[Olympus] Weekly Meeting Minutes for December 16
Brian S. Henderson
bhender1 at MIT.EDU
Mon Dec 16 14:25:46 EST 2013
Hello all,
Please find the minutes for today's OLYMPUS meeting below. They are =
also available on the OLYMPUS wiki, along with the minutes from the last =
two meetings =
(https://olympus-docu.hiskp.uni-bonn.de/dokuwiki/doku.php?id=3Dcompiled_min=
utes_of_the_weekly_meetings). =
Please let me know if you have any suggested changes or additions to the =
minutes.
Thanks,
Brian
------------------------------------------------------------------------
December 16, 2013
*
D. Hasell opened the meeting by announcing that the OLYMPUS detector
paper has been accepted for publication by NIM A.
o
One remaining issue: NIM editors say that Figure 2 will not
reproduce well in black and white, and they ask us to either pay
for color reproduction or to redo the figure. D. Hasell will
investigate the cost of printing the figure in color.
*
Prepared Talk: Status of BPM Calibration, U.Schneekloth
<https://olympus-docu.hiskp.uni-bonn.de/dokuwiki/lib/exe/fetch.php?medi=
a=3Dmeetings:bpm_calibration_december16.pdf>
o
U. Schneekloth reported on the progress of the survey and
calibration of the beam position monitors (BPMs), which is
ongoing in the DORIS hall.
o
His report included:
+
A description of the test stand
+
A discussion of the challenges to doing the calibrations
with the old (Neumann) readout electronics (pulse size too
small, problem with reflected signals, readout removed, etc.)
+
Some plots showing the preliminary results of a few
measurements, which included a plot indicating that BPM 2
was not being sufficiently well-measured with the current
test stand
+
A plan for improving the test stand to make the measurements
for BPM 2 work. These changes to the test stand will require
the machining of some new parts, and so they will not be
ready until some time in January.
+
A look at BPM data from the DORIS archives from during the
data runs
#
Comparisons of the Neumann and LIBERA readout systems,
and whether the Neumann readout can be calibrated
relative to a survey of the LIBERA readout
#
Examination of the dependence of the BPM measurement on
beam current (which was found to be negligible)
#
Dependence of the measurement on beam species (found to
be negligible for the LIBERA monitors, but substantial
for the Neumann readout).
o
Questions/Comments:
+
Question from M. Kohl: Is the LIBERA output already calibrated.
#
Response from U. Schneekloth: While the results from the
LIBERA system look reasonable, we do not yet have the
absolute offsets for the BPM data so in that sense the
measurement is not calibrated.
+
Question from M. Kohl: For what portions of the data runs is
the LIBERA data available?
#
Response from J. Bernauer: The LIBERA data is in the
OLYMPUS database for the entire fall run, but only in
the ROOT files for approximately the last half of the
fall. It should be possible to incorporate the LIBERA
data for the whole fall run, but for the February run
the data is only available in the DORIS archive which
may be difficult to properly synchronize. Hopefully, it
is possible to correlate the Neumann system with the
LIBERA system and use this for the February run and
other times when the LIBERA data is not available.
+
Comment from U. Schneekloth: Based on his studies, the
LIBERA/Neumman relative offsets seem to be stable, and so a
relative calibration is probably possible.
+
Comment from J. Bernauer: Raised a previously seen issue
that the measured beam position shifts during refills, and
stated that we don't know if this is a real effect from a
change in the beam orbit during refills or simply a response
from the electronics to the conditions during injection.
Since this could have an affect on SYMB measurements during
injection, we should investigate this further to determine
if it is necessary to veto SYMB counts from during refills.
+
Comment from U. Schneekloth: The Neumann system signals
certainly depend on the pulse shape/magnitude (which could
vary during refills relative to stable beam circulation).
+
Question from J. Bernauer: Is it possible to reinstall the
Neumann electronics for a calibration measurement?
#
Response from U. Schneekloth: Yes, but they likely won't
work in the test stand (pulse too small, problems with
reflected signals).
+
Question from M. Kohl: Is the Neumann system data in the
ROOT files?
#
Response from J. Bernauer: Yes, for all runs.
+
Comment from J. Bernauer: It would be good to study the
dependence of the LIBERA system output on the pulse size.
+
Comment from D. Veretennikov: Suggested using a test beam to
calibrate the BPMs.
#
Response from several people: This would likely be very
technically challenging, and it would be difficult to
secure test beam time anyway.
+
Comment from J. Bernauer: Please keep in mind that in the
OLYMPUS databased BPM refers to the Neumann system, which
BPM 1 upstream. The LIBERA monitors are called LIBERA in the
database, but LIBERA 1 is downstream.
+
Question from R. P=E9rez-Benito: Will there be a cooker plugin
for the beam position information?
#
Response from J. Bernauer: Yes, once the calibration
data is available, there will be a plugin that produces
the beam position and slope at the center of the target.
*
Further general questions and comments:
o
It was suggested by U. Schneekloth and J. Bernauer that the SYMB
group look into ep rates in the SYMBs, and that MC studies be
done to look into the sensitivity of the SYMBs to the beam
position. R. P=E9rez-Benito says these items are on the to-do list.
o
D. Hasell noted that only MIT students and L. Ice have signed up
to write the minutes for the weekly meetings, and suggested that
other groups from the collaboration should contribute to the
minutes since they are meant as a tool for the entire collaboration.
o
D. Hasell wished everyone a happy holiday season, noted that the
next weekly meeting will not be until January 6, 2014, and
attempted to call the meeting to a close.
o
M. Kohl brought up concerns regarding the "mini-review"
requested by the PRC in mid-January.
+
D. Hasell responded that he felt it was best to simply
report our status at that time without making any special
effort to make a detailed presentation on an specific
topics. He also felt that any such review would be more
useful if it was pushed to a later date.
+
M. Kohl concurred that moving the review to a later date
would be better.
+
S. Belostotski noted that it would be difficult for the PNPI
group to contribute results to a mid-January review due to
the holidays, and also supported an effort to move the date
back.
+
J. Bernauer noted that the frequency of PRC reviews is
taking away work time from the analysis and suggested that
we communicate this to the PRC.
+
D. Hasell noted that the next full PRC meeting is on April
24-25.
o
S. Belostotski asked if tracking will be done by April.
+
Response from J. Bernauer: The full process for all runs
will likely not be complete, but there will certainly be a
large set of tracked data (as there is already) with further
improvements in the tracking relative to the current tracked
files.
o
D. Veretennikov asked if it is predominantly wire chamber
calibration that is delaying the tracking.
+
Response from J. Bernauer: The main issue is with the wire
chamber time-to-distance calibration, which is being
actively worked-on and is likely to be improved
significantly in the near future. Also, there are problems
with the tracking at certain angles, but data from the ToFs
is being used to help resolve these issues.
o
S. Belostotski commented that we should aim to have the
luminosity resolved by April.
+
J. Bernauer noted on this topic that there are significant
issues with both luminosity monitoring systems that need to
be addressed before a statement on the luminosity can be made.
+
D. Hasell noted that data from negative field runs may be
useful to illuminate solutions to problems in the luminosity
monitors, since only the wire chambers are adversely
affected in the negative field setting.
#
R. P=E9rez-Benito commented that there are no negative
field runs in the current analysis focus set, but others
noted that it would be easy enough to look at files from
other periods since many aspects of the luminosity
analysis (especially for the SYMBs) don't require wire
chamber track data.
o
D. Veretennikov commented that he is still having problems with
the tracked proton files and sees very few correlated
proton+lepton in lumi arm events when he combines files.
+
Response from J. Bernauer: The missing events in the WC
tracked files are only at the end of the run and thus should
not affect the event-by-event synchronization. He suggested
using the Event Display to identify events where the proton
track is missed, and to send those event numbers to him so
that he can investigate why the tracker misses them.
o
N. Akopov asked if more runs will be tracked with the same
algorithm used to produce the current tracked files.
+
J. Bernauer replied that further improvements (mostly
regarding the time-to-distance) will be made before tracking
more files. If people need more statistics than what is
available already, they should let him know.
o
N. Akopov commented that when he looks at the tracked files, he
notices that there are few events with a single track in each
sector.
+
J. Bernauer says this is due to the fact that the tracker
typically passes multiple track for a single event,
generally trying multiple particle types for a given hit
combination and so there are indeed few events with a single
track on each side.
+
D. Veretennikov asked if the tracker will continue to
produce multiple tracks per event in the future.
#
J. Bernauer replied yes, since this is the best way to
approach things. Other detectors can be incorporated to
help with particle ID and to select the correct
candidate track.
*
There were no further comments/questions, and so D. Hasell called
the meeting to a close.
Minutes compiled by: --- /Brian S. Henderson <mailto:bhender1 at mit.edu> =
2013/12/16 20:22/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.mit.edu/pipermail/olympus/attachments/20131216/724760d0=
/attachment.htm
More information about the Olympus
mailing list