An Algorithm for Calculating the Spin Tune in Circular Accelerators

A new algorithm for calculating the spin tune and the n-axis for circular accelerators is presented. The method resembles the one employed in the existing program code SODOM in that one-turn numerical spin maps at equally spaced orbit angle variables are used but it is more efficient than the latter. Furthermore, it is applicable at large openning angles of the n-axis, whereas the existing SODOM only converges for small angles.