First results from the DarkSide-50 dark matter experiment at Laboratori Nazionali del Gran Sasso

Abstract

We report the first results of DarkSide-50, a direct search for dark matter operating in the underground Laboratori Nazionali del Gran Sasso (LNGS) and searching for the rare nuclear recoils possibly induced by weakly interacting massive particles (WIMPs). The dark matter detector is a Liquid Argon Time Projection Chamber with a (46.4±0.7) kg active mass, operated inside a 30 t organic liquid scintillator neutron veto, which is in turn installed at the center of a 1 kt water Cherenkov veto for the residual flux of cosmic rays. We report here the null results of a dark matter search for a View the MathML source exposure with an atmospheric argon fill. This is the most sensitive dark matter search performed with an argon target, corresponding to a 90% CL upper limit on the WIMP-nucleon spin-independent cross section of 6.1×10−44 cm2 for a WIMP mass of 100 Gev/c2

Performance and Application of VUV-sensitive MPPCs for Liquid Argon Scintillation Light

“…Therefore the smaller covariance of Slow/Total distribution certainly gives a stronger pulse shape discrimination (PSD) power. It should be noted that typical PSD covariance obtained by normal PMT+TPB method [8] is wider than that of the MPPC observed here, although direct comparisons would not be appropriate since detector condition and energy scale in addition to incident particles are all different. However, it is at least concluded that VUV MPPC should be very useful device for understanding argon scintillation process because of its direct detection capability and small covariance and also may potentially have a stronger PSD, applicable for dark matter search.…”

Darkside Status and Prospects

“…DarkSide-50k is a direct-detection dark matter search experiment, based on a Liquid Argon Time Projection Chamber (LAr-TPC) [1,2]. It is located at the Laboratorio Nazionale del Gran Sasso (LNGS) in Italy.…”

“…Electron-recoil background events (typically β /γ radiation) have S1 shape very different from that of NR (see Figure 1). The pulse shape discrimination (PSD) parameter f 90 -defined as the fraction of S1 signal detected in the first 90ns from the trigger -has been shown to discriminate between NR events and ER events at the level of 2 · 10 −7 [1]. …”

“…PSD and other background-rejection techniques were perfected using Atmospheric Argon (AAr), which contains ∼ 1 Bq/kg of the cosmic-ray-produced 39 Ar isotope [1]. The argon currently used in the active volume is low-radioactivity Underground Argon (UAr).…”

Consistency test of PMT SPE spectrum from dark-noise pulses and LED low-intensity light

“…PMT has been an essential instrument for experimental particle physics, especially for the low background experiments such as DarkSide [1] and XENON [2], which are all expecting the least material near the target volume. The accuracy of SPE calibration of PMT is essential to energy reconstruction, which will directly affect the results of the experiment.…”