An experiment on the study of the ²⁴⁶Fm spontaneous fission has been conducted using the SHELS separator of the Flerov Laboratory of Nuclear Reactions. The isotope has been synthesised in the complete fusion reaction of ⁴⁰Ar beam ions and ²⁰⁸Pb target nuclei.

The neutron yields data of ²⁴⁶Fm spontaneous fission (ν = 3.79 ± 0.30, σ²_ν = 2.1) have been obtained using the SFiNx detector system. The multiplicity distribution of emitted prompt neutrons has been restored using the Tikhonov method of statistical regularisation (ν_r = 3,79 ± 0,20, σ²_νr= 2,8). The spontaneous fission branching ratio (b_SF = 0,061 ± 0,005) and the half-life (T_1/2 = 1,50 ^+0,08_-0,07 с) of the isotope have been determined as well.

The experimental data have been compared with scission point model predictions. Excellent convergence has been observed in the average number of neutrons per spontaneous fission process. However, the forms of the experimental and model prompt neutron multiplicity distributions differ significantly.

The obtained results have been presented in a recently published preprint of the JINR Publishing Department authored by Andrey Isaev, a FLNR junior researcher, and his colleagues. The results have also been published in the European Physical Journal A.

The scientific paper received the grant support from the Russian Foundation for Basic Research and the Joint Institute for Nuclear Research. One of the co-authors (T. M. Shneidman) has also been supported by Kazan Federal University.

Photograph of the SFiNx detector system at the focal plane of the SHELS