Minutes of the 4 Oct 02 Tevatron Dept Meeting

1. Luminosity report from Dean: just two stores over the last week with
L=27.6 and 27.0, in between we have lost two stores due to quench at flat
top and early in squeeze, over the course of the week we changed FBI
calibration, perfected operation with hor damper and smoothed orbits and
tunes, p-losses were high early in stores, it was obsrved that after
access one of low-beta quads was tilted by 0.15 mrad (relative to
what is was before the access as measured by tiltmeters). Seems that overall
pbar efficiency went up since end of September: e.g. in record store 1787
MI efficiency was 68% and 73% in Tev, in the last two stores it was about
82% in Mi and 80% in Tev. Reasons are: a) smaller stack sizes; b) MI
cpoalecsing tune up(?); c) better pbar lifetime at 150 and ramp (damper?);
d) A1 line tune up.

2. S.Pordes on FBI recalibration using waveform generator: FBI gain is
corrected by +15% for pbar channels FBIANG/AWG, and -2% for protons. (so
we instantly get 15% more pbars at low-beta!). 12%-discrepancy beween AWG
and ANG - supposedly because of incorrect background subtraction - is
not fixed, though number of buckets for wide gate channel is now
sreduced and set to 3 reduced. Intensity also can be extracted from
SBD signals and that would solve that "proton-backround" issue. Alvin
emphasized that AWG(and ANG?) still needs to be calibrated against IBEAM.

3. Mike M on many things done over last two weeks: a) coupling and tune
drifts are compensated at 150 to the level of 0.001; b) the b2 unwind
compensation which we are doing at the begining of the ramp is close to
what recent magnetic measurements report should be (Pierre Bauer); c)
it was found last week that orbits on the ramp and squeeze are
bouncing by +- 1 mm (e.g at A0), the orbits were smoother to 8/8/02 orbit
(though some DFGs need to be set high); d) a new algorithm developed to
detect flaky BPMs (with help of CD guys) and now it takes 5 min to check
all of them - do 3-bumps and check readings with model expectations.

4. Tan on dampers: a) hor damper seems to be helping to improve pbar and
proton lifetime at 150 GEv by lowering chromaticities C_v,h; b) hor damper
has been left On all the way to LB and no harm seen; c) vert damper is too
noisy as it leads to >12pi/hr emittance growth at 150 and about 5 at LB;
d) injection is not possible with lower C_h, v and the damper(s) ON -
beam just falls out, but after the injection C's can be lowered (C_h
by 5-6 units, C_v by 2 with hor damper only); e) even with dampers On at
LB beam goes coherent if chromaticity dropped by more than 8 units. No
damper store will be done to estimate benefits and harm due to the
hor-damper. Emittance growth due to the damper to be measured at the end
of store.

5. Peter I on octupoles: OZF curcuit has a ground fault which limits
its current at 20 A - that needs to be fixed. At low-beta central orbit
octupoles allowed to reduce C_v, h from +25 to +5, but on the helix the
threshold chromaticities were found to be about +15 (in one plane, it can
be reduced toalmost 0 in another plane). "Ghost line" excites the
instability - so the line is real.

More studies needed to decide do we really want to reduce
C_v,h at flat top or low-beta with use of dampers or octupoles.

6. Alvin on p-only stores: a) there are no losses of uncoalesced beam on
ramp; b) lifetime at 980 central orbit is about 600 hrs; c) that
corresponds to average N_2 pressure of 5e-10 Torr and 0.1 pi mm mrad /hr
emittance growth; for He the numbers are 2.5e-9 and 0.03 pi mm mrad/hr.
Valery's numbers for dE/dt are three times larger.

7. Vladimir on tune scans at 150 GeV: a) p-losses at 150 Gev helix are the
smallest at nominal WP 0.575/0.583; b) in presence of beam-beam force
(=TEL dQ=0.001) the better working point is on diagonal 0.582/0.582;  c)
we might want to scan for better WP (better lifetime) with real pbars at
150.

8. Bela on B0 low-beta quad rolls: new method is developed to determine
the LB quad rolls on base of near IP BPM readings (difference orbits)
after various local bumps, the biggest roll found to be about 1.5 mrad for
Q4D, the errors of the method still to be understood.

9. Valery on A1 line work: a) difference orbits for reverse injection
(i.e. BPM readings Tev-A1-MI) show significant D_x mismatch; b) new A1
settings (quad currents) are incorporated and the D_x mismatch should
become factor of 2 smaller (with insignificant D_y mistach increase), c)
even better optics is on its way. Dave Johnson pointed that data (wire
profiles along A1 and in MI) taken by him and his MI colleagues show
significant beta-mismatch. He would like to see some convergence of their
and Valery's conclusions/actions (for that the language should be set the
same).