star detector

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


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


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


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


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


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


Largest TPC in the World


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


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


Cartoon of Signal Collection in TPC


Pixel Readout of a Pad Plane Sector

A cosmic ray + deltaelectron


STAR Event @ 200GeV


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


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)


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 +


Photon Conversion

TPC

X-Raying Reaction&TPC Material1-3% Efficiency


Electromagnetic Calorimeter

Leading Particle


Proton Spin

BEMC, EEMC, FPD


Paddles/BBCZDC ZDC

Au Au

Paddles/BBC Central

Multiplicity Detectors

Zero Degree Calorimeter


Calibration&Vertexing… with nuclear excitation AuAu -> Au*Au*0

5% Central

STAR


CTB&BBC


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)


Data Formats

Raw Data: Bank Structure Word:

ADC, TIME Final Data:

ROOT BASED TTree Track

Parameters

RAW DATA

DST:TTree in ROOT


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


Mapping with Data


Centrality and Participants

HIJING1.35

Glauber Model


Geometry from Experiments

Paddles/BBCZDC ZDC

Au Au

Paddles/BBC Central

Multiplicity Detectors Paddle signal (a.u.)

5% Central

STAR


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


Summary

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

Hardware Analysis


Charged hadron pt spectra

130 GeV nucl-ex/0206011

Preliminary sNN = 200 GeV

Preliminary sNN = 200 GeV


Multiplicity &<pT>


, 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


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


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


Gluon Saturation: Multiplicity

D. Kharzeev, et al., nucl-th/0108006

Multiplicity Comparison: centrality and pseudorapidity dependence

Model assumes: gluons from initial state directly hadrons


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


Gluon SaturationThermalization?

A.H. Mueller QM02

A different view on the consequences of gluon saturation


Universal Particle Production?

M. Szczekowski PRD 44 (1991) R577

PHOBOS QM02

Universal or not??

OPAL e+e- PLB94


• 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


Trigger Scheme (RICH)

RICHDetector

RICHDAQ

Readout

STARTRIGGER

RICHTRG

STARDAQ

SLOW Control

LiquidGAS

System

DB

DATA RCF

ONLINERICHONLINE

HVPreTrigger

star detector

Documents

ohio state

wayne state

penn state

university of birminghamfrance

inner sectors

inner field cage

uc berkeley

au ausnn200 gevl