| dc.description.abstract | This thesis presents the rate of Carbon-11 production in the SNO+ scintillator phase. Carbon-11, created by a cosmogenic muon interacting with Carbon-12, is a background to the solar neutrino studies planned for the SNO+ scintillator phase. With a half-life of 20.3 minutes, Carbon-11 cannot be removed from analyses with a simple 20 or 60 second post-muon veto as many of the muon-induced backgrounds in SNO+ are. Instead Carbon11 can be identified using a three-fold coincidence, firstly the muon passing through the scintillator, then a coincident neutron capture, and finally an event with the expected energy of a Carbon-11 decay that is sufficiently close spatially to the neutron capture within several half-lives. This thesis details the steps taken to tune the pre-existing muon identification from water phase to scintillator phase, the development of a coincident neutron capture identification, and the results of both these steps in partial fill and scintillator phases. This thesis then outlines the development of a likelihood algorithm that calculates a likelihood for every Carbon-11 candidate, and shows the results of this algorithm in the scintillator phase. A likelihood was chosen to allow for a strict cut to remove Carbon-11 from analyses, while also allowing a pure sample of Carbon-11 to be found in order to perform a data-MC calibration. A background rejection cut of 0.01 likelihood was chosen, removing 94% of the 11C with only a 1% sacrifice of signal. Then two higher purity likelihood cuts are presented, 0.2 and 0.4. The 0.2 cut has a purity of 0.6, whilst the 0.4 cut has a purity of 0.9, but is statistically limited. | en_US |
