Speaker
Description
To achieve the observation of Supernova Relic Neutrinos (SRNs) in the SK-Gd experiment for the first time all over the world, we must estimate atmospheric neutrino backgrounds precisely. The number of generated neutrons (neutron multiplicity) in an SRN event is one, while that in an atmospheric neutrino event is not necessarily one but sometimes zero, sometimes multiple. By understanding the neutron multiplicity precisely, we can reduce atmospheric neutrino backgrounds and improve the accuracy of the estimation. Unfortunately, we know that neutron multiplicity predicted from atmospheric neutrino event simulation is larger than observed data. At this moment, we have not identified the cause. The source could be neutrino-nucleus interaction, nucleon-nucleus interaction, or both. In this poster, as a first step in revealing the reason, we report the change of neutron multiplicity by the difference between the nucleon-nucleus reaction model and the consideration.
