<div id="ymail_android_signature"><span style="color: rgb(109, 0, 246); font-family: Roboto, sans-serif;" id="yMail_cursorElementTracker_1619527010770">Dear users</span></div><div id="ymail_android_signature"><span style="color: rgb(109, 0, 246); font-family: Roboto, sans-serif;" id="yMail_cursorElementTracker_1619527044977"><br></span></div><div id="yMail_cursorElementTracker_1619527027653">According to the problem with scintillation photons on optical simulation with vgate9.0 and the solution of it regarding the link below:</div><div id="yMail_cursorElementTracker_1619527027653"><a href="http://lists.opengatecollaboration.org/pipermail/gate-users/2020-October/011977.html" target="_blank" id="yMail_cursorElementTracker_1619527029374">http://lists.opengatecollaboration.org/pipermail/gate-users/2020-October/011977.html</a></div><div id="yMail_cursorElementTracker_1619527035633">Could anyone help me how to downgrade the Geant4 in vGate9.0?</div><div id="yMail_cursorElementTracker_1619527040295"><br></div><div id="yMail_cursorElementTracker_1619527041743">Thanks a lot</div>