A60 tank #4 was cooled down to 80 Kelvin overnight. Once it was cold and the feedback loop regulating it was encouraging to see the tank pressure decrease as the temperature dropped - indicating the presence of lN2 (rather than just cold gas) flowing through the tanks. This morning the lN2 was disconnected and the piping pressurized to 50 psi with helium. After 10 minutes in this state there was NO indication of helium on the RGA nor of increasing vacuum pressure. Conclusion - tank 4 is now leak-free. For the remainder of the day and overnight, tank 4 will warm back up to ambient temperature. Warm nitrogen gas is flowing through the cryo pipng to hasten the warm-up. Sector 60 is being prepped for a bake which will begin in the morning barring unforeseen problems. The bake will consume the weekend. Once the bake has started and is stable, the need for accesses should be minimal until it is complete - then one shift will be required to undo the bake, hook the stochastic cooling equipment back up, etc. When will stacking start? Probably Monday afternoon/evening. Regards, Elvin ------------------------------------------------------------------------- ------------------------------------------------------------------------- Summary of E-835 Meeting 3/30/2000 Present: Rosen, Kasper, Graham, Seo, Vidnovic, Roethel, Joffe, Gollwitzer, Stancari(M), Stancari(G), Garzoglio, Boca, Negrini, Baldini, Marchetto, Obertino, Legger There was some discussion about the long-term. We have lost essentially all of March and we need to understand the longer term to decide how to spend our time. The spokespeople need to get an understanding of the likely use of the pbar source between now and June by the time of the group meeting. Keith said that data on disk from Jnauary-February would be removed. The data will be (has been?) put on tape. Giulio gave a presentation on some beam work that needs to be done and some measurements that he feels we should make periodically to check "things". Work: The orbit correction to put the beam at the height of the gas-jet needs to be incorporated in the ramp. This does not need luminosity - it can be done using the BPM's - and can be done with pbars or reverse protons. He anticipates 8 hours to do this through the energy range. Measurements: Lattice: Giulio says that the lattice needs to be measured at relevant ramp points to give an estimate of the systematic energy error at different energies. Giulio suggests psi'(6200), chi-1 (5500) and 4858 (the lowest point on the ramp). Each point takes about 4 hrs and relevant points could be taken once per 3 to 4 weeks. This will also exercise the BPM system. Eta: (conversion between frequency spectrum and momentum spectrum) Giulio says that we should measure eta along the ramp to get an accurate estimate of the beam momentum spectrum (shape in momentum space). This takes about 2 hrs/point, can be done with either protons or pbars and should be done also every 3 to 4 weeks. Run Plan A list of requests for special data or time during the coming stack, expected to be ~10 mA was collected. The stack may come on Tuesday. It was agreed that the energy should be at the psi-prime peak. It is expected that changes will be made to the: VLPC pedestals settings (to reduce spurious data), Neutral Trigger Thresholds (to compensate for high voltage changes on CCaL) Charged Veto width (will look on scope at triggering events) Also, the window on the center luminosity monitor will be tuned (the detector has been moved); this is done on the PC. This is the list of requests with luminosities, times and/or no. of events as best I understand it. The order below is a suggestion. Please correct any request that I have misunderstood, add any request that I have omitted. I expect we will discuss the order again on Monday morning. (the quantity not in parens is the driving condition) - Time does not include full overhead to go from one trigger or luminosity condition to another. Data Type/Requester Luminosity Time Events Establish Standard Running - 0.5 mA (2hrs) (standard triggers) No changes from last stack (to tape) /Stephen Phi-Phi trigger/Wander low (2hrs) 1 tape Min-bias to check above/Wander low (1hr) 500,000 >> Change thresholds on neutral (none) 2hrs (none) >> trigger and pedestals on VLPC's Min-bias (after changing low ?? ??? thresholds)/Jason Charged Veto Timing (neutral low 1hr scope study.. veto) Michelle/Wander Standard Data/everyone 2.5mA (2hrs) check new settings Random Gates only/Michelle 3*10^31 (1hr) few thousand (may be postponed) Min-bias timing data/Jason low (2.5hrs) 1,000,000 (total) (1/8 CCaL on) High jet Density test/Stephen as high (2hrs) 0.5 mA as possible VLPC Adjustments/Wander ?? 2hrs ?? Phi-Phi-gamma software/Flavio low 8hrs ??? ------------------------------------------------------------------------- ------------------------------------------------------------------------- Addendum to minutes of 3/30 meeting 3/31 I failed to include that there are now four new data sets that can be reached from the Numbers & Information box on our Home Page Gabriele has added a page that gives information of run, luminosity, energy (nominal and measured)..it is called "Overall Table". He has also added a page with the offline calculations of the beam energies (same numbers as in the previous page) and some luminosity weighted averages; this is called "Offline calculations of beam energy". David has produced a page called Log of Luminosities which has - indeed - the luminosities of the various runs with beam energy and instantaneous luminosity. Keith has made the shift summaries available from this box, too. Stephen