James Kurfess - Gambrills MD,
Richard Kroeger - Bowie MD,
W. Johnson - Alexandria VA,
Bernard Phlips - Accokeek MD,
250/370130, 250/370090, 250/385100
A device for determining the photon energy Eand direction cone angle of incident gamma ray includes a radiation detector for receiving an incident gamma ray having an unknown photon energy Eand an unknown direction and for scattering the gamma ray with two Compton scattering interactions and a subsequent scattering or absorption interaction. The detector provides three outputs, each output corresponding to one of the Compton scattering and the subsequent scattering or absorption interactions, to a processor, which is programmed to calculate the photon energy Eand direction cone angle of the incident gamma ray based on these outputs. The detector configuration, for example one that includes multiple detector layers, provides an accurate determination of both the position and energy of the incident gamma ray, while the calculation of the photon energy Eand direction cone angle of the incident gamma ray does not require absorption and measurement of the entire or substantially all the energy Ein the detector.