for the Collaboration Particle Production at Very Low and Intermediate Transverse Momenta in d+Au and Au+Au Collisions Adam Trzupek The Henryk Niewodniczański Institute of Nuclear Physics Polish Academy of Sciences Kraków, Poland Quark Matter 2005 18th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions, Budapest, Hungary
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Particle Production at Very Low and Intermediate Transverse Momenta in d+Au and Au+Au Collisions
Particle Production at Very Low and Intermediate Transverse Momenta in d+Au and Au+Au Collisions. Adam Trzupek The Henryk Niewodniczański Institute of Nuclear Physics Polish Academy of Sciences Kraków, Poland. for the Collaboration. Quark Matter 2005 - PowerPoint PPT Presentation
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for the Collaboration
Particle Production at Very Low and Intermediate Transverse Momenta in d+Au and Au+Au Collisions
Adam TrzupekThe Henryk Niewodniczański Institute of Nuclear Physics
Polish Academy of Sciences
Kraków, Poland
Quark Matter 200518th International Conference on Ultra-Relativistic
Nucleus-Nucleus Collisions, Budapest, Hungary
Collaboration (August 2005)
Burak Alver, Birger Back, Mark Baker, Maarten Ballintijn, Donald Barton, Russell Betts, Richard Bindel,
Kristjan Gulbrandsen, Clive Halliwell, Joshua Hamblen, Ian Harnarine, Conor Henderson, David Hofman, Richard Hollis, Roman Hołyński, Burt Holzman, Aneta Iordanova, Jay Kane,Piotr Kulinich,
Chia Ming Kuo, Wei Li, Willis Lin, Constantin Loizides, Steven Manly, Alice Mignerey, Gerrit van Nieuwenhuizen, Rachid Nouicer, Andrzej Olszewski, Robert Pak, Corey Reed,
Eric Richardson, Christof Roland, Gunther Roland, Joe Sagerer, Iouri Sedykh, Chadd Smith, Maciej Stankiewicz, Peter Steinberg, George Stephans, Andrei Sukhanov, Artur Szostak, Marguerite Belt Tonjes, Adam Trzupek, Sergei Vaurynovich, Robin Verdier, Gábor Veres, Peter Walters, Edward Wenger, Donald Willhelm, Frank Wolfs, Barbara Wosiek, Krzysztof
Woźniak, Shaun Wyngaardt, 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
Particle Production at Very Low pT
Enhanced production of low-pT particles was predicted as a consequence of NEW long wave-length phenomena
PHOBOS experiment has a unique capability to measure particles down to very small transverse momenta: 0.03 - 0.2 GeV/c
Particle spectra at low pT can be modified due to collective transverse expansion
A recent optical model implies that chiral symmetry restoration can have significant impact on shapes of pion spectra at very low pTJ.Cramer, et al., Phys. Rev. Lett. 94 (2005) 102302
pT and PID Measurement in PHOBOS Spectrometer
10 cm
z-x
PHOBOS Spectrometer• 16 layers of silicon wafers• fine pixelization, precise dE measurement• collision vertex close to spectrometer• near mid-rapidity coverage• dipole magnetic field of 2T at maximum
• pT > 0.2 GeV/c track curvature in B field p,charge dE/dx in Si, ToF mass
• pT = 0.03 - 0.2 GeV/c low-p particles stop in silicon wafers p, mass
B field negligible no charge identification
70 cm
0 10 20 Z [cm]
X[cm
]
AB
CDE F
Be pipe . .
pT (GeV/c)0.03 0.5 5.0
Stoppingparticles dE/dx TOF
Particle ID from low to high pT
Eloss (MeV)
PHOBOS PID Capabilities
1 2 3 4 50p (GeV/c)
30
40
50
60
70
1/v
(ps/
cm)
PRC 70 (2004) 051901(R)
p+p
K +K + -
++-
p (GeV/c)
Identified Particle pT -Spectra,
Au+Au at 62.4 GeV
These results at 62.4 GeV fit smoothly into the energy evolution of antiparticle/particle ratios
Low-pT Spectra of IdentifiedParticles in Au+Au Collisions
T= 229 MeV for (++-) 293 MeV for (K++ K-) 392 MeV for (p + p)
[ ] 12
1)/exp(121 −−= BET
TTTmA
dydmNd
mπ
mT = pT2+mh
2
B-E fit
BWF fit
(2p
T)1 d
2 N/d
ydp T
[c2 /G
eV2 ]
(2p
T)1 d
2 N/d
ydp T
[c2 /G
eV2 ]
Invariant Yields of Very Low pT Particlesin Central Au+Au Collisions at sNN=200 GeV
(2p
T)1 d
2 N/d
ydp T
[c2 /G
eV2 ]
Low-pT Spectra as Model Constraints
J. Cramer (private comm.,erratum to be published)
J.Cramer, et al., PRL 94 (2005) 102302(2
pT)
1 d2 N
/dyd
p T[c
2 /GeV
2 ]
Identified Particle pT -Spectra, d+Au at sNN= 200 GeV
pT range:(++-) : > 0.03 GeV/c (K++ K
-): > 0.09 GeV/c
(p + p) : > 0.14 GeV/c
Background corrections: very low-pT:
(++-) : 20% (K++ K
-): 10%
(p + p) : 20% intermediate pT
(p + p) : ~20%
Systematic uncertainties: very low pT: ~30% intermediate pT : ~15%
Event selection: described in PRL 93, 082301Tfo = 152 GeV, <T>=0.37 c
(2p
T)1 d
2 N/d
ydp T
[c2 /G
eV2 ]
mT -Scaling in d+Au at sNN= 200 GeV
(++-), (K++ K-), (p + p) mT-yields are similar after scaling (K++ K-) yield by a factor 2 (strangeness suppression)
Local slopes of mT -spectra similar
T loc
[GeV
/c2 ]
mT -Scaling in d+Au vs. Au+Au at sNN = 200 GeVPRC 70 (2004) 051901(R)
In central Au+Au, larger flattening for of p+p mT spectra at small pT
Low-pT spectra of p+p can constrain models describing collective transverse expansion of the system
(2p
T)1 d
2 N/d
ydp T
[c2 /G
eV2 ]
(2p
T)1 d
2 N/d
ydp T
[c2 /G
eV2 ]
T loc
[GeV
/c2 ]
T loc
[GeV
/c2 ]
Summary
No evidence for enhanced production of very low-pT pions iaiiin the mosticentral Au+Au collisions at energy 62.4 and iaii200 GeV Flattening of p+p mT spectra at low-pT in 15% most central iaiiAu+Au collisions at energy 62.4 and 200 GeV Approximate mT scaling of particle spectra for d+Au iaiicollisions at low and intermediate transverse momentum New constraints on models and fits