XXth International Conference on Neutrino Physics and Astrophysics

Poster Abstract

M.Dragowsky, A.Hime & J.J.Simpson for the SNO Collaboration

Sudbury Neutrino Observatory Neutron Calibration in the Pure D2O Phase

Sudbury Neutrino Observatory (SNO) charged current, elastic scattering and neutral current (NC) signal separation is achieved through a decomposition based on predicted characteristic distributions obtained from the SNO Monte Carlo (SNOMAN). Extracting the NC signal requires detailed knowledge of neutron transport, including neutron detection efficiency measurements and the detector neutron response. The Monte Carlo predictions for neutron detection efficiency, capture event radial profile, energy and mean lifetime are tested against data obtained from 252Cf. In addition, the neutron detection efficiency is obtained from two independent techniques. One approach relies on knowing the neutron emission rate from the calibration source and identifying neutron capture events. The other uses the 252Cf neutron multiplicity distribution to fit for both the 252Cf fission rate and the SNO detector neutron detection efficiency for a point neutron source. The connection between the point source calibrations and systematic uncertainties for the uniformly distributed NC signal is made through an analytic diffusion model and Monte Carlo. The program to obtain and analyze calibration data as well as the assessment of uncertainties in the NC extraction due to this calibration are presented.

Based on nucl-ex/0204008 and nucl-ex/0204009.

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