Exploring Diffuse Supernova Neutrino Background in Hyper-Kamiokande

Sammanfattning: This thesis studies the Diffuse Supernova Neutrino Background (DSNB) that is expected to be detected in the future neutrino detector Hyper-Hamiokande. DSNB refers to the flux which is made up of neutrinos from all past core-collapsing supernova explosions. The ability to determine the mass hierarchy and the ability to determine parameters of the initial flux by using DNSB are investigated. For comparison is the neutrino flux detected in Hyper-Kamiokande coming from a galactic supernova at a distance of 10 kpc calculated and studied. Different aspects of the calculations are varied in order to see how they affect the ability to determine the mass hierarchy. The result shows that the different models of the initial neutrino flux have the greatest impact on the ability to determine the mass hierarchy. According to the calculations, it will take between 3-36 years of detecting DSNB through inverted beta decay in the range of 16-30 MeV in order to determine the mass hierarchy to the confidence level of 3σ. The possibility of reducing the background noise using neutron tagging can reduce the number of years from 10 to 3 years. The detected spectrum from a single galactic supernova can provide a confidence level within the range of 43σ to 122σ. However, the DSNB can give a significant result regarding the mass hierarchy before a galactic or near-galactic supernova event is possible to detect. The calculated confidence regions for the parameters of the initial flux show that a galactic supernova spectrum gives at least 30 times better precision than what DSNB collected over 10 years can give. The result also shows that mass hierarchy affects the size of the confidence region and the ability to determine some of the parameters.