1 February 8, 2008 Sunil Dogra QM2008 Jaipur 1 Sunil M. Dogra University of Jammu, India (For the STAR collaboration) Outline Motivation STAR Experiment Analysis Method Results Summary STARs measurement of correlation and fluctuations between photons and charged particles at forward rapidity at RHIC 2 February 8, 2008 Sunil Dogra QM2008 Jaipur 2 Motivation Inclusive photons provide the information of production of Chiral symmetry restoration could be reflected via study of Photon- Charged particles Fluctuations. Formation of Disoriented Chiral Condensates (DCC) generate fluctuations between photons and charged particles. DCC formation is expected to provide information on the vacuum structure of strong interaction and chiral phase transition. Anti-CENTAURO event of JACEE 36 photons, 1 charged particle 3 February 8, 2008 Sunil Dogra QM2008 Jaipur 3 STAR Experiment Nucl.Instrum.Meth.A499: ,2003 Coverage: 2.3< | < 4.0 Event-by-event number of charged particles Spatial distribution ( , ) and p T of charged particles Coverage: | < 1.5 Nucl.Instrum.Meth A 499, 713 (2003) 4 February 8, 2008 Sunil Dogra QM2008 Jaipur 4 Photon Multiplicity Detector Two planes CPV+Preshower Gas detector of hexagonal cells Cell cross section : 1.0 cm 2 Cell depth : 0.8 cm Gas used: Ar+CO 2 in 70:30 Total number of cells : 82,944 Area of the detector : 4.2 m 2 Distance from vertex : 540 cm Coverage: -2.3 to -3.8 in with full Nucl. Instrum. Meth. A 499, 751 (2003) 5 February 8, 2008 Sunil Dogra QM2008 Jaipur 5 Principle of Photon Multiplicity detector Photons passing through the converter initiate an electro-magnetic shower and produce large signal on several cells of the sensitive volume of the detector. Hadrons normally affect only one cell and produce a signal representing minimum ionizing particles. 6 February 8, 2008 Sunil Dogra QM2008 Jaipur 6 This Analysis: clusters with N cells > 1 & Cluster ADC > 5*MIP (Purity ~ 67%) Efficiency and Purity of Photon sample % Charged hadrons are rejected by using thresholds on strengths and number of cells on PMD clusters. Raising thresholds on cluster ADC increases purity of photon samples. 7 February 8, 2008 Sunil Dogra QM2008 Jaipur 7 Data Samples AuAu (200GeV) : 1.8 M events CuCu (200 GeV) : 320 K Event cuts: Zvertex 5 MIP No of cells > 1 Charged tracks (FTPC): dca < 2 cm, nHits > 5, 0.1< p T than correlated term) part * dynamics almost constant at lower N part and increase for higher N part No pt dependence -> No abnormal correlations, induced by DCC An analysis to determine sensitivity of dynamics for DCC is ongoing