RADIOCHEMICAL STUDIES OF COMPLEX PARTICLE-EMISSION IN LOW AND INTERMEDIATE-ENERGY REACTIONS

The probability of complex particle emission in low and intermediate e nergy nuclear reactions (E less than or equal to 70 MeV) is generally small. The data are of significance from the fundamental point of view as well as for applications. Radiochemical and other interdisciplinar y techniques like mass spectrometry and accelerator mass spectrometry play an important role in the study of these low-yield processes. To i nterpret the experimentally obtained integral data, comparisons are do ne with results of nuclear model calculations, based mainly on the sta tistical model. This paper briefly reviews the experimental and theore tical information available on each process. Several systematic correl ations were developed which contribute to some mechanistic understandi ng and also allow a prediction of unknown data. Most extensive studies have been performed on He-4-emission. In general, the compound and pr ecompound models together adequately describe the He-4-emission cross section; occasinally direct interactions need to be included. The H-2- emission, on the other hand, appears to entail a strong contribution f rom direct processes. Radiochemical methods have contributed appreciab ly to the study of trinucleon emission reactions. Whereas in the case of H-3-emission both compound and direct processes play an important r ole, the He-3-emission appears to be dominated by direct interactions. The emission of heavier particles like Be-7 has been relatively littl e investigated. With the exception of H-2 and He-4 emissions, it appea rs that the higher the charge of the emitted complex particle, the low er is its emission probability.