hepg.ustc.edu.cnSeminarxzb09xzb_ustc_lecture09_

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					STAR Detector

   Introduction
   STAR Detector
       Time Projection Chamber
       EMC, FPD, RICH
       Trigger Detectors
           ZDC, CTB, BBC
   Generic Characteristics of RHIC Event


                     Zhangbu Xu (BNL) USTC lecture
                 RHIC @ Brookhaven
                                  PHOBOS                            BRAHMS
Relativistic
Heavy
                             PHENIX
Ion
                                                         STAR
Collider
                              h




     2 concentric rings of 1740 superconducting magnets
     3.8 km circumference
     counter-rotating beams of ions from p to Au

                                    Zhangbu Xu (BNL) USTC lecture
     RHIC – Runs in 2000 and 2001
                                                                      17 Aug – 2 Oct




Performance (2000)   Au + Au                         Performance (2001)      Au + Au
snn                 130 GeV                         snn                    200 GeV
L [cm-2 s -1 ]       ~ 2 x 1025 (10% design)         L [cm-2 s -1 ]          > 2 x 1025 (>10% design)
*                   5m                               *                     5m2m
# bunches            initially 6, later 56           # bunches               56  112


                                             Zhangbu Xu (BNL) USTC lecture
        Luminosity Calculation in Collider


Van Der Meer Scan
•Absolute Normalization for AA, pp             STAR Preliminary
•Scaling pp, pA, AA



                                                        N N
                                      L  f              1 2
                                       0    2             
                                              Vx Vy
            300m
                                      N     /L
                                          ZDC   0
     Blue/Yellow Beams

                            Zhangbu Xu (BNL) USTC lecture
                    The STAR Collaboration
                                                                            Poland: Warsaw University,
Brazil:   Universidade de Sao                                               Warsaw University of
Paolo                                 Spokesperson: Nu Xu                   Technology
China: IHEP - Beijing, Institute of                                         Russia: MEPHI – Moscow,
Modern Physics, Lanzhou                                                     LPP/LHE JINR–Dubna, IHEP-
IPP – Wuhan,                                                                Protvino
Tsinghua, SINAP, USTC                                                       U.S. Labs: Argonne,
England: University of                                                      Berkeley, Brookhaven National
Birmingham                                                                  Labs

France: SUBATECH – Nantes                                                   U.S. Universities: Arkansas,
                                                                            UC Berkeley, UC Davis,
Institut de Recherches                                                      UCLA, Carnegie Mellon,
Subatomiques,Strasbourg                                                     Creighton, Indiana, Kent
Germany: Max Planck Institute –                                             State, MSU, CCNY, Ohio
Munich University of Frankfurt                                              State, Penn State,
                                                                            Purdue,Rice, Texas A&M,
India: Bhubaneswar, Kolkata,            Countries:     13
Mumbai , Panjab, Rajasthan                                                  UT Austin, Washington,
                                        Institutions:  47                   Wayne State, Yale
                                        Collaborators: 451
                                        Students:      ~50
                                            Zhangbu Xu (BNL) USTC lecture
        A TPC is at the heart of STAR at RHIC
       Magnet                                          Time
                                                       Projection
       Coils                                           Chamber

                                                       Silicon
                                                       Vertex
       TPC                                             Tracker
       Endcap &
       MWPC                                            FTPCs
ZCal                                                               ZCal
       Endcap                                          Vertex
       Calorimeter                                     Position
                                                       Detectors
       Barrel EM                                       Central
       Calorimeter                                     Trigger
                                                       Barrel or
                                                       TOF

                                                       RICH

                       Zhangbu Xu (BNL) USTC lecture
Largest TPC in the World




          Zhangbu Xu (BNL) USTC lecture
     TPC Gas Volume & Electrostatic Field Cage




                             420 CM



   Gas: P10 ( Ar-CH4 90%-10% ) @ 1 atm
   Voltage : - 31 kV at the central membrane        Self supporting Inner Field Cage:
                                                        Al on Kapton using Nomex
              148 V/cm over 210 cm drift path           honeycomb; 0.5% rad length

                                   Zhangbu Xu (BNL) USTC lecture
   Outer and Inner Sectors of the
             Pad Plane
                                                              24 sectors
                                                               (12 on a side)


                                                              Large pads
                                                               good dE/dx
                                                               resolution in the
                                                               Outer sector

                                                              Small pads for
                                                               good two track
                                                               resolution in the
                                                               inner sector
                                                  60 cm

                                                190 cm
        Outer sector              Inner sector
6.2 × 19.5 mm pads       2.85 × 11.5 mm pads
          3940 pads                 1750 pads
                                                       70 Millions readout Channels

                       Zhangbu Xu (BNL) USTC lecture
Cartoon of Signal Collection in TPC




               Zhangbu Xu (BNL) USTC lecture
Pixel Readout of a Pad Plane Sector
              A cosmic ray + delta electron




            Zhangbu Xu (BNL) USTC lecture
STAR Event @ 200GeV




        Zhangbu Xu (BNL) USTC lecture
    Many Small Effects – B, E, Clock, Twist, CM …

                                                                                         Before




                                                        Track Residuals (cm)
                    All calculated distortions
                                                                                        > 200 m

              180

                                                                               Inner
              140                                                              sector
                                                                                        Outer sector
Radius (cm)




              100
                                                                                          After


                                                        Track Residuals (cm)
                                                                                         < 50 m
              60
                      Distortion scale  1.5 mm
              20
               -200    -100      0      100       200
                                                                               Inner
                               Z (cm)                                                   Outer sector
                                                                               sector



                                          Zhangbu Xu (BNL) USTC lecture
Hui Long, Steve Trentelange(UCLA), JT (LBNL)
Offline Particle Identification: dE/dx
                 12
                      Aihong Tang (Kent State U)
                                                                    No calibration          9%
                                                     d              With calibration        7.5%
dE/dx (keV/cm)




                 8                            p
                                     K                              Design                  6.7%

                           
                 4
                       
                      e
                                                                                       Anti - 3He
                 0
                                dE/dx PID range:
                                     ~ 0.7 GeV/c for K/
                                     ~ 1.0 GeV/c for K/p


                                                    Zhangbu Xu (BNL) USTC lecture
Particle ID via Topology & Combinatorics
Secondary vertex:
                          Ks   + +  -                  f  K + + K-            L
 Ks   +  L p + 
 X  L +  W L + K
                           p + -                        r  ++-
 g  e++e-


                                dn/dm                     f from K+ K- pairs
                                                             background
                                                             subtracted



                                                                            m inv
                                dn/dm
                                                                K+ K- pairs
                                                              same event dist.
                                                              mixed event dist.
                   “kinks”
                   K  +                                                  m inv

                          Zhangbu Xu (BNL) USTC lecture
Photon Conversion

       X-Raying Reaction&TPC Material
       1-3% Efficiency




                     TPC




         Zhangbu Xu (BNL) USTC lecture
           Electromagnetic Calorimeter




Leading Particle

                     Zhangbu Xu (BNL) USTC lecture
           Proton Spin




BEMC, EEMC, FPD
                  Zhangbu Xu (BNL) USTC lecture
Zero Degree Calorimeter




                                          Paddles/BBC
           ZDC                                                 ZDC
                              Au          Au

                     Paddles/BBC
                                               Central Multiplicity
                                               Detectors

          Zhangbu Xu (BNL) USTC lecture
       Calibration&Vertexing
… with nuclear excitation
AuAu -> Au*Au*r0




                      STAR




                    5% Central




                             Zhangbu Xu (BNL) USTC lecture
CTB&BBC




          Zhangbu Xu (BNL) USTC lecture
Trigger Timing
                         1. Heart beat: RHIC Clock
                         2. Event Trigger: ZDC, CTB
                         3. L0 Decision: 1.5s
                         4.   L1, L2: 2ms
                         5.   TPC Readout: 2K
                         6.   L3 Online Analysis: 1/100 s
                         7.   DAQ Rate:
                              1. 1 Hz central event (2000)
                              2. 6Hz                 (2001)
                              3. >20Hz               (2002)
                         8.   Data Rate per week:
                              3.6M (30% Eff, 2002)




           Zhangbu Xu (BNL) USTC lecture
        Data Formats
                                                           RAW DATA

   Raw Data:
       Bank Structure
       Word:
        ADC, TIME
   Final Data:
       ROOT BASED
                                                           DST:
       TTree                                              TTree in ROOT
       Track Parameters




                           Zhangbu Xu (BNL) USTC lecture
          Geometry
                              r0
  
r x,  p                       r  r0
                                                 Woods-Saxon distribution
                           1 e            c


                                                     
                       
TAA b   d s  dz1  dz2 r1 s r 2 s  b                     Overlap Integral
                   
           z2

   
TA b   dz r  b, z        
              z1



         
N BC b   pp A2TAA b                         #collisions


                                                         
                                                                AA
N part   b  2 A d s TA s 1  1  TA b  s  pp 
                                                 
                   #interacting nucleons




                                                  Zhangbu Xu (BNL) USTC lecture
Mapping with Data




         Zhangbu Xu (BNL) USTC lecture
Centrality and Participants

                                      HIJING1.35




                                            Glauber Model




          Zhangbu Xu (BNL) USTC lecture
      Geometry from Experiments
                    Paddles/BBC
ZDC                                       ZDC
              Au    Au

      Paddles/BBC
                          Central Multiplicity
                          Detectors
                                                              Paddle signal (a.u.)


                      STAR




                    5% Central




                              Zhangbu Xu (BNL) USTC lecture
       Differential Cross Section
 dN     dN           N count
E 3           
 d p 2pT dpT dy  2pT pT y
 dN     dN           N count
E 3           
 d p 2mT dmT dy  2mT mT y
e mT / T           Exponential
mT e      mT / T
                    Boltzmann
     pT / 2 2
       2            Gaussian
e
Lorentz Invariant Yield per event


                          Zhangbu Xu (BNL) USTC lecture
Summary


   Largest TPC works well
   There are many exciting results
   Additional Capability (MRPC TOF)
   Come and Join STAR
       Hardware
       Analysis


                   Zhangbu Xu (BNL) USTC lecture
Charged hadron pt spectra
130 GeV nucl-ex/0206011                  Preliminary sNN = 200 GeV




                                                   Preliminary sNN = 200 GeV




                   Zhangbu Xu (BNL) USTC lecture
Multiplicity &<pT>




          Zhangbu Xu (BNL) USTC lecture
         ,   K -,   p Spectra
                            pp  uncorrected for trigger bias
                            and vertex finding efficiency

                                                                200 GeV
                                                          Central Au+Au
                                                             Preliminary



                                                                  -

                                                                K-

                                                              p
   p+p: same slope
   AA: different slope

                          Zhangbu Xu (BNL) USTC lecture
Model Predictions I:
ColorGlassCondensate
          Qs2 ~ s(xGA(x, Qs2))/(RA2)
          dNch/d/(RA2)  Qs2/ s
          dNch/d/Npart  1/ s




             Gluon Saturation
Relevant Scale: Qs2dNch/d/(RA2)

                  Zhangbu Xu (BNL) USTC lecture
       Model Predictions II:
       “Soft”+”Hard”
               dNch/d = (1/2) Npartns
                                                   soft
                       + nhNbinjet/in minijet contribution
                                                 hard
        hard
                     Npart: # wound incoming Nucleons

soft                 Nbin: # Interactions of Incoming Nucleons

                p0
                         Zhangbu Xu (BNL) USTC lecture
   Gluon Saturation: Multiplicity
                                            D. Kharzeev, et al., nucl-th/0108006




Multiplicity Comparison: centrality and pseudorapidity dependence

  Model assumes: gluons from initial state directly hadrons

                             Zhangbu Xu (BNL) USTC lecture
   Gluon Saturation: pT Spectra
                                                                Nucl-th/0108048




pT spectra comparison: beam energy and centrality dependence
Works well                                      Saturation model:
                                                J. Schaffner-Bielich, et al. nucl-th/0108048
                                                                      D. Kharzeev, et al. hep-ph/0111315


the <pT> should also reflect the gluon momentum Qs.

                                      Zhangbu Xu (BNL) USTC lecture
Gluon SaturationThermalization?




                              A.H. Mueller QM02

    A different view on the consequences of gluon saturation
                      Zhangbu Xu (BNL) USTC lecture
Universal Particle Production?
     OPAL e+e- PLB94




                                     Universal or not??




                       PHOBOS QM02



                                                           M. Szczekowski PRD 44 (1991) R577



                               Zhangbu Xu (BNL) USTC lecture
          STAR Ring Imaging Cherenkov Detector

   PID for Kaon/Pion/Proton                      C6F14
                                                  Quartz
   1-3 GeV/c for K/                             CH4
   1.5-5 GeV/c for p/anti-p

• C6F14 Liquid Radiator
• CsI Photo Cathode
• MWPC with 16,000 Pads




                               Zhangbu Xu (BNL) USTC lecture
 Trigger Scheme (RICH)

                                                      GAS
             Liquid                                  System
PreTrigger
                                       HV
             RICH      RICH                         SLOW
             TRG      Detector                      Control
                                                              DB
                          Readout
    STAR              RICH                 STAR
   TRIGGER            DAQ                  DAQ            DATA RCF


                       RICH                          ONLINE
                      ONLINE

                          Zhangbu Xu (BNL) USTC lecture

				
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