First Direct Measurement of 12C (12C,n )23Mg at Stellar Energies

Bucher, B. and Tang, X. D. and Fang, X. and Heger, A. and Almaraz-Calderon, S. and Alongi, A. and Ayangeakaa, A. D. and Beard, M. and Best, A. and Browne, J. and Cahillane, C. and Couder, M. and deBoer, R. J. and Kontos, A. and Lamm, L. and Li, Y. J. and Long, A. and Lu, W. and Lyons, S. and Notani, M. and Patel, D. and Paul, N. and Pignatari, Marco and Roberts, A. and Robertson, D. and Smith, K. and Stech, E. and Talwar, R. and Tan, W. P. and Wiescher, M. (2015) First Direct Measurement of 12C (12C,n )23Mg at Stellar Energies. PHYSICAL REVIEW LETTERS, 114 (25). ISSN 0031-9007

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Abstract

Neutrons produced by the carbon fusion reaction 12C(12C,n)23Mg play an important role in stellar nucleosynthesis. However, past studies have shown large discrepancies between experimental data and theory, leading to an uncertain cross section extrapolation at astrophysical energies. We present the first direct measurement that extends deep into the astrophysical energy range along with a new and improved extrapolation technique based on experimental data from the mirror reaction 12C(12C,p)23Na. The new reaction rate has been determined with a well-defined uncertainty that exceeds the precision required by astrophysics models. Using our constrained rate, we find that 12C(12C,n)23Mg is crucial to the production of Na and Al in Pop-III Pair Instability Supernovae. It also plays a non-negligible role in the production of weak s-process elements as well as in the production of the important galactic γ-emitter 60Fe.

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