Photoproduction of ${\ensuremath{\pi}}^{0}$ mesons off targets of $^{6}\mathrm{Li}$, $^{12}\mathrm{C}$, $^{28}\mathrm{Si}$, $^{40}\mathrm{Ca}$, natural Cd, and natural Pb was studied using a bremsstrahlung beam with endpoint energies of 140, 145, 150, and 155 MeV. Photoproduction from a liquid hydrogen target was employed as a normalization. The measured yields were found to be in disagreement with published theoretical cross sections for $^{6}\mathrm{Li}(\ensuremath{\gamma}, {\ensuremath{\pi}}^{0})^{6}\mathrm{Li}$ and also in disagreement with a simple schematic model which assumed only coherent contributions from the ${M}_{1+}$ multipole. The schematic model, however, did approximately predict the relative magnitudes of the yield curves for the energy range 14-20 MeV over threshold.NUCLEAR REACTIONS $^{6}\mathrm{Li}$, $^{12}\mathrm{C}$, $^{28}\mathrm{Si}$, $^{40}\mathrm{Ca}$, Cd, Pb, ($\ensuremath{\gamma}, {\ensuremath{\pi}}^{0}$); ${E}_{\ensuremath{\gamma}}=140\ensuremath{-}155$ MeV; measured $\ensuremath{\sigma}$; test of reaction model.

We present measured angular distributions for ${\ensuremath{\pi}}^{+}$-elastic scattering at 30 and 50 MeV from selected targets with $A=12 \mathrm{to} 208$. These angular distributions were analyzed using a phenomenological optical potential of first-order form. The mass dependence of the potential strength parameters displays the isospin dependence expected from the free $\ensuremath{\pi}N$ interaction.NUCLEAR REACTIONS Elastic scattering of 30 and 50 MeV ${\ensuremath{\pi}}^{+}$ from $^{12}\mathrm{C}$, $^{16}\mathrm{O}$, $^{40}\mathrm{Ca}$, $^{90}\mathrm{Zr}$, $^{208}\mathrm{Pb}$. Angular distributions: $25\ifmmode^\circ\else\textdegree\fi{}<{\ensuremath{\theta}}_{\mathrm{LAB}}<160\ifmmode^\circ\else\textdegree\fi{}$. Optical model analysis of cross-section data.

Differential cross sections for elastic scattering of 40 MeV positive pions from /sup 12/C, /sup 16/O, /sup 40/Ca, /sup 90/Zr, and /sup 208/Pb were measured at 18 angles in the angular range 25/sup 0/--160/sup 0/. Relative uncertainties of 2.5% to 7% and overall normalization uncertainties of 4% to 7% were obtained. An optical potential fit of the data indicates that while the magnitudes of the strength parameters, except for Re b/sub 1/, are different from values obtained from free ..pi..N scattering amplitudes, the variation of these magnitudes with target mass is roughly as predicted by the impulse approximation. Coulomb effects, especially in the cases of /sup 90/Zr and /sup 208/Pb, are extremely important, but impossible to unambiguously separate from the strong interaction in the optical model.

The ${\ensuremath{\pi}}^{+}$ photoproduction on $^{12}\mathrm{C}$ has been measured relative to the proton from 0-20 MeV above threshold. Total cross sections from 0-12 MeV, summed over states in $^{12}\mathrm{B}$ have been extracted with accuracies between 5% and 8% relative to the proton photoproduction cross section. Distorted wave impulse approximation calculations have been performed and show good agreement with the data. The yield from 0-3 MeV above threshold is well described by a one parameter fit for the ground state cross section using only the $\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\sigma}}\ifmmode\cdot\else\textperiodcentered\fi{}\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\epsilon}}$ term of the Hamiltonian.NUCLEAR REACTIONS $^{12}\mathrm{C}$($\ensuremath{\gamma}$,${\ensuremath{\pi}}^{+}$)$^{12}\mathrm{B}$, bremsstrahlung endpoint energies to 175 MeV, deduced $\ensuremath{\sigma}(E)$; calculated $\ensuremath{\sigma}(E)$, DWIA.

Differential cross sections for the elastic scattering of positive pions on $^{12}\mathrm{C}$ at 49.9 MeV were measured. The results differ from those deteermined by other investigators. The data are analyzed in terms of ${\ensuremath{\pi}}^{+}$ nucleus partial waves and are compared to various model calculations.NUCLEAR REACTIONS $^{12}\mathrm{C}({\ensuremath{\pi}}^{+}, {\ensuremath{\pi}}^{+})^{12}\mathrm{C}$. $E=49.9$ MeV, $\ensuremath{\theta}=25\ifmmode^\circ\else\textdegree\fi{}\ensuremath{-}160\ifmmode^\circ\else\textdegree\fi{}$ measured $\frac{d\ensuremath{\sigma}}{d\ensuremath{\Omega}}(\ensuremath{\theta})$. Partial wave and optical model analyses.

Energy spectra of inelastic scattered π+ mesons from 16O, 40Ca, 60Ni, and 208Pb at Tπ = 50 MeV have been obtained at θlab = 40° and 80° for nuclear excitation energies up to ≈ 25 MeV. Differential cross section for the observed low-lying states and integrated continuum cross sections are given.