J.M. Loiseaux

Elastic and inelastic scattering of 1.03 GeV 12C projectiles

Abstract Elastic scattering cross sections of 86 MeV/N 12C ions on 12C, NATCa, 89Y and 208Pb targets has been measured together with inelastic scattering to the 4.4 MeV state of 12C. There is some indication for giant (quadrupole) resonance excitation in 40Ca. Optical model and DWBA analyses are reported. Nuclear transparency effect is discussed.

Projectile fragments from 86 MeV/nucleon 12C induced reactions

Abstract An 86 MeV/nucleon 12 C beam has been used to bombard targets of C, Ag and Au. Energy spectra of reaction products with Z = 3−6 and A = 6−12 have been measured at angles between 3° and 20°. A simple fragmentation model, while predicting approximately the gross features of the data, fails to describe the results in detail.

Proton emission in 58A and 86A MeV 12C-induced heavy-ion reactions

Abstract Inclusive proton spectra from 12 C-induced heavy-ion interactions at 58 A and 86 A MeV have been obtained by using a ΔE − E time-of-flight telescope. The shapes of the energy spectra above 30 MeV for 32°⩽ θ ⩽142° are very similar for five targets ranging from C to Au. The backward spectra can be reproduced both in the picture of a thermalized source characterized by an 11–17 MeV temperature Boltzmann distribution moving with half the beam velocity and in the picture of quasi-elastic nucleon-nucleon scattering from two interacting Fermi spheres. The forward spectra are difficult to reproduce unless a combination of the two descriptions is accepted. The 58 A MeV spectra peak substantially closer to the beam energy per nucleon and show significantly steeper slopes than 86 A MeV spectra.

Study of the high-lying states of 12C by inelastic scattering of hadrons

Abstract Beams of 45 and 155 MeV protons and 60 MeV α-particles have been used to investigate the high-lying continuum of 12 C. Various multipolarities and strengths have been located between the excitation energies of 15 and 30 MeV. Isovector El states have been located at excitation energies between 20 and 30 MeV; E2 states at 15.3 and 18.4 MeV ( T = 0); an E3 state at 21.65 MeV ( T = 0); an E4 state at 19.6 MeV ( T = 0); and a M2 state at 19.2 MeV ( T = 1). The results are analyzed in terms of both collective and microscopic model calculations.

g-factor of an isometric level in 117Sb

Abstract The g -factor of an isomeric level in 117 Sb has been measured, in beam, by the differential perturbed angular correlation method with a pulsed magnetic field. The result is | g | = 0.116 ± 0.003.

Excitation of low-lying levels and giant resonances in 90Zr via 57.5 MeV polarized proton inelastic scattering

Abstract Differential cross section and analyzing power angular distributions have been measured for transitions to low-lying bound states with J π = 2 + , 3 − , 4 + and 5 − , and the giant resonance region from 6 to 27 MeV excitation energy. Collective model calculations using a full Thomas form factor reproduce the data fairly well. The so-called LEOR turns out not to be seen as pure E3 in (p, p′). In the giant resonance region the data do not reveal the presence of a sizeable monopole strength, 10–20% of the energy-weighted sum rule at most. There is strong indication for a mixture of E2 (18% of the EWSR) and E4 (16% of the EWSR). Calculations were also carried out using RPA (1p1h) wave functions. They reproduce the experimental data rather poorly, except for the general behaviour of the cross-section angular distributions.

Excitation function of giant resonances as doorway states in the 12C(p, p′)12C∗ reaction between 19 and 23 MeV

Abstract Differential cross section and analyzing power angular distributions for the elastic scattering and inelastic scattering to the 2+ state at 4.44 MeV and the 1+ state at 12.7 MeV have been measured at incident proton energies varying from 19.15 to 23.34 MeV in 200 keV steps. Elastic scattering data are analyzed using an averaged optical model. Coupled-channel calculations reproduce roughly the 2+ data. The rapid variation of the data concerning the 1+ state is explained by virtual excitation of giant resonances. For each value of the incident energy, the coupling strength for each resonance is found by fitting the experimental angular distributions. The analysis assuming a weak coupling in the compound system gave a satisfactory fit to the cross section but a poor reproduction of the analyzing power. The assumption of a strong coupling in the 13N system allowed a good fit of all data. The angular distributions are dominated by the E1 resonance, whose 1 2 + component exhausting more than 37 % of the energy weighted sum rule, explains the isotropy of the cross section below 22 MeV. A 7 2 + resonance (15 % EWSR) is located at 19.9 MeV. The 5 2 − resonance with its maxima at 20.2 and 21.4 MeV, exhausts about 18 % of the sum rule, which is in good agreement with the results of previous works.

Experimental study of the Ne 20 + C 12 system

Excitation functions for elastic, inelastic, and four-particle transfer channels of the /sup 12/C + /sup 20/Ne system were measured from 17 to 35 MeV (c.m.). The elastic scattering data (excitation functions and angular distribution at 24.7 MeV) have been analyzed with the optical model. Elastic and inelastic scattering are also studied in the framework of the coupled-channel Born approximation. The results emphasize the importance of the 2/sup +/ state of /sup 20/Ne in the descciption of the absorption. The comparison with the /sup 16/O + /sup 16/O system is discussed.

Experimental study of the /sup 20/Ne + /sup 12/C system

Excitation functions for elastic, inelastic, and four-particle transfer channels of the /sup 12/C + /sup 20/Ne system were measured from 17 to 35 MeV (c.m.). The elastic scattering data (excitation functions and angular distribution at 24.7 MeV) have been analyzed with the optical model. Elastic and inelastic scattering are also studied in the framework of the coupled-channel Born approximation. The results emphasize the importance of the 2/sup +/ state of /sup 20/Ne in the descciption of the absorption. The comparison with the /sup 16/O + /sup 16/O system is discussed.