Minutes of the Feb 6, 2004 Tevatron Dept Meeting

1. Dept news: a) Dave McGinnis presented "Letters of Recognition" to Ralph
Pasquinelli and Paul Lebrun (the third celebrity - Andreas Jansson - was
absent because of birth of a son - congratulations!) for their
contribution to the design, fabrication and commissioning of 1.7GHz Tev
Schottky detector - CONGRATULATIONS!); b) Jerry updated on plans to move
B0 Low-beta quads horizontally to reduce corrector currents, short beam
studies requested; c) Vladimir - tentative date for 2.5 days shutdown is
Feb 24.

2. Dan Bollinger reviewed Tev operation last week: a) three luminosity
records with 55.4, 55.5 58.9 e30; record integrated L for a single store
of 3.1pb-1 in #3214 which lasted record long 34 hrs, luminosity lifetime
bounces btw 9.0 to 9.8 hrs - a bit better than a week ago; b) during short
access E03 collimator was repaired (bad threaded rod did not allow to
place the collimator properly); c) +1mm bump at A0 was introduced that led
to significant reduction of pbar losses at the end of the ramp (from 6% to
some 2%)

3. Valery did measure differential orbits at low-beta and concludes that
beta wave in arcs is some +-20%, beta^* at CDF is 53/43 cm at D0 41/43 cm,
X and Y waists are some 40 cm apart at CDF - in rough agreement with their
SVT data, sees minor dispersion at both IPs (not a factor for luminosity).
He suggested to change currents in a dozen of quads to correct the beta
wave and bring beta^* to design 35 cm. Expected tune correction 0.03. The
changes are drastic and there was a lengthy discussion how it happened
that the lattice is so off and what is the best way to introduce
significant current changes smoothly.

4. Tan and Jim Steimel timed 200W hor damper kicker onto the abort gap and
tried to clean DC beam at the end of store #3214. Though the effect of the
cleaning was seen, it was incomparable to the TEL. They estimated the
power spectral density needs to be increased by factor of 100 to be
competitive with TEL. Vladimir was more optimistic and predicted that 10
fold reduction of noise bandwidth will make the damper cleaning
successful.

5. Ron showed new java applications available (go to Tev Web page):
colliderramp generator (C49), C49 files for different HEP stores can now
be easily compared; new arrays added to the Tev Array Display.

6. Vahid looked into beam oscillations at the end of the ramp when hor
Schottky power goes "weird" for 20 sec. He sees big tune line at Q=0.5 in
hor motion but it is present in the low-beta oscillations as well.  At
low-beta (midle of the store), distribution of particle oscillation
amplitudes along the bunch is asymmetric - is that head-tail? He also
sees +-50 microns hor oscillations at low-beta at synchrotron frequency
(previously reported, reason unknown).

7. XiaoLong Zhang compared accuracy of many diagnostics channels we use
(fluctuations over 5 min interval at the end of #3217): best(least
fluctuating) luminosity channel is D0FZTL 0.3%, worst B0ILUM[i] 4.2%; best
intensity channel IBEAM 0.02%, worst SLAAV 3.5%; best beam size channel
SBDMS1 0.05%, worst SLAEY[i] 4.5%; best position channel Z:TPOS3 5
microns, worst T:VPA16 (regular Tev BPM) 97 microns.

8. Yuri and Tanaji computed pbar bunch tunes in presence of coupling: Yuri
used min tune split 0.003 and found that it can not explain scallop-like
tune distribution, while Tanaji used dQ_min=0.005 and got tunes close to
what we observe. No one in the room was sure what is coupling on pbar
helix at LB, though MMartens said the tuning goal is dQ_min<=0.003. Paul
Lebrun did mention that the tune pattern slighly varies store to store.
Yuri also calculated differential chromaticity (for pbars) due to beam
beam (where chromatism of low-beta plays significant role) and found it +2
units in Hor chromaticity and -4 units in vert.

9. Alvin looked into longitudinal emittance evolution in the record long
store #3214 (34 hrs): longitudinal scraping on the ramp was minimal, at
980 GeV proton distribution was not quite Gaussian, but at the end of
store it looked more like Gaussian; there is clear sign of thermaliztion
of proton longitudional phase space at the end of store, while pbar
distribution shape did not change much. Also, there was no tail growth
for pbars.  95% long emittance of protons had grown from 2.6eVsec at 980
to 6.2 at the EoS, pbar - from 2.5 to 3.5eVsec.


Minutes recorded by V. Shiltsev, edited by R. Moore