Minutes of the 21 Dec 2007 Tevatron Dept Meeting http://indico.fnal.gov/conferenceDisplay.py?confId=1456 * News - The Tevatron will be down until approximately New Year's Day. A4 needs to be warmed up to room temperature to identify/repair/replace an apparently broken component between the A44 and A45. There is a helium-to- cryostat vacuum leak that likely contributed to or was caused by the A4 quench that ended store 5813. * Weekly Operations Summary (Jerry Annala) - The Tevatron delivered 32.1 pb^-1 over the past week. There were 7 HEP stores with initial luminosities from 168 to 210 ub^-1/s. Three of those stores ended unintentionally - store 5805 ended after only 1.7 hrs when the A3 wet engine failed; store 5811 ended after 3.2 hrs when the C4 cold compressor failed; store 5813 ended after 14 hrs when A4 cryostat vacuum degraded following a power glitch that tripped off the A43 roughing pump and eventually led to a quench. Other issues this week: many processors for QPMs, SBD, and FBI required reboots (network problem?); the trigger module for the E48 pbar injection kicker was replaced; the water pump for the A0 compressors failed; the E4 BLM lost its limits leading to false aborts during proton loading (restoring fixed the problem). It was thought there was a failed surge resistor in the C17 separators, but after replacement, the old one was found to be OK - perhaps not a hard failure. We continue to mis-steer pbars intentionally during transfers to blow-up their emittance to help reduce the proton/pbar emittance difference and improve proton lifetime. Store 5809 was an interesting data point - the pbar emittances were blown up the ramp so that the pbars were much larger (~40%) than typical for collisions. The proton lifetime and losses at the experiments were much improved, even the luminosity lifetime was ~15% better, with little impact (5%) on the initial luminosity. In addition, there were essentially no proton losses during the squeeze. Jerry modified the pbar injection closure program to allow deliberate mis-steering by a programmable amount - it is ready to test. We continue to develop plans to blow-up pbars in a more controlled fashion either right before collisions or maybe just after acceleration. * D0 Beta* Update (Bill Lee) - Bill showed updated meaurements of the waist positions we implemented the alpha bumps before store 5780. The waists are now within +-2 cm of center - the bumps actually "over-corrected" by ~1 cm. The luminosity increased ~3%, but their measured beta* values haven't changed. In particular, the horz beta* is still larger than expected and shows greater variation over a store. * Nonlinear Optics Measurement with AC Dipole (Ryoichi Miyamoto) - Ryoichi showed some preliminary results from data taken at 150 GeV in Nov 2006 where he varied the AC dipole current to look at detuning for various driving amplitudes. He saw fairly good agreement between the observed vertical detuning (AC dipole is vertical only) and that expected from the dipoles, quads and octupoles for a 1 mm kick. Alex noted the sextupoles should also contribute, so the agreement could be better. Ryoichi also showed the amplitude variation of other modes - he sees evidence of the rolled quad at D16 (before it was unrolled). He estimates the BPM non-linearity contributes ~1% effect on his measurements. BPM rolls are not yet taken into account. * Recent Digital Tune Monitor Measurement (Seva Kamerdzhiev) - Seva showed proton vertical tune data from store 5813. Bunches 2, 6, 10 of every train show 2 peaks around 0.56. These peaks are not from 60 Hz electrical that is present (even without external excitation). Seva can provide such spectra easily during stores upon request. * Plan for Next Week - fix the Tevatron.