418 Matching Results

Search Results

Advanced search parameters have been applied.

Extracting longitudinal shower development information from crystal calorimetry plus tracking

Description: We present an approach to derive longitudinal shower development information from the longitudinally unsegmented BABAR electromagnetic calorimeter by using tracking information. Our algorithm takes advantage of the good three-dimensional tracking resolution of BABAR, which provides an independent geometric constraint on the shower as measured in the BABAR crystal calorimeter. We show that adding the derived longitudinal shower development information to standard particle identification algorithms significantly improves the low-momentum separation of pions from electrons and muons. We also verify that the energy dependence of the electromagnetic shower development we measure is consistent with the prediction of a standard electromagnetic shower model.
Date: November 1, 2007
Creator: Brown, David; Brown, D.N.; Ilic, J. & Mohanty, G.B.
Partner: UNT Libraries Government Documents Department

Progress on Development of the New FDIRC PID Detector

Description: We present a progress status of a new concept of PID detector called FDIRC, intended to be used at the SuperB experiment, which requires {pi}/K separation up to a few GeV/c. The new photon camera is made of the solid fused-silica optics with a volume 25x smaller and speed increased by a factor of ten compared to the BaBar DIRC, and therefore will be much less sensitive to electromagnetic and neutron background
Date: August 3, 2012
Creator: Vavra, Jerry
Partner: UNT Libraries Government Documents Department

The Focusing DIRC - the First RICH Detector toCorrect the Chromatic Error by Timing, and the Development of a New TOFDetector Concept

Description: We have built and successfully tested a novel particle identification detector called Focusing DIRC. The prototype's concept is based on the BaBar DIRC with several important improvements: (a) much faster pixilated photon detectors based on Burle MCP-PMT and Hamamatsu MaPMT, (b) mirror allowing to make the photon detector smaller and less sensitive to background in future applications, (c) electronics allowing to measure the single photon resolution to better than {sigma} {approx} 100-200ps, which allows a correction of the chromatic error. While testing the timing resolution limits of a 64-pixel MCP-PMT with 10 mm MCP holes, we have achieved a timing resolution of {sigma} {approx} 30ps with single photoelectrons. In this paper we further investigate limits of the timing resolution with this particular detector.
Date: September 12, 2007
Creator: Va'vra, Jaroslav; Benitez, Jorge A.; Leith, David W.G.S.; Mazaheri, Gholamali; Ratcliff, Blair N.; Schwiening, Jochen et al.
Partner: UNT Libraries Government Documents Department

CCpi0 Event Reconstruction at MiniBooNE

Description: We describe the development of a fitter to reconstruct {nu}{sub {mu}} induced Charged-Current single {pi}{sup 0} (CC{pi}{sup 0}) events in an oil Cerenkov detector (CH{sub 2}). These events are fit using a generic muon and two photon extended track hypothesis from a common event vertex. The development of ring finding and particle identification are described. Comparisons between data and Monte Carlo are presented for a few kinematic distributions.
Date: September 1, 2009
Creator: Nelson, Robert H. & U., /Colorado
Partner: UNT Libraries Government Documents Department

Proposal for Research and Development: Vertexing, Tracking, and Data Acquisition for the Bottom Collider Detector

Description: The authors propose a program of research and development into the detector systems needed for a B-physics experiment at the Fermilab p-{bar p} Collider. The initial emphasis is on the critical issues of vertexting, tracking, and data acquisition in the high-multiplicity, high-rate collider environment. R and D for the particle-identification systems (RICH counters, TRD's, and EM calorimeter) will be covered in a subsequent proposal. To help focus their efforts in a timely manner, they propose the first phase of the R and D should culminate in a system test at the C0 collider intersect during the 1990-1991 run: a small fraction of the eventual vertex detector would be used to demonstrate that secondary-decay vertices can be found at a hadron collider. The proposed budget for the r and D program is $800k in 1989, $1.5M in 1990, and $1.6M in 1991.
Date: January 1, 1989
Creator: Castro, H.; Gomez, B.; Rivera, F.; Sanabria, J.-C.; U., /Los Andes; Yager, P. et al.
Partner: UNT Libraries Government Documents Department

The inclusive jet cross section at {radical}s = 630 GeV at D0

Description: The authors present a preliminary measurement of the cross section for central inclusive jet production at {radical}s = 630 GeV using {approximately} 400 nb{sup {minus}1} of data collected during the December 1995 Fermilab collider run at D0. These results are compared to NLO QCD predictions.
Date: September 1, 1996
Creator: Krane, J.
Partner: UNT Libraries Government Documents Department

Searches with taus at the Tevatron

Description: We discuss tau identification techniques at hadron colliders, and present the measurements and the searches performed so far. We report on top quark pair production in the decay channel containing at least one tau lepton. Also, we present results dedicated to searches for new particles, with taus in the final state. We present a search for the charged Higgs boson in the tau decay channel, as well as for the leptoquark family containing tau leptons. Finally, we indicate the capabilities of detecting and triggering on tau leptons in the future collider run.
Date: April 29, 1999
Creator: Gallinaro, M.
Partner: UNT Libraries Government Documents Department

MEGA -- A search for {mu} {r_arrow} e{gamma}

Description: The MEGA experiment is a search for the decay {mu} {r_arrow} e{gamma}. Even though there is no fundamental reason to expect lepton number to be a conserved quantity, processes such as {mu} {r_arrow} e{gamma} have not been observed. (The present upper limit for the branching ratio for {mu} {r_arrow} e{gamma} is 4.9 x 10{sup {minus}11}.) The minimal standard model of electroweak interactions, which is enormously successful, builds in lepton number conservation. However, the decay {mu} {r_arrow} e{gamma} is expected in many extensions to the standard model, in particular in supersymmetry models. The experimental signature for {mu} {r_arrow} e{gamma} from decays at rest is the observation of a positron and photon, each of 52.8 MeV , that are back-to-back, in time coincidence, and originate from a common spatial point. The MEGA detector consists of two spectrometers designed to measure the kinematic characteristics of positrons and photons to search for events with this signature. The primary difficulty in the analysis of these data has been the development of reconstruction algorithms that balance efficiency and resolution. Also, many calibrations and corrections are needed to get optimum resolutions. Most surviving candidate events are accidentals. Results of analysis are given.
Date: December 1, 1998
Creator: Mischke, R. E.
Partner: UNT Libraries Government Documents Department

Panel discussion on the future of hadron spectroscopy

Description: This contribution addresses two of the questions which were submitted to the panel on future developments in light hadron spectroscopy. Specifically, these were the extent to which glueball spectroscopy should be explored and how far it is appropriate to continue experimental studies of the light hadron spectrum. The authors suggest that at a minimum three particular glueball states should be identified, that hybrids should also be identified, and that experiments on hadrons should continue for as long as the theoretical community remains unable to predict their outcome.
Date: December 31, 1995
Creator: Barnes, T.
Partner: UNT Libraries Government Documents Department

Experimental overview of axion searches

Description: Experimental methods to search for the ``invisible axion`` (f{sub a} {much_gt} 250 GeV) are reviewed. The report focuses on the axion-photon coupling, both for laboratory experiments as well as those looking for stellar or cosmologically produced axions. The conclusion is that while the axion-photon mixing in principle would permit laboratory axion searches which are broadband in mass, in fact no such experiment could have the sensitivity to the axion, where m{sub afa} {approx} m{sub {pi}f{pi}}. The only experiments which promise to have any chance to find the axion are the microwave cavity experiments, which presume axions to constitute our galactic halo dark matter. The conversion of axions into a monochromatic microwave signal in a resonant circuit affords the experiment the extraordinary sensitivity required to see the axion, at the expense of being narrow-band in mass, i.e. a tuning experiment. Two such efforts are underway in the world.
Date: June 28, 1995
Creator: van Bibber, K.
Partner: UNT Libraries Government Documents Department

Search for anomalous WW and WZ production at D0

Description: We present a preliminary result from a search for anomalous WW and WZ production in p{bar p} collisions at {radical}s = 1.8 TeV using p{bar p} {yields} e{nu}jj events observed during the 1992-1993 run of the Fermilab Tevatron collider. A fit to the p{sub T} spectrum of W(e{nu}) yields direct limits on the CP-conserving anomalous WW{gamma} and WWZ coupling parameters of -0.89 < {Delta}{kappa} < 1.07 ({lambda} = 0) and -0.66 < {lambda} < 0.67 ({Delta}{kappa} = 0) at the 95% confidence level, assuming that the WWZ coupling parameters are equal to the WW{gamma} coupling parameters, and a form factor scale {Lambda} = 1.5 TeV.
Date: July 1, 1995
Creator: Abachi, S.
Partner: UNT Libraries Government Documents Department

The CDFII time-of-flight detector and impact on beauty flavor tagging

Description: Following the successful RunI from 1992 to 1996, the CDF detector has undergone a major upgrade [1] for the RunII which begun in March 2001. The approval for the addition of a Time-of-Flight detector was granted in January 1999. The installation of the TOF detector was completed in August 2001 and its data has been included in the CDFII readout since then. The primary physics motivation for TOF is to complement and enhance the particle identification capability provided by the central drift chamber (COT) since it distinguishes K{sup {+-}} and {pi}{sup {+-}} in the momentum region of their cross-over in dE=dX. With an expected time-of-flight resolution of 100 ps, the TOF system will be capable of identifying charged kaons from pions by their flight time difference with at least two standard deviation separation up to kaon momenta of 1.6 GeV/c. Such an addition results in an enhancement of the b flavor identification power, crucial to improve the statistical precision in CP violation and B{sub s} mixing measurements.
Date: December 3, 2002
Creator: al., C. Grozis et
Partner: UNT Libraries Government Documents Department

B Decay Studies at SLD

Description: We present three preliminary results from SLD on B decays: an inclusive search for the process b {r_arrow} s gluon, a measurement of the branching ratio for the process B {r_arrow} D{bar D}X, and measurements of the charged and neutral B lifetimes. All three measurements make use of the excellent vertexing efficiency and resolution of the CCD Vertex Detector and the first two make use of the excellent particle identification capability of the Cherenkov Ring Imaging Detector. The b {r_arrow} sg analysis searches for an enhancement of high momentum charged kaons produced in B decays. Within the context of a simple, Jetset-inspired model of b {r_arrow} sg, a limit of B(b {r_arrow} sg) &lt; 7.6% is obtained. The B(B {r_arrow} D{bar D}X) analysis reconstructs two secondary vertices and uses identified charged kaons to determine which of these came from charm decays. The result of the analysis is B(B {r_arrow} D{bar D}X) = (16.2 {+-} 1.9 {+-} 4.2)%. The results of the lifetime analysis are: {tau}{sub B{sup +}} = 1.686 {+-} 0.025 {+-} 0.042 ps, {tau}{sub B{sup 0}} = 1.589 {+-} 0.026 {+-} 0.055 ps and {tau}{sub B{sup +}}/{tau}{sub B{sup 0}} = 1.061 {+-} 0.031/0.029 {+-} 0.027.
Date: March 19, 1999
Creator: Convery, Mark R
Partner: UNT Libraries Government Documents Department

Search for light top squarks with the D{O} detector

Description: We present preliminary results of a search for pair produced top squarks, the supersymmetric partners to the top quark, under the assumption that the two-body decay {bar t}{sub 1} {yields} b{bar W}{sub 1} and three-body decay {bar t}{sub 1} {yields} bW{bar Z}{sub 1} are kinematically forbidden. This scenario is realized if {bar t}{sub 1} is considerably lighter than all other squarks as well as {bar W}{sub 1}, all {bar v}s, and the top quark. Such light top squarks will dominantly decay via {bar t}{sub 1} {yields} c{bar Z}{sub 1} yielding a signal of two acollinear jets with (E){sub T}. The data reported here were taken during the 1992-1993 run of the D0 detector at the Fermilab Tevatron p{bar p} collider operating at {radical}s = 1.8 TeV.
Date: July 1, 1995
Creator: Abachi, S.
Partner: UNT Libraries Government Documents Department

DIRC Dreams: Research Directions for the Next Generation of Internally Reflected Imaging Counters

Description: Some conceptual design features of the total internally reflecting,imaging Cherenkov counter (DIRC) are described. Limits of the DIRC approach to particle identification, and a few features of alternative DIRC designs, are briefly explored.
Date: August 17, 1999
Creator: Ratcliff, Blair N
Partner: UNT Libraries Government Documents Department

The CDF Time of Flight Detector

Description: A new Time of Flight (TOF) detector based on scintillator bars with fine-mesh photomultipliers at both ends has been in operation since 2001 in the CDF experiment. With a design resolution of 100 ps, the TOF can provide separation between K{sup +-} and {pi}{sup +-} in p{bar p} collisions at the 2{omega} level for low momentum, which enhances b flavor tagging capabilities. Because of its very fast response, the TOF is an excellent triggering device, and it is used to trigger on highly ionizing particles, multiple minimum ionizing particles and cosmic rays. Particle identification is achieved by comparing the time-of-flight of the particle measured by the TOF to the time expected for a given mass hypothesis. In order to obtain the resolution necessary for particle ID, optimal calibrations are critical. This paper describes the TOF detector, its calibration procedure, the achieved resolution, the long term operation performances and some of the first results from data analysis using this detector.
Date: January 6, 2004
Creator: al., S. Cabrera et
Partner: UNT Libraries Government Documents Department

An improved Neutrino Oscillations Analysis of the MiniBooNE Data

Description: We calculate the exclusion region in the parameter space of {nu}{sub {mu}} {yields} {nu}{sub e} oscillations of the LSND type using a combined fit to the reconstructed energy distributions of neutrino candidate samples from the MiniBooNE data obtained with two different particle identification methods. The two {nu}{sub e} candidate samples are included together with a high statistics sample of {nu}{sub {mu}} events in the definition of a {chi}{sup 2} statistic which includes the correlations between the energy intervals of all three samples and handles the event overlap between the {nu}{sub e} samples. The {nu}{sub {mu}} sample is introduced to constrain the effect of systematic uncertainties. This analysis increases the exclusion limit in the region {Delta}m{sup 2} {approx}&lt; 1eV{sup 2} when compared with the result previously published by the collaboration, which used a different technique.
Date: January 1, 2008
Creator: Aguilar-Arevalo, Alexis Armando & U., /Columbia
Partner: UNT Libraries Government Documents Department

A 30 ps Timing Resolution for Single Photons with Multi-pixel Burle MCP-PMT

Description: We have achieved {approx}30 psec single-photoelectron and {approx}12ps for multi-photoelectron timing resolution with a new 64 pixel Burle MCP-PMT with 10 micron microchannel holes. We have also demonstrated that this detector works in a magnetic field of 15kG, and achieved a single-photoelectron timing resolution of better than 60 psec. The study is relevant for a new focusing DIRC RICH detector for particle identification at future Colliders such as the super B-factory or ILC, and for future TOF techniques. This study shows that a highly pixilated MCP-PMT can deliver excellent timing resolution.
Date: July 5, 2006
Creator: Va'vra, J.; Benitez, J.; Coleman, J.; Leith, D.W.G.S.; Mazaheri, G.; Ratcliff, B. et al.
Partner: UNT Libraries Government Documents Department

MiniBooNE Neutrino Physics at the University of Alabama

Description: This report summarizes the activities conducted by the UA group under the auspices of the DoE/EPSCoR grant number DE--FG02--04ER46112 since the date of the previous progress report, i.e., since November 2005. It also provides a final report of the accomplishments achieved during the entire period of this grant (February 2004 to January 2007). The grant has fully supported the work of Dr. Yong Liu (postdoctoral research assistant -- in residence at Fermilab) on the MiniBooNE reconstruction and particle identification (PID) algorithms.
Date: April 27, 2007
Creator: Stancu, Ion
Partner: UNT Libraries Government Documents Department

Development of Photon Detectors for a Fast Focusing DIRC

Description: We report progress in developing a Focusing DIRC with very good timing resolution. This basic detector development has been motivated by a possible upgrade of the very successful BaBar DIRC particle identification detector for a future Super B-factory. We have built a single bar full size prototype, which aims to reduce the chromatic error by precise timing, and to remove the effect of bar thickness with a focusing mirror. This paper describes the design of the prototype, and systematic studies of the timing resolution and position response for single photons for two 64-pixel detectors: (a) Hamamatsu Flat Panel PMTs, and (b) Burle MCP-PMTs. To test the prototype, we have developed new electronics for {approx}300 pixels capable of measuring a single electron timing resolution to {approx}100ps. We also report on a first measurement of aging with the MCP-PMT.
Date: September 30, 2005
Creator: Field, C.; Hadig, T.; Leith, David W.G.S.; Mazaheri, G.; Ratcliff, B.; Schwiening, J. et al.
Partner: UNT Libraries Government Documents Department

Search for Lepton Flavour Violating Decays Tau -> l Ks with the BABAR Detector

Description: We present the search for the lepton flavour violating decay {tau} {yields} lK{sup 0}{sub s} with the BaBar experiment data. This process and many other lepton flavour violating {tau} decays, like {tau} {yields} {mu}{gamma} and {tau} {yields} lll, are one of the most promising channel to search for evidence of new physics. According to the Standard Model and the neutrino mixing parameters, branching fractions are estimated well below 10{sup -14}, but many models of new physics allow for branching fractions values close to the present experimental sensitivity. This analysis is based on a data sample of 469fb{sup -1} collected by BABAR detector at the PEP-II storage ring from 1999 to 2007, equivalent to 431 millions of {tau} pairs. the BABAR experiment, initially designed for studying CP violation in B mesons, has demonstrated to be one of the most suitable environments for studying {tau} decays. The tracking system, the calorimeter and the particle identification of BABAR, together with the knowledge of the {tau} initial energy, allow an extremely powerful rejection of background events that, for this analysis, is better than 10{sup -9}. Being {tau} {yields} lK{sup 0}{sub s} a decay mode without neutrinos, the signal {tau} decay can be fully reconstructed. Kinematical constraints are used in a fit that provides a decay tree reconstruction with a high resolution. For this analysis MC simulated events play a decisive role for estimating the signal efficiency and study the residual background. High statistics MC sample are produced simulating detector conditions for different periods of data collection, in order to reduce any discrepancies with the data. When discrepancies can not be removed, we perform studies to compute a correction factor or an estimation of systematic errors that need to be included in the final measurement. A significant improvement of the current result can be reached ...
Date: March 20, 2009
Creator: Cenci, Riccardo
Partner: UNT Libraries Government Documents Department

Time-dependent Dalitz-Plot Analysis of the Charmless Decay B^0 -> K^0S Pi Pi- at BABAR

Description: A time-dependent amplitude analysis of B{sup 0} {yields} K{sub S}{sup 0}{pi}{sup +}{pi}{sup -} decays is performed in order to extract the CP violation parameters of f{sub 0}(980)K{sub S}{sup 0} and {rho}{sup 0}(770)K{sub S}{sup 0} and direct CP asymmetries of K*{sup +}(892){pi}{sup -}. The results are obtained from the final BABAR data sample of (465 {+-} 5)10{sup 6} B{bar B} decays, collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. The time dependent CP asymmetry for f{sub 0}(980)K{sub S}{sup 0} and {rho}{sup 0}(770)K{sub S}{sup 0} are measured to be S(f{sub 0}(980)K{sub S}{sup 0}) = -0.97 {+-} 0.09 {+-} 0.01 {+-} 0.01, and S({rho}{sup 0}(770)K{sub S}{sup 0}) = 0.67 {+-} 0.20 {+-} 0.06 {+-} 0.04, respectively. In decays to K*{sup +}(892){pi}{sup -} the direct CP asymmetry is found to be A{sub CP}(K*{sup {+-}}(892){pi}{sup {-+}}) = -0.18 {+-} 0.10 {+-} 0.04 {+-} 0.00. The relative phases between B{sup 0} {yields} K*{sup +}(892){pi}{sup -} and {bar B}{sup 0} {yields} K*{sup -}(892){pi}{sup +}, relevant for the extraction of the unitarity triangle angle {gamma}, is measured to be {Delta}{phi}(K*(892){pi}) = (34.9 {+-} 23.1 {+-} 7.5 {+-} 4.7){sup o}, where uncertainties are statistical, systematic and model-dependent, respectively. Fit fractions, direct CP asymmetries and the relative phases of different other resonant modes have also been measured. A new method for extracting longitudinal shower development information from longitudinally unsegmented calorimeters is also presented. This method has been implemented as a part of the BABAR final particle identification algorithm. A significant improvement in low momenta muon identification at BABAR is obtained.
Date: October 17, 2009
Creator: Ilic, J
Partner: UNT Libraries Government Documents Department

Study of electron and neutrino interactions. Final report

Description: This is the final report for the DOE-sponsored experimental particle physics program at Virginia Tech to study the properties of the Standard Model of strong and electroweak interactions. This contract (DE-AS05-80ER10713) covers the period from August 1, 1980 to January 31, 1993. Task B of this contract, headed by Professor Alexander Abashian, is described in this final report. This program has been pursued on many fronts by the researchers in a search for axions at SLAC, in electron-positron collisions in the AMY experiment at the TRISTAN collider in Japan, in measurements of muon decay properties in the MEGA and RHO experiments at the LAMPF accelerator, in a detailed analysis of scattering effects in the purported observation of a 17 keV neutrino at Oxford, in a search for a disoriented chiral condensate with the MiniMax experiment at Fermilab, and in an R&D program on resistive plate counters that could find use in low-cost high-quality charged particle detection at low rates.
Date: March 18, 1997
Creator: Abashian, A.
Partner: UNT Libraries Government Documents Department