Search

The scintillation mechanism in NaI:Tl crystals produces different pulse shapes that are dependent on the incoming particle type. The time distribution of scintillation light from nuclear recoil events decays faster than for electron recoil events and this difference can be categorised using various Pulse Shape Discrimination (PSD) techniques. In this study, we measured nuclear and electron recoils in a NaI:Tl crystal, with electron equivalent energies between 2 and 40 keV. We report on a new PSD approach, based on an event-type likelihood; this outperforms the charge-weighted mean-time, which is the conventional metric for PSD in NaI:Tl. Furthermore, we show that a linear combination of the two methods improves the discrimination power at these energies., Comment: 12 pages, 12 figures, 1 table

The Sodium iodide Active Background Rejection Experiment-South (SABRE-South) is a direct dark matter detector soon to be deployed in the Stawell gold mine, in Victoria, Australia. Monitoring of external environmental and experimental conditions, (temperature, barometric pressure, relative humidity, high voltage, and seismic vibration) is vital to ensure the data quality of the SABRE search for dark matter via direct detection. These parameters are generally non-time-critical in the range of Hz to a few kHz and constitute a slow control system. We present the design of a novel compact, industrial-grade, and self-contained slow control system for SABRE-South. This system, featuring innovative hardware and software architecture based on National instruments compact RIO (NI-cRIO) and LabVIEW can be scaled up at low-cost and is capable of implementing the functionalities available in high-end SCADA systems while maintaining the flexibility to integrate custom software code (i.e. C++, PYTHON) for bespoke interfacing needs., 31 pages, 18 figures

SABRE (Sodium-iodide with Active Background REjection) is a direct dark matter search experiment based on an array of radio-pure NaI(Tl) crystals surrounded by a liquid scintillator veto. Twin SABRE experiments in the Northern and Southern Hemispheres will differentiate a dark matter signal from seasonal and local effects. The experiment is currently in a Proof-of-Principle (PoP) phase, whose goal is to demonstrate that the background rate is low enough to carry out an independent search for a dark matter signal, with sufficient sensitivity to confirm or refute the DAMA result during the following full-scale experimental phase. The impact of background radiation from the detector materials and the experimental site needs to be carefully investigated, including both intrinsic and cosmogenically activated radioactivity. Based on the best knowledge of the most relevant sources of background, we have performed a detailed Monte Carlo study evaluating the expected background in the dark matter search spectral region. The simulation model described in this paper guides the design of the full-scale experiment and will be fundamental for the interpretation of the measured background and hence for the extraction of a possible dark matter signal., Comment: 13 pages, 5 figures

Ultra-pure NaI(Tl) crystals are the key element for a model-independent verification of the long standing DAMA result and a powerful means to search for the annual modulation signature of dark matter interactions. The SABRE collaboration has been developing cutting-edge techniques for the reduction of intrinsic backgrounds over several years. In this paper we report the first characterization of a 3.4 kg crystal, named NaI-33, performed in an underground passive shielding setup at LNGS. NaI-33 has a record low $$^{39}$$ 39 K contamination of 4.3 ± 0.2 ppb as determined by mass spectrometry. We measured a light yield of 11.1 ± 0.2 photoelectrons/keV and an energy resolution of 13.2% (FWHM/E) at 59.5 keV. We evaluated the activities of $$^{226}$$ 226 Ra and $$^{228}$$ 228 Th inside the crystal to be $$5.9\pm 0.6~\upmu $$ 5.9 ± 0.6 μ Bq/kg and $$1.6\pm 0.3~\upmu $$ 1.6 ± 0.3 μ Bq/kg, respectively, which would indicate a contamination from $$^{238}$$ 238 U and $$^{232}$$ 232 Th at part-per-trillion level. We measured an activity of 0.51 ± 0.02 mBq/kg due to $$^{210}$$ 210 Pb out of equilibrium and a $$\alpha $$ α quenching factor of 0.63 ± 0.01 at 5304 keV. We illustrate the analyses techniques developed to reject electronic noise in the lower part of the energy spectrum. A cut-based strategy and a multivariate approach indicated a rate, attributed to the intrinsic radioactivity of the crystal, of $$\sim $$ ∼ 1 count/day/kg/keV in the [5–20] keV region.

The Belle II at SuperKEKB will accumulate e+e- collision data at an unprecedented instantaneous luminosity of 8 X 1035, cm−2 s−1, about 40 times larger than its predecessor (Belle). Such a dramatic increase in luminosity will result in a harsh background environment in Belle II. In this paper, we present the detailed performance studies of the Belle II silicon vertex detector with test beam data and Phase II data.

We present an innovative compact dual-modality detector, which integrates an ultrasound probe with a scintigrafic γ -camera for molecular imaging in medicine, in order to get both morphological and functional information in a single three-dimensional image. The scintigraphic detector consists of a 2 × 2 array of a multi-anode PMT Hamamatsu H8500-Mod8 and a 4.0 mm thick continuous LaBr 3 (Ce) crystal equipped with four segment slant-hole collimators for single photon imaging (SPET). The collimator permits to recover the depth of a lesion by rotating around its vertical axis (z) without the need of rotating the camera around the investigated object. This detector can take advantage from being positioned close to the object and overcome the intrinsic limitations in spatial resolution arising from the geometry of SPET/CT gantry. The aim of this work is to describe preliminary phantom analysis and to provide a 3D US/SPET image.

The aim of this work is to present a 64-independent channels, low noise and wide dynamic range readout system for multi-anodes photo-multiplier tubes (MA-PMTs). The results consist of some imaging tests obtained with a Hamamatsu H8500 MA-PMT coupled to different scintillation crystals, like a LaBr3(Ce) continuous crystal and NaI(Tl), CsI(Tl) and YAP pixilated scintillation arrays. Moreover, the Hamamatsu H8500C-Mod8 new series equipped with a super bialkali (SBA) photocatode was also studied. Energy and spatial resolutions showed an improvement with respect to the previous generation of multi-channel read-out electronics and we also reported some very interesting results with LaBr3(Ce) crystal coupled to the new Hamamatsu H8500-Mod8 with high quantum efficiency. That demonstrated the excellent response characteristics and versatility of our proposed electronic system and its potential use with all γ-ray detectors.

The Muon Spectrometer of the ATLAS experiment is based on regular arrays of 3 cm diameter high pressure drift tubes (MDT) in a toroidal magnetic field with an associated bending power of about 3 and 5 Tm (barrel and endcap). The gas composition (93%Ar -7%CO 2 ) and gain (2×104), chosen in order to limit aging effects, make the drift response function slow and highly non linear. A test beam setup, with a small MDT chamber and a high resolution silicon strip telescope, was organised at the Cern H8 high energy muon beam with the goal of measuring the drift properties of both the standard ATLAS gas mixture and of alternative, faster gas mixtures, typically based on CF 4 , in view of a possible use at SLHC or elsewhere. We describe the analysis of the test beam data and show the first, preliminary, results and their comparison with the expectations of the simulation.