Irradiation-induced ordering of a disordered suspension of superheated microspheres

The “hot border model” of a suspension of Type-I metastable superconducting grains under irradiation is modified to incorporate heating considerations, and results in the existence of two borders h1 and h2 defined by the minimum and maximum grain volumes of the suspension, respectively. Following a sufficiently long irradiation, the true “hot border”, i.e. the region of the (T, H) phase space in which no superconducting grains exist, should lie only a distance h2⪡h1 below the phase line: between the two borders, the superconducting grain population is only depleted, and ordered according to decreasing size with increasing distance from the phase line. We provide a partial experimental confirmation of this, and discuss how this modification results in an intrinsic energy calibration for device spectroscopy.