Subjects: Physics >> Nuclear Physics submitted time 2024-02-16
Abstract: The basic properties of atomic nuclei including spins, magnetic moments, electric quadrupole moments and charge radii, are sensitive probes to different aspects of exotic nuclear structure, and are also important to investigate the unrevealed nature of interaction between nucleons. Based on multidiscipline, laser spectroscopy is a unique tool to precisely measure the basic nuclear properties mentioned above in a nuclear-model independent way by measuring the hyperfine structure of atoms, ions, or molecules, which has played an important role in the study of exotic nuclear structures across the different regions of the nuclear chart. Basic principles of laser spectroscopy and various types of experimental devices are expounded after the brief history of the hyperfine structure. Furthermore, advantages of utilizing laser spectroscopy in the study of nuclear structure are briefly introduced by taking the radioactive neutron-deficient Pb region as an illustration. In addition, current condition of collinear laser spectroscopy setup has been systematically reviewed, together with the latest progress on collinear resonance ionization spectroscopy offline devices at Peking University. Finally, the developing status and ongoing plan of laser spectroscopy devices for current and future radioactive ion beam facilities in China have been put forward, and the broad prospects of laser spectroscopy in unstable nuclear properties and the fundamental symmetries based on molecular spectroscopy are interpreted.
Subjects: Physics >> Nuclear Physics submitted time 2024-02-06
Abstract: Recently, an inelastic scattering experiment of 16O + 12C was performed at the Beijing Tandem Accelerator Nuclear Physics National of China Institute of Atomic Energy. New evidence for the existence of Bose-Einstein condensation state of 16𝑂 has been obtained. Employing a series of double-sided-silicon-strip-based telescopes, this experiment achieved accurate particle identification and coincidence measurement of 4-𝛼 in the decay of 16O for the first time. Based on this, high-resolution reaction 𝑄-value spectra was obtained and clear 4-𝛼 resonance states were reconstructed. In the vicinity of the 4-𝛼 separation threshold, 4 highly significant (3 of them above 5𝜎) resonance states were observed, which decay to the characteristic pattern of 12C(Hoyle state) + 𝛼, consistent with the predicted Hoyle-BEC structure and its rotating band features. The observation results will promote further theoretical research, and more measurements are needed for these resonance states in experiments.