Reactions with the double-Borromean nucleusHe8

Abstract

Differential cross-sections for elastic scattering and neutron transfer reactions along with crosssections for fusion in the 8 He+ 65 Cu system are reported at energies above the Coulomb barrier (E lab = 19.9 and 30.6 MeV). The present work demonstrates the feasibility of using inclusive measurements of characteristic in-beam γ rays with low-intensity (∼ 10 5 pps) radioactive ion beams to obtain the residue cross-sections for fusion and neutron transfer. Exclusive measurements of γ rays in coincidence with light charged particles have been used to further characterize the direct reactions induced by this double-Borromean nucleus. Coupled reaction channels calculations are used to illustrate the important role played by the transfer channels and to help in understanding the influence of the structure of 8 He on the reaction mechanism.

Recent developments in fusion and direct reactions with weakly bound nuclei

“…[40]. 120 Sn [46], 206 Pb [47] and 208 Pb [48][49][50]; (iii) 8 He on 65 Cu [51]. We discuss below some results showing the damping of the rainbow maximum for these systems.…”

“…Thus, it has been accomplished in very few situations. The main examples are the experiments on collisions of 6 He projectiles on 209 Bi, performed in Notre Dame [129,[146][147][148], and collisions of the same projectile on 65 Cu and on 197 Au targets [51,149] and on 9 Be [150].…”

“…Very impressive experimental setups were developed at the SPIRAL facility, in GANIL, to perform simultaneous measurements of several processes involving the radioactive 6,8 He nuclei [51,149,157]. Lemasson et al [149] used beams of 8 He with intensities in the [2 − 4] × 10 5 pps range to measure fusion, neutron transfer, direct breakup and elastic scattering cross sections for the 8 He + 197 Au system.…”

Nuclear structure effects on heavy-ion reactions with microscopic theory

“…Experiments have shown that dynamic effects such as low-lying vibrational couplings [3][4][5] and transfer reactions [6][7][8][9][10] strongly affect fusion reactions. Other dynamic effects, such as breakup [11][12][13][14] and rotational couplings [4], have also been seen to play a role.…”

Elastic Scattering of ^{<span class="cmr-7">8</span>}He + ^{<span class="cmr-7">208</span>}Pb at 22 MeV

“…8 He is the lightest skin nucleus and it has the largest neutron-to-proton ratio of the particle-stable nucleus. Only a few scattering data sets at barrier energies are presently available [1,2] and there is still a lack of information concerning collective aspects as characteristic nuclear excitations, coupling between different reaction channels and neutron-core correlations.…”