Formation of ion-beam images in gelatine and various polymers

Abstract

It has recently been reported by Najz̆er, Humar and Ilić (1982) that the pure gelatine can be used for producing relief images of high-fluence ion-beams after a treatment in water at room temperature for few minutes. The new method is proposed for high-resolution microradiography of boron in metals via 10B(n,α) 7Li reaction. In our present work studies are performed to understand the phenomenon observed. We have simulated the image formation by accelerated electron, proton and alpha-particle beams at different fluences. A narrow fluence region is found in which a highly enhanced dissolution rate of the irradiated gelatine is induced. We assume that when the fluence exceeds a critical value (tipically 10 12–10 13 ions·cm -2) the damage zones of individual tracks cover almost completely the irradiated area, transforming the irradiated layer into a huge damage zone. In this case the effective diameter of damage zone around a single track has to be d eff= =φ c -1 2 ≅(3–10) nm . We have found that the ion-induced image formation phenomenon observed in gelatine is a more general one and the method may be extended to almost all the etch-track and non-etch-track forming polymers and perhaps to insulating silicates. For example high-resolution α- microradiographs have been obtained with CR-39, CN-85, PC and PET sheets and even with hydrate-cellulose known as a non-track-forming material.