Minutes of the 26 Jan 2007 Tevatron Dept Meeting

https://indico.fnal.gov/conferenceDisplay.py?confId=526

* News (Ron) - The D0 Collaboration is offering a special presentation and tour
for AD personnel on Jan 31 at 11:30.  (You should have received an email from
Traci about it.)  For planning purposes, please let Traci know if you will
attend.

* Operations Summary (Dan Bollinger) - Only 27 pb^-1 were delivered to the
experiments over the Friday-to-Friday period.  There have been 6 HEP stores
with initial luminosites ranging from 65 to 273 E30 cm^-2 s^-1.  The very
small initial lumi for store 5188 resulted from Recycler damper problems that
caused pbar loss and large emittances.  Store 5190 was terminated after only
4 hours because one of the B17 horz separator power supplies failed, causing a
large drop in luminosity, and it could not be replaced without causing more
problems; all others stores were terminated intentionally.  The D0 collision 
point position was adjusted by a couple hundred microns in both planes upon 
their request.  D0 needed a 10 hr access, so several other long jobs around the
complex were initiated at that time, too, e.g. replacing the failing dipole 
magnet in pbar's AP2 transfer line.  In the Tevatron, the first set of 
sextupoles to be used for second-order chromaticity correction was recabled to
be powered from new power supplies.  For now those elements will be run as the
normal chromaticity sextupoles, but some studies can be done before the 
sextupole reconfiguration is complete; the b2 drift compensation and unwind 
algorithms required minor changes to account for the sextupole changes.  The 
TEL-2 Marx generator was removed from the tunnel and then reinstalled with 
additional steel shielding between it and the abort dump.  The laser alignment 
system was installed on the crystal collimator.  Failed turbo and roughing 
pumps in B-sector were replaced.  Cryo performed lots of maintenance in the 
frig buildings.  After a nice hiatus, we had a couple of D0 rad trips @ LBSEQ 
17...they're under investigation.

* Helix Measurements @ 150 GeV (Alex Valishev) - The Linux version of P163
was used successfully to measure the current injection helix lattice and record
the orbits when powering individual separators.  The current OptiM lattice
model agrees very well with the measurements.  The "fudge factors" for the 
separator voltages-to-kick angles are < 5% except for C17V (14%).  There 
have been no siginificant changes since the last optics meaurement.  Alex also
made estimates of new feeddown settings if the new C2 sextupole circuits are 
set to zero @ 150 GeV; the tune changes should be small 0.002-0.003.

* Cogging Between Pbar Transfers (Ron Moore) - Based on observations during
a previous study, we looked at proton bunch lifetimes (qualitatively) when 
cogging pbars +10 buckets for ~1 min between the 3rd/4th and 6th/7th pbar 
injections on shot 5194.  Many bunches did show better lifetimes with the test
cogging, while some did not, depending upon the position within the bunch
train and where they interacted with pbars.  The study will be repeated cogging
between every pbar transfer.  Automating the cog between transfers will require
assistance from a controls expert. Yuri suggested +9 buckets should be better 
since the 7Qy resonance driving term should be a factor of 2.5 smaller than 
the +10 bucket cog.  The new cog for the ramp should be adjusted a little to 
get to a similar configuration.

* Beam-Beam Compensation Update (Vladimir Shiltsev) - They have *lots* of data
in hand and are busy analyzing it.  The TEL-2 Marx Generator was removed due
to (temporary) radiation damage effects, but it was recovered and reinstalled 
after only a few days with additional steel shielding.  In the meantime, they 
instead used an RF tube modulator and showed during an end-of-store study that
it is very stable and caused no additional emittance growth in compensation 
mode on protons.  Before the damaged Marx Generator was removed, they ran
TEL-2 in DC mode working on all proton bunches.  They compared lifetime
improvements from TEL-2 compensation to a similar small < 0.001 increase of 
(vertical) tune - a similar improvement was seen for all bunches; that 
suggests the proton tunes should be higher.  Beam-beam compensation studies 
using TEL-1 alone and then both TELs simultaneously are forthcoming.

* Plan for Next Week

  - Continue delivering lots of lumiosity to CDF and D0.
  - P1/A1 Line Matching with IPM (Andreas - shot-setup/proton-only)
  - Resume proton scraping @ 150 GeV (Dean - shot-setup)
  - Crystal collimator alignment (Dean - end-of-HEP stores)
  - Pbar cogging while waiting between transfers (to
    look for better proton lifetime) (Ron - shot-setup)
  - New 150 GeV Helix (Alex/Yuri, proton-only)
  - Coupling @ LBSEQ 15-19 (Yuri, proton-only)
  - ...couple of other studies on the list