Minutes of the July 20, 2007 Tevatron Dept Meeting https://indico.fnal.gov/conferenceDisplay.py?confId=1052 * Weekly Operations Summary (C-Y Tan) - The Tevatron delivered 31 pb^-1 to the experiments over the past week. There were 7 stores with initial luminsoites between 133 and 206 ub^-1/s - 2 stores were terminated unintentionally. Store 5553 was lost (no quench) after 14.5 hr when communication was lost to the $C2 crate; store 5554 was lost after only 12.9 hrs when cryo crate @ E2 lost power and caused a quench. For store 5551, approximately 1/2 of the D0 vertical angle change made the previous week was removed to eliminate very high losses @ C49 at low-beta. In store 5552, the protons blew-up by ~8 pi when the helix was opened at 150 GeV, presumably due to incorrect chromaticity settings - the resulting proton efficiency and lifetime were terrible. In store 5559, the pbar emittances were blown-up by a B17H separator spark during acceleration; there were 2 other separator sparks during HEP possibly aggravated by lightning during strong thunderstorms passing through - it's a wonder how that store lasted for an intentional termination. Store 5562 turned out to be a 36x35 store - 1 pbar bunch was lost in the MI and the first 2 pbar transfers had larger emittances due to other problems in the Recycler -> MI transfer. Problems with reverse injection while tuning up for store 5559 were traced back to a Main Injector studier who did not restore changes made during the study. The A4 cryo vacuum suffered greatly after a power glitch/lightning caused the A43 turbo pump to fail; an access was needed to replace that pump and the E27 pump as well; there is likely a leak in A4 that the A43 pump was overpowering. * Low-Beta Optics Measurement (Alex Valishev) - Alex completed differential orbit measurements on the central orbit to complement the proton helix measurements made 2 weeks ago. The CDF beta* is 10% larger than measured 1 year ago, while D0 is a few % larger. There are no large sources of normal quad gradient errors, but there are several locations with large skew quad errors that contribute to the larger beta*. The well-known rolled quad @ D16 seems to have become worse - that skew error is equivalent to a 47 mrad roll! There was some discussion on what can be checked before the long shutdown... is it possible the problem is internal to the quad necessitating replacement? The skew errors in A-sector likely arise from feeddwown effects from orbit changes through sextupoles. We may be able to correct the A-sector effect, but the coupling from D16 probably can only be fixed by unrolling the quad during the shutdown (which we were planning on doing already - D1 has to be warmed up to 300 K for that). * TBT Low-Beta Optics Measurement (Eliana Gianfelice-Wendt) - There are still some problems with the delay settings used to ping the beam vetically via the C101 application, but Eliana was able to acquire data with both horz and vertical pingers for central orbit and proton helix. Eliana's measurements confirm Alex's results - the beta* values are larger now and there are larger point sources of coupling relative to her last measurments in Sep 2006. * New E17 Schottky Electronics (Ralph Pasquinelli) - The new CERN-style processor electronics were installed in E17 a couple of weeks ago, while the new lower-gain preamps were installed in the tunnel last week. The system is operational and working nicely. Saturation is no longer a problem, so we can usually get reliable tune measurements very quickly. Ralph will work on understanding a couple of curiosities and testing a way to track the tunes up the ramp. * Observations with VTICK (Seva Kamerdzhiev) - Seva presented some interesting observations of the Schottky power when using VTICK (vertical tickler) to measure tunes with the digital tune meter. He uses VTICK for very brief (few seconds) measurments during HEP stores. In January, the Schottky power would increase by 6-9 dB when VITCK was turned on. Since then, the Schottky powers have been increasing gradually more and more when VTICK is turned on. No intentional changes have been made to VTICK or the 21 MHz Schottky system, so these changes are curious. Valeri suggested that the chromaticities are a bit lower so that we are closer to an instability threshhold. * Plans for Next Week (All) - Keep delivering luminosity to CDF and D0 as we get close to the shutdown. - Proton-only studies as needed to work on understanding the low-beta optics - 3-bumps through the identified point sources of coupling - Test any proposed corrections - Include AC dipole measurements to complement where appropriate - B0 and D0 aperture scans - Chromaticity Tracker - New collision helix (last thing before shutdown)