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I. Yu

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DOI: 10.1103/physrevlett.108.191802
2012
Cited 1,635 times
Observation of Reactor Electron Antineutrinos Disappearance in the RENO Experiment
The RENO experiment has observed the disappearance of reactor electron antineutrinos, consistent with neutrino oscillations, with a significance of 4.9 standard deviations. Antineutrinos from six 2.8 GW$_{th}$ reactors at the Yonggwang Nuclear Power Plant in Korea, are detected by two identical detectors located at 294 m and 1383 m, respectively, from the reactor array center. In the 229 day data-taking period between 11 August 2011 and 26 March 2012, the far (near) detector observed 17102 (154088) electron antineutrino candidate events with a background fraction of 5.5% (2.7%). The ratio of observed to expected numbers of antineutrinos in the far detector is $0.920 \pm 0.009({\rm stat.}) \pm 0.014({\rm syst.})$. From this deficit, we determine $\sin^2 2 \theta_{13} = 0.113 \pm 0.013({\rm stat.}) \pm 0.019({\rm syst.})$ based on a rate-only analysis.
DOI: 10.1103/physrevlett.116.211801
2016
Cited 180 times
Observation of Energy and Baseline Dependent Reactor Antineutrino Disappearance in the RENO Experiment
The RENO experiment has analyzed about 500 live days of data to observe an energy dependent disappearance of reactor ν[over ¯]_{e} by comparing their prompt signal spectra measured in two identical near and far detectors. In the period between August of 2011 and January of 2013, the far (near) detector observed 31 541 (290 775) electron antineutrino candidate events with a background fraction of 4.9% (2.8%). The measured prompt spectra show an excess of reactor ν[over ¯]_{e} around 5 MeV relative to the prediction from a most commonly used model. A clear energy and baseline dependent disappearance of reactor ν[over ¯]_{e} is observed in the deficit of the observed number of ν[over ¯]_{e}. Based on the measured far-to-near ratio of prompt spectra, we obtain sin^{2}2θ_{13}=0.082±0.009(stat)±0.006(syst) and |Δm_{ee}^{2}|=[2.62_{-0.23}^{+0.21}(stat)_{-0.13}^{+0.12}(syst)]×10^{-3} eV^{2}.
DOI: 10.1016/j.nima.2012.12.121
2013
Cited 68 times
Production and optical properties of Gd-loaded liquid scintillator for the RENO neutrino detector
Reactor experiment for neutrino oscillation (RENO) began data-taking from August 2011. It successfully observed reactor antineutrino disappearance in April 2012 to measure the smallest mixing angle of θ13. Two identical detectors, one at near location and the other at far location, are constructed at the Yonggwang nuclear power plant in South Korea, to compare the observed reactor neutrino fluxes. Each RENO detector is filled with 16 mass tons of Gadolinium loaded liquid scintillator (GdLS) in the neutrino target region, and with 28 mass tons of unloaded liquid scintillator (LS) in the γ-catcher region surrounding the target. LS was developed to satisfy chemical, physical, optical properties, and safety requirements. Linear alkyl benzene (LAB) was chosen as a solvent because of its high flash-point, sufficient light yield, and being environmentally friendly. GdLS is carefully developed to keep a long attenuation length and high light yield for a long time period. In this paper, we report the characteristics and mass production of the RENO LS and GdLS.
DOI: 10.1016/s0168-9002(02)01274-3
2002
Cited 54 times
Neutron beam test of CsI crystal for dark matter search
We have studied the response of Tl- and Na-doped CsI crystals to nuclear recoils and γ's below 10keV. The response of CsI crystals to nuclear recoil was studied with mono-energetic neutrons produced by the 3H(p,n)3He reaction. This was compared to the response to Compton electrons scattered by 662keV γ-ray. Pulse shape discrimination between the response to these γ's and nuclear recoils was studied, and quality factors were estimated. The quenching factors for nuclear recoils were derived for both CsI(Na) and CsI(Tl) crystals.
DOI: 10.1016/j.nima.2003.11.097
2004
Cited 41 times
A Time-of-Flight detector in CDF-II
A Time-of-Flight (TOF) detector, based on plastic scintillators and fine-mesh photomultipliers, has been added to the Collider Detector at Fermilab (CDF)-II experiment at the Tevatron pp̄ collider. The primary physics motivation is to provide charged kaon identification to improve neutral B meson flavor determination. Besides that, the TOF detector found application in the CDF trigger system in implementation of highly ionizing particle, high multiplicity and cosmic rays triggers.
DOI: 10.1103/physrevlett.125.191801
2020
Cited 14 times
Search for Sub-eV Sterile Neutrinos at RENO
We report a search result for a light sterile neutrino oscillation with roughly 2200 live days of data in the RENO experiment. The search is performed by electron antineutrino (ν¯e) disappearance taking place between six 2.8 GWth reactors and two identical detectors located at 294 m (near) and 1383 m (far) from the center of the reactor array. A spectral comparison between near and far detectors can explore reactor ν¯e oscillations to a light sterile neutrino. An observed spectral difference is found to be consistent with that of the three-flavor oscillation model. This yields limits on sin22θ14 in the 10−4≲|Δm412|≲0.5 eV2 region, free from reactor ν¯e flux and spectrum uncertainties. The RENO result provides the most stringent limits on sterile neutrino mixing at |Δm412|≲0.002 eV2 using the ν¯e disappearance channel.Received 16 June 2020Revised 8 October 2020Accepted 9 October 2020DOI:https://doi.org/10.1103/PhysRevLett.125.191801Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasNeutrino oscillationsPhysical SystemsNeutrinosSterile neutrinosTechniquesNeutrino detectorsParticle mixing & oscillationsScintillatorsParticles & Fields
DOI: 10.48550/arxiv.2404.04153
2024
Evaluation of the performance of the event reconstruction algorithms in the JSNS$^2$ experiment using a $^{252}$Cf calibration source
JSNS$^2$ searches for short baseline neutrino oscillations with a baseline of 24~meters and a target of 17~tonnes of the Gd-loaded liquid scintillator. The correct algorithm on the event reconstruction of events, which determines the position and energy of neutrino interactions in the detector, are essential for the physics analysis of the data from the experiment. Therefore, the performance of the event reconstruction is carefully checked with calibrations using $^{252}$Cf source. This manuscript describes the methodology and the performance of the event reconstruction.
DOI: 10.1016/j.nima.2024.169400
2024
CMS iRPC FEB development and validation
In view of the High Luminosity upgrade of the CERN LHC, the forward CMS Muon spectrometer will be extended with two new stations of improved Resistive Plate Chambers (iRPC) covering the pseudorapidity range from 1.8 to 2.4. Compared to the present RPC system, the gap thickness is reduced to lower the avalanche charge, and an innovative 2D strip readout geometry is proposed. These improvements will allow iRPC detector to cope with higher background rates. A new Front-End-Board (FEB) is designed to readout iRPC signals with a threshold as low as 30 fC and an integrated Time Digital Converter with a resolution of 30 ps. In addition, the communication bandwidth is significantly increased by using optical fibers. The history, final design, certification, and calibration of this FEB are presented.
DOI: 10.1016/s0168-9002(02)01512-7
2002
Cited 21 times
The CDF-II time-of-flight detector
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 pp̄ collisions. With a design resolution goal of about 100ps, separation between charged kaons and pions is expected at the 2 sigma level for momenta below 1.6GeV/c, which enhances CDF's b-flavor tagging capabilities. We 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.
DOI: 10.48550/arxiv.1705.08629
2017
Cited 9 times
Technical Design Report (TDR): Searching for a Sterile Neutrino at J-PARC MLF (E56, JSNS2)
In this document, the technical details of the JSNS$^2$ (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) experiment are described. The search for sterile neutrinos is currently one of the hottest topics in neutrino physics. The JSNS$^2$ experiment aims to search for the existence of neutrino oscillations with $\Delta m^2$ near 1 eV$^2$ at the J-PARC Materials and Life Science Experimental Facility (MLF). A 1 MW beam of 3 GeV protons incident on a spallation neutron target produces an intense neutrino beam from muon decay at rest. Neutrinos come predominantly from $\mu^+$ decay: $\mu^{+} \to e^{+} + \bar{\nu}_{\mu} + \nu_{e}$. The experiment will search for $\bar{\nu}_{\mu}$ to $\bar{\nu}_{e}$ oscillations which are detected by the inverse beta decay interaction $\bar{\nu}_{e} + p \to e^{+} + n$, followed by gammas from neutron capture on Gd. The detector has a fiducial volume of 17 tons and is located 24 meters away from the mercury target. JSNS$^2$ offers the ultimate direct test of the LSND anomaly. In addition to the sterile neutrino search, the physics program includes cross section measurements with neutrinos with a few 10's of MeV from muon decay at rest and with monochromatic 236 MeV neutrinos from kaon decay at rest. These cross sections are relevant for our understanding of supernova explosions and nuclear physics.
DOI: 10.1016/s0168-9002(00)01305-x
2001
Cited 15 times
Design and performance tests of the CDF time-of-flight system
Abstract The CDF II detector contains a time-of-flight detector consisting of 216 scintillator bars of 279 cm length and 4×4 cm2 cross-section located at a radius of 138 cm from the beam axis. The bars are installed on the inner surface of the CDF solenoid, which produces an axial field of 1.4 T. Nineteen-stage fine-mesh photomultiplier tubes are attached at both ends of the scintillator bars. Photostatistics limit the time-of-flight resolution, which is expected to be 100 ps. The primary physics motivation is K± identification for improved neutral B meson flavor determination.
DOI: 10.1088/1748-0221/16/11/p11014
2021
Cited 4 times
Performance of a triple-GEM demonstrator in pp collisions at the CMS detector
After the Phase-2 high-luminosity upgrade to the Large Hadron Collider (LHC), the collision rate and therefore the background rate will significantly increase, particularly in the high $\eta$ region. To improve both the tracking and triggering of muons, the Compact Muon Solenoid (CMS) Collaboration plans to install triple-layer Gas Electron Multiplier (GEM) detectors in the CMS muon endcaps. Demonstrator GEM detectors were installed in CMS during 2017 to gain operational experience and perform a preliminary investigation of detector performance. We present the results of triple-GEM detector performance studies performed in situ during normal CMS and LHC operations in 2018. The distribution of cluster size and the efficiency to reconstruct high $p_T$ muons in proton--proton collisions are presented as well as the measurement of the environmental background rate to produce hits in the GEM detector.
2020
Cited 4 times
Search for sterile neutrino oscillation using RENO and NEOS data
We present a reactor model independent search for sterile neutrino oscillation using 2\,509\,days of RENO near detector data and 180 days of NEOS data. The reactor related systematic uncertainties are significantly suppressed as both detectors are located at the same reactor complex of Hanbit Nuclear Power Plant. The search is performed by electron antineutrino\,($\overline{\nu}_e$) disappearance between six reactors and two detectors with baselines of 294\,m\,(RENO) and 24\,m\,(NEOS). A spectral comparison of the NEOS prompt-energy spectrum with a no-oscillation prediction from the RENO measurement can explore reactor $\overline{\nu}_e$ oscillations to sterile neutrino. Based on the comparison, we obtain a 95\% C.L. excluded region of $0.1<|\Delta m_{41}^2|<7$\,eV$^2$. We also obtain a 68\% C.L. allowed region with the best fit of $|\Delta m_{41}^2|=2.41\,\pm\,0.03\,$\,eV$^2$ and $\sin^2 2\theta_{14}$=0.08$\,\pm\,$0.03 with a p-value of 8.2\%. Comparisons of obtained reactor antineutrino spectra at reactor sources are made among RENO, NEOS, and Daya Bay to find a possible spectral variation.
DOI: 10.1016/s0920-5632(00)01132-4
2001
Cited 8 times
The time of flight detector at CDF
A Time-of-Flight detector (TOF) has been incorporated into the CDF-II experiment in order to provide charged kaon identification to improve neutral B meson flavor determination. With an expected time-of-flight resolution of 100 ps, the system will be able to provide 2 standard deviation separation between K± and π± for momenta p < 1.6 GeV/c, complementing the specific ionization energy loss dE/dx measured with the new drift chamber.
DOI: 10.1016/j.nima.2023.168266
2023
RPC background studies at CMS experiment
During Run2 the high instantaneous luminosity, up to 2.21034cm−2s−1, lead to a substantial hit rate in the Compact Muon Solenoid experiment’s muon chambers due to multiple background sources to physics processes sought for at LHC. In this article we will describe the analysis method devised to measure and identify the contributions to such background in the Resistive Plate Chambers. Thorough understanding of the background rates provides the base for the upgrade of the muon detectors for the High-Luminosity LHC.
DOI: 10.1142/s0217751x01009077
2001
Cited 5 times
A TIME-OF-FLIGHT DETECTOR FOR CDF
A Time-of-Flight detector (TOF), with a technique based on plastic scintillators and finemesh photomultipliers, has been added to the CDF-II experiment. The main physics motivation is to improve neutral B meson flavor determination by K ± identification. The expected time resolution is 100 ps, which provides at least two standard deviations separation between K ± and π ± for momenta p &lt; 1.6 Gev/cand better than 1.2 standard deviations separation over all momenta when combining TOF identification with dE/dx identification using the new drift chamber.
DOI: 10.1088/1748-0221/15/09/t09002
2020
The JSNS<sup>2</sup> data acquisition system
The JSNS2 (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) experiment aims to search for neutrino oscillations over a 24 m short baseline at J-PARC. The JSNS2 inner detector is filled with 17 tons of gadolinium(Gd)-loaded liquid scintillator (LS) with an additional 31 tons of unloaded LS in the intermediate γ-catcher and an optically separated outer veto volumes. A total of 120 10-inch photomultiplier tubes observe the scintillating optical photons and each analog waveform is stored with flash analog-to-digital converters. We present details of the data acquisition, processing, and data quality monitoring system. We also present two different trigger logics which are developed for the beam and self-trigger.
DOI: 10.48550/arxiv.1609.09483
2016
In-Situ Measurement of Relative Attenuation Length of Gadolinium-Loaded Liquid Scintillator Using Source Data at RENO Experiment
We present in situ measurements of the relative attenuation length of the gadolinium loaded liquid scintillator in the RENO (Reactor Experiment Neutrino Oscillation) detectors using radioactive source calibration data. We observed a steady decrease in the attenuation length of the Gd-LS in the RENO detectors by 50% in about four years since the commissioning of the detectors.
2013
International Journal of Interventional Cardioangiology
DOI: 10.3938/jkps.58.1101
2011
Simulation Studies of a Pixel-type 3-D Silicon Sensor
DOI: 10.1007/s41605-022-00340-6
2022
R &amp;D of back-end electronics for improved resistive plate chambers for the phase 2 upgrade of the CMS end-cap muon system
The Large Hadron Collider (LHC) at European Organization for Nuclear Research is planned to be upgraded to the high luminosity LHC. Increasing the luminosity makes muon triggering reliable and offline reconstruction very challenging. To enhance the redundancy of the Compact Muon Solenoid (CMS) Muon system and resolve the ambiguity of track reconstruction in the forward region, an improved Resistive Plate Chamber (iRPC) with excellent time resolution will be installed in the Phase-2 CMS upgrade. The iRPC will be equipped with Front-End Electronics (FEE), which can perform high-precision time measurements of signals from both ends of the strip. New Back-End Electronics (BEE) need to be researched and developed to provide sophisticated functionalities such as interacting with FEE with shared links for fast, slow control (SC) and data, in addition to trigger primitives (TPs) generation and data acquisition (DAQ). The BEE prototype uses a homemade hardware board compatible with the MTCA standard, the back-end board (BEB). BEE interacts with FEE via a bidirectional 4.8 Gbps optical paired-link that integrates clock, data, and control information. The clock and fast/slow control commands are distributed from BEB to the FEE via the downlink. The uplink is used for BEB to receive the time information of the iRPC’s fired strips and the responses to the fast/slow control commands. To have a pipelined detector data for cluster finding operation, recover (DeMux) the time relationship of which is changed due to the transmission protocol for the continuous incoming MUXed data from FEE. Then at each bunch crossing (BX), clustering fired strips that satisfy time and spatial constraints to generate TPs. Both incoming raw MUXed detector data and TPs in a time window and latency based on the trigger signal are read out to the DAQ system. Gigabit Ethernet (GbE) of SiTCP and commercial 10-GbE are used as link standards for SC and DAQ, respectively, for the BEB to interact with the server. The joint test results of the BEB with iRPC and Front-End Board (FEB) show a Bit Error Rate of the transmission links less than $$1\times {10^{-16}}$$ , a time resolution of the FEB Time-to-Digital Converter of 16 ps, and the resolution of the time difference between both ends of 160 ps which corresponding a spatial resolution of the iRPC of approximately 1.5 cm. Test results showed the correctness and stable running of the BEB prototype, of which the functionalities fulfill the iRPC requirements.
DOI: 10.5281/zenodo.1286848
2018
Recent Results from RENO
DOI: 10.1109/tap.1971.1139981
1971
Modification of scattered field of long wire by multiple impedance loading
By loading a long wire with several impedances, the scattered field of the wire may be changed so that a more desirable scattering pattern is obtained. A simple design procedure and formulas relevant to this method are presented.
DOI: 10.48550/arxiv.1911.04601
2019
Observation of Reactor Antineutrino Disappearance Using Delayed Neutron Capture on Hydrogen at RENO
The Reactor Experiment for Neutrino Oscillation (RENO) experiment has been taking data using two identical liquid scintillator detectors of 44.5 tons since August 2011. The experiment has observed the disappearance of reactor neutrinos in their interactions with free protons, followed by neutron capture on hydrogen. Based on 1500 live days of data taken with 16.8 GW$_{th}$ reactors at the Hanbit Nuclear Power Plant in Korea, the near (far) detector observes 567690 (90747) electron antineutrino candidate events with a delayed neutron capture on hydrogen. This provides an independent measurement of $\theta_{13}$ and a consistency check on the validity of the result from n-Gd data. Furthermore, it provides an important cross-check on the systematic uncertainties of the n-Gd measurement. Based on a rate-only analysis, we obtain sin$^{2}$2$\theta _{13}$= 0.087 $\pm$ 0.008 (stat.) $\pm$ 0.014 (syst.).
DOI: 10.1093/ptep/ptab044
2021
Slow control and monitoring system at the JSNS2
Abstract The Sterile Neutrino Search at the J-PARC Spallation Neutron Source (JSNS$^2$) experiment aims to search for sterile neutrino oscillations using a neutrino beam from muon decays at rest. The JSNS$^2$ detector contains 17 tons of 0.1$\%$ gadolinium (Gd) loaded liquid scintillator (LS) as a neutrino target. Detector construction was completed in the spring of 2020. A slow control and monitoring system (SCMS) was implemented for reliable control and quick monitoring of the detector operational status and environmental conditions. It issues an alarm if any of the monitored parameters exceed a preset acceptable range. The SCMS monitors the high voltage of the photomultiplier tubes, the LS level in the detector, possible LS overflow and leakage, the temperature and air pressure in the detector, the humidity of the experimental hall, and the LS flow rate during filling and extraction. An initial 10 days of data-taking with a neutrino beam was done following a successful commissioning of the detector and SCMS in 2020 June. In this paper, we present a description of the assembly and installation of the SCMS and its performance.
2005
CERN beam test of silicon-tungsten calorimeter test module
DOI: 10.1109/nssmic.2001.1009707
2001
The CDF-II time-of-flight detector system
A Time-of-Flight detector (TOF) has been added to the CDF-II experiment to provide charged kaon identification primarily for neutral B meson flavor determination. With its expected 100 ps time-of-flight resolution, the TOF system will be able to provide at least two standard deviation separation between K/sup /spl plusmn// and /spl pi//sup /spl plusmn// for momenta p < 1.6 GeV/c, complementing the specific ionization energy loss, dE/dx, measured in the new drift chamber. This paper describes the TOF detector and reports on the initial performance based on the data collected by the CDF-II so far.
2011
ПРЕДИКТОРЫ СОЦИАЛИЗАЦИИ ИНВАЛИДОВ ПРИ БОЛЕЗНЯХ СИСТЕМЫ КРОВООБРАЩЕНИЯ
Information literacy for an active and ef fective citizenship: White paper prepared for Unesco, the US National Commission on Libraries and Informa-tion Science and the National Forum on Information Literacy, for use at the Information Literacy Meeting of experts. Prague, 2002. URL: http://www.nclis.gov/libinter/infolitconf&meet/papers/correiafullpaper. (дата обращения: 17.02.2010).
DOI: 10.1002/pmic.201370123
2013
Contents: Proteomics 13'15
PROTEOMICSVolume 13, Issue 15 ContentsFree Access Contents: Proteomics 13'15 First published: 02 August 2013 https://doi.org/10.1002/pmic.201370123AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Volume13, Issue15August 2013 RelatedInformation
DOI: 10.48550/arxiv.2006.00670
2020
The JSNS$^{2}$ data acquisition system
The JSNS$^{2}$ (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) experiment aims to search for neutrino oscillations over a 24 m short baseline at J-PARC. The JSNS$^{2}$ inner detector is filled with 17 tons of gadolinium(Gd)-loaded liquid scintillator (LS) with an additional 31 tons of unloaded LS in the intermediate $\gamma$-catcher and an optically separated outer veto volumes. A total of 120 10-inch photomultiplier tubes observe the scintillating optical photons and each analog waveform is stored with the flash analog-to-digital converters. We present details of the data acquisition, processing, and data quality monitoring system. We also present two different trigger logics which are developed for the beam and self-trigger.
DOI: 10.1109/nssmic.2003.1352035
2003
The CDF time of flight detector
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 /spl plusmn// and /spl pi//sup /spl plusmn// in pp~ collisions at the 2/spl sigma/ 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.
DOI: 10.2172/1422808
1996
Measurement of $b\bar{b}$ Production Correlations, $B^0 \bar{B}^0$ Mixing, and a Limit on the CP Violating Parameter $\epsilon_B$ in $p\bar{p}$ Collisions at CDF
In $p\bar{p}$ collisions at $\sqrt{s}$ = 1.8 TeV, $b\bar{b}$ quark pairs are produced with a significant cross section. High momentum muons from semileptonic decays of bottom quarks can provide a data set for the studies of $b\bar{b}$ physics. Muons from bottom decays are distinguishable from others by their displaced trajectories resulting from the long lifetimes of bottom hadrons. In this thesis, we have presented a measurement of correlated $b\bar{b}$ cross-sections, $\mu - \mu$, correlations, and the average $B^O \bar{B}^0$ mixing parameter $\bar{X}$, and a limit on the CP violating parameter $\epsilon_B$, using dimuon events from $b\bar{b}$ double semileptonic decays. The data used were taken with the CDF detector during the 1992-1993 run of the Fermilab Tevatron and represent an integrated luminosity of 17.4 ± 0.6 $pb^{-1}$. The results concerning $b\bar{b}$ production correlations are compared to predictions of next-to-leading (NLO) order QCD computations. The normalization of the bb cross section is found to be higher than the theory prediction, which could be explained by adjusting the QCD input parameters. The distributions of the azimuthal opening angle and the muon transverse momentum obtained from the studies of $\mu - \mu$, correlations show reasonable agreement between data and NLO QCD theory. A comparison between the number of $b\bar{b}$ events with like-sign and opposite-sign dimuons yields a value of the $B^O \bar{B}^0$ mixing parameter X = 0.131 ± 0.020(stat) ± O.016(sys). In addition, the asymmetry between the number of $\mu^+ \mu+$ and $\mu^+\mu^+$,events is used to place a limit on the real part of $\epsilon_B$ which gives rise to CP violation in $B^O \bar{B}^0$ mixing.
1995
A measurement of b{bar b} production correlations using low-p{sub T} dimuons at CDF
The authors present a measurement of the b{bar b} cross section at the CDF detector from the 1992-1993 run of the Tevatron Collider using the dual semimuonic decay of b{bar b} pair. For the study of kinematic correlations, the cross section has been measured for P{sub T}(b1) > 6.5 GeV, 7.5 GeV, amd 8.75 GeV and P{sub T} > 6.5 GeV. The authors have reduced the systematic error of the measurement with the improved tracking resolution with newly installed silicon vertex detector. By studying the charge correlations between like-sign and unlike-sign dimuons, the average B{bar B} mixing parameter has also been measured.