The analyzer can be operated either internally or externally. The 10 ma germanium discriminator is quiescently biased to 8.5 ma in its low-voltage state. An input signal current of 3.5 ma or more triggers it to its high voltage state. This triggers the oscillator. The oscillator signal is buffered and mixed in the bridge modulator with the reference radiofrequency signal from the cyclotron. The low-frequency beat note from the bridge modulator is squared up and passed to the beat zero univibrator which generates 0.7 mu sec signals each time the beat note passes through zero from positive to negative. The trailing edge of the beat zero univibrator is employed to terminate the time-of-flight measurement and to control the servo measurement. Drawings are included. (M.C.G.)

The polymerization of vinyl monomers can be initiated by heat, ultraviolet radiation, and various catalysts. More recently, ionizing radiation has been shown to effectively initiate vinyl polymerization. However, polymerization in the solid state by ionizing radiation is not reported in the literature, although several papers have been published that describe briefly the thermal polymerization of divinyldiphenyl, Leuch's anhydride and in greater detail the peroxide catalyzed polymerization of acetaldehyde. The purpose of this note is to describe some experiments which demonstrate that crystalline acrylamide undergoes polymerization upon irradiation with γ-rays from an intense Co-60 source. Below its melting point the monomer shows little or no tendency to polymerize thermally.