379 research outputs found

    A Light Calibration System for the ProtoDUNE-DP Detector

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    A LED-based fiber calibration system for the ProtoDUNE-Dual Phase (DP) photon detection system (PDS) has been designed and validated. ProtoDUNE-DP is a 6x6x6 m3 liquid argon time-projection-chamber currently being installed at the Neutrino Platform at CERN. The PDS is based on 36 8-inch photomultiplier tubes (PMTs) and will allow triggering on cosmic rays. The system serves as prototype for the PDS of the final DUNE DP far detector in which the PDS also has the function to allow the 3D event reconstruction on non-beam physics. For this purpose an equalized PMT response is desirable to allow using the same threshold definition for all PMT groups, simplifying the determination of the trigger efficiency. The light calibration system described in this paper is developed to provide this and to monitor the PMT performance in-situ.Comment: 15 pages, 5 figure

    Performances of multi-gap timing RPCs for relativistic ions in the range Z=1-6

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    We present the performance of Multi-gap timing RPCs under irradiation by fully stripped relativistic ions (gamma*beta=2.7, Z=1-6). A time resolution of 80 ps at high efficiency has been obtained by just using standard `off the shelf' 4-gap timing RPCs from the new HADES ToF wall. The resolution worsened to 100 ps for ~ 1 kHz/cm2 proton flux and for ~ 100 Hz/cm2 Carbon flux. The chambers were operated at a standard field of E=100 kV/cm and showed a high stability during the experiment, supporting the fact that RPCs are a convenient choice when accommodating a very broad range of ionizing particles is needed. The data provides insight in the region of very highly ionizing particles (up to x 36 mips) and can be used to constrain the existing avalanche and Space-Charge models far from the usual `mip valley'. The implications of these results for the general case of detection based on secondary processes (n, gamma) resulting in highly ionizing particles with characteristic energy distributions will be discussed, together with the nature of the time-charge correlation curve.Comment: 31 pages, 19 figures, submitted to JINS

    Mixed Ti-Zr metal-organic-frameworks for the photodegradation of acetaminophen under solar irradiation

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    Mixed Ti-Zr metal-organic-frameworks (MOFs)have been synthesized and tested as photocatalysts under solar-simulated radiation using acetaminophen (ACE)as target pollutant. These materials were obtained upon partial substitution of Ti by Zr atoms in the crystalline structure of NH2-MIL-125(Ti)MOF. The effect of the Ti:Zr molar ratio on their characteristics and catalytic behaviour has been analysed. Materials with high Zr relative amount (60–80%)showed amorphous structure and low solar-photocatalytic activity. In contrast, lower Zr proportions resulted in new MOFs with well-defined crystalline structure and high activity for the solar photocatalytic degradation of ACE, even higher than that of the bare Ti MOF. Results with scavengers allowed concluding that O2[rad]− radicals are the main reactive species, although photogenerated [rad]OH radicals and electrons also contribute to the degradation. The stability of the most active photocatalyst was confirmed upon three successive runsThe authors acknowledge the financial support from Spanish MINECO (project CTQ2016-78576-R). M. Peñas-Garzón thanks Spanish MECD for FPU16/00576 grant. Authors thank the Research Support Services of the University of Extremadura (SAIUEx) for its technical and scientific support. We also thank to Dr. Juan Cabanillas for his help with PL measurement

    Adsorption of emerging pollutants on lignin-based activated carbon: Analysis of adsorption mechanism via characterization, kinetics and equilibrium studies

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    Lignin has been employed as a precursor to synthesize activated carbons with the aim of lignin-biomass revalorization. The properties of these activated carbons were compared, and the best adsorbent was employed to remove two emerging pollutants from water, acetaminophen and acetamiprid. The adsorption mechanisms of pharmaceutical and pesticide compounds were analyzed, modeled and interpreted via statistical physics models. In particular, adsorption kinetics and isotherms of acetaminophen and acetamiprid at temperatures between 20 and 60 ◦C were quantified experimentally. Equilibrium data were fitted to different statistical physics-based isotherm models to establish the corresponding adsorption mechanism. A double layer adsorption model with one type of functional group was the best to correlate and explain the removal of these organic molecules. Steric parameters for the adsorption of these organic compounds were also calculated thus determining that their adsorption was multi-molecular. At tested operating conditions, acetaminophen adsorption was endothermic, while acetamiprid removal was exothermic. Physical adsorption forces were expected to be responsible for the removal of both compounds. This study reports new insights on the adsorption mechanisms of relevant emerging pollutants commonly found in water worldwid

    Electronic Developments for the Hades RPC Wall: Overview and Progress

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    This contribution presents the current status and progress of the electronics developed for the Resistive Plate Chamber detector of HADES. This new detector for the time-of-flight detection system will contain more than 1000 RPC modules, covering a total active area of around 7 m2. The Front-End electronics consist of custom-made boards that exploit the benefit of the use of commercial components to achieve time resolutions below 100 ps. The Readout electronics, also custom-made, is a multipurpose board providing a 128- channel Time to Digital Converter (TDC) based on the HPTDC chip

    New RPC front-end electronics for hades

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    Time-of-flight (TOF) detectors are mainly used for both particle identification and triggering. Resistive Plate Chamber (RPC) detectors are becoming widely used because of their excellent TOF capabilities and reduced cost. The new ESTRELA* RPC wall, which is being installed in the HADES detector at Darmstadt GSI, will contain 1024 RPC modules, covering an active area of around 7 m2. It has excellent TOF and good charge resolutions. Its Front-End electronics is based on a 8-layer Mother-Board providing impedance matched paths for the output signals of each of the eight 4-channel Daughter-Boards to the TDC

    Deep sub-threshold Ξ\Xi^- production in Ar+KCl reactions at 1.76A GeV

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    We report first results on a deep sub-threshold production of the doubly strange hyperon Ξ\Xi^- in a heavy-ion reaction. At a beam energy of 1.76A GeV the reaction Ar+KCl was studied with the High Acceptance Di-Electron Spectrometer (HADES) at SIS18/GSI. A high-statistics and high-purity Λ\Lambda sample was collected, allowing for the investigation of the decay channel ΞΛπ\Xi^- \to \Lambda \pi^-. The deduced Ξ/(Λ+Σ0)\Xi^-/(\Lambda+\Sigma^0) production ratio of (5.6±1.21.7+1.8)103(5.6 \pm 1.2 ^{+1.8}_{-1.7})\cdot 10^{-3} is significantly larger than available model predictions.Comment: 4 pages, including 4 figure
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