Minutes of the Tevatron Dept Meeting Dec 6, 2002


1. Mike Church has presented Letters of Recognition signed by the BD Head
to Jim Steimel and Chien-Yang Tan for their work on design, construction
and commissioning of the Tevatron longitudinal and transverse dampers; and
to Dean Still for personal contribution to the recent Tevatron luminosity
progress, including his resourceful work on the Tevatron operation under
record luminosity conditions and Tevatron coordination in October-November
2002.
CONGRATULATIONS!!!

2. Vladimir announcements: a)CYTan will be Tevatron Coordinator from Dec.1
till Jan.12 23:59pm. b) Shutdown will begin Jan.13 and last 3 weeks. Jim
Volk will be the Tev coordinator during that time. c) Jerry Annala will be
the Tev coordinator starting Feb.3; d) Tev Hardware milestones set by
management: i) Complete C0 Lamberston Replacement by 2/15/03; ii)
commission Tev injection dampers by 5/15/03.

3. Jerry calls for better discipline of Tev studies: a) better planning,
submit detailed study plans; b) write summaries in the Tev Elog; c)
NEW - fill and sign special form "Documentation of Changes" (available on
Tev Web) and leave it in MCR after studies; d) present results Friday at
the Tev mtg and/or write a report (Tev-note). Valery shared his past
experience in JLAB where N signatures were needed to approve any beam
study. Mike Church refused to sign anything like that. Jerry was willing
to sign only well prepared and useful plans. Vladimir pointed out that not
all studies we should do are supposed to improve Tev performance
immediately, some studies are needed to understand better what's going on.

4. Valery informed on DC beam investigation progress meeting: TD guys made
certain progress in simulations of the TEV RF cavities and measurement of
RF phase noise. It was decided to perform bunch lengthening studies with
open phase feedback loops.

5. Tan presented summary of stores since the week of Thanksgiving:
there were 6 stores since 11/28, but only 3 were above 30e30, plus one was
lost yesterday due to improper use of dampers, we also had separator
sparks, pbar blowups in squeeze etc in 3 stores that kept lumi under
20e30. The latest store went in without dampers (they need to be either
fixed or re-considered). SL pbar emittance scaling changed by 3.24 after
11/27 but to our surprise pbar hor emittance has grown by much
larger factor 6-7 (44pi vs 6 pi), while vertical emittance increased as
expected by 3.2 (36 vs 11).

6. Todd observed correlation between humidity in the tunnel and roll of
one of the magnets (10% in RH results in 20 urad roll). Effect on the
orbit was not that clear but orbit variation measured by SL at C11 over
last 2 weeks was huge - 2 mm! Todd has some theory why rusted stands would
do that and is going to set a lab experiment to study that.

7. Bruce lowered abort kicker voltage to 36 kV (from 38 kV) and expects
less kicker prefires in the future.

8. Mike M and Pierre Bauer studied b2 snapback in the first 20 seconds of
the ramp (150 to 200 GeV) and found no obvious problem there,
especially if the time at front porch is short, 20 min - both C_h, v go
down 3-4 units in the first 4 seconds and then slowly go up. After sitting
at 150 GeV for 2 hrs, they observed some 0.003 V-tune bump early on
ramp and much larger C_v,h dip down - some 7-8 units down over 6-8 sec and
recovery up later on. Measurements are quite repeatable, except sometime
it's hard to follow tune lines on ramp (after 2 hrs at 150GeV).

9. Frank Z summarized pbar tune measurements at the end of store. Tan's
Q-meter tickler was gated on only one pbar bunch and changes in Schottky
spectra were detected. Results show that A1 has lower hor tune shift
than A2-A12 (-0.004 with 140e9 protons/bunch), while A12 has 0.003 lower
vertical tune than A1-A11. That is consistent with theory predictions by 3
different groups Shatilov, Alexahin, T.Sen&Co, except that theorists'
bunch numbering should be reverted (i.e. their A1 is actually A12, A2=A11,
etc). P.Bagley did similar measurements in 1995 and our results look very
much like his [though tuneshift is smaller]. After p and pbar beams were
separated in CDF and Do, pbar tunes went down by 0.005-0.006 H and 0.003 V
[that is due to head-on beam-beam]. Expected shifts - on base of
measured beam parameters are somewhat (15-25%) larger.

10. XiaoLong reported results of the chromaticity scan: a) at 150 GeV on
C_v,h on proton helix are 4-5 units higher than on pbar helix (11-12 vs
7); b) exploring losses on p helix with C_h,v from 4 to 14 it was found
that losses grow slowly till about 11-12 units, but grow fast above that
(it's opposite to previously observed "linear" dependence of dN/dt vs
C_v,h); c) on pbar helix it was observed that for nominal bunch population
of 250e9, threshold of instability is about 4 units of C, again,
variation of losses on C_h was quite remarkable - factor of 8 while C_h
changed from about 1 to 7 (C_v=7); d) diagonal (simultaneous in V and H)
reduction of C at collisions (doen > week ago) had shown that losses
slightly GROW with decrease of C_v,h (! - opposite to situation at 150),
and threshold is about 1-4 units (then they quenched on pbar losses).

11. Tanaji on tune scan at 150: a) decay on p-helix is exp(-t), on pbar
helix it's more like exp(-SQRt(t)); b) tunescan has shown that minimal
losses on p-helix occure at Q_h="niominal"; Q_v="nominal"- 0.002(3),
though minimum is broad and variation is not very large (less than factor
of 2).

12. Frank summarized two attempts to calibrate FWs and SL emittances by
beam removal (scraping) : both were partial (some 20% of beam scraped)
and nothing solid can be concluded. He still needs full removal
(of pbars) by a single vert colliamtor at 980 to say smth about SL and FW.