[Bteam] No meeting today, just an update for your entertainment
Arne Freyberger
freyberg at jlab.org
Wed Sep 30 08:52:50 EDT 2009
NO BTEAM MEETING TODAY!! Just a status update
1 2009-09-30 Wed 14:00 No meeting today
There will not be a Bteam meeting today.
* Tuesday's activities
The machine was down for 2 shifts of C50 commmissioning on NL04
Tuesday. During that time the following activities were performed:
o Fixed the laser power meter
o Measure QE, value was about 0.18% for A laser
<http://opweb.acc.jlab.org/CSUEApps/elog/entry/1489558>
o spot move
o search for source of 35kHz current fluctuations, source
traced to the Gun HV. No plans to remove the noise. -
<http://opweb.acc.jlab.org/CSUEApps/elog/entry/1489552>Measure
QE at new spot, QE now 1.2% for A laser
<http://opweb.acc.jlab.org/CSUEApps/elog/entry/1489598>
o Install beat frequency module to support 31MHz operation,
found some problems with the hardware, hope to fix and
install today. 31MHz beam to Hall-C moved to Thursday.
People involved in making 31MHz beam *will* meet after the
1:30 meeting to discuss the status and make final
preparation plans.
o Operational
<http://opweb.acc.jlab.org/CSUEApps/elog/entry/1489619?PHPSESSID=8434b04d77b6e49c87bccc06a1b681c2>
Emaxes for 3 of the 4 remaining NL04 cavities set and now 7
of the eight cavities are in *operation!!!!*
o NL04-3 has a cabling issue and an access will be needed to
get this cavity online. This work will be deferred to next
CHL trip or winter down? Up for discussion.
o Hall-C dump pump repaired, installed and returned to operation
o HKS magnet limits adjusted to support upcoming energy shifts.
Machine restored reasonably quickly from the down activity and the
program to send beam to HKS with small energy shifts is on schedule.
* Program for the upcoming week
o HKS special energy runs
We are presently, 7:30am Wednesday, delivering beam at -1MeV
from the nominal energy. HKS expects to finish data at about
8:30am at this energy. From there the program is as follows:
+ Configure the machine +20MeV above nominal energy (4hrs)
+ Two shifts of HKS data taking (16hrs)
+ Restore machine to nominal energy (4hrs)
+ 31 MHz run to HKS (2hrs?)
+ Back for nominal program, 100? A to Hall-A (3-pass),
30? A to Hall-C (2-pass)
o The return of Hall-B
Hall-B will return to 5-pass operation sometime in the next
few days, earliest date is Thursday swing, but we will hear
more definitive times at today's 1:30 scheduling meeting.
o Happex-III Phase advance
Conversation with Kent yesterday about phase advance in the
line. The last quad change
<http://opweb.acc.jlab.org/CSUEApps/elog/entry/1489207>
improved the situation and "it might be good enough". I
conveyed our plan to take data, quad scan at 1C05 and
raytrace through the A line, in order to have some data to
chew on while they decide if the phase advance is adequate.
Kent wasn't too keen on the idea of taking the data right
away and suggested that we wait until 100? A CW production
has been established for a few shifts. I disagree, most of
the work in establishing CW operation has been orbit
steering, not quad tweaking. So the optics are not changing
and we should take the data as soon as possible.
Presently it looks like Hall-A will be getting beam back
about noon on Thursday. After the 31 MHz run to HKS.
Kent expressed his view that since the optics are linear it
makes no difference if one or two correctors are used. This
is true, accept that aperture issues are non-linear and it
may be that by using two correctors one can better utilize
the available aperture to achieve the required phase
advance. This is one more reason to put apertures in the
elegant decks, so that we can explore these issues.
Riad was present and also suggest that perhaps bigger kicks
should be tried and Kent thought this was a reasonable
suggestion.
So the phase advance is still an open issue, developing
tools/techniques to easily and deterministically setup the
desired phase advance in the A and C line need to developed.
We will be dealing with parity experiments until the end of
6 GeV operations and they will be a large part of the 12 GeV
program as well.
2 2009-09-28 Mon 13:30 Two things
I'd like to have a meeting *today* at 13:30 to discuss the HKS energy
changes and the Happex-III phase advance.
* HKS energy changes
o Physics consensus on the allotted amount of time Arne
Still no word from Dennis on the agreed upon time allotment.
2009-09-28 Mon 14:48
This just in from Dennis
Dennis:
I talked to Nue some more. He would be willing to go down to one
major energy change (+20MeV), but get more statistics. It doesn't
save much time , but reduces risk because of fewer energy changes.
So the request looks like
Pulsed beam 2hr (spacing between micropulses to do Time of flight studies.)
+1 MeV 4hr (including tuning)
-1 Mev 4hr (including tuning)
+20Mev Tune 4hr
+20MeV data 16hr
Restore 4hr
So about 4.25 shifts.
Steve
o HKS desired energy shifts Spata
+ ± 1 MeV shifts
Small ± 1 MeV energy shifts, with the energy
acceptance of the machine. Hall-C does not need high
currents for these energy shifts. four hours of data
taking per point.
Hall-A beam during this part of the test? one-hour to
perform these shifts.
# dial in the shift into the energy lock.
# adjust Hall-C arc dipole to accomodate this
change? No leave dipole strings alone.
# Adjust Hall-A string? Might need to do this
since Hall-A is running at 100?\text{A}.
# FFB in relative mode in C due to the energy offset.
# DW1, DW2 small adjustments to keep beam on dump
viewers.
+ +20 MeV shift
This will require a tune of the entire machine (after
it is scaled). It will go faster if we leave Hall-A
out of the mix.
# splitter stays unchanged
# DW1 goes down
# DW2 goes up
# change dipoles, quads, correctors.
# Raise DZ HMAX, HOPR need more headroom. Needs to
goto 320 Amps.
# Steps
* load scaled allsave, in the special file area
* relem at the new energy
o Schedule
+ Dump pump issues Arne
Presently Hall-C dump pump is broken and Hall-C is
limited to 3.5?\text{A}. The pump will be repaired
sometime on Wednesday.
When the pump is repaired and ready to be installed,
there will be a 2hour interruption to beam delivery to
Hall-C during this period.
The pump will have to fixed before the 20 MeV shift
since HKS wants to run at full current for this
portion of the test.
o Plans
+ Yan to develop ATLIS
+ Benesch to scale the file
o Owner
+ Spata to own the process, review the ATlis, and review
the scaled allsave file
* Happex-III phase advance
o Happex-III requirement Alex Jay
+ Position at 1H04A, 1H04B
+ angle at 1H04A, 1H04B
+ Energy shifts
o Present status Alex Jay
Using various settings of the quadrupoles after the Compton
polarimeter Jay has altered the phase advance for Hall-A. It
has improved, but we are waiting for word if it is good
enough. Presently they have 20 ? radians in horizontal, 8 ?
radians in the vertical plane. Changes are coupled to
changes in the rastered beam size. These two requirements
are often in conflict.
o Hardware
Qweak is moving towards powering two coils simultaneously
with different amplitudes. Hall-A has the same hardware
installed but are not using the coils in this manner. Why
not? Need to write a letter to Kees and Kent. We want to use
the coils as designed for PVDIS and Prex and possibly for
Happex-III.
o Plans if present status is unacceptable
Upon resumption of beam delivery to Hall-A, after C50 work
and HKS energy shifts, we will take a couple of hours to
perform:
+ Ray-trace data through the hall-A line
+ New set of harp data at 1C05
+ ????
o Owner
Jay and Alex will work on this problem. Ryan will help by
collecting the ray-trace data and assisting the analysis.
3 2009-09-23 Wed 14:00 No meeting
There will not be a B-Team meeting today.
* Brief status Report
Machine is running well since last Wednesday transport clean up.
It is unclear if the Compton rate reduction was due to shifting
the doglegs "out of the mud" and fixing the separator, or the
thorough cleaning up of separation and transport lines by MikeS
and Yan. The reason we are confused is due to the fact that the
Compton detector was in a non-standard configuration all day
Wednesday. Nevertheless the machine is in a "good place" due to
all these efforts.
The Beam Loss Accounting system is still has a large amount of
noise, but the transport appears to be clean if one looks at the
Beam Loss Monitors, Beam Scraping monitors, Hall-B harp scans,
Hall-A compton rates. Yesterday the 500KeV kicker sensor was
jumpered out to remove a 80Hz intensity fluctuations in order to
minimize the issues with BLA system. With the this sensor jumpered
out the 80 Hz noise was removed, but the BLA still fluctuates
between 0 and 1.7 ? A of loss.
The main issue this week have been establishing robust FFB
configuration to both A and C. Sometime Monday morning, things
drifted such that disabling/enabling FFB in the A line caused ep
ion chamber trips. By carefully calibrating the FFB response
matrix using low 5 to 10 ? A beam current, the FFB system appears
to be more stable. Scott Higgins, Pete Francis and Yan worked out
the FFB subtleties yesterday.
There was a spurious, unexplained vacuum event in Arc1 earlier
this week. The excursion was not significant enough to close
valves, but three ion pumps reported elated vacuum levels.
o Parity Quality-Happex
Happex is not reported any information on parity quality so
we don't know where we stand on this issue, only that the
user claims there are more pressing issues. The most
pressing issue to Happex is the phase advance at the last
two BPMS, Alex and Jay have some plans to address this at
Happex's request.
o Energy Spread-HKS
Energy spread appears to be reasonably under control. The
OPS crews need to keep running KREST and chase down
pathlength errors as much as possible to keep the energy
spread under control. Without knowing the ?, ? and ? and the
3C12 dipole the exact value for the energy spread is
unknown. The Synchrotron Light Interferometer measures 3.5×
10^-5 , which is an upper limit as long as the ? is near the
design value of 4m.
Beam transport to HKS has been routine over the week, no
issues other than FFB.
o Hall-B
Hall-B finished their experiment this morning and will down
for the next nine days to reconfigure. This experiment
started in the Winter run this year. For this Fall09 run
period Hall-B did not achieve its goals.
* On Call
Reza was on-call last week. This week it is Geoff Krafft.
Date: 2009-09-30 08:51:43 EDT
HTML generated by org-mode 6.30trans 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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