Speaker
Description
Multigap Resistive Plate Chambers (MRPCs) are gaseous detectors of choice for nuclear and particle physics experiments given their excellent time resolution, high efficiency and low cost. Among others, two large-area experiments have employed MRPCs for over 15 years: the ALICE Time-of-Flight (TOF) detector at the LHC and the Extreme Energy Events project (EEE).
The ALICE TOF is a key Particle IDentification (PID) system at intermediate momenta. It consists of $1593$ MRPCs ($\sim900$ cm$^2$ each) operating with a mixture of C$_2$H$_2$F$_2$ (93$\%$) and SF$_6$ (7$\%$), covering an active area of $\sim140$ m$^2$ with over $150000$ readout channels. A global time resolution of $\sim$60 ps has been achieved, with stable performance since 2009 and no signs of degradation. During LHC Long Shutdown 2, the readout and the online-offline (O$^2$) framework were upgraded to handle the targeted 50 kHz Pb–Pb interaction rate via a continuous readout scheme. The TOF performance along with selected PID results from LHC Run 3 will be discussed.
The same technology with a different layout is employed in the Extreme Energy Events project, a network of $\sim 50$ tracking telescopes mostly hosted in Italian high schools studying cosmic rays and supporting outreach. Each telescope consists of three MRPCs ($\sim13000$ cm$^2$ each) operated until 2020 with a $\text{C}_2\text{H}_2\text{F}_4$ ($98\%$) and $\text{SF}_6$ ($2\%$) mixture. Recent R&D efforts focus on eco-friendly gas mixtures such as helium- and R1234ze-based solutions, now in use in several telescopes. A compact gas recirculation system is also under development to reduce gas consumption. Detector performance with the new gas mixtures and preliminary recirculation tests will be presented.