The direct search for Dark Matter has produced so far mainly negative results. One positive claim by the DAMA Collaboration however stands unverified since 15 years. This is a strong model-independent claim, which requires a direct verification by a new project exploiting the same technology but with a superior sensitivity. The SABRE experiment, is now undertaking the task, with a new project based on NaI(Tl) scintillating crystals, and surrounded by a liquid scintillator veto. However, by extending the physics reach of the technology, it is possible to lower significantly the detection energy threshold. In this way, one can provide a definite proof or rejection of the DAMA result, and at the same time extend the observation window in an energy range where the signal would be strongly enhanced. This can be achieved by operating the crystals in a cold environment, and choosing appropriate light detectors, which would help in reducing noise and threshold, and the appropriate cooling technique. In this project I propose to exploit Liquid Argon, that can be used both as cooling medium for the crystals and as detecting medium able to veto some of the dominant background contributions. The main goal of this project is to successfully cool down the crystals themselves, and then systematically measure their response to and neutron sources, in terms of Light Yield and Nuclear Recoil Quenching. It is expected that these properties may vary at cold, with respect to room temperature, however existing measurements are scarce and not consistent among one another. This project therefore proposes to develop the technology to uniformly and safely cool down the crystals in liquid or cold gas argon, then to study their response as a function of temperature, on a dedicated neutron beam facility.
Andrea Zani – INFN MILANO
Dr. Andrea Zani (PhD in Physics in 2014) is a researcher at INFN Milan. He has a deep experience on low-background detectors for rare events interactions (neutrino and dark matter physics). He participated in construction and operation of several detectors based on Liquid Argon Time Projection Chamber technology, and was deputy technical coordinator for the ICARUS detector overhaul and for the ProtoDUNE beam run at the CERN SPS Very Low Energy beam. He exported his experience in cryogenics to scintillating NaI(Tl) crystals, to improve their physics reach by operating them at liquid argon temperature with suitable photodetectors (Silicon Photomultipliers)