Rotational character of the 12C spectrum investigated through inelastic cross sections via photon emission.

In this work the bremsstrahlung and photon dissociation cross sections for transitions between 0⁺, 2⁺, and 4⁺ states in ¹²C are computed. The nucleus is described within the three-alpha model, and the wave functions are computed by means of the hyperspherical adiabatic expansion method. The continuum states are discretized by imposing a box boundary condition. The transition strengths are obtained from the cross sections, and compared to schematic rotational model predictions. The computed results strongly suggest that the two lowest bands are made, respectively, by the states with angular momentum and parity {0⁺₁ , 2⁺₁ , 4⁺₂ } and {0⁺₂ , 2⁺₂ , 4⁺₁ }. The transitions between the states in the first band are consistent with the rotational pattern corresponding to three alphas in an equilateral triangular structure. For the second band, the transitions are also consistent with a rotational pattern, but with the three alphas in an aligned distribution. [ABSTRACT FROM AUTHOR]