Nitration under influence of gamma radiation

It has recently been found by Mint and his co-workers [185] that nitration of benzene occurs when benzene in an aqueous solution of calcium nitrate is irradiated with gamma rays. The yield is up to 45% of nitrobenzene and a certain amount of picric acid is also formed. Mint suggested the formation of the nitronium 

Nitration would proceed as (c) in accordance with the radical mechanism or as (d) assuming an ionic mechanism  

The radical, C6H5, would be formed through the reaction between benzene and OH or H02 radicals. 

It has already been mentioned (p. 5) that indirect methods of introducing a nitro group are used in many cases. 

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