Systematics of 0° neutron production by 800 MeV protons on targets with<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mn>27</mml:mn><mml:mi>≤</mml:mi><mml:mi>A</mml:mi><mml:mi>≤</mml:mi><mml:mn>238</mml:mn></mml:math>

The 0\ifmmode^\circ\else\textdegree\fi{} neutron spectra resulting from 800 MeV proton bombardment of targets of Al, Ti, Cu, W, Pb, and U have been measured for neutron momenta above 500 MeV/c. Integrated cross sections for the quasielastic charge exchange peaks and the broad pion associated peaks at lower momenta show a remarkably smooth dependence on atomic mass of the target, varying as ${A}^{\frac{2}{3}}$ and ${A}^{\frac{1}{2}}$, respectively.NUCLEAR REACTIONS Al, Ti, Cu, W, Pb, U ($p, n$), $E=800$ MeV; measured $\ensuremath{\sigma}$ (0\ifmmode^\circ\else\textdegree\fi{}; ${P}_{n}$); deduced $A$ dependence of charge exchange and pion associated cross sections.