0000000000204172
AUTHOR
M. Rousseau
Backbending in the pear-shaped 223(90)Th nucleus: Evidence of a high-spin octupole to quadrupole shape transition in the actinides
International audience; Relatively neutron-rich thorium isotopes lie at the heart of a nuclear region of nuclei exhibiting octupole correlation effects. The detailed level structure of Th223 has been investigated in measurements of γ radiation following the fusion-evaporation channel of the Pb208(O18,3n)Th223 reaction at 85 MeV beam energy. The level structure has been extended up to spin 49/2, and 33 new γ rays have been added using triple-γ coincidence data. The spins and parities of the newly observed states have been confirmed by angular distribution ratios. In addition to the two known yrast bands based on a K=5/2 configuration, a non-yrast band has been established up to spin 35/2. We…
Influence of fusion barrier distributions on spin populations
Abstract Heavy-ion fusion barrier distributions are now routinely obtained directly from experimental data. By measuring the total γ -ray multiplicity for the 58 Ni + 60 Ni system, which has a striking yet well understood barrier distribution, we show that some evidence of the barrier structures is present in the derived spin populations. In particular, very high spins can be populated at energies rather close to (and even below) the ‘nominal’ Coulomb barrier.
Mass Measurements with the CSS2 and CIME cyclotrons at GANIL
Commune avec ACEN; This paper presents two original direct mass-measurement techniques developed at GANIL using the CSS2 and CIME cyclotrons as high-resolution mass spectrometers. The mass measurement with the CSS2 cyclotron is based on a time-of-flight method along the spiral trajectory of the ions inside the cyclotron. The atomic mass excesses of 68Se and 80Y recently measured with this technique are -53.958(246) MeV and -60.971(180) MeV, respectively. The new mass-measurement technique with the CIME cyclotron is based on the sweep of the acceleration radio-frequency of the cyclotron. Tests with stable beams have been performed in order to study the accuracy of this new mass-measurement m…
Spin distributions at the Coulomb barrier in the $^{58}$Ni+$^{60}$Ni fusion reaction from gamma-ray multiplicity measurements
Abstract Heavy-ion fusion barrier distributions are now routinely obtained directly from experimental data. Measurements of the total γ-ray multiplicity for the fusion channels of the 58 Ni + 60 Ni system, which has striking yet well understood barrier structures, confirm the theoretical predictions that very high spins can be populated at energies close to (and even below) the nominal Coulomb barrier. The mapping from multiplicities to spin populations shows that structures in the barrier distribution are still evident in the γ-ray results.
Direct mass measurements ofSe68andY80
The masses of neutron-deficient nuclides near the $N=Z$ line with $A=64\text{\ensuremath{-}}80$ have been determined using a direct time-of-flight technique which employed a cyclotron as a high-resolution spectrometer. The measured atomic masses for $^{68}\mathrm{Se}$ and $^{80}\mathrm{Y}$ were 67.9421(3) u and 79.9344(2) u, respectively. The new values agree with the 2003 Atomic Mass Evaluation. The result for $^{68}\mathrm{Se}$ confirms that this nucleus is a waiting point of the rp-process, and that for $^{80}\mathrm{Y}$ resolves the conflict between earlier measurements. Using the present results and the 2003 Atomic Mass Evaluation compilation, the empirical interaction between the last…
The FIRST experiment at GSI
The FIRST (Fragmentation of Ions Relevant for Space and Therapy) experiment at the SIS accelerator of GSI laboratory in Darmstadt has been designed for the measurement of ion fragmentation cross-sections at different angles and energies between 100 and 1000 MeV/nucleon. Nuclear fragmentation processes are relevant in several fields of basic research and applied physics and are of particular interest for tumor therapy and for space radiation protection applications. The start of the scientific program of the FIRST experiment was on summer 2011 and was focused on the measurement of 400 MeV/nucleon 12C beam fragmentation on thin (8 mm) graphite target. The detector is partly based on an alread…
Direct mass measurement of N $\sim$ Z nuclei with A = 64–80 using the CSS2 cyclotron
International audience; The masses of ten neutron-deficient nuclides near the N = Z line with A = 64–80 have been measured with the direct time-of-flight technique using the CSS2 cyclotron as a high-resolution spectrometer. All measured masses agree with the 2003 atomic mass evaluation and are compared to the predictions of the finite range droplet model. The atomic mass excesses obtained for $^{68}$Se and $^{80}$Y are -53.958(246) MeV and -60.971(180) MeV, respectively. The new results for $^{68}$Se and $^(80}$Y are compared to other recent experimental values.
FIRST experiment: Fragmentation of Ions Relevant for Space and Therapy
International audience; Nuclear fragmentation processes are relevant in different fields of basic research and applied physics and are of particular interest for tumor therapy and for space radiation protection applications. The FIRST (Fragmentation of Ions Relevant for Space and Therapy) experiment at SIS accelerator of GSI laboratory in Darmstadt, has been designed for the measurement of different ions fragmentation cross sections at different energies between 100 and 1000 MeV/nucleon. The experiment is performed by an international collaboration made of institutions from Germany, France, Italy and Spain. The experimental apparatus is partly based on an already existing setup made of the …