Minutes of the Aug 17 Tevatron Dept Meeting

https://indico.fnal.gov/conferenceDisplay.py?confId=1222

* News (Ron) - Any Tevatron Dept members who wich to attend the next USPAS
session in Jan 2008, please let me know.  More information can be found at
http://uspas.fnal.gov.

* Shutdown Status (Ron for Jim Volk) - (Best wishes to Jim who is recovering
from a bicycle accident this morning.)  Magnet roll measurements were completed
this week - we'd like to unroll ~50 magnets with roll > 1 mrad magnitude.  9-10
of those need to have stands replaced in order to align them; it would be nice
to replace another 9-10 of the remaining worst ones.  The B0 and D0 as-founds
have been completed; we will have meetings next week to discuss if/what to 
realign.  The D16-1 quad has been unrolled; D1 vacuum certification is
underway.  The C4 vacuum certification is essentially complete; the (small) 
cold leak being searched for vanished at room temperature - they'll check again
@ 20K.  The E1 warm-up should begin today.  The new TEL-1 collector was 
installed.

* New Collision Helix Study (Ron) - With the last shot of protons before the
shutdown began, we looked at the new collision helix (flipped horizontal in
the short arc B0-C0-D0).  We were able to get the desired tunes on both proton
and pbar helices with good minimum tune split (0 on proton helix, 0.003 on pbar
helix).  The S4 feeddown elements in C sector required opposite polarity (as
expected), but we needed to change their value independently from the S4 
F-sector elements to get good pbar helix coupling; vertical orbit offset
through sextupoles could be the explanation.  This behavior may require
modification of the C49 application to put different current in magnets of the
same family.  The HEP tune mults worked as expected using different sign on the
S4 C-sector elements.  Helix closure will need to be checked during start-up.
The orbit changes reported by synch-light (@ C11) were as expected.  We will
need to modify the squeeze tables for startup to accomodate the new separator
and feeddown settings; we could delete some now redundant steps since the
B17H separator does not need to change polarity.  Alex suggested "moving" some
of the extra steps to near the end of the squeeze to allow a smoother 
transition to the low-beta helix.

* AC Dipole Measurements on New Helix (Ryoichi Miyamoto) - During the above
study of the new collision helix, Ryoichi measured the new proton and pbar
helices (vertical only).  (These may be the first low-beta pbar helix 
measurements made.)  His beta* measurements on the proton helix (28 cm @ CDF,
31 cm @ D0) are consistent with AC dipole measurements made on May 27 - before
the second order chromaticity sextupoles were implemented. The vertical beta*
on the pbar helix were measured to be 36 cm.  There also seemed to be a 
significant beta-beat on the pbar helix. Alex pointed out that the larger
pbar helix beta* may benefit protons since the pbars would have larger cross
section with the larger beta*.  Yuri suggested making TBT measurements to get
the horizontal beta functions to make sure they are similar so as not to have
elliptical beams.  Valeri commented that it would be better to use a coupled-
beta function model to interpret the results.

* Toward Routine Operation of the Digital Tune Monitor (Seva Kamerdzhiev) -
Seva and Alexei Semenov tested the vertical proton system with the "final"
version of hardware to control the kicker and measure the bunch-by-bunch tunes.
The system works well - they used it during 2 stores before the shutdown.
The system is controlled via LabView now, but they are working on integrating
into ACNET.  The hardware for the remaining parts (proton horz, pbar horz and
vert) is being procured/made - hopefully all will be complete by the end of the
year.  Other new features include bunch-by-bunch gains and feedback, doing
the FFT inside the FPGA, and upgrade to 100 Mbit ethernet.

Next meeting in two weeks.