Minutes of the 08/09/02 Tev Dept Meeting


1. M. Church informed: 
a) 6 weeks shutdown will begin (tentatively) Jan 6, 2003;
b) beam studies will take place every other week (instead of every week);
c) Tev goal is 4e31 by 10/01; 
d) there will be more Recycler Pbar studies.

2. Jim Steimel reviewed transvesre damper status: 
a) the first (horz) damper parts are either bench tested or almost complete; 
b) damper commissioning will start mid-next week - we plan a shift of studies 
   for them at the end of the next week; 
c) the second (Vert) system will be fabricated in 2-3 weeks after that using 
   parts of Q-meter will be used for that.

3. Vladimir will conduct performance reviews with 8 people next Mon and Tue.

4. XiaoLong Zhang presented summary of three stores since last Fri: avg
Lumi about 18e30, there was transverse blow-up in pbar beam in store #1634
--> large emittances. SyncLite reports very larger emittances (several
times larger than effective emittance and FW emittance), especially for
pbars. A.Hahn changed SL pbar scaling factor - many people think it was unwise
and that any move with diagnostics should be first coordinated
with Tev group since we rely on them. Proton lifetime early in store
somewhat better (50 hrs) but still too low (should be >200 hrs). We were
fighting instabilities all week. Vladimir summarized comments of many:
a) do not stay at flat top long, go into squeeze ASAP; 
b) chromaticities and SQ help in may cases; 
c) looks like pbars somewhat stabilize the instability; 
d) somebody in MCR should be ready to change C_v,h, SQ,
   or tunes tunes during the shot-set-up: instability is slow and can be
   damped before emittances are greatly blown. 
Dean questioned usefulness of pilot 36x0 stores as they do not reflect instability
conditions in 36x36. Last store aborted during scraping - still not
well understood.

4. Mike M finished orbit smoothing and is thinking about operational orbit
smoothing before every shot. He adjusted D0 position following their
request (admitted that at some moment he lost track of the orbit changes
- requested that everyone who does the orbit changes should report that
properly and explains the reason for the change). F0 and A0 bumps are still
there - no big need yet to remove them. He and Tan measured and analyzed
the tune/coupling drifts at 150: tune drift is repeatable, coupling drift
seems to be dependent on time duration of the previous store (but we
regularly do dry squeeze, so the difference will not affect us in near
future). He will implement tune/coupling drift compensation in about 4
weeks.

5. Valery and Aimin tuned the currents in A1/P1 injection lines and
reduced hor emittance dilution by 15% (some 2pi on top of 15pi) , there is
45% left for further improvement. Changes in vert plane are minimal and
not that effective. P1 line magnets are tuned better and did not require
any significant changes (so, do not expect improvement of proton emittances
at injection). Next step - differential orbit measurements.

6. Vladimir informed on an experiment with 36 bunches at 980: when VTICK
(vert noise source) was turned ON the vert and hor emitaance growth rate
increased significantly, while longitudinal rate went down. Slava Danilov of ORNl
is analysing the data - expect conclusions.

7. Paul Lebrun analyzed HEP store data and found no solid evidence that 
dsigma_s/dt or dN_p/dt depend on proton bunch number (--> no transient beam
loading effect). As for dSigma_s/dt vs N_p: yes, there is direct
correlation in some stores, but in the dedicated stores with 3 different
intensities long-growth rate does not depend on N_p (except very early in
store). He also calls for experiment on wether Flying Wires significantly
blow p emittances, as the Moliere calculations do not agree with
observations by factor of 2, and no emittance growth can be seen at 150
GeV with helix opened (as the beams are being shaved).

8. Kip Bishofberger presented preliminary results of the TEL shift:
p-lifetime with TEL ON is strongly dependent on TeV tunes.

9. Alvin used store 1613 data to calibrate CDF halo counters (in this store one
RF station tripped OFF and later TEL tripped for some time, too).
Conclusions: transverse losses are factor of 4-5 larger than what it
should be due to vacuum --> another loss mechanism (Tunes, chroma's),
losses out of RF bucket calibrated again. It's not clear how particles
were lost when one of the bunches blew-up longitudinally at the end of
that store.