DELAYED RADIATION-INDUCED CONDUCTIVITY IN NICKEL POLYMETHACRYLATE .2.

Generation and transport of charge carriers in nickel polymethacrylate (NiPMA) in the post-irradiation phase have been investigated by means of DC conductivity as a function of temperature, exposure rate and el ectric field strength. The delayed radiation-induced conductivity due to the temperature-and field-assisted dissociation of electron-holes e xcitation of the chain segment is appropriately described within the f ramework of the one-dimensional Onsager theory of geminate-pair dissoc iation. At high temperatures the conductivity is dominated by the loca l, liquid-like motion of the heterocharges moving in an amorphous or l ocally disordered environment. After a certain radiation dose the tran sition from increasing to decreasing conductivity with increase of exp osure rate is due to the radiation-hardening of the material. It is co ncluded that prolonged irradiation of the material produces new trap-c entres which cause a decrease in conductivity.