Dark current and X ray measurements of an 805 MHz pillbox cavity

The muon cooling systems proposed for neutrino factories require low frequency (201 MHz) RF cavities with Be windows, at high gradient (Eacc ∼ 16 MV/m), in strong solenoidal magnetic field (∼ 5 T). For the proposed Muon Ionization Cooling Experiment (MICE), an experimental demonstration of cooling, we have an additional constraint that we must operate sensitive particle detectors very close to the RF cavities, which produce backgrounds from dark currents and X rays. To understand the processes involved in cavity conditioning and operation near particle detectors, we have constructed a test facility at Lab G of Fermilab, where a 5 Tesla superconducting solenoid, a 14 MW peak power klystron and a pillbox test cavity at 805 MHz are available. We present measurements of dark currents, X rays and surface structure from the pillbox cavity, with both copper and beryllium endplates, and discuss the interaction between surface structure and radiation backgrounds produced.