Forward Proton Calorimetry at

Corey Reed / MIT

2003 Fall Meeting of the Division of Nuclear PhysicsOctober 30, 2003

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Collaboration (October 2003)

Birger Back, Mark Baker, Maarten Ballintijn, Donald Barton, Russell Betts, Abigail Bickley,

Richard Bindel, Wit Busza (Spokesperson), Alan Carroll, Zhengwei Chai, Patrick Decowski,

Edmundo García, Tomasz Gburek, Nigel George, Kristjan Gulbrandsen, Stephen Gushue,

Clive Halliwell, Joshua Hamblen, Adam Harrington, Conor Henderson, David Hofman, Richard

Hollis,

Roman Hołyński, Burt Holzman, Aneta Iordanova, Erik Johnson, Jay Kane, Nazim Khan, Piotr

Kulinich, Chia Ming Kuo, Willis Lin, Steven Manly, Alice Mignerey, Gerrit van Nieuwenhuizen,

Rachid Nouicer, Andrzej Olszewski, Robert Pak, Inkyu Park, Heinz Pernegger, Corey Reed,

Michael Ricci,

Christof Roland, Gunther Roland, Joe Sagerer, Iouri Sedykh, Wojtek Skulski, Chadd Smith,

Peter Steinberg, George Stephans, Andrei Sukhanov, Marguerite Belt Tonjes, Adam Trzupek,

Carla Vale, Siarhei Vaurynovich, Robin Verdier, Gábor Veres, Edward Wenger, Frank Wolfs,

Barbara Wosiek, Krzysztof Woźniak, Alan Wuosmaa, Bolek Wysłouch, Jinlong Zhang

ARGONNE NATIONAL LABORATORY BROOKHAVEN NATIONAL LABORATORYINSTITUTE OF NUCLEAR PHYSICS, KRAKOW MASSACHUSETTS INSTITUTE OF TECHNOLOGYNATIONAL CENTRAL UNIVERSITY, TAIWAN UNIVERSITY OF ILLINOIS AT CHICAGO

UNIVERSITY OF MARYLAND UNIVERSITY OF ROCHESTER

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Phobos Detector 2003

mini-pCal

pCal

Two new calorimetersinstalled.

d

Au

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Calorimeter Modules

• Built by E864 (AGS)NIM A406, 227 (1998)

• Lead-scintillator10 cm x 10 cm x 117 cm

• 47x47 fibers / module

• 2 detectors built– Au exit side: 8x11

– d exit side: 2x2

117.0 cm

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Performance

• AGS energy resolution0.38 / sqrt(E (GeV))(single module)

• For our 8x11 array,0.23 / sqrt(E (GeV))

• Tubes very stable overd+Au run

• No evidence of saturation

En

erg

y (

arb

itra

ry u

nit

s)

Shower simulation(top view)

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PCAL Assembly

“Pile on many more layers and I’ll be joining you there.”

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Calibration

• Au-exit side PCAL– Cosmic triggers installed

– Use cosmic rays to calibrate

– Gains vertically symmetric

• d-exit side PCAL– Gains vertically symmetric

– Relative gains horizontally match Au-exit side detector

Cosmic Ray Event in PCAL

Column

Row

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Signal

d

In nucleus rest frame.White circles show neutrons.

Participants

Recoils

Spectators

• Measure recoiling and spectator protons• Use Glauber calculation to get centrality

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Signal

Au ion 100 GeV/c spectator proton 50 GeV/c recoiling proton

Protons bent into calorimeter byRHIC accelerator magnet

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Centrality Measure

• Independent centrality measure

• Correlates well with multiplicity-based measure

• See centrality talks by Richard Hollis and Aneta Iordanova

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PCAL as Crosscheck

• PCAL used as crosscheck in study of systematic errors

• With PCAL centrality, data shows same features

• See talk by Abigail Bickley tomorrow

Preliminary

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Deuteron Side PCAL

• On deuteron exit side:– PCAL finds proton,

ZDC finds nothingn+Au interaction

– PCAL finds nothing,ZDC finds neutronp+Au interaction

• Studies underway

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Deuteron Side PCAL

• Does the selection make sense?– Signal in d-side PCALPeripheral event

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Summary

• New calorimeters added to Phobos

• Detectors working and stable

• Provide centrality information

• Provide information on collision system