Hadron Spectra from

Gábor I. Veres / MITfor the

PHOBOS Collaboration

Collaboration

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

PHOBOS Detector System

New trigger systemfor d+Au PID spectra

TOF

TOF

SpecTrig

See poster by C. Henderson and G.V.

pT (GeV/c)0.05 0.5 5.0

Stoppingparticles dE/dx TOF

Particle ID from low to high pT

Eloss (MeV)

dE

/dx

Subm. to PRLnucl-ex/0401006

0.4

0.6

0.8

25

1.2

1.4

20151050

0.2

0

1.0

PHOBOS PID Capabilities

1 2 3 4 50p (GeV/c)

30

40

50

60

70

1/v

(ps

/cm

)

Acceptance for PID Analyses

dE/dx

TOF

K p

pT (

Ge

V/c

)

pT (

Ge

V/c

)

pT (

Ge

V/c

)

d+Au: =Ncoll

/Npart

d

Particle Ratios Using dE/dx PID

Subm. to PRC nucl-ex/030913

See poster by A.A. Bickley

PHOBOS 200 GeV

...p/p Compared to Models

200 GeV

PHOBOS Preliminary

Au+Au: =Ncoll

/(Npart

/2)d+Au: =N

coll/N

partd

Particle Ratios Using dE/dx PID

Subm. to PRC nucl-ex/030913

See poster by A.A. Bickley

PHOBOS 200 GeV

Particle/Antiparticle Ratios using the TOFd+Au

T

Identified pT -spectra in d+Au

Not feed-down corrected

Scale uncertainty: 15%

Particle Composition in d+Au

Not feed-down corrected

Identified mT-spectra in d+Au

Scale uncertainty: 15%m

T=m +p

T

2 2 2

Not feed-down corrected

Identified mT-spectra at 200 GeV

Subm. to PRLnucl-ex/0401006

d+Au

Scale uncertainty: 15%

Not feed-down corrected

Au+Au

Spectra normalized at 2 GeV/c

200 GeV

Comparison: Low Energy d+Au

Cronin, PRD 11, 3105, 1975-0.1< <0.2y

y0.2< <1.2-0.5< <-0.2y

lab=3.26

Not feed-down corrected

d+Au200 GeV

Centrality Dependence of p/h+, p/h-

Centrality dependence

peripheral 40-70% central 0-20%

d+Au200 GeV

Centrality Dependence of p/h+, p/h-

medium 20-40%

Cronin Effect in d+Au vs. Centrality

6% mostcentral Au+AuPRL 91, 072302 (2003)

peripheral

central

PRL 91, 072302 (2003)

Cronin Effect as a Function of (d+Au)

Cronin Effect as a Function of (d+Au)

Evolution of RdAu with

See poster by J.L. Kane

More coming soon...

Summary

● Phobos has PID coverage from 0.05 to 3.5 GeV/c in pT

First PID ratios and spectra from PHOBOS TOF

Surprisingly small centrality dependence of p/p ratios

Approximate mT scaling in d+Au as opposed to Au+Au

Particle composition in d+Au: similar pT-dependence to

lower energy data (but different overall proton fraction) ● Study of -dependence

Exciting new -dependent RdAu values measured

RdAu continuously decreases with