“…A number of experiments seem to indicate, however, that other defects, such as static displacements, may also be effective (Testardi 1977a,b). Moreover, it is not certain if a 'homogeneous' defect model is adequate since there is evidence (Pande 1977) that particle irradiation creates small disordered regions in a less disordered matrix. I n such a situation, the proximity effect has to be taken into account and several sets of careful measurements (see, for example, Viswanathan et a1 1978) actually support the description based on inhomogeneous damage.…”