The design and construction of a 13‐stage electron multiplier tube are discussed. Electrodes formed from BeCu alloy sheet are used and the method of activating these surfaces is described. The over‐all multiplication of this type of tube is about 107. The efficiency of the tube as an electron counter is 100 percent for electrons of 500 ev and decreases to 40 percent for electrons of 6 kev. Preliminary results indicate that the efficiency as an alpha‐particle counter is also 100 percent.

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