![](https://coimages.sciencemuseumgroup.org.uk/282/981/large_thumbnail_1982_1434__0003_.jpg)
Model of a cobalt-60 source
1985
1985
1981
1980
1981
1980
1981
1981
1981
1981
1981
1982
1988-1998
1981
1981
1981
1981-1982
1993
1993
circa 1990
1978-1979
1981
1981
1981
1981
1981
1981
1980
1978-1979
1981
1981
1981
1978-1979
1978-1979