We report a measurement of a new high spin J π = 5 − state at 22.4(0.2) MeV in 12 C which fits very well to the predicted (ground state) rotational band of an oblate equilateral triangular spinning top with a D 3h symmetry characterized by the sequence 0 + , 2 + , 3 − , 4 ± , 5 − with almost degenerate 4 + and 4 − (parity doublet) states. Such a D 3h symmetry was observed in triatomic molecules and it is observed here for the first time in nuclear physics. We discuss a classification of other rotation-vibration bands in 12 C such as the (0 + ) Hoyle band and the (1 − ) bending mode band and suggest measurements in search of the predicted ("missing") states that may shed new light on clustering in 12 C and light nuclei. In particular the observation (or non-observation) of the predicted ("missing") states in the Hoyle band will allow us to conclude the geometrical arrangement of the three alpha-particle composing the Hoyle state at 7.654 MeV in 12 C.

26 Mg(α, α ) 26 Mg reaction -probing astrophysically important states in 26 Mg. 26 Mg reactions. The strengths of these reactions as functions of temperature are one of the major uncertainties in the s-process.

Background: Aspects of the nuclear structure of light α-conjugate nuclei have long been associated with nuclear clustering based on α particles and heavier α-conjugate systems such as 12 C and 16 O. Such structures are associated with strong deformation corresponding to superdeformed or even hyperdeformed bands. Superdeformed bands have been identified in 40 Ca and neighboring nuclei and find good description within shell model, mean-field, and α-cluster models. The utility of the α-cluster description may be probed further by extending such studies to more challenging cases comprising lighter α-conjugate nuclei such as 24 Mg, 28 Si, and 32 S. Purpose: The purpose of this study is to look for the number and energy of isoscalar 0 + states in 28 Si. These states are the potential bandheads for superdeformed bands in 28 Si corresponding to the exotic structures of 28 Si. Of particular interest is locating the 0 + bandhead of the previously identified superdeformed band in 28 Si. Methods: α-particle inelastic scattering from a nat Si target at very forward angles including 0• has been performed at the iThemba Laboratory for Accelerator-Based Sciences in South Africa. Scattered particles corresponding to the excitation energy region of 6 to 14 MeV were momentum-analysed in the K600 magnetic spectrometer and detected at the focal plane using two multiwire drift chambers and two plastic scintillators. Results: Several 0 + states have been identified above 9 MeV in 28 Si. A newly identified 9.71 MeV 0 + state is a strong candidate for the bandhead of the previously discussed superdeformed band. The multichannel dynamical symmetry of the semimicroscopic algebraic model predicts the spectrum of the excited 0 + states. The theoretical prediction is in good agreement with the experimental finding, supporting the assignment of the 9.71-MeV state as the bandhead of a superdeformed band. Conclusion: Excited isoscalar 0+ states in 28 Si have been identified. The number of states observed in the present experiment shows good agreement with the prediction of the multichannel dynamical symmetry.