High gradient cavities for long bunch muon beams

The large energy spread of muon beams can be reduced by so-called phase rotation. It requires rather low frequency or long slope in the RF waveform and rather high gradient field against the short muon lifetime. Because such a low frequency high gradient RF cavity is difficult to construct, a high frequency bunching system is proposed. The bunching system located after 100 m from a production target can bunch a muon beam of 100 MeV ±50% with 200 MHz RF, and a 100 MHz bunched muon beam is obtained at the 200 m position