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1. Angular correlations in the prompt neutron emission of spontaneous fission of 252Cf

Author

E. V. Chernysheva, Zh. V. Mezentseva, Yu. N. Kopatch, Manfred Mutterer, Friedrich Gönnenwein, I. S. Guseva, S.A. Telezhnikov, A. M. Gagarski, F. Hanappe, F.-J. Hambsch, A. Chietera, Louise Stuttge, Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), and Université de Strasbourg (UNISTRA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Fission, Neutron emission, Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Nuclear physics, Prompt neutron, 0103 physical sciences, Neutron detection, Nuclear fusion, Neutron, Nuclear Experiment, 010306 general physics, Anisotropy, Spontaneous fission
Abstract

Neutron angular distributions in spontaneous fission of 252Cf are investigated. The CORA experiment, performed at IPHC Strasbourg, aims at elucidating neutron emission mechanisms in the fission process. The experimental setup is composed of the angle-sensitive twin ionisation chamber CODIS for the detection of fission fragments and the DEMON neutron detector assembly. The development of a simulation toolkit based on GEANT4 and MENATE_R is described, adapted as a strategy to investigate the influence of experimental conditions on the observed properties of neutrons emitted. Besides the kinematic neutron anisotropy in the laboratory system due to neutron evaporation from moving fragments, two additional effects are discussed which may have an influence on the angular distributions of neutrons: scission neutrons and dynamic neutron emission anisotropy in the CM system of fragments due to the spin carried by fragments. A new analysis method is presented to disentangle the dynamic anisotropy from the other effects in an independent way. For the dynamic anisotropy only an upper limit could be found. Results for the angular correlation $ (\mathrm{n},\mathrm{n})$ between two evaporated neutrons and the correlation $ (\mathrm{n},\mathrm{LF})$ between an evaporated neutron and the Light Fragment direction of flight are reported.

Published
2018
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2. Challenging fission dynamics around the barrier: The case of $^{34}$S + $^{186}$W

Author

F. Hanappe, S. Calinescu, A. Gottardo, F. Azaiez, I. M. Harca, K. V. Novikov, E. M. Kozulin, I. M. Itkis, O. Dorvaux, Wladyslaw Henryk Trzaska, D. Verney, T. Loktev, Emanuele Vardaci, J. Piot, G. N. Knyazheva, C. Schmitt, I. Matea, A. A. Bogachev, C. Borcea, G. G. Chubarian, S. N. Dmitriev, C. Petrone, Grand Accélérateur National d'Ions Lourds (GANIL), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Université de Strasbourg (UNISTRA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Kozulin, E. M., Vardaci, Emanuele, Harca, I. M., Schmitt, C., Itkis, I., Knyazheva, G., Novikov, K., Bogachev, A., Dmitriev, S., Loktev, T., Azaiez, F., Matea, I., Verney, D., Gottardo, A., Dorvaux, O., Piot, J., Chubarian, G., Trzaska, W. H., Hanappe, F., Borcea, C., Calinescu, S., and Petrone, C.

Subjects
Physics, Nuclear and High Energy Physics, Field (physics), 010308 nuclear & particles physics, Fission, Hadron, Coulomb barrier, Observable, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Collision, Kinetic energy, 01 natural sciences, Nuclear physics, 0103 physical sciences, Nuclear fusion, Nuclear Experiment, 010306 general physics
Abstract

The current status of fission dynamics studies in heavy-ion collisions around the Coulomb barrier is illustrated with the 34S + 186W reaction. The fission-fragment mass and total kinetic energy were measured at the ALTO facility at IPN Orsay, France, with a dedicated set-up using the (v, E) approach. The measurement reveals the presence of an asymmetric fission component on top of a predominantly symmetric distribution. The asymmetric structure, pointed out for the first time, is discussed along with results of previous experiments studying the same reaction. While these analyses suggested the contribution from either quasi-fission or pre-equilibrium fission, we offer an alternative interpretation, in terms of shell-driven compound-nucleus fission. The present measurement demonstrates the critical influence of resolution when addressing puzzling cases, situated at the crossroads of the various channels opened in a heavy-ion collision. Current status in the field clearly calls for innovative measurements involving manifold correlations and new observables. The outcome of the attempt done in this work in this direction, based on the coincident measurement of prompt \( \gamma\)-rays is reported, and encouraging perspectives are discussed.

Published
2016
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3. Pre-scission neutron multiplicity associated with the dynamical process in the superheavy-mass region

Author

Masahisa Ohta, Yoshihiro Aritomo, and F. Hanappe

Subjects
Physics, Nuclear and High Energy Physics, Nuclear Theory, Basis (linear algebra), Neutron emission, FOS: Physical sciences, Space (mathematics), Nuclear Theory (nucl-th), Nuclear physics, medicine.anatomical_structure, Distribution (mathematics), Scientific method, medicine, Deformation (engineering), Nuclear Experiment, Nucleus, Bond cleavage
Abstract

The fusion-fission process accompanied by neutron emission is studied in the superheavy-mass region on the basis of the fluctuation-dissipation model combined with a statistical model. The calculation of the trajectory or the shape evolution in the deformation space of the nucleus with neutron emission is performed. Each process (quasi-fission, fusion-fission, and deep quasi-fission processes) has a characteristic travelling time from the point of contact of colliding nuclei to the scission point. These dynamical aspects of the whole process are discussed in terms of the pre-scission neutron multiplicity, which depends on the time spent on each process. We have presented the details of the characteristics of our model calculation in the reactions $^{48}$Ca+$^{208}$Pb and $^{48}$Ca+$^{244}$Pu, and shown how the structure of the distribution of pre-scission neutron multiplicity depends on the incident energy., 19 pages, 12 figures, Accepted for publication in J. Phys. G

Published
2006
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4. Dynamics of fusion-fission process with neutron evaporation in superheavy mass region

Author

Yoshihiro Aritomo, F. Hanappe, Masahisa Ohta, L. Stuttge, Th. Materna, Heyd, Yvette, Institut de Recherches Subatomiques (IReS), and Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Nuclear and High Energy Physics, Fusion, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Fission, Neutron emission, Nuclear Theory, Evaporation, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Kinetic energy, Nuclear physics, Cross section (physics), Scientific method, Neutron, Atomic physics, Nuclear Experiment
Abstract

The fusion-fission process for the synthesis of superheavy elements is discussed on the basis of fluctuation-dissipation dynamics. Recently, experiments at Dubna on fission of superheavy nuclei were carried out, and the mass and total kinetic energy distributions of fission fragments were measured. The fusion-fission cross section was derived from the experiments. We analyze the data using a three-dimensional Langevin calculation. We present a clear understanding of the competition between the fusion and the quasifission. We emphasize that a one-or two-dimensional model of Langevin calculation is not sufficient to estimate the fusion cross section in the superheavy mass region. Also, experiments on the emission of neutrons in correlation with fission fragments were conducted. It is useful to investigate the fusion-fission dynamics. We take into account the neutron emission with a Langevin calculation and compare it with experimental data. Finally, we discuss the evaporation residue cross section for superheavy elements.

Published
2004
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5. Investigation of Shell Effects in the Fusion-Fission Process in the Reaction $^{34}$S + $^{186}$W Near the Interaction Barrier

Author

J.M. Itkis, A. Gottardo, I. Matea, F. Hanappe, K. V. Novikov, W. H. Trzaska, G. Chubarian, G. Knyazheva, F. Azaiez, C. Schmitt, E. Vardaci, A. A. Bogachev, E.M. Kozulin, S. N. Dmitriev, I.M. Harca, D. Verney, J. Piot, T. Loktev, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Grand Accélérateur National d'Ions Lourds (GANIL), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Yu. E. Penionzhkevich, Yu. G. Sobolev, Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, 010308 nuclear & particles physics, Shell effects, Shell (structure), Bi-modal fission, Fusion fission, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, 01 natural sciences, Gamma spectroscopy, Chemical physics, Scientific method, 0103 physical sciences, 010306 general physics, Nuclear Experiment, Fusion-fission
Abstract

International audience; The reaction 34S + 186W at Elab = 160 MeV was investigated with the aim of diving into the features of the fusion-fission process. Gamma rays coincident with binary reaction fragments were measured using the high efficiency gamma-ray spectrometer ORGAM at the TANDEM Accelerator facility of I.P.N., Orsay, and the time-of-flight spectrometer for fission fragments registration CORSET of the Flerov Laboratory of Nuclear Reactions (FLNR), Dubna. Evidence of symmetric and asymmetric fission modes were observed in the mass and TKE distributions, occurring due to shell effects in the fragments. The coupling of the ORGAM and CORSET setups enables the FF-γ coincident measurement which offers the opportunity to extract the isotopic distribution of the fragments of different masses formed in the aforementioned reaction and to find the exact neutron multiplicity, the average spin and average angular momenta. Details regarding the experimental setup, methods of processing the acquisitioned data and preliminary results are presented.

Published
2014
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6. Halo Structure ofB14e

Author

M. J. Lopez, S. Leenhardt, B. Benoit, N. Curtis, L. Axelsson, M. J. G. Borge, Thomas Nilsson, L. Stuttge, Giovanni Fazio, D. Guillemaud-Mueller, O. Sorlin, E. de Goes Brennand, F. Sarazin, F. M. Marqués, C. Le Brun, Graziele De Sousa Costa, B. R. Fulton, K. Riisager, A. D'Arrigo, G. Giardina, J. C. Angélique, M. Lewitowicz, N. M. Clarke, S. M. Singer, O. Dorvaux, W. N. Catford, M. Labiche, Björn Jonson, S. Grévy, F. Hanappe, S. P. G. Chappell, I. Piqueras, N. A. Orr, B. Heusch, F. de Oliveira, K. L. Jones, Gunnar Nyman, Karin Markenroth, M. G. Saint Laurent, A.C. Mueller, Alain Ninane, U. C. Bergmann, and Martin Freer

Subjects
Physics, 010308 nuclear & particles physics, Nuclear Theory, General Physics and Astronomy, Halo nucleus, 01 natural sciences, Dissociation (chemistry), Spectral line, 0103 physical sciences, Invariant mass, Neutron, Halo, Atomic physics, Nuclear Experiment, 010306 general physics, Nucleon, Excitation
Abstract

The two-neutron halo nucleus (14)Be has been investigated in a kinematically complete measurement of the fragments ((12)Be and neutrons) produced in dissociation at 35 MeV/nucleon on C and Pb targets. Two-neutron removal cross sections, neutron angular distributions, and invariant mass spectra were measured, and the contributions from electromagnetic dissociation (EMD) were deduced. Comparison with three-body model calculations suggests that the halo wave function contains a large nu(2s(1/2))(2) admixture. The EMD invariant mass spectrum exhibited enhanced strength near threshold consistent with a nonresonant soft-dipole excitation.

Published
2001
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7. Highest temperatures sustainable in heavy nuclei produced in Ar+Au collisions at 60 AMeV

Author

J.C. Steckmeyer, G. Rudolf, B. Heusch, L. Stuttge, G. Bizard, B. Benoit, G. Costa, A. Huck, G. Guillaume, I. Tilquin, Y. El Masri, F. Hanappe, Francesca Gulminelli, Bernard Tamain, M. Louvel, Dominique Durand, François-René Lecolley, O. Dorvaux, C. Le Brun, Alain Ninane, R. Regimbart, Thomas Keutgen, F. Lefebvres, Guesnon, Sandrine, Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), and Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nuclear reaction, Physics, Nuclear and High Energy Physics, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Fission, Nuclear Theory, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Kinetic energy, Nuclear physics, Fragmentation (mass spectrometry), Coincident, Neutron detection, Neutron, Atomic physics, Nuclear Experiment
Abstract

The specific decay mode of hot nuclei surviving fission or fragmentation and leading in the final state to the production of a large residue has been studied in Ar+Au collisions at 60 A MeV. The temperature of these residues has been obtained by analysing the kinematical characteristics (angular and kinetic energy distributions) of the coincident neutrons detected by the DEMON neutron detector, A total cross section of 50 mb has been measured for the production of residues with an initial temperature of 6 MeV or more. This result is compared with the predictions of a microscopic transport model. (C) 1997 Elsevier Science B.V.

Published
1997
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8. Neutron Emission in Fission And Quasi-Fission of Hs

Author

I. M. Itkis, M. G. Itkis, G. N. Knyazheva, E. M. Kozulin, L. Krupa, F. Hanappe, O. Dorvaux, L. Stuttge, Yu. E. Penionzhkevich, and S. M. Lukyanov

Subjects
Chemical kinetics, Nuclear reaction, Isotope, Fission, Neutron emission, Chemistry, Nuclear Theory, Coulomb barrier, Neutron, Atomic physics, Nuclear Experiment, Nucleon
Abstract

Mass and energy distributions of fission‐like fragments obtained in the reactions 26Mg+248Cm, 36S+238U and 58Fe+208Pb leading to the formation of 266,274Hs are reported. From the analysis of TKE distributions for symmetric fragment it was found that at energies below the Coulomb barrier the bimodal fission of 274Hs, formed in the reaction 26Mg+248Cm, is observed, while in the reaction 36S+238U at these energies the main part of the symmetric fragments arises from the quasi‐fission process. At energies above the Coulomb barrier the fusion‐fission is a main process leading to the formation of symmetric fragment for the both reactions. In the case of 58Fe+208Pb reaction the quasi‐fission process is the main reaction mechanism at all measured energies. The pre‐ and post‐scission neutron multiplicities as a function of the fragment mass have been obtained for all studied reactions.

Published
2010
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9. Spectroscopy of heavy elements at Dubna

Author

O. Dorvaux, A. Lopez-Martens, K. Hauschild, A. V. Yeremin, A. Khouaja, A. V. Belozerov, Ch. Briançon, M. L. Chelnokov, V. I. Chepigin, D. Curien, P. Désesquelles, B. Gall, V. A. Gorshkov, M. Guttormsen, F. Hanappe, A. P. Kabachenko, F. Khalfallah, A. Korichi, A. C. Larsen, O. N. Malyshev, A. Minkova, Yu. Ts. Oganessian, A. G. Popeko, M. Rousseau, N. Rowley, R. N. Sagaidak, S. Sharo, A. V. Shutov, S. Siem, V. I. L. Stuttgé, A. I. Svirikhin, N. U. H. Syed, Ch. Theisen, P. Demetriou, R. Julin, and S. V. Harissopulos

Subjects
Physics, Nuclear physics, Recoil, Isotope, Isotonic, Nuclear structure, Nuclear Experiment, Spectroscopy
Abstract

In 2004, the GABRIELA (Gamma Alpha Beta Recoil Investigation with the Electromagnetic Analyzer VASSILISSA) collaboration started a twofold scientific program at the FLNR (Dubna) laboratory : (a) the systematic study of the behaviour of single particle states within isotopic and isotonic chains with Z = 100–104 as N varies from 152 to 162 and (b) the study of isotopes for which very little spectroscopic information is known. After discussing the Physics motivations and the experimental setup, some new results concerning the structure of 249Fm and 253No nuclei, and some preliminary results on the decay of 217Pa decay are presented.

Published
2008
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10. Quest for the $^{10}$He nucleus

Author

A. M. Rodin, A. S. Fomichev, V. A. Kuzmin, S. V. Stepantsov, A. V. Gorshkov, A.A. Korsheninnikov, E. Yu. Nikolskii, S. A. Krupko, Yu. Ts. Oganessian, F. Hanappe, D. N. Stepanov, B. G. Novatskii, O. Dorvaux, V. Bouchat, M. S. Golovkov, L. Stuttge, V. A. Gorshkov, V. Kinnard, S. I. Sidorchuk, R. S. Slepnev, V. Chudoba, G.M. Ter-Akopian, W. Mittig, P. Roussel-Chomaz, R. Wolski, Th. Materna, L. V. Grigorenko, Joint Institute for Nuclear Research (JINR), RIKEN Nishina Center for Accelerator-Based Science [Wako] (RIKEN RNC), RIKEN - Institute of Physical and Chemical Research [Japon] (RIKEN), Grand Accélérateur National d'Ions Lourds (GANIL), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Département Recherches Subatomiques (DRS-IPHC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Joint Institute for Nuclear Research - Dubna, RIKEN Nishina Center (for Accelerator-Based Science), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Resolution (mass spectrometry), 010308 nuclear & particles physics, General Physics and Astronomy, Resonance, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Coincidence, Nuclear physics, medicine.anatomical_structure, 0103 physical sciences, Mass spectrum, medicine, General Materials Science, Center of mass, Physical and Theoretical Chemistry, Atomic physics, 010306 general physics, Nuclear Experiment, Nucleus
Abstract

The spectrum of $\rm ^He$ was studied by means of the $\rm ^He, p)^He$ reaction at a laboratory energy of 25 $\rm MeV/A$ and small center-of-mass angles. Missing mass spectrum of $\rm ^He$ was derived from the obtained p-8He coincidence. A resolution of 0.7 MeV was achieved in this spectrum for the measured $\rm ^He$ energy. Most likely, a well isolated group of 10 events detected between 2 and 5 MeV and showing a maximum at about 3 MeV in the spectrum of the present work exhibits the $\rm ^He$ g.s. resonance.

Published
2008
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11. Angular Correlations Between Fragment Spin and Prompt Neutron Evaporation in Spontaneous Fission of 252Cf: CORA-Demon Experiment

Author

E. Prokhorova, F. Gönnenwein, Yu. Kopatch, M. Mutterer, F. Hanappe, V. Kinnard, L. Stuttgé, O. Dorvaux, H.-J. Wollersheim, Yu. E. Penionzhkevich, E. A. Cherepanov, Département Recherches Subatomiques (DRS-IPHC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), and Yu. E. Penionzhkevich, E. A. Cherepanov

Subjects
25.85.Ca, 25.70.Pq, 23.20.En, 21.10.Gv, Cold fission, cadmium, Fission, Neutron emission, Astrophysics::High Energy Astrophysical Phenomena, Double ionization, Nuclear Theory, 02 engineering and technology, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear physics, spontaneous fission, Prompt neutron, 0202 electrical engineering, electronic engineering, information engineering, Neutron, Nuclear Experiment, angular correlation techniques, Spontaneous fission, Physics, Cluster decay, nuclei with mass number 220 or higher, neutrons, 020206 networking & telecommunications, nuclear fragmentation, 020201 artificial intelligence & image processing, Atomic physics
Abstract

International audience; A novel method to search for the anisotropic emission of prompt neutrons in the center-of-mass system of fission fragments is presented. The anisotropy is conjectured to be due to the large spins of fission fragments are known to carry. Triple neutron- neutron-fragment correlations in spontaneous fission of $^{252}$Cf were investigated in an exploratory experiment dubbed CORA-DEMON experiment. Fission fragments were intercepted in a double ionization chamber while neutrons were spotted in 2 two-dimensional cylindrical walls of Demon detectors with the target on the vertical cylinder axis. A new method of analysis of triple angular correlations between 2 neutrons and a fission fragment was applied. Preliminary results are reported.

Published
2007
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12. High-energy two-neutron removal fromBe10

Author

J. C. Angélique, Yannick Kerckx, N. M. Clarke, Mihai Horoi, Th. Materna, N. Curtis, F. Carstoiu, Shenaz Ahmed, D. J. Millener, N. I. Ashwood, C. N. Timis, J.L. Lecouey, N. A. Orr, Martin Freer, V. A. Ziman, F. M. Marqués, F. Hanappe, S.D. Pain, Neven Soić, W. N. Catford, G. Normand, V. Bouchat, and A. Unshakova

Subjects
Physics, Nuclear and High Energy Physics, education.field_of_study, Population, 01 natural sciences, Excited state, 0103 physical sciences, Quasiparticle, Neutron, Born approximation, Atomic physics, Nuclear Experiment, 010306 general physics, Nucleon, Ground state, education, 010303 astronomy & astrophysics, Energy (signal processing)
Abstract

A kinetically complete measurement of the $^{12}\mathrm{C}$($^{10}\mathrm{Be}$, $\ensuremath{\alpha}+\ensuremath{\alpha}+n$) and ($^{10}\mathrm{Be}$, $\ensuremath{\alpha}+\ensuremath{\alpha}$) reactions has been performed at a beam energy of 30 MeV/nucleon. The charged beam velocity particles were detected in an array of Si-CsI detectors placed at zero degrees, and the neutrons in an 81-element neutron array. The coincident detection of the final-state particles, produced in the breakup of $^{10}\mathrm{Be}$, allowed the reconstruction of the excitation energy in the $^{8}\mathrm{Be}$ and $^{9}\mathrm{Be}$ systems. States in $^{8}\mathrm{Be}$ were identified, in particular the ground and first-excited states; and in $^{9}\mathrm{Be}$, states at 1.68, 2.43, and (2.78, 3.05) MeV were observed. The population of these levels, in particular the 2.43 MeV $5/{2}^{\ensuremath{-}}$ level, suggests that collective excitations play an important role in the neutron removal process. Distorted wave Born approximation and Glauber-type calculations have been used to model the direct neutron removal from the $^{10}\mathrm{Be}$ ground state and the two-step removal via inelastic excitations of the $^{10}\mathrm{Be}$(2${}^{+}$) and $^{9}\mathrm{Be}(5/{2}^{\ensuremath{-}})$ excited states.

Published
2005
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13. Neutron removal and cluster breakup ofB14andBe14

Author

M. Labiche, F. Hanappe, V. A. Ziman, L. Stuttge, N. M. Clarke, F. M. Marqués, Alain Ninane, C. N. Timis, Martin Freer, W. N. Catford, V. Bouchat, S.D. Pain, N. A. Orr, Yannick Kerckx, Neven Soić, G. Normand, N. I. Ashwood, J. L. Lecouey, A. Unshakova, Th. Materna, J. C. Angélique, O. Dorvaux, and N. Curtis

Subjects
Physics, Nuclear and High Energy Physics, Nuclear Theory, Cluster (physics), Neutron, Atomic physics, Nuclear Experiment, Ground state, Nucleon, Breakup, Excitation
Abstract

Measurements of the neutron removal and cluster breakup cross sections for the neutron-rich nuclei $^{14}\mathrm{Be}$ and $^{14}\mathrm{B}$ have been performed at 34.4 and $40.8\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}∕\mathrm{nucleon}$, respectively. Enhancement of the first chance cluster breakup cross section for $^{14}\mathrm{Be}$ compared to that of $^{14}\mathrm{B}$ provides evidence for a well-developed $\mathrm{He}$ cluster structure of the ground state of $^{14}\mathrm{Be}$. Measurements of both the cross sections and decay-particle velocities suggest that multistep processes play an important role in the excitation and decay of both $^{14}\mathrm{B}$ and $^{14}\mathrm{Be}$.

Published
2004
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14. Breakup reaction studies ofBe10andB10,11using aBe10beam

Author

N. Curtis, Th. Materna, W. N. Catford, Neven Soić, F. Hanappe, V. Bouchat, C. N. Timis, J. C. Angélique, Shenaz Ahmed, N. A. Orr, Steven D. Pain, V. A. Ziman, F. M. Marqués, J. C. Lecouey, N. M. Clarke, A. Unshakova, N. I. Ashwood, Alain Ninane, Martin Freer, and G. Normand

Subjects
Physics, Nuclear and High Energy Physics, education.field_of_study, Proton, Excited state, Population, Production (computer science), Atomic physics, Inelastic scattering, Nuclear Experiment, education, Ground state
Abstract

The structure of $^{10}\mathrm{Be}$ has been investigated by inelastic scattering to states above the breakup threshold using the reaction $^{12}\mathrm{C}(^{10}\mathrm{Be},^{10}\mathrm{Be}^{*}\ensuremath{\rightarrow}^{6}\mathrm{He}+^{4}\mathrm{He})^{12}\mathrm{C}$ at ${E}_{\mathit{beam}}=302\phantom{\rule{0.3em}{0ex}}\text{MeV}$. Excited states in $^{10}\mathrm{Be}$ were observed at $9.6\ifmmode\pm\else\textpm\fi{}0.1$ and $10.2\ifmmode\pm\else\textpm\fi{}0.1\phantom{\rule{0.3em}{0ex}}\text{MeV}$. No evidence was observed for the population of the ${4}^{+}$ member of the ground-state band of $^{10}\mathrm{Be}$ indicating the shell-model-like structure of the ground state. In addition, the decay of $^{8}\mathrm{Be}$, $^{10}\mathrm{B}$, and $^{11}\mathrm{B}$, populated in the two-neutron, proton pickup, breakup and $1p$ pickup reactions, was reconstructed through the detection of coincident $^{4}\mathrm{He}+^{4}\mathrm{He}$, $^{4}\mathrm{He}+^{6}\mathrm{Li}$, and $^{4}\mathrm{He}+^{7}\mathrm{Li}$ particles. Cross sections for the formation of the $^{8}\mathrm{Be}$, $^{9}\mathrm{Be}$, $^{10}\mathrm{B}$, and $^{11}\mathrm{B}$ were also deduced. Contrary to expectations, the two-neutron removal results in the production of $^{8}\mathrm{Be}$ predominantly $(80%)$ in the first excited $({2}^{+})$ state. This suggests that dynamical excitations play an important role in the neutron removal process.

Published
2004
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15. Observation of excited states in $^5$H

Author

Yu. I. Vinogradov, S. I. Sidorchuk, R. Palit, A. A. Korsheninnikov, V. Bouchat, A. A. Bogatchev, L. Stuttge, V. Kinnard, A. S. Fomichev, O. Dorvaux, L. V. Grigorenko, M. S. Golovkov, V. V. Perevozchikov, E. Yu. Nikolskii, N. A. Kondratiev, A. M. Rodin, R. Wolski, M. G. Itkis, G. M. Ter-Akopian, V. Lapoux, F. Hanappe, S. V. Stepantsov, C. Angulo, L. Nalpas, S. A. Krupko, P. Roussel-Chomaz, W. Mittig, R. S. Slepnev, A. A. Yukhimchuk, R. Raabe, Yu. Ts. Oganessian, E. M. Kozulin, Th. Materna, S. V. Zlatoustovskiy, S. K. Grishechkin, RIKEN Nishina Center for Accelerator-Based Science [Wako] (RIKEN RNC), RIKEN - Institute of Physical and Chemical Research [Japon] (RIKEN), Grand Accélérateur National d'Ions Lourds (GANIL), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and RIKEN Nishina Center (for Accelerator-Based Science)

Subjects
Physics, 010308 nuclear & particles physics, Hadron, General Physics and Astronomy, 27.10.+h. 25.10.+s, 24.50.+g. 25.55.Hp, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, 01 natural sciences, Charged particle, Spectral line, Baryon, Excited state, 0103 physical sciences, Mass spectrum, Physics::Accelerator Physics, Atomic physics, Nuclear Experiment, 010306 general physics, Ground state, Nucleon
Abstract

The 5H system was produced in the 3H(t,p)5H reaction studied with a 58 MeV tritium beam at small c.m. angles. High statistics data were used to reconstruct the energy and angular correlations between the 5H decay fragments. A broad structure in the 5H missing mass spectrum showing up above 2.5 MeV was identified as a mixture of the 3/2+ and 5/2+ states. The data also present evidence that the 1/2+ ground state of 5H is located at about 2 MeV.

Published
2004
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16. Fusion-Fission Dynamics of Superheavy Nuclei by the Fluctuation-Dissipation Model

Author

Louise Stuttge, Th. Materna, Masahisa Ohta, Yoshihiro Aritomo, and F. Hanappe

Subjects
Physics, Nuclear physics, Langevin equation, Mass distribution, Fission, Neutron emission, Scientific method, Nuclear Theory, Dynamics (mechanics), Physics::Atomic and Molecular Clusters, Trajectory, Dissipation, Nuclear Experiment
Abstract

We discuss the fusion-fission process in superheavy mass region. By analyzing the mass distribution of fission fragments, we can distinguish between fusion-fission process and quasi-fission process. We investigate the process using the fluctuation-dissipation model and employ the three-dimensional Langevin equation. We find a lot of mass symmetric fission events come from the quasi-fission process in the superheavy mass region. In order to classify the fusion-fission paths and compare with the experimental data directly, we analyze the pre-scission neutron emission in the correlation with the fission fragments. The neutron multiplicity depends on the travelling time of the trajectory. It is useful to investigate the fusion-fission process.

Published
2004
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17. Helium Clustering in Neutron-Rich Be Isotopes

Author

M. Freer, N. Curtis, Roy Crawford Lemmon, G. Normand, Th. Materna, V. Bouchat, B. R. Fulton, V. A. Ziman, Alain Ninane, J. C. Angélique, W. N. Catford, O. Dorvaux, N. A. Orr, Shenaz Ahmed, Yannick Kerckx, F. Hanappe, A. Unshakova, C. N. Timis, J.L. Lecouey, Neven Soić, N. I. Ashwood, F. M. Marqués, J. S. Winfield, L. Stuttge, S.D. Pain, M. Labiche, N. M. Clarke, Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), and Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nuclear and High Energy Physics, Isotopes of germanium, Isotopes of samarium, Knockout, Nuclear Theory, FOS: Physical sciences, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Isotopes of oxygen, Clustering, Nuclear physics, Breakup, Cross-sections, Anti-symmetrized Molecular Dynamics, Beryllium, Isotopes of protactinium, 0103 physical sciences, Physics::Atomic Physics, Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment, Physics, 010308 nuclear & particles physics, Isotopes of argon, Physique atomique et nucléaire, Isotopes of nitrogen, Atomic physics, Isotopes of beryllium, s-process
Abstract

Measurements of the helium-cluster breakup and neutron removal cross-sections for neutron-rich Be isotopes 10-12,14Be are presented. These have been studied in the 30 to 42 MeV/nucleon energy range where reaction measurements are proposed to be sensitive to the cluster content of the ground-state wave-function. These measurements provide a comprehensive survey of the decay processes of the Be isotopes by which the valence neutrons are removed revealing the underlying α-α core-cluster structure. The measurements indicate that clustering in the Be isotopes remains important up to the drip-line nucleus 14Be and that the dominant helium-cluster structure in the neutron-rich Be isotopes corresponds to α-Xn-α. © 2003 Published by Elsevier B.V., SCOPUS: ar.j, info:eu-repo/semantics/published

Published
2003
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18. Fission dynamics in the proton induced fission of heavy nuclei

Author

D. N. Vakhtin, S. Khlebnikov, I. M. Itkis, V.A. Rubchenya, V.G. Lyapin, G. N. Kniajeva, F. Hanappe, W. Trzaska, M. G. Itkis, I. V. Pokrovski, O. Dorvaux, J. Kliman, N. A. Kondratiev, Th. Materna, L. Krupa, V.M. Voskressenski, E. M. Kozulin, L. Stuttge, G. G. Chubarian, Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), and Heyd, Yvette

Subjects
Nuclear reaction, Physics, Nuclear and High Energy Physics, Cluster decay, Proton, Mass distribution, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Fission, Nuclear Theory, Shell (structure), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Kinetic energy, Spectral line, Nuclear physics, Atomic physics, Nuclear Experiment
Abstract

Multi-parameter correlation study of the reaction 242 Pu(p, f) at E p = 13, 20 and 55 MeV has been carried out. Fission fragment mass and kinetic energy distributions and the double differential neutron spectra have been measured. It was observed that the two-humped shape of mass distributions prevailed up to highest proton energy. Manifestation of the nuclear shell Z = 28 near fragment mass A fr = 70 has been detected. The experimental results were analyzed in the framework of a time-dependent statistical model with inclusion of nuclear friction effects in the fission process. The multi-parameter correlation study of the reaction.

Published
2003

19. Evidences for resonances states in $^{5}$H

Author

A. M. Rodin, A. S. Fomichev, S. K. Grishechkin, Yu. I. Vinogradov, M. G. Itkis, S. V. Zlatoustovskiy, N. Alamanos, F. Hanappe, A. M. Demin, A. A. Yukhimchuk, G.M. Ter-Akopian, A. V. Kuryakin, Alain Ninane, Yu. Ts. Oganessian, A.A. Korsheninnikov, M. S. Golovkov, E. M. Kozulin, A. A. Bogatchev, E. C. Pollacco, E. Yu. Nikolskii, M. L. Chelnokov, S. V. Stepantsov, R.I Il'kayev, L. Nalpas, V. V. Perevozchikov, I. V. Korzyukov, N. A. Kondratiev, P. Roussel-Chomaz, R. Wolski, Th. Materna, V. Lapoux, L. Stuttge, W. Mittig, R. S. Slepnev, Isao Tanihata, V. A. Gorshkov, S. I. Sidorchuk, S. V. Filchagin, D. D. Bogdanov, Grand Accélérateur National d'Ions Lourds (GANIL), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Triple coincidence, Physics, Nuclear and High Energy Physics, Proton, Nuclear Theory, Two-neutron transfer reaction, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Resonance (particle physics), Physique atomique et nucléaire, Nuclear physics, Mass spectrum, Physics::Accelerator Physics, Neutron, Tritium, Tritium target, Atomic physics, Tritium beam, Nuclear Experiment, Beam (structure)
Abstract

Resonance states of 5H were investigated through the two-neutron transfer reaction t(t, p)5 H. A triton beam at 57.5 MeV and a cryogenic liquid tritium target were used. The 5H missing mass spectrum in triple coincidence, proton + triton + neutron, shows a resonance at 1.8 ± 0.1 MeV above the t + 2n decay threshold. This energy is in good agreement with the result reported in Phys. Rev. Lett. 87 (2001) 092501. The resonance width, Γintr ≤ 0.5 MeV, is surprisingly small and difficult to reconcile with theory predictions. © 2003 Published by Elsevier B.V., SCOPUS: ar.j, info:eu-repo/semantics/published

Published
2003
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20. Probing fission time scales with neutrons and GDR gamma rays

Author

M. L. Halbert, V. S. Salamatin, A. Bacak, A. Huck, E. de Goes Brennand, I. V. Pokrovsky, M. G. Itkis, B. Hurst, R. L. Varner, Yu. Ts. Oganessian, E. M. Kozulin, N. Gan, T. Botting, M. Hamelin, N. A. Kondratiev, J. R. Beene, K.L. Wolf, G. G. Chubarian, F. Hanappe, L. Stuttge, H. Jabs, E. Liatard, R.P. Schmitt, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Nuclear and High Energy Physics, Cluster decay, 010308 nuclear & particles physics, Fission, Astrophysics::High Energy Astrophysical Phenomena, Detector, Nuclear Theory, Gamma ray, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, 01 natural sciences, Atomic and Molecular Physics, and Optics, Coincidence, Nuclear physics, Nuclear fission, Cascade, 0103 physical sciences, Neutron, 010306 general physics, Nuclear Experiment
Abstract

The time scales for nuclear fission have been explored using both pre- and postfission neutrons and GDR gamma rays. Four systems were investigated: 133-MeV /sup 16/O+/sup 176/Yb and /sup 208/Pb and 104-MeV /sup 4/He+/sup 188/Os and /sup 209/Bi. Fission fragments were measured in coincidence with PPACs. The neutrons were detected using eight detectors from the DEMON array, while gamma rays were measured using the US BaF/sub 2/ array. The pre- and postfission gamma rays were determined using moving source fits parallel and perpendicular to the fission fragment emission directions. The time scales for fission for the neutrons were determined using the neutron clock technique. The gamma-ray data were fitted using a statistical model calculation based on the code CASCADE. The results of the fits from both data types were used to extract nuclear friction coefficients, gamma , and fission time scales. The gamma values ranged from 7 to 20, while the fission times were (31-105)*10/sup -21/s.

Published
2003
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21. Detection of neutron clusters

Author

M. Freer, F. de Oliveira Santos, Thomas Nilsson, Graziele De Sousa Costa, S. P. G. Chappell, B. R. Fulton, N. A. Orr, J. C. Angélique, Fred Sarazin, O. Dorvaux, Karin Markenroth, Leif Axelsson, K. Riisager, S. Grévy, G. Giardina, N. M. Clarke, M. J. G. Borge, Giovanni Fazio, D. Guillemaud-Mueller, B. Heusch, Gunnar Nyman, B. Benoit, Alain Ninane, F. M. Marqués, M. G. Saint Laurent, U. C. Bergmann, E. de Goes Brennand, F. Hanappe, A.C. Mueller, I. Piqueras, M. J. Lopez, S. Leenhardt, L. Stuttge, M. Labiche, N. Curtis, M. Lewitowicz, W. N. Catford, O. Sorlin, C. Le Brun, Björn Jonson, A. D'Arrigo, S. M. Singer, Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Grand Accélérateur National d'Ions Lourds (GANIL), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)

Subjects
Physics, Nuclear and High Energy Physics, Proton, 010308 nuclear & particles physics, Nuclear Theory, Scintillator, Few-body systems, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Breakup, 01 natural sciences, 3. Good health, Nuclear physics, 0103 physical sciences, Tetraneutron, Cluster (physics), Neutron, [PACS]Few-body systems, [PACS]Nucleon distributions and halo features, Nuclear Experiment, 010306 general physics, Nucleon, [PACS]Nuclear reactions involving few-nucleon systems
Abstract

10 pages, 2 tables, 13 figures.--PACS nrs.: 21.45.1v, 25.10.1s, 21.10.Gv.--ArXiv pre-print available at: http://arxiv.org/abs/nucl-ex/0111001, A new approach to the production and detection of bound neutron clusters is presented. The technique is based on the breakup of beams of very neutron-rich nuclei and the subsequent detection of the recoiling proton in a liquid scintillator. The method has been tested in the breakup of intermediate energy (30-50 MeV/nucleon) Li-11, Be-14, and B-15 beams. Some six events were observed that exhibit the characteristics of a multineutron cluster liberated in the breakup of Be-14, most probably in the channel Be-10+(4)n. The various backgrounds that may mimic such a signal are discussed in detail., This work was funded under the auspices of the IN2P3-CNRS (France) and EPSRC (United Kingdom). Additional support from the ALLIANCE program (Ministère des Affaires Etrangères and British Council) and the Human Capital and Mobility Program of the European Community (Contract No. CHGE-CT94-0056) is also acknowledged.

Published
2002
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22. Effects of shell structure in reactions leading to the same compound nucleus or different isotopes

Author

A. K. Nasirov, G. Fazio, G. Giardina, A. Lamberto, R. Ruggeri, A. Taccone, A. I. Muminov, F. Hanappe, R. Palamara, L. Stuttg'e, Heyd, Yvette, Institut de Recherches Subatomiques (IReS), and Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nuclear Theory, Isotope, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Chemistry, FOS: Physical sciences, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Theory (nucl-th), medicine.anatomical_structure, Chemical physics, medicine, Nuclear Experiment (nucl-ex), Nuclear Experiment, Nuclear theory, Nucleus
Abstract

The role of the entrance channel in fusion-fission reactions was studied by the theoretical analysis of the experimental evaporation residue excitation functions for reactions leading to the same compound nucleus. The evaporation residues cross sections for xn-channels were calculated in the frame of the combined dinuclear system concept and advanced statistical model. The revealed differences between experimental data on the evaporation residues in the ^{40}Ar+^{176}Hf, ^{86}Kr + ^{130}Xe and ^{124}Sn + ^{92}Zr reactions leading to the ^{216}Th^* compound nucleus are explained by the different spin distributions of compound nuclei which are formed. It is shown that the intrinsic fusion barrier B^*_{fus} and size of potential well are different for every entrance channel., Comment: 14 pages, 5 EPS figures, Latex, ws-p8-50x6-00.cls is used, Talk given at the Conference NPBL2001, Lipari (Messina, Italy), 21-24 May, 2001

Published
2001
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23. Production of Super Heavy Elements at GANIL: Present Status and Perspectives

Author

N. Alamanos, A. Wieloch, M. G. Saint-Laurent, T Legou, F Hanappe, J. C. Angélique, N. A. Orr, F. Becker, Rubens Lichtenthäler, E Lienard, G. Auger, R. de Tourreil, G. Politi, R. Anne, F. de Oliveira, R. Hue, J.P. Wieleczko, A. Drouart, N. Amar, D. Guerreau, J Tillier, A. Gillibert, C. Stodel, A. S. Lalleman, J. C. Steckmeyer, S. Grévy, Zbigniew Sosin, R. Dayras, W. Mittig, A. C. C. Villari, J M Fontbonne, Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Grand Accélérateur National d'Ions Lourds (GANIL), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), FULIS, Lion, Michel, Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Silicon, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], 010308 nuclear & particles physics, High intensity, Detector, FOS: Physical sciences, chemistry.chemical_element, Transactinide element, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, 7. Clean energy, Ion, Nuclear physics, chemistry, 0103 physical sciences, Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment, Beam (structure)
Abstract

Experiments on the production and study of superheavy nuclei have been undertaken at GANIL taking advantages of the powerful velocity filter LISE3 and the high intensity ECR ion sources. A complete set-up has been built: - reaction chamber containing large rotating wheels, - slits and beam profiler at mid-filter, - detection chamber with time-of-flight and Silicon detectors for identifying evaporation residues and their decay products. The response was checked via fusion reactions with known cross sections producing known alpha-decay chains and fission fragments. Excellent transmission of evaporation residues and rejection factor for the primary beam were obtained. This device is presented together with the results obtained in our last experiments and our future plans are discussed., proceeding to the ASR2001 Conference, Tokai, Japan, november 2001, to be published in the Journal of Nuclear and Radiiochemical Sciences (june 2002)

Published
2001

24. Two-neutron correlations at small relative momenta in ^40Ar + ^197Au collisions at 60 MeV/nucleon

Author

B. Tamain, K. Wosinska, A. Stavinskiy, O. Dorvaux, K. Miller, A. Staranowicz, M. Przewlocki, B. Norén, J. Pluta, P. Désesquelles, C. Lebrun, B. Erazmus, P. Leszczynski, Bo Jakobsson, T. Pawlak, G. Bizard, K. Mikhailov, R. Lednicky, F.R. Lecolley, F. Hanappe, D. Durand, Ö. Skeppstedt, B. Benoit, L. Stuttge, Zoran Basrak, Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Laboratoire SUBATECH Nantes (SUBATECH), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Nantes (UN)-Mines Nantes (Mines Nantes), Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS), Mines Nantes (Mines Nantes)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)

Subjects
010302 applied physics, Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Nuclear Theory, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, 01 natural sciences, Spectral line, Nuclear physics, Correlation function (statistical mechanics), 0103 physical sciences, nuclear physics, heavy ions, neutron interferometry, Neutron, Nucleon, Nuclear Experiment
Abstract

Two-neutron correlation functions are measured in the 40Ar + 197Au reaction at 60 MeV/nucleon to study the space-time characteristics of neutron emitting sources. The source temperatures and velocities are deduced by fitting the single-neutron energy spectra with a three-source model. A comparison of the correlation data with the predictions of the model of moving sources and with the dynamical Landau-Vlasov model suggests the relevance of a multisource description. Particular care has been paid to the influence of the relative source abundance on the shape of the correlation function.

Published
2000

25. Angular momentum effects in multimodal fission of

Author

B. Hurst, G. Bellia, K. Lukashin, C. Agodi, V.V. Pashkevich, Yu. Ts. Oganessian, E. M. Kozulin, G. Chubarian, M. G. Itkis, Luciano Calabretta, C. Maiolino, A. Huck, E. Liatard, F. Hanappe, N. A. Kondratiev, I. V. Pokrovsky, D. O’Kelly, V. S. Salamatin, A. Ya. Rusanov, R.P. Schmitt, and L. Stuttge

Subjects
Nuclear physics, Angular momentum, Fission products, Cluster decay, Chemistry, Fission, Neutron emission, Saddle point, Nuclear Theory, Mass spectrum, Nuclear Experiment, Excitation
Abstract

The γ-rays from the multimodal fission of the 226Th formed in 18O+208Pb was investigated at the near- and sub-barrier energies. The corresponding excitation energies at the saddle point, Esp*, ranged from 23 to 26 MeV. The average γ-ray multiplicities and relative γ-ray energies as a function of the mass of the fission fragments exhibits a complex structure and strong variations. Such strong variations have never been previously observed in heavy ion-induced fusion-fission reactions. Obtained results may be explained with the influence of shell effects on the properties of the fission fragments. Present work is the one in series of investigation of the multimodal fission phenomena in At-Th region.

Published
1998
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26. Observation of fission modes in heavy ion induced reactions

Author

K. Lukashin, Yu. Ts. Oganessian, E. M. Kozulin, E. Liatard, C. Agodi, L. Stuttge, D. O’Kelly, A. Huck, A. Ya. Rusanov, R.P. Schmitt, V. S. Salamatin, I. V. Pokrovsky, M. G. Itkis, V.V. Pashkevich, F. Hanappe, Luciano Calabretta, B. Hurst, G. Bellia, C. Maiolino, N. A. Kondratiev, and G. Chubarian

Subjects
Mass distribution, Isotope, Chemistry, Fission, Excited state, Saddle point, Nuclear structure, Mass spectrum, Atomic physics, Nuclear Experiment, Excitation
Abstract

The fission of the systems 220,224,226Th was investigated by measuring the mass-energy distributions of the fission fragments. The corresponding excitation energies at the saddle point, Esp*, ranged from 16 to 40 MeV. As Esp* decreases, an asymmetric mass component becomes visible on the predominately symmetric mass distribution. The contribution of the asymmetric mode is characterized by the total yield ratio Ys/Ya, which decreases rapidly for the heavier isotopes of thorium. This behavior of Ys/Ya is in qualitative agreement with theoretical calculations. For all isotopes studied, the subtracted asymmetric fission component, Ya=Y1−Ys, exhibits a complex structure, actually showing two components, Ya=Ya1+Ya0, which have average masses Ma1=132 and Ma0=140.

Published
1998
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27. Exotic molecular and halo states in

Author

S. Leenhardt, B. Heusch, M. Labiche, M. Motta, F. Hanappe, M. G. Saint Laurent, Alain Ninane, C. Gregori, U. C. Bergmann, F. D’Oliviera, L. Stuttge, Thomas Nilsson, E. de Goes Brennard, Martin Freer, S. P. G. Chappell, Leif Axelsson, Björn Jonson, K. Riisager, M. J. G. Borge, Gunnar Nyman, D. L. Watson, O. Sorlin, A. D'Arrigo, J. T. Murgatroyd, S. M. Singer, I. Piqueras, A.C. Mueller, N. A. Orr, C. Le Brun, Graziele De Sousa Costa, S. Grévy, B. R. Fulton, D. Guillemaud-Mueller, J. C. Angélique, O. Dorvaux, W. N. Catford, Karin Markenroth, N. M. Clarke, B. Benoit, N. Curtis, F. Sarazin, G.R. Kelly, F. M. Marqués, G. Gardina, and M. Lewitowicz

Subjects
Physics, Spins, Nuclear Theory, chemistry.chemical_element, Breakup, 3. Good health, Helium-4, chemistry, Excited state, Neutron, Halo, Atomic physics, Nuclear Experiment, Spin (physics), Helium
Abstract

The two nuclei 12Be and 14Be have been studied using breakup reactions on p, 12C and 208Pb targets. The decay of 12Be into two helium clusters (6He+6He and 4He+8He) was observed from a series of excited states between 10 and 25 MeV, with spins in the range 4+ to 8+. The single neutron angular distributions for 14Be exhibit the narrow forward peak characteristic of a halo. The widths of these distributions in coincidence with 12Be fragments are ΓL = 78±6 and 80±1 MeV/c for breakup on carbon and lead.

Published
1998
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28. Deuteron stripping on beryllium target in the 100-2300 MeV energy range

Author

J.C. Duchazeaubeneix, S. Ménard, S. Leray, Y. Patin, Esteban Martínez, A. Boudard, F. Lefebvres, L. Stuttge, C. Varignon, J.E. Thun, F. Hanappe, M. Louvel, C. Le Brun, F. Borne, X. Ledoux, François-René Lecolley, Y. Terrien, J. Fréhaut, J.F. Lecolley, R. Legrain, G. Milleret, J.M. Durand, Dominique Durand, P. Pras, Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Nuclear and High Energy Physics, Nuclear Theory, Hadron, chemistry.chemical_element, 02 engineering and technology, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 010402 general chemistry, 021001 nanoscience & nanotechnology, 7. Clean energy, 01 natural sciences, Dissociation (chemistry), 0104 chemical sciences, Nuclear physics, chemistry, Deuterium, Nuclear fusion, Beryllium, Atomic physics, Nuclear Experiment, 0210 nano-technology, Nuclear Physics
Abstract

Cross sections for stripping and dissociation of deuterons interacting with Be targets in the 100–2300 MeV energy range have been measured. Comparisons with model calculations suggest a dominant contribution of the stripping process. It is also shown that the deuteron break-up cross section exhibits the same energy dependence as the nucleon-nucleon cross section.

Published
1998

29. Energy relaxation time in heavy ion collisions between 27 and 44 mev/u

Author

G. Mamane, M. Dakowski, Hiroaki Utsunomiya, Y. El Masri, C. Cabot, D. Jouan, M.F. Rivet, F. Hanappe, Bernard Borderie, D. Gardes, P. Box, X. Tarrago, Institut de Physique Nucléaire d'Orsay (IPNO), and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)

Subjects
Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Nuclear Theory, Binary number, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Energy sharing, Nuclear physics, 0103 physical sciences, Dissipative system, Nuclear fusion, Heavy ion, Atomic physics, Nuclear Experiment, 010306 general physics, Separation time, Excitation, Energy (signal processing), Nuclear Physics
Abstract

The excitation energy sharing between the two partners of binary dissipative collisions was derived for the Ar-40 + Ag-nat system at 27 and 44 MeV/u. From the eventual equilibration of energy between the two partners, and their separation time obtained from Landau-Vlasov simulations, the energy relaxation time was extracted, and compared with theoretical predictions.

Published
1997

30. Neutrons from the breakup of $^{19}$C

Author

P. G. Hansen, E. Liegard, M. H. Smedberg, G. Bizard, D. Guillemaud-Mueller, W. N. Catford, F. M. Marqués, B. Heusch, Y. Schutz, M. G. Saint-Laurent, G. Martınez, N. A. Orr, A.C. Mueller, D. D. Warner, F. Hanappe, Björn Jonson, M. Lewitowicz, Thomas Nilsson, Alain Ninane, J. C. Angélique, Leif Axelsson, C. Le Brun, Martin Freer, O. Sorlin, K. Riisager, Göran Hugo Nyman, G. J. Gyapong, L. Stuttge, F. Pougheon, B. Petersen, F. Lefebvres, N. M. Clarke, François-René Lecolley, S. Grévy, G.J. Costa, Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Laboratoire SUBATECH Nantes (SUBATECH), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Nantes (UN)-Mines Nantes (Mines Nantes), Grand Accélérateur National d'Ions Lourds (GANIL), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Mines Nantes (Mines Nantes)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Nuclear Theory, Tantalum, chemistry.chemical_element, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Breakup, 01 natural sciences, Momentum, Nuclear physics, chemistry, Reaction model, 0103 physical sciences, Neutron, Halo, Atomic physics, Nuclear Experiment, 010306 general physics, Nucleon, Beam (structure)
Abstract

Neutrons arising from the breakup of a 30 MeV/nucleon C-19 beam on a tantalum target have been measured using the 98 element array DEMON. A narrow, forward peaked neutron angular distribution, with a corresponding momentum spread considerably smaller than those measured simultaneously for N-21, O-22 and F-24 was observed for charged fragments with Z < Z(proj). Interpreted in terms of the core-breakup reaction model, the results support the existence of a one neutron halo in C-19.

Published
1996
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31. Rapid decrease of fragment emission time in the range of 3-5 mev/u excitation energy

Author

J.F. Lecolley, A. Péghaire, R. Brou, A. Genoux-Lubain, R. Bougault, S.C. Jeong, J.C. Steckmeyer, F. Saint-Laurent, Y. El Masri, K. Hagel, H. Fugiwara, G. Bizard, R. Regimbart, B. Tamain, M. Louvel, H. Doubre, S. Kato, T. Matsuse, F. Hanappe, D. Durand, G.M. Jin, J.L. Laville, Jean Péter, S.M. Lee, A. Buta, T. Motobayashi, T. Hamdani, C. Le Brun, Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Grand Accélérateur National d'Ions Lourds (GANIL), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), and Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)

Subjects
Physics, Nuclear and High Energy Physics, Range (particle radiation), Excited state, Nuclear Theory, Atomic physics, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment, Excitation, Energy (signal processing)
Abstract

Multifragment emission processes from highly excited nuclei produced in Ar-40+Au-197 reactions at incident energies of 30 and 60 MeV/u are compared. At the lowest bombarding energy and 3.3 MeV/u excitation energy, the composite system decay process supports the hypothesis of long-lived equilibrated nuclei decaying by successive binary splittings. For excited nuclei around 5 MeV/u, the depletion observed at small relative angles in the correlation functions is interpreted as the result of a strong reduction in the fragment emission time scale.

Published
1994
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32. Three fragment sequential decay of heavy nuclei around 3 MeV/u excitation energy

Author

J.C. Steckmeyer, J.P. Patry, H. Fugiwara, R. Bougault, F. Hanappe, K. Hagel, J.L. Laville, R. Regimbart, S. Kato, R. Brou, A. Genoux-Lubain, Y. El-Masri, A. Péghaire, S.M. Lee, J.F. Lecolley, C. Le Brun, G. Bizard, B. Tamain, T. Matsuse, F. Saint-Laurent, H. Doubre, T. Motobayashi, D. Durand, G.M. Jin, Jean Péter, N. Prot, S.C. Jeong, A. Hajfani, M. Louvel, Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Grand Accélérateur National d'Ions Lourds (GANIL), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), and Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)

Subjects
Physics, Nuclear and High Energy Physics, Fragment (logic), Nuclear Theory, Binary number, Atomic physics, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment, Energy (signal processing), Excitation
Abstract

A new method is proposed to identify the sequential decay of hot nuclei into large fragments. This method is based on a minimization procedure. It is illustrated for the Ar + Au reaction at 30 MeV/u. In this case, corresponding to about 3 MeV/u excitation energy, it is shown that the three fragment production can be explained by sequential binary splittings.

Published
1992
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33. Decay of equilibrated very hot nuclei via multifragment emission

Author

Y. El‐Marsi, D. Durand, R. Brou, A. Genoux-Lubain, C. Le Brun, J.P. Patry, J.L. Laville, N. Prot, J. C. Stechmeyer, B. Tamain, G.M. Jin, F. Saint-Laurent, Jean Péter, Suh Lee, A. Péghaire, A. Haifani, S.C. Jeong, T. Motobayashi, T. Matsuse, M. Louvel, F. Hanappe, H. Fugiwara, G. Bizard, J.F. Lecolley, H. Doubre, R. Regimbart, K. Hagel, S. Kato, R. Bougault, Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), and Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)

Subjects
Physics, Nuclear physics, Mass distribution, Nuclear Theory, Atomic physics, Multiplicity (chemistry), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment, Excitation
Abstract

International audience; Coïncidences between at least 3 fragments emitted at large angle have been used to study central collisions in the Ar+Au reactions at 30 and 60 MeV/u incident energies. For both energies, the formation of equilibrated very hot nuclei is evidenced. Excitation energy as high as 1 GeV are reached in the reaction at 60 MeV/u.

Published
1991
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34. Matter distribution in neutron-rich light nuclei and total reaction cross-section

Author

Tsan Ung Chan, J.F. Bruandet, E. Liatard, R. Bimbot, Ch. Heitz, F. Hanappe, G. Costa, D. Guillemaud-Mueller, S. Kox, Y. El Masri, F. Glasser, A.C. Mueller, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)

Subjects
Physics, SIMPLE (dark matter experiment), Isotope, 010308 nuclear & particles physics, Projectile, Nuclear Theory, General Physics and Astronomy, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, 01 natural sciences, Nuclear physics, Cross section (physics), Distribution (mathematics), Isospin, 0103 physical sciences, Neutron, Nuclear drip line, Atomic physics, Nuclear Experiment, 010306 general physics
Abstract

Mean square radii of light radioactive projectiles, including exotic isotopes close to the neutron drip line (11Li, 14Be, and 17B), have been deduced from total reaction cross-section measurements, using a simple microscopic model. The isospin dependence of nuclear radii is discussed and compared to other experimental results.

Published
1990

35. Gamma-ray multiplicity measurements for the determination of the initial angular momentum ranges in normal and fast fission processes

Author

R. Brou, Bernard Tamain, F. Hanappe, J.L. Laville, P. Duhamel, R. Regimbart, V. Martin, B. Borderie, M. Rivet, J.C. Steckmeyer, J. Péter, G. Bizard, Y. El Masri, J.F. Bruandet, H. Fuchs, Tsan Ung Chan, Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nuclear reaction, Physics, Nuclear and High Energy Physics, Angular momentum, Cluster decay, 010308 nuclear & particles physics, Fission, Nuclear Theory, Gamma ray, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Kinetic energy, 7. Clean energy, 01 natural sciences, Fast fission, Nuclear physics, Excited state, 0103 physical sciences, Atomic physics, Nuclear Experiment, 010306 general physics
Abstract

Gamma-ray multiplicities (first and second moments) have been measured, in the 220 MeV 20 Ne + nat Re and 315 MeV 40 Ar+ 165 Ho reactions, as a function of fission fragment masses and centre-of-mass total kinetic energies. The two reactions lead to the same fusion nucleus, 205 At, at the same excitation energy (167 MeV). The experimental critical angular momentum for the fission process in the Ne + Re system (91 ± 3) ℏ is close to l Bf =0 (~80ℏ) while in the Ar + Ho reaction this critical angular momentum (136 ± 4) ℏ is much larger than the l Bf =0 value, favoring the occurrence of the fast fission process. The observed widths of the fission fragment mass distribution: (42 ± 2) u in the Ne + Re system and (56 ± 4) u in the Ar + Ho reaction strengthen this hypothesis. For both compound nucleus fission and fast fission components in Ar + Ho, the total spin values obtained in absolute magnitude and in their dependence on the mass asymmetry are well described by assuming rigid rotation of the fissioning complex and statistical excitation of some collective rotational modes such as “Bending” and “Wriggling” according to the Schmitt-Pacheco model. These modes, however, are not all fully excited, their degrees of excitation are approximately the same for both fission components. From theoretical estimates of equilibration times, one anticipates the “Tilting” mode to be by far the last to be excited, and from its non-excitation in the present data together with the excitation of bending and wriggling, a time interval of about 10 −21 s to 2 × 10 −20 s can be derived for the reaction time of both normal fission and fast fission. The γ-ray multiplicity as a function of the c.m. total kinetic energy decreases in the Ne + Re system, while it increases in the Ar + Ho system even for symmetric splitting, which indicates experimentally for the first time that fast fission populates the whole mass range. This difference between the two reactions is in agreement with the normal-fission-fast-fission distinction in angular momentum space.

Published
1990

36. Fission of medium and heavy nuclei induced by 40Ar from 160 to 300 MeV: average total kinetic energy

Author

F. Hanappe, B. Borderie, C. Ngô, Jean Péter, and B. Tamain

Subjects
Nuclear physics, Physics, Nuclear and High Energy Physics, Fissility, Range (particle radiation), Fission, Nuclear fission, Excited state, Atomic physics, Nuclear Experiment, Kinetic energy, Excitation, Ion
Abstract

The average total kinetic energy of fission fragments for symmetric fission induced by argon ions has been measured over a wide range of fissility parameters. The results are compared with other results, with the predictions of Nix (liquid-drop model) and those of Mosel and Schmitt (two-center model). The shell effects predicted by Mosel and Schmitt are not seen, probably because of the high value of the excitation energies involved in the reactions. The variation of the total kinetic energy with the fissility parameter is rather well described by Nix but the calculated absolute values are too low. It is seems that the fissility parameter (used in the liquid-drop model) rather than the mass of the fissioning nucleus (in the Mosel and Schmitt model), is the important parameter which determines the total fragment kinetic energy of excited nuclei.

Published
1974
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37. Collective modes associated with the proton-induced fission ofBi209

Author

F. Hanappe, B. Borderie, C. Cabot, Michel Berlanger, B. Tamain, L. Nowicki, Youssef El Masri, Charles Grégoire, C. Ngô, and P. Delmarmol

Subjects
Physics, Nuclear reaction, Nuclear and High Energy Physics, Angular momentum, Fission, Nuclear Theory, Inelastic collision, Inelastic scattering, Nuclear physics, Excited state, Atomic physics, Multiplicity (chemistry), Nuclear Experiment, Excitation
Abstract

Gamma-ray multiplicity (first and second moments) has been measured in the 60 MeV proton-induced fission of Bi209. From this work we have evidence that shell effects play an effective role at the scission point, even at an excitation energy of 65 MeV. Collective modes seem to be more easily excited when the nascent fragments are far from spherical shapes. The γ-multiplicity moments seem to depend weakly on excitation energy of the fissioning nucleus and do not really reflect the angular momentum of the entrance channel. The good agreement of our results with the Moretto-Schmitt model highly supports the role played by collective modes (bending) in the heavy ion induced fission and deep inelastic collisions which are presently the field of many recent experimental and theoretical investigations. NUCLEAR REACTIONS p+Bi209; Ep=60 MeV; measured fission fragment mass distribution dNdM; measured γ-ray multiplicity first and second moments Mγ and σγ functions of fragment mass ratios α and ETKE;; measured average γ-ray energy Eγ (α); measured in-plane, out-of-plane Mγα(θ); comparison to s.f. and HI reaction mechanisms and to Moretto-Schmitt model; deduced effects of collective rotational modes (bending) on fragment spins. © 1982 The American Physical Society.

Published
1982
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38. Gamma ray multiplicities in deep inelastic collisions for the Cu + Au 400 MeV system

Author

N. Perrin, J. Kuzminski, F. Hanappe, B. Borderie, D. Chapoulard, B. Tamain, C. Ngô, J. B. Natowitz, Michel Berlanger, and C. Gerschel

Subjects
Nuclear reaction, Nuclear physics, Physics, Nuclear and High Energy Physics, Angular momentum, Hydrogen-like atom, Total angular momentum quantum number, Landé g-factor, Angular momentum coupling, Inelastic collision, Rotational transition, Atomic physics, Nuclear Experiment
Abstract

For the Cu + Au 400 MeV system γ-ray multiplicities have been measured. The mean value of the transferred angular momentum, the variances, and the repartition of angular momentum between the fragments have been deduced. It is shown that, early in the reaction the building up of angular momentum is a very fast process. For longer times, additional angular momentum is induced in the fragments. The excitation of collective modes can account for this effect. The properties of such modes have been analysed.

Published
1982
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39. Neutron multiplicity in deep inelastic collisions: 400 MeV Cu+Au system

Author

M. Dakowski, M. Morjean, R. Chechik, C. Signarbieux, B. Lucas, Jean Péter, C. Ngô, M. Ribrag, H. Fuchs, B. Tamain, F. Hanappe, and C. Mazur

Subjects
Physics, Nuclear and High Energy Physics, Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, Inelastic collision, Neutron multiplicity, Coincidence, Neutron time-of-flight scattering, Nuclear physics, Neutron detection, Neutron, Atomic physics, Nuclear Experiment, Beam (structure), Excitation
Abstract

We have detected in nine different positions of space the neutrons associated with the collision of 63 Cu on 197 Au at 400 MeV bombarding energy. The deep inelastic products were detected at two different angles: close to the grazing angle and 30° forwards of it. Their masses were measured using a time-of-flight technique. The neutrons were detected in coincidence with the fragments - the efficiency of the neutron detectors was measured relatively to a 252 Cf source during beam time. The neutron threshold was set at 300 keV. Within an accuracy of 10% all the emitted neutrons are evaporated by the fully accellerated deep inelastic fragments. It is shown that the excitation energy is shared between the fragments in proportion to their masses and that the relaxation time for internal equilibration of the composite system is very short (∼10 −22 s).

Published
1979
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40. Influence of angular momentum on the mass distribution width of heavy ion induced fission: What is the frontier between fission and quasi-fission?

Author

Jean Péter, J.F. Lecolley, C. Ngô, B. Tamain, F. Lefebvres, F. Hanappe, and C. Lebrun

Subjects
Physics, Nuclear and High Energy Physics, Angular momentum, Cluster decay, Mass distribution, Fission, Nuclear Theory, Rotational transition, Nuclear physics, medicine.anatomical_structure, medicine, Heavy ion, Atomic physics, Nuclear Experiment, Nucleus
Abstract

The 124 and 206 MeV 20 Ne+ nat Re and the 192 and 297 MeV 40 Ar+ 165 Ho systems have been used to form the 205 At nucleus with different angular momentum populations. The mass distributions of the fission fragments have been measured. Removing the effect of the temperature, it has been found that their width strongly increases with angular momentum especially when the fission barrier has vanished.

Published
1979
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41. Gamma ray multiplicity in the quasi-fission of Cu + Au at 443 MeV

Author

M. Leblanc, B. Tamain, J.F. Mayault, M.A. Deleplanque, N. Perrin, C. Gerschel, J. Péter, C. Ngô, F. Hanappe, D. Paya, L. Valentin, Michel Berlanger, Institut de Physique Nucléaire d'Orsay (IPNO), and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)

Subjects
Angular momentum, sticking hypothesis, gamma ray spectra, Fission, degree of inelasticity, nuclei with mass number 190 to 219, Gamma ray spectra, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], angular momentum, gamma ray multiplicity, 01 natural sciences, Nuclear physics, 0103 physical sciences, fission, Multiplicity (chemistry), Nuclear Experiment, 010306 general physics, sup 63 Cu+ sup 197 Au system, Physics, deep inelastic collisions, 010308 nuclear & particles physics, General Engineering, Gamma ray, heavy ion nucleus scattering, nuclei with mass number 59 to 89, [PHYS.HIST]Physics [physics]/Physics archives, 443 MeV, quasifission, Atomic physics
Abstract

We have measured the γ-ray multiplicity associated with the quasi-fission of the system 63Cu + 197Au at 443 MeV lab. energy. Its value increases with the degree of inelasticity. The maximum values are 25 at 35° (corresponding to initial l-waves of about 150 ħ) and 22 at 49° (close to the grazing angle). Taking into account the angular momentum carried away by emitted particles and the deformation of the fragments at the scission point, these values agree with the sticking hypothesis. The possibility of additional angular momentum imparted to the fragments by the quasi-fission process itself is discussed. The γ-multiplicity associated with sequential fission has also been measured.

Published
1976
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42. Study by track detectors of the 580-MeV photofission of U, Au, Te, Ag, Se, Cu and Cr

Author

J. Péter, B.D. Pate, F. Hanappe, F.M. Kiely, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), and Robert, Suzanne

Subjects
Physics, Nuclear and High Energy Physics, Photon, 010308 nuclear & particles physics, Fission, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Theory, Photofission, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, 7. Clean energy, Nuclear physics, 0103 physical sciences, Nuclear fusion, High Energy Physics::Experiment, Mica, Atomic physics, Track detectors, Nuclear Experiment, 010306 general physics
Abstract

The fission of U, Au, Te, Ag, Se, Cu and Cr induced by photons with a maximum energy of 580 MeV has been investigated using mica and glass track detectors in a sandwich configuration. Cross sections for U, Au, Te and Ag fission have been obtained which are in fair agreement with existing data for charged-particle induced fission, but are substantially lower than previous photofission results, obtained by other authors for Te and Ag targets.

Published
1976

43. Evidence for shape deformations of fragments in deep inelastic collisions

Author

C. Mazur, C. Signarbieux, H. Fuchs, B. Lucas, J. Péter, M. Morjean, M. Ribrag, F. Hanappe, M. Dakowski, B. Tamain, and R. Chechik

Subjects
Physics, Nuclear and High Energy Physics, Neutron emission, Nuclear Theory, Inelastic collision, Nuclear fusion, Neutron, Deformation (engineering), Atomic physics, Nuclear Experiment, Spectral line, Energy (signal processing), Excitation
Abstract

The number and energy spectra of neutrons evaporated by the heavy and light fragments in deep inelastic collisions have been obtained for the system 240 MeV40Ar +197Au. They indicate that at the scission point the deformation energy is a large part of the total excitation energy espe cially for the light fragment. In the last two years, neutron emission has been studied in deep inelastic reactions1−6. All the results are similar: the incident energy which is lost during the process is transformed into excitation energy of the final fragments and is shared between the two products proportionnally to their masses. This means that the nuclear temperature was uniform in the composite system. The excitation energy equilibration time is really very short since equilibration is achieved after reaction times as small as 10−22 s2,6. Moreover, no preequilibrium emission (direct neutrons-) has been observed.

Published
1980
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