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Hi Sanghwa,</div>
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I assume it depends how and where this FFB system impacts. I copied B team here to get their opinion assuming the north linac vacuum issue is resolves soon.</div>
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Thanks,</div>
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HyeKyoung<br>
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<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> Sanghwa Park <sanghwa@jlab.org><br>
<b>Sent:</b> Thursday, August 20, 2020 5:40 PM<br>
<b>To:</b> HyeKyoung Park <hkpark@jlab.org><br>
<b>Cc:</b> Jay Benesch <benesch@jlab.org>; Steve Suhring <suhring@jlab.org>; Paul Vasilauskis <vasilaus@jlab.org><br>
<b>Subject:</b> Re: B team meeting</font>
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<div>Hello,</div>
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<div>Thank you for initiating the discussion. While I am not sure we need a meeting, I just wanted to add some details from our observations. The figure below shows the run-wise average dp/p and sigma (while there is beam) from physics run in Hall A. The 2A
energy lock was engaged using Hall D beam today during the Moller measurement, but this doesn't seem to work very well for us. </div>
<div>For us, we monitor HALL:dpp closely during the data taking and this value to be around
<b>-</b>1.e-4 +/- 1.e4. If the dp/p drift by more than 1.e4, this reflects 1.6 mm drift on our detector which would bring additional background in our measurements. </div>
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<div>If the FFB system works, that would be ideal.. but so far when we turn on the FFB (and FF) on, it brings noise in our BPMs and reduces sensitivity in our energy slope</div>
<div>and we also observe instability to Compton central rate too. So, unless the FFB issue gets resolved we prefer to run without FFB.</div>
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<div>My question to the PD was if there are other options to stabilize the energy in the machine. If people think a meeting will be useful for the discussion, I am happy to attend and provide additional information. Please let me know how you would like to
proceed.</div>
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<div>Thanks,</div>
<div>Sanghwa</div>
<div><img alt="image.png" width="562" height="246" data-outlook-trace="F:1|T:1" src="cid:ii_ke3b0k960"><br>
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<div dir="ltr" class="x_gmail_attr">On Thu, Aug 20, 2020 at 4:22 PM HyeKyoung Park <<a href="mailto:hkpark@jlab.org" target="_blank">hkpark@jlab.org</a>> wrote:<br>
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Hi Jay,</div>
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<div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt">Sanghwa (Hall A RC) requested a meeting to discuss options to improve the hall A beam stability.
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<div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt">I propose we switch to B team meeting after 0800 meeting tomorrow. I'd also invite other hall run coordinators since the remedy might have impact on their beams.
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Would you please forward this note to the beam team? I don't have the whole list. Please feel free to add the details that hall A has encountered today.</div>
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Thanks!</div>
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HyeKyoung<br>
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<div dir="ltr"><span style="font-size:12.8px">Sanghwa Park</span>
<div style="font-size:12.8px">Stony Brook University</div>
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