[Sbs] [New Logentry] Hall A RC Update [10/5/21]

[flay at jlab.org]

Logentry Text:
--
We're on the eve of taking beam, and everyone's putting in long hours to get us taking good data, we're almost there; great work by everyone so far. 

Updates through about 3 pm are here: https://sbs.jlab.org/cgi-bin/DocDB/private/ShowDocument?docid=120

Additional notes:

Activities in the Hall Tonight
- The hall is in Restricted Access
- Jessie and his team are cleaning up the hall in preparation for beam tomorrow
- SBS and BB magnets will be tested to half-max current tonight, and full current
  tomorrow during the day; likely they will be ready for beam end of day Thursday.
- Given the magnet testing and the Hall A checkout list Jessie will do during
  day shift tomorrow, we have cancelled Wednesday Day shifts.  Shifts for Swing
  are still ON.

Preparing for Beam
- We (Don and DF) are modifying the plan presented yesterday at the commissioning
  meeting to bring beam into the hall with BB and SBS magnets *off*.  Conversations
  with Jay and others in Accelerator agree this will be a useful approach to steer
  us through the DP apertures and to the dump.
- Andrew and Eric ran the g4sbs simulation to estimate the trigger rates we'll
  see when we get beam on target; the present estimate is about 10 kHz/uA on LD2,
  1 kHz/uA on Carbon; these numbers need refining given some settings in g4sbs,
  but this is a great starting point of what to look for on our scalers.
- Full-DAQ configurations are making good progress.  Work is ongoing to fold
  in the sbsvme29 crate which houses beam scaler copies and BB triggers.  

Target
- Cooldown is progressing; plans to condense H2/D2 tomorrow.  Possibly need a controlled
  access for the condensation work.
- Need to obtain operational restrictions on the target; Dave Meekins and DF are
  on contact on this.

Beam Line
- Had MCC turn on the raster magnets to a nominal 2x2 and did a spot++ run; Y channel on upstream raster looked ok, others not making sense.  Had MCC turn off raster and we're checking our software. 

Radiation Monitoring
- NDX detectors nearly ready; last connections being made this evening    

HCAL
- Determined long tails on ADC signals are due to bad modules, not bad PMTs
  Maybe a broken light guide or something?
  - Can run like this, but have to be aware of it
- Some other cleanup tasks and tests

GEMs/Tracking
- Ran last night; clarify that the gas we have going into GEMs is what we actually think is going in
  - Monitoring now the pressures from the cylinders
  - ~80--90% efficiencies down to ~30% last night.  GEMs have moved around a bit, so perhaps this is better
    now with better alignment.
- Working on documentation for the SBS Wiki

BB Calorimeter
- PS, SH is calibrated
- Drafted instructions on what to do when beam turns on
  - What should be on
  - What to do in first few minutes
  - First draft circulating to BB folks
- Flow of gas (air) to hodoscopes and PS modules.  Measuring He content in the hall?  Can't do before Wednesday;
  Jack/Jessie: if the He load changes in the hall, need to set up system to get gas flow to the PS PMTs.
  If we're flowing nitrogen, need ODH approval. Air flow purpose is to reduce He concentration.  Lifetime
  of PMT is defined by He.  If He concentration 1 ppm, this isn't a problem, but 1% is a big deal.
  Schedule a measurement in the hall. **Has to be done for HCAL as well**.  Jack should have equipment to do this measurement
  Jessie: Equipment used to measure this is pretty sensitive; needs calibration first + good stats => days-long measurement
- Aside from gas studies, ready for data

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This is a plain text email for clients that cannot display HTML.  The full logentry can be found online at https://logbooks.jlab.org/entry/3918672
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