353 research outputs found

    Measurement of the π− -Ar total hadronic cross section at the LArIAT experiment

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    We present the first measurement of the negative pion total hadronic cross section on argon in a restricted phase space, which we performed at the Liquid Argon In ATestbeam (LArIAT) experiment. All hadronic reaction channels, as well as hadronic elastic interactions with scattering angle greater than 5° are included. The pions have kinetic energies in the range 100–700 MeVand are produced by a beam of charged particles impinging on a solid target at the Fermilab test beam facility. LArIAT employs a 0.24 ton active mass liquid argon time projection chamber (LArTPC) to measure the pion hadronic interactions. For this measurement, LArIAT has developed the “thin slice method,” a new technique to measure cross sections with LArTPCs. While moderately higher, our measurement of the π−-Ar total hadronic cross section is generally in agreement with the GEANT4 prediction.Fermi Research Alliance, LLC (FRA) DE-AC02-07CH11359National Science Foundation (NSF)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ) 233511/2014-8Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES) 001Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) 16/22738-0Polish National Science Centre 2013/09/N/ST2/02793UK Research & Innovation (UKRI)Science & Technology Facilities Council (STFC)Royal Society of LondonMinistry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Japan Society for the Promotion of Science 2510500

    Development of a novel, windowless, amorphous selenium based photodetector for use in liquid noble detectors

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    Detection of the vacuum ultraviolet (VUV) scintillation light produced by liquid noble elements is a central challenge in order to fully exploit the available timing, topological, and calorimetric information in detectors leveraging these media. In this paper, we characterize a novel, windowless amorphous selenium based photodetector with direct sensitivity to VUV light. We present here the manufacturing and experimental setup used to operate this detector at low transport electric fields (2.7-5.2 V/μ\mum) and across a wide range of temperatures (77K-290K). This work shows that the first proof-of-principle device windowless amorphous selenium is robust under cryogenic conditions, responsive to VUV light at cryogenic temperatures, and preserves argon purity. These findings motivate a continued exploration of amorphous selenium devices for simultaneous detection of scintillation light and ionization charge in noble element detectors

    Curva di apprendimento nella scialoendoscopia diagnostica e interventistica per le patologie salivari ostruttive

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    La scialoendoscopia è un nuovo strumento diagnostico e chirurgico che offre l’opportunità di trattare alcune patologie delle ghiandole salivari con procedure non invasive e con risultati potenzialmente superiori alle precedenti tecniche. Come per tutte le nuove tecniche, per raggiungere rapidamente risultati paragonabili a quelli riportati in letteratura, è indispensabile un corretto programma di formazione che segua una graduale curva di apprendimento. Questo include un appropriato programma diagnostico, una corretta selezione dei pazienti e la conoscenza delle possibili insidie operatorie. Abbiamo eseguito uno studio retrospettivo confrontando le prime 141 procedure (74 parotidee e 67 sottomandibolari) eseguite con questa tecnica nel nostro Dipartimento dal 2009 al 2013 con analoghe esperienze riportate in letteratura. I pazienti sono stati divisi in 3 gruppi: Gruppo A (le prime 49 procedure effettuate), gruppo B (le successive 50), Gruppo C (le ultime 42 procedure effettuate). Fra i tre gruppi non sono state evidenziate differenze statisticamente significative nei tempi medi di durata delle procedure, nella percentuale di ricorrenza della sintomatologia dopo il trattamento, nel numero di pazienti che hanno necessitato di più trattamenti e nell’incidenza di complicanze minori. Non sono state riportate complicanze maggiori. Con l’acquisizione di una maggiore esperienza da parte dei chirurghi si è evidenziato un progressivo calo del numero di interventi eseguiti in anestesia generale rispetto a quelli in anestesia locale (51% vs 18% vs 14%). Solo in tre casi su 130 ghiandole trattate (2.3%) è stato necessario eseguire un’asportazione ghiandolare. Per i calcoli salivari è stato valutato il tipo di tecnica utilizzato per l’estrazione e la percentuale d’insuccesso che era analoga nei tre gruppi (13.6% vs 15% vs 15%). I nostri risultati non differiscono sostanzialmente da quelli riportati in letteratura. Abbiamo risolto la difficoltà iniziale nella cateterizzazione del dotto con esercizi chirurgici su cadavere o su teste di maiale. La mancanza di precisione degli strumenti diagnostici radiologici può essere migliorata autonomizzando il chirurgo nell’esecuzione delle ecografie pre e post-operatorie. Viene infine sottolineata l’opportunità di creare dei centri di scialoendoscopia con un bacino di utenza di circa 1 o 2 milioni di abitanti in modo da concentrare le patologie, far fronte agli elevati costi della strumentazione necessaria e poter guadagnare la necessaria esperienza nelle gestione delle varie tecniche chirurgiche

    Molecular and microbiological insights on the enrichment procedures for the isolation of petroleum degrading bacteria and fungi

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    Autochthonous bioaugmentation, by exploiting the indigenous microorganisms of the contaminated environment to be treated, can represent a successful bioremediation strategy. In this perspective, we have assessed by molecular methods the evolution of bacterial and fungal communities during the selective enrichment on different pollutants of a soil strongly polluted by mixtures of aliphatic and polycyclic hydrocarbons. Three consecutive enrichments were carried out on soil samples from different soil depths (0\u20131, 1\u20132, 2\u20133 m), and analyzed at each step by means of high-throughput sequencing of bacterial and fungal amplicons biomarkers. At the end of the enrichments, bacterial and fungal contaminants degrading strains were isolated and identified in order to (i) compare the composition of enriched communities by culture-dependent and culture-independent molecular methods and to (ii) obtain a collection of hydrocarbon degrading microorganisms potentially exploitable for soil bioremediation. Molecular results highlighted that for both bacteria and fungi the pollutant had a partial shaping effect on the enriched communities, with paraffin creating distinct enriched bacterial community from oil, and polycyclic aromatic hydrocarbons generally overlapping; interestingly neither the soil depth or the enrichment step had significant effects on the composition of the final enriched communities. Molecular analyses well-agreed with culture-dependent analyses in terms of most abundant microbial genera. A total of 95 bacterial and 94 fungal strains were isolated after selective enrichment procedure on different pollutants. On the whole, isolated bacteria where manly ascribed to Pseudomonas genus followed by Sphingobacterium, Bacillus, Stenothrophomonas, Achromobacter, and Serratia. As for fungi, Fusarium was the most abundant genus followed by Trichoderma and Aspergillus. The species comprising more isolates, such as Pseudomonas putida, Achromobacter xylosoxidans and Ochromobactrum anthropi for bacteria, Fusarium oxysporum and Fusarium solani for fungi, were also the dominant OTUs assessed in Illumina

    Calorimetry for low-energy electrons using charge and light in liquid argon

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    Precise calorimetric reconstruction of 5-50 MeV electrons in liquid argon time projection chambers (LArTPCs) will enable the study of astrophysical neutrinos in DUNE and could enhance the physics reach of oscillation analyses. Liquid argon scintillation light has the potential to improve energy reconstruction for low-energy electrons over charge-based measurements alone. Here we demonstrate light-augmented calorimetry for low-energy electrons in a single-phase LArTPC using a sample of Michel electrons from decays of stopping cosmic muons in the LArIAT experiment at Fermilab. Michel electron energy spectra are reconstructed using both a traditional charge-based approach as well as a more holistic approach that incorporates both charge and light. A maximum-likelihood fitter, using LArIAT\u27s well-tuned simulation, is developed for combining these quantities to achieve optimal energy resolution. A sample of isolated electrons is simulated to better determine the energy resolution expected for astrophysical electron-neutrino charged-current interaction final states. In LArIAT, which has very low wire noise and an average light yield of 18 pe/MeV, an energy resolution of σ/E≃9.3%/E 1.3% is achieved. Samples are then generated with varying wire noise levels and light yields to gauge the impact of light-augmented calorimetry in larger LArTPCs. At a charge-readout signal-to-noise of S/N≃30, for example, the energy resolution for electrons below 40 MeV is improved by ≈10%, ≈20%, and ≈40% over charge-only calorimetry for average light yields of 10 pe/MeV, 20 pe/MeV, and 100 pe/MeV, respectively

    Design and construction of the MicroBooNE Cosmic Ray Tagger system

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    The MicroBooNE detector utilizes a liquid argon time projection chamber (LArTPC) with an 85 t active mass to study neutrino interactions along the Booster Neutrino Beam (BNB) at Fermilab. With a deployment location near ground level, the detector records many cosmic muon tracks in each beam-related detector trigger that can be misidentified as signals of interest. To reduce these cosmogenic backgrounds, we have designed and constructed a TPC-external Cosmic Ray Tagger (CRT). This sub-system was developed by the Laboratory for High Energy Physics (LHEP), Albert Einstein center for fundamental physics, University of Bern. The system utilizes plastic scintillation modules to provide precise time and position information for TPC-traversing particles. Successful matching of TPC tracks and CRT data will allow us to reduce cosmogenic background and better characterize the light collection system and LArTPC data using cosmic muons. In this paper we describe the design and installation of the MicroBooNE CRT system and provide an overview of a series of tests done to verify the proper operation of the system and its components during installation, commissioning, and physics data-taking
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