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An additional study of multi-muon events produced in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV

Description: We present one additional study of multi-muon events produced at the Fermilab Tevatron collider and recorded by the CDF II detector. We use a data set acquired with a dedicated dimuon trigger and corresponding to an integrated luminosity of 3.9 fb{sup -1}. We investigate the distribution of the azimuthal angle between the two trigger muons in events containing at least four additional muon candidates to test the compatibility of these events with originating from known QCD processes. We find that this distribution is markedly different from what is expected from such QCD processes and this observation strongly disfavours the possibility that multi-muon events result from an underestimate of the rate of misidentified muons in ordinary QCD events.
Date: November 1, 2011
Creator: Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A. et al.
Partner: UNT Libraries Government Documents Department

CDF End Plug calorimeter Upgrade Project

Description: We report on the status of the CDF End Plug Upgrade Project. In this project, the CDF calorimeters in the end plug and the forward regions will be replaced by a single scintillator based calorimeter. After an extensive R&D effort on the tile/fiber calorimetry, we have now advanced to a construction phase. We review the results of the R&D leading to the final design of the calorimeters and the development of tooling devised for this project. The quality control program of the production of the electromagnetic and hadronic calorimeters is described. A shower maximum detector for the measurement of the shower centroid and the shower profile of electrons, {gamma} and {pi}{sup 0} has been designed. Its performance requirements, R&D results and mechanical design are discussed.
Date: January 1, 1994
Creator: Apollinari, G.; de Barbaro, P. & Mishina, M.
Partner: UNT Libraries Government Documents Department

Design and Fabrication of a Single-Aperture 11T Nb3Sn Dipole Model for LHC Upgrades

Description: The planned upgrade of the LHC collimation system includes additional collimators to be installed in the dispersion suppressor areas of points 2, 3 and 7. To provide the necessary longitudinal space for the collimators, a replacement of 8.33 T Nb-Ti LHC main dipoles with 11 T dipoles based on Nb{sub 3}Sn superconductor compatible with the LHC lattice and main systems is being considered. To demonstrate this possibility FNAL and CERN have started a joint program to develop a 2 m long single-aperture dipole magnet with the nominal field of 11 T at {approx}11.85 kA current and 60 mm bore. This paper describes the demonstrator magnet magnetic and mechanical designs and analysis, coil fabrication procedure. The Nb{sub 3}Sn strand and cable parameters and test results are also reported.
Date: November 28, 2011
Creator: Andreev, N.; Apollinari, G.; Barzi, E.; Bossert, R.; Nobrega, F.; Novitski, I. et al.
Partner: UNT Libraries Government Documents Department

Design, fabrication and testing of single spoke resonators at Fermilab

Description: The Fermilab High Intensity Neutrino Source (HINS) linac R&D program is building a pulsed 30 MeV superconducting H- linac. The linac incorporates superconducting solenoids, high power RF vector modulators and superconducting spoke-type accelerating cavities starting at 10 MeV. This will be the first application and demonstration of any of these technologies in a low-energy, high-intensity proton/H- linac. The HINS effort is relevant to a high intensity, superconducting H- linac that might serve the next generation of neutrino physics and muon storage ring/collider experiments. In this paper we present the RF design, the mechanical design, the fabrication, the chemistry and testing of the first two SSR1 (Single Spoke Resonator type-1) prototype cavities that were built. These cavities operate at 325 MHz with {beta} = 0.21. The design and testing of the input coupler and the tuning mechanism are also discussed.
Date: September 1, 2009
Creator: Ristori, L.; Apollinari, G.; Borissov, E.; Gonin, I.V.; Khabiboulline, T.N.; Mukherjee, A. et al.
Partner: UNT Libraries Government Documents Department

Design of 325 MHz single and triple spoke resonators at FNAL

Description: The proposed 8-GeV driver at FNAL is based on approximately 400 independently phased SC resonators. In this paper the design of 325 MHz Spoke Resonators, two single spoke resonators ({beta}=0.22 and {beta}=0.4) and a triple spoke resonator ({beta}=0.62), for the High Intensity Neutrino Source (HINS) front end is presented. We describe the optimization of the spoke resonators geometry, the goal being to minimize the E{sub peak}/E{sub acc} and B{sub peak}/E{sub acc} ratios. We report on the coupled ANSYS-MWS analysis on the resonators mechanical properties and power coupler RF design. The current status of mechanical design, slow tuning mechanism and cryostat are also presented.
Date: August 1, 2006
Creator: Lanfranco, G.; Apollinari, G.; Gonin, I.; Khabiboulline, T.; McConologue, F.; Romanov, G. et al.
Partner: UNT Libraries Government Documents Department

Development of 325 MHz single spoke resonators at Fermilab

Description: The High Intensity Neutrino Source (HINS) project represents the current effort at Fermilab to produce an 8-GeV proton linac based on 400 independently phased superconducting cavities. Eighteen ?=0.21 single spoke resonators, operating at 325 MHz, comprise the first stage of the linac cold section. In this paper we present the current status of the production and testing of the first two prototype cavities. This includes descriptions of the fabrication, frequency tuning, chemical polishing, high pressure rinse, and high-gradient cold tests.
Date: August 1, 2008
Creator: Apollinari, G.; Gonin, I.V.; Khabiboulline, T.N.; Lanfranco, G.; Mukherjee, A.; Ozelis, J. et al.
Partner: UNT Libraries Government Documents Department

Development of Nb3Sn 11 T single aperture demonstrator dipole for LHC upgrades

Description: The LHC collimation upgrade foresees additional collimators installed in dispersion suppressor regions. To obtain the necessary space for the collimators, a solution based on the substitution of LHC main dipoles for stronger dipoles is being considered. CERN and FNAL have started a joint program to demonstrate the feasibility of Nb{sub 3}Sn technology for this purpose. The goal of the first phase is the design and construction of a 2-m long single-aperture demonstrator magnet with a nominal field of 11 T at 11.85 kA with 20% margin. This paper describes the magnetic and mechanical design of the demonstrator magnet and summarizes its design parameters.
Date: March 1, 2011
Creator: Zlobin, A.V.; Apollinari, G.; Andreev, N.; Barzi, E.; Kashikhin, V.V.; Nobrega, f. et al.
Partner: UNT Libraries Government Documents Department

Diffractive Dijet Production in $\bar{p}p$ Collisions at $\sqrt{s}=1.96$ TeV

Description: We report on a study of diffractive dijet production in {bar p}p collisions at {radical}s = 1.96 TeV using the CDF II detector at the Fermilab Tevatron {bar p}p collider. A data sample from 310 pb{sup -1} of integrated luminosity collected by triggering on a high transverse energy jet, E{sub T}{sup jet}, in coincidence with a recoil antiproton detected in a Roman pot spectrometer is used to measure the ratio of single-diffractive to inclusive-dijet event rates as a function of x{sup {bar p}} of the interacting parton in the antiproton, the Bjorken-x, x{sub Bj}{sup {bar p}}, and a Q{sup 2} {approx} (E{sub T}{sup jet}){sup 2} in the ranges 10{sup -3} < x{sub Bj}{sup {bar p}} < 10{sup -1} and 10{sup 2} < Q{sup 2} < 10{sup 4} GeV{sup 2}, respectively. Results are presented for the region of {bar p}-momentum-loss fraction 0.03 < {zeta}{sub {bar p}} < 0.09 and a four-momentum transfer squared t{sub {bar p}} > -4 GeV{sup 2}. The t{sub {bar p}} dependence is measured as a function of Q{sup 2} and x{sub Bj}{sup {bar p}} and compared with that of inclusive single diffraction dissociation. We find weak x{sub Bj}{sup bar p}} and Q{sup 2} dependencies in the ratio of single diffractive to inclusive event rates, and no significant Q{sup 2} dependence in the diffractive t{sub {bar p}} distributions.
Date: June 1, 2012
Creator: Aaltonen, T.; Albrow, M.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A. et al.
Partner: UNT Libraries Government Documents Department

Diffractive W and Z Production at the Fermilab Tevatron

Description: We report on a measurement of the fraction of events with a W or Z boson produced diffractively in {bar p}p collisions at {radical}s = 1.96 TeV, using data from 0.6 fb{sup -1} of integrated luminosity collected with the CDF II detector equipped with a Roman-pot spectrometer that detects the {bar p} from {bar p} + p {yields} {bar p}+[X+W/Z]. We find that (0.97 {+-} 0.11)% of Ws and (0.85 {+-} 0.22)% of Zs are produced diffractively in a region of (anti)proton fractional momentum loss {zeta} of 0.03 < {zeta} < 0.10 and 4-momentum transferred squared t of -1 < t < 0 (GeV/c){sup 2}. We also report on searches for W and Z production in double Pomeron exchange, p+{bar p} {yields} p+[X+W/z]+{bar p}, and on exclusive Z production, {bar p}p {yields} {bar p}+Z+p. No signal is seen above background for these processes, and comparisons are made with expectations.
Date: July 1, 2010
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Alvarez Gonzalez, B.; Phys., /Cantabria Inst. of; Amerio, S.; /INFN, Padua et al.
Partner: UNT Libraries Government Documents Department

Direct Measurement of the W Production Charge Asymmetry in p anti-p Collisions at s**(1/2) = 1.96-TeV

Description: We present the first direct measurement of the W production charge asymmetry as a function of the W boson rapidity y{sub W} in p{bar p} collisions at {radical}s = 1.96 TeV. We use a sample of W {yields} e{nu} events in data from 1 fb{sup -1} of integrated luminosity collected using the CDF II detector. In the region |y{sub W}| < 3.0, this measurement is capable of constraining the ratio of up and down quark momentum distributions in the proton more directly than in previous measurements of the asymmetry that are a function of the charged-lepton pseudorapidity.
Date: January 1, 2009
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, J.; /Chicago U., EFI; Akimoto, T.; U., /Tsukuba et al.
Partner: UNT Libraries Government Documents Department

A Direct Top-Quark Width Measurement from Lepton + Jets Events at CDF II

Description: We present a measurement of the top-quark width using t{bar t} events produced in p{bar p} collisions at Fermilab's Tevatron collider and collected by the CDF II detector. In the mode where the top quark decays to a W boson and a bottom quark, we select events in which one W decays leptonically and the other hadronically (lepton + jets channel) . From a data sample corresponding to 4.3 fb{sup -1} of integrated luminosity, we identify 756 candidate events. The top-quark mass and the mass of W boson that decays hadronically are reconstructed for each event and compared with templates of different top-quark widths ({Lambda}{sub t}) and deviations from nominal jet energy scale ({Delta}{sub JES}) to perform a simultaneous fit for both parameters, where {Delta}{sub JES} is used for the in situ calibration of the jet energy scale. By applying a Feldman-Cousins approach, we establish an upper limit at 95% confidence level (CL) of {Lambda}{sub t} < 7.6 GeV and a two-sided 68% CL interval of 0.3 GeV < {Lambda}{sub t} < 4.4 GeV for a top-quark mass of 172.5 GeV/c{sup 2}, which are consistant with the standard model prediction. This is the first direct measurement of {Lambda}{sub t} to set a lower limit with 68% CL.
Date: August 1, 2010
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Alvarez Gonzalez, B.; Phys., /Oviedo U. /Cantabria Inst. of; Amerio, S.; /INFN, Padua et al.
Partner: UNT Libraries Government Documents Department

Evidence for a Mass Dependent Forward-Backward Asymmetry in Top Quark Pair Production

Description: We present a new measurement of the inclusive forward-backward t{bar t} production asymmetry and its rapidity and mass dependence. The measurements are performed with data corresponding to an integrated luminosity of 5.3 fb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV, recorded with the CDF II Detector at the Fermilab Tevatron. Significant inclusive asymmetries are observed in both the laboratory frame and the t{bar t} rest frame, and in both cases are found to be consistent with CP conservation under interchange of t and {bar t}. In the t{bar t} rest frame, the asymmetry is observed to increase with the t{bar t} rapidity difference, {Delta}y, and with the invariant mass M{sub t{bar t}} of the t{bar t} system. Fully corrected parton-level asymmetries are derived in two regions of each variable, and the asymmetry is found to be most significant at large {Delta}y and M{sub t{bar t}}. For M{sub t{bar t}} {ge} 450 GeV/c{sup 2}, the parton-level asymmetry in the t{bar t} rest frame is A{sup t{bar t}} = 0.475 {+-} 0.114 compared to a next-to-leading order QCD prediction of 0.088 {+-} 0.013.
Date: January 1, 2011
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Alvarez Gonzalez, B.; Phys., /Cantabria Inst. of; Amerio, S.; /INFN, Padua et al.
Partner: UNT Libraries Government Documents Department

Evidence for a Narrow Near-Threshold Structure in the $J/\psi\phi$ Mass Spectrum in $B^+\to J/\psi\phi K^+$ Decays

Description: Evidence is reported for a narrow structure near the J/{psi}{phi} threshold in exclusive B{sup +} {yields} J/{psi}{phi}K{sup +} decays produced in {bar p}p collisions at {radical}s = 1.96 TeV. A signal of 14 {+-} 5 events, with statistical significance in excess of 3.8 standard deviations, is observed in a data sample corresponding to an integrated luminosity of 2.7 fb{sup -1}, collected by the CDF II detector. The mass and natural width of the structure are measured to be 4143.0 {+-} 2.9(stat) {+-} 1.2(syst) MeV/c{sup 2} and 11.7{sub -5.0}{sup +8.3}(stat) {+-} 3.7(syst) MeV/c{sup 2}.
Date: March 1, 2009
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, Jahred A.; /Chicago U., EFI; Akimoto, T.; U., /Tsukuba et al.
Partner: UNT Libraries Government Documents Department

Exclusion of an Exotic Top Quark with -4/3 Electric Charge Using Soft Lepton Tagging

Description: We present a measurement of the electric charge of the top quark using p{bar p} collisions corresponding to an integrated luminosity of 2.7 fb{sup -1} at the CDF II detector. We reconstruct t{bar t} events in the lepton+jets final state and use kinematic information to determine which b-jet is associated with the leptonically- or hadronically-decaying t-quark. Soft lepton taggers are used to determine the b-jet flavor. Along with the charge of the W boson decay lepton, this information permits the reconstruction of the top quark's electric charge. Out of 45 reconstructed events with 2.4 {+-} 0.8 expected background events, 29 are reconstructed as tt with the standard model +2/3 charge, whereas 16 are reconstructed as t{bar t} with an exotic -4/3 charge. This is consistent with the standard model and excludes the exotic scenario at 95% confidence level. This is the strongest exclusion of the exotic charge scenario and the first to use soft leptons for this purpose.
Date: June 1, 2010
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, J.; /Chicago U., EFI; Alvarez Gonzalez, B.; Phys., /Oviedo U. /Cantabria Inst. of 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

Fabrication and test of the first normal conducting crossbar H-type accelerating cavity at Fermilab for HINS

Description: The proposed High Intensity Neutrino Source (HINS) at Fermilab is based on an 8 GeV linear proton accelerator that consists of a normal-conducting (warm) and a superconducting section. The warm section is composed of an ion source, a radio frequency quadrupole, a medium energy beam transport (MEBT) and 16 warm Crossbar H-type (CH) cavities that accelerate the beam from 2.5 MeV to 10 MeV (from {beta}=0.0744 to {beta}=0.1422). These warm cavities are separated by superconducting solenoids enclosed in individual cryostats. Beyond 10 MeV, the design uses superconducting spoke resonators to accelerate the beam up to 8 GeV. In this paper, we illustrate the completion of the first warm CH cavity ({beta}=0.0744) explaining in detail the mechanical engineering aspects related to the machining and brazing processes. The radio-frequency (RF) measurements and tuning performed at Fermilab on the resonator and comparisons with simulations are also discussed.
Date: June 1, 2007
Creator: Ristori, L.; Apollinari, G.; Gonin, I.; Khabiboulline, T.; Romanov, G. & /Fermilab
Partner: UNT Libraries Government Documents Department

Fermilab HINS Proton Ion Source Beam Measurements

Description: The proton ion source for the High Intensity Neutrino Source (HINS) Linac front-end at Fermilab has been successfully commissioned. It produces a 50 keV, 3 msec beam pulse with a peak current greater than 20mA at 2.5Hz. The beam is transported to the radio-frequency quadrupole (RFQ) by a low energy beam transport (LEBT) that consists of two focusing solenoids, four steering dipole magnets and a beam current transformer. To understand beam transmission through the RFQ, it is important to characterize the 50 keV beam before connecting the LEBT to the RFQ. A wire scanner and a Faraday cup are temporarily installed at the exit of the LEBT to study the beam parameters. Beam profile measurements are made for different LEBT settings and results are compared to those from computer simulations. In lieu of direct emittance measurements, solenoid variation method based on profile measurements is used to reconstruct the beam emittance.
Date: May 1, 2009
Creator: Tam, W.M.; Apollinari, G.; Chaurize, S.; Hays, S.; Romanov, G.; Scarpine, V. et al.
Partner: UNT Libraries Government Documents Department

First Measurement of the Angular Coefficients of Drell-Yan $e^{+}e^{-}$ pairs in the Z Mass Region from $p\bar{p}$ Collisions at $\sqrt{s}$ = 1.96 TeV

Description: We report on the first measurement of the angular distributions of final state electrons in p{bar p} {yields} {gamma}*/Z {yields} e{sup +}e{sup -} + X events produced in the Z boson mass region at {radical}s = 1.96 TeV. The data sample collected by the CDF II detector for this result corresponds to 2.1 fb{sup -1} of integrated luminosity. The angular distributions are studied as a function of the transverse momentum of the electron-positron pair and show good agreement with the Lam-Tung relation, consistent with a spin-1 description of the gluon, and demonstrate that at high values of the transverse momentum, Z bosons are produced via quark anti-quark annihilation and quark-gluon Compton processes.
Date: March 1, 2011
Creator: Aaltonen, T.; Aaltonen, T.; Phys., /Helsinki Inst. of; Alvarez Gonzalez, B.; Phys., /Oviedo U. /Cantabria Inst. of; Amerio, S. et al.
Partner: UNT Libraries Government Documents Department

First Measurement of the b-jet Cross Section in Events with a W Boson in p anti-p Collisions at s**(1/2) = 1.96-TeV

Description: The cross section for jets from b quarks produced simultaneously with a W boson has been measured in p{bar p} collision data from 1.9 fb{sup -1} of integrated luminosity recorded by the CDF II detector at the Tevatron. Jets consistent with the decay of long-lived hadrons are selected by identifying a displaced decay vertex. The invariant mass of the charged particle tracks associated with the vertex is sensitive to the flavor of the decaying hadron and is used to determine the fraction of jets from b-quark production. We measure a b-jet cross section of 2.74 {+-} 0.27(stat.) {+-} 0.42(syst.) pb in association with one flavor of leptonic W boson decay over a limited kinematic phase space.
Date: September 1, 2009
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, J.; /Chicago U., EFI; Akimoto, T.; U., /Tsukuba et al.
Partner: UNT Libraries Government Documents Department

First Measurement of the Ratio sigma_(t-tbar) / sigma_(Z/\gamma*->ll) and Precise Extraction of the t-tbar Cross Section

Description: We report a measurement of the ratio of the t{bar t} to Z/{gamma}* production cross sections in {radical}s = 1.96 TeV p{bar p} collisions using data corresponding to an integrated luminosity of up to 4.6 fb{sup -1}, collected by the CDF II detector. The t{bar t} cross section ratio is measured using two complementary methods, a b-jet tagging measurement and a topological approach. By multiplying the ratios by the well-known theoretical Z/{gamma}* {yields} ll cross section predicted by the standard model, the extracted t{bar t} cross sections are effectively insensitive to the uncertainty on luminosity. A best linear unbiased estimate is used to combine both measurements with the result {sigma}{sub t{bar t}} = 7.70 {+-} 0.52 pb, for a top-quark mass of 172.5 GeV/c{sup 2}.
Date: April 1, 2010
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, J.; /Chicago U., EFI; Alvarez Gonzalez, B.; Phys., /Cantabria Inst. of et al.
Partner: UNT Libraries Government Documents Department

First Measurement of the t anti-t Differential Cross Section d sigma/dM(t anti-t) in p anti-p Collisions at s**(1/2)=1.96-TeV

Description: We present a measurement of the t{bar t} differential cross section with respect to the t{bar t} invariant mass, d{sigma}/dM{sub t{bar t}}, in p{bar p} collisions at {radical}s = 1.96 TeV using an integrated luminosity of 2.7 fb{sup -1} collected by the CDF II experiment. The t{bar t} invariant mass spectrum is sensitive to a variety of exotic particles decaying into t{bar t} pairs. The result is consistent with the standard model expectation, as modeled by PYTHIA with CTEQ5L parton distribution functions.
Date: March 1, 2009
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, Jahred A.; /Chicago U., EFI; Akimoto, T.; U., /Tsukuba et al.
Partner: UNT Libraries Government Documents Department