Neutron spectroscopy of 26Mg states: Constraining the stellar neutron source 22Ne(α,n)25Mg

• Main Authors: C. Massimi, S. Altstadt, J. Andrzejewski, L. Audouin, M. Barbagallo, V. Bécares, F. Bečvář, F. Belloni, E. Berthoumieux, J. Billowes, S. Bisterzo, D. Bosnar, M. Brugger, M. Calviani, F. Calviño, D. Cano-Ott, C. Carrapiço, D.M. Castelluccio, F. Cerutti, E. Chiaveri, L. Cosentino, M. Chin, G. Clai, N. Colonna, G. Cortés, M.A. Cortés-Giraldo, S. Cristallo, M. Diakaki, C. Domingo-Pardo, I. Duran, R. Dressler, C. Eleftheriadis, A. Ferrari, P. Finocchiaro, K. Fraval, S. Ganesan, A.R. García, G. Giubrone, I.F. Gonçalves, E. González-Romero, E. Griesmayer, C. Guerrero, F. Gunsing, A. Hernández-Prieto, D.G. Jenkins, E. Jericha, Y. Kadi, F. Käppeler, D. Karadimos, N. Kivel, P. Koehler, M. Kokkoris, S. Kopecky, M. Krtička, J. Kroll, C. Lampoudis, C. Langer, E. Leal-Cidoncha, C. Lederer, H. Leeb, L.S. Leong, S. Lo Meo, R. Losito, A. Mallick, A. Manousos, J. Marganiec, T. Martínez, P.F. Mastinu, M. Mastromarco, E. Mendoza, A. Mengoni, P.M. Milazzo, F. Mingrone, M. Mirea, W. Mondelaers, A. Musumarra, C. Paradela, A. Pavlik, J. Perkowski, M. Pignatari, L. Piersanti, A. Plompen, J. Praena, J.M. Quesada, T. Rauscher, R. Reifarth, A. Riego, M.S. Robles, C. Rubbia, M. Sabaté-Gilarte, R. Sarmento, A. Saxena, P. Schillebeeckx, S. Schmidt, D. Schumann, G. Tagliente, J.L. Tain, D. Tarrío, L. Tassan-Got, A. Tsinganis, S. Valenta, G. Vannini, I. Van Rijs, V. Variale, P. Vaz, A. Ventura, M.J. Vermeulen, V. Vlachoudis, R. Vlastou, A. Wallner, T. Ware, M. Weigand, C. Weiß, R. Wynants, T. Wright, P. Žugec
• Format: Article
• Language: English
• Published: Elsevier 2017-05-01
• Series: Physics Letters B
• Subjects: s Process; α+22Ne; Neutron spectroscopy
• Online Access: http://www.sciencedirect.com/science/article/pii/S0370269317301260
• ISSN: 0370-2693; 1873-2445

This work reports on accurate, high-resolution measurements of the 25Mg(n,γ)26Mg and 25Mg(n,tot) cross sections in the neutron energy range from thermal to about 300 keV, leading to a significantly improved 25Mg(n,γ)26Mg parametrization. The relevant resonances for n+25Mg were characterized from a combined R-matrix analysis of the experimental data. This resulted in an unambiguous spin/parity assignment of the corresponding excited states in 26Mg. With this information experimental upper limits of the reaction rates for 22Ne(α,n)25Mg and 22Ne(α,γ)26Mg were established, potentially leading to a significantly higher (α,n)/(α,γ) ratio than previously evaluated. The impact of these results has been studied for stellar models in the mass range 2 to 25 M⊙.