Proceedings of ICRC 2001:1836 () Copernicus Gesellschaft 2001

We use a new version of our numerical model for particle propagation in the Galaxy to study radioactive secondaries. For evaluation of the production cross sections we use the Los Alamos compilation of all available experimental cross sections together with calculations using the improved Cascade-Exciton Model code CEM2k. Using the ra- dioactive secondary ratios 26AI/27A1, 36C1/C1, a4Mn/Mn, we show how the improved cross-section calculations together with the new propagation code allow us to better constrain the size of the CR halo