<html><head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Hi Gaters,<div class=""><br class=""></div><div class="">I am trying to understand results output by the dose actor, which I enabled with the following lines:</div><div class=""><br class=""></div><div class=""><div class="">/gate/actor/addActor DoseActor dose5</div><div class=""> /gate/actor/dose5/save <span style="color: rgb(0, 0, 0); font-family: Menlo; font-size: 11px;" class="">results/dose_2021May11_171652_5.root</span></div><div class=""> /gate/actor/dose5/attachTo box5</div><div class=""> /gate/actor/dose5/stepHitType random</div><div class=""> /gate/actor/dose5/setResolution 1 10 1</div><div class=""> /gate/actor/dose5/enableDose true</div><div class=""> /gate/actor/dose5/enableUncertaintyDose true</div><div class=""> /gate/actor/dose5/enableNumberOfHits true</div><div class=""><br class=""></div></div><div class="">The source is a pencil beam of protons of 100 MeV. I simulated 10000 events.</div><div class=""><br class=""></div><div class="">Here is the histogram I got:</div><div class=""><img apple-inline="yes" id="FB1EE12D-028F-4D15-BF0D-945FF1B50B9B" src="cid:769C72E4-851D-4BB3-AF6E-9ECD44B40F14" class=""></div><div class=""><br class=""></div><div class="">My question is why is the error so large? How is it calculated?</div><div class=""><br class=""></div><div class="">Cheers,</div><div class=""><br class=""></div><div class="">Dmitry</div><div class=""><br class=""></div></body></html>