Time-of-Flight measurements with a detector using a liquid Cherenkov radiator-prototype of a possible TOF detector for the Super-FRS at FAIR

Aiming to develop a Time-of-Flight (TOF) detector with a precision down to about 50 ps (σ) in time, radiation hard and operating with a high radiation rate of relativistic heavy ions of up to 10⁷ per spill of 1 to 10 s., we have constructed a new Time-of-Flight Cherenkov detector based on an Iodine-Naphthalene liquid radiator. This fluid with high refractive index (n=1.7003) was chosen to cover the corresponding velocities of the ions β∼ 0.59-0.92 at the future Super-FRS at FAIR. The application of a liquid radiator allows to circulate the material and therefore greatly reduce the effects of a degradation of the optical performance during exposure to the high ion rates and radiation dose at the focal planes of the Super-FRS. The key properties of the prototype of a TOF-Cherenkov detector have been investigated in measurements with nickel ions at GSI in 2014. More recently, TOF measurements were performed with xenon ions at 600 MeV/u at GSI in 2016 and a timing resolution of 63 ps (standard deviation σ) was achieved.