Proton resonance scattering of a shape-coexistence nucleus ¹¹⁸Sn

It is well known that shape coexistence was observed in stable even-even Sn(Z=50) nuclei, and the even-odd neighbouring nucleus may have a hint of the structure. So far, some single-particle like states in ¹¹⁹Sn were observed by measuring (d,p) reaction on ¹¹⁸Sn. Though the isobaric analog resonances corresponding to the low-lying states in ¹¹⁹Sn were already measured for the spectroscopic information on ¹¹⁹Sn, there are some missing resonances expected from (d,p) reaction. It is necessary to measure the excitation function of proton-elastic resonance scattering with the wide energy range to understand the structure of 119Sn. The proton resonance elastic scattering on ¹¹⁸Sn yields the spectroscopic information of the single particle state coupled to the ground state of ¹¹⁸Sn. In addition, the inelastic channels will also tell the fruitful information.

The experiment was carried out at the tandem accelerator facility in Kyushu Univ. An enriched 118Sn target was irradiated by a proton beam while varying the beam energy from 7 to 10 MeV. The reaction channel was identified by the outgoing angle and energy of scattered protons measured by single-sided silicon strip detectors placed at 140-160°_lab. We will present the details of the experimental setup and the preliminary result.