C-Arapuca: A new device for Cherenkov radiation detection

Many high-energy physic experiments use Cherenkov radiation as a detection method. Photomultiplier tubes are typically used to convert the radiation into an electrical signal. In this work, we present the development of a new device dedicated to the detection of Cherenkov radiation photons that could replace photomultiplier tubes in experiments that detect this radiation. C-Arapuca is the name given to this device, as it uses the concept of photon trapping in a box, already used in the Deep Underground Neutrino Experiment, but now adapted for the detection of a range of energies of Cherenkov radiation photons. Calculations of efficiency, design, and performance of the C-Arapuca are described, highlighting its performance compared to photomultiplier tube in the detection of Cherenkov radiation. A shortpass dichroic filter with a cut-off wavelength at 400 nm was used in the C-Arapuca window, and the inner part of the box, covered with highly reflective material, contains a blue-emitting wavelength-shifting plastic slab and Hamamatsu silicon photomultipliers. In this study, a cylindrical tank containing 550 liters of ultrapure water was used, in which two C-Arapucas and a photomultiplier tube with a photocathode of 110 mm in diameter were installed. The useful area of the optical window of a C-Arapuca is 70.0 x 93.0 mm². Relativistic muons from local cosmic radiation passing through the water volume were used as a source of Cherenkov radiation detected by both the C-Arapucas and the photomultiplier tube, allowing for a relative comparison of the performance of the new device.