If you have followed the shift reports you will have noticed both some accomplishments early this weekend followed by a long down period. At present the accelerator maybe up to somewhere between 20-30% uptime, but with quite varied luminosity up to (initial stores) of 300 ZDC counts/sec ie. close to 25% luminosity. In the near future the RHIC acc will work on a)improved avaibility b) RF recunching c) reduce betastar while slowly injection more ions into the bunches. One of the implication for us is that with N(ZDC) >=100 it is becomes nescesary to utilise the 'centrality' trigger cutting down the overall DAQ rate to below 100 to keep a reasonable deadtime. Thus data will be biased towards central events. - Today was a scheduled shutdown which we utilized to i) install T3 following the repair of the broken wire. By sometime late tomorrow the HV can be turned back on and the chanber checked out ii) One removved si-det was reinstalled. iii) A failure of the 4032 was again seen today, but in a somewhat different mode- a simple recycling seem to solve the preoblem. The ZDC adc signal splitting has been completed, the noise reduced with a resulting good response for both low and high energy gain signals. The physics program completed during the last weeks is 1.5 M events for 40 deg 3A and 3B each (following the first 90 deg measureemnts) about 4.5 M events for 1/5B (proton prefered ) at 4 degree and 2.5M for 1/5A( setting). The immediate next set of measurements is to complete another 1+1 M events A/B for 40 deg and 2 M events for 1/5 A at 4 deg, hopefully within the next few days. Flemming ------------------------------------------------------ Flemming Videbaek Physics Department Brookhaven National Laboratory tlf: 631-344-4106 fax 631-344-1334 e-mail: videbaek@bnl.gov
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