[Halld-pid] Time-of-Flight Meeting Minutes, November 18, 2014

[Mark M. Ito]

Gluons,

Please find the minutes below and at

https://halldweb1.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_November_18,_2014#Minutes

   -- Mark
________________________________________________


GlueX TOF Meeting, November 18, 2014
Minutes

Present:

  * *FSU*: Hussein Al Ghoul, Paul Eugenio, Sasha Ostrovidov, Aristeidis
    Tsaris
  * *JLab*: Mark Ito (chair)


Commissioning Plan Review

Paul was prepared to present the commissioning run plan 
<https://hdops.jlab.org/wiki/index.php/Time-of-Flight_System_Commissioning> 
for the TOF at this morning's Run Coordination Meeting, but the agenda 
did not include this discussion. We went over the components of our 
request:

 1. For calibration we need straight tracks (no field) going through the
    TOF.
 2. We need a TOF-based trigger to illuminate the corners of the TOF
    array that are beyond the FCAL.
 3. We need running in two target positions:
     1. Nominal position to allow tracking with the FDC.
     2. Forward position to allow tracks to hit the corners of the TOF.
        In the nominal position parts of the TOF are shadowed by the
        solenoid iron.
 4. High-rate running to assess TOF performance under those conditions.
    For this we want as thick a target and as high a beam rate as possible.


FADC Voltage Range

We have been running with a full range of 1 Volt so far. All tests at 
FSU were done with the 2-V range. Sasha has reported 30% of the pulses 
with overflows in the last cosmic runs he took some weeks ago. Fernando 
Barbosa has questioned whether we need to make this change. It is 
possible that the cosmic data has much larger average pulse height than 
beam data due to the high number of vertical cosmics. Sasha will look at 
the beam data from last night to check whether we want to proceed with 
changing the FADC range.

TDC Timing

The upgrade to the firmware that we discussed at the last TOF meeting 
has still not been installed. Sascha Somov had told Paul that it would 
be in by now. In addition we have still not seen the trigger signal in 
the TDC data. We need to continue to pursue this issue.
Sasha O. is concerned that there might be timing jitter from 
board-to-board in the system due to the trigger pulse being presented to 
different boards at different times. Mark stated that this should not 
happen; if it occurs in the data then we need to address it, but we 
should push ahead on the assumption that there are no random time shifts 
between any two channels in the CAEN TDC crate.

Calibration

We have transitioned to pursuing beam-based calibration only.
The last run examined, run 995, had no TDC data for the TOF. The 
read-out window was not adjusted when going from the stand-alone TOF 
trigger to the global FCAL trigger. Last Thursday Paul adjusted the 
window. Sasha O. will look at the data taken yesterday and see if the 
TDC data is present.
There is still confusion about the pulse-integral data. The behavior of 
the data seems different than that of the raw mode data. The effect of 
NSB/NSA on the integral data is not clear. Mark will try to find the 
document describing the algorithm used by the firmware. It would be 
helpful to have data with the full raw pulse and the pulse-integral 
summary in the same event so an offline check can be made.

Equipment Loan

Paul is looking through the items and will return those that are not 
needed for reading out the mini-TOF.

Action Items

 1. Look at overflow fraction in beam-based FADC data.
 2. Request the TS change to synch the CAEN TDC system clock to the
    global system clock.
 3. Look for TDC hits in the read-out window of beam data.
 4. Get the document on the FADC pulse-integral algorithm.
 5. Ask for raw and summary FADC data in the same event.
 6. Assess need for loaned equipment.

Retrieved from 
"https://halldweb1.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_November_18,_2014"

-- 
Mark M. Ito, Jefferson Lab, marki at jlab.org, (757)269-5295

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.jlab.org/pipermail/halld-pid/attachments/20141118/b224b2c6/attachment-0002.html>