九大タンデム加速器を活用した天体核反応測定の歴史と成果

摘要

4He+~(12)C→~(16)O+γ reaction at Ecm = 0.3 MeV plays a crucial role in nuclear synthesis in stars, but measurement of the total reaction cross section has not been succeeded yet in spite of many experiments in the world for about 45 year. We have been preparing for the measurement for about 20 years using Kyushu University tandem accelerator facility. For this experiment we have developed many original instruments and tools, for example, a windowless He gas target, acceleration-deceleration operation of the tandem accelerator, a long-time chopper for reaction recoils, ΔE-E counter using an ionization chamber. Making many attempts and faults till the final goal is important. We succeeded in the measurement at 1.5 MeV first in the world, and we are now challenging the next measurement at 1.2 MeV.