Smithsonian Report, 1964. — Cowan 



Plate 4 



1. The lower "triad" of detectors of the system used at the Savannah Ri\-er Plant rests 

 in its lead shield ready for test at the Los Alamos Scientific Laborator}'. The dark 

 rectangles labeled "2" and "3" are the ends of the large liquid scintillation tanks which 

 were to form the "bread" of the club-sandwich-detector. The target liquid is in the 

 white center tank. 



2. This multichamber dark-box was built to put each of the many photomultiplier tubes 

 through a rigorous testing and balancing procedure before use in the detector. Three 

 chambers are shown opened, and a photomultiplier with a sodium iodide crystal may be 

 seen in one of them. The tubes were thus carefully selected for uniformity and stability 

 from a large number of candidates. 



