6Heinteraction with protons

Abstract

Experimental data for 6 Heϩ 1 H elastic scattering and the two-neutron transfer reaction, measured recently at the Joint Institute for Nuclear Research in Dubna, Russia, were analyzed by coupled channels calculations using a dineutron model of 6 He. The results of the analysis reveal that all the processes induced by 6 He on a hydrogen target are coupled. This analysis shows that the couplings to the 6 He→␣ϩ2n breakup channels can be included in a simple optical model calculation by means of a polarization potential that is repulsive and whose strength is about 25% of the single-folding potential. Predictions for the pϩ 6 He inelastic scattering to the 2 ϩ resonance are made. A good description of the two-neutron transfer reaction data is obtained when the triton transfer process is coherently added to the dineutron transfer. The spectroscopic amplitude of the tϩt component of the 6 He ground-state wave function is found to have the opposite sign to that of ␣ϩ2n with a magnitude close to that predicted by a microscopic four-cluster model of 6 He.

Investigation ofHe6cluster structures

“…These new data allow to better determine the nuclear interaction potential 6 He + p, which is an essential ingredient for the analysis of the transfer reaction, since it is necessary for the entrance channel in the DWBA calculation. Previous results obtained on 6 He + p elastic scattering in the same energy range have shown that the nucleon-nucleus optical models potentials used for stable nuclei have to be modified in the case of loosely bound nuclei such as 6 He [12,23]. Coupling to the continuum and to the resonant states are expected to play a significant role since the scattering states are much closer to the continuum states than in stable nuclei.…”

“…This approach previously used by Rusek et al [12,25] assumes a two body cluster model α+2n for the 6 He nucleus with the spin of the 2n cluster set to s=0. The wave functions Ψ 0 (r ) and Ψ 2 (r ) describing the relative motion of the two clusters in the 6 He ground state and the 6 He(2 + ) resonant state were calculated in potential wells whose depths were varied to reproduce respectively the binding energy of 0.975 MeV and the excitation energy of 1.8 MeV.…”

“…[34] and the remnant potential V α−p was determined in the previous section. All the potentials and the spectroscopic amplitudes used in the calculation are listed in Table I and II. Special care was taken in the choice of the potential for the α+t exit channel and several potentials were considered [10,12,13,34,35,36]. To obtain the α+t potential, we used α+ 3 He elastic scattering data at E c.m.…”

“…Next, we used the potential B obtained in Ref. [12] fitted on the complete differential cross section of the 3 He( 4 He, 4 He) 3 He elastic scattering. This fit on the α+ 3 He data corresponds to the solid line on Fig.…”

“…The DWBA analysis done by Wolski et al suggests a spectroscopic factor S t−t of 0.42. Rusek et al also conclude to a small spectroscopic factor S t−t equal to 0.25 [12]. The extreme case is the analysis of Oganessian et al, which described the data in a fourbody three dimensional DWBA approach without any t +t clustering [13].…”