Cascade modeling in superconductors: Production, registration and implications of branch imbalance potential

The mechanism for creation of electron-hole branch imbalance in superconductors subjected to high-energy particle/radiation bombardment is considered. The physical basis for the production of imbalance lies in the geometrical difference between the densities of states in phase space for electron- and hole-like excitations in metals. The requirement of charge neutrality fails to prevent branch imbalance only in superconductors. Using appropriately modified kinetic equations, numerical solutions for the distribution functions of electron- and hole-excitation branches are obtained under steady state, non-equilibrium conditions. Recent experimental results on the response of Nb to pulsed laser energy deposition are also discussed. An order of magnitude estimate for the case of a 10 keV X-ray quantum detection is made.