1. Measurement of Rn-222 dissolved in water at the Sudbury neutrino observatory
- Author
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Blevis, I, Boger, J, Bonvin, E, Cleveland, B, Dai, X, Dalnoki-Veress, F, Doucas, G, Farine, J, Fergani, H, Grant, D, Hahn, R, Hamer, A, Hargrove, C, Heron, H, Jagam, P, Jelley, N, Jillings, C, Knox, AB, Lee, H, Levine, I, Liu, M, Majerus, S, McDonald, A, McFarlane, K, and Mifflin, C
- Abstract
The technique used at the Sudbury Neutrino Observatory (SNO) to measure the concentration of 222Rn in water is described. Water from the SNO detector is passed through a vacuum degasser (in the light water system) or a membrane contact degasser (in the heavy water system) where dissolved gases, including radon, are liberated. The degasser is connected to a vacuum system which collects the radon on a cold trap and removes most other gases, such as water vapor and N2. After roughly 0.5 tonnes of H2O or 6 tonnes of D2O have been sampled, the accumulated radon is transferred to a Lucas cell. The cell is mounted on a photomultiplier tube which detects the α-particles from the decay of 222Rn and its progeny. The overall degassing and concentration efficiency is about 38% and the single-α counting efficiency is approximately 75%. The sensitivity of the radon assay system for D2O is equivalent to ∼ 3 × 10-15 g U/g water. The radon concentration in both the H 2O and D2O is sufficiently low that the rate of background events from U-chain elements is a small fraction of the interaction rate of solar neutrinos by the neutral current reaction. © 2003 Elsevier B.V. All rights reserved.
- Published
- 2016