04/11/2008 Lijuan Ruan (WWND2008) 1

Prototype Performance of Novel Muon TelescopeDetector at STAR

Outline:• Motivation • Simulation

• Intrinsic timing and spatial resolution: Cosmic ray results Beam test results at Fermi-lab

• Detector performance at STAR

• Summary

Lijuan Ruan (for the STAR Collaboration)(Brookhaven National Laboratory)

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The STAR Detector

MagnetMagnet

CoilsCoils

Central Central TriggerTriggerBarrel Barrel (CTB)(CTB)

ZCalZCal

Time Time Projection Projection

ChamberChamber(TPC)(TPC)

Year 2000Year 2000

Barrel EM Cal Barrel EM Cal (BEMC)(BEMC)

Silicon Vertex Silicon Vertex Tracker (SVT)Tracker (SVT)Silicon Strip Silicon Strip Detector (SSD)Detector (SSD)

FTPCFTPCEndcap EM CalEndcap EM CalFPDFPD

TOFp, TOFrTOFp, TOFr

FPDFPD

Year 2001+Year 2001+

PMD

Large acceptance: 2 coverage at mid-rapidity

Future upgrade: Time of Flight, DAQ1000, Heavy Flavor Tracker, Muon Telescope DetectorFuture upgrade: Time of Flight, DAQ1000, Heavy Flavor Tracker, Muon Telescope Detector

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Identify and study the properties of matter with partonic degrees of freedom (flavor, color, sound, temperature …)

Penetrating probes Bulk probes

- “jets” and heavy flavor - v2 partonic collectivity - spectra at low pT, particle ratios.

Electromagnetic probes: - vector meson properties (,e+e-) chiral symmetry restoration - thermal dileptons and photons TQGP

- quarkonia (J/e+e-) color screening

Physics Goals at RHIC

PCM & clust. hadronization

NFD

NFD & hadronic TM

PCM & hadronic TM

CYM & LGT

string & hadronic TM

S.

Bas

s

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Muons: Penetrating Probes A large area of muon telescope detector (MTD) at mid-rapidity, allows for the detection of

• di-muon pairs from QGP thermal radiation, quarkonia, light vector mesons, possible correlations of quarks and gluons as resonances in QGP, and Drell-Yan production • single muons from their semi- leptonic decays of heavy flavor hadrons• advantages over electrons: no conversion, much less Dalitz decay contribution, less affected by radiative losses in the detector materials

Quarkonium dissociation temperatures – Digal, Karsch, Satz

+-

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Concept of Design

A pseudo detector with scintillator covering the whole iron bars and left the gaps in-between uncovered.

1. muon efficiency: 35-45%, pion efficiency: 0.5-1%2. muon-to-pion enhancement factor: 50-1003. muon-to-hadron enhancement factor: 100-1000 including track matching, tof

and dE/dx4. dimuon trigger enhancement factor from online trigger: 10-50 (Guoji Lin, DNP06)

Detection efficiency

pT (GeV)

pionmuon

This together with DAQ1000 will greatly enhance our capability of J/ and other dilepton program in RHIC II and future QCD Lab

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Hadron Rejection at Intermediate pT

pT (GeV) Part of the hits come from the secondary muons from hadron decay. Some can

be removed by using distance of closest approach (DCA) to the vertex on the corresponding track. Guoji Lin, DNP06

Pion efficiency is ~0.5%, pion rejection is about 100 at intermediate pT; Kaons and protons can be rejected by TOF and dE/dx in TPC, hadron rejection is ~300.

π+π-

Detection efficiency

● all hits

○ hits from π

pT (GeV)

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Novel & Compact Muon Detector for QCDLab

• Novel and compact -------- Convention timing, position track segments + fastHits

• Muon is penetrating probe J/ trigger, separate +- states

• QCDLab (RHIC II, eRHIC)

• Works with accelerator high luminosity upgrades

• R & D to address: spatial and time resolution, muon identification capability, trigger capability and hadron rejection power

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Cosmic Ray Results: Long-Strip Multi-gap Resistive Plate Chamber Technology

Long MRPC Technology with double-end readout

HV: 6.3 KV

gas mixture: 95% Freon + 5% isobutane

time resolution: ~60 ps

spatial resolution: ~1cm

efficiency: >95%

950 mm

256

mm

25

mm

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Fermi Lab Beam Test Setup (T963 May 2-15 2007)

TOF1

TOF2

AND Trigger, common start

MWPC1

MWPC2 MWPC5

MWPC4

TOF1

252” 73”

TOF2

72” 164”449”

MRPC1&2

GEMsMWPC3

191”

11”

453381

TOF3

70”

Upper stream

Down stream

C1, C2

Test the performance of two long MRPC modules under different working conditions. Comprehensive scans on HV, gas mixture, position, beam energy, etc … (T963 spokesman: Zhangbu Xu)

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Beam Test Results

HV: 6.3 KV

gas mixture: 95% Freon + 5% isobutane

time resolution: ~60-70 ps

spatial resolution: ~0.6-1cm

efficiency: >95%

consistent with cosmic test results

Tsinghua module as

trigger

Scintillator as trigger

USTC

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STAR-MTD in Year 2007

• iron bars as hadron absorber

• two scintillator trays as our trigger

• 403 cm away from TPC center, ||<0.25

• gas: 95% Freon and 5% iso-butane; HV: 6.3 KV

• MTD Triggered events: 380 K Au+Au events were taken

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Performance at STAR

• MTD hits: matched with real high pT tracks

• z distribution has two components: narrow (muon) and broad (hadron) ones

• spatial resolution (narrow Gaussian) is ~10 cm at pT>2 GeV; hadron rejection: 200-300

• time resolution: 300 ps Improve our electronics with full scale detector

STAR Preliminary

pT>2 GeV/c

STAR Preliminary

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Compared to Simulation

from data: pT>2 GeV/c, (z) of muon: ~10 cm

from simulation: pT=2.5 GeV/c, (z) of muon: ~9 cm

Data and simulation show consistent results

p T (

Ge

V/c

)

z (cm)

muons pions muons

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Muon Identification: dE/dx Effect

STAR Preliminary

n<-1

STAR Preliminary

n>0

• the narrow Gaussian distribution: dominated by muons

STAR Preliminary STAR Preliminary

|z|<20

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• the narrow Gaussian distribution: dominated by muons

Muon Identification: Cut on High Velocity STAR Preliminary

STAR Preliminary

STAR Preliminary

STAR Preliminary

1/trackhits- 1/rawhits >0

n>0

STAR Preliminary

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Simulation: Are Muons Primary?

From simulation: the hits from pion decay seem not to have a narrow Gaussian distribution in z

further investigation by studying the DCA distribution in data and simulation

+ detection efficiency

● all hits

○ hits from π

distance between mc hits and projected hits (cm) pT (GeV)

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Summary and Future Plan • Cosmic and beam tests:

intrinsic timing resolution of long MRPC: ~60-70 ps

spatial resolution: ~1 cm

• The prototype of MTD works at STAR in year 2007. We observed:

---- clear narrow muon peak

---- hadron rejection: 200-300 (requiring track matching)

---- spatial resolution: ~10 cm, consistent with simulation

---- time resolution: ~300 ps

• The possible physics topics to do: electron muon correlation, muon spectra and v2 in run7 (2007) Au+Au collisions at 200 GeV

• The plan: analyze the data in run8 (2008) d+Au and p+p collisions

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Towards the Future at STAR

Current hardware supports at STAR:• HV supply for Long-MRPC: 2 channels from TOF• Low voltage supply for read-out electronic boards: old TOF • Gas system: share with TOF• Gas control computer: share with TOF• DAQ system: trigger, including DSM and 2 CDB• VPD (start time detector): DSM

This set up: run 9 at STAR as well; have a plan to install another tray with TOF electronics

Towards the future:• Collaborators for a proposal of full scale detector

Gas, VPD: share with TOF Electronics: similar to TOF HV, LV: similar to TOF Trigger: DSM and QT Boards

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Novel & Compact Muon Detector for QCDLab

• Novel and compact -------- Convention timing, position track segments + fastHits

• QCDLab (RHIC II, eRHIC)

• Works with accelerator high luminosity upgrades

• Muon is penetrating probe

J/ trigger, separate +- states;

vector meson; thermal dileptons …

STAR Preliminary

n>0

STAR Preliminary