Single-bunch extraction at the 88-Inch Cyclotron

The extraction system of the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory has been modified to enable single-bunch extraction. This is achieved by increasing the voltage of the first deflector to oversteer the beam, halting extraction, and then selectively switching it off using a high-voltage chopper to synchronize the deflector’s operational voltage with the transit time of a single bunch, enabling its extraction. A pre-chopper positioned before the cyclotron limits the beam available for acceleration, minimizing activation and sputtering damage from discarded bunches. This cost-effective technique is crucial for time-sensitive experiments and provides precise control over dose delivery, broadening the cyclotron’s range of applications. Future efforts will focus on increasing extraction frequency by optimizing the deflector electronics for faster recovery times, and exploring sequential switching of two deflectors to reduce the required oversteering voltage.