Multilayer cylindrical magnetic screens

The design is described of a horizontal multilayer cylindrical magnetic screen with end covers, which substantially reduces the mechanical stresses in the cylinders in experiments on particle beams. Two permalloy screens have been made for use in nuclear physics and magnetobiological studies: five-layer and eight-layer ones with internal volumes of 1.4 and 0.02 m3 correspondingly. The screen characteristics have been examined: the transverse and longitudinal screening coefficients, and also the distribution and stability of the residual magnetic field. A simple method is proposed for magnetizing the screens, which greatly increases the screening coefficients. A method is also described for increasing the longitudinal screening coefficient by means of two-layer end covers. Such cylindrical screens enable the introduction and extraction of the particle beam in a simple fashion, and also the location and extraction of measuring equipment and specimens