The 25-Inch Liquid Hydrogen Bubble Chamber

Abstract

A new 25-inch liquid hydrogen bubble chamber incorporates into its design many, improvements and several unique features. Unique to this chamber is a movable top window that serves both as the piston for the liquid-expansion system and as an optical condenser lens. The motion of this window is controlled by a single-convolution bellows welded into the chamber perimeter; use of such a bellows avoids frequencyresponse problems common with multiconvolution bellows. Due to the action of this top window, turbulence is virtually eliminated because no liquid either enters or leaves the chamber. The aspherized condenser lens system is believed to be approximately five •to ten times more efficient than any installed in earlier machines of this • ~ize. We couil.t fewer ghost reflections, observe more uniform bubble tracks, and enjoy greater simplicity of operation than before. A scattering angle of 12 ° improves photographic uniformity in depth and avoids the need for individual light sources for each stereo lens. This. chamber combines a high degree of pre~ision with a rapid operating cycle. At present the chamber can be operated twice during each Bevatron pulse, thus doubling the number of pictures taken. A conventional water-cooled magnet provides a vertical field of 18.5 to 22.8 kilogauss .

Hybrid Bubble Chamber Systems

“…A sliding piston with rings not only leaks liquid from the chamber to the region behind the piston, thereby reducing expansion efficiency, but it also produces a large amount of heat as a result of sliding friction. Eckman (10) introduced the use of a single-convolution bellows on the LBL 25-in chamber, and most fast chambers now have such a bellows in one form or Annu. Rev another.…”

“…However, there are special cases in which the decay angular distribution of the forward meson is well understood, and the object is to study a complicated N* or y* state left behind in the bubble chamber. Examples of such reactions are n ± p-+pN* l:::+"" 10. and n ± p-+ K*Y*…”