Associated particle imaging

Abstract

An associated particle imaging (API) system has been built. API is a three-dimensional imaging technique using fast neutrons. API uses the direction and time correlation between the 14 MeV neutron and the associated alpha particle produced by the T(d,n)/sup 4/He reaction in a small accelerator or sealed-tube neutron generator (STNG). Detection of the alpha particle with a position-sensitive detector provides direction and time of emission of the neutron. The neutron may then interact with the target nucleus to produce a gamma-ray whose energy is characteristic of the target material. The time of detection of the gamma ray is used to locate the neutron-nucleus interaction and, hence, the target material, while the measurement of gamma-ray energy identifies the elemental composition of the target. A STNG tube with a focused beam and position-sensitive alpha detector has been produced and incorporated in an API system. Preliminary images which have been recorded show clearly the objects being imaged. Analysis of the data reveals elemental information for two real objects and one phantom caused by shielding required for radiological safety reasons. >