Measurement of the C(,)O reaction at TRIAC

Makii, Hiroyuki   ; Miyatake, Hiroari*; Wakabayashi, Yasuo; Ishiyama, Hironobu*; Niki, Kazuaki*; Okada, Masashi*; Imai, Nobuaki*; Watanabe, Yutaka*; Hirayama, Yoshikazu*; Jeong, S. C.*; Shima, Tatsushi*; Nishinaka, Ichiro; Mitsuoka, Shinichi; Nishio, Katsuhisa   ; Chiba, Satoshi

The C(,)O reaction plays an important role in stellar evolution at the stage of helium-burning. Its reaction rate determines the mass fraction of C and O, the abundance distribution of the elements between oxygen and iron, and the iron-core mass before the super-nova explosion. However, the cross section at low energy still has a large uncertainty mainly due to the poor determination of the ratio of E2 cross section to E1 one. In order to provide a stringent constraint to extrapolation down to stellar temperature, additional data is crucial. Hence we designed new measurement at TRIAC (Tokai Radioactive Ion Accelerator Complex). With use of the 18 GHz ECR (electron cyclotron resonance) ion source set upstream of the TRIAC accelerators, TRIAC has a possibility to deliver intense -beams. By using the pulsed alpha-beams provide by TRIAC, the high efficiency anti-Compton NaI(Tl) spectrometers, and enriched carbon targets (99.99 % enrichment in C), we measured the -ray spectrum of the C(,)O reaction near the resonance at a center of mass energy of 2.4 MeV. In this contribution, we will discuss obtained E1 and E2 cross sections of the reaction.