Upgraded sinusoidal beam chopping system at CYRIC

The sinusoidal beam chopping system installed in the neutron time-of-flight (TOF) beam line at CYRIC was upgraded during the construction of the new K110 AVF cyclotron. In order to achieve high stability of the RF phase under easy control, a new low-level RF electronics was designed and built using a direct digital synthesizer (DDS). The new control system for the beam chopper was also developed on the basis of programmable logic controllers (PLC). The performance tests were successfully carried out with proton beams from the cyclotron. The present beam chopping system has covered a wide dynamic range from 325.5 to 1000 ns for neutron TOF measurements at CYRIC.