[Halld-cpp] CPP Meeting Minutes, January 19, 2022

[Mark Ito]

Folks,

Please find the minutes here 
<https://halldweb.jlab.org/wiki/index.php/%CE%A0_polarizability_Meeting_Jan_19,_2022#Minutes> 
and below.

   -- Mark

      _____________________________________


  Π polarizability Meeting Jan 19, 2022, Minutes

Present: Alex Austregesilo, Albert Fabrizi, David Hornidge, Mark Ito 
(chair), Nikhil Kalra, Ilya Larin, David Lawrence, Rory Miskimen, Andrew 
Schick, Simon Taylor, Beni Zihlmann

There is a (partial) recording of this meeting 
<https://jlab-org.zoomgov.com/rec/share/8w89wZ1fWpv57x76H1Teu6glPerQCa5Ew1AVbII4g8sy9qnUrscdjF0AbuykwTW2.UbFFAtUx2xgOEW9u> 
on the ZoomGov website. The passcode is !&C^z71c


      Action Items

We reviewed the action items.


        Generate MC samples of pi+pi-

David L. reported that he and Andrew have put together a directory on 
the work disk,

/work/halld/CPP/MC/generated

containing three directories at present:

BHgen_electron_positron
BHgen_muons
gen_2pi_primakoff

There are samples of generated events in each of these directories that 
can be used for studies and for benchmarks of future CPP reconstruction 
and analysis code.


      Make a pull request for hdds

Simon reported that Elton merged the pull request last week. In addition 
he got new numbers for the MWPCs from Stephanie Worthington and has put 
the updated geometry into the CCDB.


      Review CPP test run for rates and check with Sasha on steps for
      "replay"

Ilya showed slides on his first look at the trigger test data taken at 
the end of the SRC run. He is having trouble analyzing the data. Beni 
and David will have a look to see if they can retrieve the trigger bits 
from the events. See his slides 
<https://userweb.jlab.org/~ilarin/cpp/1221m10/rcdb.m10.pdf> for more 
details.

Beni also mentioned that when he balanced the gains for the TOF 
recently, the average gain was a bit higher than before. This 
effectively lower energy threshold may account for the increase in rate 
that Ilya saw.


      Check with Hovanes and Alexandre on using JD103 diamond

Rory reported on the recent email exchange that Elton Smith initiated. 
It looks like the only option we have at this point is to use the 
JD70-103 diamond. Tim sent around a photo showing it on the goniometer 
stage. The consensus is that the the coherent edge from this diamond may 
not be very sharp, but that it can provide adequate polarization to do 
the experiment. Richard Jones has suggested a calculation where data 
from a run at the light source is convolved with a typical electron beam 
profile to calculate the polarization we expect. Rory will follow up 
with Richard on what is involved in doing this calculation.


      Check that Rory's grounding suggestions do not deteriorate the
      performance of Arwen using cosmics

Beni reported on activities with the test set up in the EEL. On earlier 
in the week he got the gas turned on and the DAQ system running. We have 
been taking data since yesterday morning at about 20 Hz. He sees nice 
signals in the monitoring plots. Next Wednesday we may need to change 
the gas bottle. One mystery: he is not seeing action on the output bubbler.


      Microscope move (in progress)

No one has heard any news from the UConn crew. The consensus was that 
this should be interpreted as good news.


      PID + AI

David ran the 10 k $pi;$pi; events through his machinery to produce 
input for Nikhil to chew on. This happened just yesterday.


      CPP and NPP Readiness Review

Final certification of readiness has been granted by Physics management.


      CPP and NPP Experiment Configuration
      <https://halldweb.jlab.org/wiki/index.php/CPP_and_NPP_Experiment_Configuration>

We skimmed the CPP and NPP Experiment Configuration document 
<https://halldweb.jlab.org/wiki/index.php?title=CPP_and_NPP_Experiment_Configuration_document&action=edit&redlink=1>. 


Beni reported that the cutting of the cable trays on the forward 
platform was underway when he was in the Hall yesterday.


      Electronic Configuration

Beni gave us an update on electronics for the chambers and the new 
scintillators.

  * There are plenty of FADC channels for the eight PMTs
  * There are also lots of discriminator channels available.
  * TDCs are an issue
      o They need an additional connection to the trigger module[?].
  * The bottom CAEN HV mainframe has four slots for the DIRC. The plan
    is to use two of these for chamber HV (requires board replacement)
    and the other two for the scintillators.
      o Nick Sandoval has test stands appropriate for both high and low
        voltage.


Rory brought up the idea of a scintillator-only trigger that could be 
used for diagnostics for the chambers. Such a trigger might yield a nice 
sample of muon pairs. Beni noted that there was already a NIM crate on 
the forward carriage that could be used to form a front-panel trigger. 
Though not simple, we thought that it was within the realm of 
possibility and the idea should be explored further.


      Software consolidation

Simon submitted a pull request to merge the CPP branch of halld_recon 
onto the master. Sean Dobbs had several suggestions and Simon is 
responding to them. For details, see the conversation on GitHub 
<https://github.com/JeffersonLab/halld_recon/pull/616>.


      Next meeting

We decided that we should have one. ;-)

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