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Sample records for argon imaging tpc

  1. First Demonstration of Imaging Cosmic Muons in a Two-Phase Liquid Argon TPC using an EMCCD Camera and a THGEM

    CERN Document Server

    Mavrokoridis, K; McCormick, K J; Paudyal, P; Roberts, A; Smith, N A; Touramanis, C

    2015-01-01

    Colossal two-phase Liquid Argon Time Projection Chambers (LAr TPCs) are a proposed option for future long-baseline neutrino experiments. This study illustrates the feasibility of using an EMCCD camera to capture light induced by single cosmic events in a two-phase LAr TPC employing a THGEM. An Andor iXon Ultra 897 EMCCD camera was externally mounted via a borosilicate glass viewport on the Liverpool two-phase LAr TPC. The camera successfully captured the secondary scintillation light produced at the THGEM holes that had been induced by cosmic events. The light collection capability of the camera for various EMCCD gains was assessed. For a THGEM gain of 64 and an EMCCD gain of 1000, clear images were captured with an average signal-to-noise ratio of 6. Preliminary 3D reconstruction of straight cosmic muon tracks has been performed by combining the camera images, PMT signals and THGEM charge data. Reconstructed cosmic muon tracks were used to determine THGEM gain and to calibrate the intensity levels of the EMC...

  2. The liquid argon TPC for the ICARUS experiment

    CERN Document Server

    Arneodo, F

    1997-01-01

    The ICARUS project aims at the realisation of a large liquid argon TPC to be run at the Underground Laboratories of Gran Sasso in Italy. An intense R&D; activity has put on firm grounds this new detector technology and experimentally confirmed its feasibility on a few ton scale. Based on these solid achievements, the collaboration is now confident of being able to build and safely operate a multi-kton detector. The reseach program of the experiment involves the systematic study of a wide spectrum of physical phenomena covering many orders of magnitude in the energy deposited in the detector: from the few MeV of solar neutrino interactions, to the about one GeV of the proton decay and atmospheric neutrinos, up to the higher energies of neutrinos from accelerators.

  3. First measurements with ARGONTUBE, a 5 m long drift Liquid Argon TPC

    International Nuclear Information System (INIS)

    The Liquid Argon Time Projection Chamber (LAr TPC) technique is a promising technology for future neutrino detectors. At LHEP of the University of Bern (Switzerland), an R and D program towards large detectors are on-going. The main goal is to show the feasibility of long drift paths over many meters. Therefore, a liquid Argon TPC with 5 m of drift distance was constructed. Many other aspects of the liquid Argon TPC technology are also investigated, such as a new device to generate high voltage in liquid Argon (Greinacher circuit), a recirculation filtering system and the multi-photon ionization of liquid Argon with a UV laser. Two detectors are built: a medium size prototype for specific detector technology studies, and ARGONTUBE, a 5 m long device

  4. Optical Readout of a Two Phase Liquid Argon TPC using CCD Camera and TGEMs

    CERN Document Server

    Mavrokoridis, K; Carroll, J; Lazos, M; McCormick, K J; Smith, N A; Touramanis, C; Walker, J

    2014-01-01

    This paper presents a preliminary study into the use of CCDs to image secondary scintillation light generated by Thick Gas Electron Multipliers (TGEMs) in a two phase LAr TPC. A Sony ICX285AL CCD chip was mounted above a double TGEM in the gas phase of a 40 litre two-phase LAr TPC with the majority of the camera electronics positioned externally via a feedthrough. An Am-241 source was mounted on a rotatable motion feedthrough allowing the positioning of the alpha source either inside or outside of the field cage. Developed for and incorporated into the TPC design was a novel high voltage feedthrough featuring LAr insulation. Furthermore, a range of webcams were tested for operation in cryogenics as an internal detector monitoring tool. Of the range of webcams tested the Microsoft HD-3000 (model no:1456) webcam was found to be superior in terms of noise and lowest operating temperature. In ambient temperature and atmospheric pressure 1 ppm pure argon gas, the TGEM gain was approximately 1000 and using a 1 msec...

  5. Study of electron recombination in liquid argon with the ICARUS TPC

    International Nuclear Information System (INIS)

    Electron recombination in liquid argon (LAr) is studied by means of charged particle tracks collected in various ICARUS liquid argon TPC prototypes. The dependence of the recombination on the particle stopping power has been fitted with a Birks functional dependence. The simulation of the process of electron recombination in Monte Carlo calculations is discussed. A quantitative comparison with previously published data is carried out

  6. TPB-coated Light Guides for Liquid Argon TPC Light Detection Systems

    CERN Document Server

    Ignarra, C M

    2013-01-01

    Light detection systems in Liquid Argon Time Projection Chambers (LArTPCs) require the detection of the 128 nm light produced during argon scintillation. Most detectors use Tetraphenyl Butadiene (TPB) to shift the wavelength of the light into a range visible to Photomultiplier Tubes (PMTs). These proceedings summarize characterizations of light-guides coated with a matrix of TPB in UV transmitting acrylic which are more compact than existing LArTPC light collection systems.

  7. TPB-coated light guides for liquid argon TPC light detection systems

    Science.gov (United States)

    Ignarra, C. M.

    2013-10-01

    Light detection systems in Liquid Argon Time Projection Chambers (LArTPCs) require the detection of the 128 nm light produced during argon scintillation. Most detectors use Tetraphenyl Butadiene (TPB) to shift the wavelength of the light into a range visible to Photomultiplier Tubes (PMTs). These proceedings summarize characterizations of light-guides coated with a matrix of TPB in UV transmitting acrylic which are more compact than existing LArTPC light collection systems.

  8. Improved TPB-coated light guides for liquid argon TPC light detection systems

    International Nuclear Information System (INIS)

    Scintillation light produced in liquid argon (LAr) must be shifted from 128 nm to visible wavelengths in light detection systems used for liquid argon time-projection chambers (LArTPCs). To date, LArTPC light collection systems have employed tetraphenyl butadiene (TPB) coatings on photomultiplier tubes (PMTs) or plates placed in front of the PMTs. Recently, a new approach using TPB-coated light guides was proposed. In this paper, we report on light guides with improved attenuation lengths above 100 cm when measured in air. This is an important step in the development of meter-scale light guides for future LArTPCs. Improvements come from using a new acrylic-based coating, diamond-polished cast UV transmitting acrylic bars, and a hand-dipping technique to coat the bars. We discuss a model for connecting bar response in air to response in liquid argon and compare this to data taken in liquid argon. The good agreement between the prediction of the model and the measured response in liquid argon demonstrates that characterization in air is sufficient for quality control of bar production. This model can be used in simulations of light guides for future experiments

  9. Improved TPB-coated light guides for liquid argon TPC light detection systems

    Science.gov (United States)

    Moss, Z.; Bugel, L.; Collin, G.; Conrad, J. M.; Jones, B. J. P.; Moon, J.; Toups, M.; Wongjirad, T.

    2015-08-01

    Scintillation light produced in liquid argon (LAr) must be shifted from 128 nm to visible wavelengths in light detection systems used for liquid argon time-projection chambers (LArTPCs). To date, LArTPC light collection systems have employed tetraphenyl butadiene (TPB) coatings on photomultiplier tubes (PMTs) or plates placed in front of the PMTs. Recently, a new approach using TPB-coated light guides was proposed. In this paper, we report on light guides with improved attenuation lengths above 100 cm when measured in air. This is an important step in the development of meter-scale light guides for future LArTPCs. Improvements come from using a new acrylic-based coating, diamond-polished cast UV transmitting acrylic bars, and a hand-dipping technique to coat the bars. We discuss a model for connecting bar response in air to response in liquid argon and compare this to data taken in liquid argon. The good agreement between the prediction of the model and the measured response in liquid argon demonstrates that characterization in air is sufficient for quality control of bar production. This model can be used in simulations of light guides for future experiments.

  10. Improved TPB-coated Light Guides for Liquid Argon TPC Light Detection Systems

    CERN Document Server

    Moss, Z; Collin, G; Conrad, J M; Jones, B J P; Moon, J; Toups, M; Wongjirad, T

    2014-01-01

    Scintillation light produced in liquid argon (LAr) must be shifted from 128 nm to visible wavelengths in light detection systems used for liquid argon time-projection chambers (LArTPCs). To date, LArTPC light collection systems have employed tetra phenyl butadiene (TPB) coatings on photomultiplier tubes (PMTs) or plates placed in front of the PMTs. Recently, a new approach using TPB-coated light guides was proposed. In this paper, we report on light guides with improved attenuation lengths above 100 cm when measured in air. This is an important step in the development of meter-scale light guides for future LArTPCs. Improvements come from using a new acrylic-based coating, diamond-polished cast UV transmitting acrylic bars, and a hand-dipping technique to coat the bars.

  11. Image Segmentation in Liquid Argon Time Projection Chamber Detector

    CERN Document Server

    Płoński, Piotr; Sulej, Robert; Zaremba, Krzysztof

    2015-01-01

    The Liquid Argon Time Projection Chamber (LAr-TPC) detectors provide excellent imaging and particle identification ability for studying neutrinos. An efficient and automatic reconstruction procedures are required to exploit potential of this imaging technology. Herein, a novel method for segmentation of images from LAr-TPC detectors is presented. The proposed approach computes a feature descriptor for each pixel in the image, which characterizes amplitude distribution in pixel and its neighbourhood. The supervised classifier is employed to distinguish between pixels representing particle's track and noise. The classifier is trained and evaluated on the hand-labeled dataset. The proposed approach can be a preprocessing step for reconstructing algorithms working directly on detector images.

  12. ArgonCube: a novel, fully-modular approach for the realization of large-mass liquid argon TPC neutrino detectors

    CERN Document Server

    Amsler, C; Asaadi, J; Auger, M; Barbato, F; Bay, F; Bishai, M; Bleiner, D; Borgschulte, A; Bremer, J; Cavus, E; Chen, H; De Geronimo, G; Ereditato, A; Fleming, B; Goldi, D; Hanni, R; Kose, U; Kreslo, I; La Mattina, F; Lanni, F; Lissauer, D; Luthi, M; Lutz, P; Marchionni, A; Mladenov, D; Nessi, M; Noto, F; Palamara, O; Raaf, J L; Radeka, V; Rudolph Von Rohr, Ch; Smargianaki, D; Soderberg, M; Strauss, Th; Weber, M; Yu, B; Zeller, G P; Zeyrek, M; CERN. Geneva. SPS and PS Experiments Committee; SPSC

    2015-01-01

    The Liquid Argon Time Projection Chamber is a prime candidate detector for future neutrino oscillation physics experiments, underground neutrino observatories and proton decay searches. A large international project based on this technology is currently being considered at the future LBNF facility in the United States on the very large mass scale of 40 kton. In this document, following the long standing R&D work conducted over the last years in several laboratories in Europe and in the United States, we intend to propose a novel Liquid Argon TPC approach based on a fully-modular, innovative design, the ArgonCube. The related R&D work will proceed along two main directions; one aimed at on the assessment of the proposed modular detector design, the other on the exploitation of new signal readout methods. Such a strategy will provide high performance while being cost-effective and robust at the same time. According to our plans, we will firstly realize a detector prototype hosted in a cryostat that is a...

  13. Benchmarking TPB-coated Light Guides for Liquid Argon TPC Light Detection Systems

    OpenAIRE

    Baptista, B.; Bugel, L.; Chiu, C; Conrad, J. M.; Ignarra, C. M.; Jones, B. J. P.; Katori, T.; Mufson, S.

    2012-01-01

    Scintillation light from liquid argon is produced at 128 nm and thus must be shifted to visible wavelengths in light detection systems used for Liquid Argon Time Projection Chambers (LArTPCs). To date, designs have employed tetraphenyl butadiene (TPB) coatings on photomultiplier tubes (PMTs) or plates placed in front of the PMTs. Recently, a new approach using TPB-coated light guides was proposed. In this paper, we show that the response of lightguides coated with TPB in a UV Transmitting (UV...

  14. Benchmarking TPB-coated Light Guides for Liquid Argon TPC Light Detection Systems

    CERN Document Server

    Baptista, B; Chiu, C; Conrad, J M; Ignarra, C M; Jones, B J P; Katori, T; Mufson, S

    2012-01-01

    Scintillation light from liquid argon is produced at 128 nm and thus must be shifted to visible wavelengths in light detection systems used for Liquid Argon Time Projection Chambers (LArTPCs). To date, designs have employed tetraphenyl butadiene (TPB) coatings on photomultiplier tubes (PMTs) or plates placed in front of the PMTs. Recently, a new approach using TPB-coated light guides was proposed. In this paper, we show that the response of lightguides coated with TPB in a UV Transmitting (UVT) acrylic matrix is very similar to that of a coating using a polystyrene (PS) matrix. We obtain a factor of three higher light yield than has been previously reported from lightguides. This paper provides information on the response of the lightguides so that these can be modeled in simulations for future LArTPCs. This paper also identifies areas of R&D for potential improvements in the lightguide response

  15. WA105: a large-scale demonstrator of the Liquid Argon double phase TPC

    Science.gov (United States)

    Tonazzo, A.; WA105 Collaboration

    2016-05-01

    The physics case for a large underground detector devoted to neutrino oscillation measurements, nucleon decay and astrophysics is compelling. A time projection chamber based on the dual-phase liquid Argon technique is an extremely attractive option, allowing for long drift distances, low energy threshold and high readout granularity. It has been extensively studied in the LAGUNA-LBNO Design Study and is one of the two designs foreseen for the modules of the DUNE detector in the US. The WA105 experiment envisages the construction of a large scale prototype at CERN, to validate technical solutions and perform physics studies with charged particle beams.

  16. Muon-induced background to proton decay in the p→K+ν decay channel with large underground liquid argon TPC detectors

    Directory of Open Access Journals (Sweden)

    J. Klinger

    2015-06-01

    Full Text Available Large liquid argon TPC detector programs such as LBNE and LAGUNA-LBNO will be able to make measurements of the proton lifetime which will outperform Cherenkov detectors in the proton decay channel p→K+ν. At the large depths which are proposed for such experiments, a non-negligible source of isolated charged kaons may be produced in the showers of cosmogenic muons. We present an estimate of the cosmogenic muon background to proton decay in the p→K+ν channel. The simulation of muon transport to a depth of 4 km w.e. is performed in the MUSIC framework and the subsequent propagation of muons and secondary particles in the vicinity of a cylindrical 20 kt LAr target is performed using Geant4. An exposure time of 100 years is considered, with a rate of <0.0012 events/kt/year at 90% CL predicted from our simulations.

  17. Muon-induced background to proton decay in the p →K+ ν decay channel with large underground liquid argon TPC detectors

    Science.gov (United States)

    Klinger, J.; Kudryavtsev, V. A.; Richardson, M.; Spooner, N. J. C.

    2015-06-01

    Large liquid argon TPC detector programs such as LBNE and LAGUNA-LBNO will be able to make measurements of the proton lifetime which will outperform Cherenkov detectors in the proton decay channel p →K+ ν. At the large depths which are proposed for such experiments, a non-negligible source of isolated charged kaons may be produced in the showers of cosmogenic muons. We present an estimate of the cosmogenic muon background to proton decay in the p →K+ ν channel. The simulation of muon transport to a depth of 4 km w.e. is performed in the MUSIC framework and the subsequent propagation of muons and secondary particles in the vicinity of a cylindrical 20 kt LAr target is performed using GEANT4. An exposure time of 100 years is considered, with a rate of <0.0012 events/kt/year at 90% CL predicted from our simulations.

  18. Image Processing Techniques applied to Liquid Argon Time Projection Chamber Data

    Science.gov (United States)

    Esquivel, Jessica; MicroBooNE Collaboration

    2015-04-01

    Large scale Liquid Argon Time Projection Chambers(LArTPC), like MicroBooNE, offer new ways to study neutrino cross sections and neutrino oscillations. The data from these LArTPCs are very detailed images of charged particles passing through the detector. A plethora of hit finding, cluster finding and tracking algorithms have been implemented to process data coming from MicroBooNE, but it is still possible that particle tracks that are easily visible by eye are being missed during data processing. Because the human eye sometimes does a better job at finding particle tracks that are sometimes missed by data processing, using Image Processing algorithms which emulate the human eye in conjunction with the already implemented algorithms could be beneficial. In particular Edge Detection algorithms could be useful due to the fact that tracks will often have defined deposited energy along straight lines. This talk will cover preliminary data processed with Edge Detection algorithms, and discussion of what the potential benefits are to this approach to LArTPC data analysis. On behalf of the MicroBooNE Collaboration.

  19. Characterization of UV-enhanced SiPMs for Imaging in High Pressure Xenon Electroluminescent TPC

    International Nuclear Information System (INIS)

    The possibility of recording charged particle tracks in an electro-luminescent xenon gas TPC is investigated using a SiPM-based tracking system, operated in the demonstrator prototype of the NEXT-100 ββ decay experiment. The tracks of the ββ0ν events from the decay of the 136Xe isotope have a distinctive topology, which allows their discrimination against single-electron events from the natural radioactivity that populates the region of interest of the neutrinoless decay in the ββ energy spectrum. Combined to the near-intrinsic energy resolution of the gaseous detector, this tracking capability provides a powerful background rejection tool for the search of the neutrinoless ββ decay aimed by the experiment. The NEXT-100 detector concepts and sensitivity and the first results of its demonstrator prototype are presented. The characterization studies relevant for the operation of UV-enhanced SiPMs used for imaging in an electro-luminescent TPC are reviewed. (authors)

  20. Liquid argon imaging a novel detection technology

    CERN Document Server

    Rubbia, Carlo

    2002-01-01

    Ionisation electrons may drift over large distances (meters) in a volume of highly purified liquid argon (O2 equivalent less than 0.1 ppb!) under the action of an electric field. With an appropriate readout system (i.e. a set of fine pitch wire grids) we have realised a massive, continuously sensitive 'bubble chamber' with multiple readouts of the same, small charge (a minimum ionising track segment, 2 mm long, yields • 10000 electrons). We have developed this technology since 1987, initially with small laboratory devices and later with progressively larger and more sophisticated detectors, the latest being the T600 module (740 ton of liquid Argon), which has been operated in Pavia, as a step toward the ICARUS programme in the Gran Sasso Laboratory (LNGS). With cloning of T600 we aim at a 3000 ton detector by 2005. Argon is a medium with density 1.4 g/cm3, similar in characteristics to the heavy freon used in the famous Gargamelle. With wire pitches of 2-3 mm, it provides an extremely high spatial re...

  1. The GAP-TPC

    CERN Document Server

    Rossi, B; Boiano, A; Catalanotti, S; Cocco, A G; Covone, G; Di Meo, P; Longo, G; Vanzanella, A; Walker, S; Wang, H; Wang, Y; Fiorillo, G

    2016-01-01

    Several experiments have been conducted worldwide, with the goal of observing low-energy nuclear recoils induced by WIMPs scattering off target nuclei in ultra-sensitive, low-background detectors. In the last few decades noble liquid detectors designed to search for dark matter in the form of WIMPs have been extremely successful in improving their sensitivities and setting the best limits. One of the crucial problems to be faced for the development of large size (multi ton-scale) liquid argon experiments is the lack of reliable and low background cryogenic PMTs: their intrinsic radioactivity, cost, and borderline performance at 87 K rule them out as a possible candidate for photosensors. We propose a brand new concept of liquid argon-based detector for direct dark matter search: the Geiger-mode Avalanche Photodiode Time Projection Chamber (GAP-TPC) optimized in terms of residual radioactivity of the photosensors, energy and spatial resolution, light and charge collection efficiency

  2. Neutrino Oscillations With A Next Generation Liquid Argon TPC Detector in Kamioka or Korea Along The J-PARC Neutrino Beam

    CERN Document Server

    Meregaglia, A

    2008-01-01

    The ``baseline setup'' for a possible, beyond T2K, next generation long baseline experiment along the J-PARC neutrino beam produced at Tokai, assumes two very large deep-underground Water Cerenkov imaging detectors of about 300 kton fiducial each, located one in Korea and the other in Kamioka but at the same off-axis angle. In this paper, we consider the physics performance of a similar setup but with a single and smaller, far detector, possibly at shallow depth, composed of a 100 kton next generation liquid Argon Time Projection Chamber. The potential location of the detector could be in the Kamioka area ($L\\sim 295$ km) or on the Eastern Korean coast ($L\\sim 1025$ km), depending on the results of the T2K experiment. In Korea the off-axis angle could be either $2.5^{o} \\sim 3^{o}$ as in SuperKamiokande, or $\\sim 1^{o}$ as to offer pseudo-wide-band beam conditions.

  3. TPC Workshop

    International Nuclear Information System (INIS)

    The first workshop to focus on time projection chambers was held at TRIUMF (Canada) this summer. Some 75 participants came from groups in Europe and North America using TPCs in a variety of applications in experimental physics. Reports included several general descriptions of existing detectors as well as some proposals for new instruments. A time projection chamber (TPC) is the name given to a class of large volume drift chambers which operate generally with parallel electric and magnetic fields. Applications span energies from a few MeV in double beta decay searches, through intermediate energies in muon decay studies to large high energy arrays planned for LEP at CERN

  4. Search for anomalies in the neutrino sector with muon spectrometers and large LArTPC imaging detectors at CERN

    CERN Document Server

    Antonello, A; Baibussinov, B; Bilokon, H; Boffelli, F; Bonesini, M; Calligarich, E; Canci, N; Centro, S; Cesana, A; Cieslik, K; Cline, D B; Cocco, A G; Dequal, D; Dermenev, A; Dolfini, R; De Gerone, M; Dussoni, S; Farnese, C; Fava, A; Ferrari, A; Fiorillo, G; Garvey, G T; Gatti, F; Gibin, D; Gninenko, S; Guber, F; Guglielmi, A; Haranczyk, M; Holeczek, J; Ivashkin, A; Kirsanov, M; Kisiel, J; Kochanek, I; Kurepin, A; Lagoda, J; Lucchini, G; Louis, W C; Mania, S; Mannocchi, G; Marchini, S; Matveev, V; Menegolli, A; Meng, G; Mills, G B; Montanari, C; Nicoletto, M; Otwinowski, S; Palczewki, T J; Passardi, G; Perfetto, F; Picchi, P; Pietropaolo, F; Plonski, P; Rappoldi, A; Raselli, G L; Rossella, M; Rubbia, C; Sala, P; Scaramelli, A; Segreto, E; Stefan, D; Stepaniak, J; Sulej, R; Suvorova, O; Terrani, M; Tlisov, D; Van de Water, R G; Trinchero, G; Turcato, M; Varanini, F; Ventura, S; Vignoli, C; Wang, H G; Yang, X; Zani, A; Zaremba, K; Benettoni, M; Bernardini, P; Bertolin, A; Brugnera, R; Calabrese, M; Cecchetti, A; Cecchini, S; Collazuol, G; Creti, P; Corso, F Dal; Del Prete, A; De Mitri, I; De Robertis, G; De Serio, M; Esposti, L Degli; Di Ferdinando, D; Dore, U; Dusini, S; Fabbricatore, P; Fanin, C; Fini, R A; Fiore, G; Garfagnini, A; Giacomelli, G; Giacomelli, R; Guandalini, C; Guerzoni, M; Kose, U; Laurenti, G; Laveder, M; Lippi, I; Loddo, F; Longhin, A; Loverre, P; Mancarella, G; Mandrioli, G; Margiotta, A; Marsella, G; Mauri, N; Medinaceli, E; Mengucci, A; Mezzetto, M; Michinelli, R; Muciaccia, M T; Orecchini, D; Paoloni, A; Papadia, G; Pastore, A; Patrizii, L; Pozzato, M; Rosa, G; Sahnounm, Z; Simone, S; Sioli, M; Sirri, G; Spurio, M; Stanco, L; Surdo, A; Tenti, M; Togo, V; Ventura, M; Zago, M

    2012-01-01

    A new experiment with an intense ~2 GeV neutrino beam at CERN SPS is proposed in order to definitely clarify the possible existence of additional neutrino states, as pointed out by neutrino calibration source experiments, reactor and accelerator experiments and measure the corresponding oscillation parameters. The experiment is based on two identical LAr-TPCs complemented by magnetized spectrometers detecting electron and muon neutrino events at Far and Near positions, 1600 m and 300 m from the proton target, respectively. The ICARUS T600 detector, the largest LAr-TPC ever built with a size of about 600 ton of imaging mass, now running in the LNGS underground laboratory, will be moved at the CERN Far position. An additional 1/4 of the T600 detector (T150) will be constructed and located in the Near position. Two large area spectrometers will be placed downstream of the two LAr-TPC detectors to perform charge identification and muon momentum measurements from sub-GeV to several GeV energy range, greatly comple...

  5. GEM-based TPC with CCD Imaging for Directional Dark Matter Detection

    CERN Document Server

    Phan, N S; Lee, E R; Loomba, D; Matthews, J A J; Miller, E H

    2015-01-01

    Directional dark matter detection will require scale-ups to large volumes if low-pressure gas Time Projection Chambers (TPCs) are the only viable technology. We discuss some of the challenges for this technology, where balancing the goal of achieving the best sensitivity with that of cost effective scale-up requires an optimization over a large parameter space. Critical for this are the precision measurements of the fundamental properties of both electron and nuclear recoil tracks down to the lowest energies. Such measurements would provide a benchmark for background discrimination and directional sensitivity that could be used for future optimization studies for directional dark matter experiments. In this paper we describe a small, high resolution, high signal-to-noise GEM-based TPC with a 2D CCD readout designed for this goal. The performance of the detector was characterized using X-rays, gamma-rays, and neutrons, enabling detailed measurements of electron and nuclear recoil tracks. Stable effective gas g...

  6. Imaging of hydrogen halides photochemistry on argon and ice nanoparticles

    International Nuclear Information System (INIS)

    The photodissociation dynamics of HX (X = Cl, Br) molecules deposited on large ArN and (H2O)N, N¯≈ 102–103, clusters is investigated at 193 nm using velocity map imaging of H and Cl photofragments. In addition, time-of-flight mass spectrometry after electron ionization complemented by pickup cross section measurements provide information about the composition and structure of the clusters. The hydrogen halides coagulate efficiently to generate smaller (HX)n clusters on ArN upon multiple pickup conditions. This implies a high mobility of HX molecules on argon. On the other hand, the molecules remain isolated on (H2O)N. The photodissociation on ArN leads to strong H-fragment caging manifested by the fragment intensity peaking sharply at zero kinetic energy. Some of the Cl-fragments from HCl photodissociation on ArN are also caged, while some of the fragments escape the cluster directly without losing their kinetic energy. The images of H-fragments from HX on (H2O)N also exhibit a strong central intensity, however, with a different kinetic energy distribution which originates from different processes: the HX acidic dissociation followed by H3O neutral hydronium radical formation after the UV excitation, and the slow H-fragments stem from subsequent decay of the H3O. The corresponding Cl-cofragment from the photoexcitation of the HCl·(H2O)N is trapped in the ice nanoparticle

  7. Imaging of hydrogen halides photochemistry on argon and ice nanoparticles.

    Science.gov (United States)

    Poterya, V; Lengyel, J; Pysanenko, A; Svrčková, P; Fárník, M

    2014-08-21

    The photodissociation dynamics of HX (X = Cl, Br) molecules deposited on large ArN and (H2O)N, N̄ ≈ 10(2)-10(3), clusters is investigated at 193 nm using velocity map imaging of H and Cl photofragments. In addition, time-of-flight mass spectrometry after electron ionization complemented by pickup cross section measurements provide information about the composition and structure of the clusters. The hydrogen halides coagulate efficiently to generate smaller (HX)n clusters on ArN upon multiple pickup conditions. This implies a high mobility of HX molecules on argon. On the other hand, the molecules remain isolated on (H2O)N. The photodissociation on ArN leads to strong H-fragment caging manifested by the fragment intensity peaking sharply at zero kinetic energy. Some of the Cl-fragments from HCl photodissociation on ArN are also caged, while some of the fragments escape the cluster directly without losing their kinetic energy. The images of H-fragments from HX on (H2O)N also exhibit a strong central intensity, however, with a different kinetic energy distribution which originates from different processes: the HX acidic dissociation followed by H3O neutral hydronium radical formation after the UV excitation, and the slow H-fragments stem from subsequent decay of the H3O. The corresponding Cl-cofragment from the photoexcitation of the HCl·(H2O)N is trapped in the ice nanoparticle. PMID:25149788

  8. Electron Neutrino Classification in Liquid Argon Time Projection Chamber Detector

    OpenAIRE

    Płoński, Piotr; Stefan, Dorota; Sulej, Robert; Zaremba, Krzysztof

    2015-01-01

    Neutrinos are one of the least known elementary particles. The detection of neutrinos is an extremely difficult task since they are affected only by weak sub-atomic force or gravity. Therefore large detectors are constructed to reveal neutrino's properties. Among them the Liquid Argon Time Projection Chamber (LAr-TPC) detectors provide excellent imaging and particle identification ability for studying neutrinos. The computerized methods for automatic reconstruction and identification of parti...

  9. Current and future liquid argon neutrino experiments

    International Nuclear Information System (INIS)

    The liquid argon time projection chamber (LArTPC) detector technology provides an opportunity for precision neutrino oscillation measurements, neutrino cross section measurements, and searches for rare processes, such as SuperNova neutrino detection. These proceedings review current and future LArTPC neutrino experiments. Particular focus is paid to the ICARUS, MicroBooNE, LAr1, 2-LArTPC at CERN-SPS, LBNE, and 100 kton at Okinoshima experiments

  10. Evidence of electric breakdown induced by bubbles in liquid argon

    CERN Document Server

    Bay, F; Murphy, S; Resnati, F; Rubbia, A; Sergiampietri, F; Wu, S

    2014-01-01

    We report on the results of a high voltage test in liquid argon in order to measure its dielectric rigidity. Under stable conditions and below the boiling point, liquid argon was found to sustain a uniform electric field of 100 kV/cm, applied in a region of 20 cm$^2$ area across 1 cm thick gap. When the liquid is boiling, breakdowns may occur at electric fields as low as 40 kV/cm. This test is one of the R&D efforts towards the Giant Liquid Argon Charge Imaging ExpeRiment (GLACIER) as proposed Liquid Argon Time Projection Chamber (LAr TPC) for the LBNO observatory for neutrino physics, astrophysics and nucleon decay searches.

  11. Electron Neutrino Classification in Liquid Argon Time Projection Chamber Detector

    CERN Document Server

    Płoński, Piotr; Sulej, Robert; Zaremba, Krzysztof

    2015-01-01

    Neutrinos are one of the least known elementary particles. The detection of neutrinos is an extremely difficult task since they are affected only by weak sub-atomic force or gravity. Therefore large detectors are constructed to reveal neutrino's properties. Among them the Liquid Argon Time Projection Chamber (LAr-TPC) detectors provide excellent imaging and particle identification ability for studying neutrinos. The computerized methods for automatic reconstruction and identification of particles are needed to fully exploit the potential of the LAr-TPC technique. Herein, the novel method for electron neutrino classification is presented. The method constructs a feature descriptor from images of observed event. It characterizes the signal distribution propagated from vertex of interest, where the particle interacts with the detector medium. The classifier is learned with a constructed feature descriptor to decide whether the images represent the electron neutrino or cascade produced by photons. The proposed ap...

  12. Fast-imaging and spectroscopic analysis of atmospheric argon streamers for large gap arc breakdown

    Science.gov (United States)

    Pachuilo, Michael; Stefani, Francis; Bengtson, Roger; Raja, Laxminarayan

    2014-10-01

    A non-equilibrium plasma source has been developed to assist in the low-voltage arc breakdown of large electrode gaps. The source consists of a dielectric embedded wire helically wound around a confining cylindrical quartz chamber. Annular electrodes cap the ends of the quartz chamber. An argon feed gas is used to provide a uniform environment and exhausts to ambient atmospheric conditions. A negative polarity 50 kV trigger pulse is applied to the embedded trigger wire to initiate the arc breakdown. Application of the trigger pulse produces a localized coronal discharges along the inner surface of the quartz tube. The corona provides seed electrons through which streamers propagate from one of the main discharge electrode along the quartz surface until it reaches the opposite electrode to bridge the gap. Once the gap is bridged a spark over occurs and robust arc discharge is formed in the chamber volume. Fast imaging of the streamer propagation establishes its velocity in the range of ~ 100 km/s. Spectroscopy of the streamer discharge in atmospheric argon has been conducted and electron temperature and number density estimated from a collision radiative model. Argon spectrum is dominated by neutral argon lines in the 650--950 nm range, and singly ionized argon lines are observed in the ultra-violet to near UV (300--400 nm). Research was performed in connection with AFOSR Contract FA9550-11-1-0062.

  13. ALICE installs its TPC

    CERN Document Server

    2007-01-01

    The ALICE time projection chamber has been transported to the experimental cavern. The handling of this extremely fragile detector was a long and delicate process. The lorry transporting the TPC took one hour to travel from the assembly hall to the access shaft...200 metres away.The TPC was lowered into the ALICE experimental cavern with extreme care. The gap between the structure and the shaft wall was only 10 centimetres! For ALICE the year started with a flurry of activity...but at a snail's pace. On 8 January, the day CERN reopened after the end-of-year break, teams from ALICE and the TS Department began the transportation of the experiment's time projection chamber (TPC), the largest ever built. This 5-metre long and 5-m diameter cylinder was transported from the clean room where it had been assembled to the experimental cavern. The 300-metre journey took no less than four days! Since the TPC is an extremely fragile object, the utmost precautions were exercised in its transportation. The TPC, which is d...

  14. Research and development program on dense TPC's at LBL

    International Nuclear Information System (INIS)

    We have initiated a research and development program at LBL to develop high density TPC's. We are motivated by their potential use as tracking calorimeters to study nucleon decay. They may also be useful in the study of cosmic neutrino fluxes, double β decay and other low rate processes. Of these applications, the use of dense TPC's to study nucleon decay is the most challenging one because it requires instrumenting very large masses. Our R and D program is aimed at developing large TPC's which are competitive in cost with other proposed nucleon decay detectors while offering superior capabilities for energy resolution, particle identification and uniformity of response. There are two ways of obtaining high density TPC's: the first is to use a cryogenic liquid such as liquid argon or liquid methane; the second is to pressurize a gas such as argon or methane to several hundred atmospheres where the density of the gas approaches that of the liquid state. While we are interested in studying both approaches, we are concentrating on the high pressure approach since it offers the potential advantage of proportional wire amplification. A wire amplification of about 3 orders of magnitude would eliminate the noise problems which are inherent in ionization mode detectors such as liquid argon chambers. A possible 10 kton detector is described, and its properties are discussed in terms of tracking, energy measurements and particle identification

  15. Ideas for future liquid Argon detectors

    International Nuclear Information System (INIS)

    We outline a strategy for future experiments on neutrino and astroparticle physics based on the use, at different detector mass scales (100 ton and 100 kton), of the liquid Argon Time Projection Chamber (LAr TPC) technique. The LAr TPC technology has great potentials for both cases with large degree of interplay between the two applications and a strong synergy. The ICARUS R and D programme has demonstrated that the technology is mature and that one can built a large (∼ 1 kton) LAr TPC. We believe that one can conceive and design a very large mass LAr TPC with a mass of 100 kton by employing a monolithic technology based on the use of industrial, large volume cryogenic tankers developed by the petro-chemical industry. We show a potential implementation of a large LAr TPC detector. Such a detector would be an ideal match for a Superbeam[New J. Phys. 4 (2002) 88 [arXiv:hep-ph/0208047

  16. A Muti-channel Distributed DAQ for n-TPC

    OpenAIRE

    Xiaolei, Cheng; jianfang, Liu; Qian, Yu; libo, Niu; Yulan, Li

    2015-01-01

    A new fast neutron spectrometer named n-TPC has been designed by LPRI (Key Laboratory of Particle & Radiation Imaging, Ministry of Education) at Tsinghua University. The neutron energy spectrum can be calculated from the recoil angle and energy of the recoil proton detected by a 704-pad GEM-TPC. In beam tests at IHIP (Institute of Heavy Ion Physics, Peking University) in 2014, n-TPC performed better than 6 percents at 6MeV energy resolution and 0.5 percents detection efficiency. To find the b...

  17. On TPC cluster reconstruction

    CERN Document Server

    Dydak, F; Nefedov, Y; Wotschack, J; Zhemchugov, A

    2004-01-01

    For a bias-free momentum measurement of TPC tracks, the correct determination of cluster positions is mandatory. We argue in particular that (i) the reconstruction of the entire longitudinal signal shape in view of longitudinal diffusion, electronic pulse shaping, and track inclination is important both for the polar angle reconstruction and for optimum r phi resolution; and that (ii) self-crosstalk of pad signals calls for special measures for the reconstruction of the z coordinate. The problem of 'shadow clusters' is resolved. Algorithms are presented for accepting clusters as 'good' clusters, and for the reconstruction of the r phi and z cluster coordinates, including provisions for 'bad' pads and pads next to sector boundaries, respectively.

  18. An optical imaging method for studying the spatial distribution of argon clusters

    International Nuclear Information System (INIS)

    An optical imaging method based on Rayleigh scattering is introduced to study the spatial distribution of atomic argon clusters produced in a gas jet. The radial distribution and evolution of the clusters are captured directly by a high speed camera, resulting in greatly increased precision and accuracy. It is found that the radial distribution of the clusters follows a Gaussian curve rather than the double-humped curve observed in a previous experiment. The normalized radial and axial distributions of the clusters are not influenced by the stagnation pressure and may be strictly determined by the nozzle structure. The average cluster sizes decrease slightly at far axial distances. A method of estimating the half-angle of the nozzle is also presented

  19. A Muti-channel Distributed DAQ for n-TPC

    CERN Document Server

    Xiaolei, Cheng; Qian, Yu; libo, Niu; Yulan, Li

    2015-01-01

    A new fast neutron spectrometer named n-TPC has been designed by LPRI (Key Laboratory of Particle & Radiation Imaging, Ministry of Education) at Tsinghua University. The neutron energy spectrum can be calculated from the recoil angle and energy of the recoil proton detected by a 704-pad GEM-TPC. In beam tests at IHIP (Institute of Heavy Ion Physics, Peking University) in 2014, n-TPC performed better than 6 percents at 6MeV energy resolution and 0.5 percents detection efficiency. To find the best working parameters (the component and proportion of the gas, the high voltage between each GEM layer, etc.) of the n-TPC and support its application in various conditions, a multichannel distributed DAQ has been design to read out the signals from the 704 channels. With over 25 Ms/s sampling rate and 12 bit resolution for each channel, it can record the time and amplitude information as well as traditional DAQs in the TPC application domain. The main design objective of this distributed DAQ, however, is more flexi...

  20. Performance of TPC crosstalk correction

    CERN Document Server

    Dydak, F; Krasnoperov, A; Nefedov, Y; Wotschack, J; Zhemchugov, A

    2004-01-01

    The performance of the CERN-Dubna-Milano (CDM) algorithm for TPC crosstalk correction is presented. The algorithm is designed to correct for uni-directional and bi-directional crosstalk, but not for self-crosstalk. It reduces at the 10% level the number of clusters, and the number of pads with a signal above threshold. Despite of dramatic effects in selected channels with complicated crosstalk patterns, the average longitudinal signal shape of a hit, and the average transverse signal shape of a cluster, are little affected by uni-directional and bi-directional crosstalk. The longitudinal signal shape of hits is understood in terms of preamplifier response, longitudinal diffusion, track inclination, and self-crosstalk. The transverse signal shape of clusters is understood in terms of the TPC's pad response function. The CDM crosstalk correction leads to an average charge decrease at the level of 15%, though with significant differences between TPC sectors. On the whole, crosstalk constitutes a relatively benig...

  1. First working prototype of a steerable UV laser system for LArTPC calibrations

    CERN Document Server

    Ereditato, A; Kreslo, I; Lüthi, M; von Rohr, C Rudolf; Schenk, M; Strauss, T; Weber, M; Zeller, M

    2014-01-01

    A number of liquid argon time projection chambers (LArTPC's) are build for or proposed as neutrino experiments on long- and short baseline beams. For these drift chambers a distortion in the drift field can appear especially if the detectors are located at surface or shallow depths due to space charge accumulation by the slower drifting ions. Depending on the TPC's geometry and electric drift field strength the distortion could be of the same magnitude as the drift field itself. We present a method to calibrate the drift field and correct for these possible distortions. While straight cosmic tracks could provide this measurement, the multiple coulomb scattering and momentum uncertainties allow only a limited resolution. A UV laser can create straight ionization tracks, and allows to map the drift field along different paths in the TPC volume. A UV laser feed-through design with a steerable UV mirror in liquid argon can point the laser beam at many locations through the TPC for the field mapping. The design in...

  2. A new concept of y-ray telescope. LArGO: Liquid Argon Gamma-ray Observatory

    OpenAIRE

    Caliandro, Giuseppe Andrea; Rossi, Biagio; Longo, Francesco; Fiorillo, Giuliana; Labanti, Claudio; Sanchez, Federico; Lux, Thorsten

    2013-01-01

    LArGO (Liquid Argon Gamma-ray Observatory) consists of a new design for a $\\gamma$-ray telescope, which exploits the idea of using a Liquid Argon Time Projection Chamber (LAr-TPC) as tracker-converter. Particle tracking in LAr-TPC can efficiently starts since the primary photon vertex. Indeed, while in the present space telescopes the incident photon converts in a tungsten foil, which is a passive material, in a LAr-TPC this conversion happens in LAr itself, which is fully active. In this pro...

  3. Protonated water clusters in TPC's

    Science.gov (United States)

    Kaya, Yunus; Kalkan, Yalçın; Veenhof, Rob

    2016-07-01

    Water vapour is added to the ALICE TPC gas to enhance its stability. These polar molecules create large protonated water clusters around a H+ core. In this context, the reactions H3O+(H2O)n-1 +H2 O →H3O+(H2O)n (n=1-9) were studied in the gas phase. Structures for these clusters are suggested and the most stable structures for each cluster size are shown. The thermodynamic parameters Δ Hn-1,n0,Δ Gn-1,n0,Δ Sn-1,n0 and equilibrium constants Kn-1,n for the reaction were calculated to determine the size of the water clusters. The results are close to experimental data found in the literature. Protonated water clusters at stp have a size of 6-9 which corresponds to a mass of 127.1 - 181.2 g / mole.

  4. Positive ion suppression with untriggered TPC

    International Nuclear Information System (INIS)

    A TPC sector can be operated in a mode that permits electron collection by the sense wires while simultaneously preventing the resulting positive ions from returning to the TPC volume. In the presence of a sufficiently strong magnetic field, electrons are less affected than ions by electric field components transverse to the magnetic field. Thus the requirement that electron drift trajectories terminate on sense wires does not necessarily imply that positive ion drift trajectories return to the TPC volume. The motivation for a static one-way grid is given. The physical principles involved are presented. The optimization of the design of a static one-way grid is discussed

  5. Integrated plan for LArTPC neutrino detectors in the US

    Energy Technology Data Exchange (ETDEWEB)

    Baller, B.; Fleming, B.; /Fermilab

    2009-11-01

    We present an integrated R&D plan aimed at demonstrating the ability to build a very large Liquid Argon Time Projection Chamber (LArTPC), on a scale suitable for use as a Far Detector for the LBNE neutrino oscillation experiment. This plan adopts current LArTPC R&D-related activities and proposes new ones to address questions that go beyond those being answered by the current efforts. We have employed a risk evaluation strategy to identify questions that can be answered (or risks that can be mitigated) through one or more R&D steps. In summary form, the plan consists of the following pre-existing components: (1) The Materials Test Stand program, now in operation at Fermilab, addressing questions pertaining to maintenance of argon purity; (2) Existing electronics test stands at FNAL and BNL; (3) The Liquid Argon Purity Demonstrator (LAPD) now being assembled at Fermilab; (4) The ArgoNeuT prototype LArTPC, now running in the NuMI beam; (5) The MicroBooNE experiment, proposed as a physics experiment that will advance our understanding of the LArTPC technology, now completing its conceptual design phase; (6) A software development effort that is well integrated across present and planned LArTPC detectors. We are proposing to add to these efforts the following: (1) A membrane cryostat mechanical prototype to evaluate and gain expertise with this technology; (2) An installation and integration prototype, to understand issues pertaining to detector assembly, particularly in an underground environment; (3) A {approx} 5% scale electronics systems test to understand system-wide issues as well as individual component reliability. (4) A calibration test stand that would consist of a small TPC to be exposed to a test beam for calibration studies, relevant for evaluation of physics sensitivities. We have developed a timeline and milestones for achieving these goals as discussed in Section 4. The proposed activities necessary for the final design of LAr20 are complete by CD3 in

  6. Cryogenic testing of the TPC superconducting solenoid

    Science.gov (United States)

    Green, M. A.; Smits, R. G.; Taylor, J. D.; Vanslyke, V.; Barrera, F.; Petersen, H.; Rago, C. E.; Rinta, R. I.; Talaska, D.; Watt, R. D.

    1983-06-01

    This report describes the results of a series of tests on the TPC superconducting magnet cryogenic system which occurred during the winter and spring of 1983. The tests occurred at interaction region 2 of the PEP colliding beam facility at the Stanford Linear Accelerator Center (SLAC). The TPC Magnet Cryogenic System which was tested includes the following major components: a remote helium compressor with a full flow liquid nitrogen purification station, 400 meters of high pressure supply and low pressure return lines; and locally a CTi Model 2800 refrigerator with two Sulzer gas bearing turbines, the TPC magnet control dewar, 70 meters of transfer lines, and the TPC thin superconducting solenoid magnet. In addition, there is a conditioner (liquid nitrogen heat exchangers and gas heaters) system for cooldown and warmup of the magnet. This report describes the local cryogenic system and describes the various steps in the cooldown and operation of the TPC magnet. The tests were successful in that they showed that the TPC magnet could be cooled down in 24 hours and the magnet could be operated on the refrigerator or a helium pump with adequate cooling margin.

  7. Signal Processing in the MicroBooNE LArTPC

    CERN Document Server

    Joshi, Jyoti

    2015-01-01

    The MicroBooNE experiment is designed to observe interactions of neutrinos with a Liquid Argon Time Projection Chamber (LArTPC) detector from the on-axis Booster Neutrino Beam (BNB) and off-axis Neutrinos at the Main Injector (NuMI) beam at Fermi National Accelerator Laboratory. The detector consists of a $2.5~m\\times 2.3~m\\times 10.4~m$ TPC including an array of 32 PMTs used for triggering and timing purposes. The TPC is housed in an evacuable and foam insulated cryostat vessel. It has a 2.5 m drift length in a uniform field up to 500 V/cm. There are 3 readout wire planes (U, V and Y co-ordinates) with a 3-mm wire pitch for a total of 8,256 signal channels. The fiducial mass of the detector is 60 metric tons of LAr. In a LArTPC, ionization electrons from a charged particle track drift along the electric field lines to the detection wire planes inducing bipolar signals on the U and V (induction) planes, and a unipolar signal collected on the (collection) Y plane. The raw wire signals are processed by speciali...

  8. Development of liquefaction circulation system for liquid-Ar TPC detector

    International Nuclear Information System (INIS)

    We are developing the high efficiently circulation system for refining liquid argon to high purity for the hundred kton liquid argon TPC. In this measurement, the liquefaction efficiency was measured with the length and the material of the heat exchanger coil. The performance of re-condenser was measured with the test bench and the prototype cryostat with size of 250 L. The efficiency of liquefaction was about 86% with the test bench. With the system of connecting of the re-condenser to the 250LAr container, the flow rate of circulating gas is the maximum 25L/min on -188.5degC of cold head temperature and the maximum 48L/min on -185.7degC. When operating by 48L/min of flow rate of supplied gas, the liquid argon of 300L was able to circulate in about 82 hours. (author)

  9. The FIDIAS project: Development of a Micromegas TPC for the detection of low-energy heavy ions

    Science.gov (United States)

    Iguaz, Francisco José; Panebianco, Stefano; Axiotis, Michael; Druillole, Frédéric; Fanourakis, George; Geralis, Theodoros; Giomataris, Ioannis; Harissopulos, Sotirios; Lagoyannis, Anastasios; Papaevangelou, Thomas

    2014-01-01

    Time Projection Chambers are widely used since many years for tracking and identification of charged particles in high energy physics. We present here a new R&D project, called FIDIAS, meant to investigate the feasibility of a Micromegas TPC for low energy heavy ions detection. In this framework, a TPC prototype based on Micromegas bulk technique has been extensively tested with spontaneous fission source. A deep analysis of the experimental results has been realized leading to a full characterization of the prototype in terms of gain, energy resolution and track reconstruction as a function of three working gas: helium, neon and argon. The encouraging results have also been compared to simulations, showing the Micromegas TPC is a very well suited detector for the detection of heavy ions in nuclear reactions at low energy.

  10. Improved mass resolution and mass accuracy in TOF-SIMS spectra and images using argon gas cluster ion beams.

    Science.gov (United States)

    Shon, Hyun Kyong; Yoon, Sohee; Moon, Jeong Hee; Lee, Tae Geol

    2016-06-01

    The popularity of argon gas cluster ion beams (Ar-GCIB) as primary ion beams in time-of-flight secondary ion mass spectrometry (TOF-SIMS) has increased because the molecular ions of large organic- and biomolecules can be detected with less damage to the sample surfaces. However, Ar-GCIB is limited by poor mass resolution as well as poor mass accuracy. The inferior quality of the mass resolution in a TOF-SIMS spectrum obtained by using Ar-GCIB compared to the one obtained by a bismuth liquid metal cluster ion beam and others makes it difficult to identify unknown peaks because of the mass interference from the neighboring peaks. However, in this study, the authors demonstrate improved mass resolution in TOF-SIMS using Ar-GCIB through the delayed extraction of secondary ions, a method typically used in TOF mass spectrometry to increase mass resolution. As for poor mass accuracy, although mass calibration using internal peaks with low mass such as hydrogen and carbon is a common approach in TOF-SIMS, it is unsuited to the present study because of the disappearance of the low-mass peaks in the delayed extraction mode. To resolve this issue, external mass calibration, another regularly used method in TOF-MS, was adapted to enhance mass accuracy in the spectrum and image generated by TOF-SIMS using Ar-GCIB in the delayed extraction mode. By producing spectra analyses of a peptide mixture and bovine serum albumin protein digested with trypsin, along with image analyses of rat brain samples, the authors demonstrate for the first time the enhancement of mass resolution and mass accuracy for the purpose of analyzing large biomolecules in TOF-SIMS using Ar-GCIB through the use of delayed extraction and external mass calibration. PMID:26861497

  11. Inbetriebnahme und Kalibrierung der ALICE-TPC

    OpenAIRE

    Wiechula, Jens

    2010-01-01

    ALICE (A Large Ion Collider Experiment), is the dedicated heavy-ion experiment at the Large Hadron Collider (LHC) at CERN. It is optimised to reconstruct and identify the particles created in a lead-lead collision with a centre of mass energy of 5.5TeV. The main tracking detector is a large-volume time-projection chamber (TPC). With an active volume of about 88m^3 and a total readout area of 32.5m^2 it is the most challenging TPC ever build. A central electrode divides the 5m long detector in...

  12. Front end electronics for the STAR TPC

    International Nuclear Information System (INIS)

    The Solenoidal Tracker at RHIC (STAR) is a large acceptance detector now being built to study high energy heavy ion collisions. It detects charged particles with a large time projection chamber. The 136,600 TPC pads are instrumented with waveform digitizers, implemented in custom low noise preamplifier/shaper and switched capacitor array/ADCs ICs. The system is highly integrated with all analog functions mounted on small cards that plug into the TPC. Detector mounted readout boards multiplex data from 1,152 channels onto a 1.5 Gbit/sec fiber optic link to the data acquisition system

  13. Study in a beam test of the resolution of a Micromegas TPC with standard readout pads

    International Nuclear Information System (INIS)

    The results of a beam test performed at the KEK PS in June 2005 are presented. Drift properties of an argon-isobutane mixture have been accurately measured and compared with predictions at magnetic fields between 0 and 1 T. The r.m.s. point resolution of a padrow is compared with simulation and with an analytical calculation. The fundamental limitations due to detector geometry and gas properties are reviewed and the measured performances of the detector are found to be close to this limit. A numerical application to the case of a linear collider Time Projection Chamber (TPC) is presented.

  14. ALICE Time Projection Chamber (TPC) Readout Sector in Lab

    CERN Multimedia

    2003-01-01

    The Time Projection Chamber (TPC) is the main particle tracking detector in ALICE. Charged particles crossing the gas of the TPC knock electrons out of their atoms, which drift in the eletric field. By measuring the arrival of electrons at the end of the chamber, at segments such as the one shown here, the TPC will reconstruct the paths of the original charged particles.

  15. TPC1 - SV Channels Gain Shape

    Institute of Scientific and Technical Information of China (English)

    Rainer Hedrich; Irene Marten

    2011-01-01

    T The most prominent ion channel localized in plant vacuoles is the slow activating SV type. Slow vacuolar (SV)channels were discovered by patch clamp studies as early as 1986. In the following two decades, numerous studies revealed that these calcium- and voltage-activated, nonselective cation channels are expressed in the vacuoles of all plants and every plant tissue. The voltage-dependent properties of the SV channel are susceptible to modulation by calcium, pH, redox state, as well as regulatory proteins. In Arabidopsis, the SV channel is encoded by the AtTPC1 gene, and even though its gene product represents the by far largest conductance of the vacuolar membrane, tpc1-loss-of-function mutants appeared not to be impaired in major physiological functions such as growth, development, and reproduction. In contrast, the fou2 gain-of-function point mutation D454N within TPC1 leads to a pronounced growth phenotype and increased synthesis of the stress hormone jasmonate. Since the TPC1 gene is present in all land plants, it likely encodes a very general function. In this review, we will discuss major SV channel properties and their impact on plant cell physiology.

  16. TPC with GEM readout for TESLA

    International Nuclear Information System (INIS)

    A Time Projection Chamber (TPC) is proposed as the main tracking device for the detector at the future e+e- linear accelerator now studied in Europe. The performance requirements and the basic design using a Gas Electron Multiplier (GEM) as the readout device are described. Some preliminary R and D results are discussed

  17. Data links for the EOS TPC

    International Nuclear Information System (INIS)

    We report on the design and performance of high speed data links and slower configuration control links used between the EOS TPC detector and the data processing electronics. Data rates of 5MBytes/s/link are maintained over 30m with optical isolation. Pedestal subtraction, hit detection, and data reordering are performed online. 3 refs., 1 fig

  18. Liquid Argon Time Projection Chamber Research and Development in the United States

    CERN Document Server

    Bromberg, C; Junk, T; Katori, T; Lang, K; Marchionni, A; Mauger, C; Mufson, S; Pordes, S; Raaf, J; Rebel, B; Soderberg, M; Thorn, C; Urheim, J

    2013-01-01

    A workshop was held at Fermilab on March 20-21, 2013 to discuss the development of liquid argon time projection chambers (LArTPC) in the United States. The workshop was organized under the auspices of the Coordinating Panel for Advanced Detectors, a body that was initiated by the American Physical Society Division of Particles and Fields. All presentations at the workshop were made in plenary sessions organized into seven topical categories: $i)$ Argon Purity, $ii)$ Cryogenics, $iii)$ TPC and High Voltage, $iv)$ Electronics, Data Acquisition and Triggering, $v)$ Scintillation Light Detection, $vi)$ Calibration and Test Beams, and $vii)$ Software. This document summarizes the current efforts in each of these topical categories. It also highlights areas in LArTPC research and development that are common between neutrino experiments and dark matter experiments.

  19. HARPO: beam characterization of a TPC for gamma-ray polarimetry and high angular-resolution astronomy in the MeV-GeV range

    CERN Document Server

    Wang, Shaobo; Bruel, Philippe; Frotin, Mickael; Geerebaert, Yannick; Giebels, Berrie; Gros, Philippe; Horan, Deirdre; Louzir, Marc; Poilleux, Patrick; Semeniouk, Igor; Attié, David; Calvet, Denis; Colas, Paul; Delbart, Alain; Sizun, Patrick; Götz, Diego; Amano, Sho; Kotaka, Takuya; Hashimoto, Satoshi; Minamiyama, Yasuhito; Takemoto, Akinori; Yamaguchi, Masashi; Miyamoto, Shuji; Daté, Schin; Ohkuma, Haruo

    2015-01-01

    A time projection chamber (TPC) can be used to measure the polarization of gamma rays with excellent angular precision and sensitivity in the MeV-GeV energy range through the conversion of photons to e+e- pairs. The Hermetic ARgon POlarimeter (HARPO) prototype was built to demonstrate this concept. It was recently tested in the polarized photon beam at the NewSUBARU facility in Japan. We present this data-taking run, which demonstrated the excellent performance of the HARPO TPC.

  20. GridPix application to dual phase TPC

    International Nuclear Information System (INIS)

    GridPix is a gas-filled detector with an aluminium mesh stretched 50 μm above the Timepix CMOS pixel chip. This defines a high electric field where gas amplification occurs. A feasibility study is ongoing at Nikhef for the application of the GridPix technology as a charge sensitive device in a dual phase noble gas Time Projection Chamber (TPC), within the framework of the DARWIN design study for next generation dark matter experiments. The smallness of the device and well defined materials allow for high radio-purity and low outgassing. The high granularity of a pixel readout and the high detection efficiency of single electrons of GridPix bring benefits especially in terms of energy resolution for small energy deposits. This feature is interesting also for the measurement of the scintillation yield and the ionisation yield of noble liquids. The accurate measurements of such quantities have a direct impact on the data interpretation of dark matter experiments. The application in dual phase argon or xenon TPCs implies several technological challenges, such as the survival of the device at cryogenic temperature as well as the operation in a pure noble gas atmosphere without discharges. We describe here the recent developments of the project

  1. Conceptual design of a large cavern for giant liquid argon charge imaging equipment in Oki-no-shima Island

    International Nuclear Information System (INIS)

    The T2K utilizing J-PARK high intensity started the data accumulation. If beam intensity of J-PARC will become the 1MW class in the future, we will build the cavern under the ground in Oki-no-shima to accommodate the experiment with 100kton liquid Ar TPC. Geologically, the Oki gneiss in the Oki-no-shima eastern side is very stable. The Oki gneiss is the one of the Japanese oldest rocks born about 2 billion years ago and compressive strength of the bedrock is about 80Mpa over. The development of the crack is not seen and has few springs in the underground. We designed large dome cylindrical cavern(the diameter 90m and the height 50m) for storage 100kton liquid Ar, some access tunnel and others connected to a cavern. (author)

  2. Results from the STAR TPC system test

    International Nuclear Information System (INIS)

    A system test of various components of the Solenoidal Tracker at RHIC (STAR) detector, operating in concern, has recently come on-line. Communication between a major sub-detector, a sector of the Time Projection Chamber (TPC), and the trigger, data acquisition and slow controls systems has been established, enabling data from cosmic ray muons to be collected. First results from an analysis of the TPC data are presented. These include measurements of system noise, electronic parameters such as amplifier gains and pedestal values, and tracking resolution for cosmic ray muons and laser induced ionization tracks. A discussion on the experience gained in integrating the different components for the system test is also given

  3. Strange particle measurements from the EOS TPC

    International Nuclear Information System (INIS)

    A high statistics sample of Λ's produced in 2 GeV/nucleon 58Ni + natCu collisions has been obtained with the EOS Time Projection Chamber at the Bevalac. The coverage of the EOS TPC is essentially 100% for y > ycm and extends down to PT = 0 where interesting effects such as collective radial expansion may be important. In addition, the detection of a majority of the charged particles in the TPC, along with the presence of directed flow for protons and heavier fragments at this beam energy, allows for the correlation of A production with respect to the event reaction plane. Our preliminary analysis indicates the first observation of a sidewards flow signature for A's. Comparisons with the cascade code ARC are made

  4. The STAR TPC front end electronics

    International Nuclear Information System (INIS)

    The Solenoidal Tracker at RHIC (STAR) uses a large time projection chamber. Each of the 136,600 pads is instrumented with a waveform digitizer, implemented in custom low noise preamplifier/shaper and switched capacitor array/ADCs ICs. The system is highly integrated with all analog functions mounted on small cards that plug into the TPC. Detector mounted readout boards multiplex data from 1152 channels onto a 1.5 Gbit/sec fiber optic link to the data acquisition system

  5. Proportional model calorimeters of the TPC facility

    International Nuclear Information System (INIS)

    Two wire proportional mode gas calorimeter modules have been tested as prototypes for the Pole Tip calorimeters of the TPC Facility at PEP. The results of the tests at several electron energies (0.25 to 12. GeV) and several pressures (1.0 to 30. atms) are presented, comparisons with a detailed simulation program are made, and results from the Pole Tip modules now operating at PEP are given

  6. Highly integrated electronics for the star TPC

    Energy Technology Data Exchange (ETDEWEB)

    Arthur, A.A.; Bieser, F.; Hearn, W.; Kleinfelder, S.; Merrick, T.; Millaud, J.; Noggle, T.; Rai, G.; Ritter, H.G.; Wieman, H. [Lawrence Berkeley Laboratory, CA (United States)

    1991-12-31

    The concept for the STAR TPC front-end electronics is presented and the progress toward the development of a fully integrated solution is described. It is the goal of the R+D program to develop the complete electronics chain for the STAR central TPC detector at RHIC. It is obvious that solutions chosen e.g. for ALEPH are not adequate for the 150000 channels that need to be instrumented for readout. It will be necessary to perform all the signal processing, digitization and multiplexing directly on the detector in order to reduce per channel cost and the amount of cabling necessary to read out the information. We follow the approach chosen by the EOS TPC project, where the readout electronics on the detector consists of an integrated preamplifier, a hybrid shaping amplifier, an integrated switched capacitor array and a highly multiplexed ADC. The STAR electronics will be further integrated so that approximately 16 channels of the preamplifier, the shaper, the analog store and the ADC will be contained in two integrated circuits located directly on the pad plane.

  7. Momentum scale in the HARP TPC

    CERN Document Server

    Catanesi, M G; Edgecock, R; Ellis, M; Soler, F J P; Gössling, C; Bunyatov, S; Krasnoperov, A; Popov, B; Serdiouk, V; Tereschenko, V; Di Capua, E; Vidal-Sitjes, G; Artamonov, A; Giani, S; Gilardoni, S; Gorbunov, P; Grant, A; Grossheim, A; Ivanchenko, V; Kayis-Topaksu, A; Panman, J; Papadopoulos, I; Chernyaev, E; Tsukerman, I; Veenhof, R; Wiebusch, C; Zucchelli, P; Blondel, A; Borghi, S; Morone, M C; Prior, G; Schroeter, R; Meurer, C; Gastaldi, Ugo; Mills, G B; Graulich, J S; Grégoire, G; Bonesini, M; Ferri, F; Kirsanov, M; Bagulya, A; Grichine, V; Polukhina, N; Palladino, V; Coney, L; Schmitz, D; Barr, G; De Santo, A; Bobisut, F; Gibin, D; Guglielmi, A; Mezzetto, M; Dumarchez, J; Dore, U; Orestano, D; Pastore, F; Tonazzo, A; Tortora, L; Booth, C; Howlett, L; Bogomilov, M; Chizhov, M; Kolev, D; Tsenov, R; Piperov, S; Temnikov, P; Apollonio, M; Chimenti, P; Giannini, G; Burguet-Castell, J; Cervera-Villanueva, A; Gómez-Cadenas, J J; Martín-Albo, J; Novella, P; Sorel, M

    2007-01-01

    Recently a claim was made that the reconstruction of the large angle tracks in the HARP TPC was affected by a momentum bias as large as 15% at 500 MeV/c transverse momentum. In the following we recall the main issues with the momentum measurement in the HARP TPC, and describe the cross-checks made to validate the momentum scale. Proton-proton elastic scattering data off the hydrogen target are used to alibrate the momentum of charged particles with a precision evaluated to be 3.5%. A full description of the time development of the dynamic distortions in the TPC during physics spills is now available together with a correction algorithm. This allows a new cross-check using an enlarged data set made by comparing positive and negative pion elasticscattering data collected with negative polarity of the solenoid magnet. These data confirm the absence of a bias in the sagitta measurement. The dE/dx versus momentum curves are revisited, and shown to provide a confirmation that the HARP momentum calibration is correc...

  8. Liquid argon neutrino detectors

    CERN Document Server

    Battistoni, G

    2001-01-01

    The liquid argon imaging technique, as proposed for the ICARUS detector, offers the possibility to perform complementary and simultaneous measurements of neutrinos, as those of CERN to Gran Sasso beam (CNGS) and those from cosmic ray events. For the currently allowed values of the Super-Kamiokande results, the combination of both CNGS and atmospheric data will provide a precise determination of the oscillation parameters. Since one can observe and unambiguously identify nu /sub e/, nu /sub mu / and nu /sub tau / components, this technology allows to explore the full (3*3) mixing matrix. The same class of detector can be proposed for high precision measurements at a neutrino factory. (3 refs).

  9. Search for “anomalies” from neutrino and anti-neutrino oscillations at $\\Delta_m^{2} ≈ 1eV^{2}$ with muon spectrometers and large LAr–TPC imaging detectors

    CERN Document Server

    Antonello, M; Baibussinov, B; Bilokon, H; Boffelli, F; Bonesini, M; Calligarich, E; Canci, N; Centro, S; Cesana, A; Cieslik, K; Cline, D B; Cocco, A G; Dequal, D; Dermenev, A; Dolfini, R; De Gerone, M; Dussoni, S; Farnese, C; Fava, A; Ferrari, A; Fiorillo, G; Garvey, G T; Gatti, F; Gibin, D; Gninenko, S; Guber, F; Guglielmi, A; Haranczyk, M; Holeczek, J; Ivashkin, A; Kirsanov, M; Kisiel, J; Kochanek, I; Kurepin, A; Łagoda, J; Lucchini, G; Louis, W C; Mania, S; Mannocchi, G; Marchini, S; Matveev, V; Menegolli, A; Meng, G; Mills, G B; Montanari, C; Nicoletto, M; Otwinowski, S; Palczewski, T J; Passardi, G; Perfetto, F; Picchi, P; Pietropaolo, F; Płonski, P; Rappoldi, A; Raselli, G L; Rossella, M; Rubbia, C; Sala, P; Scaramelli, A; Segreto, E; Stefan, D; Stepaniak, J; Sulej, R; Suvorova, O; Terrani, M; Tlisov, D; Van de Water, R G; Trinchero, G; Turcato, M; Varanini, F; Ventura, S; Vignoli, C; Wang, H G; Yang, X; Zani, A; Zaremba, K; Benettoni, M; Bernardini, P; Bertolin, A; Bozza, C; Brugnera, R; Cecchetti, A; Cecchini, S; Collazuol, G; Creti, P; Dal Corso, F; De Mitri, I; De Robertis, G; De Serio, M; Degli Esposti, L; Di Ferdinando, D; Dore, U; Dusini, S; Fabbricatore, P; Fanin, C; Fini, R A; Fiore, G; Garfagnini, A; Giacomelli, G; Giacomelli, R; Grella, G; Guandalini, C; Guerzoni, M; Kose, U; Laurenti, G; Laveder, M; Lippi, I; Loddo, F; Longhin, A; Loverre, P; Mancarella, G; Mandrioli, G; Margiotta, A; Marsella, G; Mauri, N; Medinaceli, E; Mengucci, A; Mezzetto, M; Michinelli, R; Muciaccia, M T; Orecchini, D; Paoloni, A; Pastore, A; Patrizii, L; Pozzato, M; Rescigno, R; Rosa, G; Simone, S; Sioli, M; Sirri, G; Spurio, M; Stanco, L; Stellacci, S; Surdo, A; Tenti, M; Togo, V; Ventura, M; Zago, M

    2012-01-01

    This proposal describes an experimental search for sterile neutrinos beyond the Standard Model with a new CERN-SPS neutrino beam. The experiment is based on two identical LAr-TPC's followed by magnetized spectrometers, observing the electron and muon neutrino events at 1600 and 300 m from the proton target. This project will exploit the ICARUS T600, moved from LNGS to the CERN "Far" position. An additional 1/4 of the T600 detector will be constructed and located in the "Near" position. Two spectrometers will be placed downstream of the two LAr-TPC detectors to greatly complement the physics capabilities. Spectrometers will exploit a classical dipole magnetic field with iron slabs, and a new concept air-magnet, to perform charge identification and muon momentum measurements in a wide energy range over a large transverse area. In the two positions, the radial and energy spectra of the nu_e beam are practically identical. Comparing the two detectors, in absence of oscillations, all cross sections and experimenta...

  10. Studies with a liquid argon time projection chamber. Addressing technological challenges of large-scale detectors

    International Nuclear Information System (INIS)

    Michael Schenk evaluates new technologies and methods, such as cryogenic read-out electronics and a UV laser system, developed to optimise the performance of large liquid argon time projection chambers (LArTPC). Amongst others, the author studies the uniformity of the electric field produced by a Greinacher high-voltage generator operating at cryogenic temperatures, measures the linear energy transfer (LET) of muons and the longitudinal diffusion coefficient of electrons in liquid argon. The results are obtained by analysing events induced by cosmic-ray muons and UV laser beams. The studies are carried out with ARGONTUBE, a prototype LArTPC in operation at the University of Bern, Switzerland, designed to investigate the feasibility of drift distances of up to five metres for electrons in liquid argon.

  11. Beam Test with a GridGEM TPC Prototype Module

    OpenAIRE

    Diener, Ralf; Behnke, Ties; Caiazza, Stefano; Heinze, Isa; Prahl, Volker; Rosemann, Christoph; Schäfer, Oliver; Timmermans, Jan; Volkenborn, Robert; Zenker, Klaus

    2013-01-01

    The International Large Detector (ILD) --a detector concept for the International Linear Collider (ILC)-- foresees a Time Projection Chamber (TPC) as its main tracking detector. Currently, the R&D efforts for such a TPC focus on studies using a large prototype that can accommodate up to seven read-out modules which are comparable to the ones that would be used in the final ILD TPC. The DESY TPC group has developed such a module using GEMs for the gas amplification, which are mounted on thin c...

  12. The influence of detector effects on TPC performance

    Energy Technology Data Exchange (ETDEWEB)

    Christiansen, P. [Division of Experimental High-Energy Physics, Lund University, 22100 Lund (Sweden)], E-mail: peter.christiansen@hep.lu.se; Dobrin, A. [Division of Experimental High-Energy Physics, Lund University, 22100 Lund (Sweden); Gros, P. [Division of Experimental High-Energy Physics, Lund University, 22100 Lund (Sweden)], E-mail: philippe.gros@hep.lu.se; Gustafsson, H.-A. [Division of Experimental High-Energy Physics, Lund University, 22100 Lund (Sweden); Ivanov, M. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Kowalski, M. [Institute of Nuclear Physics, Cracow (Poland); Oskarsson, A.; Osterman, L.; Stenlund, E. [Division of Experimental High-Energy Physics, Lund University, 22100 Lund (Sweden)

    2009-10-11

    TPC stand alone simulations based on different energy loss models are compared to previously reported measurements with an ALICE TPC prototype. The performance obtained from simulations is shown to depend significantly on all the included detector effects stressing that energy loss model calculations alone are inadequate for describing the performance. When all effects are included, a good quantitative description of both the specific energy loss and the space point resolution can be obtained from all models. This shows that the TPC description in the official ALICE TPC simulation is in agreement with the measured test beam data.

  13. A hardware implementation of Region-of-Interest selection in LAr-TPC for data reduction and triggering

    International Nuclear Information System (INIS)

    Large Liquid Argon TPC detectors in the range of multi-kton mass for neutrino and astroparticle physics require the extraction and treatment of signals from some 105 wires. In order to increase the throughput of the DAQ system an on-line lossless data compression has been realized reducing by almost a factor 4 the data flow. Moreover a new efficient on-line identification algorithm of wire hits was studied, implemented on the ICARUS digital read-out boards and fully tested on the ICARINO LAr-TPC facility operated at LNL INFN Laboratory with cosmic-rays. This system permits the extraction of the event Region-of-Interest maximizing the global throughput of the DAQ and the realization of a trigger based on charge deposition on the wires. Capability to trigger isolated low energy events down to few MeV visible energy was also demonstrated.

  14. The Development of a 2000L Liquid Argon Time Projection Chamber and its Application to the Search for Proton Decay

    Science.gov (United States)

    Zhou, Ming

    A new type of particle detector, the liquid argon time projection chamber, is developed and systematically tested using cosmic ray muons with a three ton prototype. The main technical problems, such as the liquid argon purity, wire chamber configuration, low noise electronics, and their long term stability, are solved after two years of run. Most of the basic parameters associated with the liquid argon TPC technology, the charge drift velocity, the spatial resolution, charge recombination and diffusion, are extracted. In order to apply this technique to solar neutrino physics, a measurement of the intrinsive radioactive Ar^{42} was performed and the results are compatible with current limits. An application to the search for proton decay with the liquid argon TPC technique is studied and some preliminary results are reported.

  15. On the electric breakdown in liquid argon at centimeter scale

    Science.gov (United States)

    Auger, M.; Blatter, A.; Ereditato, A.; Goeldi, D.; Janos, S.; Kreslo, I.; Luethi, M.; von Rohr, C. Rudolf; Strauss, T.; Weber, M. S.

    2016-03-01

    We present a study on the dependence of electric breakdown discharge properties on electrode geometry and the breakdown field in liquid argon near its boiling point. The measurements were performed with a spherical cathode and a planar anode at distances ranging from 0.1 mm to 10.0 mm. A detailed study of the time evolution of the breakdown volt-ampere characteristics was performed for the first time. It revealed a slow streamer development phase in the discharge. The results of a spectroscopic study of the visible light emission of the breakdowns complement the measurements. The light emission from the initial phase of the discharge is attributed to electro-luminescence of liquid argon following a current of drifting electrons. These results contribute to set benchmarks for breakdown-safe design of ionization detectors, such as Liquid Argon Time Projection Chambers (LAr TPC).

  16. On the Electric Breakdown in Liquid Argon at Centimeter Scale

    CERN Document Server

    Auger, M; Ereditato, A; Goeldi, D; Janos, S; Kreslo, I; Luethi, M; von Rohr, C Rudolf; Strauss, T; Weber, M S

    2015-01-01

    We present a study on the dependence of electric breakdown discharge parameters on electrode geometry and the breakdown field in liquid argon near its boiling point. The measurements were performed with a spherical cathode and a planar anode at distances ranging from 0.1 mm to 10.0 mm. A detailed study of the time evolution of the breakdown volt-ampere characteristics was performed for the first time. It revealed a slow streamer development phase in the discharge. The results of a spectroscopic study of the visible light emission of the breakdowns complement the measurements. The light emission from the initial phase of the discharge is attributed to electro-luminescence of liquid argon following a current of drifting electrons. These results contribute to set benchmarks for breakdown-safe design of ionization detectors, such as Liquid Argon Time Projection Chambers (LAr TPC).

  17. MicroBooNE and the Road to Large Liquid Argon Neutrino Detectors

    Science.gov (United States)

    Karagiorgi, G.

    Liquid Argon Time Projection Chambers (LArTPC's) provide a promising technology for multi-kiloton scale detectors aiming to address-among other pressing particle physics questions-the possibility of short and long baseline electron neutrino and antineutrino appearance. MicroBooNE, a 170 ton LArTPC under construction, is the next necessary step in a phased R&D effort toward construction and stable operation of larger-scale LArTPC's. This development effort also leans heavily on the ArgoNeuT and LAr1 LArTPC R&D experiments at Fermilab. In addition to advancing the LArTPC technology, these projects also provide unique physics opportunities. For example, Micro-BooNE will be located in the Booster Neutrino Beamline at Fermilab, at ∼470 m from neutrino production. Thus, in addition to measuring a suite of low energy neutrino cross sections on argon, MicroBooNE will investigate the anomalous low energy excess seen by the MiniBooNE experiment. Furthermore, the neutrino beam energy and relatively short baseline provide MicroBooNE with sensitivity to high-∼m2 neutrino oscillations. These proceedings summarize the role of the MicroBooNE detector in the US LArTPC R&D program, present its physics reach, and briefly discuss the physics potential of a dedicated near-future neutrino oscillation program at the Booster Neutrino Beamline, as a way to maximize the physics output of the Fermilab LArTPC R&D projects.

  18. Modular TPC's for relativistic heavy ion experiments

    International Nuclear Information System (INIS)

    We have developed a TPC system for use in relativistic heavy ion experiments that permits the efficient reconstruction of high multiplicity events including events with decay vertices. It operates with the beam through the middle of the chamber giving good efficiency, two-track separation and spatial resolution. The three-dimensional points in this system allow the reconstruction of the complex events of interest. The use of specially developed hybrid electronics allows us to build a compact and cost-effective system. 11 figs

  19. Future prospects of the TPC idea

    International Nuclear Information System (INIS)

    General aspects affecting TPC size, readout plane characteristics and operation in the LEP environment are presented, with the general conclusion that modest improvements relative to PEP-4 can be realized in several areas. The problem of positive ion reduction is discussed according to two qualitatively new operating modes, asynchronous and synchronous gating. Either gating mode appears to offer a means to eliminate almost completely the ion return flux. Some speculative ideas involving 3-component gas mixtures, low-mass components and parallel plane geometry are presented as future possibilities

  20. R&D Argon Detector at Ash River (RADAR) - Letter of Intent

    CERN Document Server

    Adamson, P; Guzowski, P; Habig, A; Holin, A; Huang, J; Kordosky, M; Kreymer, A E; Lang, K; Marshak, M; Mehdiyev, R; Miller, W H; Naples, D; Nichol, R J; Patterson, R B; Sousa, A; Thomas, J; Whitehead, L H

    2013-01-01

    The RADAR project proposes to deploy a 6 kton liquid argon TPC at the NOvA Far Detector building in Ash River, Minnesota, and expose it to the NuMI beam during NOvA running. It will significantly add to the physics capabilities of the NOvA program while providing LBNE with an R&D program based on full-scale TPC module assemblies. RADAR offers an excellent opportunity to improve the full Homestake LBNE project in physics reach, timeline, costs, and fostering international partnership. The anticipated duration of the project's construction is 5 years, with running happening between 2018 and 2023.

  1. A large area Micromegas TPC for tracking at the ILC

    International Nuclear Information System (INIS)

    modules with a Kalman filter algorithm. The results of these studies are given in Chapter 7. The TPC technique has been applied to neutron imaging in collaboration with the University of Lanzhou. A test using a neutron source has been carried out in China. The results are reported in Chapter 8. (author)

  2. A new concept of y-ray telescope. LArGO: Liquid Argon Gamma-ray Observatory

    CERN Document Server

    Caliandro, Giuseppe Andrea; Longo, Francesco; Fiorillo, Giuliana; Labanti, Claudio; Sanchez, Federico; Lux, Thorsten

    2013-01-01

    LArGO (Liquid Argon Gamma-ray Observatory) consists of a new design for a $\\gamma$-ray telescope, which exploits the idea of using a Liquid Argon Time Projection Chamber (LAr-TPC) as tracker-converter. Particle tracking in LAr-TPC can efficiently starts since the primary photon vertex. Indeed, while in the present space telescopes the incident photon converts in a tungsten foil, which is a passive material, in a LAr-TPC this conversion happens in LAr itself, which is fully active. In this proceeding is described a plausible design for the tracker-converter detector which fulfills the constraints on conversion efficiency, angular resolution, and wide field of view. It is demonstrated how this design can provide an unprecedented angular resolution for a $\\gamma$-ray telescope, leading to a significant improvement in sensitivity and most important disclosing the possibility to detect the polarization of $\\gamma$-ray emission.

  3. Inbetriebnahme und Kalibrierung der ALICE-TPC

    CERN Document Server

    Wiechula, Jens

    2008-01-01

    ALICE (A Large Ion Collider Experiment), is the dedicated heavy-ion experiment at the Large Hadron Collider (LHC) at CERN. It is optimised to reconstruct and identify the particles created in a lead-lead collision with a centre of mass energy of 5.5TeV. The main tracking detector is a large-volume time-projection chamber (TPC). With an active volume of about 88m^3 and a total readout area of 32.5m^2 it is the most challenging TPC ever build. A central electrode divides the 5m long detector into two drift regions. Each readout side is subdivided into 18 inner and 18 outer multi-wire proportional read-out chambers. The readout area is subdivide into 557568 pads, where each pad is read out by and electronics chanin. A complex calibration is needed in order to reach the design position-resolution of the reconstructed particle tracks of about 200um. One part of the calibration lies in understanding the electronic-response. The work at hand presents results of the pedestal and noise behaviour of the front-end elect...

  4. Team Primacy Concept (TPC) Based Employee Evaluation and Job Performance

    Science.gov (United States)

    Muniute, Eivina I.; Alfred, Mary V.

    2007-01-01

    This qualitative study explored how employees learn from Team Primacy Concept (TPC) based employee evaluation and how they use the feedback in performing their jobs. TPC based evaluation is a form of multirater evaluation, during which the employee's performance is discussed by one's peers in a face-to-face team setting. The study used Kolb's…

  5. Development of a high rate TPC with GEM readout

    International Nuclear Information System (INIS)

    The concept of a Time Projection Chamber (TPC) for high rate experiments has been developed. A gating grid can not be used to reduce the ion backflow. Gas Electron Multipliers (GEM) combine the requirements of an excellent spatial resolution with an intrinsic suppression of ions. These key features of a GEM allow a TPC to maintain its excellence performance even in an ungated continuous mode. A large GEM TPC prototype with a diameter of 30.8 cm, a drift length of 72.8 cm and 10.000 readout channels has been built and tested within the low rate FOPI experiment at the GSI. The operation at high interaction rates with overlapping events in a single drift frame requires a continuous readout of the TPC including online feature extraction and and data compression. The reconstruction software then has to identify physics and filter out background events. A pattern recognition software has been developed and tested within the PANDA framework to cope with the maximal track density of 0.5 cm/cm3 in the TPC. It provides excellent information about kinked tracks or secondary vertices in the TPC to contribute to an online event selection. The concept of a GEM TPC for high rate applications, first results of the GEM TPC prototype within FOPI as well as an outlook for potential application of this concept in other high rate applications are presented.

  6. An optical readout TPC (O-TPC) for studies in nuclear astrophysics with gamma-ray beams at HI{gamma}S{sup 1}

    Energy Technology Data Exchange (ETDEWEB)

    Gai, M; Zimmerman, W R; Kading, T J; Seo, P-N; Young, A H [LNS at Avery Point, University of Connecticut, Groton, CT 06340-6097 (United States); Ahmed, M W; Stave, S C; Henshaw, S S; Martel, P P; Weller, H R [TUNL, Dept. of Physics, Duke University, Durham, NC 27708 (United States); Breskin, A; Chechik, R [Dept. of Particle Physics, Weizmann Institute of Science, 76100 Rehovot (Israel); Bromberger, B; Dangendorf, V; Tittelmeier, K [Physikalisch-Technische Bundesanstalt, 38116 Braunschweig (Germany); Delbar, Th [Universite Catholique de Louvain, 1348 Louvain-la-Neuve (Belgium); III, R H France [Georgia College and State University, CBX 82, Milledgeville, GA 31061 (United States); McDonald, J E R, E-mail: moshe.gai@yale.edu [Dept. of Physics, Yale University, New Haven, CT 06520-8124 (United States)

    2010-12-15

    We report on the construction, tests, calibrations and commissioning of an Optical Readout Time Projection Chamber (O-TPC) detector operating with a CO{sub 2}(80%) + N{sub 2}(20%) gas mixture at 100 and 150 Torr. It was designed to measure the cross sections of several key nuclear reactions involved in stellar evolution. In particular, a study of the rate of formation of oxygen and carbon during the process of helium burning will be performed by exposing the chamber gas to intense nearly mono-energetic gamma-ray beams at the High Intensity Gamma Source (HI{gamma}S) facility. The O-TPC has a sensitive target-drift volume of 30x30x21 cm{sup 3}. Ionization electrons drift towards a double parallel-grid avalanche multiplier, yielding charge multiplication and light emission. Avalanche-induced photons from N{sub 2} emission are collected, intensified and recorded with a Charge Coupled Device (CCD) camera, providing two-dimensional track images. The event's time projection (third coordinate) and the deposited energy are recorded by photomultipliers and by the TPC charge-signal, respectively. A dedicated VME-based data acquisition system and associated data analysis tools were developed to record and analyze these data. The O-TPC has been tested and calibrated with 3.183 MeV alpha-particles emitted by a {sup 148}Gd source placed within its volume with a measured energy resolution of 3.0%. Tracks of alpha and {sup 12}C particles from the dissociation of {sup 16}O and of three alpha-particles from the dissociation of {sup 12}C have been measured during initial in-beam test experiments performed at the HI{gamma}S facility at Duke University. The full detection system and its performance are described and the results of the preliminary in-beam test experiments are reported.

  7. An optical readout TPC (O-TPC) for studies in nuclear astrophysics with gamma-ray beams at HIγS1

    International Nuclear Information System (INIS)

    We report on the construction, tests, calibrations and commissioning of an Optical Readout Time Projection Chamber (O-TPC) detector operating with a CO2(80%) + N2(20%) gas mixture at 100 and 150 Torr. It was designed to measure the cross sections of several key nuclear reactions involved in stellar evolution. In particular, a study of the rate of formation of oxygen and carbon during the process of helium burning will be performed by exposing the chamber gas to intense nearly mono-energetic gamma-ray beams at the High Intensity Gamma Source (HIγS) facility. The O-TPC has a sensitive target-drift volume of 30x30x21 cm3. Ionization electrons drift towards a double parallel-grid avalanche multiplier, yielding charge multiplication and light emission. Avalanche-induced photons from N2 emission are collected, intensified and recorded with a Charge Coupled Device (CCD) camera, providing two-dimensional track images. The event's time projection (third coordinate) and the deposited energy are recorded by photomultipliers and by the TPC charge-signal, respectively. A dedicated VME-based data acquisition system and associated data analysis tools were developed to record and analyze these data. The O-TPC has been tested and calibrated with 3.183 MeV alpha-particles emitted by a 148Gd source placed within its volume with a measured energy resolution of 3.0%. Tracks of alpha and 12C particles from the dissociation of 16O and of three alpha-particles from the dissociation of 12C have been measured during initial in-beam test experiments performed at the HIγS facility at Duke University. The full detection system and its performance are described and the results of the preliminary in-beam test experiments are reported.

  8. MARLEY: Model of Argon Reaction Low Energy Yields

    Science.gov (United States)

    Gardiner, Steven; Bilton, Kyle; Grant, Christopher; Pantic, Emilija; Svoboda, Robert

    2015-10-01

    Core-collapse supernovae are sources of tremendous numbers of neutrinos with energies of up to about 50 MeV. In recent years, there has been growing interest in building detectors that are sensitive to supernova neutrinos. Such detectors can provide information about the initial stages of stellar collapse, early warning signals for light emission from supernovae, and opportunities to study neutrino oscillation physics over astronomical distances. In an effort to enable supernova neutrino detection in next-generation experiments like DUNE, the CAPTAIN collaboration plans to make the first direct measurement of cross sections for neutrino interactions on argon in the supernova energy regime. To help predict neutrino event signatures in the CAPTAIN liquid argon time projection chamber (LArTPC), we have developed a first-of-its-kind Monte Carlo event generator called MARLEY (Model of Argon Reaction Low Energy Yields). This generator attempts to model the complicated nuclear structure dependence of low-energy neutrino-nucleus reactions in sufficient detail for use in LArTPC simulations. In this talk we present some preliminary results calculated using MARLEY and discuss how the current version of the generator may be improved and expanded.

  9. Tracks in a small slice of the NA49 TPC

    CERN Multimedia

    1996-01-01

    An event display of the data recorder by the six readout chambers of the Vertex TPC. After amplification the drifting ionization is detected in small pads of 3x20 mm (small rectangles in the six readout chambers) at 10 nanosecond intervals. Only a two centimeter slice of the data is projected here while the full depth of the TPC is about 80 cm. A complicated analysis on those data aims into ``reconstructing'' the real trajectories of the charged particles that crossed the TPC.

  10. The design and implementation of TPC encoder and decoder

    Science.gov (United States)

    Xiang, L. J.; Wang, Z. B.; Yuan, J. B.; Zheng, L. H.

    2016-02-01

    Based on the analysis and simulation of TPC codec principle and iteration decoding algorithm based on Chase 2, the design and implementation methods of TPC encoder and decoder are presented in this paper. In particular, circuit design and implementation flow of soft-input soft-output modified method in decoder algorithm and iteration decoding are analyzed. Aiming at (64,57,4) TPC, when the iteration times is 3 and the uncertain position number is 3, simulation and implementation results show that at least 6.8dB encoding gain can be obtained under the condition of BER=10-6

  11. Argon plasma coagulation

    Directory of Open Access Journals (Sweden)

    Zenker, Matthias

    2008-03-01

    Full Text Available Argon Plasma Coagulation (APC is an application of gas discharges in argon in electrosurgery, which is increasingly used especially in endoscopy. The major application fields are haemostasis, tissue devitalization and tissue reduction.This review describes the physics and technology of electrosurgery and APC. Some characteristics of the argon discharge are shown and discussed, and thermal effects in biological tissue are described. Subsequently, examples of medical applications are given.

  12. Liquid Argon Time Projection Chamber research and development in the United States

    International Nuclear Information System (INIS)

    A workshop was held at Fermilab on March 20-21, 2013 to discuss the development of liquid argon time projection chambers (LArTPCs) in the United States. The workshop was organized under the auspices of the Coordinating Panel for Advanced Detectors, a body that was initiated by the American Physical Society Division of Particles and Fields. All presentations at the workshop were made in seven topical plenary sessions: i) Argon Purity, ii) Cryogenics, iii) TPC and High Voltage, iv) Electronics, Data Acquisition and Triggering, v) Scintillation Light Detection, vi) Calibration and Test Beams, and vii) Software. This document summarizes the current efforts in each of these areas. It also highlights areas in LArTPC research and development that are common between neutrino experiments and dark matter experiments

  13. Liquid Argon Time Projection Chamber research and development in the United States

    Science.gov (United States)

    Baller, B.; Bromberg, C.; Buchanan, N.; Cavanna, F.; Chen, H.; Church, E.; Gehman, V.; Greenlee, H.; Guardincerri, E.; Jones, B.; Junk, T.; Katori, T.; Kirby, M.; Lang, K.; Loer, B.; Marchionni, A.; Maruyama, T.; Mauger, C.; Menegolli, A.; Montanari, D.; Mufson, S.; Norris, B.; Pordes, S.; Raaf, J.; Rebel, B.; Sanders, R.; Soderberg, M.; St. John, J.; Strauss, T.; Szelc, A.; Tope, T.; Touramanis, C.; Thorn, C.; Urheim, J.; Van de Water, R.; Wang, H.; Yu, B.; Zuckerbrot, M.

    2014-05-01

    A workshop was held at Fermilab on March 20-21, 2013 to discuss the development of liquid argon time projection chambers (LArTPCs) in the United States. The workshop was organized under the auspices of the Coordinating Panel for Advanced Detectors, a body that was initiated by the American Physical Society Division of Particles and Fields. All presentations at the workshop were made in seven topical plenary sessions: i) Argon Purity, ii) Cryogenics, iii) TPC and High Voltage, iv) Electronics, Data Acquisition and Triggering, v) Scintillation Light Detection, vi) Calibration and Test Beams, and vii) Software. This document summarizes the current efforts in each of these areas. It also highlights areas in LArTPC research and development that are common between neutrino experiments and dark matter experiments.

  14. Some TPC measurements in an oxygen beam at the AGS

    International Nuclear Information System (INIS)

    The principal detector for AGS Experiment 810 is a Time Projection Chamber (TPC) in which it is intended to measure momenta and angles of a major fraction of the charged particles from each light ion collision. This report describes the results of a test of a prototype of the TPC in a beam of (14.6x16=233.6 GeV/c) oxygen ions run in June of this year. (orig.)

  15. Optimization of the resolution of a track drift chamber (TPC)

    International Nuclear Information System (INIS)

    In the framework of this diploma thesis it was studied, how the position resolution of a TPC can be improved. For this first properties like electron drift velocity as well transverse and longitudinal diffusion of different gases in a test TPC were determined. Starting from the measurement results it is possible, to select chamber gases with suitable drift velocity and low diffusion and to improve by this the position resolution of a TPC. The second essential point of approach for the improvement of the position resolution of a TPC was the variation of the TPC geometry. Here the pad width, the gap distance, and the sampling frequency was varied and the influence on the resolution studied. The essential result hereby was the development of a TPC with a gap distance of 1 mm, which reduced the pad response width to 1.4 mm and by this contributed to a distinct improvement of the position resolution. In a last step a gas microstrip chamber with TPC pad readout was designed, in which the amplification wire planes of the TPC were replaced by a microstrip structure on a glass substrae. Hereby the proof-of-principle of such a facility was brought and first measurements on the position resolution and on the time behaviour of the gas amplification performed. Looking out to the future further measurements with this facility, like for example variation of the substrate material, the substrate thickness, or the manufacturing process of the microstrip structure for the improvement of the time stability of the gas amplification and the position resolution would be desirable. (HSI)

  16. TPC Readout Electronics with Time-to-Digital Converters

    CERN Document Server

    Kaukher, Alexander

    2009-01-01

    Development of readout electronics for Time Projection Chamber for a Linear Collider is ongoing under stringent requirements on high channel density, lowest possible power consumption and small material budget. In the studied TPC readout electronics time and charge of TPC signals are measured with the help of Time-to-Digit Converters. Optimization of performance of this electronics is considered and a methodology of signal simulation is presented.

  17. Compression of TPC Data in the ALICE Experiment

    CERN Document Server

    Nicolaucig, A; Carrato, S

    2002-01-01

    In this paper two algorithms for the compression of the data generated by the Time Projection Chamber (TPC) detector of the ALICE experiment at CERN are described. The first algorithm is based on a lossless source code modelling technique, i.e. the original TPC signal information can be reconstructed without errors at the decompression stage. The source model exploits the temporal correlation that is present in the TPC data to reduce the entropy of the source. The second algorithm is based on a source model which is lossy if samples of the TPC signal are considered one by one. Conversely, the source model is lossless or quasi-lossless if some physical quantities that are of main interest for the experiment are considered. These quantities are the area and the location of the center of mass of each TPC signal pulse. Obviously entropy coding is applied to the set of events defined by the two source models to reduce the bit rate to the corresponding source entropy. Using TPC simulated data according to the expec...

  18. RHIC TPC R and D progress and goals

    International Nuclear Information System (INIS)

    The authors have identified eight areas of progress and goals, they are: 1. They have found and tried a method of interconnect that will allow a piggy-back assembly of the several stages of front end electronics described in the proposal. This method also provides interconnect to the TPC pads. The goal is to produce multi-layer printed circuits suitable for mounting the custom IC's for this front end electronics. 2. The have produced the first cathode pad end cap assembly for a test TPC. The goal is to assemble and evaluate the TPC. 3. A gas system has been designed and components ordered. The completion of this gas system will allow a systematic study of gases suitable for a RHIC TPC. 4. They are developing a 3 dimensional electrostatic field simulation software program. 5. A laser system is under study. This laser-multiplier will allow a critical measurement of field distortions in the TPC. 6. They have been in communication with Dave Dorfan at UC Santa Cruz who is developing a 64 channel amplifier IC suitable for their requirements. 7. The collaborators in both this R and D project and the forthcoming RHIC experiment proposal, Kleinfelder and Nygren from LBL, have developed a 16 channel 256 sample analog memory IC that will be used on the HISS TPC. 8. They have designed an IC test facility to evaluate the custom IC's mentioned in items 6 and 7

  19. Development of a GEM-TPC for high rate applications

    International Nuclear Information System (INIS)

    The concept of a Time Projection Chamber (TPC) has to be further developed to be suitable for high rate experiments. The application of a TPC at high interaction rates with overlapping events in a single drift frame requires a continuous readout. Gas Electron Multipliers (GEM) combine the requirements of an excellent spatial resolution and particle identification by measurements of specific energy loss with an intrinsic suppression of ions. These key features of a GEM allow a TPC to maintain its excellence performance even in an ungated continuous mode. A large GEM TPC prototype with an outer diameter of 30.8 cm, an inner diameter of 10.4 cm and a drift length of 72.8 cm and 10.000 readout channels has been built and tested within the low rate FOPI experiment at the GSI. The TPC detector, preliminary performance studies of the GEM TPC prototype within FOPI as well as an outlook for a potential application of this concept are presented.

  20. Muon tomography of rock density using Micromegas-TPC telescope

    Science.gov (United States)

    Hivert, Fanny; Busto, José; Gaffet, Stéphane; Ernenwein, Jean-Pierre; Brunner, Jurgen; Salin, Pierre; Decitre, Jean-Baptiste; Lázaro Roche, Ignacio; Martin, Xavier

    2014-05-01

    The knowledge of the subsurface properties is essentially obtained by geophysical methods, e.g., seismic imaging, electric prospection or gravimetry. The current work is based on a recently developed method to investigate in situ the density of rocks using a measurement of the muon flux, whose attenuation depends on the quantity of matter the particles travel through and hence on the rock density and thickness. The present project (T2DM2) aims at performing underground muon flux measurements in order to characterize spatial and temporal rock massif density variations above the LSBB underground research facility in Rustrel (France). The muon flux will be measured with a new muon telescope device using Micromegas-Time Projection Chamber (TPC) detectors. The first step of the work presented covers the muon flux simulation based on the Gaisser model (Gaisser T., 1990), for the muon flux at the ground level, and on the MUSIC code (Kudryavtsev V. A., 2008) for the propagation of muons through the rock. The results show that the muon flux distortion caused by density variations is enough significant to be observed at 500 m depth for measurement times of about one month. This time-scale is compatible with the duration of the water transfer processes within the unsaturated Karst zone where LSBB is located. The work now focuses on the optimization of the detector layout along the LSBB galleries in order to achieve the best sensitivity.

  1. Analysis and optimization of energy resolution of neutron-TPC

    Institute of Scientific and Technical Information of China (English)

    黄孟; 李玉兰; 牛莉博; 李金; 李元景

    2015-01-01

    Neutron-TPC (nTPC) is a fast neutron spectrometer based on GEM-TPC (Gas Electron Multiplier-Time Pro-jection Chamber) and expected to be used in nuclear physics, nuclear reactor operation monitoring, and thermo-nuclear fusion plasma diagnostics. By measuring the recoiled proton energy and slopes of the proton tracks, the incident neutron energy can be deduced. It has higher n/γseparation ability and higher detection efficiency than conventional neutron spectrometers. In this paper, neutron energy resolution of nTPC is studied using the analytical method. It is found that the neutron energy resolution is determined by 1) the proton energy resolu-tion (σEp/Ep), and 2) standard deviation of slopes of the proton tracks caused by multiple Coulomb scattering (σk(scat ering)) and by the track fitting accuracy (σk(fit)). Suggestions are made for optimizing energy resolution of nTPC. Proper choices of the cut parameters of reconstructed proton scattering angles (θcut), the number of fitting track points (N ), and the working gas help to improve the neutron energy resolution.

  2. Resolution studies of a GEM-based TPC

    International Nuclear Information System (INIS)

    Currently there are four different concept studies trying to optimise the detector for the requirements at the ILC. In three of these detector concepts a time projection chamber (TPC) is foreseen as the main tracking device. To achieve the intended spatial resolution of 100 μm, micro pattern gas detectors (MPGD) are considered for gas amplification. The two different MPGDs discussed for the ILC TPC are Micro-Mesh Gaseous Detectors (Micromegas) and Gas Electron Multiplier foils (GEMs). The current thesis shows resolution studies with a TPC prototype equipped with a triple GEM readout structure. A hodoscope made up of silicon strip sensors gives a precision reference track, allowing an unbiased measurement of the spatial resolution. High statistics measurements have been conducted at the DESY test beam facility, which provides positrons with a tunable energy between 1 GeV and 6 GeV. Using the independent measurement of the hodoscope allows systematic studies of the homogeneity of the TPC's electric field. The fluctuations of the field in the chamber's central region were found to be ΔE/E=8.10-3. Field distortions have been determined and corrected, reducing the remaining deviations to a level well below the spatial resolution of the TPC. One important task is to reduce the number of ions drifting back into the sensitive volume. Special GEM settings with minimised ion backdrift have been examined with respect to their influence on the spatial resolution and it was found that the spatial resolution is not degraded using these special settings. The TPC prototype has been operated in a 4 T magnetic field, provided by a superconducting solenoid located at DESY Hamburg. Again the spatial resolution measured with the ion backdrift optimised settings is compared to that achieved with nonoptimised settings. In both cases the measured resolution is approximately 130 μm. (orig.)

  3. Resolution studies of a GEM-based TPC

    Energy Technology Data Exchange (ETDEWEB)

    Killenberg, M.

    2006-12-15

    Currently there are four different concept studies trying to optimise the detector for the requirements at the ILC. In three of these detector concepts a time projection chamber (TPC) is foreseen as the main tracking device. To achieve the intended spatial resolution of 100 {mu}m, micro pattern gas detectors (MPGD) are considered for gas amplification. The two different MPGDs discussed for the ILC TPC are Micro-Mesh Gaseous Detectors (Micromegas) and Gas Electron Multiplier foils (GEMs). The current thesis shows resolution studies with a TPC prototype equipped with a triple GEM readout structure. A hodoscope made up of silicon strip sensors gives a precision reference track, allowing an unbiased measurement of the spatial resolution. High statistics measurements have been conducted at the DESY test beam facility, which provides positrons with a tunable energy between 1 GeV and 6 GeV. Using the independent measurement of the hodoscope allows systematic studies of the homogeneity of the TPC's electric field. The fluctuations of the field in the chamber's central region were found to be {delta}E/E=8.10{sup -3}. Field distortions have been determined and corrected, reducing the remaining deviations to a level well below the spatial resolution of the TPC. One important task is to reduce the number of ions drifting back into the sensitive volume. Special GEM settings with minimised ion backdrift have been examined with respect to their influence on the spatial resolution and it was found that the spatial resolution is not degraded using these special settings. The TPC prototype has been operated in a 4 T magnetic field, provided by a superconducting solenoid located at DESY Hamburg. Again the spatial resolution measured with the ion backdrift optimised settings is compared to that achieved with nonoptimised settings. In both cases the measured resolution is approximately 130 {mu}m. (orig.)

  4. An Optical Readout TPC (O-TPC) for Studies in Nuclear Astrophysics With Gamma-Ray Beams at HIgS

    CERN Document Server

    Gai, M; Stave, S C; Zimmerman, W R; Breskin, A; Bromberger, B; Chechik, R; Dangendorf, V; Delbar, Th; France, R H; Henshaw, S S; Kading, T J; Martel, P P; McDonald, J E R; Seo, P -N; Tittelmeier, K; Weller, H R; Young, A H; 10.1088/1748-0221/5/12/P12004

    2011-01-01

    We report on the construction, tests, calibrations and commissioning of an Optical Readout Time Projection Chamber (O-TPC) detector operating with a CO2(80%) + N2(20%) gas mixture at 100 and 150 Torr. It was designed to measure the cross sections of several key nuclear reactions involved in stellar evolution. In particular, a study of the rate of formation of oxygen and carbon during the process of helium burning will be performed by exposing the chamber gas to intense nearly mono-energetic gamma-ray beams at the High Intensity Gamma Source (HIgS) facility. The O-TPC has a sensitive target-drift volume of 30x30x21 cm^3. Ionization electrons drift towards a double parallel grid avalanche multiplier, yielding charge multiplication and light emission. Avalanche induced photons from N2 emission are collected, intensified and recorded with a Charge Coupled Device (CCD) camera, providing two-dimensional track images. The event's time projection (third coordinate) and the deposited energy are recorded by photomultip...

  5. B decays studies with the TPC at PEP

    International Nuclear Information System (INIS)

    In the past the TPC/2 photon collaboration at PEP has not been in a position to contribute much to B decay studies because it did not have a good position resolution at the origin. Now that a new Vertex Chamber (VC) has been built and tested, the B-physics program can proceed. Last November, there was a short run at the beam energy of 13.6 GeV. The TPC and VC worked well. With the 300 pb to the minus 1 that is planned in the next 18 months, the B lifetime should be measured with accuracy equal to the present world average. 2 refs., 4 figs

  6. Future Upgrade and Physics Perspectives of the ALICE TPC

    OpenAIRE

    Gunji, Taku; Collaboration, For The ALICE

    2014-01-01

    The ALICE experiment at the Large Hadron Collider (LHC) proposes major detector upgrades to fully exploit the increase of the luminosity of the LHC in RUN~3 and to extend the physics reach for rare probes at low transverse momentum. The Time Projection Chamber (TPC) is one of the main tracking and PID devices in the central barrel of ALICE. The maximum trigger rate of the TPC is currently limited to about 3.5 kHz by the operation of a gating grid system. In order to make full use of the lumin...

  7. Lunar exospheric argon modeling

    Science.gov (United States)

    Grava, Cesare; Chaufray, J.-Y.; Retherford, K. D.; Gladstone, G. R.; Greathouse, T. K.; Hurley, D. M.; Hodges, R. R.; Bayless, A. J.; Cook, J. C.; Stern, S. A.

    2015-07-01

    Argon is one of the few known constituents of the lunar exosphere. The surface-based mass spectrometer Lunar Atmosphere Composition Experiment (LACE) deployed during the Apollo 17 mission first detected argon, and its study is among the subjects of the Lunar Reconnaissance Orbiter (LRO) Lyman Alpha Mapping Project (LAMP) and Lunar Atmospheric and Dust Environment Explorer (LADEE) mission investigations. We performed a detailed Monte Carlo simulation of neutral atomic argon that we use to better understand its transport and storage across the lunar surface. We took into account several loss processes: ionization by solar photons, charge-exchange with solar protons, and cold trapping as computed by recent LRO/Lunar Orbiter Laser Altimeter (LOLA) mapping of Permanently Shaded Regions (PSRs). Recycling of photo-ions and solar radiation acceleration are also considered. We report that (i) contrary to previous assumptions, charge exchange is a loss process as efficient as photo-ionization, (ii) the PSR cold-trapping flux is comparable to the ionization flux (photo-ionization and charge-exchange), and (iii) solar radiation pressure has negligible effect on the argon density, as expected. We determine that the release of 2.6 × 1028 atoms on top of a pre-existing argon exosphere is required to explain the maximum amount of argon measured by LACE. The total number of atoms (1.0 × 1029) corresponds to ∼6700 kg of argon, 30% of which (∼1900 kg) may be stored in the cold traps after 120 days in the absence of space weathering processes. The required population is consistent with the amount of argon that can be released during a High Frequency Teleseismic (HFT) Event, i.e. a big, rare and localized moonquake, although we show that LACE could not distinguish between a localized and a global event. The density of argon measured at the time of LACE appears to have originated from no less than four such episodic events. Finally, we show that the extent of the PSRs that trap

  8. Prototype of the ALICE Time Projection Chamber (TPC) Field-Cage

    CERN Multimedia

    2003-01-01

    The ALICE Time Projection Chamber (TPC) is the main particle tracking detector in ALICE. Charged particles crossing the gas of the TPC knock electons out of their atoms, which then drift in in the electric field. By measuring the arrival of electrons at the end of the chamber, the TPC will reconstruct the paths of the original charged particles.

  9. Depleted Argon from Underground Sources

    International Nuclear Information System (INIS)

    Argon is a strong scintillator and an ideal target for Dark Matter detection; however 39Ar contamination in atmospheric argon from cosmic ray interactions limits the size of liquid argon dark matter detectors due to pile-up. Argon from deep underground is depleted in 39Ar due to the cosmic ray shielding of the earth. In Cortez, Colorado, a CO2 well has been discovered to contain approximately 600 ppm of argon as a contamination in the CO2. We first concentrate the argon locally to 3% in an Ar, N2, and He mixture, from the CO2 through chromatographic gas separation, and then the N2 and He will be removed by continuous distillation to purify the argon. We have collected 26 kg of argon from the CO2 facility and a cryogenic distillation column is under construction at Fermilab to further purify the argon.

  10. Magnetic field map for a large TPC prototype

    International Nuclear Information System (INIS)

    A new e+e- linear collider with an energy of up to 1000 GeV is currently being planned: the International Linear Collider (ILC). It will allow high precision measurements of the Higgs boson and physics beyond the Standard Model. In the Large Detector Concept (LDC) -which is one of the proposed detector concepts for the ILC- a Time Projection Chamber (TPC) is intended as the main tracking device. Within the EUDET project a large TPC prototype is currently being built as an infrastructure to test different gas amplification and readout technologies. The prototype will be operated in a 1T superconducting solenoid magnet -the PCMAG- at the DESY testbeam area. In order to reach the best possible track reconstruction the magnetic field has to be known very precisely throughout the TPC volume. The magnetic field of PCMAG has been measured in July 2007. In this work the creation of a high precision field map from the measurements is presented. The magnet and modelling techniques for its magnetic field are described. A model of the magnet has been created as a best fit from the measurements and its limitations are investigated. The field map will be included in the reconstruction software for the TPC prototype. (orig.)

  11. First results from the ALICE GEM TPC prototype test

    International Nuclear Information System (INIS)

    A large Time Projection Chamber (TPC) is the main device for tracking and charged particle identification in the ALICE experiment at the CERN LHC. After the second long shutdown in 2018, the LHC will deliver Pb beams colliding at an interaction rate of about 50 kHz, which is about a factor of 100 above the present readout rate of the TPC. In order to make full use of this luminosity, a major upgrade of the TPC is required. It is foreseen to replace the existing MWPC-based readout with Gas Electron Multiplier (GEM) foils. A GEM TPC can exploit the intrinsic suppression of back-drifting ions from the amplification stage to reduce the problem of drift-field distortions in an ungated operation. The latter is essential for a continuous readout required for all central detectors of ALICE after the upgrade. A prototype of an ALICE Inner Read-Out Chamber (IROC) was equipped with three large-size GEM foils as amplification stage to demonstrate the feasibility of this solution. The GEM IROC was installed within a test field cage with a drift length of 115 mm and commissioned with radioactive sources. The dE/dx resolution of the prototype was evaluated in a test beam campaign using protons, pions and electrons (1 to 6 GeV/c) at the CERN PS. Preliminary results from these measurements are discussed in this contribution.

  12. Beam test of a GEM-TPC prototype

    International Nuclear Information System (INIS)

    A Time Projection Chamber (TPC) with a GEM-based read out is one option for the central tracker of PANDA at the Facility for Antiproton and Ion Research (FAIR) in Darmstadt. A TPC offers very good momentum resolution and the ability to do particle ID using precise energy-loss measurements. The suppression of ion backflow intrinsic to GEM-based amplification allows us to operate the TPC an ungated, continuous mode, as required by the quasi-continuous beam in the HESR. To show the feasibility of such a detector a prototype with a drift length of 725 mm and an outer radius of 300 mm has been built. The pad plane of the detector has 10254 hexagonal read out pads which are read out using 42 front end cards based on the AFTER-T2K chip. A gas mixture of Ar/CO2 (90/10) was used together with different drift fields ranging from 150 to 350 (V)/(cm). The GEM-TPC was installed and tested in the FOPI spectrometer at GSI (Darmstadt, Germany) with a 2 %X0 Al target being hit by heavy ion beams of Kr at 1.2 AGeV and Au at 1.0 AGeV, respectively. A detailed overview of the detector hardware as well as first experimental data from the beam test is presented.

  13. Magnetic field map for a large TPC prototype

    Energy Technology Data Exchange (ETDEWEB)

    Grefe, Christian

    2008-12-15

    A new e{sup +}e{sup -} linear collider with an energy of up to 1000 GeV is currently being planned: the International Linear Collider (ILC). It will allow high precision measurements of the Higgs boson and physics beyond the Standard Model. In the Large Detector Concept (LDC) -which is one of the proposed detector concepts for the ILC- a Time Projection Chamber (TPC) is intended as the main tracking device. Within the EUDET project a large TPC prototype is currently being built as an infrastructure to test different gas amplification and readout technologies. The prototype will be operated in a 1T superconducting solenoid magnet -the PCMAG- at the DESY testbeam area. In order to reach the best possible track reconstruction the magnetic field has to be known very precisely throughout the TPC volume. The magnetic field of PCMAG has been measured in July 2007. In this work the creation of a high precision field map from the measurements is presented. The magnet and modelling techniques for its magnetic field are described. A model of the magnet has been created as a best fit from the measurements and its limitations are investigated. The field map will be included in the reconstruction software for the TPC prototype. (orig.)

  14. Performance of a liquid argon time projection chamber exposed to the CERN West Area Neutrino Facility neutrino beam

    International Nuclear Information System (INIS)

    We present the results of the first exposure of a Liquid Argon TPC to a multi-GeV neutrino beam. The data have been collected with a 50 liters ICARUS-like chamber located between the CHORUS and NOMAD experiments at the CERN West Area Neutrino Facility (WANF). We discuss both the instrumental performance of the detector and its capability to identify and reconstruct low-multiplicity neutrino interactions

  15. Measurement of 1.7 to 74 MeV polarised gamma rays with the HARPO TPC

    CERN Document Server

    Geerebaert, Y; Amano, S; Attié, D; Bernard, D; Bruel, P; Calvet, D; Colas, P; Daté, S; Delbart, A; Frotin, M; Giebels, B; Götz, D; Hashimoto, S; Horan, D; Kotaka, T; Louzir, M; Minamiyama, Y; Miyamoto, S; Ohkuma, H; Poilleux, P; Semeniouk, I; Sizun, P; Takemoto, A; Yamaguchi, M; Wang, S

    2016-01-01

    Current {\\gamma}-ray telescopes based on photon conversions to electron-positron pairs, such as Fermi, use tungsten converters. They suffer of limited angular resolution at low energies, and their sensitivity drops below 1 GeV. The low multiple scattering in a gaseous detector gives access to higher angular resolution in the MeV-GeV range, and to the linear polarisation of the photons through the azimuthal angle of the electron-positron pair. HARPO is an R&D program to characterise the operation of a TPC (Time Projection Chamber) as a high angular-resolution and sensitivity telescope and polarimeter for {\\gamma} rays from cosmic sources. It represents a first step towards a future space instrument. A 30 cm cubic TPC demonstrator was built, and filled with 2 bar argon-based gas. It was put in a polarised {\\gamma}-ray beam at the NewSUBARU accelerator in Japan in November 2014. Data were taken at different photon energies from 1.7 MeV to 74 MeV, and with different polarisation configurations. The electronic...

  16. Development of a GEM-based TPC for PANDA

    International Nuclear Information System (INIS)

    A Time Projection Chamber (TPC) is a very promising option for the central tracker of the PANDA experiment at the new Facility for Antiproton and Ion Research (FAIR) at Darmstadt, Germany. Installed in a ring-type experiment with 2x107 p anti p annihilations per second it has to be operated continuously despite the presence of space charge effects. These are kept at a bearable level using GEM-based amplification providing an intrinsic suppression of ion backflow. The system promises high-accuracy tracking as well as information on the specific energy-loss and features high momentum resolution of 1% as well as particle-identification capability with a highly homogeneous and low material budget. A test TPC with an active volume of 8 cm length and a diameter of 20 cm was operated in 2009 at the test-bench of the CB-ELSA experiment in Bonn. It served to investigate some of the relevant design features, the electronic foreseen for the readout as well as the analysis procedures. A large-volume TPC with a drift length of 70 cm and an active diameter of 30 cm is being built in parallel. Due to its very similar design it serves as a precursor prototype of a PANDA TPC. This detector is installed and employed within both the FOPI spectrometer at GSI and the Crystal-Barrel experiment at ELSA in Bonn. In this talk, we present the status of the project; report on the results obtained with the test detector as well as the design and construction of the GEM-TPC prototype.

  17. Stellar Helium Burning Studied with an Optical Readout TPC (O-TPC) at HIγS

    International Nuclear Information System (INIS)

    An Optical Readout Time Projection Chamber (O-TPC) operating with the gas mixture of CO2(80%) + N2(20%) at 100 torr with gamma beams from the HIγS facility of TUNL at Duke University were used to study the formation of carbon and oxygen during helium burning. Measurements were carried out with circularly polarized gamma-ray beams at energies: Eγ = 9.08, 9.38, 9.58, 9.78, 10.08, 10.38 and 10.68 MeV. We have begun the process of extracting complete angular distributions for the 16O(γ,α)12C reaction and the 12C(γ,3α) reaction (eventually with energy bins of approximately 100 keV) in order to determine the values of SE1, SE2 and the mixing phase φ12 of the 16O(γ, α)12C reaction. The rate of carbon formation at high temperatures (T > 3 GK) was suggested to increase due to contributions from a higher lying 2+ state. We have measured an angular distribution of (essentially) pure E2 transition at Eγ = 9.78 MeV of the 12C(γ, 3α) reaction, providing conclusive evidence for the elusive 2+2 state in 12C.

  18. Studies in Nuclear Astrophysics with an Optical Readout TPC (O-TPC) at HIγS

    International Nuclear Information System (INIS)

    An Optical Readout Time Projection Chamber (O-TPC) operating with the gas mixture of CO2(80%) + N2(20%) at 100 torr with gamma beams from the HIγS facility of TUNL at Duke University were used to study the formation of carbon and oxygen during helium burning. Measurements were carried out with circularly polarized gamma-ray beams at energies: Eγ = 9.08, 9.38, 9.58, 9.78, 10.08, 10.38 and 10.68 MeV. We have begun the process of extracting complete angular distributions for the 16O(γ, α)12C reaction and the 12C(γ, 3α) reaction (eventually with energy bins of approximately 100 keV) in order to determine the values of SE1, SE2 and the mixing phase φ12 of the 16O(γ, α)12C reaction. The rate of carbon formation at high temperatures (T > 3 GK) was suggested to increase due to contributions from a higher lying 2+ state. We have measured an angular distribution of (essentially) pure E2 transition at Eγ = 9.78 MeV of the 12C(γ, 3α) reaction, providing conclusive evidence for the elusive 2+2 state in 12C.

  19. Argon in action

    CERN Multimedia

    Corinne Pralavorio

    2015-01-01

    Over the past few days, the SPS has been accelerating argon ions, which have started to be sent to the NA61/SHINE experiment. This operating mode, using a new type of ion, required a number of modifications to the accelerator.   Picture 1: a “super-cycle” of the SPS, featuring a proton cycle for the LHC, followed by an argon ion cycle for the North Area. Today, the accelerators are once again juggling particles and even performing completely new tricks. The SPS is supplying beams of argon ions for the first time, at energies never before achieved for this type of beam. They are destined for the NA61/SHINE experiment (see box) located in the North Area, which began receiving the beams on 11 February. Argon ions have a relatively large mass, as they consist of 40 nucleons, so they can be used in a similar way to lead ions. The main difficulty in accelerating them lies in the SPS, where the variation in acceleration frequency is limited. “The SPS was designed for a...

  20. Thermophysical properties of argon

    Energy Technology Data Exchange (ETDEWEB)

    Jaques, A.

    1988-02-01

    The entire report consists of tables of thermodynamic properties (including sound velocity, thermal conductivity and diffusivity, Prandtl number, density) of argon at 86 to 400/degree/K, in the form of isobars over 0.9 to 100 bars. (DLC)

  1. Micromegas-TPC development for rare event detection

    Energy Technology Data Exchange (ETDEWEB)

    Ounalli, L; Vuilleumier, J-M; Schenker, D; Vuilleumier, J-L [Department of Corpuscular Physics, University of Neuchatel, A.-L Breguet 1 (Switzerland)

    2007-04-15

    We present some important results related to Micromegas-TPC development for rare event detection: First, we show the influence of the detection plane structure on the energy resolution, where, replacing the wires planes (MWPC) by the Micromegas micropattern, gave a high collection efficiency with good uniformity and good energy resolution. Second, we prove that the increase of the height of the amplification zone permits a good charge collection at higher gas pressure. Third, we present a new gas mixture 'Xe(98)CF{sub 4}(2)', which is convenient for the search of neutrinoless double beta decay in {sup 136}Xe. Fourth, large size Micromegas, with 50 cm of diameter is operated in the Gotthard-TPC (200 l) and showed high efficiency and good energy resolution with low energy sources.

  2. Commissioning and calibration of the ALICE-TPC

    International Nuclear Information System (INIS)

    ALICE (A Large Ion Collider Experiment), is the dedicated heavy-ion experiment at the Large Hadron Collider (LHC) at CERN. It is optimised to reconstruct and identify the particles created in a lead-lead collision with a centre of mass energy of 5.5 TeV. The main tracking detector is a large-volume time-projection chamber (TPC). With an active volume of about 88m3 and a total readout area of 32.5 m2 it is the most challenging TPC ever build. A central electrode divides the 5 m long detector into two drift regions. Each readout side is subdivided into 18 inner and 18 outer multi-wire proportional read-out chambers. The readout area is subdivided into 557568 pads, where each pad is read out by an electronic chain. A complex calibration is needed in order to reach the design position-resolution of the reconstructed particle tracks of about 200 μm. The work at hand presents results of the pedestal and noise behaviour of the front-end electronics (FEE), measurements of the pulse-shaping properties of the FEE using results obtained with a calibration pulser and measurements performed with the laser-calibration system. The data concerned were taken during two phases of the TPC commissioning. First measurements were performed in the clean room where the TPC was built. After the TPC was moved underground and built into the experiment, a second round of commissioning took place. Noise measurements in the clean room revealed a very large fraction of pads with noise values larger than the design specifications. Two modifications helped to reduce the 'ground bounce' effect: A desynchronisation in the the start of the readout of groups of channels and a modification in the grounding scheme of the FEE. Further noise measurements were carried out after the TPC has been moved to the experimental area underground. Here even a larger fraction of channels showed too large noise values. To study the shaping properties of the FEE a calibration pulser was used. To generate signals in

  3. NEXT: Neutrino Experiment with high pressure Xenon gas TPC

    Energy Technology Data Exchange (ETDEWEB)

    Yahlali, Nadia, E-mail: Nadia.Yahlali@ific.uv.e [Instituto de Fisica Corpuscular (Centro mixto UV-CSIC), Apdo. de Correos 22085, E-46071 Valencia (Spain); Ball, M.; Carcel, S.; Diaz, J.; Gil, A.; Gomez Cadenas, J.J.; Martin-Albo, J.; Monrabal, F.; Serra, L.; Sorel, M. [Instituto de Fisica Corpuscular (Centro mixto UV-CSIC), Apdo. de Correos 22085, E-46071 Valencia (Spain)

    2010-05-21

    The search of the neutrinoless double-{beta} decay address the major Physics goals of revealing the nature of the neutrino and setting an absolute scale for its mass. The observation of a positive {beta}{beta}{sup 0{nu}}signal, the unique signature of Majorana neutrinos, would have deep consequences in particle physics and cosmology. Therefore, any claim of observing a positive signal shall require extremely robust evidences. NEXT is a new double-{beta} experiment which aims at building a 100 kg high pressure {sup 136}Xe gas TPC, to be hosted in the Canfranc Underground Laboratory (LSC), in Spain. This paper address the novel design concept of NEXT TPC believed to provide a pathway for an optimized and robust double-{beta} experiment.

  4. The iTPC upgrade for BES-II

    Science.gov (United States)

    Videbaek, Flemming; STAR Collaboration

    2015-10-01

    STAR has proposed to upgrade the inner sectors of the STAR TPC to increase the segmentation on the inner padplane and to renew the inner sector wires. The upgrade will provide better momentum resolution, better dE/dx resolution and, most importantly, it will provide improved acceptance at high rapidity to | η| compared to the current TPC configuration of | η| energy trends that only appear near the edge of the current STAR acceptance. In the area of dielectron measurements it reduces hadron contamination from a dominant source of uncertainty to an expected statistical uncertainty of only 10%, and will enable significantly improved understanding of in-medium modifications. In this talk I will discuss the physics impact and give a technical overview of the detector upgrade. This work was supported in part by the Office of Nuclear Physics within the U.S. DOE Office of Science.

  5. ARIADNE, a Photographic LAr TPC at the CERN Neutrino Platform

    CERN Document Server

    Mavrokoridis, K; Nessi, M; Roberts, A; Smith, N A; Touramanis, C; CERN. Geneva. SPS and PS Experiments Committee; SPSC

    2016-01-01

    This letter of intent describes a novel and innovative two-phase LAr TPC with photographic capabilities as an attractive alternative readout method to the currently accepted segmented THGEMs which will require many thousands of charge readout channels for kton-scale two-phase TPCs. These colossal LAr TPCs will be used for the future long-baseline-neutrino-oscillation experiments. Optical readout also presents many other clear advantages over current readout techniques such as ease of scalability, upgrade, installation and maintenance, and cost effectiveness. This technology has already been demonstrated at the Liverpool LAr facility with the photographic capturing of cosmic muon tracks and single gammas using a 40-litre prototype. We have now secured ERC funding to develop this further with the ARIADNE programme. ARIADNE will be a 1-ton two-phase LAr TPC utilizing THGEM and EMCCD camera readouts in order to photograph interactions, allowing for track reconstruction and particle identification. We are request...

  6. Fast algorithm of track reconstruction for the Delphy TPC

    International Nuclear Information System (INIS)

    We describe a simple geometrical method (polar inversion) to reconstruct tracks. When the magnetic field is constant in magnitude and direction. This method uses geometrical properties of the trajectories. In the case of the DELPHI apparatus, the track reconstruction is done using TPC informations. After explaining the algorithm, we give results on ''GEANT'' simulated events using the ''Lund'' generator. Today we get a computer time of the order of 1.2 milliseconds on a CDC 7600 and an efficiency of 98%

  7. Pattern recognition for the PANDA GEM-TPC

    International Nuclear Information System (INIS)

    The PANDA fixed target experiment at the future FAIR facility in Darmstadt, Germany, will investigate fundamental questions of non-perturbative QCD. It will make use of a cooled, continuous antiproton beam (impinging on a hydrogen target) with momenta from 1.5 to 15 GeV/c, reaching a anti pp-annihilation rate of 2.107s-1. One option for the central tracker of the target spectrometer is a cylindrical, ungated, continuously running Time Projection Chamber (TPC) with GEM-based gas amplification stage. The chamber is designed to be 150 cm long with an outer radius of 41.5 cm and will be read out by ∝100.000 pickup electrodes. In this setup, several thousand tracks will be stored inside the TPC volume at any given time, leading to sustained data rates of ∝50 GB s-1 in the TPC alone. On top of such technical challenges, PANDA is designed to run without a 1st-level hardware trigger, making powerful online data processing indispensable. Most importantly, in order to filter out interesting signatures from the purely time-stamped track data and associate information from different detectors uniquely to distinct physics events, fast and efficient online pattern recognition methods will play a central role. Several methods, which are presently being studied - testing them on simulated data as well as data recently taken with a large GEM-TPC prototype (over 10.000 readout channels) - are discussed, complemented by first results from simulated and real events.

  8. Investigation of GEM space point resolution for a TPC tracker

    International Nuclear Information System (INIS)

    The Gas Electron Multiplier (GEM) is a leading candidate for the readout of the Time Projection Chamber (TPC) at a future linear collider detector. This presentation describes measurements of the space point resolution of a GEM with relatively large hexagonal pads. Resolution of approximately 50 μm is achieved for 4.5 keV x-rays with two independent methods, using charge sharing and using induction signals

  9. Fission cross section uncertainties with the NIFFTE TPC

    Science.gov (United States)

    Sangiorgio, Samuele; Niffte Collaboration

    2014-09-01

    Nuclear data such as neutron-induced fission cross sections play a fundamental role in nuclear energy and defense applications. In recent years, understanding of these systems has become increasingly dependent upon advanced simulation and modeling, where uncertainties in nuclear data propagate in the expected performances of existing and future systems. It is important therefore that uncertainties in nuclear data are minimized and fully understood. For this reason, the Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) uses a Time Projection Chamber (TPC) to measure energy-differential (n,f) cross sections with unprecedented precision. The presentation will discuss how the capabilities of the NIFFTE TPC allow to directly measures systematic uncertainties in fission cross sections, in particular for what concerns fission-fragment identification, and target and beam uniformity. Preliminary results from recent analysis of 238U/235U and 239Pu/235U data collected with the TPC will be presented. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  10. Cellular automaton based track reconstruction in the STAR TPC

    International Nuclear Information System (INIS)

    STAR is an active collider heavy-ion experiment at RHIC/BNL (Upton, USA). The main tracking detector of the experiment is a Time Projection Chamber (TPC). For future collision rates of up to 1 kHz STAR experiment requires a fast track reconstruction procedure, which can deal with high track densities (up to 10-20 thousands tracks). The Cellular Automaton (CA) algorithm is based on local reconstruction and therefore is robust, fast and easily parallelized, that makes it perfectly suitable for the task under consideration. The algorithm has been implemented by adaptation of the Alice HLT TPC CA track finder for the STAR TPC detector. The efficiency, speed and robustness have been increased. The algorithm is highly parallelized on both data (uses SIMD instruction set) and task (uses Threading Building Blocks technology) levels. The memory usage in the algorithm is optimized as well. Tests with Au-Au at 200 AGeV real data events have been performed. It has been shown that event reconstruction procedure with the CA based track finder demonstrates better track reconstruction efficiency by 9% with respect to the previous scalar version based on track following with Kalman Filter. CA based track finder takes only 10% of event reconstruction procedure.

  11. A continuous read-out TPC for the ALICE upgrade

    Science.gov (United States)

    Lippmann, C.

    2016-07-01

    The largest gaseous Time Projection Chamber (TPC) in the world, the ALICE TPC, will be upgraded based on Micro Pattern Gas Detector technology during the second long shutdown of the CERN Large Hadron Collider in 2018/19. The upgraded detector will operate continuously without the use of a triggered gating grid. It will thus be able to read all minimum bias Pb-Pb events that the LHC will deliver at the anticipated peak interaction rate of 50 kHz for the high luminosity heavy-ion era. New read-out electronics will send the continuous data stream to a new online farm at rates up to 1 TByte/s. A fractional ion feedback of below 1% is required to keep distortions due to space charge in the TPC drift volume at a tolerable level. The new read-out chambers will consist of quadruple stacks of Gas Electron Multipliers (GEM), combining GEM foils with a different hole pitch. Other key requirements such as energy resolution and operational stability have to be met as well. A careful optimisation of the performance in terms of all these parameters was achieved during an extensive R&D program. A working point well within the design specifications was identified with an ion backflow of 0.63%, a local energy resolution of 11.3% (sigma) and a discharge probability comparable to that of standard triple GEM detectors.

  12. The commissioning of the O-TPC at TUNL

    Science.gov (United States)

    Seo, P.-N.; Ahmed, M. W.; Clinton, E. R.; Howell, C. R.; Stave, S. C.; Weller, H. R.; Young, A. H.; Gai, M.; Bromberger, B.; Dangendorf, V.; Tittelmeier, K.

    2008-04-01

    We are commissioning the Optical Readout Time Projection Chamber (O-TPC) that will be used in an experiment at the HIgS facility at TUNL for studying oxygen formation during stellar helium burning by studying the time reversed ^16O(,)^12C reaction. The initial calibration of the O-TPC was carried out at the LNS at Avery Point with a CMAC based data acquisition system. The tests at TUNL used a VME based data acquisition system that also controls a CCD camera. Under stable conditions an energy resolution as good as 2.6% was measured for the charge signal and single and double tracks of alpha particles from a ^148Gd source were recorded in the CCD camera. These tracks were analyzed using an automated pattern recognition algorithm that allows us to extract that track centroid (from which the scattering angle is deduced) as well as DE/DX along the track. The azimuthal angle of the track is deduced from the Time Projection. The O-TPC is found to be ready for accepting beams from the HIgS facility.

  13. The Readout Control Unit of the ALICE TPC

    CERN Document Server

    Lien, J A

    2004-01-01

    The ALICE Time Projection Chamber (TPC) is the main tracking detector of the central barrel of the ALICE (A Large Ion Collider) Experiment at the Large Hadron Collider (LHC), being constructed at CERN, Geneva. It is a 88 m$^{3}$ cylinder filled with gas and divided into two drift regions by the central electrode located at its axial center. The readout chambers of the TPC are multi-wire proportional chambers with cathode pad readout. About 570 000 pads are read-out by an electronics chain of amplification, digitalization and pre-processing. One of the challenges in designing the TPC for ALICE is the design of Front End Electronics (FEE) to cope with the data rates and the channel occupancy. The Readout Control Unit (RCU), which is presented in this work, is designed to control and monitor the Front End Electronics, and to collect and ship data to the High Level Trigger and the Data Acquisition System, via the Detector Data Link (DDL - optical fibre). The RCU must be capable of reading out up to 200 Mbytes/s f...

  14. AGS silicon gold collisions measured in the E-810 TPC

    International Nuclear Information System (INIS)

    The tracking detector of AGS Experiment 810 is a three-piece Time Projection Chamber (TPC) intended to measure all charged tracks in the forward hemisphere of the nucleon-nucleon center of mass system, i.e. forward of an angle of about 20 degrees in the lab. Each module of the TPC contains twelve rows of short anode wires which give 3-D space points on each track, but no dE/dx information useable for particle identification. The TPC was operated in a beam of silicon ions at the end of June 1989 and this talk reports the results of analysis of the data taken with a thin gold target in that run. The authors have gathered a similar amount of data from thin copper and silicon targets, the analysis of which is in a less advanced state. The results of the investigation of the neutral strange particle decays appear in a separate contribution by Al Saulys. This paper presents the current state of the analysis of the charged tracks from the silicon gold collisions

  15. Future Upgrade and Physics Perspectives of the ALICE TPC

    CERN Document Server

    Gunji, Taku

    2014-01-01

    The ALICE experiment at the Large Hadron Collider (LHC) proposes major detector upgrades to fully exploit the increase of the luminosity of the LHC in RUN~3 and to extend the physics reach for rare probes at low transverse momentum. The Time Projection Chamber (TPC) is one of the main tracking and PID devices in the central barrel of ALICE. The maximum trigger rate of the TPC is currently limited to about 3.5 kHz by the operation of a gating grid system. In order to make full use of the luminosity in RUN 3, the TPC is foreseen to be operated in an ungated mode with continuous readout. The existing MWPC readout will be replaced by a Micro-Pattern Gaseous Detector (MPGD) based readout, which provides intrinsic ion capture capability without gating. Extensive detector R\\&D employing Gas Electron Multiplier (GEM) and Micro-Mesh Gaseous detector (Micromegas) technologies, and simulation studies to advance the techniques for the corrections of space-charge distortions have been performed since 2012. In this pap...

  16. Readout system of TPC/MPD NICA project

    Energy Technology Data Exchange (ETDEWEB)

    Averyanov, A. V.; Bajajin, A. G.; Chepurnov, V. F.; Cheremukhina, G. A.; Fateev, O. V.; Korotkova, A. M.; Levchanovskiy, F. V.; Lukstins, J.; Movchan, S. A.; Razin, S. V.; Rybakov, A. A.; Vereschagin, S. V., E-mail: vereschagin@jinr.ru; Zanevsky, Yu. V.; Zaporozhets, S. A.; Zruyev, V. N. [Joint Institute for Nuclear Research (Russian Federation)

    2015-12-15

    The time-projection chamber (TPC) is the main tracking detector in the MPD/NICA. The information on charge-particle tracks in the TPC is registered by the MWPG with cathode pad readout. The frontend electronics (FEE) are developed with use of modern technologies such as application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), and data transfer to a concentrator via a fast optical interface. The main parameters of the FEE are as follows: total number of channels, ∼95 000; data stream from the whole TPC, 5 GB/s; low power consumption, less than 100 mW/ch; signal to noise ratio (S/N), 30; equivalent noise charge (ENC), <1000e{sup –} (C{sub in} = 10–20 pF); and zero suppression (pad signal rejection ∼90%). The article presents the status of the readout chamber construction and the data acquisition system. The results of testing FEE prototypes are presented.

  17. Development of gem based detector for ALICE TPC

    International Nuclear Information System (INIS)

    The goal of A Large Ion Collider Experiment (ALICE) at Large Hadron Collider (LHC) is to study matter at highly extreme condition. The main detector of ALICE experiment is Time Projection Chamber (TPC), which is used for charged particle tracking and identification. The present ALICE TPC readout is based on Multi Wire Proportional Chamber (MWPC). The readout chambers are operated with an active bipolar Gating Grid (GG), which, in the presence of a trigger, switches to transparent mode to allow the ionization electrons to pass into the amplification region. However, operation of the TPC at high interaction rate (50 kHz) cannot be accomplished with an active ion-gating scheme. The back-drifting ions from the amplification region of a MWPC without gate will lead to excessive ion charge densities and drift distortions that render precise space-point measurements impossible. Therefore there is a proposal to replace existing MWPC-based readout chambers by a multi-stage GEM system

  18. Triple-GEM detector for the readout of a TPC

    International Nuclear Information System (INIS)

    A time-projection-chamber (TPC) allows to do a full 3D track reconstruction in combination with a precise energy-loss measurement for particle identification. Up to now it was not possible to operate a TPC in a continuous mode due to back drifting secondary ions from the amplification stage. This can be overcome by using GEM foils for the amplification, exploiting the intrinsic ion back flow suppression of the GEM foils. A continuous read-out TPC is one option for the inner tracker of the future anti PANDA spectrometer which will be built at the new FAIR facility rate at GSI (Darmstadt, Germany). To check the operation of this solution a prototype detector of 300 mm diameter and a drift length of 725 mm with the GEM stack and readout detachable from the fieldcage was build. Tests for the commissioning of the GEM stack with an analog readout and an Fe55 source have been done. For the read-out of the GEM stack front-end electronics based on the AFTER/T2K chip were developed. The detector description, results of the GEM stack evaluation, front-end noise properties and some first experimental results achieved under realistic beam conditions within FOPI rate at GSI are presented in this contribution.

  19. Particle identification with a large GEM-TPC

    International Nuclear Information System (INIS)

    A Time Projection Chamber (TPC) with its low material budget constitutes an almost ideal device for 3-dimensional tracking of charged particles. The employment of Gas Electron Multiplier (GEM) foils for gas amplification promises to remedy the former limitation of TPCs to low-rate experiments: The intrinsic ion backflow suppression features of GEMs make traditional gating structures dispensable and thus open the possibility of a continuous operation of TPCs even in high-rate environments. A large prototype (75 cm length, 15 cm radius) of such a GEM-TPC with ∝10000 readout channels has been built and successfully used in a physics campaign (π-beam on different targets) at the FOPI experiment at GSI, Darmstadt. From the recorded data, charged particle tracks entering the GEM-TPC are reconstructed using a fully 3-dimensional clustering algorithm and then matched with the surrounding FOPI tracking detectors. In this talk we present a first analysis of the specific energy loss (dE/dx) of Pions, Kaons and Protons as a function of the particle momentum. Energy loss resolutions as well as separation power for particle identification are discussed.

  20. A measurement of the absorption of liquid argon scintillation light by dissolved nitrogen at the part-per-million level

    Science.gov (United States)

    Jones, B. J. P.; Chiu, C. S.; Conrad, J. M.; Ignarra, C. M.; Katori, T.; Toups, M.

    2013-07-01

    We report on a measurement of the absorption length of scintillation light in liquid argon due to dissolved nitrogen at the part-per-million (ppm) level. We inject controlled quantities of nitrogen into a high purity volume of liquid argon and monitor the light yield from an alpha source. The source is placed at different distances from a cryogenic photomultiplier tube assembly. By comparing the light yield from each position we extract the absorption cross section of nitrogen. We find that nitrogen absorbs argon scintillation light with strength of (1.51±0.15) × 10-4 cm-1ppm-1, corresponding to an absorption cross section of (4.99±0.51) × 10-21 cm2molecule-1. We obtain the relationship between absorption length and nitrogen concentration over the 0 to 50 ppm range and discuss the implications for the design and data analysis of future large liquid argon time projection chamber (LArTPC) detectors. Our results indicate that for a current-generation LArTPC, where a concentration of 2 parts per million of nitrogen is expected, the attenuation length due to nitrogen will be 30±3 meters.

  1. Antiapoptotic activity of argon and xenon.

    Science.gov (United States)

    Spaggiari, Sabrina; Kepp, Oliver; Rello-Varona, Santiago; Chaba, Kariman; Adjemian, Sandy; Pype, Jan; Galluzzi, Lorenzo; Lemaire, Marc; Kroemer, Guido

    2013-08-15

    Although chemically non-reactive, inert noble gases may influence multiple physiological and pathological processes via hitherto uncharacterized physical effects. Here we report a cell-based detection system for assessing the effects of pre-defined gas mixtures on the induction of apoptotic cell death. In this setting, the conventional atmosphere for cell culture was substituted with gas combinations, including the same amount of oxygen (20%) and carbon dioxide (5%) but 75% helium, neon, argon, krypton, or xenon instead of nitrogen. The replacement of nitrogen with noble gases per se had no effects on the viability of cultured human osteosarcoma cells in vitro. Conversely, argon and xenon (but not helium, neon, and krypton) significantly limited cell loss induced by the broad-spectrum tyrosine kinase inhibitor staurosporine, the DNA-damaging agent mitoxantrone and several mitochondrial toxins. Such cytoprotective effects were coupled to the maintenance of mitochondrial integrity, as demonstrated by means of a mitochondrial transmembrane potential-sensitive dye and by assessing the release of cytochrome c into the cytosol. In line with this notion, argon and xenon inhibited the apoptotic activation of caspase-3, as determined by immunofluorescence microscopy coupled to automated image analysis. The antiapoptotic activity of argon and xenon may explain their clinically relevant cytoprotective effects. PMID:23907115

  2. TPC2 controls pigmentation by regulating melanosome pH and size.

    Science.gov (United States)

    Ambrosio, Andrea L; Boyle, Judith A; Aradi, Al E; Christian, Keith A; Di Pietro, Santiago M

    2016-05-17

    Melanin is responsible for pigmentation of skin and hair and is synthesized in a specialized organelle, the melanosome, in melanocytes. A genome-wide association study revealed that the two pore segment channel 2 (TPCN2) gene is strongly linked to pigmentation variations. TPCN2 encodes the two-pore channel 2 (TPC2) protein, a cation channel. Nevertheless, how TPC2 regulates pigmentation remains unknown. Here, we show that TPC2 is expressed in melanocytes and localizes to the melanosome-limiting membrane and, to a lesser extent, to endolysosomal compartments by confocal fluorescence and immunogold electron microscopy. Immunomagnetic isolation of TPC2-containing organelles confirmed its coresidence with melanosomal markers. TPCN2 knockout by means of clustered regularly interspaced short palindromic repeat/CRISPR-associated 9 gene editing elicited a dramatic increase in pigment content in MNT-1 melanocytic cells. This effect was rescued by transient expression of TPC2-GFP. Consistently, siRNA-mediated knockdown of TPC2 also caused a substantial increase in melanin content in both MNT-1 cells and primary human melanocytes. Using a newly developed genetically encoded pH sensor targeted to melanosomes, we determined that the melanosome lumen in TPC2-KO MNT-1 cells and primary melanocytes subjected to TPC2 knockdown is less acidic than in control cells. Fluorescence and electron microscopy analysis revealed that TPC2-KO MNT-1 cells have significantly larger melanosomes than control cells, but the number of organelles is unchanged. TPC2 likely regulates melanosomes pH and size by mediating Ca(2+) release from the organelle, which is decreased in TPC2-KO MNT-1 cells, as determined with the Ca(2+) sensor tyrosinase-GCaMP6. Thus, our data show that TPC2 regulates pigmentation through two fundamental determinants of melanosome function: pH and size. PMID:27140606

  3. The Argon Geochronology Experiment (AGE)

    Science.gov (United States)

    Swindle, T. D.; Bode, R.; Fennema, A.; Chutjian, A.; MacAskill, J. A.; Darrach, M. R.; Clegg, S. M.; Wiens, R. C.; Cremers, D.

    2006-01-01

    This viewgraph presentation reviews the Argon Geochronology Experiment (AGE). Potassium-Argon dating is shown along with cosmic ray dating exposure. The contents include a flow diagram of the Argon Geochronology Experiment, and schematic diagrams of the mass spectrometer vacuum system, sample manipulation mechanism, mineral heater oven, and the quadrupole ion trap mass spectrometer. The Laser-Induced Breakdown Spectroscopy (LIBS) Operation with elemental abundances is also described.

  4. Commissioning of a dual-phase Xenon TPC and first Compton scatter results

    International Nuclear Information System (INIS)

    With the MainzTPC, a small 3D position-sensitive dual-phase xenon time projection chamber (TPC), we aim to measure the xenon response for low-energy recoils (few keV) with better precision than previous experiments. Furthermore the setup allows to study the liquid xenon scintillation pulse shape. The goal is to deepen the understanding of xenon as a detection material in the low-energy regime for Dark Matter searches. Here we report on the commissioning of the MainzTPC and first measurements, including scintillation and charge signals as well as coincidence signals between the TPC and a germanium detector for the Compton scattering.

  5. Measuring Muon-Neutrino Charged-Current Differential Cross Sections with a Liquid Argon Time Projection Chamber

    Energy Technology Data Exchange (ETDEWEB)

    Spitz, Joshua B. [Yale Univ., New Haven, CT (United States)

    2011-01-01

    More than 80 years after its proposed existence, the neutrino remains largely mysterious and elusive. Precision measurements of the neutrino's properties are just now beginning to take place. Such measurements are required in order to determine the mass of the neutrino, how many neutrinos there are, if neutrinos are different than anti-neutrinos, and more. Muon-neutrino charged-current differential cross sections on an argon target in terms of the outgoing muon momentum and angle are presented. The measurements have been taken with the ArgoNeuT Liquid Argon Time Projection Chamber (LArTPC) experiment. ArgoNeuT is the first LArTPC to ever take data in a low energy neutrino beam, having collected thousands of neutrino and anti-neutrino events in the NuMI beamline at Fermilab. The results are relevant for long baseline neutrino oscillation experiments searching for non-zero $\\theta_{13}$, CP-violation in the lepton sector, and the sign of the neutrino mass hierarchy, among other things. Furthermore, the differential cross sections are important for understanding the nature of the neutrino-nucleus interaction in general. These measurements represent a significant step forward for LArTPC technology as they are among the first neutrino physics results with such a device.

  6. Measuring Muon-Neutrino Charged-Current Differential Cross Sections with a Liquid Argon Time Projection Chamber

    Science.gov (United States)

    Spitz, Joshua B.

    More than 80 years after its proposed existence, the neutrino remains largely mysterious and elusive. Precision measurements of the neutrino's properties are just now beginning to take place. Such measurements are required in order to determine the mass of the neutrino, how many neutrinos there are, if neutrinos are different than anti-neutrinos, and more. Muon-neutrino charged-current differential cross sections on an argon target in terms of the outgoing muon momentum and angle are presented. The measurements have been taken with the ArgoNeuT Liquid Argon Time Projection Chamber (LArTPC) experiment. ArgoNeuT is the first LArTPC to ever take data in a low energy neutrino beam, having collected thousands of neutrino and anti-neutrino events in the NuMI beamline at Fermi-lab. The results are relevant for long baseline neutrino oscillation experiments searching for non-zero theta13, CP-violation in the lepton sector, and the sign of the neutrino mass hierarchy, among other things. Furthermore, the differential cross sections are important for understanding the nature of the neutrino-nucleus interaction in general. These measurements represent a significant step forward for LArTPC technology as they are among the first neutrino physics results with such a device.

  7. Experimental study of electric breakdowns in liquid argon at centimeter scale

    CERN Document Server

    Blatter, A; Hsu, C -C; Janos, S; Kreslo, I; Luethi, M; von Rohr, C Rudolf; Schenk, M; Strauss, T; Weber, M S; Zeller, M

    2014-01-01

    In this paper we present results on measurements of the dielectric strength of liquid argon near its boiling point and cathode-anode distances in the range of 0.1 mm to 40 mm with spherical cathode and plane anode. We show that at such distances the applied electric field at which breakdowns occur is as low as 40 kV/cm. Flash-overs across the ribbed dielectric of the high voltage feed-through are observed for a length of 300 mm starting from a voltage of 55 kV. These results contribute to set reference for the breakdown-free design of ionization detectors, such as Liquid Argon Time Projection Chambers (LAr TPC).

  8. ALICE TPC upgrade for High-Rate operations

    OpenAIRE

    Biswas, Saikat

    2015-01-01

    A new type of Time Projection Chamber (TPC) has been proposed for the upgrade of the ALICE (A Large Ion Collider Experiment at CERN) so as to cater to the high luminosity environment expected at the Large Hadron Collider (LHC) facility in future. This device will rely on the intrinsic ion back flow (IBF) suppression of Micro-Pattern Gas Detectors (MPGD) based technology in particular the Gas Electron Multiplier (GEM). GEM is to minimise the space charge effect in the main drift volume and thu...

  9. GridPix application to dual phase TPC

    OpenAIRE

    Alfonsi, M.; Bakel, van, P.J.T.; Colijn, A. P.; Decowski, M.P.; de Graaf,, Dirk C; Schön, R.; Tiseni, A.

    2012-01-01

    GridPix is a gas-filled detector with an aluminium mesh stretched 50 μm above the Timepix CMOS pixel chip. This defines a high electric field where gas amplification occurs. A feasibility study is ongoing at Nikhef for the application of the GridPix technology as a charge sensitive device in a dual phase noble gas Time Projection Chamber (TPC), within the framework of the DARWIN design study for next generation dark matter experiments. The smallness of the device and well defined materials al...

  10. Progress on a spherical TPC for low energy neutrino detection

    International Nuclear Information System (INIS)

    The new concept of the spherical TPC aims at relatively large target masses with low threshold and background, keeping an extremely simple and robust operation. Such a device would open the way to detect the neutrino-nucleus interaction, which, although a standard process, remains undetected due to the low energy of the neutrino-induced nuclear recoils. The progress in the development of the first 1 m3 prototype at Saclay is presented. Other physics goals of such a device could include supernova detection, low energy neutrino oscillations and study of non-standard properties of the neutrino, among others

  11. Anode-coupled readout for light collection in Liquid Argon TPCs

    Science.gov (United States)

    Moss, Z.; Toups, M.; Bugel, L.; Collin, G. H.; Conrad, J. M.

    2016-03-01

    This paper will discuss a new method of signal read-out from photon detectors in ultra-large, underground liquid argon time projection chambers. In this design, the signal from the light collection system is coupled via capacitive plates to the TPC wire-planes. This signal is then read out using the same cabling and electronics as the charge information. This greatly benefits light collection: it eliminates the need for an independent readout, substantially reducing cost; it reduces the number of cables in the vapor region of the TPC that can produce impurities; and it cuts down on the number of feed-throughs in the cryostat wall that can cause heat-leaks and potential points of failure. We present experimental results that demonstrate the sensitivity of a LArTPC wire plane to photon detector signals. We also simulate the effect of a 1 μs shaping time and a 2 MHz sampling rate on these signals in the presence of noise, and find that a single photoelectron timing resolution of ~30 ns can be achieved.

  12. Anode-Coupled Readout for Light Collection in Liquid Argon TPCs

    CERN Document Server

    Moss, Z; Bugel, L; Collin, G H; Conrad, J M

    2015-01-01

    This paper will discuss a new method of signal read-out from photon detectors in ultra-large, underground liquid argon time projection chambers. In this design, the signal from the light collection system is coupled via capacitive plates to the TPC wire-planes. This signal is then read out using the same cabling and electronics as the charge information. This greatly benefits light collection: it eliminates the need for an independent readout, substantially reducing cost; It reduces the number of cables in the vapor region of the TPC that can produce impurities; And it cuts down on the number of feed-throughs in the cryostat wall that can cause heat-leaks and potential points of failure. We present experimental results that demonstrate the sensitivity of a LArTPC wire plane to photon detector signals. We also simulate the effect of a 1 $\\mu$s shaping time and a 2 MHz sampling rate on these signals in the presence of noise, and find that a single photoelectron timing resolution of $\\sim$30 ns can be achieved.

  13. Argon Welding Inside A Workpiece

    Science.gov (United States)

    Morgan, Gene E.

    1988-01-01

    Canopies convert large hollow workpiece into inert-gas welding chamber. Large manifold serves welding chamber for attachment of liner parts in argon atmosphere. Every crevice, opening and passageway provided with argon-rich environment. Weld defects and oxidation dramatically reduced; also welding time reduced.

  14. Pattern recognition for a continuously operating GEM-TPC

    International Nuclear Information System (INIS)

    A pattern recognition software for a continuously operating high rate Time Projection Chamber with Gas Electron Multiplier amplification (GEM-TPC) has been designed and tested. A track-independent clustering algorithm delivers space points. A true 3-dimensional track follower combines them to helical tracks, without constraints on the vertex position. Fast helix fits, based on a conformal mapping on the Riemann sphere, are the basis for deciding whether points belong to one track. The software has been tested on simulated as well as on real data taken in a physics run of the GEM-TPC prototype installed in the FOPI detector at GSI facility, Germany. To assess the performance of the algorithm in a high-rate environment, anti pp-interactions corresponding to a maximum average track density of 0.5 cm/cm3 have been simulated. The pattern recognition is capable of finding all kinds of track topologies with high efficiency and provides excellent seed values for fitting or online event selection. Computational costs are O(50) ms/track on a 3.1 GHz office PC. Parallel implementation of the code on a graphics processing unit (GPU) is under investigation. Structure, functioning and benchmark results of the algorithm are presented.

  15. Test Beam Results for ALICE TPC Upgrade Prototypes

    Science.gov (United States)

    Mulligan, James; Alice Tpc-Upgrade Collaboration

    2015-04-01

    The ALICE detector is one of four major experiments at the Large Hadron Collider (LHC), and its main purpose is to study the quark-gluon plasma created in relativistic heavy ion collisions. The Time Projection Chamber (TPC) is the main tracking detector within ALICE, and currently has an intrinsic rate limitation of 3 kHz. The LHC will be upgraded during Long Shutdown 2 in 2018 to have Pb-Pb collision rates up to 50 kHz, and so the TPC readout must be accordingly upgraded. This will be done by replacing the current Multi-Wire Proportional Chamber assembly, which uses a gating grid to prevent ion backflow, with Micro-Pattern Gas Detectors such as Gas Electron Multipliers (GEMs) and Micro-Mesh Gaseous Structures (MMGs), which allow for continuous rather than gated readout. A substantial R&D effort is underway for a 4-GEM design, as well as an alternate 2-GEM/MMG design. Prototypes of each design were tested in November-December 2014 at the PS and SPS beams at CERN; the results for the 2-GEM/MMG chambers will be presented.

  16. Towards a GEM-based TPC for PANDA

    International Nuclear Information System (INIS)

    A Time Projection Chamber (TPC) is a very promising option for the central tracker of the PANDA experiment at the new Facility for Antiproton and Ion Research (FAIR) at Darmstadt, Germany. Installed in a ring-type experiment with 2 x 107 p anti p annihilations per second it has to be operated continuously despite the presence of space charge effects. These are kept at a bearable level using GEM-based amplification providing an intrinsic suppression of ion backflow. The system promises high-accuracy tracking as well as information on the specific energy-loss and features high momentum resolution of 1% as well as particle-identification capability with a highly homogeneous and low material budget. As a prototype of a PANDA TPC a large-volume detector with a ring-cylindrical shape of the drift volume with diameters of 10/30 cm and 73 cm length has been set up. A triple-GEM stack serves as an amplification stage. The signals of 10254 hexagonal pads are read out using front end cards based on the AFTER-T2K chip. Two copies of this system will be installed and employed in 2011 within both the FOPI spectrometer at GSI and the Crystal-Barrel experiment at ELSA in Bonn. In this contribution, we will present the status of the project; report on the design and construction of the detector system as well as results obtained during the commissioning and first beam experiments.

  17. New developments for the GEM-based TPC for PANDA

    International Nuclear Information System (INIS)

    The PANDA experiment is an internal target experiment at the High Energy Storage Ring (HESR) at the new Facility for Antiproton and Ion Research (FAIR) at Darmstadt. A TPC is proposed as the central tracker due to its good position and momentum resolution, its low material budget, and its particle identification capabilities via ionization measurements. The continuous nature of the antiproton beam makes the use of a traditional ion gate impractical and hence GEM foils are used for gas amplification, due to their intrinsic ion back flow suppression properties. A small prototype of this GEM-TPC (diameter 200mm, drift length 77mm) has been built and characterized with cosmic muons using a rectangular pad readout structure. The chamber has recently been upgraded with a new readout plane with hexagonal pads, and new front end electronics, based on the AFTER ASIC. The performance of the detector is expected to improve significantly and is currently being studied at a beam test at the ELSA accelerator at Bonn. Preliminary results are presented in this talk.

  18. NOSTOS: a spherical TPC to detect low energy neutrinos

    International Nuclear Information System (INIS)

    A novel low-energy (∼few keV) neutrino-oscillation experiment NOSTOS, combining a strong tritium source and a high pressure spherical Time Projection Chamber (TPC) detector 10 m in radius has been recently proposed. The oscillation of neutrinos of such energies occurs within the size of the detector itself, potentially allowing for a very precise (and rather systematics-free) measure of the oscillation parameters, in particular, of the smaller mixing angle θ13, which value could be determined for the first time. This detector could also be sensitive to the neutrino magnetic moment and be capable of accurately measure the Weinberg angle at low energy. The same apparatus, filled with high pressure Xenon, exhibits a high sensitivity as a Super Nova neutrino detector with extra galactic sensitivity. The outstanding benefits of the new concept of the spherical TPC will be presented, as well as the issues to be demonstrated in the near future by an ongoing R and D. The very first results of small prototype in operation in Saclay are shown

  19. Heavy ion reaction measurements with the EOS TPC (looking for central collisions with missing energy)

    International Nuclear Information System (INIS)

    The EOS TPC was constructed for complete event measurement of heavy ion collisions at the Bevalac. We report here on the TPC design and some preliminary measurements of conserved event quantities such as total invariant mass, total momentum, total A and Z

  20. Progress on the superconducting magnet for the time projection chamber experiment (TPC) at PEP

    International Nuclear Information System (INIS)

    The TPC (Time Projection Chamber) experiment at PEP will have a two meter inside diameter superconducting magnet which creatests a 1.5 T uniform solenoidal field for the TPC. The superconducting magnet coil, cryostat, cooling system, and the TPC gas pressure vessel (which operatests at 11 atm) were designed to be about two thirds of a radiation length thick. As a result, a high current density coil design was chosen. The magnet is cooled by forced flow two phase helium. The TPC magnet is the largest adiabatically stable superconducting magnet built to date. The paper presents the parameters of the TPC thin solenoid and its subsystems. Tests results from the Spring 1980 cryogenic tes are presented. The topics to be dealt with in the paper are cryogenic services and the tests of magnet subsystems such as the folded current leads. Large thin superconducting magnet technology will be important to large detectors to be used on LEP

  1. Upgrade of the ALICE TPC FEE online radiation monitoring system

    International Nuclear Information System (INIS)

    This paper presents the radiation monitoring system on the Readout Control Unit (RCU) of the the ALICE TPC Front End Electronics. In Run 1, Single Event Upsets (SEUs) in the configuration memory of an SRAM based FPGA were counted, and the results from different run periods with stable beam conditions are presented. For Run 2, a new RCU, the RCU2, has been designed in order to achieve higher data readout rates and increase radiation tolerance. The RCU2 also includes a new radiation monitor solution with increased sensitivity, which is based on counting the number of SEUs in dedicated SRAM memories. The paper presents this new solution together with the results from the targeted irradiation campaigns

  2. NEXT, a HPGXe TPC for neutrinoless double beta decay searches

    CERN Document Server

    Granena, F; Nova, F; Rico, J; Sánchez, F; Nygren, D R; Barata, J A S; Borges, F I G M; Conde, C A N; Dias, T H V T; Fernandes, L M P; Freitas, E D C; Lopes, J A M; Monteiro, C M B; Santos, J M F dos; Santos, F P; Tavora, L M N; Veloso, J F C A; Calvo, E; Gil-Botella, I; Novella, P; Palomares, C; Verdugo, A; Giomataris, Yu; Ferrer-Ribas, E; Hernando-Morata, J A; Martínez, D; Cid, X; Ball, M; Carcel, S; Cervera-Villanueva, Anselmo; Díaz, J; Gil, A; Gómez-Cadenas, J J; Martín-Albo, J; Monrabal, F; Munoz-Vidal, J; Serra, L; Sorel, M; Yahlali, N; Bosch, R Esteve; Lerche, C W; Martinez, J D; Mora, F J; Sebastiá, A; Tarazona, A; Toledo, J F; Lazaro, M; Perez, J L; Ripoll, L; Carmona, J M; Cebrián, S; Dafni, T; Galan, J; Gomez, H; Iguaz, F J; Irastorza, I G; Luzón, G; Morales, J; Rodríguez, A; Ruz, J; Tomas, A; Villar, J A

    2009-01-01

    We propose a novel detection concept for neutrinoless double-beta decay searches. This concept is based on a Time Projection Chamber (TPC) filled with high-pressure gaseous xenon, and with separated-function capabilities for calorimetry and tracking. Thanks to its excellent energy resolution, together with its powerful background rejection provided by the distinct double-beta decay topological signature, the design discussed in this Letter Of Intent promises to be competitive and possibly out-perform existing proposals for next-generation neutrinoless double-beta decay experiments. We discuss the detection principles, design specifications, physics potential and R&D plans to construct a detector with 100 kg fiducial mass in the double-beta decay emitting isotope Xe(136), to be installed in the Canfranc Underground Laboratory.

  3. Upgrade of the ALICE TPC FEE online radiation monitoring system

    Science.gov (United States)

    RØed, K.; Alme, J.; Askeland, E.; David, E.; Gunji, T.; Helstrup, H.; Kiss, T.; Lippmann, C.; Rehman, A.; Röhrich, D.; Ullaland, K.; Velure, A.; Zhao, C.

    2015-12-01

    This paper presents the radiation monitoring system on the Readout Control Unit (RCU) of the the ALICE TPC Front End Electronics. In Run 1, Single Event Upsets (SEUs) in the configuration memory of an SRAM based FPGA were counted, and the results from different run periods with stable beam conditions are presented. For Run 2, a new RCU, the RCU2, has been designed in order to achieve higher data readout rates and increase radiation tolerance. The RCU2 also includes a new radiation monitor solution with increased sensitivity, which is based on counting the number of SEUs in dedicated SRAM memories. The paper presents this new solution together with the results from the targeted irradiation campaigns.

  4. Microwave Argon Plasma Torch

    Science.gov (United States)

    Felizardo, Edgar; Pencheva, Mariana; Benova, Evgenia; Dias, Fransisco; Tatarova, Elena

    2009-10-01

    A theoretical and experimental investigation of a microwave (2.45 GHz) Argon plasma torch driven by a surface wave is presented. The theoretical model couples in a self-consistent way the wave electrodynamics and the electron and heavy particle kinetics. The set of coupled equations includes: Maxwell's equations, the electron Boltzmann equation, including electron-electron collisions, and the particle balance equations for electrons, excited atoms (4s, 4p, 3d, 5s, 5p, 4d, 6s), and atomic (Ar^+) and molecular ions (Ar2^+). The input parameters of the model are: gas pressure (760 Torr), plasma radius (R = 0.75 cm), dielectric permittivity (ɛd = 4.0) and tube thickness (d = 0.15 cm) as well as the measured axial profile of the gas temperature (3500 K - 1500 K). The latter was determined from measurements of the rotational temperature of the OH molecular band in the range 306 - 315 nm. Phase and amplitude sensitive recording provides the data for the axial wavenumber and wave attenuation coefficient. The wavenumber decreases along the generated plasma torch. The electron density (Ne) axial profile as determined from measurements of Hβ Stark broadening is in agreement with the theoretical one.

  5. The Liquid Argon Purity Demonstrator

    Energy Technology Data Exchange (ETDEWEB)

    Adamowski, M.; Carls, B.; Dvorak, E.; Hahn, A.; Jaskierny, W.; Johnson, C.; Jostlein, H.; Kendziora, C.; Lockwitz, S.; Pahlka, B.; Plunkett, R.; Pordes, S.; Rebel, B.; Schmitt, R.; Stancari, M.; Tope, T.; Voirin, E.; Yang, T.

    2014-07-01

    The Liquid Argon Purity Demonstrator was an R&D test stand designed to determine if electron drift lifetimes adequate for large neutrino detectors could be achieved without first evacuating the cryostat. We describe here the cryogenic system, its operations, and the apparatus used to determine the contaminant levels in the argon and to measure the electron drift lifetime. The liquid purity obtained by this system was facilitated by a gaseous argon purge. Additionally, gaseous impurities from the ullage were prevented from entering the liquid at the gas-liquid interface by condensing the gas and filtering the resulting liquid before returning to the cryostat. The measured electron drift lifetime in this test was greater than 6 ms, sustained over several periods of many weeks. Measurements of the temperature profile in the argon, to assess convective flow and boiling, were also made and are compared to simulation.

  6. Electrical conductivity of compressed argon

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, R. [Univ. Regensburg (Germany); Windl, W.; Collins, L.; Kress, J.; Kwon, I. [Los Alamos National Lab., NM (United States)

    1997-10-01

    The authors report calculations of the electrical conductivity of solid argon as a function of compression within the density functional local density approximation formulation for a norm-conserving pseudopotential using both electron-phonon coupling and molecular dynamics techniques.

  7. Testing a liquid Argon calorimeter

    CERN Multimedia

    1976-01-01

    Physicists from Karlsruhe test a liquid argon calorimeter in the neutral beam b16 at the PS. The calorimeter was meant to supply some neutral particles identification at the Split-Field Magnet Facility for R416.

  8. The Liquid Argon Purity Demonstrator

    CERN Document Server

    Adamowski, M; Dvorak, E; Hahn, A; Jaskierny, W; Johnson, C; Jostlein, H; Kendziora, C; Lockwitz, S; Pahlka, B; Plunkett, R; Pordes, S; Rebel, B; Schmitt, R; Stancari, M; Tope, T; Voirin, E; Yang, T

    2014-01-01

    The Liquid Argon Purity Demonstrator was an R&D test stand designed to determine if electron drift lifetimes adequate for large neutrino detectors could be achieved without first evacuating the cryostat. We describe here the cryogenic system, its operations, and the apparatus used to determine the contaminant levels in the argon and to measure the electron drift lifetime. The liquid purity obtained by this system was facilitated by a gaseous argon purge. Additionally, gaseous impurities from the ullage were prevented from entering the liquid at the gas-liquid interface by condensing the gas and filtering the resulting liquid before returning to the cryostat. The measured electron drift lifetime in this test was greater than 6 ms, sustained over several periods of many weeks. Measurements of the temperature profile in the argon, to assess convective flow and boiling, were also made and are compared to simulation.

  9. Measurement of the two-photon absorption cross-section of liquid argon with a time projection chamber

    CERN Document Server

    Badhrees, I; Kreslo, I; Messina, M; Moser, U; Rossi, B; Weber, M S; Zeller, M; Altucci, C; Amoruso, S; Bruzzese, R; Velotta, R

    2010-01-01

    This paper reports on laser-induced multiphoton ionization at 266 nm of liquid argon in a time projection chamber (LAr TPC) detector. The electron signal produced by the laser beam is a formidable tool for the calibration and monitoring of next-generation large-mass LAr TPCs. The detector that we designed and tested allowed us to measure the two-photon absorption cross-section of LAr with unprecedented accuracy and precision: $\\sigma_ex$=(1.24$\\pm$0.10stat $\\pm$0.30syst)$\\times$10^{-56} cm$^4$s{-1}.

  10. Electronic Devices for Controlling the Very High Voltage in the ALICE TPC Detector

    CERN Document Server

    Boccioli, Marco

    2007-01-01

    The Time Projection Chamber (TPC) is the core of the ALICE experiment at CERN. The TPC Very High Voltage project covers the development of the control system for the power supply that generates the 100kV necessary for the drift field in the TPC. This paper reports on the project progress, introducing the control system architecture from the electronics up to the control level. All the electronic devices will be described, highlighting their communication issues, and the challenges in integrating these devices in a PLC-based control system.

  11. Test Beam Measurements with the DESY GridGEM TPC Prototype Module

    OpenAIRE

    Mueller, Felix Johannes

    2014-01-01

    A Time Projection Chamber (TPC) is foreseen as the central tracking detector for the International Large Detector (ILD). To reach the physics goals of the ILD, the performance goals of the TPC surpass previous detectors by an order of magnitude. Micro Pattern Gaseous Detector (MPGD) technology has been shown to be able to meet the requirements.Within the framework of the LCTPC Collaboration, a Large Prototype (LP) TPC has been build as a demonstrator which can be operated in a 1 T magnet at t...

  12. Track reconstruction of normal muon decays in the LAMPF TPC: one working scheme

    International Nuclear Information System (INIS)

    A working scheme for track reconstruction of normal muon decays in the LAMPF TPC is here outlined. Muon tracks stopping in the TPC and helical electron tracks from muon decay are both identified and fitted for complete event reconstruction. Because of certain geometrical characteristics of the TPC, novel techniques are deployed to find the tracks. Normal road tracing methods do not work reliably; they are replaced by, among other things, a random search technique that locates the helix's planar projection and a carefully worked-out method for correctly putting each coordinate on its proper turn in the helix

  13. R&D on the Gem Readout of the Tesla TPC

    OpenAIRE

    Hamann, Markus

    2003-01-01

    Ongoing studies for the TESLA TPC with GEM readout at DESY/Hamburg University are presented. They include basic GEM performances, tracking and the determination of the resolution using different pad sizes and geometries as well as ion feedback measurements.

  14. Some TPC [Time Projection Chamber] measurements in an oxygen beam at the AGS

    International Nuclear Information System (INIS)

    The principal detector for AGS Experiment 810 is a Time Projection Chamber (TPC) in which it is intended to measure momenta and angles of a major fraction of the charged particles from each light ion collision. This report describes the results of a test of a prototype of the TPC in a beam of (14.6 /times/ 16 = 233.6 GeV/c) oxygen ions run in June of this year

  15. Behavior of TPC`s in a high particle flux environment

    Energy Technology Data Exchange (ETDEWEB)

    Etkin, A.; Eiseman, S.E.; Foley, K.J.; Hackenburg, R.W.; Longacre, R.S.; Love, W.A.; Morris, T.W.; Platner, E.D.; Saulys, A.C.; Lindenbaum, S.J. [Brookhaven National Lab., Upton, NY (United States); Chan, C.S.; Kramer, M.A.; Zhao, K.H.; Zhu, Y. [City College of New York, New York (United States); Hallman, T.J.; Madansky, L. [Johns Hopkins Univ., Baltimore, MD (United States); Ahmad, S.; Bonner, B.E.; Buchanan, J.A.; Chiou, C.N.; Clement, J.M.; Mutchler, G.S.; Roberts, J.B. [Bonner Nuclear Lab., Houston, TX (United States)

    1991-12-31

    TPC`s (Time Projection Chamber) used in E-810 at the TAGS (Alternating Gradient Synchrotron) were exposed to fluxes equivalent to more than 10 minimum ionizing particles per second to find if such high fluxes cause gain changes or distortions of the electric field. Initial results of these and other tests are presented and the consequences for the RHIC (Relativistic Heavy Ion Collider) TPC-based experiments are discussed.

  16. Sealed operation, and circulation and purification of gas in the HARPO TPC

    CERN Document Server

    Frotin, M; Attié, D; Bernard, D; Dauvois, V; Delbart, A; Durand, D; Geerebaert, Y; Legand, S; Magnier, P; Poilleux, P; Semeniouk, I

    2015-01-01

    HARPO is a time projection chamber (TPC) demonstrator of a gamma-ray telescope and polarimeter in the MeV-GeV range, for a future space mission. We present the evolution of the TPC performance over a five month sealed-mode operation, by the analysis of cosmic-ray data, followed by the fast and complete recovery of the initial gas properties using a lightweight gas circulation and purification system.

  17. Simulation of GEM-TPC prototype for the super-FRS beam diagnostics system at FAIR

    International Nuclear Information System (INIS)

    The Superconducting Fragment Recoil Separator will be a key part of the experiments of the NuSTAR collaboration. The beam of the separator will have heavy ion projectiles that are steered to the experimental area. With the Time Projection Chambers with Gas Electron Multiplier amplification (GEM-TPC), diagnostics of the beam properties can be performed. The performance of the components of the design of a GEM-TPC prototype has been studied with Geant4 and Garfield simulation tools. (author)

  18. The ALICE TPC Readout Electronics Design, performance optimization and verification of the DAQ circuit

    CERN Document Server

    Attiq, urRehman; Dieter, Røhrich

    2012-12-03

    ALICE (A Large Ion Collider Experiment) is a dedicated heavy-ion experiment at CERN’s LHC (Large Hadron Collider). It is designed to study the physics of strongly interacting matter and the quark-gluon plasma in heavy-ion collisions. It contains a large volume Time Projection Chamber (TPC) as its main tracking device. The ALICE TPC is the largest ever built gaseous TPC, both in terms of dimensions and number of read-out channels (557,578). A total number of 128 channels are packed in one TPC Front End Card (FEC) and 4,356 FECs are distributed over 216 independent readout partitions. Each readout partition steered by a single Readout Control Unit (RCU) functions as an independent unit in the data acquisition system of the TPC. The RCU functions as an interface between the FECs, Data AcQuisition system (DAQ), the Trigger and Timing Circuit (TTC) and the Detector Control System (DCS). The ALICE TPC readout electronics is in operation since the start of the LHC in November 2009. The primary objectives of the wo...

  19. Summary of the second workshop on liquid argon time projection chamber research and development in the United States

    Science.gov (United States)

    Acciarri, R.; Adamowski, M.; Artrip, D.; Baller, B.; Bromberg, C.; Cavanna, F.; Carls, B.; Chen, H.; Deptuch, G.; Epprecht, L.; Dharmapalan, R.; Foreman, W.; Hahn, A.; Johnson, M.; Jones, B. J. P.; Junk, T.; Lang, K.; Lockwitz, S.; Marchionni, A.; Mauger, C.; Montanari, C.; Mufson, S.; Nessi, M.; Olling Back, H.; Petrillo, G.; Pordes, S.; Raaf, J.; Rebel, B.; Sinins, G.; Soderberg, M.; Spooner, N. J. C.; Stancari, M.; Strauss, T.; Terao, K.; Thorn, C.; Tope, T.; Toups, M.; Urheim, J.; Van de Water, R.; Wang, H.; Wasserman, R.; Weber, M.; Whittington, D.; Yang, T.

    2015-07-01

    The second workshop to discuss the development of liquid argon time projection chambers (LArTPCs) in the United States was held at Fermilab on July 8-9, 2014. The workshop was organized under the auspices of the Coordinating Panel for Advanced Detectors, a body that was initiated by the American Physical Society Division of Particles and Fields. All presentations at the workshop were made in six topical plenary sessions: i) Argon Purity and Cryogenics, ii) TPC and High Voltage, iii) Electronics, Data Acquisition and Triggering, iv) Scintillation Light Detection, v) Calibration and Test Beams, and vi) Software. This document summarizes the current efforts in each of these areas. It primarily focuses on the work in the US, but also highlights work done elsewhere in the world.

  20. Summary of the second workshop on liquid argon time projection chamber research and development in the United States

    International Nuclear Information System (INIS)

    The second workshop to discuss the development of liquid argon time projection chambers (LArTPCs) in the United States was held at Fermilab on July 8-9, 2014. The workshop was organized under the auspices of the Coordinating Panel for Advanced Detectors, a body that was initiated by the American Physical Society Division of Particles and Fields. All presentations at the workshop were made in six topical plenary sessions: i) Argon Purity and Cryogenics, ii) TPC and High Voltage, iii) Electronics, Data Acquisition and Triggering, iv) Scintillation Light Detection, v) Calibration and Test Beams, and vi) Software. This document summarizes the current efforts in each of these areas. It primarily focuses on the work in the US, but also highlights work done elsewhere in the world

  1. Summary of the Second Workshop on Liquid Argon Time Projection Chamber Research and Development in the United States

    CERN Document Server

    Acciarri, R; Artrip, D; Baller, B; Bromberg, C; Cavanna, F; Carls, B; Chen, H; Deptuch, G; Epprecht, L; Dharmapalan, R; Foreman, W; Hahn, A; Johnson, M; Jones, B J P; Junk, T; Lang, K; Lockwitz, S; Marchionni, A; Mauger, C; Montanari, C; Mufson, S; Nessi, M; Back, H Olling; Petrillo, G; Pordes, S; Raaf, J; Rebel, B; Sinins, G; Soderberg, M; Spooner, N J C; Stancari, M; Strauss, T; Terao, K; Thorn, C; Tope, T; Toups, M; Urheim, J; Van de Water, R; Wang, H; Wasserman, R; Weber, M; Whittington, D; Yang, T

    2015-01-01

    The second workshop to discuss the development of liquid argon time projection chambers (LArTPCs) in the United States was held at Fermilab on July 8-9, 2014. The workshop was organized under the auspices of the Coordinating Panel for Advanced Detectors, a body that was initiated by the American Physical Society Division of Particles and Fields. All presentations at the workshop were made in six topical plenary sessions: $i)$ Argon Purity and Cryogenics, $ii)$ TPC and High Voltage, $iii)$ Electronics, Data Acquisition and Triggering, $iv)$ Scintillation Light Detection, $v)$ Calibration and Test Beams, and $vi)$ Software. This document summarizes the current efforts in each of these areas. It primarily focuses on the work in the US, but also highlights work done elsewhere in the world.

  2. Summary of the Second Workshop on Liquid Argon Time Projection Chamber Research and Development in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Acciarri, R. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); et al.

    2015-04-21

    The second workshop to discuss the development of liquid argon time projection chambers (LArTPCs) in the United States was held at Fermilab on July 8-9, 2014. The workshop was organized under the auspices of the Coordinating Panel for Advanced Detectors, a body that was initiated by the American Physical Society Division of Particles and Fields. All presentations at the workshop were made in six topical plenary sessions: i) Argon Purity and Cryogenics, ii) TPC and High Voltage, iii) Electronics, Data Acquisition and Triggering, iv) Scintillation Light Detection, v) Calibration and Test Beams, and vi) Software. This document summarizes the current efforts in each of these areas. It primarily focuses on the work in the US, but also highlights work done elsewhere in the world.

  3. ALICE TPC upgrade for High-Rate operations

    CERN Document Server

    ,

    2015-01-01

    A new type of Time Projection Chamber (TPC) has been proposed for the upgrade of the ALICE (A Large Ion Collider Experiment at CERN) so as to cater to the high luminosity environment expected at the Large Hadron Collider (LHC) facility in future. This device will rely on the intrinsic ion back flow (IBF) suppression of Micro-Pattern Gas Detectors (MPGD) based technology in particular the Gas Electron Multiplier (GEM). GEM is to minimise the space charge effect in the main drift volume and thus will not require the standard gating grid and the resulting intrinsic dead time. It will thus be possible to read all minimum bias Pb--Pb events that the Large Hadron Collider (LHC) will deliver at the anticipated peak interaction rate of 50 kHz for the high luminosity heavy-ion era in Run 3. New read-out electronics will send the continuous data stream to a new online farm at rates up to 1~TByte/s. The new read-out chambers will consist of stacks of 4 GEM foils combining different hole pitches. In addition to a low ion...

  4. Fano factor in pure argon

    International Nuclear Information System (INIS)

    The Fano factor for 5.3 MeV alpha particles in pure argon has been measured with a gridded ionization chamber and estimated to be 0.20 (+0.01-0.02). The obtained value is consistent with the theoretical value if the contribution of elastic nuclear collisions to the Fano factor is taken into the consideration. There is no appreciable difference between the values for pure argon and for a gas mixture of Ar (10%)CH4 obtained in the previous measurement. (orig.)

  5. A ROS-Assisted Calcium Wave Dependent on the AtRBOHD NADPH Oxidase and TPC1 Cation Channel Propagates the Systemic Response to Salt Stress1[OPEN

    Science.gov (United States)

    Evans, Matthew J.; Choi, Won-Gyu

    2016-01-01

    Plants exhibit rapid, systemic signaling systems that allow them to coordinate physiological and developmental responses throughout the plant body, even to highly localized and quickly changing environmental stresses. The propagation of these signals is thought to include processes ranging from electrical and hydraulic networks to waves of reactive oxygen species (ROS) and cytoplasmic Ca2+ traveling throughout the plant. For the Ca2+ wave system, the involvement of the vacuolar ion channel TWO PORE CHANNEL1 (TPC1) has been reported. However, the precise role of this channel and the mechanism of cell-to-cell propagation of the wave have remained largely undefined. Here, we use the fire-diffuse-fire model to analyze the behavior of a Ca2+ wave originating from Ca2+ release involving the TPC1 channel in Arabidopsis (Arabidopsis thaliana). We conclude that a Ca2+ diffusion-dominated calcium-induced calcium-release mechanism is insufficient to explain the observed wave transmission speeds. The addition of a ROS-triggered element, however, is able to quantitatively reproduce the observed transmission characteristics. The treatment of roots with the ROS scavenger ascorbate and the NADPH oxidase inhibitor diphenyliodonium and analysis of Ca2+ wave propagation in the Arabidopsis respiratory burst oxidase homolog D (AtrbohD) knockout background all led to reductions in Ca2+ wave transmission speeds consistent with this model. Furthermore, imaging of extracellular ROS production revealed a systemic spread of ROS release that is dependent on both AtRBOHD and TPC1. These results suggest that, in the root, plant systemic signaling is supported by a ROS-assisted calcium-induced calcium-release mechanism intimately involving ROS production by AtRBOHD and Ca2+ release dependent on the vacuolar channel TPC1. PMID:27261066

  6. A ROS-Assisted Calcium Wave Dependent on the AtRBOHD NADPH Oxidase and TPC1 Cation Channel Propagates the Systemic Response to Salt Stress.

    Science.gov (United States)

    Evans, Matthew J; Choi, Won-Gyu; Gilroy, Simon; Morris, Richard J

    2016-07-01

    Plants exhibit rapid, systemic signaling systems that allow them to coordinate physiological and developmental responses throughout the plant body, even to highly localized and quickly changing environmental stresses. The propagation of these signals is thought to include processes ranging from electrical and hydraulic networks to waves of reactive oxygen species (ROS) and cytoplasmic Ca(2+) traveling throughout the plant. For the Ca(2+) wave system, the involvement of the vacuolar ion channel TWO PORE CHANNEL1 (TPC1) has been reported. However, the precise role of this channel and the mechanism of cell-to-cell propagation of the wave have remained largely undefined. Here, we use the fire-diffuse-fire model to analyze the behavior of a Ca(2+) wave originating from Ca(2+) release involving the TPC1 channel in Arabidopsis (Arabidopsis thaliana). We conclude that a Ca(2+) diffusion-dominated calcium-induced calcium-release mechanism is insufficient to explain the observed wave transmission speeds. The addition of a ROS-triggered element, however, is able to quantitatively reproduce the observed transmission characteristics. The treatment of roots with the ROS scavenger ascorbate and the NADPH oxidase inhibitor diphenyliodonium and analysis of Ca(2+) wave propagation in the Arabidopsis respiratory burst oxidase homolog D (AtrbohD) knockout background all led to reductions in Ca(2+) wave transmission speeds consistent with this model. Furthermore, imaging of extracellular ROS production revealed a systemic spread of ROS release that is dependent on both AtRBOHD and TPC1 These results suggest that, in the root, plant systemic signaling is supported by a ROS-assisted calcium-induced calcium-release mechanism intimately involving ROS production by AtRBOHD and Ca(2+) release dependent on the vacuolar channel TPC1. PMID:27261066

  7. CAPTAIN-Minerνa. Neutrino-Argon Scattering in a Medium-Energy Neutrino Beam

    Energy Technology Data Exchange (ETDEWEB)

    Mauger, Christopher M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-10-29

    The NuMI facility at Fermilab is currently providing an extremely intense beam of neutrinos for the NOνA, MINERνA and MINOS+ experiments. By installing the 5-ton CAPTAIN liquid argon TPC in front of the MINERνA detector in the NuMI beamline and combining the data from the CAPTAIN, MINERνA and MINOS+ detectors, a broad program of few-GeV neutrino cross section measurements on argon can be pursued. These measurements will be extremely helpful for future oscillation experiments. By directly comparing the cross sections on argon to MINERνA’s scintillator (CH) target, a new level of precision can be achieved in the measurements of the effects of the nucleus on neutrino interactions. These effects are of interest to not only the particle physics but also the nuclear physics community. This document describes in detail the physics goals of the CAPTAIN-MINERνA experiment, in addition to a first estimate of the technical resources required to install, commission and operate the CAPTAIN detector in front of the MINERVA detector.

  8. CAPTAIN-Miner@@a. Neutrino-Argon Scattering in a Medium-Energy Neutrino Beam

    International Nuclear Information System (INIS)

    The NuMI facility at Fermilab is currently providing an extremely intense beam of neutrinos for the NO@@A, MINER@@A and MINOS+ experiments. By installing the 5-ton CAPTAIN liquid argon TPC in front of the MINER@@A detector in the NuMI beamline and combining the data from the CAPTAIN, MINER@@A and MINOS+ detectors, a broad program of few-GeV neutrino cross section measurements on argon can be pursued. These measurements will be extremely helpful for future oscillation experiments. By directly comparing the cross sections on argon to MINER@@A@@@s scintillator (CH) target, a new level of precision can be achieved in the measurements of the effects of the nucleus on neutrino interactions. These effects are of interest to not only the particle physics but also the nuclear physics community. This document describes in detail the physics goals of the CAPTAIN-MINER@@A experiment, in addition to a first estimate of the technical resources required to install, commission and operate the CAPTAIN detector in front of the MINERVA detector.

  9. Bacteria Inactivation Using DBD Plasma Jet in Atmospheric Pressure Argon

    International Nuclear Information System (INIS)

    A coaxial dielectric barrier discharge plasma jet was designed, which can be operated in atmospheric pressure argon under an intermediate frequency sinusoidal resonant power supply, and an atmospheric pressure glow-like discharge was achieved. Two kinds of typical bacteria, i.e., the Staphylococcus aureus (S. aureus) and Escherichia coil (E. coil), were employed to study the bacterial inactivation mechanism by means of the non-thermal plasma. The killing log value (KLV) of S. aureus reached up to 5.38 with a treatment time of 90 s and that of E. coil up to 5.36 with 60 s, respectively. According to the argon emission spectra of the plasma jet and the scanning electron microscope (SEM) images of the two bacteria before and after the plasma treatment, it is concluded that the reactive species in the argon plasma played a major role in the bacterial inactivation, while the heat, electric field and UV photons had little effect. (plasma technology)

  10. Solar neutrino detection in a large volume double-phase liquid argon experiment

    CERN Document Server

    Franco, D; Agnes, P; Agostino, L; Bottino, B; Davini, S; De Cecco, S; Fan, A; Fiorillo, G; Galbiati, C; Goretti, A M; Hungerford, E V; Ianni, Al; Ianni, An; Jollet, C; Marini, L; Martoff, C J; Meregaglia, A; Pagani, L; Pallavicini, M; Pantic, E; Pocar, A; Renshaw, A L; Rossi, B; Rossi, N; Suvorov, Y; Testera, G; Tonazzo, A; Wang, H; Zavatarelli, S

    2015-01-01

    The direct search for dark matter WIMP particles through their interaction with nuclei at the "neutrino floor" sensitivity, where neutrino-induced coherent scattering on nuclei starts contributing to the background, requires detectors capable of collecting exposures of the order of 1~ktonne yr free of background resulting from beta and gamma decays and cosmogenic and radiogenic neutrons. The same constraints are required for precision measurements of solar neutrinos elastically scattering on electrons. Two-phase liquid argon time projection chambers (LAr TPCs) are prime candidates for the ambitious program to explore the nature of dark matter. The large target, high scintillation light yield and good spatial resolution in all three cartesian directions concurrently allows a high precision measurement of solar neutrino fluxes. We studied the cosmogenic and radiogenic backgrounds affecting solar neutrino detection in a 300 tonne (100 tonne fiducial) LAr TPC operating at LNGS depth (3,800 meters of water equival...

  11. Measurements of ion mobility in argon and neon based gas mixtures

    CERN Document Server

    Deisting, Alexander; Szabo, Alexander; Vranic, Danilo

    2016-01-01

    As gaseous detectors are operated at high rates of primary ionisation, ions created in the detector have a considerable impact on the performance of the detector. The upgraded ALICE Time Projection Chamber (TPC) will operate during LHC Run$\\,3$ with a substantial space charge density of positive ions in the drift volume. In order to properly simulate such space charges, knowledge of the ion mobility $K$ is necessary. To this end, a small gaseous detector was constructed and the ion mobility of various gas mixtures was measured. To validate the corresponding signal analysis, simulations were performed. Results are shown for several argon and neon based mixtures with different $\\textrm{CO}_2$ fractions. A decrease of $K$ was measured for increasing water content.

  12. A Measurement of the Absorption of Liquid Argon Scintillation Light by Dissolved Nitrogen at the Part-Per-Million Level

    CERN Document Server

    Jones, B J P; Conrad, J M; Ignarra, C M; Katori, T; Toups, M

    2013-01-01

    We report on a measurement of the absorption length of scintillation light in liquid argon due to dissolved nitrogen at the part-per-million (ppm) level. We inject controlled quantities of nitrogen into a high purity volume of liquid argon and monitor the light yield from an alpha source. The source is placed at different distances from a cryogenic photomultiplier tube assembly. By comparing the light yield from each position we extract the absorption cross section of nitrogen. We find that nitrogen absorbs argon scintillation light with strength of $\\left(1.51\\pm 0.15\\right)\\times10^{-4} \\;\\mathrm{cm^{-1} ppm^{-1}}$, corresponding to an absorption cross section of $\\left(4.99 \\pm 0.51 \\right)\\times10^{-21}\\;\\mathrm{cm^{2} molecule^{-1}}$. We obtain the relationship between absorption length and nitrogen concentration over the 0 to 50 ppm range and discuss the implications for the design and data analysis of future large liquid argon time projection chamber (LArTPC) detectors. Our results indicate that for a ...

  13. Development of a high-rate TPC based on GEM amplification

    International Nuclear Information System (INIS)

    Future experiments at high-luminosity machines such as PANDA, an antiproton-proton annihilation experiment at FAIR, require high-resolution tracking detectors with good momentum resolution, which at the same time have a very small material budget in order to minimize secondary interactions. A TPC ideally fulfills these requirements, and in addition contributes to particle identification via the measurement of the specific energy loss. The high interaction rate at these machines, however, requires to run the TPC in a continuous mode, i.e. without a gating grid. Therefore GEM foils are used to limit the backflow of ions from the multiplication into drift region. A small triple GEM-TPC has been built and tested using cosmic muons as well as electrons from ELSA, Bonn. First results from these tests will be shown, which provide a valuable cross-check for Monte Carlo simulations of the performance of a TPC in PANDA. These simulations indeed indicate that the challenges of field distortions and event mixing can be overcome. Currently, a larger prototype TPC with a driftlength of 60 cm and a diameter of 30 cm is being built. This chamber is expected to be tested both in the FOPI experiment at GSI and at ELSA in the near future. The design and the present status of this prototype are discussed.

  14. Discharge probability studies in GEM structures for the ALICE TPC upgrade

    International Nuclear Information System (INIS)

    A large Time Projection Chamber (TPC) is the main device for tracking and charged particle identification in the ALICE experiment at the CERN LHC. After the second long shutdown in 2018, the LHC will deliver Pb beams colliding at an interaction rate of about 50 kHz, which is about a factor of 100 above the present readout rate of the TPC. In order to make full use of this luminosity, a major upgrade of the TPC is required. It is foreseen to replace the existing MWPC-based readout with Gas Electron Multiplier (GEM) foils. The GEM foils are commonly known structures used as proportional counters, which permits to obtain high gains at very high radiation rates. However, highly ionizing particles, which may be produced during heavy ion collisions, may trigger an electrical breakdown which may result in damage of the foils or readout electronics. The key parameter for a long-term operation of the GEM-based TPC is the stability against electrical discharges. We performed discharge probability studies in triple and quadruple GEM structures in Ne- and Ar-based gas mixtures to find operational conditions for the upgraded ALICE TPC. Preliminary results from these measurements are discussed in this contribution.

  15. Performances of a GEM-based TPC prototype for new high-rate particle experiments

    International Nuclear Information System (INIS)

    Time projection chamber (TPC) has been successfully used as a central tracker and a particle identification device in a number of a high-energy physics experiments. However, the performance requirements on TPC for new high-rate particle experiments greatly exceed the abilities of traditional TPC readout by multi-wire proportional chamber (MWPC). Gas Electron Multiplier (GEM) detector has great potential to improve TPC performances when used as amplification device. In this paper we present the R and D activity on a new GEM-based TPC (TPG) detector for the inner part of the AMADEUS experiment, a new experimental proposal at DAΦNE accelerator at LNF, aiming to perform measurements of the low-energy negative kaons interactions in nuclei. In order to evaluate the TPG feasibility, a 10x10cm2 prototype with a drift length up to 15 cm are designed. The performances of a 10x10cm2 pre-existing prototype with a reduced drift gap, operated with Ar/CO2/CF4 (45/15/40) gas mixture and successfully tested at BTF facility, are presented. The gas mixture properties, such as the electron drift velocity and the diffusion, have been measured and they result comparable with those simulated with Garfield. A good resolution along the beam direction (z-coordinate), sufficient for a more large scale TPG in AMADEUS, is achieved.

  16. The excitation structure in a micro-hollow cathode discharge in the normal regime at medium argon pressure

    OpenAIRE

    C. Lazzaroni; Chabert, P.; A. Rousseau(MSSL, Surrey, United Kingdom); Sadeghi, N.

    2010-01-01

    Abstract A microplasma is generated in the microhole (400 ?m diameter) of a molybdenum-aluminamolybdenum sandwich (MHCD type) at medium pressure (30-200 Torr) in pure argon. Imaging and emission spectroscopy have been used to study the light emission mechanisms in the microdischarge. We find that emission intensities of both argon atom and argon ion lines present sharp peaks located near the cathode, and that the position of these peaks moves toward the cathode with increasing gas pressure...

  17. Analysis of TPC inner drift chamber wire coatings

    International Nuclear Information System (INIS)

    In the context of analyzing the chemical composition of deposits on wires in a drift chamber at SLAC that failed with an argon/methane gas, the techniques of mass spectroscopy (MS) and Auger electron spectroscopy (AES) are demonstrated. Chemical mechanisms are proposed for conversion of methane gas of polyethylene-like insulating coatings on the wires. Discussion of mass spectra for model compounds is turned toward evaluation of spectra from both field wires and sense wires. Contamination from phthalate plasticizers is found on both sets of wires, while silicone polymer is detected only on sense wires. AES data on field wires show mostly (90%+) carbon; profiles of carbon/gold/copper implicate nonuniformities in the gold coating and/or the underlying copper-beryllium alloy. Successful chamber operation was subsequently achieved by reducing the wire potentials, though polymeric deposition continued at a slower rate

  18. Characteristics of atmospheric-pressure, radio-frequency glow discharges operated with argon added ethanol

    International Nuclear Information System (INIS)

    Rf, atmospheric-pressure glow discharge (APGD) plasmas with bare metal electrodes have promising prospects in the fields of plasma-aided etching, thin film deposition, disinfection and sterilization, etc. In this paper, the discharge characteristics are presented for the rf APGD plasmas generated with pure argon or argon-ethanol mixture as the plasma-forming gas and using water-cooled, bare copper electrodes. The experimental results show that the breakdown voltage can be reduced significantly when a small amount of ethanol is added into argon, probably due to the fact that the Penning ionization process is involved, and a pure α-mode discharge can be produced more easily with the help of ethanol. The uniformity of the rf APGDs of pure argon or argon-ethanol mixtures using bare metallic electrodes is identified with the aid of the intensified charge coupled device images

  19. Characteristics of atmospheric-pressure, radio-frequency glow discharges operated with argon added ethanol

    Science.gov (United States)

    Sun, Wen-Ting; Li, Guo; Li, He-Ping; Bao, Cheng-Yu; Wang, Hua-Bo; Zeng, Shi; Gao, Xing; Luo, Hui-Ying

    2007-06-01

    Rf, atmospheric-pressure glow discharge (APGD) plasmas with bare metal electrodes have promising prospects in the fields of plasma-aided etching, thin film deposition, disinfection and sterilization, etc. In this paper, the discharge characteristics are presented for the rf APGD plasmas generated with pure argon or argon-ethanol mixture as the plasma-forming gas and using water-cooled, bare copper electrodes. The experimental results show that the breakdown voltage can be reduced significantly when a small amount of ethanol is added into argon, probably due to the fact that the Penning ionization process is involved, and a pure α-mode discharge can be produced more easily with the help of ethanol. The uniformity of the rf APGDs of pure argon or argon-ethanol mixtures using bare metallic electrodes is identified with the aid of the intensified charge coupled device images.

  20. Binocular indirect argon laser photocoagulator.

    OpenAIRE

    Mizuno, K

    1981-01-01

    The binocular indirect argon laser photocoagulator was newly designed to enable visualisation of the entire fundus during panretinal laser photocoagulation and to treat retinal tears immediately after buckling procedures of the sclera. The lamp housing of the binocular ophthalmoscope was remodelled and adjusted so that the laser beam and illuminating light are coaxial after leaving the ophthalmoscope. The blocking filter was permanently fixed in the eye-pieces to lighten the weight of the oph...

  1. Liquid Argon Barrel Cryostat Arrived

    CERN Multimedia

    Pailler, P

    Last week the first of three cryostats for the ATLAS liquid argon calorimeter arrived at CERN. It had travelled for 46 days over several thousand kilometers from Japan to CERN. During three years it has been fabricated by Kawasaki Heavy Industries Ltd. at Harima, close to Kobe, under contract from Brookhaven National Laboratory (BNL) of the U.S.. This cryostat consists of two concentric cylinders made of aluminium: the outer vacuum vessel with a diameter of 5.5 m and a length of 7 m, and the inner cold vessel which will contain the electromagnetic barrel calorimeter immersed in liquid argon. The total weight will be 270 tons including the detectors and the liquid argon. The cryostat is now located in building 180 where it will be equipped with 64 feed-throughs which serve for the passage of 122,880 electrical lines which will carry the signals of the calorimeter. After integration of the calorimeter, the solenoidal magnet of ATLAS will be integrated in the vacuum vessel. A final cold test of the cryostat inc...

  2. Online drift velocity calibration with the laser system of the ALICE-TPC

    International Nuclear Information System (INIS)

    The ALICE Time Projection Chamber (TPC) is the main tracking detector of ALICE which was designed to perform well at multiplicities of up to 20000 charged primary and secondary tracks emerging from Pb-Pb collisions. For a precise reconstruction of particle tracks in the TPC, the calibration of the drift velocity, which provides time information and thus the z position of the traversing particles, is essential. In this presentation an online method for the calibration of the drift velocity is presented, using the TPC laser system. The resulting time dependent drift velocity correction parameters are entered into a database and provide start values for the offline reconstruction process of ALICE. Even though no tracking information is used, the online drift velocity calibration is in agreement with the full offline calibration including tracking on the level of 2 x 10-4.

  3. Construction and testing of the two meter diameter TPC thin superconducting solenoid

    International Nuclear Information System (INIS)

    High energy colliding beam physics often requires large detectors which contain large volumes of magnetic field. The TPC (Time Projection Chamber) experiment at PEP will use a 1.5T magnetic field within a cylindrical volume which is 2.04m in diameter bounded by iron poles which are separated by a gap of 3.25m. The TPC magnet, built in 1979 by the Lawrence Berkeley Laboratory (LBL), is the largest high current density superconducting magnet built to date. It is designed to operate at a current density of 7 x 108Am-2 and a stored energy of 11MJ, and it is protected by shorted secondary windings during a quench. The paper describes the basic parameters of the TPC magnet and the results of the first subassembly tests at LBL

  4. TPC track distortions: correction maps for magnetic and static electric inhomogeneities

    CERN Document Server

    Dydak, F; Nefedov, Y

    2003-01-01

    Inhomogeneities of the magnetic and electric fields in the active TPC volume lead to displacements of cluster coordinates, and therefore to track distortions. In case of good data taking conditions, the largest effects are expected from the inhomogeneity of the solenoidal magnetic field, and from a distortion of the electric field arising from a high voltage misalignment between the outer and inner field cages. Both effects are stable over the entire HARP data taking. The displacements are large compared to the azimuthal coordinate resolution but can be corrected with sufficient precision, except at small TPC radius. The high voltage misalignment between the outer and inner field cages is identified as the likely primary cause of sagitta distortions of TPC tracks. The position and the length of the target plays an important role. Based on a detailed modelling of the magnetic and static electric field inhomogeneities, precise correction maps for both effects have been calculated. Predictions from the correctio...

  5. Investigations of the long-term stability of a GEM-TPC

    Energy Technology Data Exchange (ETDEWEB)

    Fedorchuk, Oleksiy [DESY, Hamburg (Germany); Collaboration: LCTPC-Deutschland-Collaboration

    2015-07-01

    For the International Large Detector (ILD) at the planned International Linear Collider (ILC), a Time Projection Chamber (TPC) is foreseen as the main tracking detector. The gas amplification will be done by Micro Pattern Gaseous Detectors (MPGD). One option is to use Gas Electron Multipliers (GEM). While the applicability of GEMs for the gas amplification in a TPC readout has been shown, the focus of the current research is to improve the stability and reliability of the readout modules. This is a crucial requirement for the operation in the final ILD TPC. This presentation shows results from precise discharge current measurements and parallel optical investigations. Ways to improve the long-term stability of the amplification system have been studied.

  6. The whole liver perfusion imaging by using 320-row dynamic volume CT scanning with low-dose in evaluating the short-term effect of argon-helium knife treatment for hepatocellular carcinoma

    International Nuclear Information System (INIS)

    Objective: To investigate the application of the whole liver perfusion imaging by using 320-row dynamic volume CT scanning with low-dose in evaluating the short-term effect of argon-helium (Ar- He) knife treatment for hepatocellular carcinoma (HCC). Methods: The whole liver CT perfusion scanning was carried out in 20 patients with HCC at 2-3 days before and 30-45 days after Ar-He knife treatment The perfusion scanning parameters were determined before and after the treatment. The results were compared with those obtained from another 20 patients who received plain and enhanced CT scanning. Results: (1) Before Ar-He knife treatment, the HAP and HAPI value of tumor were higher than those of peritumoral and normal liver tissues, while the PVP value of tumor was lower than that of peritumoral and normal liver tissue (P<0.05). No significant difference in the values of HAP, HAPI and PVP existed between peritumoral liver tissue and normal liver tissue, with the P values being 0.394, 0.084 and 0.988 respectively. (2) After Ar-He knife treatment, the HAP and HAPI values of tumor decreased, and the difference was statistically significant (both P<0.05), and PVP value decreased slightly with no statistical significance (P=0.970). All HAP, HAPI and PVP values of peritumoral liver tissues decreased, and the differences between each other were significant difference (all P<0.05); while the values of HAP, HAPI and PVP of normal liver tissue showed no significant significance (all P>0.05). (3) The dosage used for the whole liver perfusion scanning was lower than that used for conventional abdominal plain and enhanced scanning, and the difference was statistically significant (P<0.05). Conclusion: The whole liver perfusion imaging by using 320-row dynamic volume CT scanning with low-dose is an effective method to evaluate the short-term curative effect of Ar-He knife for HCC. (authors)

  7. Peach Bottom Turbine Trip Simulations with RETRAN Using INER/TPC BWR Transient Analysis Method

    International Nuclear Information System (INIS)

    The work described in this paper is benchmark calculations of pressurization transient turbine trip tests performed at the Peach Bottom boiling water reactor (BWR). It is part of an overall effort in providing qualification basis for the INER/TPC BWR transient analysis method developed for the Kuosheng and Chinshan plants. The method primarily utilizes an advanced system thermal hydraulics code, RETRAN02/MOD5, for transient safety analyses. Since pressurization transients would result in a strong coupling effect between core neutronic and system thermal hydraulics responses, the INER/TPC method employs the one-dimensional kinetic model in RETRAN with a cross-section data library generated by the Studsvik-CMS code package for the transient calculations. The Peach Bottom Turbine Trip (PBTT) tests, including TT1, TT2, and TT3, have been successfully performed in the plant and assigned as standards commonly for licensing method qualifications for years. It is an essential requirement for licensing purposes to verify integral capabilities and accuracies of the codes and models of the INER/TPC method in simulating such pressurization transients. Specific Peach Bottom plant models, including both neutronics and thermal hydraulics, are developed using modeling approaches and experiences generally adopted in the INER/TPC method. Important model assumptions in RETRAN for the PBTT test simulations are described in this paper. Simulation calculations are performed with best-estimated initial and boundary conditions obtained from plant test measurements. The calculation results presented in this paper demonstrate that the INER/TPC method is capable of calculating accurately the core and system transient behaviors of the tests. Excellent agreement, both in trends and magnitudes between the RETRAN calculation results and the PBTT measurements, shows reliable qualifications of the codes/users/models involved in the method. The RETRAN calculated peak neutron fluxes of the PBTT

  8. A TPC [Time Projection Chamber] detector for the study of high multiplicity heavy ion collisions

    International Nuclear Information System (INIS)

    The design of a Time Projection Chamber (TPC) detector with complete pad coverage is presented. The TPC will allow the measurements of high multiplicity (∼ 200 tracks) relativistic nucleus-nucleus collisions initiated with the heaviest, most energetic projectiles available at the LBL BEVALAC accelerator facility. The front end electronics, composed of over 15,000 time sampling channels, will be located on the chamber. The highly integrated, custom designed, electronics and the VME based data acquisition system are described. 10 refs., 8 figs., 1 tab

  9. Pad equalization and dE/dx in the HARP TPC

    CERN Document Server

    Ammosov, V; Chelkov, G; Dedovitch, D; Dydak, F; Elagin, A; Gostkin, M; Guskov, A; Koreshev, V; Krumshtein, Z; Nefedov, Y; Nikolaev, K; Wotschack, J; Zhemchugov, A

    2006-01-01

    In the HARP TPC, the specific ionization dE/dx depends critically on the pad equalization, which in turn depends on the crosstalk correction. We discuss the TPC pad equalization algorithm and its performance in terms of average and resolution of dE/dx of negative pions with an average active track length of 300 mm. The observed dE/dx of pions and protons agrees satisfactorily with the theoretical expectation, the resolution for a minimum-ionizing track length of 300 mm is 16%.

  10. The scintillation of liquid argon

    CERN Document Server

    Heindl, T; Hofmann, M; Krücken, R; Oberauer, L; Potzel, W; Wieser, J; Ulrich, A

    2015-01-01

    A spectroscopic study of liquid argon from the vacuum ultraviolet at 110 nm to 1000 nm is presented. Excitation was performed using continuous and pulsed 12 keV electron beams. The emission is dominated by the analogue of the so called 2nd excimer continuum. Various additional emission features were found. The time structure of the light emission has been measured for a set of well defined wavelength positions. The results help to interpret literature data in the context of liquid rare gas detectors in which the wavelength information is lost due to the use of wavelength shifters.

  11. Metal clusters on supported argon layers; Metallcluster auf dielektrischen Substraten

    Energy Technology Data Exchange (ETDEWEB)

    Faber, Bernhard

    2011-10-21

    The deposition of small sodium clusters on supported Ar(001)-surfaces is simulated. Theoretical description is achieved by a hierarchical model consisting of time-dependent DFT and molecular dynamics. The valence electrons of the sodium atoms are considered by Kohn-Sham-Scheme with self interaction correction. The interaction of argon atoms and sodium ions is described by atom-atom potentials whereas the coupling to the QM electrons is done by local pseudo-potentials. A decisive part of the model is the dynamical polarizability of the rare-gas atoms. The optional metal support is considered by the method of image charges. The influence of the forces caused by image charges and the influence of the number of argon monolayers on structure, optical response and deposition dynamics of Na{sub 6} and Na{sub 8} is investigated. There is very little influence on cluster structure and only a small shift of the cluster perpendicular to the surface. Concerning optical response the position of the Mie plasmon peak stays robust whereas the details of spectral fragmentation react very sensitively to changes. The forces caused by image charges of the metal support play only a little role with the dynamics of deposition while the thickness of the argon surface strongly influences the dissipation. (orig.)

  12. Lessons from the operation of the `Penning-Fluorescent' TPC and prospects

    CERN Document Server

    Gonzalez-Diaz, Diego; Castel, J; Cebrian, S; Dafni, T; Garcia, J A; Gomez, H; Herrera, D C; Iguaz, F J; Irastorza, I G; Lagraba, A; Luzon, G; Rodriguez, A; Ruiz-Choliz, E; Ferrer-Ribas, A Tomas E; Giomataris, I

    2015-01-01

    We have recently reported the development of a new type of high-pressure Xenon time projection chamber operated with an ultra-low diffusion mixture and that simultaneously displays Penning effect and fluorescence in the near-visible region (300 nm). The concept, dubbed `Penning-Fluorescent' TPC, allows the simultaneous reconstruction of primary charge and scintillation with high topological and calorimetric fidelity.

  13. Particle Identification in Jets and High-Multiplicity pp Events with the ALICE TPC

    CERN Document Server

    AUTHOR|(SzGeCERN)683272; Vogelsang, Werner

    The spectra of identified particles in a collision experiment comprise crucial information about the underlying physical processes. The ALICE experiment has powerful Particle IDentification (PID) capabilities, which are unique at the Large Hadron Collider (LHC). In this thesis, a statistical PID method based on the specific energy loss d$E$/d$x$ in the ALICE Time Projection Chamber (TPC) is developed: the TPC Multi-Template Fit (MTF). The MTF allows for the extraction of identified charged particle spectra in a wide momentum range, which extends from about 150 MeV/$c$ to above 20 GeV/$c$. The TPC PID requires a detailed modelling of the TPC d$E$/d$x$ response for momenta above 2-3 GeV/$c$. A framework is developed that allows for the determination of the model parameters and for evaluating the PID information of charged particles. With the MTF, the transverse momentum $p_{\\mathrm{T}}$ spectra of charged pions, kaons and protons at mid-rapidity ($|\\eta| < 0.9$) are measured for pp collisions at $\\sqrt{s}$ ...

  14. Precise Nuclear Data Measurements Possible with the NIFFTE fissionTPC for Advanced Reactor Designs

    Science.gov (United States)

    Towell, Rusty; Niffte Collaboration

    2015-10-01

    The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) Collaboration has applied the proven technology of Time Projection Chambers (TPC) to the task of precisely measuring fission cross sections. With the NIFFTE fission TPC, precise measurements have been made during the last year at the Los Alamos Neutron Science Center from both U-235 and Pu-239 targets. The exquisite tracking capabilities of this device allow the full reconstruction of charged particles produced by neutron beam induced fissions from a thin central target. The wealth of information gained from this approach will allow systematics to be controlled at the level of 1%. The fissionTPC performance will be presented. These results are critical to the development of advanced uranium-fueled reactors. However, there are clear advantages to developing thorium-fueled reactors such as Liquid Fluoride Thorium Reactors over uranium-fueled reactors. These advantages include improved reactor safety, minimizing radioactive waste, improved reactor efficiency, and enhanced proliferation resistance. The potential for using the fissionTPC to measure needed cross sections important to the development of thorium-fueled reactors will also be discussed.

  15. Front-end electronics and readout system for the ILD TPC

    CERN Document Server

    Hedberg, V; Lundberg, B; Mjörnmark, U; Oskarsson, A; Österman, L; De Lentdecker, G; Yang, Y; Zhang, F

    2015-01-01

    A high resolution TPC is the main option for a central tracking detector at the future International Linear Collider (ILC). It is planned that the MPGD (Micro Pattern Gas Detector) technology will be used for the readout. A Large Prototype TPC at DESY has been used to test the performance of MPGDs in an electron beam of energies up to 6 GeV. The first step in the technology development was to demonstrate that the MPGDs are able to achieve the necessary performance set by the goals of ILC. For this ’proof of principle’ phase, the ALTRO front-end electronics from the ALICE TPC was used, modified to adapt to MPGD readout. The proof of principle has been verified and at present further improvement of the MPGD technology is going on, using the same readout electronics. The next step is the ’feasibility phase’, which aims at producing front-end electronics comparable in size (few mm2) to the readout pads of the TPC. This development work is based on the succeeding SALTRO16 chip, which combines the analogue ...

  16. Tokamak plasma power balance calculation code (TPC code) outline and operation manual

    International Nuclear Information System (INIS)

    This report is a detailed description on the TPC code, that calculates the power balance of a tokamak plasma according to the ITER guidelines. The TPC code works on a personal computer (Macintosh or J-3100/ IBM-PC). Using input data such as the plasma shape, toroidal magnetic field, plasma current, electron temperature, electron density, impurities and heating power, TPC code can determine the operation point of the fusion reactor (Ion temperature is assumed to be equal to the electron temperature). Supplied flux (Volt · sec) and burn time are also estimated by coil design parameters. Calculated energy confinement time is compared with various L-mode scaling laws and the confinement enhancement factor (H-factor) is evaluated. Divertor heat load is predicted by using simple scaling models (constant-χ, Bohm-type-χ and JT-60U empirical scaling models). Frequently used data can be stored in a 'device file' and used as the default values. TPC code can generate 2-D mesh data and the POPCON plot is drawn by a contour line plotting program (CONPLT). The operation manual about CONPLT code is also described. (author)

  17. Performance of the fissionTPC and the Potential to Advance the Thorium Fuel Cycle

    Science.gov (United States)

    Towell, Rusty; Niffte Collaboration

    2014-09-01

    The NIFFTE fission Time Projection Chamber (fissionTPC) is a powerful tool that is being developed to take precision measurements of neutron-induced fission cross sections of transuranic elements. During the last run at the Los Alamos Neutron Science Center (LANSCE) the fully instrumented TPC took data for the first time. The exquisite tracking capabilities of this device allow the full reconstruction of charged particles produced by neutron beam induced fissions from a thin central target. The wealth of information gained from this approach will allow cross section systematics to be controlled at the level of 1%. The fissionTPC performance from this run will be shared. These results are critical to the development of advanced uranium-fueled reactors. However, there are clear advantages to developing thorium-fueled reactors including the abundance of thorium verses uranium, minimizing radioactive waste, improved reactor safety, and enhanced proliferation resistance. The potential for using the fissionTPC to measure needed cross sections important to the development of thorium fueled nuclear reactors will also be discussed.

  18. Performance of a micro-TPC for a time-resolved neutron PSD

    CERN Document Server

    Miuchi, K; Nagayoshi, T; Orito, R; Takada, A; Takeda, A; Tanimori, T; Ueno, M; Miuchi, Kentaro; Kubo, Hidetoshi; Nagayoshi, Tsutomu; Orito, Reiko; Takada, Atsushi; Takeda, Atsushi; Tanimori, Toru; Ueno, Masaru

    2004-01-01

    We report on the performance of a micro-TPC with a micro pixel chamber($\\mu$-PIC) readout for a time-resolved neutron position-sensitive detector(PSD). Three-dimensional tracks and the Bragg curves of protons with energies of around 1 MeV were clearly detected by the micro-TPC. More than 95% of gamma-rays of 511 keV were found to be discriminated by simple analysis. Simulation studies showed that the total track length of proton and triton emitted from the $\\rm {}^{3}He$(n,p(573 keV))$\\rm {}^{3}H(191 keV)$ reaction is about 1.2 cm, and that both particles have large energy losses ($\\rm > 200 keV/cm$) in 1 atm Ar+$\\rm C_{2}H_{6}(10%)$+${}^{3}$He($< 1%$). These values suit the current performance of the micro-TPC, and we conclude that a time-resolved neutron PSD with spatial resolution of sub-millimeters shall be developed as an application of the micro-TPC.

  19. Measuring Cross-Section and Estimating Uncertainties with the fissionTPC

    Energy Technology Data Exchange (ETDEWEB)

    Bowden, N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Manning, B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Sangiorgio, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Seilhan, B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-01-30

    The purpose of this document is to outline the prescription for measuring fission cross-sections with the NIFFTE fissionTPC and estimating the associated uncertainties. As such it will serve as a work planning guide for NIFFTE collaboration members and facilitate clear communication of the procedures used to the broader community.

  20. Analysis of TPC Single Sextant U-238/U-235 Engineering In-Beam Data

    Energy Technology Data Exchange (ETDEWEB)

    Tony Hill

    2012-09-01

    The Time Projection Chamber is a collaborative effort to implement an innovative approach and deliver unprecedented fission measurements to DOE programs. This 4p- detector system will provide unrivaled 3-D data about the fission process. This TPC has been shipped and installed at LANSCE and is collecting further engineering data for the full system scale up next year.

  1. A time projection chamber for high-rate experiments: Towards an upgrade of the ALICE TPC

    International Nuclear Information System (INIS)

    A Time Projection Chamber (TPC) is a powerful detector for three-dimensional tracking and particle identification for ultra-high multiplicity events. It is the central tracking device of many experiments, e.g. of the ALICE experiment at CERN. The necessity of a switching electrostatic gate, which prevents ions produced in the amplification region of the MWPCs from entering the drift volume, however, restricts its application to trigger rates of the order of 1 kHz. Charge amplification by Gas Electron Multiplier (GEM) foils instead of proportional wires offers an intrinsic suppression of the ion backflow, although not to the same level as a gating grid. Detailed Monte Carlo simulations have shown that the distortions due to residual space charge from back-drifting ions can be limited to a few cm, and thus can be corrected using standard calibration techniques. A prototype GEM-TPC has been built with the largest active volume to date for a detector of this type. It has been commissioned with cosmic rays and with particle beams at the FOPI experiment at GSI, and was employed for a physics measurement with pion beams. For the future operation of the ALICE TPC at the CERN LHC beyond 2019, where Pb–Pb collision rates of 50 kHz are expected, it is planned to replace the existing MWPCs by GEM detectors, operated in a continuous, triggerless readout mode, thus allowing an increase in event rate by a factor of 100. As a first step of the R and D program, a prototype of an Inner Readout Chamber was equipped with large-size GEM foils and exposed to beams of protons, pions and electrons from the CERN PS. In this paper, new results are shown concerning ion backflow, spatial and momentum resolution of the FOPI GEM-TPC, detector calibration, and dE/dx resolution with both detector prototypes. The perspectives of a GEM-TPC for ALICE with continuous readout will be discussed

  2. ALICE TPC Upgrade Activities for LHC Run 3 and Beyond: "SAMPA ASIC Tests with GEM Detector Prototype"

    OpenAIRE

    Engeseth, Kristian Philip

    2015-01-01

    The Time Projection Chamber (TPC) signal readout of the ALICE detector is being upgraded to accommodate the higher collision rates and -energies during LHC Run 3 in 2018. Due to the increased collision rates, the TPC drift time of about 100 μs will be 5 times longer than the average time between interactions, rendering the presently employed gating of the TPC wire-chambers insufficient. Therefore, a Gas Electron Multiplier (GEM) based system will be replacing the wire-chambers. In addition, t...

  3. First measurement of polarisation asymmetry of a gamma-ray beam between 1.74 to 74 MeV with the HARPO TPC

    CERN Document Server

    Gros, Philippe; Attié, David; Bernard, Denis; Bruel, Philippe; Calvet, Denis; Colas, Paul; Daté, Schin; Delbart, Alain; Frotin, Mickael; Geerebaert, Yannick; Giebels, Berrie; Götz, Diego; Hashimoto, S; Horan, Deirdr; Kotaka, T; Louzir, Marc; Minamiyama, Y; Miyamoto, Shuji; Ohkuma, H; Poilleux, Patrick; Semeniouk, Igor; Sizun, Patrick; Takemoto, A; Yamaguchi, M; Wang, Shaobo

    2016-01-01

    Current $\\gamma$-ray telescopes suffer from a gap in sensitivity in the energy range between 100keV and 100MeV, and no polarisation measurement has ever been done on cosmic sources above 1MeV. Past and present e$^+$e$^-$ pair telescopes are limited at lower energies by the multiple scattering of electrons in passive tungsten converter plates. This results in low angular resolution, and, consequently, a drop in sensitivity to point sources below 1GeV. The polarisation information, which is carried by the azimuthal angle of the conversion plane, is lost for the same reasons. HARPO (Hermetic ARgon POlarimeter) is an R\\&D program to characterise the operation of a gaseous detector (a Time Projection Chamber or TPC) as a high angular-resolution and sensitivity telescope and polarimeter for $\\gamma$ rays from cosmic sources. It represents a first step towards a future space instrument in the MeV-GeV range. We built and characterised a 30cm cubic demonstrator [SPIE 91441M], and put it in a polarised $\\gamma$-ray...

  4. Transition probabilities for argon I

    International Nuclear Information System (INIS)

    Transition probabilities for ArI lines have been calculated on the basis of the (j,k)-coupling scheme for more than 16000 spectral lines belonging to the transition arrays 4s-np (n=4 to n=9), 5s-np (n=5 to n=9), 6s-np (n=6 to n=9), 7s-np (n=8 to n=9), 4p-ns (n=5 to n=10), 5p-ns (n=6 to n=9), 6p-ns (n=7 to n=8), 4p-nd (n=3 to n=9), 5p-nd (n=4 to n=9), 3d-np (n=5 to n=9), 4d-np (n=6 to n=9), 5d-np (n=7 to n=9), 3d-nf (n=4 to n=9), 4d-nf (n=4 to n=9), 5d-nf (n=5 to n=9), 4f-nd (n=5 to n=9) 5f-nd (n=6 to n=9), 4f-ng (n=5 to n=9), 5f-ng (n=6 to n=9). Inso far as values by other authors exist, comparison is made with these values. It turns out that the results obtained in (j,k)-coupling are close to those obtained in intermediate coupling except for intercombination lines. For high principal and/or orbital quantum numbers the transition probabilities for a multiplet approach those of the corresponding transitions in atomic hydrogen. The calculated values are applied to construct a simplified argon-atom model, which reflects the real transition properties and which allows simplified but realistic non-equilibrium calculations for argon plasmas which deviate from local thermodynamic equilibrium (LTE)

  5. An Optical Readout TPC (O-TPC) for Studies in Nuclear Astrophysics With Gamma-Ray Beams at HIgS

    OpenAIRE

    Gai, M.; Ahmed, M.W.; Stave, S. C.; Zimmerman, W. R.; Breskin, A.; Bromberger, B.; Chechik, R.; Dangendorf, V.; Delbar, Th.; France III, R. H.; Henshaw, S. S.; Kading, T. J.; Martel, P.P.; McDonald, J. E. R.; Seo, P. -N.

    2011-01-01

    We report on the construction, tests, calibrations and commissioning of an Optical Readout Time Projection Chamber (O-TPC) detector operating with a CO2(80%) + N2(20%) gas mixture at 100 and 150 Torr. It was designed to measure the cross sections of several key nuclear reactions involved in stellar evolution. In particular, a study of the rate of formation of oxygen and carbon during the process of helium burning will be performed by exposing the chamber gas to intense nearly mono-energetic g...

  6. Surface modification of polypropylene using argon plasma: Statistical optimization of the process variables

    International Nuclear Information System (INIS)

    Low pressure plasma treatment using radiofrequency (rf) discharge of argon gas was employed to improve the hydrophilicity of polypropylene. The effects of argon plasma on the wettability, surface chemistry and surface morphology of polypropylene were studied using static contact angle measurements, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Increase in surface energy of polypropylene was observed as a result of argon plasma treatment. SEM and AFM images revealed the increased surface roughness. A set of identified process variables (rf power, pressure, argon flow rate and time) were used in this study and were optimized using central composite design (CCD) of response surface methodology (RSM). A statistical model was developed to represent the surface energy in terms of the process variables mentioned above. Accuracy of the model was verified and found to be high.

  7. A large liquid argon time projection chamber for long-baseline, off-axis neutrino oscillation physics with the NuMI beam

    International Nuclear Information System (INIS)

    Results from neutrino oscillation experiments in the last ten years have revolutionized the field of neutrino physics. While the overall oscillation picture for three neutrinos is now well established and precision measurements of the oscillation parameters are underway, crucial issues remain. In particular, the hierarchy of the neutrino masses, the structure of the neutrino mixing matrix, and, above all, CP violation in the neutrino sector are the primary experimental challenges in upcoming years. A program that utilizes the newly commissioned NuMI neutrino beamline, and its planned upgrades, together with a high-performance, large-mass detector will be in an excellent position to provide decisive answers to these key neutrino physics questions. A Liquid Argon time projection chamber (LArTPC), which combines fine-grained tracking, total absorption calorimetry, and scalability, is well matched for this physics program. The few-millimeter-scale spatial granularity of a LArTPC combined with dE/dx measurements make it a powerful detector for neutrino oscillation physics. Scans of simulated event samples, both directed and blind, have shown that electron identification in νe charged current interactions can be maintained at an efficiency of 80%. Backgrounds for νe appearance searches from neutral current events with a π0 are reduced well below the ∼ 0.5-1.0% νe contamination of the νμ beam. While the ICARUS collaboration has pioneered this technology and shown its feasibility with successful operation of the T600 (600-ton) LArTPC, a detector for off-axis, long-baseline neutrino physics must be many times more massive to compensate for the low event rates. We have a baseline concept based on the ICARUS wire plane structure and commercial methods of argon purification and housed in an industrial liquefied-natural-gas tank. Fifteen to fifty kton liquid argon capacity tanks have been considered. A very preliminary cost estimate for a 50-kton detector is $100M

  8. Argon-39 Background in DUNE Photon Detectors

    Science.gov (United States)

    Sinev, Gleb; DUNE Collaboration

    2016-03-01

    The Deep Underground Neutrino Experiment (DUNE) is a 40-kt liquid argon detector that will be constructed 5000 ft underground in the Sanford Underground Research Facility in order to study neutrino and proton decay physics. Instrumenting liquid argon with photon detectors to record scintillation in addition to the ionization signal can significantly improve time and energy resolution of the experiment. Argon produces light with wavelength of 128 nm. The reference design for the photon detectors includes acrylic bars covered in wavelength shifter, where the scintillation light can be captured and reemitted with longer wavelengths, then detected using silicon photomultipliers. Radiological backgrounds may noticeably deteriorate the photon detection system performance, especially for low-energy interactions. A particularly important background comes from argon-39 decays, because argon-39 is present in natural argon that will be used in DUNE and the background rate increases with the size of the experiment. The effect of the argon-39 background has been studied and is presented in this talk.

  9. Emissive spectra of shock-heated argon

    International Nuclear Information System (INIS)

    To study the radiant properties of argon under weak shock compression, an aluminum target filled with gaseous argon at ambient states was impacted by a tungsten alloy projectile which was launched from a two-stage light gun to 2.00 km/s. The radiant signals of single shock-compressed argon were recorded by a six-channel pyrometer and oscilloscopes, which varied with time linearly for the five channels from 405 nm to 700 nm and exponentially for the channel 800 nm, and the corresponding velocity of shock wave was determined to be 4.10 ± 0.09 km/s. By the present experiment, it has been shown that the absorbability of the shock-heated argon is low for visual light and the optical depths of argon gas turn from thin to thick as wavelengths gradually increase. The time-resolved spectra in the rising-front of the radiant signal in the re-shocked argon were recorded by means of an OMA, and strong emissive spectrum bands near 450 nm light-wave length but no linear spectrum were found. The emissive spectrum properties of shock-compression argon were qualitatively explained by the state parameters and ionization degree

  10. Development of GEM-based Read-Out Chambers for the upgrade of the ALICE TPC

    International Nuclear Information System (INIS)

    ALICE at the LHC at CERN is planning a major upgrade of the central barrel detectors, including the TPC, to cope with an increase of the LHC luminosity after 2018. A prototype of an ALICE TPC Inner Read-Out Chamber (IROC) was equipped with three large-size Gas Electron Multiplier (GEM) foils as amplification stage to demonstrate the feasibility of replacing the current readout by Multi-Wire Proportional Chambers (MWPC) with such technology. The GEM IROC was installed within a test field cage with a drift length of 115 mm and commissioned with radioactive sources. The dE/dx resolution of the prototype was evaluated in a test beam campaign at the CERN PS and is comparable to the resolution of the MWPC IROC. Stability under LHC conditions was tested during the ALICE p-Pb beam time, when the prototype was mounted underneath LHC beam pipe, close to the interaction point

  11. Clock and data recovery methods for the readout control unit 2 in ALICE TPC

    International Nuclear Information System (INIS)

    The present ALICE TPC readout electronics consists of 4356 Front End Cards that are read out and controlled by a total of 216 Readout Control Units (RCUs). The RCU communicates with all sub-systems, in particular with the Timing, Trigger and Control (TTC) system, which provides each RCU with the 40.08 MHz LHC clock, which is used as a system and sampling clock in TPC readout electronics. The LHC clock and trigger data are sent over the TTC fiber using 80 Mb/s Time Division Multiplexed BiPhase Mark encoded signals. It is important to have a radiation tolerant solution to recover the clock with low jitter and with a predefined phase-offset to the LHC input clock. Presently, this is handled by the TTC receiver (TTCrx) ASIC sitting on the RCU

  12. Synchrotron radiation monitoring for LEP2 using the DELPHI-TPC silicon detector

    International Nuclear Information System (INIS)

    The Time Projection Chamber (TPC) of the DELPHI detector suffers contamination due to Synchrotron Radiation (small ionized cloud with slow drift velocity which causes a magnetic field perturbation), specially during the new phase of operation of the LEP. Therefore one needs to monitor this radiation by means of an independent detector. This detector, which has been developed during the last 20 months, uses the silicon technique and allows precise measurements of both the energy and time of flight of the photons, either direct, or back-scattered by the quadrupoles, masks or collimations in front of the TPC. Typical time delay and energy range are of the order of 50 ns and 100 to 400 KeV, respectively. The detector being independent of the DELPHI acquisition system, it allows a good monitoring task that can give some clue on the state of the beams and non-stop trace plot

  13. Energy calibration of a GEM-TPC prototype with 83mKr

    International Nuclear Information System (INIS)

    A GEM-TPC has been built as a 10% scale prototype for the P-bar ANDA experiment and as a full-scale prototype for the CBELSA/TAPS experiment (Fabbietti L, et al: Nucl Instrum Methods A 628:204, 2011). The intrinsic suppression of ion backflow into the drift volume makes it suitable for high rate/background environments. The GEM-TPC has been used as an inner tracking update for the FOPI experiment at GSI where cosmic and beam tests were performed. For calibration purposes a 83Rb source has been produced at the Bonn HISKP Cyclotron. Using the isomeric 83mKr evaporated by the source, a relative channel-wise gain calibration as well as gain estimation for different high voltage settings could be performed.

  14. A Time Projection Chamber for High-Rate Experiments: Towards an Upgrade of the ALICE TPC

    OpenAIRE

    Ketzer, Bernhard; GEM-TPC, for the; Collaborations, ALICE TPC

    2013-01-01

    A Time Projection Chamber (TPC) is a powerful detector for 3-dimensional tracking and particle identification for ultra-high multiplicity events. It is the central tracking device of many experiments, e.g. the ALICE experiment at CERN. The necessity of a switching electrostatic gate, which prevents ions produced in the amplification region o MWPCs from entering the drift volume, however, restricts its application to trigger rates of the order of 1 kHz. Charge amplification by Gas Electron Mul...

  15. The PreAmplifier ShAper for the ALICE TPC detector

    International Nuclear Information System (INIS)

    In this paper the PreAmplifier ShAper (PASA) for the Time Projection Chamber (TPC) of the ALICE experiment at LHC is presented. The ALICE TPC PASA is an ASIC that integrates 16 identical channels, each consisting of Charge Sensitive Amplifiers (CSA) followed by a Pole-Zero network, self-adaptive bias network, two second-order bridged-T filters, two non-inverting level shifters and a start-up circuit. The circuit is optimized for a detector capacitance of 18–25 pF. For an input capacitance of 25 pF, the PASA features a conversion gain of 12.74 mV/fC, a peaking time of 160 ns, a FWHM of 190 ns, a power consumption of 11.65 mW/ch and an equivalent noise charge of 244e+17e/pF. The circuit recovers smoothly to the baseline in about 600 ns. An integral non-linearity of 0.19% with an output swing of about 2.1 V is also achieved. The total area of the chip is 18 mm2 and is implemented in AMS's C35B3C1 0.35μm CMOS technology. Detailed characterization tests were performed on about 48 000 PASA circuits before mounting them on the ALICE TPC front-end cards. After more than two years of operation of the ALICE TPC with p–p and Pb–Pb collisions, the PASA has demonstrated to fulfill all requirements.

  16. Simulation of double beta decay in the ''SeXe'' TPC

    Science.gov (United States)

    Mauger, F.

    2007-04-01

    In 2004, the NEMO collaboration has started some preliminary studies for a next-generation double beta decay experiment: SuperNEMO. The possibility to use a large gaseous TPC has been investigated using simulation and extrapolation of former experiments. In this talk, I report on the reasons why such techniques have not been selected in 2004 and led the NEMO collaboration to reuse the techniques implemented within the NEMO3 detector.

  17. Simulation of double beta decay in the 'SeXe' TPC

    Energy Technology Data Exchange (ETDEWEB)

    Mauger, F [LPC Caen and University of Caen, ENSICAEN, 6 Bd Marechal Juin, 14050 CAEN CEDEX 4 (France)

    2007-04-15

    In 2004, the NEMO collaboration has started some preliminary studies for a next-generation double beta decay experiment: SuperNEMO. The possibility to use a large gaseous TPC has been investigated using simulation and extrapolation of former experiments. In this talk, I report on the reasons why such techniques have not been selected in 2004 and led the NEMO collaboration to reuse the techniques implemented within the NEMO3 detector.

  18. Particle ID with dE/dx at the TESLA-TPC

    CERN Document Server

    Hauschild, M

    2000-01-01

    The dE/dx resolution of the TESLA-TPC has been studied using a toy Monte Carlo simulation based on measured cluster size distributions. Various parameters like sampling length, electronics noise, crosstalk etc. have been investigated. An optimum number of 240 samples has been found (5 mm sampling length) with a simulated dE/dx resolution of 4.1%. The particle separation power has been estimated. (11 refs).

  19. Thermal influences of the front-end electronics on the ALICE TPC readout chamber

    CERN Document Server

    Popescu, Sorina; Schmidt, Hans Rudolf

    2004-01-01

    The ALICE TPC detector will be operated with a gas mixture of 90% Ne and 10% CO/sub 2/ at the electric field of 400 V/cm. Recent studies favor a three-component mixture by adding about 5% N/sub 2/, which will improve the stability of the gas against discharges. These operating parameters lead to a non-saturated drift velocity for electrons but also impose that all external influences on the drift gas must be reduced to minimum. The most problematic influence is temperature variation, which can lead to local fluctuation in the gas density and therefore directly affects the drift velocity. For the Alice TPC, the aim is to have a temperature stability of 0.1 degrees C over the full drift length (2.5 m). The main heat contribution comes from the readout chambers front-end electronics and one estimates that a total of 30.2 kW must be removed. The test results discussed here give qualitative and quantitative information about the thermal behavior of the chambers for validation of the TPC cooling strategy.

  20. A study with a small prototype TPC for the international linear collider experiment

    CERN Document Server

    Ackermann, K; Arogancia, D C; Bacala, A M; Ball, M; Behnke, T; Bito, H; Eckardt, V; Fujii, K; Fusayasu, T; Ghodbane, N; Gooc, H C; Kijima, T; Hamann, M; Habu, M; Heuer, R D; Hiramatsu, K; Ikematsu, K; Kaukher, A; Kuroiwa, H; Janssen, M E; Kato, Y; Kobayashi, M; Kühl, T; Lux, T; Matsuda, T; Matsushita, S; Miyazaki, A; Nakamura, K; Nitoh, O; Ohta, H; Reserva, R L; Sakai, K; Sakamoto, N; Sanuki, T; Settles, R; Sugiyama, A; Takahashi, T; Tomioka, T; Tsuji, H; Watanabe, T; Wienemann, P; Wurth, R; Yamaguchi, H; Yamaguchi, M; Yamaguchi, A; Yamamura, T; Yamaoka, H; Yazu, T; Yonamine, R; 10.1016/j.nima.2010.02.175

    2010-01-01

    A time projection chamber (TPC) is a strong candidate for the central tracker of the international linear collider (ILC) experiment and we have been conducting a series of cosmic ray experiments under a magnetic field up to 4 T, using a small prototype TPC with a replaceable readout device: multi-wire proportional chamber (MWPC) or gas electron multiplier (GEM). We first confirmed that the MWPC readout could not be a fall-back option of the ILC-TPC under a strong axial magnetic field of 4 T since its spatial resolution suffered severely from the so called E x B effect in the vicinity of the wire planes. The GEM readout, on the other hand, was found to be virtually free from the E x B effect as had been expected and gave the resolution determined by the transverse diffusion of the drift electrons (diffusion limited). Furthermore, GEMs allow a wider choice of gas mixtures than MWPCs. Among the gases we tried so far a mixture of Ar-CF4-isobutane, in which MWPCs could be prone to discharges, seems promising as th...

  1. Lossy compression of TPC data and trajectory tracking efficiency for the ALICE experiment

    CERN Document Server

    Nicolaucig, A; Mattavelli, M

    2003-01-01

    In this paper a quasi-lossless algorithm for the on-line compression of the data generated by the Time Projection Chamber (TPC) detector of the ALICE experiment at CERN is described. The algorithm is based on a lossy source code modeling technique, i.e. it is based on a source model which is lossy if samples of the TPC signal are considered one by one; conversely, the source model is lossless or quasi-lossless if some physical quantities that are of main interest for the experiment are considered. These quantities are the area and the location of the center of mass of each TPC signal pulse, representing the pulse charge and the time localization of the pulse. So as to evaluate the consequences of the error introduced by the lossy compression process, the results of the trajectory tracking algorithms that process data off-line after the experiment are analyzed, in particular, versus their sensibility to the noise introduced by the compression. Two different versions of these off- line algorithms are described,...

  2. Search for H-dibaryon at J-PARC with a Large Acceptance TPC

    Directory of Open Access Journals (Sweden)

    Sako H.

    2014-03-01

    Full Text Available H-dibaryon has been predicted as a stable 6-quark color-singlet state. It has been searched for by many experiments but has never been discovered. Recent lattice QCD calculations predict H-dibaryon as a weakly bound or a resonant state close to the LL threshold. E224 and E522 experiments at KEK observed peaks in LL invariant mass spectra near the threshold in (K-, K+ reactions, which were statistically not significant. Therefore, we proposed a new experiment E42 at J-PARC. It will measure decay products of ΛΛ and Λπ-p in a (K-, K+ reaction. We design a large acceptance spectrometer based on a Time Projection Chamber (TPC immersed in a dipole magnetic field. The TPC surrounds a target to cover nearly 4π acceptance, and accepts K- beams up to 106 counts per second. To suppress drift field distortion at high beam rates, we adopt Gas Electron Multipliers (GEMs for electron amplification and a gating grid. We show an overview of the experiment, the design of the spectrometer, and the R&D status of the TPC prototype.

  3. Simulation and Calibration of the ALICE TPC including innovative Space Charge Calculations

    CERN Document Server

    Rossegger, S; Riegler, W; Betev, L

    2009-01-01

    ALICE is one of the four main particle detectors located around the LHC accelerator at CERN. It is particularly designed to study the physics of the quark-gluon plasma by means of nucleus--nucleus collisions at center-of-mass energies up to 5.5 TeV per nucleon pair. A Time-Projection Chamber (TPC) was chosen to be its central-sub-detector due to its low mass properties and its capabilities to provide a robust and accurate Particle Identification even within ultra-high multiplicity environments (up to 8000 tracks per unit of eta). To achieve the required physics performance, the space point resolution of the TPC must be in the order of 0.2 mm. Due to its gigantic size of 5~m in diameter and 5~m in length, corrections for static as well as dynamic effects are indispensable in order to accomplish the design goal. The research presented covers all major issues relevant for the final calibration and therefore the enhancement of the TPC performance in terms of resolution. The main focus was to distinguish between t...

  4. Alpha-lipoic acid induces sodium iodide symporter expression in TPC-1 thyroid cancer cell line

    International Nuclear Information System (INIS)

    Introduction: Patients with metastatic thyroid cancers that do not uptake iodine need effective therapeutic option. Differentiation-inducing agents have been tried to restore functional expression of sodium iodide symporter (NIS) without success. Our objective was to assess the effect of alpha-lipoic acid (ALA), known as potential antioxidant, on expression of sodium iodide symporter in thyroid cancer cells. Methods: Human thyroid cancer-derived cell lines, TPC-1, were treated with ALA, and changes in NIS mRNA and protein expression were measured. ALA's effect on NIS gene promoter was evaluated, and functional NIS expression was assessed by iodide uptake assay. Results: Treatment with ALA increased NIS mRNA expression up to ten folds of control dose-dependently after 24 h of exposure. ALA increased NIS promoter activity, and increased iodide uptake by 1.6 fold. ALA induced expression of NIS protein, but had no significant effect on the plasma membrane trafficking. ALA increased phosphorylation of CREB and nuclear translocation of pCREB, and co-treatment of ALA and trichostatin A increased iodide uptake by three folds in TPC-1 cells. Conclusions: ALA is a potential agent to increase NIS transcription in TPC-1. It could be used as an adjunctive agent to increase efficacy of radioiodine therapy if combined with a strategy to increase NIS protein trafficking to cell membrane.

  5. Status of the R&D activities for the upgrade of the ALICE TPC

    CERN Document Server

    Deisting, Alexander

    2016-01-01

    In order to cope with the high interaction rates provided by the LHC after the long shut-down 2, the ALICE TPC needs to be upgraded. After the upgrade the TPC will run in a continuous mode, without any degradation of the momentum and $\\textrm{d}E/\\textrm{d}x$ resolution compared to the performance of the present TPC. Since readout by MWPCs is no longer feasible with these requirements, new technologies have to be employed. In the new readout the electron amplification is provided by a stack of four GEM foils. Here foils with a standard hole pitch of 140um as well as large pitch foils (280um) are used. Their high voltage settings and orientation have been optimised to provide an energy resolution of $\\sigma_{{E}}/{E}\\leq12\\%$ at the photopeak of $^{55}\\textrm{Fe}$. At the same settings the Ion BackFlow into the drift volume is less than 1% of the effective number of ions produced during gas amplification and the primary ionisations. This is necessary to prevent the accumulation of space charge, which eventuall...

  6. Recent measurements with the NIFFTE fission TPC and the potential to advance thorium fuelled reactors

    International Nuclear Information System (INIS)

    The NIFFTE Fission Time Projection Chamber (TPC) is a powerful tool that is being developed to take precision measurements of neutron-induced fission cross sections of transuranic elements. These improved data are needed for many applications including the development of future generations of nuclear reactors. During the last run at the Los Alamos Neutron Science Center (LANSCE) the fully instrumented TPC took data with several different targets for the first time. The exquisite tracking capabilities of this device allow the full reconstruction of charged particles produced by neutron beam induced fissions from a thin central target. The wealth of information gained from this approach will allow cross section systematics to be controlled at the level of 1%. Results from this run will be shared. These results are critical to the development of advanced uranium-fuelled reactors. However, there are clear advantages to developing thorium-fuelled reactors including the abundance of thorium verses uranium, minimizing radioactive waste, improved reactor safety, and enhanced proliferation resistance. The potential for using the NIFFTE fission TPC to measure needed cross sections important to the development of thorium fuelled nuclear reactors will also be discussed. (author)

  7. Studies of characteristics of triple GEM detector for the ALICE-TPC upgrade

    International Nuclear Information System (INIS)

    Gas Electron Multiplier (GEM) is a novel gas detector in the field of radiation detection. GEM detectors have tremendous advantages over other types gas detectors like high rate handling capability with high efficiency and very low ion back flow (IBF). These detectors are most suitable for the use in the future experiments in high-energy proton-proton and heavy-ion collisions at the Large Hadron Collider (LHC) at CERN and Facility for Antiproton and Ion Research (FAIR) at GSI. A Large Ion Collider Experiment (ALICE) at the LHC is a dedicated experiment for the study of Quark Gluon Plasma (QGP). In few years, the data taking rate for Pb-Pb collisions will increase by 100 times to 50 KHz. The ALICE Time Projection Chamber (TPC) is the main tracking detector in ALICE. It is planned that by the year 2018, GEM detectors will replace the present readout planes of TPC. The goal of the present study is to characterize the GEM detector to achieve the performance goal of the TPC

  8. Measurement of Gain and Drift Velocity of the Prototype AT-TPC

    Science.gov (United States)

    Wolff, Michael; Soussi Tanani, Rim; Cortesi, Marco; Mittig, Wolfgang; Fritsch, Adam

    2015-10-01

    The Prototype Active-Target Time-Projection Chamber (PAT-TPC) at the National Superconducting Cyclotron Laboratory (NSCL) is used to study reactions induced by radioactive ions in a detector gas that serves both as the target and tracking medium. It employs gaseous amplification of the primary electrons that drift to the amplification gap to track and measure charged particles traversing the active gaseous volume of the chamber. A setup consisting of two THGEMs (Thick Gas Electron Multipliers) stacked on a Micromegas (Micro mesh gas amplifier) device was tested in the PAT-TPC in June and July of 2015. A 337-Si laser, a 252Cf spontaneous fission source, and an α source were used to ionize target gas molecules in the active volume. Electron drift velocity was measured as a function of the electric field held across the volume and for varying gas compositions ranging from pure H2 to a 95:5 H2:C4H10 mixture. Analysis of the tests provided information on conditions for optimal gain for the setup used in an August 2015 PAT-TPC experiment at the University of Notre Dame's Nuclear Science Laboratory and other future experiments. Data and results will be presented. Funded in part thanks to College of Wooster and NSF Grant Nos. PHy-1430152, MRI09-23087, and PHY09-69456.

  9. Argon plasma irradiation of polypropylene

    International Nuclear Information System (INIS)

    Polypropylene samples were exposed to argon plasma discharge and the changes of the PP surface properties were studied by different methods. Surface wettability was derived from contact angle measured by standard goniometry and chemical structure of the plasma modified PP was studied using X-ray photoelectron spectroscopy (XPS) and by Rutherford backscattering spectroscopy (RBS), surface morphology and roughness of samples using AFM. Zeta potential of pristine and modified PP was determined with the SurPASS. The presence of incorporated oxygen in the PP surface layer, about 60 nm thick, was observed in RBS spectra. Oxygen concentration is a decreasing function of the depth. With progressing aging time the oxygen concentration on the PP surface decreases. Plasma treatment results in a rapid decrease of the contact angle, which increases again with increasing aging time. In XPS measurement the oxygen containing structures, created by the plasma treatment, were found on the very surface of the modified PP and the zeta potential being changed too. The significant difference in zeta potential between pristine and plasma treated PP clearly indicates that the plasma treatment leads to a more hydrophilic PP surface.

  10. Status and perspecitves of liquid argon calorimeters

    International Nuclear Information System (INIS)

    The status of liquid argon calorimeters is reviewed, and experience obtained with these devices is described. Future perspectives of the liquid ionization chamber technique in calorimetry are also discussed. (orig.)

  11. Clinical periodontics with the argon laser

    Science.gov (United States)

    Finkbeiner, R. L.

    1995-04-01

    The argon laser has proven to be a valuable tool for the thermodynamic debridement of the periodontal lesion, incisions and tissue fusion. Illustrations of clinical applications and discussion of laser parameters will be provided.

  12. Liquid argon neutrals detector (LAND) for PEP

    International Nuclear Information System (INIS)

    The physical effects limiting the gamma energy resolution of a liquid argon calorimeter without passive converter plates is discussed. An example of such a detector based on the General User's Magnet designed at this Summer Study is given

  13. Opacity of Shock-Generated Argon Plasmas

    Institute of Scientific and Technical Information of China (English)

    王藩侯; 陈敬平; 周显明; 李西军; 经福谦; 孟续军; 孙永盛

    2001-01-01

    Argon plasmas with uniform density and temperature are generated by a planar shock wave through argon gas. The opacities of argon plasma, covering the thermodynamic states at temperatures of 1.4-2.2eV and in densities of 0.0083- 0.015 g/cm3, are investigated by measuring the emitted radiance versus time at several visible wavelengths. Comparison of the measured opacities with those calculated demonstrates that the average atom model can be used well to describe the essential transport behaviour of photons in argon plasma under the abovementioned thermodynamic condition. A simplified and self-consistent method to deduce the reflectivity R(λ) at the baseplate surface is applied. It demonstrates that the values of R(λ) are all around 0.4 in the experiments, which are basically in agreement with those given by Erskine previously (1994 J. Quant. Spectrosc. Radiat.Transfer 51 97).

  14. 21 CFR 868.1075 - Argon gas analyzer.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Argon gas analyzer. 868.1075 Section 868.1075 Food... DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1075 Argon gas analyzer. (a) Identification. An argon gas analyzer is a device intended to measure the concentration of argon in a gas mixture to aid...

  15. Negative corona current pulses in argon and in mixture argon with SF6

    International Nuclear Information System (INIS)

    Waveforms of the first negative current pulses in a short negative point-to plane gap in pure argon and argon with SF6 admixture have been investigated with a nanosecond time resolution at a gas pressure 50 kPa as a function of applied gap voltage and content of SF6 in the mixture. We have made an attempt to explain the differences in the discharge development in pure argon and in argon with admixture of SF6 based on the observed changes of the pulse shape. The experimental results obtained will be discussed in context with existing computer simulation models (Authors)

  16. Measurements on scintillation light from liquid argon

    International Nuclear Information System (INIS)

    It is shown that an argon calorimeter can operate as a scintillation detector, provided that xenon is added. With the addition of 170 ppm xenon a light yield of 70% has been obtained. In addition the light yield is determined under influence of an electric field, from differently ionising particles and by the use of aluminium mirrors acting as light guides. Finally first measurements with a photomultiplier working at liquid argon temperatures are reported. (orig.)

  17. Improved background rejection in neutrinoless double beta decay experiments using a magnetic field in a high pressure xenon TPC

    CERN Document Server

    Renner, J; Hernando, J A; Imzaylov, A; Monrabal, F; Muñoz, J; Nygren, D; Gomez-Cadenas, J J

    2015-01-01

    We demonstrate that the application of an external magnetic field could lead to an improved background rejection in neutrinoless double-beta (0nbb) decay experiments using a high pressure xenon (HPXe) TPC. HPXe chambers are capable of imaging electron tracks, a feature that enhances the separation between signal events (the two electrons emitted in the 0nbb decay of 136Xe) and background events, arising chiefly from single electrons of kinetic energy compatible with the end-point of the 0nbb decay (Qbb ). Applying an external magnetic field of sufficiently high intensity (in the range of 0.5-1 Tesla for operating pressures in the range of 5-15 atmospheres) causes the electrons to produce helical tracks. Assuming the tracks can be properly reconstructed, the sign (direction) of curvature can be determined at several points along these tracks, and such information can be used to separate signal (0nbb) events containing two electrons producing a track with two different directions of curvature from background (s...

  18. Potassium-argon/argon-40-argon-39 geochronology of Cenozoic alkali basalts from the South China Sea

    Institute of Scientific and Technical Information of China (English)

    YAN Quanshu; SHI Xuefa; YANG Yaomin; WANG Kunshan

    2008-01-01

    Based on the isotopic chronologic results of Cenozoic alkali basalts from the South China Sea,the characteristics of volcanic activi-ty of the South China Sea after spreading were studied.The potassium - argon ages of eight alkali basalt samples from the South China Sea,and the argon - argon ages of two samples among them are reported.Apparent ages of the whole rock are 3.80 to 7.91 Ma with an average value of 5.43 Ma (potassium- argon,whole rock),and there is little difference among samples at the same location,e.g.,4.76~5.78 Ma for location S04-12.The argon - argon ages for the two samples are 6.06 and 4.71 Ma,which lie within the age scope of potassium - argon method.The dating results indicate that rock-forming age is from late Miocene to Pli-ocene,which is consistent with erupting event for alkali basalts from adjacent regions of the South China Sea.Volcanic activities occur after the cessation of spreading of the South China Sea,which are controlled by lithospheric fault and the spreading center formed during the spreading period of the South China Sea.These dating results,combined with geochemical characteristics of these basalts,the published chronological data for the South China Sea and its adjacent regions,and the updated geophysical data near Hainan Island,suggest that after the cessation of spreading of the South China Sea,there occur widely distributing magmatic activities which primarily is alkali basalt,and the volcanic activity continues to Quaternary.The activity may be relative to Hainan mantle plume originated from core/mantle boundary.

  19. Argon Collection And Purification For Proliferation Detection

    Energy Technology Data Exchange (ETDEWEB)

    Achey, R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hunter, D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-10-09

    In order to determine whether a seismic event was a declared/undeclared underground nuclear weapon test, environmental samples must be taken and analyzed for signatures that are unique to a nuclear explosion. These signatures are either particles or gases. Particle samples are routinely taken and analyzed under the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) verification regime as well as by individual countries. Gas samples are analyzed for signature gases, especially radioactive xenon. Underground nuclear tests also produce radioactive argon, but that signature is not well monitored. A radioactive argon signature, along with other signatures, can more conclusively determine whether an event was a nuclear test. This project has developed capabilities for collecting and purifying argon samples for ultra-low-background proportional counting. SRNL has developed a continuous gas enrichment system that produces an output stream containing 97% argon from whole air using adsorbent separation technology (the flow diagram for the system is shown in the figure). The vacuum swing adsorption (VSA) enrichment system is easily scalable to produce ten liters or more of 97% argon within twelve hours. A gas chromatographic separation using a column of modified hydrogen mordenite molecular sieve has been developed that can further purify the sample to better than 99% purity after separation from the helium carrier gas. The combination of these concentration and purification systems has the capability of being used for a field-deployable system for collecting argon samples suitable for ultra-low-background proportional counting for detecting nuclear detonations under the On-Site Inspection program of the CTBTO verification regime. The technology also has applications for the bulk argon separation from air for industrial purposes such as the semi-conductor industry.

  20. Kinetic and experimental study of argon and argon--nitrogen mixtures excited by fission fragments

    International Nuclear Information System (INIS)

    Optical emission from argon and argon-nitrogen mixtures excited by fission fragments are studied in an effort to better understand the fission fragment energy deposition into the gas. A model of the energy flow in the gas is developed and compared with the experimental results

  1. Argon activation analysis, application to dating by the potassium-argon method

    International Nuclear Information System (INIS)

    Activation analysis using radiogenic argon-40 has been applied to rock-dating by the K-Ar method. The argon is extracted from the sample, purified, activated to saturation in a flux of 2 X 1013 neutrons/cm2 sec-1 and measured by gamma spectroscopy. The sensitivity obtained is such that it is possible to measure amounts of argon corresponding to age of a few thousand years only. However since it has not been possible to measure the amount of pollution of radiogenic argon by atmospheric argon with any accuracy, the measurable age limit is in fact of the order of MY. The method has been applied to basalts from the Mont-Dore region. The results obtained are in fairly good agreement with geological, stratigraphic and paleomagnetic data. (author)

  2. Attenuation of vacuum ultraviolet light in liquid argon

    CERN Document Server

    Neumeier, A; Oberauer, L; Potzel, W; Schönert, S; Dandl, T; Heindl, T; Ulrich, A; Wieser, J

    2015-01-01

    The transmission of liquid argon has been measured, wavelength resolved, for a wavelength interval from 118 to 250 nm. The wavelength dependent attenuation length is presented for pure argon. It is shown that no universal wavelength independent attenuation length can be assigned to liquid argon for its own fluorescence light due to the interplay between the wavelength dependent emission and absorption. A decreasing transmission is observed below 130 nm in both chemically cleaned and distilled liquid argon and assigned to absorption by the analogue of the first argon excimer continuum. For not perfectly cleaned argon a strong influence of impurities on the transmission is observed. Two strong absorption bands at 126.5 and 141.0 nm with approximately 2 and 4 nm width, respectively, are assigned to traces of xenon in argon. A broad absorption region below 180 nm is found for unpurified argon and tentatively attributed to the presence of water in the argon sample.

  3. New gas mixtures suitable for rare event detection using a Micromegas-TPC detector

    International Nuclear Information System (INIS)

    The aim of the presented work was to develop further techniques based on a Micromegas-TPC, in order to reach a high gas gain with good energy resolution, and to search for gas mixtures suitable for rare event detection. This paper focuses on Xenon, which is convenient for the search of neutrinoless double beta decay in 136Xe, and CF4, suitable for dark matter searches and the study of solar and reactor neutrinos. Various configurations of the Micromegas plane were investigated and are described. Gains of 105 and energy resolutions of 35-65% at 6 keV have been achieved.

  4. New gas mixtures suitable for rare event detection using a Micromegas-TPC detector

    Energy Technology Data Exchange (ETDEWEB)

    Ounalli, L; Vuilleumier, J-L; Schenker, D; Vuilleumier, J-M [Laboratory for Particle Physics, A.L. Breguet 1, CH-2000 Neuchatel (Switzerland)], E-mail: leila.ounalli@unine.ch

    2009-01-15

    The aim of the presented work was to develop further techniques based on a Micromegas-TPC, in order to reach a high gas gain with good energy resolution, and to search for gas mixtures suitable for rare event detection. This paper focuses on Xenon, which is convenient for the search of neutrinoless double beta decay in {sup 136}Xe, and CF{sub 4}, suitable for dark matter searches and the study of solar and reactor neutrinos. Various configurations of the Micromegas plane were investigated and are described. Gains of 10{sup 5} and energy resolutions of 35-65% at 6 keV have been achieved.

  5. Silicon ion interactions measured in the E-810 TPC at the AGS

    International Nuclear Information System (INIS)

    The tracking detector of AGS Experiment 810 is a three-piece Time Projection Chamber (TPC) which measures all charged tracks in the forward hemisphere of the nucleon-nucleon center of mass system, i.e. forward of 20 degrees in the lab. A cut at multiplicity 50 was used to select more central collisions, yielding 2291 events from the gold sample, 2170 from the copper. This corresponds to cross sections of 0.59 and 0.20 barns, respectively, defining the 'central' sample for the charged particle distributions presented here. (orig./HSI)

  6. Studies on Gas Electron Multiplier (GEM) modules for a Large Prototype TPC for the ILC

    OpenAIRE

    Tsionou, Dimitra

    2015-01-01

    The International Large Detector is a detector concept for the ILC which uses a Time Projection Chamber as its the main tracker. Within the framework of the LCTPC collaboration, a Large Prototype (LP) TPC has been built as a demonstrator. Its endplate is able to contain up to seven identical modules of Micro-Pattern Gas Detectors (MPGD). The LP has been equipped with MPGD modules and studied with an electron beam (1-6 GeV) in a 1 Tesla magnetic field.The interest of this talk lies in the stud...

  7. First performance results of the ALICE TPC Readout Control Unit 2

    Science.gov (United States)

    Zhao, C.; Alme, J.; Alt, T.; Appelshäuser, H.; Bratrud, L.; Castro, A.; Costa, F.; David, E.; Gunji, T.; Kirsch, S.; Kiss, T.; Langøy, R.; Lien, J.; Lippmann, C.; Oskarsson, A.; Rehman, A. Ur; Røed, K.; Röhrich, D.; Sekiguchi, Y.; Stuart, M.; Ullaland, K.; Velure, A.; Yang, S.; Österman, L.

    2016-01-01

    This paper presents the first performance results of the ALICE TPC Readout Control Unit 2 (RCU2). With the upgraded hardware typology and the new readout scheme in FPGA design, the RCU2 is designed to achieve twice the readout speed of the present Readout Control Unit. Design choices such as using the flash-based Microsemi Smartfusion2 FPGA and applying mitigation techniques in interfaces and FPGA design ensure a high degree of radiation tolerance. This paper presents the system level irradiation test results as well as the first commissioning results of the RCU2. Furthermore, it will be concluded with a discussion of the planned updates in firmware.

  8. Quality assurance of GEM foils in the framework of the TPC upgrade in the ALICE experiment

    CERN Document Server

    Ozcelik, Melih Arslan

    2016-01-01

    In the framework of the TPC upgrade of the ALICE Experiment, new readout chambers will be installed during the LHC long shutdown 2, which is scheduled to start in July 2018. The current MWPCs (Multi Wire Proportional Chambers) will be replaced by readout chambers consisting of GEM (Gas Electron Multipliers) foils in order to meet the increasing readout rate requirements. QA (Quality Assurance) tests on the GEMs are performed to classify the foils. In this report we present the work done during the CERN Summer Student Programme 2016.

  9. Performance of MPGD-based TPC prototypes for the linear collider experiment

    International Nuclear Information System (INIS)

    We conducted a series of beam tests of prototype TPCs for the International Linear Collider (ILC) experiment, equipped with an MWPC, a MicroMEGAS, or GEMs as a readout device. The prototype operated successfully in a test beam at KEK under an axial magnetic field of up to 1 T. The analysis of data is now in progress and some of the preliminary results obtained with GEMs and MicroMEGAS are presented along with our interpretation. Also given is the extrapolation of the obtained spatial resolution to that of a large TPC expected as the central tracker of the ILC experiment

  10. Solar neutrino detection in a large volume double-phase liquid argon experiment

    Science.gov (United States)

    Franco, D.; Giganti, C.; Agnes, P.; Agostino, L.; Bottino, B.; Canci, N.; Davini, S.; De Cecco, S.; Fan, A.; Fiorillo, G.; Galbiati, C.; Goretti, A. M.; Hungerford, E. V.; Ianni, Al.; Ianni, An.; Jollet, C.; Marini, L.; Martoff, C. J.; Meregaglia, A.; Pagani, L.; Pallavicini, M.; Pantic, E.; Pocar, A.; Razeti, M.; Renshaw, A. L.; Rossi, B.; Rossi, N.; Suvorov, Y.; Testera, G.; Tonazzo, A.; Wang, H.; Zavatarelli, S.

    2016-08-01

    Precision measurements of solar neutrinos emitted by specific nuclear reaction chains in the Sun are of great interest for developing an improved understanding of star formation and evolution. Given the expected neutrino fluxes and known detection reactions, such measurements require detectors capable of collecting neutrino-electron scattering data in exposures on the order of 1 ktonne-yr, with good energy resolution and extremely low background. Two-phase liquid argon time projection chambers (LAr TPCs) are under development for direct Dark Matter WIMP searches, which possess very large sensitive mass, high scintillation light yield, good energy resolution, and good spatial resolution in all three cartesian directions. While enabling Dark Matter searches with sensitivity extending to the ``neutrino floor'' (given by the rate of nuclear recoil events from solar neutrino coherent scattering), such detectors could also enable precision measurements of solar neutrino fluxes using the neutrino-electron elastic scattering events. Modeling results are presented for the cosmogenic and radiogenic backgrounds affecting solar neutrino detection in a 300 tonne (100 tonne fiducial) LAr TPC operating at LNGS depth (3,800 meters of water equivalent). The results show that such a detector could measure the CNO neutrino rate with ~15% precision, and significantly improve the precision of the 7Be and pep neutrino rates compared to the currently available results from the Borexino organic liquid scintillator detector.

  11. Scintillation efficiency of liquid argon in low energy neutron-argon scattering

    International Nuclear Information System (INIS)

    Experiments searching for weak interacting massive particles with noble gases such as liquid argon require very low detection thresholds for nuclear recoils. A determination of the scintillation efficiency is crucial to quantify the response of the detector at low energy. We report the results obtained with a small liquid argon cell using a monoenergetic neutron beam produced by a deuterium-deuterium fusion source. The light yield relative to electrons was measured for six argon recoil energies between 11 and 120 keV at zero electric drift field

  12. Gas Gain Measurements from a Negative Ion TPC X-ray Polarimeter

    CERN Document Server

    Prieskorn, Z; Kaaret, P E; Black, J K; Jahoda, K

    2011-01-01

    Gas-based time projection chambers (TPCs) have been shown to be highly sensitive X-ray polarimeters having excellent quantum efficiency while at the same time achieving large modulation factors. To observe polarization of the prompt X-ray emission of a Gamma-ray burst (GRB), a large area detector is needed. Diffusion of the electron cloud in a standard TPC could be prohibitive to measuring good modulation when the drift distance is large. Therefore, we propose using a negative ion TPC (NITPC) with Nitromethane (CH3NO2) as the electron capture agent. The diffusion of negative ions is reduced over that of electrons due to the thermal coupling of the negative ions to the surrounding gas. This allows for larger area detectors as the drift distance can be increased without degrading polarimeter modulation. Negative ions also travel ~200 times slower than electrons, allowing the readout electronics to operate slower, resulting in a reduction of instrument power. To optimize the NITPC design, we have measured gas ga...

  13. R and D on a Fast LXe TPC with real-time event reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Dussoni, S., E-mail: simeone.dussoni@pi.infn.it [INFN Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Baldini, A. [INFN Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Galli, L. [INFN Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Paul Scherrer Institute PSI, CH-5232 Villigen (Switzerland); Cerri, C.; Grassi, M. [INFN Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Papa, A. [Paul Scherrer Institute PSI, CH-5232 Villigen (Switzerland); Signorelli, G. [INFN Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy)

    2013-12-21

    The FOXFIRE project (Feasibility Of a Xenon detector with Front-end for Ionization Real-time Extraction) aims at the realization of a Liquid Xenon TPC optimized for high rate particle physics experiments, in particular in the field of rare event searches, with particles in the 10–100 MeV energy range. Liquid Xenon has several attractive properties to be exploited resulting in superior time and energy resolution, by using the scintillation light readout with suitable photo-detectors. A novel approach with a complementary TPC readout scheme can improve the space resolution to a level of a few hundred microns. We are studying both the feasibility of a light readout with higher granularity by means of Silicon PhotoMultipliers optimized for the Xenon emission spectrum as well as on an innovative micro-fabricated device capable of charge multiplication in liquid phase. The detector will be equipped with a readout electronics capable of online reconstruction of events, allowing the detector to sustain a high rate of interactions.

  14. A Time Projection Chamber for High-Rate Experiments: Towards an Upgrade of the ALICE TPC

    CERN Document Server

    Ketzer, Bernhard

    2013-01-01

    A Time Projection Chamber (TPC) is a powerful detector for 3-dimensional tracking and particle identification for ultra-high multiplicity events. It is the central tracking device of many experiments, e.g. the ALICE experiment at CERN. The necessity of a switching electrostatic gate, which prevents ions produced in the amplification region o MWPCs from entering the drift volume, however, restricts its application to trigger rates of the order of 1 kHz. Charge amplification by Gas Electron Multiplier (GEM) foils instead of proportional wires offers an intrinsic suppression of the ion backflow, although not to the same level as a gating grid. Detailed Monte Carlo simulations have shown that the distortions due to residual space charge from back-drifting ions can be limited to a few cm, and thus can be corrected using standard calibration techniques. A prototype GEM-TPC has been built with the largest active volume to date for a detector of this type. It has been commissioned with cosmics and particle beams at t...

  15. ALICE HLT TPC Tracking of Pb-Pb Events on GPUs

    International Nuclear Information System (INIS)

    The online event reconstruction for the ALICE experiment at CERN requires processing capabilities to process central Pb-Pb collisions at a rate of more than 200 Hz, corresponding to an input data rate of about 25 GB/s. The reconstruction of particle trajectories in the Time Projection Chamber (TPC) is the most compute intensive step. The TPC online tracker implementation combines the principle of the cellular automaton and the Kalman filter. It has been accelerated by the usage of graphics cards (GPUs). A pipelined processing allows to perform the tracking on the GPU, the data transfer, and the preprocessing on the CPU in parallel. In order for CPU pre- and postprocessing to keep step with the GPU the pipeline uses multiple threads. A splitting of the tracking in multiple phases searching for short local track segments first improves data locality and makes the algorithm suited to run on a GPU. Due to special optimizations this course of action is not second to a global approach. Because of non-associative floating-point arithmetic a binary comparison of GPU and CPU tracker is infeasible. A track by track and cluster by cluster comparison shows a concordance of 99.999%. With current hardware, the GPU tracker outperforms the CPU version by about a factor of three leaving the processor still available for other tasks.

  16. The PreAmplifier ShAper for the ALICE TPC-Detector

    CERN Document Server

    Soltveit, H K; Braun-Munzinger, P; Musa, L; Gustafsson, H A; Bonnes, U; Oeschler, H; Osterman, L; Lang, S

    2012-01-01

    In this paper the PreAmplifier ShAper (PASA) for the Time Projection Chamber (TPC) of the ALICE experiment at LHC is presented. The ALICE TPC PASA is an ASIC that integrates 16 identical channels, each consisting of Charge Sensitive Amplifiers (CSA) followed by a Pole-Zero network, self-adaptive bias network, two second-order bridged-T filters, two non-inverting level shifters and a start-up circuit. The circuit is optimized for a detector capacitance of 18-25 pF. For an input capacitance of 25 pF, the PASA features a conversion gain of 12.74 mV/fC, a peaking time of 160 ns, a FWHM of 190 ns, a power consumption of 11.65 mW/ch and an equivalent noise charge of 244e + 17e/pF. The circuit recovers smoothly to the baseline in about 600 ns. An integral non-linearity of 0.19% with an output swing of about 2.1 V is also achieved. The total area of the chip is 18 mm$^2$ and is implemented in AMS's C35B3C1 0.35 micron CMOS technology. Detailed characterization test were performed on about 48000 PASA circuits before m...

  17. Structure, inhibition and regulation of two-pore channel TPC1 from Arabidopsis thaliana.

    Science.gov (United States)

    Kintzer, Alexander F; Stroud, Robert M

    2016-03-10

    Two-pore channels (TPCs) comprise a subfamily (TPC1-3) of eukaryotic voltage- and ligand-gated cation channels with two non-equivalent tandem pore-forming subunits that dimerize to form quasi-tetramers. Found in vacuolar or endolysosomal membranes, they regulate the conductance of sodium and calcium ions, intravesicular pH, trafficking and excitability. TPCs are activated by a decrease in transmembrane potential and an increase in cytosolic calcium concentrations, are inhibited by low luminal pH and calcium, and are regulated by phosphorylation. Here we report the crystal structure of TPC1 from Arabidopsis thaliana at 2.87 Å resolution as a basis for understanding ion permeation, channel activation, the location of voltage-sensing domains and regulatory ion-binding sites. We determined sites of phosphorylation in the amino-terminal and carboxy-terminal domains that are positioned to allosterically modulate cytoplasmic Ca(2+) activation. One of the two voltage-sensing domains (VSD2) encodes voltage sensitivity and inhibition by luminal Ca(2+) and adopts a conformation distinct from the activated state observed in structures of other voltage-gated ion channels. The structure shows that potent pharmacophore trans-Ned-19 (ref. 17) acts allosterically by clamping the pore domains to VSD2. In animals, Ned-19 prevents infection by Ebola virus and other filoviruses, presumably by altering their fusion with the endolysosome and delivery of their contents into the cytoplasm. PMID:26961658

  18. The vacuolar Ca2+-activated channel TPC1 regulates germination and stomatal movement.

    Science.gov (United States)

    Peiter, Edgar; Maathuis, Frans J M; Mills, Lewis N; Knight, Heather; Pelloux, Jérôme; Hetherington, Alistair M; Sanders, Dale

    2005-03-17

    Cytosolic free calcium ([Ca2+]cyt) is a ubiquitous signalling component in plant cells. Numerous stimuli trigger sustained or transient elevations of [Ca2+]cyt that evoke downstream stimulus-specific responses. Generation of [Ca2+]cyt signals is effected through stimulus-induced opening of Ca2+-permeable ion channels that catalyse a flux of Ca2+ into the cytosol from extracellular or intracellular stores. Many classes of Ca2+ current have been characterized electrophysiologically in plant membranes. However, the identity of the ion channels that underlie these currents has until now remained obscure. Here we show that the TPC1 ('two-pore channel 1') gene of Arabidopsis thaliana encodes a class of Ca2+-dependent Ca2+-release channel that is known from numerous electrophysiological studies as the slow vacuolar channel. Slow vacuolar channels are ubiquitous in plant vacuoles, where they form the dominant conductance at micromolar [Ca2+]cyt. We show that a tpc1 knockout mutant lacks functional slow vacuolar channel activity and is defective in both abscisic acid-induced repression of germination and in the response of stomata to extracellular calcium. These studies unequivocally demonstrate a critical role of intracellular Ca2+-release channels in the physiological processes of plants. PMID:15772667

  19. Design, construction and test of a precursor prototype TPC for PANDA

    International Nuclear Information System (INIS)

    A time projection chamber (TPC) is a very promising option for the central tracker of the PANDA experiment at the new Facility for Antiproton and Ion Research (FAIR) at Darmstadt, Germany. Installed in a ring-type experiment with 2.107 p anti p annihilations per second it has to be operated continuously despite the presence of space charge effects. These are kept at a bearable level using GEM-based amplification providing an intrinsic suppression of ion backflow. The system promises high-accuracy tracking as well as information on the specific energy-loss and features high momentum resolution of 1% as well as particle-identification capability with a highly homogeneous and low material budget. As a precursor prototype of a PANDA TPC a large-volume detector with a ring-cylindrical shape of the drift volume of 73 cm length and active diameters of 10/30 cm has been set up. Three GEM foils serve as an amplification stage. The signals of approximately 10.000 hexagonal pads are read out using 42 front end cards. In this contribution, we present the design and construction of the detector system and we report on the results of its commissioning.

  20. A pixel TPC for the linear collider. A testbeam with the demonstrator

    Energy Technology Data Exchange (ETDEWEB)

    Lupberger, Michael [Universitaet Bonn (Germany); Collaboration: LCTPC-Deutschland-Collaboration

    2015-07-01

    A Time Projection Chamber (TPC) is foreseen as tracker for the ILD, one of the two detector concepts at the planned International Linear Collider (ILC). At the TPC endplates, Micromegas or GEMs will be used as gas amplification structure. Besides segmented anodes, also an active endplate with pixel ASICs is considered as a readout option. We use the Timepix chip as readout ASIC in our experiments. In a photolithographic process a grid has been produced on top of the chip to form a so called InGrid, which is a Micromegas-like detector. An endplate module with an array of eight InGrids has been tested as readout of a prototype time projection chamber at DESY in March 2013. Meanwhile, a complete module has been equipped with 96 InGrid chips. 50% of the module surface is covered with pixels, resulting in 6.2 million readout channels. For that reason, the readout system was largely extended, also using the scalability that it provides. This final design of the module and readout system, including data transfer and concentration, cooling, low and high voltage distribution will be tested in another testbeam campaign at the beginning of 2015. Design choices, implementations and impressions from the construction and commissioning phase are presented.

  1. Contraction ionization waves in the argon contracted discharge

    International Nuclear Information System (INIS)

    An investigation of ionization waves in the argon contracted discharge and a definition of their arising propagation mechanism accounting for the specificity of elementary pocesses characteristic of argon are presented. (author)

  2. Thermal decomposition of barium valerate in argon

    DEFF Research Database (Denmark)

    Torres, P.; Norby, Poul; Grivel, Jean-Claude

    2015-01-01

    The thermal decomposition of barium valerate (Ba(C4H9CO2)(2)/Ba-pentanoate) was studied in argon by means of thermogravimetry, differential thermal analysis, IR-spectroscopy, X-ray diffraction and hot-stage optical microscopy. Melting takes place in two different steps, at 200 degrees C and 280...

  3. Argon-ion contamination of the plasmasphere

    International Nuclear Information System (INIS)

    This paper applies present observational and analytic knowledge on effects of plasma beam interaction wth the magnetosphere to the plasmasphere contamination problem of the argon ion engine exhaust expected to be deposited in the magnetosphere during the construction phase of the Satellite Power System. Effects of plasmasphere, ionosphere, and radiation belt modifications are discussed

  4. Near-infrared scintillation of liquid argon

    Science.gov (United States)

    Alexander, T.; Escobar, C. O.; Lippincott, W. H.; Rubinov, P.

    2016-03-01

    Since the 1970s it has been known that noble gases scintillate in the near infrared (NIR) region of the spectrum (0.7 μm motivation for using the NIR scintillation in liquid argon detectors, then briefly review early as well as more recent efforts and finally show encouraging preliminary results of a test performed at Fermilab.

  5. Silicon compounds of neon and argon

    Czech Academy of Sciences Publication Activity Database

    Roithová, J.; Schröder, Detlef

    -, č. 46 (2009), s. 8788-8790. ISSN 1433-7851 R&D Projects: GA ČR GA203/09/1223 Grant ostatní: ERC(XE) Adg HORIZOMS Institutional research plan: CEZ:AV0Z40550506 Keywords : argon * bond formation * dications * neon Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 11.829, year: 2009

  6. Argon Laser Treatment of Strawberry Hemangioma in Infancy

    OpenAIRE

    Achauer, Bruce M.; Vander Kam, Victoria M.

    1985-01-01

    Argon laser therapy is effective for removing port-wine stains and for reducing cutaneous vascular and pigmented lesions. Strawberry hemangiomas, being much thicker lesions than port-wine stains, were considered not appropriate for argon laser treatment. Using argon laser therapy in 13 cases of strawberry hemangioma, we achieved poor to dramatic results.

  7. Absence of intracellular ion channels TPC1 and TPC2 leads to mature-onset obesity in male mice, due to impaired lipid availability for thermogenesis in brown adipose tissue.

    Science.gov (United States)

    Lear, Pamela V; González-Touceda, David; Porteiro Couto, Begoña; Viaño, Patricia; Guymer, Vanessa; Remzova, Elena; Tunn, Ruth; Chalasani, Annapurna; García-Caballero, Tomás; Hargreaves, Iain P; Tynan, Patricia W; Christian, Helen C; Nogueiras, Rubén; Parrington, John; Diéguez, Carlos

    2015-03-01

    Intracellular calcium-permeable channels have been implicated in thermogenic function of murine brown and brite/beige adipocytes, respectively transient receptor potential melastin-8 and transient receptor potential vanilloid-4. Because the endo-lysosomal two-pore channels (TPCs) have also been ascribed with metabolic functionality, we studied the effect of simultaneously knocking out TPC1 and TPC2 on body composition and energy balance in male mice fed a chow diet. Compared with wild-type mice, TPC1 and TPC2 double knockout (Tpcn1/2(-/-)) animals had a higher respiratory quotient and became obese between 6 and 9 months of age. Although food intake was unaltered, interscapular brown adipose tissue (BAT) maximal temperature and lean-mass adjusted oxygen consumption were lower in Tpcn1/2(-/-) than in wild type mice. Phosphorylated hormone-sensitive lipase expression, lipid density and expression of β-adrenergic receptors were also lower in Tpcn1/2(-/-) BAT, whereas mitochondrial respiratory chain function and uncoupling protein-1 expression remained intact. We conclude that Tpcn1/2(-/-) mice show mature-onset obesity due to reduced lipid availability and use, and a defect in β-adrenergic receptor signaling, leading to impaired thermogenic activity, in BAT. PMID:25545384

  8. Liquid argon scintillation read-out with silicon devices

    International Nuclear Information System (INIS)

    Silicon photosensors represent a viable alternative to standard photomultipliers in fields such as communications and medical imaging. We explored the interesting possibility of using these sensors in combination with liquid argon (LAr) for astroparticle physics applications such as neutrino, dark matter and double beta decay experiments. In fact, silicon photosensors have detection efficiencies comparable with those of the highest performance PMTs and can be manufactured with high level of radiopurity. In particular within the on-going R and D activity of the SILENT project (Low background and low noise techniques for double beta decay physics funded by ASPERA) a large area SiPM (Silicon PhotoMultiplier - Hamamatsu S11828-3344M - 1.7 cm2 area) has been installed in a LAr scintillation chamber of 0.5 liters volume together with a cryogenic photomultiplier tube (Hamamatsu R11065) used as a reference. The liquid argon chamber has been exposed to many gamma sources of different energies and single photoelectron response and light yield for the SiPM and PMT have been measured and compared. In this contribution the results of the tests, and the ongoing R and D to optimize the SiPM for cryogenic and for ultralow background applications, are reported, as well as the possible application in the GERDA experiment on Double Beta Decay Searches of 76Ge

  9. Liquid argon scintillation read-out with silicon devices

    Science.gov (United States)

    Canci, N.; Cattadori, C.; D'Incecco, M.; Lehnert, B.; Machado, A. A.; Riboldi, S.; Sablone, D.; Segreto, E.; Vignoli, C.

    2013-10-01

    Silicon photosensors represent a viable alternative to standard photomultipliers in fields such as communications and medical imaging. We explored the interesting possibility of using these sensors in combination with liquid argon (LAr) for astroparticle physics applications such as neutrino, dark matter and double beta decay experiments. In fact, silicon photosensors have detection efficiencies comparable with those of the highest performance PMTs and can be manufactured with high level of radiopurity. In particular within the on-going R&D activity of the SILENT project (Low background and low noise techniques for double beta decay physics funded by ASPERA) a large area SiPM (Silicon PhotoMultiplier - Hamamatsu S11828-3344M - 1.7 cm2 area) has been installed in a LAr scintillation chamber of 0.5 liters volume together with a cryogenic photomultiplier tube (Hamamatsu R11065) used as a reference. The liquid argon chamber has been exposed to many gamma sources of different energies and single photoelectron response and light yield for the SiPM and PMT have been measured and compared. In this contribution the results of the tests, and the ongoing R&D to optimize the SiPM for cryogenic and for ultralow background applications, are reported, as well as the possible application in the GERDA experiment on Double Beta Decay Searches of 76Ge.

  10. Building a large-area GEM-based readout chamber for the upgrade of the ALICE TPC

    CERN Document Server

    Gasik, Piotr

    2016-01-01

    A large Time Projection Chamber (TPC) is the main device for tracking and charged-particle identification in the ALICE experiment at the CERN LHC. After the second long shutdown in 2019-2020, the LHC will deliver Pb beams colliding at an interaction rate up to 50 kHz, which is about a factor of 100 above the present read-out rate of the TPC. To fully exploit the LHC potential the TPC will be upgraded based on the Gas Electron Multiplier (GEM) technology. A prototype of an ALICE TPC Outer Read-Out Chamber (OROC) was equipped with twelve large-size GEM foils as amplification stage to demonstrate the feasibility of replacing the current Multi Wire Proportional Chambers with the new technology. With a total area of $\\sim$0.76 m$^2$ it is the largest GEM-based detector built to date. The GEM OROC was installed within a test field cage and commissioned with radioactive sources.

  11. Directional detection of Dark Matter with the MIcro-tpc MAtrix of Chambers

    CERN Document Server

    Couturier, C; Naraghi, F; Riffard, Q; Santos, D; Sauzet, N; Colas, P; Ribas, E Ferrer; Giomataris, I; Busto, J; Fouchez, D; Tao, C; Zhou, N

    2016-01-01

    Particles weakly interacting with ordinary matter, with an associated mass of the order of an atomic nucleus (WIMPs), are plausible candidates for Dark Matter. The direct detection of an elastic collision of a target nuclei induced by one of these WIMPs has to be discriminated from the signal produced by the neutrons, which leaves the same signal in a detector. The MIMAC (MIcro-tpc MAtrix of Chambers) collaboration has developed an original prototype detector which combines a large pixelated Micromegas coupled with a fast, self-triggering, electronics. Aspects of the two-chamber module in operation in the Modane Underground Laboratory are presented: calibration, characterization of the $^{222}$Rn progeny. A new test bench combining a MIMAC chamber with the COMIMAC portable quenching line has been set up to characterize the 3D tracks of low energy ions in the MIMAC gas mixture: the preliminary results thereof are presented. Future steps are briefly discussed.

  12. Meson and baryon correlation studies using the PEP-TPC/2γ Facility

    International Nuclear Information System (INIS)

    Results on vector meson, and strange and charmed-baryon production are presented for data taken during the period 1982--1986 using the TPC/2γ detector at PEP. Vector mesons (ρ0, K* and φ) with 0, 1 and 2 strange quarks are used to obtain redundant measures of strange-quark suppression and of the vector to pseudoscalar ratio in hadronization. Measurements of the production rates of Λ, Ξ-, Ω and Ξ*0 hyperons and for the Λc and of rapidity correlations between Λ bar Λ pairs provide sensitive tests of baryon production in fragmentation models. In addition, two- and three-particle correlations between like sign pions provide further evidence for the Bose-Einstein effect in e+e- interactions including the relativistic motion of particle sources. 9 refs., 7 figs

  13. The $\\mu$TPC Method: Improving the Position Resolution of Neutron Detectors Based on MPGDs

    CERN Document Server

    Pfeiffer, Dorothea; Birch, Jens; Hall-Wilton, Richard; Höglund, Carina; Hultman, Lars; Iakovidis, George; Oliveri, Eraldo; Oksanen, Esko; Ropelewski, Leszek; Thuiner, Patrik

    2015-01-01

    Due to the Helium-3 crisis, alternatives to the standard neutron detection techniques are becoming urgent. In addition, the instruments of the European Spallation Source (ESS) require advances in the state of the art of neutron detection. The instruments need detectors with excellent neutron detection efficiency, high-rate capabilities and unprecedented spatial resolution. The Macromolecular Crystallography instrument (NMX) requires a position resolution in the order of 200 um over a wide angular range of incoming neutrons. Solid converters in combination with Micro Pattern Gaseous Detectors (MPGDs) are proposed to meet the new requirements. Charged particles rising from the neutron capture have usually ranges larger than several millimetres in gas. This is apparently in contrast with the requirements for the position resolution. In this paper, we present an analysis technique, new in the field of neutron detection, based on the Time Projection Chamber (TPC) concept. Using a standard Single-GEM with the catho...

  14. MIMAC: A micro-tpc matrix for dark matter directional detection

    International Nuclear Information System (INIS)

    The dark matter directional detection opens a new field in cosmology bringing the possibility to build a map of nuclear recoils that would be able to explore the galactic dark matter halo giving access to a particle characterization of such matter and the shape of the halo. The MIMAC (MIcro-tpc MAtrix of Chambers) collaboration has developed in the last years an original prototype detector based on the direct coupling of large pixelized micromegas with a devoted fast self-triggered electronics showing the feasibility of a new generation of directional detectors. The discovery potential of this search strategy is discussed and illustrated. In June 2012, the first bi-chamber prototype has been installed at Modane Underground Laboratory (LSM) and the first underground background events, the gain stability and calibration are shown

  15. MIMAC: A micro-tpc matrix project for directional detection of dark matter

    CERN Document Server

    Santos, D; Bosson, G; Bouly, J L; Bourrion, O; Fourel, Ch; Guillaudin, O; Mayet, F; Richer, J P; Delbart, A; Ferrer, E; Giomataris, I; Iguaz, F J; Mols, J P; Golabek, C; Lebreton, L

    2011-01-01

    Directional detection of non-baryonic DarkMatter is a promising search strategy for discriminating WIMP events from background ones. This strategy requires both a measurement of the recoil energy down to a few keV and 3D reconstruction of tracks down to a few mm. The MIMAC project, based on a micro-TPC matrix, filled with CF4 and CHF3 is being developed. The first results of a chamber prototype of this matrix, on low energy nuclear recoils (1H and 19F) obtained with mono-energetic neutron fields are presented. The discovery potential of this search strategy is illustrated by a realistic case accessible to MIMAC.

  16. MIMAC: MIcro-tpc MAtrix of Chambers for dark matter directional detection

    CERN Document Server

    Santos, D; Bouly, J L; Bourrion, O; Fourel, Ch; Guillaudin, O; Lamblin, J; Mayet, F; Muraz, J F; Richer, J P; Riffard, Q; Lebreton, L; Maire, D; Busto, J; Brunner, J; Fouchez, D

    2013-01-01

    Directional detection of non-baryonic Dark Matter is a promising search strategy for discriminating WIMP events from neutrons, the ultimate background for dark matter direct detection. This strategy requires both a precise measurement of the energy down to a few keV and 3D reconstruction of tracks down to a few mm. The MIMAC (MIcro-tpc MAtrix of Chambers) collaboration has developed in the last years an original prototype detector based on the direct coupling of large pixelized micromegas with a special developed fast self-triggered electronics showing the feasibility of a new generation of directional detectors. The first bi-chamber prototype has been installed at Modane, underground laboratory in June 2012. The first undergournd background events, the gain stability and calibration are shown. The first spectrum of nuclear recoils showing 3D tracks coming from the radon progeny is presented.

  17. MIMAC : A micro-tpc matrix for directional detection of dark matter

    CERN Document Server

    Santos, D; Bosson, G; Bouly, J L; Bourrion, O; Fourel, Ch; Grignon, C; Guillaudin, O; Mayet, F; Richer, J P; Delbart, A; Ferrer, E; Giomataris, I; Iguaz, F J; Mols, J P; Golabek, C; Lebreton, L

    2011-01-01

    Directional detection of non-baryonic Dark Matter is a promising search strategy for discriminating WIMP events from background. However, this strategy requires both a precise measurement of the energy down to a few keV and 3D reconstruction of tracks down to a few mm. To achieve this goal, the MIMAC project has been developed. It is based on a gaseous micro-TPC matrix, filled with CF4 and CHF3. The first results on low energy nuclear recoils (H, F) obtained with a low mono-energetic neutron field are presented. The discovery potential of this search strategy is discussed and illustrated by a realistic case accessible to MIMAC.

  18. TPC-like readout for thermal neutron detection using a GEM-detector

    CERN Document Server

    Flierl, Bernhard; Hertenberger, Ralf; Zeitelhack, Karl

    2015-01-01

    Spatial resolution of less than 200 um is challenging for thermal neutron detection. A novel readout scheme based on the time-projection-chamber (TPC) concept is used in a gaseous electron multiplier (GEM) detector. Thermal neutrons are captured in a single 2 um thick Boron-10 converter cathode and secondary Helium and Lithium ions are produced with a combined energy of 2.8 MeV. These ions have sufficient energy to form straight tracks of several mm length. With a time resolving 2-dimensional readout of 400 um pitch in both directions, based on APV25 chips, the ions are tracked and their respective origin in the cathode converter foil is reconstructed. Using an Ar-CO2 93:7% gas mixture, a resolution of 100 um (FWHM 235 um) has been observed with a triple GEM-detector setup at the Garching neutron source (FRMII) for neutrons of 4.7 Angstrom.

  19. Neutral Current Coherent Cross Sections -- Implications on Gaseous Spherical TPC's for detecting SN and Earth neutrinos

    CERN Document Server

    Giomataris, Y

    2016-01-01

    The detection of galactic supernova (SN) neutrinos represents one of the future frontiers of low-energy neutrino physics and astrophysics. The neutron coherence of neutral currents (NC) allows quite large cross sections in the case of neutron rich targets, which can be exploited in detecting earth and sky neutrinos by measuring nuclear recoils. They are relatively cheap and easy to maintain. The relevant NC cross sections are not dependent on flavor conversions and, thus, their measurement will provide useful information about the neutrino source. In particular they will yield information about the primary neutrino fluxes and perhaps about the spectrum after flavor conversions in neutrino sphere.They might also provide some clues about the neutrino mass hierarchy. The advantages of large gaseous low threshold and high resolution detectors with time projection counters (TPC) are discussed.

  20. First measurement of dE/dx with a GEM-based TPC

    International Nuclear Information System (INIS)

    In this work we present the first measurement of the specific energy loss (dE/dx) and an analysis of the resulting charged-particle identification (PID) capabilities of a large-scale TPC with GEM-based gas amplification. The data has been recorded inside the FOPI spectrometer at GSI, Germany, using reactions of 1.7 GeV/c pions impinging on a carbon target. In the specific energy loss spectrum clear bands for pions, kaons, protons and deuterons are observed. The specific energy loss resolution is studied as a function of the total particle momentum and as a function of the track length. It is found to be ∼15%, consistent with expectations

  1. TPC in gamma-ray astronomy above pair-creation threshold

    CERN Document Server

    Bernard, Denis

    2012-01-01

    We examine the performance of a TPC as a gamma-ray telescope above the pair-creation threshold. The contributions to the photon angular resolution are studied and their dependence on energy is obtained. The effective area per detector unit mass for such a thin detector is the conversion mass attenuation coefficient. The differential sensitivity for the detection of a point-like source is then derived. Finally, the measurement of track momentum from deflections due to multiple scattering is optimized. These analytical results are exemplified numerically for a few sets of detector parameters. TPCs show an impressive improvement in sensitivity with respect to existing pair-creation-based telescopes in the [MeV - GeV] energy range, even with the modest detector parameters of this study. In addition, gas TPCs allow an improvement in angular resolution of about one order of magnitude.

  2. 内存数据库在TPC-H负载下的处理器性能%Main Memory Database TPC-H Workload Characterization on Modern Processor

    Institute of Scientific and Technical Information of China (English)

    刘大为; 栾华; 王珊; 覃飙

    2008-01-01

    Ailamaki等人1999年研究了数据库管理系统(database management system,简称DBMS)在处理器上的时间开销分解.此后,相关研究集中在分析DBMS在处理器上的瓶颈.但这些研究工作均是在磁盘数据库DRDBs(disk resident databases)上开展的,而且都是分析DBMS上的TPC-C类负载.然而,随着硬件技术的进步,现代计算机的多级缓存结构(memory hierarchy)在逐渐地"上移".例如,容量越来越大的芯片内缓存(on-chip caches)和芯片外缓存(off-chip caches),容量越来越大的RAM,Flash Memory等等.为此,处理器负载分析的研究工作也应随之"上移".研究内存数据MMDBs(main memory resident databases)在计算密集型负载下的处理器行为特性.由于磁盘数据库的主要性能瓶颈是磁盘I/O,因而可以用索引、压缩等技术进行优化;然而,内存数据库的性能瓶颈却在于处理器和内存之间的数据交换.针对这一问题,首先分析了磁盘数据库和内存数据库在TPC-H负载下处理器性能瓶颈的差异,并给出了一些优化建议,提出了通过预取的优化方法.其次,通过实验比较了不同存储体系结构(行存储与列存储)对处理器利用率的差异,并探索了下一代内存数据库体系结构方面的解决方案.此外,还研究了索引结构对处理器多级缓存的影响,并给出了索引的优化建议.最后,提出一个微测试集用于评估内存数据库在DSS(decision support system)负载下处理器的性能及行为特性.研究结果会对运行于下一代处理器上的内存数据库体系结构设计和性能优化提供一定的实验依据.

  3. Argon laser irradiation of the otolithic organ

    Energy Technology Data Exchange (ETDEWEB)

    Okuno, T.; Nomura, Y.; Young, Y.H.; Hara, M. (Univ. of Tokyo (Japan))

    1990-12-01

    An argon laser was used to irradiate the otolithic organs of guinea pigs and cynomolgus monkeys. After stapedectomy, the argon laser (1.5 W x 0.5 sec/shot) irradiated the utricle or saccule without touching the sensory organs. The stapes was replaced over the oval window after irradiation. The animals used for acute observation were killed immediately for morphologic studies; those used for long-term observation were kept alive for 2, 4, or 10 weeks. Acute observation revealed that sensory and supporting cells were elevated from the basement membrane only in the irradiated area. No rupture of the membranous labyrinth was observed. Long-term observation revealed that the otolith of the macula utriculi had disappeared in 2-week specimens. The entire macula utricili had disappeared in 10-week specimens. No morphologic changes were observed in cochlea, semicircular canals, or membranous labyrinth. The saccule showed similar changes.

  4. Explanation of the memory effect in argon

    Directory of Open Access Journals (Sweden)

    Marković Vidosav

    2005-01-01

    Full Text Available Memory effect - the long time variation of the electrical breakdown time delay on the relaxation time td (τ was observed in argon 24 hours after relaxation times and explained by the long-lived metastable states remaining from the preceding glow. However, the quenching processes reducing the effective lifetime of metastable states several orders of magnitude below that relevant for the time scale of observation were neglected. By applying approximate gas phase models it was found that the early afterglow kinetics up to hundreds of milliseconds is dominated by the decay of molecular argon ions Ar2+ and the approximate value of their ambipolar diffusion coefficient is determined. After that, nitrogen atoms present as impurities and recombined on the cathode surface and/or field emission determine the breakdown time delay down to the cosmic rays and natural radioactivity level.

  5. Flow Parameters of Argon plasma Discharge

    International Nuclear Information System (INIS)

    Owing to the viscosity, the plasma will be adhering to the inner surface of the outer electrode and outer surface of the inner one. As result that the discharge will be eroding the walls of coaxial system. The thickness of the boundary layer near the walls has been estimated at different positions from the breech of coaxial plasma gun. It is found that the thickness of layer 0.008 cm at the end of inner electrode (17 cm). A coaxial plasma gun device is operated in argon gas at ambient pressure 0.6 Torr and discharge voltage about 10 KV. The electron temperature of argon discharge has been determined by using spectroscopic technique. It is found that kTe=3.4 eV. By knowing the thickness of the boundary layer, the density can be determined. The Reynolds number R=105 and Mach number M=5 i.e. the flow is compressible and hypersonic

  6. ATLAS liquid argon calorimeter back end electronics

    CERN Document Server

    Bán, J; Bellachia, F; Blondel, A; Böttcher, S; Clark, A; Colas, Jacques; Díaz-Gómez, M; Dinkespiler, B; Efthymiopoulos, I; Escalier, M; Fayard, Lo; Gara, A; He, Y; Henry-Coüannier, F; Hubaut, F; Ionescu, G; Karev, A; Kurchaninov, L; Lafaye, R; Laforge, B; La Marra, D; Laplace, S; Le Dortz, O; Léger, A; Liu, T; Martin, D; Matricon, P; Moneta, L; Monnier, E; Oberlack, H; Parsons, J A; Pernecker, S; Perrot, G; Poggioli, L; Prast, J; Przysiezniak, H; Repetti, B; Rosselet, L; Riu, I; Schwemling, P; Simion, S; Sippach, W; Strässner, A; Stroynowski, R; Tisserant, S; Unal, G; Wilkens, H; Wingerter-Seez, I; Xiang, A; Yang, J; Ye, J

    2007-01-01

    The Liquid Argon calorimeters play a central role in the ATLAS (A Toroidal LHC Apparatus) experiment. The environment at the Large Hadron Collider (LHC) imposes strong constraints on the detectors readout systems. In order to achieve very high precision measurements, the detector signals are processed at various stages before reaching the Data Acquisition system (DAQ). Signals from the calorimeter cells are received by on-detector Front End Boards (FEB), which sample the incoming pulse every 25ns and digitize it at a trigger rate of up to 75~kHz. Off-detector Read Out Driver (ROD) boards further process the data and send reconstructed quantities to the DAQ while also monitoring the data quality. In this paper, the ATLAS Liquid Argon electronics chain is described first, followed by a detailed description of the off-detector readout system. Finally, the tests performed on the system are summarized.

  7. Nanotextured Shrink Wrap Superhydrophobic Surfaces by Argon Plasma Etching

    Directory of Open Access Journals (Sweden)

    Jolie M. Nokes

    2016-03-01

    Full Text Available We present a rapid, simple, and scalable approach to achieve superhydrophobic (SH substrates directly in commodity shrink wrap film utilizing Argon (Ar plasma. Ar plasma treatment creates a stiff skin layer on the surface of the shrink film. When the film shrinks, the mismatch in stiffness between the stiff skin layer and bulk shrink film causes the formation of multiscale hierarchical wrinkles with nano-textured features. Scanning electron microscopy (SEM images confirm the presence of these biomimetic structures. Contact angle (CA and contact angle hysteresis (CAH measurements, respectively, defined as values greater than 150° and less than 10°, verified the SH nature of the substrates. Furthermore, we demonstrate the ability to reliably pattern hydrophilic regions onto the SH substrates, allowing precise capture and detection of proteins in urine. Finally, we achieved self-driven microfluidics via patterning contrasting superhydrophilic microchannels on the SH Ar substrates to induce flow for biosensing.

  8. Distribution and Abundance of Mars' Atmospheric Argon

    Science.gov (United States)

    Sprague, A. L.; Boynton, W. V.; Kerry, K. E.; Nelli, Steven; Murphy, Jim; Reedy, R. C.; Metzger, A. E.; Hunten, D. M.; Janes, K. D.; Crombie, M. K.

    2005-01-01

    One and one half Mars years (MY 26 and 27) of atmospheric Argon measurements are described and studied in the context of understanding how Argon, a minor constituent of Mars atmosphere that does not condense at Mars temperatures, can be used to study martian circulation and dynamics. Argon data are from the 2001 Mars Odyssey Gamma Subsystem (GS) of the suite of three instruments comprising the Gamma Ray Spectrometer (GRS). A comprehensive data analysis including gamma-ray production and attenuation by the atmosphere is included. Of particular interest is the enhanced abundance of Ar over the observed Ar abundance at lower latitudes at south (up to a factor of 10) and north (up to a factor of 4) polar regions during winter. Calibration of the measurements to actual Ar abundance is possible because GS measurements cover the same latitude and season as measurements made by the gas chromatograph mass spectrometer (GCMS) on Viking Landers 1 and 2 (VL1 and VL2). [2].

  9. Methods and results for calibration and track separation of a GEM based TPC using an UV-laser

    Energy Technology Data Exchange (ETDEWEB)

    Ball, Markus

    2008-12-15

    In the last 30 years high energy physics could write an impressive story of success. Since the introduction of the Standard Model (SM), it has met every experimental test. However the final confirmation has to prove the mechanism of electroweak symmetry breaking, which could not be confirmed yet. The most favored theory, which includes the introduction of a Higgs field, could not be verified experimentally. Furthermore there is clear evidence, that the SM is only a low energy description of nature and its principles, as the SM describes only 4 % of the known matter in the universe. There are two different approaches in accelerator driven high energy physics to clarify the open questions. The Large Hadron Collider (LHC) have a good opportunity to measure some of the missing pieces with its high center of mass energy. The International Linear Collider (ILC) will then measure their parameters with high precision. To guarantee this high precision the detectors have to be able to identify every single particle and determine its properties with high accuracy. These high requirements to the single detectors as well as the interconnectivity between all detectors are summarised by the concept of particle flow (PFLOW). This means that all particles must be separable, which includes in particular the main tracking device. A possible candidate for the central tracking device is a Time Projection Chamber (TPC). In this work a TPC with Gas Electron Multipliers (GEM) as gas amplification system was used. The GEMs replace the conventional wire amplification system of the TPC. In this PhD work a method to determine the drift velocity of a TPC was developed and tested using an ultraviolet laser. To ensure a high accuracy of the method all relevant gas parameters were measured with a slow control system. Furthermore the laser was used to investigate the separation capability of nearby tracks. Therefore an existing TPC prototype, which was developed to operate in a 5 T magnet facility

  10. Methods and results for calibration and track separation of a GEM based TPC using an UV-laser

    International Nuclear Information System (INIS)

    In the last 30 years high energy physics could write an impressive story of success. Since the introduction of the Standard Model (SM), it has met every experimental test. However the final confirmation has to prove the mechanism of electroweak symmetry breaking, which could not be confirmed yet. The most favored theory, which includes the introduction of a Higgs field, could not be verified experimentally. Furthermore there is clear evidence, that the SM is only a low energy description of nature and its principles, as the SM describes only 4 % of the known matter in the universe. There are two different approaches in accelerator driven high energy physics to clarify the open questions. The Large Hadron Collider (LHC) have a good opportunity to measure some of the missing pieces with its high center of mass energy. The International Linear Collider (ILC) will then measure their parameters with high precision. To guarantee this high precision the detectors have to be able to identify every single particle and determine its properties with high accuracy. These high requirements to the single detectors as well as the interconnectivity between all detectors are summarised by the concept of particle flow (PFLOW). This means that all particles must be separable, which includes in particular the main tracking device. A possible candidate for the central tracking device is a Time Projection Chamber (TPC). In this work a TPC with Gas Electron Multipliers (GEM) as gas amplification system was used. The GEMs replace the conventional wire amplification system of the TPC. In this PhD work a method to determine the drift velocity of a TPC was developed and tested using an ultraviolet laser. To ensure a high accuracy of the method all relevant gas parameters were measured with a slow control system. Furthermore the laser was used to investigate the separation capability of nearby tracks. Therefore an existing TPC prototype, which was developed to operate in a 5 T magnet facility

  11. Fast TPC Online Tracking on GPUs and Asynchronous Data Processing in the ALICE HLT to facilitate Online Calibration

    Science.gov (United States)

    Rohr, David; Gorbunov, Sergey; Krzewicki, Mikolaj; Breitner, Timo; Kretz, Matthias; Lindenstruth, Volker

    2015-12-01

    ALICE (A Large Heavy Ion Experiment) is one of the four major experiments at the Large Hadron Collider (LHC) at CERN, which is today the most powerful particle accelerator worldwide. The High Level Trigger (HLT) is an online compute farm of about 200 nodes, which reconstructs events measured by the ALICE detector in real-time. The HLT uses a custom online data-transport framework to distribute data and workload among the compute nodes. ALICE employs several calibration-sensitive subdetectors, e.g. the TPC (Time Projection Chamber). For a precise reconstruction, the HLT has to perform the calibration online. Online- calibration can make certain Offline calibration steps obsolete and can thus speed up Offline analysis. Looking forward to ALICE Run III starting in 2020, online calibration becomes a necessity. The main detector used for track reconstruction is the TPC. Reconstructing the trajectories in the TPC is the most compute-intense step during event reconstruction. Therefore, a fast tracking implementation is of great importance. Reconstructed TPC tracks build the basis for the calibration making a fast online-tracking mandatory. We present several components developed for the ALICE High Level Trigger to perform fast event reconstruction and to provide features required for online calibration. As first topic, we present our TPC tracker, which employs GPUs to speed up the processing, and which bases on a Cellular Automaton and on the Kalman filter. Our TPC tracking algorithm has been successfully used in 2011 and 2012 in the lead-lead and the proton-lead runs. We have improved it to leverage features of newer GPUs and we have ported it to support OpenCL, CUDA, and CPUs with a single common source code. This makes us vendor independent. As second topic, we present framework extensions required for online calibration. The extensions, however, are generic and can be used for other purposes as well. We have extended the framework to support asynchronous compute

  12. Development of a low-cost inductively coupled argon plasma

    International Nuclear Information System (INIS)

    The aim of this investigation is to drastically reduce running costs of an inductively coupled plasma. This is done by reducing the argon consumption from 20 l/min to about 1 l/min. First, a sample introduction system operating on 0.1 l/min of carrier argon is described. This system ensures a high ratio of plasma argon and carrier argon even at the low total argon consumptions intended. Next, the developed low consumption plasma is presented. In the proposed design, air is blown perpendicularly against the outside of the torch. A different coil has been developed to make air-cooling efficient. Preliminary data on coupling efficiency for the air-cooled plasma are presented. A similarly low argon consumption has been achieved with water as an external coolant medium. It is concluded that a cheaper alternative to the current ICP has become available. (Auth.)

  13. Cell Proliferation of HaCaT Keratinocytes on Collagen Films Modified by Argon Plasma Treatment

    OpenAIRE

    Jorge López García; Ahmad Asadinezhad; Jiří Pacherník; Marián Lehocký; Ita Junkar; Petr Humpolíček; Petr Sáha; Pavel Valášek

    2010-01-01

    Argon plasma treatment was used to modify the surface of atelocollagen films using a plasmochemical reactor. To evaluate the effects of the treatment, the untreated and treated samples were characterized by Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), Scanning Electron Microscopy (SEM) imaging, and X-ray Photoelectron Spectroscopy (XPS) techniques. Cell growth was carried out by culturing human immortalized keratinocyte (HaCaT) cells and proliferation was m...

  14. Direct WIMP Detection Using Scintillation Time Discrimination in Liquid Argon

    OpenAIRE

    Boulay, M. G.; Hime, A.

    2004-01-01

    Discrimination between electron and nuclear recoil events in a liquid argon scintillation detector has been demonstrated with simulations by using the differences in the scintillation photon time distribution between these classes of events. A discrimination power greater than 10^{8} is predicted for a liquid argon experiment with a 10 keV threshold, which would mitigate electron and gamma-ray backgrounds, including beta decays of 39-Ar and 42-Ar in atmospheric argon. A dark matter search usi...

  15. Effects of Nitrogen contamination in liquid Argon

    Science.gov (United States)

    Acciarri, R.; Antonello, M.; Baibussinov, B.; Baldo-Ceolin, M.; Benetti, P.; Calaprice, F.; Calligarich, E.; Cambiaghi, M.; Canci, N.; Carbonara, F.; Cavanna, F.; Centro, S.; Cocco, A. G.; Di Pompeo, F.; Fiorillo, G.; Galbiati, C.; Gallo, V.; Grandi, L.; Meng, G.; Modena, I.; Montanari, C.; Palamara, O.; Pandola, L.; Piano Mortari, G. B.; Pietropaolo, F.; Raselli, G. L.; Roncadelli, M.; Rossella, M.; Rubbia, C.; Segreto, E.; Szelc, A. M.; Ventura, S.; Vignoli, C.

    2010-06-01

    A dedicated test of the effects of Nitrogen contamination in liquid Argon has been performed at the INFN-Gran Sasso Laboratory (LNGS, Italy) within the WArP R&D program. A detector has been designed and assembled for this specific task and connected to a system for the injection of controlled amounts of gaseous Nitrogen into the liquid Argon. The purpose of the test is to detect the reduction of the Ar scintillation light emission as a function of the amount of the Nitrogen contaminant injected in the Argon volume. A wide concentration range, spanning from ~ 10-1 ppm up to ~ 103 ppm, has been explored. Measurements have been done with electrons in the energy range of minimum ionizing particles (γ-conversion from radioactive sources). Source spectra at different Nitrogen contaminations are analyzed, showing sensitive reduction of the scintillation yield at increasing concentrations. Direct PMT signal acquisition exploiting high time resolution by fast waveform recording allowed high precision extraction of the main characteristics of the scintillation light emission in contaminated LAr. In particular, the decreasing behavior in lifetime and relative amplitude of the slow component is found to be appreciable starting from Script O(1 ppm) of Nitrogen concentrations. The rate constant of the quenching process induced by Nitrogen in liquid Ar has been found to be kQ(N2) = 0.11 ± 0.01 μs-1ppm-1, consistent with a previous measurement of this quantity but with significant improvement in precision. On the other hand, no evidence for absorption by N2 impurities has been found up to the higher concentrations here explored.

  16. HARP: high pressure argon readout for calorimeters

    International Nuclear Information System (INIS)

    Steel tubes of approximately 8 mm O.D., filled with Argon gas to approx.200 bar, are considered as the active element for a charge collecting sampling calorimeter readout system. The tubes are permanently sealed and operated in the ion chamber mode, with the charge collection on a one-millimeter concentric anode. We present the motivation for such a device, including Monte Carlo predictions of performance. The method of construction and signal collection are discussed, with initial results on leakage and ageing of the filling gas. A prototype electromagnetic calorimeter is described

  17. Argon isotope fractionation induced by stepwise heating

    Science.gov (United States)

    Trieloff, Mario; Falter, Martina; Buikin, Alexei I.; Korochantseva, Ekaterina V.; Jessberger, Elmar K.; Altherr, Rainer

    2005-03-01

    Noble gas isotopes are widely used to elucidate the history of the rocks in which they have been trapped, either from distinct reservoirs or by accumulation following radioactive decay. To extract noble gases from their host rocks, stepwise heating is the most commonly used technique to deconvolve isotopically different components, e.g., atmospheric, in situ radiogenic, or excess radiogenic from mantle or crustal reservoirs. The accurate determination of the isotopic composition of these different components is of crucial importance, e.g., for ages obtained by 40Ar- 39Ar stepheating plateaus. However, diffusion theory-based model calculations predict that the stepwise thermal extraction process from mineral phases induces isotope fractionation and, hence, adulterates the original composition. Such effects are largely unconsidered, as they are small and a compelling experimental observation is lacking. We report the first unequivocal evidence for significant mass fractionation of argon isotopes during thermal extraction, observed on shungite, a carbon-rich Precambrian sedimentary rock. The degree of fractionation, as monitored by 38Ar/ 36Ar and 40Ar/ 36Ar ratios, very well agrees with theoretical predictions assuming an inverse square root dependence of diffusion coefficient and atomic mass, resulting in easier extraction of lighter isotopes. Hence, subatmospheric 40Ar/ 36Ar ratios obtained for argon extracted at low temperatures may not represent paleoatmospheric argon. Shungite argon resembles modern atmospheric composition, but constraints on the timing of trapping appear difficult to obtain, as shungites are multicomponent systems. In 40Ar- 39Ar stepwise heating, the isotope fractionation effect could cause systematic underestimations of plateau ages, between 0.15 and 0.4% depending on age, or considerably higher if samples contain appreciable atmospheric Ar. The magnitude of this effect is similar to the presently achieved uncertainties of this increasingly

  18. Near-infrared scintillation of liquid argon

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, T. [Fermilab; Escobar, C. O. [Campinas State U.; Lippincott, W. H. [Fermilab; Rubinov, P. [Fermilab

    2016-03-03

    Since the 1970s it has been known that noble gases scintillate in the near infrared (NIR) region of the spectrum (0.7 $\\mu$m < $\\lambda$; < 1.5$\\mu$m). More controversial has been the question of the NIR light yield for condensed noble gases. We first present the motivation for using the NIR scintillation in liquid argon detectors, then briefly review early as well as more recent efforts and finally show encouraging preliminary results of a test performed at Fermilab.

  19. Near-infrared scintillation of liquid argon

    CERN Document Server

    Alexander, T; Lippincott, W H; Rubinov, P

    2016-01-01

    Since the 1970s it has been known that noble gases scintillate in the near infrared (NIR) region of the spectrum (0.7 $\\mu$m < $\\lambda$; < 1.5$\\mu$m). More controversial has been the question of the NIR light yield for condensed noble gases. We first present the motivation for using the NIR scintillation in liquid argon detectors, then briefly review early as well as more recent efforts and finally show encouraging preliminary results of a test performed at Fermilab.

  20. Attosecond Time-Resolved Autoionization of Argon

    International Nuclear Information System (INIS)

    Autoionization of argon atoms was studied experimentally by transient absorption spectroscopy with isolated attosecond pulses. The peak position, intensity, linewidth, and shape of the 3s3p6np 1P Fano resonance series (26.6-29.2 eV) were modified by intense few-cycle near infrared laser pulses, while the delay between the attosecond pulse and the laser pulse was changed by a few femtoseconds. Numerical simulations revealed that the experimentally observed splitting of the 3s3p64p 1P line is caused by the coupling between two short-lived highly excited states in the strong laser field.

  1. Argon Purification Studies and a Novel Liquid Argon Re-circulation System

    CERN Document Server

    Mavrokoridis, K; Coleman, J; Lightfoot, P K; McCauley, N; McCormick, K J; Touramanis, C

    2011-01-01

    Future giant liquid argon (LAr) time projection chambers (TPCs) require a purity of better than 0.1 parts per billion (ppb) to allow the ionised electrons to drift without significant capture by any electronegative impurities. We present a comprehensive study of the effects of electronegative impurity on gaseous and liquid argon scintillation light, an analysis of the efficacy of various purification chemicals, as well as the Liverpool LAr setup, which utilises a novel re-circulation purification system. Of the impurities tested - Air, O_2, H_2O, N_2 and CO_2 in the range of between 0.01 ppm to 1000 ppm - H_2O was found to have the most profound effect on gaseous argon scintillation light, and N_2 was found to have the least. Additionally, a correlation between the slow component decay time and the total energy deposited with 0.01 ppm - 100 ppm O_2 contamination levels in liquid argon has been established. The superiority of molecular sieves over anhydrous complexes at absorbing Ar gas, N_2 gas and H_2O vapou...

  2. Characterization of a medium size Xe/TMA TPC instrumented with microbulk Micromegas, using low-energy \\gamma-rays

    CERN Document Server

    Alvarez, V; Carcel, S; Castel, J; Cebrian, S; Cervera, A; Conde, C A N; Dafni, T; Dias, T H V T; Diaz, J; Egorov, M; Esteve, R; Evtoukhovitch, P; Fernandes, L M P; Ferrario, P; Ferreira, A L; Freitas, E D C; Gehman, V M; Gil, A; Goldschmidt, A; Gomez, H; Gomez-Cadenas, J J; Gonzalez-Diaz, D; Gutierrez, R M; Hauptman, J; Morata, J A Hernando; Herrera, D C; Iguaz, F J; Irastorza, I G; Jinete, M A; Labarga, L; Laing, A; Liubarsky, I; Lopes, J A M; Lorca, D; Losada, M; Luzon, G; Mari, A; Martin-Albo, J; Martinez, A; Martinez-Lema, G; Miller, T; Moiseenko, A; Monrabal, F; Monteiro, C M B; Mora, F J; Moutinho, L M; Vidal, J Munoz; da Luz, H Natal; Navarro, G; Nebot-Guinot, M; Nygren, D; Oliveira, C A B; Palma, R; Perez, J; Aparicio, J L Perez; Renner, J; Ripoll, L; Rodriguez, A; Rodriguez, J; Santos, F P; Santos, J M F dos; Segui, L; Serra, L; Shuman, D; Simon, A; Sofka, C; Sorel, M; Toledo, J F; Tomas, A; Torrent, J; Tsamalaidze, Z; Vazquez, D; Veloso, J F C A; Villar, J A; Webb, R C; White, J T; Yahlali, N; Aznar, F; Calvet, D; Druillole, F; Ferrer-Ribas, E; Garcia, J A; Giomataris, I; Gracia, J; Coguie, A Le; Mols, J P; Pons, P; Ruiz, E

    2013-01-01

    NEXT-MM is a general-purpose high pressure (10 bar, $\\sim25$ l active volume) Xenon-based TPC, read out in charge mode with an 8 cm $\\times$8 cm-segmented 700 cm$^2$ plane (1152 ch) of the latest microbulk-Micromegas technology. It has been recently commissioned at University of Zaragoza as part of the R&D of the NEXT $0\

  3. First results of a large-area cryogenic gaseous photomultiplier coupled to a dual-phase liquid xenon TPC

    OpenAIRE

    Arazi, L.; Coimbra, A. E. C.; Erdal, E.; ISRAELASHVILI I.; Rappaport, M. L.; Shchemelinin, S.; Vartsky, D.; Santos, J. M. F. dos; Breskin, A.

    2015-01-01

    We discuss recent advances in the development of cryogenic gaseous photomultipliers (GPM), for possible use in dark matter and other rare-event searches using noble-liquid targets. We present results from a 10 cm diameter GPM coupled to a dual-phase liquid xenon (LXe) TPC, demonstrating - for the first time - the feasibility of recording both primary ("S1") and secondary ("S2") scintillation signals. The detector comprised a triple Thick Gas Electron Multiplier (THGEM) structure with cesium i...

  4. A prototype of a directional detector for non-baryonic dark matter search: MIMAC (Micro-TPC Matrix of Chambers)

    OpenAIRE

    Grignon, C; Bernard, G. (Guillaume); Billard, J.; Bosson, G.; Bourrion, O.; Guillaudin, O; Koumeir, C.; Mayet, F.; Santos, D.; Colas, P; Ferrer, E.; Giomataris, I.; Allaoua, A.; Lebreton, L.

    2009-01-01

    We have developed a micro-tpc using a pixelized bulk micromegas coupled to dedicated acquisition electronics as a read-out allowing to reconstruct the three dimensional track of a few keV recoils. The prototype has been tested with the Amande facility at the IRSN-Cadarache providing monochromatic neutrons. The first results concerning discrimination of a few keV electrons and proton recoils are presented.

  5. A prototype of a directional detector for non-baryonic dark matter search: MIMAC (Micro-TPC Matrix of Chambers)

    Science.gov (United States)

    Grignon, C.; Bernard, G.; Billard, J.; Bosson, G.; Bourrion, O.; Guillaudin, O.; Koumeir, C.; Mayet, F.; Santos, D.; Colas, P.; Ferrer, E.; Giomataris, I.; Allaoua, A.; Lebreton, L.

    2009-11-01

    We have developed a micro-tpc using a pixelized bulk micromegas coupled to dedicated acquisition electronics as a read-out allowing to reconstruct the three dimensional track of a few keV recoils. The prototype has been tested with the Amande facility at the IRSN-Cadarache providing monochromatic neutrons. The first results concerning discrimination of a few keV electrons and proton recoils are presented.

  6. Measurements of electron drift and diffusion properties in a large cylindrical drift chamber (TPC) with parallel electric and magnetic fields

    International Nuclear Information System (INIS)

    This work describes measurements on the drift of electrons in gases, using the TPC90, the prototype of the ALEPH Time Projection Chamber. Tracks which were created by UV-Laser ionization have been drifted over distances of up to 1.3 m in parallel electric and magnetic fields. Electron drift properties have been systematically measured as a function of these, in several gas mixtures. (orig./HSI)

  7. ARGON RECOIL ION ELECTRON CAPTURE FROM NEUTRAL ARGON AND HELIUM STUDIED BY TIME RESOLVED V.U.V. SPECTROSCOPY

    OpenAIRE

    Lesteven-Vaisse, I.; Chantepie, M.; Folkmann, F.; Lecler, D.; Ben Sitel, A.

    1989-01-01

    Electron capture phenomena in recoil ion V.U.V. spectroscopy are tested through the evolution of the observed argon spectrum by introduction of helium in addition to argon in the collision chamber. Taking into account these mixed gas data by the time-differential method and using decay time analysis, an improved analysis of argon recoil ion V.U.V. radiation is presented.

  8. Design of a two-phase Xenon TPC for the study of fast scintillation in LXe dark matter detectors

    International Nuclear Information System (INIS)

    XENON100 is currently the most sensitive dark matter search experiment, its successor XENON1T is already in development phase. Dark Matter detectors at the 10 ton scale (e.g. DARWIN) are being envisioned. These experiments are based on dual-phase Xenon time projection chambers. Background suppression and discrimination are driving forces in the design of these experiments. Currently this is accomplished by fiducialization using position sensitivity and light/charge discrimination. Additional discrimination may be achieved by pulse-shape discrimination. The Mainz group is setting up a small two-phase Xenon-TPC to measure charge and scintillation yield at recoil energies in the order of few keV and to study the liquid Xenon scintillation pulse shape. As new features compared to former scintillation/charge yield experiments, our TPC will have 3D position resolution and very fast readout electronics (sampling rate 2.5 GS/s). Position resolution will be used to fiducialize the active volume, select single scatters and to reduce systematic errors. This talk gives an overview on motivation of planned measurements, the simulations done to optimize the design of the TPC and the current state of the experiment.

  9. Design of a two-phase Xenon TPC for the study of fast scintillation in LXe dark matter detectors

    Energy Technology Data Exchange (ETDEWEB)

    Beskers, Bastian; Grignon, Cyril; Oberlack, Uwe; Othegraven, Rainer; Sissol, Pierre [Johannes Gutenberg Universitaet Mainz (Germany)

    2012-07-01

    XENON100 is currently the most sensitive dark matter search experiment, its successor XENON1T is already in development phase. Dark Matter detectors at the 10 ton scale (e.g. DARWIN) are being envisioned. These experiments are based on dual-phase Xenon time projection chambers. Background suppression and discrimination are driving forces in the design of these experiments. Currently this is accomplished by fiducialization using position sensitivity and light/charge discrimination. Additional discrimination may be achieved by pulse-shape discrimination. The Mainz group is setting up a small two-phase Xenon-TPC to measure charge and scintillation yield at recoil energies in the order of few keV and to study the liquid Xenon scintillation pulse shape. As new features compared to former scintillation/charge yield experiments, our TPC will have 3D position resolution and very fast readout electronics (sampling rate 2.5 GS/s). Position resolution will be used to fiducialize the active volume, select single scatters and to reduce systematic errors. This talk gives an overview on motivation of planned measurements, the simulations done to optimize the design of the TPC and the current state of the experiment.

  10. Giant Liquid Argon Observatory for Proton Decay, Neutrino Astrophysics and CP-violation in the Lepton Sector (GLACIER)

    CERN Document Server

    Badertscher, A; Degunda, U; Epprecht, L; Horikawa, S; Knecht, L; Lazzaro, C; Lussi, D; Marchionni, A; Natterer, G; Otiougova, P; Resnati, F; Rubbia, A; Strabel, C; Ulbricht, J; Viant, T

    2010-01-01

    GLACIER (Giant Liquid Argon Charge Imaging ExpeRiment) is a large underground observatory for proton decay search, neutrino astrophysics and CP-violation studies in the lepton sector. Possible underground sites are studied within the FP7 LAGUNA project (Europe) and along the JPARC neutrino beam in collaboration with KEK (Japan). The concept is scalable to very large masses.

  11. Argon laser-welded arteriovenous anastomoses.

    Science.gov (United States)

    White, R A; Kopchok, G; Donayre, C; White, G; Lyons, R; Fujitani, R; Klein, S R; Uitto, J

    1987-11-01

    This study compared the healing of laser-welded and sutured canine femoral arteriovenous anastomoses. Arteriovenous fistulas 2 cm in length were created bilaterally in the femoral vessels of 10 dogs and were studied at 1 (n = 2), 2 (n = 2), 4 (n = 3), and 8 (n = 3) weeks. In each animal, one anastomosis (control) was closed with running 6-0 polypropylene sutures, and the contralateral anastomosis (experimental) was sealed with an argon laser (0.5 watt, 4 minutes of exposure, 1830 J/cm2/1 cm length of anastomosis). At removal all experimental anastomoses were patent without hematomas, aneurysms, or luminal narrowing. Histologic examination at 4 weeks revealed that laser-welded anastomoses had less inflammatory response and almost normal collagen and elastin reorientation. At 8 weeks sutured anastomoses had significant intimal hyperplasia whereas laser repairs had normal luminal architecture. Tensile strength and collagen production, measured by the synthesis of hydroxyproline and the steady-state levels of type I and type III procollagen messenger ribonucleic acids, at the anastomoses and in adjacent vein and artery specimens were similar in sutured and laser-welded repairs at 2, 4, and 8 weeks. We conclude that argon laser welding of anastomoses is an acceptable alternative to suture techniques, with the advantage of improved healing without foreign body response and possible diminished intimal hyperplasia at the anastomotic line. PMID:3312648

  12. Electron scattering and transport in liquid argon

    International Nuclear Information System (INIS)

    The transport of excess electrons in liquid argon driven out of equilibrium by an applied electric field is revisited using a multi-term solution of Boltzmann’s equation together with ab initio liquid phase cross-sections calculated using the Dirac-Fock scattering equations. The calculation of liquid phase cross-sections extends previous treatments to consider multipole polarisabilities and a non-local treatment of exchange, while the accuracy of the electron-argon potential is validated through comparison of the calculated gas phase cross-sections with experiment. The results presented highlight the inadequacy of local treatments of exchange that are commonly used in liquid and cluster phase cross-section calculations. The multi-term Boltzmann equation framework accounting for coherent scattering enables the inclusion of the full anisotropy in the differential cross-section arising from the interaction and the structure factor, without an a priori assumption of quasi-isotropy in the velocity distribution function. The model, which contains no free parameters and accounts for both coherent scattering and liquid phase screening effects, was found to reproduce well the experimental drift velocities and characteristic energies

  13. Pollution of liquid argon after neutron irradiation

    CERN Document Server

    Andrieux, M L; Collot, J; de Saintignon, P; Ferrari, A; Hostachy, J Y; Hoummada, A; Martin, P; Merkel, B; Puzo, P; Sauvage, D; Wielers, M

    2001-01-01

    The purpose of the neutron facility installed at SARA is to investigate the behavior of various materials to be used in the ATLAS liquid argon calorimeter, when submitted to fast neutron radiation. The samples are placed in a liquid argon cryostat a few cm away from the neutron source. Various pieces of the electromagnetic calorimeter have been tested in order to evaluate the rate of pollution of the liquid and consequently the possible signal loss in energy measurements. The average fluence was equivalent to the maximum expected in the calorimeter in about 10 years. The most striking feature of the results is that the pollution is not due to oxygen, at least for most of it. Using a particular value of the absorption length derived from these data, a simulation was carried out and the energy signal loss in the calorimeter could be predicted. Within the limits of our present knowledge, the conclusion is that damages due to this pollution will not be a problem. (17 refs).

  14. Pollution of liquid argon after neutron irradiation

    International Nuclear Information System (INIS)

    The purpose of the neutron facility installed at SARA is to investigate the behavior of various materials to be used in the ATLAS liquid argon calorimeter, when submitted to fast neutron radiation. The samples are placed in a liquid argon cryostat a few cm away from the neutron source. Various pieces of the electromagnetic calorimeter have been tested in order to evaluate the rate of pollution of the liquid and consequently the possible signal loss in energy measurements. The average fluence was equivalent to the maximum expected in the calorimeter in about 10 years. The most striking feature of the results is that the pollution is not due to oxygen, at least for most of it. Using a particular value of the absorption length derived from these data, a simulation was carried out and the energy signal loss in the calorimeter could be predicted. Within the limits of our present knowledge, the conclusion is that damages due to this pollution will not be a problem

  15. Ion-beam excitation of liquid argon

    CERN Document Server

    Hofmann, M; Heindl, T; Neumeier, A; Oberauer, L; Potzel, W; Roth, S; Schönert, S; Wieser, J; Ulrich, A

    2015-01-01

    The scintillation light of liquid argon has been recorded wavelength and time resolved with very good statistics in a wavelength interval ranging from 118 nm through 970 nm. Three different ion beams, protons, sulfur ions and gold ions, were used to excite liquid argon. Only minor differences were observed in the wavelength-spectra obtained with the different incident particles. Light emission in the wavelength range of the third excimer continuum was found to be strongly suppressed in the liquid phase. In time-resolved measurements, the time structure of the scintillation light can be directly attributed to wavelength in our studies, as no wavelength shifter has been used. These measurements confirm that the singlet-to-triplet intensity ratio in the second excimer continuum range is a useful parameter for particle discrimination, which can also be employed in wavelength-integrated measurements as long as the sensitivity of the detector system does not rise steeply for wavelengths longer than 190 nm. Using ou...

  16. TPC-like readout for thermal neutron detection using a GEM-detector

    Science.gov (United States)

    Flierl, B.; Hertenberger, R.; Biebel, O.; Zeitelhack, K.

    2016-07-01

    Spatial resolution of less than 200 μm is challenging for thermal neutron detection. A novel readout scheme based on the time-projection-chamber (TPC) concept is used in a gaseous electron multiplier (GEM) detector [1]. Thermal neutrons are captured in a single 2 μm thick Boron-10 converter cathode and secondary Helium and Lithium ions are produced with a combined energy of 2.8 MeV. These ions have sufficient energy to form straight tracks of several mm length. With a time resolving 2-dimensional readout of 400 μm pitch in both directions, based on APV25 chips, the ions are tracked and their respective origin in the cathode converter foil is reconstructed. Using an Ar-CO2 93:7% gas mixture, a resolution of 100 μm (FWHM 235 μm) has been observed with a triple GEM-detector setup at the Garching neutron source (FRMII) for neutrons of 4.7 Å.

  17. TREX-DM: a low background Micromegas-based TPC for low-mass WIMP detection

    CERN Document Server

    Iguaz, F J; Aznar, F; Castel, J F; Cebrian, S; Dafni, T; Garcia, J A; Irastorza, I G; Lagraba, A; Luzon, G; Peiro, A

    2016-01-01

    Dark Matter experiments are recently focusing their detection techniques in low-mass WIMPs, which requires the use of light elements and low energy threshold. In this context, we describe the TREX-DM experiment, a low background Micromegas-based TPC for low-mass WIMP detection. Its main goal is the operation of an active detection mass $\\sim$0.3 kg, with an energy threshold below 0.4 keVee and fully built with previously selected radiopure materials. This work describes the commissioning of the actual setup situated in a laboratory on surface and the updates needed for a possible physics run at the Canfranc Underground Laboratory (LSC) in 2016. A preliminary background model of TREX-DM is also presented, based on a Geant4 simulation, the simulation of the detector's response and two discrimination methods: a conservative muon/electron and one based on a neutron source. Based on this background model, TREX-DM could be competitive in the search for low-mass WIMPs. In particular it could be sensitive, e.g., to t...

  18. TREX-DM: a low background Micromegas-based TPC for low mass WIMP detection

    CERN Document Server

    Iguaz, F J; Aznar, F; Castel, J F; Cebrian, S; Dafni, T; Garcia, J A; Gomez, H; Gonzalez-Diaz, D; Irastorza, I G; Lagraba, A; Luzon, G; Peiro, A; Rodriguez, A

    2015-01-01

    Dark Matter experiments are recently focusing their detection techniques in low-mass WIMPs, which requires the use of light elements and low energy threshold. In this context, we present the TREX-DM experiment, a low background Micromegas-based TPC for low-mass WIMP detection. Its main goal is the operation of an active detection mass $\\sim$0.300 kg, with an energy threshold below 0.4 keVee and fully built with previously selected radiopure materials. This article describes the actual setup, the first results of the comissioning in Ar+2\\%iC$_4$H$_{10}$ at 1.2 bar and the future updates for a possible physics run at the Canfranc Underground Laboratory in 2016. A first background model is also presented, based on Geant4 simulations and a muon/electron discrimination method. In a conservative scenario, TREX-DM could be sensitive to DAMA/LIBRA and other hints of positive WIMPs signals, with some space for improvement with a neutron/electron discrimination method or the use of other light gases.

  19. The μTPC method: improving the position resolution of neutron detectors based on MPGDs

    International Nuclear Information System (INIS)

    Due to the 3He crisis, alternatives to the standard neutron detection techniques are becoming urgent. In addition, the instruments of the European Spallation Source (ESS) require advances in the state of the art of neutron detection. The instruments need detectors with excellent neutron detection efficiency, high rate capabilities and unprecedented spatial resolution. The Macromolecular Crystallography instrument (NMX) requires a position resolution in the order of 200 μm over a wide angular range of incoming neutrons. Solid converters in combination with Micro Pattern Gaseous Detectors (MPGDs) are proposed to meet the new requirements. Charged particles rising from the neutron capture have usually ranges larger than several millimetres in gas. This is apparently in contrast with the requirements for the position resolution. In this paper, we present an analysis technique, new in the field of neutron detection, based on the Time Projection Chamber (TPC) concept. Using a standard Single-GEM with the cathode coated with 10B4C, we extract the neutron interaction point with a resolution of better than σ = 200 μm

  20. Alice HLT TPC tracking of PbPb-events on GPU and CPU

    International Nuclear Information System (INIS)

    The ALICE experiment for the Large Hadron Collider was specifically designed to study heavy ion collisions. Track reconstruction for the TPC is an extremely complex task because of the very high number of particles in the chamber. The ALICE High Level Trigger requires real-time tracking for a precise trigger decision. A fast online tracking algorithm was developed that can run on both CPU and GPU. The algorithm starts with combinatorial tasks on a cellular automaton principle followed by a Kalman filter step. This makes it extremely suited to run on parallel hardware. During the development a new GPU generation was released and the tracker was adapted to make use of the latest graphics processors. The GPU hardware accelerator can play its strength in heavy ion collisions. GPU enabled compute nodes were deployed and commissioned in late 2010. The first heavy ion events were successfully reconstructed in real-time by the ALICE HLT. The cluster has sufficient compute resources available to handle the increased luminosity which is expected in the next heavy ion session of LHC. First results, benchmarks, and QA plots are presented.

  1. First measurement of dE/dx with a GEM-based TPC

    International Nuclear Information System (INIS)

    Realizing gas amplification for TPCs with GEM foils - instead of the traditional setup using MWPCs and a gating grid - promises to allow continuous operation of such a detector: exploiting the intrinsic suppression of ion backflow that is characteristic for GEMs lifts the constraint to low-rate environments entailed by the presence of a gating system. While the spatial resolution achievable with GEM foils is comparable to or better than that of MWPCs, fluctuations of the gain in a multi-GEM system could compromise the energy resolution of the detector. We have studied the specific energy loss (''dE/dx'') performance of a TPC based on a triple-GEM readout - the largest of its kind to date - on data from a 3-weeks physics campaign inside the FOPI spectrometer at GSI, Germany. Particle identification capabilities for particles originating from π-induced reactions are studied as a function of the momentum. Resolutions are extracted using an exponentially modified Gaussian as a fit function, and are found to be in good agreement with expectations. A dedicated Monte Carlo study has been performed to investigate the impact of the track length on the peak asymmetries in a truncated mean analysis.

  2. Nitrogen Removal from Molten Steel under Argon DC Glow Plasma

    Institute of Scientific and Technical Information of China (English)

    SUN Ming-shan; DING Wei-zhong; LU Xiong-gang

    2005-01-01

    Under argon DC glow plasma, the nitrogen removal from molten steel was studied. The experimental result showed that nitrogen mass percent could be reduced to 0.000 8%. The change of polarity had no impact on nitrogen removal when the nitrogen mass percent was low. The mechanism of denitrogenation of molten steel under argon DC glow plasma was discussed.

  3. WARP: a double phase argon programme for dark matter detection

    International Nuclear Information System (INIS)

    WARP (Wimp ARgon Programme) is a double phase Argon detector for Dark Matter search under construction at Laboratori Nazionali del Gran Sasso. We present recent results obtained operating a prototype with a sensitive mass of 2.3 litres deep underground

  4. Stopping Power of Solid Argon for Helium Ions

    DEFF Research Database (Denmark)

    Besenbacher, F.; Bøttiger, Jørgen; Grauersen, O.;

    1981-01-01

    By means of the Rutherford-backscattering method, the stopping cross section of solid argon has been measured for 0.5–3 MeV helium ions to an accuracy of not, vert, similar3%. The results agree within the experimental accuracies with our earlier measurements for gaseous argon over the energy region...

  5. Cell Proliferation of HaCaT Keratinocytes on Collagen Films Modified by Argon Plasma Treatment

    Directory of Open Access Journals (Sweden)

    Jorge López García

    2010-04-01

    Full Text Available Argon plasma treatment was used to modify the surface of atelocollagen films using a plasmochemical reactor. To evaluate the effects of the treatment, the untreated and treated samples were characterized by Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR, Scanning Electron Microscopy (SEM imaging, and X-ray Photoelectron Spectroscopy (XPS techniques. Cell growth was carried out by culturing human immortalized keratinocyte (HaCaT cells and proliferation was measured via MTT assay. It was observed that argon plasma treatment significantly enhanced the extent of cell proliferation, which was ascribed to the favourable role of plasma treatment in inducing surface oxygen-containing entities together with increasing surface roughness. This can be considered as a potentially promising approach for tissue regeneration purposes.

  6. Commissioning of the ATLAS liquid argon calorimeters

    CERN Document Server

    Rezaie, Erfan

    ATLAS, a multi-purpose detector built at the LHC at CERN, requires an extensive commissioning campaign to be ready for proton-proton collisions. In this work, we focus on the commissioning of the liquid Argon (LAr) calorimeters, with emphasis on commissioning with cosmic rays. First we outline one phase of the commissioning work, which involves testing of the front-end electronics of the two endcap calorimeters. We then describe two cosmic ray generators as input to a Monte-Carlo simulation of cosmic rays in ATLAS, and compare their results. Finally, we explain a technique developed for this work which uses information from the Tile calorimeters to predict the timing of cosmic rays within the LAr calorimeters, because cosmic rays occur randomly in time whereas the electronics are clocked at [Special characters omitted.] . The results from this analysis tool are compared to default tools, using both simulated and real cosmic ray data in the calorimeters.

  7. Neutron Inelastic Scattering Study of Liquid Argon

    International Nuclear Information System (INIS)

    The inelastic scattering functions for liquid argon have been measured at 85.2 K. The coherent scattering function was obtained from a measurement on pure A-36 and the incoherent function was derived from the result obtained from the A-36 sample and the result obtained from a mixture of A-36 and A-40 for which the scattering is predominantly incoherent. The data, which are presented as smooth scattering functions at constant values of the wave vector transfer in the range 10 - 44/nm, are corrected for multiple scattering contributions and for resolution effects. Such corrections are shown to be essential in the derivation of reliable scattering functions from neutron scattering data. The incoherent data are compared to recent molecular dynamics results and the mean square displacement as a function of time is derived. The coherent data are compared to molecular dynamics results and also, briefly, to some recent theoretical models

  8. Large vessel sealing with the argon laser.

    Science.gov (United States)

    White, R A; Kopchok, G; Donayre, C; Lyons, R; White, G; Klein, S R; Pizzurro, D; Abergel, R P; Dwyer, R M; Uitto, J

    1987-01-01

    This study compared the histology, biochemistry, and tensile strength of laser-welded and sutured canine venotomies, arteriotomies, and arteriovenous fistulas. Twelve animals had bilateral femoral vessels studied, with one repair (control) closed with interrupted 6-0 polypropylene sutures, and the contralateral repair (experimental) welded with the argon laser. Specimens were examined at weekly intervals from 1 to 4 weeks (four animals for each type of repair), and were evaluated histologically by hematoxylin and eosin, elastin, and trichrome stains; biochemically by the formation of [3H]hydroxyproline as an index of collagen synthesis; and mechanically by tensile strength determinations. At removal, all experimental closures were patent without hematomas, aneurysms, or luminal dilatation. Histologic and biochemical examination and tensile strength determinations suggest that laser welding may be an alternative to sutures for repair of large-diameter venotomies, arteriotomies, and arteriovenous fistulas, as healing is comparable to that seen with suture repairs up to 4 weeks postoperatively. PMID:3306233

  9. Vascular Welding Using The Argon Laser

    Science.gov (United States)

    White, Rodney A.; Donayre, Carlos; Kopchok, George; White, Geoffrey; Abergel, R. Patrick; Lyons, Richard; Klein, Stanley; Dwyer, Richard; Uitto, Jouni

    1987-03-01

    This study compared the histology, biochemistry, and tensile strength of laser welded and sutured canine venotomies, arteriotomies and arteriovenous fistulas. Bilateral femoral, carotid or jugular vessels were studied with one repair (control) closed with interrupted 6-0 polypropylene sutures, and the contralatral repair (experimental) welded with the argon laser. Specimens were examined at weekly intervals from 1 to 4 weeks for each type of repair and evaluated histologically by hematoxylineosin, elastin and trichrome stains, biochemically by the formation of [3H] hyaroxyproline as an index of collagen synthesis, ana mechanically by tensile strength determinations. At removal, all experimental closures were patent without hematomas, aneurysms or luminal dilatation. Histologic and biochemical examination and tensile strength determinations suggest that laser welaing may be an alternative to sutures for repair of large diameter venotomies, arteriotomies and arteriovenous fistulas, as they heal comparable to suture repairs up to 4 weeks postoperatively.

  10. Liquid-argon cylindrical pulsed ionization chamber

    International Nuclear Information System (INIS)

    A liquid-argon cylindrical ionization chamber with a working volume of 200 cm2 is described. The chamber anode is made of stainless steel in the form of a hollow cylinder 30 mm in diameter and 140 mm in length. A beryllium bronze wire in diameter of 0.1 mm and at a spacing of 1 mm is used for winding the chamber screen grid. The chamber cathode is a brass thin-walled cylinder having an internal diameter of 56 mm and a height of 156 mm. The cathode-grid gap is 10 mm, the cathode-case gap is 2 mm. A 0.5 l cooling bath filled with liquid nitrogen is used to refrigirate the chamber. The chamber is evacuated to about 10-5 mm Hg. The total concentration of electronegative impurities in argon does not exceed 6x10-9. Dependences of the chamber counting and amplitude responses, on the cathode voltage under irradiation with γ-quanta at energies of 0.898 MeV and 1.836 MeV are given. The value of the energy resolution was evaluated by differentiating the high-energy edge of the Compton spectrum. The total width at a peak half-height constitutes 5% for an electron energy of 1.612 MeV. To achieve better resolution of the chamber it is necessary to reduce preamplifier noises by three times, to increase the working gap of the chamber and decrease the grid-anode gap

  11. Formation of argon-boron bonds in the reactions of BFn+/2+ cations with neutral argon

    Czech Academy of Sciences Publication Activity Database

    Levee, L.; Calogero, C.; Barbieri, E.; Byrne, S.; Donahue, C.; Eisenberg, M.; Hattenbach, S.; Le, J.; Capitani, J. F.; Roithová, J.; Schröder, Detlef

    2012-01-01

    Roč. 323, 1 Jun (2012), s. 2-7. ISSN 1387-3806 R&D Projects: GA ČR GA203/09/1223 Grant ostatní: European Research Council(XE) AdG HORIZOMS Institutional support: RVO:61388963 Keywords : argon compound * boron fluoride * dication * gas phase reactivity * mass spectrometry * neon compound Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.142, year: 2012

  12. Argon laser induced changes to the carbonate content of enamel

    Energy Technology Data Exchange (ETDEWEB)

    Ziglo, M.J. [Orthodontic Graduate Program, Faculty of Medicine and Dentistry, University of Alberta, Private Practice, Regina, Saskatchewan (Canada); Nelson, A.E., E-mail: aenelson@dow.com [Department of Chemical and Materials Engineering, Faculty of Engineering, University of Alberta (Canada); Heo, G.; Major, P.W. [Orthodontic Graduate Program, Faculty of Medicine and Dentistry, University of Alberta (Canada)

    2009-05-15

    Argon laser irradiation can be used to cure orthodontic brackets onto teeth in significantly less time than conventional curing lights. In addition, it has been shown that the argon laser seems to impart a demineralization resistance to the enamel. The purpose of this study was to use surface science techniques to ascertain if this demineralization resistance is possibly a result of a decrease in the carbonate content of enamel. Eleven mandibular third molars previously scheduled for extraction were collected and used in the present study. The teeth were sectioned in two and randomly assigned to either the argon laser (457-502 nm; 250 mW cm{sup -2}) or the control (no treatment) group. The sections assigned to the argon laser group were cured for 10 s and analyzed. To exaggerate any potential changes the experimental sections were then exposed to a further 110 s of argon laser irradiation. Surface analysis was performed using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The results showed no statistically significant change in the carbonate content of enamel after argon laser irradiation (p > 0.05). Thus, it is suggested that any demineralization resistance imparted to the enamel surface by argon laser irradiation is not due to alterations in carbonate content.

  13. Argon laser induced changes to the carbonate content of enamel

    International Nuclear Information System (INIS)

    Argon laser irradiation can be used to cure orthodontic brackets onto teeth in significantly less time than conventional curing lights. In addition, it has been shown that the argon laser seems to impart a demineralization resistance to the enamel. The purpose of this study was to use surface science techniques to ascertain if this demineralization resistance is possibly a result of a decrease in the carbonate content of enamel. Eleven mandibular third molars previously scheduled for extraction were collected and used in the present study. The teeth were sectioned in two and randomly assigned to either the argon laser (457-502 nm; 250 mW cm-2) or the control (no treatment) group. The sections assigned to the argon laser group were cured for 10 s and analyzed. To exaggerate any potential changes the experimental sections were then exposed to a further 110 s of argon laser irradiation. Surface analysis was performed using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The results showed no statistically significant change in the carbonate content of enamel after argon laser irradiation (p > 0.05). Thus, it is suggested that any demineralization resistance imparted to the enamel surface by argon laser irradiation is not due to alterations in carbonate content.

  14. Gating of the two-pore cation channel AtTPC1 in the plant vacuole is based on a single voltage-sensing domain.

    Science.gov (United States)

    Jaślan, D; Mueller, T D; Becker, D; Schultz, J; Cuin, T A; Marten, I; Dreyer, I; Schönknecht, G; Hedrich, R

    2016-09-01

    The two-pore cation channel TPC1 operates as a dimeric channel in animal and plant endomembranes. Each subunit consists of two homologous Shaker-like halves, with 12 transmembrane domains in total (S1-S6, S7-S12). In plants, TPC1 channels reside in the vacuolar membrane, and upon voltage stimulation, give rise to the well-known slow-activating SV currents. Here, we combined bioinformatics, structure modelling, site-directed mutagenesis, and in planta patch clamp studies to elucidate the molecular mechanisms of voltage-dependent channel gating in TPC1 in its native plant background. Structure-function analysis of the Arabidopsis TPC1 channel in planta confirmed that helix S10 operates as the major voltage-sensing site, with Glu450 and Glu478 identified as possible ion-pair partners for voltage-sensing Arg537. The contribution of helix S4 to voltage sensing was found to be negligible. Several conserved negative residues on the luminal site contribute to calcium binding, stabilizing the closed channel. During evolution of plant TPC1s from two separate Shaker-like domains, the voltage-sensing function in the N-terminal Shaker-unit (S1-S4) vanished. PMID:27270880

  15. Cold front-end electronics and Ethernet-based DAQ systems for large LAr TPC readout

    CERN Document Server

    D.Autiero,; B.Carlus,; Y.Declais,; S.Gardien,; C.Girerd,; J.Marteau; H.Mathez

    2010-01-01

    Large LAr TPCs are among the most powerful detectors to address open problems in particle and astro-particle physics, such as CP violation in leptonic sector, neutrino properties and their astrophysical implications, proton decay search etc. The scale of such detectors implies severe constraints on their readout and DAQ system. We are carrying on a R&D in electronics on a complete readout chain including an ASIC located close to the collecting planes in the argon gas phase and a DAQ system based on smart Ethernet sensors implemented in a µTCA standard. The choice of the latter standard is motivated by the similarity in the constraints with those existing in Network Telecommunication Industry. We also developed a synchronization scheme developed from the IEEE1588 standard integrated by the use of the recovered clock from the Gigabit link

  16. Imaging of hydrogen halides photochemistry on argon and ice nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Poterya, Viktoriya; Lengyel, Jozef; Pysanenko, Andriy; Svrčková, Pavla; Fárník, Michal

    2014-01-01

    Roč. 141, č. 7 (2014), 074309. ISSN 0021-9606 R&D Projects: GA ČR(CZ) GA14-14608S Institutional support: RVO:61388955 Keywords : AR-N CLUSTERS * MONTE-CARLO SIMULATIONS * ION-PAIR FORMATION Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.952, year: 2014

  17. LArGe - A liquid argon scintillation veto for GERDA

    OpenAIRE

    Heisel, M.(Max-Planck-Institut für Kernphysik, Heidelberg, Germany)

    2011-01-01

    LArGe is a Gerda low-background test facility to study novel background suppression methods in a low-background environment, for possible applications in the Gerda experiment. Gerda searches for the neutrinoless double-beta decay in 76Ge, by operating naked germanium detectors submersed into 65 m3 of liquid argon. Similarly, LArGe runs Ge-detectors in 1 m3 (1.4 tons) of liquid argon, which in addition is instrumented with photomultipliers to detect argon scintillation light. The light is used...

  18. Practical reactor production of {sup 41}Ar from argon clathrate

    Energy Technology Data Exchange (ETDEWEB)

    Mercer, J.R. E-mail: jmercer@pharmacy.ualberta.ca; Duke, M.J.M.; McQuarrie, S.A

    2000-06-01

    The radionuclide {sup 41}Ar has many ideal properties as a gas flow tracer. However, the modest cross-section of {sup 40}Ar for thermal neutron activation makes preparation of suitable activities of {sup 41}Ar technically difficult particularly for low flux reactors. Argon can however be trapped in a molecular complex called a clathrate that can then be irradiated. We prepared argon clathrate and explored its irradiation and stability characteristics. Argon clathrate can be used to provide gigabecquerel quantities of {sup 41}Ar even with low power reactors.

  19. Membrane separation processes for argon plasma gas recovery

    OpenAIRE

    Harlacher, Thomas

    2014-01-01

    A mixture of argon and hydrogen is used as plasma gas in a thermal plasma synthesis for the production of silicon carbide. Next to argon and hydrogen, the exhaust gas of the ceramic synthesis contains carbon monoxide. Since argon is an expensive gas, the plasma gas needs to be recycled. For this purpose, the carbon monoxide has to be removed from the exhaust gas. The applicability of a membrane based gas separation process for this separation task was investigated in this study. A process rou...

  20. Stopping Power of Solid Argon for Helium Ions

    DEFF Research Database (Denmark)

    Besenbacher, F.; Bøttiger, Jørgen; Grauersen, O.; Hansen, Jens Leonhart; Sørensen, H.

    1981-01-01

    By means of the Rutherford-backscattering method, the stopping cross section of solid argon has been measured for 0.5–3 MeV helium ions to an accuracy of not, vert, similar3%. The results agree within the experimental accuracies with our earlier measurements for gaseous argon over the energy region...... studied. This proves that the gas/solid difference for argon predicted in recent stopping-power tabulations is significantly overestimated. With high-order Z1 correction terms included in the theoretical description, calculated shell corrections based on the Lindhard-Scharff model are in good agreement...

  1. Optical Readout Time Projection Chamber (O-TPC) for a Study of Oxygen Formation In Stellar Helium Burning

    OpenAIRE

    Gai, Moshe; Breskin, Amos; Chechik, Rachel; Dangendorf, Volker; Weller, Henry R.

    2005-01-01

    We are developing an Optical Readout Time Projection Chamber (O-TPC) detector for the study of the 12C(a,g)16O reaction that determines the ratio of carbon to oxygen in helium burning. This ratio is crucial for understanding the final fate of a progenitor star and the nucleosynthesis of elements prior to a Type II supernova; an oxygen rich star is predicted to collapse to a black hole, and a carbon rich star to a neutron star. Type Ia supernovae (SNeIa) are used as standard candles for measur...

  2. Argon laser treatment of urethral stricture and vesical neck contracture.

    Science.gov (United States)

    Adkins, W C

    1988-01-01

    The physical characteristics of the argon laser wavelength allow a precise incision with excellent hemostasis and negligible heating of adjacent tissues resulting in less scarring. These qualities are used to advantage in the treatment of strictures. The argon laser was used to perform 13 internal urethrotomies and ten vesical neck incisions. The operative method used is similar to optical internal urethrotomy. The argon probe incises hemostatically, reducing the need for extensive fulguration of tissues at the operative site and thereby reducing the tendency for more scar tissue to form and compromise the operation. The same hemostasis reduces the need for postoperative indwelling urethral catheterization. Utility of the argon device in most instances allows treatment to be conducted on an outpatient basis without general anesthesia and without use of postoperative urethral catheters, yielding an effective, cost-saving therapy. PMID:3210887

  3. Excitation temperatures of atmospheric argon in dielectric barrier discharges

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yu; Wen Xiaohui; Yang Weihong [CAS Key Laboratory of Basic Plasma Physics and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2007-08-15

    A method for the determination of excitation temperatures based on optical emission spectroscopy and Fermi-Dirac distribution was set up and experiments were performed on atmospheric argon dielectric barrier discharges. Local thermodynamic equilibrium was proved to exist in the discharge and the validity of Boltzmann distribution is discussed. The main aim of this paper is to obtain the temperatures of atmospheric Ar II as a function of the discharge voltage, discharge frequency, argon flow rate and the argon fraction. It was found that the excitation temperatures are in the range 3800-4950 K. Besides, an increase in the argon flow rate resulting in a slight growth of the temperature and the add-in of air leading to the decrease in temperature was observed.

  4. The Effects of Dissolved Methane upon Liquid Argon Scintillation Light

    CERN Document Server

    Jones, B J P; Back, H O; Collin, G; Conrad, J M; Greene, A; Katori, T; Pordes, S; Toups, M

    2013-01-01

    In this paper we report on measurements of the effects of dissolved methane upon argon scintillation light. We monitor the light yield from an alpha source held 20 cm from a cryogenic photomultiplier tube (PMT) assembly as methane is injected into a high-purity liquid argon volume. We observe significant suppression of the scintillation light yield by dissolved methane at the 10 part per billion (ppb) level. By examining the late scintillation light time constant, we determine that this loss is caused by an absorption process and also see some evidence of methane-induced scintillation quenching at higher concentrations (50-100 ppb). Using a second PMT assembly we look for visible re-emission features from the dissolved methane which have been reported in gas-phase argon methane mixtures, and we find no evidence of visible re-emission from liquid-phase argon methane mixtures at concentrations between 10 ppb and 0.1%.

  5. The ATLAS Liquid Argon Calorimeter Construction, Integration, Commissioning

    CERN Document Server

    Aleksa, Martin

    2006-01-01

    The ATLAS liquid argon (LAr) calorimeter system consists of an electromagnetic barrel calorimeter and two end caps with electromagnetic, hadronic and forward calorimeters. The liquid argon sampling technique, with an accordion geometry was chosen for the barrel electromagnetic calorimeter (EMB) and adapted to the end cap (EMEC). The hadronic end cap calorimeter (HEC) uses a copper-liquid argon sampling technique with flat plate geometry and is subdivided in depth in two wheels per end-cap. Finally, the forward calorimeter (FCAL) is composed of three modules employing cylindrical electrodes with thin liquid argon gaps. The construction of the full calorimeter system is complete since mid-2004. Production modules constructed in the home institutes were integrated into wheels at CERN in 2003-2004, and inserted into the three cryostats. They passed their first complete cold test before the lowering into the ATLAS cavern. Results of quality checks (e.g. electrical, mechanical, ...) performed on all the 190304 read...

  6. Size Determination of Argon Clusters from a Rayleigh Scattering Experiment

    Institute of Scientific and Technical Information of China (English)

    LEI An-Le; ZHAI Hua-Jin; LIU Bing-Chen; LI Zhong; NI Guo-Yuan; XU Zhi-Zhan

    2000-01-01

    Argon clusters are produced in the process of adiabatic expansion of a high backing pressure gas into vacuum through a nozzle. The cluster size is determined by a Rayleigh scattering measurement. The scattered signal measured is proportional to the 2.78th power of gas stagnation pressure. The average cluster sizes vary from 100 to more than 12000 atoms/cluster with the argon gas backing pressures ranging between 3 to 45 atm.

  7. A purity monitoring system for liquid argon calorimeters

    International Nuclear Information System (INIS)

    For liquid argon calorimeters electronegative impurities dissolved in the medium degrade the detector response and deteriorate the energy resolution, especially at high energies. A concept for a purity monitoring system for liquid argon calorimeters has been developed and is presented here. Special combined monitors of 241Am- and 207Bi-cells are used to monitor the concentration of impurities. The working principle as well as results from test measurements are discussed

  8. Studies of Electron Avalanche Behavior in Liquid Argon

    OpenAIRE

    Kim, J.G.; Dardin, S. M.; Jackson, K.H.; Kadel, R. W.(Lawrence Berkeley National Laboratory and University of California, 94720, Berkeley, California, USA); Kadyk, J. A.; Peskov, V.; Wenzel, W. A.

    2002-01-01

    Electron avalanching in liquid argon is being studied as a function of voltage, pressure, radiation intensity, and the concentrations of certain additives, especially xenon. The avalanches produced in an intense electric field at the tip of a tungsten needle are initiated by ionization from a moveable americium (241Am) gamma ray source. Photons from xenon excimers are detected as photomultiplier signals in coincidence with the current pulse from the needle. In pure liquid argon the avalanche ...

  9. Pulse shape discrimination studies in a liquid Argon scintillation detector

    OpenAIRE

    Pollmann, T.

    2007-01-01

    Liquid rare gases have been gaining popularity as detector media in rare event searches, especially dark matter experiments, and one factor driving their adoption is the possibility to recognise different types of ionizing radiation by the pulse shapes they evoke. This work on pulse shape discrimination in a liquid argon scintillation detector was done in the framework of the GERDA experiment, where liquid argon scintillation signals may be used for background suppression purposes. Liquid arg...

  10. RF-ARGON PLASMA INDUCED SURFACE MODIFICATION OF PAPER

    OpenAIRE

    HALIL TURGUT SAHIN

    2008-01-01

    The radio frequency (RF) argon plasma induced surface modification of paper revealed novel surface characteristics and substantially changed surface topography. It was found that RF-argon glow discharge affects surface properties resulting in photo-degradation and chain-scission mechanism on paper network structure. High-power and extended treatment time caused increasing elemental carbon, while decreasing the oxygen concentration on paper surface. However, increased hydroxyls and the creatio...

  11. First results of a large-area cryogenic gaseous photomultiplier coupled to a dual-phase liquid xenon TPC

    International Nuclear Information System (INIS)

    We discuss recent advances in the development of cryogenic gaseous photomultipliers (GPM), for possible use in dark matter and other rare-event searches using noble-liquid targets. We present results from a 10 cm diameter GPM coupled to a dual-phase liquid xenon (LXe) TPC, demonstrating—for the first time—the feasibility of recording both primary (''S1'') and secondary (''S2'') scintillation signals. The detector comprised a triple Thick Gas Electron Multiplier (THGEM) structure with cesium iodide photocathode on the first element; it was shown to operate stably at 180 K with gains above 105, providing high single-photon detection efficiency even in the presence of large α particle-induced S2 signals comprising thousands of photoelectrons. S1 scintillation signals were recorded with a time resolution of 1.2 ns (RMS). The energy resolution (σ/E) for S2 electroluminescence of 5.5 MeV α particles was ∼ 9%, which is comparable to that obtained in the XENON100 TPC with PMTs. The results are discussed within the context of potential GPM deployment in future multi-ton noble-liquid detectors

  12. First results of a large-area cryogenic gaseous photomultiplier coupled to a dual-phase liquid xenon TPC

    CERN Document Server

    Arazi, L; Erdal, E; Israelashvili, I; Rappaport, M L; Shchemelinin, S; Vartsky, D; Santos, J M F dos; Breskin, A

    2015-01-01

    We discuss recent advances in the development of cryogenic gaseous photomultipliers (GPM), for possible use in dark matter and other rare-event searches using noble-liquid targets. We present results from a 10 cm diameter GPM coupled to a dual-phase liquid xenon (LXe) TPC, demonstrating - for the first time - the feasibility of recording both primary ("S1") and secondary ("S2") scintillation signals. The detector comprised a triple Thick Gas Electron Multiplier (THGEM) structure with cesium iodide photocathode on the first element; it was shown to operate stably at 180 K with gains above 10^5, providing high single-photon detection efficiency even in the presence of large alpha particle-induced S2 signals comprising thousands of photoelectrons. S1 scintillation signals were recorded with a time resolution of 1.2 ns (RMS). The energy resolution ({\\sigma}/E) for S2 electroluminescence of 5.5 MeV alpha particles was ~9%, which is comparable to that obtained in the XENON100 TPC with PMTs. The results are discusse...

  13. First results of a large-area cryogenic gaseous photomultiplier coupled to a dual-phase liquid xenon TPC

    Science.gov (United States)

    Arazi, L.; Coimbra, A. E. C.; Erdal, E.; Israelashvili, I.; Rappaport, M. L.; Shchemelinin, S.; Vartsky, D.; dos Santos, J. M. F.; Breskin, A.

    2015-10-01

    We discuss recent advances in the development of cryogenic gaseous photomultipliers (GPM), for possible use in dark matter and other rare-event searches using noble-liquid targets. We present results from a 10 cm diameter GPM coupled to a dual-phase liquid xenon (LXe) TPC, demonstrating—for the first time—the feasibility of recording both primary (``S1'') and secondary (``S2'') scintillation signals. The detector comprised a triple Thick Gas Electron Multiplier (THGEM) structure with cesium iodide photocathode on the first element; it was shown to operate stably at 180 K with gains above 105, providing high single-photon detection efficiency even in the presence of large α particle-induced S2 signals comprising thousands of photoelectrons. S1 scintillation signals were recorded with a time resolution of 1.2 ns (RMS). The energy resolution (σ/E) for S2 electroluminescence of 5.5 MeV α particles was ~ 9%, which is comparable to that obtained in the XENON100 TPC with PMTs. The results are discussed within the context of potential GPM deployment in future multi-ton noble-liquid detectors.

  14. Pattern recognition of 136Xe double beta decay events and background discrimination in a high pressure xenon TPC

    International Nuclear Information System (INIS)

    High pressure xenon gas time projection chambers (TPC) for the detection of the neutrinoless double beta decay of 136Xe provide good energy resolution and detailed topological information of events. The ionization topology of the double beta decay event of 136Xe in gaseous xenon has a characteristic shape defined by the two straggling electron tracks ending in two larger energy depositions. With a properly pixelized readout, this topological information is invaluable for performing powerful background discrimination. In this study, we carry out detailed simulations of the signal topology, as well as of the competing topologies from gamma events that typically compose the background at these energies. We define observables based on graph theory concepts and develop automated discrimination algorithms which reduce the background level in the region of interest by around three orders of magnitude, while keeping signal efficiency of 40%. This result supports the competitiveness of current or future ββ experiments based on gas TPCs, such as the Neutrino Xenon TPC (NEXT) currently under construction at the Laboratorio Subterráneo de Canfranc. (paper)

  15. The ALICE TPC, a large 3-dimensional tracking device with fast readout for ultra-high multiplicity events

    CERN Document Server

    Alme, J; Appelshäuser, H; Bablok, S; Bialas, N; Bolgen, R; Bonnes, U; Bramm, R; Braun-Munzinger, P; Campagnolo, R; Christiansen, P; Dobrin, A; Engster, C; Fehlker, D; Foka, P; Frankenfeld, U; Gaardhøje, J J; Garabatos, C; Glässel, P; Gonzalez Gutierrez, C; Gros, P; Gustafsson, H A; Helstrup, H; Hoch, M; Ivanov, M; Janik, R; Junique, A; Kalweit, A; Keidel, R; Kniege, S; Kowalski, M; Larsen, D T; Lesenechal, Y; Lenoir, P; Lindegaard, N; Lippmann, C; Mager, M; Mast, M; Matyja, A; Munkejord, M; Musa, L; Nielsen, B S; Nikolic, V; Oeschler, H; Olsen, E K; Oskarsson, A; Osterman, L; Pikna, M; Rehman, A; Renault, G; Renfordt, R; Rossegger, S; Röhrich, D; Røed, K; Richter, M; Rueshmann, G; Rybicki, A; Sann, H; Schmidt, H R; Siska, M; Sitár, B; Soegaard, C; Soltveit, H K; Soyk, D; Stachel, J; Stelzer, H; Stenlund, E; Stock, R; Strmen, P; Szarka, I; Ullaland, K; Vranic, D; Veenhof, R; Westergaard, J; Wiechula, J; Windelband, B

    2010-01-01

    The design, construction, and commissioning of the ALICE Time-Projection Chamber (TPC) is described. It is the main device for pattern recognition, tracking, and identification of charged particles in the ALICE experiment at the CERN LHC. The TPC is cylindrical in shape with a volume close to 90 m^3 and is operated in a 0.5 T solenoidal magnetic field parallel to its axis. In this paper we describe in detail the design considerations for this detector for operation in the extreme multiplicity environment of central Pb--Pb collisions at LHC energy. The implementation of the resulting requirements into hardware (field cage, read-out chambers, electronics), infrastructure (gas and cooling system, laser-calibration system), and software led to many technical innovations which are described along with a presentation of all the major components of the detector, as currently realized. We also report on the performance achieved after completion of the first round of stand-alone calibration runs and demonstrate result...

  16. Energy resolution for α-particles in doped liquid argon

    International Nuclear Information System (INIS)

    The report describes experiments on the effect of allene doped in liquid argon. In the case of doped argon, a large amount of charge is obtained even at low electric fields and the measured charge increases with the field gradually. This can be explained as follows; part of deposited energy which does not form charge in pure argon contributes to charge signal in doped argon through scintillation photons which ionize allene molecules. The main factors determining the energy resolution for α-particles are considered to be (1) fluctuation in the number of produced ion-electron pairs as expressed by the Fano factor, (2) fluctuation in recombination process, (3) fluctuation in photoionization, (4) fluctuation due to the condition of radioactive source and surface of electrodes, (5) fluctuation in geometrical efficiency due to the range and emission angle of α-particles in liquid argon, and (6) electronic noise of amplifier. The factors (1) and (3) can be neglected because of a large number of associated electrons or photons. In pure liquid argon, the factor (2) may be a cause of bad resolution since the fraction of the produced ion-electron paris which do not recombine is small and the photoionization process never occurs for photons emitted through recombination. (N.K.)

  17. Power Consideration for Pulsed Discharges in Potassium Seeded Argon

    Institute of Scientific and Technical Information of China (English)

    XIA Sheng-Guo; HE Jun-Jia; LIU Ke-Fu

    2007-01-01

    Minimization of energy consumed in plasma generation is critical for applications, in which a large volume of plasmas is needed. We suggest that a high electron density atmospheric pressure plasmas can be generated by pulsed discharges in potassium seeded argon at an elevated temperature with a very small power input. The ionization efficiency and power budget of pulsed discharges in such plasmas are analytically studied. The results show that ionization efficiency of argon, especially at small reduced electric field E/N (the ratio of the electric field to the gas number density), is improved effectively in the presence of small amount of potassium additives. Power input of pulsed discharge to sustain a prescribed average level of ionization in potassium seeded argon is three orders of magnitude lower than that in pure argon. Further, unlike in pure argon, it is found that very short high-voltage pulses with very high repetition rates are unnecessary in potassium seeded argon. A pulse with 100ns of pulse duration, 5kHz of repetition rate, and 2Td (1 Td = 1 ×10-21 Vm2) of E/N is enough to sustain an electron density of 10l9m-3 in 1 atm 1500 K Ar+0.1% K mixture, with a very small power input of about 0.08 × 104 W/m3.

  18. Morphology and characteristics of laser-induced aluminum plasma in argon and in air: A comparative study

    Science.gov (United States)

    Bai, Xueshi; Cao, Fan; Motto-Ros, Vincent; Ma, Qianli; Chen, Yanping; Yu, Jin

    2015-11-01

    In laser-induced breakdown spectroscopy (LIBS), ablation takes place in general in an ambient gas of the atmospheric pressure, often in air but also in noble gas such as argon or helium. The use of noble gas is known to significantly improve the performance of the technique. We investigate in this work the morphology and the characteristics of induced plasma in argon and in air. The purpose is to understand the mechanism of the analytical performance improvement by the use of argon ambient with respective to air ambient and the dependence on the other experimental parameters such as the laser fluence. The observation of plasma morphology in different ambient gases provides also information for better design of the detection system which optimizes the signal collection according to the used ambient gases. More specifically, the expansion of the plasma induced on an aluminum target with nanosecond infrared (1064 nm) laser pulse in two ambient gases, argon and the atmospheric air, has been studied with spectroscopic imaging at short delays and with emission spectroscopy at longer delays. With relatively low ablation laser fluence (65 J/cm2), similar morphologies have been observed in argon and in air over the early stage of plasma expansion, while diagnostics at longer delay shows stronger emission, higher electron density and temperature for plasma induced in argon. With higher ablation laser fluence (160 J/cm2) however, different expansion behaviors have been observed, with a stagnating aluminum vapor near the target surface in air while a propagating plume away from the target in argon. The craters left on the target surface show as well corresponding difference: in air, the crater is very shallow with a target surface chaotically affected by the laser pulse, indicating an effective re-deposition of the ablated material back to the crater; while in Ar a deeper crater is observed, indicating an efficient mass removal by laser ablation. At longer delays, a brighter

  19. Electron densities and energies of a guided argon streamer in argon and air environments

    International Nuclear Information System (INIS)

    In this study we report the temporally and spatially resolved electron densities and mean energies of a guided argon streamer in ambient argon and air obtained by Thomson laser scattering. The plasma is driven by a positive monopolar 3.5 kV pulse, with a pulse width of 500 ns and a frequency of 5 kHz which is synchronized with the high repetition rate laser system. This configuration enables us to use the spatial and temporal stability of the guided streamer to accumulate a multitude of laser/plasma shots by a triple grating spectrometer equipped with an ICCD camera and to determine the electron parameters. We found a strong initial ne-overshoot with a maximum of 7 × 1019 m−3 and a mean electron energy of 4.5 eV. This maximum is followed by a fast decay toward the streamer channel. Moreover, a 2D distribution of the electron density is obtained which exhibits a peculiar mushroom-like shape of the streamer head with a diameter significantly larger than that of the emission profile. A correlation of the width of the streamer head with the expected pre-ionization channel is found. (paper)

  20. Detrapping of tungsten nanoparticles in a direct-current argon glow discharge

    International Nuclear Information System (INIS)

    Nanoparticles are grown from the sputtering of a tungsten cathode in a direct current argon glow discharge. Laser light scattering of a vertical laser sheet going through the plasma reveals that the dust particle cloud is compressed and pushed towards the anode during the discharge. Scanning electron microscopy images of substrates exposed to the plasma for given durations show that dust particles are continuously falling down on the anode during the discharge. These observations are explained by the fact that the electrostatic force at the negative glow-anode sheath boundary cannot balance the ion drag, gravity, and thermophoresis forces for particles of more than a few tens of nanometres in diameter

  1. Honeycomb superlattice pattern in a dielectric barrier discharge in argon/air

    International Nuclear Information System (INIS)

    We report on a honeycomb superlattice pattern in a dielectric barrier discharge in argon/air for the first time. It consists of hexagon lattice and honeycomb framework and bifurcates from a hexagon pattern as the applied voltage increases. A phase diagram of the pattern as a function of the gas component and gas pressure is presented. The instantaneous images show that the hexagon lattice and honeycomb framework are ignited in turn in each half voltage cycle. The honeycomb framework is composed of filaments ignited randomly. The spatiotemporal dynamics of honeycomb superlattice pattern is discussed by wall charges

  2. Low-energy structure in the ionization of argon:Comparison of experiment with theory

    Institute of Scientific and Technical Information of China (English)

    Feng Li-Qiang; Chu Tian-Shu; Wang Li

    2013-01-01

    The above-threshold ionization of argon in an intense 70-fs,400-nm linearly polarized laser pulse has been investigated by the velocity map imaging techniques,combined with an attosecond-resolution quantum wave packet dynamics method.There is a quantitative agreement in all dominant features between the experiment and the theory.Moreover,a peak-splitting phenomenon in the first energy peak has been observed at high pulse intensity.Further,through the theoretical analysis,an ac Stark splitting with evident resonant and nonresonant ionization pathways has been found to be the physical reason for the experimental observations.

  3. Position resolution of the track drift chamber (TPC) in the magnetic field

    International Nuclear Information System (INIS)

    In the present thesis the ExB effect was studied, the expected angular dependence sigmasub(ExB) = g . cosα . (tanα-tanphi) confirmed, and the strength g and the Lorentz angle phi at different argon-methane mixtures under normal conditions measured. α is the angle between the counting wires and the direction of the narrow side of the cathodes. In all performed measurements the ionization track (laser respectively particles) was parallel to the long side of the cathodes. The expected dependence of the pad-response width on the diffusion was observed. An ExB effect of the pad-response width was detected. This contribution lies between 1 until 4%. A change of the ExB effect of the spatial resolution by the counting wire voltage at constant gas gain was not observed. The tangens of the Lorentz angle is to a great extent proportional to the magnetic field strength. The tangens of the Lorentz angle is between 5 and 10% methane independent on the methane concentration and grows between 10 and 30% methane contribution nearly linearly with the methane admixture. (orig.)

  4. New argon-argon (40Ar/39Ar) radiometric age dates from selected subsurface basalt flows at the Idaho National Laboratory, Idaho

    Science.gov (United States)

    Hodges, Mary K.; Turrin, Brent D.; Champion, Duane E.; Swisher, Carl C., III

    2015-01-01

    In 2011, the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, collected samples for 12 new argon-argon radiometric ages from eastern Snake River Plain olivine tholeiite basalt flows in the subsurface at the Idaho National Laboratory. The core samples were collected from flows that had previously published paleomagnetic data. Samples were sent to Rutgers University for argon-argon radiometric dating analyses.

  5. Evolution of Martian atmospheric argon: Implications for sources of volatiles

    Science.gov (United States)

    Hutchins, Kevin S.; Jakosky, Bruce M.

    We have examined processes affecting isotopes of argon (36Ar, 38Ar, 40Ar) in order to determine important atmospheric sources and sinks. Our simple model for argon evolution incorporates production of radiogenic argon in the mantle, outgassing of all argon species by extrusive and intrusive volcanism, and loss to space by knock-on sputtering above the exobase. Sputtering has been shown previously to be an important loss process for atmospheric species, especially isotopes of noble gases, which have few other mechanisms of escape. The integrated evolution of argon (36Ar, 38Ar, and 40Ar, respectively) is modeled in terms of these variables: (1) the planetary concentration of potassium, (2) the fraction of juvenile argon released catastrophically during the first 600 Myr., (3) potential variation in the time-history of sputtering loss from that suggested by Luhmann et al. [1992], and (4) the volume of total outgassing to the surface as compared to outgassing contributed by volcanic release. Our results indicate that Mars has lost between 85-95% of 36Ar and 70-88% of outgassed 40Ar. Due to this substantial loss, the planet must have outgassed the equivalent of between 10 and 100 times the total volume of gases released by extrusive and intrusive volcanics. This indicates that volcanic outgassing, alone, is insufficient to explain the present-day abundances of 36Ar and 40Ar in the Martian atmosphere. Similar calculations for 20Ne suggest outgassed volumes of between 100 and 1800 times in excess of that due to volcanism. This results in a distinct Ne/Ar elemental fractionation, with a preference for outgassing argon, of the order of 10 to 17. Although the results must be evaluated within the model uncertainties, the results are compelling in that they unequivocally show the existence of additional sources of atmospheric volatiles and helps define a means to identify them.

  6. Images

    Data.gov (United States)

    National Aeronautics and Space Administration — Images for the website main pages and all configurations. The upload and access points for the other images are: Website Template RSW images BSCW Images HIRENASD...

  7. Television system for automatic control of electrode position during argon arc welding of large-sized components

    International Nuclear Information System (INIS)

    The article deals with a TV system designed for controlling the position of electrode during argon-arc welding of butt joints with deep bevelling (levelling depth exceeds 10 mm). The operation of the system is based on the processing of bevelling images. The application of the system ensures the travel of the electrode along bevelling axis with an accuracy ±1 mm, minimum. 2 refs., 3 figs

  8. Search for QGP signals at AGS with a TPC spectrometer, and comparison of our event generator predictions for plasma model and cascade interactions

    International Nuclear Information System (INIS)

    We have developed and successfully tested a TPC Magnetic Spectrometer to search for QGP signals produced by ion beams at AGS. We also developed a cascade and plasma event generator the predictions of which are used to illustrate how our technique can detect possible plasma signals. 4 refs., 6 figs., 1 tab

  9. Near-Intrinsic Energy Resolution for 30 to 662 keV Gamma Rays in a High Pressure Xenon Electroluminescent TPC

    CERN Document Server

    Álvarez, V; Cárcel, S; Castel, J; Cebrián, S; Cervera, A; Conde, C A N; Dafni, T; Dias, T H V T; Díaz, J; Egorov, M; Esteve, R; Evtoukhovitch, P; Fernandes, L M P; Ferrario, P; Ferreira, A L; Freitas, E D C; Gehman, V M; Gil, A; Goldschmidt, A; Gómez, H; Gómez-Cadenas, J J; González-Díaz, D; Gutiérrez, R M; Hauptman, J; Morata, J A Hernando; Herrera, D C; Iguaz, F J; Irastorza, I G; Jinete, M A; Labarga, L; Laing, A; Liubarsky, I; Lopes, J A M; Lorca, D; Losada, M; Luzón, G; Marí, A; Martín-Albo, J; Martínez, A; Miller, T; Moiseenko, A; Monrabal, F; Monteiro, C M B; Mora, F J; Moutinho, L M; Vidal, J Muñoz; da Luz, H Natal; Navarro, G; Nebot, M; Nygren, D; Oliveira, C A B; Palma, R; Pérez, J; Aparicio, J L Pérez; Renner, J; Ripoll, L; Rodríguez, A; Rodríguez, J; Santos, F P; Santos, J M F dos; Segui, L; Serra, L; Shuman, D; Simón, A; Sofka, C; Sorel, M; Toledo, J F; Tomás, A; Torrent, J; Tsamalaidze, Z; Vázquez, D; Veloso, J F C A; Villar, J A; Webb, R; White, J T; Yahlali, N

    2012-01-01

    We present the design, data and results from the NEXT prototype for Double Beta and Dark Matter (NEXT-DBDM) detector, a high-pressure gaseous natural xenon electroluminescent time projection chamber (TPC) that was built at the Lawrence Berkeley National Laboratory. It is a prototype of the planned NEXT-100 $^{136}$Xe neutrino-less double beta decay ($0\

  10. Characterisation of GERDA Phase-I detectors in liquid argon

    International Nuclear Information System (INIS)

    GERDA will search for neutrinoless double beta decay in 76Ge by submerging bare enriched HPGe detectors in liquid argon. In GERDA Phase-I, reprocessed enriched-Ge detectors, which were previously operated by the Heidelberg-Moscow and IGEX collaborations, and reprocessed natural-Ge detectors from Genius-TF, will be redeployed. We have tested the operation and performance of bare HPGe detectors in liquid nitrogen and in liquid argon over more than three years with three non-enriched p-type prototype detectors. The detector handling and mounting procedures have been defined and the Phase-I detector technology, the low-mass assembly and the long-term stability in liquid argon have been tested successfully. The Phase-I detectors were reprocessed by Canberra Semiconductor NV, Olen, according to their standard technology but without the evaporation of a passivation layer. After their reprocessing, the detectors have been mounted in their low-mass holders and their characterisation in liquid argon performed. The leakage current, the counting characteristics and the efficiency of the detectors have been measured. The testing of the detectors was carried out in the liquid argon test stand of the GERDA underground Detector Laboratory (GDL) at LNGS. The detectors are now stored underground under vacuum until their operation in GERDA.

  11. Pattern recognition of $^{136}$Xe double beta decay events and background discrimination in a high pressure Xenon TPC

    CERN Document Server

    Cebrian, S; Gomez, H; Herrera, D C; Iguaz, F J; Irastorza, I G; Luzon, G; Segui, L; Tomas, A

    2013-01-01

    High pressure gas detectors offer advantages for the detection of rare events, where background reduction is crucial. For the neutrinoless double beta decay of 136Xe a high pressure xenon gas Time Projection Chamber (TPC) combines a good energy resolution and a detailed topological information of each event. The ionization topology of the double beta decay event of 136Xe in gaseous xenon has a characteristic shape defined by the two straggling electron tracks ending up in two higher ionization charge density blobs. With a properly pixelized readout, this topological information is invaluable to perform powerful background discrimination. In this study we carry out detailed simulations of the signal topology, as well as the competing topologies from gamma events that typically compose the background at these energies. We define observables based on graph theory concepts and develop automated discrimination algorithms which reduce the background level in around three orders of magnitude while keeping signal eff...

  12. Studies of THGEM-based detector at low-pressure Hydrogen/Deuterium, for AT-TPC applications

    International Nuclear Information System (INIS)

    We study the performance of single- and double- THick Gas Electron Multiplier (THGEM) detectors in pure Hydrogen (H2) and Deuterium (D2) at low pressures, in the range of 100–450 torr. The effect of the pressure on the maximum achievable gain, ion-back flow and long-term gain stability are investigated for single and double cascade detectors. In particular, it was found that maximum achievable gains above 104, from single-photoelectrons avalanche, can be achieved for pressures of 200 torr and above; for lower pressure the gains are limited by avalanche-induced secondary effects to a values of around 103. The results of this work are relevant in the field of avalanche mechanism in low-pressure, low-mass noble gases, in particular for applications of THGEM end-cap readout for active-target Time Projection Chambers (TPC) in the field of nuclear physics and nuclear astrophysics

  13. Plasma of Argon Affects the Earliest Biological Response of Different Implant Surfaces: An In Vitro Comparative Study.

    Science.gov (United States)

    Canullo, L; Genova, T; Tallarico, M; Gautier, G; Mussano, F; Botticelli, D

    2016-05-01

    The aim of this in vitro study was to evaluate the early cell response and protein adsorption elicited by the argon plasma treatment of different commercially available titanium surfaces via a chair-side device. Sterile disks made of grade 4 titanium (n= 450, 4-mm diameter) with 3 surface topographies (machined, plasma sprayed, and zirconia blasted and acid etched) were allocated to receive 4 testing treatments (2% and 10% protein adsorption and cell adhesion with MC3T3-E1 and MG-63). Furthermore, the specimens were divided to undergo 1) argon plasma treatment (10 W, 1 bar for 12 min) in a plasma reactor, 2) ultraviolet (UV) light treatment for 2 h (positive control group), or 3) no treatment (control group). Pretreatment surface analyses based on a scanning electron microscope and profilometer images were also performed. Profilometric analysis demonstrated that the evaluated specimens perfectly suit the standard parameters. The use of argon plasma was capable of affecting the quantity of proteins adsorbed on the different surfaces, notwithstanding their roughness or topographic features at a low fetal bovine serum concentration (2%). UV light treatment for 2 h attained similar results. Moreover, both the plasma of argon and the UV light demonstrated a significant increase in the number of osteoblasts adherent at 10 min in all tested surfaces. Within its limitations, this in vitro study highlights the potential biological benefits of treating implant surfaces with plasma of argon or UV, irrespective of the roughness of the titanium surface. However, in vivo experiments are needed to confirm these preliminary data and settle the rationale of a treatment that might be clinically relevant in case of bone-reparative deficiencies. PMID:26848069

  14. Argon-40: Excess in submarine pillow basalts from Kilauea Volcano, Hawaii

    Science.gov (United States)

    Brent, Dalrymple G.; Moore, J.G.

    1968-01-01

    Submarine pillow basalts from Kilauea Volcano contain excess radiogenic argon-40 and give anomalously high potassium-argon ages. Glassy rims of pillows show a systematic increase in radiogenic argon-40 with depth, and a pillow from a depth of 2590 meters shows a decrease in radiogenic argon-40 inward from the pillow rim. The data indicate that the amount of excess radiogenic argon-40 is a direct function of both hydrostatic pressure and rate of cooling, and that many submarine basalts are not suitable for potassium-argon dating.

  15. Metastable argon beam source using a surface wave sustained plasma

    International Nuclear Information System (INIS)

    A new source of metastable argon atoms in the thermal energy range is reported. The source is based on expanding a plasma sustained by electromagnetic surface waves in a quartz tube through a converging nozzle and extracting a beam from the supersonic free-expansion jet. The beam was characterized by time-of-flight measurements which yielded the absolute intensity and velocity distribution of the argon metastables. The source produced a maximum intensity of 6.2x1014 metastables per second per steradian, the highest time-averaged intensity of thermal argon metastables of any source reported to date. A simple picture of an expanding plasma in a recombination regime is used to explain the dependence of the metastable intensity on absorbed power

  16. Pressure regulation in the dry-boxes. Argon purification

    International Nuclear Information System (INIS)

    Each dry-box is equipped with an autonomous installation for circulation and purification of argon and for pressure regulation. This installation consists essentially of a ballast tank, a compressor and two valves electromagnetically controlled by a contact manometer. The compressor and the valves are enclosed in the tank to form a system as compact as possible. The argon is purified by passing it over a furnace filled with titanium-zirconium turnings brought to about 800 deg. C, branching off the main system. With this set-up as well as the automatic maintenance of a constant depression in the box, a quality of argon is obtained whose oxygen contact is undetectable by the manganous hydroxide method. (author)

  17. Energy resolution studies of liquid argon ionization detectors

    International Nuclear Information System (INIS)

    A gridded ionization chamber was used to study the energy resolution in liquid argon with electrons from a 207Bi radioactive source. Argon was purified in the gas phase with a simple and reliable system, capable of reducing the impurity level below 1 ppb O2 equivalent, as inferred by a pulse shape analysis of the ionization signals. The electron spectrum was measured at different drift fields, up to 10.9 KV/cm. At this maximum field, a total energy resolution of 32 keV (fwhm), corresponding to a noise-subtracted energy resolution of 26 keV (fwhm), was obtained for the 976 keV conversion electron line. This value is the best reported so far in liquid argon but is still a factor of seven worse than the theoretical limit set by the Fano factor. The reasons for this discrepancy are discussed. (orig.)

  18. Attenuation measurements of vacuum ultraviolet light in liquid argon revisited

    CERN Document Server

    Neumeier, A; Himpsl, A; Hofmann, M; Oberauer, L; Potzel, W; Schönert, S; Ulrich, A

    2015-01-01

    The attenuation of vacuum ultraviolet light in liquid argon in the context of its application in large liquid noble gas detectors has been studied. Compared to a previous publication several technical issues concerning transmission measurements in general are addressed and several systematic effects were quantitatively measured. Wavelength-resolved transmission measurements have been performed from the vacuum ultraviolet to the near-infrared region. On the current level of sensitivity with a length of the optical path of 11.6 cm, no xenon-related absorption effects could be observed, and pure liquid argon is fully transparent down to the short wavelength cut-off of the experimental setup at 118 nm. A lower limit for the attenuation length of pure liquid argon for its own scintillation light has been estimated to be 1.10 m based on a very conservative approach.

  19. Liquid Argon Calorimetry with LHC-Performance Specifications

    CERN Multimedia

    2002-01-01

    % RD-3 Liquid Argon Calorimetry with LHC-Performance Specifications \\\\ \\\\Good electromagnetic and hadronic calorimetry will play a central role in an LHC detector. Among the techniques used so far, or under development, the liquid argon sampling calorimetry offers high radiation resistence, good energy resolution (electromagnetic and hadronic), excellent calibration stability and response uniformity. Its rate capabilities, however, do not yet match the requirements for LHC. \\\\ \\\\The aim of this proposal is to improve the technique in such a way that high granularity, good hermiticity and adequate rate capabilities are obtained, without compromising the above mentioned properties. To reach this goal, we propose to use a novel structure, the $^{\\prime\\prime}$accordion$^{\\prime\\prime}$, coupled to fast preamplifiers working at liquid argon temperature. Converter and readout electrodes are no longer planar and perpendicular to particles, as usual, but instead they are wiggled around a plane containing particles. ...

  20. Laser propagation and energy absorption by an argon spark

    OpenAIRE

    Bindhu, C V; Harilal, S S; Tillack, M. S.; Najmabadi, F; Gaeris, A C

    2003-01-01

    The laser propagation and energy absorption of an argon spark induced by a laser at different pressures is investigated. 8 ns pulses from a frequency-doubled Q-switched Nd:YAG laser are used to create the spark. The pressure of the argon is varied from 1 atm to 10 Torr. Significant energy absorption by the plasma is observed at high pressures (>100 Torr) while there is negligible absorption when the pressure is lower than 50 Torr. The plasma kernel showed distinct behavior with respect to las...

  1. Modelling of a supersonic ICP argon-hydrogen expansion

    International Nuclear Information System (INIS)

    An expanding argon-hydrogen plasma is investigated by means of simulations. The model is a hydrodynamical model specific for plasma expansions, taking into account the conservation laws of mass, momentum and energy. The code includes the Rankine-Hugoniot relations to calculate shock jump conditions. Results are shown for the expansion from an inductively coupled plasma (ICP) with a separated Laval nozzle. The expansion discussed here is a 'weakly' under-expanding argon-hydrogen plasma. The results from the ICP expansion are verified with probe measurements

  2. Oxygen removal from tantalum and niobium in an argon atmosphere

    International Nuclear Information System (INIS)

    The rate of oxygen removal from tantalum and niobium has been determined as a function of argon pressure (0-760 Torr) at temperatures from 1900 to 24000C. The reduction of the reaction rate v depends only on the argon pressure and can be given by a factor α = v/v0. The following formulae are obtained for α: Ta: α = (1 + 0.15psub(Ar)sup(0.9))-1, Nb: α = (1 + 0.5psub(Ar)sup(0.9))-1.

  3. Photoionization in liquid argon doped with trimethylamine or triethylamine

    International Nuclear Information System (INIS)

    Ionization yields for alpha particles and 1 MeV electrons in liquid argon doped with trimethylamine and with triethylamine have been measured. In both liquids, a collected charge larger than Anderson's results is observed for alpha particles although that for electrons is similar to Anderson's value. By using a new equation for the collected charge, the photoionization quantum efficiencies for scintillation light in liquid argon are estimated to be 0.35+-0.05 for trimethylamine and greater than 0.23+-0.03 for triethylamine. (orig.)

  4. Superconductivity of compressed solid argon from first principles

    Science.gov (United States)

    Ishikawa, Takahiro; Asano, Masamichi; Suzuki, Naoshi; Shimizu, Katsuya

    2015-02-01

    We present first-principles calculations on the superconductivity of solid argon under high pressure. Solid argon is found to take the double hexagonal close-packed structure in pressure range from 420 to 690 GPa, where an insulator-to-metal transition occurs at around 590 GPa. The crystal structure transforms into the hexagonal close-packed structure at 690 GPa and into the face-centered cubic structure at 2300 GPa. The superconducting critical temperature is gradually increased with the successive phase transitions and reaches the maximum value of 12 K at 2600 GPa due to the enhancement of the Fermi surface nesting.

  5. Attosecond-correlated dynamics of two electrons in argon

    Indian Academy of Sciences (India)

    V Sharma; N Camus; B Fischer; M Kremer; A Rudenko; B Bergues; M Kuebel; N G Johnson; M F Kling; T Pfeifer; J Ullrich; R Moshammer

    2014-01-01

    In this work we explored strong field-induced decay of doubly excited transient Coulomb complex Ar** → Ar2++2. We measured the correlated two-electron emission as a function of carrier envelop phase (CEP) of 6 fs pulses in the non-sequential double ionization (NSDI) of argon. Classical model calculations suggest that the intermediate doubly excited Coulomb complex loses memory of its formation dynamics. We estimated the ionization time difference between the two electrons from NSDI of argon and it is 200 ± 100 as (N Camus et al, Phys. Rev. Lett. 108, 073003 (2012)).

  6. The ATLAS liquid argon electromagnetic calorimeter construction status

    CERN Document Server

    Jérémie, A

    2004-01-01

    The construction and assembly of the ATLAS liquid argon electromagnetic calorimeter was described. The calorimeter was built with accordion geometry composed of lead absorbers, liquid argon as ionizing medium and highly granular readout electrodes. The calorimeter was composed of the Barrel and the End-cap, both preceded by presampler sectors to ensure complete recovery of the energy resolution. The detection of cabling errors and testing of the whole calibration chain was done by sending a pulse through the calibration circuit with single readout. (Edited abstract) 3 Refs.

  7. The Erosion of Frozen Argon by Swift Helium Ions

    DEFF Research Database (Denmark)

    Besenbacher, F.; Bøttiger, Jørgen; Graversen, O.; Hansen, Jens Leonhart; Sørensen, H.

    The temperature, energy, and thickness dependence of the erosion rates of frozen argon films when irradiated with 0.1–3 MeV helium ions have been measured. The erosion yields Y are much too high to be explained by the concentional collisional cascade-sputtering theory and are furthermore unequivo......The temperature, energy, and thickness dependence of the erosion rates of frozen argon films when irradiated with 0.1–3 MeV helium ions have been measured. The erosion yields Y are much too high to be explained by the concentional collisional cascade-sputtering theory and are furthermore...

  8. Measurement of Longitudinal Electron Diffusion in Liquid Argon

    CERN Document Server

    Li, Yichen; Thorn, Craig; Qian, Xin; Diwan, Milind; Joshi, Jyoti; Kettell, Steve; Morse, William; Rao, Triveni; Stewart, Jim; Tang, Wei; Viren, Brett

    2015-01-01

    We report the measurement of longitudinal electron diffusion coefficients in liquid argon for electric fields between 100 and 2000 V/cm with a gold photocathode as a bright electron source. The measurement principle, apparatus, and data analysis are described. Our results, which are consistent with previous measurements in the region between 100 to 350 V/cm [1] , are systematically higher than the prediction of Atrazhev-Timoshkin[2], and represent the world's best measurement in the region between 350 to 2000 V/cm. The quantum efficiency of the gold photocathode, the drift velocity and longitudinal diffusion coefficients in gas argon are also presented.

  9. Uranium-liquid argon calorimetry: preliminary results from the DO tests

    International Nuclear Information System (INIS)

    The motivations for using uranium and liquid argon in sampling calorimetry are reviewed and the pros and cons of the technique are discussed. Preliminary results of the DO uranium-liquid argon test program are presented. 9 refs., 7 figs

  10. Web-based oil immersion whole slide imaging increases efficiency and clinical team satisfaction in hematopathology tumor board

    Directory of Open Access Journals (Sweden)

    Zhongchuan Will Chen

    2014-01-01

    Full Text Available Background: Whole slide imaging (WSI is widely used for education and research, but is increasingly being used to streamline clinical workflow. We present our experience with regard to satisfaction and time utilization using oil immersion WSI for presentation of blood/marrow aspirate smears, core biopsies, and tissue sections in hematology/oncology tumor board/treatment planning conferences (TPC. Methods: Lymph nodes and bone marrow core biopsies were scanned at ×20 magnification and blood/marrow smears at 83X under oil immersion and uploaded to an online library with areas of interest to be displayed annotated digitally via web browser. Pathologist time required to prepare slides for scanning was compared to that required to prepare for microscope projection (MP. Time required to present cases during TPC was also compared. A 10-point evaluation survey was used to assess clinician satisfaction with each presentation method. Results: There was no significant difference in hematopathologist preparation time between WSI and MP. However, presentation time was significantly less for WSI compared to MP as selection and annotation of slides was done prior to TPC with WSI, enabling more efficient use of TPC presentation time. Survey results showed a significant increase in satisfaction by clinical attendees with regard to image quality, efficiency of presentation of pertinent findings, aid in clinical decision-making, and overall satisfaction regarding pathology presentation. A majority of respondents also noted decreased motion sickness with WSI. Conclusions: Whole slide imaging, particularly with the ability to use oil scanning, provides higher quality images compared to MP and significantly increases clinician satisfaction. WSI streamlines preparation for TPC by permitting prior slide selection, resulting in greater efficiency during TPC presentation.

  11. a Novel Method for Estimation of Glacier Surface Motion in 1960s from Argon KH-5 Optical Imagery

    Science.gov (United States)

    Li, R.; Ye, W.; Kong, F.; Qiao, G.; Tong, X.; Ma, X.; Guo, S.; Wang, Z.

    2016-06-01

    The Antarctic ice sheet response to the global climate change, specifically the ice flow speed change of the glaciers, has been investigated by many researchers. However, most research results cover the period since 1970s or after the operation of the LANDSAT series. The availability of the film-based ARGON KH-5 data makes it possible to quantify the changes of the Antarctic ice sheet in 1960s. To meet the challenges of processing the low quality film-based ARGON images, a novel method was developed to allow estimating the ice sheet surface motion and reconstructing the surface model simultaneously from ARGON stereo images by decomposing the total parallaxes to terrain and motion based components. A photogrammetric approach was developed to distinguish stable ice surface features from those on motion and use them for recovering the camera orientation information. Several existing Antarctic mapping products were used to establish the ground control. The ice flow speed field is reconstructed using a hierarchical image matching strategy. Firstly, epipolar images are generated via a fundamental matrix derived from correspondences used in the geometric modelling process, and then an image pyramid is built. Second, the normalized cross-correlation (NCC) technique is conducted on each layer of the pyramid to match the extracted features. Since the images were taken at different times, during which the glacier motion occurred, the measured total parallaxes are decomposed to terrain and motion parallaxes according to given ice flow directions which are derived from the iteratively produced DTM or images. Finally, a speed map and a DTM can be generated at each level of the image pyramid. This process repeats itself. At the bottom of the pyramid the final speed map and DTM are produced at a resolution of about 60m and represent the ice flow field of 1963. This approach was tested using two ARGON stereo-pairs in Rayner glacier in East Antarctica. Both the ice flow speed map

  12. Optical emission spectroscopy of argon and hydrogen-containing plasmas

    Science.gov (United States)

    Siepa, Sarah; Danko, Stephan; Tsankov, Tsanko V.; Mussenbrock, Thomas; Czarnetzki, Uwe

    2015-09-01

    Optical emission spectroscopy (OES) on neutral argon is applied to investigate argon, hydrogen and hydrogen-silane plasmas. The spectra are analyzed using an extensive collisional-radiative model (CRM), from which the electron density and the electron temperature (or mean energy) can be calculated. The CRM also yields insight into the importance of different excited species and kinetic processes. The OES measurements are performed on pure argon plasmas at intermediate pressure. Besides, hydrogen and hydrogen-silane plasmas are investigated using argon as a trace gas. Especially for the gas mixture discharges, CRMs for low and high pressure differ substantially. The commonly used line-ratio technique is found to lose its sensitivity for gas mixture discharges at higher pressure. A solution using absolutely calibrated line intensities is proposed. The effect of radiation trapping and the shape of the electron energy distribution function on the results are discussed in detail, as they have been found to significantly influence the results. This work was supported by the Ruhr University Research School PLUS, funded by Germany's Excellence Initiative [DFG GSC 98/3].

  13. High-frequency electrodeless lamps in argon-mercury mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Denisova, N [Institute of Theoretical and Applied Mechanics, Novosibirsk (Russian Federation); Revalde, G [Institute of Atomic Physics and Spectroscopy, University of Latvia, Raina blvd. 19, Riga (Latvia); Skudra, A [Institute of Atomic Physics and Spectroscopy, University of Latvia, Raina blvd. 19, Riga (Latvia); Zissis, G [CPAT, University Toulouse 3, 118 rte de Narbonne, 31062 Toulouse (France); Zorina, N [Institute of Atomic Physics and Spectroscopy, University of Latvia, Raina blvd. 19, Riga (Latvia)

    2005-09-07

    In this paper, numerical and experimental investigations of high-frequency (HF) electrodeless lamps in argon-mercury mixtures are performed. The intensities of the mercury spectral lines having wavelengths {lambda} = 404.66, 435.83, 546.07 nm (7{sup 3}S{sub 1}-6{sup 3}P{sub 0,1,2}) and the resonance line {lambda} = 253.7 nm (6{sup 3} P{sub 1}-6{sup 1}S{sub 0}) are measured at a wide range of mercury pressures, varying the HF generator current and argon filling pressure. A stationary self-consistent model of HF electrodeless discharge lamp is developed including kinetics of the excited mercury and argon atomic states. Based on the developed model, the radiation characteristics of the discharge plasma are calculated. Numerical simulation of the line intensities behaviour in dependence on the mercury pressure, HF generator current and argon filling pressure is performed. The model results are in qualitative agreement with the experimental data. The calculations of the relative intensities of the visible triplet lines 7{sup 3}S{sub 1}-6{sup 3}P{sub 0,1,2} are presented for the first time in this paper.

  14. Measurement of the argon plasma temperature by use of pyrometer

    International Nuclear Information System (INIS)

    The author describes in detail how to use pyrometer to measure the plasma temperature. The temperatures of shock-generated argon plasmas are given in the present work. Measured results of temperature-pressure curve are compared with calculated results using Saha-Debye-Huckel model, which are in good agreement

  15. LArGe. A liquid argon scintillation veto for GERDA

    International Nuclear Information System (INIS)

    LArGe is a GERDA low-background test facility to study novel background suppression methods in a low-background environment, for possible applications in the GERDA experiment. GERDA searches for the neutrinoless double-beta decay in 76Ge, by operating naked germanium detectors submersed into 65 m3 of liquid argon. Similarly, LArGe runs Ge-detectors in 1 m3 (1.4 tons) of liquid argon, which in addition is instrumented with photomultipliers to detect argon scintillation light. The light is used in anti-coincidence with the germanium detectors, to effectively suppress background events that deposit energy in the liquid argon. This work adresses the design, construction, and commissioning of LArGe. The background suppression efficiency has been studied in combination with a pulse shape discrimination (PSD) technique for various sources, which represent characteristic backgrounds to GERDA. Suppression factors of a few times 103 have been achieved. First background data of LArGe (without PSD) yield a background index of (0.12-4.6).10-2 cts/(keV.kg.y) (90% c.l.), which is at the level of the Gerda phase I design goal. Furthermore, for the first time we measure the natural 42Ar abundance (in parallel to Gerda), and have indication for the 2νββ-decay in natural germanium. (orig.)

  16. Study of Liquid Argon Dopants for LHC Hadron Calorimetry

    CERN Multimedia

    2002-01-01

    Hadron calorimetry based on the Liquid Argon Ionisation Chamber technique is one of the choice techniques for LHC-experimentation. A systematic study of the effect of selected dopants on Liquid Argon (LAr) will be carried out with the aim to achieve an improvement on: \\item (i)~``Fast Liquid Argon'' search and study of dopants to increase the drift velocity. It has been already shown that CH&sub4. added at a fraction of one percent increases the drift velocity by a factor of two or more. \\item (ii)~``Compensated Liquid Argon'' search and study of dopants to increase the response to densely ionising particles, resulting in improved compensation, such as photosensitive dopants. \\end{enumerate}\\\\ \\\\ Monitoring of the parameters involved in understanding the response of a calorimeter is essential. In case of doped LAr, the charge yield, the non-saturated drift velocity and the electron lifetime in the liquid should be precisely and simultaneously monitored as they all vary with the level of dopant concentrati...

  17. Aging tests of ethylene contaminated argon/ethane

    International Nuclear Information System (INIS)

    We report on aging tests of argon/ethane gas with a minor (1800 ppM) component of ethylene. The measurements were first conducted with the addition of alcohol to test the suppression of aging by this additive, with exposure up to ∼1.5 C/cm. Tests have included: a proportional tube with ethanol, another with isopropyl alcohol, and for comparison a tube has also been run with ethanol and argon/ethane from CDF's old (ethylene-free) ethane supply. The aging test with ethanol showed no difference between the ethylene-free and the ethylene tube. Furthermore, raw aging rates of argon/ethane and argon/ethane/ethylene were measured by exposing tubes without the addition of alcohol to about 0.1 C/cm. Again, no significant difference was observed. In conclusion, we see no evidence that ethylene contamination up to 1800 ppM has any adverse effect on wire aging. However, this level of ethylene does seem to significantly suppress the gas gain

  18. The ATLAS Liquid Argon Calorimeter: Construction, Integration, Commissioning

    International Nuclear Information System (INIS)

    The ATLAS liquid argon (LAr) calorimeter system consists of an electromagnetic barrel calorimeter and two end caps with electromagnetic, hadronic and forward calorimeters. The liquid argon sampling technique, with an accordion geometry was chosen for the barrel electromagnetic calorimeter (EMB) and adapted to the end cap (EMEC). The hadronic end cap calorimeter (HEC) uses a copper-liquid argon sampling technique with flat plate geometry and is subdivided in depth in two wheels per end-cap. Finally, the forward calorimeter (FCAL) is composed of three modules employing cylindrical electrodes with thin liquid argon gaps.The construction of the full calorimeter system is complete since mid-2004. Production modules constructed in the home institutes were integrated into wheels at CERN in 2003-2004, and inserted into the three cryostats. They passed their first complete cold test before the lowering into the ATLAS cavern. Results of quality checks (e.g. electrical, mechanical, ...) performed on all the 190304 read-out channels after cool down will be reported. End 2004 the ATLAS barrel electromagnetic (EM) calorimeter was installed in the ATLAS cavern and since summer 2005 the front-end electronics are being connected and tested. Results of this first commissioning phase will be shown to demonstrate the high standards of quality control for our detectors

  19. Investigation of non-equilibrium argon and hydrogen plasmas

    International Nuclear Information System (INIS)

    Theoretical and experimental investigations are made into non-equilibrium argon and hydrogen partially-ionized plasmas characteristic of glow-discharge devices such as thyratrons and discharge tubes. For an argon plasma, the development and use of a collisional-radiative, steady-state, three-energy-level model is presented, and experimental measurements on pulsed argon plasmas are briefly mentioned. Two different theoretical argon plasma models are discussed; the first is numerically solved using a non-Maxwellian electron distribution function, while the second is solved analytically, including atom-atom inelastic collisions, assuming Maxwellian electron and atom distribution functions. For a hydrogen plasma, experimental measurements using fluorescence and laser-induced fluorescence have been made in a modified hydrogen thyratron over a wide current density range (from 100 to 8000 A/cm2) for the atomic hydrogen population densities n = 2,3,4. A pronounced rise in the atomic hydrogen excited state populations is observed after the end of the current pulse. A new method to measure the time-resolved electron density was developed and results are presented

  20. X ray diagnostics of the argon filled dense plasma focus

    International Nuclear Information System (INIS)

    An experimental investigation has been conducted to use a Dense Plasma Focus Machine as a prospected high intensity pulsed x ray source. The argon was chosen for the plasma discharge. An effort to reach the highest x ray intensity emission has been made. Although it has not yet been possible to operate with as high energy in argon as in hydrogen, the argon focus provides an intensified ''point source'' of x ray. Based on the diagnostic data and the characteristic difference between argon and hydrogen, a theoretical model of the shock wave was proposed. The x ray energy spectrum of the focus was determined by a crystal spectrometer. Analyzing this spectrum, one can obtain a combined radiation from a 3 keV thermal plasma and a 48 keV electron beam bombarding the center electrode. The polarization of the x ray was measured at a direction perpendicular to the DPF axis. The change of the polarization with time indicated that the plasma impinged radially and then followed by an axial flow. The correlation of the x ray signal with the voltage signal showed that the plasma resistance was rising after the density reached its maximum, and associated the increase of the resistivity as a result of ion-acoustic instability

  1. Scattering of Slow Metastable Argon Atoms by Dielectric Nanospheres

    Science.gov (United States)

    Baudon, J.; Hamamda, M.; Grucker, J.; Perales, F.; Dutier, G.; Ducloy, M.; Bocvarski, V.

    2009-11-01

    The elastic scattering at low energy of metastable argon atoms with internal angular momentum J = 0 and 2 by dielectric nanospheres is investigated. The differential cross sections are calculated for both isotropic and anisotropic interactions. A polarization effect is clearly evidenced. The possible use of a metastable atom beam as a probe of an ensemble of nanospheres deposited on a passive substrate is examined.

  2. LArGe. A liquid argon scintillation veto for GERDA

    Energy Technology Data Exchange (ETDEWEB)

    Heisel, Mark

    2011-04-13

    LArGe is a GERDA low-background test facility to study novel background suppression methods in a low-background environment, for possible applications in the GERDA experiment. GERDA searches for the neutrinoless double-beta decay in {sup 76}Ge, by operating naked germanium detectors submersed into 65 m{sup 3} of liquid argon. Similarly, LArGe runs Ge-detectors in 1 m{sup 3} (1.4 tons) of liquid argon, which in addition is instrumented with photomultipliers to detect argon scintillation light. The light is used in anti-coincidence with the germanium detectors, to effectively suppress background events that deposit energy in the liquid argon. This work adresses the design, construction, and commissioning of LArGe. The background suppression efficiency has been studied in combination with a pulse shape discrimination (PSD) technique for various sources, which represent characteristic backgrounds to GERDA. Suppression factors of a few times 10{sup 3} have been achieved. First background data of LArGe (without PSD) yield a background index of (0.12-4.6).10{sup -2} cts/(keV.kg.y) (90% c.l.), which is at the level of the Gerda phase I design goal. Furthermore, for the first time we measure the natural {sup 42}Ar abundance (in parallel to Gerda), and have indication for the 2{nu}{beta}{beta}-decay in natural germanium. (orig.)

  3. Design of capsules capable of argon-filling

    International Nuclear Information System (INIS)

    The possibility of the use of polycarbosilane capsules as fuel container in inertial confinement fusion experiments was analyzed in the paper. Primary study indicates that the polycarbosilane capsules can be filled with argon by means of diffusion and possess reasonable retention time for deuterium. (author)

  4. Laser-induced vibrational dynamics of ozone in solid argon

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Amstrup, B.; Henriksen, Niels Engholm

    We consider the vibrational dynamics, induced by an intense infrared laser pulse, in an ozone molecule with isotopic substitution, that is, (OOO)-O-16-O-16-O-18 and compare the dynamics in the gas phase and in solid ar on. not perturbed by argon on a time-scale of a few picoseconds and selective...

  5. Experimental and numerical study of high intensity argon cluster beams

    International Nuclear Information System (INIS)

    Experimental and numerical investigations of expansion of argon with homogeneous condensation in supersonic conical nozzle and in free jet behind it were carried out. Optimal parameters (stagnation pressure, nozzle-skimmer distance) for the formation of cluster beam with maximum intensity were determined. Two available models for nonequilibrium nucleation were tested. The numerical results are in satisfactory agreement with the measured data

  6. Thermal decomposition of yttrium(III) valerate in argon

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Yue, Zhao; Tang, Xiao; Pallewatta, Pallewatta G A P; Watenphul, A.; Zimmermann, M. v.

    2014-01-01

    The thermal decomposition of yttrium(III) valerate (Y(C4H9CO2)3) was studied in argon by means of thermogravimetry, differential thermal analysis, IR-spectroscopy, X-ray diffraction, in-situ synchrotron diffraction and hot-stage microscopy as well as room temperature optical microscopy. Melting...

  7. Turbulence and transport in a magnetized argon plasma

    International Nuclear Information System (INIS)

    An experimental study on turbulence and transport in the highly ionized argon plasma of a hollow cathode discharge is described. In order to determine the plasma parameters three standard diagnostics have been used, whilst two diagnostics have been developed to study the plasma turbulence. (Auth.)

  8. Study of a microwave discharge in argon/helium mixtures

    International Nuclear Information System (INIS)

    A discharge created by a surface wave in Argon-Helium mixture is studied. First, the helium influence on plasma parameters has been studied (electron density, electric field, effective collision frequency, etc...), then, on excitation processes in the discharge. Relations between plasma lines, electron density and electric field have been established

  9. Thermophysical properties of multi-shock compressed dense argon.

    Science.gov (United States)

    Chen, Q F; Zheng, J; Gu, Y J; Chen, Y L; Cai, L C; Shen, Z J

    2014-02-21

    In contrast to the single shock compression state that can be obtained directly via experimental measurements, the multi-shock compression states, however, have to be calculated with the aid of theoretical models. In order to determine experimentally the multiple shock states, a diagnostic approach with the Doppler pins system (DPS) and the pyrometer was used to probe multiple shocks in dense argon plasmas. Plasma was generated by a shock reverberation technique. The shock was produced using the flyer plate impact accelerated up to ∼6.1 km/s by a two-stage light gas gun and introduced into the plenum argon gas sample, which was pre-compressed from the environmental pressure to about 20 MPa. The time-resolved optical radiation histories were determined using a multi-wavelength channel optical transience radiance pyrometer. Simultaneously, the particle velocity profiles of the LiF window was measured with multi-DPS. The states of multi-shock compression argon plasma were determined from the measured shock velocities combining the particle velocity profiles. We performed the experiments on dense argon plasmas to determine the principal Hugonoit up to 21 GPa, the re-shock pressure up to 73 GPa, and the maximum measure pressure of the fourth shock up to 158 GPa. The results are used to validate the existing self-consistent variational theory model in the partial ionization region and create new theoretical models. PMID:24559345

  10. Thermal decomposition of yttrium(III) hexanoate in argon

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Suarez Guevara, Maria Josefina; Attique, Fahmida;

    2015-01-01

    The thermal decomposition of yttrium(III) hexanoate (Y(C5H11CO2)3)·xH2O in argon was studied by means of thermogravimetry, differential thermal analysis, IR-spectroscopy, X-ray diffraction at a laboratory Cu-tube source and in-situ experiments at a synchrotron radiation source as well as hot...

  11. The role of metastable atoms in argon-diluted silane radiofrequency plasmas

    OpenAIRE

    Sansonnens, L.; Howling, A.A.; Hollenstein, C.; Dorier, J. L.; Kroll, U.

    2008-01-01

    The evolution of the argon metastable states density has been studied by absorption spectroscopy in power-modulated plasmas of argon and a mixture of 4% silane in argon. A small concentration of silane suppresses the argon metastable states density by molecular quenching. This molecular quenching adds to the electronic collisional dissociation to increase the silane dissociation rate as compared with pure silane plasmas. Using time-resolved emission spectroscopy, the role of metastable states...

  12. Potassium-Argon ages on mesozoic tholeutic dike Swarm in Rio Grande do Norte, Brazil

    International Nuclear Information System (INIS)

    Potassium-argon ages are reported for samples from four localities which represent three laterally separated Mesozoic tholeitic dikes in Precambrian oF Rio Grande do Norte, Brazil. The ages for the dikes are between 167 Ma and 130 Ma. It is shown that most of the ages determined are minimum ages due to argon losses. The methodological approach to identify argon losses is described. Ecess argon cannot be of significant influence on the ages found. (author)

  13. Conversion of an atomic to a molecular argon ion and low pressure argon relaxation

    Science.gov (United States)

    M, N. Stankov; A, P. Jovanović; V, Lj Marković; S, N. Stamenković

    2016-01-01

    The dominant process in relaxation of DC glow discharge between two plane parallel electrodes in argon at pressure 200 Pa is analyzed by measuring the breakdown time delay and by analytical and numerical models. By using the approximate analytical model it is found that the relaxation in a range from 20 to 60 ms in afterglow is dominated by ions, produced by atomic-to-molecular conversion of Ar+ ions in the first several milliseconds after the cessation of the discharge. This conversion is confirmed by the presence of double-Gaussian distribution for the formative time delay, as well as conversion maxima in a set of memory curves measured in different conditions. Finally, the numerical one-dimensional (1D) model for determining the number densities of dominant particles in stationary DC glow discharge and two-dimensional (2D) model for the relaxation are used to confirm the previous assumptions and to determine the corresponding collision and transport coefficients of dominant species and processes. Project supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia (Grant No. ON171025).

  14. Argon metastable dynamics and lifetimes in a direct current microdischarge

    Science.gov (United States)

    Stefanović, Ilija; Kuschel, Thomas; Schröter, Sandra; Böke, Marc

    2014-09-01

    In this paper we study the properties of a pulsed dc microdischarge with the continuous flow of argon. Argon metastable lifetimes are measured by tunable diode laser absorption spectroscopy (TDLAS) and are compared with calculated values which yield information about excitation and de-excitation processes. By increasing the gas flow-rate about 5 times from 10 to 50 sccm, the Arm lifetime increases from 1 to 5 μs due to the reduction of metastable quenching with gas impurities. Optical emission spectroscopy reveals nitrogen and water molecules as the main gas impurities. The estimated N2 density [N2] = 0.1% is too low to explain the measured metastable lifetimes. Water impurity was found to be the main de-excitation source of argon metastable atoms due to high quenching coefficients. The water impurity level of [H2O] = 0.15% to 1% is sufficient to bring calculated metastable lifetimes in line with experiments. The maximum value of water content in the discharge compared to the argon atoms is estimated to approximately 6%, due to the large surface to volume ratio of the microdischarge. The current pulse releases the water molecules from the electrode surface and they are either re-adsorbed in the time between 0.4 ms for [H2O] = 1% and 2.6 ms for [H2O] = 0.15% or pumped out of the discharge with the speed equal to the gas flow-rate. Depending on its partial pressure, the water impurity re-adsorption time is of the order of magnitude or less then the argon gas residence time.

  15. Observations of acoustic-wave-induced superluminescence in an argon plasma

    International Nuclear Information System (INIS)

    It is shown that in an argon discharge plasma it is possible to obtain overpopulation of certain electronic levels of atomic argon under the influence of acoustic waves. When the specified threshold is exceeded, then a superluminescence (in the form of light flashes) from the overpopulated electronic levels of atomic argon is observed

  16. 21 CFR 874.4490 - Argon laser for otology, rhinology, and laryngology.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Argon laser for otology, rhinology, and laryngology. 874.4490 Section 874.4490 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... Argon laser for otology, rhinology, and laryngology. (a) Identification. The argon laser device for...

  17. Clustering and photochemistry of freon CF2Cl2 on argon and ice nanoparticles.

    Science.gov (United States)

    Poterya, Viktoriya; Kočišek, Jaroslav; Lengyel, Jozef; Svrčková, Pavla; Pysanenko, Andriy; Hollas, Daniel; Slavíček, Petr; Fárník, Michal

    2014-07-01

    The photochemistry of CF2Cl2 molecules deposited on argon and ice nanoparticles was investigated. The clusters were characterized via electron ionization mass spectrometry, and the photochemistry was revealed by the Cl fragment velocity map imaging after the CF2Cl2 photodissociation at 193 nm. The complex molecular beam experiment was complemented by ab initio calculations. The (CF2Cl2)n clusters were generated in a coexpansion with Ar buffer gas. The photodissociation of molecules in the (CF2Cl2)n clusters yields predominantly Cl fragments with zero kinetic energy: caging. The CF2Cl2 molecules deposited on large argon clusters in a pickup experiment are highly mobile and coagulate to form the (CF2Cl2)n clusters on ArN. The photodissociation of the CF2Cl2 molecules and clusters on ArN leads to the caging of the Cl fragment. On the other hand, the CF2Cl2 molecules adsorbed on the (H2O)N ice nanoparticles do not form clusters, and no Cl fragments are observed from their photodissociation. Since the CF2Cl2 molecule was clearly adsorbed on (H2O)N, the missing Cl signal is interpreted in terms of surface orientation, possibly via the so-called halogen bond and/or embedding of the CF2Cl2 molecule on the disordered surface of the ice nanoparticles. PMID:24911048

  18. Recent advances with a hybrid micro-pattern gas detector operated in low pressure H2 and He, for AT-TPC applications

    CERN Document Server

    Cortesi, Marco; Bazin, Daniel; Beceiro-Novo, Saul; Yurkon, John; Tanani, Rim Soussi; Wolff, Michael; Stolz, Andreas

    2015-01-01

    In view of a possible application as a charge-particle track readout for an Active-Target Time Projection Chamber (AT-TPC), the operational properties and performances of a hybrid Micro-Pattern Gaseous Detector (MPGD) were investigated in pure low-pressure Hydrogen (H2) and Helium (He). The detector consists of a MICROMesh GAseous Structure (MICROMEGAS) coupled to a single- or multi-cascade THick Gaseous Electron Multiplier (THGEM) as a pre-amplification stage. This study reports of the effective gain dependence of the hybrid-MPGD at relevant pressure (in the range of 200-760 torr) for different detector arrangements. The results of this work are relevant in the field of avalanche mechanism in low-pressure, low-mass noble gases, in particularly for applications of MPGD end-cap readout for active-target Time Projection Chambers (TPC) in the field of nuclear physics and nuclear astrophysics.

  19. Optimization of ultrasound-assisted extraction of total monomeric anthocyanin (TMA) and total phenolic content (TPC) from eggplant (Solanum melongena L.) peel.

    Science.gov (United States)

    Dranca, Florina; Oroian, Mircea

    2016-07-01

    The present study describes the extraction of total monomeric anthocyanin (TMA) and total phenolic content (TPC) from eggplant peel using ultrasonic treatments and methanol and 2-propanol as extraction solvents. The extraction yields were optimized by varying the solvent concentration, ultrasonic frequency, temperature and time of ultrasonic treatment. Box-Behnken design was used to investigate the effect of process variables on the ultrasound-assisted extraction. The results showed that for TPC extraction the optimal condition were obtained with a methanol concentration of 76.6%, 33.88 kHz ultrasonic frequency, a temperature of 69.4 °C and 57.5 min extraction time. For TMA the optimal condition were the following: 54.4% methanol concentration, 37 kHz, 55.1 °C and process time of 44.85 min. PMID:26701808

  20. Development and construction of a large TPC prototype for the ILC and study of τ polarisation in τ decays with the ILD detector

    International Nuclear Information System (INIS)

    This thesis presents two studies which have been made in the framework of the detector development for the International Large Detector (ILD). In the preparation phase for the ILD, prototype studies are performed to develop and optimise the sub-detector technologies which will come into operation. Complementary to these hardware studies, expected physics scenarios are being investigated in full detector simulations. These simulations demonstrate the physics potential of the detector concept and are a benchmark for the detector and the accelerator design. The first part of this thesis gives an introduction to the physics questions addressed to the ILC. Also, the machine and the ILD detector concept are presented. The second part is dedicated to the development and the construction to a large Time Projection Chamber (TPC) prototype (LP). A TPC is foreseen as one of ILD's sub-detectors and shall measure the trajectories of charged particles with an accuracy unprecedented by TPCs operated before. The new prototype offers an infrastructure for the development of modern TPC readout structures which can fulfil the required criteria. Before construction, the design plans of the LP have been optimised for a low material budget of the structure and a very homogeneous drift field. During the manufacturing of the LP, experience with construction techniques has been gained for the construction of the ILD TPC. The third part deals with a simulation study for a polarisation measurement of τ leptons in the process e+e- → τ1τ1 → χ10χ10ττ. Here, the τ1 is the supersymmetric partner of the τ lepton. This simulation study shows the feasibility of the measurement in the chosen SUSY scenario and estimates the accuracy to be expected. Both studies address in particular the track reconstruction capabilities of the ILD detector. Conclusions of the discussed studies and an outlook are presented in part IV. (orig.)

  1. Total polyphenolic compounds contents (TPC), total antioxidant activities (TAA) and HPLC determination of individual polyphenolic compounds in selected Moravian and Austrian wines

    OpenAIRE

    Soyollkham, Badamtsetseg; Valášek, Pavel; Fišera, Miroslav; Fic, Vlastimil; Kubáň, Vlastimil; Hoza, Ignác

    2011-01-01

    Wine samples (Gruner Veltliner (GV) and Zweigelt (ZW) from four different geographical regions of Austria and Czech Republic) were analyzed to determine their total phenolic content (TPC) by applying the Folin-Ciocalteau method, total antioxidant activity (TAA) by FRAP (ferric reducing antioxidant power) and DPPH (1,1-diphenyl-2-picryl-hydrazyl) assays, and to identify and quantify eleven phenolic compounds using a HPLC/UV-VIS method.

  2. Method to determine argon metastable number density and plasma electron temperature from spectral emission originating from four 4p argon levels

    CERN Document Server

    Mariotti, Davide; Sasaki, Takeshi; Koshizaki, Naoto; 10.1063/1.2390631

    2010-01-01

    A simple model and method is proposed here to determine argon metastable number densities and electron temperature with the assumption of a Maxwell-Boltzmann electron energy distribution. This method is based on the availability of experimental relative emission intensities of only four argon lines that originate from any of the 4p argon levels. The proposed model has a relatively wide range of validity for laboratory plasmas that contain argon gas and can be a valuable tool for the emerging field of atmospheric microplasmas, for which diagnostics is still limited.

  3. EFFECTS OF ARGON ON THE PROPERTIES OF RF SPUTTERED AMORPHOUS SILICON

    OpenAIRE

    Shao-Qi, Peng; Qai, Yu; Xian, Zhang; Jing, Ye

    1981-01-01

    The Effects of argon on the properties of rf sputtered amorphous silicon film have been investigated. As the sputtering argon pressure is increased from 2 to 20 mTorr, the content of argon in the amorphous silicon film increases apparently (Argon/Silicon : from 10-2 to 5 x 10-2). The other properties measured as a function of argon pressure PAr show that as the PAr is increased, the photoconductivity, resistivity (300K), conductivity activation energy and optical gap increase also, while the ...

  4. TREX-DM: a low-background Micromegas-based TPC for low-mass WIMP detection

    CERN Document Server

    Iguaz, F J; Aznar, F; Castel, J F; Cebrián, S; Dafni, T; García, J A; Irastorza, I G; Lagraba, A; Luzón, G; Peiró, A

    2015-01-01

    If Dark Matter is made of Weakly Interacting Massive Particles (WIMPs) with masses below 10-20 GeV, the corresponding nuclear recoils in mainstream WIMP experiments are of energies too close, or below, the experimental threshold. New detection techniques, focused on the use of light target nuclei together with low energy thresholds, are needed to get competitive sensitivity to the low-mass range of the WIMP parameter space. Gas Time Projection Chambers (TPCs) can be operated with a variety of target elements, and on account of the amplification in gas, very low thresholds are achievable. Recent advances in electronics and in novel radiopure TPC readouts, especially micro-mesh gas structure (Micromegas) are improving the scalability and low-background prospects of Micromegas-based TPCs. If we add their well-known tracking capabilities, they are a good detection option for the search of low-mass WIMPs. Here we present TREX-DM, a prototype built to test this concept. The detector is designed to host an active ma...

  5. Development and tests of an anode readout TPC with high track separability for large solid angle relativistic ion experiments

    International Nuclear Information System (INIS)

    We have developed, constructed and tested an anode readout TPC with high track separability which is suitable for large solid angle relativistic ion experiments. The readout via rows of short anode wires parallel to the beam has been found in tests to allow two-track separability of ∼2-3 mm. The efficiency of track reconstruction for events from a target, detected inside the MPS 5 KG magnet, is estimated to be >90% for events made by incident protons and pions. 15 GeV/c x A Si ion beams at a rate of ∼25 K per AGS pulse were permitted to course through the chamber and did not lead to any problems. When the gain was reduced to simulate the total output of a minimum ionizing particle, many Si ion tracks were also detected simultaneously with high efficiency. The resolution along the drift direction (parallel to the MPS magnetic field and perpendicular to the beam direction) was <1 mm and the resolution along the other direction /perpendicular/ to the beam direction was <1 mm also. 3 refs., 5 figs

  6. First Commissioning of a Cryogenic Distillation Column for Low Radioactivity Underground Argon

    CERN Document Server

    Back, Henning O; Alton, Andrew; Condon, Christopher; de Haas, Ernst; Galbiati, Cristiano; Goretti, Augusto; Hohmann, Tristan; Ianni, Andrea; Kendziora, Cary; Loer, Ben; Montanari, David; Mosteiro, Pablo; Pordes, Stephen

    2012-01-01

    We report on the performance and commissioning of a cryogenic distillation column for low radioactivity underground argon at Fermi National Accelerator Laboratory. The distillation column is designed to accept a mixture of argon, helium, and nitrogen and return pure argon with a nitrogen contamination less than 10 ppm. In the first commissioning, we were able to run the distillation column in a continuous mode and produce argon that is 99.9% pure. After running in a batch mode, the argon purity was increased to 99.95%, with 500 ppm of nitrogen remaining. The efficiency of collecting the argon from the gas mixture was between 70% and 81%, at an argon production rate of 0.84-0.98 kg/day.

  7. Time-resolved characterization of a filamentary argon discharge at atmospheric pressure in a capillary using emission and absorption spectroscopy

    Science.gov (United States)

    Schröter, Sandra; Pothiraja, Ramasamy; Awakowicz, Peter; Bibinov, Nikita; Böke, Marc; Niermann, Benedikt; Winter, Jörg

    2013-11-01

    An argon/nitrogen (0.999/0.001) filamentary pulsed discharge operated at atmospheric pressure in a quartz tube is characterized using voltage-current measurements, microphotography, optical emission spectroscopy (OES) and absorption spectroscopy. Nitrogen is applied as a sensor gas for the purpose of OES diagnostic. The density of argon metastable atoms Ar(3P2) is determined using tunable diode laser absorption spectroscopy (TDLAS). Using a plasma chemical model the measured OES data are applied for the characterization of the plasma conditions. Between intense positive pulses the discharge current oscillates with a damped amplitude. It is established that an electric current flows in this discharge not only through a thin plasma filament that is observed in the discharge image but also through the whole cross section of the quartz tube. A diffuse plasma fills the quartz tube during a time between intense current pulses. Ionization waves are propagating in this plasma between the spike and the grounded area of the tube producing thin plasma channels. The diameter of these channels increases during the pause between the propagation of ionization waves probably because of thermal expansion and diffusion. Inside the channels electron densities of ˜2 × 1013 cm-3, argon metastable densities ˜1014 cm-3 and a reduced electric field about 10 Td are determined.

  8. Time- and space-resolved spectroscopic characterization of a laser carbon plasma plume in an argon background

    International Nuclear Information System (INIS)

    We present time- and space-resolved spectroscopic observations of a laser-produced carbon plasma, in an argon background. An Nd : YAG laser pulse, 370 mJ, 3.5 ns, at 1.06 µm, with a fluence of 6.9 J cm−2, is used to produce a plasma from a solid graphite target in a 0.5 to 415 mTorr argon background. The spectral emission in the visible is recorded with 15 ns time resolution. We use 20 ns time resolution plasma imaging, filtered at characteristic carbon species emission wavelengths, to study the dynamics of the expanding plasma. The carbon plasma emission is found to evolve from the characteristic of single ionized carbon, to a more complex one, where C2 and C3 molecular bands dominate. Several plasma fronts, with either ionic or molecular composition, are seen to detach from the laser target plasma. The temporal and spatial features of the molecular carbon species evolution are found to be dependent on the actual argon background pressure. (paper)

  9. [Experience with argon laser in urological diseases (author's transl)].

    Science.gov (United States)

    Rothauge, C F; Nöske, H D; Kraushaar, J

    1981-09-01

    The application of the Argon laser in urology has proved to be effective in resecting recurrent, exophytic urothelial tumors of the bladder up to the size of a raspberry. In cases of wide spread bladder tumors we only perform a radiation of the resected area as local recurrence prophylaxis following transurethral resection. The urethroscopic Argon laser irradiation makes laser urethrotomy and evaporisation of urethral strictures possible. Furthermore, a curative and conservative treatment of urethral tumors is possible in combination with chemotherapy. The same applies for the penis carcinoma. Urethral ruptures are also successfully treated by urethroscopic laser recanalization. A determination of the ureteral submucosal course, which may allow a prognosis about the probable maturation, is possible in cases of cystoureteral reflux with the help of laser diaphanoscopy. PMID:7197839

  10. Development of cryogenic installations for large liquid argon neutrino detectors

    CERN Document Server

    Adamowski, M; Geynisman, M; Hentschel, S; Montanari, D; Nessi, M; Norris, B

    2015-01-01

    A proposal for a very large liquid argon (68,000 kg) based neutrino detector is being studied. To validate the design principles and the detector technology, and to gain experience in the development of the cryostats and the cryogenic systems needed for such large experiments, several smaller scale installations will be developed and implemented, at Fermilab and CERN. The cryogenic systems for these installations will be developed, constructed, installed and commissioned by an international engineering team. These installations shall bring the required cooling power under specific conditions to the experiments for the initial cool-down and the long term operation, and shall also guarantee the correct distribution of the cooling power within the cryostats to ensure a homogeneous temperature distribution within the cryostat itself. The cryogenic systems shall also include gaseous and liquid phase argon purification devices to be used to reach and maintain the very stringent purity requirements needed for these...

  11. Measurement of longitudinal electron diffusion in liquid argon

    Science.gov (United States)

    Li, Yichen; Tsang, Thomas; Thorn, Craig; Qian, Xin; Diwan, Milind; Joshi, Jyoti; Kettell, Steve; Morse, William; Rao, Triveni; Stewart, James; Tang, Wei; Viren, Brett

    2016-04-01

    We report the measurement of longitudinal electron diffusion coefficients in liquid argon for electric fields between 100 and 2000 V/cm with a gold photocathode as a bright electron source. The measurement principle, apparatus, and data analysis are described. In the region between 100 and 350 V/cm, our results show a discrepancy with the previous measurement [1]. In the region between 350 and 2000 V/cm, our results represent the world's best measurement. Over the entire measured electric field range, our results are systematically higher than the calculation of Atrazhev-Timoshkin [2]. The quantum efficiency of the gold photocathode, the drift velocity and longitudinal diffusion coefficients in gas argon are also presented.

  12. Evaporation and condensation at a liquid surface. I. Argon

    Science.gov (United States)

    Yasuoka, Kenji; Matsumoto, Mitsuhiro; Kataoka, Yosuke

    1994-11-01

    Molecular dynamics computer simulations were carried out to investigate the dynamics of evaporation and condensation for argon at the temperature of 80 and 100 K. From the decrease of the survival probability of vapor molecules, the ratio of self reflection to collision is estimated to be 12%-15%, only weakly dependent on the temperature. This suggests that argon vapor molecules are in the condition of almost complete capture, and the condensation is considered to be a barrierless process. The total ratio of reflection which is evaluated with the flux correlation of condensation and evaporation is 20% at both temperature. The difference between these two ratios of reflection is ascribed to a phenomenon that vapor molecules colliding with the surface drive out other liquid molecules. This molecule exchange at the surface is as important as the self-reflection, and the conventional picture of condensation as a unimolecular chemical reaction is not appropriate.

  13. Trimming a Metallic Biliary Stent Using an Argon Plasma Coagulator

    International Nuclear Information System (INIS)

    Background. Distal migration is one of the common complications after insertion of a covered metallic stent. Stent repositioning or removal is not always possible in every patient. Therefore, trimming using an argon plasma coagulator (APC) may be a good alternative method to solve this problem. Methods. Metallic stent trimming by APC was performed in 2 patients with biliary Wallstent migration and in another patient with esophageal Ultraflex stent migration. The power setting was 60-100 watts with an argon flow of 0.8 l/min. Observations. The procedure was successfully performed and all distal parts of the stents were removed. No significant collateral damage to the nearby mucosa was observed. Conclusions. In a patient with a distally migrated metallic stent, trimming of the stent is possible by means of an APC. This new method may be applicable to other sites of metallic stent migration

  14. Narrow spectral width laser diode for metastable argon atoms pumping

    Science.gov (United States)

    Gao, Jun; Li, Bin; Wang, Xinbing; Zuo, Duluo

    2016-03-01

    Diode laser pump source with narrow emitting spectrum for optically pumped metastable rare gas laser (OPRGL) of argon was achieved by employing a complex external cavity coupled with volume Bragg grating (VBG). A commercially available c-mount laser diode with rated power of 6 W was used and studied in both the free running mode and VBG external cavity. The maximum output power of 3.9 W with FWHM less than 25 pm and peak wavelength locked around 811.53 nm was obtained from the VBG external cavity laser diode. Precise control of VBG temperature enabled fine tuning of the emission wavelength over a range of 450 pm. Future researches on OPRGL of argon will benefit from it.

  15. Scintillation time dependence and pulse shape discrimination in liquid argon

    International Nuclear Information System (INIS)

    Using a single-phase liquid argon detector with a signal yield of 4.85 photoelectrons per keV of electronic-equivalent recoil energy (keVee), we measure the scintillation time dependence of both electronic and nuclear recoils in liquid argon down to 5 keVee. We develop two methods of pulse shape discrimination to distinguish between electronic and nuclear recoils. Using one of these methods, we measure a background- and statistics-limited level of electronic recoil contamination to be 7.6x10-7 between 52 and 110 keV of nuclear recoil energy (keVr) for a nuclear recoil acceptance of 50% with no nuclear recoil-like events above 62 keVr. Finally, we develop a maximum likelihood method of pulse shape discrimination based on the measured scintillation time dependence

  16. Demonstration of a Lightguide Detector for Liquid Argon TPCs

    CERN Document Server

    Bugel, L; Ignarra, C; Jones, B J P; Katori, T; Smidt, T; Tanaka, H -K

    2011-01-01

    We report demonstration of light detection in liquid argon using an acrylic lightguide detector system. This opens the opportunity for development of an inexpensive, large-area light collection system for large liquid argon time projection chambers. The guides are constructed of acrylic, with TPB embedded in a surface coating with a matching index of refraction. We study the response to early scintillation light produced by a 5.3 MeV alpha. We measure coating responses from 7 to 8 PE on average, compared to an ideal expectation of 10 PE on average. We estimate the attenuation length of light along the lightguide bar to be greater than 0.5 m. The coating response and the attenuation length can be improved; we show, however, that these results are already sufficient for triggering in a large detector.

  17. Opacity measurements in shock-generated argon plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Erskine, D.

    1993-07-01

    Dense plasmas having uniform and constant density and temperature are generated by passage of a planar shock wave through gas. The opacity of the plasma is accurately measured versus wavelength by recording the risetime of emitted light. This technique is applicable to a wide variety of species and plasma conditions. Initial experiments in argon have produced plasmas with 2 eV temperatures, 0.004--0.04 g/cm{sup 3} densities, and coupling parameters {Gamma} {approximately}0.3--0.7. Measurements in visible light are compared with calculations using the HOPE code. An interesting peak in the capacity at 400 nm is observed for the first time and is identified with the 4s-5p transition in excited neutral argon atoms.

  18. The Erosion of Frozen Argon by Swift Helium Ions

    DEFF Research Database (Denmark)

    Besenbacher, F.; Bøttiger, Jørgen; Graversen, O.;

    1981-01-01

    The temperature, energy, and thickness dependence of the erosion rates of frozen argon films when irradiated with 0.1–3 MeV helium ions have been measured. The erosion yields Y are much too high to be explained by the concentional collisional cascade-sputtering theory and are furthermore unequivo......The temperature, energy, and thickness dependence of the erosion rates of frozen argon films when irradiated with 0.1–3 MeV helium ions have been measured. The erosion yields Y are much too high to be explained by the concentional collisional cascade-sputtering theory and are furthermore...... unequivocally associated with electronic processes generated by the bombarding particle. In the present energy region, it is found that Y scales approximately as the electronic stopping power squared, depends on the charge state of the incoming helium ions, and perhaps more important, is independent of the...

  19. Readiness of the ATLAS Liquid Argon Calorimeter for LHC Collisions

    CERN Document Server

    Aad, G; Abdallah, J; Abdelalim, A A; Abdesselam, A; Abdinov, O; Abi, B; Abolins, M; Abramowicz, H; Abreu, H; Acharya, B S; Adams, D L; Addy, T N; Adelman, J; Adorisio, C; Adragna, P; Adye, T; Aefsky, S; Aguilar-Saavedra, J A; Aharrouche, M; Ahlen, S P; Ahles, F; Ahmad, A; Ahmed, H; Ahsan, M; Aielli, G; Akdogan, T; Åkesson, T P A; Akimoto, G; Akimov, A V; Aktas, A; Alam, M S; Alam, M A; Albert, J; Albrand, S; Aleksa, M; Aleksandrov, I N; Alessandria, F; Alexa, C; Alexander, G; Alexandre, G; Alexopoulos, T; Alhroob, M; Aliev, M; Alimonti, G; Alison, J; Aliyev, M; Allport, P P; Allwood-Spiers, S E; Almond, J; Aloisio, A; Alon, R; Alonso, A; Alviggi, M G; Amako, K; Amelung, C; Ammosov, V V; Amorim, A; Amorós, G; Amram, N; Anastopoulos, C; Andeen, T; Anders, C F; Anderson, K J; Andreazza, A; Andrei, V; Anduaga, X S; Angerami, A; Anghinolfi, F; Anjos, N; Antonaki, A; Antonelli, M; Antonelli, S; Antunovic, B; Anulli, F; Aoun, S; Arabidze, G; Aracena, I; Arai, Y; Arce, A T H; Archambault, J P; Arfaoui, S; Arguin, J-F; Argyropoulos, T; Arik, E; Arik, M; Armbruster, A J; Arnaez, O; Arnault, C; Artamonov, A; Arutinov, D; Asai, M; Asai, S; Asfandiyarov, R; Ask, S; Åsman, B; Asner, D; Asquith, L; Assamagan, K; Astbury, A; Astvatsatourov, A; Atoian, G; Auerbach, B; Auge, E; Augsten, K; Aurousseau, M; Austin, N; Avolio, G; Avramidou, R; Axen, D; Ay, C; Azuelos, G; Azuma, Y; Baak, M A; Baccaglioni, G; Bacci, C; Bach, A; Bachacou, H; Bachas, K; Backes, M; Badescu, E; Bagnaia, P; Bai, Y; Bailey, D C; Bain, T; Baines, J T; Baker, O K; Baker, M D; Baltasar Dos Santos Pedrosa, F; Banas, E; Banerjee, P; Banerjee, S; Banfi, D; Bangert, A; Bansal, V; Baranov, S P; Baranov, S; Barashkou, A; Barber, T; Barberio, E L; Barberis, D; Barbero, M; Bardin, D Y; Barillari, T; Barisonzi, M; Barklow, T; Barlow, N; Barnett, B M; Barnett, R M; Baron, S; Baroncelli, A; Barr, A J; Barreiro, F; BarreiroGuimarães da Costa, J; Barrillon, P; Barros, N; Bartoldus, R; Bartsch, D; Bastos, J; Bates, R L; Bathe, S; Batkova, L; Batley, J R; Battaglia, A; Battistin, M; Bauer, F; Bawa, H S; Bazalova, M; Beare, B; Beau, T; Beauchemin, P H; Beccherle, R; Becerici, N; Bechtle, P; Beck, G A; Beck, H P; Beckingham, M; Becks, K H; Bedajanek, I; Beddall, A J; Beddall, A; Bednár, P; Bednyakov, V A; Bee, C; Begel, M; Behar Harpaz, S; Behera, P K; Beimforde, M; Belanger-Champagne, C; Bell, P J; Bell, W H; Bella, G; Bellagamba, L; Bellina, F; Bellomo, M; Belloni, A; Belotskiy, K; Beltramello, O; Ben Ami, S; Benary, O; Benchekroun, D; Bendel, M; Benedict, B H; Benekos, N; Benhammou, Y; Benincasa, G P; Benjamin, D P; Benoit, M; Bensinger, J R; Benslama, K; Bentvelsen, S; Beretta, M; Berge, D; Bergeaas Kuutmann, E; Berger, N; Berghaus, F; Berglund, E; Beringer, J; Bernardet, K; Bernat, P; Bernhard, R; Bernius, C; Berry, T; Bertin, A; Besson, N; Bethke, S; Bianchi, R M; Bianco, M; Biebel, O; Biesiada, J; Biglietti, M; Bilokon, H; Bindi, M; Binet, S; Bingul, A; Bini, C; Biscarat, C; Bitenc, U; Black, K M; Blair, R E; Blanchard, J-B; Blanchot, G; Blocker, C; Blocki, J; Blondel, A; Blum, W; Blumenschein, U; Bobbink, G J; Bocci, A; Boehler, M; Boek, J; Boelaert, N; Böser, S; Bogaerts, J A; Bogouch, A; Bohm, C; Bohm, J; Boisvert, V; Bold, T; Boldea, V; Boldyrev, A; Bondarenko, V G; Bondioli, M; Boonekamp, M; Booth, J R A; Bordoni, S; Borer, C; Borisov, A; Borissov, G; Borjanovic, I; Borroni, S; Bos, K; Boscherini, D; Bosman, M; Bosteels, M; Boterenbrood, H; Bouchami, J; Boudreau, J; Bouhova-Thacker, E V; Boulahouache, C; Bourdarios, C; Boyd, J; Boyko, I R; Bozovic-Jelisavcic, I; Bracinik, J; Braem, A; Branchini, P; Brandenburg, G W; Brandt, A; Brandt, G; Brandt, O; Bratzler, U; Brau, B; Brau, J E; Braun, H M; Brelier, B; Bremer, J; Brenner, R; Bressler, S; Breton, D; Brett, N D; Britton, D; Brochu, F M; Brock, I; Brock, R; Brodbeck, T J; Brodet, E; Broggi, F; Bromberg, C; Brooijmans, G; Brooks, W K; Brown, G; Brubaker, E; Bruckman de Renstrom, P A; Bruncko, D; Bruneliere, R; Brunet, S; Bruni, A; Bruni, G; Bruschi, M; Buanes, T; Bucci, F; Buchanan, J; Buchholz, P; Buckley, A G; Budagov, I A; Budick, B; Büscher, V; Bugge, L; Bulekov, O; Bunse, M; Buran, T; Burckhart, H; Burdin, S; Burgess, T; Burke, S; Busato, E; Bussey, P; Buszello, C P; Butin, F; Butler, B; Butler, J M; Buttar, C M; Butterworth, J M; Byatt, T; Caballero, J; Cabrera Urbán, S; Caforio, D; Cakir, O; Calafiura, P; Calderini, G; Calfayan, P; Calkins, R; Caloba, L P; Caloi, R; Calvet, D; Camarri, P; Cambiaghi, M; Cameron, D; Campabadal-Segura, F; Campana, S; Campanelli, M; Canale, V; Canelli, F; Canepa, A; Cantero, J; Capasso, L; Capeans-Garrido, M D M; Caprini, I; Caprini, M; Capua, M; Caputo, R; Caracinha, D; Caramarcu, C; Cardarelli, R; Carli, T; Carlino, G; Carminati, L; Caron, B; Caron, S; Carrillo Montoya, G D; Carron Montero, S; Carter, A A; Carter, J R

    2010-01-01

    The ATLAS liquid argon calorimeter has been operating continuously since August 2006. At this time, only part of the calorimeter was readout, but since the beginning of 2008, all calorimeter cells have been connected to the ATLAS readout system in preparation for LHC collisions. This paper gives an overview of the liquid argon calorimeter performance measured in situ with random triggers, calibration data, cosmic muons, and LHC beam splash events. Results on the detector operation, timing performance, electronics noise, and gain stability are presented. High energy deposits from radiative cosmic muons and beam splash events allow to check the intrinsic constant term of the energy resolution. The uniformity of the electromagnetic barrel calorimeter response along eta (averaged over phi) is measured at the percent level using minimum ionizing cosmic muons. Finally, studies of electromagnetic showers from radiative muons have been used to cross-check the Monte Carlo simulation. The performance results obtained u...

  20. Evaluation of bone response to synthetic bone grafting material treated with argon-based atmospheric pressure plasma

    International Nuclear Information System (INIS)

    Bone graft materials are utilized to stimulate healing of bone defects or enhance osseointegration of implants. In order to augment these capabilities, various surface modification techniques, including atmospheric pressure plasma (APP) surface treatment, have been developed. This in vivo study sought to assess the effect of APP surface treatment on degradation and osseointegration of Synthograft™, a beta-tricalcium phosphate (β-TCP) synthetic bone graft. The experimental (APP-treated) grafts were subjected to APP treatment with argon for a period of 60 s. Physicochemical characterization was performed by environmental scanning electron microscopy, surface energy (SE), and x-ray photoelectron spectroscopy analyses both before and after APP treatment. Two APP-treated and two untreated grafts were surgically implanted into four critical-size calvarial defects in each of ten New Zealand white rabbits. The defect samples were explanted after four weeks, underwent histological analysis, and the percentages of bone, soft tissue, and remaining graft material were quantified by image thresholding. Material characterization showed no differences in particle surface morphology and that the APP-treated group presented significantly higher SE along with higher amounts of the base material chemical elements on it surface. Review of defect composition showed that APP treatment did not increase bone formation or reduce the amount of soft tissue filling the defect when compared to untreated material. Histologic cross-sections demonstrated osteoblastic cell lines, osteoid deposition, and neovascularization in both groups. Ultimately, argon-based APP treatment did not enhance the osseointegration or degradation of the β-TCP graft. Future investigations should evaluate the utility of gases other than argon to enhance osseointegration through APP treatment. - Highlights: • Degradation/osseointegration of bone graft treated with argon-based APP is studied. • APP treatment did

  1. Unified set of atomic transition probabilities for neutral argon

    OpenAIRE

    Wiese, W.; Brault, J.; Danzmann, K.; Helbig, V.; de Kock, M

    1989-01-01

    The atomic transition probabilities and radiative lifetimes of neutral argon have been the subject of numerous experiments and calculations, but the results exhibit many discrepancies and inconsistencies. We present a unified set of atomic transition probabilities, which is consistent with essentially all recent results, albeit sometimes only after critical reanalysis. The data consistency and scale confirmation has been achieved in two ways. (i) We have carried out some lifetime–branching-ra...

  2. Operational performance of a large liquid argon photon calorimeter

    International Nuclear Information System (INIS)

    We describe the performance of a large (0.9x1.4 m2) liquid argon photon calorimeter in high energy experiments at Fermilab. Resolutions for π0 and electron showers, obtained under data-taking conditions, are compared with electron-beam calibration results. Exceptional spatial and time resolutions have been achieved for isolated showers (sigmasub(x,y)0 data up to 180 GeV are presented. (orig.)

  3. Changes in colour contrast sensitivity associated with operating argon lasers.

    OpenAIRE

    Gündüz, K; Arden, G B

    1989-01-01

    A new test of colour vision using computer graphics has been used to obtain quantitative estimates of colour contrast sensitivity in ophthalmologists before and after they have treated patients by argon laser retinal photocoagulation. The colour vision of all subjects is normal when tested with the 100-hue test and HRR (Hardy, Rittler, Rand) plates, but colour contrast sensitivity measured along a tritan colour confusion line is selectively impaired after a treatment session. No such change o...

  4. Influence of argon pollution on the weld surface morphology

    OpenAIRE

    Krolczyk, G.M.; Nieslony, P.; Krolczyk, J.B.; I. Samardzic; Legutko, S.; S. Hloch; Barrans, Simon; Maruda, R.W.

    2015-01-01

    In this paper the surfaces of butt welded joints in steel tubes were analyzed using an optical 3D measurement system to determine the morphology and topographic parameters. It was established that pollution of the argon shield gas with oxygen did not influence the width of the heat-affected zone. However, the composition of the shield gas significantly influenced the surface asymmetry, Ssk, and its inclination Sku. The measurement of these parameters enabled the selection of a ...

  5. Experimental Investigation of Low Pressure Audio Frequency Discharge in Argon

    International Nuclear Information System (INIS)

    Experimental data obtained on audio frequency (100–10000 Hz) discharge in argon at four pressures 50, 60, 70, and 80 mTorr are presented. The data show significant changes of the discharge current waveform with frequency. These changes seem to be associated with the glow discharge profile and colour. An empirical model based on the assumption of a frequency-dependent breakdown voltage is used to describe the experimental data

  6. STATUS OF THE ATLAS LIQUID ARGON CALORIMETER AND ITS PERFORMANCE

    CERN Document Server

    Berillari, T; The ATLAS collaboration

    2011-01-01

    The liquid argon (LAr) calorimeters are used in ATLAS for all electromagnetic and for hadron calorimetry. The LAr calorimeter system consists of an electromagnetic barrel calorimeter and two endcaps with electromagnetic, hadronic and forward calorimeters. The latest status of the detector as well as problems and solutions addressed during the last years will be presented. Aspects of operation of a large detector over a long time period will be summarized and selected topics showing the performance of the detector will be shown.

  7. Thermal decomposition of lanthanum(III) butyrate in argon atmosphere

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Yue, Zhao; Xiao, Tang;

    2013-01-01

    The thermal decomposition of La(C3H7CO2)3·xH2O (x≈0.82) was studied in argon during heating at 5K/min. After the loss of bound H2O, the anhydrous butyrate presents at 135°C a phase transition to a mesophase, which turns to an isotropic liquid at 180°C. The decomposition of the anhydrous butyrate ...

  8. Argon laser photocoagulation of cyclodialysis clefts after cataract surgery

    International Nuclear Information System (INIS)

    Three patients with cyclodialysis clefts, hypotony and hypotonic retinopathy subsequent to cataract surgery were treated with argon laser photocoagulation. The hypotony was reversed in each patient and their visual acuity was normalized. Laser photocoagulation is a noninvasive treatment that can be repeated easily and safely. The complications of the treatment are minor. A hypertensive episode commonly occurs in the early postoperative period. (au) 8 refs

  9. Spectroscopy of Argon Excited in an Electron Beam Ion Trap

    Energy Technology Data Exchange (ETDEWEB)

    Trabert, E

    2005-04-18

    Argon is one of the gases best investigated and most widely used in plasma discharge devices for a multitude of applications that range from wavelength reference standards to controlled fusion experiments. Reviewing atomic physics and spectroscopic problems in various ionization stages of Ar, the past use and future options of employing an electron beam ion trap (EBIT) for better and more complete Ar data in the x-ray, EUV and visible spectral ranges are discussed.

  10. Spectroscopic Investigations of Air Entrainment into an Argon Plasma Jet

    Czech Academy of Sciences Publication Activity Database

    Hlína, Jan; Něnička, Václav; Šlechta, Jiří; Krejčí, Luděk; Dolínek, Vladimír; Sopuch, Pavel

    Vol. 3. Orléans : GREMI, CNRS/University of Orléans, 2001 - (Bouchoule, A.; Pouvesle, J.), s. 1107-1110 [INTERNATIONAL SYMPOSIUM ON PLASMA CHEMISTRY /15./. Orléans (FR), 09.07.2001-13.07.2001] R&D Projects: GA AV ČR IAA1057001; GA ČR GA202/99/0389 Keywords : nitrogen molecular bands * dependence of nitrogen radiations on the argon flow rate Subject RIV: BL - Plasma and Gas Discharge Physics

  11. An estimation of the effective number of electrons contributing to the coordinate measurement with a TPC II

    OpenAIRE

    Kobayashi, Makoto

    2013-01-01

    For time projection chambers (TPCs) the accuracy in measurement of the track coordinates along the pad-row direction deteriorates with the drift distance (z): Resolution**2 = D**2 * z / N_eff, where D is the diffusion constant and N_eff is the effective number of electrons. Experimentally it has been shown that N_eff is smaller than the average number of drift electrons per pad row (). In the previous work we estimated N_eff by means of a simple numerical simulation for argon-based gas mixtur...

  12. Underground operation of the ICARUS T600 LAr-TPC: first results

    Science.gov (United States)

    Rubbia, C.; Antonello, M.; Aprili, P.; Baibussinov, B.; Baldo Ceolin, M.; Barzè, L.; Benetti, P.; Calligarich, E.; Canci, N.; Carbonara, F.; Cavanna, F.; Centro, S.; Cesana, A.; Cieslik, K.; Cline, D. B.; Cocco, A. G.; Dabrowska, A.; Dequal, D.; Dermenev, A.; Dolfini, R.; Farnese, C.; Fava, A.; Ferrari, A.; Fiorillo, G.; Gibin, D.; Gigli Berzolari, A.; Gninenko, S.; Golan, T.; Guglielmi, A.; Haranczyk, M.; Holeczek, J.; Karbowniczek, P.; Kirsanov, M.; Kisiel, J.; Kochanek, I.; Lagoda, J.; Lantz, M.; Mania, S.; Mannocchi, G.; Mauri, F.; Menegolli, A.; Meng, G.; Montanari, C.; Muraro, S.; Otwinowski, S.; Palamara, O.; Palczewski, T. J.; Periale, L.; Piazzoli, A.; Picchi, P.; Pietropaolo, F.; Plonski, P.; Prata, M.; Przewlocki, P.; Rappoldi, A.; Raselli, G. L.; Rossella, M.; Sala, P.; Scantamburlo, E.; Scaramelli, A.; Segreto, E.; Sergiampietri, F.; Sobczyk, J.; Stefan, D.; Stepaniak, J.; Sulej, R.; Szarska, M.; Terrani, M.; Varanini, F.; Ventura, S.; Vignoli, C.; Wachala, T.; Wang, H.; Yang, X.; Zalewska, A.; Zaremba, K.; Zmuda, J.

    2011-07-01

    Important open questions are still present in fundamental Physics and Cosmology, like the nature of Dark Matter, the matter-antimatter asymmetry and the validity of the Standard Model of particle interactions. Addressing these questions requires a new generation of massive particle detectors to explore the subatomic and astrophysical worlds. ICARUS T600 is the first large mass (760 tons) example of a new generation of detectors able to combine the imaging capabilities of the old famous ``bubble chamber'' with the excellent energy measurement of huge electronic detectors. ICARUS T600 now operates at the Gran Sasso underground laboratory and is used to study cosmic rays, neutrino oscillations and the proton decay. The potential for doing physics of this novel telescope is presented through a few examples of neutrino interactions reconstructed with unprecedented detail. Detector design and early operation are also reported.

  13. Two dimensional condensation of argon adsorbed on lamellar halides

    International Nuclear Information System (INIS)

    Lamellar halides such as NiCl2, FeCl2, NiBr2, MnBr2, MgBr2, CdBr2, CoI2, FeI2, MnI2, CaI2 and PbI2 were sublimed in a rapid stream of dry nitrogen. The adsorption of argon on such materials shows stepped isotherms which reveal two dimensional condensations. From sets of isotherms the Helmholtz free energy, the internal energy and the entropy of the successive layers are determined. From the entropy of the first layer the role of the potential relief of the adsorbent surface on the structure of the adsorbed layer may be determined while the Helmholtz free energy reveals how the ionic character of the adsorbent governs the attractive force of adsorption. The study of the second third and fourth layers shows that their growth follows quite a different behaviour depending on whether the Van der Waals diameter of argon is greater or smaller than the distance between adjacent anions on the crystal surface. A proposition is made to account for the difference in the critical temperatures of the first and second dense layers in terms of the vibrationnal state of their respective substrate. The occurence for the maximum critical temperature observed of corresponding to a triangular layer 3% more expanded than the (111) plane of solid argon is discussed

  14. A liquid argon scintillation veto for the Gerda experiment

    Energy Technology Data Exchange (ETDEWEB)

    Wegmann, Anne [Max-Planck Institut fuer Kernphysik, Heidelberg (Germany); Collaboration: GERDA-Collaboration

    2013-07-01

    Gerda is an experiment to search for the neutrinoless double beta decay of {sup 76}Ge. Bare germanium detectors are operated in a cryostat with 65 m{sup 3} of liquid argon (LAr). To reach the aspired background index of ≤10{sup -3} cts/(keV.kg.yr) for Phase II active background-suppression techniques will be applied, including an active liquid argon veto (LAr veto). A light instrumentation of LAr installed in the LArGe test facility has demonstrated that the detection of argon scintillation light can be used to effectively suppress background events in the germanium, which simultaneously deposit energy in LAr. Based on these results, Gerda pursues several options for the light instrumentation, which have to be compatible with the stringent radiopurity requirements of the experiment and should provide a significant suppression of the background in the region of interest around Q{sub ββ} at 2039 keV. This talk gives an account of the competing design options under investigation in the Gerda collaboration. The design options using photomultiplier tubes (PMT) and silicon photomultipliers (SiPM) are discussed, together with their expected performance from Monte Carlo simulations. In addition, the progress of development is reported, along with the design criteria for light instrumentation in Gerda.

  15. A liquid argon scintillation veto for the Gerda experiment

    International Nuclear Information System (INIS)

    Gerda is an experiment to search for the neutrinoless double beta decay of 76Ge. Bare germanium detectors are operated in a cryostat with 65 m3 of liquid argon (LAr). To reach the aspired background index of ≤10-3 cts/(keV.kg.yr) for Phase II active background-suppression techniques will be applied, including an active liquid argon veto (LAr veto). A light instrumentation of LAr installed in the LArGe test facility has demonstrated that the detection of argon scintillation light can be used to effectively suppress background events in the germanium, which simultaneously deposit energy in LAr. Based on these results, Gerda pursues several options for the light instrumentation, which have to be compatible with the stringent radiopurity requirements of the experiment and should provide a significant suppression of the background in the region of interest around Qββ at 2039 keV. This talk gives an account of the competing design options under investigation in the Gerda collaboration. The design options using photomultiplier tubes (PMT) and silicon photomultipliers (SiPM) are discussed, together with their expected performance from Monte Carlo simulations. In addition, the progress of development is reported, along with the design criteria for light instrumentation in Gerda.

  16. Demonstration and comparison of photomultiplier tubes at liquid Argon temperature

    International Nuclear Information System (INIS)

    Liquified noble gases are widely used as a target in direct Dark Matter searches. Signals from scintillation in the liquid, following energy deposition from the recoil nuclei scattered by Dark Matter particles (e.g. WIMPs), should be recorded down to very low energies by photosensors suitably designed to operate at cryogenic temperatures. Liquid Argon based detectors for Dark Matter searches currently implement photomultiplier tubes for signal read-out. In the last few years PMTs with photocathodes operating down to liquid Argon temperatures (87 K) have been specially developed with increasing Quantum Efficiency characteristics. The most recent of these, Hamamatsu Photonics K.K. Mod. R11065 with peak QE up to about 35%, has been extensively tested within the R and D program of the WArP Collaboration. During these tests the Hamamatsu PMTs showed excellent performance and allowed obtaining a light yield around 7 phel/keVee in a Liquid Argon detector with a photocathodic coverage in the 12% range, sufficient for detection of events down to few keVee of energy deposition. This shows that this new type of PMT is suited for experimental applications, in particular for new direct Dark Matter searches with LAr-based experiments.

  17. Electron density measurements of high pressure argon surface wave plasmas

    International Nuclear Information System (INIS)

    The electron density of an argon standing surface wave plasma has been measured from Stark broadening of the hydrogen H/sub beta/ (4861A) line. The experimental setup, consisting of two coaxial cavities, was similar to that reported by Rogers and Asmussen. The plasma was generated by 45 watts per cavity of CW, 2.54 GHz microwave power in a 6 mm O.D. (4 mm I.D.) quartz tube. Experimental argon gas pressure varied from 50 torr to over one atmosphere. Small amounts (1-5%) of hydrogen added to the argon plasma were found to shorten the plasma by as much as 80%. Thus, the Stark measurements were made using trace amounts of hydrogen. The line width of H/sub beta/ was measured with a 1 meter Czerny-Turner grating spectrometer. The Stark broadening measurements revealed that the electron density is between 1013 and 1014 electrons/cc for a pressure range of 50 to 1000 torr. These measurements agree very well with the electron density determined from the wavelength of standing surface waves. The volume of the plasma was also measured photographically and average plasma power densities (absorbed power in the plasma divided by the plasma volume) was calculated

  18. Isotopic fractionation of argon during stepwise release from shungite

    International Nuclear Information System (INIS)

    In previous attempts to determine the 40Ar/36Ar ratio in the ancient atmosphere, the only direct measurement yielding a value below the atmospheric value of today is for argon released at low temperatures from a pre-Cambrian shungite, an amorphous carbon mineral The present work confirms a low value for 40Ar/36Ar in gas released from a type I shungite at low temperatures. But quantitative scrutiny of the accompanying 38AR/36Ar ratios and the enhanced ratio of 40Ar/36Ar for the fractions released at high temperatures shows convincingly that the effect seen here is an artifact of the stepwise heating and the argon diffusion mobilized thereby. The low 40Ar/36Ar previously obtained is very likely from the same cause rather than reflecting the isotopic composition of the pre-Cambrian atmosphere. The vitreous character of and the sharp, conchoidal fractures seen in the specimens of type I shungite suggest that the substance may exhibit simple volume diffusion over macroscopic dimensions as glasses do. If so, the diffusion parameters (D infinitely = 3 x 10-4 cm2/s and E = 11 kcal/mole) obtained from the data imply rapid exchange with the atmosphere for any argon initially trapped in centimenter-thick veins of the material. (orig.)

  19. Isotopic fractionation of argon during stepwise release from shungite

    Science.gov (United States)

    Rison, W.

    1980-05-01

    It is noted that in previous attempts to determine the Ar-40/Ar-36 ratio in the ancient atmosphere, the only direct measurement yielding a value below the atmospheric value of today is for argon released at low temperatures from a pre-Cambrian shungite. In the present work, a low value for Ar-40/Ar-36 in gas released from a type I shungite at low temperatures is confirmed. Attention is given to a study of the accompanying Ar-38/Ar-36 ratios and the enhanced ratio of Ar-40/Ar-36 for the fractions released at high temperatures which shows that the effect observed is a result of the stepwise heating and the argon diffusion mobilized thereby. It is suggested that the low Ar-40/Ar-36 obtained in the past is from the same source rather than reflecting the isotropic composition of the pre-Cambrian atmosphere, and that the type I shungite may exhibit simple volume diffusion over macroscopic dimensions as glasses do. It is concluded that if this is so, the diffusion parameters obtained from the data would imply rapid exchange with the atmosphere for any argon initially trapped in the veins of the material.

  20. ARAPUCA a new device for liquid argon scintillation light detection

    International Nuclear Information System (INIS)

    We present a totally innovative device for the detection of liquid argon scintillation light, that has been named ARAPUCA (Argon R and D Advanced Program at UniCAmp). It is composed of a passive light collector and of active devices. The latters are standard SiPMs that operate at liquid argon temperature, while the passive collector is based on a new technology, never explored in this field before. It is a photon trap, that allows to collect light with extremely high efficiency. The total detection efficiency of the device can be tuned by modifying the ratio between the area of the active devices (SiPM) and the area of the optical window. For example, it will allow to reach a detection efficiency at the level of 1% on a surface of 50 × 50 cm2 with an active coverage of 2 × 2 cm2 (two/three large area SiPM). It is also a cheap device, since the major part of its cost is represented by the active devices. For these reason this appears to be the ideal device for scintillation light detection in large Time Projection Chambers. With appropriate modifications it can be used also in next generation Dark Matter detectors

  1. Demonstration and comparison of photomultiplier tubes at liquid Argon temperature

    Science.gov (United States)

    Acciarri, R.; Antonello, M.; Boffelli, F.; Cambiaghi, M.; Canci, N.; Cavanna, F.; Cocco, A. G.; Deniskina, N.; Di Pompeo, F.; Fiorillo, G.; Galbiati, C.; Grandi, L.; Kryczynski, P.; Meng, G.; Montanari, C.; Palamara, O.; Pandola, L.; Perfetto, F.; Piano Mortari, G. B.; Pietropaolo, F.; Raselli, G. L.; Rubbia, C.; Segreto, E.; Szelc, A. M.; Triossi, A.; Ventura, S.; Vignoli, C.; Zani, A.

    2012-01-01

    Liquified noble gases are widely used as a target in direct Dark Matter searches. Signals from scintillation in the liquid, following energy deposition from the recoil nuclei scattered by Dark Matter particles (e.g. WIMPs), should be recorded down to very low energies by photosensors suitably designed to operate at cryogenic temperatures. Liquid Argon based detectors for Dark Matter searches currently implement photomultiplier tubes for signal read-out. In the last few years PMTs with photocathodes operating down to liquid Argon temperatures (87 K) have been specially developed with increasing Quantum Efficiency characteristics. The most recent of these, Hamamatsu Photonics K.K. Mod. R11065 with peak QE up to about 35%, has been extensively tested within the R&D program of the WArP Collaboration. During these tests the Hamamatsu PMTs showed excellent performance and allowed obtaining a light yield around 7 phel/keVee in a Liquid Argon detector with a photocathodic coverage in the 12% range, sufficient for detection of events down to few keVee of energy deposition. This shows that this new type of PMT is suited for experimental applications, in particular for new direct Dark Matter searches with LAr-based experiments.

  2. Status of the ATLAS Liquid Argon Calorimeter and its Performance

    CERN Document Server

    Barillari, T; The ATLAS collaboration

    2011-01-01

    The ATLAS experiment is designed to study the proton-proton collisions produced at the LHC with a centre-of-mass energy of 14 TeV. Liquid argon (LAr) sampling calorimeters are used in ATLAS for all electromagnetic calorimetry covering the pseudorapidity region |eta|<3.2, as well as for hadronic calorimetry from |eta|=1.4 to |eta|=4.8. The calorimeter system consists of an electromagnetic barrel calorimeter and two endcaps with electromagnetic (EMEC), hadronic (HEC) and forward (FCAL) calorimeters. The lead-liquid argon sampling technique with an accordion geometry was chosen for the barrel electromagnetic calorimeter (EMB) and adapted to the endcap (EMEC). This geometry allows a uniform acceptance over the whole azimuthal range without any gap. The hadronic endcap calorimeter (HEC) uses a copper-liquid argon sampling technique with plate geometry and is subdivided into two wheels in depth per end-cap. Finally, the forward calorimeter (FCAL) is composed of three modules featuring cylindrical electrodes ...

  3. ARAPUCA a new device for liquid argon scintillation light detection

    Science.gov (United States)

    Machado, A. A.; Segreto, E.

    2016-02-01

    We present a totally innovative device for the detection of liquid argon scintillation light, that has been named ARAPUCA (Argon R&D Advanced Program at UniCAmp). It is composed of a passive light collector and of active devices. The latters are standard SiPMs that operate at liquid argon temperature, while the passive collector is based on a new technology, never explored in this field before. It is a photon trap, that allows to collect light with extremely high efficiency. The total detection efficiency of the device can be tuned by modifying the ratio between the area of the active devices (SiPM) and the area of the optical window. For example, it will allow to reach a detection efficiency at the level of 1% on a surface of 50 × 50 cm2 with an active coverage of 2 × 2 cm2 (two/three large area SiPM). It is also a cheap device, since the major part of its cost is represented by the active devices. For these reason this appears to be the ideal device for scintillation light detection in large Time Projection Chambers. With appropriate modifications it can be used also in next generation Dark Matter detectors.

  4. Roles of argon seeding in energy confinement and pedestal structure in JT-60U

    International Nuclear Information System (INIS)

    The mechanism of improving energy confinement with argon seeding at high density has been investigated in JT-60U. Better confinement is sustained at high density by argon seeding accompanied by higher core and pedestal temperatures. The electron density profiles become flatter with increasing density in conventional H-mode plasmas, whereas peaked density profiles are maintained with argon seeding. Density peaking and dilution effects lower the pedestal density at a given averaged density. The pedestal density in the argon seeded plasmas, which is lower than that in plasmas with deuterium puff, enables the pedestal temperature to be higher, whereas the increase in the pedestal pressure with argon seeding is small. High pedestal temperature is a boundary condition for high core temperature through profile stiffness, which leads to better confinement with argon seeding. The density peaking is a key factor of sustaining better confinement in argon seeded H-mode plasmas. The radiative loss power density is predominantly enhanced in the edge region by argon puff. The role of argon seeding in the pedestal characteristics has also been examined. The pedestal width becomes larger continuously with edge collisionality, but is nearly independent of the presence of argon seeding. (paper)

  5. Argon-41 production and evolution at the Oregon State University TRIGA Reactor (OSTR)

    International Nuclear Information System (INIS)

    In this study, argon-41 concentrations were measured at various locations within the reactor facility to assess the accuracy of models used to predict argon-41 evolution from the reactor tank, and to determine the relationship between argon gas evolution from the tank and subsequent argon-41 concentrations throughout the reactor room. In particular, argon-41 was measured directly above the reactor tank with the reactor tank lids closed, at other accessible locations on the reactor top with the tank lids both closed and open, and at several locations on the first floor of the reactor room. These measured concentrations were then compared to values calculated using a modified argon-41 production and evolution model for TRIGA reactor tanks and ventilation values applicable to the OSTR facility. The modified model was based in part on earlier TRIGA models for argon-41 production and release, but added features which improved the agreement between predicted and measured values. The approximate dose equivalent rate due to the presence of argon-41 in reactor room air was calculated for several different locations inside the OSTR facility. These dose rates were determined using the argon-41 concentration measured at each specific location, and were subsequently converted to a predicted quarterly dose equivalent for each location based on the reactor's operating history. The predicted quarterly dose equivalent values were then compared to quarterly doses measured by film badges deployed as dose-integrating area radiation monitors at the locations of interest. The results indicate that the modified production and evolution model is able to predict argon-41 concentrations to within a factor of ten when compared to the measured data. Quarterly dose equivalents calculated from the measured argon-41 concentrations and the reactor's operating history seemed consistent with results obtained from the integrating area radiation monitors. Given the argon-41 concentrations measured

  6. Precision meson spectroscopy. Diffractive production at COMPASS and development of a GEM-based TPC for PANDA

    International Nuclear Information System (INIS)

    Meson spectroscopy is a unique way to access Quantum Chromo Dynamics (QCD) and learn about its properties. Due to the non-Abelian structure, QCD predicts new states of matter with gluonic degrees of freedom. In particular q anti qg hybrids, which can have spin-exotic quantum numbers forbidden for conventional q anti q mesons, are expected to exist. Such states were searched for in the past, mostly in the light-quark sector. However, the experimental situation is still ambiguous and needs to be clarified. Further insights will certainly also come from the heavy-quark spectroscopy. Several new charmonium-like resonances were for example discovered during the last years, which have to be studied in more detail by future experiments to reveal their nature. Diffractive dissociation reactions at COMPASS provide clean access to meson resonances with masses below 2.5 GeV/c2. During a pilot run in 2004 using pion beams on lead targets, a competitive number of π-π-π+ final state events were recorded within a few days of data taking. A full partial wave analysis (PWA) of these data has been performed for this dissertation, concentrating on the kinematic domain of large momentum transfer (t' element of [0.1, 1.0] GeV2/c2). While well-known mesons are resolved with high quality, also a strong signal consistent with the much disputed hybrid candidate π1(1600) is observed in the spin-exotic JPC = 1-+ partial wave. A Breit-Wigner parameterization yields a mass and width of 1.660+0.010-0.074 and 0.269+0.063-0.085 GeV/c2, respectively. In addition, a first PWA of events with small momentum transfer (t' element of [10-3,10-2] GeV2/c2) has been carried out, yielding several high-mass radial-excitation states. In the future, the PANDA experiment at the FAIR facility will perform highprecision spectroscopy in the charm-sector employing anti pp annihilations. Due to its excellent tracking capabilities for charged particles, a time projection chamber (TPC) has been proposed for the

  7. Precision meson spectroscopy. Diffractive production at COMPASS and development of a GEM-based TPC for PANDA

    Energy Technology Data Exchange (ETDEWEB)

    Weitzel, Quirin

    2008-09-24

    . Due to its excellent tracking capabilities for charged particles, a time projection chamber (TPC) has been proposed for the central tracker of PANDA. A continuous operation without ion gate is foreseen, which constitutes a novel development in high-rate particle physics experiments. Gas Electron Multiplier (GEM) foils offer an intrinsic ion back-flow suppression combined with high gains, and will therefore be used for gas amplification. A small-size GEM-TPC test chamber has been constructed during this thesis and commissioned using both X-rays and muons from cosmic-ray air-showers. From the latter data, a spatial resolution down to 140 {mu}m has been achieved. The detector has been operated stably for many months with Ar/CO{sub 2} (70/30) and at typical gas amplification factors of (5-10).10{sup 3}. (orig.)

  8. Multispectral angular domain optical tomography in scattering media with argon and diode laser sources

    Science.gov (United States)

    Chan, Paulman K. Y.; Vasefi, Fartash; Chapman, Glenn H.; Kaminska, Bozena; Pfeiffer, Nick

    2007-02-01

    Angular Domain Imaging (ADI) within highly scattering media employs micromachined angular filter tunnels to detect nonscattered photons which pass through the tunnels unattenuated while scattered photons collide with the tunnel walls. Each tunnel is micromachined approximately 51 μm wide by 10 mm long in silicon, giving a maximum acceptance angle of 0.29 degrees. The ADI technique is inherently independent of wavelength, and thus multispectral laser sources can be incorporated. Previous ADI experiments employed a 488-514 nm Argon ion laser source. This paper describes the construction of a new imaging system utilizing a high-power (up to 0.5 W) laser diode at the 670 nm wavelength, along with an aspheric and cylindrical lens system for shaping the beam into a collimated line of light. ADI results of biological samples (i.e. chicken breast tissue) are also presented. Image resolution is 204 μm or better in compressed chicken breast tissue approximately 3.8 mm in thickness. Digital image processing techniques are employed to improve image contrast, definition, and detectability of test structures. Because silicon is 40% reflective, scattered light at up to three times the acceptance angle is not sufficiently absorbed by the angular filter tunnels and contributes significant background noise, thus decreasing image contrast and detectability. Roughening of the tunnel surface using a NH4OH etchant solution scatters light hitting the walls, thus allowing it to be absorbed. Images after roughening show dramatic reductions in background scattered light levels between tunnels, suggesting that further experiments will make progress towards improved contrast and detectability of structures.

  9. Non-destructive determination of total polyphenols content and classification of storage periods of Iron Buddha tea using multispectral imaging system.

    Science.gov (United States)

    Xiong, Chuanwu; Liu, Changhong; Pan, Wenjuan; Ma, Fei; Xiong, Can; Qi, Li; Chen, Feng; Lu, Xuzhong; Yang, Jianbo; Zheng, Lei

    2015-06-01

    Total polyphenols is a primary quality indicator in tea which is consumed worldwide. The feasibility of using near infrared reflectance (NIR) spectroscopy (800-2500nm) and multispectral imaging (MSI) system (405-970nm) for prediction of total polyphenols contents (TPC) of Iron Buddha tea was investigated in this study. The results revealed that the predictive model by MSI using partial least squares (PLS) analysis for tea leaves was considered to be the best in non-destructive and rapid determination of TPC. Besides, the ability of MSI to classify tea leaves based on storage period (year of 2004, 2007, 2011, 2012 and 2013) was tested and the classification accuracies of 95.0% and 97.5% were achieved using LS-SVM and BPNN models, respectively. These overall results suggested that MSI together with suitable analysis model is a promising technology for rapid and non-destructive determination of TPC and classification of storage periods in tea leaves. PMID:25624215

  10. Comparative effects of argon green and krypton red laser photocoagulation for patients with diabetic exudative maculopathy.

    OpenAIRE

    Khairallah, M; Brahim, R; Allagui, M.; Chachia, N

    1996-01-01

    AIMS/BACKGROUND: Focal treatment of diabetic macular oedema is usually done using a haemoglobin absorbing wave-length, such as argon green laser. This study aimed to compare photocoagulation with argon green (514 nm) and krypton red (647 nm), which is poorly absorbed by haemoglobin, in the focal treatment of patients with diabetic exudative maculopathy. METHODS: A total of 151 eyes of 78 outpatients were assigned randomly to receive either argon green (n = 79) or krypton red (n = 72) laser tr...

  11. Emission properties of an atmospheric pressure argon plasma jet excited by barrier discharge

    International Nuclear Information System (INIS)

    An atmospheric-pressure argon plasma jet is initiated by the barrier discharge in a capillary, through which argon was flown. The spectral composition of radiation emitted by the jet in the atmosphere and its variation in the space are analyzed in detail. The jet radiation spectrum is shown to be predominantly formed by spectral transitions of argon and oxygen atoms, by electron-vibrational transitions of the first positive system of nitrogen molecules N2, and by transitions of hydroxyl radical OH

  12. The effects of argon in the bioenergetics of the hamster and the rat

    Science.gov (United States)

    Tempel, G. E.; Musacchia, X. J.

    1974-01-01

    Oxygen consumption was examined in hamsters and rats exposed to normoxic mixtures of argon at 1 atm. In fasted and nonfasted animals, no marked change in O2 utilization was detectable at 22 C. However, at 7 C a significant decrease in oxygen consumption was observed where the animals were exposed in argon. The data are interpreted in terms of the greater thermal conductivity of nitrogen. The study was prompted by conflicting reports on the metabolic effects of argon and helium.

  13. Argon Laser Photoablation for Treating Benign Pigmented Conjunctival Nevi

    Science.gov (United States)

    Alsharif, Abdulrahman M.; Al-Gehedan, Saeed M.; Alasbali, Tariq; Alkuraya, Hisham S.; Lotfy, Nancy M.; Khandekar, Rajiv

    2016-01-01

    Purpose: To evaluate the outcomes of argon laser photoablation of benign conjunctival pigmented nevi with different clinical presentations. Patients and Methods: This interventional case series was conducted between July 2014 and January 2015. Patients presenting with benign conjunctival nevi were included. Data were collected on the clinical features at presentation, argon laser photoablation, and follow-up at 8 and 24 weeks. Postoperative photography allowed recording of the success of each case and the overall success rate. Complete removal of conjunctival pigments was considered an absolute success. Partial pigmentation requiring repeat laser treatment was considered a qualified success. Results: There were 14 eyes (four right eyes and ten left eyes) with benign pigmented conjunctival nevi. There were three males and eight females in the study sample. The median age was 36 (25% percentile: 26 years). Three patients had bilateral lesions. The nevi were located temporally in nine eyes, nasally in three eyes, and on the inferior bulbar conjunctiva in two eyes. The mean horizontal and vertical diameters of nevi were 5 ± 2 mm and 4 ± 2.7 mm, respectively. The mean follow-up period was 5 months. Following laser treatment, no eyes had subconjunctival hemorrhage, infection, scarring, neovascularization, recurrence, or corneal damage. The absolute success rate of laser ablation was 79%. Three eyes with elevated nevi had one to three sessions of laser ablation resulting in a qualified success rate of 100%. Conclusions: Argon laser ablation was a safe and effective treatment for the treatment of selective benign pigmented conjunctival nevi in Arab patients. PMID:27555708

  14. Foam injection moulding of a TPO/TPC-blend and the effect of different nucleating agents on the resulting foam structure

    Science.gov (United States)

    Mueller, J.; Spoerrer, A.; Altstaedt, V.

    2014-05-01

    The manufacturing of car interior parts with a soft touch surface is possible in a one-step injection moulding process, in which an injection moulded carrier is overmoulded with a compatible foamed thermoplastic elastomer (TPE). In contrast to the complex conventional process the structural foaming of the TPE component allows a saving of one material component as it combines a compact skin and a foamed core. Furthermore the manufacturing process can be achieved on a two component injection moulding machine which offers a much higher economic efficiency. One approach to reach an adhesion between a reinforced PP carrier and the foamed TPE component including good surface resistance is the use of an olefinic-/polyester-based TPE blend (TPO/TPC-blend). This paper is going to show the possibility to process a TPO/TPC-blend system by foam injection moulding with MuCell® and how the resulting foam structure can be influenced by various nucleating agents. For this purpose particles which differ in type, form and size were added in various concentrations to the TPE-blend. Before the structure elucidation of the foamed samples the particle dispersion and their effects on the polymers rheological properties were investigated. Finally abrasion tests were performed to investigate the influence of the particles on the performance characteristics of the foamed blend system. The results showed that the foam structure as well as the surface quality of the foamed TPO/TPC-blend can be improved with the use of suitable nucleating agents. Furthermore the abrasion properties can be advanced with appropriate additives in the right dosage.

  15. Sodium aerosol formation in an argon flow over hot sodium

    International Nuclear Information System (INIS)

    Vapour evaporation, which partly forms aerosol, occurs when a cold gas flows over a hot liquid. A previous well-mixed model is extended to predict the final vapour plus aerosol content of such a flow in terms of its initial and final temperatures. The predictions are compared to results of the Copacabana II experiment in which argon passed over a sodium pool. Agreement is obtained for the final sodium density at moderate flow rates, and physical reasons are given as to why deviations occur at low and high flow rates. (author)

  16. Performance of the TGT liquid argon calorimeter and trigger system

    International Nuclear Information System (INIS)

    A novel concept of a liquid argon calorimeter, the 'Thin Gap Turbine' (TGT) calorimeter, is presented. A TGT test module, equipped with specially developed cold front-end electronics in radiation hard GaAs technology, has been operated in a particle beam. Results on its performance are given. A 40 MHz FADC system with a 'circular data store' and standalone readout and playback capability has been developed to test the properties of the TGT detector for trigger purposes. Results on trigger efficiency, response and energy resolution are given. 12 refs., 21 figs., 6 tabs

  17. Optical fiber read-out for liquid argon scintillation light

    CERN Document Server

    Csáthy, J Janicskó; Kratz, J; Schönert, S; Wiesinger, Ch

    2016-01-01

    In this paper we describe the performance of a light detector for Ar scintillation light made of wavelength-shifting (WLS) fibers connected to Silicon-Photomultipliers (SiPM). The setup was conceived to be used as anti-Compton veto for high purity germanium (HPGe) detectors operated directly in liquid Argon (LAr). Background suppression efficiencies for different radioactive sources were measured in a test cryostat with about 800 kg LAr. This work was part of the R\\&D effort for the GERDA experiment.

  18. HARP: high-pressure argon readout for calorimeters

    International Nuclear Information System (INIS)

    Steel tubes of approximately 8 mm O.D., filled with Argon gas to approx. 200 bar, are considered as the active element for a charge collecting sampling calorimeter readout system. The tubes are permanently sealed and operated in the ion chamber mode, with the charge collection on a one-millimeter concentric anode. We present the motivation for such a device, including Monte Carlo predictions of performance. The method of construction and signal collection are discussed, with initial results on leakage and ageing of the filling gas. A prototype electromagnetic calorimeter is described

  19. Modeling of an argon cascaded arc plasma by ANSYS FLUENT

    International Nuclear Information System (INIS)

    In this work, an argon cascaded arc plasma is simulated by the business software ANSYS FLUENT. In fact, thus plasma is a high temperature arc (plasma window) with an average temperature of 12000 °C, which can be used as a medium between high pressure and vacuum mainly due to its characteristics of high temperature. According to the simulating results, the temperature can reach as high as 11500 °C which is in great agreement with that of other reports about plasma window.

  20. Diffusion coefficient of metal vapours into rare gases. Mercury - argon

    International Nuclear Information System (INIS)

    The source information is present as well as the results of analysis and integration of data on mutual diffusion coefficient (MDC) of mercury - argon mixture at Hg concentration → 0 in 300-2500 K temperature range. Reference data on MDC for metal - inert gas binary mixtures obtained on the base of complex analysis of various information, as it exemplified by Hg-Ar pair, can be used as a part of metrological support at calibration of devices for determination MDC of gas - metal vapors