Pulse filtering techniques for mercuric iodide gamma ray detectors

The performance of mercuric iodide gamma ray detectors is limited by hole transport properties. Pulse filtering techniques have been developed to circumvent the poor hole collection efficiency and long collection times. Using pulse filtering techniques which compensate for incomplete hole collection, improvements in energy resolution by as much as a factor of 2 has been achieved with detectors of 1-5 mm thickness. For the thickest detectors (≅ 1 cm), electron-only measurement techniques have recently demonstrated significant improvement over standard pulse shaping. A summary of computer and analog techniques which correct pulse amplitudes for incomplete hole collection is presented and a new technique for centimeter-thick detectors is described. Spectral results are presented and the implementation and limitations of the different methods are discussed. (orig.)