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<div>I would think that final background rates and engineering input would be needed before the final decision is make. Both Cu and Pb have advantages.</div>
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<div>Paul</div>
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<span style="font-weight:bold">From: </span>Solid_baffle <<a href="mailto:solid_baffle-bounces@jlab.org">solid_baffle-bounces@jlab.org</a>> on behalf of "Richard S. Holmes" <<a href="mailto:rsholmes@syr.edu">rsholmes@syr.edu</a>><br>
<span style="font-weight:bold">Date: </span>Monday, July 11, 2016 at 3:22 PM<br>
<span style="font-weight:bold">To: </span>Zhiwen Zhao <<a href="mailto:zwzhao@jlab.org">zwzhao@jlab.org</a>>, "<a href="mailto:solid_baffle@jlab.org">solid_baffle@jlab.org</a>" <<a href="mailto:solid_baffle@jlab.org">solid_baffle@jlab.org</a>><br>
<span style="font-weight:bold">Subject: </span>Re: [Solid_baffle] baffle material<br>
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<div dir="ltr">There are some slides in this talk <a href="https://hallaweb.jlab.org/wiki/images/9/95/Baffles_5-15_rsholmes.pdf">https://hallaweb.jlab.org/wiki/images/9/95/Baffles_5-15_rsholmes.pdf</a> (two slides from Zhiwen and three of mine), which also
are summarized in my baffle writeup at <a href="https://hallaweb.jlab.org/wiki/images/9/91/Baffles_writeup_2-2016.pdf">https://hallaweb.jlab.org/wiki/images/9/91/Baffles_writeup_2-2016.pdf</a>. With Cu the photon rate is about 15% higher than for Pb overall.
The energy dependence of this probably should be checked. With Pb lined Cu the photon rate is about 8% higher, and if the last baffle is solid Pb it<span style="line-height:1.5"> performs about the same as Pb. Pb lined Cu has some of the advantages of solid
Cu, though it would be the same as far as machining the slits is concerned.</span>
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<div>There were questions about the activation of Cu which I'm not sure we ever got a good answer to.</div>
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<div dir="ltr">On Mon, Jul 11, 2016 at 3:02 PM Zhiwen Zhao <<a href="mailto:zwzhao@jlab.org">zwzhao@jlab.org</a>> wrote:<br>
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<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Dear All<br>
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The question about baffle material was raised by the review committee<br>
and need to be addressed<br>
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I had the study last year showing Copper seems not a bad choice among<br>
other materials.<br>
<a href="http://hallaweb.jlab.org/12GeV/SoLID/download/baffle/talk/solid_baffle_zwzhao_20150316.pdf" rel="noreferrer" target="_blank">http://hallaweb.jlab.org/12GeV/SoLID/download/baffle/talk/solid_baffle_zwzhao_20150316.pdf</a><br>
I think Rich also had some study favoring Copper, but I can't find the<br>
record any more.<br>
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If we decide on Copper, we can<br>
1. use that to do background and trigger study from now on.<br>
2. Rich could further tune baffle because Copper can be machined with<br>
good precision.<br>
(for example, maybe the inner surface of baffle slit can have some<br>
angle to follow electrons within the 9cm length)<br>
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Practically, it would be some kind Copper alloy.<br>
Roger from hallC has good suggestion and experience from Qweak Collimator<br>
Seamus, maybe you can even get some cost estimation to update the very<br>
rough number in pCDR.<br>
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Thanks<br>
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Zhiwen<br>
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