Ryan Martin (Queen's University and Lawrence Berkeley National Laboratory)
This poster presents the techniques that were developed for analyzing the data from an array of 36 strings of low background 3He proportional counters that were deployed during the third phase of the Sudbury Neutrino Observatory experiment. The counters were used to detect neutrons created by the Neutral Current interaction of solar neutrinos with deuterium; measuring the production rate of these neutrons is a direct measurement of the total flux 8B of solar neutrinos. The methods presented in this poster are aimed at substantially increasing the ratio of signal to background events. The number of neutrons in the data is determined by fitting the energy spectrum of these events. By increasing the signal-to-background ratio the total number of neutron events can be determined more accurately. We use a combination of three different pulse-shape-analysis techniques, including the use of calibration data, simulated signal and background events, and the skewness and kurtosis characteristics of the pulses. The cuts on the events were optimized to reject approximately 98% of alpha events while retaining 75% of the neutrons. The energy-spectrum fit on this cleaned data results in a significant improvement compared to previously published analysis of this data.