Evidence for strong refraction ofHe3in an α-particle condensate

Abstract

We have analyzed 3 He scattering from 12 C at 34.7 and 72 MeV in a coupled channel method with a double folding potential derived from the precise wave functions for the ground 0 + state and 0 + 2 (7.65 MeV) Hoyle state, which has been suggested to be an α particle condensate. It is found that strong refraction of 3 He in the Hoyle state can be clearly seen in the experimental angular distribution at low incident energy region as an Airy minimum of the pre-rainbow oscillations.

Evidence of enhanced threeαradius inα+12C inelastic scattering

“…The MCC calculations employing the long-range 3α folding interaction have been applied to the α+ 12 C [7] and 3 He+ 12 C [8,9] systems, and the calculation nicely reproduces the angular distributions of various exit channels. In the differential cross section for the 0 + 2 channel, a scattering angle for the first Airy minimum is shifted to the larger angle region, and the number of the Airly minima increases in a comparison to other inelastic channels, going to the rotational and vibrational states such as the 2 + 1 and 3 − 1 states.…”

“…In the inelastic scattering of light ions by 12 C, which excites the 12 C(0 + 2 ) state in a final state, an oscillating pattern in the differential cross section of the scattered ion is discussed in connection to the enhanced radius of the final 0 + 2 ⋆ e-mail: itomk@kansai-u.ac.jp state with the 3α structure [5][6][7][8][9]. However, the relation of the extended radius and the oscillating pattern of the cross section of the 12 C inelastic scattering still remains unclear [10,11].…”

“…In the coupled-channel approaches [7][8][9], for example, nuclear interactions for the system of the 12 C target plus a projectile are constructed from the double folding model, which employs the internal wave function of 12 C, obtained from the 3α resonating group method (3αRGM) [2] and from an effective density-dependent nucleon-nucleon interaction. This coupled-channel calculation is called microscopic coupled-channels (MCC) [14].…”

“…In the differential cross section for the 0 + 2 channel, a scattering angle for the first Airy minimum is shifted to the larger angle region, and the number of the Airly minima increases in a comparison to other inelastic channels, going to the rotational and vibrational states such as the 2 + 1 and 3 − 1 states. From this result, the authors have claimed that the evolution of the Airy structure originated from the spatial extension of the nuclear interaction in the final 0 + 2 channel [7][8][9].…”

“…By employing the MCC calculation, which is the same method as in Refs. [7][8][9], the authors have clearly demonstrated that the Airy structure in the angular distribution is dominated by not the size of the 0 + 2 state, but by a spatial distribution of the coupling potential for the 0 + 1 → 0 + 2 transition. There is another problem in the relation of the monopole 0 + 1 → 0 + 2 transition and the spatial size of the final 0 + 2 state.…”