Minutes of the Aug 19, 2005 Tevatron Dept Meeting

* Store Summary (Bruce) - There have been 5 stores since the last meeting.
Initial luminosity ranged from 61 to 128 E30 cm^-2 s^-1.  (Store 4332 was the
second best initial lumi ever.)  The lower luminosities were caused in part
by fewer available pbars (pbar Li lens failed and was replaced) and large
proton emittances for store 4341 (poor closure for proton injections, still
not understood).  Two stores ended unintentionally.  During store 4332, human
error while checking out the newly installed pbar Li lens caused 120 GeV beam
to be lost in the P2 line resulting in a large vacuum leak (vented to 
atmosphere) that propagated upstream to the F0 lambertson.  When the lambertson
vacuum degraded enough, high beam losses were generated in the Tevatron and
caused a quench at F11 (just downstream of the lambertson).  Stote 4337 ended
when a well-placed lightning strike caused several QPMs and the D0 SMT to
pull the abort, but losses were low and there was no quench.  The lightning
also fried many components in the C17 separator controls crates (repaired or
replaced) and blew out fuses in the O2 octupole circuit power supply (B4 
service building).  A cryo roughing pump in the tunnel at B43 also failed
(needs to be replaced).  The TEL electron pulse was shortened so that it could
be used during pbar loading and up the ramp.  There seems to be evidence that
the TEL is reducing the amount of DC beam that would be lost early in the 
ramp.  The timing (position in the abort gap) also needed to be changed to 
prevent DC beam from building up during HEP stores.  The TRF7 tripped off 
during store 4336, and the modulator was replaced between stores.  Over 18 
pb^-1 of collisions have been delivered from store 4328 onward.

* 28 cm beta* stuides (Jerry) - There were 2 proton-only beam studies this
week.  An automated method to transition to the new optics (for studies) works
pretty well.  A bug in the CAMAC 460 card firmware was identified; a work-
arond is being used for now.  There are a couple of lingering minor issues, but
the method works well overall - we can switch to the new optics in < 1 min as
compared to the 30 min or so in previous studies.  Tunes, chromaticity, and
coupling were measured on both helices (the pbar helix was simulated using
dipole corrector bumps) and are fine.  The helix closure was measured and
corrected - a 10 um offset in the beams at CDF contributed to the lower
than expected luminosity gain in the previous end-of-store study.  The lattice
model reproduces the helical orbits quite well.  After some minor lattice
adjustments, we will be ready for another end-of-store study by Tuesday or
Wednesday (alpha-bump scan).  Great progress!

* Crystal Collimator (Dean) - Two weeks ago, the crystal collimator limit
switches were moved so that it could travel farther into the aperture.  We
can now move the beam into the collimator at 150 GeV.  A beam scan of the
crystal seems to indicate its face is ~10 mm high, but it should only be 5 mm.
Perhaps there is some twist, or it's just an artifact of measuring it with
beam that is scraped away during the scan.  The inchworm for pivoting and the
laser system (measures alignment) are functional.  Dean would like to test
channeling in a proton-only store at 980 GeV.

* Studies for next week

  - 28 cm beta* end-of-store studies

  - additional coupling measurements using the C100 application

  - test HEP proton-only tune mults (end-of-store)

  - test crystal collimator at 980 GeV