ABSTRACT
The experimental study of the rare modes of radioactive decay intermediate between α-decay and fission is confronted with several difficulties, among which the main one is the very low branching ratio. Theoretical estimations show a probability lower than 10-10 for the heavy-cluster emission as compared with that for α-particle disintegration. Until now, two techniques have been used for overcoming this difficulty: the magnetic deflection of the α-particles or the plastic detectors which do not record them.
