Systematic study of fusion reaction in heavy reaction systems at RIKEN and JAEA

mardi 31 oct. 2017, 10:30 → 12:30 Europe/Paris

Bat 27

Systematic study of fusion reaction in heavy reaction systems at RIKEN and JAEA

 

Taiki Tanaka , RIKEN/Kyushu-univ. for the collaboration

 

When one aims to synthesize unknown superheavy nuclei near the ultimate ”Island of stability”, the optimal incident beam energy is unknown and thus often set near the Coulomb barrier. Therefore it is important to know the real barrier position. However, the predictions of the calculated barrier heights are different from one model to another and experimental data is essential.

In this seminar, I will detail experiments run at RIKEN and JAEA, in order to study the nucleus-nucleus interactions for syntheses of superheavy nuclei. We measured excitation functions for quasielastic scattering of 48Ca and 50Ti on 208Pb, 48Ca on 238U, 22Ne, 26Mg and 48Ca on 248Cm using the gas-filed-type recoil ion separator GARIS [1]. The quasielastic scattering events were separated from background events by using the GARIS and its focal plane detectors. The quasielastic barrier distributions were compared with coupled-channels calculations [2]. The results of the calculations indicate that vibrational and rotational excitations of the colliding nuclei, as well as neutron transfers before the contact, strongly influence the barrier distributions. For reactions 208Pb with the spherical nucleus target reactions, the peaks of the barrier distributions were found to coincide with peaks of 2n evaporation residue cross-sections. On the other hand, for reactions 248Cm and 238U with the deformed nucleus target, the barrier distributions become wider, and the peak of the evaporation residue cross-section coincide with the Coulomb barrier of the side collision.

 

[1] T. Tanaka et al., J. Phys. Soc. Jpn. (to be submitted).

[2] K. Hagino et al., Comput. Phys. Commun. 143 123 (1999).