Core momentum distribution in two-neutron halo nuclei

L.A Souza,Lauro Tomio,M.T Yamashita,T Frederico,F.F Bellotti

doi:10.1016/j.physletb.2016.03.087

Abstract

The core momentum distribution of a weakly-bound neutron-neutron-core exotic nucleus is computed within a renormalized zero-range three-body model, with interactions in the s-wave channel. The halo wave-function in momentum space is obtained by using as inputs the two-body scattering lengths and the two-neutron separation energy. The core momentum densities are computed for $^{11}$Li, $^{14}$Be $^{20}$C and $^{22}$C. The model describes the experimental data for $^{11}$Li, $^{14}$Be and to some extend $^{20}$C. The recoil momentum distribution of the $^{20}$C from the breakup of $^{22}$C nucleus is computed for different two-neutron separation energies, and from the comparison with recent experimental data the two-neutron separation energy is estimated in the range $100\lesssim S_{2n}\lesssim 400$ KeV. The recoil momentum distribution depends weakly on the neutron-$^{20}$C scattering length, while the matter radius is strongly sensitive to it. The expected universality of the momentum distribution width is verified by also considering excited states for the system.

Highlights

The core recoil momentum distribution of radioactive two-neutron halo nuclei close to the drip line, extracted from breakup reactions at few hundredsPreprint submitted to ElsevierMeV/A, are expected to be quite useful in order to get insights on the underlying neutron-neutron-core structure of these exotic nuclei [1,2]
We start by showing results for Enn = Enc = 0, in order to study the limit-cycle for the core momentum distribution in the context of the two-neutron halo nuclei
For A → 0, the momentum distribution tends be concentrated at small momentum as one can check that the relevant contribution to the integral equation for the spectator function comes from small momentum and σ → 0

Summary

Introduction

The core recoil momentum distribution of radioactive two-neutron halo nuclei close to the drip line, extracted from breakup reactions at few hundreds. For the analysis of the core momentum distribution, we consider data for 11Li [1], 14Be [8] and 20C [9] as the low-energy parameters, which are the inputs of our renormalized zero-range model This procedure allows us to verify the utility of such “bare” formula (1), which does not include distortion effects from the scattering, to analyse the actual breakup data for those systems, taken at few-hundred MeV/A. The constraints in the parameters associated with the 22C halo structure and two-neutron separation energy provided by the scaling formula for the width of the core recoil momentum distribution are discussed on the basis that corresponding data, fitted to three-body model calculations.

Model formalism

Results and discussion

Conclusions