Difference between revisions of "GlueX Start Counter Meeting, March 23, 2017"
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# Review [[GlueX Start Counter Meeting, March 9, 2017#Minutes|minutes from the last meeting]] | # Review [[GlueX Start Counter Meeting, March 9, 2017#Minutes|minutes from the last meeting]] | ||
# Run Recap | # Run Recap | ||
− | # Calibration | + | # Calibration |
+ | # Time-dependent geometry adjustments | ||
+ | # Mcsmear procedure and parameters for the start counter | ||
# NIM/TDR | # NIM/TDR | ||
# Action Item Review | # Action Item Review | ||
Line 23: | Line 25: | ||
Talks can be deposited in the directory <code>/group/halld/www/halldweb/html/talks/2017</code> on the JLab CUE. This directory is accessible from the web at https://halldweb.jlab.org/talks/2017/ . | Talks can be deposited in the directory <code>/group/halld/www/halldweb/html/talks/2017</code> on the JLab CUE. This directory is accessible from the web at https://halldweb.jlab.org/talks/2017/ . | ||
+ | |||
+ | ==Minutes== | ||
+ | |||
+ | Present: | ||
+ | * '''FIU''': Mahmoud Kamel | ||
+ | * '''JLab''': Thomas Britton, Mark Ito (chair), Simon Taylor | ||
+ | |||
+ | There is a [https://bluejeans.com/s/7ITwj/ recording of this meeting] on the [https://jlab.bluejeans.com/ BlueJeans site]. | ||
+ | |||
+ | === Calibration Update === | ||
+ | |||
+ | Mahmoud showed [https://halldweb.jlab.org/talks/2017/SC_Meeting_03-23-2017.pdf the latest results] from his time-walk calibration. | ||
+ | |||
+ | * He showed plots of pulse-height (in ADC counts) vs. z-position (as measured by charged tracks) at the point of intersection with the start counter. Clear minimum ionizing peaks are visible with amplitude increasing with increasing z. | ||
+ | * He then showed the difference in TDC time and ADC time as a function of pulse-height (in ADC counts) and the time-walk correction he derives from these plots. He then showed the same TDC-ADC time vs. pulse-height plot after the correction is applied. The pulse-height dependence is largely removed, as expected. In particular, there does not appear to be a large failure of the correction at large pulse-height. | ||
+ | |||
+ | === Propagation Time Correction Constants === | ||
+ | |||
+ | Although there was no smoking gun in the time-walk calibration, Mark thought that, at least for now, we should go with the single-linear fit in the nose region to for the propagation time correction until that non-linearity is understood. The current constants being used in the monitoring run are consistent with that. | ||
+ | |||
+ | === Time-dependent geometry adjustments === | ||
+ | |||
+ | We discussed a few issues: | ||
+ | |||
+ | * Although the start counter is mounted on the target cart its position is physically tied to that of the target. In the HDDS representation, the two positions are specified independently. | ||
+ | ** Simon reported that that the target position has varied from run-to-run by as much as a centimeter. The cause of such a large shift needs to be understood, mechanically. | ||
+ | * We discussed whether or not target/start-counter position should be reflected in the base geometry or represented as a correction in the new geometry specification scheme, i. e., what is the philosophy for deciding which shifts are considered part of the base geometry and which are called a correction. | ||
+ | * Thomas pointed out that if we settle on a philosophy for the parametrization, that philosophy should be applied for all detector groups. It would be messy if different sub-systems viewed the base geometry in different ways. | ||
+ | * Lately only Richard and Simon have been modifying the main GlueX geometry files. |
Latest revision as of 13:19, 23 March 2017
GlueX Start Counter Meeting
Thursday, March 23, 2017
11:00 am EDT
CEBAF Center, Room F326/327
Contents
Agenda
- Announcements
- Review minutes from the last meeting
- Run Recap
- Calibration
- Time-dependent geometry adjustments
- Mcsmear procedure and parameters for the start counter
- NIM/TDR
- Action Item Review
Communication
BlueJeans
- The BlueJeans Meeting ID is 556 286 544 .
- Connect to the Meeting
Slides
Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2017
on the JLab CUE. This directory is accessible from the web at https://halldweb.jlab.org/talks/2017/ .
Minutes
Present:
- FIU: Mahmoud Kamel
- JLab: Thomas Britton, Mark Ito (chair), Simon Taylor
There is a recording of this meeting on the BlueJeans site.
Calibration Update
Mahmoud showed the latest results from his time-walk calibration.
- He showed plots of pulse-height (in ADC counts) vs. z-position (as measured by charged tracks) at the point of intersection with the start counter. Clear minimum ionizing peaks are visible with amplitude increasing with increasing z.
- He then showed the difference in TDC time and ADC time as a function of pulse-height (in ADC counts) and the time-walk correction he derives from these plots. He then showed the same TDC-ADC time vs. pulse-height plot after the correction is applied. The pulse-height dependence is largely removed, as expected. In particular, there does not appear to be a large failure of the correction at large pulse-height.
Propagation Time Correction Constants
Although there was no smoking gun in the time-walk calibration, Mark thought that, at least for now, we should go with the single-linear fit in the nose region to for the propagation time correction until that non-linearity is understood. The current constants being used in the monitoring run are consistent with that.
Time-dependent geometry adjustments
We discussed a few issues:
- Although the start counter is mounted on the target cart its position is physically tied to that of the target. In the HDDS representation, the two positions are specified independently.
- Simon reported that that the target position has varied from run-to-run by as much as a centimeter. The cause of such a large shift needs to be understood, mechanically.
- We discussed whether or not target/start-counter position should be reflected in the base geometry or represented as a correction in the new geometry specification scheme, i. e., what is the philosophy for deciding which shifts are considered part of the base geometry and which are called a correction.
- Thomas pointed out that if we settle on a philosophy for the parametrization, that philosophy should be applied for all detector groups. It would be messy if different sub-systems viewed the base geometry in different ways.
- Lately only Richard and Simon have been modifying the main GlueX geometry files.