[en] The structure of the N≅28 ^45,46₁₈Ar_27,28 nuclei has been investigated through in-beam γ-ray spectroscopy using the fragmentation reaction of a 60 A MeV ⁴⁸Ca beam on a thin Be target. γ-ray energies, intensities, γγ coincidences and γ-ray angular anisotropies have been measured. The level scheme of ⁴⁵Ar is proposed for the first time, while that of ⁴⁶Ar has been extended to states above the previously known 2⁺ first excited state. An isomeric state at 537 keV of 0.34^+0.32_-0.15 ns lifetime has been found in ⁴⁵Ar from the line-shape analysis of the γ ray connecting the first excited state to the ground state. The experimental results are interpreted using shell-model calculations

[en] This report states the specificity of light particles elastic scattering, and the need of detecting recoil protons to improve angular resolution. Then the development of a specific MUST strip detector is detailed: 60 strips detectors with Si O sub 2 dielectric, that yield 500 ps time resolution, and Si (Li) detectors following next. A versatile data acquisition system has been developed too, with CAMAC interface to suit to any experimental plant. (D.L.)

[en] Beta-decay branching ratios of ⁶²Ga have been measured at the IGISOL facility of the Accelerator Laboratory of the University of Jyvaeskylae. ⁶²Ga is one of the heavier T_z=0, 0⁺→0⁺β-emitting nuclides used to determine the vector coupling constant of the weak interaction and the V_ud quark-mixing matrix element. For part of the experimental studies presented here, the JYFLTRAP facility has been employed to prepare isotopically pure beams of ⁶²Ga. The branching ratio obtained, BR=99.893(24) %, for the super-allowed branch is in agreement with previous measurements and allows to determine the ft value and the universal Ft value for the super-allowed β -decay of ⁶²Ga. (orig.)

[en] A new and innovative array, MUST, based on silicon strip technology and dedicated to the study of reactions induced by radioactive beams on light particles is described. The detector consists of 8 silicon strip - Si(Li) telescopes used to identify recoiling light charged particles through time of flight, energy loss and energy measurements and to determine precisely their scattering angle through X, Y position measurements. Each 60x60 mm² double sided silicon strip detector with 60 vertical and 60 horizontal strips yields an X-Y position resolution of 1 mm, an energy resolution of 50 keV, a time resolution of around 1 ns and a 500 keV energy threshold for protons. The backing Si(Li) detectors stop protons up to 25 MeV with a resolution of approximately 50 keV. CsI crystals read out by photo-diodes which stop protons up to 70 MeV are added to the telescopes for applications where higher energy particles need to be detected. The dedicated electronics in VXIbus standard allow us to house the 968 logic and analog channels of the array in one crate placed adjacent to the reaction chamber and fully remote controlled, including pulse visualization on oscilloscopes. A stand alone data acquisition system devoted to the MUST array has been developed. Isotope identification of light charged particles over the full energy range has been achieved, and the capability of the system to measure angular distributions of states populated in inverse kinematics reactions has been demonstrated. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

[en] The structure of neutron-rich light nuclei around N=20 and 28 has been investigated at GANIL by means of in-beam gamma-spectroscopy using fragmentation reactions of ³⁶S and ⁴⁸Ca beams on a Be target. Gamma-decay of relatively high-lying excited states have been measured for the first time in nuclei around ³²Mg and ⁴⁴S. Level schemes are proposed and discussed for a large number of these neutron-rich nuclei around N=20 and N=28. (orig.)

[en] Lifetimes of the excited states in the neutron-rich ^52,54Ti nuclei, produced in a multinucleon-transfer reaction, were measured by employing the Cologne plunger device and the recoil-distance Doppler-shift method. The experiment was performed at the Grand Accelerateur National d'Ions Lourds facility by using the Advanced Gamma Tracking Array for the gamma-ray detection, coupled to the large-acceptance variable mode spectrometer for an event-by-event particle identification. A comparison between the transition probabilities obtained from the measured lifetimes of the 2₁⁺ to 8₁⁺ yrast states in ^52,54Ti and that from the shell-model calculations based on the well-established GXPF1A, GXPF1B, and KB3G fp shell interactions support the N = 32 subshell closure. The B(E₂) values for ⁵²Ti determined in this work are in disagreement with the known data, but are consistent with the predictions of the shell-model calculations and reduce the previously observed pronounced staggering across the even-even titanium isotopes. (authors)

[en] A new and innovative array, MUST, based on silicon strip technology and dedicated to the study of reactions induced by radioactive beams on light particles is described. The detector consists of 8 silicon strip - Si(Li) telescopes used to identify recoiling light charged particles through time of flight, energy loss and energy measurements and to determine precisely their scattering angle through X, Y position measurements. Each 60x60 mm² double sided silicon strip detector with 60 vertical and 60 horizontal strips yields an X-Y position resolution of 1 mm, an energy resolution of 50 keV, a time resolution of around 1 ns and a 500 keV energy threshold for protons. The backing Si(Li) detectors stop protons up to 25 MeV with a resolution of approximately 50 keV. CsI crystals read out by photo-diodes which stop protons up to 70 MeV are added to the telescopes for applications where higher energy particles need to be detected. The dedicated electronics in VXIbus standard allow us to house the 968 logic and analog channels of the array in one crate placed adjacent to the reaction chamber and fully remote controlled, including pulse visualization on oscilloscopes. A stand alone data acquisition system devoted to the MUST array has been developed. Isotope identification of light charged particles over the full energy range has been achieved, and the capability of the system to measure angular distributions of states populated in inverse kinematics reactions has been demonstrated