Minutes of Friday meeting, April 12, 2002

1) Dept news: a) (Vladimir) upon CDF request we will abort beam if any
RF station trips; b) (Valery+Tanaji) SLAC collaborators do some work for
us: Gennady Stupakov will report soon on longitudinal modes dynamics with
36 bunches and Yunghai has started b-b simulations at Los-Alamos
supercomputers

2) Jerry - last week luminosity was up, but losses were a big problem for
several stores, high losses are often associated with bunch length
blow-up at the beginning of the store (e.g. quick blowup from 2ns to 2.5
ns), he sees big variation of the loss rate from bunch to bunch - factor
of two - and longer the bunch higher the losses, we may need to do some
changes in the collimation scheme to counteract high losses

3) CYtan: large dipole and quadrupole longitudinal oscillations occur at
980 GeV, he was able to adjust dipole feedback loop gain and suppress
phase oscillations by factor of 2, quadrupole ones remained the same

4) Jerry&Dean finished parsing the squeeze, also he summarized TeV
aperture scans: if C0 aperture is greatly increased (that's what Bruce
is planning) we expect that TeV beam aperture will increase by some 50%
(vert) [100% is normal helix separation]

5) Valery has shown Tev vacuum estimates from observed emittance growth
of low intensity DC beam at 150 GeV - numbers are scary: 5 pi mm mrad
/hour or 4e-7 Torr for atomic H. His model includes multiple and single
Coulomb scattering and fits (too) well experimental data. To be on safe
side (before doing smth) we decided to repeat the measurement next week.

6) Mike martens, Yuri and other did pbar studies at 150 GeV with new
injection helix and did not observe much of improvement with two 36x12
stores. There are number of ideas "why". One of them is that tunes have to
re-adjusted - e.g. Mike did change dQh by 0.003 (hor pbar tune up 0.003,
proton down 0.003) and observed drastic lifetime improvement. The ha\game
to continue next week.

7) Mike and Vladimir complained that FWires were not operational during
studies period (!!!)

8) Vladimir reported: for medium intensity 1.7e11 single p-bunch they saw
some 1% of the DC beam right after injection and 1.5 % lost at the
beginning of the ramp - numbers are too small compared to normal stores,
when we loose some 5-8% of the DC beam at the beginning of the ramp; they
also observed longitudinal waves in the e-beam excited by proton
bunch.

9) Alvin has reported progress in modeling Dc beam loss at 980 GeV; there
is qualitative understanding of the loss distribution in abort gaps, but
some questions remain open. Vladimir proposed end of store studies to
compare loss distribution with and without collimators.