Minutes of the Mar 25, 2005 Tevatron Dept Mtg.

1. Vladimir attracted attention to recent memos on spring clean up and
on LOTO procedures (call for safer workplace).

2. XiaoLong on operations: 7 stores in the last 7 days, Lumi from 76 to
two record with 113 and 117e30 (reasons are +10% D0 monitor correction and
smaller pbar emittances); 2 quenches : AAK1 prefire - the tube has been
changed; A49 separator sparked 11 hrs in the record store; last three
stores with pbars from AA only (lower L) - better proton lifetime but
eff-emittance is up 1pi; general trend of having great 150 GeV lifetime
for protons and not as good as it used to be for pbars.

3. Ron showed data on pbar and luminosity lifetime variations vs helix
size (over last several stores he changes the size regularly + or -10%):
qualitatively one can see that the lifetime is better for a larger helix,
but the spread in the data is of the order of the effect (+- some 5%).
Need more statistics (more stores with various sizes) and a more
sophisticated analysis.

4. XL and Tan blew up the beam at 150 GeV helices and found that
acceptances on pbar helix are about the same as before the shutdown, and a
bit less on proton helix (e.g H 75-->65 pi; can be attributed to strange
scatter in FW data due to bad fitting).

5. Yuri reported results of Robinson stability studies (YA, VS, VicS):
longitudinal beam stability improves if RF frequency (VFKNOB) is turned
down -200Hz; changing RF cavity resonant frequency up +300 hz did not help
much. Quadrupole oscilations are seen in both cases. Proposed explanation
is that very high order modes (~1-2GHz) in cavities drive the beam more
effectively if it's off center. Next steps:  investigate dependence on
local bumps at F0 and study 36x0 stability with lower cavity frequency.

6. Tan on tunetracker (TT): worked great at 150, ramp and squeeze (shows
no tune excursion at seq24); Q' measured by the TT is within 0.5 units
from what ops measure by a standard technique; found that quadratic
chromaticity Q" is much larger when measured with coalesced bunch (wrt to
Q" with uncoalesced bunch).

7. Vahid offered an explanation to the effect mentioned above (item 6):
Q" is larger because of impedance which is dependent on beam orbit
position, numbers in his model look reasonable (which assumes that few mm
of orbit matter). His Head-Tail Q' measurement application C100 was
successfully tested during the last 9 stores (during inj tuneup),
deviation from the standard method is about 1 unit.

8. Vic Scarpine and Jean-Paul again measured TBT vert beam position at E0
for about 40k turns, and FFT showed no remarkable betatron motion. Want to
repeat the same EoS with VTICK (noise source) ON.

9. Randy Keup presented SL status: pbar mirror is moved in every store,
camera focus adjusted, instrumentation effects taken into account, images
agree with (a sophisticated) optics model. Vertical SL emittances agree
with FWs; horizontals are off +-10 pi. He needs an EOS to measure D_x
and new values of beta-functions to match with FW emittances.

10. Stephen wants to change SBD and FBI scales by - and +1%,
correspondingly (p-only). Dean encourages people to submit study plans via
new web page and put study results there as well.

11. Alvin was puzzled to see that during the IBS study in Dec'04,
vertical instability did not cause any blowup in hor emittance. He also
sees very well that beta-functions in FWs are not correct (FWs report +6
pi emittance blowup btw 150 and LowBeta - that's not possible as
Schottky is very quiet all the time).


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