- A search for hep neutrinos with the Sudbury Neutrino Observatory
- Howard, Christopher William
markov chain monte carlo
- Aug 18, 2010 4:25 PM
- This thesis focuses on the search for neutrinos from the solar hep reaction using the combined three phases of the Sudbury Neutrino Observatory (SNO) data. The data were taken over the years 1999–2006, totalling 1,083 days of live neutrino time. The previous published SNO hep neutrino search was completed in 2001 and only included the first phase of data taking. That hep search used an event counting approach in one energy bin with no energy spectral information included. This thesis will use a spectral analysis approach. The hep neutrino search will be a Bayesian analysis using Markov Chain Monte Carlo (MCMC), and a Metropolis-Hastings algorithm to sample the likelihood space. The method allows us to determine the best fit values for the parameters. This signal extraction will measure the 8B flux, the atmospheric neutrino background rate in the SNO detector, and the hep flux. This thesis describes the tests used to verify the MCMC algorithm and signal extraction. It defines the systematic uncertainties and how they were accounted for in the fit. It also shows the correlations between all of the parameters and the effect of each systematic uncertainty on the result. The three phase hep signal extraction was completed using only 1/3 of the full data set. With these lowered statistics, this analysis was able to place an upper limit on the hep flux of 4.2 × 10^4 cm−2 s−1 with a 90% confidence limit. It was able to measure a hep flux of (2.40(+1.19)(-1.60))×10^4 cm−2 s−1. These numbers can be compared with the previous SNO upper limit of 2.3×10^4 cm−2 s−1 with a 90% confidence limit, and the standard solar model prediction of (7.970 ± 1.236) × 10^3 cm−2 s−1.
- Doctor of Philosophy
- Department of Physics
- Fall 2010
- Aksel Hallin (Physics)
Theses and Dissertations Spring 2009 to present
Department of Physics
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