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Low energy cross section measurement of the 10B(a;n)13N reaction and its impact on neutron production in 1st generation stars



Q Liu, M Febbraro, R.J. deBoer, S. Aguilar, A Boeltzig, Y Chen, M Couder, J Görres, Jamie Weaver, K. T. Macon, M. Wiescher, K. Manukyan, L. Morales, S Pain, W. A. Peters, C. Seymour, G. Seymour, R. Toomey, B. Vande Kolk


Nucleosynthesis in the fi rst generation of massive stars offer a unique setting to explore the creation of the fi rst heavier nuclei in an environment free of impurities from earlier stellar generations. In later generations of massive stars, hydrogen burning occurs predominantly through the CNO cycles, but without the carbon, nitrogen, and oxygen to catalyze the reaction sequence, first stars would have to rely on the ineffcient pp-chains for their energy production. Observations of second and third generation stars show pronounced abundances of carbon and oxygen isotopes, which suggests a rapid conversion of the primordial abundances to heavier elements. While the triplealpha-process primarily facilitates this conversion, there are alternative reaction sequences, such as the 2H(a;y)6Li(a;y)10B(a;n)13N, that may play a signi cant role. To study such alternate reaction pathways for production of carbon and heavier nuclei, a number of new measurements are needed. In this work, new measurements are reported for the 10B(a;n)13N reaction, extending the cross section down to 575 keV incident a-particle energy. The measurements were made using a state-of-the-art deuterated liquid scintillator and a spectrum unfolding technique. An R- matrix analysis was performed in order to facilitate a comparison of the underlying nuclear structure with the reaction measurements. An unexpected upturn is observed in the low energy S-factor that indicates the presence of a new low energy resonance. A revised reaction rate is determined that takes into account the present data as well as other previous measurements from the literature that were previously neglected.
Journal of Physical Chemistry C


10B cross section, neutron stars, astrophysics, neutron depth profiling


Liu, Q. , Febbraro, M. , deBoer, R. , Aguilar, S. , Boeltzig, A. , Chen, Y. , Couder, M. , Gorres, J. , Weaver, J. , Macon, K. , Wiescher, M. , Manukyan, K. , Morales, L. , Pain, S. , Peters, W. , Seymour, C. , Seymour, G. , Toomey, R. and Vande Kolk, B. (2020), Low energy cross section measurement of the 10B(a;n)13N reaction and its impact on neutron production in 1st generation stars, Journal of Physical Chemistry C (Accessed June 8, 2023)
Created February 25, 2020, Updated March 1, 2023