THE TOTAL BETA ACTIVITY OF NEW ZEALAND RAINWATER, SEPTEMBER 1956-JUNE 1959
The total beta activity of ralnwater collected monthly at one New Zealand site from September 1956, and from five more sites from june 1957 through June 1959, was measured and the decay curves plotted. An attempt was made to age the samples assuming the decrease in activity with time was caused by fission product decay. Deposition of radioactivity was found to be approximately proportional to ralnfall but there was a latitude effect which showed as lower activities further from the equator. Waves of fresh activity were identified and an attempt made to associate them with nuclear test series. In late 1956 fresh activity from U.K. tests in Australia was possibly followed by a wave of debris in early 1957 which was of USSR origin. The main deposition in the second half of 1957 was from the UK Grapple series at Christmas Island although this was overshadowed in September/October by short lived activity from the UK Antler series in Australia. Activity from a further UK Pacific test was detected in early 1958, but the latter half was caused by extended US and UK Pacific tests which cannot be separately identified. It is possible that a fresh wave in the second quarter of 1959 is from the Russian October 1958 series. It is possible that troposphere debris from USSR Megaton explosions, as well as from Pacific equatorial tests has arrived within two months. By a stratospheric path, megaton equatorial debris may be deposited in New Zealand 2 to 4 months after the explosion and USSR Northern Hemisphere debris in 5 to 7 months. The November 1958 USSR explosions probably contributed a maximum of 7% of the Sr-90 deposited in February/May 1959 at Lower Hutt (41 deg S). (auth)
- Research Organization:
- New Zealand. Dept. of Scientific and Industrial Research. Div. of Nuclear Sciences, Lower Hutt
- NSA Number:
- NSA-16-000396
- OSTI ID:
- 4836748
- Report Number(s):
- NS-R-12
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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