g.j.kunde@yale.edu Pylos June 2002 1

The STAR-RICH Gerd J. Kunde, Yale

Background Transition Performance

Measurements Summary

g.j.kunde@yale.edu Pylos June 2002 2

STAR Au+Au Central Collision at 200 GeV TPC

RICHSTAR-RICH

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The STAR-RICHThe HMPID Prototype

• Device Characteristics– construction– components

• Heavy Ion Environment

• Particle Identification

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Device Characteristics

• Extend PID beyond TPC TOF:

1 < p < 3 GeV/c K 2 < p < 5 GeV/c p

• 160 x 85 cm2 1.2 m2

• Radial Distance of 2.4 m• |y| < 0.2

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Components

• Radiator

– C6F14 Liquid

• Photo Converter– CsI– < 210 (nm)

• Ionization Detector– MWPC pad chamber

– CH4 Gas

80 mm

• Developed by CERN RD-26 in ALICE framework headed by F. Piuz, E. Nappi

• ALICE RICH Prototype Module (1.2 m2)

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STAR-RICH PicturesBari/Cern/Yale STAR-RICH Collaboration

• RICH at CERN : Testbeam Setup in ‘98

• RICH at BNL: Installation into STAR Magnet in ‘99

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Response to BNL Safety Review :-(

• RICH in Aluminum Safety Box

• Buffer Volume N2

• Temperature probes under Slow Control

• Gas detectors have be calibrated to Methane

• Closed Liquid System– Transfer of liquid

under nitrogen• Construction of NEW

LV Distribution Boards made with FR4

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Mechanical Design Completed in ‘99

• RICH• Safety Box with

Nitrogen Flow• 5 o’clock West• Width: 7 Rails• Cables/Tubes in

Trays

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Mechanical Design

• Safety Box – Gas Flow with

Nitrogen– Front Panel– Back Panel

• Thermal Shield– Kinematic Mount

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Gas System • Relative Pressures

Regulated by Bubblers• Chamber

– 2.3 mbar CH4

– 3.1 mbar Ar• Safety Box

– 1.8 mbar

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Gas Requirements and Shipment

• O2 & H2O hazardous to CsI

• Must Deliver Clean Anhydrous Gas

– CH4 Flow Rate of 30 l hr-1

– Ar Purge/Buffer Flow at 60 l hr-1

Exposure Limits Test Allowed Shipment

talk to F. Piuz to hear the fun details

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• CsI Photo-Converter– Vacuum Ultra-Violet (VUV)

• Liquid Radiator

– ~100L of C6F14

– Closed Recirculation/Cleaning– VUV Transparency Monitor

Liquid System

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Liquid System II

• Inert Liquid– Fluoro Inert PF5060DL

• Closed Recirculation System

• Gravity Feed to/from Distribution Rack

• SS Pipes • 3 Overpressure Relief

Valves

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Slow Control

• EPICS– Temperatures– HV-System– LV-System

• Gas System– Alan Bradley PLC– Interlock– EPICS Control

• Liquid System– Siemens PLC

• VME-Scalers

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Electronics• GASSIPLEX CMOS 1.5 m technology

– Charge Pre-amp, Shaper, and Track and Hold Stage– Pad Readout ONLY– 11 bit Dynamic Range .17 fC/channel

• Event Rate allows 700 ns Integration– Multiplexed 16 Analog Channels MCM

• STAR Trigger Rate few Hz• STAR-L0 at 1.8 microseconds !• Fast Clear Logic with Pretrigger !

– Heat Generation • 6mW channel-1 => ~100 W/16k channels

• concern for liquid dn/dT = 5x10-4 oC-1

g.j.kunde@yale.edu Pylos June 2002 17

Photo Electrons

Charged Particles

Pad Chamber

• 2-D Cathode Pad Readout

– 500 nm CsI Layer on Pads

• 8.0 x 8.4 mm2

• 15360k pads

• Dynamic Range

– Single Electron

– MIP detection

– Chamber Stability

– Ambient Pressure :-)

• CH4 Chamber Gas

– Quenching

– High Photo-Electron Emission Efficiency

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Radiator• Liquid C6F14

– Index of Refraction 1.29

– pth = 1.26 mc (GeV/c)

• Match Spectral Sensitivity of CsI

Ring Radii * Proximity Focussing * Normally Incident Tracks

p

K

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Liquid Again

• Oxygen and Water

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Clean Liquid !

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How long it takes to get there ....

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Determination of Cherenkov Angle

• Cern Test Beam Determination– 350 GeV/c -

– Normal Incidence • Resolution– 12.0 mrad single – 3.0 mrad ring average

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Alignment in STAR

• Track Extrapolation drift = 2.7 mm

bend = 3.1 mm

• Near Expected Resolution– 8.0 x 8.4 mm2 pads – 4 mm anode wire pitch– 2 mm anode-cathode

spacing

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The STAR Environment

• Effect of:

– Track Incidence Angle

– Proximity Focussing

Normal Incidence

10o Incidence

20o Incidence

• Ring Azimuth Angles• 180o

• 90o

• 60o

Cherenkov Light is Internally Reflected at an Angle of ~10o

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Golden Event

• Illustrative Example• Separation Possible

– Signal/Background is Large

– Proximity Focussing produces “Rings”

• Both Pion and Kaon Emerge

• Size of MIP and

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Event Characteristics

PeripheralCentral

more central

PixelOccupancy

<5%

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Separation Achieved !

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Number of Photons in Real Analysis

Average Number is limited due to Incident Angle Range

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pbar/p Ratio in STAR p

bar

/p

rati

o

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Summary

• STAR-RICH project has been extremely successful– Prototype RICH Chamber in Operation at STAR– Performance as Expected– Two Successful Physics Runs– Stable Operation over 3 years !

• Particle Identification– Consistent Results– Controlled Systematics– Not just Detector Test but Physics !

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STAR Collaborators/Institutions

Brazil: Universidade de Sao Paolo

China: IHEP - Beijing, IPP - Wuhan

England:

University of Birmingham

France:

Institut de Recherches Subatomiques Strasbourg, SUBATECH - Nantes

Germany:

Max Planck Institute Munich, University of Frankfurt

India: Institute of Physics - Bhubaneswar, VECC

Calcutta, Panjab University - Chandrigrarh, University of Rajasthan - Jaipur, Jammu University, IIT -Bombay

Poland:

Warsaw University, Warsaw University of Technology

Russia:

MEPHI – Moscow, LPP/LHE JINR – Dubna, IHEP - Protvinoh

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

U.S. Labs:

Argonne, Berkeley, and Brookhaven

National Laboratories

~400

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STAR-RICH Collaboration

• Y.Andres1, A.Braem1, M.Calderon2, N.Colonna3, D. Cozza3 , M.Davenport1, L. Dell’Olio3, D. DiBari3, A. DiMauro1, J.C.Dunlop2, D.Elia3, E.Finch4, R.Fini3, D. Fraissard1, B.Ghidini3, B. Goret1, R.Gregory1, J.W.Harris2, M.Horsley2, G.J.Kunde2, B.Lasiuk2, Y. Lescenechal1, R.D.Majka4, P.Martinengo1, A.Morsch1, E.Nappi3, G.Paic1, F.Piuz1, F.Posa3, J.Raynaud1, J.Sandweiss4, J.C.Santiard1, E.Schyns1, N.Smirnov2, S.Stucchi3, G.Tomasicchio3, J. Van Beelen1, T.D. Williams1, Z. Xu4

1 CERN HMPID Group

2 Yale Relativistic Heavy Ion Group

3 Bari HMPID Group

4 Yale High Energy Group

My Personal Special Thanks to F. Piuz !!!!!!!!!!!!