Beam optics of upgraded high energy heavy ion microbeam in Lanzhou

In order to expand applications of the Lanzhou microbeam the resent improvements were introduced in its slits, lens system and target chamber. In this study a beam optics of the new system was calculated for the 12C+6 ion beam of 966 MeV. To compensate a negative influence of a sector magnet dispersion on the beam dynamics an excitation of the magnetic quadrupole between two bending dipoles was determined. By varying parameters of the final triplet of magnetic quadrupole lenses a set of the microbeam systems with a stigmatic focusing were obtained. The best two of them were selected applying an optimization for a beam collimation by object and divergence slits. Simulation of the beam dynamics after the collimation allowed to determine the slit sizes that provide the highest current in the 1 µm probe on the target for these microbeam systems.