Minutes of the August 12, 2005 Tevatron Dept Mtg

* News (Ron) - The AD has underspent their budget for FY05; we may be able to
purchase early some items expected to be purchased in FY06.  Send me your
suggestions.  All employees should be working on their yearly accomplishment
reports.  Supervisors should be completing performance reviews over the next
couple of weeks.

* Store Summary (Bruce) - Over the past two weeks, there have been 10 HEP
stores.  Initial luminosities varied between 76 and 129 E30 cm^-2 s^-1; store
4318 is now the record initial luminosity store!  Six of the 10 stores had 
initial luminosities > 100 E30 cm^-2 s^-1.  Machine reliability has been
good - only one store was lost unintentionally (4309 - B0Q6 ramp card failed).
In the record store 4318, there was also a record pbar intensity - the proton
lifetime suffered as the pbars tune-shifted the protons (horz) closer to the
7/12 resonance.  The horz proton tune was decreased 0.001 for subsequent
stores.  Increasing the longitudinal damper gain stopped occurrences of a mode
1 instability during recent HEP stores.  In store 4324, pbar transfer #8 
were injected 1 RF bucket late; the 8 proton bunches not colliding head-on 
with those misplaced pbars had poorer lifetime during HEP and caused higher
than normal background in D0.  Also in that store, pbar abort kicker AAK5
tripped off.  Experts were unable to fix it during HEP.  Since we would have 
been unable to abort pbars cleanly, pbars were eliminated using the TEL and
collimators (good job Xiaolong and Dean!) before dumping the protons
intentionally.  Kicker experts later replaced a blown filter capacitor in the
oil tank.  (The damaged cap may have contributed to an AAK5 prefire two weeks 
ago.)  Motion of various low beta quads caused occasional higher losses in CDF
and D0; C4Q4 was notably "active" for a few stores. 

* Pbar Tune Stabilization During HEP (Ron) - For the past two weeks, we have
been trying to keep pbar tunes constant during HEP by compensating for the
decreasing beam-beam tune shift.  Ops have been using a special mult
to adjust the pbar tunes when an OAC (Open Access Client) causes an ACNET
device to alarm when the tunes drop below the desired value.  Operationally,
the procedure works fine.  The mult has been modified to compensate the
unintended changes to horz chromaticity and horz proton tune.  Any benefits
in lifetimes, etc, have yet to be determined.  A proton-only tune mult was
tried during an end-of-store study, and that mult must be adjusted as well.
Eventually, we could stabilize proton tunes the same way as for pbars, if
desired.

* 28 cm beta* Study (Alex) - We switched to the 28 cm beta* optics at the end
of an HEP store.  D0 lumi increased 5%, and CDF 3% - lower than expected.  Alex
found that the pbar vertical emittances increased as they were gradually 
changing the optics.  It's possible that vertical orbit missteering through
the IPs is to blame, since they saw similar emittance growth later when 
separator scans were being done.  In addition, the beta function waists were
expected to move up to 10 cm, and they didn't try any alpha bumps to optimize
waist positions, so lumi increase may have been lost there, too.  Overall,
there were no big surprises - tunes, chromaticity were under control, losses
were OK.  They need a proton-only store to optimize separator settings and
to look at coupling on the helices, followed by end-of-store studies to 
exercise the new settings.  Jerry is working on new ramp card tables to move
to the new optics quickly during studies.  Additional work will be needed
before actually implementing the 28 cm beta* into the normal low beta squeeze.

* 1/2 Integer Working Point (Yuri) - Yuri showed the reconstructed optics
using TBT data from a beam study near the 1/2 integer working point at low
beta.  The fit was not too bad, although the coupling was ignored for now.  To
check the model, he was able to adjust the model to reproduce the current
optics pretty well.  Yuri also tried to correct the reconstructed 1/2 integer
optics using only the low beta and trim quads, i.e. not using the Q39S and Q39C
circuits.  The major problems (beta-beat in arcs, waist positions at IPs) were
corrected well, but he couldn't quite obtain the ideal phase advance between 
the IPs (just a bit above a 1/2 integer) in order to minimize the beam-beam 
tune shift.  The drawback is that several trim quads would run very close to
the 50 Amp trip current.  Although using the Q39S/C circuits is the preferred
way to correct the 1/2 integer working point optics, we could use Yuri's 
proposal for studies until we can configure and run those circuits as desired
(we need a new power supply).

* Study Topics for Next Week

  - 28 cm beta* (proton-only, followed by additional end-of-store studies)

  - 1/2 integer low-beta working point (proton-only)

  - crystal collimator testing (proton-only @ 150 GeV)

  - commission C100 coupling measurements (proton-only / during shot setup)

  - test proton-only tune mult for HEP (end-of-store)

  - using octupoles @ low beta (end-of-store)

Minutes recorded by R. Moore