Fusion of halo nucleus $^{6}He$ on $^{238}U$: evidence for tennis-ball (bubble) structure of the core of the halo (even the giant-halo) nucleus

Abstract

In a decade-and-a-half old experiment, Raabe et al.(Nature 431 (2004) 823), had studied fusion of an incoming beam of halo nucleus $^{6}He$ with the target nucleus $^{238}U$. We extract a new interpretation of the experiment, different from the one that has been inferred so far. We show that their experiment is actually able to discriminate between the structures of the target nucleus (behaving as standard nucleus with density distribution described with canonical RMS radius r = $r_0 A^{\frac{1}{3}}$ with $r_0$ = 1.2 fm), and the {\bf "core"} of the halo nucleus, which surprisingly, does not follow the standard density distribution with the above RMS radius. In fact the core has the structure of a tennis-ball (bubble) like nucleus, with a "hole" at the centre of the density distribution. This novel interpretation of the fusion experiment provides an unambigous support to an almost two decades old model (Abbas, Mod. Phys. Lett. A 16 (2001) 755), of the halo nuclei. This Quantum Chromodyanamics based model, succeeds in identifyng all known halo nuclei and makes clear-cut and unique predictions for new and heavier halo nuclei. This model supports the existence of tennis-ball (bubble) like core, of even the giant-neutron halo nuclei. This should prove beneficial to the experimentalists, to go forward more confidently, in their study of exotic nuclei.