Nuclear structure effects in quasifission – understanding the formation of the heaviest elements

D J Hinde,K J Cook,G Mohanto,M Dasgupta,E C Simpson,K Vo-Phuoc,I P Carter,C Simenel,D Y Jeung,C S Palshetkar,E Williams,E Prasad,A Wakhle,D C Rafferty,D H Luong,M.W Reed,A.J Mitchell,E.C Simpson

doi:10.1051/epjconf/201612303005

D J Hinde, K J Cook + Show 16 more

Open Access

https://doi.org/10.1051/epjconf/201612303005

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Journal: EPJ web of conferences	Publication Date: Jan 1, 2016
Citations: 2	License type: cc-by

Affiliation: Australian National University

Abstract

Quasifission is an important process suppressing the fusion of two heavy nuclei in reactions used to create superheavy elements. Quasifission results in rapid separation of the dinuclear system initially formed at contact. Achieving reliable a priori prediction of quasifission probabilities is a very diffcult problem. Through measurements with projectiles from C to Ni, the Australian National University’s Heavy Ion Accelerator Facility and CUBE spectrometer have been used to map out mass-angle distributions (MAD) - the fission mass-ratio as a function of centre-of-mass angle. These provide information on quasifission dynamics in the least modeldependent way. Average quasifission time-scales have been extracted, and compared with TDHF calculations of the collisions, with good agreement being found. With the baseline information from the survey of experimental MAD, strong influences of the nuclear structure of the projectile and target nuclei can be clearly determined.

Highlights

Fusion of two heavy nuclei has been a successful pathway to produce new very heavy and superheavy elements (SHE)
This dynamical non-equilibrium process results when the combined system formed after capture separates before a compact compound nucleus is formed, resulting in two fragments
The months of beamtime needed to determine if a given reaction is likely to be successful or not gives additional motivation to obtain a reliable predictive model based on an full understanding of this competition

Summary

Introduction

Fusion of two heavy nuclei has been a successful pathway to produce new very heavy and superheavy elements (SHE). It has been found that the quasifission probability and MAD characteristics can depend strongly on the nuclear structure of the two colliding nuclei. Collisions of spherical magic nuclei at sub-barrier energies can result in enhancement of heavy element yields [8, 9] and fission distributions characteristic of fusion-fission [10, 11].

Results

Conclusion