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Title page for ETD etd-12042008-160313

Type of Document Dissertation
Author Valle, Hugo Edilberto
Author's Email Address hugo.valle@gmail.com
URN etd-12042008-160313
Title Source dynamics from deuterons and anti-deuterons in sqrt(s_NN) = 200 GeV Au+Au collisions
Degree PhD
Department Physics
Advisory Committee
Advisor Name Title
Julia Velkovska Committee Chair
Charles F. Maguire Committee Member
Franz Baudenbacher Committee Member
Volker Oberacker Committee Member
Will Johns Committee Member
  • Nuclear Physics
  • RHIC
  • spectra
  • anti-deuterons
  • deuterons
Date of Defense 2008-11-18
Availability unrestricted
We have studied the source dynamics of the matter in ultra relativistic $Au+Au$ collisions at $sqrt{s_{N N}} = $200 GeV by analyzing the production of the simplest nuclei: deuterons and anti-deuterons. In relativistic heavy ion collision the system expands and cool s, and when the interactions among the particles finally cease during the ``free ze-out", light nuclei like $d$ and $ar{d}$ can be formed.

The transverse momentum ($p_T$) spectra of $d$ and $ar{d}$ in the range 1.1 $< $ $p_{T}$ $<$ 5.0 GeV/c have been measured at mid-rapidity. The slopes of the ha dron spectra are directly related to the temperature of the source at freeze-out and the flow velocity of the collectively expanding system. The radial flow has the effect of flattening the spectra of heavier particles, thus the $d$ and $ ar{d}$ spectra are less steeply falling than the (anti-)proton spectra.

Measurements of radial flow velocity and freeze-out temperature using the blast- wave hydrodynamic model for deuterons was attempted. Our results indicate that w ithin this model the deuterons do not freeze-out contemporaneously with the prod uced hadrons. The deuteron spectra require a lower flow velocity than the proton spectra. Due to their unique sensitivity to the dynamics of the emission proces s, these results can constrain full hydrodynamics calculations.

The coalescence probability, $B_2$, of neutrons and protons into deuterons as a function of transverse momentum and centrality has been studied. We observed a d ecrease in $B_2$ for more central collisions where the volume of the system is l arger. The ratio of the hadron spectra in central and peripheral collisions ($R_ {CP}$) is used to study the effects of the quark-gluon plasma medium on the prop agation of fast partons through it. For deuterons, we observe a significant enha ncement in $R_{CP}$ compared to other hadrons. This behavior indicates that both proton and neutron production are enhanced contrary to the suppression of pions .

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