Voltage noise measurement of the vortex mean free path in superconducting granular tin films

We present the results of simultaneous current-voltage and voltage noise measurements on granular tin films in the region of the superconducting transition. Interpretation of the results in terms of a phase-slip shot noise demonstrates that vortex motion is uniform only over some characteristic length. This effective mean free path increases as the temperature is lowered and is probably dominated by vortex-antivortex recombination. © 1982 The American Physical Society.