Angular Distribution of Particle Accompanied ²⁵²Cf Fission:

Figure 2: Polar diagram of -particle energy versus the emission angle with respect to the light fission fragment, for ²⁵²Cf.

Most of the ternary particles are emitted about perpendicular to the fission axis; hence they are not evaporated from the accelerated fragments. Fig. 2 displays the double differential yield and the corresponding single angular spectrum [Mut93]. Both figures exhibit besides of the dominant equatorial -particles also the small fraction of predominantly higher energetic polar -particles being emitted along the fission axis and under small angles with respect to the directions of the light and heavy group of fission fragments. The mean angle and the width of the angular distribution for the different light charged particles (LCP) emitted in a ternary fission process are summarized in table 1. The most probable angle of emission is always determined with respect to the direction of the light (L) fragment. All these data were obtained with lower energy cut-offs which result from the use of absorber foils to prevent the registration of the rare ternary LCP's from interference with the several orders of magnitude more frequent fission fragments or -particles from radioactive decay.

Figure 3: Angular distribution of ternary -particles in spontaneous fission of ²⁵²Cf, as a function of the angle relative to the direction of the light fission fragment.

Table 2: Mean emission angle and angular width of the light charged particles (LCP) emitted in the ternary fission process of ²⁵²Cf. The most probable angle of emission is always determined with respect to the direction of the light (L) fragment. The used energy cut-offs are also given (see text).