In 1988, a hoard of lead ingots was discovered on a Roman shipwreck by a scuba diver, off the coast of Sardinia in Italy. What makes this lead special is that, because it was cast between 80 – 50 BCE, it is free from radiation as all the radioactive lead (the isotope ²¹⁰Pb) has decayed. Luca Pattavina from Università degli Studi di Milano Bicocca is leading a project to make the most of this unusual property and use this ancient lead for a much more high-tech application: neutrino and dark matter detection.

Crystals made from this radiation-free lead are highly sensitive to low-energy neutrino interactions. The project RES-NOVA aims to use these crystals to detect the very low energy neutrinos produced by astrophysical sources such as supernovae, but also dark matter from the centre of our galaxy. It will be based at Laboratori Nazionali del Gran Sasso of INFN, the largest underground research centre in the world. RES-NOVA will be sensitive to supernova bursts up to Andromeda. Within our Galaxy, it will be possible to discriminate core-collapse supernovae from black hole forming collapses with no ambiguity.

​Although the crystals are expected to be radiation-free, the team need to know whether radioactive isotopes will be created when the crystals are exposed to radiation from the atmosphere during their transportation by ship from China, where they will be manufactured, to the Gran Sasso underground laboratory.

To find out, they brought two of their lead tungstate (PbWO₄) crystals to the ChipIr beamline at ISIS, which replicates accelerated exposure to atmospheric neutrons.

Preliminary results indicate that the cosmogenic activation of PbWO₄ crystals in RES-NOVA will be measurable. However, its contribution remains low enough that it will not significantly impact the experimental sensitivity.

The results of the irradiation carried out at ChipIr will aid in developing a detailed background model for the final RES-NOVA experiment, ensuring a more precise understanding of potential sources of background and their impact on sensitivity.

Image, right: Luca Pattavina loading a crystal sample into a germanium detector to test which radioisotopes are present after irradiation on ChipIr.