Larry O. Oswald

30-INCH PROPANE BUBBLE CHAMBER

A propane bubble chamber with a sensitive volume of 30½ in. by 21½ in. by 6½ in. deep operating in a magnetic field of 14 000 gauss is described. Operating parameters and some engineering details are given. The part of the chamber containing the propane is hydrostatically supported in oil through which the chamber is photographed. This permits the use of small glass windows with a large safety factor.

Thirty‐Six‐Atmosphere Diffusion Cloud Chamber

A 36‐atmosphere diffusion cloud chamber has been constructed for use with the 184‐inch cyclotron and with the bevatron. Minimum‐ionizing particles leave dense, sharp tracks of good contrast with hydrogen filling at design pressure. In the operation described, one event is obtained every 15 minutes for a reaction cross section of 30 mb for negative pions on hydrogen. Among the unique features of the chamber are (a) the high pressure; (b) the high magnetic field; (c) the simple unit preassembly of the chamber and the upper pole piece; (d) the distortion‐free photography afforded by the small camera windows of good optical quality directly in front of the camera lenses and the absence of a large top glass near the sensitive region; (e) the thin window for collimated beams; (f) the supported cast Astrolite windows for illumination; and (g) the satisfactory sensitive layer obtained despite the large height‐diameter ratio of the pressure vessel.

BRIGHT-FIELD BUBBLE CHAMBER ILLUMINATION USING A BEADED REFLECTIVE SCREEN

Bright‐field illumination using a beaded reflective screen is accomplished in the 30‐in. heavy liquid bubble chamber by using separate light sources for each lens. The resolution obtainable is about four times as great as with dark‐field illumination.

Propane Bubble Chamber in a High Magnetic Field

A liquid propane chamber 3.25 by 6.5 by 13 in., operating in a magnetic field of 22 000 gauss, is described. A simple compact dark‐field type of illumination is used; this is discussed. For personnel and equipment safety a secondary pressure vessel is incorporated in the design. Special reference is given to some of the construction and design problems.A brief summary of the operation of the propane chamber in the 6.2‐Bev neutron beam is given.