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
Jan 11, 2016
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
RHIC @ Brookhaven
h
Long Island
Long Island
Relativistic
Heavy
Ion
Collider
2 concentric rings of 1740 superconducting magnets 3.8 km circumference counter-rotating beams of ions from p to Au
STAR
PHENIX
PHOBOS BRAHMS
Zhangbu Xu (BNL) USTC lecture
RHIC – Runs in 2000 and 2001
Performance (2000) Au + Au
snn 130 GeV
L [cm-2 s -1 ]~ 2 x 1025 (10% design)
* 5 m
# bunches initially 6, later 56
Performance (2001) Au + Au
snn 200 GeV
L [cm-2 s -1 ]> 2 x 1025 (>10% design)
* 5 m 2 m
# bunches 56 112
17 Aug – 2 Oct
Zhangbu Xu (BNL) USTC lecture
0/
221
0
LZDC
N
VyVx
NNfL
Van Der Meer Scan•Absolute Normalization for AA, pp•Scaling pp, pA, AA
STAR Preliminary
Luminosity Calculation in Collider
300m
Blue/Yellow Beams
Zhangbu Xu (BNL) USTC lecture
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
Countries: 13Institutions: 47Collaborators: 451 Students: ~50
Spokesperson: Nu Xu
Zhangbu Xu (BNL) USTC lecture
A TPC is at the heart of STAR at RHIC
ZCal
Barrel EM Calorimeter
Endcap Calorimeter
Magnet
Coils
TPC Endcap & MWPC
ZCal
FTPCs
Vertex Position Detectors
Central Trigger Barrel or TOF
Time Projection Chamber
Silicon Vertex Tracker
RICH
Zhangbu Xu (BNL) USTC lecture
Largest TPC in the World
Zhangbu Xu (BNL) USTC lecture
TPC Gas Volume & Electrostatic Field Cage
Gas: P10 ( Ar-CH4 90%-10% ) @ 1 atm Voltage : - 31 kV at the central membrane
148 V/cm over 210 cm drift path
420 CM
Self supporting Inner Field Cage: Al on Kapton using Nomex honeycomb; 0.5% rad length
Zhangbu Xu (BNL) USTC lecture
60 cm
190 cm
Outer sector6.2 × 19.5 mm pads
3940 pads
Inner sector2.85 × 11.5 mm pads
1750 pads
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
70 Millions readout Channels
Outer and Inner Sectors of the Pad Plane
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 + deltaelectron
Zhangbu Xu (BNL) USTC lecture
STAR Event @ 200GeV
Zhangbu Xu (BNL) USTC lecture
Many Small Effects – B, E, Clock, Twist,
CM …
Hui Long, Steve Trentelange(UCLA), JT (LBNL)
All calculated distortions
20
60
100
140
-200 2000-100 100
180
Z (cm)
Rad
ius
(cm
)
Distortion scale 1.5 mm
Outer sectorInner sector
Tra
ck R
esid
ual
s (c
m) Before
> 200 m
Inner sector
Outer sector
Tra
ck R
esid
ual
s (c
m) After
< 50 m
Zhangbu Xu (BNL) USTC lecture
Offline Particle Identification: dE/dx
No calibration 9 %
With calibration 7.5%
Design 6.7%
12
Kp
d
edE
/dx
(keV
/cm
)
0
8
4
Anti - 3He
dE/dx PID range:
~ 0.7 GeV/c for K/
~ 1.0 GeV/c for K/p
Aihong Tang (Kent State U)
Zhangbu Xu (BNL) USTC lecture
Particle ID via Topology & Combinatorics
Secondary vertex: Ks + p + + + K e++e-
Ks + + - K + + K- p + - + + -
from K+ K- pairs
K+ K- pairs
m inv
m inv
same event dist.mixed event dist.
background subtracted
dn/dm
dn/dm
“kinks”
K +
Zhangbu Xu (BNL) USTC lecture
Photon Conversion
TPC
X-Raying Reaction&TPC Material1-3% Efficiency
Zhangbu Xu (BNL) USTC lecture
Electromagnetic Calorimeter
Leading Particle
Zhangbu Xu (BNL) USTC lecture
Proton Spin
BEMC, EEMC, FPD
Zhangbu Xu (BNL) USTC lecture
Paddles/BBCZDC ZDC
Au Au
Paddles/BBC Central
Multiplicity Detectors
Zero Degree Calorimeter
Zhangbu Xu (BNL) USTC lecture
Calibration&Vertexing… with nuclear excitation AuAu -> Au*Au*0
5% Central
STAR
Zhangbu Xu (BNL) USTC lecture
CTB&BBC
Zhangbu Xu (BNL) USTC lecture
Trigger Timing1. Heart beat: RHIC Clock2. Event Trigger: ZDC, CTB3. L0 Decision: 1.5s4. L1, L2: 2ms5. TPC Readout: 2K6. L3 Online Analysis: 1/100 s7. 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: Bank Structure Word:
ADC, TIME Final Data:
ROOT BASED TTree Track
Parameters
RAW DATA
DST:TTree in ROOT
Zhangbu Xu (BNL) USTC lecture
Geometry
0
0,1
r rc
x pe
Woods-Saxon distribution
1 2 1 2AAT b d s dz dz s s b
Overlap Integral
2BC pp AAN b A T b
2 1 1A
part A A ppN b A d s T s T b s
2
1
,z
A
z
T b dz b z
#collisions
#interacting nucleons
A
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/BBCZDC ZDC
Au Au
Paddles/BBC Central
Multiplicity Detectors Paddle signal (a.u.)
5% Central
STAR
Zhangbu Xu (BNL) USTC lecture
Differential Cross Section
22 2/
/
/
3
3
22
22
T
T
T
p
TmT
Tm
TT
count
TT
TT
count
TT
e
em
e
ymm
N
dydmm
dN
pd
dNE
ypp
N
dydpp
dN
pd
dNE
Lorentz Invariant Yield per event
ExponentialBoltzmannGaussian
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
200 GeVCentral Au+Au
Preliminary
p
-
K-
p+p: same slope AA: different slope
pp uncorrected for trigger bias and vertex finding efficiency
Zhangbu Xu (BNL) USTC lecture
Model Predictions I: ColorGlassCondensate
Qs2 ~ s(xGA(x, Qs
2))/(RA2)
dNch/d/(RA2) Qs
2/ s
dNch/d/Npart 1/ s
Relevant Scale: Qs2dNch/d/(RA
2)
Gluon Saturation
Zhangbu Xu (BNL) USTC lecture
Model Predictions II:
“Soft”+”Hard”
dNch/d = (1/2) Npartns soft
+ nhNbinjet/in
hard
hard
soft
p0
minijet contribution
Npart: # wound incoming Nucleons
Nbin: # Interactions of Incoming Nucleons
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 dependenceWorks well
the <pT> should also reflect the gluon momentum Qs.
Saturation model:J. Schaffner-Bielich, et al. nucl-th/0108048D. Kharzeev, et al. hep-ph/0111315
Zhangbu Xu (BNL) USTC lecture
Gluon SaturationThermalization?
A.H. Mueller QM02
A different view on the consequences of gluon saturation
Zhangbu Xu (BNL) USTC lecture
Universal Particle Production?
M. Szczekowski PRD 44 (1991) R577
PHOBOS QM02
Universal or not??
OPAL e+e- PLB94
Zhangbu Xu (BNL) USTC lecture
• C6F14 Liquid Radiator
• CsI Photo Cathode
• MWPC with 16,000 Pads
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
Zhangbu Xu (BNL) USTC lecture
Trigger Scheme (RICH)
RICHDetector
RICHDAQ
Readout
STARTRIGGER
RICHTRG
STARDAQ
SLOW Control
LiquidGAS
System
DB
DATA RCF
ONLINERICHONLINE
HVPreTrigger