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Since Hall C is at max 70 that is 350 so that leaves 80uA/2pass = 40uA max for</div>
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Hall A. There will probably be more RF trips. So you may want to talk to Hall A</div>
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to see if there is dummy running ( 40uA) needed that could work at that time.</div>
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Cheers,</div>
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Mark</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Sbs_gems <sbs_gems-bounces@jlab.org> on behalf of David Flay <flay@jlab.org><br>
<b>Sent:</b> Monday, February 7, 2022 12:09 PM<br>
<b>To:</b> Liyanage, Nilanga K (nl8n) <nl8n@virginia.edu>; Arun Tadepalli <arunts@jlab.org><br>
<b>Cc:</b> sbs_gems@jlab.org <Sbs_gems@jlab.org><br>
<b>Subject:</b> Re: [Sbs_gems] [EXTERNAL] Upper limits in terms of beam current for the GEM study planned for tomorrow</font>
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Hi Nilanga, </div>
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I believe the total current allowed in the machine is 430 uA -- so this accounts for beam passes. In other words, certainly have to negotiate with Hall C depending on where they are in terms of beam-pass. </div>
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Best regards,</div>
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David </div>
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<span style="margin:0px">----------------------------------------------------------------</span></div>
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David Flay, Ph. D.</div>
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Hall A/C Staff Scientist</div>
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Thomas Jefferson National Accelerator Facility</div>
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Office: CEBAF Center, C119</div>
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<div id="x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> Sbs_gems <sbs_gems-bounces@jlab.org> on behalf of Liyanage, Nilanga K (nl8n) <nl8n@virginia.edu><br>
<b>Sent:</b> Monday, February 7, 2022 12:05 PM<br>
<b>To:</b> Arun Tadepalli <arunts@jlab.org><br>
<b>Cc:</b> sbs_gems@jlab.org <sbs_gems@jlab.org><br>
<b>Subject:</b> Re: [Sbs_gems] [EXTERNAL] Upper limits in terms of beam current for the GEM study planned for tomorrow</font>
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Hi Arun</div>
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Thanks for that information.</div>
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It is nice to see that we are allowed to go up to 70 uA with the cryo targets.</div>
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But the question is what will hall C be taking during that time ? </div>
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What is the maximum current the accelerator could deliver at this time ?</div>
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If we are going to hit this upper limit of the total current, then you will have to negotiate with Hall C to see if they agree to lower their current for an hour or two while we take out data.</div>
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Best</div>
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Nilanga</div>
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<div id="x_x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> Arun Tadepalli <arunts@jlab.org><br>
<b>Sent:</b> Monday, February 7, 2022 11:59 AM<br>
<b>To:</b> Liyanage, Nilanga K (nl8n) <nl8n@virginia.edu><br>
<b>Cc:</b> sbs_gems@jlab.org <sbs_gems@jlab.org><br>
<b>Subject:</b> Re: [Sbs_gems] [EXTERNAL] Upper limits in terms of beam current for the GEM study planned for tomorrow</font>
<div> </div>
</div>
<div class="" style="word-wrap:break-word; line-break:after-white-space">Hello GEM folks,
<div class=""><br class="">
</div>
<div class="">I sent a snapshot of max current per target as per the OR document. Any update on what current you would like to go to? I’d have to give a heads up to other halls on our plans.</div>
<div class=""><br class="">
</div>
<div class="">Best,</div>
<div class=""><br class="">
</div>
<div class="">Arun<br class="">
<div><br class="">
<blockquote type="cite" class="">
<div class="">On Feb 6, 2022, at 11:38 PM, Arun Tadepalli <<a href="mailto:arunts@jlab.org" class="">arunts@jlab.org</a>> wrote:</div>
<br class="x_x_x_Apple-interchange-newline">
<div class="">
<div class="" style="word-wrap:break-word; line-break:after-white-space">Dear Nilanga,
<div class=""><br class="">
</div>
<div class="">Please find attached a snapshot from the operational restrictions document for Hall A. It contains the maximum allowable CW current on each target.</div>
<div class=""><br class="">
</div>
<div class="">Best,</div>
<div class=""><br class="">
</div>
<div class="">Arun</div>
<div class=""><br class="">
</div>
<div class=""><span id="x_x_x_cid:2CA3D081-873F-48D8-A33D-3B03E139830E"><OR_max_current.png></span><br class="">
<div class=""><br class="">
<blockquote type="cite" class="">
<div class="">On Feb 6, 2022, at 4:19 PM, David Armstrong <<a href="mailto:armd@jlab.org" class="">armd@jlab.org</a>> wrote:</div>
<br class="x_x_x_Apple-interchange-newline">
<div class="">
<div class="x_x_x_moz-cite-prefix" style="font-family:Helvetica; font-size:12px; font-style:normal; font-variant-caps:normal; font-weight:normal; letter-spacing:normal; text-align:start; text-indent:0px; text-transform:none; white-space:normal; word-spacing:0px; text-decoration:none">
Hi Folks,<br class="">
This will be a very interesting study!<br class="">
cheers,<br class="">
David<br class="">
<br class="">
On 2/6/22 3:12 PM, Liyanage, Nilanga K (nl8n) wrote:<br class="">
</div>
<blockquote type="cite" class="" style="font-family:Helvetica; font-size:12px; font-style:normal; font-variant-caps:normal; font-weight:normal; letter-spacing:normal; orphans:auto; text-align:start; text-indent:0px; text-transform:none; white-space:normal; widows:auto; word-spacing:0px; text-decoration:none">
<div class="" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt">
Dear All</div>
<div class="" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt">
<br class="">
</div>
<div class="" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt">
My objectives for the high current study are to learn about challenges in high occupancy running such as pileups in both time and space, two signals on the same strip separated by a short time) and two hits on nearby strips causing the clusters to merge.
Even if we solve all hardware problems like gain drop, we are sure to be limited by the occupancy issues in GEp. </div>
<div class="" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt">
<br class="">
</div>
<div class="" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt">
Like Kondo said the highest beam current we can take will be limited by the 1 mA limit on the GEM power supplies. The baseline GEM current is about 735 uA, and we are running around 780 uA now (with 5 uA of beam current on LH2) ; this is about 45 uA excess
current in GEM. Given this we should be able to go five times higher or more in beam current before we hit this limit. </div>
<div class="" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt">
<br class="">
</div>
<div class="" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt">
So I would like to try to go up to 25 uA on LH2 and also on LD2, if we can get those beam currents.</div>
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<br class="">
</div>
<div class="" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt">
We can do this in a few steps, say 5 uA steps in beam current. All we need are short runs, say 10 min at each setting</div>
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<br class="">
</div>
<div class="" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt">
I agree with Alex that it is best to take these without zero suppression. </div>
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<br class="">
</div>
<div class="" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt">
As Kondo suggested, at each setting we can first take a run with only one UV chamber turned on. After that run, if things look OK, turn the rest of the GEMs and take another run, and then repeat this procedure at the rest of the beam currents.</div>
<div class="" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt">
<br class="">
</div>
<div class="" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt">
If we only take the high current runs with only one chamber on, and not take the tracking runs with the other chambers on, then there is nothing we can learn about pileup and this exercise would not be very useful.</div>
<div class="" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt">
<br class="">
</div>
<div class="" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt">
So we must take tracking data to as high beam current as we can</div>
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<br class="">
</div>
<div class="" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt">
Best</div>
<div class="" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt">
<br class="">
</div>
<div class="" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt">
Nilanga</div>
<div class="" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt">
<br class="">
</div>
<div class="" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt">
Arun: Given accelerator limits and Hall C running, how much maximum beam current can we take ?</div>
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<br class="">
</div>
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<br class="">
</div>
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<div id="x_x_x_divRplyFwdMsg" dir="ltr" class=""><font face="Calibri, sans-serif" class="" style="font-size:11pt"><b class="">From:</b><span class="x_x_x_Apple-converted-space"> </span>Sbs_gems<span class="x_x_x_Apple-converted-space"> </span><a class="x_x_x_moz-txt-link-rfc2396E" href="mailto:sbs_gems-bounces@jlab.org"><sbs_gems-bounces@jlab.org></a><span class="x_x_x_Apple-converted-space"> </span>on
behalf of Holly Szumila-Vance<span class="x_x_x_Apple-converted-space"> </span><a class="x_x_x_moz-txt-link-rfc2396E" href="mailto:hszumila@jlab.org"><hszumila@jlab.org></a><br class="">
<b class="">Sent:</b><span class="x_x_x_Apple-converted-space"> </span>Sunday, February 6, 2022 10:45 AM<br class="">
<b class="">To:</b><span class="x_x_x_Apple-converted-space"> </span>Rathnayake, Anuruddha (adr4zs)<span class="x_x_x_Apple-converted-space"> </span><a class="x_x_x_moz-txt-link-rfc2396E" href="mailto:adr4zs@virginia.edu"><adr4zs@virginia.edu></a><br class="">
<b class="">Cc:</b><span class="x_x_x_Apple-converted-space"> </span><a class="x_x_x_moz-txt-link-abbreviated" href="mailto:Sbs_gems@jlab.org">Sbs_gems@jlab.org</a><span class="x_x_x_Apple-converted-space"> </span><a class="x_x_x_moz-txt-link-rfc2396E" href="mailto:Sbs_gems@jlab.org"><Sbs_gems@jlab.org></a>;
Arun Tadepalli<span class="x_x_x_Apple-converted-space"> </span><a class="x_x_x_moz-txt-link-rfc2396E" href="mailto:arunts@jlab.org"><arunts@jlab.org></a><br class="">
<b class="">Subject:</b><span class="x_x_x_Apple-converted-space"> </span>Re: [Sbs_gems] [EXTERNAL] Upper limits in terms of beam current for the GEM study planned for tomorrow</font>
<div class=""> </div>
</div>
<div dir="auto" class="">
<div dir="ltr" class="">To be clear, the question is what current limits are we willing to test up to for the gem test tomorrow on swing- probably a question for Nilanga and/or Kondo. I think this is for coordination with MCC purposes. </div>
<div dir="ltr" class=""><br class="">
<blockquote type="cite" class="">On Feb 6, 2022, at 9:52 AM, Anuruddha Rathnayake<span class="x_x_x_Apple-converted-space"> </span><a class="x_x_x_moz-txt-link-rfc2396E" href="mailto:adr4zs@virginia.edu"><adr4zs@virginia.edu></a><span class="x_x_x_Apple-converted-space"> </span>wrote:<br class="">
<br class="">
</blockquote>
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<blockquote type="cite" class="">
<div dir="ltr" class="">
<div dir="ltr" class="">Dear All,<br class="">
<br class="">
There is a discussion going on between our current RC (Arun) and some of us here in Jlab about what would be the beam current limits that we should adhere to, if it is possible to come into such a limit looking at the observations we have made so far. <br class="">
<br class="">
I'm attaching the GEM linearity studies we have done so far, if that helps to make a decision. <a href="https://logbooks.jlab.org/entry/3932489" class="x_x_x_moz-txt-link-freetext">https://logbooks.jlab.org/entry/3932489</a><br class="">
<br class="">
I believe if you use linearity studies done at SBS-11, that would be the best as our current spectrometer angles at SBS-9 are similar to what we had at SBS-9 (Please correct me if I am wrong, I know this more of as a word of mouth rather than referring to any
official documentation).<br class="">
<br class="">
Best,<br class="">
Anu<br class="">
<br class="">
</div>
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