Ponente
Descripción
Darkside-20k is a global direct dark matter search experiment situated underground at LNGS (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. The entire TPC wall is surrounded by polymethylmethacrylate (PMMA), which acts as a neutron veto, immersed in a second low-radioactivity liquid argon bath enclosed in a stainless-steel vessel. The TPC and the neutron veto are enclosed within the cryostat volume, which is filled with 650 tonnes of atmospheric argon comprising the outer veto volume.
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 a compact design meant to minimise the material (and hence the radioactive budget) used for the active electronics, cables and connectors: the PhotoDetection Units (PDUs). A PDU comprises 16 "Tiles", each containing 24 SIPMs, together with front-end electronics, and a motherboard (which distributes voltage and control signals, sums Tiles channels, and drives the electrical signal transmission), providing a single readout area of 10x10 cm$^2$. The TPC will be equipped with 518 PDUs and the neutron veto with another 120, for an unprecedented total active SiPM area of 26 m$^2$.
The talk will focus on the production of the TPC and veto PDUs, describing the assembly chain in Italy and in the UK institutes, to underline the rigorous QA/QC procedures, up to the final characterisation between Italy, UK and Poland.
Tests have been extensively performed at any stage of the production (mechanical tests, electrical functional tests, I-V curves, noise measurements, dust counting), and in particular in liquid nitrogen baths (pulsed laser response to check the photodetection efficiency), either for the single Tiles and for the fully assembled PDUs, with the purpose to assign a "quality passport" to each component, in order to meet the stringent requirements for the DarkSide-20k photosensors.
References
- DarkSide-20k Collaboration, “Quality assurance and quality control of
the 26 m$^2$ SiPM production for the DarkSide-20k dark matter
experiment”, Eur.Phys.J.C 85 (2025) 5, 534 - DarkSide-20k
Collaboration, “Production, Quality Assurance and Quality Control of
the SiPM Tiles for the DarkSide-20k Time Projection Chamber",
submitted - DarkSide-20k Collaboration, “Construction and
characterisation of the DarkSide-20k2 veto silicon photo-multiplier
detectors”, in review
