Introduction: The Princeton-Pennsylvania Accelerator, a 3 BEV proton synchrotron with a 20 per second pulse rate, has been in operation for two years. The 3 BEV beam can supply an average of 1012 protons per second to an internal target. Construction of this machine was started in 1959. Primarily because of the high repetition rate, there were many new problems, both for the magnet and the rf system, which had to be solved. References 1 through 5 describe these problems, and the methods used to solve them.

Some of the most difficult problems were in the field of instrumentation. The radio frequency system spanned the range from 2.5 to 30 mc, and modern electronics techniques were just able to provide precision analog and digital instrumentation over this range. A precision (0.01%) frequency to voltage converter used to stabilize the master oscillator has been described in reference 2.