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J/  Simulations for RUN III

J/  Simulations for RUN III. Manuel Calderon for the Heavy-Flavor Group Analysis Meeting at BNL October 23, 2002. Simulations so far ….

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J/  Simulations for RUN III

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  1. J/ Simulations for RUN III Manuel Calderon for the Heavy-Flavor Group Analysis Meeting at BNL October 23, 2002

  2. Simulations so far … • Rejection/Efficiency: Working on AuAu low multiplicity simulations only up to now. Need dAu simulations, can probably get higher rejection with lower multiplicity events. Use Seff = S/(2B/S + 1) • Background: • Minbias Au+Au (only last weekend did d+Au begin running…) • Select most peripheral 50% x-section: dN/dh = 11 (5.6 at 40%) to approx. d+Au multiplicity • Signal: • J/Psi simulated flat in pt and h to see efficiency vs pt • Will use more realistic pt distribution to see where most signal sits. • Throw one J/Psi in an empty event • Need to also mix them into a background event. • Using 3 cuts: Tower Energy (L0), Mass, Cos(q) (L2)

  3. Algorithm 1) Approximate the electron daughters with towers (or clusters) Energy, Position 2) Obtain vertex from BBC timing 3) Need at least 2 towers to make a pair (could require this at L0?) 4) Take all selected towers and make all possible pairs Minv  2E1E2(1-cos(q12)) 5) Do cuts in M and cos(q)… Still exploring possibilities Towers, clusters, cluster size?

  4. Algorithm : Need to explore various ideas • What are the best energy thresholds to use? • 1, 1.5, 2 GeV? Want acceptable resolution and not to kill the signal. • First tested with Tower Energy only: resolution not good! • Now testing various cluster approaches: 2 towers, or patches of various sizes (3x3, 5x5, 7x7, 9x9) 2-Tower Cluster Single Tower

  5. Acceptance and Trigger Efficiency J/Y • 1) Done at mid-rapidity with full EMC • 2) Trigger efficiency using Tower Energy (no clustering), and both towers with same threshold (1 GeV)

  6. Half EMC acceptance (pT - h) Raw Accepted electrons with E>1 GeV, 0.1 < h < 0.9

  7. Acceptance and Trigger Efficiency (Half Emc, Cluster) • Half Emc, 0.2 < h < 1

  8. J/Y Mass at Level 2 J/Y flat in pt-h Background Thrown mass L2 Mass, real E, real cos(q) L2 Mass, cluster E, real cos(q) L2 Mass, real E, cluster cos(q) L2 Mass, cluser E and cos(q) To do: simulate with some pT slope

  9. J/Y Mass at Level 2 (from today!) J/Y with slope 600 MeV Background (w/ dAu) Thrown mass L2 Mass, real E, real cos(q) L2 Mass, cluster E, real cos(q) L2 Mass, real E, cluster cos(q) L2 Mass, cluser E and cos(q) <M> = 2.93, 2.68 GeV sM = 300, 668 MeV Rejection Factor at L2 for loose cuts: 35 Goal: ~48 KHz/1KHz not too far

  10. Decay Topology: large opening angle for most J/Y Accepted J/Y (flat in pt-h) Background

  11. Isolation cuts… Compare tower (or “cluster”) energy to surrounding energy in patch For 3x3 patch Electrons

  12. To Do: • Still many simulations and tests to do to arrive at a good L2 Algorithm: • + Low multiplicity in d+Au will reduce the backgrounds • - Signal is faint ~ “one in a million” • - Half EMC drastically reduces acceptance • Need to try out • various patches, 3x3, 5x5 • Energy Thresholds • Mass Thresholds • Opening Angles • Isolation cuts

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