Silicon irradiations at the Harwell Laboratory of the United Kingdom Atomic Energy Authority

Silicon irradiations have been carried out at Harwell since 1975 in both DIDO and PLUTO. This paper describes the irradiation facilities and how conditions have been improved to give the best possible results for neutron transmutation doping. A neutron dose/resistivity relationship has been developed, whose validity has been demonstrated by the accuracy of the post-irradiation resistivity. The quality control system which makes available data for any particular silicon crystal before, during and after its irradiation is also discussed. Finally the paper describes health physics system which ensures that the silicon is returned to the customers' manufacturing environment with residual radio-activity value lower than that defined in the regulations for exempt material. (author). 7 refs, 13 figs, 1 tab