Minutes of the April 27, 2007 Tevatron Department Meeting https://indico.fnal.gov/conferenceDisplay.py?confId=770 * (Two-Week) Operations Summary (Jerry Annala) - Over the past two weeks, the Tevatron delivered 41 and 39 pb^-1, to the experiments. There have been 13 HEP stores with initial luminosities in the range 156 to 276 ub^-1/s. Three of those stores ended unintentionally - store 5395 ended in a quench when a CAMAC card in a crate with the A49 and B11 separator electronics failed and brought down the whole crate; store 5366 ended after only 3.7 hrs when the B11 horz separator sparked and drove pbars into the F4 collimators causing a quench; store 5376 ended after 7.2 hrs when the A4 QPM pulled the abort although there was no quench. The TRF7 PA was replaced after 3 consecutive stores with TRF7 sparks. The spurious A17H separator spark counts were resolved by adjusting the spark detector sensitivity. There have been several instances of pbar longitudinal instabilities early in stores - it is suspected that the proton longitudinal damper may affect the pbars when working hard to suppress proton instabilities - a check-up of the vector-summing of the RF system may be needed. The C101 application used to minimize coupling during shot-setup had not been working properly recently - an underlying library change likely resulted in stale BPM data being used - explicitly enabling and disabling turn-by-turn BPM mode within C101 fixed the problem. The B11 horz separator spark that ended store 5366 was likely instigated by that separator being run in the wrong polarity while recovering from the failed CAMAC crate that ended store 5395. The separators were conditioned for 4 hours after the lost store. The D17 vert separator #1 sparked twice during store 5368 - likely aggravated by the brief period it was on @ 130 kV (higher than usual) when entering and exiting conditioning mode for the A49 and B11 separators prior to that store. We are developing an ACL script to help adjust the proton tunes prior to a shot based on the available Recycler pbar intensity. * Helix Measurements in Squeeze (Alex Valishev) - Alex recorded separator voltage references at LBSEQ 15-17 and 23-24 where there are larger than desired losses. Assuming the "fudge factors" from low-beta are valid at the other steps, the minimum beam separations are likely smaller than desired. We hope to make helix adjustments to increase the separations to reduce beam-beam effects and the losses. * TEL-1 Studies (Seva Kamerdzhiev) - During recent in-store studies, TEL-1 has demonstrated successful lifetime improvement of individual proton bunches. Working on P1, P13 or P25, TEL-1 repeatedly increased lifetime 15-45% and reduced halo from those bunches. The benefit was seen with electron currents corresponding to (horz) tune shifts of 0.0010-0.0015 and smaller currents. Based on these positive results, it was decided to cancel possible upgrade work on the TEL-1 magnetic system planned for the long shutdown. Future study plans include using TEL-1 during scraping, try simultaneous TEL-1 and TEL-2 operation on a single bunch, compare TEL-1 tune shift with shifting base Tevatron tune, increasing electron beam size, study effects on emittance growth. * IP Bump Spreadsheet and New IP Devices (Ron Moore) - Ron added new worksheets to the TevCalculators excel file to help calculate the DFG changes needed to implement various IP position and angle changes at CDF and D0 @ low-beta. Inputs are the current flattop and low-beta slot DFG kick angles and the desired position or angle changes; output is the new DFG kick angles to enter into the low-beta slot. The worksheet indicates if DFG would be close to or over its current limit by highlighting the corresponding entries in yellow or red. New MACALC devices (C:B0XPOS, C:B0YPOS, C:B0XANG, C:B0YANG, C:B0RPOS, C:B0RANG) show the CDF IP positions and angles relative to the desired (center of the silicon detector). It's just a bit easier to evaluate those positions/angles with the known offsets taken into account. * Plans for Next Week - Keep up the delivered luminosity to CDF and D0. - New Sextupole Commissioning (proton-only, many people - try to get to the point of doing an HEP store with the new circuits at zero current) - TEL-1 studies (the usual gang - during HEP stores) - Chromaticity Tracker (Tan, proton-only) - P1 line matching with IPM (Andreas, proton-only and/or shot-setup) - AC Dipole (Ryoichi, proton-only) - E48 bumper as abort gap cleaner (Elmie, Jim, proton-only) - ...