Minutes of the Dec 5, 2003 Tevatron Dept Meeting

1. Dept news: a) new Guests Scientists in the Dept - Vinay Boocha and
Sasha Valsihev - welcome!; b) CDF thankful to Ron Moore for TDC board DSP
code and A48 collimator (both done during shutdown).

2. Andreas on Tev operation over the last two weeks: 8 HEP stores with L
from 9 to 22e30, effective emittances somewhat (5-10%) larger than before
the shutdown; one case of high proton losses, one case of scallops, pbar
lifetime at LB is OK, luminosity lifetime 10 to 22 hrs, p and pbar abort
kickers were found mistimed by 6-8 RF cycles (reason not understood yet,
RFC=21ns) that resulted in multiple quenches on abort and few days of
investigation/adjustments, CDF IP moved further up 0.4 mm after they moved
in heavy steel stuff (shielding) on 11/25 and slowly continues to drift up
since then; seems that one of few LB quads moved at that time as it
resulted in +-5mm vertical orbit distortions ringwide - smoothing has been
done (most of change in VA49 - some -0.04 mrad)

3. Peter Ivanov studied stability criteria at 150 and found that now
injection is possible at zero chromaticities;  stability does not depend
on beam position in the Lambertson (all thanks to liner); it's hard to
keep chromaticity near zero due to some 1-2 units/hr drift. Jerry : C_vh
drifts (as well as newly measured tune drifts which look a bit larger than
before) not compensated yet as scale and signs vary measurement to
mesaurement - to be further studied. Currently we run at C=4 in v,h and
150 lifetime is better than in Sep (due to to larger aperture, too). Peter
thinks that coherent instability at 980 is not head-tail. Signs are not
very sensitive to C_v,h, sensitive to coupling and tune changes, often
appears while scraping, self-stabilizes and reappears over few min time
scale.

4. Ron and Vladimir did separator scans and noticed that for the same
variation in luminosity during the scan (say , 4-5%), pbar losses do not
change much while scanning beam-beam separation but vary a lot during
angle scan. I.e.  pbar loss rate very sensitive to crossing angle. Mike M
and Valery think that might be due to changes in nearest parasitic points
(i.e. not only at the main IP itself).

5. Norm Gelfand presented proposal to move CDF IP down 5mm - it requires
tilting girders on which LB quads are set on both sides of IP (many
millimeter moves). Effect is promised to be local (i.e. no orbit
distortions ringwide, just B0 IP).  Jerry and Vladimir are in favor of
making first move of some 20% of total to see that things go right.

6. Vaia showed CDF and D0 vertex data pointing to a significant coupling
at the IPs: e.g. <xy>/(sigmaXsigmaY) is about 0.3 at D0 and 0.1 at CDF and
vary along z coordinate. More analysis to follow.

7. Vladimir flew FWs across the same uncoal beam on central orbit and
p-helix (at 150 GeV) and comparing reported sigmas concluded that
beta_y is +12% and beta_x +6% higher on the helix [that shows the scale of
lattice distortions between CO and helices].

8. Valery performed lattice measurements at 150 and observed vertical
dispersion and off-plane beta functions reduced by about 1.5-2 times wrt
to what was before shutdown. Mike Syphers pointed that vert dispersion
pattern depends on currents in skew correctors which are now different
than in Sep.

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