A Fast Chopper System at SARAF to Enable RFQ Single Bunch Selection

We describe a recently commissioned "fast chopper" system which enables RFQ single bunch selection at SARAF. SARAF is an RF accelerator operating at 176 MHz. The SARAF RFQ accelerates and bunches the incident DC beam to enable further acceleration by the superconducting RF resonator cavities. We have developed a "fast chopper" system that makes possible single RFQ bunch selection based on an original idea developed at Soreq. Electrostatic deflection plates before to the RFQ deflect the DC beam either to the right or to the left of the RFQ opening, where only during the polarity switch can a non-deflected beam pass through the RFQ opening. Proper tuning of the deflection parameters allows for single bunch transmission through the RFQ, with subsequent acceleration in the superconducting linac. We describe results of the most recent developments, and discuss points for further improvement. Single bunch selection makes possible neutron time-of-flight measurements at SARAF.