Destruction of the metastable state of a type I superconducting granule by an external irradiation

We present a dynamic study of the normal state thermal nucleation of a 2 03BC-radius In granule, initially in an equilibrium metastable state in the presence of a magnetic field. The driving mechanism is the neutrino-indium collision which is assumed to provide a local energy deposition. An analytic expression for the quasiparticle and phonon temperatures Te ( r, t ) and Tp ( r, t ) characterizing the electron-phonon system is obtained for a central energy deposition. It is shown that both Te and Tp undergo large deviations everywhere in the grain for times up to 10-10 s; Tp remains non-uniform in the grain for a larger time than Te. At the grain surface, the quasiparticle temperature is seen to be a nonmonotonic function of time, even under the assumption of no energy loss towards the embedding paraffin. The superheating critical field is determined from the calculations of the surface energy barrier and the thermal nucleation is discussed. J. Physique 47 (1986) 1939-1949 NOVEMBRE 1986, Classification Physics Abstracts 74.55-74.90-65.90