Frequency control: Report on the 19th annual symposium…

Specialists in frequency control are improving their crystal vibrators and atomic frequency standards. Toward better crystal devices, they are making filter crystals that operate above 30 Mc/sec; with better mathematical analysis of vibration modes to help, they are using electrode‐thickness tuning and crystal shaping to improve crystal response; they are using sound waves and x rays to investigate vibration‐mode patterns. Some are seeking new materials to replace quartz, especially endowed by nature to function as a frequency standard. Others have used quartz in a new way to make a new kind of delay line. Toward better atomic frequency standards, they are improving both stability and accuracy. All‐solid‐state versions are making rubidium gas‐cell standards and cesium‐beam standards more useful. Other improvements in atomic devices include better circuits for hydrogenbeam tubes, narrower reference lines, and better frequency stabilities, both long‐ and short‐term.