Minutes of the November 20, 2008 Tevatron Dept Meeting

http://indico.fnal.gov/conferenceDisplay.py?confId=2915

* Weekly Operations Summary (Dean Still) - The Tevatron delivered 42 pb^-1
to the experiments over the past 7 days.  There have been 7 stores with initial
luminosity between 254 and 272 ub^-1/s; all were terminated intentionally.
There were 2 accesses to address the overheating A25 upstream power lead.  Cryo
experts finally found and removed a small piece of G10 (from a broken 
thermometry resistor) restricting LHe flow through the lead; all is well again.
During one of the accesses, the A18 quad, known 1.5 mm high, was adjusted (more
later).  Orbit bumps and tune-up was needed afterwards. Pbar longitudinal 
instabilities continue despite efforts to tune the cavities.  The pbar 
collimator F49V occasionally fails to get all the way to the beam and 
contributes to high pbar halo.  The VB11 dipole regulator was replaced after 
putting out 65 amps - larger than the normal 50 amp max.

* A18 Alignment (Jim Volk) - The A18 quad was lowered about 55 mils, while the 
adjacent spool piece was raised > 70 mils since it was found low.  The A18-2
dipole to lessen the vertical tilt.  The spool also has a 2.6 mrad roll that
could not be removed under the vacuum load.  A-sector typically has very 
active ground motion.  Jim recommends doing an as-found from A11 to A25 during
an upcoming downtime to move more components.

* Tune-up after A18 Alignment (Alex Valishev) - Orbit correction was as
expected after lowering the quad ~1.5 mm.  The collision optics needed
significant coupling adjustment, driven by the spool elevation change.  That
spool has 2 sextupole elements that run hard at collisions, so a vertical
orbit change causes feeddown effects.  An end-of-store study had shown such 
effects can distort the separation helix - that probably leads to higher losses
during the squeeze, too.  Additional studies are needed to understand the
orbit offset in the spool and the repeat the A18 orbit bump study to look at
cross-plane response.  Also, a low-beta lattice measurement is needed.
(Already requested anyway.)

* Tevatron Accelerator Studies Workshop (Ron) - Ron is organizing a workshop
at FNAL on Jan 13-14 to garner interest and ideas for using the Tevatron for
accelerator physics experiements.  The lab seeks this input as part of a
discussion for the April AAC (Accelerator Advisory Committee) meeting.  Details
will be forthcoming.

* Plan for Next Week (All)

   - Deliver lumnosity.
   - Tune and chromaticity tracker tune-up (Tan, during shot-setup)
   - HEP Tune Mult Calibration (Ron, end-of-store)
   - Low-beta Lattice Measurement (Alex, proton-only)
   - TEL-2 BPM calibration (Alex, Giulio, end-of-store)
   - Crystal Collimator (Dean, end-of-store)