arXiv:astro-ph/9808033v2 14 Oct 1998 THE PHOTODISINTEGRATION OF COSMIC RAY NUCLEI BY SOLAR PHOTONS: THE GERASIMOVA-ZATSEPIN EFFECT REVISITED Gustavo A. Medina-Tanco 1,2 and Alan A. Watson 2 1. Instituto Astronˆ omico e Geof´ ısico, University of S˜ ao Paulo, Brasil gustavo@iagusp.usp.br 2. Dept. of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK a.a.watson@leeds.ac.uk Received ; accepted