Constraints on the dipole photon strength for the odd uranium isotopes

Author(s)

J. Moreno-Soto, S. Valenta, E. Berthoumieux, A. Chebboubi, M. Diakaki, W. Dridi, E. Dupont, F. Gunsing, M. Krticka, O. Litaize, O. Serot, O. Aberle, V. Alcayne, S. Amaducci, J. Andrzejewski, L. Audouin, V. Bécares, V. Babiano-Suarez, M. Bacak, M. Barbagallo, Th Benedikt, S. Bennett, J. Billowes, D. Bosnar, A. Brown, M. Busso, M. Caamaño, L. Caballero-Ontanaya, F. Calviño, M. Calviani, D. Cano-Ott, A. Casanovas, F. Cerutti, E. Chiaveri, N. Colonna, G. Cortés, M. A. Cortés-Giraldo, L. Cosentino, S. Cristallo, L. A. Damone, P. J. Davies, M. Dietz, C. Domingo-Pardo, R. Dressler, Q. Ducasse, I. Durán, Z. Eleme, B. Fernández-Domínguez, A. Ferrari, P. Finocchiaro, V. Furman, K. Göbel, A. Gawlik-Ramiga, S. Gilardoni, I. F. Gonçalves, E. González-Romero, C. Guerrero, S. Heinitz, J. Heyse, D. G. Jenkins, A. Junghans, F. Käppeler, Y. Kadi, A. Kimura, I. Knapová, M. Kokkoris, Y. Kopatch, D. Kurtulgil, I. Ladarescu, C. Lampoudis, C. Lederer-Woods, S. J. Lonsdale, D. Macina, A. Manna, T. Martínez, A. Masi, C. Massimi, P. Mastinu, M. Mastromarco, E. A. Maugeri, A. Mazzone, E. Mendoza, A. Mengoni, V. Michalopoulou, P. M. Milazzo, F. Mingrone, A. Musumarra, A. Negret, R. Nolte, F. Ogállar, A. Oprea, N. Patronis, A. Pavlik, J. Perkowski, L. Piersanti, C. Petrone, E. Pirovano, I. Porras, J. Praena, J. M. Quesada, D. Ramos-Doval, T. Rauscher, R. Reifarth, D. Rochman, M. Sabaté-Gilarte, A. Saxena, P. Schillebeeckx, D. Schumann, A. Sekhar, A. G. Smith, N. V. Sosnin, P. Sprung, A. Stamatopoulos, G. Tagliente, J. L. Tain, A. Tarifeño-Saldivia, L. Tassan-Got, P. Torres-Sánchez, A. Tsinganis, J. Ulrich, S. Urlass, G. Vannini, V. Variale, P. Vaz, A. Ventura, D. Vescovi, V. Vlachoudis, R. Vlastou, A. Wallner, P. J. Woods, T. Wright, P. Žugec

Abstract

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 ?-ray spectra from neutron-capture reactions on the U234, U236, and U238 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.

Organisation(s)

Isotope Physics

External organisation(s)

Université Paris-Saclay, Charles University Prague, CEA Cadarache, Technopark Sidi Thabet, European Organization for Nuclear Research (CERN), Centro de Investigaciones Energeticas Medioambientales y Tecnológica, Istituto Nazionale di Fisica Nucleare (INFN), Roma, University of Lodz, IPHC, Universitat de València, Technische Universität Wien, Johann Wolfgang Goethe-Universität Frankfurt am Main, University of Manchester, University of Zagreb, York University, Università degli Studi di Perugia, Universidade de Santiago de Compostela (USC), Universitat Politècnica de Catalunya, Universidad de Sevilla, INAF-Osservatorio Astrofisico di Torino, Università degli Studi di Bari, University of Edinburgh, Paul Scherrer Institute, Physikalisch-Technische Bundesanstalt, University of Ioannina, Associação EURATOM/IST, Commiss European Communities, Joint Res Ctr, Inst Reference Mat & Measurements, Helmholtz-Zentrum Dresden-Rossendorf, Karlsruher Institut für Technologie, Japan Atomic Energy Agency, National Technical University of Athens (NTUA), Aristotle University of Thessaloniki, University of Bologna, Istituto Nazionale di Fisica Nucleare (INFN), Legnaro, Institute of Genetics and Biophysics "Adriano Buzzati-Traverso", CNR, Agenzia nazionale per le nuove tecnologie, l’energia e lo sviluppo economico sostenibile, Università degli Studi di Trieste, Università degli Studi di Catania, Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering, Universidad de Granada, Universität Basel, University of Hertfordshire, Bhabha Atomic Research Center, Joint Institute for Nuclear Research, Australian National University, Dubna

Journal

Physical Review C

Volume

105

No. of pages

14

ISSN

2469-9985

DOI

https://doi.org/10.1103/PhysRevC.105.024618

Publication date

02-2022

Peer reviewed

Yes

Austrian Fields of Science 2012

103014 Nuclear physics, 103012 High energy physics

Keywords

ASJC Scopus subject areas

Nuclear and High Energy Physics

Portal url

https://ucris.univie.ac.at/portal/en/publications/constraints-on-the-dipole-photon-strength-for-the-odd-uranium-isotopes(6fe30b2f-518d-4d43-9391-e3b88c6cde18).html