[en] This paper presents the response of an hydrogenated amorphous silicon thin film p-i-n diode to protons as a function of the applied bias. A typical pulse shape is also presented. These data are understood on the basis of a model whose main features are fast (<5 nsec) electron collection and slow (few μsec) hole collection due to multiple trapping transport through the shallow gap states. The overall charge normalization yields a means pair creation energy εp of 3.4 - .4 eV, comparable to 3.63 eV in crystalline Silicon despite the large 1.7 eV gap. To understand this result, a microscopic Monte Carlo calculation, taking into account the actual density of states in a-Si:H, is used to study the energy sharing between ionization and phonon production during hot carrier thermalization. This simulation yields a value of 4.3 eV for εp