Speaker
Description
Darkside-20k is a global direct dark matter detection experiment situated underground at LNGS (in Italy), designed to reach a total exposure of 200 tonne-years, nearly free from instrumental backgrounds. The core of the detector is a dual-phase Time Projection Chamber (TPC) filled with 50 tonnes of low-radioactivity liquid argon. This is surrounded by inner and outer active veto volumes. Both TPC and vetoes are instrumented with large-area light detectors utilising a custom Silicon Photo-Multiplier (SiPM) technology optimised for high optical photon detection efficiency and low noise at liquid argon temperatures.
SiPMs are arranged in Photo-Detector Units (PDUs), which is a compact design meant to minimise the material (and hence the radioactive budget) used for the active electronics, cables and connectors. Each PDU has 20$\times$20 cm$^2$ of active area, comprising 384 SiPMs. The TPC is equipped with 518 PDUs and the inner veto with another 120, for an unprecedented cryogenic SiPM area of 26 m$^2$.
The talk will focus on the production of the TPC and Veto PDUs, illustrating the assembly chain in Italy and the UK institutes, and in particular describing the completion of the Veto production in the UK. Mechanical, electrical, cleanliness and noise tests have been extensively performed at every stage of the production, in order to meet the stringent requirements for the DarkSide-20k photosensors.