Disappearance of shell effects and persistence of an even-odd staggering in the fragment production in nuclear reactions at relativistic energies

F. Rejmund, A. Bethenod, P. Napolitani, J. Taieb, C. Villagrasa, L. Audouin, P. Armbruster, C. O. Bacri, J. Benlliure, M. Bernas, B. Berthier, A. Boudard, E. Casajeros, S. Czajkowski, J. J. Connell, T. Enqvist, T. Faesterman, J. S. George, A. Junghans, B. JuradoF. Hammache, S. Leray, R. Legrain, R. A. Mewaldt, J. Pereira, M. V. Ricciardi, K. H. Schmidt, C. Stéphan, K. Sümmerer, L. Tassan-Got, C. Volant, M. E. Wiedenbeck, W. Wlazlo, Nathan Eugene Yanasak

Research output: Contribution to journalArticle

Abstract

The isotopic distributions of fragments produced in the spallation of uranium are strongly influenced by the fission of the excited prefragments, highly fissile nuclei. The competition between fission and evaporation around the doubly-magic nucleus Pb is discussed. The light fragments from Fe beam are produced with a strong enhancement of even-even nuclei compared to the odd-odd in the region of nuclei with equal number of neutrons and protons, N ∼ Z. This staggering in the production of light fragments is not observed in the production of heavy fragments, and is in contradiction with the basis of the statistical model of deexcitation of a hot nucleus. Pairing interaction as a function of the excitation energy and as a function of the isospin of the nucleus are questioned.

Original languageEnglish (US)
Pages (from-to)85-91
Number of pages7
JournalActa Physica Hungarica New Series Heavy Ion Physics
Volume16
Issue number1-4
DOIs
StatePublished - Dec 1 2002
Externally publishedYes

Fingerprint

staggering
nuclear reactions
fragments
nuclei
fission
energy
even-even nuclei
spallation
uranium
evaporation
neutrons
protons
augmentation
excitation
interactions

Keywords

  • Fission probabilities
  • Proton-neutron pairing
  • Shell effect in level densities
  • Spallation reaction

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Physics and Astronomy(all)

Cite this

Disappearance of shell effects and persistence of an even-odd staggering in the fragment production in nuclear reactions at relativistic energies. / Rejmund, F.; Bethenod, A.; Napolitani, P.; Taieb, J.; Villagrasa, C.; Audouin, L.; Armbruster, P.; Bacri, C. O.; Benlliure, J.; Bernas, M.; Berthier, B.; Boudard, A.; Casajeros, E.; Czajkowski, S.; Connell, J. J.; Enqvist, T.; Faesterman, T.; George, J. S.; Junghans, A.; Jurado, B.; Hammache, F.; Leray, S.; Legrain, R.; Mewaldt, R. A.; Pereira, J.; Ricciardi, M. V.; Schmidt, K. H.; Stéphan, C.; Sümmerer, K.; Tassan-Got, L.; Volant, C.; Wiedenbeck, M. E.; Wlazlo, W.; Yanasak, Nathan Eugene.

In: Acta Physica Hungarica New Series Heavy Ion Physics, Vol. 16, No. 1-4, 01.12.2002, p. 85-91.

Research output: Contribution to journalArticle

Rejmund, F, Bethenod, A, Napolitani, P, Taieb, J, Villagrasa, C, Audouin, L, Armbruster, P, Bacri, CO, Benlliure, J, Bernas, M, Berthier, B, Boudard, A, Casajeros, E, Czajkowski, S, Connell, JJ, Enqvist, T, Faesterman, T, George, JS, Junghans, A, Jurado, B, Hammache, F, Leray, S, Legrain, R, Mewaldt, RA, Pereira, J, Ricciardi, MV, Schmidt, KH, Stéphan, C, Sümmerer, K, Tassan-Got, L, Volant, C, Wiedenbeck, ME, Wlazlo, W & Yanasak, NE 2002, 'Disappearance of shell effects and persistence of an even-odd staggering in the fragment production in nuclear reactions at relativistic energies', Acta Physica Hungarica New Series Heavy Ion Physics, vol. 16, no. 1-4, pp. 85-91. https://doi.org/10.1556/APH.16.2002.1-4.10
Rejmund, F. ; Bethenod, A. ; Napolitani, P. ; Taieb, J. ; Villagrasa, C. ; Audouin, L. ; Armbruster, P. ; Bacri, C. O. ; Benlliure, J. ; Bernas, M. ; Berthier, B. ; Boudard, A. ; Casajeros, E. ; Czajkowski, S. ; Connell, J. J. ; Enqvist, T. ; Faesterman, T. ; George, J. S. ; Junghans, A. ; Jurado, B. ; Hammache, F. ; Leray, S. ; Legrain, R. ; Mewaldt, R. A. ; Pereira, J. ; Ricciardi, M. V. ; Schmidt, K. H. ; Stéphan, C. ; Sümmerer, K. ; Tassan-Got, L. ; Volant, C. ; Wiedenbeck, M. E. ; Wlazlo, W. ; Yanasak, Nathan Eugene. / Disappearance of shell effects and persistence of an even-odd staggering in the fragment production in nuclear reactions at relativistic energies. In: Acta Physica Hungarica New Series Heavy Ion Physics. 2002 ; Vol. 16, No. 1-4. pp. 85-91.
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AU - Bethenod, A.

AU - Napolitani, P.

AU - Taieb, J.

AU - Villagrasa, C.

AU - Audouin, L.

AU - Armbruster, P.

AU - Bacri, C. O.

AU - Benlliure, J.

AU - Bernas, M.

AU - Berthier, B.

AU - Boudard, A.

AU - Casajeros, E.

AU - Czajkowski, S.

AU - Connell, J. J.

AU - Enqvist, T.

AU - Faesterman, T.

AU - George, J. S.

AU - Junghans, A.

AU - Jurado, B.

AU - Hammache, F.

AU - Leray, S.

AU - Legrain, R.

AU - Mewaldt, R. A.

AU - Pereira, J.

AU - Ricciardi, M. V.

AU - Schmidt, K. H.

AU - Stéphan, C.

AU - Sümmerer, K.

AU - Tassan-Got, L.

AU - Volant, C.

AU - Wiedenbeck, M. E.

AU - Wlazlo, W.

AU - Yanasak, Nathan Eugene

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N2 - The isotopic distributions of fragments produced in the spallation of uranium are strongly influenced by the fission of the excited prefragments, highly fissile nuclei. The competition between fission and evaporation around the doubly-magic nucleus Pb is discussed. The light fragments from Fe beam are produced with a strong enhancement of even-even nuclei compared to the odd-odd in the region of nuclei with equal number of neutrons and protons, N ∼ Z. This staggering in the production of light fragments is not observed in the production of heavy fragments, and is in contradiction with the basis of the statistical model of deexcitation of a hot nucleus. Pairing interaction as a function of the excitation energy and as a function of the isospin of the nucleus are questioned.

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KW - Proton-neutron pairing

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