Stacking simulations in the beta-beam decay ring

The so-called beta-beam concept for accelerator-driven neutrino experiments envisages the production of a pure beam of electron neutrinos (or their antiparticles) through the beta-decay of radioactive ions circulating in a highenergy storage ring. An unprecedented number of ions must be collected in the decay ring and maintained in a few short bunches. Stacking is unavoidable to match the available source rates with this demand. A new stacking method makes use of off-momentum injection into the decay ring to approach the circulating beam without requiring ultra-fast injection elements, rotation in the longitudinal plane to bring the fresh bunches onto the central orbit and asymmetric merging to transport these ions into the centre of the large stack. Simulation results are presented for the repetitive stacking process for two candidate ion species of significantly different charge-tomass ratio.