The Northwestern University 50 cm Liquid Helium Bubble Chamber

摘要

The Northwestern University 50 cm liquid helium bubble chamber had its engineering run at the University of Chicago cyclotron in October 1965, after a construction and testing period of just under 2 yr. The chamber dimensions are approximately 50×25×32 cm, and the water‐cooled magnet can provide a field of 30 kG. The chamber and magnet, which weigh about 2.2×105 N, can be lifted into a beam site while in operational condition, and the chamber and magnet require a space of only 7.6×4.5 m in the beam line. The expansion is performed by a bellows located above the magnet. A repetition period of 1.2 sec/pulse has been achieved continuously. The optical system uses dark field illumination with three cameras which view the entire chamber with a maximum stereo angle of 16°. The cameras use 35 mm film and have a demagnification of 1/12. The chamber has produced approximately 106 useful photographs in three separate runs, and these pictures are currently being analyzed.