<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Hello Nicollas,<div class=""><br class=""></div><div class="">You can use the ion source to simulate the I-131 isotope. But you have to put the radioactive decay process in the physics list. You can define this source as:</div><div class=""><br class=""></div><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/gate/source/addSource I-131 gps</span></div></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/gate/source/I-131/gps/particle ion</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><div style="margin: 0px; line-height: normal;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/gate/source/</span>I-131/gps/ion 53 131 0 0</div><div style="margin: 0px; line-height: normal;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/gate/source/</span>I-131/gps/ene/mono 0.0 MeV</div><div style="margin: 0px; line-height: normal;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/gate/source/</span>I-131/gps/ang/type iso</div><div style="margin: 0px; line-height: normal;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><div style="margin: 0px; line-height: normal;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/gate/source/</span>I-131/gps/pos/type Volume</div><div style="margin: 0px; line-height: normal;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/gate/source/</span>I-131/gps/shape Point </div><div style="margin: 0px; line-height: normal;" class=""><span style="font-variant-ligatures: no-common-ligatures;" class="">/gate/source/</span>I-131/gps/centre 0. 0. 0. cm</div></span></div></span></div><div class=""><br class=""></div><div class=""><span style="background-color: rgb(255, 255, 255);" class=""><font face="Menlo" class=""><span style="font-size: 11px;" class="">This definition depends on what you want to simulate. See users guide version 8.0, page 123 to define the shape of the source. </span></font></span></div><div class=""><span style="background-color: rgb(255, 255, 255);" class=""><font face="Menlo" class=""><span style="font-size: 11px;" class=""><br class=""></span></font></span></div><div class=""><span style="background-color: rgb(255, 255, 255);" class=""><font face="Menlo" class=""><span style="font-size: 11px;" class="">Thanks,</span></font></span></div><div class=""><font face="Menlo" class=""><span style="font-size: 11px; background-color: rgb(255, 255, 255);" class="">Ashok Tiwari</span></font></div></body></html>