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Angle integrated energy spectra of protons (plus deuterons) anda particles have been obtained from neutron bombardment of a CsI crystal serving both as detector and target. Measurements were performed for neutron energies between 14 and 32 MeV. An explanation of proton anda yields cannot be given by statistical evaporation, but requires the assumption of a preequilibrium mechanism dominating for projectile energies in excess of 20 MeV. For these neutron energies the hard components of the proton anda particle spectra can be described quantitatively with the hybrid and the quasi free scattering preequilibrium model, respectively.

Using the activitation method (n,2n) excitation-functions were measured for54Fe,70Ge,74Se,85Rb,8688Sr,89Y,92Mo, and204Hg in the neutron-energy region 13–18 MeV. The results are checked for consistency by means of a systematic of (n, 2n) cross-sections as a function of the nuclear neutron excess (N-Z)/A. Furthermore the data are compared with results from the statistical nuclear reactions theory which were calculated using optical model absorption cross-sections and the Fermi-gas-model formula for the nuclear level density. In the case of204Hg the influence of preequilibrium nucleon emission was taken into account.

The break-up contribution to the continuous neutron spectra measured with3He projectiles of 34.4MeV for targets with masses 27?A?197 shows a broad peak centering the more belowE3He/3 the heavier the target is. The DWBA theory of elastic and inelastic break-up underestimates the inclusive spectra, but gives the correct shapes. Both, calculated and experimental peak positions, are indicative of a peripheral collision.

Excitation functions of the reactions109Ag(3He,xn) and111Cd(p, xn) have been measured with stacked foil techniques for projectile energies E?45 MeV and multiplicitiesx?4 populating ground and spin isomeric states in112-xIn. Preequilibrium (PE) contributions are more pronounced for thep than for the3He entrance channel and for low multiplicitiesx and can be reproduced with the (geometry dependent) hybrid model. The observed isomeric cross section ratios require a reduced population for the high spin state (as compared with the expectation for equilibrated systems) whenever PE emission contributes significantly. Calculations for a full statistical model with a PE decay mode and approximate angular momentum conservation indicate PE neutron emission to be stretched in angular momentum space. For the (p, xn) reactions a more detailed coupling scheme is imperative whereas the (3He,xn) data suggest the competitive PE emission of complex particles.

Double differential cross sections for the inclusive production of neutrons from64Zn,65Cu and89Y bombarded with 26.0 MeV protons have been measured with time-of-flight techniques. The data reduction is discussed with respect to the influence of background corrections in the continuous part of the spectra, and a short comparison with preequilibrium model calculations is presented, showing good agreement with predictions of both, the hybrid and the geometry-dependent hybrid model including multiple particle emission. The question of how to treat pairing remains open.

Excitation functions of the reactions9Be(3He,n),10B(d,n),11B(p,n),9Be(a,2n),11B(d,2n) and12C(n,2n), all leading to the residual nucleus11C, were measured with activation techniques. Projectile energies have been chosen to populate the composite systems12C* and13C* in energy ranges overlapping for 31MeV?E*(12C)?38MeV and 26 MeV?E*(13C)?33Mev, respectively. The attainable thick target yields are highest forp+11B. Statistical model calculations fail to quantitatively reproduce the experimental data although preequilibrium decay modes have been taken into account.

The angular and spectral distributions of coincident neutrons from the reactions127I(n, 2n)126I and209Bi(n, 2n)208Bi have been measured with two time-of-flight detectors at the incident energy 14.1 MeV. Neutron emission has been studied for reaction angles?lab between 10° and 150° (relative angles from 60° to 270°). Energy spectra, angular distributions and coincidence yields are compared with statistical model calculations including preequilibrium decay modes, and nuclear level density and spin cut off parameters are derived.

Elastic scattering angular distributions for35Cl from27Al,58, 62Ni,116, 120, 124Sn and141Pr have been measured at energies between 100 and 170 MeV. Optical model analyses have been performed to determine reaction cross sections, strong absorption radii and grazing angular momenta. The results are compared with the corresponding quantities extracted by means of the Fresnel scattering model. Near the interaction barrier the quarter point method yields reaction cross sections systematically smaller than the optical model results. The interaction radii, however, do not show significant differences or energy dependencies. These radii are compared with trend formulae for interaction radii, and comparisons with fusion radii are made.

The cross sections for the reactions N14(n, a)B11 and N14(n, t)C12 have been measured in the neutron energy range 4.0 to 6.4 MeV and at 2.5 MeV. Mono-energetic neutrons were produced in the D(d, n) He3 reaction using a gas target. The (n, a) and (n, t) disintegrations were detected in a gridded ionization chamber filled with an argonnitrogen mixture. The response of the chamber under different operation conditions is described. The excitation functions, measured with a neutron energy resolution of 40 to 50 keV, are given for thea0 group from the N14(n,a)B11 reaction over the entire neutron energy range and for thea1 group and the t0 group from N14(n, t) C12 for neutron energies above 4.3 and 5.6 MeV, respectively.