A large aperture superconducting dipole for beta beams to minimize heat deposition in the coil

The aim of beta beams in a decay ring is to produce highly energetic pure electron neutrino and anti-neutrino beams coming from b-decay of ¹⁸Ne¹⁰⁺ and ⁶He²⁺ ion beams. The decay products, having different magnetic rigidities than the main ion beam, are deviated inside the dipole. The aperture and the length of the magnet have to be optimized to avoid that the decay products hit the coil. The decay products are intercepted by absorber blocks inside the beam pipe between the dipoles to protect the following dipole. A first design of a 6T arc dipole using a cosine theta layout of the coil with an aperture of 80 mm fulfils the optics requirements. Heat deposition in the coil has been calculated using different absorber materials to find a solution to efficiently protect the coil. Aspects of impedance minimization for the case of having the absorbers inside the beam pipe have also been addressed.