More Like this

1. SiPM-matrix readout of two-phase argon detectors using electroluminescence in the visible and near infrared range

   https://doi.org/-https://doi.org/10.1140/epjc/s10052-020-08801-2  

   Aalseth, C. E. ; et, al ( February 2021 , European physical journal)

   Abstract: Proportional electroluminescence (EL) in noble gases is used in two-phase detectors for dark matter searches to record (in the gas phase) the ionization signal induced by particle scattering in the liquid phase. The “standard” EL mechanism is considered to be due to noble gas excimer emission in the vacuum ultraviolet (VUV). In addition, there are two alternative mechanisms, producing light in the vis- ible and near infrared (NIR) ranges. The first is due to bremsstrahlung of electrons scattered on neutral atoms (“neu- tral bremsstrahlung”, NBrS). The second, responsible for electron avalanche scintillation in the NIR at higher electric fields,more »is due to transitions between excited atomic states. In this work, we have for the first time demonstrated two alternative techniques of the optical readout of two-phase argon detectors, in the visible and NIR range, using a sili- con photomultiplier matrix and electroluminescence due to either neutral bremsstrahlung or avalanche scintillation. The amplitude yield and position resolution were measured for these readout techniques, which allowed to assess the detec- tion threshold for electron and nuclear recoils in two-phase argon detectors for dark matter searches. To the best of our knowledge, this is the first practical application of the NBrS effect in detection science.« less
2. Performance of the ReD TPC, a novel double-phase LAr detector with silicon photomultiplier readout

   https://doi.org/10.1140/epjc/s10052-021-09801-6  

   Agnes, P. ; Albergo, S. ; Albuquerque, I. ; Arba, M. ; Ave, M. ; Boiano, A. ; Bonivento, W. M. ; Bottino, B. ; Bussino, S. ; Cadeddu, M. ; et al ( November 2021 , The European Physical Journal C)

   Abstract A double-phase argon Time Projection Chamber (TPC), with an active mass of 185 g, has been designed and constructed for the Recoil Directionality (ReD) experiment. The aim of the ReD project is to investigate the directional sensitivity of argon-based TPCs via columnar recombination to nuclear recoils in the energy range of interest (20– $$200\,\hbox {keV}_{nr}$$ 200 keV nr ) for direct dark matter searches. The key novel feature of the ReD TPC is a readout system based on cryogenic Silicon Photomultipliers (SiPMs), which are employed and operated continuously for the first time in an argon TPC. Over the course ofmore »6 months, the ReD TPC was commissioned and characterised under various operating conditions using $$\gamma $$ γ -ray and neutron sources, demonstrating remarkable stability of the optical sensors and reproducibility of the results. The scintillation gain and ionisation amplification of the TPC were measured to be $$g_1 = (0.194 \pm 0.013)$$ g 1 = ( 0.194 ± 0.013 ) photoelectrons/photon and $$g_2 = (20.0 \pm 0.9)$$ g 2 = ( 20.0 ± 0.9 ) photoelectrons/electron, respectively. The ratio of the ionisation to scintillation signals (S2/S1), instrumental for the positive identification of a candidate directional signal induced by WIMPs, has been investigated for both nuclear and electron recoils. At a drift field of 183 V/cm, an S2/S1 dispersion of 12% was measured for nuclear recoils of approximately 60– $$90\,\hbox {keV}_{nr}$$ 90 keV nr , as compared to 18% for electron recoils depositing 60 keV of energy. The detector performance reported here meets the requirements needed to achieve the principal scientific goals of the ReD experiment in the search for a directional effect due to columnar recombination. A phenomenological parameterisation of the recombination probability in LAr is presented and employed for modeling the dependence of scintillation quenching and charge yield on the drift field for electron recoils between 50–500 keV and fields up to 1000 V/cm.« less
3. Separating $${^{39}\hbox {Ar}}$$ from $${^{40}\hbox {Ar}}$$ by cryogenic distillation with Aria for dark-matter searches

   https://doi.org/10.1140/epjc/s10052-021-09121-9  

   Agnes, P. ; Albergo, S. ; Albuquerque, I. F. M. ; Alexander, T. ; Alici, A. ; Alton, A. K. ; Amaudruz, P. ; Arba, M. ; Arpaia, P. ; Arcelli, S. ; et al ( April 2021 , The European Physical Journal C)

   Aria is a plant hosting a$${350}\,\hbox {m}$$$350\text{m}$cryogenic isotopic distillation column, the tallest ever built, which is being installed in a mine shaft at Carbosulcis S.p.A., Nuraxi-Figus (SU), Italy. Aria is one of the pillars of the argon dark-matter search experimental program, lead by the Global Argon Dark Matter Collaboration. It was designed to reduce the isotopic abundance of$${^{39}\hbox {Ar}}$$${}^{39}\text{Ar}$in argon extracted from underground sources, called Underground Argon (UAr), which is used for dark-matter searches. Indeed,$${^{39}\hbox {Ar}}$$${}^{39}\text{Ar}$is a$$\beta $$$\beta$-emitter of cosmogenic origin, whose activity poses background and pile-up concerns in the detectors. In this paper, we discuss the requirements, design,more »construction, tests, and projected performance of the plant for the isotopic cryogenic distillation of argon. We also present the successful results of the isotopic cryogenic distillation of nitrogen with a prototype plant.

   « less
4. A study of events with photoelectric emission in the DarkSide-50 liquid argon Time Projection Chamber

   The DarkSide-50 Collaboration) Agnes, P. ; Albuquerque, I. F. ; Alexander, T. ; Alton, A. K. ; Ave, M. ; Back, H. O. ; Batignani, G. ; Biery, K. ; Bocci, V. ; Bonivento, W. M. ; et al ( July 2021 , ArXivorg)

   Finding unambiguous evidence of dark matter interactions in a particle detector is a main objective of physics research. The liquid argon time projection chamber technique for the detection of Weakly Interacting Massive Particles (WIMP) allows sensitivities down to the so-called neutrino floor for high and low WIMP masses. Based on the successful operation of the DarkSide-50 detector, a new and more sensitive experiment, DarkSide-20k, was designed and is now under construction. A thorough understanding of the DarkSide-50 detector response to events classified as dark matter as well as all other interactions is essential for an optimal design of the newmore »experiment. In this paper, we report on a particular set of events, for which scintillation-ionization signals are observed in association with signals from single or few isolated electrons. We identified and provided an interpretation for two event types in which electrons are produced via photoelectric effect on the cathode electrode and in the bulk liquid. Events with photoelectric emissions are observed in association with most interactions with large energy depositions in the detector. From the measured rate of these events, we determine the photo-ionization probability, or photoelectric quantum efficiency, of tetraphenyl butadiene (TPB) at wavelengths around 128 nm.« less
5. A self-consistent hybrid model of kinetic striations in low-current Argon discharges

   https://doi.org/10.1088/1361-6595/ac4b68  

   Kolobov, Vladimir ; Guzmán, Juan Alonso ; Arslanbekov, R R ( January 2022 , Plasma Sources Science and Technology)

   Abstract A self-consistent hybrid model of standing and moving striations was developed for low-current DC discharges in noble gases. We introduced the concept of surface diffusion in phase space (r,u) (where u denotes the electron kinetic energy) described by a tensor diffusion in the nonlocal Fokker-Planck kinetic equation for electrons in the collisional plasma. Electrons diffuse along surfaces of constant total energy ε=u-eφ(r) between energy jumps in inelastic collisions with atoms. Numerical solutions of the 1d1u kinetic equation for electrons were obtained by two methods and coupled to ion transport and Poisson solver. We studied the dynamics of striation formationmore »in Townsend and glow discharges in Argon gas at low discharge currents using a two-level excitation-ionization model and a “full-chemistry” model, which includes stepwise and Penning ionization. Standing striations appeared in Townsend and glow discharges at low currents, and moving striations were obtained for the discharge currents exceeding a critical value. These waves originate at the anode and propagate towards the cathode. We have seen two types of moving striations with the 2-level and full-chemistry models, which resemble the s and p striations previously observed in the experiments. Simulations indicate that processes in the anode region could control moving striations in the positive column plasma. The developed model helps clarify the nature of standing and moving striations in DC discharges of noble gases at low discharge currents and low gas pressures.« less