Triangular D3h Symmetry in the Rotation-Vibration Spectrum of 12C

11th International Spring Seminar on Nuclear Physics: Shell Model and Nuclear Structure – achievements of the past two decades

Gai, Moshe^1,2

LNS at Avery Point, University of Connecticut, Groton

CT

06340-6097, United States^1

Wright Lab, Dept of Physics, Yale University, New Haven

CT

06520-8124, United States^2

关键词: Bending modes;    Geometrical arrangements;    Geometrical symmetries;    Measurements of;    Rotation vibration;    Rotational band;    Spinning tops;    Triatomic molecules;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/580/1/012043/pdf
DOI  :  10.1088/1742-6596/580/1/012043

来源: IOP

【 摘 要 】

Our recent measurements of new states in12C including the second 2+at 10 MeV and the high spin 5-state at 22.4 MeV allow us to study the Rotation-Vibration spectrum of12C from which evidence for a new (D3h) geometrical symmetry emerges. The data fit very well to the predicted (ground state) rotational band of an oblate equilateral triangular spinning top with a D3h symmetry characterized by the sequence of states: 0+, 2+, 3-, 4±, 5-with almost degenerate 4+and 4-(parity doublet) states. Such a D3h symmetry was observed in triatomic molecules, and it is observed in12C for the first time in nuclear physics. The triatomic like structure in nuclei is reminiscent of the discovery of diatomic α+14C structure in18O. We discuss a classification of other rotation-vibration bands in12C 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 in12C 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 particles composing the Hoyle state at 7.654 MeV in12C.