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The Lambda (3 rd installment)

The Lambda (3 rd installment). Lbar+random observations Richard Seto Ppg016 meeting Jan 2, 2003. Procedure. CNT ntuples to pair ntuples from munir ppi- and pbarpi+ TOF-TOF, EMCE-EMCE, TOF-EMCE, all east Cuts done for me by munir No additional cuts for now

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The Lambda (3 rd installment)

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  1. The Lambda (3rd installment) Lbar+random observations Richard Seto Ppg016 meeting Jan 2, 2003

  2. Procedure • CNT ntuples to pair ntuples from munir ppi- and pbarpi+ • TOF-TOF, EMCE-EMCE, TOF-EMCE, all east • Cuts done for me by munir • No additional cuts for now • Normalization is still just between 1.13 –1.2 GeV • Note- mass of lambda is 1.1157 • Gaussian fit, convoluted with gausian of 1.3 GeV (from resolution?)- extracted “width” is plotted from 1.10-1.13 (30 MeV, 2 MeV bins, 15-3=12 degrees of freedom • Chisq tends to be ~ 25 (10-45) for 13 DOF • Centrality bins 0-10, 10-20, 20-40, 40-60, 60-100 • Pt bins .3-1.8, 1.8-5 or .3,.8,1.3,1.8,2.3,2.8 • Still problems with background – working on ++ and – (no results yet)

  3. For the record (from munir) • List of runs • run2_v03_burn1/CNT files. The complete list at /phenix/u/munir/FileList/UCR_CNT_file.lis • We do 3-types of combinations: • Both pbar and pion are identified in tof (TOF-TOF) • Both pbar and pion are identified in PbSc (East-East) • One member of the pair in TOF and the other in PbSc (TOF-East) • Only pi+ in TOF and pbar in PbSc contributes for the third kind of mixing. • RKS has a question about this

  4. EMCal (East): |bbcz| < 30. |zed|<75 quality==31 || 63 0.3<mom<1.2 for both protons and pions emcsdphi*emcsdphi + emcsdz*emcsdz < 9. isPi ans isK calculated using EMCal resolution of 480ps (followed HadPid in CVS) |isP|<2 |isPi|<2 Tof           |bbcz| < 30. |zed|<75 quality==31 || 63 etof>0.002 |tofsdphi|<2.5 && |tofsdz|<2.5 |isP|<2.5 |isPi|<2.5 0.5<mom<3.0 for proton 0.25<mom<1.8 for pion Single particle Cuts

  5. Pair acceptace criteria • ghost track rejection : applied ONLY to same sign pairs • |delta_zed|<0.02 • |delta_phi|<0.03 • one member of the pair is randomly rejected • intruder rejection : In same arm and same sector • TOF : delta_ttof=0 && delta_etof=0 • PbSc: delta_temc=0 && delta_ecore=0 • both members of pair are rejected. • For actual pair +-, ++ and -- : • 0<centclock<93 • For mixed pair +-, ++ and --  : • 18 centrality bins from 0% in an increment of 5%, the last bin is 85%-92% • 15 bbcz bins from -30 cm in an increment of 4 cm • tracks from same centrality and vertex bins are mixed

  6. Cut (TOF+)(EMC-) • Typical cut requires for tof-emc combo + in TOF, and – in emce for phi – use same cut for lambda • IS this OK? seems like a mass cut to me (looking at lbar) Without Pt<1.8 With cut Pt<1.8

  7. Widths • Consistent with flat lambda lambdabar

  8. Masses • Reasonable value • Pdg=1.1157 lambda lambdabar

  9. Pt dependence“all”

  10. To do • Do a more careful study of these plots • See munirs stuff • Look at ++, -- and study subtraction problems

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