Minutes of Tev Dept Meeting 06/21/02


1. Vladimir: we plan to install new 1.5 GHz Schottky detyectors (V, H) in
October, design/fabrication underway, Jerry and Jim S. will keep an eye on
that.

2. Jerry: there was one more meeting on where to put SyncLite monitor if
not at C0. No problem for pbar Lite. The only option left for protons - a
long mirror in a quadrupole before bypass. S.Pordes/Harry Cheung will
make a final look into feasibility of that option. If it will be
unreasonalble, then we replace C0 magnets with Tev dipoles.

3. Tanaji: there were visitors from SLAC and LBL doing/willing to do Tev
beam-beam simulations on parallel computers. SLAC guys have some progress,
and might be able to study 1 hr pbar lifetime at 150 GEV. Seems taht the
first test for the code should be lifetime vs emittance at 150 (we have
exp data), and bunch-by-bunch lifetime variation at 980 GeV (quite stable
pattern). If Paul Lebrun will correlate pbar lifetime at 150 vs proton
intensity based on SDA - SLAC code should show the same behavior.

4. Bruce reported all sorts of problems after the shutdown (p-injection,
pbar transfer, MI kickers, instability on ramp) which led to poor
luminosity in the first 3 stores (2,5,6.5e30). The last two store were
with < 1/2 of typical proton intensity. Proton lifetime at injection is
about 1 hour (compared to 3-4 before), + we loose some 15-20% p's on ramp.
Good news is that effective emittance is not much worse than before.

5. Vladimir summarized the transverse instability we suffer from over the
last 4 weeks (pbar and p emittances blow up when protons become unstable,
pbar losses to follow): it's dependent on N_p (most observations were
with N_p beween 5800 and 7500e9); sometimes can be damped by increase of
chromaticity, sometimes change of coupling helps; it seems to be a single
bunch phenomena. His guess was that this in a "weak head-tail" in x-y
coupled system - something not explored. Jerry and Yuri may probably have
some old papers on this or similar phenomena in Tev or elsewhere.

6. Todd reported that M5.0 earthquake 06/18 12:39 pm in Evansville, IN
affected the Tev (CDF backgound rose 6 fold, Todd's seismometers were
excited by at least 10 microns). It took about 2 min for the wave (or two
waves) to propagte from IN to FNAL.

7. Todd compared vacuum pressure and CDF losses before and after
RWM ferrite replacement: F11 vacuum pressure is 100 times smaller (1 e-8
Torr) now for about the same 7C temperature rise of the ferrite
during the store. Still, number of protons is 1/2 of what it was before
shutdown. Also, he mentioned some sort of F11 vacuum instability after the
end of the store(?).

8. Alvin continues CDF loss rate analysis. Now he found that
a) losses from the abort gaps were independent of F11 vacuum
b) they do not grow vs time in store (! contrary to all our previous
understanding)
c) they are not correlated with losses from (i.e. synchronized with)
proton bunches (contrary to complete correlation of losses from bunches
and between the bunches, reported by Alvin a week ago)
d) abort gap losses are TEL dependent and probably reflect mostly RF
bucket leakage losses (DC beam), while losses from bunches reflect
mostly intercation with vacuum molecules.
e) only some 3% of total losses end in the CDF counters

9. based on ANSYS Ron has estimated AVERAGE vacuum at the CDF and DO (i.e.
15 m long sections) to be about 1.2e-8 (20 times better than some of us
though before). Vacuum load (intergated vacuum) from both detectors is
some 10 times smaller than from F11 at worst times. He is going to
estimate outgasing rate at D0 based on Bruce's data and compare
with previous rate measurements,