Development of the Detector Control System for the LHCb RICH Upgrade

LHCb is one of the four main experiments running at the Large Hadron Collider (LHC). Its main purpose is to perform precise measurements to study CP violation and rare decays of b and c quarks. The RICH detectors are crucial components in identifying these decays by providing identification of charged hadrons. The LHCb experiment is currently undergoing an upgrade during the long shutdown (2019-2020) in order to run with a five-fold increase in the instantaneous luminosity. The LHCb detector will be readout at the full LHC bunch-crossing rate of 40MHz. This will allow to fully exploit the delivered luminosity of =2*〖10〗^33 〖cm〗^(-2) s^(-1) during the upgrade [1]. The upgraded RICH detectors will have significant modifications to RICH1 optics and mechanics. Moreover, new photo detectors and frontend electronics will be installed in both RICH1 and RICH2. This will require a new Detector Control System (DCS) to ensure proper running of the upgraded RICH detectors. Both must run at the maximum performance, but at the same time be safe to operate without damaging any fragile electronics or mechanical parts. Namely three different environmental conditions need to be monitored within RICH detectors: temperature, pressure and humidity. These conditions are measured using different sensors which must be tested, calibrated and implemented within the DCS and Detector Safety System (DSS) before being hard-wired to the detectors. Level of precision in monitoring these conditions is directly related to the ability to properly determine the mass of a particle and thus determine its type. Charged particles pass through C_4 F_10 gas present in the vessel. Due to Cherenkov Effect, photons are emitted at an angle relative to the trajectory of the track, called Cherenkov angle. This angle is given by: cos⁡〖θ=1/(β*n)〗 where cos⁡θ is the Cherenkov angle, β is the speed of a particle over the speed of light and n is the refractive index of a gas in the vessel. To identify mass of a particle, β is desired and thus, we also need to know the refractive index, n, precisely. Because n=n(p,T), the extent to which we know n is determined by our ability to precisely measure pressure and temperature [2,3].