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</style><article id="node-991683" class="node node-logentry contextual-links-region article ia-n clearfix" role="article"><header class="node-header"><h1 class="node-title">
<a href="https://logbooks.jlab.org/entry/3918672" rel="bookmark">Hall A RC Update [10/5/21]</a>
</h1>
</header><div class="contextual-links-wrapper"><ul class="contextual-links"><li><a href="https://logbooks.jlab.org/entry/3918672/edit?destination=email/send">Edit</a></li><li><a href="https://logbooks.jlab.org/entry/3918672/delete?destination=email/send">Delete</a></li></ul></div>
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<p class="author-datetime">
Lognumber <a href="https://logbooks.jlab.org/entry/3918672" class="lognumber" data-lognumber="3918672">3918672</a>. Submitted by <a href="https://logbooks.jlab.org/user/flay">flay</a> on <time datetime="2021-10-05T20:41:06-0400" pubdate="pubdate"><a href="https://logbooks.jlab.org/entries?start_date=1633477266&end_date=1633484466&book=HALOG">Tue, 10/05/2021 - 20:41</a></time>. </p>
<table class="field-vitals"><tr><th>Logbooks: </th><td><a href="https://logbooks.jlab.org/book/halog">HALOG</a></td></tr><tr><th>Entry Makers: </th><td>flay</td></tr></table></div>
<div class="logentry node-content">
<p>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. </p>
<p>Updates through about 3 pm are here: <a href="https://sbs.jlab.org/cgi-bin/DocDB/private/ShowDocument?docid=120">https://sbs.jlab.org/cgi-bin/DocDB/private/ShowDocument?docid=120</a></p>
<p>Additional notes:</p>
<p>Activities in the Hall Tonight<br />
- The hall is in Restricted Access<br />
- Jessie and his team are cleaning up the hall in preparation for beam tomorrow<br />
- SBS and BB magnets will be tested to half-max current tonight, and full current<br />
tomorrow during the day; likely they will be ready for beam end of day Thursday.<br />
- Given the magnet testing and the Hall A checkout list Jessie will do during<br />
day shift tomorrow, we have cancelled Wednesday Day shifts. Shifts for Swing<br />
are still ON.</p>
<p>Preparing for Beam<br />
- We (Don and DF) are modifying the plan presented yesterday at the commissioning<br />
meeting to bring beam into the hall with BB and SBS magnets *off*. Conversations<br />
with Jay and others in Accelerator agree this will be a useful approach to steer<br />
us through the DP apertures and to the dump.<br />
- Andrew and Eric ran the g4sbs simulation to estimate the trigger rates we'll<br />
see when we get beam on target; the present estimate is about 10 kHz/uA on LD2,<br />
1 kHz/uA on Carbon; these numbers need refining given some settings in g4sbs,<br />
but this is a great starting point of what to look for on our scalers.<br />
- Full-DAQ configurations are making good progress. Work is ongoing to fold<br />
in the sbsvme29 crate which houses beam scaler copies and BB triggers. </p>
<p>Target<br />
- Cooldown is progressing; plans to condense H2/D2 tomorrow. Possibly need a controlled<br />
access for the condensation work.<br />
- Need to obtain operational restrictions on the target; Dave Meekins and DF are<br />
on contact on this.</p>
<p>Beam Line<br />
- 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. </p>
<p>Radiation Monitoring<br />
- NDX detectors nearly ready; last connections being made this evening </p>
<p>HCAL<br />
- Determined long tails on ADC signals are due to bad modules, not bad PMTs<br />
Maybe a broken light guide or something?<br />
- Can run like this, but have to be aware of it<br />
- Some other cleanup tasks and tests</p>
<p>GEMs/Tracking<br />
- Ran last night; clarify that the gas we have going into GEMs is what we actually think is going in<br />
- Monitoring now the pressures from the cylinders<br />
- ~80--90% efficiencies down to ~30% last night. GEMs have moved around a bit, so perhaps this is better<br />
now with better alignment.<br />
- Working on documentation for the SBS Wiki</p>
<p>BB Calorimeter<br />
- PS, SH is calibrated<br />
- Drafted instructions on what to do when beam turns on<br />
- What should be on<br />
- What to do in first few minutes<br />
- First draft circulating to BB folks<br />
- Flow of gas (air) to hodoscopes and PS modules. Measuring He content in the hall? Can't do before Wednesday;<br />
Jack/Jessie: if the He load changes in the hall, need to set up system to get gas flow to the PS PMTs.<br />
If we're flowing nitrogen, need ODH approval. Air flow purpose is to reduce He concentration. Lifetime<br />
of PMT is defined by He. If He concentration 1 ppm, this isn't a problem, but 1% is a big deal.<br />
Schedule a measurement in the hall. **Has to be done for HCAL as well**. Jack should have equipment to do this measurement<br />
Jessie: Equipment used to measure this is pretty sensitive; needs calibration first + good stats => days-long measurement<br />
- Aside from gas studies, ready for data</p>
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