Diffractive dissociation of high momentum pions in Fermilab E791

We report very preliminary results of studies of diffractive dissociation of 500 GeV/c π- into di-jets. The measurements were carried out using data from Fermilab E791. The A-dependence of the yield of the diffractive di-jets is a predicted signal of color transparency. The measured ratio of the jets momenta is used to test predictions of the pion momentum wave function. The results are in agreement with color transparency prediction and the proposed asymptotic pion wave function. copyright 1998 American Institute of Physics