Minutes of the March 11, 2005 Tevatron Dept Meeting

1. Vladimir welcomed Eliana Gianfelice-Wendt (from DESY, just joined Tev
Dept).

2. XiaoLong on operations: 7 shots setups since last Fri ended up in only
4 stores with L=74-104, others died due to AAK1 and PAK3 kicker prefires
and D0 LB QPM problems; proton lifetime at 150 and 980 was not great
mid-week, but improved in latest stores; D17V collimator kept farther from
beam to avoid high losses during scraping.

3. Comments on subsystems: a) Bruce: AAK1 prefired 4 times since Dec,
recently it s reservoir voltage lowered but another prefire happened after
that; found signs of arcing in the oil tank due to improperly high oil
level, the level was adjusted and some gounding problems fixed; PAK3 - voltage
lowered, clogged oil filter replaced, beam loss monitor placed underneath
to figure out whether prefires are beam induced; b) Dean: D17V collimator
went too close to beam and intercepted particles sprayed by D49 collimator
during halo removal (led to a quench), now it's retracted (losses
reduced); there were collimator-loss monitor interface problems after F1
front-end died (fixed.. we think); d) Jerry: tune excursion at seq24 fixed,
losses reduced...but D0 muon chambers still tripped after that; O1 and O2
octupoles were introduced and that quite positively affected p and pbar
lifetime at 150 in the following store; chromaticity measurement has to be
less ambiguous (Vahid's C100 suggested to be used by ops).

4. Ray Tomlin demonstrated MARV robot which will do rad survey in the
Booster. A similar robot is an old dream of Tev people and now seems
to be affordable.

5. Ron showed a movie of bunch-by-bunch longitudinal motion during
longitudinal instability at 980; mode 1 seems to be dominant...
we're waiting for study time to damp it by Robinson.

6. Ron and Paul scaled helix at LB by +-10% and did not detect significant
tune changes (makes scaling easier.... should be verified by optics model)

7. Vladimir presented a) a summary of observations of transverse
instability at 980; b) Petr Ivanov's estimates on growth rates and
contradictory (to reality) conclusion that beam-beam induced tune spread
should be more than enough to stabilize it at zero chromaticity; and c)
Yuri's idea that 100's of long-range interactions make instability
possible thru pbar bunches, in that case many rigid bunch modes can not be
damped by anything but chromaticity; d) other observations (significant
pbar emittance blowup during instability and separator sparks dEmmittance
varies a lot bunch-by-bunch) as well as absence of the instability in Run I
support Yuri's model.


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