Si detector cryotrap for single atom radon detection
The ultra low levels of {sup 232}Th and {sup 238}U in the D{sub 2}O of the Sudbury Neutrino Observatory will be monitored by extracting radium on MnO{sub 2} filters and {alpha}-counting the daughters, {sup 220}Rn (t{sub 1/2} = 55.6 s; {sup 232}Th chain) and {sup 222}Rn (t{sub 1/2}= 3.8 d; {sup 238}U chain), emanating from these filters. A 1 cm{sup 3} vacuum cryocell, with 50% wall coverage by a pair of bare Si PIN photodiodes, efficiently traps and {alpha}-counts single atoms of radon and its daughters. Energy resolution and time correlation are used to identify the different isotopes. The cell is essentially background free and has a projected sensitivity of the equivalent of 10{sup -15} g of Th and U per g of D{sub 2}O. Progress in the development of the cryocell as well as associated D{sub 2}O radioactivity monitoring system components will be reported.
- OSTI ID:
- 387226
- Report Number(s):
- CONF-931044-; ISSN 0003-0503; TRN: 96:027172
- Journal Information:
- Bulletin of the American Physical Society, Vol. 38, Issue 9; Conference: Fall meeting of the Division of Nuclear Physics of the American Physical Society, Pacific Grove, CA (United States), 20-23 Oct 1993; Other Information: PBD: Oct 1993
- Country of Publication:
- United States
- Language:
- English
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