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<p><font face="Helvetica, Arial, sans-serif">FYI, the T2 target in
Hall A is cold since about noon yesterday. It's drawing about 7
g/s at 13.5 K.</font></p>
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<p><font face="Helvetica, Arial, sans-serif">Chris</font><br>
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<div class="moz-cite-prefix">On 12/6/17 8:13 AM, Dave Kashy wrote:<br>
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<blockquote type="cite"
cite="mid:11108606.2644135.1512566025175.JavaMail.zimbra@jlab.org">
<pre wrap="">Hi All,
Now that we are starting 4 Hall Physics, we need to be very careful with our use of the cryogens.
The current status of the ESR is that it is FULLY loaded, ie, running full out (both turbines and compressors). In fact, can not independently support the loads of the magnets and targets as they are now, and Hall A still has to cool its target and most if not all of the Magnets are not powered. When we ramp the magnets this will add more load (lead flow and lead heating conducting heat directly into the liquid reservoirs) and of course so will cooling the Hall A target. The CHL has excess capacity to support the ESR and we will be able to run our physics program, BUT, if the load changes rapidly it could trip the ESR and recovery time will reduce the time for physics.
Please take the following actions before making changes to any portion of the cyrogenic system that could or will effect the ESR or CHL.
1) Consider the effect of your change not only on your device and be sure your plan has minimum impact on everyone. If possible discuss your change with a second person before deciding to proceed. (David Schleeper would be the ideal person, if he is not available you can contact me or someone else in your Hall)
2) Write an e-mail to <a class="moz-txt-link-abbreviated" href="mailto:esr-users@jlab.org">esr-users@jlab.org</a> alerting others of your plans (such as ramping a magnet or any of the items below)
3) Contact Cryo if the change will add or subtract significant load (such as cooling a high power target or putting a magnet on warm return or taking a magnet off line, AND do not proceed with out their approval.
4) Of course we need to be very careful with regard to contamination, so do not break into a system with out communicating your intentions
5) And finally helium loss is a major laboratory expense so while now is not the right time to start a major leak hunt, if there are known leaks they must be repaired and if they are too big it may need to be ASAP. If cyro observes a big increase in helium loss rate it could require an access to search for leaks and that too will reduce time for physics.
We will all need to be on our best "cryo-ops" behavior to make this run a success.
Thanks and Good Luck.
Dave
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<pre class="moz-signature" cols="72">--
______________________________________________________
Christopher D. Keith, PhD
Jefferson Lab, Suite 6 email: <a class="moz-txt-link-abbreviated" href="mailto:ckeith@jlab.org">ckeith@jlab.org</a>
12000 Jefferson Ave. ph: 757-269-5878
Newport News VA 23606 fax: 757-269-5235
______________________________________________________</pre>
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