XXth International Conference on Neutrino Physics and Astrophysics
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.