Minutes of the Feb 23, 2007 Tevatron Dept Meeting

https://indico.fnal.gov/conferenceDisplay.py?confId=584

* News (Ron) - Dean noted a number of visitors have arrived to help conduct
crystal collimator experiments.  Welcome to Yuri Chesnokov (IHEP-Protvino),
Walter Scandale (CERN), Shinya Sawada (KEK), Massimiliano Fiorini
(INFN-Ferrara), and Vincenzo Guidi (INFN-Ferrara)!  Sawada and Scandale will be
the speakers at two AD seminars next week.

* Operations Summary (Bruce Hanna) - The Tevatron delivered 37 pb^-1 to D0
and CDF this week.  There were 6 HEP stores with initial luminosities
ranging from 173 to a new record 285 E30 cm^-2 s^-1.  Not only did store 5234
have the record initial luminosity, it also set the record for delivered 
luminosity in a single store - just over 9.3 pb^-1.  Store 5231 was lost after
20.7 hours when the B0Q6 power supply apparently switched off momentarily. This
problem has recurred occasionally over the past 3 years; engineers have 
replaced many different components, but no smoking gun has ever been found.
Store 5238 was lost after 11.7 hours when a Commonwealth Edison glitch tripped
off several RF stations and caused a quench @ C15.  D0 loss spikes during the
squeeze have been reduced with vertical angle bumps.  Roughing pumps @ B13 and
C33 require an access for replacement.  There was a vacuum burst in the A150 
line that cascaded to the Tev lambertsons during studies; valves had to be
closed to help recover.  During the recovery from the ComEd glitch, a Booster
crate restore corrupted C:LBSEQ; the save/restore properties of C:LBSEQ have
been eliminated to prevent a reoccurrence.  The power supply for crate $C3
failed at a fortunate time - just before loading pbars for an HEP store; no
pbars were lost and the supply was replaced.  TEL-2 is now the default 
abort gap cleaner while TEL-1 is used for beam-beam compensation studies.  Tan
adjusted the horz tune tracker.

* Status of New Sextupole Circuits (Alex Valishev) - The polarity check of
all the new sextupole elements using orbit bumps is complete.  All elements
appear to be hooked up correctly.  Even the A25 element may be OK after all, 
but we'll do another beam measurement and look at it visually during the next
access.  The first study to make the new circuits operational was done - tuning
OFF those circuits at 150 GeV.  All the needed adjustments for orbits, tunes,
coupling and chromaticity were close to the expected values.  Jerry will
prepare a C49 database file with the new values for continued studies.  So far,
so good!

* Recent TEL Studies (Seva Kamerdzhiev) - TEL-2 has demonstrated reliable
abort gap cleaning, so it will be used by default for a while so that TEL-1
can be used for dedicated studies.  Significant jitter in the TEL-1 electron
pulses was reduced by replacing the pulse generator and "cleaning up" the 
trigger cabling.  The initial beam-beam compensation study with TEL-1 acting
on P13 caused a reduction in the lifetime, but more work needs to be done
on improving the electron beam alignment, power supply ripple, etc.

* Crystal Collimator Status (Dean Still) - Earlier this week, it looked like
channeling was observed during an end-of-store study, but they could not 
confirm it during studies the next day.  During upcoming end-of-store studies,
they hope to complete the scanning of the full angular range and revisit
interesting locations.  If no channeling is observed, they will request an
access to try to verify the crystal bend angle.  In the past month, there have
been 15 hours of end-of-store studies for the crystal collimator.

* Pbar Cogging between Transfers (Ron Moore) - During store 5231, pbars
were cogged +9 buckets between transfers to look improved proton lifetimes.
The study was stopped after the 4th transfer because those pbars landed where
the 6th transfer should have been.  It is still not understood what happened;
the cogging and all state variables for injection looked fine.  Compared to
store 5194 when the cogging was first attempted briefly after the 3rd and
6th transfers, the proton lifetime was improved, but this was likely due to
the tuning that was done after hooking up the sextupole circuits.  Compared
to a more recent store 5234 with nominal cogging, the proton lifetimes during 
the first three pbar transfers were very similar, but some bunches clearly
benefit more with the new cogging scheme.  We hope to repeat the study for all
9 transfers.

* Plan for Next Week (All)

   - Reliable delivery of luminosity to CDF and D0.
   - New Sextupole Commissioning (Alex, Jerry - proton-only)
   - TEL-1 studies (the usual crew - during HEP)
   - Crystal collimator (Dean + visitors - end-of-store)
   - Test E48 bumper as abort gap cleaner (Jim, Elmie - proton-only)
   - P1 line matching with IPM (Andreas - proton-only)
   - Chromaticity Tracker (Tan - proton-only)
   - Install new BPM firmware (new offsets from DB) - Bruce will coordinate