Speaker
Description
Resistive Plate Chambers at the CERN LHC experiments are operated with gas mixtures based on R-134a, i-C4H10 and SF6. R-134a and SF6 are potent greenhouse gases, known for their high Global Warming Potential, and are therefore subject to decreasing availability due to the European regulation on F-gases.
A mid-term solution was identified in reducing the use of R-134a by diluting the standard gas mixture with 30% CO2. However, to keep the detector performance stable, the SF6 concentration has to be increased from 0.3% to 0.5% or 1%.
This contribution shows the performance of RPCs operated with alternatives to SF6, in particular with two gases from the family of chlorinated hydrofluoroolefins: R-1233zd and R-1224yd.
The performance is shown using the standard CMS gas mixture as a reference, as well as the ATLAS RPC gas mixture containing 30% CO2.
The detectors were operated in laboratory conditions with cosmic muons for gas mixture tuning. Once suitable gas mixtures were found, the RPCs were tested at CERN’s Gamma Irradiation Facility, where a gamma source provided background conditions similar to those expected at the High-Luminosity LHC, and a muon beam allowed the detection efficiency to be evaluated.
The increased concentration of isobutane and the use of reclaimed R-134a with RPC operated in laboratory condition is also investigated, and preliminary results will be presented.