Large-scale neutrino telescopes use water or ice as a target medium. The detection of particles is therefore restricted to those which produce Cherenkov light, bremsstrahlung, or visible secondaries. This excludes the detection of slowly moving, massive particles proposed in theories which go beyond the standard model of particles, including magnetic monopoles.

Simulations show that these particles would be detectable with neutrino telescopes using a little known property of water: highly ionizing particles inducing the production of luminescence after passing through the water and exciting electronic states of the molecules or the lattice.

The few previous measurements of water luminescence show inconsistent results. In addition, there are no measurements with conditions comparable to those present in current large-scale neutrino telescopes. Measurements have therefore been designed that target these particular conditions and enable detailed investigations of the leading uncertainties.

Measurement results are presented and discussed in this contribution where the luminescence of water and ice is induced by $\alpha$-particles. Measurements of warm ice $>-45\,^\circ\textrm{C}$ are included which has never been considered before.