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Diffractive and Exclusive Production at the Tevatron

Description: Exclusive Higgs production, in which the event consists of nothing but the leading protons and a Higgs boson, has been proposed as a channel in which to study the properties of the Higgs boson at the Large Hadron Collider (LHC). Although we do not expect to observe exclusive Higgs-boson production at the Tevatron, we can observe similar processes which provide a calibration for theoretical predictions of exclusive Higgs production at the LHC. The CDF measurements of exclusive dijet and diphoton production, examples of such processes, are presented in Sec. 2. Single diffraction has been studied extensively at the Tevatron in Run I, including diffractive dijet and W/Z-boson production. New results with extended kinematical reach allowed by the larger Run II dataset are presented in Sec. 3. CDF II includes forward detectors designed for studying diffractive physics. The MiniPlug calorimeters cover the pseudorapidity region 3.5<|{eta}|<5.1. Beam Shower Counters (BSC) surrounding the beampipe in several locations detect particles in the forward region 5.4<|{eta}|<7.4. A spectrometer consisting of three Roman-pot detectors preceded by Tevatron dipoles is used to track diffractive antiprotons which have lost a fraction 0.03<{zeta}<0.10 of the beam momentum.
Date: October 1, 2008
Creator: Convery, M.E. & Collaboration, for the CDF
Partner: UNT Libraries Government Documents Department

A disoriented chiral condensate search at the Fermilab Tevatron

Description: MiniMax (Fermilab T-864) was a small test/experiment at the Tevatron designed to search for disoriented chiral condensates (DCC) in the forward direction. Relativistic quantum field theory treats the vacuum as a medium, with bulk properties characterized by long-range order parameters. This has led to suggestions that regions of {open_quotes}disoriented vacuum{close_quotes} might be formed in high-energy collision processes. In particular, the approximate chiral symmetry of QCD could lead to regions of vacuum which have chiral order parameters disoriented to directions which have non-zero isospin, i.e. disoriented chiral condensates. A signature of DCC is the resulting distribution of the fraction of produced pions which are neutral. The MiniMax detector at the C0 collision region of the Tevatron was a telescope of 24 multi-wire proportional chambers (MWPC`s) with a lead converter behind the eighth MWPC, allowing the detection of charged particles and photon conversions in an acceptance approximately a circle of radius 0.6 in pseudorapidity-azimuthal-angle space, centered on pseudorapidity {eta} {approx} 4. An electromagnetic calorimeter was located behind the MWPC telescope, and hadronic calorimeters and scintillator were located in the upstream anti-proton direction to tag diffractive events.
Date: May 1, 1997
Creator: Convery, M.E.
Partner: UNT Libraries Government Documents Department

CDF results on hard diffraction and rapidity gap physics

Description: We review published rapidity gap results on diffractive W and dijet production and discuss new results on diffractive b and J/{psi} production. The diffractive structure function of the proton obtained from Roman pot dijet data is presented and com- pared with expectations based on the diffractive parton densities extracted from DIS at HERA. Also presented are results on dijet production in double Pomeron exchange. Finally, we review hard double-diffractive results (rapidity gaps between jets) and present new results on soft double diffraction.
Date: October 11, 1999
Creator: Convery, M. E.
Partner: UNT Libraries Government Documents Department

Optimization of integrated luminosity in the Tevatron

Description: We present the strategy which has been used recently to optimize the performance of the Fermilab Tevatron proton-antiproton collider. We use a relatively simple heuristic model based on the antiproton production rate, which optimizes the number of antiprotons in a store in order to maximize the integrated luminosity. A store is terminated as soon as the target number of antiprotons is reached and the Tevatron quickly resets to load another store. Since this procedure was implemented, the integrated luminosity has improved by {approx} 35%. Other recent operational improvements include decreasing the shot setup time, and reducing beam-beam effects by making the proton and antiproton brightness more compatible, for example by scraping protons to smaller emittances.
Date: April 1, 2009
Creator: Gattuso, C.; Convery, M.; Syphers, M. & /Fermilab
Partner: UNT Libraries Government Documents Department

Relative Humidity in Limited Streamer Tubes for Stanford Linear Accelerator Center's BaBar Detector

Description: The BABAR Detector at the Stanford Linear Accelerator Center studies the decay of B mesons created in e{sup +}e{sup -} collisions. The outermost layer of the detector, used to detect muons and neutral hadrons created during this process, is being upgraded from Resistive Plate Chambers (RPCs) to Limited Streamer Tubes (LSTs). The standard-size LST tube consists of eight cells, where a silver-plated wire runs down the center of each. A large potential difference is placed between the wires and ground. Gas flows through a series of modules connected with tubing, typically four. LSTs must be carefully tested before installation, as it will be extremely difficult to repair any damage once installed in the detector. In the testing process, the count rate in most modules showed was stable and consistent with cosmic ray rate over an approximately 500 V operating range between 5400 to 5900 V. The count in some modules, however, was shown to unexpectedly spike near the operation point. In general, the modules through which the gas first flows did not show this problem, but those further along the gas chain were much more likely to do so. The suggestion was that this spike was due to higher humidity in the modules furthest from the fresh, dry inflowing gas, and that the water molecules in more humid modules were adversely affecting the modules' performance. This project studied the effect of humidity in the modules, using a small capacitive humidity sensor (Honeywell). The sensor provided a humidity-dependent output voltage, as well as a temperature measurement from a thermistor. A full-size hygrometer (Panametrics) was used for testing and calibrating the Honeywell sensors. First the relative humidity of the air was measured. For the full calibration, a special gas-mixing setup was used, where relative humidity of the LST gas mixture could be ...
Date: December 15, 2005
Creator: Lang, M.I.; /MIT; Convery, M.; /SLAC; Menges, W. & /Queen Mary, U. of London
Partner: UNT Libraries Government Documents Department

Accelerator/Experiment Operations - FY 2007

Description: This Technical Memorandum (TM) summarizes the Fermilab accelerator and accelerator experiment operations for FY 2007. It is one of a series of annual publications intended to gather information in one place. In this case, the information concerns the FY 2007 Run II at the Tevatron Collider, the MiniBooNE and SciBooNE experiments running in the Booster Neutrino Beam (BNB), MINOS using the Main Injector Neutrino Beam (NuMI), and the Meson Test Beam (MTest) activities in the 120 GeV external Switchyard beam (SY120). Each section was prepared by the relevant authors, and was somewhat edited for inclusion in this summary.
Date: October 1, 2007
Creator: Brice, S.; Buchanan, N.; Coleman, R.; Convery, M.; Denisov, D.; Ginther, G. et al.
Partner: UNT Libraries Government Documents Department

A Novel Technique for the Production of Large Area Z-coordinate Readout Planes for the BaBar Muon System

Description: The BABAR detector, at the Stanford Linear Accelerator Center is a general purpose detector for the study of e{sup +}e{sup -} interactions at the {Upsilon}(4S) resonance. BABAR's muon detection system consists of two parts: a hexagonal barrel region and two planar endcap regions each containing 18 layers of iron ({approx} 3.6{lambda}), with resistive plate chambers within the inter-iron gaps. These chambers have suffered deterioration in performance over the past few years and are being replaced by limited streamer tube chambers in the barrel. Each layer of the system consists of a set of up to 10 streamer tube modules oriented parallel to the beamline providing the azimuthal coordinate ({Phi}) and a single ''Z-plane'' with strips oriented perpendicular the streamer tubes providing the coordinate (Z) along the beamline. The large area Z-planes (up to 12 m{sup 2}) are 1 mm thick and contain 96 strips that detect the induced charge from avalanches on the streamer tube wires. This paper reports on the novel construction technique of the Z-planes.
Date: September 30, 2005
Creator: Convery, M.R.; Kim, P.C.; /SLAC; Paar, H.P.; /UC, San Diego; Rogers, C.H. et al.
Partner: UNT Libraries Government Documents Department

Measurements of B meson decays to (omega)K* and (omega)(rho)

Description: The authors describe searches for B meson decays to the charmless vector-vector final states {omega}K* and {omega}{rho} in 89 million B{bar B} pairs produced in e{sup +}e{sup -} annihilation at {radical}s = 10.58 GeV.
Date: March 14, 2006
Creator: Aubert, B.; Cheng, C. H.; Lange, D. J.; Simani, M. C.; Wright, D. M.; Abrams, G. S. et al.
Partner: UNT Libraries Government Documents Department

Exotic physics: search for new physics leading to high mass tau pairs with ppbar collisions at 1.96 tev using cdf ii

Description: Abstract: We present the results of a search for anomalous resonant production of tau lepton pairs with large invariant mass, the first such search using the CDF II Detector in Run II of the Tevatron p{bar p} collider. Such anomalous production could arise from various new physics processes. In a data sample corresponding to 195 pb{sup -1} of integrated luminosity we predict 2.8 {+-} 0.5 events from Standard Model background processes and observe 4. We use this result to set limits on the production of heavy scalar and vector particles decaying to tau lepton pairs.
Date: June 15, 2005
Creator: Academia Sinica Institute of Physics
Partner: UNT Libraries Government Documents Department