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<div class="">Hi All,</div>
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<div class=""> I’ve posted some minutes from the meeting this morning (up to the point I left). Others may feel free to modify and add to.</div>
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<div class=""><a href="https://halldweb.jlab.org/wiki/index.php/Π_polarizability_Meeting_Apr_15,_2020" class="">https://halldweb.jlab.org/wiki/index.php/%CE%A0_polarizability_Meeting_Apr_15,_2020</a></div>
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<span class="mw-headline" id="Minutes">Minutes</span><span class="mw-editsection" style="font-size: small; margin-left: 1em; vertical-align: baseline; line-height: 1em; display: inline-block;"><span class="mw-editsection-bracket">[</span><a href="https://halldweb.jlab.org/wiki/index.php?title=%CE%A0_polarizability_Meeting_Apr_15,_2020&action=edit§ion=4" title="Edit section: Minutes" style="text-decoration: none; color: rgb(90, 54, 150); background: none;" class="">edit</a><span class="mw-editsection-bracket">]</span></span></h2>
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Attendees: Albert F., Andrew S., Elton S., Iliya L., Mark I., Rory M., Nick B., Vambow</div>
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<b class="">Engineering</b></div>
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<li style="margin-bottom: 0.1em;" class="">Tim sent e-mail a few days ago asking about alignment requirements of absorbers and chambers
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<li style="margin-bottom: 0.1em;" class="">is +/-4mm good enough</li><li style="margin-bottom: 0.1em;" class="">what about reproducibility if platform must be moved</li></ul>
</li><li style="margin-bottom: 0.1em;" class="">General consensus was that 4mm will not be accurate enough given the size of the beam spot and holes.</li><li style="margin-bottom: 0.1em;" class="">Some top-of-the-head estimates that we'll need at least +/-2mm and possibly even better</li><li style="margin-bottom: 0.1em;" class="">Elton noted that +/-1mm will probably be pretty difficult but we'll need to discuss it with Tim</li><li style="margin-bottom: 0.1em;" class="">Iliya suggested a different spec. for the upstream Pb absorber than other components may be an option since that will be stopping most of the low energy beam halo</li><li style="margin-bottom: 0.1em;" class="">Rory will respond to Tim's e-mail and ask if we can schedule a meeting next week to discuss it</li></ul>
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<b class="">e+e- Simulation</b></div>
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<li style="margin-bottom: 0.1em;" class="">Andrew has made some progress in calculating the acceptance of e+e- events as a function of invariant mass.
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<li style="margin-bottom: 0.1em;" class="">expanded cut on θ to be >0.75<sup style="line-height: 1;" class="">o</sup> as opposed to previous cut of >0.1<sup style="line-height: 1;" class="">o</sup></li><li style="margin-bottom: 0.1em;" class="">acceptance peak dropped to below 1.0 (previously it had been >3)</li><li style="margin-bottom: 0.1em;" class="">discussed the possibility of floating point round off errors, but unable to clearly identify that as source.</li></ul>
</li><li style="margin-bottom: 0.1em;" class="">Some work has started on MVA</li></ul>
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<b class="">Jeopardy</b></div>
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<li style="margin-bottom: 0.1em;" class="">Suggested schedule from Bob M. was to keep new proposals due June 1st (no change) and give Jeopardy proposals an extra 2 weeks (June 15th).</li><li style="margin-bottom: 0.1em;" class="">Schedule not finalized yet and will depend on negotiations between PAC members and lab management</li><li style="margin-bottom: 0.1em;" class="">Rory will set up LateX document with outline so we can start working on it.</li></ul>
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