Strangeness enhancement in heavy ion collisions at the AGS as a possible signature of the quark gluon plasma formation.
Item
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Title
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Strangeness enhancement in heavy ion collisions at the AGS as a possible signature of the quark gluon plasma formation.
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Identifier
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AAI9431379
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identifier
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9431379
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Creator
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Zhao, Kaihui.
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Contributor
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Adviser: S. J. Lindenbaum
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Date
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1994
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Language
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English
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Publisher
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City University of New York.
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Subject
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Physics, Elementary Particles and High Energy | Physics, Nuclear
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Abstract
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Enhanced strangeness production was suggested a decade ago{dollar}\sp1{dollar} as a possible signature of Quark Gluon Plasma (QGP), which is a state of unconfined quarks and gluons that will exist in superdense and hot nuclear matter as predicted by Quantum Chromodynamics (QCD). Theorists believe that such a state (QGP) existed in the early universe for {dollar}\sim{dollar}10{dollar}\sp{lcub}-\in\ni{rcub}{dollar} seconds, and could possibly be created in laboratory with relativistic heavy-ion collisions. We utilized the 14.6 {dollar}\times{dollar} A GeV/c Si beam provided by the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory (BNL) to bombard different targets (Al, Si, W, Au, Pb, etc.) in searching for a QGP. Particles produced in the forward hemisphere (NN center of mass system) from these collisions traveled through up to 3 TPC (Time Projection Chamber) modules which were in a 5 kilogauss magnetic field. Each detected track was recorded individually with regards to position, momentum and charge.;A significantly enhanced {dollar}K\sbsp{lcub}s{rcub}{lcub}\rm O{rcub}{dollar} and {dollar}\Lambda{dollar} production in relativistic heavy-ion collisions over that of a simple cascade of NN collisions was detected. But the enhancement of single strangeness particles may not be good signature of QGP, because secondary scatterings of resonant states (e.g. {dollar}\Delta{dollar} and {dollar}N\sp\*{dollar}) in a hadron gas may as well increase their production. This makes the multistrange hyperon (e.g. {dollar}\Xi\sp-{dollar}) production a better alternative for a QGP signature, because its formation through resonant state rescatterings in hadron gas is more difficult than that of single strangeness particles (e.g. {dollar}K\sbsp{lcub}x{rcub}{lcub}\rm O{rcub},\ \Lambda).{dollar} Excessive strangeness content in a QGP may favor {dollar}\Xi\sp-{dollar} production (as well as strangelets) during hadronization.;Copious production of {dollar}\Xi\sp-{dollar} has been detected with limited statistics. The measured ratio of N{dollar}(\Xi\sp-){dollar}/N{dollar}(\Lambda){dollar} = {dollar}0.12\pm 0.02\pm 0.025{dollar} is at least 3 times larger than the predictions of generally known hadronic cascade models. Various models and general considerations have been explored trying to understand the physical implications of the experimental results.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
