[Halld-pid] Time-of-Flight Meeting Minutes, June 3, 2020

[Mark Ito]

Folks,

Please find the minutes here 
<https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_June_3,_2020#Minutes> 
and below.

   -- Mark


    GlueX TOF Meeting, June 3, 2020, Minutes

Present: Paul Eugenio, Mark Ito (chair), Susan Schadmand, Simon Taylor, 
Beni Zihlmann

There is a recording of this meeting <https://bluejeans.com/s/KXYRM/> on 
the BlueJeans site. Use your JLab credentials to gain access.


      Announcements

The lab has a plan in place for starting to re-open and it has been 
submitted to DOE. No announcement of a date when things will start 
happening.


      Review of minutes from the last meeting

We went over the minutes from May 6 
<https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_May_6,_2020#Minutes>. 


  * Beni would like to re-do his position study using the reverse Kalman
    filter. Simon has given him examples of how to use it.
  * Paul reports that the shop at FSU is back working on fabrication of
    the six units of PMT-replacement-glue-joint holders. He was
    wondering if we had candidates for swapping out. He reminded us that
    we have a cache of new tubes at FSU. Beni has a candidate that shows
    strange pulse shape and low amplitude. Increasing the HV on this
    channel did not help much. He is afraid that this may be the PMT
    that seemed to have a loose mechanical connection to the light
    guide. Beni would like to take raw mode data during the upcoming run
    to evaluate other candidates for replacement via their pulse shape
    characteristics.


      TOF energy calibration

Beni led us through his recent work on the energy calibration. He is 
reviewing the current procedure, both for calibration and the 
reconstruction algorithm that uses the calibration, and making 
improvements. Please see his slides 
<https://halldweb.jlab.org/talks/2020/tofecal.pdf> for the details.

In summary, he is able to find peak values of the Landau distribution 
for minimum ionizing particles in bins of position along the counter for 
each channel. Position is determined by end-to-end timing using the ADCs 
themselves. He can then extrapolate the pulse area to that which comes 
from the middle of the counter (or the end of the counter for 
single-ended counters) and find the conversion constant to energy, where 
energy is determined from Monte Carlo.

He proposes that the TOF reconstruction should report the energy found 
in each layer of a TOF point, rather than the average of the two layers 
in the case of two double-ended counters. It turns out the currently, if 
the contribution of one of the layers is from a single-ended counter, 
that layer is ignored in the reported energy.

This is work in progress.


      TOF NIM paper

  * Sasha Ostrovidov has recently added to the section on testing.
  * Paul has some changes that he needs to add to Overleaf.
  * Beni would like to review the section he wrote on calibration. He
    suspects that procedures have improved since the original draft was
    written.

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