SVX4 is the new silicon strip readout IC designed to meet the increased radiation tolerance requirements for Run IIb at the Tevatron collider. Devices have been fabricated, tested, and approved for ...production. The SVX4 design is a technology migration of the SVX3D design currently in use by CDF. Whereas SVX3D was fabricated in a 0.8-/spl mu/m radiation-hard process, SVX4 was fabricated in a standard 0.25-/spl mu/m mixed-signal CMOS technology using the "radiation tolerant by design" transistor topologies devised by the CERN RD49 collaboration. The specific cell layouts include digital cells developed by the ATLAS Pixel group, and full-custom analog blocks. Unlike its predecessors, the new design also includes the necessary features required for generic use by both the CDF and D0 experiments at Fermilab. Performance of the IC includes >20 MRad total dose tolerance, and /spl sim/2000 e-rms equivalent input noise charge with 40-pF input capacitance, when sampled at 132-ns period with an 80-ns preamp risetime. At the nominal digitize/readout rate of 106/53 MHz, the 9 mm/spl times/6.3 mm die dissipates /spl sim/2 mW/channel average at 2.5 V. A review of typical operation, details of the design conversion process, and performance measurements are covered.
The layer 0 inner silicon detector of the D0 experiment Angstadt, R.; Bagby, L.; Bean, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2010, Letnik:
622, Številka:
1
Journal Article
Recenzirano
Odprti dostop
This paper describes the design, fabrication, installation and performance of the new inner layer called Layer 0 (L0) that was inserted in the existing Run IIa silicon micro-strip tracker (SMT) of ...the D0 experiment at the Fermilab Tevatron p¯p collider. L0 provides tracking information from two layers of sensors, which are mounted with center lines at a radial distance of 16.1 and 17.6mm from the beam axis. The sensors and read-out electronics are mounted on a specially designed and fabricated carbon fiber structure that includes cooling for sensor and read-out electronics. The structure has a thin polyimide circuit bonded to it so that the circuit couples electrically to the carbon fiber allowing the support structure to be used both for detector grounding and a low impedance connection between the remotely mounted hybrids and the sensors.
We search for the semi-inclusive process B_s^0 --> D_s^(*)D_s^(*) using 2.8 fb^-1 of ppbar collisions at s^(1/2) = 1.96 TeV recorded by the D0 detector operating at the Fermilab Tevatron Collider. We ...observe 26.6 +/- 8.4 signal events with a significance above background of 3.2 standard deviations yielding a branching ratio of Br(B_s^0 --> D_s^(*)D_s^(*)) = 0.035 +/- 0.010(stat) +/- 0.011(syst). Under certain theoretical assumptions, these double-charm final states saturate CP-even eigenstates in the B_s^0 decays resulting in a width difference of Delta_Gamma_s^CP/Gamma_s = 0.072 +/- 0.021(stat) +/- 0.022(syst). This corresponds to the first evidence for a width difference in the B_s^0 system.
We present the first evidence of WW+WZ production with lepton+jets final states at a hadron collider. The data correspond to 1.07 inverse femtobarns of integrated luminosity collected with the D0 ...detector at the Fermilab Tevatron Collider in proton-antiproton collisions at sqrt(s)=1.96 TeV. The observed cross section for WW+WZ production is 20.2 +/- 4.5 pb, consistent with the SM prediction of 16.1 +/- 0.9 pb. The probability for background fluctuations to produce an excess equal to or larger than that observed is estimated to be 5.4e-6, corresponding to a significance of 4.4 standard deviations.
The first search in ppbar collisions at sqrt(s)=1.96 GeV for the production of neutral Higgs bosons in association with bottom quarks and decaying in two tau leptons is presented. The cross section ...for this process is enhanced in many extensions of the Standard Model (SM), such as its minimal supersymmetric extension (MSSM) at large tan(beta). The data, corresponding to an integrated luminosity of 328 pb-1, were collected with the D0 detector at the Fermilab Tevatron Collider. An upper limit is set on the production cross section of neutral Higgs bosons in the mass range of 90 to 150 GeV, and this limit is used to exclude part of the MSSM parameter space.
We present the first observation of the Zgamma to nunugamma process at the Tevatron at 5.1 standard deviations significance, based on 3.6 fb-1 of integrated luminosity collected with the D0 detector ...at the Fermilab Tevatron ppbar Collider at sqrt{s} = 1.96 TeV. The measured Zgamma cross section multiplied by the branching fraction of Z to nunu is 32 +- 9 (stat.+syst.) +- 2 (lumi.) fb for the photon ET > 90 GeV. It is in agreement with the standard model prediction of 39 +- 4 fb. We set the most restrictive limits on anomalous trilinear Zgammagamma and ZZgamma gauge boson couplings at a hadron collider to date, with three constraints being the world's strongest.
We present cross section measurements for Z/gamma*+jets+X production, differential in the transverse momenta of the three leading jets. The data sample was collected with the D0 detector at the ...Fermilab Tevatron proton anti-proton collider at a center-of-mass energy of 1.96 TeV and corresponds to an integrated luminosity of 1 fb-1. Leading and next-to-leading order perturbative QCD predictions are compared with the measurements, and agreement is found within the theoretical and experimental uncertainties. We also make comparisons with the predictions of four event generators. Two parton-shower-based generators show significant shape and normalization differences with respect to the data. In contrast, two generators combining tree-level matrix elements with a parton shower give a reasonable description of the the shapes observed in data, but the predicted normalizations show significant differences with respect to the data, reflecting large scale uncertainties. For specific choices of scales, the normalizations for either generator can be made to agree with the measurements.
We report results of a search for the pair production of the lightest supersymmetric partner of the top quark using 1 fb-1 of data collected by the D0 detector at a ppbar center-of-mass energy of ...1.96 TeV at the Fermilab Tevatron Collider. Both scalar top quarks are assumed to decay into a b quark, a charged lepton and a scalar neutrino. The search is performed in the electron plus muon and dielectron final states. The signal topology consists of two isolated leptons, missing transverse energy, and jets. We find no evidence for this process and exclude regions of parameter space in the framework of the minimal supersymmetric standard model.
PDF
