1. Zhangbu Xu (BNL) USTC lecture
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

2. Zhangbu Xu (BNL) USTC lecture
Brookhaven
PHOBOS
BRAHMS
Relativistic
Heavy
Ion
Collider
PHENIX
STAR h
Long Island
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

3. Zhangbu Xu (BNL) USTC lecture
RHIC – Runs in 2000 and 2001
17 Aug – 2 Oct
Performance (2001) Au + Au
snn 200 GeV
L [cm-2 s -1 ] > 2 x (>10% design)
* m  2 m
# bunches  112
Performance (2000) Au + Au
snn 130 GeV
L [cm-2 s -1 ] ~ 2 x 1025 (10% design)
* m
# bunches initially 6, later 56
Zhangbu Xu (BNL) USTC lecture

4. Zhangbu Xu (BNL) USTC lecture
Luminosity Calculation in Collider
Van Der Meer Scan
Absolute Normalization for AA, pp
Scaling pp, pA, AA
STAR Preliminary
300m
Blue/Yellow Beams
Zhangbu Xu (BNL) USTC lecture

5. The STAR Collaboration
Poland: Warsaw University, Warsaw University of Technology
Russia: MEPHI – Moscow, LPP/LHE JINR–Dubna, IHEP-Protvino
U.S. Labs: Argonne, Berkeley, Brookhaven National Labs
U.S. Universities: Arkansas, UC Berkeley, UC Davis, UCLA, Carnegie Mellon, Creighton, Indiana, Kent State, MSU, CCNY, Ohio State, Penn State, Purdue,Rice, Texas A&M,
UT Austin, Washington, Wayne State, Yale
Brazil: Universidade de Sao Paolo
China: IHEP - Beijing, Institute of Modern Physics, Lanzhou
IPP – Wuhan, Tsinghua, SINAP, USTC
England: University of Birmingham
France: SUBATECH – Nantes
Institut de Recherches Subatomiques,Strasbourg
Germany: Max Planck Institute – Munich University of Frankfurt
India: Bhubaneswar, Kolkata, Mumbai , Panjab, Rajasthan
Spokesperson: Nu Xu
Countries:
Institutions:
Collaborators: 451
Students: ~50
Zhangbu Xu (BNL) USTC lecture

6. A TPC is at the heart of STAR at RHIC
ZCal
Barrel EM Calorimeter
Endcap Calorimeter
Magnet
Coils
TPC Endcap & MWPC
FTPCs
Vertex Position Detectors
Central Trigger Barrel or TOF
Time Projection Chamber
Silicon Vertex Tracker
RICH
Zhangbu Xu (BNL) USTC lecture

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

8. TPC Gas Volume & Electrostatic Field Cage
420 CM
Gas: P10 ( Ar-CH4 90%-10% ) @ 1 atm
Voltage : kV at the central membrane V/cm over 210 cm drift path
Self supporting Inner Field Cage: Al on Kapton using Nomex honeycomb; 0.5% rad length
Zhangbu Xu (BNL) USTC lecture

9. Outer and Inner Sectors of the Pad Plane
60 cm
190 cm
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
Outer sector
6.2 × 19.5 mm pads
3940 pads
Inner sector
2.85 × 11.5 mm pads
1750 pads
70 Millions readout Channels
Zhangbu Xu (BNL) USTC lecture

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

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

12. Zhangbu Xu (BNL) USTC lecture
STAR 200GeV
Zhangbu Xu (BNL) USTC lecture

13. Many Small Effects – B, E, Clock, Twist, CM …
Outer sector
Inner sector
Track Residuals (cm)
Before > 200 mm
After < 50 mm
All calculated distortions 20 60
100
140
-200
200
-100
180
Z (cm)
Radius (cm)
Distortion scale ± 1.5 mm
Zhangbu Xu (BNL) USTC lecture
Hui Long, Steve Trentelange(UCLA), JT (LBNL)

14. Offline Particle Identification: dE/dx12  K p d e m
dE/dx (keV/cm) 8 4
Aihong Tang (Kent State U)
No calibration
9 %
With calibration
7.5%
Design
6.7%
Anti - 3He
dE/dx PID range:
~ 0.7 GeV/c for K/
~ 1.0 GeV/c for K/p
Zhangbu Xu (BNL) USTC lecture

15. Particle ID via Topology & Combinatorics
Secondary vertex:
Ks  p + p  L p + p
X  L + p  W L + K
g  e++e-
Ks  p + + p - f  K + + K L  p + p r  p + + p -
f from K+ K- pairs
K+ K- pairs
m inv
same event dist.
mixed event dist.
background subtracted
dn/dm
“kinks”
K  + 
Zhangbu Xu (BNL) USTC lecture

16. Zhangbu Xu (BNL) USTC lecture
Photon Conversion
X-Raying Reaction&TPC Material
1-3% Efficiency
TPC
Zhangbu Xu (BNL) USTC lecture

17. Electromagnetic Calorimeter
Leading Particle
Zhangbu Xu (BNL) USTC lecture

18. Zhangbu Xu (BNL) USTC lecture
Proton Spin
BEMC, EEMC, FPD
Zhangbu Xu (BNL) USTC lecture

19. Zero Degree Calorimeter
Paddles/BBC
ZDC Au
Central Multiplicity Detectors
Zhangbu Xu (BNL) USTC lecture

20. Calibration&Vertexing
… with nuclear excitation AuAu -> Au*Au*r0
5% Central
STAR
Zhangbu Xu (BNL) USTC lecture

21. Zhangbu Xu (BNL) USTC lecture
CTB&BBC
Zhangbu Xu (BNL) USTC lecture

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

23. Zhangbu Xu (BNL) USTC lecture
Data Formats
RAW DATA
Raw Data:
Bank Structure
Word: ADC, TIME
Final Data:
ROOT BASED
TTree
Track Parameters
DST:
TTree in ROOT
Zhangbu Xu (BNL) USTC lecture

24. Zhangbu Xu (BNL) USTC lecture
Geometry
Woods-Saxon distribution
Overlap Integral
#collisions
#interacting nucleons A
Zhangbu Xu (BNL) USTC lecture

25. Zhangbu Xu (BNL) USTC lecture
Mapping with Data
Zhangbu Xu (BNL) USTC lecture

26. Centrality and Participants
HIJING1.35
Glauber Model
Zhangbu Xu (BNL) USTC lecture

27. Geometry from Experiments
Paddle signal (a.u.)
Paddles/BBC
ZDC Au
Central Multiplicity Detectors
5% Central
STAR
Zhangbu Xu (BNL) USTC lecture

28. Differential Cross Section
Exponential
Boltzmann
Gaussian
Lorentz Invariant Yield per event
Zhangbu Xu (BNL) USTC lecture

29. 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

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

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

32. Zhangbu Xu (BNL) USTC lecture
p-, K-, p Spectra
pp  uncorrected for trigger bias and vertex finding efficiency
200 GeV Central Au+Au Preliminary p- K- p
p+p: same slope
AA: different slope
Zhangbu Xu (BNL) USTC lecture

33. 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

34. Model Predictions II: “Soft”+”Hard”
dNch/d = (1/2) Npartns soft
+ nhNbinjet/in
hard
minijet contribution
hard
soft
Npart: # wound incoming Nucleons
Nbin: # Interactions of Incoming Nucleons p0
Zhangbu Xu (BNL) USTC lecture

35. Gluon Saturation: Multiplicity
D. Kharzeev, et al., nucl-th/
Multiplicity Comparison: centrality and pseudorapidity dependence
Model assumes: gluons from initial state directly hadrons
Zhangbu Xu (BNL) USTC lecture

36. Gluon Saturation: pT Spectra
Nucl-th/
pT spectra comparison: beam energy and centrality dependence Works well
the <pT> should also reflect the gluon momentum Qs.
Saturation model:
J. Schaffner-Bielich, et al. nucl-th/
D. Kharzeev, et al. hep-ph/
Zhangbu Xu (BNL) USTC lecture

37. Gluon SaturationThermalization?
A.H. Mueller QM02
A different view on the consequences of gluon saturation
Zhangbu Xu (BNL) USTC lecture

38. Universal Particle Production?
OPAL e+e- PLB94
Universal or not??
PHOBOS QM02
M. Szczekowski PRD 44 (1991) R577
Zhangbu Xu (BNL) USTC lecture

39. Zhangbu Xu (BNL) USTC lecture
STAR Ring Imaging Cherenkov Detector
C6F14
CH4
Quartz
PID for Kaon/Pion/Proton
1-3 GeV/c for K/
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

40. Zhangbu Xu (BNL) USTC lecture
Trigger Scheme (RICH)
RICH
Detector
DAQ
Readout
STAR
TRIGGER
TRG
SLOW
Control
Liquid
GAS
System DB
DATA RCF
ONLINE HV
PreTrigger
Zhangbu Xu (BNL) USTC lecture