Production ofπ∘Mesons in Hydrogen and Deuterium by High Energyγ-Rays

Abstract

The angular distribution of the ${\ensuremath{\pi}}^{\ensuremath{\circ}}$'s and the dependence of the cross sections on the energy of the $\ensuremath{\gamma}$-rays have been studied for the reactions ${\ensuremath{\gamma}+P,\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{\circ}}+P,}{\ensuremath{\gamma}+P,\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{\circ}}+D(P,N).}$ For the first reaction, the angular distribution in the center-of-mass system has the form $a+b{sin}^{2}\overline{\ensuremath{\theta}}$, with $\frac{a}{b}\ensuremath{\simeq}1$, and the cross section is proportional to approximately the square of the excess energy of the $\ensuremath{\gamma}$-rays above the threshold; $\frac{{\ensuremath{\sigma}}_{\mathrm{D}}}{{\ensuremath{\sigma}}_{\mathrm{H}}}\ensuremath{\simeq}2$ at all energies and angles.