New measurement of neutron capture resonances in Bi-209
Author
Domingo-Pardo, C.
Abbondanno, U.
Aerts, G.
Alvarez-Pol, H.
Alvarez-Velarde, F.
Andriamonje, S.
Andrzejewski, J.
Assimakopoulos, P.
Audouin, L.
Badurek, G.
Baumann, P.
Becvar, F.
Berthoumieux, E.
Calvino, F.
Cano-Ott, D.
Capote, R.
de Albornoz, A. Carrillo
Cennini, P.
Chepel, V.
Chiaveri, E.
Colonna, N.
Cortes, G.
Couture, A.
Cox, J.
Dahlfors, M.
David, S.
Dillman, I.
Dolfini, R.
Dridi, W.
Duran, I.
Eleftheriadis, C.
Embid-Segura, M.
Ferrant, L.
Ferrari, A.
Ferreira-Marques, R.
Fitzpatrick, L.
Frais-Koelbl, H.
Fujii, K.
Furman, W.
Gallino, R.
Goncalves, I.
Gonzalez-Romero, E.
Goverdovski, A.
Gramegna, F.
Griesmayer, E.
Guerrero, C.
Gunsing, F.
Haas, B.
Haight, R.
Heil, M.
Herrera-Martinez, A.
Igashira, M.
Isaev, S.
Jericha, E.
Kadi, Y.
Kappeler, F.
Karamanis, D.
Karadimos, D.
Kerveno, M.
Ketlerov, V.
Koehler, P.
Konovalov, V.
Kossionides, E.
Krticka, M.
Lamboudis, C.
Leeb, H.
Lindote, A.
Lopes, I.
Lozano, M.
Lukic, S.
Marganiec, J.
Marques, L.
Marrone, S.
Mastinu, P.
Mengoni, A.
Milazzo, P. M.
Moreau, C.
Mosconi, M.
Neves, F.
Oberhummer, H.
Oshima, M.
O'Brien, S.
Pancin, J.
Papachristodoulou, C.
Papadopoulos, C.
Paradela, C.
Patronis, N.
Pavlik, A.
Pavlopoulos, P.
Perrot, L.
Plag, R.
Plompen, A.
Plukis, A.
Poch, A.
Pretel, C.
Quesada, J.
Rauscher, T.
Reifarth, R.
Rosetti, M.
Rubbia, C.
Rudolf, G.
Rullhusen, P.
Salgado, J.
Sarchiapone, L.
Savvidis, I.
Stephan, C.
Tagliente, G.
Tain, J. L.
Tassan-Got, L.
Tavora, L.
Terlizzi, R.
Vannini, G.
Vaz, P.
Ventura, A.
Villamarin, D.
Vincente, M. C.
Vlachoudis, V.
Vlastou, R.
Voss, F.
Walter, S.
Wendler, H.
Wiescher, M.
Wisshak, K.
Attention
2299/12388
Abstract
The neutron capture cross section of Bi-209 has been measured at the CERN n_TOF facility by employing the pulse-height-weighting technique. Improvements over previous measurements are mainly because of an optimized detection system, which led to a practically negligible neutron sensitivity. Additional experimental sources of systematic error, such as the electronic threshold in the detectors, summing of gamma-rays, internal electron conversion, and the isomeric state in bismuth, have been taken into account. gamma-Ray absorption effects inside the sample have been corrected by employing a nonpolynomial weighting function. Because Bi-209 is the last stable isotope in the reaction path of the stellar s-process, the Maxwellian averaged capture cross section is important for the recycling of the reaction flow by alpha decays. In the relevant stellar range of thermal energies between kT=5 and 8 keV our new capture rate is about 16% higher than the presently accepted value used for nucleosynthesis calculations. At this low temperature an important part of the heavy Pb-Bi isotopes are supposed to be synthesized by the s-process in the He shells of low mass, thermally pulsing asymptotic giant branch stars. With the improved set of cross sections we obtain an s-process fraction of 19 +/- 3% of the solar bismuth abundance, resulting in an r-process residual of 81 +/- 3%. The present (n,gamma) cross-section measurement is also of relevance for the design of accelerator driven systems based on a liquid metal Pb/Bi spallation target.