Difference between revisions of "Preparation for 2021 Run"

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;Perform preventative replacement of FCAL PMT bases in 4 inner rings, which is critical for reconstruction of Compton events <span style="color:brown"> -- Support needed from Chris S., Nick S. Fernando B, Mark D., Matt S. </span>
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;Preventative maintenance of FCAL PMT bases  <span style="color:brown"> -- Coordinated by Mark D, with support from Chris S., Nick S., Fernando B., Matt S., Ben R.,Paul  </span>
: Several bases have already been replaced in this area. The status of FCAL bases in the 3 inner FCAL rings was provided by Colin and is presented in the link below
+
# '''Change out bases which draw excessive current (> 13 mA) when they are on or which show other signs of problems.'''    High current bases are associated with [https://logbooks.jlab.org/entry/3848122 increased temperature, increased deviation from setpoint] and future high voltage failure.  There are about 200 high current bases.  They are repaired using the standard procedure for cleaning and replacing resistors on the base.
:[https://logbooks.jlab.org/entry/3810770 Status of FCAL dividers in 3 inner rings]
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#* Status:
 +
#** [https://logbooks.jlab.org/entry/3853228 The first 100 bases to remove have been identified]
 +
#** 21 bases have been removed from FCAL and waiting for radiological survey.
 +
# '''Diagnose bases which draw excessive current (> 13 mA) when they are on and off.'''  This curious symptom is not understood. [https://logbooks.jlab.org/entry/3846223]
 +
#* Status:
 +
#** [https://logbooks.jlab.org/entry/3853381 8 bases have been remove from the FCAL] and sent to Paul at IU for diagnosis.  <span style="color:brown">  Paul </span>
 +
# '''Improve robustness of firmware for handling communication failures.'''  When the beam is on we regularly have about 2-3 bases that lose communication per day.  The HV drops to zero and the only known way to recover is to power cycle all the bases at the end of the run.  This means that we permanently have some holes in the FCAL from perfectly working bases.  We will try to modify the firmware to fix this issues. <span style="color:brown">  Ben R., Mark D. </span>
 +
## compile the existing code and load onto a test unit to make sure we can reproduce what you currently have
 +
## have it communicate over the CAN interface like normal
 +
## try to crash the micro-controller with a radiation source
 +
## make a small firmware change to enable the watchdog timer and try to crash the micro-controller again with source (we should plan to track/observe if a watchdog reset occurs which should match the rate of lockups from step 3 if conditions are the same, but in this case it should self recover)
 +
## look into  remote/boot loader firmware update code & power to try and optimize.
 +
# '''Evaluation of bases in inner rings for Compton events'''
 +
#* 25 bases have already been replaced in this area.  [https://logbooks.jlab.org/entry/3810770 Status of FCAL bases in 3 inner rings] <span style="color:brown">  Colin </span>
 +
#* A possible 47 more could be replaced, we should evaluate which of these are showing any issues. <span style="color:brown">  Mark D. </span>
  
 
;Perform preventative maintenance of FCAL PMT bases, which draw excessive current  <span style="color:brown">  -- Support needed from Chris S., Nick S., Fernando B., Mark D., Matt S. </span>
 
:Diagnose and subsequently replace (reapair) bases which draw excessive current (typically larger than 15 mA), which is an indication of the possible failure of the base. Currently 200 - 300 FCAL bases exhibit such a big current.
 
  
  

Revision as of 21:04, 1 October 2020

Below is a list of action items which we would like accomplish before the PrimEx Phase II run in Spring/Summer of 2021


Aligning FCAL in the Hall -- Coordinated by Tim Whitlatch
Moving FCAL platform by about 5 mm in X-direction to make sure that the beam goes through the middle of the FCAL hole (3x3 modules). The exact position of the platform should be confirmed by the alignment group


Preventative maintenance of FCAL PMT bases -- Coordinated by Mark D, with support from Chris S., Nick S., Fernando B., Matt S., Ben R.,Paul
  1. Change out bases which draw excessive current (> 13 mA) when they are on or which show other signs of problems. High current bases are associated with increased temperature, increased deviation from setpoint and future high voltage failure. There are about 200 high current bases. They are repaired using the standard procedure for cleaning and replacing resistors on the base.
  2. Diagnose bases which draw excessive current (> 13 mA) when they are on and off. This curious symptom is not understood. [1]
  3. Improve robustness of firmware for handling communication failures. When the beam is on we regularly have about 2-3 bases that lose communication per day. The HV drops to zero and the only known way to recover is to power cycle all the bases at the end of the run. This means that we permanently have some holes in the FCAL from perfectly working bases. We will try to modify the firmware to fix this issues. Ben R., Mark D.
    1. compile the existing code and load onto a test unit to make sure we can reproduce what you currently have
    2. have it communicate over the CAN interface like normal
    3. try to crash the micro-controller with a radiation source
    4. make a small firmware change to enable the watchdog timer and try to crash the micro-controller again with source (we should plan to track/observe if a watchdog reset occurs which should match the rate of lockups from step 3 if conditions are the same, but in this case it should self recover)
    5. look into remote/boot loader firmware update code & power to try and optimize.
  4. Evaluation of bases in inner rings for Compton events
    • 25 bases have already been replaced in this area. Status of FCAL bases in 3 inner rings Colin
    • A possible 47 more could be replaced, we should evaluate which of these are showing any issues. Mark D.


Refurbish CCAL active bases
- manufacture 150 new active bases according to recent modifications by V. Popov and install them on the CCAL -- Chris S., Nick S., and Fernando B.
- Chris has already prepared a new PCB design for the active base
- ( replace bases: A.Somov, J.Crafts, V. Berdnikov )


Increase LED light pulse on the CCAL LMS system
- replace (use multiple LEDs) on the LMS system (A.Somov, J.Crafts, V. Berdnikov)
- Driver(s) for multiple LEDs Chris S., Nick S., and Fernando B.