Supersymmetry is one of the most natural extensions of the Standard Model. At low energy it may consist in the Minimal Supersymmetric Standard Model which is the framework chosen to perform the search of the stop with 350 pb{sup -1} of data collected by D0 during the RunIIa period of the TeVatron. They selected the events with an electron, a muon, missing transverse energy and non-isolated tracks, signature for the stop decay in 3-body ({bar t} {yields} bl{bar {nu}}). Since no significant excess of signal is seen, the results are interpreted in terms of limit on the stop production cross-sections, in such a way that they extend the existing exclusion region in the parameter space (m{sub {bar t}},m{sub {bar {nu}}}) up to stop masses of 168 (140) GeV for sneutrino masses of 50 (94) GeV. Finally because of the crucial role of the electromagnetic calorimeter, a fine calibration was performed using Z {yields} e{sup +}e{sup -} events, which improved significantly the energy resolution.

We are becoming dependent on energy more today than we were a century ago, and with increasing world population and booming economies, sooner or later our energy sources will be exhausted. Moreover, our economy and welfare strongly depends on foreign oil and in the shadow of political uncertainties, there is an urgent need for a reliable, safe, and cheap energy source. Thermonuclear fusion, if achieved, is that source of energy which not only will satisfy our demand for today but also for centuries to come. Today, there are two major approaches to achieve fusion: magnetic confinement fusion (MFE) and inertial confinement fusion (ICF). This dissertation explores the inertial confinement fusion using the fast ignition concept. Unlike the conventional approach where the same laser is used for compression and ignition, in fast ignition separate laser beams are used. This dissertation addresses three very important topics to fast ignition inertial confinement fusion. These are laser-to-electron coupling efficiency, laser-generated electron beam transport, and the associated isochoric heating. First, an integrated fast ignition experiment is carried out with 0.9 kJ of energy in the compression beam and 70 J in the ignition beam. Measurements of absolute K{sub {alpha}} yield from the imploded core revealed …

A search for neutral supersymmetric Higgs bosons and work relating to the improvement of the b-tagging and trigger capabilities at the D0 detector during Run II of the Fermilab Tevatron collider is presented. The search for evidence of the Higgs sector in the Standard Model (SM) and supersymmetric extensions of the SM are a high priority for the D0 collaboration, and b-tagging and good triggers are a vital component of these searches. The development and commissioning of the first triggers at D0 which use b-tagging is outlined, along with the development of a new secondary vertex b-tagging tool for use in the Level 3 trigger. Upgrades to the Level 3 trigger hit finding code, which have led to significant improvements in the quality and efficiency of the tracking code, and by extension the b-tagging tools, are also presented. An offline Neural Network (NN) b-tagging tool was developed, trained on Monte Carlo and extensively tested and measured on data. The new b-tagging tool significantly improves the b-tagging performance at D0, for a fixed fake rate relative improvements in signal efficiency range from {approx} 40% to {approx} 15%. Fake rates, for a fixed signal efficiency, are typically reduced to between a quarter …

This thesis describes the development, calibration and performance evaluation of an Opposite-side b flavor tagger using K mesons at a p{bar p} hadron collider. In particular, this work is performed using data collected by the Collider Detector at Fermilab (CDF) during the Run II of the Tevatron hadron collider running at {radical}s = 1.96 TeV. b flavor tagging consists of the determination of the flavor of the b quark contained within a hadron. This information is vital to perform any time-dependent measurement involving flavor asymmetries in b hadron decays and flavor oscillations, where it is necessary to know whether a b or {bar b} was contained in a hadron when it was produced. Although at a hadron collider the biggest challenge is probably to perform an effective selection of interesting events in real time and with the best signal-to-background ratio, the statistical significance of any time-dependent measurement is proportional to the effectiveness with which the selected data sample is tagged.

Single Particle Aerosol Mass Spectrometry (SPAMS) was evaluated as a real-time detection technique for single particles of high explosives. Dual-polarity time-of-flight mass spectra were obtained for samples of 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitro-1,3,5-triazinane (RDX), and pentaerythritol tetranitrate (PETN); peaks indicative of each compound were identified. Composite explosives, Comp B, Semtex 1A, and Semtex 1H were also analyzed, and peaks due to the explosive components of each sample were present in each spectrum. Mass spectral variability with laser fluence is discussed. The ability of the SPAMS system to identify explosive components in a single complex explosive particle ({approx}1 pg) without the need for consumables is demonstrated. SPAMS was also applied to the detection of Chemical Warfare Agent (CWA) simulants in the liquid and vapor phases. Liquid simulants for sarin, cyclosarin, tabun, and VX were analyzed; peaks indicative of each simulant were identified. Vapor phase CWA simulants were adsorbed onto alumina, silica, Zeolite, activated carbon, and metal powders which were directly analyzed using SPAMS. The use of metal powders as adsorbent materials was especially useful in the analysis of triethyl phosphate (TEP), a VX stimulant, which was undetectable using SPAMS in the liquid phase. The capability of SPAMS to detect high explosives and CWA …