From: Ian Bearden (bearden@nbi.dk)
Date: Thu Jan 30 2003 - 08:03:59 EST
Hi Dana, Do you understand why the background is so much worse now than last year? We ran last year with C1 down to 3 degrees with no big problems (at least they were not so big that we became aware of them...), and now there are fewer 'real' tracks per event (that is, in Au+Au at small angles last year, we had a mean # of reconstructed tracks of almost 2, i think, whereas this year it is roughly 1 and now we can actually trigger on tracks) so the problems must come exclusively from the large background. It seems really odd to me, since I would expect (naively) less background from d than from Au, and less background with shielding than without. I am not arguing that we should keep C1 in, though I would argue that we should keep H1. Still, I wonder if anyone has any explanation for the worse environment and whether there is anything that we can do to ameliorate the situation. Cheers, Ian On Thursday, January 30, 2003, at 01:59 PM, Dana Beavis wrote: > There may be an additonal thing to consider. At what angle/ field > settings > should C1 be removed. I am sure that the material causes interactions > and > multiple scattering. A new set of extension bars were made for this > years > run which allows both C1 and the multiplicity array to be moved > out/serviced > at the same time. The same thought may occur for H1. > dana > > ----- Original Message ----- > From: "Ian Bearden" <bearden@nbi.dk> > To: <brahms-l@bnl.gov> > Sent: Thursday, January 30, 2003 2:34 AM > Subject: C1 > > >> I am sending this to the list to 'advertise' the usefulness of the >> elog, and so that other people who are involved in this can see what >> happened. We have had some problems with calibrating C1, but looking >> on Wed. day entry in the elog I find a nice writeup with scope >> pictures, explaining that the problems may come simply from the number >> of particles in C1. The calibration was attempted using data with the >> FFS trigger (trigger 6), but in such events there are (evidently) too >> many pions in C1. We will try to look for the 1 p.e. in min bias >> events. >> So, thanks to Ramiro for clearing this up. >> And thanks to Hiro for providing the wonderful elog. Now if we could >> just pry that paper log book out of Flemming's hands, all would be >> well:-) >> Cheers, >> Ian >> > >
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