Smithsonian Report, 1964. — Cowan 



PLATE 2 



1. One of the thin "ineaL" tanks fur the "duuble-decker club sandwich" detector. This 

 tank, containing scintillating solution and a cadmium salt, was used for analysis of the 

 detector and calibration of its performance. It was replaced by a tank of water and 

 cadmium acetate (later heavy-water and cadmium acetate) for the measurement at the 

 reactor. There were, of course, two of these target tanks in the detector. It is shown 

 resting in a special fork-lift built to handle the detector sections. 



2. A completed detector section ready for insertion in the shield. The tank is made of 

 steel plate, with the exception of the bottom. This is a cellular aluminum structure, 

 similar to aircraft skin sections, which provides strength against bending while affording 

 little obstruction to the entry of gamma rays from below. 



