No abstract

Double differential cross sections for the neutron-induced production of p, d, t, 3He, and alpha particles from carbon have been measured using unpolarized neutrons. Neutron beam energies of 27.4, 39.7, and 60.7 MeV were used. The charged particle energy spectra at nine laboratory angles - 15, 20, 35, 40, 45, 65, 90, 130, and 150 degrange up to the kinematic maximum, from a lower energy cutoff of 4 MeV for p, d, t, and alpha and 8 MeV for He. A CH target was used so that the absolute normalization was obtained simultaneously from the n-p cross sections. Intranuclear cascade plus deexcitation calculations were carried out. The data are compared with these calculations and with available proton induced (charge symmetric) reaction spectra.NUCLEAR REACTIONS ' C(n, px;dx; Hx; Hex; Hex), E"=27. 4, 39.7, 60.7 MeV; measured o. (0;E},Ol, 20, 35, 40, 45, 65, 90, 130, 150 deg. Intranuclear cascade plus deexcitation calculations.

Neutron total non-elastic cross sections have been obtained from transmission measurements of 40.3 and 50.4 MeV neutrons on C, 0, Ca, and Fe. The results agree within error bars with proton data on the same nuclei. The data are well represented by the relation o ", "= n. (rP '" + L)', where r, = (1.21+0.03) fm. Comparisons of o """withoptical model calculations for C and 0 show a preference for the parameters of Bassel and Herling, while for Ca both the parameter sets of Patterson and those of Becchetti and Greenlees work reasonably well. None of the parameter sets is entirely satisfactory for Fe. Implications of these data for the isospin dependence of the optical model are discussed.NUCLEAR REACTIONS C, 0, Ca, and Fe+ n, E"=40. 3 and 50.4 MeV. Inferred neutron total elastic and non-elastic cross sections. Natural targets.

Double-differential cross sections for the neutron-induced production of p, d, t, 'He, and alpha particles from oxygen and nitrogen have been measured using an unpolarized neutron facility. Neutron beam energies of 27.4, 39.7, and 60.7 MeV were used. The charged particle energy spectra, at six forward laboratory angles, 15, 20, 35, 40, 45, and 65, and, where feasible, at three backward angles, 90, 130, and 150 deg, range up to the kinematic maximum, from a typical low-energy cutoff of 4 MeV for p, d, t, and alpha particles, and 8 MeV for 3He. Intranuclear cascade plus deexcitation calculations were carried out. The data are compared with these calculations and with available proton-induced (charge-symmetric) reaction spectra for oxygen.

The (n 9 p) reaction in 6 Li and 7 Li at 60 MeV reveals large structures at high excitations which are the analogs of states in 6 Li and 7 Li at 29 and 31 MeV, respectively. These new structures, which exhibit giant dipole strength, are not seen in photoneutron data. They do not appear to contain appreciable dipole spin-mode strength. The exhaust large sumrule fractions, and largely answer the longstanding question of missing giant dipole resonance strength in these nuclei.