Mc/sec signal obtained from the 5-Mc/sec output from an Atomichron by multiplication in a Gertsch FM4A frequency multiplier. The 29. 595-Mc/sec i. f. signal is amplified and mixed in a phase dis-criminator with a similar signal froma Gertsch AM-1 stabilized oscillator. The resultant low-Yrequency signal passes through an BC filter, which limits the detector's over-all bandwidth, apd is displayed on an oscilloscope. In addition to oscillation, stimulated emission has also been observed. In this case oscillation is completely suppressed by shortening the mean time in the bulb (by means of a larger entrance aperture) or by loading the cavity. A pulse of rf at the transition frequency is fed into the cavity by a second coupling loop (not shown in Fig. 1). If this pulse is of the correct intensity the elec-tron spin of the atom is precessed 90', and the atom will continue to radiateafter the rf has been turned off. A picture of the …