Time series analysis for the CF source in Sudbury Neutrino Observatory
The Sudbury Neutrino Observatory uses a 252Cf source to measure the neutron detection efficiency of its detector. We propose a method, the Time Series Analysis, that uses pairs of time intervals between the detected events to find the neutron detection efficiency, the probability to detect from a fission the prompt [gamma]-rays, the neutron mean life inside the detector, the source fission rate and the residual activity rate from non-fission events. We explain our theoretical model of the source and the procedure to fit the data. With a 2.5 MeV threshold cut on the data, the neutron mean life is 5.281 ± 0.004(stat) msec and the source fission rate at June 12, 2001 is 4.360 ± 0.004(stat) sec -1. At this moment, the Time Series can only be applied to data when the source is near the centre. The technique is also applied with an AmBe source. We also show the latest progress to improve the technique. Finally, we briefly show another method, the Multiplicity Analysis, which was used before we changed to the Time Series.