A spectrometer system employs a gridless Xenon detector having an anode and a cathode supported in spaced relation from the anode devoid of structure intermediate the anode and cathode. Pulses resulting from charge collection due to radiation ionization of the Xenon gas are detected and parametrized by a computation engine through multiple detected pulses. Simultaneous determination of the position and ionization energy allows selective presentation of the data to compensate for various position dependent phenomena.