Abstract
Analysis of π0, η0, and ω0 production by 2- and 3-GeV protons in the reaction p+dHe3+X0 leads to an understanding of the variation of these cross sections with respect to momentum transfer and yields information concerning the He3 form factor. It is shown that the observed missing-mass spectra at the 2π threshold, which deviates from phase space in this reaction (the ABC effect), can be explained using this momentum-transfer dependence of the He3 form factor.