Magnetic Analyzer for Nuclear Reaction Products

Abstract

A magnetic analyzer for nuclear reaction products has been built which employs a sector-shaped uniform magnetic field. The shaped sectors are inserted in the 8.5-in. gap of a C-shaped magnet with a 12×12 in. cross section. The iron core is 54×33 in., and 69 360 ampere-turns give 13 500 gauss across a total air gap of 1⅝ in. In the notation of W. G. Cross, [Rev. Sci. Instr. 22, 717, (1951)], the parameters were: ρ=15 in., φ=60°, useful gap=1.5 in., l′=22.5 in., l″=45 in., ε1=+46°38′, ε2=−18°21′, max usable α=±3°, max usable ω=±1.6°. The entrance boundary was straight, and the exit boundary had a convex curvature of 123.7 in. The boundaries of the sector and the locations of the object and image positions were corrected for the effect of the fringing field. The observed l″ was 46.5 in. Fringing field focusing in the direction perpendicular to the plane of deflection was not as strong as calculated; the maximum image height was 2 in. The magnet is capable of bending 12-Mev protons and has an energy resolution of 300 for the maximum useful solid angle of 1/2000 of 4π steradians. The observed maximum energy resolution was 400. The advantages of this magnet are simplicity of construction and ease of adaptation to other sector parameters.