Deep Underground Laboratory Measurement of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">C</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>13</mml:mn></mml:mrow></mml:mmultiscripts><mml:mo stretchy="false">(</mml:mo><mml:mi>α</mml:mi><mml:mo>,</mml:mo><mml:mi>n</mml:mi><mml:mo stretchy="false">)</mml:mo><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>16</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math> in the Gamow Windows of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>s</mml:mi></mml:mrow></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>i</mml:mi></mml:mrow></mml:math> Processes
B. S. Gao, T. Y. Jiao, Yu-Tian Li, Hong Tao Chen, Weiping Lin, Zhu An, L. H. Ru, Zhi-Chao Zhang, Xiaodong Tang, X. Y. Wang, N. T. Zhang, Xiao Fang, Dehao Xie, Y. H. Fan, Long Ma, X. Zhang, Fan Bai, P. Wang, Yikui Fan, G. Liu, H. X. Huang, Q. Wu, Y. B. Zhu, Jiahui Chai, J. Q. Li, L. T. Sun, S. Wang, Jianbin Cai, Y. Z. Li, J. Su, Hao Zhang, Zhihong Li, Y. J. Li, E. T. Li, C. Chen, Y. P. Shen, Gang Lian, Bing Guo, X. Y. Li, L. Y. Zhang, Jinrong He, Y. D. Sheng, Y. J. Chen, Luo-Huan Wang, L. Zhang, F. Cao, Wei Nan, Weike Nan, Gexing Li, Na Song, Baoqun Cui, L. H. Chen, Roshna Parveen G., Zhicheng Zhang, S. Q. Yan, J. Liao, Y. B. Wang, Sheng Zeng, D. Nan, Q. W. Fan, Ningchun Qi, Wenliang Sun, Xiangbo Guo, P. Zhang, Y. H. Chen, Yong Zhou, Jifang Zhou, Jinjin He, C. S. Shang, M. C. Li, S. Kubono, Weiping Liu, R. J. deBoer, M. Wiescher, M. Pignatari
Abstract
The ^{13}C(α,n)^{16}O reaction is the main neutron source for the slow-neutron-capture process in asymptotic giant branch stars and for the intermediate process. Direct measurements at astrophysical energies in above-ground laboratories are hindered by the extremely small cross sections and vast cosmic-ray-induced background. We performed the first consistent direct measurement in the range of E_{c.m.}=0.24 to 1.9 MeV using the accelerators at the China Jinping Underground Laboratory and Sichuan University. Our measurement covers almost the entire intermediate process Gamow window in which the large uncertainty of the previous experiments has been reduced from 60% down to 15%, eliminates the large systematic uncertainty in the extrapolation arising from the inconsistency of existing datasets, and provides a more reliable reaction rate for the studies of the slow-neutron-capture and intermediate processes along with the first direct determination of the alpha strength for the near-threshold state.