VAMOS identification performance for fission fragments produced through transfer and fusion reactions in inverse-kinematics in the Thorium region

Using the inverse-kinematics technique and multi-nucleon transfer reactions, the fission process is studied at GANIL with the VAMOS++ spectrometer. This enables the isotopic identification of complete fission fragment distributions. Moreover, the coupling of this spectrometer to a highly stripped silicon detector (PISTA) allows the identification of the fissioning system and the reconstruction of its excitation energy with high resolution.

A new experiment was conducted at VAMOS++ with the newly accelerated 232Th beam at Coulomb energies. Transfer and fusion reactions performed with a 12C target permitted to populate fissioning systems from 230Th up to 244Cm. The produced nuclei lay on a region closer to the known transition between asymmetric to symmetric fission in the actinides. This allows the systematic study of the shell-closure effects occurring for different deformation parameters, like octupole deformation, recently proposed to be responsible for the asymmetric fission in the actinides region . Moreover, experimental results show that the isotopic distributions around Th isotopes deviate from the general actinide behaviour.