The electronics, trigger and data acquisition system for the liquid argon time projection chamber of the DarkSide-50 search for dark matter

FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPThe DarkSide-50 experiment at the Laboratori Nazionali del Gran Sasso is a search for dark matter using a dual phase time projection chamber with 50 kg of low radioactivity argon as target. Light signals from interactions in the argon are detected by a system of 38 photo-multiplier tubes (PMTs), 19 above and 19 below the TPC volume inside the argon cryostat. We describe the electronics which processes the signals from the photo-multipliers, the trigger system which identifies events of interest, and the data-acquisition system which records the data for further analysis. The electronics include resistive voltage dividers on the PMTs, custom pre-amplifiers mounted directly on the PMT voltage dividers in the liquid argon, and custom amplifier/discriminators (at room temperature). After amplification, the PMT signals are digitized in CAEN waveform digitizers, and CAEN logic modules are used to construct the trigger; the data acquisition system for the TPC is based on the Fermilab artdaq software. The system has been in operation since early 2014.12126FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP2016/09084-0The DarkSide-50 Collaboration thanks the LNGS laboratory and its staff for their invaluable technical and logistical support. We particularly wish to thank our Fermilab colleagues Dr. Jin-Yuan Wu for his contributions to the FPGA firmware, Dr. Don Holmgren for his advice on the selection and procurement of the computing and networking hardware, Engineer Sten Hansen for his work on designing the PMT divider and his help with the V1495 firmware, and Engineer Ron Rechenmacher for resolving issues with Infiniband and our raid disk arrays. DarkSide-50 has been supported by the Italian Istituto Nazionale di Fisica Nucleare, the U.S. National Science Foundation under grant Nos. 1004051, 1242571, 1314268, 1314479, 1314483, 1314501, 1314507 & 1314752, the US Department of Energy under contracts DE-AC02-07CH11359 and DE-FG02-91ER40671, the Polish NCN (Grant UMO-2014/15/B/ST2/02561), and the Russian Science Foundation Grant No. 16-12-10369. We also acknowledge financial support from the UnivEarthS Labex program of Sorbonne Paris Cité (ANR-10-LABX-0023 and ANR-11-IDEX-0005-02) and from the São Paulo Research Foundation (FAPESP) grant No. 2016/09084-0. Development of the in-liquid pre-amplifier was supported by the INFN CSN-V(5) QUPID-R&D grant