Difference between revisions of "GlueX TOF Meeting, November 3, 2015"
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GlueX Time-of-Flight Meeting<br> | GlueX Time-of-Flight Meeting<br> | ||
− | Tuesday, | + | Tuesday, November 3, 2015<br> |
− | 11:00 am | + | 11:00 am EST<br> |
JLab: CEBAF Center, Room F326/327 | JLab: CEBAF Center, Room F326/327 | ||
Line 7: | Line 7: | ||
# Announcements | # Announcements | ||
− | # Review of [[GlueX TOF Meeting, September | + | # Review of [[GlueX TOF Meeting, September 22, 2015#Minutes|minutes from September 22]] |
# Calibration Status FSU | # Calibration Status FSU | ||
# Calibration Status JLab | # Calibration Status JLab | ||
+ | # NIM Article | ||
+ | |||
==Communication== | ==Communication== | ||
Line 22: | Line 24: | ||
Present: | Present: | ||
− | * '''FSU''': Brad Cannon, Sasha Ostrovidov, Aristeidis Tsaris | + | * '''FSU''': Hussein Al Ghoul, Brad Cannon, Sasha Ostrovidov, Aristeidis Tsaris |
− | * '''JLab''': Mark Ito (chair), Simon Taylor, | + | * '''JLab''': Mark Ito (chair), Simon Taylor |
+ | |||
+ | There is a recording of this meeting at https://bluejeans.com/s/8MQf/ . | ||
+ | |||
+ | ===Calibration with Cosmics=== | ||
+ | |||
+ | Sasha gave a report on recent work. | ||
+ | |||
+ | * He has succeeded in taking cosmic data, but had a couple of difficulties: | ||
+ | *# He needed to attempt to start runs several times before getting any triggers at all. He suspects that with multi-block readout of the CAEN TDCs, the token passing between modules would stop, hanging the system. | ||
+ | *# ROCTOF1, which houses the FADCs, would crash in minutes from the start of the run. A hard reboot was needed to get things going again. | ||
+ | *#* This problem has resolved itself recently. | ||
+ | ** In the end he got a few times 100 k events. | ||
+ | * The trend of higher gains at the edges of the arrays seen in beam data is also seen in cosmic data. | ||
+ | ** This rules out the magnetic field, or a systematic problem using beam tracks. | ||
+ | ** Possible culprits: | ||
+ | *** Different HV supplies than those used at FSU. | ||
+ | *** Different HV cables. | ||
+ | ** He is working on a program to adjust HV to equalize gains. Data will be taken, gains measured, HV adjusted, and process iterated. | ||
+ | ** He is also seeing a difference in the gain when comparing a hit in the middle of the paddle versus one near the ends, even after accounting for attenuation. The gain is about 10% higher near the ends. | ||
+ | * He is trying to judge the effect of gain calibration using a set of "tracks" in the TOF in cosmic data. He requires 5 counters minimum. The yield of such events is extremely low, about one part in ten thousand. | ||
+ | ** The trigger rate is about 600 Hz. | ||
+ | ** The threshold for a single FADC channel to be read out is 500 counts. The trigger threshold on the sum is about 50,000 typically, but other values have been tried. | ||
− | + | ===Calibration=== | |
− | * Brad is | + | * Brad is in contact with Sean Dobbs about a plug-in to be used in the calibration challenge. |
− | * | + | * He is also cleaning up the script to drive the calibrations already done. |
− | + |
Latest revision as of 16:08, 9 November 2015
GlueX Time-of-Flight Meeting
Tuesday, November 3, 2015
11:00 am EST
JLab: CEBAF Center, Room F326/327
Agenda
- Announcements
- Review of minutes from September 22
- Calibration Status FSU
- Calibration Status JLab
- NIM Article
Communication
- The BlueJeans Meeting number is 350 531 998.
- Enter BlueJeans Meeting
Slides
Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2015
on the JLab CUE. This directory is accessible from the web at https://halldweb.jlab.org/talks/2015/ .
Minutes
Present:
- FSU: Hussein Al Ghoul, Brad Cannon, Sasha Ostrovidov, Aristeidis Tsaris
- JLab: Mark Ito (chair), Simon Taylor
There is a recording of this meeting at https://bluejeans.com/s/8MQf/ .
Calibration with Cosmics
Sasha gave a report on recent work.
- He has succeeded in taking cosmic data, but had a couple of difficulties:
- He needed to attempt to start runs several times before getting any triggers at all. He suspects that with multi-block readout of the CAEN TDCs, the token passing between modules would stop, hanging the system.
- ROCTOF1, which houses the FADCs, would crash in minutes from the start of the run. A hard reboot was needed to get things going again.
- This problem has resolved itself recently.
- In the end he got a few times 100 k events.
- The trend of higher gains at the edges of the arrays seen in beam data is also seen in cosmic data.
- This rules out the magnetic field, or a systematic problem using beam tracks.
- Possible culprits:
- Different HV supplies than those used at FSU.
- Different HV cables.
- He is working on a program to adjust HV to equalize gains. Data will be taken, gains measured, HV adjusted, and process iterated.
- He is also seeing a difference in the gain when comparing a hit in the middle of the paddle versus one near the ends, even after accounting for attenuation. The gain is about 10% higher near the ends.
- He is trying to judge the effect of gain calibration using a set of "tracks" in the TOF in cosmic data. He requires 5 counters minimum. The yield of such events is extremely low, about one part in ten thousand.
- The trigger rate is about 600 Hz.
- The threshold for a single FADC channel to be read out is 500 counts. The trigger threshold on the sum is about 50,000 typically, but other values have been tried.
Calibration
- Brad is in contact with Sean Dobbs about a plug-in to be used in the calibration challenge.
- He is also cleaning up the script to drive the calibrations already done.