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New particle searches at CDF

Description: One of the fundamental roles of a general purpose detector exploring, by means of increasing luminosity, higher and higher mass reach, is to search for new particles and exotic phenomena. This is a continuing effort for the CDF collaboration, and will report on several searches using about 20 pb{sup -1} from the 1992/93 run labelled {open_quotes}run 1a{close_quotes} and {approximately}50 of the 90 pb{sup -1} so far from the current {open_quotes}run 1b.{close_quotes} These are mostly preliminary analyses, typically using a total of 70 pb{sup -1}. Our limits on SUSY using missing E{sub T} with jets as well as three leptons are discussed elsewhere; results from the D0 collaboration are similar. I will discuss searches for additional vector bosons Z{prime} and W{prime}, second generation scalar leptoquarks, as well as a broad search for objects decaying into jet pairs, including b-tagged jet pairs. I will also describe two events which do not fit in comfortably with either the standard model or a phenomenologically motivated search.
Date: September 1, 1995
Creator: Nodulman, L.J.
Partner: UNT Libraries Government Documents Department

Prospects for HERMES-spin structure studies at HERA

Description: HERMES (HERA Measurement of Spin), is a second generation experiment to study the spin structure of the nucleon by using polarized internal gas targets in the HERA 35-GeV electron storage ring. Scattered electrons and coincident hadrons will be detected in an open geometry spectrometer which will include particle identification. Measurements are planned for each of the inclusive structure functions, g{sub 1},(x), g{sub 2}(x), b{sub 1}(x) and A(x), as well as the study of semi-inclusive pion and kaon asymmetries. Targets of hydrogen, deuterium and {sup 3}He will be studied. The accuracy of data for the inclusive structure functions will equal or exceed that of current experiments. The semi-inclusive asymmetries will provide a unique and sensitive probe of the flavor dependence of quark helicity distributions and properties of the quark sea. Monte Carlo simulations of HERMES data for experiment asymmetries and polarized structure functions are discussed.
Date: December 31, 1994
Creator: Jackson, H.E.
Partner: UNT Libraries Government Documents Department

Strong interaction physics with pions at LAMPF: Report of the study group on future opportunities at LAMPF

Description: The LAMPF accelerator, with its high-intensity teams of pions and array of high-resolution spectrometers, provides opportunities for investigations of nuclear structure as well as of strong-interaction hadron dynamics. During operation of LAMPF as a national users facility, Nuclear Physics has undergone an evolution in the way it pictures nuclei: from a system of nucleons interacting through potentials to a system of mutually coupled nucleons, {Delta}(1232)`s, and mesons. While nuclear physics is in the midst of yet another shift of paradigm, with quarks and gluons playing a central role, the traditional picture still has great predictive power, and LAMPF has new opportunities to contribute to solving problems of current interest. At the same time, LAMPF is poised to make important contributions to the evolving area of nonperturbative QCD, where we will be learning how to connect phenomena at large momentum transfer to those at lower momentum scales. where the physically observable hadrons are the natural degrees of freedom. Within the traditional area, exploration of nuclei having extreme ratios of neutron/proton number is of growing interest in a variety of contexts, including astrophysics. Pion double charge exchange (the ({pi}{sup {plus_minus}}, {pi}{sup {plus_minus}}) processes) can produce proton-rich nuclei such as {sup 9}C, {sup 10}C, and {sup 11}N as well as neutron-rich nuclei such as {sup 10}He, {sup 11}Li, {sup 14}Be, and {sup 17}B. With spectrometers available for analyzing the outgoing pion spectra, one can study interesting and controversial modes of motion (soft-dipole modes) and obtain angular distributions that explore the spatial extent of neutron halos.
Date: July 1, 1995
Creator: Johnson, M.B. & Matthews, J.L.
Partner: UNT Libraries Government Documents Department

The CEBAF Large Acceptance Spectrometer (CLAS)

Description: The CEBAF Large Acceptance Spectrometer (CLAS) is used to study photo- and electro-induced nuclear and hadronic reactions by providing efficient detection of neutral and charged particles over a good fraction of the full solid angle. A collaboration of about thirty institutions has designed, assembled, and commissioned CLAS in Hall B at the Thomas Jefferson National Accelerator Facility. The CLAS detector is based on a novel six-coil toroidal magnet which provides a largely azimuthal field distribution. Trajectory reconstruction using drift chambers results in a momentum resolution of 0.5% at forward angles. Cerenkov counters, time-of-flight scintillators, and electromagnetic calorimeters provide good particle identification. Fast triggering and high data acquisition rates allow operation at a luminosity of 10{sup 34} nucleon cm {sup -2}s{sup -1}. These capabilities are being used in a broad experimental program to study the structure and interactions of mesons, nucleons, and nuclei using polarized and unpolarized electron and photon beams and targets. This paper is a comprehensive and general description of the design, construction and performance of CLAS.
Date: January 1, 2003
Creator: Mecking, Bernhard & Collaboration, CLAS
Partner: UNT Libraries Government Documents Department

Hadron fragmentation functions and leading particle effects in hadronic Z{sup 0} decays: New results from SLD

Description: The authors have measured the differential cross sections for the production of {pi}{sup {+-}}, K{sup {+-}}, K{sup 0}, K*(892), {phi}(1,020), p and {Lambda} in hadronic Z{sup 0} decays and in subsets of flavor-tagged Z{sup 0} {yields} light quark (u{anti u}, d{anti d}, or s{anti s}), Z{sup 0} {yields} c{anti c} and Z{sup 0} {yields} b{anti b} events. Charged hadrons were identified with the SLD Cherenkov ring imaging detector. The vertex detector was employed to select flavor enriched samples and the polarized electron beam from SLC was used to tag quark and anti-quark jets. The authors observe a flavor dependence in the hadron fragmentation functions. The authors present evidence for leading particle production in hadronic decays of the Z{sup 0} boson to light-flavor jets and a direct measurement of the strangeness suppression factor {gamma}{sub s}.
Date: May 1, 1997
Creator: Schwiening, J. & Collaboration, SLD
Partner: UNT Libraries Government Documents Department

DIRC, the internally reflecting ring imaging Cerenkov detector for BABAR: Properties of the quartz radiators

Description: A new type of detector for particle identification will be used in the BABAR experiment at the SLAC B Factory (PEP-II). This barrel region detector is called DIRC, an acronym for Detection of Internally Reflected Cerenkov (light). The DIRC is a Cerenkov ring imaging device which utilizes totally internally reflecting Cerenkov photons in the visible and near UV range. An extensive prototype program, demonstrated that the principles of operation are well understood, and that an excellent performance over the entire momentum range of the B factory is to be expected. The DIRC utilizes long, thin, flat quartz radiator bars (effective mean refractive index n{sub 1} = 1.474) with a rectangular cross section. In the present design the bars have transverse dimensions of 1.7 cm thick by 3.5 cm wide, and are about 4.90 m long. The length is achieved by gluing end-to-end four 1.225 m bars, that size being the longest high quality quartz bar currently available from industry. Several natural and synthetic fused silica candidate materials were tested for their optical properties and radiation hardness. In a Co{sup 60} source, samples were exposed to doses of up to 500 krad. While natural quartz materials showed significant absorption in the wavelength range of the Cerenkov photons after being exposed to only a few krad, the synthetic material proved to be sufficiently radiation hard. This led to the choice of Suprasil Standard and Spectrosil 2000 as bar material for the DIRC.
Date: July 1, 1997
Creator: Schwiening, J. & Collaboration, BABAR DIRC
Partner: UNT Libraries Government Documents Department

Physics with CLAS

Description: The authors describe the physics program and the experimental equipment of the CEBAF Large Acceptance Spectrometer, CLAS. The spectrometer is located in Hall B, one of the three experimental areas at the Continuous Electron Beam Accelerator Facility (CEBAF) operated by the Thomas Jefferson National Accelerator Facility. They review the program to study baryon resonances to demonstrate the multi-particle detection capabilities of the CLAS detector.
Date: September 1, 1997
Creator: Collaboration, E. Smith for the CLAS
Partner: UNT Libraries Government Documents Department

Measurement of sin2{beta} from J/{psi} K{sub s} decays

Description: The CP-violating parameter sin 2{beta} is directly measured using 110 pb{sup {minus}1} of data accumulated with the CDF detector at the Fermilab {anti p}p Tevatron collider operating at {radical}s = 1.8 TeV. The signal consists of 395 {+-} 31 B{sub d}{sup 0} {r{underscore}arrow} J/{psi} K{sub s} events. Three tagging methods are used to identify the type of B meson at production (B{sub d}{sup 0} or {anti B}{sub d}{sup 0}). From the CP asymmetry, sin 2{beta} is measured to be 0.79 {sub {minus}0.44}{sup +0.41}, consistent with Standard Model predictions. Sin 2{beta} is in the interval 0 {lt} sin2{beta} {lt} 1 at the 93% confidence level.
Date: January 24, 2000
Creator: Blocker, C.A.
Partner: UNT Libraries Government Documents Department

A limit on {sigma} {center_dot} BR (B{sub c}{sup {+-}} {yields} J/{psi} + {pi}{sup {+-}})/{sigma} {center_dot} BR(B{sub u}{sup {+-}} {yields} J/{psi} + K{sup {+-}}) in {radical}s = 1.8 TeV proton-antiproton collisions

Description: We report on the results of a search for the B{sub c} (b{bar c}) meson in the decay B{sub c}{sup +-} {yields} J/{psi} + {pi}{sup +-}. This search is guided by a control sample of decays of B{sub u} mesons to J/{psi} + K and uses {approx_equal} 75pb{sup -1} of data collected at the Collider Detector Facility (CDF) at Fermilab. The lifetime of the B{sub c} meson is unknown, so the 95% confidence level limit on {sigma} {center_dot} BR(B{sub c} {yields} {psi} + {pi})/{sigma} {center_dot} BR(B{sub u} {yields} {psi} + K) is obtained as a function of the B{sub c} lifetime.
Date: July 15, 1995
Creator: Abe, F.
Partner: UNT Libraries Government Documents Department

Neutrino oscillation appearance experiment using nuclear emulsion and magnetized iron

Description: This report describes an apparatus that could be used to measure both the identity and charge of an outgoing lepton in a charged current neutrino interaction. This capability in a massive detector would allow the most comprehensive set of neutrino oscillation physics measurements. By measuring the six observable transitions between initial and final state neutrinos, one would be able to measure all elements of the neutrino mixing matrix, as well as search for CP violation, and matter effects. If the measured matrix is not unitary, then one would also have an unambiguous determination of sterile neutrinos. Emulsion is considered as the tracking medium, and different techniques are discussed for the application of a magnetic field.
Date: January 24, 2000
Creator: Harris, D.A. & Para, A.
Partner: UNT Libraries Government Documents Department

Proceedings of PIXEL98 -- International pixel detector workshop

Description: Experiments around the globe face new challenges of more precision in the face of higher interaction rates, greater track densities, and higher radiation doses, as they look for rarer and rarer processes, leading many to incorporate pixelated solid-state detectors into their plans. The highest-readout rate devices require new technologies for implementation. This workshop reviewed recent, significant progress in meeting these technical challenges. Participants presented many new results; many of them from the weeks--even days--just before the workshop. Brand new at this workshop were results on cryogenic operation of radiation-damaged silicon detectors (dubbed the Lazarus effect). Other new work included a diamond sensor with 280-micron collection distance; new results on breakdown in p-type silicon detectors; testing of the latest versions of read-out chip and interconnection designs; and the radiation hardness of deep-submicron processes.
Date: August 1, 1998
Creator: Anderson, D.F. & Kwan, S.
Partner: UNT Libraries Government Documents Department

The CDF-II time-of-flight detector

Description: A Time-of-Flight (TOF) detector, based on plastic scintillator and fine-mesh photomultiplier tubes, has been added to the CDF-II experiment. Since August 2001, the TOF system has been fully instrumented and integrated into the CDF-II data acquisition system. The TOF system will provide particle identification of low momentum charged pions, kaons and protons in -collisions. With a design resolution goal of about 100 ps, separation between charged kaons and pions is expected at the 2 sigma level for momenta below 1.6 GeV/c, which enhances CDF's b-flavor tagging capabilities. They describe the design of the TOF detector and discuss its on-line and off-line calibration. Some performance benchmarks using proton-antiproton collision data are presented.
Date: July 1, 2002
Creator: Cabera, S. et al.
Partner: UNT Libraries Government Documents Department

CDF evidence for the top quark & B physics at Fermilab

Description: We present the first direct evidence for the top quark with the Collider Detector at Fermilab (CDF) in a sample of {bar p}p collisions at {radical}s=1.8 TeV with an integrated luminosity of 19.3 pb{sup -1}. The recent B physics results at Fermilab from both collider and fixed target experiments are reviewed.
Date: February 1, 1997
Creator: Yao, Weiming
Partner: UNT Libraries Government Documents Department

D0 search for new phenomena

Description: Presented here are the results from three searches for non-standard model particles using approximately 13 pb{sup {minus}1} of data taken with the D0 detector at Fermilab`s Tevatron, a p{bar p} collider operating at center-of-mass energy {radical}s=1.8 TeV. A heavy right-handed W, predicted by left-right symmetric theories, is excluded at 95% confidence level with mass between 200 GeV/c{sup 2} and 540 GeV/c{sup 2}, for a right-handed neutrino mass less than 100 GeV/c{sup 2}, regardless of the decay-properties of the neutrino, and assuming the W{sub R}`s couplings and C-K-M matrix are the same as the standard model W. Stricter limits are given on the right-handed neutrino mass for W{sub R} masses near the upper limit, and for specific assumptions on the right-handed neutrino decay modes. A 95% confidence-level limit on the cross-section p{bar p} {yields} W{sub 1}Z{sub 2} {yields} 3 leptons, where {sub 1}, is the lightest supersymmetric partner of the charged vector bosom and charged higgs and Z{sub 2} is the second lightest supersymmetric partner of the Z, {gamma}, and neutral higgs, ranging from 3 pb for M{sub w1}, =45 GeV/c{sup 2} to 1 pb for M{sub W1}=100 GeV/c{sup 2} is presented, assuming mass relations between the supersymmetric particles predicted by a popular supergravity inspired model. Third, a 95% confidence-level limit on the mass of the supersymmetric partner of the gluon of 144 GeV/c{sup 2}, if the supersymmetric partner of the quarks are very heavy, or 212 GeV/c{sup 2}, if they have equal masses, is presented within the framework of the same popular model.
Date: May 1, 1995
Creator: Eno, S.
Partner: UNT Libraries Government Documents Department

CP violation and rare decays

Description: After a brief essay on the current state of particle physics and possible approaches to the opportunities that have presented themselves, the author summarizes the contributions to the Third Workshop on Physics and Detectors for DA{Phi}NE that deal with CP Violation and Rare Decays.
Date: January 24, 2000
Creator: Quigg, C.
Partner: UNT Libraries Government Documents Department

CP violation at CDF

Description: A major goal of experimental particle physics over the next decade is to measure the sides and angles of the Unitarity triangle redundantly, and as precisely as possible. Overconstraining the triangle will test the Cabbibo-Kobayashi-Maskawa model of quark mixing. The CDF collaboration, due to begin a second run in March 2001 with major upgrades to both the accelerator and the detector, will study the angle {beta} using B{sup 0} decays, the angle {gamma} using B{sup 0} and B{sub s}{sup 0} decays, and a side of the triangle through the observation of B{sub s}{sup 0}--{bar B}{sub s}{sup 0} mixing. Projected sensitivities are driven mostly by previous measurements using data from the first run. One highlight of the Run I B physics program is a measurement of the CP violating parameter sin 2{beta} = 0.79{sub {minus}0.44}{sup +0.41}, based on a tagged sample of 400 B{sup 0} decays in the mode B{sub 0}/{bar B}{sup 0} {r_arrow} J/{psi}K{sub s}{sup 0}. The technology of flavor tagging, used here as well as in numerous B{sup 0}-{bar B}{sup 0} mixing analyses in run I, is crucial and will be augmented in Run II with better particle identification capabilities. Exclusive all-hadronic final states will enter the data sample in Run II through a new displaced track trigger.
Date: April 16, 2001
Creator: Boudreau, J.
Partner: UNT Libraries Government Documents Department

Tau jet signals for supersymmetry at the Tevatron

Description: The authors present a more detailed account of the study (hep-ph/9903238) for the supersymmetry reach of the Tevatron in channels with isolated leptons and identified tau jets. They review the theoretical motivations for expecting such signatures, and describe the relevant parameter space in the minimal supergravity and the minimal gauge-mediated models. With explicit Monte Carlo simulations they then show that for certain parameter ranges, channels with two leptons and one tau jet offer a better reach in Run 2 than the clean trilepton signal. They emphasize that improving on tau ID is an important prerequisite for successful searches in multiple tau jet channels. Finally, they discuss some triggering issues.
Date: January 25, 2000
Creator: Lykken, J.D. & Matchev, K.T.
Partner: UNT Libraries Government Documents Department

Search for exotic particles at CDF

Description: CDF has searched for 2nd generation leptoquarks, new gauge bosons W{prime} and Z{prime}, axigluons, excited quarks, color octet technirhos and E{sub 6} diquarks. We place the most stringent limits on direct production of these exotic particles.
Date: February 1, 1995
Creator: Harris, R.M.
Partner: UNT Libraries Government Documents Department

A recipe for the construction of confidence limits

Description: In this note, the authors present the recipe recommended by the Search Limits Committee for the construction of confidence intervals for the use of D0 collaboration. In another note, currently in preparation, they present the rationale for this recipe, a critique of the current literature on this topic, and several examples of the use of the method. This note is intended to fill the need of the collaboration to have a reference available until the more complete note is finished. Section 2 introduces the notation used in this note, and Section 3 contains the suggested recipe.
Date: April 12, 2000
Creator: al., Iain A Bertram et
Partner: UNT Libraries Government Documents Department

Run II jet physics: Proceedings of the Run II QCD and weak boson physics workshop

Description: The Run II jet physics group includes the Jet Algorithms, Jet Shape/Energy Flow, and Jet Measurements/Correlations subgroups. The main goal of the jet algorithm subgroup was to explore and define standard Run II jet finding procedures for CDF and D0. The focus of the jet shape/energy flow group was the study of jets as objects and the energy flows around these objects. The jet measurements/correlations subgroup discussed measurements at different beam energies; {alpha}{sub S} measurements; and LO, NLO, NNLO, and threshold jet calculations. As a practical matter the algorithm and shape/energy flow groups merged to concentrate on the development of Run II jet algorithms that are both free of theoretical and experimental difficulties and able to reproduce Run I measurements. Starting from a review of the experience gained during Run I, the group considered a variety of cone algorithms, and K{sub T} algorithms. The current understanding of both types of algorithms, including calibration issues, are discussed in this report along with some preliminary experimental results. The jet algorithms group recommends that CDF and D0 employ the same version of both a cone algorithm and a K{sub T} algorithm during Run II. Proposed versions of each type of algorithm are discussed. The group also recommends the use of full 4-vector kinematic variables whenever possible. The recommended algorithms attempt to minimize the impact of seeds in the case of the cone algorithm and preclustering in the case of the K{sub T} algorithm. Issues regarding precluster definitions and merge/split criteria require further study.
Date: May 11, 2000
Creator: al., Gerald C. Blazey et
Partner: UNT Libraries Government Documents Department

Search for new phenomena in CDF-I: Z{prime}, W{prime} and leptoquarks

Description: We present the latest results of CDF searches for Z{prime}, W{prime} and leptoquarks. Using about 70pb{sup -1} data from 1992-95 CDF runs, we have searched for Z{prime} {yields} l{sup +}l{sup -}, W{prime} {yields} WZ and pairs of second generation scalar leptoquark, S{sub 2}. We find no evidence for these new particles, and set new mass limits at 95% CL. We exclude M{sub Z{prime}} < 650 GeV/c{sup 2}, 205 < M{prime}{sub W} < 400 GeV/c{sup 2}, and M{sub S2} < 180 GeV/c{sup 2} for {beta} = 1 and M{sub S2} < 141 GeV/c{sup 2} for {beta} = 0.5. Two interesting strange events are also shown.
Date: July 1, 1995
Creator: Park, S.
Partner: UNT Libraries Government Documents Department

Pion, kaon, proton and anti-proton transverse momentum distributions from p+p and d+Au collisions at sqrt(sNN) = 200 GeV

Description: Identified mid-rapidity particle spectra of {pi}{sup {+-}}, K{sup {+-}}, and p({bar p}) from 200 GeV p+p and d+Au collisions are reported. A time-of-flight detector based on multi-gap resistive plate chamber technology is used for particle identification. The particle-species dependence of the Cronin effect is observed to be significantly smaller than that at lower energies. The ratio of the nuclear modification factor (R{sub dAu}) between (p+ {bar p}) and charged hadrons (h) in the transverse momentum range 1.2 &lt; p{sub T} &lt; 3.0 GeV/c is measured to be 1.19 {+-} 0.05(stat) {+-} 0.03(syst) in minimum-bias collisions and shows little centrality dependence. The yield ratio of (p + {bar p})/h in minimum-bias d+Au collisions is found to be a factor of 2 lower than that in Au+Au collisions, indicating that the Cronin effect alone is not enough to account for the relative baryon enhancement observed in heavy ion collisions at RHIC.
Date: September 16, 2003
Creator: Adams, J.; Adler, C.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B.D. et al.
Partner: UNT Libraries Government Documents Department

Detector implications for eletroweak physics at the Tevatron

Description: D0 and CDF are two large, powerful, multipurpose detectors with outstanding tracking, calorimeter and muon systems that have done an excellent job in exploiting the Top Quark, b Quark, QCD, New Phenomena/Exotics and Electroweak Physics at the Fermilab Tevatron Collider. The upgrades of the D0 and CDF detectors will further enhance their capabilities for physics at the Tevatron. The addition of a magnetic field and silicon vertex chamber will open up new physical opportunities for D0, and the replacement of the plug and forward gas calorimeters with new scintillator based calorimeters will give CDF uniform calorimetry over all {eta}.
Date: December 1, 1996
Creator: Madaras, R.J.
Partner: UNT Libraries Government Documents Department

Particle physics with kaons, muons and neutrinos. Summary of JHF K-Arena working groups 1a/1b

Description: The areas of rare K and {mu} decays and of neutrino oscillations are very active at the present time, and there is little reason to doubt that this will continue to be the case in the JHF era. The session featured talks describing the present status and projected future activity in these areas.
Date: August 1, 1998
Creator: Kuno, Yoshitaka & Littenberg, L.
Partner: UNT Libraries Government Documents Department