A large and thin superconducting solenoid for TOPAZ detector

The TOPAZ electromagnet is a very large, thin superconducting magnet for a detector used for the TRISTAN project now being advanced in the National Laboratory for High Energy Physics. Four laboratories are placed at the middle of straight parts of the TRISTAN ring having about 1 km diameter, installed about 13 m underground, and the TOPAZ electromagnet is installed in Tsukuba Laboratory. The tracks of charged particles resulted from the collision of electrons and positrons are detected with a drift chamber and a time projection chamber, while photons without charge are detected with a lead glass counter, and μ particles are detected with a muon detector. The TOPAZ electromagnet is that generating a magnetic field for measuring momentum. Its basic design was carried out by the National Laboratory for High Energy Physics, and the manufacture was carried out by Furukawa Electric Co., Ltd., Fuji Electric Corp. and Ishikawajima Harima Heavy Industries Co., Ltd. The performance test using air core was successfully finished, and the solenoid was delivered to the Laboratory. The construction and the features of the electromagnet, the manufacture and test are reported. The development of internal winding method was made for the first time in the world. (Kako, I.)