Subject: Minutes of the Tev Dept mtg, Apr.4, 2003 From: Vladimir Shiltsev Date: Fri, 04 Apr 2003 15:12:56 -0600 (CST) To: tevatron , annala@fnal.gov, bhanna@fnal.gov, bollinger@fnal.gov, cytan@fnal.gov, erdelyi@fnal.gov, garbincius@fnal.gov, jansson@fnal.gov, jwalton@fnal.gov, kipster@fnal.gov, koch@fnal.gov, martens@fnal.gov, mccormac@fnal.gov, meiqin@fnal.gov, pmivanov@fnal.gov, ranjbar@fnal.gov, rivetta@fnal.gov, ronmoore@fnal.gov, vs , stefanski@fnal.gov, steimel@fnal.gov, still@fnal.gov, tjohnson@fnal.gov, tsen@fnal.gov, val@fnal.gov, volk@fnal.gov, xiaoam@fnal.gov, zhangxl@fnal.gov CC: tevcc , balbekov@fnal.gov, burov@fnal.gov, cheung@fnal.gov, church@fnal.gov, drozhdin@fnal.gov, emclark@fnal.gov, finley@fnal.gov, frankz@fnal.gov, fritzd@fnal.gov, frs@fnal.gov, gena@fnal.gov, gromanov@fnal.gov, holmes@fnal.gov, khabibul@fnal.gov, marriner@fnal.gov, mhuening@fnal.gov, mokhov@fnal.gov, mont@fnal.gov, roger@Fnal.gov, scarpine@fnal.gov, slaughte@fnal.gov, spalding@fnal.gov, stephen@fnal.gov, syoon@fnal.gov, syphers@fnal.gov, vaia@fnal.gov, webber@fnal.gov 1. Vladimir informed that 7 Tev people will attend PAC and 2 will attend HALO'03/Beam-Beam'03 in BNL in May. 2. Mike Martens was OFF after sleepless night, so Vladimir briefly described situation with stores - there were problems with dampers (still not completely resolved) and orbits. After smoothing orbit early this week we established a good store with L=32e30, unfortunately, we lost store yesterday due to losses on ramp at 500GeV. MM, JA, DB, DS still investigating before the next store. Tan rules out beam coupling as a reason of the damper problems (beam becomes unstable horizonatlly when vertical damper is turned ON). He wants to do TDR measurements and(if possible) survey of the vert pick-up/kicker to make sure that nothing bad happened mechanically. Ray S asked whether all orbit/corectors data being saved in SDA for each store and the answer was "not yet" (MikeC/Jean) 3. Peter shown results of recent studies of beam stability vs position in F0 Lambertson which indicate that chromaticity thresholds are very dependent on distance between the beam and the laminations (so, beam is extremetly stable in the center of the field free region, and unstable in the notch). P-Beam has to be in the notch during unjection (injection bumps) and is only only 9 mm from laminations while we inject pbars. Current understanding of the Tev impedance: we have about 1MOhm/m due to resistive walls, we HAD about 1MOhm/m in three C0 Lambertson magnets (now removed), and depending on postion in F0 lambertson its contrubution varies between 1 to 3MOhm/m. SS or copper stip (0.2-0.5 mm thickness) covering F0 magnet laminations would eliminate the impedance completely. Peter aslo demonstarated that with 5A in OZD octupoles record high intensity beam is stable even at negative chromaticities (-1, -2). ANother conclusion: stability threshold for 36 bunches is not much different than for a single bunch (with the same N_p/bunch). Mike C suggested to make careful aperture scan to determine exactly where the beam is at injection and after helix is opened. 4. Tan got quite promising results on Signal-to-Noise ratio for his tunetracker - he used HA15 pick-up as a kicker fed with -20dB sine wave and observed good clean line in A17 Schottky pickup signal. No emittance growth observed during 5 min operation with -20dB signal. 5. Tan also installed 53 MHz quartz filters on the BPM cables and, thus, made coalesced bunch signal ringing as it'd be a very long train of uncoaleced bunches. As the result, the BPM postion signal is nice and stable and easy to sample. More investigations/comparison with existing BPM electronics to follow (with the goal to be able to use BPM data for coalesced buches for obrit smoothing - e,g,. during stores ) 6. Vladimir made first look into new E17 Schottky signals and found a bunch of strange lines in spectrum. Power in the Pbar Hor betatron band at 980 GeV behaves in a completely different way wrt effective emittance. Futher improvemnts are needed. He also mentioned that the SyncLite emittances in stores #2377 and #2385 grow by factor of 2 slower than necessary to explain effective emittance (N_p N_pbar/Lumi) growth. [Paul had some resrvations about that - to be resolved]. Pbar removal at the end of store can shed light on the SL emitances. Finally, he analysed Stephens data on beam centroids at 150 p and pbar helices and found that FW postions are 10-30% off (overestimate) the Tevatron helix models. Direct bump measurements and installation of QXR quads near FW (to measure beta-functions) should help to calibrate FWs better.