Difference between revisions of "GlueX TOF Meeting, May 31, 2016"

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GlueX Time-of-Flight Meeting<br>
 
GlueX Time-of-Flight Meeting<br>
−
Tuesday, April 19, 2016<br>
+
Tuesday, May 31, 2016<br>
−
3:00 pm EDT<br>
+
11:00 am EDT<br>
−
JLab: CEBAF Center, Room A110
+
JLab: CEBAF Center, Room F326/327
  
 
==Agenda==
 
==Agenda==
  
 
# Announcements
 
# Announcements
−
# Review of [[GlueX TOF Meeting, March 8, 2016#Minutes|minutes from the previous meeting]]
+
# Review of [[GlueX TOF Meeting, April 19, 2016#Minutes|minutes from the previous meeting]]
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# Calibration Status FSU
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# Calibration Status  
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# Calibration Status JLab
+
 
# [https://halldweb.jlab.org/wiki/index.php/Mcsmear_updates#TOF mcsmear parameters]
 
# [https://halldweb.jlab.org/wiki/index.php/Mcsmear_updates#TOF mcsmear parameters]
−
# Run Status
+
# NIM paper: [https://halldsvn.jlab.org/repos/trunk/publications/GlueXTOF| svn co https://halldsvn.jlab.org/repos/trunk/publications/GlueXTOF]
−
#* [[Example of Monitoring Histogram Email|Monitoring Histograms]]
+
−
# NIM paper
+
  
 
==Communication==
 
==Communication==
Line 28: Line 25:
 
Present:
 
Present:
  
 +
* '''FSU''': Brad Cannon, Sasha Ostrovidov
 
* '''JLab''': Mark Ito (chair), Simon Taylor, Beni Zihlmann
 
* '''JLab''': Mark Ito (chair), Simon Taylor, Beni Zihlmann
−
* '''FSU''': Brad and Sasha absent due to shift taking duties.
 
  
−
=== Calibration Status, JLab ===
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=== Calibration ===
  
−
Beni has been working on the calibration system.
+
Beni gave us an update.
  
−
==== Timing Calibration ====
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He showed a plot of the difference in x as measured by tracks and as measured by the TOF (simply by noting which paddle was hit). The distribution is shown for each paddle in the plane.
  
−
* He has changed the philosophy from a completely stand-alone system, to one that can run as part of the Calibration Train. The new plug-ins have been checked into the Git repository.
+
[[File:tof_trkmatching.gif|700px]]
−
* He is currently correcting the configuration of his farm jobs to allow for enough disk space to accommodate the large ROOT files.
+
−
* The scheme has been modified to use a global speed-of-light in the scintillator bars, saving unnecessary calibration effort.
+
  
−
==== Energy Calibration ====
+
In the TOF measurement, it is assumed that the paddles are 6 cm wide with no gaps. The slope seen in the plot is due to the known gaps between counters (wrapping, non-planar edges). A similar plot is shown for the difference in y. From this method Beni measures a gap of about 0.9 mm between the paddles. Simon is adding these gaps to the geometry. In the reconstruction, this will improve the matching to charged tracks.
  
−
* This is work in progress.
+
The timing calibration is done for all spring 2016 data.
−
* He is now using the same two attenuation lengths for all counters (i. e., light loss is modeled as a sum of two exponentials).
+
−
* The code in the TOF library will have to change as a result.
+
  
−
=== mcsmear Parameters ===
+
The plane with horizontal paddles is upstream in the experiment but downstream in the current geometry. Simon is fixing that by swapping the plane identifier: plane 0 becomes plane 1 and vice-versa.
  
−
We reviewed [https://halldweb.jlab.org/wiki/index.php/Mcsmear_updates#TOF Sean's compilation of mcsmear parameters for the Time-of-Flight]. We noted that the list of parameters is identical to those for the start counter. Mark and Simon had discussed the parameters some weeks ago in the context of the start counter, and were confident that those ideas could be easily applied to the TOF. Details of the discussion were not easily recalled by either one, but Mark assured us that he has notes.
+
Sasha and Beni have both noticed a trend where the matching has a lower efficiency near the beam line than in the periphery. The track matching efficiency is  less than 95% in the central region.
  
−
=== Monitoring Histograms ===
+
Beni sees a issue with the difference between ADC and TDC timing in the central region.
  
−
We reviewed an [[Example of Monitoring Histogram Email|example email]] from the [[Simple Email Lists|"simple" email list]] that David, Justin, and Paul have put together. The mail sends out links to a minimal set of monitoring histograms, accumulated online, for runs taken during the previous twenty four hours.
+
[[File:t_offset_c17.gif|300px]] [[File:t_offset_c22.gif|300px]]
  
−
We agreed that we need to designate a member of this working group to be responsible for reviewing the Time-of-Flight histograms daily during running.
+
Each entry in the histograms is from calibration of a single run. The ADC-TDC time difference is a by-product of the time-walk correction. Shown is the mean difference in a run for two channels, 17 and 22. For 22, which is near the beam, there is a strange instability in the value. It is not known if this is related to the the matching inefficiency mentioned above.
 +
Sasha speculated that the effect may be due to small pulses around the beam line whose times are not well measured by the ADCs. Beni remarked that it is possible to check the quality of the ADC time before using it. A pedestal value of 0 indicates a problem finding a good time.
  
−
=== NIM paper, Technical Design Report ===
+
Beni has been talking to Sean about using the TOF calibration to determine the ADC vs. TDC time offsets rather than getting the numbers from Mike Staib's global program. The plan is to make the replacement.
  
−
Mark has started a draft of an updated section for the TOF for the TDR.
+
The energy calibration using tracking and matched paddle hits is in progress.
 +
 
 +
Both of the geometry changes (plane order, gaps) will be put in for the reconstruction of Spring 16 data, which starts this Thursday.
 +
 
 +
=== NIM paper ===
 +
 
 +
Beni has started a draft. [https://halldsvn.jlab.org/repos/trunk/publications/GlueXTOF Find it in the Subversion repository]. He asked the FSU folks to look over the construction section and expand it as necessary.
 +
 
 +
The plan is to distill parts of this paper and replace the current section of the TDR on the Time-of-Flight.
 +
 
 +
=== Meeting Frequency ===
 +
 
 +
We decided to try monthly meetings. That makes the next one on Thursday, June 28.

Latest revision as of 13:51, 2 June 2016

GlueX Time-of-Flight Meeting
Tuesday, May 31, 2016
11:00 am EDT
JLab: CEBAF Center, Room F326/327

Agenda

  1. Announcements
  2. Review of minutes from the previous meeting
  3. Calibration Status
  4. mcsmear parameters
  5. NIM paper: svn co https://halldsvn.jlab.org/repos/trunk/publications/GlueXTOF

Communication

Slides

Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2016 on the JLab CUE. This directory is accessible from the web at https://halldweb.jlab.org/talks/2016/ .

Minutes

Present:

  • FSU: Brad Cannon, Sasha Ostrovidov
  • JLab: Mark Ito (chair), Simon Taylor, Beni Zihlmann

Calibration

Beni gave us an update.

He showed a plot of the difference in x as measured by tracks and as measured by the TOF (simply by noting which paddle was hit). The distribution is shown for each paddle in the plane.

Tof trkmatching.gif

In the TOF measurement, it is assumed that the paddles are 6 cm wide with no gaps. The slope seen in the plot is due to the known gaps between counters (wrapping, non-planar edges). A similar plot is shown for the difference in y. From this method Beni measures a gap of about 0.9 mm between the paddles. Simon is adding these gaps to the geometry. In the reconstruction, this will improve the matching to charged tracks.

The timing calibration is done for all spring 2016 data.

The plane with horizontal paddles is upstream in the experiment but downstream in the current geometry. Simon is fixing that by swapping the plane identifier: plane 0 becomes plane 1 and vice-versa.

Sasha and Beni have both noticed a trend where the matching has a lower efficiency near the beam line than in the periphery. The track matching efficiency is less than 95% in the central region.

Beni sees a issue with the difference between ADC and TDC timing in the central region.

T offset c17.gif T offset c22.gif

Each entry in the histograms is from calibration of a single run. The ADC-TDC time difference is a by-product of the time-walk correction. Shown is the mean difference in a run for two channels, 17 and 22. For 22, which is near the beam, there is a strange instability in the value. It is not known if this is related to the the matching inefficiency mentioned above. Sasha speculated that the effect may be due to small pulses around the beam line whose times are not well measured by the ADCs. Beni remarked that it is possible to check the quality of the ADC time before using it. A pedestal value of 0 indicates a problem finding a good time.

Beni has been talking to Sean about using the TOF calibration to determine the ADC vs. TDC time offsets rather than getting the numbers from Mike Staib's global program. The plan is to make the replacement.

The energy calibration using tracking and matched paddle hits is in progress.

Both of the geometry changes (plane order, gaps) will be put in for the reconstruction of Spring 16 data, which starts this Thursday.

NIM paper

Beni has started a draft. Find it in the Subversion repository. He asked the FSU folks to look over the construction section and expand it as necessary.

The plan is to distill parts of this paper and replace the current section of the TDR on the Time-of-Flight.

Meeting Frequency

We decided to try monthly meetings. That makes the next one on Thursday, June 28.

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