Difference between stable and exotic nuclei: medium polarization effects

R A Broglia (1, 2, 3) , G Potel (1, 2) , F Barranco (4) , E Vigezzi (2)

1 Dipartimento di Fisica
2 INFN
3 NBI - Niels Bohr Institute [Copenhagen]
4 Departamento de Fisica Aplicada III

The 1 S 0 phase shift is large and positive at low densities (relative momenta), while it vanishes and eventually becomes negative at densities of the order of the saturation nuclear density. The bare N N -potential, parametrized so as to reproduce these phase shifts leads to a sizable Cooper pair binding energy in nuclei along the stability valley. It is a much debated matter whether this value accounts for the " empirical " value of the pairing gap or whether a similarly important contribution arises from the exchange of collective vibrations between Cooper pair partners. In keeping with the fact that two-particle transfer reactions are the specific probe of pairing in nuclei, and that exotic halo nuclei like 11 Li are extremely polarizable (representing, as far as this property is concerned, almost a caricature of stable nuclei), we find that the recently studied reaction, namely 11 Li+p → 9 Li+t, provides, for the first time, direct evidence of phonon mediated pairing in nuclei. Difference between stable and exotic nuclei: medium polarization effects 2

Mots clés: Physical Sciences

R A Broglia, G Potel, F Barranco, E Vigezzi. Difference between stable and exotic nuclei: medium polarization effects. Journal of Physics G: Nuclear and Particle Physics, 2010, 37 (6), pp.64022. ⟨10.1088/0954-3899/37/6/064022⟩. ⟨hal-00600806⟩