Measurements of intrabeam scattering rates below transition in the Fermilab Antiproton Accumulator

An important factor in the successful operation of the Antiproton Recycler Project at Fermilab is the rate at which intrabeam scattering heats the stored beam in each plane. This machine will operate below transition energy. An application of classical intrabeam scattering theory for such a machine indicates that transverse or longitudinal cooling might occur, rather than heating, under certain conditions. However, this effect has not been studied experimentally. Hence, we have undertaken a study of the heating/cooling rates below transition in a coasting antiproton beam in the Fermilab Accumulator Ring, in an attempt to verify the theoretical models in this regime. This storage ring employs a variety of stochastic cooling systems which can be used to alter the ratio of emittances in each plane as the initial conditions for our experiment. We have used both a conventional free-expansion technique as well as a longitudinal-echo-decay-rates technique to determine the scattering rates. In this paper, we present a preliminary analysis of our data and its comparison with various intrabeam scattering models below transition