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Scientific program

Dernière mise à jour : mercredi 7 juin 2006, par Nicolas Busser

DEMON’s activity concerns mainly the study of dynamics of nuclear reactions at close to the barrier energies as well as in the Fermi energy domain.

At low energy

At low energy, a wide program of measurements has been undertaken which aims to study the time-scale and the dynamics associated with the fusion-fission process by investigating the whole fissility domain from the Businaro-Gallone point up to the super-heavy elements with Z=110.
More than 50 projectile-target and incident energy combinations have already been used (red points in figure) at SARA in Grenoble, LNS in Catania, K500 at Texas A&M and at the VIVITRON in Strasbourg. Some 30 more combinations are planned at the VIVITRON and at JINR in Dubna (blue points in figure).

Beside the determination of the time-scale and of the related dissipation (which is studied in different domains of competition between fusion-fission, evaporation residue formation or fast fission and as a function of entrance and output channel mass asymmetries, shape evolution, excitation energy and angular momentum), particular aspects connected with

  • the possible influence of the formation time,
  • the bimodal character of the Thorium isotopes fission,
  • the influence of the neutron composition of the projectile on the extra-extra-push in asymmetric systems leading to Z=110 are of particular interest.

Bibliography

  • Nature and properties of the fission modes of the neutron deficient 220,224,226Th nuclides. - M.G.Itkis, N.A.Kondratiev, E.M.Kozulin, Yu.Ts.Oganessian, V.V.Pashkevich, I.V.Pokrovsky, A.Ya.Rusanov, V.S.Salamatin, L.Calabretta, C.Maiolino, K.Lukashi, C.Agodi, G.Bellia, G.G.Chubarian, B.Hurst, D.OíKelly, R.Schmitt, F.Hanappe, E.Liatard, L.Stuttgé - International Symposium on Large-Scale Collective Motion of Atomic Nuclei, Brolo, Italy, October 15-19, 1996, to be published.
  • DEMON as a neutron probe in heavy ion collisions. - O.Dorvaux, F.R.Lecolley, L.Stuttgé, F.Hanappe, G.Rudolf, G.Bizard, D.Durand, B.Benoit, J.Colin, G.Costa, G.Guillaume, F.Gulminelli, B.Heusch, A.Huck, F.Lefebvres, S.Mouatassim, S.Tomasevic, C.Le Brun, M.Louvel, R.Regimbart, J.C.Steckmeyer, B.Tamain - International Symposium on Large-Scale Collective Motion of Atomic Nuclei, Brolo, Italy, October 15-19, 1996, to be published.

At intermediate energy

At intermediate energy, two experiments have been performed at GANIL

- The experiment E236 aimed to get an answer about the excitation energy sharing between the projectile and the target in the 86Kr + 165Ho at 60 MeV/u. A confirmation of an equipartition has been obtained. The existence of a new prethermalization component which had been observed in previous experiments in the emission of light charged particles by the projectile-like fragment could also been confirmed.

Bibliography

  • Etude de la dynamique des collisions entre noyaux lourds dans la réaction 86Kr + 165Ho à 60 MeV/n à l’aide du multidétecteur DéMoN. - O.Dorvaux, PhD Thesis, Université Louis Pasteur de Strasbourg, France, January 14 , 1997.
  • Dynamics of nuclear collisions studied with the neutron detector DEMON. - O.Dorvaux, B.Bilwes, G.Bizard, G.Costa, D.Durand, D.Durand, G.Guillaume, F.Hanappe, B.Heusch, A.Huck, C.Le Brun, F.R.Lecolley, J.F.Lecolley, S.Mouatassim, A.Ninane, G.Rudolf, J.C.Steckmeyer, L.Stuttgé, B.Tamain and S.Tomasevic - International Conference on Dynamical Aspects of Nuclear Fission, Casta-Papiernicka (Slovakia), August 30 - September 4, 1996.
  • DEMON as a neutron probe in heavy ion collisions. - O.Dorvaux, F.R.Lecolley,L.Stuttgé, F.Hanappe, G.Rudolf, G.Bizard, D.Durand, B.Benoit, J.Colin, G.Costa, G.Guillaume, F.Gulminelli, B.Heusch, A.Huck, F.Lefebvres, S.Mouatassim, S.Tomasevic, C.Le Brun, M.Louvel, R.Regimbart, J.C.Steckmeyer, B.Tamain - International Symposium on Large-Scale Collective Motion of Atomic Nuclei, Brolo, Italy, October 15-19, 1996, to be published.

- The experiment E240 was dedicated to measure the production of heavy residues in 40Ar + 197Au at 60 MeV/u and in particular to determine the maximum of excitation energy or temperature a hot nucleus can sustain without disrupting. The temperatures of the excited nuclei have been deduced from the energy spectra of the coincident neutrons. A temperature as high as 6 MeV has been observed for the most excited heavy partner of the dissipative collisions.

Bibliography

  • Mesure de la température maximale des résidus chauds émis dans la réaction Ar + Au à 60 MeV/u. - F.R.Lecolley, PhD Thesis, Université de Caen, France, June 12, 1996.
  • Highest temperatures sustainable in heavy nuclei produced in Ar + Au collisions at 60 MeV/u. - F.R.Lecolley, B.Benoit, G.Bizard, G.Costa, O.Dorvaux, D.Durand, Y.el Masri, G.Guillaume, F.Gulminelli, F.Hanappe, B.Heusch, A.Huck, T.Keutgen, C.Le Brun, F.Lefebvres, M.Louvel, A.Ninane, R.Regimbart, G.Rudolf, J.C.Steckmeyer, L.Stuttgé, B.Tamain, accepted by Nuclear Physics.