F. Boué

MEASUREMENT OF THE COULOMB DISSOCIATION OF 8B AT 254 MEV/NUCLEON AND THE 8B SOLAR NEUTRINO FLUX

We have measured the Coulomb dissociation of 8B into 7Be and proton at 254 MeV/nucleon using a large-acceptance focusing spectrometer. The astrophysical S17 factor for the 7Be(p,gamma)8B reaction at E{c.m.} = 0.25-2.78 MeV is deduced yielding S17(0)=20.6 \pm 1.2 (exp.) \pm 1.0 (theo.) eV-b. This result agrees with the presently adopted zero-energy S17 factor obtained in direct-reaction measurements and with the results of other Coulomb-dissociation studies performed at 46.5 and 51.2 MeV/nucleon.

Total interaction and proton-removal cross-section measurements for the proton-rich isotopes 7Be, 8B, and 9C

Abstract In an experiment performed at the FRS of GSI, we measured total interaction cross sections for 7 Be, 8 B, and 9 C, one-proton-removal cross sections for 8 B and 9 C as well as two-proton-removal cross sections for 9 C on targets ranging from carbon to lead at an energy of 285 MeV/nucleon. In addition, we performed measurements at 142 MeV/nucleon for 8 B. The experimental results are compared to different calculations. Glauber-type calculations with different model·density distributions show that, down to incident energies of about 50 MeV/nucleon, total interaction cross-section measurements with light targets are not sensitive to an extended proton distribution in 8 B. However, at lower incident energies, a tail in the proton density distribution is needed to explain the total interaction cross sections. Total interaction cross-section measurements with high-Z targets in the present experiment show a significant increase of the cross sections due to low-lying electromagnetic strength.

The spectroscopy of 22Al: a βp, β2p and βα emitter

Abstract In an experiment at the LISE3 facility of GANIL, we produced the proton-rich isotope 22Al by the fragmentation of a 36Ar primary beam at 95 MeV/nucleon. After implantation in a detector telescope, the decay of 22Al via β-delayed proton emission, β-delayed two-proton emission as well as, for the first time, via β-delayed α emission has been studied. An α peak has been observed at (3.27 ± 0.04) MeV with a branching ratio of (0.31 ± 0.09) %. The comparison of the different decay channels to those of the mirror nucleus 22F and to shell-model calculations favor a 3+ state as being the ground state of 22Al. A half life of T1/2 = (59 ± 3) ms has been measured.

Beta-p,-2p,-alpha spectroscopy of 22,23,24Si and 22Al

Abstract In an experiment at the LISE3 facility of GANIL, we used the projectile fragmentation of a 36 Ar 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 βp, β2p, and βα decay of the isotopes 22,23,24 Si and 22 Al. Beta-decay half-lives have been measured. The ground-state mass excess of 23 Si has been determined. Partial decay schemes are presented on the basis of the transitions associated with the observed decay peaks.

Isomeric states in 66As

Abstract Two new isomeric states in the self-conjugate nucleus 66 As have been observed at the final focus of the LISE3 spectrometer at GANIL. The nucleus has been produced in a fragmentation reaction of 78 Kr at 73A MeV. The 66 m 1, m 2 As isomeric levels are placed at excitation energies of E ∗m1 =3023.9 keV and E ∗m2 =1356.7 keV. Half-lives of T 1/2 m 1 =17.5(15) μ s and T 1/2 m 2 =1.9(5) μ s have been measured for the isomers and a decay scheme has been established.

Beta-delayed proton spectroscopy of 24Si

Abstract In an experiment at the LISE3 facility of GANIL, we used the projectile fragmentation of a 36 Ar primary beam at 95 MeV/nucleon to produce the isotope 24 Si. The beta decay half-life of 24 Si has been determined to be T 1/2 = (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 24 Si. These results are compared with shell-model predictions.

Spectroscopy of 22,23,24Si and 22Al

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.

On the road to doubly-magic 48Ni

A relativistic primary beam of 58Ni 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 Tz=−7/2 nuclei 45Fe and 49Ni. In addition, the new isotope 42Cr (Tz=−3) was identified. This opens the route to the yet unobserved doubly-magic nucleus 48Ni.

On the road to doubly-magic

A relativistic primary beam of 58Ni 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 Tz=−7/2 nuclei 45Fe and 49Ni. In addition, the new isotope 42Cr (Tz=−3) was identified. This opens the route to the yet unobserved doubly-magic nucleus 48Ni.

On the road to doubly-magic {sup 48}Ni

A relativistic primary beam of 58Ni 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 Tz=−7/2 nuclei 45Fe and 49Ni. In addition, the new isotope 42Cr (Tz=−3) was identified. This opens the route to the yet unobserved doubly-magic nucleus 48Ni.