Minutes of the 16 Feb 2007 Tevatron Dept Meeting

https://indico.fnal.gov/conferenceDisplay.py?confId=583

* Weekly Operations Summary (Bruce Hanna) - The Tevatron delivered over 36 1/pb
to CDF and D0 this week.  There were 6 HEP stores over that period; the 
initial luminosities luminosities ranged from 149 to a new record 284 E30 cm^-2
s^-1 on store 5226.  Two stores ended prematurely - store 5226 (the record
store) ended after 10 hours when the A1 wet engine failed and caused a quench;
store 5229 ended after 12.5 hours when an LCW leak in a power supply rack
caused the HA13 dipole corrector supply to trip off (other components in that
rack got soaked, too).  In store 5228, the proton halo was higher than normal
at the start of the store, and the proton vertical tune was shifted too high
in an attempt to reduce the proton losses.  That tune got too close to the 3/5
resonance and proton emittances jumpmed up causing a sharp drop in luminosity
lifetime.  The tunes were restored to recover the lifetime, and the real cause
of the high losses was identified - the E03V collimator did not end up in a 
correct position.  A round of orbit smoothing was done to try to reduce the
D0 losses during the squeeze.  Studies for the new sextupoles, crystal
collimator and TEL-2 were done.

* Status of New Sextupoles (Jerry Annala) - We are looking for incorrectly
connected sextupoles by doing large 3-bumps through all the new sextupole
elements with and without current in them and measuring the tune changes.  The
tunes agree with Alex's model very well - except for A25.  We may have
discovered a longstanding wiring mistake on that spool; the connections for the
quadrupole and sextupole in that spool may have been swapped.  That spool is
a very early model that is a little different than most others.  More
archaeology and other investigation is needed to verify a wiring mistake there.
We need more study time to complete these 3-bump studies.

* Quad Gradient Errors (Alex Valishev) - Motivated by the 3-bump investigation
of the new sextupole circuits, Alex has looked at existing lattice measurements
for errors in quadrupole gradients @ 150 GeV and low-beta.  Indeed, he sees
significant deviation (> 1%) at A25 where the quad and sextupole spool 
elements may be swapped.  (See above topic.)  Alex also "found" the quad
element at B43 that is jumpered off.  There are several other locations around
the ring that merit further investigation.

* b2 Drift @ 150 GeV (Norman Gelfand) - Norm has revisited a longstanding
puzzle with the Tevatron - why do the tunes drift as much as they do @ 150 GeV?
(The drift is well compensated, but what is the source of the drift?)  Norm
added the in-situ magnet survey data to the usual MAD model including the MTF
higher multipole measurements and closed orbit measurements.  The observed
tune shifts are ~factor 10 larger than expected from the b2 drift in the
dipoles alone.  However, Norm can reproduce the observed tune drift if the 
the kbendq (strength of zero-length quadrupole element at the dipole end in 
MAD, which is understood to be due to the feed down of the sextupole moment in
the dipole and a non-central tractjory of the beam in the dipole) also varies
with time at 150 GeV.  It might be nice to make new end and body b2 
measurements at the magnet test facility to supplement Norm's model.

* Pbars in the Abort Gap (Ron Moore) - After a TRF2 trip in store 5208, there
was clear evidence that pbars (as well as the usual protons) got knocked into
the abort gap.  Randy Thurman-Keup's pbar abort gap intensity monitor T:AGAGI2
showed less than 1 E9, but there was a clear jump at the time of the RF trip
and a slow decrease ~15 minutes later as those pbars spiraled into the 
collimators as they lost enough energy from synchrotron radiation.  CDF's 
pbar abort gap loss counter reading (C:B0AAGC) became elevated and spiky as
the DC pbars reached the collimators.  This was the first time we have seen
(or maybe noticed) DC pbars in the abort gap.  There was similar behavior after
the TRF1 trip in store 5221, but the pbar abort gap intensity and CDF pbar
abort gap loss counter reading were much smaller (~factor 4 less).

* Plans for Next Week

   - Continue delivering quality luminosity to the experiments.
   - Try to reduce the D0 losses during the squeeze even more.
   - Complete check-out of new sextupole elements (Jerry, Alex; proton-only
     or during shot setup)
   - TEL-1/TEL-2 studies (the usual gang; in-store/end-of-store)
   - Crystal collimator (Dean; end-of-store)
   - Transfer line matching with IPM (Andreas; shot-setup, proton-only)
   - Check-out E48 bumper as abort gap cleaner (Jim, Elmie; proton-only)
   - New Cogging between Pbar Transfers (Ron; shot-setup)
   - couple of others...