In response to Flemming's email outlining the 'near term goals,' I.G. Bearden writes: > > ---------------------------------- > What rates can be expected? > The approximate formulae for collision rates is > N(ZDC)/sec == I(Blues)*I(Yellow)*Nbunches *3/40 where > I(Blue) number of Ions per bunch > > For typical value achieved so far this will give > N ~ 2-20 /sec; > Once the machine goes to 60 bunches the intensity should be 20-200/sec. > Last years rates at 10% luminosity was ~ 150/sec. > > Shifts should evaluate the rate from actual values given on screen > i.e. I(Blue)= TV-value / Nbunches (6) > If values are much smaller than this, and if smaller than other exp call > main control and discuss issue > (i.e. ask for MCR activity, request steering to up the rate) > > Run length > > To get a useable run for the spectrometers and DC one needs integrated > zdc-triggers in orders > or 200,000 to 400,000 i.e with 6 bunches hours of beam (1 hour > may yield up > to 36,000 events). > > First goals > > a) Zero field run for MRS @ 90 deg. Goal 1-2K tracks require ~400K > events. > b) Once completed same amount for A-polarity > c) Collect data for DC in present FS configuration i.e. 6 > deg, and FFS > at 15 deg. All no field running to check all chambers T3-T5 and > get straight througs. 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? 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. Whether the polarity is A or B is not so important, since we can only look at tracks, and not do any serious PID without momentum determination. > Second Goal > This second step is unlikely to be complete before end of weekend, but if > goes well. > 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. > This sounds good, but why not do this at 4 degrees. That way we have both commisioning data, and we start to 'redo' last year's run. > On MRS collect high statistics on 90 deg 2A/2B and 4A/4B to check out > systematic features with new tof wall. > By high statistics is meant about 1M events per setting. This is not quite > enough for a physics result with the > still wide vertex, but should enabled to setup timing for TOFW, check > tracking etc. > > Once T1 is alive one can consider to move to 4 deg, to have at least > acceptance overlap with the > 2000 data settings both A and B polarity. One should record about a factor > od two more > statistics with A pol (i.e negatives) than for B positives. > Yes, this sounds fantastic! > > Are there any estimates as to when T1 will be ready? Thanks for the update, and best regards, Ian
This archive was generated by hypermail 2b30 : Sat Jul 28 2001 - 05:39:39 EDT