Hi Flemming I concur with your answer to Kirk on the 22 GeV running. As I see it 22 GeV is of marginal use for us (mostly mult. dist at SPS energy). We should not be overtly negative, but must stress that under no circumstances can this take more than 24 hr (real time) out of the program. It must also depend on the quality of RHIC beam from now up to the end, so that this is scrapped if integrated luminosoty over the next week is too low. As a matter of principle RHIC should have planned this earlier on. We must stress that we have made a plan for a particular run (high pt) , that needs all available lum. Had we known that the plan would be different, we might have started earlier. regards JJ ________________________________ Jens Jørgen Gaardhøje Assoc. prof. Dr. Scient. Chair Ph.D: school of Physics NBI.f.AFG. (secretariat. 35 32 04 41) Chair science committee. UNESCO Natl. Commission. (secretariat. 33 92 52 16) Office: Niels Bohr Institute, Blegdamsvej 17, 2100, Copenhagen, Denmark. Tlf: (+45) 35 32 53 09 Fax: (+45) 35 32 50 16 ________________________________ ----- Original Message ----- From: "Flemming Videbaek" <videbaek@sgs1.hirg.bnl.gov> To: <brahms-l@bnl.gov> Sent: Wednesday, November 14, 2001 3:24 AM Subject: Fw: RHIC Au x Au Running at 22 GeV > as promised my response to Tom Kirk. > Flemming > > ------------------------------------------------------ > Flemming Videbaek > Physics Department > Brookhaven National Laboratory > > tlf: 631-344-4106 > fax 631-344-1334 > e-mail: videbaek@bnl.gov > ----- Original Message ----- > From: "Flemming Videbaek" <videbaek@sgs1.hirg.bnl.gov> > To: "tom kirk" <tkirk@bnl.gov> > Sent: Tuesday, November 13, 2001 9:17 PM > Subject: Re: RHIC Au x Au Running at 22 GeV > > > > Dear Tom, > > > > Unfortunately, I had not heard this until your e-mail of this evening, and > > have not had a chance to communicate with the rest of the Collaboration on > > this, and secondly will not be at BNL tomorow until mid-afternoon and thus > > cannot attend the 1.30- meeting. > > > > Though not an collaboration agreed upon statement ,my first hand reaction > is > > summarized below. > > > > There is a physics merit to do such measurements, as discussed by Dima > > (Though I doubt high pt will be feasible > > even with the high solid angle by STAR and phenix). > > > > In the case of the BRAHMS detector with it's small solid angle > > a 24 hours run (12 hours beam ?) with beta* of 10 and reduced luminosity > > (1/gamma) , and shorter life time the use fullness of such beam is highly > > questionable . For a single setting e.g. at 90 deg or a single forward > spec > > angle > > we typically need ~200K central collisions (also dN/dy is lower by ~1/3). > > With a reduced rate .. this would > > take ~30 hours (with beam) for a single setting, and thus of marginal > > interest. > > > > We were in fact planning to collect in the remaining period high > statistics > > data to extend to high pt (3-4GeV/c) > > measurements at this point where the survey for low pt (.2-1.5) is almost > > complete. > > Given the choice I believe Brahms would prefer continuing the 200 GeV run > > particular in view of the concern given in the following paragraph. > > > > The amount of beam available in the last 1.5 week has certainly been quite > a > > bit less than anticipated, and with the unfortunate accident at STAR even > > more time is being taken out of the remaining time. A 24 hour run is a > > substantial amount of the remaining time. This, in particular if it mean > 24 > > hours of running , and not just a 24 hours time slot set aside to this. I > > do honestly fear, that if such period has problems there will be pressure > to > > continue outside such time and hope if agreed upon is real restricted to a > > fixed amount of time. > > > > best regards > > Flemming > > > > > > > > >
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