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</style><article id="node-987487" 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/3914476" rel="bookmark">RC update</a>
</h1>
</header><div class="contextual-links-wrapper"><ul class="contextual-links"><li><a href="https://logbooks.jlab.org/entry/3914476/edit?destination=email/send">Edit</a></li><li><a href="https://logbooks.jlab.org/entry/3914476/delete?destination=email/send">Delete</a></li></ul></div>
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Lognumber <a href="https://logbooks.jlab.org/entry/3914476" class="lognumber" data-lognumber="3914476">3914476</a>. Submitted by <a href="https://logbooks.jlab.org/user/jonesdc">jonesdc</a> on <time datetime="2021-09-29T10:42:21-0400" pubdate="pubdate"><a href="https://logbooks.jlab.org/entries?start_date=1632922941&end_date=1632930141&book=HALOG">Wed, 09/29/2021 - 10:42</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>jonesdc</td></tr></table></div>
<div class="logentry node-content">
<p>A quick update from your RC for those who haven't been able to attend meetings.<br />
First, a quick shout out to everyone who is working long hours to have this experiment ready, especially to those who may not be a part of the collaboration but who are working so hard to make our experiment a success: Jessie, Jack and the technical staff working long hours and over weekends to support us; DAQ experts and the detector support team working what appears to be around the clock to get the bugs out of the system; Dave Meekins and the target crew quickly developing a solution for the vacuum issues that could have taken us down for weeks; Robyn designing and making sure the experimental layouts actually will work as they change daily...and many more. Thank you so much.<br />
To collaborators who I will not name because I fear I will overlook critical efforts, Thank you. So much effort is being put forward in these last days and weeks, it is exhausting for many of you I am sure. Monday, Oct 4. is still the big day we are aiming for locking up and bringing first beam into the Hall.</p>
<p>The biggest issue facing us currently is the vacuum leaks in the region downstream of the target. The large diameter (2' and 4') pipes with their many welds and perforations cannot hold vacuum at better than 2e-4 Torr. The target chamber should be in the few 10^-6 Torr region. Rather than spend weeks chasing down leaks in the downstream pipe, a solution is being introduced to allow differential pumping in the region between the downstream and the target. This will consist of a section of ~14" long of 4"OD beam pipe just downstream of the target with a thin aluminum disc closing off either end. The discs will have a small 0.75" diameter hole on their centers for the beam to pass through. A vacuum turbo pump will pump continuously on this 14" spool region. Per Dave Meekins, the reduced conductance that these apertures provide along with the extra pump will allow us to get to the required vacuum in the target. Dave has further decided to glue a thin Kapton layer over the openings and allow the beam to melt its way through the Kapton to further reduce the conductance and thus the load on the target and differential pumps. All parts are in hand and preparation for installation is ongoing.</p>
<p>Although work continues on most subsystems, they are essentially ready for beam. One of the upper INFN GEM modules in the Bigbite arm will not hold voltage and right now it appears we will have to work without it. Another single GEM module is equipped with a mylar foil gas window which will likely eventually collapse under the radiation doses of this experiment. When crane access is possible, plans are being worked out to replace these, but timing remains uncertain. We can still run with this module not working since it represents a partial loss of one out of 5 planes. There will be a loss in efficiency, but how large that is remains to be determined once beam arrives. </p>
<p>Work is continuing almost non-stop on getting all aspects of the DAQ integrated and working without errors and communication issues. However, full readout of all detector systems is now possible and several trigger types have been implemented. Testing with cosmics is ongoing in all systems. </p>
<p>HCal and BBCal (shower and preshower) have now been gain-matched with cosmics and are ready for beam. </p>
<p>The software team reports that they are ready for real time analysis of data. There is an online GUI under development for the shift crew to see key features of the data in real time as well as the full offline analyzer. Top rates are expected to approach 2 Gb/s during the GEn-RP experiment. Ole assures us the network connection for transferring and storing these data to tape can handle these rates. Most of the analysis is expected to take place on the ifarm since the analysis is limited to order 100 events per second per core even with Zero suppression working.</p>
<p>For those who can attend, we will have an RC meeting with brief status updates today at 3:15 PM. The connection information is given below.</p>
<p> BlueJeans calling instructions:<br />
Toll-Free Number (U.S.& Canada): 888-240-2560<br />
International toll number: 408-740-7256<br />
Bluejeans CODE: 256 205 934<br />
Bluejeans link: <a href="https://bluejeans.com/256205934">https://bluejeans.com/256205934</a></p>
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