Computation of the magnetic field of a spectrometer in detectors region

Computed results of the 3D magnetic field of a spectrometer intended for investigation of hadron production of charmed particles and the indication of the narrow resonances in neutron-nucleus interactions are presented. The methods used in computations: finite element method and finite element method with suggested new infinite elements are described. For accuracy control the computations were carried out on a sequence of three-dimensional meshes. Special attention is devoted to behaviour of the magnetic field in the basic detectors (proportional chambers) region. The performed results can be used for the field behaviour estimate of similar spectrometer magnets.