<div dir="ltr">Mike, Nathan, and all,<div><br></div><div>I whole-heartedly agree with Curtis. Anything in the logbook is for our internal consumption only, and represents a snapshot of where we are at any particular moment as we move forward toward understanding our systematics. Thank you for sharing what you have, I think it is helpful.<div><br></div><div>-Richard Jones</div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Mar 14, 2016 at 8:34 AM, Curtis A. Meyer <span dir="ltr"><<a href="mailto:cmeyer@cmu.edu" target="_blank">cmeyer@cmu.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div style="word-wrap:break-word">Hi Everyone -<div><br></div><div> I just wanted to comment that there has been spectacular progress on all fronts in</div><div>understanding the degree of linear polarization. Everyone involved has done a </div><div>fantastic job in getting preliminary results out as quickly as possible, and the entire </div><div>collaboration is thrilled to see that within errors, all the methods that we have report</div><div>consistent (preliminary) results. We now know that our diamonds are producing </div><div>coherent bremsstrahlung and appear quite consistent with our predictions. This</div><div>work is something we should all be very proud of.</div><div><br></div><div> We also fully understand that none of these results are final. But the fact that people</div><div>are able to get us preliminary results is crucial to our moving forward. I also feel that</div><div>without the apparent redundancy that we have, most of us would not be nearly as </div><div>comfortable as we are now.</div><div><br></div><div> Curtis</div><div><div>
<span style="border-collapse:separate;color:rgb(0,0,0);font-family:Helvetica;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:-webkit-auto;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><div><div>---------</div><div>Curtis A. Meyer<span style="white-space:pre-wrap"> </span>MCS Associate Dean for Faculty and Graduate Affairs</div><div>Wean: <a href="tel:%28412%29%20268-2745" value="+14122682745" target="_blank">(412) 268-2745</a><span style="white-space:pre-wrap"> </span>Professor of Physics</div><div>Doherty: <a href="tel:%28412%29%20268-3090" value="+14122683090" target="_blank">(412) 268-3090</a><span style="white-space:pre-wrap"> </span>Carnegie Mellon University</div><div>Fax: <a href="tel:%28412%29%20681-0648" value="+14126810648" target="_blank">(412) 681-0648</a><span style="white-space:pre-wrap"> </span>Pittsburgh, PA 15213</div><div><a href="mailto:curtis.meyer@cmu.edu" target="_blank">curtis.meyer@cmu.edu</a><span style="white-space:pre-wrap"> </span><a href="http://www.curtismeyer.com/" target="_blank">http://www.curtismeyer.com/</a></div></div><div><br></div></span><br>
</div><div><div class="h5">
<br><div><blockquote type="cite"><div>On Mar 14, 2016, at 8:17 AM, Nathan Sparks <<a href="mailto:nsparks@jlab.org" target="_blank">nsparks@jlab.org</a>> wrote:</div><br><div><div>The reported degree of polarization from the TPOL is a rough estimate, based on the information I had available at the time.<br>I have no reason to believe it is not in the right ballpark, and it was not presented as a final result.<br><br>-Nathan<br><blockquote type="cite">On Mar 14, 2016, at 7:48 AM, <a href="mailto:dugger@jlab.org" target="_blank">dugger@jlab.org</a> wrote:<br><br>Hi,<br><br>The reported polarizations for the polarimeter are not correct. It was too<br>early for the degree of polarization to have been reported.<br><br>Take care,<br>Michael<br><br><blockquote type="cite">Message from Ken regarding comparison between different methods for beam<br>polarization estimation.<br>-forwarded by Richard Jones<br><br>---------- Forwarded message ----------<br>From: Ken Livingston <<a href="mailto:Kenneth.Livingston@glasgow.ac.uk" target="_blank">Kenneth.Livingston@glasgow.ac.uk</a>><br>Date: Mon, Mar 14, 2016 at 6:35 AM<br>Subject: Re: polarization update<br>To: Justin Stevens <<a href="mailto:jrsteven@jlab.org" target="_blank">jrsteven@jlab.org</a>>, Nathan Sparks <<a href="mailto:nsparks@jlab.org" target="_blank">nsparks@jlab.org</a>>,<br>Richard Jones <<a href="mailto:richard.t.jones@uconn.edu" target="_blank">richard.t.jones@uconn.edu</a>><br><br><br>Hi Justin,<br>That a very nice study. It's exactly what's needed. If we believe the<br>photon asymmetry for the rho in this energy range is really 1, and are<br>convinced that it's very cleanly extracted signal, that's the best<br>polarimiter we can have. It has an event rate that's better than the<br>triple<br>polarimiter and doesn't need an analysing power, and it does not need all<br>the vaguely known parameters that are required to match the enhancement<br>with a coherent brem calculation.<br><br>For the 20 um radiator it's also good to see that, as we'd expect, the<br>shape of the enhancement (and hence polarization) is much better with<br>collimated data rather than raw scalers. The similarity between the<br>polarization for the 20um and 50um is borne out by Nathan's studies<br>although the energy range is different (8-9GeV).<br><br>It looks like both your studies are assuming that Ppara = Pperp.<br>I got the impression from the raw spectra that this might not be true for<br>the 20um diamond. It would be good to check this out.<br>A quick and check would come from using the more complicated fit function<br>I<br>sent you earlier, where the flux ratio and pol ratio are free parameters.<br><blockquote type="cite">From this, you could plot the pol ratio as a function of E_gammma, as you<br></blockquote>have for Sigma.<br><br>My "phenomenological fit" is clearly not as phenomenal as I'd hoped. It<br>doesn't cope with the ~200MeV spread in the coherent edge for the 20um<br>diamond. I believed it would. It can fit almost any enhancement, but is<br>not<br>much use if it doesn't get the corresponsing polarization correct. Either<br>I've made a silly assumption somewhere, screwed up the algebra or screwed<br>up the code. Maybe all three together - although it generally gives good<br>agreement when used to extract asymmetries and compare with previous<br>measurements.<br><br>I'll need to scrutinise it as soon as I get time.<br><br><br>Regards,<br>Ken<br><br><br><br><br><br><br><br>On 11/03/16 17:06, Justin Stevens wrote:<br><br><blockquote type="cite">FYI, from this mornings meeting: rho and TPOL asymmetries comparing 20<br>and<br>50 um diamonds.<br><br><a href="https://logbooks.jlab.org/entry/3390212" target="_blank">https://logbooks.jlab.org/entry/3390212</a><br><a href="https://logbooks.jlab.org/entry/3390218" target="_blank">https://logbooks.jlab.org/entry/3390218</a><br><br></blockquote><br><br>--<br>=======================================================<br>Ken Livingston<br><br>Dept. of Physics & Astronomy, Tel: <a href="tel:%2B44%20141%20330%206428" value="+441413306428" target="_blank">+44 141 330 6428</a><br>University of Glasgow, Fax: <a href="tel:%2B44%20141%20330%205889" value="+441413305889" target="_blank">+44 141 330 5889</a><br>Glasgow G12 8QQ.<br>Scotland. 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