Beam Abort System for the NAL 500 BeV Synchrotron

An internal beam dump is designed for the NAL main ring to dispose of circulating beam at any time during the acceleration cycle. An abort at full beam power is an emergency procedure, but activation of the system at the end of every cycle purges unextracted protons and provides a continuous check on system operability. The system consists of a full aperture vertical orbit bump in a 50 m drift space which carries the beam onto a 6 m aluminum and steel dump. Four 12.8 kG vertical bending magnets excited from individual 18 kJ capacitor banks provide a full aperture kick in 84 ¿s. Monte Carlo calculations show that primary stopping efficiency of about 99.8% can be expected, but that local heating problems will require a cautious approach to full beam power dumping.