Investigation of wavelength shifter properties of p-terphenyl and TPB

Wavelength shifter materials like p- Terphenyl and Tetra Phenyl Butadiene (TPB) of thick- nesses between 65 and 250 µg/cm 2 have been studied in order to improve the quantum efficiency (QE) of a pho- tomultiplier in the UV range. The best result has been obtained for p-Terphenyl of 100 µg/cm 2 thickness. In this case the quantum efficiency integrated over a broad range of photon energies up to 6.2 eV shows a gain of a factor 1.6 compared to an uncovered photomultiplier.