Magnetic sextuplet as a zoom lens for the nuclear nanoprobe at the Louisiana Accelerator Center

Abstract

A new quadrupole focusing system-magnetic sextuplet (RMS), with the same symmetry as the Russian quadruplet (RQ), has been proposed and is presently under development. The RMS has the same demagnifications and the same focal lengths as the RQ system and it can have the same spherical aberration in both planes. Its main feature, however, is the capability to change the demagnification over a wide range from 1 to greater than 1000 by changing the excitation of the middle lenses. In the RMS it is possible to obtain a point crossover between the middle lenses with a corresponding minimum sensitivity to the relative rotation of both triplets around the longitudinal axis. By changing the excitation of the middle lenses, the optimal demagnification for every emittance can be found and for every beam emittance it is possible to achieve a minimum spot size by varying the sizes of collimator diaphragms and the distance between them. All capabilities of the RMS are numerically investigated and the smallest beam spot size and appropriate optimal parameters of the system have been found for different emittances.