[Bteam] notes/scribbles from last week's Bteam meeting
Arne Freyberger
freyberg at jlab.org
Tue Dec 22 13:38:14 EST 2009
B-team Meeting Notes
1 2009-12-23 Wed 13:01 No Meeting This Week
Happy Holidays!!! See you next year!
2 2009-12-17 Thu 13:30 Notes
Due to Hall-A collaboration meeting the BTEAM meeting has been moved to
Thursday at 1:30pm MCC conference room.
2.1 Hall-B Dark matter experiment Stepanyan
Stepan will introduce us to a proposal for a dark matter search in
Hall-B that will likely need some optics support.
Both Hall-A and Hall-B have proposals going to PAC. Same SLAC group.
Various cosmic ray and satellite measurements are hard to explain with
standard cosmological models.
Two possible scenarios: between the tagger exit and tagger dump or
somewhere in the Moller region.
Moller region will require a combined optics. The present proposal is to
use the Moller quads to pull out the e^-e ^-e ^+ triplets into a
calorimeter. Stepan needs help in verifying that the Moller quads can be
used in this fashion and that the primary electron beam can be cleanly
transported to the Tagger dump.
There will be a collaboration meeting on January 21 and 22, Stepan has
requested that some knowledgeable beam transport (Bteam) staff attend.
2.2 PRex requirements ATTACH
* Spot size at target < 50 ? m
PRex adjust the spot size at target down to 50 ? m. The nominal
design value for 1 pass, 1 GeV beam is a bit larger than 100 ? m.
This requirement will need new optics that also respect the
requirements at the compton and other tight spots on the A line.
Such a tight beam size will not be possible with combined optics.
2009-12-21 Mon 13:06
Jay has worked out an alternate optics, this optics needs to be
reviewed and evaluated before acceptance.
* Helicity Reversal
Need to touch base with Hall-B, make sure they are ready for 240
Hz. Any changes in helicity reversal during the run need to be
coordinated with Hall-B.
o TODO Confirm Hall-B 240Hz capable Riad
DEADLINE: 2010-01-13 Wed
* Polarization Orientation
At present the transverse component is nulled at the 2% level. To
achieve the desire 1% value will require effort. This effort is
mostly beam time, although it is not guaranteed that vertical
components at the 1% level can creep in as the beam traverses the
machine. To achieve better than 2% more dedicated time in the
injector will be required.
PRex will ask for transverse measurements in the injector more
frequently than previous experiments. About once per week?
* Priority in source configuration
Hall-B will, at times, like to control the Hall-B charge
asymmetry. They may not do this at the level that PRex would
like.....
* Time for source configuration
There is not much time for work on the source. The two wien system
must be installed and commissioned and commissioning higher
voltage gun operation is also scheduled. With such a tight
schedule it is not possible to have PRex staff perform laser
alignment. The present plan to have the source group configure the
gun as best they can, including laser alignment. Have PRex
collaboration make measurements and if the configuration is
unacceptable, time will be made available to fix the problems.
* Control of the Source Lasers
Aside from Hall-B IA control, this is not an issue
* Electron Beam Transmission
This is not a spec. Yes we will configure the injector for minimal
transmission, but if parity quality and compton polarimetry
functional who cares what the transmission is.
* Helicity Correlated Beam Size
Will need time to measure the laser spot size for the two
different helicity states. This issue drive the new desire for
small beam size at the target.
* Beam and halo acceptable for Compton Polarimeter
The real specification here, is a compton polarimeter that
achieves 1% polarization error and beam that is acceptable for
PRex spectrometers. Previous changes to the Compton polarimeter
and beam tune issues have made the Fall run rather challenging.
The compton will be modified during the Winter down. Specific time
for commissioning the Compton and the beam needs to be a priority
for the commissioning period.
* Fast feedback
Stable optics near design will help make the fast feedback system
robust. This should be specifically addressed during the
commissioning period.
* Beam Modulation
The PRex collaboration needs to communicate requirements and
proposed changes to the software group as soon as possible if they
want these changes ready for the experiment.
* Phase Advance
Two coil modulation will help achieve the desired phase advance.
* Random Beam Jitter at Target
* Radiation levels
The large beam current, modest energy and thick target will
produce quite a hot environment in the Hall. We need to be
prepared to deal with dieing IOCs.
o TODO Communicate High Rad levels in A to Controls and I&C Arne
DEADLINE: 2010-01-13 Wed
Not sure what we can do. We have one VME bus extender ready
(for QWeak). Perhaps we should buy another. How many
accelerator IOCs are in the Hall?
2.3 Shutdown Issues
* Shim missing on 2T line
2009-12-22 Tue 13:34
Walk the line this morning did not see anything amiss. But did not
bring a flashlight, so I could have missed something.
* Droop in Injector
Need to walk the injector chicane region to see if there is a
visible displacement of the beamline.
2.4 Next Year
* Tiefenback!!!!
* QWeak Beam requirements ATTACH
QWeak has forwarded their beam requirements for us to review.
Date: 2009-12-22 13:36:19 EST
HTML generated by org-mode 6.33trans in emacs 23
--
Arne Freyberger
Director Operations Department
Jefferson Lab Phone: (757) 269-6268
12000 Jefferson Avenue Pager: (757) 584-6268
Newport News, VA 23606 Email: freyberg at jlab.org
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