A damper for the p injection oscillations in the PS machine

After accumulation in the AA ring, at 3.5 GeV/c, the antiprotons are injected as a low intensity (10 9 , 10 10 ppb), 80 nsec singlte bunch into the PS machine, accelerated up to 26 GeV/c and then transferred to the SPS collider. Random transverse errors at injection into the PS lead to beam oscillations which increase the transverse emittances and decrease finally the luminosity in the collider. As part of the improvement program for the pp run at the end of last year a 'damper' has been installed in the PS to counteract such oscillations. This paper describes the justifications, the technical solutions and the results of such an equipment.