Researcher working with a detector of the double beta decay experiment, which is in operation at the Gran Sasso Laboratory, Italy, the largest underground centre in the world. The experiment studies the decay of tellurium-130 into xenon-130, together with the emission of two electrons and two antineutrinos. The detector is formed by a crystal of tellurium oxide with a mass of 35g kept at a temperature of 20 millikelvin. The double beta decay has never been observed and the experiment at Gran Sasso will also check whether it may occur without the emission of neutrinos.