Excitation rates for transitions in Ca XV

Collision strengths for transitions among the energetically lowest 46 fine-structure levels belonging to the (1s ^2) 2s ^22p ^2, 2s2p ^3, 2p ^4, and 2s ^22p3 l configurations of Ca XV are computed, over a wide electron energy range below 300 Ryd, using the Dirac Atomic R-matrix Code (DARC) of Norrington & Grant (2003). Resonances in the threshold region have been resolved in a fine energy mesh, and excitation rates are determined over a wide electron temperature range below 10 ^7 K. The results are compared with those available in the literature, and the accuracy of the data is assessed.