UV-enhancement of photomultiplier response: a study of wavelength shifters for the AMANDA/IceCube detector

Wavelength shifters have been tested to investigate the enhancement of the sensitivity of AMANDA/IceCube optical modules to Cherenkov light. An improvement in signal detection can be achieved by adding a layer of material in front of the detector that is capable of absorbing light in the wavelength interval 200–350 nm, and re-emits it within the region of maximum response of the photomultiplier, i.e., ∼400 nm. Two chemical compounds were found to be very suitable: an increase in light detection efficiency by more than 40% was measured, while the time resolution of the detector is only worsened by less than 3 ns.