Kyoto Univ. JSPS RIKEN RIKEN PHENIX D 2010 / 10/ 15 1 Kyoto Univ. / JSPS / RIKEN spin puzzle ? g g Q Q-bar hard scattering process G G 2010/9/112 JPS fall meeting Kyoto Univ. / JSPS / RIKEN PHENIX PHENIX heavy meson PHENIX 2010/9/11 JPS fall meeting 3 photonic electron Dalitz small, but significant at high p T non-photonic electron ( signal ) Kyoto Univ. / JSPS / RIKEN simulation result of e yield heavy meson 2010/9/11 JPS fall meeting 4 photonic electron Dalitz small, but significant at high p T non-photonic electron dominant background background ~ a few% of non-photonic electrons ~ a few% of non-photonic electrons photonic ~95% negligiblenegligible HBD ( signal ) Kyoto Univ. / JSPS / RIKEN Hadron Blind Detector (HBD) Hadron Blind Detector CsI GEM gas Cherenkov hadron ( ) hadron > 10 27mm pad size Cherenkov blob ~ 36mm 1 20 photoelectron hadron : 1 photoelectron non-photonic photonic 2010/9/11 JPS fall meeting 5 HBD CF 4 gas non-photonic electron ( single electron ) photonic electron ( pair electrons ) Mesh CsI layer Triple GEM Readout Pads e-e- Primary ionization HV 50cm Kyoto Univ. / JSPS / RIKEN HBD Event Display add blob (cluster) information private clustering algorithm 6 HBD charge [p.e.] seed pad seed pad seed pad Clustering Algorithm make a cluster with seed pads add neighbor pads to the cluster cluster charge is the sum of pad charges seed pad: pad with large charge (> 3p.e.) Dead Not Stable SNSN Kyoto Univ. / JSPS / RIKEN Electron Cut electron cut abs(bbc_z) < 20cm quality==31|51|63 n0>=2 e/p cut ecore>0, mom>0 abs(emcsdphi_e)=2 : (reject fake hit) 2010/9/11 JPS fall meeting 7 Kyoto Univ. / JSPS / RIKEN HBD non-photonic & photonic 2010/9/11 JPS fall meeting 8 non-photonic electron photonic electron single e cluster merged cluster reject eff. ~ 80% eff. ~ 30% non-photonic electron photonic electron HBD non-photonic electrons photonic electrons Dalitz electron pair Dalitz pair mass < 135MeV Kyoto Univ. / JSPS / RIKEN HBD charge distribution (East) Not including HBD efficiency Integral(0,inf) = 1 9 NorthSouthNorthSouth Sect0 Sect1 Sect2 Sect3 Sect4 Sect5 very low stat. not stable gain Red: merged cluster Blue: separated cluster low stat. #{bin content}/ #{all entry} Kyoto Univ. / JSPS / RIKEN HBD charge distribution (West) 10 NorthSouthNorthSouth Sect6 Sect7 Sect8 Sect9 Sect10 Sect11 strange shape Red: merged cluster Blue: separated cluster low stat. Kyoto Univ. / JSPS / RIKEN HBD charge distribution for Hadrons (fake hits) normalized with the number of tracks satisfying hadron cut hadron efficiency < 10% 11 HBD charge distribution of hadron cut + hbd association cut tracks HBD charge [p.e.] threshold in offline code requiring following cuts hadron cut abs(bbc_z) < 20cm quality == 63 mom > 0.5 && mom < 3.0 n0 0 e/p = 2 efficiency ~ 162/213 = 76% using good sector (sect 2,3,4(south), 8,9,10) cut Kyoto Univ. / JSPS / RIKEN HBD association efficiency w/o HBD size cut HBD association efficiency w/ HBD size cut HBD efficiency with J/phi events (select good region) HBD cut abs(hbdsdphi) < 3.5 abs(hbdsdz) < 3.5 efficiency ~ 100% within error HBD cut abs(hbdsdphi) < 3.5 abs(hbdsdz) < 3.5 hbdsize >= 2 efficiency ~ 66/77 = 86% good region good region 26.5cm 22.9cm 18.0cm 14.0cm Kyoto Univ. / JSPS / RIKEN HBD charge distribution for electron tracks sect8 north 0.75