Longitudinal instability in the Fermilab accumulator during slow transition crossing

Recently the Fermilab Accumulator was modified for use in a medium energy experiment studying charmonium states. The experiment required a circulating antiproton beam with momenta between 6.7GeV/c and 3.7 GeV/c. During accumulator transition crossing with this coasting beam, longitudinal instability was observed with a resistive wall current monitor and a dedicated longitudinal Schottky detector. Results are presented of measurements in which longitudinal coherent signals and emittance growth were observed. The data are compared to the predictions of a multiparticle computer simulation.<
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