BRAHMS analysis meeting Friday 27 April 2007 ============================================ Submitted by Michael Murray Present: ======== Chellis, Flemming, JH, Kris, Hongyan, Ramiro, Dipali, Pawel, Alte, Natalia and Pawel and Peter I think. Agenda: ======= http://indico.cern.ch/conferenceDisplay.py?confId=15406 Update on p+p 200GeV Run V spectrum analysis K. Hagel TAMU Update on p+p 62.4 GeV Atle Qviller Oslo 62GeV pp at Krakow Natalia, Pawel Start of a pp paper: Flemming Action Items: ============= TAMU: Give Kris time for analysis Krakow: Try and find 10% difference with Flemming. Flemming will rerun data again since he wants to finalize spectra. Krakow: JH would like to see spectra with only CC vertex and only track vertex separately. Michael and anyone else: Submit abstracts to SQM07 Flemming: After final pass through with data Flemming will send spectra to Pawel. Kris Hagel pp_at_200GeV ==================== Cuts: • -15. < vz< 15. for 2255B; -10. < vz< 0 for ll h 90d iall other 90 deg settings • 2σcut on momentum dependent vyp y • 2σcut on vz-track vertex difference • Detectorcuts• Detector cuts –TPM1 -10 < x < 15 –TPM2 -16 < x < 18 –Tofw 40 < slatno < 80 eliminates a bunch of dead slats • 2σmomentum dependent pid cuts He is using "on the fly" acceptance correction. Kris has y dependent momentum cuts. He still sees low Pt dips at all settings. JH thinks it is a momentum resolution problem. Ramiro thinks the problem is that the two sigma cut on the vertex is two tight. For B setting the high field setting is somewhat lower than the 1050 setting Comparison to STAR: Pions about 15% higher, kaons perhaps lower and steeper then STAR, protons tend to be higher. Flemming says the only one that we can compare to is the Kaons. STAR tries to measure "direct" protons. Note above one GeV they see proton protons than us since they reconstruct those that are decay products from lambda's. Note PID cuts are 2 sigma as a function of Pt. JH asks if this function is consistent with data. Flemming wonders weather 2 sigma is too tight. Alte: RICH PID • Direct pions: 520 GeV/c (typo in last pres) • Direct kaons: 1020 GeV/c • Direct protons: 1530 GeV/c • Indirect protons: 1020 GeV/c • The proton PIDs overlap in momentum and and the only effect to be subtracted is meson contamination from ring0 hits • All settings work with n=1.0018 Direct and indirect proton spectra match well. At y=3 proton spectrum is well fit by a Boltzman for 0.8<Pt<1.5GeV/c H2+RICH PID • Pions are identified with RICH • Protons are identified in H2 • Kaons are seen indirectly as ring0 particles 5 to 7GeV. • Correct for protons not identified in H2 and 3% ring0 pions. Flemming says at 6-7GeV kaons/protons start to overlap in TOF. Be careful about this. Onut and Flemming have 2 different methods. • Ring0 pion contamination is subtracted from indirect kaons Pions at y=0 look nice. He has looked at T2 dips in reconstruction efficiency. This seems to be handled correctly. 2B1723 setting yield is systematically 20% below 3B setting. Slopes look equivalent. No problem for corresponding 2&3A settings. At y=3 he does not see a power law in the spectrum. Flemming notes that there is probably no hard scattering component there and perhaps we should fit with a gaussian in pt as was done at the ISR. Action Item: Fit spectrum to gaussian in Pt. Krakow pp_at_62GeV Pawel and Natalie. She has a reasonable aggreement with Flemming for pi- at y=3. (The ratio is stable at 1.1). They use the CC vertex information when they have it. Note at high Pt conservation of energy makes CC vertex inefficient. They will make an analysis without requiring the CC vertex. Action Item: Try and find 10% difference with Flemming. Flemming will rerun data again since he wants to finalize spectra. Action Item: JH would like to see spectra with only CC vertex and only track vertex separately. Flemming: Figures for a future pp paper: Inverse slope parameters for pions start at 180MeV at mid-rapidity and drop down to 100MeV at forward rapidity. He has comparisons to pQCD for pions. Vogelsang has promised to give predictions for kaons but we will not bother for protons. Proton dN/dy distribution is consistent with a flat distribution in X and constant Pt. Remember these are not final data, Not to be shown at SQM07. _______________________________________________ Brahms-l mailing list Brahms-l_at_lists.bnl.gov https://lists.bnl.gov/mailman/listinfo/brahms-lReceived on Fri Apr 27 2007 - 13:26:13 EDT
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