Notes from Main Injector/Recycler Group Meeting Wednesday 16 October 2002 Bruce C. Brown Krish Gounder -- Most Recent Large RR PBar Shot The PBar shot which is currently circulating came from transferring a substantial stack from the Accumulator into the RR Stash. Problems in synchronizing properly the RF manipulations after a few of the shots resulted in an overall transfer efficiency of about 61%. After cooling hard a horizontal instability developed which resulted in one event with a substantial loss and another event with a small loss. After the cooling was well established (but the intensity had dropped) the lifetime was 112 hours. The lifetime as measured from shortly after the end of transfers (including the two instability losses) was about 92 hours. Dan Broemmelsiek -- Progress in Cooling Large Stashes It's hard to cool lots of PBars. The .5-1 GHz momentum (longitudinal) cooling system in now in operation after addition of the required bandpass filter. Ralph Pasquinelli is doing the thorough checkout of all components of this system. Do to the observation of an instability, the horizontal system has been turned down a bit. Krish Gounder -- Study Plans General -- Try to keep the present PBar Stash in the RR, adding from the bottom of the stack on most TeV stores and sometimes adding more from dedicated RR stacking with the goal of achieving 200E10 PBars. We will seek to continue working on this goal until a tunnel access cannot be avoided. During this period with PBars in the ring, we will try to continue machine studies. A list is available. [Krish's Study Plan slide is available: http://www-ap.fnal.gov/~bcbrown/MtgNotes/KG_RR_StudyPlan_Oct2002.ps or as http://beamdocs.fnal.gov/DocDB/0003/000384/001/KG_RR_StudyPlan_Oct2002.ps ] PBar Studies -- These include Cooling Tuneup, Lifetime vs. Chromaticity, Lifetime vs. Tune, .... We would like to get a measure of the beam size by scraping the edges (without MI Ramping) to lose up to 10% of the stash. Proton Studies -- The usual list will be worked on when we no longer have PBars in the ring. These include heating studies and Main Injector Ramp effects. Discussion -- John Marriner suggested that we make PBar beam requests to the PBar Source in terms of desired emittance (perhaps 10 eV-sec) rather than request an intensity. Bill Foster observed that if we are managing our stash with adequate barriers, we can fire the kicker twice -- once before and once during injection -- without loss. If we do have DC beam, we can measure it. If the mechanism which creates DC beam is fast, we will loose it twice, but know that we are doing so. If it is slow, we can separate the DC beam loss from the other contributions to transfer inefficiency. Shekhar Mishra -- Plans We will have another PBar transfer tomorrow evening. John Marriner will be making preparations by examining the sequencer setup in consultation with Cons. We will have to reduce the time gap for the cooled stash by a large amount. Perhaps we will try to get a brief period with no MI Ramps to allow longitudinal cooling to reduce the momentum spread so that the DC beam created in this process is minimized. Fred Mills -- Induced Fields in the Recycler The general accelerator physics considerations were presented for how the MI affects the orbit, momentum and tune of the RR beam. Please see the note attached at http://www-ap.fnal.gov/~bcbrown/MtgNotes/FEM_Note_on_Induced_Fields.doc or http://beamdocs.fnal.gov/DocDB/0003/000384/001/FEM_Note_on_Induced_Fields.doc The meeting was ending in time for the Beams Division Champaign Celebration for the achieving 5 inverse p-barns of integrated luminosity last week.