Interactions of 197Au projectiles at 800 A MeV with protons leading to fission are investigated. We measured the production cross sections and velocities of all fission residues which are fully identified in atomic and mass number by using the in-flight separator FRS at GSI. The new data are compared with earlier measurements of the characteristics of fission in similar reactions. Both the production cross sections and the recoil energies are relevant for a better understanding of spallation reactions.

Formation cross sections of isotopes produced in inverse kinematics from the spallation/fragmentation and fission of 197Au (at 800 A⋅MeV), 208Pb (at 1 A⋅GeV) and 238U (at 1 A⋅GeV) are presented. These data are extremely important for the design of acceleratordriven systems and new radioactive-ion-beam facilities. The data have been measured at GSI with the FRagment Separator, which allows precise measurements of the cross sections of the fragments and of their velocities. The knowledge of the velocity enables to deduce the reaction mechanisms and leads to a better understanding of the physics of intermediateenergy nuclear reactions. Thanks to this, nuclear models capable to predict the isotopic formation cross sections have been implemented and benchmarked with the measured data. Results are presented.

Experiments of spallation in inverse kinematics were performed at GSI. The isotopic distribution cross-sections of the residual nuclides of spallation were measured for each element. The fragment separator (FRS) was used to select and identify the reaction products, and the full (Z,N) map was measured. The velocity distributions of all products are determined with the high resolution of the spectrometer, which give further information on the reaction mechanism. These data are relevant for the design of accelerator-driven subcritical reactors. They are also of the highest importance to improve the understanding of the spallation mechanism.

Fission induced by 197Au on proton collisions is investigated in order to study the nuclear viscosity in highly excited nuclear matter. The isotopic identification of the fission residues allows to determine the mean values of the mass number, nuclear charge and excitation energy of the fissioning nuclei at saddle. The comparison of these properties with statistical fission calculations evidences the role of the nuclear viscosity in the description of the fission dynamics.

beta-delayed one- and two-proton and alpha spectroscopic studies of the neutron-deficient nuclei Si-22,Si-23,Si-24 and Al-22 produced in projectile fragmentation of a Ar-36 primary beam at 95 MeV/u have been performed at GANIL. Isotopes of interest were analyzed using the LISE3 spectrometer and were implanted in a telescope made of silicon detectors and a micro-strip gaseous counter where decay particles were detected.

A relativistic primary beam of Ni-58 from the SIS synchrotron at GSI was used to produce proton-rich isotopes in the titanium-to-nickel region by projectile fragmention at the FRS. We report here on the first observation of the T-z = -7/2 nuclei Fe-45 and Ni-49. In addition, the new isotope Cr-42 (T-z = -3) was identified. This opens the route to the yet unobserved doubly-magic nucleus Ni-48.

Projectile fragmentation and fission, induced in collisions of 238U at 1 A GeV with lead, have systematically been studied. A complete survey on the isotopic production cross sections of all elements between vanadium (Z = 23) and rhenium (Z = 75) down to a cross section of 0.1 mb is given. About 600 isotopes produced in fragmentation and about 600 isotopes produced in fission were identified in the GSI fragment separator FRS from magnetic rigidities, time-of-flight values, and the energy loss in an ionisation chamber. In addition, the velocity distributions of all these reaction products have been mapped, and the products are unambiguously attributed to the different reaction mechanisms due to their kinematical properties. The results are compared with empirical systematics and previous data. The velocity of the fragments obtained in the fission process by the Coulomb repulsion allows one to reconstruct the TKE-value of the break-up and to identify the atomic number of the fissioning nucleus in hot fission. The mean velocities of light projectile fragments were found to be higher than the beam velocity.

β-delayed one- and two-proton and α spectroscopic studies of the neutron-deficient nuclei 22,23,24Si and 22Al produced in projectile fragmentation of a 36Ar primary beam at 95 MeV/u have been performed at GANIL. Isotopes of interest were analyzed using the LISE3 spectrometer and were implanted in a telescope made of silicon detectors and a micro-strip gaseous counter where decay particles were detected.

In an experiment at the LISE3 facility of GANIL, we used the projectile fragmentation of a 36Ar primary beam at 95 MeV/nucleon to produce the isotope 24Si. The beta decay half-life of 24Si has been determined to be T1/2 = (140 ± 8) ms, in agreement with earlier measurements. In addition to the decay of the isobaric analog state, several proton peaks are observed for the first time allowing to identify most of the Gamow-Teller transitions to unbound states and to present a partial decay scheme for 24Si. These results are compared with shell-model predictions.

Spallation experiments in inverse kinematics have been performed at GSI. The momentum distributions and the isotopic production cross sections have been measured. The data are relevant for the design of accelerator-driven subcritical reactors.

Two new isomeric states in the self-conjugate nucleus 66As have been observed at the final focus of the LISE3 spectrometer at GANIL. The nucleus has been produced in a fragmentation reaction of 78Kr at 73A MeV. The 66m1,m2As isomeric levels are placed at excitation energies of E∗m1=3023.9 keV and E∗m2=1356.7 keV. Half-lives of T1/2m1=17.5(15) μs and T1/2m2=1.9(5) μs have been measured for the isomers and a decay scheme has been established.

23Si isotopes have been produced as projectile fragments of a 36Ar primary beam at 95 MeV/nucleon at the LISE3 spectrometer of GANIL. After implantation in a detector telescope, β-delayed one-proton and β-delayed two-proton emission has been observed. The main one-proton peaks are at (1.32±0.04)MeV, (2.40±0.04)MeV, and (2.83±0.06)MeV. The total decay energy for the β2p decay is (6.18±0.10)MeV for the decay to the ground state and (5.86±0.10)MeV for the decay to the first excited state in the daughter nucleus. However, energetically possible decays via βpα and β3p emission have not been identified. The spectra allowed us to determine the excitation energy of the isobaric analogue state in 23Al. This enabled us to calculate the coefficients of the T = 5/2 isobaric multiplet mass equation for A = 23. The mass excess of the 23Si ground state was deduced. This value is compared to different theoretical predictions. Additionally, we determined the branching ratios for the different decay branches. A half-life measurement yielded T1/2 = (40.7±0.4)ms.

Si-23 isotopes have been produced as projectile fragments of a Ar-36 primary beam at 95 MeV/nucleon at the LISE3 spectrometer of GANTL. After implantation in a detector telescope, beta-delayed one-proton and beta-delayed two-proton emission has been observed. The main one-proton peaks are at (1.32+/-0.04)MeV, (2.40+/-0.04)MeV, and (2.83+/-0.06)MeV. The total decay energy for the beta 2p decay is (6.18+/-0.10)MeV for the decay to the ground state and (5.86+/-0.10)MeV for the decay to the first excited state in the daughter nucleus. However, energetically possible decays via beta pa and beta 3p emission have not been identified. The spectra allowed us to determine the excitation energy of the isobaric analogue state in Al-23. This enabled us to calculate the coefficients of the T = 5/2 isobaric multiplet mass equation for A = 23. The mass excess of the Si-23 ground state was deduced. This value is compared to different theoretical predictions. Additionally, we determined the branching ratios for the different decay branches. A half-life measurement yielded T-1/2 = (40.7+/-0.4)ms.

In an experiment at the LISE3 facility of GANIL, we used the projectile fragmentation of a Ar-36 primary beam at (95) MeV/nucleon to produce neutron-deficient isotopes in the Al-Si region. The selected isotopes were implanted in a detector telescope, where their decay particles were observed. We report here on the study of the beta p, beta 2p, and beta alpha decay of the isotopes Si-22,Si-23,Si-24 and Al-22. Beta-decay half-lives have been measured. The ground-state mass excess of Si-23 has been determined. Partial decay schemes are presented on the basis of the transitions associated with the observed decay peaks.

In an experiment at the LISE3 facility of GANIL, we produced the proton-rich isotope Si-22 by the fragmentation of a Ar-36 primary beam at 95 MeV/nucleon. After implantation in a detector telescope, we studied the decay of Si-22 via a measurement of charged particles emitted during the decay. The most important beta-delayed proton activity is observed at an energy of E(p) = (1.99+/-0.05) MeV with a branching ratio of (20 +/-2)%. The spectra allow us also to determine the half-life of Si-22 to be T-1/2 = (29 +/- 2) ms. These results are compared with theoretical estimates and model predictions.