Efficiency and temporal response of p-terphenyl based wavelength shifting films on H12700 multi anode photomultipliers

Wavelength-shifting (WLS) films of p-terphenyl have been applied by means of dip-coating on the entrance window of the H12700 multi anode photomultiplier (MAPMT) in order to enhance the UV sensitivity. Using coated and uncoated MAPMTs in a CBM RICH testbox in a proton testbeam at the COSY accelerator, an enhancement of the number of hits per ring of 15%–20% depending on cuts has been observed. Due to new fast readout electronics of the RICH detector for the CBM/ HADES experiments, the time response of p-terphenyl has been measured to show a decay constant of 2.35 ns. This compares well with time-resolved fluorescence measurements of the films.