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Study of fission reactions induced by 4,6He and 7Li beams on 209Bi and 208Pb targets, leading to the production of 210,212A compound nuclei, was performed. It was shown that the fission excitation functions for the three reactions 4,6He + 209Bi and 7Li + 208Pb had similar behavior within the experimental error for a broad range of energy. More likely, halo structure of 6He is not reflected on the fission reaction mechanism. Otherwise, a large value of the fusion cross section was observed so far, as it could be expected in the case of weakly bound character of 6He projectile.

Two fission experiments have been performed at GANIL using 238U beams at different energies and light targets. Different fissioning systems were produced with centre of mass energies from 10 to 240 MeV and their decay by fission was investigated with GANIL spectrometers. Fission-fragment isotopic distributions have been obtained. The evolution with impinging energy of their properties, the neutron excess and the width of the neutron-number distributions, gives important insights into the dynamics of the fusion-fission mechanism.

Two fission experiments have been performed at GANIL using 238U beams at different energies and light targets. Different fissioning systems were produced with excitation energies from 10 to 230 MeV and their decay by fission was investigated with GANIL spectrometers. Preliminary fission-fragment isotopic distributions have been obtained. The evolution with impinging energy of their properties, the neutron excess and the width of the neutron-number distributions, gives important insights into the dynamics of fusion-fission mechanism.

Excitation functions of the reaction products were measured for the reactions induced by 4,6He projectiles on 208,206Pb targets, leading to the same compound nucleus. The excitation functions for the 2n evaporation channels were obtained at energies below the sub-Coulomb barrier region. A large value of the fusion cross section was observed in the case of the reaction induced by the weakly bound 6He projectile. This reflects an unusual mechanism is present in reactions induced by weakly bound nuclei.

Abstract: Excitation functions of the reaction products were measured for the reactions induced by 4,6He projectiles on 208,206Pb targets, leading to the same compound nucleus. This was accomplished by using the stacked-foil activation technique. The identification of the reaction products (accumulated in the Pb targets) was done by their radioactive α-decays. The excitation functions for the various products were obtained at energies including the sub-Coulomb barrier region. A large value of the fusion cross section was observed in the case of the reaction induced by the weakly bound 6He projectile. [Copyright &y& Elsevier]

The neutron drip line in the neon–magnesium region has been explored by the projectile fragmentation of a [sup 48]Ca (59.8 A MeV) beam using the new fragment separator LISE-2000 at GANIL. New neutron-rich isotopes, [sup 34]Ne and [sup 37]Na, have been observed together with some evidence for the particle instability of [sup 33]Ne and [sup 36]Na.© 2003 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

A setup for studying reactions induced by secondary radioactive beams has been constructed. It allows simultaneous measurement of α-particle and fission fragment energy spectra. By measuring the α particles, identification of evaporation residues is achieved. A set of three targets can be used so as to ensure sufficient statistics. Two silicon detectors, located at 90° to the secondary beam direction, face each target, thus covering 30% of the solid angle. This experimental setup is to be used to obtain excitation functions of fusion–fission reactions and of reactions leading to evaporation residue production.© 2003 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

The neutron-rich nuclei2360-63V have been produced at GANIL via interactions of a 61.8A·MeV76Ge beam with a58Ni target. Beta-decay to2460-63Cr has been investigated using combined β- and γ-ray spectroscopy. Half-lives of the60-63V nuclei have been determined, and the existence of a beta-decay isomer in the60V nucleus is strongly supported. The observation of low-energy 2+ states in60Cr (646keV) and62Cr (446keV) suggests that these isotopes are strongly deformed with β2 ∼ 0.3. This is confirmed by shell model calculations which show the dominant influence of the intruder g and d orbitals to obtain low 2+ energies in the neutron-rich Cr isotopes. [ABSTRACT FROM AUTHOR]

Following mass measurements in the region N = 20 and N = 28, we have studied inelastic nuclear scattering for the nuclei 34Si, 33Al and 32Mg. No evidence for a low-lying shape isomeric 0+ state was found in 34Si, and an upper limit for the population cross-section could be established, rendering its existence very unlikely. A new transition was found in 33Al, that is a good candidate for a 2p-2h state and therefore a determination of the 2p-2h gap at N = 20. Inelastic nuclear scattering strongly excites 3- states, as seen in 34Si. A strong transition was found in 32Mg that should correspond to the first 3- in this nucleus, lying very low as compared to theory and systematics in this region. [ABSTRACT FROM AUTHOR]

The reduced transition probability B( E2: 01 +→ 2+) of 72Zn has been measured for the first time by Coulomb excitation at intermediate energy. The result B( E2: 01 +→ 2+) = 1740±210 e2fm4, corresponds to the deformation parameter β2 of 0.23, in close agreement with expectations derived from the neighboring nucleus 73Zn. A discussion of the evolution of the N = 40 sub-shell closure as a function of Z is presented. [ABSTRACT FROM AUTHOR]

The experimentally measured excitation functions for the fission and 4n evaporation channels are presented for the 6He + 209Bi reaction. The secondary 6He beam was produced using the special beam line (Q4DQ-spectrometer) of the U400M accelerator at FLNR, JINR. The comparison of the obtained experimental data with similar results for the 4He + 209Bi reaction shows that in the case of the 6He + 209Bi reaction a significant enhancement of the cross-section is observed for energies above the barrier. In order to get an agreement between the experimental data and the theoretical calculations it is necessary to reduce the Coulomb barrier by 15-20% , which corresponds to an increase of the parameter r0 of the nuclear potential up to 1.5-1.6 fm. [ABSTRACT FROM AUTHOR]

New results have been obtained for the energy dependence of the total reaction cross section σ[sub R] of [sup 4]He on [sup 28]Si in the energy range E[sub α] ≤ 30 MeV.© 2003 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

An experiment to the search for very neutron-rich nuclei has been performed at RIKEN, using projectile fragmentation of an intense 64 A MeV 48Ca beam and the fragment separator RIPS. Three new neutron-rich isotopes, 34Ne, 37Na and 43Si were observed unambiguously for the first time, and convincing evidence for the particle instability of three others, 33Ne, 36Na and 39Mg was obtained. The experimental findings are discussed in comparison with recent theoretical predictions. [Copyright &y& Elsevier]

The paper presents a review of experimental results obtained at GANIL and FLNR Dubna on the study of the particle stability of neutron-rich nuclei near the neutron drip line. Very recent data on mass measurements of neutron-rich nuclei in the range A=29–47 at GANIL and some characteristics of binding energies in this region are presented. Nuclear binding energies are very sensitive to the existence of shells and provide clear signatures of shell closures. Experiments have been mostly performed in cooperation GANIL–Orsay–Dubna–Rˇezˇ–Bucharest–Liverpool. [Copyright &y& Elsevier]