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Analyzing 9 GeV Au+Au collisions from ~200k events, focusing on vertices, beam-pipe events, and physics insights. Run details: http://nuclear.ucdavis.edu/~ddas/9GeV_runs.html. Contact: rjreed@ucdavis.edu.
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9 GeV Au+Au Collisions • Run on March 11th, 2008 • Out of ~200k Events • 11000 had Vertices • 6700 had Vertices within 2 cm of the beamline • 4150 appeared to be beam-pipe events • Run details can be found at: http://nuclear.ucdavis.edu/~ddas/9GeV_runs.html • Combinations of bbc,vpd,ctb triggers used Rosi Reed rjreed@ucdavis.edu
9 GeV Au+Au Collisions Be beam pipe extends from -75 cm to 75 cm
Beam-Pipe Collisions and Low Energy Considerations • Why did we trigger on “empty” events? • Why did we trigger on beam-pipe events • Are the events labeled as beam-pipe events actually collisions between Au and the beam pipe? • We looked at the physics in these events to determine whether this was the case
Au-Al HBT Analysis (root SNN = 3.2) • Event quality cuts: • |Vz| > 75 cm • Vr > 2 cm • Vz*TotalEventPz < 0 • Track Quality cuts: • Assumed all negatively charged tracks were pions • nHits/nPossHits > 0.5 for either TPC or FTPC
Au-Al HBT Analysis Fit does not use lowest 3 points due to track merging