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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