The FLNR JINR wide aperture separator COMBAS

The high-resolution wide aperture separator COMBAS was installed and commissioned in the Flerov Laboratory of Nuclear Reactions, JINR (Dubna) [Nucl. Instr. and Meth. A 306 (1991) 123; 426 (1999) 605; 479 (2002) 467]. It is designed for in-flight radioactive beam production of short-lived isotopes and experiments with them. The separator operates in the (20-50)A MeV ion energy region. It consists of the two stages, dispersive and achromatising. The second half of the separator is a mirror symmetrical counterpart of the first one, the intermediate focal plane being the plane of the symmetry. Multipole magnets with special profiled poles are used to correct higher order aberrations at the intermediate and final foci. The 3D magnetic measurements of the analysing magnets of the separator were done. The KOMPOT program for the 3D magnetic field calculations [Doinikov et al., 1986, Preprint/CNNI atominform: B-0741, 13p; Belyaev et al., Int. Conf. 'Optimisation of Finite Element Approximations', St.Pt., Russia, 25-29 June 1995, p.101; IEEE Transact. On Magnetics, 28 (1) (1992) 908; Frenkel, Selected works, USSR Academy of Sciences publ., Moscow-Leningrad, v.1 (Electrodynamics), 1956; Proc. IEEE, 114 (7) (1967) 995; Livingston, Blewett, Particle accelerators, No. 7, McGraw-Hill, 1962, p. 253] was used for the analysis of these magnetic measurements data, as well as for the reconstruction of the magnet fields inside the total volume closed by the 3D surface, where the magnetic measurements had been performed. As a result of the magnetic field reconstruction we obtained field maps, which would be used in simulations of particle trajectories