We are developing detector architectures and devices based on the novel carbon nanomaterial graphene, which has been shown to exhibit unusual electrical properties of potential use for next-generation radiation detectors. Of particular interest is the use of this technology to develop novel neutron detectors.To this end, we are studying architectures based on a neutron absorbing converter material in conjunction with a graphene field-effect transistor (GFET). As an intermediate step towards the demonstration of GFET neutron detectors we utilize an alpha source to systematically study the effect of charge deposition on the device response. As an added benefit, this experiment helps us elucidate the important systematics of response to other types of radiation, including the dependence of the magnitude of graphene resistance modulation on the deposited energy and the dependence of device speed on the morphology of energy deposition.