Just before leaving let me add a few comments here. > This sounds really good, and will also allow us to start looking at H2. > Is there any estimate of how much 'no field' running we will do? Yes , the plan would be about 200-400 K. With the 6 byunches this is a good amount of beam time. It would > also be interesting to run the BFS with fields (after the needed checking is > done) to explore how to what extent we can use the BFS alone (and thus > collect data at forward rapidities in BFS while looking around y=1 in FFS. > >FFS is not so usefull for two reasons I) T1 is still in > > conditionin > > mode and ii) rates at 15 deg are very low. (400K events) > > > While it is true that the FFS is 'not so useful' without T1, we can still > start to > debug/understand T2, H1, and C1 even without T1 (and, alas, no momentum > determination). We can, however, only do this if D1 and D2 are on, so that > we have tracks in T2. I therefore request that we have D1 and D2 on at the > same field values as last time. This does not work at all for 15 deg. The mean p is about 1.5 GeV/c so if you went to the same field at last time you would see exceedingly few tracks. So the field has to be set for about the mean <pt> i.e. at 1.5/22 ==1/10 max field at most. Whether the polarity is A or B is not so > > Once c) is done move FS to 6 deg for both sections FFS and BFS. > > Goal is to commission t2-RICH; thus turn have magnets at 1/5 max field. > > Ramiro will provide proper values to set. At 6 deg this will pick > > the yield > > around <pt> of ~ 450 MeV/c. > > The rational given is that one expect T3 to start seeing increased background when you move to more forward angles, and I will argue strongly that you do not want to commision a detector under the more severe constraints, remember also for T1,T2 we will probably have at least 30% more tracks per event. For commisioning and tuning FFS I also think we are much better off with a somewhat softer momentum distribution at 6 degree since now you will have pions clearly below C1 threshold as well as above while for the last years setting essentially all would be above. Also before the machine goes to 60 bunches there is not a physics program for the spectrometers , even at the good intensity of 1200 10**8 B/Y ions the max rates are 6-8 /sec at the beginning of the fill.
This archive was generated by hypermail 2b30 : Sat Jul 28 2001 - 13:39:49 EDT