Minutes of the Nov 18, 2005 Tevatron Dept Meeting * News (Ron) - There will be no meeting next week due to the Thanksgiving lab holiday. (Enjoy your turkey!) Two weeks of pbar source studies begin Dec 5. There will limited pbars for HEP. The Tevatron will focus on delivering several special low luminosity stores for the CDF and D0 diffractive physics programs: 36x36 lumi = 1 E30 cm^-2 s^-1, 1x4 1.6 m beta* (our normal optics at 980 before the squeeze). Intermixed with these stores will be regular HEP stores (with whatever pbars are available) and hopefully some Tevatron studies. * Weekly Summary (Jerry for Andreas) - The week started out well, but a series of problems developed. There have been 5 stores this week - the 4 prior to an access period were terminated intentionally, and the fifth is in progress. Store 4495 set a delivered luminosity record of over 6.6 pb^-1 (averaged over CDF and D0). There was downtime to complete safety system tests and perform minor jobs in the tunnel. Unfortunately, an RGA head on one of the B11 separators developed a leak that spoiled vacuum by 4 orders of magnitude (up to 10^-5 torr). Many hours were spent identifying and repairing the leak as well as reconditioning those separators. Vacuum has still not recovered completely; the likely culprit is outgassing of adsorbed gases that accumulated on nearby cold beam tube during the leak. There were also various problems with low beta quad power supplies that were fixed. The TEL tetrode tube is dying and requires a 4 hr access into Transfer Hall for replacement. During one store, the orbit stabilization program was unintentionally killed, and there episodes of high losses before collimators were adjusted and the application turned back on. A newly-created ACNET device will alarm if the orbit stabilization program stops making corrections. Store-to-store orbit variations have been occasionally causing higher than normal losses at the start of HEP stores because the tunes land in bad places; we may allow the orbit stabilization program to smooth to a set reference orbit instead of keeping the orbits where it finds them. * Tev Alignment Tasks for Long Shutdown (Jim Volk) - The alignment group wants to do a level run around the Tev and to remeasure all magnets in 2 sectors, in addition to other minor jobs. Presently, there is no strong correlation between corrector currents and misalignments, so there is no plan to adjust positions of any magnets, except for known quads with large rolls (D16-1, A39-1). * New Instrumentation for Studying D0 Quad Motion (Todd Johnson) - During this week's accesses, Todd installed some new devices to help us try to understand why the D0 quads move around so much. He installed a temperature probe near the Q3 in the Tev tunnel, a temperature probe within the Q4 shielding in the D0 hall, and a differential thermoanemometer (it's a rather nifty device) within the shield wall to measure air exchanges between the Tev tunnel and the collision hall. (LVDTs between the girder and the Q4 did not get installed, and 2 other temperature probes on the girder itself can not be read out at the moment.) He has already observed interesting correlations between the air flow and quad motion. The temperature probe behind the Q4 shielding shows several degree swings in a matter of minutes, the same time scale on which we could see orbit motion in the arc without orbit stabilization. We'll continue to watch and learn; we should sit down with D0 experts to correlate these temperature and air flow changes with their collision hall HVAC. * Synchrotron Bunch Motion @ 980 GeV (Alvin) - Bob Flora added a new scope to the SBD system that can be used parasitically to acquire waveform data periodically. Alvin has used this scope to look at the evolution of a few proton bunches over a store. The longitudinal bunch profiles were fit to a Gaussian function, and then had FFTs performed on the center positions, widths and amplitudes. One sees peaks at the expected frequencies for dipole or quadrupole oscillations, and there are interesting features. Some peaks disappear over time early in the store (dampers doing their job), but others come and go. There is surely some coupled bunch phenomena going on, so it would be nice to have a scope with much more memory so that all 36 bunches could be sampled simultaneously. They are thinking about experiments that could be done, e.g., turning the longitudinal damper off/on for small periods of time. * Plan for next week There wasn't much opportunity for studies this week, so the list is quite similar to last week: - TBT measurements @ 150, 980 GeV (Yuri, Frank, Eliana - proton-only 2 hr) - Differential Chromaticity Octupoles @ low beta (Alex - proton-only) - Move proton tunes > 7/12 @ 150 (Yuri, Jerry - proton-only) - Crystal Collimator Scans (Dean - end-of-store) - Pbar Beam-Beam Tune Spread (Xiaolong, Vladimir, Seva - end-of-store) - Tune Mult Calibration (Ron - end-of-store) - Move proton tunes > 7/12 @ low beta?