Minutes of the 10 December 2010 Tevatron Dept Meeting http://indico.fnal.gov/conferenceDisplay.py?confId=3879 * Weekly Operations Summary (Dean Still) - The Tevatron delivered 48.5 pb^-1 to CDF and D0 over the past week. There have been 11 stores with initial luminosities between 170 and 331 ub^-1/s. One shot was lost early in the ramp when an RF station tripped and the resulting DC beam caused a quench. Two stores were lost unintentionally: store 8331 aborted after 11 hours when the C4 beam valves closed to due a control crate problem; store 8335 ended after only 2.5 hrs when the C1 wet engine failed and caused a quench. The D11 power leads were repaired (again) - looks good now. EE techs repaired corroded water connections in the B0 low beta power supplies that were leaking and causing ground faults. The injection closure program mysteriously set the lambertson current to zero during a shot-setup and caused several beam aborts before the problem was identified. A dipole regulator had intermittent glitches during store 8340 which caused loss spikes and luminosity dips; it was replaced between stores. A trim quad regulator also was replaced. The D0 horz IP position adjustment is now limited by the HD11 dipole current. The E01H collimator was used successfully to capture losses during the squeeze to reduce losses at other sensitive locations around the ring. (See next entry.) * Collimating Squeeze Losses (Jerry Annala) - Trying to keep D0 (proton) losses low during the squeeze has become too difficult, so attempting (again) to use the E01H collimator (designed for proton removal) as a shield. Note that this scheme was attempted first in 2008, but after a couple of mysterious quenches during the squeeze, it was abandoned. At flattop and during pbar jacking, the collimator races in to a specified position and then moves more slowly under loss monitor feedback until a pre-determinied loss rate limit is reached. E01H is not used for normal scraping, so it is retracted fully before remove halo. This procedure has been used since store 8330, and it is showing very promising results. Losses are definitely caught at E0 and are reduced at the usual trouble spots around CDF and D0. E0 orbit bumps are used as to bring the beam closer to the collimator in the squeeze slots. It is interesting to note the make-up of the losses - there is evidence that the collimator catches losses from the main bunches, satellite bunches, and even some abort gap beam (generated how so soon after acceleration?). We should be able to tolerate higher beam intensities. * Plan for Next Week (All) - Deliver luminosity! - Continue tweaking squeeze collimation (Annala, Still) - Implement alpha bump at D0 (Annala, Valishev - proton-only) - Test fast access aggregate (Annala) - Test pbar longitudinal damper (Tan, proton-only) - Phase-shakng at flattop (Tan, proton-only) - Sextupole Mult Calibration (Valishev - proton-only) - Investigate Tune Spikes (Hanna - proton-only)