Dissertation/Thesis Abstract

Charmed Meson Measurements Using a Silicon Tracker in Au+Au Collisions at √SNN = 200 GeV in Star Experiment at RHIC
by Ajish, Jaiby J., Ph.D., Kent State University, 2011, 202; 10630805
Abstract (Summary)

My area of research is experimental nuclear physics, more specifically heavy ion collisions at velocities close to the speed of light. The data analyzed comes from the STAR experiment at the Relativistic Heavy Ion Collider (RHIC), located at Brookhaven National Laboratory (BNL) in Upton, NY. At RHIC, two beams of ions travel at velocities close to the speed of light in opposite directions in a 2.4 mile ring and these beams cross at six points. RHIC has now two large experiments STAR and PHENIX. This work is done using the data collected by the STAR (Solenoidal Tracker at RHIC) detector during the year 2007 run.

Collisions of heavy ions that are traveling close to the speed of light create extreme temperatures and densities, and they might produce a new form of nuclear matter. This form of matter might have existed just a few microseconds after the Big Bang. Understanding how nuclear matter behaves under these conditions might help us to know how matter behaved at the beginning of the Universe as well as to study exotic objects in the cosmos.

At sufficiently high temperature and/or high densities it is believed that the protons and neutrons inside the nuclei melt to form a soup of quarks, antiquarks and gluons, called the Quark-Gluon Plasma (QGP). During the collision, thousands of new particles form due to nuclear interactions and this “fireball” expands and cools. The STAR detector can be used to search these particle tracks to look for clues about QGP creation. Striking observations from RHIC, such as partonic collectivity and jet quenching have led us to the conclusion that strongly interacting, deconfined partonic matter (sQGP) is created in Au+Au collisions at √SNN = 200 GeV. The properties of this new matter, however are still not well understood, especially the production and properties of heavy quarks like charm and beauty.

The energy loss of charm quarks showed an anomalous behavior in previous studies, which used an indirect method based on the decay electrons. So in this dissertation, we try a direct topological reconstruction of neutral charm mesons through the decay channel D0(0) → Kπ ±. The method uses constrained fit for secondary vertex reconstruction. The new feature of this dataset is that the data collected included the Silicon Drift and Silicon Strip detectors; their pointing capabilities are crucial for this analysis. Results obtained on neutral D-meson measurements are presented.

The precision of the previous generation of silicon detectors proved to be marginal for the purpose of drawing strong physics conclusions. For an unambiguous measurement of the heavy flavor and to understand the mechanism of partonic energy loss, a new micro-vertex detector is being built for STAR—The Heavy Flavor Tracker (HFT). The method developed here is a baseline for analyses involving HFT.

Indexing (document details)
Advisor: Margetis, Spyridon
Commitee: Kabana, Sonia, Keane, Declan, Manley, Mark, Margetis, Spyridon, Ruoming, Jin, Twieg, Robert
School: Kent State University
Department: College of Arts and Sciences / Department of Physics
School Location: United States -- Ohio
Source: DAI-B 78/11(E), Dissertation Abstracts International
Subjects: Physics, Nuclear physics
Keywords: Charm meson, Microvertexing, Quark-gluon plasma, RHIC, SVT, Silicon trackers
Publication Number: 10630805
ISBN: 9780355011500
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