We have measured total hadronic photoproduction cross sections on carbon, copper, and lead. Tagged-photon energies ranged from 20 to 185 GeV for copper and from 45 to 82 GeV for carbon and lead. The energy and A dependence of shadowing were computed by comparing these results to the hydrogen cross section as measured nearly simultaneously with the same apparatus. We observed somewhat more shadowing than did most experiments at lower photon energies.
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The total cross section of hadron photoproduction on C, Cu and Pb nuclei is measured for six energy values in the range 12–30 GeV. The obtained cross-section values for C and Cu nuclei have a weak energy dependence at high energies (above 20 GeV). The cross section for the Pb nucleus is somewhat higher in comparison with that expected, and energy dependence is not observed. The A -dependence of the effective number of hadrons agrees with VDM predictions.
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A-EFFECTIVE/A = SIG(GAMMA A)/(Z*SIG(GAMMA P) + (A-Z)*SIG(GAMMA N)) WHERE SIG(GAMMA P) = (98.7 +- 3.6) + (65 +- 10)/SQRT(P) MUB, SIG(GAMMA N) = SIG(GAMMA P) - (18.3 +- 6.1)/SQRT(P) MUB AND A IS 12, 64 AND 207 FOR THESE NUCLEI.