QM2002 (July / / Nantes / France)Susumu SATO (JSPS) for the PHENIX collaboration page 1 Susumu SATO Japan Society for the Promotion of Science, Research Abroad [BNL] for the PHENIX collaboration Measurement of identified hadron in pp collisions at = 200GeV

QM2002 (July / / Nantes / France)Susumu SATO (JSPS) for the PHENIX collaboration page 2 > p+p data gives foot of understanding of hadron production  spectra shape, particle yield, and particle ratio (in this analysis) > Experimentally, the same experimental detector setup and analysis software as those for heavy ion is desirable to minimize systematic uncertainty. > On the other hand, low multiplicity event tends to introduce bias for the event selection. Physics motivations and requirements to measure identified hadron in p+p > Phenix has introduced two of new “p+p dedicated” counters, in order to minimize trigger bias, (i) one is to cover more rapidity  NTC (1.2<|  <3.0) (Normalization Trigger Counter), and (ii) the other is T-zero counter (-0.35<  <0.35) to provide start timing for the tracks in the TOF stop counter acceptance, instead of BBC event start timing counter.

QM2002 (July / / Nantes / France)Susumu SATO (JSPS) for the PHENIX collaboration page 3 TZR BBC TZR TOF As ordinal event start counter (BBC) covers only forward (3.1<|  <4) rapidity, For the p+p collision, PHENIX has successfully operated track-by-track start counter (TZR) covering central arm (-0.35<  <0.35) where TOF (stop) counter has acceptance. This enables (i) analysis for events triggered by “NTC” counter(1.2<|  <3.0), and (ii) further study for the event bias. NTC [2 Start Counters] (i) T-zero counter (“TZR”) & (ii) Beam Beam Counter (“BBC”)

QM2002 (July / / Nantes / France)Susumu SATO (JSPS) for the PHENIX collaboration page 4 Particle identification by the flight time For each of positive and negative charged particles, in the momentum slices of  T, particle identification is done with f(x) = “3 gaussian (for , K, p) + polynominal (for back ground)” fits. The time difference,  T, between (i) the measured flight time and (ii) the expected time from measured path length and momentum are calculated for each particle.  For   For K  For p  For back ground

QM2002 (July / / Nantes / France)Susumu SATO (JSPS) for the PHENIX collaboration page 5 X-axis  T [ns] PID typical example (p =1.1 ~ 1.3 GeV/c [200 MeV/c slice]) Y-axis: yield [a.u.] ++ ++ via TOF-TZRvia TOF-BBC  - ++ ++ -- -- p p p-bar Both of the method gives good hadron identification. To study event bias etc., track-by-track starting (TZR) is needed.

QM2002 (July / / Nantes / France)Susumu SATO (JSPS) for the PHENIX collaboration page 6 In the following 3 slides (for pi, K, p respectively), the definition of identification are: in each of 4 graphs (positive via TOF-TZR, positive via TOF-BBC, negative via TOF-TZR, negative via TOF-BBC) (1)Upper points:  T upper boundaries for PID [ns] in 2 sigma (with 0.1 sigma as its error bar) from the mean for THE particle species. (2)Middle points:  T mean [ns] (with error of itself got during the gaussian fitting) for THE particle species. (3)Lower points:  T lower boundaries for PID [ns] in 2 sigma (with 0.1 sigma as its error bar) from the mean for THE particle species. Definitions of PID boundaries

QM2002 (July / / Nantes / France)Susumu SATO (JSPS) for the PHENIX collaboration page 7 RED: POSITIVE BLUE:NEGATIVE TOF-BBC TOF-TZR Y-axis:  T [ns] X-axis momentum [GeV/c] [Pion]  T boundaries In wide range of pt, >2 sigma separation is succeeded.

QM2002 (July / / Nantes / France)Susumu SATO (JSPS) for the PHENIX collaboration page 8 RED: POSITIVE BLUE:NEGATIVE TOF-BBC TOF-TZR Y-axis:  T [ns] X-axis momentum [GeV/c] [Kaon]  T boundaries In wide range of pt, >2 sigma separation is succeeded.

QM2002 (July / / Nantes / France)Susumu SATO (JSPS) for the PHENIX collaboration page 9 RED: POSITIVE BLUE:NEGATIVE TOF-BBC TOF-TZR Y-axis:  T [ns] X-axis momentum [GeV/c] [Proton]  T boundaries In wide range of pt, >2 sigma separation is succeeded.

QM2002 (July / / Nantes / France)Susumu SATO (JSPS) for the PHENIX collaboration page 10 [pion] Fitted PID boundaries (by second polynomial) TOF-BBC is used in this analysis for the PID and fiducial selection. Positive Negative

QM2002 (July / / Nantes / France)Susumu SATO (JSPS) for the PHENIX collaboration page 11 [Kaon] Fitted PID boundaries (by second polynomial) Positive Negative TOF-BBC is used in this analysis for the PID and fiducial selection.

QM2002 (July / / Nantes / France)Susumu SATO (JSPS) for the PHENIX collaboration page 12 [proton] Fitted PID boundaries (by second polynomial) Positive Negative TOF-BBC is used in this analysis for the PID and fiducial selection.

QM2002 (July / / Nantes / France)Susumu SATO (JSPS) for the PHENIX collaboration page 13 Fiducial cut Fiducial difference between p+p and Au+Au due to dead/inactive region gives ~13% error on the yield ratio. Common method with Au+Au data analysis is used.

QM2002 (July / / Nantes / France)Susumu SATO (JSPS) for the PHENIX collaboration page 14 p T [GeV/c] Correction function ++ -- K+K+ K-K- proton anti-proton

QM2002 (July / / Nantes / France)Susumu SATO (JSPS) for the PHENIX collaboration page 15 Pion particle ratio Stat. error: vertical line Sys. error: short horizontal line mark

QM2002 (July / / Nantes / France)Susumu SATO (JSPS) for the PHENIX collaboration page 16 Kaon particle ratio Stat. error: vertical line Sys. error: short horizontal line mark

QM2002 (July / / Nantes / France)Susumu SATO (JSPS) for the PHENIX collaboration page 17 Proton particle ratio Stat. error: vertical line Sys. error: short horizontal line mark

QM2002 (July / / Nantes / France)Susumu SATO (JSPS) for the PHENIX collaboration page 18 More o More than 10 times of the statistics, we have recorded. o Better calibration is in process for the wider range of kinematics coverage. o For further understanding, the event bias study with TZR and NTC is on going. More from