The enclosed comments is not for the whole paper, but for a few selected sections mainly trigger Daq and the performance section. ///////////////// NIM comments Trigger + DAQ P 1. At full luminosity the Au-Au nuclear collision rate is ~ 1.2kHz of growing to ~ 25 cm over its lifetime of ~3 hours with the 200 MHz re-bunching in place. is readout, ~2500 channels of timing information from the drift- collision rates are modest in heavy ion collisions. The The first trigger is the most inclusive selecting not only all nuclear reactions, but also the electromagnetic dissociation peripheral collisions with the cross section of about 10.7 b[5]. The second trigger selects about 50% of the nuclear collision events. In the first RHIC run these two triggers were sufficient to collect all data of interest, since the machine luminosity only reached 10% of nominal. Thus all LVL0 triggers also acted as LVL1 triggers. Rewritten section In the 2001 run a centrality trigger is implemented to select the 10% most central collisions with high efficiency. It is be implemented by requiring a collision condition from basic BBC trigger, and then further requiring a large deposited energy in the Tile Multiplicity Array (TMA). This is implemented as a LVL0 trigger, and based on studies of data selects about 20-30 % of all nuclear events, and all of the 10% most central events. A first level vertex selection is available for high luminosities based on making a precise cut on a timing overlap between the left and right ZDC modules (using Constant Fraction Discriminators) to accept only events with a narrow vertex of +-20 cm. The combination of these allows to reduce the delivered interaction rate of up to ~ 1600 peripheral collisions to the rate of 100 to 150 events per second that the DAQ can handle. Spectrometer Performance "Even if this is good .." This sounds like competition and not as an experiment design criteria as it was - re-write to something like The PID at somewhat higher moment is achieved by adding the information from the C1 Cerenkov detector, and will provide pi/K separation in the momentum range ( 2<p<7 GeV/c [check numbers]). Figure xx shows a preliminary response of the C1 vs mass**2 as determined from the TOF at a forward angle of 4 deg. The pions in the energy range (xx<p<yy) [above p = .] give a significant signal in the C1 while the Kaons and protons do not. (add the fig from CE as suggested by JJ) Rich;; "low statistics prevents ." This sentence should just be dropped - Thye momentum acceptance for the setting used do no allow protons in a relevant range, so not a statistics argument] Possibly add momentum range in fig [ pRef==7.3 GeV , pmin= 0.6*Pref, pmax ~ 2*pRef] ------------------------------------------------------ Flemming Videbaek Physics Department Brookhaven National Laboratory tlf: 631-344-4106 fax 631-344-1334 e-mail: videbaek@bnl.gov
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