[Halld-pid] Time-of-Flight Meeting Minutes, August 2, 2016

[Mark Ito]

Find the minutes below and at https://goo.gl/V1JeDY .

________________________


  GlueX TOF Meeting, August 2, 2016, Minutes

Present:

  * *FSU*: Sasha Ostrovidov
  * *JLab*: Mark Ito (chair), Simon Taylor, Beni Zihlmann


      PMT order

  * Mark received a quote from Hamamatsu
    <https://www.jlab.org/Hall-D/gluex_secure/procurements/TOF_PMT/H10534%20MOD.pdf>
    for more extra spare PMTs].
  * Beni remarked that 24 PMTs was chosen to cover the possibility of
    replacing the innermost counters that have the highest rate.
  * At Eugene's suggestion, we will add 6 more tubes to the order
    bringing the total to 30, just in case they are needed.


      Cosmic data

Beni has taken more cosmic data, this time at 1200 V on the tubes. He is 
now requiring an ADC and a TDC hit on both ends of the counter, with all 
4 hits in time with each other.
<https://halldweb.jlab.org/wiki/index.php/File:Run11721_1200V_paddle12_plane2.gif> 

1200 V, paddle 12 of horizontal plane
<https://halldweb.jlab.org/wiki/index.php/File:Run11721_1200V_paddle21_plane2.gif> 

1200 V, paddle 21 of horizontal plane

  * The new requirements clean up a lot of the noise seen at low
    amplitude in the plots from the last meeting, though a noise band is
    still visible.
  * The effect on time resolution is still open. Trying to time one
    layer against the other (crossed) layer is not giving good results.
    Beni will try the same technique with higher voltages to see if that
    makes any difference.
  * Sasha pointed out that we have to look at efficiency as well, though
    that may may be hard to asses with cosmic data.


      PMT currents during the Spring 2016 run

Beni made some estimates based on data we took in the Spring. Note that 
the recommended maximum current is 100 μA and we want to be well below 
that.

  * paddle 14, up, MIP at 900 counts => 450 mV peak, assuming triangle
    pulse => 1.4×10^-10 C/pulse. At 22 kHz => 3 μA.
  * paddle 2, 600 kHz, => 85 μA, yikes!


      Next Meeting

We will meet next week in our normal time slot. We will discuss the run 
plan for re-commissioning the TOF.

Retrieved from 
"https://halldweb.jlab.org/wiki/index.php?title=GlueX_TOF_Meeting,_August_2,_2016&oldid=76633"

  * This page was last modified on 3 August 2016, at 09:46.

-- 
marki at jlab.org, (757)269-5295

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