Minutes of the Jan 5, 2007 Tevatron Dept Meeting

https://indico.fnal.gov/conferenceDisplay.py?confId=523

Happy New Year!

* Operations Summary (Dan Bollinger) - We've had quite a good run over the
3 weeks since our last meeting.  From 15 Dec - 5 Jan, there have been 19 stores
that have delivered over 110 pb^-1 to each experiment.  The past 7 days have 
seen a record (unofficial) 43.6 pb^-1 weekly delivered luminosity.  The 136 
pb^-1 delivered in December set the monthly delivered luminosity record.  The
past 9 HEP stores all had initial luminosities over 200 E30 cm^2 s^-1 including
the new record store 5155 with an initial luminosity of 248 E30 cm^-2 s^-1.
Only 2 of those 19 stores were lost unintentionally, but two others were 
terminated earlier than desired due to problems at CHL.  D0 losses during the
squeeze have been greatly reduced by fixing horz orbit angle changes.  The
CHL problems on 3 consecutive stores were apparently caused by a flaky UPS
in the cryo controls system.  Some progress is being made on understanding the
large steering error on the first pbar transfer in HEP shots; for now, we
should be able to apply a dead-reckoned correction to eliminate most of the
error as we dig deeper into why the trim settings determined from the reverse-
injection tune-up are so far off.  There were various other minor problems that
didn't impede operations much; we hope the stable running continues for a long
while.

* TEL-2 Studies Report (Seva Kamerdzhiev) - A few "in-store" studies 
compensating P12 have continued - P12 is a good bunch to compensate its
vertical tune (and P24 and P36) are lower than other bunches due to the
different bunch-by-bunch beam-beam tune shifts.  The measured tune shift
as a function of electron beam current agrees well with expectations.
Unfortunately, the Marx generator is beginning to fail due to accumulated
radiation dose; the visible effect is a jittering beam pulse current (and 
shape distortion).  However, the jitter allowed studies to improve beam
alignment and learn that the (proton) emittance growth increase quadratically
with the amount of electron beam "noise".

* New Pbar Cogging for Acceleration (Yuri Alexahin) - Based on calculated
strengths of 5th and 7th order resonance driving terms for various cogging
positions, Yuri suggests trying to ramp with a cogging only 2 buckets later
with respect to the collision cogging value.  That should open up the abort 
gap sufficiently for the ramp while keeping the RDT's nearly identical to what
we have now, perhaps even a little better at flattop for the 7th order term.  
Cogging for collisions should still be done before the squeeze (at least for 
the current helix) because the 7th order resonance strength would be very large
@ LBSEQ 17 as we switch to the collision helix.  We'll develop a plan to try 
it for an upcoming store.

* Continuous Head/Tail Chromaticity Measurement (C.Y. Tan) - It had been 
proposed that one can measure chromaticity by looking at the head/tail phase
difference when kicking the beam (continuously) at small amplitude with a 
frequency close to the betatron tune.  Previous attempts at the SPS using a 
3D-BBQ were inconclusive.  To settle a friendly disagreement, Tan used the 
Tevatron AC dipole to kick the beam and measure the head/tail motion with a
fast oscillcope connected a stripline (what Vahid used in the past).  Indeed,
there was an observable phase difference.  So, Tan lost his bet, but he derived
an analytical expression for the phase difference versus chromaticity (assuming
dp/p matched to a linear bucket and small transverse emittance). Beam studies
will continue.

* Fast Decay Fits (Elliott McCrory) - Elliott has implemented fast lumi,
intensity, and emittance lifetime measurements based on linear fits that are
available as ACNET devices.  For now, they are based on a running 15 minute
averages that begin at start of HEP.  We asked to have the calculations to
begin right after initiating collisions.  We hope these devices can be useful
for obtaining faster feedback when tuning early in a store.


* Plan for next week

   - Continue delivering record integrated luminosities to CDF and D0.
   - Try dead-reckoning A1-line trim setting to improve pbar injection steering
   errors.  (And figure out the real cause of incorrect settings.) (Jerry)
   - Try new pbar cogging for ramp (Ron - HEP shot)
   - "Aggressive" proton scraping @ 150 GeV (Dean - proton-only, HEP shot?)
   - Rough alignment of crystal collimator (Dean - proton-only)
   - Digital Tune Meter (Jean-Paul, Seva - HEP stores)
   - P1 line matching corrections (Andreas, proton-only, HEP shot-setup)
   - E48 bumper magnet as abort-gap cleaner (Steimel, Elmie, Dan; proton-only)
   - ...couple others...