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Isomer depletion as experimental evidence of nuclear excitation by electron capture.
Chiara, C J; Carroll, J J; Carpenter, M P; Greene, J P; Hartley, D J; Janssens, R V F; Lane, G J; Marsh, J C; Matters, D A; Polasik, M; Rzadkiewicz, J; Seweryniak, D; Zhu, S; Bottoni, S; Hayes, A B; Karamian, S A.
Afiliación
  • Chiara CJ; Oak Ridge Associated Universities Fellowship Program, US Army Research Laboratory, Adelphi, Maryland 20783, USA.
  • Carroll JJ; US Army Research Laboratory, Adelphi, Maryland 20783, USA.
  • Carpenter MP; Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
  • Greene JP; Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
  • Hartley DJ; Department of Physics, US Naval Academy, Annapolis, Maryland 21402, USA.
  • Janssens RVF; Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
  • Lane GJ; Department of Nuclear Physics, Research School of Physics and Engineering, Australian National University, Canberra, Australian Capital Territory 0200, Australia.
  • Marsh JC; Oak Ridge Associated Universities Fellowship Program, US Army Research Laboratory, Adelphi, Maryland 20783, USA.
  • Matters DA; Defense Threat Reduction Agency, Fort Belvoir, Virginia 22060, USA.
  • Polasik M; Faculty of Chemistry, Nicolaus Copernicus University in Torun, 87-100 Torun, Poland.
  • Rzadkiewicz J; National Centre for Nuclear Research, 05-400 Otwock, Poland.
  • Seweryniak D; Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
  • Zhu S; Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
  • Bottoni S; Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
  • Hayes AB; Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, Dubna 141980, Russia.
  • Karamian SA; Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, Dubna 141980, Russia.
Nature ; 554(7691): 216-218, 2018 02 07.
Article en En | MEDLINE | ID: mdl-29420479
The atomic nucleus and its electrons are often thought of as independent systems that are held together in the atom by their mutual attraction. Their interaction, however, leads to other important effects, such as providing an additional decay mode for excited nuclear states, whereby the nucleus releases energy by ejecting an atomic electron instead of by emitting a γ-ray. This 'internal conversion' has been known for about a hundred years and can be used to study nuclei and their interaction with their electrons. In the inverse process-nuclear excitation by electron capture (NEEC)-a free electron is captured into an atomic vacancy and can excite the nucleus to a higher-energy state, provided that the kinetic energy of the free electron plus the magnitude of its binding energy once captured matches the nuclear energy difference between the two states. NEEC was predicted in 1976 and has not hitherto been observed. Here we report evidence of NEEC in molybdenum-93 and determine the probability and cross-section for the process in a beam-based experimental scenario. Our results provide a standard for the assessment of theoretical models relevant to NEEC, which predict cross-sections that span many orders of magnitude. The greatest practical effect of the NEEC process may be on the survival of nuclei in stellar environments, in which it could excite isomers (that is, long-lived nuclear states) to shorter-lived states. Such excitations may reduce the abundance of the isotope after its production. This is an example of 'isomer depletion', which has been investigated previously through other reactions, but is used here to obtain evidence for NEEC.
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Tipo de estudio: Prognostic_studies Idioma: En Revista: Nature Año: 2018 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Reino Unido
Texto completo
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Tipo de estudio: Prognostic_studies Idioma: En Revista: Nature Año: 2018 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Reino Unido