Development of prototype RICH detector with multi-anode photomultipliers for radioactive ions

RI-RICH, a ring-imaging Cherenkov counter for radioactive ions, has been developed to measure the velocity of the ions at intermediate energies. Our RI-RICH system consists of six multi-anode photomultiplier tubes covered with 360-nm bandpass filters and a radiator made of quartz or BK7. For the primary 132Xe beam with a velocity of β = 0 . 712 , a velocity resolution of Δ β ∕ β = 4 . 9 × 1 0 − 4 (one standard deviation σ ) and a detection efficiency of more than 99.99% were achieved. For the secondary beams with Z = 44 – 55 and β ≃ 0 . 70 , we successfully performed particle identification using the B ρ - Δ E - β method. The velocity resolutions of RI-RICH for these nuclides were equivalent to a more than 6 σ separation for the mass number.