Study of deformed structure in mass 40 region using CAGRA gamma-ray spectrometer*

In mass 40 region of atomic nuclei, onset of various structures, such as superdeformation, shape co-existence, cluster structure, etc., is expected. In order to clarify such structure, we are pursuing a systematic study of high-spin states by in-beam gamma-ray spectroscopy. In the previous studies, superdeformed rotational band was observed at ^36,40Ar, ⁴⁰Ca, and ⁴⁴Ti. Among them, it is not yet well understood at ⁴⁴Ti and high-spin states are known up to 12⁺ level. To understand the deformed structure of ⁴⁴Ti and also neighboring isotopes, we performed gamma-ray spectroscopy using ²⁴Mg+²⁴Mg reaction.

  Experiment was performed at cyclotron facility in RCNP, Osaka University. A 104MeV ²⁴Mg beam was irradiated on the ²⁴Mg target of 0.5mg/cm² thickness. Gamma rays and charged particles were measured by CAGRA gamma-ray spectrometer and Si-Ball charged particle filter, respectively. CAGRA is an array of 16 Clover type Ge detectors with BGO Compton suppression shield, constructed by international collaboration between Japan, the US and China.

  Recent analysis results on high-spin states of mass 40 region will be presented.