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A measurement of the top quark's charge

Description: The top quark was discovered in 1995 at the Fermilab National Accelerator Laboratory (Fermilab). One way to confirm if the observed top quark is really the top quark posited in the Standard Model (SM) is to measure its electric charge. In the Standard Model the top quark is the isospin partner of the bottom quark and is expected to have a charge of +2/3. However, an alternative 'exotic' model has been proposed with a fourth generation exotic quark that has the same characteristics, such as mass, as our observed top but with a charge of -4/3. This thesis presents the first CDF measurement of the top quark's charge via its decay products, a W boson and a bottom quark, using {approx} 1 fb{sup -1} of data. The data were collected by the CDF detector from proton anti-proton (p{bar p}) collisions at {radical}s = 1.96 TeV at Fermilab. We classify events depending on the charges of the bottom quark and associated W boson and count the number of events which appear 'SM-like' or 'exotic-like' with a SM-like event decaying as t {yields} W{sup +}b and an exotic event as t {yields} W{sup -}b. We find the p-value under the Standard Model hypothesis to be 0:35 which is consistent with the Standard Model. We exclude the exotic quark hypothesis at an 81% confidence level, for which we have chosen a priori that the probability of incorrectly rejecting the SM would be 1%. The calculated Bayes Factor (BF) is 2 x Ln(BF)=8.54 which is interpreted as the data strongly favors the Standard Model over the exotic quark hypothesis.
Date: November 1, 2007
Creator: Unalan, Zeynep Gunay & U., /Michigan State
Partner: UNT Libraries Government Documents Department

Measurement of the W + jet cross section at CDF

Description: A measurement of W {yields} ev + n-jet cross sections in p{bar p} collisions at {radical}s = 1.96 TeV using the Collider Detector at Fermilab in Run II is presented. The measurement is based on an integrated luminosity of 320 pb{sup -1}, and includes events with jet multiplicity from {ge} 1 to {ge} 4. In each jet multiplicity sample the differential and cumulative cross sections with respect to the transverse energy of the n{sup th}-leading jet are measured. For W + {ge} 2 jets the differential cross section with respect to the 2-leading jets invariant mass m{sub j{sub 1}j{sub 2}} and angular separation {Delta}R{sub j{sub 1}j{sub 2}} is also reported. The data are compared to predictions from Monte Carlo simulations.
Date: October 1, 2006
Creator: Messina, Andrea & U., /Michigan State
Partner: UNT Libraries Government Documents Department

Optimization of accelerator parameters using normal form methods on high-order transfer maps

Description: Methods of analysis of the dynamics of ensembles of charged particles in collider rings are developed. The following problems are posed and solved using normal form transformations and other methods of perturbative nonlinear dynamics: (1) Optimization of the Tevatron dynamics: (a) Skew quadrupole correction of the dynamics of particles in the Tevatron in the presence of the systematic skew quadrupole errors in dipoles; (b) Calculation of the nonlinear tune shift with amplitude based on the results of measurements and the linear lattice information; (2) Optimization of the Muon Collider storage ring: (a) Computation and optimization of the dynamic aperture of the Muon Collider 50 x 50 GeV storage ring using higher order correctors; (b) 750 x 750 GeV Muon Collider storage ring lattice design matching the Tevatron footprint. The normal form coordinates have a very important advantage over the particle optical coordinates: if the transformation can be carried out successfully (general restrictions for that are not much stronger than the typical restrictions imposed on the behavior of the particles in the accelerator) then the motion in the new coordinates has a very clean representation allowing to extract more information about the dynamics of particles, and they are very convenient for the purposes of visualization. All the problem formulations include the derivation of the objective functions, which are later used in the optimization process using various optimization algorithms. Algorithms used to solve the problems are specific to collider rings, and applicable to similar problems arising on other machines of the same type. The details of the long-term behavior of the systems are studied to ensure the their stability for the desired number of turns. The algorithm of the normal form transformation is of great value for such problems as it gives much extra information about the disturbing factors. In addition to ...
Date: May 1, 2007
Creator: Snopok, Pavel & U., /Michigan State
Partner: UNT Libraries Government Documents Department

Single top quark production at the Tevatron

Description: The Tevatron experiments D0 and CDF have found evidence for single top quark production, based on datasets between 0.9 fb{sup -1} and 2.2 fb{sup -1}. Several different multivariate techniques are used to extract the single top quark signal out of the large backgrounds. The cross section measurements are also used to provide the first direct measurement of the CKM matrix element |V{sub tb}|.
Date: May 1, 2008
Creator: Schwienhorst, Reinhard & U., /Michigan State
Partner: UNT Libraries Government Documents Department

Search for single top quark production at D0 in Run II

Description: I present a comprehensive search for electroweak production of single top quarks in Run II at the Fermilab Tevatron at {radical}s =1.96TeV. Using 230 pb{sup -1} of data collected with the D0 experiment, searches for s-channel and t-channel single top quark production have been carried out in the electron+jets and muon+jets decay channels using secondary-vertex b-quark tagging to select signal-like events. A binned likelihood has been constructed from the outputs of neural networks in order to maximize the sensitivity to single top quark production. No evidence for a single top quark signal is found. However, the 95% confidence level upper limits on the production cross section of 6.4 pb in the s-channel and 5.0 pb in the t-channel are improvements over previous limits by a factor of two and are approaching the cross section region predicted by the standard model.
Date: April 1, 2005
Creator: Schwienhorst, Reinhard & U., /Michigan State
Partner: UNT Libraries Government Documents Department

Measurement of the Diphoton Differential Cross Section in p anti-p Collisions at s**(1/2) = 1.96-TeV

Description: The diphoton differential cross-section as a function of mass up to 300 GeV/c{sup 2}, q{sub T} up to 100 GeV/c, and opening angle over a range of 0 to {pi} radians is measured. The measurement is performed using 1046.19 pb{sup -1} of data collected at Fermi National Accelerator Laboratory using the D0 detector. This analysis considers all direct diphoton states but attempts to suppress contributions due to fragmentation.
Date: January 1, 2007
Creator: Dyer, Joshua Marc & U., /Michigan State
Partner: UNT Libraries Government Documents Department

The inclusive jet cross-section in proton anti-proton collisions at s**(1/2) = 1.96-TeV using the MidPoint jet algorithm

Description: The following work presents a preliminary measurement of the inclusive jet cross section for jet transverse momenta from 61 to 620 GeV in the rapidity range 0.1 < |Y| < 0.7. The result is based on 218 pb{sup -1} of data collected by the CDF detector at the Fermi National Accelerator Lab. The data are consistent with NLO pQCD predictions based on the CTEQ6.1 parton distribution functions.
Date: April 1, 2005
Creator: Flanagan, Gene U. & U., /Michigan State
Partner: UNT Libraries Government Documents Department

Uncovering the single top: observation of electroweak top quark production

Description: The top quark is generally produced in quark and anti-quark pairs. However, the Standard Model also predicts the production of only one top quark which is mediated by the electroweak interaction, known as 'Single Top'. Single Top quark production is important because it provides a unique and direct way to measure the CKM matrix element V{sub tb}, and can be used to explore physics possibilities beyond the Standard Model predictions. This dissertation presents the results of the observation of Single Top using 2.3 fb{sup -1} of Data collected with the D0 detector at the Fermilab Tevatron collider. The analysis includes the Single Top muon+jets and electron+jets final states and employs Boosted Decision Tress as a method to separate the signal from the background. The resulting Single Top cross section measurement is: (1) {sigma}(p{bar p} {yields} tb + X, tqb + X) = 3.74{sub -0.74}{sup +0.95} pb, where the errors include both statistical and systematic uncertainties. The probability to measure a cross section at this value or higher in the absence of signal is p = 1.9 x 10{sup -6}. This corresponds to a standard deviation Gaussian equivalence of 4.6. When combining this result with two other analysis methods, the resulting cross section measurement is: (2) {sigma}(p{bar p} {yields} tb + X, tqb + X) = 3.94 {+-} 0.88 pb, and the corresponding measurement significance is 5.0 standard deviations.
Date: August 1, 2009
Creator: Benitez, Jorge Armando & U., /Michigan State
Partner: UNT Libraries Government Documents Department

Single top quark production and Vtb at the Tevatron

Description: Single top quark production via the electroweak interaction was observed by the D0 and CDF collaborations at the Tevatron proton-antiproton collider at Fermilab. Multivariate analysis techniques are employed to extract the small single top quark signal. The combined Tevatron cross section is 2.76{sub -0.47}{sup +0.58} pb. This corresponds to a lower limit on the CKM matrix element |V{sub tb}| of 0.77. Also reported are measurements of the t-channel cross section, the top quark polarization in single top quark events, and limits on gluon-quark flavor-changing neutral currents and W{prime} boson production.
Date: September 1, 2010
Creator: Schwienhorst, Reinhard & U., /Michigan State
Partner: UNT Libraries Government Documents Department

Standard Model Higgs searches at the Tevatron

Description: We report results of searches for the Standard Model Higgs Boson at the Fermilab Tevatron using up to 5.4 fb{sup -1} of data taken with the CDF and D0 detectors. There is no significant excess in the mass range of interest and the experiments set upper limits on the Higgs boson production cross section, including an exclusion of the Standard Model Higgs in the mass range 162-166 GeV.
Date: April 1, 2010
Creator: Herner, Kenneth & U., /Michigan
Partner: UNT Libraries Government Documents Department

Search for neutral supersymmetric Higgs bosons in \boldmath{$p\bar{p}$} collisions at \boldmath{$\sqrt{s}$} = 1.96 TeV

Description: We report results of searches for neutral supersymmetric Higgs Bosons in up to 2.7 fb{sup -1} of data collected with the D0 detector at the Fermilab Tevatron. The final states include muons, taus, and jets from the decay of b hadrons. The searches observe no significant excess and set upper limits on neutral Higgs production cross sections. The limits are also translated into exclusions of MSSM parameter space.
Date: August 1, 2009
Creator: Herner, Ken & U., /Michigan
Partner: UNT Libraries Government Documents Department

Observation of Single Top Quark Production with the D0 Detector

Description: We report on the observation of single top quark production by the D0 collaboration using a dataset of 2.3 fb{sup -1} collected at the Fermilab Tevatron p{bar p} collider. Several multivariate techniques are combined to separate the single top signal from backgrounds. The measured single top cross section is {sigma}{sub tb+tqb} = 3.94 {+-} 0.88 pb. The probability to measure a cross section at this value or higher in the absence of signal is 2.9 x 10{sup -7}, corresponding to a 5.0 standard deviation significance for the presence of signal. The lower limit at the 95% C.L. on the CKM matrix element V{sub tb} is |V{sub tb}| > 0.78. A separate measurement of the t-channel cross section gives {sigma}{sub tqb} = 3.14{sub -0.80}{sup +0.94} pb.
Date: August 1, 2009
Creator: Schwienhorst, Reinhard; collaboration, for the D0 & U., /Michigan State
Partner: UNT Libraries Government Documents Department

A GMBCG Galaxy Cluster Catalog of 55,424 Rich Clusters from SDSS DR7

Description: We present a large catalog of optically selected galaxy clusters from the application of a new Gaussian Mixture Brightest Cluster Galaxy (GMBCG) algorithm to SDSS Data Release 7 data. The algorithm detects clusters by identifying the red sequence plus Brightest Cluster Galaxy (BCG) feature, which is unique for galaxy clusters and does not exist among field galaxies. Red sequence clustering in color space is detected using an Error Corrected Gaussian Mixture Model. We run GMBCG on 8240 square degrees of photometric data from SDSS DR7 to assemble the largest ever optical galaxy cluster catalog, consisting of over 55,000 rich clusters across the redshift range from 0.1 < z < 0.55. We present Monte Carlo tests of completeness and purity and perform cross-matching with X-ray clusters and with the maxBCG sample at low redshift. These tests indicate high completeness and purity across the full redshift range for clusters with 15 or more members.
Date: August 22, 2011
Creator: Hao, Jiangang; /Fermilab; McKay, Timothy A.; U., /Michigan; Koester, Benjamin P.; U., /Chicago et al.
Partner: UNT Libraries Government Documents Department

Evolutionary algorithm for the neutrino factory front end design

Description: The Neutrino Factory is an important tool in the long-term neutrino physics program. Substantial effort is put internationally into designing this facility in order to achieve desired performance within the allotted budget. This accelerator is a secondary beam machine: neutrinos are produced by means of the decay of muons. Muons, in turn, are produced by the decay of pions, produced by hitting the target by a beam of accelerated protons suitable for acceleration. Due to the physics of this process, extra conditioning of the pion beam coming from the target is needed in order to effectively perform subsequent acceleration. The subsystem of the Neutrino Factory that performs this conditioning is called Front End, its main performance characteristic is the number of the produced muons.
Date: January 1, 2009
Creator: Poklonskiy, Alexey A.; U., /Michigan State; Neuffer, David & /Fermilab
Partner: UNT Libraries Government Documents Department

Muon cooling in a quadrupole magnet channel

Description: As discussed before,[1] a cooling channel using quadrupole magnets in a FODO transport channel can be used for initial cooling of muons. In the present note we discuss this possibility of a FODO focusing channel for cooling, and we present ICOOL simulations of muon cooling within a FODO channel. We explore a 1.5m cell-length cooling channel that could be used for the initial transverse cooling stage of a muon collider or neutrino factory.
Date: October 1, 2007
Creator: Neuffer, David; /Fermilab; Poklonskiy, A. & U., /Michigan State
Partner: UNT Libraries Government Documents Department

Pulsars as the Source of the WMAP Haze

Description: The WMAP haze is an excess in the 22 to 93 GHz frequency bands of WMAP extending about 10 degrees from the galactic center. We show that electron-positron pairs injected into the interstellar medium by the galactic population of pulsars with energies in the 1 to 100 GeV range can explain the WMAP haze. The same spectrum of high energy electron-positron pairs from pulsars, which gives rise to the haze, can also explain the observed excesses in AMS, HEAT and PAMELA.
Date: May 1, 2009
Creator: Kaplinghat, Manoj; /UC, Irvine; Phalen, Daniel J.; U., /Michigan; Zurek, Kathryn M. & U., /Fermilab /Michigan
Partner: UNT Libraries Government Documents Department

Experiments in a neutral hyperon beam

Description: The authors propose a survey experiment for a neutral hyperon beam, to measure production of {Lambda}{sup 0}, {bar {Lambda}}{sup 0}, {Xi}{sup 0}, {bar {Xi}}{sup 0}, K{sub 1}{sup 0} - K{sub 2}{sup 0} near zero mrad. by 200 GeV protons on complex nuclei. The detector will be sensitive to polarization of the hyperons. The same apparatus will then be used to search for {Xi}{sup 0} {yields} p{pi}{sup -} and to measure {Lambda}{sup 0} and {bar {Lambda}}{sup 0} total and diffractive elastic cross sections in hydrogen.
Date: June 1, 1970
Creator: March, R.H.; Pondrom, L.G.; /Wisconsin U., Madison; Overseth, O.E. & U., /Michigan
Partner: UNT Libraries Government Documents Department

200-GeV proton-proton elastic scattering at high transverse momentum

Description: This is a proposal to study p-p elastic scattering at the highest possible P{sub {perpendicular}}{sup 2} at NAL, using a CH{sub 2} or H{sub 2} target placed directly in the extracted beam and a double arm spectrometer. We expect to be able to set an upper limit at the level d{sigma}/dt/d{sigma}/dt{sub t=0} {approx} 10{sup -14}. This would be sufficient to determine if there are exactly three regions in the p-p interaction with considerable precision.
Date: June 1, 1970
Creator: Ratner, L.G.; /Argonne; Krisch, A.D.; Roberts, J.B.; Terwilliger, K.M. & U., /Michigan
Partner: UNT Libraries Government Documents Department

Neutron-proton diffraction scattering and neutron total cross-secions up to 200-GeV

Description: The authors propose to use the 0{sup o} neutral beam planned for Experimental Area 2 to measure differential cross sections for np elastic scattering in the diffraction region over the energy range of from 40 to 200 GeV and also total cross sections for neutrons on protons, deuterons, and other nuclei over the same energy range. The proposed experiments would use techniques previously developed by the authors in similar experiments at the Bevatron and the AGS. Most of the apparatus already exists. The two experiments could be run in the same beam, either simultaneously or sequentially. The experiments are simple and place very modest demands on accelerator performance.
Date: May 1, 1970
Creator: Longo, Michael J.; Jones, Lawrence W.; Overseth, Oliver E.; U., /Michigan; Cork, Bruce & /Argonne
Partner: UNT Libraries Government Documents Department

Neutron diffraction dissociation and coulomb dissociation from various nuclei

Description: We propose to use the 1.75 mr neutral beam in the Meson Lab to study the reaction n + A {yields} N* + A (p + {pi}{sup -}) for targets with as large a range in atomic weight as possible (e.g. hydrogen through lead) and incident neutron energies from approximately 80 to 200 GeV. The aim is to study (1) the cross section vs. energy and mass for (p{pi}{sup -}) masses from 1.08 to approximately 4.7 GeV, (2) the A dependence of the cross section from which information on N* total cross sections in nuclear matter can be extracted, (3) the t-dependence which, for the lighter elements, gives information on quantum numbers of the N* and the exchanged particle can be extracted. This experiment would be a natural extension of a similar experiment carried out by our group at the AGS last summer. The experience gained in the AGS experiment will be very valuable in designing an experiment for NAL.
Date: February 1, 1971
Creator: Longo, Michael J.; Gustafson, H.R.; Jones, Lawrence W.; vander Velde, John & U., /Michigan
Partner: UNT Libraries Government Documents Department

Study of multiparticle production in a small bubble chamber

Description: The authors propose to study 60,000 inelastic interactions in a small ({le} 80-inch) hydrogen chamber. They request four exposures of 15,000 interactions each, using both {pi}{sup -} and p as beam particles, at the two beam momenta 100 and 200 GeV/c. This requires 100,000 to 200,000 pictures, depending on the size of the chamber used. They couple this proposal to the strong recommendation that a small bubble chamber be available as soon as the machine provides experimental beams.
Date: June 1, 1970
Creator: Chapman, J.; Lys, J.; Ring, H.; Roe, B.; Sinclair, D.; VanderVelde, J. et al.
Partner: UNT Libraries Government Documents Department

Study of low-mass peripheral states in a small triggered bubble chamber

Description: The authors propose to study {approx} 40,000 events of the type beam particle + proton {yields} M + beam particle where M is a fairly low mass (2-5 GeV) state which is peripherally produced and slow in the lab. The decay products of M would be studied in detail as a function of M at two different beam momenta. The choice of beam particle and the two beam momenta would depend on what was technically most feasible, but at least the beam momenta should be greater than 100 GeV/c. A hydrogen bubble changer, pulsing several times per machine cycle, would be triggered on a fast forward particle near the beam momentum. The invariant mass M would be calculated for each event by momentum analysis of this particle. The experiment requires a beam with a momentum resolution {Delta}p/p of .002 or better and an emittance of .1 mm - mrad.
Date: June 1, 1970
Creator: Chapman, J.; Lys, J.; Ring, H.; Roe, B.; Sinclair, D.; VanderVelde, J. et al.
Partner: UNT Libraries Government Documents Department

Proton-Deuteron Interactions in the Thirty-Inch Bubble Chamber

Description: We propose two exposures in the thirty-inch chamber filled with deuterium, using protons of 100 and 200 GeV/c, with 50,000 pictures at each momentum. We plan to study various properties of p-n interactions including odd-prong multiplicity cross section, single and double dissociation, average {pi}{sup o} multiplicity, inclusive pion production, and correlations.
Date: May 8, 1972
Creator: Chapman, J.W.; Roe, B.P.; Seidl, A.; Sinclair, D.; VanderVelde, J.C. & U., /Michigan
Partner: UNT Libraries Government Documents Department