Accelerator Neutrinos

Abstract:

The TRIP-t front end board (TFB) will read out Geiger-mode multi-pixel Avalanche Photo-Diodes (GM-APD) in several T2K detector systems. We report the first tests of the TFB electronics with GM-APD. Measurements of GM-APD charge spectra, energy and time resolution have been performed. Individual channel voltage trimming circuit functionality has also been tested. These results indicate very good performance of the TFB prototype with both 400 and 100 pixels GMAPD from Hamamatsu photonics. © Copyright owned by the author(s).

Abstract:

We report the first measurements of inclusive W and Z boson cross-sections times the corresponding leptonic branching ratios for collisions at TeV based on the decays of the W and Z bosons into electrons and muons. The data were recorded with the CDF II detector at the Fermilab Tevatron and correspond to an integrated luminosity of 72.0 ± 4.3 pb-1. We test e-μ lepton universality in W decays by measuring the ratio of the W → μν to W → eν cross sections and determine a value of 0.991 ± 0.004(stat.) ± 0.011(syst.) for the ratio of W - ℓ - ν couplings (gμ/ge). Since there is no sign of non-universality, we combine our cross-section measurements in the different lepton decay modes and obtain σw × Br (pp̄ → W → ℓv) = 2.749 ± 0.010(stat.) ± 0.053(syst.) ± 0.165 (lum.) nb and σγ* × Br (pp̄ → γ*/Z → ℓℓ) = 254.9 ± 3.3(stat.) ± 4.6(syst.) ± 15.2(lum.) pb for dilepton pairs in the mass range between 66 GeV/c2 and 116 GeV/c2. We compute the ratio R of the W → ℓν to Z → ℓℓ cross sections taking all correlations among channels into account and obtain R = 10.84 ± 0.15(stat.) ± 0.14(syst.) including a correction for the virtual photon exchange component in our measured γ*/Z → ℓℓ cross section. Based on the measured value of R, we extract values for the W leptonic branching ratio, Br(W → ℓν)= 0.1082 ± 0.0022; the total width of the W boson, Γ(W)= 2092 ± 42 MeV; and the ratio of W and Z boson total widths, Γ(W)/Γ(Z)= 0.838 ± 0.017. In addition, we use our extracted value of Γ(W) whose value depends on various electroweak parameters and certain CKM matrix elements to constrain the Vcs CKM matrix element, |Vcs| = 0.976 ± 0.030. © 2007 IOP Publishing Ltd.

Abstract:

The Tokai-to-Kamioka (T2K) long baseline neutrino experiment goal is to measure vμto ve oscillation parameters using near (280 m) and far (295 km) detectors from the beam origin in the J-PARC accelerator in Tokai. The far detector will be Super-Kamiokande. The 280 m near detectors complex (ND280) contain a number of scintillator based sub-detectors and a beam monitor. Approximately 54,000 scintillator bars will be read out by Multi-Pixel Photon Counter devices (MPPC) via wavelength shifting fibres. It will be the first time this novel type of photo-sensor is used on such a large scale. The front end readout system for the MPPC uses Fermilab Trip-t chips mounted on Trip-t Front end Boards (TFB). The TFB design and measured performance in conjunction with MPPC photo-sensors are presented. © 2007 IEEE.

Abstract:

We present a measurement of the top quark pair production cross section in pp̄ collisions at s=1.96TeV utilizing 425pb-1 of data collected with the D0 detector at the Fermilab Tevatron Collider. We consider the final state of the top quark pair containing one high-pT electron or muon and at least four jets. We exploit specific kinematic features of tt̄ events to extract the cross section. For a top quark mass of 175 GeV, we measure σtt̄=6.4-1.2+1. 3(stat)±0.7(syst)±0.4(lum)pb, in good agreement with the standard model prediction. © 2007 The American Physical Society.