Ultraslow extraction with good duty factor

In the framework of antiproton physics at CERN, a new Low Energy Antiproton Ring (LEAR) is being designed. In the basic mode, it will serve as a beam stretcher giving spill times in the region of an hour. The spill phi (t) must, of course, have a good duty factor ( phi )/sup 2//( phi /sup 2/). A method employing 'stochastic extraction' has been studied theoretically and tried out at the CERN PS ( approximately 9 s flat top) where an extremely good duty factor has been achieved, showing that much longer spill times will be practicable. The pulse length can be varied within wide limits given by the ripple, the momentum acceptance and the intermodulation distortion of the amplifier chain for the noise power. In addition, another method has been found effective which uses empty buckets. These methods need no servo system and both can easily be applied to other synchrotrons. (6 refs).