Radiative neutron capture cross-section measurement of ge isotopes at n_TOF CERN facility and its importance for stellar nucleosynthesis

This manuscript summarizes the results of radiative neutron capture cross-section measurements on two stable germanium isotopes, 70Ge and 73Ge. Experiments were performed at the n_TOF facility at CERN via the time-of-flight technique, over a wide neutron energy range, for all stable germanium isotopes (70,72,73,74, and 76). Results for 70Ge [Phys. Rev. C 100, 045804 (2019)] and 73Ge [Phys. Lett. B 790, 458 (2019)] are already published. In the field of nuclear structure, such measurements allow to study excited levels close to the neutron binding energy and to obtain information on nuclear properties. In stellar nucleosynthesis research, neutron induced reactions on germanium are of importance for nucleosynthesis in the weak component of the slow neutron capture processes.Peer ReviewedArticle signat per 134 autors/autores: A. Gawlik, C. Lederer-Woods, J. Andrzejewski, J. Perkowski, U. Battino, P. Ferreira, F. Gunsing, S. Heinitz, M. Krtička, C. Massimi, F. Mingrone, R. Reifarth, A. Tattersall, S. Valenta, C. Weiss, O. Aberle, L. Audouin, M. Bacak, J. Balibrea, M. Barbagallo, S. Barros, V. Bécares, F. Bečvář, C. Beinrucker, E. Berthoumieux, J. Billowes, D. Bosnar, M. Brugger, M. Caamaño, F. Calviño, M. Calviani, D. Cano-Ott, R. Cardella, A. Casanovas, D.M. Castelluccio, F. Cerutti, Y.H. Chen, E. Chiaveri, N. Colonna, G. Cortés, M.A. Cortés-Giraldo, L. Cosentino, L.A. Damone, M. Diakaki, M. Dietz, C. Domingo-Pardo, R. Dressler, E. Dupont, I. Durán, B. Fernández-Domínguez, A. Ferrari, P. Finocchiaro, V. Furman, K. Göbel, A.R. García, T. Glodariu, I.F. Gonçalves, E. González-Romero, A. Goverdovski, E. Griesmayer, C. Guerrero, H. Harada, T. Heftrich, J. Heyse, D.G. Jenkins, E. Jericha, F. Käppeler, Y. Kadi, T. Katabuchi, P. Kavrigin, V. Ketlerov, V. Khryachkov, A. Kimura, N. Kivel, I. Knapova, M. Kokkoris, E. Leal-Cidoncha, H. Leeb, J. Lerendegui-Marco, S. Lo Meo, S.J. Lonsdale, R. Losito, D. Macina, T. Martínez, P. Mastinu, M. Mastromarco, F. Matteucci, E.A. Maugeri, E. Mendoza, A. Mengoni, P.M. Milazzo, M. Mirea, S. Montesano, A. Musumarra, R. Nolte, A. Oprea, N. Patronis, A. Pavlik, J.I. Porras, J. Praena, J.M. Quesada, K. Rajeev, T. Rauscher, A. Riego-Perez, P.C. Rout, C. Rubbia, J.A. Ryan, M. Sabaté-Gilarte, A. Saxena, P. Schillebeeckx, S. Schmidt, D. Schumann, P. Sedyshev, A.G. Smith, A. Stamatopoulos, G. Tagliente, J.L. Tain, A. Tarifeño-Saldivia, L. Tassan-Got, A. Tsinganis, G. Vannini, V. Variale, P. Vaz, A. Ventura, V. Vlachoudis, R. Vlastou, A. Wallner, S. Warren, M. Weigand, C. Wolf, P.J. Woods, T. Wright, P. ŽugecObjectius de Desenvolupament Sostenible::7 - Energia Assequible i No ContaminantPostprint (author's final draft

Constraints on the dipole photon strength for the odd uranium isotopes

Background: The photon strength functions (PSFs) and nuclear level density (NLD) are key ingredients for calculation of the photon interaction with nuclei, in particular the reaction cross sections. These cross sections are important especially in nuclear astrophysics and in the development of advanced nuclear technologies. Purpose: The role of the scissors mode in the M1 PSF of (well-deformed) actinides was investigated by several experimental techniques. The analyses of different experiments result in significant differences, especially on the strength of the mode. The shape of the low-energy tail of the giant electric dipole resonance is uncertain as well. In particular, some works proposed a presence of the E1 pygmy resonance just above 7 MeV. Because of these inconsistencies additional information on PSFs in this region is of great interest. Methods: The γ-ray spectra from neutron-capture reactions on the 234U, 236 U, and 238 U nuclei have been measured with the total absorption calorimeter of the n_TOF facility at CERN. The background-corrected sum-energy and multi-step-cascade spectra were extracted for several isolated s-wave resonances up to about 140 eV. Results: The experimental spectra were compared to statistical model predictions coming from a large selection of models of photon strength functions and nuclear level density. No combination of PSF and NLD models from literature is able to globally describe our spectra. After extensive search we were able to find model combinations with modified generalized Lorentzian (MGLO) E1 PSF, which match the experimental spectra as well as the total radiative widths. Conclusions: The constant temperature energy dependence is favored for a NLD. The tail of giant electric dipole resonance is well described by the MGLO model of the E1 PSF with no hint of pygmy resonance. The M1 PSF must contain a very strong, relatively wide, and likely double-resonance scissors mode. The mode is responsible for about a half of the total radiative width of neutron resonances and significantly affects the radiative cross section