Minutes of the April 8, 2008 Tevatron Dept Meeting

http://indico.fnal.gov/conferenceDisplay.py?confId=1699

* News (Ron) - The Tevatron Dept's furlough schedule for April and May has been
set - see our "vacation" calendar on our web site.

* Weekly Operation Summary (Dan Bollinger) - We set a integrated luminosity
record of 48.0 pb^-1 for our official Monday-Monday reporting week.  The
Friday-Friday integrated luminosity is 29.8 pb^-1 - lower than recent running
due to periods of extended down time in the Main Injector for repairing a 
vacuum leak and replacing a quadrupole in the NuMI line.  There have been 4
HEP stores in the Tevatron with initial luminosites between 205 and
269 ub^-1/s - all were terminated intentionally. Minor problems included:
HB11 and HC38 fuse faults, LLRF preventing transfers from MI, dce26 restarts to
clear up problems with OAC devices, S4C2B fuse fault / water leak in rack,
A2 wet engine flywheel change, proton abort kicker #4 trip during store 6021.
Tan and Jim Steimel phased the PBJ amplifier a bit better to improve the power
output - it can now blow-up the pbars at ~2.5 pi/min.

* Update on BPM / Network Issues (Luciano Piccoli) - After changing firmware
in network switches, there have been no missed BPM state transitions in 2
weeks.  Luciano has also been testing a new CPU kernel with 100 Mb/s network
speed in his teststand.  All looks well, so he would like to try that
configuration in the A0 building next week.

* New Proton Plots in Spreadsheet (Ron) - I added plots showing proton 
bunch length at 150 GeV vs intensity, 150 GeV inefficiency vs bunch length,
efficiency 150 -> Remove Halo vs intensity and bunch length, pbar non-luminous
lifetime vs proton intensity.  The proton plots support what we've known for
a long time - shorter bunches have better efficiency.  The last 2 stores had
really good bunch length (< 2.75 ns sigma) for their high intensity ~320 E9
per bunch and we lost < 6% at 150 GeV.

* P1 Line Matching (Alex Valishev) - After implementing changes to the P1 line,
the horz dispersion was reduced by ~factor 5.  We would now expect < 1%
emittance dilution (down from ~9%) from betatron and dispersion mismatches,
but we haven't seen a reduction in the average proton emittance.  Next, we
need to obtain differential orbit data to look for other mismatches, use IPM
to look for quadrupole oscillations at injection, verify/reduce our tolerances
on injection steering closure.

* Recipe for Blowing Up Pbar Emittances (Mike Syphers) - Mike recently wrote
a note looking at the beam-beam tune shift and spread for 2 beams of differing
sizes like we have in the Tevatron.  The tune shift distrbution of the larger 
beam (protons) caused by head-on collisions with the smaller beam (pbars) when
the size ratio is 2:1 is almost uniform leading to a very wide tune footprint.
We have been using the PBJ to blow-up the pbar emittances to help reduce
the proton tune spread and improve their lifetimes.  Mike's example "recipe"
is to blow-up the pbars based on the available beam intensities and emittances
to obtain beam sigmas in a ratio of 3/4 (pbar/proton) and obtain tune shift
on the protons that 1/2 of the tune shift on the pbars - the proton tune
spread is reduced significantly and almost equal to that of the pbars.  We can
use this example to motivate how we can use the PBJ for different durations
to obtain more consistent store-to-store beam-beam tune shift distributions.

* Chromaticity Tracker Update (C.-Y. Tan) - Adding a new (commutating) filter
helped improve the chromaticity measurement for uncoalesced beam (up to some
scale factor).  There is still a mysterious factor of 2 difference when
measuring with coalesced protons.  There may be still issues with high
chromaticities (>8) and possible effects from higher order chromatic effects.
Tan also note a larger than expected chromaticity drift at 150 GeV.

* Plan for Next Week

   - Run, run, run.  Deliver luminosity.
   - Test orbit stabilization mods (Dean, Jerry, proton-only)
   - Pl Line Matching Measurements (Alex, proton-only)
   - HEP Tune Mult Calibration (Ron, 1-2 hr end-of-HEP store)
   - Low-Beta Optics Measurements (Differential orbit, TBT, AC Dipole)
     (Alex, Ryoichi, proton-only)