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Haixin Huang. Mar. 27, 2009. Polarimeter in APEX Session. RHIC CNI Polarimeter APEX. We used about 1.5 hours if excluding the first failed store. The idea is to fill RHIC with lower bunch intensity, and use different target sizes to study the rate dependence (instantaneous rate).
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Haixin Huang Mar. 27, 2009 Polarimeter in APEX Session
RHIC CNI Polarimeter APEX • We used about 1.5 hours if excluding the first failed store. • The idea is to fill RHIC with lower bunch intensity, and use different target sizes to study the rate dependence (instantaneous rate). • 109*109 of 0.5*10^11 intensity in both blue and yellow. • Eight blue targets were used in blue and seven yellow targets were used in yellow. Unfortunately, there are not big variation in the target size in yellow. The yellow study is focused on testing the new Si detectors (with a separated DAQ system put in on last maintenance day). • The results show that the rate problem show up with rate between4 to 5MHz. • The analysis of these data is underway to get a compensation scheme in place.
Comment on Rate • The rate in run6 was 1MHz at 100GeV with 111*1.5*10^11, emittance around 15 pi (quote the small IPM emittance measurement). • The rate in run8 was 3.2MHz at 100GeV with 109*1.7*10^11, emittance around 15-20pi. • This year the rate is 6-8MHz for 109*10^11 at 250GeV. • Sqrt (250/100)*sqrt(20pi/7pi)/1.7~5.1MHz. The rate is higher than this estimate even with the aggressive assumption of emittance reduction. We need to look for the source of the rate increase.