RF Exercises Associated with Acceleration of Intense Antiproton Bunches at Fermilab

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Abstract
Antiprotons for the Fermilab pp collding beam project (Tevatron I) will be extracted from an 8 GeV accumulation ring in a few (1 to 3) bunches of ~ 1011, a single bunch at a time. To preserve the stack as a source of subsequent bunches, each bunch will be removed from the dense core of the stack with an isolated bucket at harmonic number h = 2. The longitudinal emittance of the bunches will be in range 1.5 to 2. eVs, roughly five times what the Main Ring usually accelerates with the installed 53 MHz rf system. Therefore, the bunch is to be narrowed on the Accumulator extraction orbit to match a 2.5 MHz bucket in the Main Ring. By raising the 2.5 MHz voltage (harmonic number h = 53), the bunch will be further narrowed in the Main Ring to span seven buckets of the prinipal system (h = 1113). The bunch will then be captured adiabaically from the h = 53 bucket into seven adjacent h = 1113 buckets for acceleration to a 150 GeV flattop. At this energy the 2.5 MHz and 53 MHz systems will be used jointly to coalesce 3the seven bunches into a single h = 1113 bucket for injection into the Energy Doubler. This paper describes unstacking in the Accumulator, the adiabatic capture into seven bunches in the Main Ring, and the coalescing of the seven back into one bunch at 150 GeV.

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