<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><br><div>Begin forwarded message:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;"><span style="font-family:'Helvetica'; font-size:medium; color:rgba(0, 0, 0, 1);"><b>From: </b></span><span style="font-family:'Helvetica'; font-size:medium;">PROCUREUR Sébastien <<a href="mailto:sebastien.procureur@cea.fr">sebastien.procureur@cea.fr</a>><br></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;"><span style="font-family:'Helvetica'; font-size:medium; color:rgba(0, 0, 0, 1);"><b>Date: </b></span><span style="font-family:'Helvetica'; font-size:medium;">September 6, 2012 3:56:33 AM EDT<br></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;"><span style="font-family:'Helvetica'; font-size:medium; color:rgba(0, 0, 0, 1);"><b>To: </b></span><span style="font-family:'Helvetica'; font-size:medium;">Lei Guo <<a href="mailto:lguo@jlab.org">lguo@jlab.org</a>><br></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;"><span style="font-family:'Helvetica'; font-size:medium; color:rgba(0, 0, 0, 1);"><b>Subject: </b></span><span style="font-family:'Helvetica'; font-size:medium;"><b>RE : dvcs plots and simulation</b><br></span></div><br><div>Hi Lei,<br><br> I indeed made some simulations with different values for the torus field, down to 50% of its nominal value.<br>DVCS events were generated using dvcsgen, then propagated in Gemc and reconstructed with Socrat. The conclusions are the following (the text below is what I sent to Latifa, Harut, and other people):<br>"<br>- the electron momentum resolution varies with 1/B as expected, which means the resolution is deteriorated by a factor of 2 with a 50% torus field. The other variables (phi, theta, z) are not affected by the torus field, as expected too.<br>- the effect of a 50% torus field is negligible on the "exclusive" resolutions of DVCS (see attached plot, where black corresponds to nominal torus field, and red to 50%). This is because these resolutions are dominated by the proton reconstruction in the Barrel. To understand this, one has to keep in mind that proton resolutions are very close to the CLAS12 requirement (5% in Dp/p) whereas the electron resolution is better (0.5% in Dp/p for a requirement at 1%).<br>- a lower torus field increases the electron acceptance. In the simulated regime (Q2>1.5GeV2) this effect is limited to 5%, but is certainly higher at smaller Q2. And also (much) higher for other reactions involving large angle, positively charged particles.<br>Of course, these conclusions may differ for other proposals. However, the fact that the electron momentum resolution is better than the original CLAS12 requirements means an optimization between acceptance and "event" resolution should be done.<br>"<br>Concerning the simulations, what I did for Harut and other people is a reconstruction using the chain Pythia-Gemc-Socrat. Please note that Socrat reconstructs only charged particles, plus photons in the IC calorimeter. Sadly, I should say I prefer not to provide the Socrat code anymore for various reasons, the main one is that the official CLAS12 tracking code (based on Socrat) will soon be released by the software group. However, if you want to study any particular process/configuration (using Pythia generator, or another one compatible with the LUND format), I will do my best to run the whole chain and provide you with the output files from both Gemc and Socrat.<br><br>Let me know,<br>Sébastien.<br><br>________________________________________<br>De : Lei Guo [lguo@jlab.org]<br>Date d'envoi : mardi 4 septembre 2012 15:59<br>À : PROCUREUR Sébastien<br>Objet : dvcs plots and simulation<br><br>HI, Dear Sebastien,<br><br>Franck gave me your email address. I have two questions for you.<br>1. Franck told me that you did simulation to show the impact of the<br>field setting on the p-DVCS experiment. Could you forward those plots<br>to me?<br>2. I also heard you did a "full" reconstruction simulation recently.<br>Do you have the software available to everybody? If not, could you let<br>me know how to replicate what you have done, for other CLAS12<br>experiments?<br><br><br>Thanks a lot!<br><br>Lei<br>**************************************<br> @<br> / *<br> / ___ ___ Lei Guo _______________________<br> L_O_/ ____ Florida International University____/_/<br> \ | Physics Dept., CP<br>212 / /<br> / \ | Miami, FL<br>33199 / / /<br> / I_/ \ ____ USA _____ /______/__________/ /<br> / /<br>L<br> / / / / /<br> / / / / / / /<br> /_/__________/______/______/__________/_/<br>/_/__________/______/______/__________/_/<br>305-348-0234(o)<br><br>**************************************<img id="079f7440-434a-4aef-a936-696ec6d657a4" height="572" width="796" apple-width="yes" apple-height="yes" src="cid:4EB5CF75-1893-4E92-AE36-8E1E6F7FB641@fiu.edu"></div></blockquote></div><br><div>
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><div>**************************************</div><div> @</div><div> / *</div><div> / ___ ___ Lei Guo _______________________</div><div> L_O_/ ____ Florida International University____/_/</div><div> \ | Physics Dept., CP 212 / /</div><div> / \ | Miami, FL 33199 / / /</div><div> / I_/ \ ____ USA _____ /______/__________/ /</div><div> / / L / / / / /</div><div> / / / / / / /</div><div> /_/__________/______/______/__________/_/</div><div>/_/__________/______/______/__________/_/</div><div>305-348-0234(o)</div><div><br></div><div>**************************************</div><div><br></div></div></div></span><br class="Apple-interchange-newline"></div></span><br class="Apple-interchange-newline"></div></span><br class="Apple-interchange-newline"></span><br class="Apple-interchange-newline">
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