Hi Let me remind you just in case about the pp-presentation I made at the May meeting http://www.nbi.dk/hehi/research/brahms/collab2002/videbaek/PP-analysis.pdf which outlines how and with what accuracy one can get a rough vertex from the Inel counters. What has been learned since is pretty much in the realm of Kris's analysis, and I should really let him answer more of this - he may even send you a draft analysis report on the progress of which parts will show up as the monthy progress report beeing gathered. The inel counters are a problem in the early part of the run e.g. I do not think that in the end we have any low field running for MRS at 90 deg with good Inel counters. I do not have the run number handy right now from which it is good. For doing ratios too we have also to redo the evaluation of contamination of background protons, of which I believe many more are introduced due to the start counter. One strong indication of such knock-out processes are the presence of lots of rather low-momentum deuterons - see the last plot in the above mentioned presnetation. I would not be surprised if phenix has not evaluated the background properly (they also had a counter installed for t0) Flemming ------------------------------------------------------ Flemming Videbaek Physics Department Brookhaven National Laboratory tlf: 631-344-4106 fax 631-344-1334 e-mail: videbaek@bnl.gov ----- Original Message ----- From: "Ian Bearden" <bearden@nbi.dk> To: "Brahms-Dev-L@Bnl. Gov" <brahms-dev-l@bnl.gov> Sent: Thursday, September 12, 2002 6:13 AM Subject: p+p data > Hi Deviants, > We'd like to take a look a couple of things in the p+p data, in particular > we'd like to check the pbar/p ratio to see whether the ultra preliminary > BRAHMS result of 0.8 is correct or if the PHENIX 0.6 value is reasonable. > We are looking at the DSTs made by Kris (thanks!) I have a couple of > questions: > 1. Do I recall correctly that only H2 has been calibrated? > 2. How does one get a 'reasonable' collision vertex...or is it not possible. > I know that the TOF info comes from the added scints at the fronts of the > spectrometers, but is it possible to use the inelastic counters to get a > vertex? > > Probably this has been written to the list by someone already and I missed > it, if so, please point me to the appropriate email in the archive... > Cheers, > Ian > > -------------------------------------------------------------------- > | I.G. Bearden | > | Niels Bohr Institute Tb 3 email: bearden@nbi.dk | > | Blegdamsvej 17 phone: (+45) 35 32 53 23 | > | København Ø FAX: (+45) 31 42 10 16 | > | Danmark Www: http://www.nbi.dk/~bearden | > -------------------------------------------------------------------- > > >
This archive was generated by hypermail 2b30 : Thu Sep 12 2002 - 09:16:07 EDT