Abstract:
A substantially immobile ''''non-shifting'''' relatively low energy radiation source includes a particulate radioisotope bearing material positioned within a chamber formed in a capsule. Movement of the radioactive isotope element or any attenuating mass is prevented by a porous deformable conformational barrier member which has pores therein smaller than the smallest particle adjacent to the barrier and which prevents any attenuating producing movement of any particulate material within the capsule. In the case of gas producing radioisotopes, provision is made to permit escape of gas while preventing movement of attenuating masses or radioactive isotope material. Various radioisotopes and barrier members are described as well as various ways to assemble a ''''non-shifting'''' source.