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Iowa State University

Elementary Particles and Fields and String Theory

2005

Articles 1 - 8 of 8

Full-Text Articles in Physics

Measurement Of Transverse Single-Spin Asymmetries For Midrapidity Production Of Neutral Pions And Charged Hadrons In Polarized P+P Collisions At √S=200 Gev, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, Et Al. Nov 2005

Measurement Of Transverse Single-Spin Asymmetries For Midrapidity Production Of Neutral Pions And Charged Hadrons In Polarized P+P Collisions At √S=200 Gev, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, Et Al.

Physics and Astronomy Publications

Transverse single-spin asymmetries to probe the transverse-spin structure of the proton have been measured for neutral pions and nonidentified charged hadrons from polarized proton-proton collisions at midrapidity and √s=200  GeV. The data cover a transverse momentum (pT) range 1.0–5.0  GeV/c for neutral pions and 0.5–5.0  GeV/c for charged hadrons, at a Feynman-x value of approximately zero. The asymmetries seen in this previously unexplored kinematic region are consistent with zero within errors of a few percent. In addition, the inclusive charged hadron cross section at midrapidity from 0.5


Centrality Dependence Of Direct Photon Production In Root S-Nn=200 Gev Au+Au Collisions, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, Et Al., Phenix Collaboration Jun 2005

Centrality Dependence Of Direct Photon Production In Root S-Nn=200 Gev Au+Au Collisions, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, Et Al., Phenix Collaboration

Physics and Astronomy Publications

The first measurement of direct photons in Au+Au collisions at root s(NN)=200 GeV is presented. The direct photon signal is extracted as a function of the Au+Au collision centrality and compared to next-to-leading order perturbative quantum chromodynamics calculations. The direct photon yield is shown to scale with the number of nucleon-nucleon collisions for all centralities.


Saturation Of Azimuthal Anisotropy In Au Plus Au Collisions At Root S-Nn=62-200 Gev, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, H. Pei, Jan Rak, Marzia Rosati, S. Skutnik, F. K. Wohn, Et Al., Phenix Collaboration Jun 2005

Saturation Of Azimuthal Anisotropy In Au Plus Au Collisions At Root S-Nn=62-200 Gev, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, H. Pei, Jan Rak, Marzia Rosati, S. Skutnik, F. K. Wohn, Et Al., Phenix Collaboration

Physics and Astronomy Publications

New measurements are presented for charged hadron azimuthal correlations at midrapidity in Au+Au collisions at root s(NN)=62.4 and 200 GeV. They are compared to earlier measurements obtained at root s(NN)=130 GeV and in Pb+Pb collisions at root s(NN)=17.2 GeV. Sizeable anisotropies are observed with centrality and transverse momentum (p(T)) dependence characteristic of elliptic flow (v(2)). For a broad range of centralities, the observed magnitudes and trends of the differential anisotropy, v(2)(p(T)), change very little over the collision energy range root s(NN)=62-200 GeV, indicating ...


Deuteron And Antideuteron Production In Au+Au Collisions At Root S(Nn)=200 Gev, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, Et Al., Phenix Collaboration Apr 2005

Deuteron And Antideuteron Production In Au+Au Collisions At Root S(Nn)=200 Gev, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, Et Al., Phenix Collaboration

Physics and Astronomy Publications

The production of deuterons and antideuterons in the transverse momentum range 1.1 < p(T)< 4.3 GeV/c at midrapidity in Au+Au collisions at root s(NN) = 200 GeV has been studied by the PHENIX experiment at RHIC. A coalescence analysis, comparing the deuteron and antideuteron spectra with that of proton and antiproton, has been performed. The coalescence probability is equal for both deuterons and antideuterons and it increases as a function of p(T), which is consistent with an expanding collision zone. Comparing (anti)proton yields, (p) over bar /p = 0.73 +/- 0.01, with (anti)deuteron yields, (d) over bar /d = 0.47 +/- 0.03, we estimate that (n) over bar /n = 0.64 +/- 0.04. The nucleon phase space density is estimated from the coalescence measurement.


Midrapidity Direct-Photon Production In P+P Collisions At Root S=200 Gev, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, Et Al., Phenix Collaboration Apr 2005

Midrapidity Direct-Photon Production In P+P Collisions At Root S=200 Gev, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, Et Al., Phenix Collaboration

Physics and Astronomy Publications

A measurement of direct photons in p+p collisions at root s=200 GeV is presented. A photon excess above background from pi(0)->gamma+gamma, eta ->gamma+gamma and other decays is observed in the transverse momentum range 5.5 < p(T)< 7 GeV/c. The result is compared to a next-to-leading-order perturbative QCD calculation. Within errors, good agreement is found between the QCD calculation and the measured result.


Nuclear Modification Factors For Hadrons At Forward And Backward Rapidities In Deuteron-Gold Collisions At Root S(Nn)=200 Gev, S. S. Adler, S. Belikov, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, H. Pei, Jan Rak, Marzia Rosati, F. K. Wohn, X. Zong, Et Al., Phenix Collaboration Mar 2005

Nuclear Modification Factors For Hadrons At Forward And Backward Rapidities In Deuteron-Gold Collisions At Root S(Nn)=200 Gev, S. S. Adler, S. Belikov, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, H. Pei, Jan Rak, Marzia Rosati, F. K. Wohn, X. Zong, Et Al., Phenix Collaboration

Physics and Astronomy Publications

We report on charged hadron production in deuteron-gold reactions at roots(NN) = 200 GeV. Our measurements in the deuteron direction cover 1.4 < eta < 2.2, referred to as forward rapidity, and in the gold direction -2.0 < eta < -1.4, referred to as backward rapidity, and a transverse momentum range p(T)=0.5-4.0 GeV/c. We compare the relative yields for different deuteron-gold collision centrality classes. We observe a suppression relative to binary collision scaling at forward rapidity, sensitive to low momentum fraction (x) partons in the gold nucleus, and an enhancement at backward rapidity, sensitive to high momentum fraction partons in the gold nucleus.


Centrality Dependence Of Charm Production From A Measurement Of Single Electrons In Au Plus Au Collisions At Root S(Nn)=200 Gev, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, Et Al., Phenix Collaboration Mar 2005

Centrality Dependence Of Charm Production From A Measurement Of Single Electrons In Au Plus Au Collisions At Root S(Nn)=200 Gev, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, Et Al., Phenix Collaboration

Physics and Astronomy Publications

The PHENIX experiment has measured midrapidity transverse momentum spectra (0.4 < p(T)<4.0 GeV/c) of single electrons as a function of centrality in Au+Au collisions at roots(NN) = 200 GeV. Contributions from photon conversions and Dalitz decays of light neutral mesons are measured by introducing a thin (1.7% X-0) converter into the PHENIX acceptance and are statistically removed. The subtracted nonphotonic electron spectra are primarily due to the semileptonic decays of hadrons containing heavy quarks, mainly charm at lower p(T). For all centralities, the charm production cross section is found to scale with the nuclear overlap function, T-AA. For minimum-bias collisions the charm cross section per binary collision is N-c (c) over bar/T-AA=622+/-57(stat)+/-160(syst) mu b.


Systematic Study Of High-Pt Di-Jet Correlations In Nuclear Collisions With The Phenix Experiment At Rhic , Nathan Conrad Grau Jan 2005

Systematic Study Of High-Pt Di-Jet Correlations In Nuclear Collisions With The Phenix Experiment At Rhic , Nathan Conrad Grau

Retrospective Theses and Dissertations

One major goal of the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory on Long Island, New York, is to create and study the quark-gluon plasma (QGP). This state of matter results from the phase transition of Quantum Chromodynamics (QCD) at extremely high temperature (1012 K) and densities (100 times normal nuclear matter). Au ions are collided in an attempt to increase the temperature necessary to cross the phase boundary. To study the properties of this new matter, high energy jets are used as a probe. Jets are a collimated spray of hadrons resulting from the fragmentation of high-energy ...