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<p style="margin-top:0;margin-bottom:0">I made a DocDB entry with a couple of plots relevant to the empty target running optimization,</p>
<p style="margin-top:0;margin-bottom:0">including the code which generated these plots.</p>
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<p style="margin-top:0;margin-bottom:0">Eugene</p>
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<p style="margin-top:0;margin-bottom:0"><a href="https://halldweb.jlab.org/doc-private/DocDB/ShowDocument?docid=3934" class="OWAAutoLink" id="LPlnk792922" previewremoved="true">https://halldweb.jlab.org/doc-private/DocDB/ShowDocument?docid=3934</a></p>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Primexd <primexd-bounces@jlab.org> on behalf of Eugene Chudakov <gen@jlab.org><br>
<b>Sent:</b> Sunday, March 3, 2019 3:48:27 AM<br>
<b>To:</b> gasparan@jlab.org; Ilya Larin<br>
<b>Cc:</b> primexd@jlab.org<br>
<b>Subject:</b> Re: [Primexd] Be empty optimal time</font>
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<p style="margin-top:0; margin-bottom:0">I attach a picture for the relative stat. error of the result depending on the fraction of the BG events in the full-target sample and the fraction of time spent on the empty target. The optima are rather broad.</p>
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<p style="margin-top:0; margin-bottom:0">Eugene</p>
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<div id="x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> Primexd <primexd-bounces@jlab.org> on behalf of gasparan@jlab.org <gasparan@jlab.org><br>
<b>Sent:</b> Saturday, March 2, 2019 12:06:27 PM<br>
<b>To:</b> Ilya Larin<br>
<b>Cc:</b> primexd@jlab.org<br>
<b>Subject:</b> Re: [Primexd] Be empty optimal time</font>
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Hi Ilya,<br>
<br>
It sounds very realistic arguments for the empty statistics.<br>
The ~25% number was close that we been talking in the last week.<br>
If this is right and if the quality of the empty statistics is<br>
okay, then we suppose to be not bad with the Be Compton.<br>
<br>
The next question is the sequence of "empty"s for the LHe4 target.<br>
Is your arguments transferable to this target also?<br>
If it is yes then we better to have ~30% "empty"s for the coming<br>
runs.<br>
<br>
Thanks,<br>
Ashot<br>
<br>
<br>
><br>
> Hi Ashot,<br>
><br>
><br>
> following our Thursday's meeting discussion about what should be<br>
><br>
> the optimal fraction of empty target statistics collection time,<br>
><br>
> I tried to calculate it assuming that errors are proportional to the<br>
> square root<br>
><br>
> of event numbers (which is not exactly true of course).<br>
><br>
> If I didn't make a mistake somewhere in math - the result<br>
><br>
> in the attached plot (vertical axis - fraction of time (vs total time)<br>
> optimal to spent for empty<br>
><br>
> target measurement for subtraction; horizontal axis - level of background<br>
><br>
> observed for empty target vs spectrum height observed for target inserted<br>
> case,<br>
><br>
> normalized to the same flux).<br>
><br>
> I got the simple formula for the quantity in the plot: y = 1 -<br>
> (1-sqrt(x))/(1-x).<br>
><br>
> If it is true, for our case the optimum for Be is between 25%...30% of<br>
> total Be time<br>
><br>
> to spend for Be empty (bckgr level x = 0.1...0.2).<br>
><br>
><br>
> Best regards,<br>
><br>
> Ilya.<br>
><br>
><br>
><br>
<br>
<br>
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