We analyze the collisional Penrose process between a particle on the innermost stable circular orbit (ISCO) orbit around an extreme Kerr black hole and a particle impinging from infinity. We consider both cases with non-spinning and spinning particles. We evaluate the maximal efficiency, ηmax=(extracted energy)/(input energy), for the elastic collision of two massive particles and for the photoemission process, in which the ISCO particle will escape to infinity after a collision with a massless impinging particle. For non-spinning particles, the maximum efficiency is ηmax\approx 2.562 for the elastic collision and ηmax\approx 7 for the photoemission process. For spinning particles we obtain the maximal efficiency ηmax\approx 8.442 for the elastic collision and ηmax\approx 12.54 for the photoemission process.
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