anti-particle to particle ratios in cu+cu collisions @ rhic vasundhara chetluru university of...
TRANSCRIPT
Anti-particle to Particle Ratios in Cu+Cu Collisions @ RHIC
Vasundhara Chetluru
University of Illinois, Chicago
For the collaboration
Division of Nuclear Physics, Nashville
October 27th, 2006
DNP Nashville, Oct 27 2006 2
PHOBOSEXPERIMENT
Vasundhara Chetluru
Burak Alver, Birger Back, Mark Baker, Maarten Ballintijn, Donald Barton, Russell Betts, Richard
Bindel,
Wit Busza (Spokesperson), Vasundhara Chetluru, Edmundo García, Tomasz Gburek, Joshua
Hamblen, Conor Henderson, David Hofman, Richard Hollis, Roman Hołyński, Burt Holzman, Aneta
Iordanova, Chia Ming Kuo, Wei Li, Willis Lin, Constantin Loizides, Steven Manly, Alice Mignerey,
Gerrit van Nieuwenhuizen, Rachid Nouicer, Andrzej Olszewski, Robert Pak, Corey Reed, Christof
Roland, Gunther Roland, Joe Sagerer, Peter Steinberg, George Stephans, Andrei Sukhanov,
Marguerite Belt Tonjes, Adam Trzupek, Sergei Vaurynovich, Robin Verdier, Gábor Veres, Peter
Walters, Edward Wenger, Frank Wolfs, Barbara Wosiek, Krzysztof Woźniak, Bolek Wysłouch
ARGONNE NATIONAL LABORATORY BROOKHAVEN NATIONAL LABORATORYINSTITUTE OF NUCLEAR PHYSICS PAN, KRAKOW MASSACHUSETTS INSTITUTE OF TECHNOLOGY
NATIONAL CENTRAL UNIVERSITY, TAIWAN UNIVERSITY OF ILLINOIS AT CHICAGOUNIVERSITY OF MARYLAND UNIVERSITY OF ROCHESTER
PHOBOS Collaboration
DNP Nashville, Oct 27 2006 3
PHOBOSEXPERIMENT
Vasundhara Chetluru
Outline• Ratios measurement
• PHOBOS detector.
• Particle identification using PHOBOS
• Corrections
• Results & Conclusions
DNP Nashville, Oct 27 2006 4
PHOBOSEXPERIMENT
Vasundhara Chetluru
Identified particle ratios
)(*)(* hhGAhh tedreconstruc
h
h
Particles
lesAntiparticRatioParticle Identified
h-/+ : identified anti-particle/particle count per event
GA : Geometric Acceptance
)(
)(*
)(
)(*
h
h
hGA
hGA
h
h
h
h
tedreconstruc
tedreconstruc
ε : Efficiency , Feed-down, Absorption
DNP Nashville, Oct 27 2006 5
PHOBOSEXPERIMENT
Vasundhara Chetluru
PHOBOS Detector
DNP Nashville, Oct 27 2006 6
PHOBOSEXPERIMENT
Vasundhara Chetluru
Acceptance
Z Z
Backward
Bending
Forward
Bending
90% contour
DNP Nashville, Oct 27 2006 7
PHOBOSEXPERIMENT
Vasundhara Chetluru
Different field settings
near mid-rapidity
Z
near mid-rapidity
Z
)()(21
BB hGAhGA
For a given bending direction
Ratios are measured independently for different bending directions.
B1
B2
DNP Nashville, Oct 27 2006 8
PHOBOSEXPERIMENT
Vasundhara Chetluru
Particle identification
Pions
Kaons
Protons
Deuterons
Electrons
DNP Nashville, Oct 27 2006 9
PHOBOSEXPERIMENT
Vasundhara Chetluru
Detector Acceptance
)(
)(*
)(
)(*
h
h
hGA
hGA
h
h
h
h
tedreconstruc
tedreconstruc
• Decay particles produced from the heavier particles.
• Absorption of the particles by the detector material and production of the particles from the detector.
DNP Nashville, Oct 27 2006 10
PHOBOSEXPERIMENT
Vasundhara Chetluru
Absorption Correction
pT GeV/C
Ab
sorp
tion
co-
effi
cien
t
ProtonsAntiprotons
Absorption correction is particle dependent.
DNP Nashville, Oct 27 2006 11
PHOBOSEXPERIMENT
Vasundhara Chetluru
Particle Ratio Results
DNP Nashville, Oct 27 2006 12
PHOBOSEXPERIMENT
Vasundhara Chetluru
Summary• Proton ratios are constant with in errors as a
function of centrality.
• As the collision energy increases, we observe that the antiproton to proton ratios increases.– Contribution from pair production becomes more
dominant than baryon transport.