The authors have studied the W + {ge} n jets process in Tevatron Run II experiment. The data used correspond to a total integrated luminosity of 72 pb{sup -1} taken from March 2002 through January 2003. The lowest order QCD predictions have been tested with a new prescription of the parton-jet matching, which allows to construct the enhanced LO phase space. According to this procedure, one gets unique results which do not depend on unphysical bias of kinematical cuts to avoid the collinear/infrared divergence in calculation. Namely, one can get the meaningful results in the lowest order prediction. The controllable event samples of the W boson plus jets events by the enhanced lowest order prediction will lead smaller systematic uncertainty than the naive prediction without any cares of the collinear/infrared divergence. They expect their method will be also useful to make systematically small samples as the background estimates in the top quark analysis. They found a good agreement between data and theory in typical kinematics distributions. The number of events for each inclusive sample up to 3 jets are compared with Monte Carlo calculations. A comparison with Run I results is also presented. This is the first result for the …

The Collider Detector at Fermilab (CDF) is a multi-purpose detector designed to study proton-antiproton collisions at center-of-mass energies of 1.96 TeV/c{sup 2}. One of the most importatn components of CDF is the silicon tracking detector. A detailed description of the testing and construction of the CDF silicon tracker is presented. Measurements of the tracking efficiency of the completed detector are also provided. Using 36 pb{sup -1} of the J/{psi} data sample collected by CDF between February and October 2002, the inclusive B {yields} J/{psi} X cross-section is measured in p{bar p} interactions at {radical}s = 1.96 TeV/c{sup 2}. The fraction of J/{psi} events arising from the decay of b hadrons is extracted using an unbinned maximum likelihood fit to the decay length of the J/{psi} candidates. The p{sub T} dependent differential cross section for inclusive B {yields} J/{psi} X events with rapidity |y| < 0.6 is obtained by combining the B-fraction result with a measurement of the J/{psi} differential cross-section. For 2.0 < p{sub T}(J/{psi}) < 17.0 GeV/c, the integrated B {yields} J/{psi} X cross-section is measured to be {sigma}(J/{psi}, B) {center_dot} {Beta}(J/{psi} {yields} {mu}{mu}) = 16.02 {+-} 0.24(stat){sub -2.20}{sup +2.26}(syst) nb.

The Cryogenic Dark Matter Search (CDMS) uses cryogenically-cooled detectors made of germanium and silicon in an attempt to detect dark matter in the form of Weakly-Interacting Massive Particles (WIMPs). The expected interaction rate of these particles is on the order of 1/kg/day, far below the 200/kg/day expected rate of background interactions after passive shielding and an active cosmic ray muon veto. Our detectors are instrumented to make a simultaneous measurement of both the ionization energy and thermal energy deposited by the interaction of a particle with the crystal substrate. A comparison of these two quantities allows for the rejection of a background of electromagnetically-interacting particles at a level of better than 99.9%. The dominant remaining background at a depth of {approx} 11 m below the surface comes from fast neutrons produced by cosmic ray muons interacting in the rock surrounding the experiment. Contamination of our detectors by a beta emitter can add an unknown source of unrejected background. In the energy range of interest for a WIMP study, electrons will have a short penetration depth and preferentially interact near the surface. Some of the ionization signal can be lost to the charge contacts there and a decreased ionization signal relative …

We have studied the dissociation of CO catalyzed by platinum single crystals. At 40 torr of CO, the Pt(111) crystal dissociates CO at 673 K. Under the same conditions, Pt(100) dissociates CO at 500 K, and Pt(557) dissociates CO at 548 K. Hence, the CO dissociation reaction is a structure sensitive reaction. SFG was used to monitor the CO top site resonance as the platinum crystals were heated to the dissociation temperature when exposed to 40 torr of CO. In all three systems, the CO resonance shifts to lower frequency as the platinum crystal is heated. However, the frequency of the CO resonance at the dissociation frequency is lower on the (100) and (111) crystal faces than on the Pt(557) crystal. We believe that the (111) and (100) crystal faces must undergo roughening to expose step or kink sites in order to facilitate the dissociation reaction. This is supported by UHV studies of CO dissociation catalyzed by platinum crystals. These studies observe dissociation only when step or kink sites are present. Since the Pt(111) surface is very stable, it needs to be heated to 673 K to produce the low coordination number sites needed for CO dissociation. Since the Pt(100) …

This thesis describes a measurement of the proper lifetime of the B{sub s}{sup 0} mesons produced in proton-antiproton collisions at a center of mass energy of 1.96 TeV, collected by the CDF experiment at Fermilab. The B{sub s}{sup 0} meson lifetime is measured in its semileptonic decay mode, B{sub s}{sup 0} {yields} {ell}{sup +}{nu}{sub {ell}}D{sub s}{sup -}. The D{sub s}{sup -} meson candidates are reconstructed in the decay mode D{sub s}{sup -} {yields} {phi}{pi}, with {phi} {yields} K{sup +}K{sup -}, in a trigger sample which requires a muon or an electron and another track which has a large impact parameters. The large impact parameter track is required by the silicon vertex trigger which is an innovative triggering device which has not previously been used in lifetime measurements. A total of 905 {+-} B{sub s}{sup 0} candidates are reconstructed in a sample which has an integrated luminosity of 140 pb{sup -1} using data gathered between February 2002 and August 2003. The pseudo-proper lifetime distribution of these candidates is fitted with an unbinned maximum likelihood fit. This fit takes into account the missing momentum carried by the neutrino and the bias caused by requiring a track with large impact parameter by modeling …

We have searched for evidence for the chargino {bar {chi}}{sub 1}{sup {+-}} and neutralino ({bar {chi}}{sub 2}{sup 0}) pair production in proton anti-proton collisions at a center of mass energy of 1.96 TeV with the D0 detector at the Fermilab Tevatron Collider. Data corresponding to an integrated luminosity of 124.5 pb{sup -1} were examined for events containing like-sign electron pair and missing energy for the first time at D0. They observed no excess above the yield from Standard Model processes. In the framework of mSUGRA, they set a series of upper limits, at the 95% confidence level, of the chargino neutralino production cross section times the branching fraction to tri-electrons as a function of the chargino mass. These limits range from 0.79 pb for m{sub {bar {chi}}{sub 1}{sup {+-}}} = 86.9 GeV/c{sup 2} to 0.52 pb for m{sub {bar {chi}}{sub 1}{sup {+-}}} = 115.1 GeV/c{sup 2}.

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This work presents a search for the pair production of doubly-charged Higgs Bosons in the process p{bar p} {yields} H{sup ++}H{sup --} {yields} {mu}{sup +}{mu}{sup +}{mu}{sup -}{mu}{sup -} using inclusive dimuon events. These data correspond to an integrated luminosity of about 113 pb 1 and were recorded by the D0 experiment between August 2002 and June 2003. In the absence of a signal, 95% confidence level mass limits of M(H{sub L}{sup {+-}{+-}}) > 118.6 GeV/c{sup 2} and M(H{sub R}{sup {+-}{+-}}) > 98.1 GeV/c{sup 2} are set for left-handed and right-handed doubly-charged Higgs boson, assuming 100% branching into muons and hypercharge |Y| = 2 and Yukawa coupling h{sub {mu}{mu}} > 10{sup -7}. This is the first search for doubly-charged Higgs bosons at hadron colliders. It significantly extends the previous mass limit of 100.5 GeV/c{sup 2} for a left-handed doubly-charged Higgs boson measured in the muon final states by the OPAL collaboration.