature. Today's knowledge is encapsulated in the Standard Model of particle physics, a model describing the fundamental particles and their interactions. It is within this model that the work in this thesis is presented. This work attempts to add to the understanding of the Standard Model by measuring the relative branching fraction of the charmed semileptonic decay D{sup +} {yields} {rho}{sup 0}{mu}{sup +}{nu} with respect to D{sup +} {yields} {bar K}*{sup 0} {mu}{sup +}{nu}. Many theoretical models that describe hadronic interactions predict the value of this relative branching fraction, but only a handful of experiments have been able to measure it with any precision. By making a precise measurement of this relative branching fraction theorists can distinguish between viable models as well as refine existing ones. In this thesis we presented the measurement of the branching fraction ratio of the Cabibbo suppressed semileptonic decay mode D{sup +} {yields} {rho}{sup 0}{mu}{sup +}{nu} with respect to ...
Date: December 1, 2008
Creator: Luiggi, Eduardo E. & U., /Vanderbilt
Partner: UNT Libraries Government Documents Department

Properties of the Top Quark

Description: The aim of particle physics is the understanding of elementary particles and their interactions. The current theory of elementary particle physics, the Standard Model, contains twelve different types of fermions which (neglecting gravity) interact through the gauge bosons of three forces. In addition a scalar particle, the Higgs boson, is needed for theoretical consistency. These few building blocks explain all experimental results found in the context of particle physics, so far. Nevertheless, it is believed that the Standard Model is only an approximation to a more complete theory. First of all the fourth known force, gravity, has withstood all attempts to be included until now. Furthermore, the Standard Model describes several features of the elementary particles like the existence of three families of fermions or the quantisation of charges, but does not explain these properties from underlying principles. Finally, the lightness of the Higgs boson needed to explain the symmetry breaking is difficult to maintain in the presence of expected corrections from gravity at high scales. This is the so called hierarchy problem. In addition astrophysical results indicate that the universe consists only to a very small fraction of matter described by the Standard Model. Large fractions of dark energy and dark matter are needed to describe the observations. Both do not have any correspondence in the Standard Model. Also the very small asymmetry between matter and anti-matter that results in the observed universe built of matter (and not of anti-matter) cannot be explained until now. It is thus an important task of experimental particle physics to test the predictions of the Standard Model to the best possible accuracy and to search for deviations pointing to necessary extensions or modifications of our current theoretical understanding. The top quark was predicted to exist by the Standard Model as the partner of ...
Date: August 1, 2009
Creator: Wicke, Daniel
Partner: UNT Libraries Government Documents Department

The Higgs boson in the Standard Model theoretical constraints and a direct search in the wh channel at the Tevatron

Description: We have presented results in two different yet strongly linked aspects of Higgs boson physics. We have learned about the importance of the Higgs boson for the fate of the Standard Model, being either only a theory limited to explaining phenomena at the electroweak scale or, if the Higgs boson lies within a mass range of 130 &lt; m<sub>H</sub> &lt; 160 GeV the SM would remain a self consistent theory up to highest energy scales O(m<sub>Pl</sub>). This could have direct implications on theories of cosmological inflation using the Higgs boson as the particle giving rise to inflation in the very early Universe, if it couples non-minimally to gravity, an effect that would only become significant at very high energies. After understanding the immense meaning of proving whether the Higgs boson exists and if so, at which mass, we have presented a direct search for a Higgs boson in associated production with a W boson in a mass range 100 &lt; m<sub>H</sub> &lt; 150 GeV. A light Higgs boson is favored regarding constraints from electroweak precision measurements. As a single analysis is not yet sensitive for an observation of the Higgs boson using 5.3 fb<sup>-1</sup> of Tevatron data, we set limits on the production cross section times branching ratio. At the Tevatron, however, we are able to combine the sensitivity of our analyses not only across channels or analyses at a single experiment but also across both experiments, namely CDF and D0. This yields to the so-called Tevatron Higgs combination which, in total, combines 129 analyses from both experiments with luminosities of up to 6.7 fb<sup>-1</sup>. The results of a previous Tevatron combination led to the first exclusion of possible Higgs boson masses since the LEP exclusion in 2001. The latest Tevatron combination from July 2010 can be seen in Fig. ...
Date: September 10, 2010
Creator: Huske, Nils Kristian & (Germany)], Bielefeld Univ.
Partner: UNT Libraries Government Documents Department

A search for the Standard Model Higgs boson in the process ZH → ℓ<sup>+</sup>ℓ<sup>-</sup>b$\bar{b}$ in 4.1 fb<sup>-1</sup> of CDF II data

Description: The standard model of particle physics provides a detailed description of a universe in which all matter is composed of a small number of fundamental particles, which interact through the exchange of force - carrying gauge bosons (the photon, W <sup>±</sup>, Z and gluons). The organization of the matter and energy in this universe is determined by the effects of three forces; the strong, weak, and electromagnetic. The weak and electromagnetic forces are the low energy manifestations of a single electro-weak force, while the strong force binds quarks into protons and neutrons. The standard model does not include gravity, as the effect of this force on fundamental particles is negligible. Four decades of experimental tests, spanning energies from a few electron-volts (eV) up to nearly two TeV, confirm that the universe described by the standard model is a reasonable approximation of our world. For example, experiments have confirmed the existence of the top quark, the W<sup>±</sup> and the Z bosons, as predicted by the standard model. The latest experimental averages for the masses of the top quark, W<sup>±</sup> and Z are respectively 173.1 ± 0.6(stat.) ± 1.1(syst.), 80.399 ± 0.023 and 91.1876 ± 0.0021 GeV/c<sup>2</sup>. The SM is a gauge field theory of zero mass particles. However, the SM is able to accommodate particles with non-zero mass through the introduction of a theoretical Higgs field which permeates all of space. Fermions gain mass through interactions with this field, while the longitudinal components of the massive W<sup>±</sup> and Z are the physical manifestations of the field itself. Introduction of the Higgs field, directly leads to the predicted existence of an additional particle, the Higgs boson. The Higgs boson is the only particle of the standard model that has not been observed, and is the only unconfirmed prediction of the theory. The ...
Date: May 1, 2010
Creator: Shalhout, Shalhout Zaki
Partner: UNT Libraries Government Documents Department

The Dark Energy Survey Camera (DECam)

Description: The Dark Energy Survey (DES) is a next generation optical survey aimed at understanding the expansion rate of the Universe using four complementary methods: weak gravitational lensing, galaxy cluster counts, baryon acoustic oscillations, and Type Ia supernovae. To perform the survey, the DES Collaboration is building the Dark Energy Camera (DECam), a 3 square degree, 570 Megapixel CCD camera that will be mounted at the prime focus of the Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory. CCD production has finished, yielding roughly twice the required 62 2k x 4k detectors. The construction of DECam is nearly finished. Integration and commissioning on a 'telescope simulator' of the major hardware and software components, except for the optics, recently concluded at Fermilab. Final assembly of the optical corrector has started at University College, London. Some components have already been received at CTIO. 'First-light' will be sometime in 2012. This oral presentation concentrates on the technical challenges involved in building DECam (and how we overcame them), and the present status of the instrument.
Date: September 9, 2011
Creator: Diehl, H.Thomas
Partner: UNT Libraries Government Documents Department

Measurement of CP-Violating Asymmetries In Neutral B Meson Decays Into Three Kaons

Description: The Standard Model (SM) of particle physics successfully describes all of the observed interactions of the fundamental particles (with the exception of non-zero neutrino mass). Despite this enormous success, the SM is widely viewed as an incomplete theory. For example, the size of the asymmetry between matter and antimatter is not nearly large enough to account for the abundance of matter observed throughout the universe. It is thus believed that as-yet-unknown physical phenomena must exist that introduce new asymmetries between matter and antimatter. In this thesis, by studying decays that happen only rarely in the SM, we make measurements of asymmetries between matter and antimatter that are potentially sensitive to the existence of processes beyond the SM. At the PEP-II asymmetric-energy B Factory at SLAC, electrons and positrons are collided at the {Upsilon}(4S) resonance to create pairs of B mesons. The BABAR detector is used to measure the subsequent decay products. Using 383 million {Upsilon}(4S) {yields} B{bar B} decays, we study the decay B{sup 0} {yields} K{sup +}K{sup -}K{sup 0}. In the SM, this decay is dominated by loop amplitudes. Asymmetries between matter and antimatter (CP asymmetries) are extracted by measuring the time-dependence of the complex amplitudes describing the B{sup 0} and {bar B}{sup 0} decays as functions of their kinematics. The interference between decays with and without the mixing of neutral B mesons allows for the measurement of the angle {beta}{sub eff}, which is a measure of CP violation. We also measure the direct CP asymmetry A{sub CP}. Data samples reconstructed from three K{sup 0} modes (K{sub S}{sup 0} {yields} {pi}{sup +}{pi}{sup -}, K{sub S}{sup 0} {yields} {pi}{sup 0}{pi}{sup 0}, and K{sub L}{sup 0}) are fit simultaneously. They find A{sub CP} = -0.015 {+-} 0.077 {+-} 0.053 and {beta}{sub eff} = 0.352 {+-} 0.076 {+-} 0.026 rad, corresponding to ...
Date: December 1, 2008
Creator: Thompson, Joshua M.
Partner: UNT Libraries Government Documents Department

A search for particle dark matter using cryogenic germanium and silicon detectors in the one- and two- tower runs of CDMS-II at Soudan

Description: 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 ...
Date: April 1, 2008
Creator: Ogburn, Reuben Walter, IV
Partner: UNT Libraries Government Documents Department