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 …

The Cryogenic Dark Matter Search (CDMS) uses position-sensitive Germanium and Silicon crystals in the direct detection of Weakly Interacting Massive Particles (WIMPs) believed to constitute most of the dark matter in the Universe. WIMP interactions with matter being rare, identifying and eliminating known backgrounds is critical for detection. Event-by-event discrimination by the detectors rejects the predominant gamma and beta backgrounds while Monte Carlo simulations help estimate, and subtract, the contribution from the neutrons. This thesis describes the effort to understand neutron backgrounds as seen in the two stages of the CDMS search for WIMPs. The first stage of the experiment was at a shallow site at the Stanford Underground Facility where the limiting background came from high-energy neutrons produced by cosmic-ray muon interactions in the rock surrounding the cavern. Simulations of this background helped inform the analysis of data from an experimental run at this site and served as input for the background reduction techniques necessary to set new exclusion limits on the WIMP-nucleon cross-section, excluding new parameter space for WIMPs of masses 8-20 GeV/c{sup 2}. This thesis considers the simulation methods used as well as how various event populations in the data served as checks on the simulations to …

Fermilab Experiment 866 took single muon data from 800 GeV/c ({radical}s = 38.8 GeV) p-Cu and p-Be interactions in an attempt to extract the inclusive nuclear open charm/anti-charm (D/{bar D}) differential cross sections as a function of p{sub T}. The muons were decay products from semi-leptonic decays of open charm mesons as well as decays from lighter non-charmed mesons ({pi}'s and K's). Data were taken simultaneously from two interaction regions; one of two thin nuclear targets and a copper beam dump 92 inches downstream. The open decay length for hadrons produced in the targets increased the contribution to the muon spectrum from light hadron decays, relative to those from the dump. Production cross sections for light hadrons from previous experiments were used in conjunction with parameterized open charm cross sections to produce total Monte Carlo single muon spectra that were subsequently fit to the data. The sensitivity of this measurement covered an open charm hadron p{sub T} range of approximately 2 to 7 GeV/c, center-of-mass rapidity, y{sub cm}, between 0 and 2, and x{sub F} between 0.2 and 0.8. Previous experimental results for p-p or p-A open charm production at comparable energy was limited to {radical}5 GeV/ Three functions describing …

In this dissertation, we measure the properties of the lowest-mass beauty baryon, {Lambda}{sub b}. Baryons are the bound states of three quarks. Protons and neutrons, constituents of atomic nuclei, are the most common baryons. Other types of baryons can be produced and studied in the high-energy collider environment. Three-body dynamics makes baryons composed of low mass quarks difficult to study. On the other hand, baryons with one heavy quark simplify the theoretical treatment of baryon structure, since the heavy quark can be treated the same way as the nucleus in the atom. The {Lambda}{sub b} is composed of u, d, and b quarks, where the b quark is much heavier than the other two. Although, it is accessible, little is known about {Lambda}{sub b}. In 1991, UA1 [1] reconstructed 9 {+-} 1 {Lambda}{sub b} {yields} J/{Psi}{Lambda} candidates. In 1996, ALEPH and DELPHI reconstructed the decay {Lambda}{sub b} {yields} {Lambda}{sub c}{sup +}{pi}{sup -} and found only 3-4 candidates [2, 3]. ALEPH measured a {Lambda}{sub b} mass of 5614 {+-} 21 MeV/c{sup 2}, while DELPHI measured 5668 {+-} 18 MeV/c{sup 2}, about 2 {sigma} higher. Subsequently, CDF-I observed 20 {Lambda}{sub b} {yields} J/{Psi}{Lambda} events [4], confirmed the existence of {Lambda}{sub b} unambiguously …

The Fermilab experiment E872 (DONUT) was designed to make the first observation of the tau neutrino charged-current interaction. Using a hybrid emulsion-spectrometer detector, the tau lepton was identified by its single-prong or trident decay. Six interactions were observed, of which five were in the deep inelastic scattering region. These five interaction were used to measure the charged-current cross section of the tau neutrino. To minimize uncertainties, the tau neutrino cross section was measured relative to the electron neutrino cross section. The result {sigma}{sub {nu}{sub {tau}}N}{sup const}/{sigma}{sub {nu}{sub e}N}{sup const} = 0.77 {+-} 0.39 is consistent with 1.0, which is predicted by lepton universality. The tau neutrino cross section was also measured for 115 GeV neutrinos, which was the average energy of the interacted tau neutrinos. The result {sigma}{sub {nu}{sub {tau}}N}{sup exp} = 45 {+-} 21 x 10{sup -38} cm{sup 2} is consistent with the standard model prediction calculated in this thesis, {sigma}{sub {tau}N}{sup SM} = 48 {+-} 5 x 10{sup -38} cm{sup 2}.

This dissertation describes a measurement of the mass of the top quark using events consistent with the hypothesis t{bar t} {yields} bW{sup +} {bar b}W{sup -} {yields} bl{sup +}{nu}{bar b}l{sup -}{bar {nu}}, where (l=e,{mu}). The events are obtained from nearly 230 pb{sup -1} of p{bar p} collision data collected by the D0 experiment between 2002 and 2004 during Run II. In this decay channel two neutrinos remain undetected. Extraction of the mass of the top quark by kinematic reconstruction is not possible because the event is under-constrained. Therefore, a dynamical likelihood method is developed to obtain the mass of the top quark. The mass of top quark obtained from the candidate events selected in the di-electron channel and the e{mu} channel is: 154.1 {sup +14.2}{sub -12.8}(stat.) {+-}6.6 (syst.) GeV.

This dissertation presents measurements of the inclusive production cross sections for W and Z gauge bosons decaying through the electron channel with p{bar p} collisions at a center-of-mass energy of 1.96 TeV. The ratio of these cross sections is then used to extract the W total width. The Standard Model (SM) of electroweak and strong interactions is a collection of theories which together encompass what is currently known about the elementary particles that make up matter and the forces through which they interact. Experimentalists are constantly searching for violations of the Standard Model by making precision measurements of predicted interactions. The decay of the W boson is one such interaction. The rate of its decay is reflected in its width which is predicted to high precision using Standard Model-based calculations. Therefore, a high precision experimental width measurement would be very sensitive to any such violation. In principle the W and Z boson production cross sections could also be good Standard Model tests. However, a precise knowledge of integrated luminosity is required which is unfortunately difficult to obtain at the Tevatron. In fact, the W and Z cross section results can be used to obtain a more precise luminosity measurement. The …

High-precision measurements are made of Z boson production in proton-antiproton collisions at {radical}s = 1.96 TeV recorded by the Collider Detector at Fermilab, using the electron decay channel. The cross-section times branching ratio is measured to be {sigma}{sub Z} {center_dot} Br(Z {yields} e{sup +}e{sup -}) = (255.7 {+-} 2.4{sub stat} {+-} 5.2{sub sys} {+-} 15.2{sub lum})pb in a dataset of 194 pb{sup -1} collected between March 2002 and June 2003. This agrees well with theoretical predictions. The cross-section for W boson production in the electron channel has also been measured in the subset of this dataset of 72 pb{sup -1} collected up until January 2003. Using this smaller dataset the ratio of cross-sections is determined to be R {equivalent_to} {sigma}{sub W} {center_dot} Br(W {yields} e{nu})/{sigma}{sub Z} {center_dot} Br(Z {yields} ee) = 10.82 {+-} 0.18{sub stat} {+-} 0.16{sub sys}. Combining these results with measurements made in the muon channel gives R = 10.92 {+-} 0.15{sub stat} {+-} 0.14{sub sys} (e + {mu} channels), from which the branching ratio of the W to electrons and muons, and the total width of the W, have been extracted: Br(W {yields} {ell}{nu}) = 0.1089 {+-} 0.0022 ({ell} = e,{mu}); {Lambda}(W) = 2078.8 {+-} 41.4 MeV, …

Two alternative measurements of the t{bar t} production cross section at {radical}s = 1.96 TeV in proton-antiproton collisions in the lepton+jets channel are presented. The t{bar t} production cross section is extracted by combining the kinematic event information in a multivariate discriminant. The measurement yields {sigma}{sub p{bar p} {yields} t{bar t} + x} = 5.13{sub -1.57}{sup +1.76}(stat){sub -1.10}{sup +0.96}(syst) {+-} 0.33 (lumi) pb in the muon+jets channel, using 229.1 pb{sup -1}, and in the combination with the electron+jets channel 226.3 pb{sup -1} {sigma}{sub p{bar p} {yields} t{bar t} + x} = 6.60{sub -1.28}{sup +1.37}(stat){sub -1.11}{sup +1.25}(syst) {+-} 0.43 (lumi) pb. The second measurement presented reconstructs explicitly secondary vertices to d lifetime b-tagging. The measurement combines the muon+jets and the electron+jets channel, using 158.4 pb{sup -1} and 168.8 pb{sup -1}, respectively: {sigma}{sub p{bar p} {yields} t{bar t} + x} = 8.24{sub -1.25}{sup +1.34}(stat){sub -1.63}{sup +1.89}(syst) {+-} 0.54 (lumi) pb.

The large sample of {Xi}{sup 0} hyperons available at KTeV 799 provides an opportunity to search for the Weak Radiative Hyperon Decay {Xi}{sup 0} {yields} {Lambda}{sup 0}{pi}{sup 0}{gamma}. They present a branching fraction measurement of {Xi}{sup 0} {yields} {Lambda}{sup 0}{pi}{sup 0}{gamma} based on the E799-II experiment data-taking in 1999 at KTeV, Fermilab. They used the principal decay of {Xi}{sup 0} {yields} {Lambda}{sup 0}{pi}{sup 0} where {Lambda} decays to a proton and a {pi}{sup -} as the flux normalization mode. This is the first observation of this interesting decay mode. 4 candidate events are found in the data. The branching ratio at 90% confidence level has been measured to be (1.67{sub -0.80}{sup +1.45}(stat.) {+-} 0.50(syst.)) x 10{sup -5} or (1.67{sub -0.69}{sup +1.16}(stat.) {+-} 0.50(syst.)) x 10{sup -5} at 68.27% confidence level.

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This thesis describes the first search for electroweak single top quark production in proton-antiproton collisions at a center of mass energy of 1.96 TeV. The data sample used for this analysis corresponds to 162 pb{sup -1} recorded by the upgraded Collider Detector at Fermilab. The search is performed by doing a classic maximum likelihood fit to the H{sub T} distribution in data. The kinematic variable H{sub T} is the scalar sum of transverse energies of all final state particles in the event. This variable has the advantage that its distribution looks very similar for both contributing (s-channel and t-channel) single top processes, but is different for background processes. The combination of both channels to one signal improves the sensitivity of the search. No significant evidence for electroweak single top quark production is found and we set an upper limit at the 95% confidence level on the combined single top quark production cross section of 17.8 pb.

The authors present a study of the p{bar p} {yields} W(Z){gamma} {yields} {gamma}q{bar q} process at the center-of-mass energy {radical}s = 1.96 TeV using data collected by the Collider Detector at Fermilab. The analysis is based on the selection of low transverse momentum photons produced in association with at least two jets. A modification of an existing photon trigger was studied and implemented in the data acquisition system to enhance the sensitivity of this analysis. The data presented are from approximately 184 pb{sup -1} of integrated luminosity collected by this new trigger. A preliminary event sample is obtained requiring a central photon with E{sub T} > 12 GeV and two jets with E{sub T} > 15 GeV. The corresponding efficiency is studied using a Monte Carlo simulation of the W(Z){gamma} {yields} {gamma}q{bar q} based on Standard Model predictions. Monte Carlo estimation of the background is not necessary as it is measured from the data. A more advanced selection based on a Neural Network method improves the signal-to-noise ratio from 1/333 to 1/71, and further optimization of the dijet mass search region increases the ratio to its final value of 1/41. No evidence of a W/Z {yields} q{bar q} peak in …

We used the upgraded D0 detector at the Tevatron at {radical}s = 1.96 TeV to collect data in a search for a compositeness signature of quarks and leptons. This analysis uses an integrated luminosity of 400 pb{sup -1}. The high-mass dimuon mass spectrum is compared with that predicted by Drell-Yan (DY) scattering, modified by a contact interaction. This interaction is parameterized by a compositeness energy scale factor {Lambda}. Preliminary limits on {lambda} are set at the 95% confidence level for constructive and destructive interference between the DY amplitude and the contact interaction for various quark and lepton chiralities.

A search for the pair production of supersymmetric partner of the top quark in scenario with R-parity violation is presented. The quantum number called R-parity distinguishes particles in standard model from supersymmetric particles. A scalar top quark (stop) is assumed to decay only via R{sub p}-violating supersymmetric coupling into tau lepton and b-quark. To collect events with multiple taus, a new special tau trigger (the lepton plus track trigger) is installed in Run II experiment of the Collider Detector at Fermilab (CDF). The goal of the lepton plus track trigger is to collect generic dilepton ({ell}{ell}, {ell}{tau}, {tau}{tau}) events with lower p{sub T} threshold (8 GeV/c) and without prescale even at high luminosity. The Z {yields} {tau}{tau} event, where one {tau}-lepton decays leptonically and the other hadronically, is a good benchmark to calibrate the lepton plus track trigger and {tau} identification. The data sample of 72 pb{sup -1}, collected using the electron plus track trigger, contains clear a {tau} signal from Z {yields} {tau}{tau} events. The data used in stop search correspond to 200 pb{sup -1}. The lower stop mass bound of 134 GeV/c{sup 2} at a 95% confidence level is obtained. This limit is also directly applicable to the …

The possible existence of light sterile neutrinos in Nature is motivated, and the prospects to extend sterile neutrino searches beyond current limits is substantiated, using the MiniBooNE neutrino beam and detector at Fermilab. We report on the neutrino flux predictions for the MiniBooNE experiment, on the characterization of the charged-current, quasi-elastic interactions of muon neutrinos ({nu}{sub {mu}}n {yields} {mu}{sup -}p) observed, and on the experiment's sensitivity to sterile neutrinos via muon neutrino disappearance.

A search for the CP-violating electric dipole (E1) direct emission contribution to the K{sub L} {yields} {pi}{sup +}{pi}{sup -}{gamma} decay is performed using data from the 1997 KTeV/E832 experiment. Because the K{sub L} {yields} {pi}{sup +}{pi}{sup -}{gamma} decay mode is massively dominated by the CP-violating inner bremsstrahlung (IB) and the CP-conserving magnetic dipole (M1) direct emission processes, previous analyses have neglected the E1 contribution. Therefore, this measurement is the first attempt to directly quantify the size of the E1 decay process. This E1 transition is one of the very few CP-violating processes that is accessible to experiment and, in principle, will produce new insights into the structure of the neutral kaon. The result of this analysis is that the E1 contribution is below the threshold of sensitivity, and therefore an upper bound of |g{sub E1}| < 0.14 (90% CL) is reported. In the process of obtaining this upper limit, high resolution measurements of fit parameters ({tilde g}{sub M1} and a{sub 1}/a{sub 2}) associated with the size and shape of the M1 direct emission peak are also extracted. The fit results for these parameters: {tilde g}{sub M1} = 1.229 {+-} 0.035 (stat) {+-} 0.087 (syst); a{sub 1}/a{sub 2} = -0.733 {+-} …

This thesis illustrates a complete study of the doubly and singly Cabibbo suppressed decays D{sup +} and D{sub s}{sup +} {yields} K{sup +} {pi}{sup -}{pi}{sup +}. Data for this analysis have been collected by the fixed-target high-energy photoproduction experiment FOCUS at Fermilab. The authors have selected the D{sup +} and D{sub s}{sup +} samples with cuts to obtain a sufficiently high statistics, a good signal to noise ratio and, at the same time, eliminate possible contaminations from the more copious and favored decays. The D{sup +} yield consists of 189 {+-} 24 events, with a signal to noise ratio {approx} 1; the D{sub s}{sup +} yield is 567 {+-} 31 and the signal to noise ratio is {approx} 2.5. The authors have measured {Lambda}(D{sup +} {yields} K{sup +}{pi}{sup -}{pi}{sup +})/{Lambda}(D{sup +} {yields} K{sup -}{pi}{sup +}{pi}{sup +}) = 0.0065 {+-} 0.0008 {+-} 0.004 and {Lambda}(D{sub s}{sup +} {yields} K{sup +}{pi}{sup -}{pi}{sup +})/{Lambda}(D{sub s}{sup +} {yields} K{sup +}K{sup -}{pi}{sup +}) = 0.127 {+-} 0.007 {+-} 0.014, improving the previous determinations of a factor of 2 and 5, respectively. The author has also performed a Dalitz plot analysis for both decays. The amplitude analysis for D{sub s}{sup +} {yields} K{sup +}{pi}{sup -}{pi}{sup +} …

A collocation method using cubic splines is developed and applied to simulate steady and time-dependent, including turbulent, thermally convecting flows for two-dimensional compressible fluids. The state variables and the fluxes of the conserved quantities are approximated by cubic splines in both space direction. This method is shown to be numerically conservative and to have a local truncation error proportional to the fourth power of the grid spacing. A ''dual-staggered'' Cartesian grid, where energy and momentum are updated on one grid and mass density on the other, is used to discretize the flux form of the compressible Navier-Stokes equations. Each grid-line is staggered so that the fluxes, in each direction, are calculated at the grid midpoints. This numerical method is validated by simulating thermally convecting flows, from steady to turbulent, reproducing known results. Once validated, the method is used to investigate many aspects of thermal convection with high numerical accuracy. Simulations demonstrate that multiple steady solutions can coexist at the same Rayleigh number for compressible convection. As a system is driven further from equilibrium, a drop in the time-averaged dimensionless heat flux (and the dimensionless internal entropy production rate) occurs at the transition from laminar-periodic to chaotic flow. This observation is …

The goal of this project is to provide the capability for simulating fluid flow on complicated geometries, such as in the Bahia de Todos Santos. The Bahia de Todos Santos is a bay situated in the northwest corner of Mexico, off the coast of Ensenada and south of San Diego, California, USA. Figure 1.1 shows the Bahia de Todos Santos. It is part of an image taken from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors on the Aqua and Terra satellites in late June and early July 2003 [8]. Roughly 200 square kilometers in size, the bay also contains two islands off the peninsula of Punta Banda. Characteristics of flow in this bay are driven by the moon tide (M2) and wind forcing [9].

This project will develop an analytical tool to calculate performance of HMX based PBXs in the skid test. The skid-test is used as a means to measure sensitivity for large charges in handling situations. Each series of skid tests requires dozens of drops of large billets. It is proposed that the reaction (or lack of one) of PBXs in the skid test is governed by the mechanical properties of the binder. If true, one might be able to develop an analytical tool to estimate skid test behavior for new PBX formulations. Others over the past 50 years have tried to develop similar models. This project will research and summarize the works of others and couple the work of 3 into an analytical tool that can be run on a PC to calculate drop height of HMX based PBXs. Detonation due to dropping a billet is argued to be a dynamic thermal event. To avoid detonation, the heat created due to friction at impact, must be conducted into the charge or the target faster than the chemical kinetics can create additional energy. The methodology will involve numerically solving the Frank-Kamenetskii equation in one dimension. The analytical problem needs to be bounded …

A measurement of the inclusive Z/{gamma}* {yields} {mu}{sup +}{mu}{sup -} cross section for M{sub {mu}{mu}} > 40 GeV at {radical}s = 1.96 TeV is presented. The measurement is performed using a data sample corresponding to an integrated luminosity of 147.7 pb{sup -1}, collected with the D0 detector at the Tevatron, Fermilab, between September 2002 and October 2003. A total of 14352 di-muon events are selected and a final result of {sigma}(Z/{gamma}*) = 327.8 {+-} 3.4(stat.) {+-} 8.4(syst.) {+-} 21.3(lumi.) pb is obtained. Correcting the number of di-muon events by a factor of 0.885 {+-} 0.015 for the contribution from pure {gamma}* exchange and Z/{gamma}* interference, the inclusive Z {yields} {mu}{sup +}{mu}{sup -} cross section is found to be: {sigma}(Z) = 290.1 {+-} 3.0(stat.) {+-} 7.4(syst.) {+-} 18.9(lumi.) pb. Finally, comparisons of W and Z boson p{sub T} distributions as measured with D0 during Run I of the Tevatron are compared to HERWIG and MC{at}NLO predictions. Relevant parameters in the simulations are tuned to obtain the best possible fit to the data. An excellent agreement is found for both HERWIG and MC{at}NLO.

Using the data collected with the D0 detector at {radical}s = 1.96 TeV with integrated luminosities of about 180 pb{sup -1}, we have measured the ratio of inclusive cross sections for p{bar p} {yields} Z + b-jet to p{bar p} {yields} Z + jet production. The inclusive Z + b-jet reaction is an important background to searches for the Higgs boson in associated ZH production at the Fermilab Tevatron collider and is sensitive to the b quark content of the proton. This thesis describes our measurement which is performed using the dimuon decay channel of the Z boson, i.e. Z {yields} {mu}{sup +}{mu}{sup -}. The ratio in the dimuon channel is measured to be 1.86 {+-} 0.44(stat){sub -0.28}{sup +0.24}(syst)% for hadronic jets with transverse momenta p{sub T} > 20 GeV/c and pseudorapidities |{eta}| < 2.5, consistent with next-to-leading order predictions of the standard model. This measurement is also combined with the result of the same ratio using the dielectron decay of the Z boson, and the combined measurement of the ratio of cross-sections yields 2.11 {+-} 0.41(stat){sub -0.25}{sup +0.22}(syst)%. In addition to our measurement, we also study optimization procedures for the search of Z({mu} {bar {mu}})+b{bar b} signal at D0. …

We discuss the measurement of the cross section for t{bar t} production in p{bar p} collisions at {radical}s = 1.96 TeV in e+jets final states observed at the D0 experiment at the Fermilab Tevatron. Our result is based on data collected from the June 2002 to September 2003 period of Run II of the p{bar p} Collider. In the Standard Model, the top quark is expected to decay mainly into a W boson and a b quark. The W boson can decay subsequently into a lepton and its neutrino or a q{bar q} quark-antiquark pair. In this thesis, we focus on the e{sup +} {nu}{sub e} or e{sup -} {bar {nu}}{sub e} decays of one of the W bosons and the q{bar q} decays of the other W boson in t{bar t} final states. The b, q and q' quarks appear as jets of particles in the detector, thereby defining the e+jets final state. We present two methods used for performing this measurement. The first method is based on a Random Grid Search (RGS) that minimizes the uncertainty on the extracted cross section. The variables used in the search take advantage of differences between expected background and signal processes to …