Direct measurement of the ⁴He(¹²C,¹⁶ O)γ cross section in inverse kinematics

A cross section measurement employing a direct ¹⁶O detection method for the reaction energies from E_cm = 2.4 to 0.7 MeV is planned at Kyushu University Tandem Laboratory (KUTL). To perform this experiment and to obtain quantitative information about the cross section to within an error of 10%, we have developed several instruments, including a blow-in type windowless gas target and an ionization chamber. A target thickness of 24×3.9 Torrcm was achieved using the developed gas target. The particle identification was successfully performed by using the energy deposit in the ionization chamber. Experiments were performed at E_cm = 2.4 and 1.5 MeV using the developed instruments and the cross sections were obtained. A hybrid detector employing both an ionization chamber and a Si-SSD detector was developed to reduce the carbon backgrounds more efficiently. It was found that the new detector could reduce the background ratio by three orders, and the experiments in E_cm < 1.2 MeV were ready for carrying out.