Dear Colleagues I have looked at some of the FFS data from the 20 degree setting. I find that for 46000 accepted trigger 6 events (from the first 5 sequences of run5712) there are 2600 matched tracks. So, now we have about 1 track per 18 (let's just call it 1 out of 20). At 12, this was ~1 track per 10 events. Also, my gut feeling which I have yet to quantify precisely, is that at 4 degrees we had roughly an id'd pion for every two tracks. I suppose that as we move toward midrapidity this fraction increases (simply because there are fewer tracks and rather less background) so that at 20 or 30 degrees things should be much cleaner. I see that since I came in this morning, a run with B polarity has been taken. I'll try to look at that and see that the rate is the same (of course, it should be since approx. all tracks are pions, but I'll check anyway...) Note that with these 20 degree data, with the magnet settings used we cover a pt range up to pt~2 (with TOF PID) and higher for pions using C1 (though the statistics are not so good here, since the distribution peaks at p=1.5=>pt~500MeV and falls exponentially.) I think that this implies that a high pt measurement should be made at a more forward angle using the entire FS. Ian
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