The 16N calibration source for the Sudbury Neutrino Observatory

A calibration source using gamma-rays from N-16 (t(1,2) = 7.13 s) beta-decay has been developed for the Sudbury Neutrino Observatory (SNO) for the purpose of energy and other calibrations. The N-16 is produced via the (n,p) reaction on 160 in the form of CO2 gas using 14-MeV neutrons from a commercially available Deuterium-Tritium (DT) generator, The N-16 is produced in a shielding pit in a utility room near the SNO cavity and transferred to the water volumes (D2O or H2O) in a CO2 gas stream via small diameter capillary tubing, The bulk of the activity decays in a decay/trigger chamber designed to block the energetic beta-particles yet permit the primary. branch 6.13 MeV gamma-rays to exit. Detection of the coincident P-particles with plastic scintillator lining the walls of the decay chamber volume provides a tag for the SNO electronics. This paper gives details of the production, transfer, and triggering systems for this source along with a discussion of the source gamma-ray. output and performance. (C) 2001 Elsevier Science B.V. All rights reserved.