A measurement system is disclosed which includes a flow chamber configured to propagate a sample in a flow stream, one or more optical sources configured to irradiate the sample in the flow stream, one or more detector systems each configured to receive resultant light from the sample and, in response, generate a photon signal, the one or more detector systems each including one or more photon sensors each adapted to generate an electronic pulse in response to receiving a photon and a circuit operating in the giga hertz supporting the one or more photon sensors thus configured to count each individual photon in the resultant light from the sample.