UC Davis June st Rosi Reed Low Energy Test Run Results Rosi Reed University of California at Davis

UC Davis June st Rosi Reed Introduction Event quality Beam Pipe Events – Spectra – HBT Beam Profile Analysis 2

UC Davis June st Rosi Reed Summary 9 GeV Test Run % with Vertex Yellow = cogged at Phenix 3.3% with Vertex r < 2 cm

UC Davis June st Rosi Reed Multiplicity – Cut on Events heading into the TPC 30% Central 62.4 GeV points are scaled to match 3.2 GeV points at Nch = 13 Au-Al Au-Al + Alpha-Al An increased yield in low multiplicity events could be the result of alpha particles from Au break-up hitting the beam pipe

UC Davis June st Rosi Reed Au-Al HBT Analysis – Rigidity π+π+ π-π- p t d

UC Davis June st Rosi Reed Some Calculations – Au-Al Events

UC Davis June st Rosi Reed Eta for Au-Al Events 30% Central All % Central Events with a Negative Average Eta Flipped for Graphs Increase at Eta = 0 from Spectators from Al

UC Davis June st Rosi Reed Eta for Au-Al Events 30% Central Proton 30% Central Pion % Central Proton % Central Pion PID done through nSigma cut

UC Davis June st Rosi Reed Pion+ Proton Yield for Au-Al Events y bin = 0.5 around y cm No efficiency corrections made T ~ 80 +/- 2 MeVT ~ 91 +/- 3 MeV T ~ 99 +/- 4 MeV

UC Davis June st Rosi Reed Proton/Pion Ratio for Au-Al Events Increase in p vs pi at y = 0 comes from Al spectators

UC Davis June st Rosi Reed Au-Al HBT Analysis (root S NN = 3.2) Event quality cuts: – Vr > 2 cm (Not Au+Au collisions) – |Vz| > 75 cm (Not Au+Be collisions) – Vz*TotalEventPz < 0 (Events “into” TPC) – Events with Pz < 0 flipped (pz = pz*-1) – Multiplicity > 10 (30% Central) Track Quality cuts: – Assumed all negatively charged tracks were pions – nHits/nPossHits > 0.5 for either TPC or FTPC

UC Davis June st Rosi Reed Au-Al pi- HBT Analysis

UC Davis June st Rosi Reed Beam profile vs time Analyzed Vx vs Vy distributions vs time for – Run 72 (13:26:02 – 28:25) – Run 73 (13:36:10 – 13:37:30) – Run 74 (43:12 – 44:21) Binned distributions with the same Vernier scan location No Z vertex cuts Cut on Vr < 2

UC Davis June st Rosi Reed Gaussian Multiplication Beam is gaussian in shape Distribution of collisions in xy space is equal to the beam distributions multiplied by each other – Also gaussian in shape

UC Davis June st Rosi Reed Assuming the beams have the same width

UC Davis June st Rosi Reed Beam profile vs time Summary Calculated from Vx vs Vy distributions # Beam- Beam Events Blue = Run 72, Yellow Run 73, Grey Run 74

UC Davis June st Rosi Reed Beam Sigmas calculated from formula on pg 15 Sigma X = 1.75 mm +/-.20 Sigma Y = 2.40 mm +/-.15 Error bars reflect statistical error only If our assumptions are correct, these distributions should be flat Beam Sigmas

UC Davis June st Rosi Reed Vernier Scan Versus Average Event Location Slope should be +/- 0.5 if our assumptions were correct

UC Davis June st Rosi Reed Time Decay for Run 97 Empty events fall off exponentially Beam-Beam and Empty Events have the same time constant Beam-Pipe events have twice the time constant of Beam-Beam and Empty Events Run 97 occurred after BBC threshold was lowered

UC Davis June st Rosi Reed Events During Vernier Scan During Vernier Scan it appears the empty event rate follows the beam-beam event rate in runs 72 and 73.

UC Davis June st Rosi Reed Conclusion We still do not understand why we triggered – Empty events BBC threshold changed but the trigger rate still seems to be beam related – Beam-Pipe Events Beam Pipe events are a combination of Au-Pipe Material and Alpha-Pipe Material We have a reasonable estimate of the good event rate

UC Davis June st Rosi Reed Backup Slides

UC Davis June st Rosi Reed Vernier Scan

UC Davis June st Rosi Reed Vx Vy Distribution of 1 st Primary Vertex at 9 GeV 24

UC Davis June st Rosi Reed Z Axis distributions Thin Be beam pipe extends from Z = -75 cm to 75 cm. Outside 75 cm there is a thicker Al beam pipe. 3.6 AGeV Au+Be 3.6 AGev Au+Al

UC Davis June st Rosi Reed Number of Vertices per Event % of events had 1 primary vertex – 81.6% of “beam-beam” events have 1 primary vertex – 71.6% of “beam-pipe” events have 1 primary vertex (Data taken from runs 97,76,72)

UC Davis June st Rosi Reed XY Location of 2 nd + 3 rd Vertices for Events with Vertex 1 r > 2 cm Data from Runs 97, 76, 72 Only 8 % of secondary vertices and 8 % of teritary vertices of events labeled as beam pipe events are located in the center Indicates that most events labeled as beam pipe events are not Au- Au events that have kicked off an energetic particle.

UC Davis June st Rosi Reed Average Eta by Event 28 Run 97, 76, 72 Eta averaged over primary tracks only

UC Davis June st Rosi Reed Vx vs Vy Distributions for Same Vernier Scan Locations

UC Davis June st Rosi Reed Vx vs Vy Distributions for Same Vernier Scan Locations

UC Davis June st Rosi Reed Track Eta Distribution for Eta Ave > 0