Created attachment 681 [details] The spectrum of gamma rays simulated by Geant4 version 10.7, 4.10.3 , 10.3.p01 , and 10.3.p02 Hi Bugzilla， I simulated the spectrum of gamma rays produced by neutron capture on gadolinium by using Geant4 10.7. The spectrum of individual gamma ray energies appears to be shifted to higher energies and the total gamma ray energy has a long tail above the Q-value. However a paper named "A plastic scintillator array for reactor based anti-neutrino studies " published in 2015，shows that the spectrum of gamma rays does not exceed 8.5*MeV, which simulated by using Geant4 4.10.3 . In addition，in Geant4 forum some people also have encountered with this problem. The topic named "weird features in gamma spectrum for neutron capture on gd". It seems that this problem may not have solved. They found that “In upgrading from Geant4 10.3.p01 to 10.3.p02, the spectrum of gamma rays produced by neutron capture on gadolinium got changed.”And they think that may be a bug. The spectrum of gamma rays simulated by Geant4 version 10.7, 4.10.3 , 10.3.p01 , and 10.3.p02, are attached in the attachment（a compressed file）. Thanks for your attention！
