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Sample records for atmospheric cherenkov effect

  1. Effect of stars in the field of view of the VHE gamma-ray atmospheric Cherenkov telescope

    Badran, H.M.

    2004-01-01

    Very high energy gamma-ray astronomy in the energy range above 100 GeV has made dramatic progress through the development of imaging atmospheric Cherenkov telescopes (lACTs). The technique has been pivotal in the establishing the existence of a number of discrete gamma-ray sources. Normally due to the presence of stars in the field of view (FOV), a number of photomultiplier tubes (pmts) in the camera has to be turned off. This may have the effect of distorting some images that happens to be in that part of the camera. This may in turn affect the gamma-ray sensitivity of the telescope. The present study aims to shade some light on this possible effect. Experimental data on the extragalactic gamma-ray source Mrk 421 measured using the 10-m Whipple IACT were used for this purpose because of its relative dark FOV compared with other sources; e.g. the Crab nebula. To simulate the presence of star(s) in the FOV, the analysis program selects randomly a number of clusters of pmts to be turned off in the software. The pmts in each cluster have to be adjacent to each other (neighbors) and the selected clusters have to be separated from each other. The significance of the detected signal and the gamma-ray rate were then determined and compared with the original results. Clusters of 2, 3 and 4 pmts were used. The number of clusters was increased up to 12 clusters at various distances from the center of the FOV

  2. Looking inside volcanoes with the Imaging Atmospheric Cherenkov Telescopes

    Del Santo, M.; Catalano, O.; Cusumano, G.; La Parola, V.; La Rosa, G.; Maccarone, M. C.; Mineo, T.; Sottile, G.; Carbone, D.; Zuccarello, L.; Pareschi, G.; Vercellone, S.

    2017-12-01

    Cherenkov light is emitted when charged particles travel through a dielectric medium with velocity higher than the speed of light in the medium. The ground-based Imaging Atmospheric Cherenkov Telescopes (IACT), dedicated to the very-high energy γ-ray Astrophysics, are based on the detection of the Cherenkov light produced by relativistic charged particles in a shower induced by TeV photons interacting with the Earth atmosphere. Usually, an IACT consists of a large segmented mirror which reflects the Cherenkov light onto an array of sensors, placed at the focal plane, equipped by fast electronics. Cherenkov light from muons is imaged by an IACT as a ring, when muon hits the mirror, or as an arc when the impact point is outside the mirror. The Cherenkov ring pattern contains information necessary to assess both direction and energy of the incident muon. Taking advantage of the muon detection capability of IACTs, we present a new application of the Cherenkov technique that can be used to perform the muon radiography of volcanoes. The quantitative understanding of the inner structure of a volcano is a key-point to monitor the stages of the volcano activity, to forecast the next eruptive style and, eventually, to mitigate volcanic hazards. Muon radiography shares the same principle as X-ray radiography: muons are attenuated by higher density regions inside the target so that, by measuring the differential attenuation of the muon flux along different directions, it is possible to determine the density distribution of the interior of a volcano. To date, muon imaging of volcanic structures has been mainly achieved with detectors made up of scintillator planes. The advantage of using Cherenkov telescopes is that they are negligibly affected by background noise and allow a consistently improved spatial resolution when compared to the majority of the current detectors.

  3. CELESTE: an atmospheric Cherenkov telescope for high energy gamma astrophysics

    Paré, E.; Balauge, B.; Bazer-Bachi, R.; Bergeret, H.; Berny, F.; Briand, N.; Bruel, P.; Cerutti, M.; Collon, J.; Cordier, A.; Cornbise, P.; Debiais, G.; Dezalay, J. P.; Dumora, D.; Durand, E.; Eschstruth, P.; Espigat, P.; Fabre, B.; Fleury, P.; Gilly, J.; Gouillaud, J. C.; Gregory, C.; Hérault, N.; Holder, J.; Hrabovský, Miroslav; Incerti, S.; Jouenne, A.; Kalt, L.; LeGallou, R.; Lott, B.; Manigot, P.; Neveu, J.; Olive, J. F.; Palatka, Miroslav; Perez, A.; Rebii, A.; Rob, L.; Sans, J. L.; Schovánek, Petr; Villard, G.

    2002-01-01

    Roč. 490, - (2002), s. 71-89 ISSN 0168-9002 R&D Projects: GA MŠk LN00A006 Institutional research plan: CEZ:AV0Z1010920 Keywords : gamma-ray astronopy * atmospheric Cherenkov detector Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 1.167, year: 2002

  4. The Atmospheric Monitoring Strategy for the Cherenkov Telescope Array

    Daniel, M. K.; CTA Consortium

    2015-04-01

    The Imaging Atmospheric Cherenkov Technique (IACT) is unusual in astronomy as the atmosphere actually forms an intrinsic part of the detector system, with telescopes indirectly detecting very high energy particles by the generation and transport of Cherenkov photons deep within the atmosphere. This means that accurate measurement, characterisation and monitoring of the atmosphere is at the very heart of successfully operating an IACT system. The Cherenkov Telescope Array (CTA) will be the next generation IACT observatory with an ambitious aim to improve the sensitivity of an order of magnitude over current facilities, along with corresponding improvements in angular and energy resolution and extended energy coverage, through an array of Large (23 m), Medium (12 m) and Small (4 m) sized telescopes spread over an area of order ~km2. Whole sky coverage will be achieved by operating at two sites: one in the northern hemisphere and one in the southern hemisphere. This proceedings will cover the characterisation of the candidate sites and the atmospheric calibration strategy. CTA will utilise a suite of instrumentation and analysis techniques for atmospheric modelling and monitoring regarding pointing forecasts, intelligent pointing selection for the observatory operations and for offline data correction.

  5. The TACTIC atmospheric Cherenkov imaging telescope

    Koul, R.; Tickoo, A.K.; Kaul, S.K.; Kaul, S.R.; Kumar, N.; Yadav, K.K.; Bhatt, N.; Venugopal, K.; Goyal, H.C.; Kothari, M.; Chandra, P.; Rannot, R.C.; Dhar, V.K.; Koul, M.K.; Kaul, R.K.; Kotwal, S.; Chanchalani, K.; Thoudam, S.; Chouhan, N.; Sharma, M.; Bhattacharyya, S.; Sahayanathan, S.

    2007-01-01

    The TACTIC (TeV Atomospheric Cherenkov Telescope with Imaging Camera) γ-ray telescope, equipped with a light collector of area ∼9.5m 2 and a medium resolution imaging camera of 349 pixels, has been in operation at Mt. Abu, India, since 2001. This paper describes the main features of its various subsystems and its overall performance with regard to (a) tracking accuracy of its two-axes drive system, (b) spot size of the light collector, (c) back-end signal processing electronics and topological trigger generation scheme, (d) data acquisition and control system and (e) relative and absolute gain calibration methodology. Using a trigger field-of-view of 11x11 pixels (∼3.4 a tx3.4 a t), the telescope records a cosmic ray event rate of ∼2.5Hz at a typical zenith angle of 15 a t. Monte Carlo simulation results are also presented in the paper for comparing the expected performance of the telescope with actual observational results. The consistent detection of a steady signal from the Crab Nebula above ∼1.2TeV energy, at a sensitivity level of ∼5.0σ in ∼25h, along with excellent matching of its energy spectrum with that obtained by other groups, reassures that the performance of the TACTIC telescope is quite stable and reliable. Furthermore, encouraged by the detection of strong γ-ray signals from Mrk 501 (during 1997 and 2006 observations) and Mrk 421 (during 2001 and 2005-2006 observations), we believe that there is considerable scope for the TACTIC telescope to monitor similar TeV γ-ray emission activity from other active galactic nuclei on a long-term basis

  6. Wavelet imaging cleaning method for atmospheric Cherenkov telescopes

    Lessard, R. W.; Cayón, L.; Sembroski, G. H.; Gaidos, J. A.

    2002-07-01

    We present a new method of image cleaning for imaging atmospheric Cherenkov telescopes. The method is based on the utilization of wavelets to identify noise pixels in images of gamma-ray and hadronic induced air showers. This method selects more signal pixels with Cherenkov photons than traditional image processing techniques. In addition, the method is equally efficient at rejecting pixels with noise alone. The inclusion of more signal pixels in an image of an air shower allows for a more accurate reconstruction, especially at lower gamma-ray energies that produce low levels of light. We present the results of Monte Carlo simulations of gamma-ray and hadronic air showers which show improved angular resolution using this cleaning procedure. Data from the Whipple Observatory's 10-m telescope are utilized to show the efficacy of the method for extracting a gamma-ray signal from the background of hadronic generated images.

  7. CELESTE an atmospheric Cherenkov telescope for high energy gamma astrophysics

    Paré, E; Bazer-Bachi, R; Bergeret, H; Berny, F; Briand, N; Bruel, P; Cerutti, M; Collon, J; Cordier, A; Cornebise, P; Debiais, G; Dezalay, J P; Dumora, D; Durand, E; Eschstruth, P T; Espigat, P; Fabre, B; Fleury, P; Gilly, J; Gouillaud, J C; Gregory, C; Herault, N; Holder, J; Hrabovsky, M; Incerti, S; Jouenne, A; Kalt, L; Legallou, R; Lott, B; Lodygensky, O; Manigot, P; Manseri, H; Manitaz, H; Martin, M; Morano, R; Morineaud, G; Muenz, F; Musquere, A; Naurois, M D; Neveu, J; Noppe, J M; Olive, J F; Palatka, M; Pérez, A; Quebert, J; Rebii, A; Reposeur, T; Rob, L; Roy, P; Sans, J L; Sako, T; Schovanek, P; Smith, D A; Snabre, P; Villard, G

    2002-01-01

    CELESTE is an atmospheric Cherenkov telescope based on the sampling method which makes use of the de-commissioned THEMIS solar electrical plant in the French Pyrenees. A large (2000 m sup 2) mirror surface area from 40 independent heliostats followed by a secondary optic, a trigger system using analog summing techniques and signal digitization with 1 GHz flash ADCs make possible the detection of cosmic gamma-rays down to 30 GeV. This paper provides a detailed technical description of the CELESTE installation.

  8. Gamma ray astronomy with atmospheric Cherenkov telescopes: the future

    Krennrich, Frank

    2009-01-01

    Atmospheric Cherenkov telescopes have been key to the recent discoveries in teraelectronvolt (TeV) γ-ray astronomy. The detection of TeV γ rays from more than 90 galactic and extragalactic sources provides a wealth of data for probing physical phenomena that pertain to some of the big questions in astrophysics. These include the understanding of the origin of cosmic rays, unveiling the connection between relativistic jets and black holes, shedding light on dark matter and its relation to supersymmetric particles and estimating the brightness of cosmological diffuse radiation fields in the optical/infrared waveband. While these recent advances were made with instruments designed in the 1990s, the present paper is concerned with a next generation of imaging atmospheric Cherenkov telescopes (IACTs) that are currently in the conceptual planning stage. We discuss the basic ideas, the required technology and expected performance of a ≥1 square-kilometer array, which is poised to yield the most dramatic step yet to come in TeV astronomy.

  9. Pattern recognition trigger electronics for an imaging atmospheric Cherenkov telescope

    Bradbury, S.M.; Rose, H.J.

    2002-01-01

    For imaging atmospheric Cherenkov telescopes, which aim to detect electromagnetic air showers with cameras consisting of several hundred photomultiplier pixels, the single pixel trigger rate is dominated by fluctuations in night sky brightness and by ion feedback in the photomultipliers. Pattern recognition trigger electronics may be used to reject night sky background images, thus reducing the data rate to a manageable level. The trigger system described here detects patterns of 2, 3 or 4 adjacent pixel signals within a 331 pixel camera and gives a positive trigger decision in 65 ns. The candidate pixel pattern is compared with the contents of a pre-programmed memory. With the trigger decision timing controlled by a fixed delay the time-jitter inherent in the use of programmable gate arrays is avoided. This system is now in routine operation at the Whipple 10 m Telescope

  10. On the kinematics of the two-photon Cherenkov effect

    Afanas'ev, G.N.; Stepanovskij, Yu.P.

    2003-01-01

    We study the kinematics of the two-photon Cherenkov effect. In the general case, the emission angles of two photons satisfy certain inequalities and the corresponding radiation intensities are rather diffused. In special cases, when the above inequalities reduce to equalities, the emission angles of two photons are fixed and the corresponding radiation intensities should have sharp maxima at these angles. This makes easier the experimental study of the two-photon Cherenkov effect

  11. Towards a network of atmospheric Cherenkov detectors 7

    Robin, M.; Weekes, T.C.; Mori, M.; Mariotti, M.; Hofmann, W.; Aharonian, F.; Sinitsyna, V.; Smith, D.; Marleau, P.; Sinnis, G.; Volk, H.; Jager, O. de; Harding, A.; Coppi, P.; Dermer, C.; Goldwurm, A.; Paul, J.; Puhlhofer, G.; Bernardini, E.; Swordy, S.; Yoshikoshi, T.; Punch, M.

    2005-01-01

    This document gathers the papers and transparencies presented at the conference. The main part of the conference was organized into 6 sessions: 1) the review of present experiments (Veritas, Cangaroo-3, Magic, Hess-1, Shalon, Cactus, Cygnus-X-3...), 2) calibration and analysis techniques in VHE (very high energy) astrophysics, 3) multi-wavelength observations and phenomenology of sources, 4) the future of ground-based VHE astronomy, 5) developments in instrumentation for Cherenkov telescopes, and 6) the evolution of the field and its link with mainstream astrophysics

  12. Towards a network of atmospheric Cherenkov detectors 7

    Robin, M. [Ecole Polytechnique, 91 - Palaiseau (France); Weekes, T.C. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Mori, M. [Tokyo Univ., Institute for Cosmic Ray Research (Japan); Mariotti, M. [Padova Univ., INFN (Italy); Hofmann, W.; Aharonian, F. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Sinitsyna, V. [P.N. Lebedev Physical Institute, Moscow (Russian Federation); Smith, D. [Centre d' Etudes Nucleaires de Bordeaux Gradignan, 33 - Gradignan (France); Marleau, P. [California Univ., Davis, CA (United States); Sinnis, G. [Los Alamos National Lab., NM (United States); Volk, H. [Max-Planck-Institut fur Kernphysik (Germany); Jager, O. de [South Africa Univ., North-West (South Africa); Harding, A. [NASA Goddard Space Flight Center (United States); Coppi, P. [Yale Univ., New Haven, CT (United States); Dermer, C. [Naval Research Laboratory (United States); Goldwurm, A.; Paul, J. [CEA Saclay, Dept. d' Astrophysique, de Physique des Particules de Physique Nucleaire et de l' Instrumentation Associee, 91- Gif sur Yvette (France); Puhlhofer, G. [Landessternwarte Heidelberg (Germany); Bernardini, E. [DESy-Zeuthen (Germany); Swordy, S. [Chicago Univ., IL (United States); Yoshikoshi, T. [Tokyo Univ., Tanashi (Japan). Inst. for Cosmic Ray Research; Teshima, M. [Max-Planck-Institute for Physics, Munich (Germany); Punch, M. [Astrophysique et Cosmologie (APC), College de France, 75 - Paris (France)

    2005-07-01

    This document gathers the papers and transparencies presented at the conference. The main part of the conference was organized into 6 sessions: 1) the review of present experiments (Veritas, Cangaroo-3, Magic, Hess-1, Shalon, Cactus, Cygnus-X-3...), 2) calibration and analysis techniques in VHE (very high energy) astrophysics, 3) multi-wavelength observations and phenomenology of sources, 4) the future of ground-based VHE astronomy, 5) developments in instrumentation for Cherenkov telescopes, and 6) the evolution of the field and its link with mainstream astrophysics.

  13. A G-APD based Camera for Imaging Atmospheric Cherenkov Telescopes

    Anderhub, H.; Backes, M.; Biland, A.; Boller, A.; Braun, I.; Bretz, T.; Commichau, S.; Commichau, V.; Dorner, D.; Gendotti, A.; Grimm, O.; Gunten, H. von; Hildebrand, D.; Horisberger, U.; Koehne, J.-H.; Kraehenbuehl, T.; Kranich, D.; Lorenz, E.; Lustermann, W.; Mannheim, K.

    2011-01-01

    Imaging Atmospheric Cherenkov Telescopes (IACT) for Gamma-ray astronomy are presently using photomultiplier tubes as photo sensors. Geiger-mode avalanche photodiodes (G-APD) promise an improvement in sensitivity and, important for this application, ease of construction, operation and ruggedness. G-APDs have proven many of their features in the laboratory, but a qualified assessment of their performance in an IACT camera is best undertaken with a prototype. This paper describes the design and construction of a full-scale camera based on G-APDs realized within the FACT project (First G-APD Cherenkov Telescope).

  14. Cherenkov detectors and a new effective-mass spectrometer method

    Hladký, Jan

    2006-01-01

    Roč. 75, - (2006), s. 854-855 ISSN 0969-806X Institutional research plan: CEZ:AV0Z10100502 Keywords : Cherenkov radiation * spectrometer * effective mass method Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 0.868, year: 2006

  15. The use of an ultra-violet camera in the atmospheric Cherenkov technique

    Urban, M.; Fleury, P.; Kerrick, A.D.; Pare, E.; Vacanti, G.

    1996-01-01

    The atmospheric Cherenkov technique for gamma ray astronomy is shown to be feasible using an ultraviolet (UV) camera on moon-lit-nights. The Whipple telescope has been used as the reflector and the CRab Nebula as the standard gamma ray beam. Our energy threshold is 1.2 TeV which is compared to 0.4 TeV in the visible. (orig.)

  16. Detection of ultraviolet Cherenkov light from high energy cosmic ray atmospheric showers: A field test

    Bartoli, B.; Peruzzo, L.; Sartori, G.; Bedeschi, F.; Bertolucci, E.; Mariotti, M.; Menzione, A.; Ristori, L.; Stefanini, A.; Zetti, F.; Scribano, A.; Budinich, M.; Liello, F.

    1991-01-01

    We present the results of a test with a prototype apparatus aimed to detect the ultraviolet Cherenkov light in the wavelenght range 2000-2300A, emitted by high energy cosmic ray showers. The system consists of a gas proportional chamber, with TMAE vapour as the photosensitive element, placed on the focal plane of a 1.5 m diameter parabolic mirror. The test was done during the summer of 1989 with cosmic ray showers seen in coincidence with the EAS-TOP experiment, an extended atmospheric shower charged particle array now being exploited at Campo Imperatore, 1900 m above sea level, on top of the Gran Sasso underground Laboratory of INFN. The results were positive and show that a full scale ultraviolet Cherenkov experiment with good sensitivity, angular resolution and virtually no background from moonlight or even daylight can be envisaged. (orig.)

  17. Large-area atmospheric Cherenkov detectors for high-energy gamma-ray astronomy

    Ong, R.A.

    1996-01-01

    This paper describes the development of new ground-based gamma-ray detectors to explore the energy region between 20 and 200 GeV. This region in energy is interesting because it is currently unexplored by any experiment. The proposed detectors use the atmospheric Cherenkov technique, in which Cherenkov radiation produced in the gamma-ray air showers is detected using mirrors and light-sensitive devices. The important feature of the proposed experiments is the use of large mirror collection areas, which should allow for a significant improvement (i.e. reduction) in energy threshold over existing experiments. Large mirror areas are available for relatively low cost at central tower solar power plants, and there are two groups developing gamma-ray experiments using solar heliostat arrays. This paper summarizes the progress in the design of experiments using this novel approach

  18. Studies on a silicon-photomultiplier-based camera for Imaging Atmospheric Cherenkov Telescopes

    Arcaro, C.; Corti, D.; De Angelis, A.; Doro, M.; Manea, C.; Mariotti, M.; Rando, R.; Reichardt, I.; Tescaro, D.

    2017-12-01

    Imaging Atmospheric Cherenkov Telescopes (IACTs) represent a class of instruments which are dedicated to the ground-based observation of cosmic VHE gamma ray emission based on the detection of the Cherenkov radiation produced in the interaction of gamma rays with the Earth atmosphere. One of the key elements of such instruments is a pixelized focal-plane camera consisting of photodetectors. To date, photomultiplier tubes (PMTs) have been the common choice given their high photon detection efficiency (PDE) and fast time response. Recently, silicon photomultipliers (SiPMs) are emerging as an alternative. This rapidly evolving technology has strong potential to become superior to that based on PMTs in terms of PDE, which would further improve the sensitivity of IACTs, and see a price reduction per square millimeter of detector area. We are working to develop a SiPM-based module for the focal-plane cameras of the MAGIC telescopes to probe this technology for IACTs with large focal plane cameras of an area of few square meters. We will describe the solutions we are exploring in order to balance a competitive performance with a minimal impact on the overall MAGIC camera design using ray tracing simulations. We further present a comparative study of the overall light throughput based on Monte Carlo simulations and considering the properties of the major hardware elements of an IACT.

  19. Front-end electronics and data acquisition system for imaging atmospheric Cherenkov telescopes

    Chen, Y.T.; La Taille, C. de; Suomijärvi, T.; Cao, Z.; Deligny, O.; Dulucq, F.; Ge, M.M.; Lhenry-Yvon, I.; Martin-Chassard, G.; Nguyen Trung, T.; Wanlin, E.; Xiao, G.; Yin, L.Q.; Yun Ky, B.; Zhang, L.; Zhang, H.Y.; Zhang, S.S.; Zhu, Z.

    2015-01-01

    In this paper, a front-end electronics based on an application-specific integrated circuit (ASIC) is presented for the future imaging atmospheric Cherenkov telescopes (IACTs). To achieve this purpose, a 16-channel ASIC chip, PARISROC 2 (Photomultiplier ARray Integrated in SiGe ReadOut Chip) is used in the analog signal processing and digitization. The digitized results are sent to the server by a user-defined User Datagram Protocol/Internet Protocol (UDP/IP) hardcore engine through Ethernet that is managed by a FPGA. A prototype electronics fulfilling the requirements of the Wide Field of View Cherenkov Telescope Array (WFCTA) of the Large High Altitude Air Shower Observatory (LHAASO) project has been designed, fabricated and tested to prove the concept of the design. A detailed description of the development with the results of the test measurements are presented. By using a new input structure and a new configuration of the ASIC, the dynamic range of the circuit is extended. A highly precise-time calibrating algorithm is also proposed, verified and optimized for the mass production. The test results suggest that the proposed electronics design fulfills the general specification of the future IACTs

  20. Front-end electronics and data acquisition system for imaging atmospheric Cherenkov telescopes

    Chen, Y.T., E-mail: chenytao@ynu.edu.cn [Institut de Physique Nucléaire, IN2P3-CNRS, Université Paris-Sud, 91406 Orsay Cedex (France); Yunnan University, 650091 Kunming (China); La Taille, C. de [OMEGA (UMS 3605) - IN2P3/CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Suomijärvi, T. [Institut de Physique Nucléaire, IN2P3-CNRS, Université Paris-Sud, 91406 Orsay Cedex (France); Cao, Z. [Institute of High Energy Physics, 100049 Beijing (China); Deligny, O. [Institut de Physique Nucléaire, IN2P3-CNRS, Université Paris-Sud, 91406 Orsay Cedex (France); Dulucq, F. [OMEGA (UMS 3605) - IN2P3/CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Ge, M.M. [Yunnan University, 650091 Kunming (China); Lhenry-Yvon, I. [Institut de Physique Nucléaire, IN2P3-CNRS, Université Paris-Sud, 91406 Orsay Cedex (France); Martin-Chassard, G. [OMEGA (UMS 3605) - IN2P3/CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Nguyen Trung, T.; Wanlin, E. [Institut de Physique Nucléaire, IN2P3-CNRS, Université Paris-Sud, 91406 Orsay Cedex (France); Xiao, G.; Yin, L.Q. [Institute of High Energy Physics, 100049 Beijing (China); Yun Ky, B. [Institut de Physique Nucléaire, IN2P3-CNRS, Université Paris-Sud, 91406 Orsay Cedex (France); Zhang, L. [Yunnan University, 650091 Kunming (China); Zhang, H.Y. [Tsinghua University, 100084 Beijing (China); Zhang, S.S.; Zhu, Z. [Institute of High Energy Physics, 100049 Beijing (China)

    2015-09-21

    In this paper, a front-end electronics based on an application-specific integrated circuit (ASIC) is presented for the future imaging atmospheric Cherenkov telescopes (IACTs). To achieve this purpose, a 16-channel ASIC chip, PARISROC 2 (Photomultiplier ARray Integrated in SiGe ReadOut Chip) is used in the analog signal processing and digitization. The digitized results are sent to the server by a user-defined User Datagram Protocol/Internet Protocol (UDP/IP) hardcore engine through Ethernet that is managed by a FPGA. A prototype electronics fulfilling the requirements of the Wide Field of View Cherenkov Telescope Array (WFCTA) of the Large High Altitude Air Shower Observatory (LHAASO) project has been designed, fabricated and tested to prove the concept of the design. A detailed description of the development with the results of the test measurements are presented. By using a new input structure and a new configuration of the ASIC, the dynamic range of the circuit is extended. A highly precise-time calibrating algorithm is also proposed, verified and optimized for the mass production. The test results suggest that the proposed electronics design fulfills the general specification of the future IACTs.

  1. Gamma/hadron segregation for a ground based imaging atmospheric Cherenkov telescope using machine learning methods: Random Forest leads

    Sharma Mradul; Koul Maharaj Krishna; Mitra Abhas; Nayak Jitadeepa; Bose Smarajit

    2014-01-01

    A detailed case study of γ-hadron segregation for a ground based atmospheric Cherenkov telescope is presented. We have evaluated and compared various supervised machine learning methods such as the Random Forest method, Artificial Neural Network, Linear Discriminant method, Naive Bayes Classifiers, Support Vector Machines as well as the conventional dynamic supercut method by simulating triggering events with the Monte Carlo method and applied the results to a Cherenkov telescope. It is demonstrated that the Random Forest method is the most sensitive machine learning method for γ-hadron segregation. (research papers)

  2. Ionization and pulse lethargy effects in inverse Cherenkov accelerators

    Sprangle, P.; Hubbard, R.F.; Hafizi, B.

    1997-01-01

    Ionization processes limit the accelerating gradient and place an upper limit on the pulse duration of the electromagnetic driver in the inverse Cherenkov accelerator (ICA). Group velocity slippage, i.e., pulse lethargy, on the other hand, imposes a lower limit on the pulse duration. These limits are obtained for two ICA configurations in which the electromagnetic driver (e.g., laser or millimeter wave source) is propagated in a waveguide that is (i) lined with a dielectric material or (ii) filled with a neutral gas. In either configuration the electromagnetic driving field is guided and has an axial electric field with phase velocity equal to the speed of light in vacuum, c. The intensity of the driver in the ICA, and therefore the acceleration gradient, is limited by tunneling and collisional ionization effects. Partial ionization of the dielectric liner or gas can lead to significant modification of the dispersive properties of the waveguide, altering the phase velocity of the accelerating field and causing particle slippage, thus disrupting the acceleration process. An additional limitation on the pulse duration is imposed since the group velocity of the driving pulse is less than c and the pulse slips behind the accelerated electrons. Hence for sufficiently short pulses the electrons outrun the pulse, terminating the acceleration. Limitations on the driver pulse duration and accelerating gradient, due to ionization and pulse lethargy, are estimated for the two ICA configurations. Maximum accelerating gradients and pulse durations are presented for a 10 μm, 1 mm, and 1 cm wavelength electromagnetic driver. The combination of ionization and pulse lethargy effects impose severe limitations on the maximum energy gain in inverse Cherenkov accelerators. copyright 1997 The American Physical Society

  3. Cherenkov radiation

    Hubert, P.

    1955-01-01

    When the radioactivity has been discovered, it was observed by researchers that different materials as mineral salts or solutions were emitting a weak light when submitted to radioactivity beams. At the beginning it has been thought that it was fluorescent light. In 1934, Cherenkov, a russian physicist, worked on the luminescence of uranyl salts solutions caused by gamma radiation and observed a very weak light was emitted by pure liquid. After further studies, he concluded that this phenomena was different from fluorescence. Since then, it has been called Cherenkov effect. This blue light emission is produced when charged particles are going through a transparent medium with an upper velocity than light velocity. This can happen only in medium with large refractive index as water or glass. It also presents its different properties discovered afterwards. The different applications of the Cherenkov radiation are discussed as counting techniques for radiation detectors or comic ray detectors. (M.P.)

  4. The development of simulation and atmospheric shower reconstruction tools for the study of future Cherenkov Imaging telescopes

    Sajjad, S.

    2007-09-01

    The future of ground based gamma-ray astronomy lies in large arrays of Imaging Atmospheric Cherenkov Telescopes with better capabilities: lower energy threshold, higher sensitivity, better resolution and background rejection. The design of IACT systems and the optimisation of their parameters requires an understanding of the atmospheric showers as well as dedicated tools for the simulation of telescope systems and the evaluation of their performance. The first part of this dissertation deals with atmospheric showers, the various properties of the Cherenkov light they emit and their simulation. The second part presents the tools we have developed for the simulation of imaging atmospheric Cherenkov telescopes and the characteristics of the shower images obtained by them. The third part of this thesis contains a presentation of the tools developed for the reconstruction of the source position in the sky, core position on the ground and energy of the gamma-rays as well as ideas for gamma-hadron separation. In the end, we use these tools to study two large arrays of telescopes at two altitudes and evaluate their performance for gamma-ray detection. (author)

  5. Effect of wavelength shifters on water Cherenkov detectors

    Badino, G; Galeotti, P; Periale, L; Saavedra, O; Turtelli, A [Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica; Turin Univ. (Italy). Ist. di Fisica Generale)

    1981-06-15

    We report the results of a test showing that concentrations of approx. equal to 2 mg/l of wavelength shifter in water give almost the maximum efficiency of detection without losing the directionality of Cherenkov light.

  6. Studies of runaway electrons via Cherenkov effect in tokamaks

    Zebrowski, J.; Jakubowski, L.; Rabinski, M.; Sadowski, M. J.; Jakubowski, M. J.; Kwiatkowski, R.; Malinowski, K.; Mirowski, R.; Mlynar, J.; Ficker, O.; Weinzettl, V.; Causa, F.; COMPASS; FTU Teams

    2018-01-01

    The paper concerns measurements of runaway electrons (REs) which are generated during discharges in tokamaks. The control of REs is an important task in experimental studies within the ITER-physics program. The NCBJ team proposed to study REs by means of Cherenkov-type detectors several years ago. The Cherenkov radiation, induced by REs in appropriate radiators, makes it possible to identify fast electron beams and to determine their spatial- and temporal-characteristics. The results of recent experimental studies of REs, performed in two tokamaks - COMPASS in Prague and FTU in Frascati, are summarized and discussed in this paper. Examples of the electron-induced signals, as recorded at different experimental conditions and scenarios, are presented. Measurements performed with a three-channel Cherenkov-probe in COMPASS showed that the first fast electron peaks can be observed already during the current ramp-up phase. A strong dependence of RE-signals on the radial position of the Cherenkov probe was observed. The most distinct electron peaks were recorded during the plasma disruption. The Cherenkov signals confirmed the appearance of post-disruptive RE beams in circular-plasma discharges with massive Ar-puffing. During experiments at FTU a clear correlation between the Cherenkov detector signals and the rotation of magnetic islands was identified.

  7. A generalized ray-tracing procedure for an atmospheric Cherenkov imaging telescope and optical characteristics of the TACTIC light collector

    Tickoo, A.K.; Suthar, R.L.; Koul, R.; Sapru, M.L.; Kumar, N.; Kaul, C.L.; Yadav, K.K.; Thoudam, S.; Kaul, S.K.; Venugopal, K.; Kothari, M.; Goyal, H.C.; Chandra, P.; Dhar, V.K.; Rannot, R.C.; Koul, M.K.; Kaul, S.R.

    2005-01-01

    A generalized ray-tracing procedure has been developed, which facilitates the design of a multimirror-based light collector used in atmospheric Cherenkov telescopes. This procedure has been employed to study the optical characteristics of the 3.5 m diameter light collector of the TACTIC Imaging telescope. Comparison of the measured point-spread function of the light collector with the simulated performance of ideal Davies-Cotton and paraboloid designs has been made to determine an optimum arrangement of the 34 spherical mirror facets used in the telescope to obtain the best possible point-spread function. A description of the ray-tracing subroutine used for processing CORSIKA-generated Cherenkov data, required for carrying out Monte-Carlo simulation studies, is also discussed in the paper

  8. The cross-talk problem in SiPMs and their use as light sensors for imaging atmospheric Cherenkov telescopes

    Buzhan, P.; Dolgoshein, B.; Ilyin, A.; Kaplin, V.; Klemin, S.; Mirzoyan, R.; Popova, E.; Teshima, M.

    2009-01-01

    One of the major drawbacks of a SiPM is due to the so-called cross-talk effect. Often, one single photon in a chain reaction can generate more photons and thus can fire more than one micro-cell of a SiPM. This can be considered as a noise in the signal multiplication process and this degrades the signal/noise ratio. In self-trigger schemes this noise can be so high that it can make operating them difficult at low threshold settings. For the past few years, we have dwelt on this effect aiming to suppress it at the design stage. One can use (a) trenches around the micro-cells for suppressing the direct photon 'communication' channel and (b) the so-called double p-n junction for suppressing photon-induced charge 'communication' in neighbor pixels. The low cross-talk is mandatory, for example, for producing SiPM-based light sensor modules for the Imaging Atmospheric Cherenkov Technique projects for ground-based gamma-ray astrophysics. We produced and tested a few modules consisting of 4 SiPMs, each with a size of 5 mmx5 mm of custom production type. We report here on the main parameters of these units.

  9. The atmospheric Cherenkov technique in searches for exploding primordial black holes

    Danaher, S.; Fegan, D.J.; Porter, N.A.; Weekes, T.C.

    1981-01-01

    The Cherenkov technique has been used with a number of detectors, ranging from 1.5 m 2 mirrors to the Central Receiver Test Facility of 8400 m 2 . Limits have been set to the flux of primordial black holes for various models of the evaporation process. (author)

  10. Electronic equipment of Cherenkov counters for detection of extensive atmospheric showers; Ehlektronnaya apparatura cherenkovskikh detektorov dlya registratsii shiroki kh atmosfernykh livnej

    Klimov, A I; meleshko, L A; Pan` kov, A A

    1996-12-31

    Paper describes electronic system of designed to record extensive atmospheric showers based on application of Cherenkov counters. Modules of preamplifier and PM divider, amplifier-scanner of two channel unit of precise time correlation, 8-channel time coder with 0.5 ns channel width and 14-input master unit are developed to realize the suggested operating circuit. 2 refs.

  11. Cherenkov effect as a probe of photonic nanostructures

    Garcia de Abajo, F.J.; Pattantyus-Abraham, A.G.; Wolf, M.O.; Zabala, N.; Rivacoba, A.; Echenique, P.M.

    2003-01-01

    Electron energy-loss spectroscopy (EELS) is shown to be an excellent source of information both on photonic crystal bands and on radiation modes of complex nanostructures. Good agreement is reported between measurements and parameter-free calculations of EELS in porous alumina films, where Cherenkov radiation is scattered by the pores to yield a strong 8.3-eV (7-eV) feature for 120-keV (200-keV) electrons. The latter is related to the bands of two-dimensional photonic crystals formed by air cylinders in an alumina matrix with similar near-range ordering. Finally, the band structure is proved to be directly mapped by angle-resolved EELS

  12. 5@5 - A 5 GeV Energy Threshold Array of Imaging Atmospheric Cherenkov Telescopes at 5 km Altitude

    Aharonian, F. A.; Konopelko, A. K.; Voelk, H. J.; Quintana, H.

    2000-10-01

    We discuss the concept and the performance of 5@5 - a stereoscopic array of several large imaging atmospheric Cherenkov telescopes installed at a very high mountain elevation of about 5 km a.s.l. or more - for the study of the gamma-ray sky at energies from several GeV to 100 GeV. With its capability to detect the ``standard'' EGRET sources with spectra extending up to 10 GeV in exposure times from 1 to 103 seconds, such a detector may serve as an ideal "Gamma-Ray Timing Explorer" for the study of transient non-thermal phenomena like gamma-radiation from AGN jets, synchrotron flares of microquasars, the high energy (GeV) counterparts of Gamma Ray Bursts, etc. Such an instrument would also allow detailed studies of the spectral characteristics of persistent gamma-ray sources like pulsars, supernova remnants, plerions, radiogalaxies, etc, in the energy region between 10 GeV and 100 GeV, where the capabilities of both the current space-based and ground-based gamma-ray projects are quite limited. The existing technological achievements in the design and construction of multi (1000) pixel, high resolution imagers, as well as of large, 20 m diameter class multi-mirror dishes with rather modest optical requirements, would allow the construction of the "5@5" in a foreseeable future. The Llano de Chajnantor (or the neighboring Cerro Toco) in the Atacama desert of Northern Chile seems an ideal site for such a ``post - CANGAROO/H.E.S.S./MAGIC/VERITAS'' era ground-based gamma-ray detector. The large flat area of that site, which was recently chosen for the installation of one of the most powerful future astronomical instruments - the Atacama Large Millimeter Array (ALMA) - could accomodate also an additional Cherenkov telescope array which requires a relatively compact area with a radius of about 100 m.

  13. Effect of Vavilov–Cherenkov radiation cone transformation upon entry of a relativistic electron into a substance layer

    Kishchin, I. A.; Kubankin, A. S., E-mail: kubankin@bsu.edu.ru; Nikulicheva, T. B.; Al-Omari; Sotnikov, A. V.; Starovoitov, A. S. [Belgorod National Research University (Russian Federation)

    2016-12-15

    Transformation of the Vavilov–Cherenkov radiation cone under grazing interaction of a relativistic electron with a layer of substance is theoretically studied. It is shown that this effect can occur when the electron enters the substance layer.

  14. Interference effects on guided Cherenkov emission in silicon from perpendicular, oblique, and parallel boundaries

    Couillard, M.; Yurtsever, A.; Muller, D. A.

    2010-05-01

    Waveguide electromagnetic modes excited by swift electrons traversing Si slabs at normal and oblique incidence are analyzed using monochromated electron energy-loss spectroscopy and interpreted using a local dielectric theory that includes relativistic effects. At normal incidence, sharp spectral features in the visible/near-infrared optical domain are directly assigned to p -polarized modes. When the specimen is tilted, s -polarized modes, which are completely absent at normal incidence, become visible in the loss spectra. In the tilted configuration, the dispersion of p -polarized modes is also modified. For tilt angles higher than ˜50° , Cherenkov radiation, the phenomenon responsible for the excitation of waveguide modes, is expected to partially escape the silicon slab and the influence of this effect on experimental measurements is discussed. Finally, we find evidence for an interference effect at parallel Si/SiO2 interfaces, as well as a delocalized excitation of guided Cherenkov modes.

  15. Interference effects on guided Cherenkov emission in silicon from perpendicular, oblique, and parallel boundaries

    Couillard, M.; Yurtsever, A.; Muller, D. A.

    2010-01-01

    Waveguide electromagnetic modes excited by swift electrons traversing Si slabs at normal and oblique incidence are analyzed using monochromated electron energy-loss spectroscopy and interpreted using a local dielectric theory that includes relativistic effects. At normal incidence, sharp spectral features in the visible/near-infrared optical domain are directly assigned to p-polarized modes. When the specimen is tilted, s-polarized modes, which are completely absent at normal incidence, become visible in the loss spectra. In the tilted configuration, the dispersion of p-polarized modes is also modified. For tilt angles higher than ∼50 deg. Cherenkov radiation, the phenomenon responsible for the excitation of waveguide modes, is expected to partially escape the silicon slab and the influence of this effect on experimental measurements is discussed. Finally, we find evidence for an interference effect at parallel Si/SiO 2 interfaces, as well as a delocalized excitation of guided Cherenkov modes.

  16. Development of a diagnostic technique based on Cherenkov effect for measurements of fast electrons in fusion devices

    Plyusnin, V. V.; Duarte, P.; Fernandes, H.; Silva, C. [Association Euratom/IST, Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Jakubowski, L.; Zebrowski, J.; Malinowski, K.; Rabinski, M.; Sadowski, M. J. [National Centre for Nuclear Research (NCBJ), 7 Andrzeja Soltana Str., 05-400 Otwock (Poland)

    2012-08-15

    A diagnostic technique based on the Cherenkov effect is proposed for detection and characterization of fast (super-thermal and runaway) electrons in fusion devices. The detectors of Cherenkov radiation have been specially designed for measurements in the ISTTOK tokamak. Properties of several materials have been studied to determine the most appropriate one to be used as a radiator of Cherenkov emission in the detector. This technique has enabled the detection of energetic electrons (70 keV and higher) and the determination of their spatial and temporal variations in the ISTTOK discharges. Measurement of hard x-ray emission has also been carried out in experiments for validation of the measuring capabilities of the Cherenkov-type detector and a high correlation was found between the data of both diagnostics. A reasonable agreement was found between experimental data and the results of numerical modeling of the runaway electron generation in ISTTOK.

  17. Modeling the Effects of Mirror Misalignment in a Ring Imaging Cherenkov Detector

    Hitchcock, Tawanda; Harton, Austin; Garcia, Edmundo

    2012-03-01

    The Very High Momentum Particle Identification Detector (VHMPID) has been proposed for the ALICE experiment at the Large Hadron Collider (LHC). This detector upgrade is considered necessary to study jet-matter interaction at high energies. The VHMPID identifies charged hadrons in the 5 GeV/c to 25 GeV/c momentum range. The Cherenkov photons emitted in the VHMPID radiator are collected by spherical mirrors and focused onto a photo-detector plane forming a ring image. The radius of this ring is related to the Cherenkov angle, this information coupled with the particle momentum allows the particle identification. A major issue in the RICH detector is that environmental conditions can cause movements in mirror position. In addition, chromatic dispersion causes the refractive index to shift, altering the Cherenkov angle. We are modeling a twelve mirror RICH detector taking into account the effects of mirror misalignment and chromatic dispersion using a commercial optical software package. This will include quantifying the effects of both rotational and translational mirror misalignment for the initial assembly of the module and later on particle identification.

  18. Cherenkov radiation in vacuum. 1

    Kozik, B.

    1985-01-01

    After discussing some historical aspects of the Cherenkov effect from electrodynamic and quantum theoretical points of view a methodically clear and simple theory of the Cherenkov effect is presented in which an arbitrary shaped rigid charge distribution is considered and which is based only on essential knowledge of Fourier transformations and cylindric functions. The Cherenkov effect is derived as a consequence of the structure of the potentials and the influence of the geometric shape of the charge distribution on the spectral distribution of the radiation intensity is taken into account in a general form. The educational value of such a representation of the Cherenkov effect in textbooks is emphasized

  19. BGO as a hybrid scintillator / Cherenkov radiator for cost-effective time-of-flight PET

    Brunner, S. E.; Schaart, D. R.

    2017-06-01

    Due to detector developments in the last decade, the time-of-flight (TOF) method is now commonly used to improve the quality of positron emission tomography (PET) images. Clinical TOF-PET systems based on L(Y)SO:Ce crystals and silicon photomultipliers (SiPMs) with coincidence resolving times (CRT) between 325 ps and 400 ps FWHM have recently been developed. Before the introduction of L(Y)SO:Ce, BGO was used in many PET systems. In addition to a lower price, BGO offers a superior attenuation coefficient and a higher photoelectric fraction than L(Y)SO:Ce. However, BGO is generally considered an inferior TOF-PET scintillator. In recent years, TOF-PET detectors based on the Cherenkov effect have been proposed. However, the low Cherenkov photon yield in the order of  ˜10 photons per event complicates energy discrimination-a severe disadvantage in clinical PET. The optical characteristics of BGO, in particular its high transparency down to 310 nm and its high refractive index of  ˜2.15, are expected to make it a good Cherenkov radiator. Here, we study the feasibility of combining event timing based on Cherenkov emission with energy discrimination based on scintillation in BGO, as a potential approach towards a cost-effective TOF-PET detector. Rise time measurements were performed using a time-correlated single photon counting (TCSPC) setup implemented on a digital photon counter (DPC) array, revealing a prompt luminescent component likely to be due to Cherenkov emission. Coincidence timing measurements were performed using BGO crystals with a cross-section of 3 mm  ×  3 mm and five different lengths between 3 mm and 20 mm, coupled to DPC arrays. Non-Gaussian coincidence spectra with a FWHM of 200 ps were obtained with the 27 mm3 BGO cubes, while FWHM values as good as 330 ps were achieved with the 20 mm long crystals. The FWHM value was found to improve with decreasing temperature, while the FWTM value showed the opposite trend.

  20. BGO as a hybrid scintillator / Cherenkov radiator for cost-effective time-of-flight PET.

    Brunner, S E; Schaart, D R

    2017-06-07

    Due to detector developments in the last decade, the time-of-flight (TOF) method is now commonly used to improve the quality of positron emission tomography (PET) images. Clinical TOF-PET systems based on L(Y)SO:Ce crystals and silicon photomultipliers (SiPMs) with coincidence resolving times (CRT) between 325 ps and 400 ps FWHM have recently been developed. Before the introduction of L(Y)SO:Ce, BGO was used in many PET systems. In addition to a lower price, BGO offers a superior attenuation coefficient and a higher photoelectric fraction than L(Y)SO:Ce. However, BGO is generally considered an inferior TOF-PET scintillator. In recent years, TOF-PET detectors based on the Cherenkov effect have been proposed. However, the low Cherenkov photon yield in the order of  ∼10 photons per event complicates energy discrimination-a severe disadvantage in clinical PET. The optical characteristics of BGO, in particular its high transparency down to 310 nm and its high refractive index of  ∼2.15, are expected to make it a good Cherenkov radiator. Here, we study the feasibility of combining event timing based on Cherenkov emission with energy discrimination based on scintillation in BGO, as a potential approach towards a cost-effective TOF-PET detector. Rise time measurements were performed using a time-correlated single photon counting (TCSPC) setup implemented on a digital photon counter (DPC) array, revealing a prompt luminescent component likely to be due to Cherenkov emission. Coincidence timing measurements were performed using BGO crystals with a cross-section of 3 mm  ×  3 mm and five different lengths between 3 mm and 20 mm, coupled to DPC arrays. Non-Gaussian coincidence spectra with a FWHM of 200 ps were obtained with the 27 mm 3 BGO cubes, while FWHM values as good as 330 ps were achieved with the 20 mm long crystals. The FWHM value was found to improve with decreasing temperature, while the FWTM value showed the opposite

  1. Nonlineart theory of relativistic beam-plasma instabilities in the regime of the collective Cherenkov effect

    Bobylev, Yu. V. [L.N. Tolstoy Tula State Pedagogical University (Russian Federation); Kuzelev, M. V. [Moscow State University (Russian Federation); Rukhadze, A. A. [Russian Academy of Sciences, Prokhorov Institute of General Physics (Russian Federation)

    2008-02-15

    A general mathematical model is proposed that is based on the Vlasov kinetic equation with a self-consistent field and describes the nonlinear dynamics of the electromagnetic instabilities of a relativistic electron beam in a spatially bounded plasma. Two limiting cases are analyzed, namely, high-frequency (HF) and low-frequency (LF) instabilities of a relativistic electron beam, of which the LF instability is a qualitatively new phenomenon in comparison with the known Cherenkov resonance effects. For instabilities in the regime of the collective Cherenkov effect, the equations containing cubic nonlinearities and describing the nonlinear saturation of the instabilities of a relativistic beam in a plasma are derived by using the methods of expansion in small perturbations of the trajectories and momenta of the beam electrons. Analytic expressions for the amplitudes of the interacting beam and plasma waves are obtained. The analytical results are shown to agree well with the exact solutions obtained numerically from the basic general mathematical model of the instabilities in question. The general mathematical model is also used to discuss the effects associated with variation in the constant component of the electron current in a beam-plasma system.

  2. Cherenkov radiation effects on counting efficiency in extremely quenched liquid scintillation samples

    Grau Carles, A.; Grau Malonda, A.; Rodriguez Barquero, L.

    1993-01-01

    The CIEMAT/NIST tracer method has successfully standardized nuclides with diverse quench values and decay schemes in liquid scintillation counting. However, the counting efficiency is computed inaccurately for extremely quenched samples. This article shows that when samples are extremely quenched, the counting efficiency in high-energy beta-ray nuclides depends principally on the Cherenkov effect. A new technique is described for quench determination, which makes the measurement of counting efficiency possible when scintillation counting approaches zero. A new efficiency computation model for pure beta-ray nuclides is also described. The results of the model are tested experimentally for 89 Sr, 90 Y, 36 Cl and 204 Tl nuclides with independence of the quench level. (orig.)

  3. Study of the photon flux from the night sky at La Palma and Namibia, in the wavelength region relevant for imaging atmospheric Cherenkov telescopes

    Preuss, S.; Hermann, G.; Hofmann, W.; Kohnle, A.

    2002-01-01

    The level of the night-sky background light at La Palma and Namibia was determined, with emphasis on the wavelength region and solid angle coverage relevant for the operation of imaging atmospheric Cherenkov telescopes. The dependence of the night-sky background light both on celestial coordinates (alt,az) and on galactic coordinates (b,l) was measured, with an angular resolution of about 1 deg. Average light levels near the zenith are similar in both locations -2.2x10 12 -2.6x10 12 photons sr -1 s -1 m -2 for 300 nm<λ<650 nm. With increasing zenith angle the level of background light increases at La Palma, whereas a constant level is measured in Namibia. Near the center of the Milky Way, background light levels are increased by a factor up to 4 and more. Also the level of light backscattered from the ground has been studied

  4. Cherenkov and anomalous Doppler effects in the relaxation of an electron beam

    Muschietti, L.; Appert, K.; Vaclavik, J.

    1981-01-01

    The interplay between the Cherenkov and anomalous Doppler interactions in the relaxation of a warm electron beam is investigated by numerical means. The most important feature in the interplay is found to be a nonelastic isotropization. A simple semianalytical model which allows one to estimate various quantities relevant to the relaxation process is also presented

  5. The History of Ground-Based Very High Energy Gamma-Ray Astrophysics with the Atmospheric Air Cherenkov Telescope Technique

    Mirzoyan, Razmik

    2013-06-15

    In the recent two decades the ground-based technique of imaging atmosphericescopes has established itself as a powerful new discipline in science. As of today some ∼ 150 sources of gamma rays of very different types, of both galactic and extragalactic origin, have been discovered due to this technique. The study of these sources is providing clues to many basic questions in astrophysics, astro-particle physics, physics of cosmic rays and cosmology. The current generation of telescopes, despite the young age of the technique, offers a solid performance. The technique is still maturing, leading to the next generation large instrument known under the name Cherenkov Telescope Array. The latter's sensitivity will be an order of magnitude higher than that of the currently best instruments VERITAS, H.E.S.S. and MAGIC. This article is devoted to outlining the milestones in a long history that step-by-step have given shape to this technique and have brought about today's successful source marathon.

  6. Analysis of Cherenkov counter efficiencies for E691

    Cremaldi, L.; Elliott, J.; Gibney, M.; Nauenberg, U.

    1985-01-01

    A program is outlined which simulates Cherenkov counters. The program can compute the effect of the magnetic field on the efficiencies of Cherenkov counters. It also tells what cone to mirror distance gives the highest collection efficiency and at which target position should the laser be placed to represent the direction of the actual Cherenkov light the mirror sees

  7. Cherenkov radiation; La radiation Cerenkov

    Hubert, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1955-07-01

    When the radioactivity has been discovered, it was observed by researchers that different materials as mineral salts or solutions were emitting a weak light when submitted to radioactivity beams. At the beginning it has been thought that it was fluorescent light. In 1934, Cherenkov, a russian physicist, worked on the luminescence of uranyl salts solutions caused by gamma radiation and observed a very weak light was emitted by pure liquid. After further studies, he concluded that this phenomena was different from fluorescence. Since then, it has been called Cherenkov effect. This blue light emission is produced when charged particles are going through a transparent medium with an upper velocity than light velocity. This can happen only in medium with large refractive index as water or glass. It also presents its different properties discovered afterwards. The different applications of the Cherenkov radiation are discussed as counting techniques for radiation detectors or comic ray detectors. (M.P.)

  8. The Cherenkov Bremsstrahlung

    Strel'tsov, V.N.

    1995-01-01

    The vanishing of the 'retardation factor' leads to a significant growth of the intensity of the electromagnetic field 'velocity part' of the moving charge. The Cherenkov radiation is its physical consequence. The same reason also conditions the growth of another term: the 'acceleration part' of the field which gives rise to the 'Cherenkov Bremsstrahlung'. 4 refs

  9. Measurement of the Muon Atmospheric Production Depth with the Water Cherenkov Detectors of the Pierre Auger Observatory

    Molina Bueno, Laura [Univ. of Granada (Spain)

    2015-09-01

    Ultra-high-energy cosmic rays (UHECR) are particles of uncertain origin and composition, with energies above 1 EeV (1018 eV or 0.16 J). The measured flux of UHECR is a steeply decreasing function of energy. The largest and most sensitive apparatus built to date to record and study cosmic ray Extensive Air Showers (EAS) is the Pierre Auger Observatory. The Pierre Auger Observatory has produced the largest and finest amount of data ever collected for UHECR. A broad physics program is being carried out covering all relevant topics of the field. Among them, one of the most interesting is the problem related to the estimation of the mass composition of cosmic rays in this energy range. Currently the best measurements of mass are those obtained by studying the longitudinal development of the electromagnetic part of the EAS with the Fluorescence Detector. However, the collected statistics is small, specially at energies above several tens of EeV. Although less precise, the volume of data gathered with the Surface Detector is nearly a factor ten larger than the fluorescence data. So new ways to study composition with data collected at the ground are under investigation. The subject of this thesis follows one of those new lines of research. Using preferentially the time information associated with the muons that reach the ground, we try to build observables related to the composition of the primaries that initiated the EAS. A simple phenomenological model relates the arrival times with the depths in the atmosphere where muons are produced. The experimental confirmation that the distributions of muon production depths (MPD) correlate with the mass of the primary particle has opened the way to a variety of studies, of which this thesis is a continuation, with the aim of enlarging and improving its range of applicability. We revisit the phenomenological model which is at the root of the analysis and discuss a new way to improve some aspects of the model. We carry

  10. On Cherenkov light production by irradiated nuclear fuel rods

    Branger, E.; Grape, S.; Svärd, S. Jacobsson; Jansson, P.; Sundén, E. Andersson

    2017-01-01

    Safeguards verification of irradiated nuclear fuel assemblies in wet storage is frequently done by measuring the Cherenkov light in the surrounding water produced due to radioactive decays of fission products in the fuel. This paper accounts for the physical processes behind the Cherenkov light production caused by a single fuel rod in wet storage, and simulations are presented that investigate to what extent various properties of the rod affect the Cherenkov light production. The results show that the fuel properties have a noticeable effect on the Cherenkov light production, and thus that the prediction models for Cherenkov light production which are used in the safeguards verifications could potentially be improved by considering these properties. It is concluded that the dominating source of the Cherenkov light is gamma-ray interactions with electrons in the surrounding water. Electrons created from beta decay may also exit the fuel and produce Cherenkov light, and e.g. Y-90 was identified as a possible contributor to significant levels of the measurable Cherenkov light in long-cooled fuel. The results also show that the cylindrical, elongated fuel rod geometry results in a non-isotropic Cherenkov light production, and the light component parallel to the rod's axis exhibits a dependence on gamma-ray energy that differs from the total intensity, which is of importance since the typical safeguards measurement situation observes the vertical light component. It is also concluded that the radial distributions of the radiation sources in a fuel rod will affect the Cherenkov light production.

  11. Cherenkov water detector NEVOD

    Petrukhin, A. A.

    2015-05-01

    A unique multipurpose Cherenkov water detector, the NEVOD facility, uses quasispherical measuring modules to explore all the basic components of cosmic rays on Earth's surface, including neutrinos. Currently, the experimental complex includes the Cherenkov water detector, a calibration telescope system, and a coordinate detector. This paper traces the basic development stages of NEVOD, examines research directions, presents the results obtained, including the search for the solution to the 'muon puzzle', and discusses possible future development prospects.

  12. Rectenna related atmospheric effects

    Lee, J.

    1980-01-01

    Possible meteorological effects arising from the existence and operations of a solar power satellite (SPS) system rectenna are examined. Analysis and model simulations in some chosen site situations and meteorological conditions indicate that the meteorological effects of the construction and operation of a rectenna are small, particularly outside the boundary of the structure. From weather and climate points of view, installation of an SPS rectenna seems likely to have effects comparable with those due to other nonindustrial land use changes covering the same area. The absorption and scattering of microwave radiation in the troposphere would have negligible atmospheric effects.

  13. Asymmetric Cherenkov acoustic reverse in topological insulators

    Smirnov, Sergey

    2014-09-01

    A general phenomenon of the Cherenkov radiation known in optics or acoustics of conventional materials is a formation of a forward cone of, respectively, photons or phonons emitted by a particle accelerated above the speed of light or sound in those materials. Here we suggest three-dimensional topological insulators as a unique platform to fundamentally explore and practically exploit the acoustic aspect of the Cherenkov effect. We demonstrate that by applying an in-plane magnetic field to a surface of a three-dimensional topological insulator one may suppress the forward Cherenkov sound up to zero at a critical magnetic field. Above the critical field the Cherenkov sound acquires pure backward nature with the polar distribution differing from the forward one generated below the critical field. Potential applications of this asymmetric Cherenkov reverse are in the design of low energy electronic devices such as acoustic ratchets or, in general, in low power design of electronic circuits with a magnetic field control of the direction and magnitude of the Cherenkov dissipation.

  14. CHERENKOV RADIATION DETECTOR

    ES Obe

    1981-03-01

    Mar 1, 1981 ... to measure the Cherenkov angles for natural radioactivity from sources as. Cs137 ... at 435 Mev in their proton-proton ..... (ii) Use is made of Table 5A Jelley ..... charge and rest mass in units of electron rest mass is shown in the table ... Proton e+. 1836. 322. Neutron. 0. 1839. 325. Alpha e2+. 7344. 1600.

  15. Development of the optical system for the SST-1M telescope of the Cherenkov Telescope Array observatory

    Ostrowski, Michael; Błocki, J.; Bogacz, L.; Bulik, T.; Cadoux, F.; Christov, A.; Curyło, M.; della Volpe, D.; Dyrda, M.; Favre, Y.; Frankowski, A.; Grudnik, Ł.; Grudzińska, M.; Heller, M.; Idźkowski, B.; Jamrozy, M.; Janiak, M.; Kasperek, J.; Lalik, K.; Lyard, E.; Mach, E.; Mandat, D.; Marszałek, A.; Michałowski, J.; Moderski, R.; Montaruli, T.; Neronov, A.; Niemiec, J.; Paśko, P.; Pech, M.; Porcelli, A.; Prandini, E.; Pueschel, E.; Rajda, P.; Rameez, M.; Schioppa, E. jr; Schovanek, P.; Skowron, K.; Sliusar, V.; Sowiński, M.; Stawarz, Ł.; Stodulska, M.; Stodulski, M.; Toscano, S.; Troyano Pujadas, I.; Walter, R.; Wiȩcek, M.; Zagdański, A.; Ziȩtara, K.; Żychowski, P.; Barciński, T.; Karczewski, M.; Kukliński, J. Nicolau; Płatos, Ł.; Rataj, M.; Wawer, P.; Wawrzaszek, R.

    2016-01-01

    The prototype of a Davies-Cotton small size telescope (SST-1M) has been designed and developed by a consortium of Polish and Swiss institutions and proposed for the Cherenkov Telescope Array (CTA) observatory. The main purpose of the optical system is to focus the Cherenkov light emitted by extensive air showers in the atmosphere onto the focal plane detectors. The main component of the system is a dish consisting of 18 hexagonal mirrors with a total effective collection area of 6.47 m2 (including the shadowing and estimated mirror reflectivity). Such a solution was chosen taking into account the analysis of the Cherenkov light propagation and based on optical simulations. The proper curvature and stability of the dish is ensured by the mirror alignment system and the isostatic interface to the telescope structure. Here we present the design of the optical subsystem together with the performance measurements of its components.

  16. FACT. Bokeh alignment for Cherenkov telescopes

    Mueller, Sebastian Achim [ETH Zurich (Switzerland); Buss, Jens [TU Dortmund (Germany)

    2016-07-01

    Imaging Atmospheric Cherenkov Telescopes (IACTs) need fast and large imaging optics to map the faint Cherenkov light emitted in cosmic ray air showers onto their image sensors. Segmented reflectors are inexpensive, lightweight and offer good image quality. However, alignment of the mirror facets remains a challenge. A good alignment is crucial in IACT observations to separate gamma rays from hadronic cosmic rays. We present a simple, yet extendable method, to align segmented reflectors using their Bokeh. Bokeh alignment does not need a star or good weather nights but can be done anytime, even during the day. Bokeh alignment optimizes the facet orientations by comparing the segmented reflector's Bokeh to a predefined template. The Bokeh is observed using the out of focus image of a nearby point like light source in a distance of about ten times the focal lengths. We introduce Bokeh alignment on segmented reflectors and present its use on the First Geiger-mode Avalanche Cherenkov Telescope (FACT) on Canary Island La Palma, as well as on the Cherenkov Telescope Array (CTA) Medium Size Telescope (MST) prototype in Berlin Adlershof.

  17. Measurement of radionuclides in the environment via Cherenkov radiation

    Ross, H.H.

    1987-01-01

    The author has developed an alternate approach to the measurement of some beta-emitting nuclides that utilizes the luminescence generated by the Cherenkov process. The luminescence, now known as Cherenkov radiation, was shown to be generated when a charged particle passes through a transparent medium at a speed that exceeds the phase velocity of light in the same medium. Cherenkov emission is different from most other luminescence processes in that it is a purely physical phenomenon. One consequence of this is that Cherenkov systems are free of chemical quenching effects. Conventional methods of analysis for environmental levels of beta-emitting radionuclides are often tedious, time-consuming, and expensive. The Cherenkov method is fast, requires very little operator attention, and is much less expensive to perform

  18. Tunable femtosecond Cherenkov fiber laser

    Liu, Xiaomin; Svane, Ask Sebastian; Lægsgaard, Jesper

    2014-01-01

    We demonstrate electrically-tunable femtosecond Cherenkov fiber laser output at the visible range. Using an all-fiber, self-starting femtosecond Yb-doped fiber laser as the pump source and nonlinear photonic crystal fiber link as the wave-conversion medium, ultrafast, milliwatt-level, tunable...... and spectral isolated Cherenkov radiation at visible wavelengths are reported. Such a femtosecond Cherenkov laser source is promising for practical biophotonics applications....

  19. Sci-Thur AM: YIS – 04: Stopping power-to-Cherenkov power ratios and beam quality specification for clinical Cherenkov emission dosimetry of electrons: beam-specific effects and experimental validation

    Zlateva, Yana; Seuntjens, Jan; El Naqa, Issam

    2016-01-01

    Purpose: To advance towards clinical Cherenkov emission (CE)-based dosimetry by investigating beam-specific effects on Monte Carlo-calculated electron-beam stopping power-to-CE power ratios (SCRs), addressing electron beam quality specification in terms of CE, and validating simulations with measurements. Methods: The EGSnrc user code SPRRZnrc, used to calculate Spencer-Attix stopping-power ratios, was modified to instead calculate SCRs. SCRs were calculated for 6- to 22-MeV clinical electron beams from Varian TrueBeam, Clinac 21EX, and Clinac 2100C/D accelerators. Experiments were performed with a 20-MeV electron beam from a Varian TrueBeam accelerator, using a diffraction grating spectrometer with optical fiber input and a cooled back-illuminated CCD. A fluorophore was dissolved in the water to remove CE signal anisotropy. Results: It was found that angular spread of the incident beam has little effect on the SCR (≤ 0.3% at d max ), while both the electron spectrum and photon contamination increase the SCR at shallow depths and decrease it at large depths. A universal data fit of R 50 in terms of C 50 (50% CE depth) revealed a strong linear dependence (R 2 > 0.9999). The SCR was fit with a Burns-type equation (R 2 = 0.9974, NRMSD = 0.5%). Below-threshold incident radiation was found to have minimal effect on beam quality specification (< 0.1%). Experiments and simulations were in good agreement. Conclusions: Our findings confirm the feasibility of the proposed CE dosimetry method, contingent on computation of SCRs from additional accelerators and on further experimental validation. This work constitutes an important step towards clinical high-resolution out-of-beam CE dosimetry.

  20. Sci-Thur AM: YIS – 04: Stopping power-to-Cherenkov power ratios and beam quality specification for clinical Cherenkov emission dosimetry of electrons: beam-specific effects and experimental validation

    Zlateva, Yana; Seuntjens, Jan; El Naqa, Issam [McGill University, Cedars Cancer Centre, University of Michigan (United States)

    2016-08-15

    Purpose: To advance towards clinical Cherenkov emission (CE)-based dosimetry by investigating beam-specific effects on Monte Carlo-calculated electron-beam stopping power-to-CE power ratios (SCRs), addressing electron beam quality specification in terms of CE, and validating simulations with measurements. Methods: The EGSnrc user code SPRRZnrc, used to calculate Spencer-Attix stopping-power ratios, was modified to instead calculate SCRs. SCRs were calculated for 6- to 22-MeV clinical electron beams from Varian TrueBeam, Clinac 21EX, and Clinac 2100C/D accelerators. Experiments were performed with a 20-MeV electron beam from a Varian TrueBeam accelerator, using a diffraction grating spectrometer with optical fiber input and a cooled back-illuminated CCD. A fluorophore was dissolved in the water to remove CE signal anisotropy. Results: It was found that angular spread of the incident beam has little effect on the SCR (≤ 0.3% at d{sub max}), while both the electron spectrum and photon contamination increase the SCR at shallow depths and decrease it at large depths. A universal data fit of R{sub 50} in terms of C{sub 50} (50% CE depth) revealed a strong linear dependence (R{sup 2} > 0.9999). The SCR was fit with a Burns-type equation (R{sup 2} = 0.9974, NRMSD = 0.5%). Below-threshold incident radiation was found to have minimal effect on beam quality specification (< 0.1%). Experiments and simulations were in good agreement. Conclusions: Our findings confirm the feasibility of the proposed CE dosimetry method, contingent on computation of SCRs from additional accelerators and on further experimental validation. This work constitutes an important step towards clinical high-resolution out-of-beam CE dosimetry.

  1. Volcanoes muon imaging using Cherenkov telescopes

    Catalano, O.; Del Santo, M.; Mineo, T.; Cusumano, G.; Maccarone, M.C.; Pareschi, G.

    2016-01-01

    A detailed understanding of a volcano inner structure is one of the key-points for the volcanic hazards evaluation. To this aim, in the last decade, geophysical radiography techniques using cosmic muon particles have been proposed. By measuring the differential attenuation of the muon flux as a function of the amount of rock crossed along different directions, it is possible to determine the density distribution of the interior of a volcano. Up to now, a number of experiments have been based on the detection of the muon tracks crossing hodoscopes, made up of scintillators or nuclear emulsion planes. Using telescopes based on the atmospheric Cherenkov imaging technique, we propose a new approach to study the interior of volcanoes detecting of the Cherenkov light produced by relativistic cosmic-ray muons that survive after crossing the volcano. The Cherenkov light produced along the muon path is imaged as a typical annular pattern containing all the essential information to reconstruct particle direction and energy. Our new approach offers the advantage of a negligible background and an improved spatial resolution. To test the feasibility of our new method, we have carried out simulations with a toy-model based on the geometrical parameters of ASTRI SST-2M, i.e. the imaging atmospheric Cherenkov telescope currently under installation onto the Etna volcano. Comparing the results of our simulations with previous experiments based on particle detectors, we gain at least a factor of 10 in sensitivity. The result of this study shows that we resolve an empty cylinder with a radius of about 100 m located inside a volcano in less than 4 days, which implies a limit on the magma velocity of 5 m/h.

  2. Volcanoes muon imaging using Cherenkov telescopes

    Catalano, O. [INAF, Istituto di Astrofisica Spaziale e Fisica cosmica di Palermo, via U. La Malfa 153, I-90146 Palermo (Italy); Del Santo, M., E-mail: melania@ifc.inaf.it [INAF, Istituto di Astrofisica Spaziale e Fisica cosmica di Palermo, via U. La Malfa 153, I-90146 Palermo (Italy); Mineo, T.; Cusumano, G.; Maccarone, M.C. [INAF, Istituto di Astrofisica Spaziale e Fisica cosmica di Palermo, via U. La Malfa 153, I-90146 Palermo (Italy); Pareschi, G. [INAF Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807, Merate (Italy)

    2016-01-21

    A detailed understanding of a volcano inner structure is one of the key-points for the volcanic hazards evaluation. To this aim, in the last decade, geophysical radiography techniques using cosmic muon particles have been proposed. By measuring the differential attenuation of the muon flux as a function of the amount of rock crossed along different directions, it is possible to determine the density distribution of the interior of a volcano. Up to now, a number of experiments have been based on the detection of the muon tracks crossing hodoscopes, made up of scintillators or nuclear emulsion planes. Using telescopes based on the atmospheric Cherenkov imaging technique, we propose a new approach to study the interior of volcanoes detecting of the Cherenkov light produced by relativistic cosmic-ray muons that survive after crossing the volcano. The Cherenkov light produced along the muon path is imaged as a typical annular pattern containing all the essential information to reconstruct particle direction and energy. Our new approach offers the advantage of a negligible background and an improved spatial resolution. To test the feasibility of our new method, we have carried out simulations with a toy-model based on the geometrical parameters of ASTRI SST-2M, i.e. the imaging atmospheric Cherenkov telescope currently under installation onto the Etna volcano. Comparing the results of our simulations with previous experiments based on particle detectors, we gain at least a factor of 10 in sensitivity. The result of this study shows that we resolve an empty cylinder with a radius of about 100 m located inside a volcano in less than 4 days, which implies a limit on the magma velocity of 5 m/h.

  3. Quenching the scintillation in CF4 Cherenkov gas radiator

    Blake, T.; D'Ambrosio, C.; Easo, S.; Eisenhardt, S.; Fitzpatrick, C.; Forty, R.; Frei, C.; Gibson, V.; Gys, T.; Harnew, N.; Hunt, P.; Jones, C.R.; Lambert, R.W.; Matteuzzi, C.; Muheim, F.; Papanestis, A.; Perego, D.L.; Piedigrossi, D.; Plackett, R.; Powell, A.

    2015-01-01

    CF 4 is used as a Cherenkov gas radiator in one of the Ring Imaging Cherenkov detectors at the LHCb experiment at the CERN Large Hadron Collider. CF 4 is well known to have a high scintillation photon yield in the near and far VUV, UV and in the visible wavelength range. A large flux of scintillation photons in our photon detection acceptance between 200 and 800 nm could compromise the particle identification efficiency. We will show that this scintillation photon emission system can be effectively quenched, consistent with radiationless transitions, with no significant impact on the photons resulting from Cherenkov radiation

  4. The cosmic ray proton, helium and CNO fluxes in the 100 TeV energy region from TeV muons and EAS atmospheric Cherenkov light observations of MACRO and EAS-TOP

    Aglietta, M; Ambrosio, M; Antolini, R; Antonioli, P; Arneodo, F; Baldini, A; Barbarino, G C; Barish, B C; Battistoni, G; Becherini, Y; Bellotti, R; Bemporad, C; Bergamasco, L; Bernardini, P; Bertaina, M; Bilokon, H; Bower, C; Brigida, M; Bussino, S; Cafagna, F; Calicchio, M; Campana, D; Carboni, M; Caruso, R; Castagnoli, C; Castellina, A; Cecchini, S; Cei, F; Chiarella, V; Chiarusi, T; Chiavassa, A; Choudhary, B C; Cini, G; Coutu, S; Cozzi, M; De Cataldo, G; De Marzo, C; De Mitri, I; De Vincenzi, M; Dekhissi, H; Derkaoui, J; Di Credico, A; Di Sciascio, G; Erriquez, O; Favuzzi, C; Forti, C; Fulgione, W; Fusco, P; Galeotti, P; Ghia, P L; Giacomelli, G; Giannini, G; Giglietto, N; Giorgini, M; Grassi, M; Grillo, A; Guarino, F; Gustavino, C; Habig, A; Hanson, K; Heinz, R; Iacovacci, M; Iarocci, E; Katsavounidis, E; Katsavounidis, I; Kearns, E; Kim, H; Kyriazopoulou, S; Lamanna, E; Lane, C; Levin, D S; Lipari, P; Longley, N P; Longo, M J; Loparco, F; Maaroufi, F; Mancarella, G; Mandrioli, G; Mannocchi, G; Margiotta, A; Marini, A; Martello, D; Marzari-Chiesa, A; Mazziotta, M N; Michael, D G; Monacelli, P; Montaruli, T; Monteno, M; Morello, C; Mufson, S; Musser, J; Navarra, G; Nicolò, D; Nolty, R; Orth, C; Osteria, G; Palamara, O; Patera, V; Patrizii, L; Pazzi, R; Peck, C W; Perrone, L; Petrera, S; D'Ettorre-Piazzoli, B; Popa, V; Rainó, A; Reynoldson, J; Ronga, F; Saavedra, O; Satriano, C; Scapparone, E; Scholberg, K; Sciubba, A; Sioli, M; Sirri, G; Sitta, M; Spinelli, P; Spinetti, M; Spurio, M; Stamerra, A; Steinberg, R; Stone, J L; Sulak, L R; Surdo, A; Tarle, G; Togo, V; Trinchero, G C; Vakili, M; Valchierotti, S; Vallania, P; Vernetto, S; Vigorito, C; Walter, C W; Webb, R; 10.1016/j.astropartphys.2004.01.005

    2004-01-01

    The primary cosmic ray (CR) proton, helium and CNO fluxes in the energy range 80-300 TeV are studied at the National Gran Sasso Laboratories by means of EAS-TOP (Campo Imperatore, 2005 m a.s.l.) and MACRO (deep underground, 3100 m w.e., the surface energy threshold for a muon reaching the detector being E/sub mu //sup th/ approximately=1.3 TeV). The measurement is based on: (a) the selection of primaries based on their energy/nucleon (i.e., with energy/nucleon sufficient to produce a muon with energy larger than 1.3 TeV) and the reconstruction of the shower geometry by means of the muons recorded by MACRO in the deep underground laboratories; (b) the detection of the associated atmospheric Cherenkov light (C.l.) signals by means of the C.l. detector of EAS-TOP. The C.l. density at core distance r>100 m is directly related to the total primary energy E/sub 0/. Proton and helium ("p+He") and proton, helium and CNO ("p +He+CNO") primaries are thus selected at E/sub 0/ approximately=80 Te V, and at E/sub 0/ appro...

  5. Mirror position determination for the alignment of Cherenkov Telescopes

    Adam, J. [TU Dortmund, Experimental Physics 5 Otto-Hahn-Str. 4, 44221 Dortmund (Germany); Ahnen, M.L. [ETH Zurich, Institute for Particle Physics Otto-Stern-Weg 5, 8093 Zurich (Switzerland); Baack, D. [TU Dortmund, Experimental Physics 5 Otto-Hahn-Str. 4, 44221 Dortmund (Germany); Balbo, M. [University of Geneva, ISDC Data Center for Astrophysics Chemin Ecogia 16, 1290 Versoix (Switzerland); Bergmann, M. [Universität Würzburg, Institute for Theoretical Physics and Astrophysics Emil-Fischer-Str. 31, 97074 Würzburg (Germany); Biland, A. [ETH Zurich, Institute for Particle Physics Otto-Stern-Weg 5, 8093 Zurich (Switzerland); Blank, M. [Universität Würzburg, Institute for Theoretical Physics and Astrophysics Emil-Fischer-Str. 31, 97074 Würzburg (Germany); Bretz, T. [ETH Zurich, Institute for Particle Physics Otto-Stern-Weg 5, 8093 Zurich (Switzerland); RWTH Aachen (Germany); Bruegge, K.A.; Buss, J. [TU Dortmund, Experimental Physics 5 Otto-Hahn-Str. 4, 44221 Dortmund (Germany); Dmytriiev, A. [University of Geneva, ISDC Data Center for Astrophysics Chemin Ecogia 16, 1290 Versoix (Switzerland); Domke, M. [TU Dortmund, Experimental Physics 5 Otto-Hahn-Str. 4, 44221 Dortmund (Germany); Dorner, D. [Universität Würzburg, Institute for Theoretical Physics and Astrophysics Emil-Fischer-Str. 31, 97074 Würzburg (Germany); FAU Erlangen (Germany); Einecke, S. [TU Dortmund, Experimental Physics 5 Otto-Hahn-Str. 4, 44221 Dortmund (Germany); Hempfling, C. [Universität Würzburg, Institute for Theoretical Physics and Astrophysics Emil-Fischer-Str. 31, 97074 Würzburg (Germany); and others

    2017-07-11

    Imaging Atmospheric Cherenkov Telescopes (IACTs) need imaging optics with large apertures to map the faint Cherenkov light emitted in extensive air showers onto their image sensors. Segmented reflectors fulfill these needs using mass produced and light weight mirror facets. However, as the overall image is the sum of the individual mirror facet images, alignment is important. Here we present a method to determine the mirror facet positions on a segmented reflector in a very direct way. Our method reconstructs the mirror facet positions from photographs and a laser distance meter measurement which goes from the center of the image sensor plane to the center of each mirror facet. We use our method to both align the mirror facet positions and to feed the measured positions into our IACT simulation. We demonstrate our implementation on the 4 m First Geiger-mode Avalanche Cherenkov Telescope (FACT).

  6. Development of an underwater Cherenkov detector to reveal sources of technogenic radionuclides

    Chernyaev, A.M.; Gaponov, I.A.; Lapushkina, L.V.

    1999-01-01

    The major difference of the Cherenkov underwater detector from a scintillation detector is that its operation does not require a primary transducer (scintillator). Detected particle energy conversion into a light flash occurs directly in sea water (radiator) due to the Cherenkov effect. Consequently, photoreceiver of the underwater Cherenkov detector registers light from radiator of actually infinite volume. The circumstance is of principle importance, as it permits attaining the utmost sensitivity in case of the minimal overall dimensions and weight of detecting equipment

  7. Study of solar activity by measuring cosmic rays with a water Cherenkov detector

    Bahena Bias, Angelica; Villasenor, Luis

    2011-01-01

    We report on an indirect study of solar activity by using the Forbush effect which consists on the anti-correlation between the intensity of solar activity and the intensity of secondary cosmic radiation detected at ground level at the Earth. We have used a cylindrical water Cherenkov detector to measure the rate of arrival of secondary cosmic rays in Morelia Mich., Mexico, at 1950 m.a.s.l. We describe the analysis required to unfold the effect of atmospheric pressure and the search for Forbush decreases in our data, the latter correspond to more than one year of continuous data collection.

  8. Study of TeV range cosmic ray detection with Cherenkov imaging techniques

    Ansari, R.; Gaillard, J.M.; Parrour, G.

    1992-03-01

    The Monte Carlo study of cosmic ray detection in the TeV energy range has been triggered by the authors' interest in the ARTEMIS (Antimatter Research Through the Earth Moon Ion Spectrometer) proposal. The properties of cosmic ray showers detected by Cherenkov imaging in the visible domain are studied. The detection sensitivity and the accuracy of the reconstruction of the parent particle direction using Cherenkov imaging are discussed. The backbone of the study is the atmospheric shower Monte Carlo generator developed by A.M. Hillas. A comparison between nucleon and photon induced showers of Cherenkov detection is also included. (R.P.) 14 refs., 48 figs., 3 tabs

  9. Cherenkov light as a source of photochemical reactions in irradiated solutions of nitrile of malachite green

    Stuglik, Z; Grodkowski, J

    1986-10-01

    Experimental data on photochemical activity of Cherenkov light are presented. Malachite green leucocyanide was used to detect the photochemical effects. The G value of Cherenkov light from the region 200-330 nm (number of quanta formed per 100 eV absorbed energy of ionizing radiation) in ethanol was estimated to be in the range of 0.0027-0.049. 14 references.

  10. Cherenkov light as a source of photochemical reactions in irradiated solutions of nitrile of malachite green

    Stuglik, Z.; Grodkowski, J.

    1986-01-01

    Experimental data on photochemical activity of Cherenkov light are presented. Malachite green leucocyanide was used to detect the photochemical effects. The G value of Cherenkov light from the region 200-330 nm (number of quanta formed per 100 eV absorbed energy of ionizing radiation) in ethanol was estimated to be in the range of 0.0027-0.049. (author)

  11. Parametric Cherenkov radiation (development of idea)

    Buts, V.A.

    2004-01-01

    Some physical results of researches about charged particles radiation in mediums with a periodic heterogeneity and in periodic potential are reported. The development of ideas Parametric Cherenkov Radiation has shown, that in mediums, which have even a weak degree of a periodic heterogeneity of an permittivity or potential, the nonrelativistic oscillators can radiated as relativistic. They effectively radiate the high numbers of harmonics. In particular, in the carried out experiments the ultra-violet radiation was excited at action on a crystal of intensive ten-centimetric radiation. These results give the reasons to hope for making of nonrelativistic lasers on free electrons

  12. The performance of silicon photomultipliers in Cherenkov TOF PET

    Dolenec, Rok; Korpar, Samo; Krizan, Peter; Pestotink, Rok

    2015-01-01

    In time-of-flight positron emission tomography (TOF PET) one of the main factors limiting the time resolution is the time evolution of the scintillation process. This can be avoided by using exclusively the Cherenkov light produced in a suitable material. Sub 100 ps FWHM timing has already been experimentally demonstrated but with a drawback of relatively low detection efficiency due to the photodetectors used. In this work silicon photomultipliers (SiPMs) are considered as a photodetector in Cherenkov TOF PET. The detection efficiency can be significantly improved by using SiPMs, however, at room temperature the SiPM dark counts introduce a significant source of fake coincidences. SiPM samples from different producers were tested in a simple back-to-back setup in combination with lead fluoride Cherenkov radiators. Results for coincidence timing, detection efficiency and effects of dark counts at different temperatures and SiPM overvoltages are presented.

  13. The GCT camera for the Cherenkov Telescope Array

    Lapington, J. S.; Abchiche, A.; Allan, D.; Amans, J.-P.; Armstrong, T. P.; Balzer, A.; Berge, D.; Boisson, C.; Bousquet, J.-J.; Bose, R.; Brown, A. M.; Bryan, M.; Buchholtz, G.; Buckley, J.; Chadwick, P. M.; Costantini, H.; Cotter, G.; Daniel, M. K.; De Franco, A.; De Frondat, F.; Dournaux, J.-L.; Dumas, D.; Ernenwein, J.-P.; Fasola, G.; Funk, S.; Gironnet, J.; Graham, J. A.; Greenshaw, T.; Hervet, O.; Hidaka, N.; Hinton, J. A.; Huet, J.-M.; Jankowsky, D.; Jegouzo, I.; Jogler, T.; Kawashima, T.; Kraus, M.; Laporte, P.; Leach, S.; Lefaucheur, J.; Markoff, S.; Melse, T.; Minaya, I. A.; Mohrmann, L.; Molyneux, P.; Moore, P.; Nolan, S. J.; Okumura, A.; Osborne, J. P.; Parsons, R. D.; Rosen, S.; Ross, D.; Rowell, G.; Rulten, C. B.; Sato, Y.; Sayede, F.; Schmoll, J.; Schoorlemmer, H.; Servillat, M.; Sol, H.; Stamatescu, V.; Stephan, M.; Stuik, R.; Sykes, J.; Tajima, H.; Thornhill, J.; Tibaldo, L.; Trichard, C.; Varner, G.; Vink, J.; Watson, J. J.; White, R.; Yamane, N.; Zech, A.; Zink, A.; Zorn, J.; CTA Consortium

    2017-12-01

    The Gamma Cherenkov Telescope (GCT) is one of the designs proposed for the Small Sized Telescope (SST) section of the Cherenkov Telescope Array (CTA). The GCT uses dual-mirror optics, resulting in a compact telescope with good image quality and a large field of view with a smaller, more economical, camera than is achievable with conventional single mirror solutions. The photon counting GCT camera is designed to record the flashes of atmospheric Cherenkov light from gamma and cosmic ray initiated cascades, which last only a few tens of nanoseconds. The GCT optics require that the camera detectors follow a convex surface with a radius of curvature of 1 m and a diameter of 35 cm, which is approximated by tiling the focal plane with 32 modules. The first camera prototype is equipped with multi-anode photomultipliers, each comprising an 8×8 array of 6×6 mm2 pixels to provide the required angular scale, adding up to 2048 pixels in total. Detector signals are shaped, amplified and digitised by electronics based on custom ASICs that provide digitisation at 1 GSample/s. The camera is self-triggering, retaining images where the focal plane light distribution matches predefined spatial and temporal criteria. The electronics are housed in the liquid-cooled, sealed camera enclosure. LED flashers at the corners of the focal plane provide a calibration source via reflection from the secondary mirror. The first GCT camera prototype underwent preliminary laboratory tests last year. In November 2015, the camera was installed on a prototype GCT telescope (SST-GATE) in Paris and was used to successfully record the first Cherenkov light of any CTA prototype, and the first Cherenkov light seen with such a dual-mirror optical system. A second full-camera prototype based on Silicon Photomultipliers is under construction. Up to 35 GCTs are envisaged for CTA.

  14. Time and charge calibration of Cherenkov telescope data acquired by Domino Ring Sampler 4 chips

    Hoerbe, Mario; Doert, Marlene [Ruhr-Universitaet Bochum (Germany); Bruegge, Kai; Buss, Jens; Bockermann, Christian; Egorov, Alexej [TU Dortmund (Germany)

    2016-07-01

    Very-high-energy gamma-ray astronomy aims to give an insight into the most energetic phenomena in our Universe. Earthbound Cherenkov telescopes can measure Cherenkov light emitted by atmospheric particle showers which are produced by incoming cosmic particles at high energies. Current Cherenkov telescopes, e.g. operated in the FACT and the MAGIC experiments, utilize Domino Ring Sampler 4 (DRS4) chips for recording signals at high speed coming from the telescopes' cameras. DRS4 chips will also be used in the cameras of the Large-Size telescopes of the projected Cherenkov Telescope Array (CTA). We aim at developing a software solution for the calibration of DRS4 data based on the streams-framework, a software tool for streaming analysis which has been developed within the Collaborative Research Center SFB 876. The objectives and the current status of the project are presented.

  15. Progress in Cherenkov femtosecond fiber lasers

    Liu, Xiaomin; Svane, Ask Sebastian; Lægsgaard, Jesper

    2016-01-01

    systems are highlighted—dependent on the realization scheme, the Cherenkov lasers can generate the femtosecond output tunable across the entire visible and even the UV range, and for certain designs more than 40% conversion efficiency from the pump to Cherenkov signal can be achieved. The femtosecond......We review the recent developments in the field of ultrafast Cherenkov fiber lasers. Two essential properties of such laser systems—broad wavelength tunability and high efficiency of Cherenkov radiation wavelength conversion are discussed. The exceptional performance of the Cherenkov fiber laser...... Cherenkov laser with all-fiber architecture is presented and discussed. Operating in the visible range, it delivers 100–200 fs wavelength-tunable pulses with multimilliwatt output power and exceptionally low noise figure an order of magnitude lower than the traditional wavelength tunable supercontinuumbased...

  16. Lunar imaging and ionospheric calibration for the Lunar Cherenkov technique

    McFadden, R.; Scholten, O.; Mevius, M.

    2013-01-01

    The Lunar Cherenkov technique is a promising method for UHE neutrino and cosmic ray detection which aims to detect nanosecond radio pulses produced during particle interactions in the Lunar regolith. For low frequency experiments, such as NuMoon, the frequency dependent dispersive effect of the

  17. Calibration strategies for the Cherenkov Telescope Array

    Gaug, Markus; Berge, David; Daniel, Michael; Doro, Michele; Förster, Andreas; Hofmann, Werner; Maccarone, Maria C.; Parsons, Dan; de los Reyes Lopez, Raquel; van Eldik, Christopher

    2014-08-01

    The Central Calibration Facilities workpackage of the Cherenkov Telescope Array (CTA) observatory for very high energy gamma ray astronomy defines the overall calibration strategy of the array, develops dedicated hardware and software for the overall array calibration and coordinates the calibration efforts of the different telescopes. The latter include LED-based light pulsers, and various methods and instruments to achieve a calibration of the overall optical throughput. On the array level, methods for the inter-telescope calibration and the absolute calibration of the entire observatory are being developed. Additionally, the atmosphere above the telescopes, used as a calorimeter, will be monitored constantly with state-of-the-art instruments to obtain a full molecular and aerosol profile up to the stratosphere. The aim is to provide a maximal uncertainty of 10% on the reconstructed energy-scale, obtained through various independent methods. Different types of LIDAR in combination with all-sky-cameras will provide the observatory with an online, intelligent scheduling system, which, if the sky is partially covered by clouds, gives preference to sources observable under good atmospheric conditions. Wide-field optical telescopes and Raman Lidars will provide online information about the height-resolved atmospheric extinction, throughout the field-of-view of the cameras, allowing for the correction of the reconstructed energy of each gamma-ray event. The aim is to maximize the duty cycle of the observatory, in terms of usable data, while reducing the dead time introduced by calibration activities to an absolute minimum.

  18. FACT light collection - solid light concentrators in Cherenkov Astronomy

    Braun, Isabel [ETH Zurich, Institute for Particle Physics, CH-8093 Zurich (Switzerland); Collaboration: FACT-Collaboration

    2011-07-01

    Pixelized cameras of Imaging Atmospheric Cherenkov Telescopes use hollow light guides with reflective surfaces based on the Winston cone design. These cones minimize insensitive spaces between the photo sensors and shield the camera from stray background light by limiting the angular acceptance to the primary reflector area. FACT (First G-APD Cherenkov Telescope) will be the first IACT with Geiger-mode avalanche photodiodes as light sensors. Solid light concentrators complementing these sensors will be used instead of hollow Winston cones. We will present simulations and measurements of our light collector design, which was optimized for the requirements of the FACT telescope and detector, and discuss the specific differences to more traditional solutions.

  19. Generation and propagation of synchro - Cherenkov radiation

    Heintzmann, H.; Novello, M.; Schruefer, E.

    1981-01-01

    Particles moving along the magnetic field lines emit under favorable conditions Cherenkov radiation in a cold, rarefied plasma. A peculiar phenomenon occurs for curved magnetic fields: in for example a toroidal magnetic field the radiation spirals inward and approaches a resonance. Both the generation and the study of the propagation of these Cherenkov modes appear to be within reach of present technology. (Author) [pt

  20. Aerogel as Cherenkov radiator for RICH detectors

    Bellunato, T.; Braem, A.; Buzykaev, A.R.; Calvi, M.; Chesi, E.; Danilyuk, A.F.; Easo, S.; Hansen, C.; Jolly, S.; Joram, C.; Kravchenko, E.A.; Liko, D.; Matteuzzi, C.; Musy, M.; Negri, P.; Neufeld, N.; Onuchin, A.P.; Seguinot, J.; Weilhammer, P.; Wotton, S.

    2003-01-01

    We present here the results obtained using silica aerogel as Cherenkov radiator for the separation and identification of particles in the momentum range from 6 to 10 GeV/c. Photoelectron yield and Cherenkov ring resolution were studied under different experimental conditions and compared to the simulation

  1. All-fiber femtosecond Cherenkov radiation source

    Liu, Xiaomin; Lægsgaard, Jesper; Møller, Uffe

    2012-01-01

    -conversion medium, we demonstrate milliwatt-level, stable, and tunable Cherenkov radiation at visible wavelengths 580–630 nm, with pulse duration of sub-160-fs, and the 3 dB spectral bandwidth not exceeding 36 nm. Such an all-fiber Cherenkov radiation source is promising for practical applications in biophotonics...

  2. A large area plastic Cherenkov detector

    Bernabei, R.; Bidoli, V.; Zorzi, G. de; Biagio, A. di

    1978-01-01

    A large area Cherenkov counter has been built up using as a radiator a sheet of Pilot 425 plastic, (180x20)cm 2 x2.5 cm. Experimental tests performed with a pion beam in order to measure the average number of photoelectrons collected by photomultipliers and the scintillation to Cherenkov light ratio. (Auth.)

  3. Charged particle identification: Cherenkov counters at ISABELLE

    Etkin, A.; Kostoulas, I.; Leith, D.W.G.S.; Thun, R.

    1977-01-01

    A brief summary is given of a study of Cherenkov counters for ISABELLE. The study was certainy not exhaustive and was meant primarily to suggest future detector development. A substantial research effort is needed in order to insure that Cherenkov counters utilizing photoionization are fully exploited

  4. Technical Note: On maximizing Cherenkov emissions from medical linear accelerators.

    Shrock, Zachary; Yoon, Suk W; Gunasingha, Rathnayaka; Oldham, Mark; Adamson, Justus

    2018-04-19

    Cherenkov light during MV radiotherapy has recently found imaging and therapeutic applications but is challenged by relatively low fluence. Our purpose is to investigate the feasibility of increasing Cherenkov light production during MV radiotherapy by increasing photon energy and applying specialized beam-hardening filtration. GAMOS 5.0.0, a GEANT4-based framework for Monte Carlo simulations, was used to model standard clinical linear accelerator primary photon beams. The photon source was incident upon a 17.8 cm 3 cubic water phantom with a 94 cm source to surface distance. Dose and Cherenkov production was determined at depths of 3-9 cm. Filtration was simulated 15 cm below the photon beam source. Filter materials included aluminum, iron, and copper with thicknesses of 2-20 cm. Histories used depended on the level of attenuation from the filter, ranging from 100 million to 2 billion. Comparing average dose per history also allowed for evaluation of dose-rate reduction for different filters. Overall, increasing photon beam energy is more effective at improving Cherenkov production per unit dose than is filtration, with a standard 18 MV beam yielding 3.3-4.0× more photons than 6 MV. Introducing an aluminum filter into an unfiltered 2400 cGy/min 10 MV beam increases the Cherenkov production by 1.6-1.7×, while maintaining a clinical dose rate of 300 cGy/min, compared to increases of ~1.5× for iron and copper. Aluminum was also more effective than the standard flattening filter, with the increase over the unfiltered beam being 1.4-1.5× (maintaining 600 cGy/min dose rate) vs 1.3-1.4× for the standard flattening filter. Applying a 10 cm aluminum filter to a standard 18 MV, photon beam increased the Cherenkov production per unit dose to 3.9-4.3× beyond that of 6 MV (vs 3.3-4.0× for 18 MV with no aluminum filter). Through a combination of increasing photon energy and applying specialized beam-hardening filtration, the amount of Cherenkov photons per

  5. Quenching the scintillation in CF{sub 4} Cherenkov gas radiator

    Blake, T. [Department of Physics, University of Warwick, Coventry (United Kingdom); D' Ambrosio, C. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Easo, S. [STFC Rutherford Appleton Laboratory, Didcot (United Kingdom); European Organization for Nuclear Research (CERN), Geneva (Switzerland); Eisenhardt, S. [School of Physics and Astronomy, University of Edinburgh, Edinburgh (United Kingdom); Fitzpatrick, C. [Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne (Switzerland); Forty, R.; Frei, C. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Gibson, V. [Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom); Gys, T. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Harnew, N.; Hunt, P. [Department of Physics, University of Oxford, Oxford (United Kingdom); Jones, C.R. [Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom); Lambert, R.W. [Nikhef National Institute for Subatomic Physics and VU University Amsterdam, Amsterdam (Netherlands); Matteuzzi, C. [Sezione INFN di Milano Bicocca, Milano (Italy); Muheim, F. [School of Physics and Astronomy, University of Edinburgh, Edinburgh (United Kingdom); Papanestis, A., E-mail: antonis.papanestis@stfc.ac.uk [STFC Rutherford Appleton Laboratory, Didcot (United Kingdom); European Organization for Nuclear Research (CERN), Geneva (Switzerland); Perego, D.L. [Sezione INFN di Milano Bicocca, Milano (Italy); Università di Milano Bicocca, Milano (Italy); Piedigrossi, D. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Plackett, R. [Imperial College London, London (United Kingdom); Powell, A. [Department of Physics, University of Oxford, Oxford (United Kingdom); and others

    2015-08-11

    CF{sub 4} is used as a Cherenkov gas radiator in one of the Ring Imaging Cherenkov detectors at the LHCb experiment at the CERN Large Hadron Collider. CF{sub 4} is well known to have a high scintillation photon yield in the near and far VUV, UV and in the visible wavelength range. A large flux of scintillation photons in our photon detection acceptance between 200 and 800 nm could compromise the particle identification efficiency. We will show that this scintillation photon emission system can be effectively quenched, consistent with radiationless transitions, with no significant impact on the photons resulting from Cherenkov radiation.

  6. Influence of thermal fluctuations on Cherenkov radiation from fluxons in dissipative Josephson systems

    Antonov, A. A.; Pankratov, A. L.; Yulin, A. V.

    2000-01-01

    The nonlinear dynamics of fluxons in Josephson systems with dispersion and thermal fluctuations is analyzed using the "quasiparticle" approach to investigate the influence of noise on the Cherenkov radiation effect. Analytical expressions for the stationary amplitude of the emitted radiation...

  7. FACT. Normalized and asynchronous mirror alignment for Cherenkov telescopes

    Mueller, Sebastian Achim [ETH Zurich (Switzerland); Buss, Jens [TU Dortmund (Germany)

    2016-07-01

    Imaging Atmospheric Cherenkov Telescopes (IACTs) need fast and large imaging optics to map the faint Cherenkov light emitted in cosmic ray air showers onto their image sensors. Segmented reflectors are inexpensive, lightweight and offer good image quality. However, alignment of the mirror facets remains a challenge. A good alignment is crucial in IACT observations to separate gamma rays from hadronic cosmic rays. We present a star tracking alignment method which is not restricted to clear nights. It normalizes the mirror facet reflections to be independent of the reference star or the cloud coverage. It records asynchronously of the telescope drive which makes the method easy to integrate in existing telescopes. It can be combined with remote facet actuation, but it does not need one to work. Furthermore, it can reconstruct all individual mirror facet point spread functions. We present the method and alignment results on the First Geiger-mode Photo Diode Avalanche Cherenkov Telescope (FACT) on the Canary Island of La Palma, Spain.

  8. Effects of atmospheric pollutants on lipids

    Howton, D.R.

    1976-01-01

    Studies on effects of atmospheric pollutants on lipids emphasized effects of nitrogen dioxide on olefinic centers of alveolar fluid surfactant lipids. The finding that NO 2 attacks α-tocopherol much more avidly than olefinic fatty esters indicates that the autoxidation enhancing effects of this atmospheric pollutant may be greatly magnified by destruction of native antioxidants that normally suppress the extensiveness of such lipid oxidation

  9. Greenhouse effect due to atmospheric nitrous oxide

    Yung, Y. L.; Wang, W. C.; Lacis, A. A.

    1976-01-01

    The greenhouse effect due to nitrous oxide in the present atmosphere is about 0.8 K. Increase in atmospheric N2O due to perturbation of the nitrogen cycle by man may lead to an increase in surface temperature as large as 0.5 K by 2025, or 1.0 K by 2100. Other climatic effects of N2O are briefly discussed.

  10. Optical trigger: a Cherenkov effect discriminator for high energy physics. Realisation and characterisation of thin films whose refractive index allow discrimination over a wide spectral range

    Delbart, A.

    1996-01-01

    The first part of this thesis sets the physical principles, and properties of actual Optical Triggers. For each of them, the cupel is sapphire made, and the external medium is liquid because of refractive index. The theory of Cherenkov emitted light cone explain how sapphire birefringence affects discrimination conditions.The second parts of the thesis (the main one) is focussed on study and realization of thin films for Optical Trigger. A layer characterization method has been developed by spectrophotometry, based on Perkin-Elmer laboratory device. Computerized simulation helped us to determine characteristics and limits of the studied device. (D.L.)

  11. Performance of aerogel as Cherenkov radiator

    Bellunato, T.; Calvi, M.; Matteuzzi, C.; Musy, M.; Negri, P.; Braem, A.; Chesi, E.; Hansen, C.; Liko, D.; Joram, C.; Neufeld, N.; Seguinot, J.; Weilhammer, P.; Buzykaev, A.R.; Kravchenko, E.A.; Onuchin, A.P.; Danilyuk, A.F.; Easo, S.; Wotton, S.; Jolly, S.

    2004-01-01

    Aerogel with index of refraction around 1.03 has been studied as Cherenkov radiator in a test at CERN PS using a π - and a mixed π + /p beam of momenta between 6 and 10 GeV/c. The Cherenkov photons were detected by means of four large HPD tubes designed and constructed at CERN. Results on the photoelectron yield, the Cherenkov angle and its resolution, and the π/p separation are obtained. The performances measured demonstrate that a RICH with aerogel is a viable detector for experiments with high multiplicity of particles in the final state

  12. Research on mutual influence of Cherenkov-type probes within the ISTTOK tokamak chamber

    Jakubowski, L., E-mail: lech.jakubowski@ncbj.gov.pl [National Centre for Nuclear Research (NCBJ), 05-400 Otwock (Poland); Plyusnin, V.V. [Association Euratom/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Malinowski, K.; Sadowski, M.J.; Zebrowski, J.; Rabinski, M. [National Centre for Nuclear Research (NCBJ), 05-400 Otwock (Poland); Fernandes, H.; Silva, C.; Figueiredo, H. [Association Euratom/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Jakubowski, M.J. [National Centre for Nuclear Research (NCBJ), 05-400 Otwock (Poland)

    2014-12-11

    The paper describes an influence of a Cherenkov-type probe, which is used for measurements of fast electron streams inside the ISTTOK chamber, on other probes and behaviour of a plasma ring. The reported study shows that such a probe situated near the plasma column has a strong influence on signals from another Cherenkov probe, and can cause a considerable reduction of electron-induced signals. This effect does not depend on positions of the probes in relation to the limiter. Measurements of hard X-ray (HXR) emission show that the deeply immersed Cherenkov probe can also influence on the limiter . Under specific experimental conditions such a Cherenkov probe can play the role of a new limiter and change the plasma configuration.

  13. Ground-based gamma-ray astronomy with Cherenkov telescopes

    Hinton, Jim

    2009-01-01

    Very high-energy (>100 GeV) γ-ray astronomy is emerging as an important discipline in both high-energy astrophysics and astro-particle physics. This field is currently dominated by imaging atmospheric-Cherenkov telescopes (IACTs) and arrays of these telescopes. Such arrays have achieved the best angular resolution and energy flux sensitivity in the γ-ray domain and are still far from the fundamental limits of the technique. Here, I will summarize some key aspects of this technique and go on to review the current status of the major instruments and to highlight selected recent results.

  14. MEMPHYS: A large scale water Cherenkov detector at Frejus

    Bellefon, A. de; Dolbeau, J.; Gorodetzky, P.; Katsanevas, S.; Patzak, T.; Salin, P.; Tonazzo, A.; Bouchez, J.; Busto, J.; Campagne, J.E.; Cavata, C.; Mosca, L.; Dumarchez, J.; Mezzetto, M.; Volpe, C.

    2006-07-01

    A water Cherenkov detector project, of megaton scale, to be installed in the Frejus underground site and dedicated to nucleon decay, neutrinos from supernovae, solar and atmospheric neutrinos, as well as neutrinos from a super-beam and/or a beta-beam coming from CERN, is presented and compared with competitor projects in Japan and in the USA. The performances of the European project are discussed, including the possibility to measure the mixing angle θ 13 and the CP-violating phase δ. (authors)

  15. Feasibility of a next generation underground water Cherenkov detector: UNO

    Jung, Chang Kee

    2000-01-01

    The feasibility of a next generation underground water Cherenkov detector is examined and a conceptual design (UNO) is presented. The design has a linear detector configuration with a total volume of 650 kton which is 13 times the total volume of the Super-Kamiokande detector. It corresponds to a 20 times increase in fiducial volume for physics analysis. The physics goals of UNO are to increase the sensitivity of the search for nucleon decay by a factor of ten and to make precision measurements of the solar and atmospheric neutrino properties. In addition, the detection sensitivity for supernova neutrinos will reach as far as the Andromeda galaxy

  16. First studies of 500-nm Cherenkov radiation from 255-MeV electrons in a diamond crystal

    Takabayashi, Y., E-mail: takabayashi@saga-ls.jp [SAGA Light Source, 8-7 Yayoigaoka, Tosu, Saga 841-0005 (Japan); Fiks, E.I. [National Research Tomsk Polytechnic University, 634050 Tomsk (Russian Federation); Pivovarov, Yu.L. [National Research Tomsk Polytechnic University, 634050 Tomsk (Russian Federation); National Research Tomsk State University, 634050 Tomsk (Russian Federation)

    2015-06-12

    The first experiment on Cherenkov light from 255-MeV electrons passing through a 50-μm-thick diamond crystal in a special geometry allowing extraction of 500-nm Cherenkov light at a right angle with respect to the electron beam direction has been performed at the injector linac of SAGA Light Source accelerator facility. The dependence of 500-nm Cherenkov light intensity (separated by a band-pass filter) on the crystal rotation angle was measured by a CCD detector. The experimentally obtained rocking curve with an intense maximum is theoretically explained as the projector effect of Cherenkov light deflected by the exit surface of the crystal. The width of the rocking curve is explained by the convolution of the standard Tamm–Frank angular distribution of Cherenkov radiation with chromatic aberration, the multiple scattering of electrons in a crystal, and initial electron beam angular divergence. In addition, it is found that the Cherenkov light intensity did not change under the (220) planar channeling condition, which is consistent with a recent theory. - Highlights: • Cherenkov light from 255-MeV electrons in a diamond crystal has been investigated. • The Cherenkov light from channeled electrons has been observed for the first time. • The experimental results are in good agreement with theory.

  17. Cherenkov light based measurement of extensive air showers around the knee with the HEGRA experiment

    Aharonian, F.; Akhperjanian, A.G.; Barrio, J.A.; Belgarian, A.S.; Bernloehr, K.; Bojahr, H.; Contreras, J.L.; Cortina, J.; Daum, A.; Deckers, T.; Denninghoff, S.; Fernandez, J.; Fonseca, V.; Gonzales, J.C.; Heinzelmann, G.; Hemberger, M.; Hermann, G.; Hess, M.; Heusler, A.; Hofmann, W.; Hohl, H.; Horns, D.; Kankanyan, R.; Kestel, M.; Kirstein, O.; Koehler, C.; Konopelko, A.; Kornmayer, H.; Kranich, D.; Krawczynski, H.; Lampeitl, H.; Lindner, A.; Lorenz, E.; Magnussen, N.; Meyer, H.; Mirzoyan, R.; Moralejo, A.; Padilla, L.; Panter, M.; Petry, D.; Plaga, R.; Plyasheshnikov, A.; Prahl, J.; Prosch, C.; Puehlhofer, G.; Rauterberg, G.; Renault, C.; Rhode, W.; Roehring, A.; Sahakian, V.; Samorski, M.; Schmele, D.; Schroeder, F.; Stamm, W.; Voelk, H.J.; Wiebel-Sooth, B

    1999-03-01

    Data of the wide angle atmospheric Cherenkov light detector array AIROBICC and the scintillator matrix of the HEGRA air shower detector complex are combined to determine the energy spectrum and coarse composition of charged cosmic rays in the energy interval from 300 TeV to 10 PeV.

  18. The greenhouse effect of planetary atmospheres

    Kondratyev, K.Ya.; Moskalenko, N.I.

    1980-01-01

    The greenhouse effect of the atmosphere is the main factor of possible climate changes of anthropogenic origin. The growing pollution of the atmosphere leads to an increase of the concentration of various gaseous components. Of great importance is also the consideration of the aerosols. All the gaseous components, as well as aerosols, have the absorption bands in the IR spectral range. The traditional attention to the problem of the CO 2 contribution to the greenhouse effect has somewhat overshadowed the significance of the different components. The data characterizing the significance of the different components of the greenhouse effect are considered. The results of studying the absorption spectra of methane, nitrous oxides, sulphuric gas, ammonia, nitric-acid vapours and other components are discussed. The assessments of their contribution to the greenhouse effect are given. The important role of the small-size fraction of the atmospheric aerosols as a factor of the greenhouse effect is discussed. Both the analysis of the causes of the Earth's climate variability and the relevant investigation of the atmospheric greenhouse effect determine the expediency of analysing the conditions of the greenhouse effect formation on other planets. Laboratory studies of the IR absorption spectra of synthetic CO 2 atmospheres were carried out. Some results from these studies are discussed. (author)

  19. Large Water Cherenkov Detectors - Technical Issues -

    Aihara, H

    2010-01-01

    We address technical issues and challenges to construct a one-megaton scale water Cherenkov detector for neutrino detection. Studies presented here are mostly based on preliminary work for Hyper Kamiokande project.

  20. Reconstruction algorithms in the Super-Kamiokande large water Cherenkov detector

    Shiozawa, M.

    1999-01-01

    The Super-Kamiokande experiment, using a large underground water Cherenkov detector, has started its operation since first April, 1996. One of the main physics goals of this experiment is to measure the atmospheric neutrinos. Proton decay search is also an important topic. For these analyses, all measurement of physical quantities of an event such as vertex position, the number of Cherenkov rings, momentum, particle type and the number of decay electrons, is automatically performed by reconstruction algorithms. We attain enough quality of the analyses using these algorithms and several impressive results have been addressed

  1. Reconstruction algorithms in the Super-Kamiokande large water Cherenkov detector

    Shiozawa, M

    1999-01-01

    The Super-Kamiokande experiment, using a large underground water Cherenkov detector, has started its operation since first April, 1996. One of the main physics goals of this experiment is to measure the atmospheric neutrinos. Proton decay search is also an important topic. For these analyses, all measurement of physical quantities of an event such as vertex position, the number of Cherenkov rings, momentum, particle type and the number of decay electrons, is automatically performed by reconstruction algorithms. We attain enough quality of the analyses using these algorithms and several impressive results have been addressed.

  2. Spontaneous emission in Cherenkov FEL devices

    Ciocci, F.; Dattoli, G.; Doria, A.; Schettini, G.; Torre, A.; Walsh, J.E.

    1987-01-01

    The main features of the spectral characteristics of the spontaneously emitted Cherenkov light in circular and rectangular wave-guides filled with dielectric are discussed. The characteristics of the radiation emitted by an electron beam moving near and parallel to the surface of a dielectric slab are also analysed. Finally, the relevance of these results to a possible FEL-Cherenkov operation is briefly discussed

  3. The Cherenkov Surface Detector of the Pierre Auger Observatory

    Billoir, Pierre, E-mail: billoir@lpnhe.in2p3.fr [LPNHE, CNRS/IN2P3 and Univ. P. and M. Curie and Univ. D. Diderot, 4 place Jussieu 75272 Paris Cedex 05 (France); Observatorio Pierre Auger, av. San Martín Norte, 304 5613, Malargüe (Argentina)

    2014-12-01

    The Pierre Auger Observatory detects the atmospheric showers induced by cosmic rays of ultra-high energy (UHE). It is the first one to use the hybrid technique. A set of telescopes observes the fluorescence of the nitrogen molecules on clear moonless nights, giving access to the longitudinal profile of the shower. These telescopes surround a giant array of 1600 water Cherenkov tanks (covering more than 3000 km{sup 2}), which works continuously and samples the particles reaching the ground (mainly muons, photons and electrons/positrons); the light produced within the water is recorded into FADC (Fast Analog to Digital Convertes) traces. A subsample of hybrid events provides a cross calibration of the two components. We describe the structure of the Cherenkov detectors, their sensitivity to different particles and the information they can give on the direction of origin, the energy and the nature of the primary UHE object; we discuss also their discrimination power for rare events (UHE photons or neutrinos). To cope with the variability of weather conditions and the limitations of the communication system, the procedures for trigger and real time calibration have been shared between local processors and a central acquisition system. The overall system has been working almost continuously for 10 years, while being progressively completed and increased by the creation of a dense “infill” subarray. - Highlights: • The water Cherenkov technique is used in the Surface Detector of the Pierre Auger Observatory. • Cross-calibrated with the Fluorescence Detector, it provides a measurement of the primary energy. • The spectrum of the UHE cosmic rays exhibits clearly an “ankle” and a cutoff. • The muon observed muon content of the atmospheric showers is larger than expected from the models. • Stringent limits on the flux of UHE neutrinos and photons are obtained.

  4. Extensive air showers and diffused Cherenkov light detection: The ULTRA experiment

    Agnetta, G.; Assis, P.; Biondo, B.

    2007-01-01

    The Uv Light Transmission and Reflection in the Atmosphere (ULTRA) experiment has been designed to provide quantitative measurements of the backscattered Cherenkov signal associated to the Extensive Air Showers (EAS) at the impact point on the Earth surface. The knowledge of such information will test the possibility to detect the diffused Cherenkov light spot from space within the Ultra high-energy cosmic ray observation. The Cherenkov signal is necessary to give an absolute reference for the track, allowing the measurement of the shower maximum and easing the separation between neutrino and hadronic showers. In this paper we discuss the experimental set-up with detailed information on the detection method; the in situ and laboratory calibrations; the simulation of the expected detector response and finally the preliminary results on the detector performance

  5. Atmospheric corrosion effects on copper

    Franey, J.P.

    1985-01-01

    Studies have been performed on the naturally formed patina on various copper samples. Samples have been obtained from structures at AT and T Bell Laboratories, Murray Hill, NJ (40,2,1 and <1 yr) and the Statue of Liberty (100 yr). The samples show a distinct layering effect, that is, the copper base material shows separate oxide and basic sulfate layers on all samples, indicating that patina is not a homogeneous mixture of oxides and basic sulfates

  6. Animal Effects from Soviet Atmospheric Nuclear Tests

    2008-03-01

    describes the effect on animal models of atmospheric nuclear weapons tests performed by the Soviet Union at the Semipalatinsk Test Site . Part I describes...understand the pathogenic mechanisms of injury and the likelihood of efficacy of proposed treatment measures. 15. SUBJECT TERMS Semipalatinsk Test Site ...the Semipalatinsk Test Site . Part 1 describes the air blast and thermal radiation effects. Part 2 covers the effects of primary (prompt) radiation and

  7. Cherenkov radiation in a plasma-filled, dielectric coaxial waveguide

    Wu Jianqiang

    2004-01-01

    Using the self-consistent linear field theory, Cherenkov radiation excitated by the beam-wave interaction of a thin annular relativistic electron beam in a plasma-filled, dielectric coaxial cylindrical waveguide was analyzed. The dispersion equation of the interaction, the synchronized condition and the wave growth rate were derived. The energy exchange between the wave and the electron beam in the presence of background plasma was discussed, and the effects of plasma density on the dispersion characteristics, the wave growth rate and the beam-wave energy exchange were calculated and discussed. It was clear that the Cherenkov radiation results from the coupling between the slow TM mode propagated along the waveguide and the negative-energy space-charge mode propagated along the beam, and the coupling strength is proportional to the beam density. It was theoretically demonstrated that due to the background plasma, the plasma-filled coaxial cylindrical Cherenkov maser could operate at higher frequency, get higher wave growth rate, or have higher beam current at the same operating frequency, leading to higher microwave output power. (authors)

  8. The Cherenkov Telescope Array For Very High-Energy Astrophysics

    Kaaret, Philip

    2015-08-01

    The field of very high energy (VHE) astrophysics had been revolutionized by the results from ground-based gamma-ray telescopes, including the current imaging atmospheric Cherenkov telescope (IACT) arrays: HESS, MAGIC and VERITAS. A worldwide consortium of scientists from 29 countries has formed to propose the Cherenkov Telescope Array (CTA) that will capitalize on the power of this technique to greatly expand the scientific reach of ground-based gamma-ray telescopes. CTA science will include key topics such as the origin of cosmic rays and cosmic particle acceleration, understanding extreme environments in regions close to neutron stars and black holes, and exploring physics frontiers through, e.g., the search for WIMP dark matter, axion-like particles and Lorentz invariance violation. CTA is envisioned to consist of two large arrays of Cherenkov telescopes, one in the southern hemisphere and one in the north. Each array will contain telescopes of different sizes to provide a balance between cost and array performance over an energy range from below 100 GeV to above 100 TeV. Compared to the existing IACT arrays, CTA will have substantially better angular resolution and energy resolution, will cover a much wider energy range, and will have up to an order of magnitude better sensitivity. CTA will also be operated as an open observatory and high-level CTA data will be placed into the public domain; these aspects will enable broad participation in CTA science from the worldwide scientific community to fully capitalize on CTA's potential. This talk will: 1) review the scientific motivation and capabilities of CTA, 2) provide an overview of the technical design and the status of prototype development, and 3) summarize the current status of the project in terms of its proposed organization and timeline. The plans for access to CTA data and opportunities to propose for CTA observing time will be highlighed.Presented on behalf of the CTA Consortium.

  9. MEAD Marine Effects of Atmospheric Deposition

    Jickells, T.; Spokes, L.

    2003-04-01

    The coastal seas are one of the most valuable resources on the planet but they are threatened by human activity. We rely on the coastal area for mineral resources, waste disposal, fisheries and recreation. In Europe, high population densities and high levels of industrial activity mean that the pressures arising from these activities are particularly acute. One of the main problems concerning coastal seas is the rapid increase in the amounts of nitrogen-based pollutants entering the water. They come from many sources, the most important ones being traffic, industry and agriculture. These pollutants can be used by algae as nutrients. The increasing concentrations of these nutrients have led to excessive growth of algae, some of which are harmful. When algae die and decay, oxygen in the water is used up and the resulting lower levels of oxygen may lead to fish kills. Human activity has probably doubled the amount of chemically and biologically reactive nitrogen present globally. In Europe the increases have been greater than this, leading to real concern over the health of coastal waters. Rivers have, until recently, been thought to be the most important source of reactive nitrogen to the coastal seas but we now know that inputs from the atmosphere are large and can equal, or exceed, those from the rivers. Our initial hypothesis was that atmospheric inputs are important and potentially different in their effect on coastal ecosystems to riverine inputs and hence require different management strategies. However, we had almost no information on the direct effects of atmospheric deposition on marine ecosystems, though clearly such a large external nitrogen input should lead to enhanced phytoplankton growth The aim of this European Union funded MEAD project has been to determine how inputs of nitrogen from the atmosphere affect the chemistry and biology of coastal waters. To try to answer this, we have conducted field experiments in the Kattegat, an area where we know

  10. Particle Identification in Cherenkov Detectors using Convolutional Neural Networks

    Theodore, Tomalty

    2016-01-01

    Cherenkov detectors are used for charged particle identification. When a charged particle moves through a medium faster than light can propagate in that medium, Cherenkov radiation is released in the shape of a cone in the direction of movement. The interior of the Cherenkov detector is instrumented with PMTs to detect this Cherenkov light. Particles, then, can be identified by the shapes of the images on the detector walls.

  11. Cherenkov TOF PET with silicon photomultipliers

    Dolenec, R.; Korpar, S.; Križan, P.; Pestotnik, R.

    2015-12-01

    As previously demonstrated, an excellent timing resolution below 100 ps FWHM is possible in time-of-flight positron emission tomography (TOF PET) if the detection method is based on the principle of detecting photons of Cherenkov light, produced in a suitable material and detected by microchannel plate photomultipliers (MCP PMTs). In this work, the silicon photomultipliers (SiPMs) were tested for the first time as the photodetectors in Cherenkov TOF PET. The high photon detection efficiency (PDE) of SiPMs led to a large improvement in detection efficiency. On the other hand, the time response of currently available SiPMs is not as good as that of MCP PMTs. The SiPM dark counts introduce a new source of random coincidences in Cherenkov method, which would be overwhelming with present SiPM technology at room temperature. When the apparatus was cooled, its performance significantly improved.

  12. Applications of Cherenkov Light Emission for Dosimetry in Radiation Therapy

    Glaser, Adam Kenneth

    Since its discovery in the 1930's, the Cherenkov effect has been paramount in the development of high-energy physics research. It results in light emission from charged particles traveling faster than the local speed of light in a dielectric medium. The ability of this emitted light to describe a charged particle's trajectory, energy, velocity, and mass has allowed scientists to study subatomic particles, detect neutrinos, and explore the properties of interstellar matter. However, only recently has the phenomenon been considered in the practical context of medical physics and radiation therapy dosimetry, where Cherenkov light is induced by clinical x-ray photon, electron, and proton beams. To investigate the relationship between this phenomenon and dose deposition, a Monte Carlo plug-in was developed within the Geant4 architecture for medically-oriented simulations (GAMOS) to simulate radiation-induced optical emission in biological media. Using this simulation framework, it was determined that Cherenkov light emission may be well suited for radiation dosimetry of clinically used x-ray photon beams. To advance this application, several novel techniques were implemented to realize the maximum potential of the signal, such as time-gating for maximizing the signal to noise ratio (SNR) and Cherenkov-excited fluorescence for generating isotropic light release in water. Proof of concept experiments were conducted in water tanks to demonstrate the feasibility of the proposed method for two-dimensional (2D) projection imaging, three-dimensional (3D) parallel beam tomography, large field of view 3D cone beam tomography, and video-rate dynamic imaging of treatment plans for a number of common radiotherapy applications. The proposed dosimetry method was found to have a number of unique advantages, including but not limited to its non-invasive nature, water-equivalence, speed, high-resolution, ability to provide full 3D data, and potential to yield data in-vivo. Based on

  13. Beam test of Cherenkov counter prototype for ZDF setup

    Kacharava, A.K.; Macharashvili, G.G.; Nioradze, M.S.; Komarov, V.I.; Sopov, V.S.; Chernyshev, V.P.

    1995-01-01

    We describe a Cherenkov counter of total internal reflection for particle separation in the momentum range where all types of particles radiate Cherenkov light. The Cherenkov counter prototype with the lucite radiator was tested on the secondary beam of the ITEP (Moscow) accelerator. Dependence of the photomultiplier pulse height on the particle entrance angle was clearly observed. 4 refs., 4 figs

  14. The Cherenkov Radiation for Non-Trivial Systems; La Radiacion Cherenkov en Sistemas No Triviales

    Grau Carles, A.

    2002-07-01

    The charge pathways and the dielectric properties of the medium are two essential aspects to be considered in the study of the emission of Cherenkov radiation. We described the evolution of the Cherenkov wavefront when the charges follow circular or helical pathways. Also we derive expressions for the refractive Index in different transparent media (solid, liquid or gas), focusing our attention on optically active plasmas. The optical analogies between the plasma and the birefringent crystals is studied in detail. Finally, we list some examples of plasmas, which can be considered emitters of Cherenkov radiation. (Author) 52 refs.

  15. The Cherenkov Surface Detector of the Pierre Auger Observatory

    Billoir, Pierre

    2014-12-01

    The Pierre Auger Observatory detects the atmospheric showers induced by cosmic rays of ultra-high energy (UHE). It is the first one to use the hybrid technique. A set of telescopes observes the fluorescence of the nitrogen molecules on clear moonless nights, giving access to the longitudinal profile of the shower. These telescopes surround a giant array of 1600 water Cherenkov tanks (covering more than 3000 km2), which works continuously and samples the particles reaching the ground (mainly muons, photons and electrons/positrons); the light produced within the water is recorded into FADC (Fast Analog to Digital Convertes) traces. A subsample of hybrid events provides a cross calibration of the two components. We describe the structure of the Cherenkov detectors, their sensitivity to different particles and the information they can give on the direction of origin, the energy and the nature of the primary UHE object; we discuss also their discrimination power for rare events (UHE photons or neutrinos). To cope with the variability of weather conditions and the limitations of the communication system, the procedures for trigger and real time calibration have been shared between local processors and a central acquisition system. The overall system has been working almost continuously for 10 years, while being progressively completed and increased by the creation of a dense "infill" subarray.

  16. NECTAr: New electronics for the Cherenkov Telescope Array

    Vorobiov, S.; Bolmont, J.; Corona, P.; Delagnes, E.; Feinstein, F.; Gascon, D.; Glicenstein, J.-F.; Naumann, C.L.; Nayman, P.; Sanuy, A.; Toussenel, F.; Vincent, P.

    2011-01-01

    The European astroparticle physics community aims to design and build the next generation array of Imaging Atmospheric Cherenkov Telescopes (IACTs), that will benefit from the experience of the existing H.E.S.S. and MAGIC detectors, and further expand the very-high energy astronomy domain. In order to gain an order of magnitude in sensitivity in the 10 GeV to >100TeV range, the Cherenkov Telescope Array (CTA) will employ 50-100 mirrors of various sizes equipped with 1000-4000 channels per camera, to be compared with the 6000 channels of the final H.E.S.S. array. A 3-year program, started in 2009, aims to build and test a demonstrator module of a generic CTA camera. We present here the NECTAr design of front-end electronics for the CTA, adapted to the trigger and data acquisition of a large IACTs array, with simple production and maintenance. Cost and camera performances are optimized by maximizing integration of the front-end electronics (amplifiers, fast analog samplers, ADCs) in an ASIC, achieving several GS/s and a few μs readout dead-time. We present preliminary results and extrapolated performances from Monte Carlo simulations.

  17. NECTAr: New electronics for the Cherenkov Telescope Array

    Vorobiov, S., E-mail: vorobiov@lpta.in2p3.f [LPTA, Universite Montpellier II and IN2P3/CNRS, Montpellier (France); Bolmont, J.; Corona, P. [LPNHE, Universite Paris VI and IN2P3/CNRS, Paris (France); Delagnes, E. [IRFU/DSM/CEA, Saclay, Gif-sur-Yvette (France); Feinstein, F. [LPTA, Universite Montpellier II and IN2P3/CNRS, Montpellier (France); Gascon, D. [ICC-UB, Universitat Barcelona, Barcelona (Spain); Glicenstein, J.-F. [IRFU/DSM/CEA, Saclay, Gif-sur-Yvette (France); Naumann, C.L.; Nayman, P. [LPNHE, Universite Paris VI and IN2P3/CNRS, Paris (France); Sanuy, A. [ICC-UB, Universitat Barcelona, Barcelona (Spain); Toussenel, F.; Vincent, P. [LPNHE, Universite Paris VI and IN2P3/CNRS, Paris (France)

    2011-05-21

    The European astroparticle physics community aims to design and build the next generation array of Imaging Atmospheric Cherenkov Telescopes (IACTs), that will benefit from the experience of the existing H.E.S.S. and MAGIC detectors, and further expand the very-high energy astronomy domain. In order to gain an order of magnitude in sensitivity in the 10 GeV to >100TeV range, the Cherenkov Telescope Array (CTA) will employ 50-100 mirrors of various sizes equipped with 1000-4000 channels per camera, to be compared with the 6000 channels of the final H.E.S.S. array. A 3-year program, started in 2009, aims to build and test a demonstrator module of a generic CTA camera. We present here the NECTAr design of front-end electronics for the CTA, adapted to the trigger and data acquisition of a large IACTs array, with simple production and maintenance. Cost and camera performances are optimized by maximizing integration of the front-end electronics (amplifiers, fast analog samplers, ADCs) in an ASIC, achieving several GS/s and a few {mu}s readout dead-time. We present preliminary results and extrapolated performances from Monte Carlo simulations.

  18. FACT - Status and experience from five years of operation of the first G-APD Cherenkov Telescope

    Neise, D.; Adam, J.; Ahnen, M. L.; Baack, D.; Balbo, M.; Bergmann, M.; Biland, A.; Blank, M.; Bretz, T.; Brügge, K. A.; Buss, J.; Dmytriiev, A.; Dorner, D.; Einecke, S.; Hempfling, C.; Hildebrand, D.; Hughes, G.; Linhoff, L.; Mannheim, K.; Müller, S.; Neronov, A.; Nöthe, M.; Paravac, A.; Pauss, F.; Rhode, W.; Shukla, A.; Temme, F.; Thaele, J.; Walter, R.

    2017-12-01

    The First G-APD Cherenkov Telescope (FACT) demonstrates the usability of novel Geiger-mode operated Avalanche Photo Diodes (G-APD, often called SiPM) for Imaging Atmospheric Cherenkov Telescopes (IACT). The camera consists of 1440 pixels with dedicated electronics operating at 2 Giga samples per second. It is installed on the refurbished HEGRA telescope with a mirror area of ≈ 9.5m2 on the Canary Island La Palma. FACT is taking data almost every night since the camera was installed in October 2011. It was possible to improve the data taking efficiency to very high values due to the very stable and reliable operation. This also allows to operate FACT remotely without any need for operators on site. Even remote human intervention became less and less frequent over the years, allowing operation to become mostly automatic. FACT is monitoring the long-term behavior of some very-high energy variable extra-galactic sources with unparalleled sampling density as well as testing the behavior of the sensors under severe weather conditions. Due to the long exposure of FACT's G-APDs under strong moonlight conditions it was possible to evaluate the aging effects of G-APDs due to collected charge. No indication of aging was found. No external calibration device is needed to operate FACT since the properties of the sensors themselves allow for a high precision self-calibration of the camera.

  19. An experimental study on cyclotron-Cherenkov radiation

    Lee, C Y; Masuzaki, M; Yoshida, H; Toyosugi, N; Kamada, K; Ando, R [Kanazawa Univ. (Japan). Department of Physics

    1997-12-31

    Dielectric-loaded cylindrical waveguide configurations with an injected electron beam in which the growth rate of the cyclotron-Cherenkov instability surpasses that of the Cherenkov instability were sought by numerical treatment, and one configuration of this kind was found. This configuration consists of a metallic core and an outer metallic cylinder with a dielectric liner on the inner surface. Based on the calculations, an experimental device was designed and assembled to investigate experimentally radiation due to the cyclotron-Cherenkov instability. Beam propagation in the dielectric-loaded coaxial waveguide and microwave radiation due to the cyclotron-Cherenkov instability and the Cherenkov instability were studied. (author). 6 figs., 10 refs.

  20. Environmental effects of increased atmospheric carbon dioxide

    Soon, W.; Baliunas, S.L.; Robinson, A.B.; Robinson, Z.W.

    1999-01-01

    A review of the literature concerning the environmental consequences of increased levels of atmospheric carbon dioxide leads to the conclusion that increases during the 20th century have produced no deleterious effects upon global climate or temperature. Increased carbon dioxide has, however, markedly increased plant growth rates as inferred from numerous laboratory and field experiments. There is no clear evidence, nor unique attribution, of the global effects of anthropogenic CO 2 on climate. Meaningful integrated assessments of the environmental impacts of anthropogenic CO 2 are not yet possible because model estimates of global and regional climate changes on interannual, decadal and centennial timescales remain highly uncertain.(author)

  1. In-beam test of a DIRC Cherenkov radiator with SiPM

    Kroeck, B.; Hayrapetyan, A.; Foehl, K.; Merle, O.; Dueren, M.; Roy, B.J.; Peters, K.

    2009-01-01

    One of the crucial points for any high energy physics experiment is to obtain a good pion/kaon separation i.e. particle identification (PID). For particles in minimum ionising range, the conventional methods of PID using energy loss and time of flight become insufficient. In such a situation, the measurement of velocity of particles using Cherenkov radiation is an effective tool for PID in combination with momentum information from a tracking detector. The PANDA experiment at FAIR/ GSI plans to use a novel technique for PID with detection of internally reflected Cherenkov (DIRC) light. DIRC uses, in contrast to the conventional gas Cherenkov detectors, a solid radiator and total internal reflection to guide Cherenkov photons onto a detection plane where it will be detected by advanced photon counters. A SiPM is a very new generation photon counter that has several advantages over conventional PMTs. Several prototype Cherenkov detectors with different readout systems are being developed for R and D studies. One such prototype detector with Geiger-APD readout has been built at Giessen and was tested in-beam at GSI. The present report provides details of the very first test measurement

  2. An anti-Cherenkov photomultiplier tube

    Selove, W.; Cormell, L.R.; Dris, M.; Kononenko, W.; Robinson, B.; Yost, B.T.

    1982-01-01

    We have designed a special photomultiplier tube (PMT), with very much reduced sensitivity to Cherenkov light produced in the end window. These PMTs have been produced for us by EMI, and have been used in a modular calorimeter array. The design eliminates a 'hot-spot' problem which was of intolerable magnitude in our application. (orig.)

  3. The nonlinear CWFA [Cherenkov Wakefield Accelerator

    Schoessow, P.

    1989-01-01

    The possible use of nonlinear media to enhance the performance of the Cherenkov Wakefield Accelerator (CWFA) is considered. Numerical experiments have been performed using a new wakefield code which demonstrate larger gradients and transformer ratios in the nonlinear CWFA than are obtained in the linear case. 7 refs., 3 figs

  4. Cherenkov ring imaging using a television digitizer

    Charpak, G.; Peisert, A.; Sauli, F.; Cavestro, A.; Vascon, M.; Zanella, G.

    1981-01-01

    A Cherenkov ring imaging device using as photon detector a multistep spark chamber coupled to a television digitizer is described. Results of a test run using triethylamine as photo-ionizing vapour are presented, as well as preliminary results obtained with a new vapour having an extremely low ionization potential. (orig.)

  5. Calibration strategies for the Cherenkov Telescope Array

    Gaug, M.; Berge, D.; Daniel, M.; Doro, M.; Förster, A.; Hofmann, W.; Maccarone, M.C.; Parsons, D.; de los Reyes Lopez, R.; van Eldik, C.

    2014-01-01

    The Central Calibration Facilities workpackage of the Cherenkov Telescope Array (CTA) observatory for very high energy gamma ray astronomy defines the overall calibration strategy of the array, develops dedicated hardware and software for the overall array calibration and coordinates the calibration

  6. Atmospheric/climatic effects of aircraft emissions

    Pueschel, R.F.

    1996-01-01

    Exhaust emissions from aircraft include oxides of nitrogen (NO x ), water vapor (H 2 O), sulfur dioxide (SO 2 ), carbon dioxide (CO 2 ), carbon monoxide (CO), hydrocarbons (HC) and particles (soot and sulfates). These emissions are small compared to industrial/urban surface emissions. However, because (1) atmospheric residence times of exhaust constituents are longer at altitude, particularly in the stratosphere, than they are in the boundary layer, (2) their background concentrations at altitude are lower than those near the surface, (3) the radiation balance is the more sensitive to atmospheric trace constituents the colder the temperature aloft and (4) inter-hemispheric mixing of aircraft effluents is inhibited, aircraft emissions near and above the tropopause and polewards of 40 degrees latitude can be environmentally critical. That's why atmospheric/climatic effects of aircraft emissions have again received scientific, economic and political scrutiny in the last few years, motivated by growth of subsonic traffic at about 5% per year over the past two decades and the advent of a technologically feasible operation of a supersonic high speed commercial transport (HSCT) fleet

  7. Evaluation of new 5 inch photomultiplier for use in threshold Cherenkov detectors with aerogel radiator

    Wojtsekhowski, B.; Zorn, C.; Flyckt, S.O.

    2000-01-01

    A cost effective alternative to UV-sensitive 5 inch PMTs often used with threshold Aerogel Cherenkov detectors has been developed and tested. The photomultiplier -XP4572-is a variation of the Photonis XP4512 glass window tube with improved electron collection efficiency. Fast timing and high gain were only moderately compromised. The effective quantum efficiency has been measured as twice that of a Burle 8854 Quantacon when exposed to a Cherenkov spectrum generated by Ru-106 electrons (les;3.54 MeV) through 1 cm of high index, high transparency Matsushita Electric aerogel (n=1.05). This new phototube is being installed in an aerogel-based Cherenkov detector for Hall A at Jefferson Lab

  8. Muon imaging of volcanoes with Cherenkov telescopes

    Carbone, Daniele; Catalano, Osvaldo; Cusumano, Giancarlo; Del Santo, Melania; La Parola, Valentina; La Rosa, Giovanni; Maccarone, Maria Concetta; Mineo, Teresa; Pareschi, Giovanni; Sottile, Giuseppe; Zuccarello, Luciano

    2017-04-01

    The quantitative understanding of the inner structure of a volcano is a key feature to model the processes leading to paroxysmal activity and, hence, to mitigate volcanic hazards. To pursue this aim, different geophysical techniques are utilized, that are sensitive to different properties of the rocks (elastic, electrical, density). In most cases, these techniques do not allow to achieve the spatial resolution needed to characterize the shallowest part of the plumbing system and may require dense measurements in active zones, implying a high level of risk. Volcano imaging through cosmic-ray muons is a promising technique that allows to overcome the above shortcomings. Muons constantly bombard the Earth's surface and can travel through large thicknesses of rock, with an energy loss depending on the amount of crossed matter. By measuring the absorption of muons through a solid body, one can deduce the density distribution inside the target. To date, muon imaging of volcanic structures has been mainly achieved with scintillation detectors. They are sensitive to noise sourced from (i) the accidental coincidence of vertical EM shower particles, (ii) the fake tracks initiated from horizontal high-energy electrons and low-energy muons (not crossing the target) and (iii) the flux of upward going muons. A possible alternative to scintillation detectors is given by Cherenkov telescopes. They exploit the Cherenkov light emitted when charged particles (like muons) travel through a dielectric medium, with velocity higher than the speed of light. Cherenkov detectors are not significantly affected by the above noise sources. Furthermore, contrarily to scintillator-based detectors, Cherenkov telescopes permit a measurement of the energy spectrum of the incident muon flux at the installation site, an issue that is indeed relevant for deducing the density distribution inside the target. In 2014, a prototype Cherenkov telescope was installed at the Astrophysical Observatory of Serra

  9. Effect of Atmospheric Ions on Interfacial Water

    Chien-Chang Kurt Kung

    2014-11-01

    Full Text Available The effect of atmospheric positivity on the electrical properties of interfacial water was explored. Interfacial, or exclusion zone (EZ water was created in the standard way, next to a sheet of Nafion placed horizontally at the bottom of a water-filled chamber. Positive atmospheric ions were created from a high voltage source placed above the chamber. Electrical potential distribution in the interfacial water was measured using microelectrodes. We found that beyond a threshold, the positive ions diminished the magnitude of the negative electrical potential in the interfacial water, sometimes even turning it to positive. Additionally, positive ions produced by an air conditioner were observed to generate similar effects; i.e., the electrical potential shifted in the positive direction but returned to negative when the air conditioner stopped blowing. Sometimes, the effect of the positive ions from the air conditioner was strong enough to destroy the structure of interfacial water by turning the potential decidedly positive. Thus, positive air ions can compromise interfacial water negativity and may explain the known negative impact of positive ions on health.

  10. The first telescope of the HEGRA air Cherenkov imaging telescope array

    Mirzoyan, R.; Kankanian, R.; Krennrich, F.; Mueller, N.; Sander, H.; Sawallisch, P.; Aharonian, F.; Akhperjanian, A.; Beglarian, A.; Fernandez, J.; Fonseca, V.; Grewe, W.; Heusler, A.; Konopelko, A.K.; Lorenz, E.; Merck, M.; Plyasheshnikov, A.V.; Renker, D.; Samorski, M.; Sauerland, K.; Smarsch, E.; Stamm, W.; Ulrich, M.; Wiedner, C.A.; Wirth, H.

    1994-01-01

    In search of VHE γ ray emission from cosmic point sources a system of imaging Cherenkov telescopes is constructed at present on the Canarian island of La Palma; the first telescope has been operational since 1992. The Cherenkov light from air shower particles is collected by a 5 m 2 reflector. The camera at the focus contains 37 photomultipliers which sample the images of the Cherenkov flashes. The subsequent image analysis allows the discrimination of γ ray induced events from the much more abundant charged cosmic ray induced showers. The telescope has an effective energy threshold for γ showers of about 1.5 TeV. During the first year of operation a signal from the Crab nebula was detected. ((orig.))

  11. SU-F-T-684: Analysis of Cherenkov Excitation in Tissue and the Feasibility of Cherenkov Excited Photodynamic Therapy

    Saunders, Sara L; Andreozzi, Jacqueline M; Pogue, Brian W; Glaser, Adam K

    2016-01-01

    Purpose: The irradiation of photodynamic agents with radiotherapy beams has been demonstrated to enhance tumor killing in various studies, and one proposed mechanism is the optical fluence of Cherenkov emission activating the photosensitizer. This mechanism is explored in Monte Carlo simulations of fluence as well as laboratory measurements of fluence and radical oxygen species. Methods: Simulations were completed using GAMOS/GEANT4 with a 6 MV photon beam in tissue. The effects of blood vessel diameter, blood oxygen saturation, and beam size were examined, recording spectral fluence. Experiments were carried out in solutions of photosensitizer and phantoms. Results: Cherenkov produced by a 100×100um"2 6 MV beam resulted in fluence of less than 1 nJ/cm"2/Gy per 1 nm wavelength. At this microscopic level, differences in absorption of blood and water in the tissue affected the fluence spectrum, but variation in blood oxygenation had little effect. Light in tissue resulting from larger (10mm ×10mm) 6 MV beams had greater fluence due to light transport and elastic scattering of optical photons, but this transport process also resulted in higher absorption shifts. Therefore, the spectrum produced by a microscopic beam was weighted more heavily in UV/blue wavelengths than the spectrum at the macroscopic level. At the macroscopic level, the total fluence available for absorption by Verteporfin (BPD) in tissue approached uJ/cm"2 for a high radiation dose, indicating that photodynamic activation seems unlikely. Tissue phantom confirmation of these light levels supported this observation, and photosensitization measurements with a radical oxygen species reporter are ongoing. Conclusion: Simulations demonstrated that fluence produced by Cherenkov in tissue by 6 MV photon beams at typical radiotherapy doses appears insufficient to activate photosensitizers to the level required for threshold effects, yet this disagrees with published biological experiments. Experimental

  12. SU-F-T-684: Analysis of Cherenkov Excitation in Tissue and the Feasibility of Cherenkov Excited Photodynamic Therapy

    Saunders, Sara L; Andreozzi, Jacqueline M; Pogue, Brian W [Dartmouth College, Hanover, NH (United States); Glaser, Adam K [University of Washington, Seattle, WA (United States)

    2016-06-15

    Purpose: The irradiation of photodynamic agents with radiotherapy beams has been demonstrated to enhance tumor killing in various studies, and one proposed mechanism is the optical fluence of Cherenkov emission activating the photosensitizer. This mechanism is explored in Monte Carlo simulations of fluence as well as laboratory measurements of fluence and radical oxygen species. Methods: Simulations were completed using GAMOS/GEANT4 with a 6 MV photon beam in tissue. The effects of blood vessel diameter, blood oxygen saturation, and beam size were examined, recording spectral fluence. Experiments were carried out in solutions of photosensitizer and phantoms. Results: Cherenkov produced by a 100×100um{sup 2} 6 MV beam resulted in fluence of less than 1 nJ/cm{sup 2}/Gy per 1 nm wavelength. At this microscopic level, differences in absorption of blood and water in the tissue affected the fluence spectrum, but variation in blood oxygenation had little effect. Light in tissue resulting from larger (10mm ×10mm) 6 MV beams had greater fluence due to light transport and elastic scattering of optical photons, but this transport process also resulted in higher absorption shifts. Therefore, the spectrum produced by a microscopic beam was weighted more heavily in UV/blue wavelengths than the spectrum at the macroscopic level. At the macroscopic level, the total fluence available for absorption by Verteporfin (BPD) in tissue approached uJ/cm{sup 2} for a high radiation dose, indicating that photodynamic activation seems unlikely. Tissue phantom confirmation of these light levels supported this observation, and photosensitization measurements with a radical oxygen species reporter are ongoing. Conclusion: Simulations demonstrated that fluence produced by Cherenkov in tissue by 6 MV photon beams at typical radiotherapy doses appears insufficient to activate photosensitizers to the level required for threshold effects, yet this disagrees with published biological experiments

  13. Stability and linearity control of spectrometric channels of the Cherenkov counters using controllable units

    Kollar, D.; Kollarova, L.; Khorvat, P.

    1976-01-01

    A system is elaborated to control stability and linearity of the Cherenkov counter spectrometric channels in an experiment on a magnetic monopole search. Linearity of a light characteristic of a photoelectric multiplier is checked with the help of the calibrated light-strikings of light emitting diodes with flare intensity adjusted by controlling generator voltage across the mercury body. A program algorithm is presented for checking stability and linearity of the Cherenkov counter spectrometric channels which helps to consider the fatigue effects of the photoelectric multiplier resulting from the considerable loads

  14. Cherenkov detectors for spatial imaging applications using discrete-energy photons

    Rose, Paul B.; Erickson, Anna S., E-mail: erickson@gatech.edu [Georgia Institute of Technology, Nuclear and Radiological Engineering, G.W. Woodruff School of Mechanical Engineering, 770 State St., Atlanta, Georgia 30332 (United States)

    2016-08-14

    Cherenkov detectors can offer a significant advantage in spatial imaging applications when excellent timing response, low noise and cross talk, large area coverage, and the ability to operate in magnetic fields are required. We show that an array of Cherenkov detectors with crude energy resolution coupled with monochromatic photons resulting from a low-energy nuclear reaction can be used to produce a sharp image of material while providing large and inexpensive detector coverage. The analysis of the detector response to relative transmission of photons with various energies allows for reconstruction of material's effective atomic number further aiding in high-Z material identification.

  15. A new approach to the theory of Cherenkov radiation based on relativistic generalization of the Landau criterion

    Chefranov, S.G.

    2004-01-01

    Relativistic generalization of the Landau criterion is obtained which, in contrast to the classical Tamm-Frank and Ginzburg theories, determines the primary energy mechanism of emission of nonbremsstrahlung Cherenkov radiation. It is shown that Cherenkov radiation may correspond to a threshold energetically favorable conversion of the condensate (ultimately long-wavelength) elementary Bose perturbations of a medium into transverse Cherenkov photons emitted by the medium proper during its interaction with a sufficiently fast charged particle. The threshold conditions of emission are determined for a medium with an arbitrary refractive index n, including the case of isotropic plasma with n < 1 for which the classical theory of Cherenkov radiation prohibits such direct and effective nonbremsstrahlung emission of these particular transverse high-frequency electromagnetic waves. It is established that these conditions of emission agree with the data of well-known experiments on the threshold for observation of Cherenkov radiation, whereas the classical theory only corresponds to the conditions of observation of the interference maximum of this radiation. The possibility of direct effective emission of nonbremsstrahlung Cherenkov radiation, not taken into account in the classical theory, is considered for many observed astrophysical phenomena (type III solar radio bursts, particle acceleration by radiation, etc.)

  16. Optical trigger: a Cherenkov effect discriminator for high energy physics. Realisation and characterisation of thin films whose refractive index allow discrimination over a wide spectral range.; Le Trigger Optique: un discriminateur a effet Cherenkov pour la physique des particules. Realisation et caracterisation de couches minces dont l`indice de refraction autorise la discrimination sur un large domaine spectral

    Delbart, A

    1996-06-19

    The first part of this thesis sets the physical principles, and properties of actual Optical Triggers. For each of them, the cupel is sapphire made, and the external medium is liquid because of refractive index. The theory of Cherenkov emitted light cone explain how sapphire birefringence affects discrimination conditions.The second parts of the thesis (the main one) is focussed on study and realization of thin films for Optical Trigger. A layer characterization method has been developed by spectrophotometry, based on Perkin-Elmer laboratory device. Computerized simulation helped us to determine characteristics and limits of the studied device. (D.L.). Refs.

  17. Development of aerogel Cherenkov detectors at Novosibirsk

    Barnyakov, A.Yu.; Barnyakov, M.Yu.; Baehr, J.; Bellunato, T.; Beloborodov, K.I.; Bobrovnikov, V.S.; Buzykaev, A.R.; Calvi, M.; Danilyuk, A.F.; Djordjadze, V.; Golubev, V.B.; Kononov, S.A.; Kravchenko, E.A.; Lipka, D.; Matteuzzi, C.; Musy, M.; Onuchin, A.P.; Perego, D.; Rodiakin, V.A.; Savinov, G.A.; Serednyakov, S.I.; Shamov, A.G.; Stephan, F.; Tayursky, V.A.; Vorobiov, A.I.

    2005-01-01

    The development of aerogel Cherenkov counters with the light collection using a wavelength shifter is described. 80 counters of this type are working in the KEDR detector. A project of similar counters for the SND detector based on 'heavy' aerogel with n=1.13 has been developed. Aerogel with a refractive index of 1.006-1.13 and dimensions of blocks up to 200x200x50mm 3 is produced by the Novosibirsk group for use in Cherenkov counters of different types. The Novosibirsk group is participating in the development of LHCb RICH as well as a beam diagnostics for a photo-injector test facility at DESY-Zeuthen. Recently we started development of RICH based on focusing aerogel (FARICH) for the endcap of the SuperBaBar. For the first time in the world the focusing aerogel with layers of different refractive indices has been produced

  18. Photon detection in ring imaging Cherenkov counters

    Jansen, H.

    1988-01-01

    One of the parts of DELPHI (a detector at the CERN LEP) is the barrel-RICH which uses Cherenkov radiation to determine the velocity of charged particles; together with the measured momentum this information yields the mass of each particle. The performance of the photon detector, which determines to a large extent the analyzing power of the barrel-RICH, is studied. 98 refs.; 40 figs.; 6 tabs

  19. Effect of atmospheric fluoride on plant metabolism

    Suketa, Y; Yamamoto, T

    1971-05-01

    Studies on the relationship between the exposure factor and foliar deposition of fluoride, or foliar burn, are introduced. Photosynthesis is adversely affected by atmospheric fluoride. The photosynthesis of a strawberry deteriorated by 50% when the strawberry was exposed to 48 ppb hydrofluoric acid for one hour. The effect of fluoride on the respiratory organs of plants is also reported. Soy beans exposed to 0.03 ppm HF had metabolic abnormalities. The total sugar quantity of leaves decreased from 242-253 mg/100 g to 111-141 mg/100 g and the non-reduced sugar/reduced sugar ratio decreased from 4.6-8.7 to 0.8-1.6. 30 references, 3 figures, 14 tables.

  20. Light collection and its fluctuation in Cherenkov and scintillation spectrometers

    Kitaev, D.F.; Samedov, V.V.; Stolyarova, E.L.

    1982-01-01

    The GAMMA program for calculating light collection in the Cherenkov and scintillation counters is described. Together with the shower modelling program the GAMNA program can be used for evaluating the output signal and energy resolution of shower spectrometers. Principle formulae and block diagram of the program are given. Results of test calculations performed on the example of scintillation counters of culindrical and rectangular shapes were considered. Modelling of the radiation polarization envisaged in the program permits to take account of the effect of selective discrimination of photoelectron amplifier photocathode. The program analyzes, for the present situation, calculation errors which permits to plan in advance the calculation with the given accuracy. The program permits to use additional subprograms together with it where it is possible to take account of other peculiarities of light collection, for example, the presence of outer reflectors and focusing elements of light collection systems, particle slowing down in the spectrometer radiator expressed in the change of angle of semiaperture of the Cherenkov radiation cone. It is concluded on the basis of analyzing results of test calculations that the choosen technique and algorithms of light collection coefficient calculation in spectrometer radiators are correct

  1. Development of a mid-sized Schwarzschild-Couder Telescope for the Cherenkov Telescope Array

    Cameron, Robert A.

    2012-06-28

    The Cherenkov Telescope Array (CTA) is a ground-based observatory for very high-energy (10 GeV to 100 TeV) gamma rays, planned for operation starting in 2018. It will be an array of dozens of optical telescopes, known as Atmospheric Cherenkov Telescopes (ACTs), of 8 m to 24 m diameter, deployed over an area of more than 1 square km, to detect flashes of Cherenkov light from showers initiated in the Earth's atmosphere by gamma rays. CTA will have improved angular resolution, a wider energy range, larger fields of view and an order of magnitude improvement in sensitivity over current ACT arrays such as H.E.S.S., MAGIC and VERITAS. Several institutions have proposed a research and development program to eventually contribute 36 medium-sized telescopes (9 m to 12 m diameter) to CTA to enhance and optimize its science performance. The program aims to construct a prototype of an innovative, Schwarzschild-Couder telescope (SCT) design that will allow much smaller and less expensive cameras and much larger fields of view than conventional Davies-Cotton designs, and will also include design and testing of camera electronics for the necessary advances in performance, reliability and cost. We report on the progress of the mid-sized SCT development program.

  2. Measurement of aerogel performance for ring image Cherenkov detector of HERMES

    Kanesaka, Jiro; Zhang Linfeng; Sato, Fumiko; Suetsugu, Kentaro; Sakami, Yasuhiro; Shibata, Toshiaki

    1999-01-01

    The first experiment of ring image Cherenkov detector (RICH) used aerogel in the world was reported in this paper. We built RICH using aerogel as illuminant for HERMES. The refractive index and size of all aerogel tiles were measured in order to select them for construction of RICH. The select conditions of tile were 113.1 -4 , the dispersion of refractive index of aerogel tile, which condition was fitted to the accuracy of Cherenkov light emission angle of RICH. The mean thickness, transmission and reflection of tile, the thickness of corner of tile (thickness of surface), the refractive index dependence on position and temperature were measured. The effect of thickness of tile on the shift of Cherenkov emission angle was 6.1% the maximum value per one tile and 0.18% mean value of center. The effect of position dependence of refractive index on the Cherenkov light emission angle was agreed with the effect of dispersion of thickness of tile. The transmission and reflection of tile were almost same as the theoretical value. (S.Y.)

  3. A wide dynamic range experiment to measure high energy γ-showers in air by detecting Cherenkov light in the middle ultraviolet

    Apollinari, G.; Bedeschi, F.; Belforte, S.; Bellettini, G.; Bertolucci, E.; Cervelli, F.; Chiarelli, G.; Dell'Orso, M.; Giannetti, P.; Menzione, A.; Ristori, L.; Scribano, A.; Sestini, P.; Stefanini, A.; Zetti, F.; Pisa Univ.

    1988-01-01

    An experiment to study high energy γ rays from localized cosmic sources is described. A number of Al mirrors reflects the Cherenkov light emitted by the showers into photosensitive gas chambers on the mirror focal plane. The use of gas chambers with large active areas allows a sensitivity superior to existing experiments to be reached. Pad readout gives the required angular accuracy. The chamber is sensitive to the middle ultraviolet Cherenkov light produced by the showers in the atmosphere. Since the ozone in the upper atmosphere absorbs the direct ultraviolet light from any outer source, the lower level atmosphere provides a large dark volume in which the Cherenkov radiation from the showers can be isolated. (orig.)

  4. Effect of modified atmosphere packaging and addition of calcium hypochlorite on the atmosphere composition, colour and microbial quality of mushrooms

    Kuyper, L

    1993-01-01

    Full Text Available The effect of modified atmosphere packaging in combination with the addition of calcium hypochlorite on the atmosphere composition, colour and microbial quality of mushrooms was investigated. A modified atmosphere which slowed down discolouration...

  5. On the fine structure of the Vavilov-Cherenkov radiation

    Afanas'ev, G.N.; Kartavenko, V.G.; Zrelov, V.P.

    2003-01-01

    The aim of this paper is to study the fine structure of the Cherenkov rings. We analyze Zrelov's experiments in which the Cherenkov radiation was detected without using the special focusing devices. The broad Cherenkov ring was observed in the plane perpendicular to the motion axis. Using the exact and approximate formulae, we investigate how a charge uniformly moving in a medium radiates in a finite space interval. The formulae obtained describe the radiation intensity in the whole space interval, inside and outside the Cherenkov ring. In the plane perpendicular to the motion axis, the radiation fills mainly the finite ring. Its width, proportional to the motion interval, and the energy released in this ring do not depend on the position of the observation plane. Outside the Cherenkov ring, the radiation intensity suddenly drops. Inside it, the radiation intensity exhibits small oscillations which are due to the interference of the Vavilov-Cherenkov radiation and bremsstrahlung. The increase in the radiation intensity at the ends of the Cherenkov ring is associated with the shock waves arising at the beginning and the end of the charge motion and at the moments when the charge velocity coincides with the light velocity in a medium. For the chosen motion interval, the well-known Tamm formula does not describe the radiation intensity inside the Cherenkov ring for any position of the observation plane. Outside the Cherenkov ring, the Tamm formula is valid only at very large observation distances. Theoretical calculations are in satisfactory agreement with experimental data. Thus, the combined experimental and theoretical study of the unfocused Cherenkov rings allows one to obtain information on the physical processes accompanying the Cherenkov radiation (bremsstrahlung, transition of the light velocity barrier, etc.)

  6. SU-G-IeP4-06: Feasibility of External Beam Treatment Field Verification Using Cherenkov Imaging

    Black, P; Na, Y; Wuu, C [Columbia University, New York, NY (United States)

    2016-06-15

    Purpose: Cherenkov light emission has been shown to correlate with ionizing radiation (IR) dose delivery in solid tissue. In order to properly correlate Cherenkov light images with real time dose delivery in a patient, we must account for geometric and intensity distortions arising from observation angle, as well as the effect of monitor units (MU) and field size on Cherenkov light emission. To test the feasibility of treatment field verification, we first focused on Cherenkov light emission efficiency based on MU and known field size (FS). Methods: Cherenkov light emission was captured using a PI-MAX4 intensified charge coupled device(ICCD) system (Princeton Instruments), positioned at a fixed angle of 40° relative to the beam central axis. A Varian TrueBeam linear accelerator (linac) was operated at 6MV and 600MU/min to deliver an Anterior-Posterior beam to a 5cm thick block phantom positioned at 100cm Source-to-Surface-Distance(SSD). FS of 10×10, 5×5, and 2×2cm{sup 2} were used. Before beam delivery projected light field images were acquired, ensuring that geometric distortions were consistent when measuring Cherenkov field discrepancies. Cherenkov image acquisition was triggered by linac target current. 500 frames were acquired for each FS. Composite images were created through summation of frames and background subtraction. MU per image was calculated based on linac pulse delay of 2.8ms. Cherenkov and projected light FS were evaluated using ImageJ software. Results: Mean Cherenkov FS discrepancies compared to light field were <0.5cm for 5.6, 2.8, and 8.6 MU for 10×10, 5×5, and 2×2cm{sup 2} FS, respectably. Discrepancies were reduced with increasing field size and MU. We predict a minimum of 100 frames is needed for reliable confirmation of delivered FS. Conclusion: Current discrepancies in Cherenkov field sizes are within a usable range to confirm treatment delivery in standard and respiratory gated clinical scenarios at MU levels appropriate to

  7. Effect of atmospheric pollution on health

    Islam, M.S.

    1990-01-01

    In recent years the incidence of smog episodes and their intensity have gone down considerably and difference in atmospheric pollutant levels between urban and rural areas is very small. Even the sudden moderate elevation of atmospheric pollution during winter months affects the pulmonary function adversely and provokes increased respiratory symptomes. The prevalence of rhinitis and allergy is more frequent both in adults and in children in urban townships than in rural areas. It has also been observed that industrial city dwellers have inferior pulmonary function. Very recent results indicate possible interaction between atmospheric pollutant levels and regeneration process following airways infection in yound children. (orig.) [de

  8. Selective Filtration of Gadolinium Trichloride for Use in Neutron Detection in Large Water Cherenkov Detectors

    Vagins, Mark R.

    2013-01-01

    Super-??Kamiokande Water Cherenkov detectors have been used for many years as inexpensive, effective detectors for neutrino interactions and nucleon decay searches. While many important measurements have been made with these detectors a major drawback has been their inability to detect the absorption of thermal neutrons. We believe an inexpensive, effective technique could be developed to overcome this situation via the addition to water of a solute with a large neutron cross section and energetic gamma daughters which would make neutrons detectable. Gadolinium seems an excellent candidate especially since in recent years it has become very inexpensive, now less than $8 per kilogram in the form of commercially-available gadolinium trichloride, GdCl 3 . This non-toxic, non-reactive substance is highly soluble in water. Neutron capture on gadolinium yields a gamma cascade which would be easily seen in detectors like Super-Kamiokande. We have been investigating the use of GdCl 3 as a possible upgrade for the Super-Kamiokande detector with a view toward improving its performance as a detector for atmospheric neutrinos, supernova neutrinos, wrong-sign solar neutrinos, reactor neutrinos, proton decay, and also as a target for the coming T2K long-baseline neutrino experiment. This focused study of selective water filtration and GdCl 3 extraction techniques, conducted at UC Irvine, followed up on highly promising benchtop-scale and kiloton-scale work previously carried out with the assistance of 2003 and 2005 Advanced Detector Research Program grants

  9. Effects of atmospheric pollution on vegetation

    Metcalfe, C R

    1953-10-10

    In September, 1953, two sections of the British Association (Botany and Forestry) jointly discussed the effects of various components of air pollution. Conclusions reached included the position that the symptoms of ill health in plants that have been subjected to a polluted fog are due not so much to reduction in availability of light as to the presence of toxic substances in the atmosphere. Examples of these symptoms include shedding of flowers and leaves, blackening and death of buds and flowers, scorching of foliage, and complete destruction of more sensitive plants. Sulfur dioxide was identified as one of the more important toxic substances. Practical remedies for the problem were discussed, and the currently-known dose-response relationships (concentrations in excess of 0.5 ppm were known to cause lesions on some plants) were defined. Instances of reduced growth of crop plants and the inhibition of development of lichens and mosses were recounted. The complex relationships between soil condition and air pollution of the growth of plants were discussed.

  10. Effect of Atmospheric Conditions on LIBS Spectra

    Effenberger, Andrew J.; Scott, Jill R.

    2010-01-01

    Laser-induced breakdown spectroscopy (LIBS) is typically performed at ambient Earth atmospheric conditions. However, interest in LIBS in other atmospheric conditions has increased in recent years, especially for use in space exploration (e.g., Mars and Lunar) or to improve resolution for isotopic signatures. This review focuses on what has been reported about the performance of LIBS in reduced pressure environments as well as in various gases other than air.

  11. Effect of Atmospheric Conditions on LIBS Spectra

    Effenberger, Andrew J.; Scott, Jill R.

    2010-01-01

    Laser-induced breakdown spectroscopy (LIBS) is typically performed at ambient Earth atmospheric conditions. However, interest in LIBS in other atmospheric conditions has increased in recent years, especially for use in space exploration (e.g., Mars and Lunar) or to improve resolution for isotopic signatures. This review focuses on what has been reported about the performance of LIBS in reduced pressure environments as well as in various gases other than air. PMID:22399914

  12. Development of a research reactor power measurement system using Cherenkov radiation

    Salles, Brício M.; Mesquita, Amir Z.

    2017-01-01

    Nuclear research reactors are usually located in open pools, to allow visibility to the core and bluish luminosity of Cherenkov radiation. Usually the thermal power released in these reactors is monitored by chambers that measure the neutron flux, as it is proportional to the power. There are other methods used for power measurement, such as monitoring the core temperature and the energy balance in the heat exchanger. The brightness of Cherenkov's radiation is caused by the emission of visible electromagnetic radiation (in the blue band) by charged particles that pass through an insulating medium (water in nuclear research reactors) at a speed higher than that of light in this medium. This effect was characterized by Pavel Cherenkov, which earned him the Nobel Prize for Physics in 1958. The project's objective is to develop an innovative and alternative method for monitoring the power of nuclear research reactors. It will be performed by analyzing and monitoring the intensity of luminosity generated by Cherenkov radiation in the reactor core. This method will be valid for powers up to 250 kW, since above that value the luminosity saturates, as determined by previous studies. The reactor that will be used to test the method is the TRIGA, located at Nuclear Technology Development Center (CDTN), which currently has a maximum operating power of 250 kW. This project complies with International Atomic Energy Agency (IAEA) recommendations on reactor safety. It will give more redundancy and diversification in this measure and will not interfere with its operation. (author)

  13. On the prospects of cross-calibrating the Cherenkov Telescope Array with an airborne calibration platform

    Brown, Anthony M.

    2018-01-01

    Recent advances in unmanned aerial vehicle (UAV) technology have made UAVs an attractive possibility as an airborne calibration platform for astronomical facilities. This is especially true for arrays of telescopes spread over a large area such as the Cherenkov Telescope Array (CTA). In this paper, the feasibility of using UAVs to calibrate CTA is investigated. Assuming a UAV at 1km altitude above CTA, operating on astronomically clear nights with stratified, low atmospheric dust content, appropriate thermal protection for the calibration light source and an onboard photodiode to monitor its absolute light intensity, inter-calibration of CTA's telescopes of the same size class is found to be achievable with a 6 - 8 % uncertainty. For cross-calibration of different telescope size classes, a systematic uncertainty of 8 - 10 % is found to be achievable. Importantly, equipping the UAV with a multi-wavelength calibration light source affords us the ability to monitor the wavelength-dependent degradation of CTA telescopes' optical system, allowing us to not only maintain this 6 - 10 % uncertainty after the first few years of telescope deployment, but also to accurately account for the effect of multi-wavelength degradation on the cross-calibration of CTA by other techniques, namely with images of air showers and local muons. A UAV-based system thus provides CTA with several independent and complementary methods of cross-calibrating the optical throughput of individual telescopes. Furthermore, housing environmental sensors on the UAV system allows us to not only minimise the systematic uncertainty associated with the atmospheric transmission of the calibration signal, it also allows us to map the dust content above CTA as well as monitor the temperature, humidity and pressure profiles of the first kilometre of atmosphere above CTA with each UAV flight.

  14. Test of aerogel as Cherenkov radiator

    Alemi, M; Calvi, M; Matteuzzi, C; Negri, P; Paganoni, M; Liko, D; Neufeld, N; Chesi, Enrico Guido; Joram, C; Séguinot, Jacques; Ypsilantis, Thomas

    2001-01-01

    Two different stacks of aerogel were tested in a pion/proton beam of momentum between 3 and 10 GeV/c. The optical characteristics of the aerogel samples were different: one sample was hygroscopic while the other was hydrophobic. Two HPD tubes were used as photodetectors, and different thicknesses of the stacks were used, in order to determine the photoelectron yield, the Cherenkov angle and its precision. Pion/proton separation has been demonstrated at momenta up to 10 GeV/c.

  15. The proposed experiment for search of acoustic phenomena from extensive atmospheric showers in Baikal

    Chernov, Dmitry; Lyashuk, Vladimir; Novikov, Evgeniy

    2009-01-01

    The experiment on registration of acoustic phenomena from Extensive Atmospheric Showers (EAS) falling on Baikal ice is discussed. The hydroacoustic recording will be carried out in response to a radio trigger from installation SPHERE-2 (raised to a height of about 1 km by means of the captive balloon) detecting Cherenkov light from EAS. The new setup of the experiment is necessary to investigate and confirm the obtained indications on acoustic effects from EAS.

  16. Application of Cherenkov light observation to reactor measurements (2). Design and trial fabrication of Cherenkov light estimation system

    Yamamoto, Keiichi; Takeuchi, Tomoaki; Tsuchiya, Kunihiko; Hayashi, Takayasu; Kosuge, Fumiaki; Sano, Tadafumi

    2015-11-01

    Development of the reactor measurement system was started to obtain the real-time in-core nuclear and thermal information, where the quantitative measurement of brightness of Cherenkov light was investigated. This report summarized the results of design and trial fabrication of the Cherenkov light estimation system from thermal power evaluation from Cherenkov light image emitted from the fuel elements. The developed Cherenkov light estimation system was verified with the Cherenkov light image emitted from the fuels in the core of Kyoto University Research Reactor (KUR). From the results, the thermal power of the fuel elements evaluated from the brightness of the Cherenkov light observed by a CCD camera was almost the same as that of thermal power calculated from SRAC code. On the other hand, the evaluation values of some fuel elements were different from the calculation values. This, it is necessary to improve the observation method of Cherenkov light in the reactor and the evaluation method of the brightness of Cherenkov light. (author)

  17. A Cherenkov-emission Microwave Source*

    Lai, C. H.; Yoshii, J.; Katsouleas, T.; Hairapetian1, G.; Joshi, C.; Mori, W.

    1996-11-01

    In an unmagnetized plasma, there is no Cherenkov emission because the phase velocity vf of light is greater than c. In a magnetized plasma, the situation is completely changed. There is a rich variety of plasma modes with phase velocities vf 2 c which can couple to a fast particle. In the magnetized plasma, a fast particle, a particle beam, or even a short laser pulse excites a Cherenkov wake that has both electrostatic and electromagnetic components. Preliminary simulations indicate that at the vacuum/plasma boundary, the wake couples to a vacuum microwave with an amplitude equal to the electromagnetic component in the plasma. For a weakly magnetized plasma, the amplitude of the out-coupled radiation is approximately wc/wp times the amplitude of the wake excited in the plasma by the beam, and the frequency is approximately wp. Since plasma wakes as high as a few GeV/m are produced in current experiments, the potential for a high-power (i.e., GWatt) coherent microwave to THz source exists. In this talk, a brief overview of the scaling laws will be presented, followed by 1-D and 2-D PIC simulations. Prospects for a tuneable microwave source experiment based on this mechanism at the UCLA plasma wakefield accelerator facility will be discussed. *Work supported by AFOSR Grant #F4 96200-95-0248 and DOE Grant # DE-FG03-92ER40745. 1Now at Hughes Research Laboratories, Malibu, CA 90265

  18. Development of aerogel Cherenkov counters at Novosibirsk

    Barnyakov, A.Yu.; Barnyakov, M.Yu.; Baehr, J.; Bellunato, T.; Beloborodov, K.I.; Bobrovnikov, V.S.; Buzykaev, A.R.; Calvi, M.; Danilyuk, A.F.; Djordjadze, V.; Golubev, V.B.; Kononov, S.A.; Kravchenko, E.A.; Lipka, D.; Matteuzzi, C.; Musy, M.; Onuchin, A.P.; Perego, D.; Rodiakin, V.A.; Savinov, G.A.; Serednyakov, S.I.; Shamov, A.G.; Stephan, F.; Tayursky, V.A.; Vorobiov, A.I.

    2006-01-01

    The work on aerogel Cherenkov counters was started in Novosibirsk in 1986. Production of aerogels with refractive indices of 1.006-1.13 and thicknesses of blocks up to 50mm was developed. The light absorption length at 400nm is 5-7m, the scattering length is 4-5cm. By these parameters, the Novosibirsk aerogel is one of the best in the world. The ASHIPH Cherenkov counters with light collection on wavelength shifters have been developed. The ASHIPH system of the KEDR detector contains 1000l of aerogel. The π/K separation is 4.5σ. A project of ASHIPH counters for the SND detector has been developed. Aerogel RICH for LHCb gives a possibility to identify hadrons in the momentum range of 2-10GeV/c. The Novosibirsk group is developing an aerogel RICH for the endcap for the SuperBaBar project. Calculations performed by a group of physicists from Novosibirsk and DESY-Zeuthen have shown that aerogel radiators enable to achieve time resolution up to 20fs

  19. Atmospheric characteristics essential for health effects modeling

    Nelson, N.S.

    1977-01-01

    Factors to be considered in evaluating the possible consequences of exposure of human populations to radioactive aerosols are reviewed. Mathematical models of the mechanisms of radioinduced carcinogenesis, tissue deposition and lung clearance of radioactive aerosols, and meteorological parameters affecting the diffusion of radioactive aerosols in the atmosphere are discussed

  20. Optical Cherenkov radiation in ultrafast cascaded second-harmonic generation

    Bache, Morten; Bang, Ole; Zhou, Binbin

    2010-01-01

    -matching point is located in the absorption region of the crystal, effectively absorbing the generated dispersive wave. By calculating the phase-matching curves for typically used frequency conversion crystals, we point out that the mid-IR absorption in the crystal in many cases automatically will filter away....... The beating between the dispersive wave and the soliton generates trailing temporal oscillations on the compressed soliton. Insertion of a simple short-wave pass filter after the crystal can restore a clean soliton. On the other hand, bandpass filtering around the dispersive wave peak results in near......We show through theory and numerics that when few-cycle femtosecond solitons are generated through cascaded (phase-mismatched) second-harmonic generation, these broadband solitons can emit optical Cherenkov radiation in the form of linear dispersive waves located in the red part of the spectrum...

  1. Effects of atmospheric moisture on rock resistivity.

    Alvarez, R.

    1973-01-01

    This study examines the changes in resistivity of rock samples as induced by atmospheric moisture. Experiments were performed on samples of hematitic sandstone, pyrite, and galena. The sandstone underwent a change in resistivity of four orders of magnitude when it was measured in a vacuum of 500 ntorr and in air of 37% relative humidity. Pyrite and galena showed no variations in resistivity when they were measured under the same conditions. These results, plus others obtained elsewhere, indicate that rocks of the resistive type are affected in their electrical properties by atmospheric moisture, whereas rocks of the conductive type are not. The experimental evidence obtained is difficult to reconcile with a model of aqueous electrolytic conduction on the sample surface. It is instead suggested that adsorbed water molecules alter the surface resistivity in a manner similar to that observed in semiconductors and insulators.

  2. The effect of atmospheric corona treatment on AA1050 aluminium

    Jariyaboon, Manthana; Møller, Per; Dunin-Borkowski, Rafal E.

    2010-01-01

    The effect of atmospheric corona discharge on AM 050 aluminium surface was investigated using electrochemical polarization, SEM-EDX, FIB-SEM. and XPS. The corona treatment was performed with varying time (1, 5, and 15 min) in atmospheric air. A 200 nm oxide layer was generated on AA1050 after...

  3. Cherenkov Water Detectors in Particle Physics and Cosmic Rays

    Petrukhin, A. A.; Yashin, I. I.

    2017-12-01

    Among various types of Cherenkov detectors (solid, liquid and gaseous) created for different studies, the most impressive development was gained by water detectors: from the first detector with a volume of several liters in which the Cherenkov radiation was discovered, to the IceCube detector with a volume of one cubic kilometer. The review of the development of Cherenkov water detectors for various purposes and having different locations - ground-based, underground and underwater-is presented in the paper. The prospects of their further development are also discussed.

  4. The Cherenkov Radiation for Non-Trivial Systems

    Grau Carles, A.

    2002-01-01

    The charge pathways and the dielectric properties of the medium are two essential aspects to be considered in the study of the emission of Cherenkov radiation. We described the evolution of the Cherenkov wavefront when the charges follow circular or helical pathways. Also we derive expressions for the refractive Index in different transparent media (solid, liquid or gas), focusing our attention on optically active plasmas. The optical analogies between the plasma and the birefringent crystals is studied in detail. Finally, we list some examples of plasmas, which can be considered emitters of Cherenkov radiation. (Author) 52 refs

  5. DIRC, the internally reflecting ring imaging Cherenkov detector for BABAR

    Adam, I.; Aston, D.

    1997-11-01

    The DIRC is a new type of Cherenkov imaging device that will be used for the first time in the BABAR detector at the asymmetric B-factory, PEP-II. It is based on total internal reflection and uses long, rectangular bars made from synthetic fused silica as Cherenkov radiator and light guide. The principles of the DIRC ring imaging Cherenkov technique are explained and results from the prototype program are presented. Its choice for the BABAR detector particle identification system is motivated, followed by a discussion of the quartz radiator properties and the detector design

  6. Effect of increased ionization on the atmospheric electric field

    Boeck, W.L.

    1980-01-01

    This study is a review of atmospheric electrical theory with the purpose of predicting the atmospheric electrical effects of increased ionization caused by radioactive inert gases. A time-independent perturbation model for the global atmospheric electric circuit precdicts that the electric field at the sea surface would be reduced to about 76% of its unperturbed value by a surface 85 Kr concentration of 3 nCi/m 3 . The electric field at a typical land station is predicted to be about 84% of its unperturbed value. Some scientists have suggested that the atmospheric electric field is part of a closed electrical feedback loop. The present model does not include such a closed feedback loop and may underestimate the total effects. This model is also useful for interpreting atmospheric electrical responses to natural fluctuations in the cosmic-ray component of background radiation

  7. A multiplicity trigger for a Cherenkov detector

    Jonsson, P.

    1984-05-01

    The Multiplicity Trigger (MT) is a device for deciding if, in a given time window, the number of wires that are hit in a multi wire proportional chamber (MWPC) is within given limits. The MT is designed for a Cherenkov detector, using a MWPC with 155 sense wires. It has ten inputs with sixteen channels on each, for 160 ECL input signals from the MWPC. With the MT, it is possible to decide if the number of hits is greater than n out of 160, where n is called the multiplicity. Here, 2 < n < 30, with an accuracy of +- 1. The time window can be adjusted from 0.7 to 4 μs. The MT has four separate NIM outputs, to make it possible to have four different values of n at the same time. The propagation delay from input to output is at the most 100 ns. (author)

  8. Aerogel Cherenkov Counters of the KEDR Detector

    Ovtin, I V; Barnyakov, M Y; Bobrovnikov, V S; Buzykaev, A R; Danilyuk, A F; Katcin, A A; Kononov, S A; Kravchenko, E A; Kuyanov, I A; Onuchin, A P; Rodiakin, V A

    2017-01-01

    The particle identification system of the KEDR detector is based on aerogel threshold Cherenkov counters called ASHIPH counters. The system consists of 160 counters arranged in two layers. An event reconstruction program for the ASHIPH system was developed. The position of each counter relative to the tracking system was determined using cosmic muons and Bhabha events. The geometric efficiency of the ASHIPH system was verified with Bhabha events. The efficiency of relativistic particle detection was measured with cosmic muons. A π/K separation of 4δ in the momentum range 0.95 −1.45 GeV/c was confirmed. A simulation program for the ASHIPH counters has been developed.

  9. Cherenkov particle identifier for relativistic heavy ions

    Dufour, J P; Olson, D L; Baumgartner, M; Girard, J G; Lindstrom, P J; Greiner, D E; Symons, T J.M.; Crawford, H J

    1985-12-01

    A total internal reflection Cherenkov detector is described. A figure of merit of 84Z/sup 2/sin/sup 2/theta photoelectrons/cm has been measured and the application of the device to charge and velocity measurements of relativistic heavy ions has been tested. We have achieved a charge resolution of ..delta..Zsub(rms)=0.15e for Z=20 with a 3 mm thick glass detector and a velocity resolution of ..delta beta..sub(rms)=2x10/sup -4/ at ..beta..=0.93 and Z=26 with a 6 mm thick fused silica detector. Combining charge and velocity measurements with a magnetic rigidity selection, we have achieved an isotopic mass resolution of ..delta..Msub(rms)=0.1 u with a 2 mm thick fused silica detector for 20

  10. Cherenkov particle identifier for relativistic heavy ions

    Dufour, J P; Olson, D L; Baumgartner, M; Girard, J G; Lindstrom, P J; Greiner, D E; Symons, T J.M.; Crawford, H J

    1985-12-01

    A total internal reflection Cherenkov detector is described. A figure of merit of 84Z/sup 2/sin/sup 2/theta photoelectrons/cm has been measured and the application of the device to charge and velocity measurements of relativistic heavy ions has been tested. We have achieved a charge resolution of ..delta..Zsub(rms)=0.15e for Z=20 with a 3 mm thick glass detector and a velocity resolution of ..delta beta..sub(rms)=2 x 10/sup -4/ at ..beta..=0.93 and Z=26 with a 6 mm thick fused silica detector. Combining charge and velocity measurements with a magnetic rigidity selection, we have achieved an isotopic mass resolution of ..delta..Msub(rms)=0.1 u with a 2 mm thick fused silica detector for 20 < A < 40.

  11. Cherenkov-like emission of Z bosons

    Colladay, D.; Noordmans, J. P.; Potting, R.

    2017-07-01

    We study CPT and Lorentz violation in the electroweak gauge sector of the Standard Model in the context of the Standard-Model Extension (SME). In particular, we show that any non-zero value of a certain relevant Lorentz violation parameter that is thus far unbounded by experiment would imply that for sufficiently large energies one of the helicity modes of the Z boson should propagate with spacelike four-momentum and become stable against decay in vacuum. In this scenario, Cherenkov-like radiation of Z bosons by ultra-high-energy cosmic-ray protons becomes possible. We deduce a bound on the Lorentz violation parameter from the observational data on ultra-high energy cosmic rays.

  12. Solar panels as air Cherenkov detectors for extremely high energy cosmic rays

    Cecchini, S.; D'Antone, I.; Degli Esposti, L.; Giacomelli, G.; Guerra, M.; Lax, I.; Mandrioli, G.; Parretta, A.; Sarno, A.; Schioppo, R.; Sorel, M.; Spurio, M.

    2000-01-01

    Increasing interest towards the observation of the highest energy cosmic rays has motivated the development of new detection techniques. The properties of the Cherenkov photon pulse emitted in the atmosphere by these very rare particles indicate low-cost semiconductor detectors as good candidates for their optical read-out. The aim of this paper is to evaluate the viability of solar panels for this purpose. The experimental framework resulting from measurements performed with suitably-designed solar cells and large conventional photovoltaic areas is presented. A discussion on the obtained and achievable sensitivities follows

  13. Trends in the development of large area photon detectors for Cherenkov light imaging applications

    Nappi, E

    2003-01-01

    Since the successful operations of hi-tech devices at OMEGA, DELPHI and SLD, the technique of Cherenkov light imaging has gone through an impressive and fruitful evolution driven by the conception of novel large area photon detectors. The well-assessed potentialities of thin CsI films, employed as reflective photoconverters in gas counters operated at atmospheric pressure, will be compared with the promising features of hybrid and multianode vacuum photomultipliers. Recently proposed single-photon gaseous detectors based on GEMs will also be reviewed.

  14. Atmospheric greenhouse effect - simple model; Atmosfaerens drivhuseffekt - enkel modell

    Kanestroem, Ingolf; Henriksen, Thormod

    2011-07-01

    The article shows a simple model for the atmospheric greenhouse effect based on consideration of both the sun and earth as 'black bodies', so that the physical laws that apply to them, may be used. Furthermore, explained why some gases are greenhouse gases, but other gases in the atmosphere has no greenhouse effect. But first, some important concepts and physical laws encountered in the article, are repeated. (AG)

  15. The Cherenkov correlated timing detector: materials, geometry and timing constraints

    Aronstein, D.; Bergfeld, T.; Horton, D.; Palmer, M.; Selen, M.; Thayer, G.; Boyer, V.; Honscheid, K.; Kichimi, H.; Sugaya, Y.; Yamaguchi, H.; Yoshimura, Y.; Kanda, S.; Olsen, S.; Ueno, K.; Tamura, N.; Yoshimura, K.; Lu, C.; Marlow, D.; Mindas, C.; Prebys, E.; Pomianowski, P.

    1996-01-01

    The key parameters of Cherenkov correlated timing (CCT) detectors are discussed. Measurements of radiator geometry, optical properties of radiator and coupling materials, and photon detector timing performance are presented. (orig.)

  16. Cherenkov and scintillation light separation in organic liquid scintillators

    Caravaca, J.; Descamps, F.B.; Land, B.J.; Orebi Gann, G.D. [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Yeh, M. [Brookhaven National Laboratory, Upton, NY (United States)

    2017-12-15

    The CHErenkov/Scintillation Separation experiment (CHESS) has been used to demonstrate the separation of Cherenkov and scintillation light in both linear alkylbenzene (LAB) and LAB with 2 g/L of PPO as a fluor (LAB/PPO). This is the first successful demonstration of Cherenkov light detection from the more challenging LAB/PPO cocktail and improves on previous results for LAB. A time resolution of 338 ± 12 ps FWHM results in an efficiency for identifying Cherenkov photons in LAB/PPO of 70 ± 3% and 63 ± 8% for time- and charge-based separation, respectively, with scintillation contamination of 36 ± 5% and 38 ± 4. LAB/PPO data is consistent with a rise time of τ{sub r} = 0.72 ± 0.33 ns. (orig.)

  17. Performance of a prototype water Cherenkov detector for LHAASO project

    An, Q.; Bai, Y.X.; Bi, X.J.; Cao, Z.; Cao, Zhe; Chang, J.F.; Chen, G.; Chen, L.H.; Chen, M.J.; Chen, T.L.; Chen, Y.T.; Cui, S.W.; Dai, B.Z.; Danzengluobu; Feng, C.F.; Gao, B.; Gu, M.H.; Hao, X.J.; He, H.H.; Hu, H.B.

    2011-01-01

    A large high-altitude air shower observatory is to be built at Yang-Ba-Jing, Tibet, China. One of its main purposes is to survey the northern sky for very-high-energy (above 100 GeV) gamma ray sources via its ground-based water Cherenkov detector array. To gain full knowledge of water Cherenkov technique in detecting air showers, a prototype water Cherenkov detector is built at the Institute of High Energy Physics, Beijing. The performance of the prototype water Cherenkov detector is studied by measuring its response to cosmic muons. The results are compared with those from a full Monte Carlo simulation to provide a series of information regarding the prototype detector in guiding electronics design and detector optimization.

  18. Cherenkov and scintillation light separation in organic liquid scintillators

    Caravaca, J.; Descamps, F.B.; Land, B.J.; Orebi Gann, G.D.; Yeh, M.

    2017-01-01

    The CHErenkov/Scintillation Separation experiment (CHESS) has been used to demonstrate the separation of Cherenkov and scintillation light in both linear alkylbenzene (LAB) and LAB with 2 g/L of PPO as a fluor (LAB/PPO). This is the first successful demonstration of Cherenkov light detection from the more challenging LAB/PPO cocktail and improves on previous results for LAB. A time resolution of 338 ± 12 ps FWHM results in an efficiency for identifying Cherenkov photons in LAB/PPO of 70 ± 3% and 63 ± 8% for time- and charge-based separation, respectively, with scintillation contamination of 36 ± 5% and 38 ± 4. LAB/PPO data is consistent with a rise time of τ r = 0.72 ± 0.33 ns. (orig.)

  19. Vavilov-Cherenkov and Synchrotron Radiation Foundations and Applications

    Afanasiev, G. N

    2005-01-01

    The theory of the Vavilov-Cherenkov radiation observed by Cherenkov in 1934 was created by Tamm, Frank and Ginsburg who associated the observed blue light with the uniform charge motion of a charge at a velocity greater than the velocity of light in the medium. On the other hand, Vavilov, Cherenkov's teacher, attributed the observed blue light to the deceleration of electrons. This has given rise to the appearance of papers in which the radiation of a charge uniformly moving in a finite space interval was related to the Bremsstrahlung arising at the end points of the motion interval. This monograph is intended for students of the third year and higher, for postgraduates, for professional scientists (both experimentalists and theoreticians) dealing with Vavilov-Cherenkov and synchrotron radiation. An acquaintance with the three volumes of the Landau and Lifshitz course (Quantum Mechanics, Classical Field Theory and Macroscopic Electrodynamics) is sufficient for understanding the text.

  20. Optical fiber Cherenkov detector for beam current monitoring

    Pishchulin, I.V.; Solov'ev, N.G.; Romashkin, O.B.

    1991-01-01

    The results obtained in calculation of an optical fiber Cherenkov detector for accelerated beam current monitoring are presented. The technique of beam parameters monitoring is based on Cherenkov radiation excitation by accelerated electrons in the optical fiber. The formulas for calculations of optical power and time dependence of Cherenkov radiation pulse are given. The detector sensitivity and time resolution dependence on the fiber material characteristics are investigated. Parameters of a 10μm one-mode quartz optical fiber detector for the free electron laser photoinjector are calculated. The structure of a monitoring system with the optical fiber Cherenkov detector is considered. Possible applications of this technique are discussed and some recommendations are given

  1. Conceptual history of the Vavilov-Cherenkov radiation

    Frank, I.M.

    1984-01-01

    The evolution of ideas on the nature of the Vavilov-Cherenkov radiation is discussed. The period between Vavilov's ideas, advanced in 1934, and the formulation of a quantitative theory of the phenomenon in 1937 is surveyed

  2. Dispersion relation and growth rate in a Cherenkov free electron laser: Finite axial magnetic field

    Kheiri, Golshad; Esmaeilzadeh, Mahdi

    2013-01-01

    A theoretical analysis is presented for dispersion relation and growth rate in a Cherenkov free electron laser with finite axial magnetic field. It is shown that the growth rate and the resonance frequency of Cherenkov free electron laser increase with increasing axial magnetic field for low axial magnetic fields, while for high axial magnetic fields, they go to a saturation value. The growth rate and resonance frequency saturation values are exactly the same as those for infinite axial magnetic field approximation. The effects of electron beam self-fields on growth rate are investigated, and it is shown that the growth rate decreases in the presence of self-fields. It is found that there is an optimum value for electron beam density and Lorentz relativistic factor at which the maximum growth rate can take place. Also, the effects of velocity spread of electron beam are studied and it is found that the growth rate decreases due to the electron velocity spread

  3. The Effect of Starspots on Detectability of Exoplanet Atmospheres

    Hofmann, Ryan; Berta-Thompson, Zachory

    2018-01-01

    Transmission spectroscopy is an effective tool for detecting and characterizing the atmospheres of transiting extrasolar planets. However, the presence of cool spots on a planet’s host star can be a source of uncertainty that is difficult to account for. Cool starspots introduce wavelength-dependent features and noise into the transmission spectrum of an orbiting exoplanet. For sufficiently cool stars, especially M dwarfs, this could cause false detections of water and other species in the planet’s atmosphere. To understand the extent of this problem, we use a combination of PHOENIX model spectra and the starspot simulation code MACULA to simulate the effects of starspots on observed transmission spectra for a wide variety of stars and spot configurations. By comparing the simulated DoTV (Depth of Transit Variation) due to starspots with models of the expected DoTV from exoplanet atmospheres with a given composition, we can estimate the level of effect the starspots have on the detectability of various atmospheres. For example, our results indicate for TRAPPIST-1’s planets that while the large amplitude absorption features from a H/He-rich atmosphere should be easily detectable, a pure water atmosphere would be much harder to distinguish from starspot noise. Consequently, proper characterization of exoplanet atmospheres, especially around cool, active host stars, requires a proper understanding of the star’s spot properties and suitable methods for reducing or removing spot-induced brightness fluctuations as a source of noise.

  4. Color quench correction for low level Cherenkov counting.

    Tsroya, S; Pelled, O; German, U; Marco, R; Katorza, E; Alfassi, Z B

    2009-05-01

    The Cherenkov counting efficiency varies strongly with color quenching, thus correction curves must be used to obtain correct results. The external (152)Eu source of a Quantulus 1220 liquid scintillation counting (LSC) system was used to obtain a quench indicative parameter based on spectra area ratio. A color quench correction curve for aqueous samples containing (90)Sr/(90)Y was prepared. The main advantage of this method over the common spectra indicators is its usefulness also for low level Cherenkov counting.

  5. Efficiency calibration of a liquid scintillation counter for 90Y Cherenkov counting

    Vaca, F.; Garcia-Leon, M.

    1998-01-01

    In this paper a complete and self-consistent method for 90 Sr determination in environmental samples is presented. It is based on the Cherenkov counting of 90 Y with a conventional liquid scintillation counter. The effects of color quenching on the counting efficiency and background are carefully studied. A working curve is presented which allows to quantify the correction in the counting efficiency depending on the color quenching strength. (orig.)

  6. Atmospheric effects on laser eye safety and damage to instrumentation

    Zilberman, Arkadi; Kopeika, Natan S.

    2017-10-01

    Electro-optical sensors as well as unprotected human eyes are extremely sensitive to laser radiation and can be permanently damaged from direct or reflected beams. Laser detector/eye hazard depends on the interaction between the laser beam and the media in which it traverses. The environmental conditions including terrain features, atmospheric particulate and water content, and turbulence, may alter the laser's effect on the detector/eye. It is possible to estimate the performance of an electro-optical system as long as the atmospheric propagation of the laser beam can be adequately modeled. More recent experiments and modeling of atmospheric optics phenomena such as inner scale effect, aperture averaging, atmospheric attenuation in NIR-SWIR, and Cn2 modeling justify an update of previous eye/detector safety modeling. In the present work, the influence of the atmospheric channel on laser safety for personnel and instrumentation is shown on the basis of theoretical and experimental data of laser irradiance statistics for different atmospheric conditions. A method for evaluating the probability of damage and hazard distances associated with the use of laser systems in a turbulent atmosphere operating in the visible and NIR-SWIR portions of the electromagnetic spectrum is presented. It can be used as a performance prediction model for directed energy engagement of ground-based or air-based systems.

  7. Application of Cherenkov light observation to reactor measurements (1). Estimation of reactor power from Cherenkov light intensity

    Yamamoto, Keiichi; Takeuchi, Tomoaki; Kimura, Nobuaki; Ohtsuka, Noriaki; Tsuchiya, Kunihiko; Sano, Tadafumi; Nakajima, Ken; Homma, Ryohei; Kosuge, Fumiaki

    2015-01-01

    Development of the reactor measurement system was started to obtain the real-time in-core nuclear and thermal information, where the quantitative measurement of brightness of Cherenkov light was investigated. The system would be applied as a monitoring system in severe accidents and for the advanced operation management technology in existing LWRs. The calculation and the observation were performed to obtain the quantity of the Cherenkov light caused by the gamma and beta rays emitted from the fuels in the core of Kyoto University Research Reactor. The results indicate that the real-time reactor power can be estimated from the brightness of the Cherenkov light observed by a CCD camera. This method can also work for the estimation of the burn-up of spent fuels at commercial reactors. Since the observed brightness value of the Cherenkov light was influenced by the camera position, the optical observation method should be improved to achieve high accuracy observation. (author)

  8. High-Energy Astrophysics with the High Altitude Water Cherenkov (HAWC) Observatory

    Pretz, John; HAWC Collaboration

    2013-04-01

    The High Altitude Water Cherenkov (HAWC) observatory, under construction at Sierra Negra in the state of Puebla, Mexico, consists of a 22500 square meter area of water Cherenkov detectors: water tanks instrumented with light-sensitive photomultiplier tubes. The experiment is used to detect energetic secondary particles reaching the ground when a 50 GeV to 100 TeV cosmic ray or gamma ray interacts in the atmosphere above the experiment. By timing the arrival of particles on the ground, the direction of the original primary particle may be resolved with an error of between 1.0 (50 GeV) and 0.1 (10 TeV) degrees. Gamma-ray primaries may be distinguished from cosmic ray background by identifying the penetrating particles characteristic of a hadronic particle shower. The instrument is 10% complete and is performing as expected, with 30% of the channels anticipated by the summer of 2013. HAWC will complement existing Imaging Atmospheric Cherenkov Telescopes and space-based gamma-ray telescopes with its extreme high-energy sensitivity and its large field-of-view. The observatory will be used to study particle acceleration in Pulsar Wind Nebulae, Supernova Remnants, Active Galactic Nuclei and Gamma-ray Bursts. Additionally, the instrument can be used to probe dark matter annihilation in halo and sub-halos of the galaxy. We will present the sensitivity of the HAWC instrument in the context of the main science objectives. We will also present the status of the deployment including first data from the instrument and prospects for the future.

  9. CHerenkov detectors In mine PitS (CHIPS) Letter of Intent to FNAL

    Adamson, P. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Austin, J. [Univ. of Minnesota, Duluth, MN (United States); Cao, S. V. [Univ. of Texas, Austin, TX (United States); Coelho, J. A. B. [Tufts Univ., Medford, MA (United States); Davies, G. S. [Iowa State Univ., Ames, IA (United States); Evans, J. J. [Univ. of Manchester (United Kingdom); Guzowski, P. [Univ. of Manchester (United Kingdom); Habig, A. [Univ. of Minnesota, Duluth, MN (United States); Holin, A. [Univ. College London, London (United Kingdom); Huang, J. [Univ. of Texas, Austin, TX (United States); Johnson, R. [Univ. of Cincinnati, OH (United States); St. John, J. [Univ. of Cincinnati, OH (United States); Kreymer, A. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Kordosky, M. [College of William and Mary, Williamsburg, VA (United States); Lang, K. [Univ. of Texas, Austin, TX (United States); Marshak, M. L. [Univ. of Minnesota, Minneapolis, MN (United States); Mehdiyev, R. [Univ. of Texas, Austin, TX (United States); Meier, J. [Univ. of Minnesota, Minneapolis, MN (United States); Miller, W. [Univ. of Minnesota, Minneapolis, MN (United States); Naples, D. [Univ. of Pittsburgh, PA (United States); Nelson, J. K. [College of William and Mary, Williamsburg, VA (United States); Nichol, R. J. [Univ. College London, London (United Kingdom); Patterson, R. B. [California Inst. of Technology (CalTech), Pasadena, CA (United States); Paolone, V. [Univ. of Pittsburgh, PA (United States); Pawloski, G. [Univ. of Minnesota, Minneapolis, MN (United States); Perch, A. [Univ. College London, London (United Kingdom); Pfutzner, M. [Univ. College London, London (United Kingdom); Proga, M. [Univ. of Texas, Austin, TX (United States); Qian, X. [Brookhaven National Lab. (BNL), Upton, NY (United States); Radovic, A. [Univ. College London, London (United Kingdom); Sanchez, M. C. [Iowa State Univ., Ames, IA (United States); Schreiner, S. [Univ. of Minnesota, Minneapolis, MN (United States); Soldner-Rembold, S. [Univ. of Manchester (United Kingdom); Sousa, A. [Univ. of Cincinnati, OH (United States); Thomas, J. [Univ. College London, London (United Kingdom); Vahle, P. [College of William and Mary, Williamsburg, VA (United States); Wendt, C. [Univ. of Wisconsin, Madison, WI (United States); Whitehead, L. H. [Univ. College London, London (United Kingdom); Wojcicki, S. [Stanford Univ., CA (United States)

    2013-12-30

    This Letter of Intent outlines a proposal to build a large, yet cost-effective, 100 kton fiducial mass water Cherenkov detector that will initially run in the NuMI beam line. The CHIPS detector (CHerenkov detector In Mine PitS) will be deployed in a flooded mine pit, removing the necessity and expense of a substantial external structure capable of supporting a large detector mass. There are a number of mine pits in northern Minnesota along the NuMI beam that could be used to deploy such a detector. In particular, the Wentworth Pit 2W is at the ideal off-axis angle to contribute to the measurement of the CP violating phase. The detector is designed so that it can be moved to a mine pit in the LBNE beam line once that becomes operational.

  10. Effect of Store Atmosphere on Consumer Purchase Intention

    Hussain, Riaz; Ali, Mazhar

    2015-01-01

    This paper aimed at identifying the effects of atmosphere on the consumer purchase intention in international retail chain outlets of Karachi, Pakistan. This was the first study, which investigated the collective impact of atmospheric variables at one point in time on purchase intention. This research was causal in nature. A sample of 300 consumers was taken who usually visited these outlets. Data was collected through a well-structured questionnaire and analyzed through regression a...

  11. The effects on the atmosphere of a major nuclear exchange

    Anon.

    1985-01-01

    Most of the earth's population would survive the immediate horrors of a nuclear holocaust, but what long-term climatological changes would affect their ability to secure food and shelter. This sobering report considers the effects of fine dust from ground-level detonations, of smoke from widespread fires, and of chemicals released into the atmosphere. The authors use mathematical models of atmospheric processes and data from natural situations - e.g., volcanic eruptions and arctic haze - to draw their conclusions

  12. Atmospheric effects of a nuclear war

    Birks, J.W.

    1983-01-01

    The subject is discussed under the headings: nuclear war scenario (assumptions of size and place of explosions); fires; urban and forest fires; smoke and soot; darkness; meteorological and climatic effects; photochemical smog; ozone shield depletion; conclusions. (U.K.)

  13. Development of a research reactor power measurement system using Cherenkov radiation

    Salles, Brício M.; Mesquita, Amir Z., E-mail: briciomares@hotmail.com, E-mail: amir@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2017-11-01

    Nuclear research reactors are usually located in open pools, to allow visibility to the core and bluish luminosity of Cherenkov radiation. Usually the thermal power released in these reactors is monitored by chambers that measure the neutron flux, as it is proportional to the power. There are other methods used for power measurement, such as monitoring the core temperature and the energy balance in the heat exchanger. The brightness of Cherenkov's radiation is caused by the emission of visible electromagnetic radiation (in the blue band) by charged particles that pass through an insulating medium (water in nuclear research reactors) at a speed higher than that of light in this medium. This effect was characterized by Pavel Cherenkov, which earned him the Nobel Prize for Physics in 1958. The project's objective is to develop an innovative and alternative method for monitoring the power of nuclear research reactors. It will be performed by analyzing and monitoring the intensity of luminosity generated by Cherenkov radiation in the reactor core. This method will be valid for powers up to 250 kW, since above that value the luminosity saturates, as determined by previous studies. The reactor that will be used to test the method is the TRIGA, located at Nuclear Technology Development Center (CDTN), which currently has a maximum operating power of 250 kW. This project complies with International Atomic Energy Agency (IAEA) recommendations on reactor safety. It will give more redundancy and diversification in this measure and will not interfere with its operation. (author)

  14. Noise simulation and rejection for the DELPHI Barrel Ring Imaging Cherenkov detector

    Bloch, D.

    1996-01-01

    The performance of Ring Imaging Cherenkov detectors is severely affected by the background noise due to the necessity of detecting single electrons. Furthermore, in the majority of the existing RICHs, the charged particles to be identified also cross the sensitive area of the apparatus thus creating secondary effects. The different noise sources and the background behaviour have been studied for the DELPHI RICH in order to efficiently clean the Cherenkov rings from the background while preserving the majority of the signal. Particular care has been taken to optimize the parameters of the Cherenkov image ''cleaning'' for the gas and the liquid radiators separately. For Z 0 hadronic decays 70% background rejection has been achieved, whilst 85% of the signal has been retained. This paper also presents a simulation of the noise producing mechanisms where ionization electrons, δ-rays, feedback electrons created during avalanches and electronic noise are modeled according to the measured parameters. Good agreement between data and simulation has been achieved. (orig.)

  15. Atmosphere pollutants-their health and environmental effects

    Issa, Ali Sasi; Ibsaim, Rajab A.

    2006-01-01

    The conducted studies, continuous monitoring and measuring of the atmosphere pollution surrounding the world cities for a decade in the last century demonstrated increased rates of some pollutants, often exceeded the levels which are considered to be safe for health. Most of the dangerous pollutants in the atmosphere are suspended particles, sulfur oxides, nitrogen oxides, ozone troposphere and lead, these are the main responsible pollutant in contaminating the atmosphere leading to increase of death percentage in the major cities. For a duration of nearly a century, atmosphere pollution accidents in cities like London approved that inhaling contaminated air is dangerous and deadly sometimes. In 1880 2200 person from London inhabitants have died when coal smoke with heating and industrial gases have been accumulated to form a toxic smog of sulfur oxide gas and suspended particles in the atmosphere of the city. In this paper we discuss type of atmosphere pollutants and their health and environmental effects on human being, creatures and earth and ways of eliminating that.(Author)

  16. CLASSiC: Cherenkov light detection with silicon carbide

    Adriani, Oscar [Physics Dept., University of Florence, Via Sansone 1, 50019, Sesto Fiorentino (Italy); INFN dep. of Florence, Via Bruno Rossi 1, 50019 Sesto Fiorentino (Italy); Albergo, Sebastiano [Physics Dept., University of Catania, Via Santa Sofia 64, 95123 Catania (Italy); INFN dep. of Catania, Via Santa Sofia 64, 95123 Catania (Italy); D' Alessandro, Raffaello [Physics Dept., University of Florence, Via Sansone 1, 50019, Sesto Fiorentino (Italy); INFN dep. of Florence, Via Bruno Rossi 1, 50019 Sesto Fiorentino (Italy); Lenzi, Piergiulio [INFN dep. of Florence, Via Bruno Rossi 1, 50019 Sesto Fiorentino (Italy); Sciuto, Antonella [CNR-IMM, VIII Strada 5, Zona Industriale, Catania (Italy); INFN dep. of Catania, Via Santa Sofia 64, 95123 Catania (Italy); Starodubtsev, Oleksandr [INFN dep. of Florence, Via Bruno Rossi 1, 50019 Sesto Fiorentino (Italy); Tricomi, Alessia [Physics Dept., University of Catania, Via Santa Sofia 64, 95123 Catania (Italy); INFN dep. of Catania, Via Santa Sofia 64, 95123 Catania (Italy)

    2017-02-11

    We present the CLASSiC R&D for the development of a silicon carbide (SiC) based avalanche photodiode for the detection of Cherenkov light. SiC is a wide-bandgap semiconductor material, which can be used to make photodetectors that are insensitive to visible light. A SiC based light detection device has a peak sensitivity in the deep UV, making it ideal for Cherenkov light. Moreover, the visible blindness allows such a device to disentangle Cherenkov light and scintillation light in all those materials that scintillate above 400 nm. Within CLASSiC, we aim at developing a device with single photon sensitivity, having in mind two main applications. One is the use of the SiC APD in a new generation ToF PET scanner concept, using the Cherenov light emitted by the electrons following 511 keV gamma ray absorption as a time-stamp. Cherenkov is intrinsically faster than scintillation and could provide an unprecedentedly precise time-stamp. The second application concerns the use of SiC APD in a dual readout crystal based hadronic calorimeter, where the Cherenkov component is used to measure the electromagnetic fraction on an event by event basis. We will report on our progress towards the realization of the SiC APD devices, the strategies that are being pursued toward the realization of these devices and the preliminary results on prototypes in terms of spectral response, quantum efficiency, noise figures and multiplication.

  17. The first GCT camera for the Cherenkov Telescope Array

    De Franco, A.; Allan, D.; Armstrong, T.; Ashton, T.; Balzer, A.; Berge, D.; Bose, R.; Brown, A.M.; Buckley, J.; Chadwick, P.M.; Cooke, P.; Cotter, G.; Daniel, M.K.; Funk, S.; Greenshaw, T.; Hinton, J.; Kraus, M.; Lapington, J.; Molyneux, P.; Moore, P.; Nolan, S.; Okumura, A.; Ross, D.; Rulten, C.; Schmoll, J.; Schoorlemmer, H.; Stephan, M.; Sutcliffe, P.; Tajima, H.; Thornhill, J.; Tibaldo, L.; Varner, G.; Watson, J.; Zink, A.

    2015-01-01

    The Gamma Cherenkov Telescope (GCT) is proposed to be part of the Small Size Telescope (SST) array of the Cherenkov Telescope Array (CTA). The GCT dual-mirror optical design allows the use of a compact camera of diameter roughly 0.4 m. The curved focal plane is equipped with 2048 pixels of ~0.2{\\deg} angular size, resulting in a field of view of ~9{\\deg}. The GCT camera is designed to record the flashes of Cherenkov light from electromagnetic cascades, which last only a few tens of nanoseconds. Modules based on custom ASICs provide the required fast electronics, facilitating sampling and digitisation as well as first level of triggering. The first GCT camera prototype is currently being commissioned in the UK. On-telescope tests are planned later this year. Here we give a detailed description of the camera prototype and present recent progress with testing and commissioning.

  18. Cherenkov Radiation Control via Self-accelerating Wave-packets.

    Hu, Yi; Li, Zhili; Wetzel, Benjamin; Morandotti, Roberto; Chen, Zhigang; Xu, Jingjun

    2017-08-18

    Cherenkov radiation is a ubiquitous phenomenon in nature. It describes electromagnetic radiation from a charged particle moving in a medium with a uniform velocity larger than the phase velocity of light in the same medium. Such a picture is typically adopted in the investigation of traditional Cherenkov radiation as well as its counterparts in different branches of physics, including nonlinear optics, spintronics and plasmonics. In these cases, the radiation emitted spreads along a "cone", making it impractical for most applications. Here, we employ a self-accelerating optical pump wave-packet to demonstrate controlled shaping of one type of generalized Cherenkov radiation - dispersive waves in optical fibers. We show that, by tuning the parameters of the wave-packet, the emitted waves can be judiciously compressed and focused at desired locations, paving the way to such control in any physical system.

  19. The Cherenkov correlated timing detector: beam test results from quartz and acrylic bars

    Kichimi, H.; Sugaya, Y.; Yamaguchi, H.; Yoshimura, Y.; Kanda, S.; Olsen, S.; Ueno, K.; Varner, G.; Bergfeld, T.; Bialek, J.; Lorenc, J.; Palmer, M.; Rudnick, G.; Selen, M.; Auran, T.; Boyer, V.; Honscheid, K.; Tamura, N.; Yoshimura, K.; Lu, C.; Marlow, D.; Mindas, C.; Prebys, E.; Asai, M.; Kimura, A.; Hayashi, S.

    1996-01-01

    Several prototypes of a Cherenkov correlated timing (CCT) detector have been tested at the KEK-PS test beam line. We describe the results for Cherenkov light yields and timing characteristics from quartz and acrylic bar prototypes. A Cherenkov angle resolution is found to be 15 mrad at a propagation distance of 100 cm with a 2 cm thick quartz bar prototype. (orig.)

  20. Effect of 1-methylcyclopropene and modified atmosphere packaging ...

    Some sweet peppers (Capsicum annuum L.) are chilling sensitive and can develop injury when stored at temperatures less than 7°C. This study was conducted to investigate the effect of 1-methylcyclopropene (1-MCP) (650 ppb) and modified atmosphere packaging (MAP) on chilling injuries (CI) of sweet pepper during 30 ...

  1. Refraction effects of atmospheric inhomogeneities along the path

    Jong, A.N. de

    2004-01-01

    A critical moment in the detection process of incoming targets at sea occurs, when a target just appears above the horizon. The corresponding light rays cross the atmospheric boundary layer, in which the presence of temperature gradients may result in optical distortion effects. This geometric

  2. Effect of noble gases on an atmospheric greenhouse /Titan/.

    Cess, R.; Owen, T.

    1973-01-01

    Several models for the atmosphere of Titan have been investigated, taking into account various combinations of neon and argon. The investigation shows that the addition of large amounts of Ne and/or Ar will substantially reduce the hydrogen abundance required for a given greenhouse effect. The fact that a large amount of neon should be present if the atmosphere is a relic of the solar nebula is an especially attractive feature of the models, because it is hard to justify appropriate abundances of other enhancing agents.

  3. The effects on the atmosphere of a major nuclear exchange

    1985-01-01

    Most of the earth's population would survive the immediate horrors of a nuclear holocaust, but what long-term climatological changes would affect their ability to secure food and shelter. This sobering report considers the effects of fine dust from ground-level detonations, of smoke from widespread fires, and of chemicals released into the atmosphere. The authors use mathematical models of atmospheric processes and data from natural situations - e.g., volcanic eruptions and arctic haze - to draw their conclusions.

  4. Feasibility study of the water Cherenkov detector as a D-T fusion power monitor in the system using neutron activation of flowing water. First experimental phase

    Verzilov, Yury M.; Ochiai, Kentaro; Nishitani, Takeo

    2003-09-01

    The technique of monitoring D-T neutrons using water flow is based on the reaction of the 16 O(n, p) 16 N. In order to significantly improve the D-T neutron monitoring system in the ITER reactor in comparison with the system that uses a γ-ray scintillation detector, a new approach was proposed. The basic idea of this approach is to utilize the Cherenkov light, produced by energetic β-particles from 16 N in water near the first wall of the fusion reactor, and then deliver the light by the optical fiber to the remote light detector. The proof of the principle experiment is divided into two phases. The main idea of the first experimental phase is to examine Cherenkov light measurements using a remotely located water and light detector. During the second phase the water radiator will be placed next to the neutron source, then the Cherenkov light will be transferred by an optical fiber to the remotely located light detector. For the purpose of the first experimental phase, a water Cherenkov detector was installed in the shielded measurement room. A closed water loop, with circulating water, was used to transport 16 N from the D-T source to the Cherenkov detector. The experiment was carried out at FNS/JAERI, with the accelerator set to a direct current mode, the source neutron yield around 2 x 10 11 n/s, and the water flowage approximately 2 m/s. The registered Cherenkov signal was identified as the light produced by β-particles from 16 N using the time decay and the energy spectra data. According to the present study, the water Cherenkov detector is very effective for measurements of the 16 N activity, due to high counting efficiency, absence of the scintillation detector and simplicity of the method. (author)

  5. New air Cherenkov light detectors to study mass composition of cosmic rays with energies above knee region

    Tsunesada, Yoshiki, E-mail: tsunesada@cr.phys.titech.ac.jp [Graduate School of Science and Engineering, Tokyo Institute of Technology, Meguro, Tokyo 152-8550 Japan (Japan); Katsuya, Ryoichi, E-mail: katsuya@cr.phys.titech.ac.jp [Graduate School of Science and Engineering, Tokyo Institute of Technology, Meguro, Tokyo 152-8550 Japan (Japan); Mitsumori, Yu; Nakayama, Keisuke; Kakimoto, Fumio; Tokuno, Hisao [Graduate School of Science and Engineering, Tokyo Institute of Technology, Meguro, Tokyo 152-8550 Japan (Japan); Tajima, Norio [RIKEN, Wako, Saitama 351-0198 (Japan); Miranda, Pedro; Salinas, Juan; Tavera, Wilfredo [Instituto de Investigaciones Físicas, Universidad Mayor de San Andrés, La Paz (Bolivia, Plurinational State of)

    2014-11-01

    We have installed a hybrid detection system for air showers generated by cosmic rays with energies greater than 3×10{sup 15}eV at Mount Chacaltaya (5200 m above the sea level), in order to study the mass composition of cosmic rays above the knee region. This detection system comprises an air shower array with 49 scintillation counters in an area of 500 m×650 m, and seven new Cherenkov light detectors installed in a radial direction from the center of the air shower array with a separation of 50 m. It is known that the longitudinal development of a particle cascade in the atmosphere strongly depends on the type of the primary nucleus, and an air shower initiated by a heavier nucleus develops faster than that by a lighter primary of the same energy, because of the differences in the interaction cross-section and the energy per nucleon. This can be measured by detecting the Cherenkov radiation emitted from charged particles in air showers at higher altitudes. In this paper we describe the design and performance of our new non-imaging Cherenkov light detectors at Mount Chacaltaya that are operated in conjunction with the air shower array. The arrival directions and energies of air showers are determined by the shower array, and information about the primary masses is obtained from the Cherenkov light data including the time profiles and lateral distributions. The detector consists of photomultiplier tube (PMT), high-speed ADCs, other control modules, and data storage device. The Cherenkov light signals from an air shower are typically 10–100 ns long, and the waveforms are digitized with a sampling frequency of 1 GHz and recorded in situ without long-distance analog signal transfers. All the Cherenkov light detectors record their time-series data by receiving a triggering signal transmitted from the trigger module of the air shower array, which is fired by a coincidence of shower signals in four neighboring scintillation counters. The optical characteristics of the

  6. Corrosion in marine atmospheres. Effect of distance from the coast

    Chico, B.; Otero, E.; Morcillos, M.; Mariaca, L.

    1998-01-01

    In marine atmospheres the deposition of saline particles on the surface of metals intensifies the metallic corrosion process. However, quantitative information about the effect of atmospheric salinity on metallic corrosion is very scarce. This paper reports the relationship between salinity and metallic corrosion, where a clear linear relation (r=0.97) has been found for a broad interval of salinities (4-500 mg Cl''-/m''2.d), as well as the relationship between salinity (or metallic corrosion) and distance from the coast. A hyperbolic function seems to be established both variables; there is an exponential drop in salinity (or corrosion) as shoreline distance increases tending towards and asymptotic value. The study has been based on information obtained from field research conducted at a marine atmosphere in Tarragona (Spain) and data compiled from the literature. (Author) 14 refs

  7. High speed decision electronics combined to a beam Cherenkov counter

    Sghaier, H.

    1993-01-01

    The Hypolit detector for identification of particles in high energy physics using the Cherenkov radiation, is based on an intensifier tube coupled to photomultipliers via a fiber-optic matrix. Cherenkov photons are focused into a ring; particle identification consists in calculating the ring radius. A fast and high level electronic system is associated to Hypolit. Besides deriving the radius, it allows a background rejection and achieves a momentum correction. This on line tagging contributes to build the WA89 trigger. Tuning is controlled with a micro-computer which makes the access to the heart of the system friendly-user

  8. Light-weight spherical mirrors for Cherenkov detectors

    Cisbani, E; Colilli, S; Crateri, R; Cusanno, F; De Leo, R; Fratoni, R; Frullani, S; Garibaldi, F; Giuliani, F; Gricia, M; Iodice, M; Iommi, R; Lagamba, L; Lucentini, M; Mostarda, A; Nappi, E; Pierangeli, L; Santavenere, F; Urciuoli, G M; Vernin, P

    2003-01-01

    Light-weight spherical mirrors have been appositely designed and built for the gas threshold Cherenkov detectors of the two Hall A spectrometers. The mirrors are made of a 1 mm thick aluminized plexiglass sheet, reinforced by a rigid backing consisting of a phenolic honeycomb sandwiched between two carbon fiber mats epoxy glued. The produced mirrors have a thickness equivalent to 0.55% of radiation length, and an optical slope error of about 5.5 mrad. These characteristics make these mirrors suitable for the implementation in Cherenkov threshold detectors. Ways to improve the mirror features are also discussed in view of their possible employment in RICH detectors.

  9. Theoretical study of Cherenkov radiation emission in anisotropic uniaxial crystals

    Delbart, A; Derre, J

    1996-04-01

    A theoretical review of the Cherenkov radiation emission in uniaxial crystals is presented. The formalism of C. Muzicar in terms of energetic properties of the emitted waves are corrected. This formalism is used to simulate the Cherenkov radiation emission in a strongly birefringent sodium nitrate crystal (NaNO{sub 3}) and to investigate the consequences of the slight anisotropy of sapphire (Al{sub 2}O{sub 3}) on the design of the Optical Trigger. (author). 12 refs. Submitted to Physical Review, D (US).

  10. Differential cardiac effects in rats exposed to atmospheric ...

    The results of this study demonstrate that atmospheric smog generated from both isoprene and toluene cause cardiac effects in rats. In addition, it appears that smog from toluene is more toxic in terms of cardiac arrhythmogenicity. Smog, which is a complex mixture of particulate matter and gaseous irritants (ozone, sulfur dioxide, reactive aldehydes), as well as components which react with sunlight to form secondary pollutants, has recently been linked to increased risk of adverse cardiac responses. The components, and therefore health effects, of atmospheric smog are determined by the fuel used to generate them. In this study we examined the difference between isoprene- and toluene-generated smog in causing cardiac effects in rats and hypothesized that both atmospheres would cause cardiac electrical and functional changes in rats. Male Wistar-Kyoto rats were exposed to either atmospheric smog generated by the USEPA’s mobile reaction chamber using either isoprene or toluene, or filtered air for four hours. One day later, rats were anesthetized and left ventricular functional responses to dobutamine were measured using a Millar probe and arrhythmia sensitivity to aconitine. Baseline left ventricular pressure (LVP) was lower in toluene-exposed animals but not isoprene when compared to air. Increases in LVP with increasing doses of dobutamine were impaired only in toluene-exposed rats. Both isoprene and toluene impaired the rate of ventri

  11. Calculation and simulation of atmospheric refraction effects in maritime environments

    Dion, Denis, Jr.; Gardenal, Lionel; Lahaie, P.; Forand, J. Luc

    2001-01-01

    Near the sea surface, atmospheric refraction and turbulence affect both IR transmission and image quality. This produces an impact on both the detection and classification/identification of targets. With the financial participation of the U.S. Office of Naval Research (ONR), Canada's Defence Research Establishment Valcartier (DREV) is developing PRIME (Propagation Resources In the Maritime Environment), a computer model aimed at describing the overall atmospheric effects on IR imagery systems in the marine surface layer. PRIME can be used as a complement to MODTRAN to compute the effective transmittance in the marine surface layer, taking into account the lens effects caused by refraction. It also provides information on image degradation caused by both refraction and turbulence. This paper reviews the refraction phenomena that take place in the surface layer and discusses their effects on target detection and identification. We then show how PRIME can benefit detection studies and image degradation simulations.

  12. Effects on the atmosphere of a major nuclear exchange

    1985-01-01

    The Committee on the Atmospheric Effects of Nuclear Explosions addressed the following charge: (1) determine the manner in which the atmosphere of the earth would be modified by a major exchange of nuclear weapons and, insofar as the current state of knowledge and understanding permits, give a quantitative description of the more important of the changes; and (2) recommend research and exploratory work appropriate to a better understanding of the question. Recent calculations by different investigators suggest that the climatic effects from a major nuclear exchange could be large in scale. Although there are enormous uncertainties involved in the calculations, the committee believes that long-term climatic effects with severe implications for the biosphere could occur, and these effects should be included in any analysis of the consequences of nuclear war. The estimates are necessarily rough and can only be used as a general indication of the seriousness of what might occur

  13. Simulated gamma-ray pulse profile of the Crab pulsar with the Cherenkov Telescope Array

    Burtovoi, A.; Zampieri, L.

    2016-07-01

    We present simulations of the very high energy (VHE) gamma-ray light curve of the Crab pulsar as observed by the Cherenkov Telescope Array (CTA). The CTA pulse profile of the Crab pulsar is simulated with the specific goal of determining the accuracy of the position of the interpulse. We fit the pulse shape obtained by the Major Atmospheric Gamma-Ray Imaging Cherenkov (MAGIC) telescope with a three-Gaussian template and rescale it to account for the different CTA instrumental and observational configurations. Simulations are performed for different configurations of CTA and for the ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) mini-array. The northern CTA configuration will provide an improvement of a factor of ˜3 in accuracy with an observing time comparable to that of MAGIC (73 h). Unless the VHE spectrum above 1 TeV behaves differently from what we presently know, unreasonably long observing times are required for a significant detection of the pulsations of the Crab pulsar with the high-energy-range sub-arrays. We also found that an independent VHE timing analysis is feasible with Large Size Telescopes. CTA will provide a significant improvement in determining the VHE pulse shape parameters necessary to constrain theoretical models of the gamma-ray emission of the Crab pulsar. One of such parameters is the shift in phase between peaks in the pulse profile at VHE and in other energy bands that, if detected, may point to different locations of the emission regions.

  14. On the possiblity of using vertically pointing Central Laser Facilities to calibrate the Cherenkov Telescope Array

    Gaug, Markus

    2014-01-01

    A Central Laser Facility is a system composed of a laser placed at a certain distance from a light-detector array, emitting fast light pulses, typically in the vertical direction, with the aim to calibrate that array. During calibration runs, all detectors are pointed towards the same portion of the laser beam at a given altitude. Central Laser Facilities are used for various currently operating ultra-high-energy cosmic ray and imaging atmospheric Cherenkov telescope arrays. In view of the future Cherenkov Telescope Array, a similar device could provide a fast calibration of the whole installation at different wavelengths. The relative precision (i.e. each individual telescope with respect to the rest of the array is expected) to be better than 5%, while an absolute calibration should reach a precisions of 6–11%, if certain design requirements are met. Additionally, a preciser monitoring of the sensitivity of each telescope can be made on time-scales of days to years

  15. Prototype of a production system for Cherenkov Telescope Array with DIRAC

    Arrabito, L; Haupt, A; Graciani Diaz, R; Stagni, F; Tsaregorodtsev, A

    2015-01-01

    The Cherenkov Telescope Array (CTA) — an array of many tens of Imaging Atmospheric Cherenkov Telescopes deployed on an unprecedented scale — is the next generation instrument in the field of very high energy gamma-ray astronomy. CTA will operate as an open observatory providing data products to the scientific community. An average data stream of about 10 GB/s for about 1000 hours of observation per year, thus producing several PB/year, is expected. Large CPU time is required for data-processing as well for massive Monte Carlo simulations needed for detector calibration purposes. The current CTA computing model is based on a distributed infrastructure for the archive and the data off-line processing. In order to manage the off-line data-processing in a distributed environment, CTA has evaluated the DIRAC (Distributed Infrastructure with Remote Agent Control) system, which is a general framework for the management of tasks over distributed heterogeneous computing environments. In particular, a production sy...

  16. The response of wavelength shifting panels in large water Cherenkov systems

    Bakich, A.M.; Peak, L.S.

    1986-01-01

    This paper describes a series of tests performed with a panel Bicron wavelength shifting acrylic plastic (BC-480) coupled to an EMI 9623B photomultiplier tube. The aim was to effectively increase the cathode coverage and its sensitivity to incident Cherenkov radiation, so that such a system could be employed in a solar neutrino detector. Measurements of the uniformity and effective efficiency of the system have been made and compared with the results of various simulation runs. The effects of side mirrors, back reflector, water interface and possible shaping of the panel to enhance its response are also assessed. (orig.)

  17. The ASTRI SST-2M prototype for the Cherenkov Telescope Array: prototype technologies goals and strategies for the future SST

    Marchiori, Gianpietro; Busatta, Andrea; Giacomel, Stefano; Folla, Ivan; Valsecchi, Marco; Canestrari, Rodolfo; Bonnoli, Giacomo; Cascone, Enrico; Conconi, Paolo; Fiorini, Mauro; Giro, Enrico; La Palombara, Nicola; Pareschi, Giovanni; Perri, Luca; Rodeghiero, Gabriele; Sironi, Giorgia; Stringhetti, Luca; Toso, Giorgio; Tosti, Gino; Pellicciari, Carlo

    2014-07-01

    The Cherenkov Telescope Array (CTA) observatory will represent the next generation of Imaging Atmospheric Cherenkov Telescope. Using a combination of large-, medium-, and small-scale telescopes (LST, MST, SST, respectively), it will explore the Very High Energy domain from a few tens of GeVup to about few hundreds of TeV with unprecedented sensitivity, angular resolution and imaging quality. In this framework, the Italian ASTRI program, led by the Italian National Institute of Astrophysics (INAF) developed a 4-meter class telescope, which will adopt an aplanatic, wide-field, double-reflection optical layout in a Schwarzschild- Couder configuration. Within this program INAF assigned to the consortium between Galbiati Group and EIE Group the construction, assembly and tests activities of the prototype named ASTRI SST-2M. On the basis of the lesson learnt from the prototype, other telescopes will be produced, starting from a re-design phase, in order to optimize performances and the overall costs and production schedule for the CTA-SST telescope. This paper will firstly give an overview of the concept for the SST prototype mount structure. In this contest, the technologies adopted for the design, manufacturing and tests of the entire system will be presented. Moreover, a specific focus on the challenges of the prototype and the strategies associated with it will be provided, in order to outline the near future performance goals for this type of Cherenkov telescopes employed for Gamma ray science.

  18. Information and Communications Technology (ICT) Infrastructure for the ASTRI SST-2M telescope prototype for the Cherenkov Telescope Array

    Gianotti, F.; Tacchini, A.; Leto, G.; Martinetti, E.; Bruno, P.; Bellassai, G.; Conforti, V.; Gallozzi, S.; Mastropietro, M.; Tanci, C.; Malaguti, G.; Trifoglio, M.

    2016-08-01

    The Cherenkov Telescope Array (CTA) represents the next generation of ground-based observatories for very high energy gamma-ray astronomy. The CTA will consist of two arrays at two different sites, one in the northern and one in the southern hemisphere. The current CTA design foresees, in the southern site, the installation of many tens of imaging atmospheric Cherenkov telescopes of three different classes, namely large, medium and small, so defined in relation to their mirror area; the northern hemisphere array would consist of few tens of the two larger telescope types. The Italian National Institute for Astrophysics (INAF) is developing the Cherenkov Small Size Telescope ASTRI SST- 2M end-to-end prototype telescope within the framework of the International Cherenkov Telescope Array (CTA) project. The ASTRI prototype has been installed at the INAF observing station located in Serra La Nave on Mt. Etna, Italy. Furthermore a mini-array, composed of nine of ASTRI telescopes, has been proposed to be installed at the Southern CTA site. Among the several different infrastructures belonging the ASTRI project, the Information and Communication Technology (ICT) equipment is dedicated to operations of computing and data storage, as well as the control of the entire telescope, and it is designed to achieve the maximum efficiency for all performance requirements. Thus a complete and stand-alone computer centre has been designed and implemented. The goal is to obtain optimal ICT equipment, with an adequate level of redundancy, that might be scaled up for the ASTRI mini-array, taking into account the necessary control, monitor and alarm system requirements. In this contribution we present the ICT equipment currently installed at the Serra La Nave observing station where the ASTRI SST-2M prototype will be operated. The computer centre and the control room are described with particular emphasis on the Local Area Network scheme, the computing and data storage system, and the

  19. The effects of solar particle events on the middle atmosphere

    Jackman, C.H.; Douglass, A.R.; Meade, P.E.

    1989-01-01

    Solar particle events (SPEs) have been investigated since the late 1960's for possible effects on the middle atmosphere. Solar protons from SPEs produce ionizations, dissociations, dissociative ionizations, and excitations in the middle atmosphere. The production of HO(x) and NO(x) and their subsequent effects on ozone can also be computed using energy deposition and photochemical models. The effects of SPE-produced HO(x) species on the odd nitrogen abundance of the middle atmosphere as well as the SPE-produced long term effects on ozone. Model computations indicate fairly good agreement with ozone data for the SPE-induced ozone depletion caused by NO(y) species connected with the August 1972 SPE. The model computations indicate that NO(y) will not be substantially changed over a solar cycle by SPEs. The changes are mainly at high latitudes and are on time scales of several months, after which the NO(y) drifts back to its ambient levels

  20. Measuring the greenhouse effect and radiative forcing through the atmosphere

    Philipona, Rolf; Kräuchi, Andreas; Brocard, Emmanuel

    2013-04-01

    In spite of a large body of existing measurements of incoming shortwave solar radiation and outgoing longwave terrestrial radiation at the Earth's surface and at the top of the atmosphere, there are few observations documenting how radiation profiles change through the atmosphere - information that is necessary to fully quantify the greenhouse effect of the Earth's atmosphere. Using weather balloons and specific radiometer equipped radiosondes, we continuously measured shortwave and longwave radiation fluxes from the surface of the Earth up to altitudes of 35 kilometers in the upper stratosphere. Comparing radiation profiles from night measurements with different amounts of water vapor, we show evidence of large greenhouse forcing. We show, that under cloud free conditions, water vapor increases with Clausius-Clapeyron ( 7% / K), and longwave downward radiation at the surface increases by 8 Watts per square meter per Kelvin. The longwave net radiation however, shows a positive increase (downward) of 2.4 Watts per square meter and Kelvin at the surface, which decreases with height and shows a similar but negative increase (upward) at the tropopause. Hence, increased tropospheric water vapor increases longwave net radiation towards the ground and towards space, and produces a heating of 0.42 Kelvin per Watt per square meter at the surface. References: Philipona et al., 2012: Solar and thermal radiation profiles and radiative forcing measured through the atmosphere. Geophys. Res. Lett., 39, L13806, doi: 10.1029/2012GL052087.

  1. Catalytic and atmospheric effects on microwave pyrolysis of corn stover.

    Huang, Yu-Fong; Kuan, Wen-Hui; Chang, Chi-Cheng; Tzou, Yu-Min

    2013-03-01

    Corn stover, which is one of the most abundant agricultural residues around the world, could be converted into valuable biofuels and bio based products by means of microwave pyrolysis. After the reaction at the microwave power level of 500W for the processing time of 30min, the reaction performance under N2 atmosphere was generally better than under CO2 atmosphere. This may be due to the better heat absorbability of CO2 molecules to reduce the heat for stover pyrolysis. Most of the metal-oxide catalysts effectively increased the maximum temperature and mass reduction ratio but lowered the calorific values of solid residues. The gas most produced was CO under N2 atmosphere but CO2 under CO2 atmosphere. Catalyst addition lowered the formation of PAHs and thus made liquid products less toxic. More liquid products and less gas products were generated when using the catalysts possibly due to the existence of the Fischer-Tropsch synthesis. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Extension of Cherenkov Light LDF Parametrization for Tunka and ...

    2016-01-27

    Jan 27, 2016 ... The Cherenkov light Lateral Distribution Function (LDF) from particles initiated Extensive Air Showers (EAS) with ultrahigh energies ( > 1016 eV) was simulated using CORSIKA program for configuration of Tunka and Yakutsk EAS arrays for different primary particles (p, Fe and O2) and different zenith ...

  3. Muon-track studies in a water Cherenkov detector

    Etchegoyen, A. [Departamento de Fisica, Comision Nacional de Energia Atomica, Avenida del Libertador 8250 (1429) Buenos Aires (Argentina)]. E-mail: etchegoy@tandar.cnea.gov.ar; Bauleo, P. [Departamento de Fisica, Comision Nacional de Energia Atomica, Avenida del Libertador 8250 (1429) Buenos Aires (Argentina); Bertou, X. [Enrico Fermfi Institute, University of Chicago, 5640 S. Ellis, Chicago, IL 60637 (United States); Bonifazi, C.B. [Departamento de Fisica, Comision Nacional de Energia Atomica, Avenida del Libertador 8250 (1429) Buenos Aires (Argentina); Filevich, A. [Departamento de Fisica, Comision Nacional de Energia Atomica, Avenida del Libertador 8250 (1429) Buenos Aires (Argentina); Medina, M.C. [Departamento de Fisica, Comision Nacional de Energia Atomica, Avenida del Libertador 8250 (1429) Buenos Aires (Argentina); Melo, D.G. [Departamento de Fisica, Comision Nacional de Energia Atomica, Avenida del Libertador 8250 (1429) Buenos Aires (Argentina); Rovero, A.C. [Instituto de Astronomia y Fisica del Espacio, CC 67, Suc. 28 (1428) Buenos Aires (Argentina); Supanitsky, A.D. [Departamento de Fisica, Comision Nacional de Energia Atomica, Avenida del Libertador 8250 (1429) Buenos Aires (Argentina); Tamashiro, A. [Departamento de Fisica, Comision Nacional de Energia Atomica, Avenida del Libertador 8250 (1429) Buenos Aires (Argentina)

    2005-06-21

    Background muons may be used in cosmic ray experiments to understand the response of a given detector system and to lay the basis for the further theoretical and simulation work needed in the analysis of air showers. Experiments were performed using a water Cherenkov detector at the Tandar Laboratory. Monte Carlo and semi-analytical calculations were compared to the data.

  4. First observation of Cherenkov ring images using hybrid photon detectors

    Albrecht, E.; Wilkinson, G.; Bibby, J.H.; Giles, R.; Harnew, N.; Smale, N.; Brook, N.H.; Halley, A.W.; O'Shea, V.; French, M.; Gibson, V.; Wotton, S.A.; Schomaker, R.

    1998-01-01

    A ring-imaging Cherenkov detector, equipped with hybrid photon detectors, has been operated in a charged-particle beam. Focussed ring images from various particle types were detected using silica aerogel, air and C 4 F 10 gas radiators. The detector, a prototype for the CERN LHC-B experiment, is described and first observations are reported. (orig.)

  5. First observation of Cherenkov ring images using hybrid photon detectors

    Albrecht, E.; Wilkinson, G. [European Organization for Nuclear Research, Geneva (Switzerland). Div. Particle Physics Experiments; Barber, G.; Duane, A.; John, M.; Miller, D.G.; Websdale, D. [Imperial College of Science Technology and Medicine, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom); Bibby, J.H.; Giles, R.; Harnew, N.; Smale, N. [University of Oxford, Department of Nuclear Physics, Keble Road, Oxford OX1 3RH (United Kingdom); Brook, N.H.; Halley, A.W.; O`Shea, V. [University of Glasgow, Department of Physics, Glasgow G12 8QQ (United Kingdom); French, M. [Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom); Gibson, V.; Wotton, S.A. [University of Cambridge, Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE (United Kingdom); Schomaker, R. [Delft Electronic Products BV, 9300 AB Roden (Netherlands)

    1998-07-11

    A ring-imaging Cherenkov detector, equipped with hybrid photon detectors, has been operated in a charged-particle beam. Focussed ring images from various particle types were detected using silica aerogel, air and C{sub 4}F{sub 10} gas radiators. The detector, a prototype for the CERN LHC-B experiment, is described and first observations are reported. (orig.)

  6. Modeling Effectivity of Atmospheric Advection-Diffusion Processes

    Brojewski, R.

    1999-01-01

    Some methods of solving the advection-diffusion problems useful in the field of atmospheric physics are presented and analyzed in the paper. The most effective one ( from the point of view of computer applications) was chosen. This is the method of problem decomposition with respect to the directions followed by secondary decomposition of the problem with respect to the physical phenomena. Introducing some corrections to the classical numerical methods of solving the problems, a hybrid composed of the finite element method for the advection problems and the implicit method with averaging for the diffusion processes was achieved. This hybrid method and application of the corrections produces a very effective means for solving the problems of substance transportation in atmosphere. (author)

  7. Cherenkov luminescence measurements with digital silicon photomultipliers: a feasibility study

    Ciarrocchi, Esther; Belcari, Nicola; Guerra, Alberto Del [Department of Physics, University of Pisa, Pisa (Italy); INFN, section of Pisa, Pisa (Italy); Cherry, Simon R. [Department of Biomedical Engineering, University of California, Davis, CA (United States); Lehnert, Adrienne; Hunter, William C. J.; McDougald, Wendy; Miyaoka, Robert S.; Kinahan, Paul E. [Department of Radiology, University of Washington, Seattle, WA (United States)

    2015-11-16

    A feasibility study was done to assess the capability of digital silicon photomultipliers to measure the Cherenkov luminescence emitted by a β source. Cherenkov luminescence imaging (CLI) is possible with a charge coupled device (CCD) based technology, but a stand-alone technique for quantitative activity measurements based on Cherenkov luminescence has not yet been developed. Silicon photomultipliers (SiPMs) are photon counting devices with a fast impulse response and can potentially be used to quantify β-emitting radiotracer distributions by CLI. In this study, a Philips digital photon counting (PDPC) silicon photomultiplier detector was evaluated for measuring Cherenkov luminescence. The PDPC detector is a matrix of avalanche photodiodes, which were read one at a time in a dark count map (DCM) measurement mode (much like a CCD). This reduces the device active area but allows the information from a single avalanche photodiode to be preserved, which is not possible with analog SiPMs. An algorithm to reject the noisiest photodiodes and to correct the measured count rate for the dark current was developed. The results show that, in DCM mode and at (10–13) °C, the PDPC has a dynamic response to different levels of Cherenkov luminescence emitted by a β source and transmitted through an opaque medium. This suggests the potential for this approach to provide quantitative activity measurements. Interestingly, the potential use of the PDPC in DCM mode for direct imaging of Cherenkov luminescence, as a opposed to a scalar measurement device, was also apparent. We showed that a PDPC tile in DCM mode is able to detect and image a β source through its Cherenkov radiation emission. The detector’s dynamic response to different levels of radiation suggests its potential quantitative capabilities, and the DCM mode allows imaging with a better spatial resolution than the conventional event-triggered mode. Finally, the same acquisition procedure and data processing could

  8. Cherenkov luminescence measurements with digital silicon photomultipliers: a feasibility study

    Ciarrocchi, Esther; Belcari, Nicola; Guerra, Alberto Del; Cherry, Simon R.; Lehnert, Adrienne; Hunter, William C. J.; McDougald, Wendy; Miyaoka, Robert S.; Kinahan, Paul E.

    2015-01-01

    A feasibility study was done to assess the capability of digital silicon photomultipliers to measure the Cherenkov luminescence emitted by a β source. Cherenkov luminescence imaging (CLI) is possible with a charge coupled device (CCD) based technology, but a stand-alone technique for quantitative activity measurements based on Cherenkov luminescence has not yet been developed. Silicon photomultipliers (SiPMs) are photon counting devices with a fast impulse response and can potentially be used to quantify β-emitting radiotracer distributions by CLI. In this study, a Philips digital photon counting (PDPC) silicon photomultiplier detector was evaluated for measuring Cherenkov luminescence. The PDPC detector is a matrix of avalanche photodiodes, which were read one at a time in a dark count map (DCM) measurement mode (much like a CCD). This reduces the device active area but allows the information from a single avalanche photodiode to be preserved, which is not possible with analog SiPMs. An algorithm to reject the noisiest photodiodes and to correct the measured count rate for the dark current was developed. The results show that, in DCM mode and at (10–13) °C, the PDPC has a dynamic response to different levels of Cherenkov luminescence emitted by a β source and transmitted through an opaque medium. This suggests the potential for this approach to provide quantitative activity measurements. Interestingly, the potential use of the PDPC in DCM mode for direct imaging of Cherenkov luminescence, as a opposed to a scalar measurement device, was also apparent. We showed that a PDPC tile in DCM mode is able to detect and image a β source through its Cherenkov radiation emission. The detector’s dynamic response to different levels of radiation suggests its potential quantitative capabilities, and the DCM mode allows imaging with a better spatial resolution than the conventional event-triggered mode. Finally, the same acquisition procedure and data processing could

  9. Modeling atmospheric effects of the September 1859 Solar Flare

    Thomas, Brian; Jackman, Charles; Melott, Adrian

    2006-01-01

    We have modeled atmospheric effects, especially ozone depletion, due to a solar proton event which probably accompanied the extreme magnetic storm of 1-2 September 1859. We use an inferred proton fluence for this event as estimated from nitrate levels in Greenland ice cores. We present results showing production of odd nitrogen compounds and their impact on ozone. We also compute rainout of nitrate in our model and compare to values from ice core data.

  10. IMPACT OF ATMOSPHERIC CHROMATIC EFFECTS ON WEAK LENSING MEASUREMENTS

    Meyers, Joshua E.; Burchat, Patricia R.

    2015-01-01

    Current and future imaging surveys will measure cosmic shear with statistical precision that demands a deeper understanding of potential systematic biases in galaxy shape measurements than has been achieved to date. We use analytic and computational techniques to study the impact on shape measurements of two atmospheric chromatic effects for ground-based surveys such as the Dark Energy Survey and the Large Synoptic Survey Telescope (LSST): (1) atmospheric differential chromatic refraction and (2) wavelength dependence of seeing. We investigate the effects of using the point-spread function (PSF) measured with stars to determine the shapes of galaxies that have different spectral energy distributions than the stars. We find that both chromatic effects lead to significant biases in galaxy shape measurements for current and future surveys, if not corrected. Using simulated galaxy images, we find a form of chromatic “model bias” that arises when fitting a galaxy image with a model that has been convolved with a stellar, instead of galactic, PSF. We show that both forms of atmospheric chromatic biases can be predicted (and corrected) with minimal model bias by applying an ordered set of perturbative PSF-level corrections based on machine-learning techniques applied to six-band photometry. Catalog-level corrections do not address the model bias. We conclude that achieving the ultimate precision for weak lensing from current and future ground-based imaging surveys requires a detailed understanding of the wavelength dependence of the PSF from the atmosphere, and from other sources such as optics and sensors. The source code for this analysis is available at https://github.com/DarkEnergyScienceCollaboration/chroma

  11. IMPACT OF ATMOSPHERIC CHROMATIC EFFECTS ON WEAK LENSING MEASUREMENTS

    Meyers, Joshua E.; Burchat, Patricia R., E-mail: jmeyers314@gmail.com [Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics, Stanford University, Stanford, CA 94305 (United States)

    2015-07-10

    Current and future imaging surveys will measure cosmic shear with statistical precision that demands a deeper understanding of potential systematic biases in galaxy shape measurements than has been achieved to date. We use analytic and computational techniques to study the impact on shape measurements of two atmospheric chromatic effects for ground-based surveys such as the Dark Energy Survey and the Large Synoptic Survey Telescope (LSST): (1) atmospheric differential chromatic refraction and (2) wavelength dependence of seeing. We investigate the effects of using the point-spread function (PSF) measured with stars to determine the shapes of galaxies that have different spectral energy distributions than the stars. We find that both chromatic effects lead to significant biases in galaxy shape measurements for current and future surveys, if not corrected. Using simulated galaxy images, we find a form of chromatic “model bias” that arises when fitting a galaxy image with a model that has been convolved with a stellar, instead of galactic, PSF. We show that both forms of atmospheric chromatic biases can be predicted (and corrected) with minimal model bias by applying an ordered set of perturbative PSF-level corrections based on machine-learning techniques applied to six-band photometry. Catalog-level corrections do not address the model bias. We conclude that achieving the ultimate precision for weak lensing from current and future ground-based imaging surveys requires a detailed understanding of the wavelength dependence of the PSF from the atmosphere, and from other sources such as optics and sensors. The source code for this analysis is available at https://github.com/DarkEnergyScienceCollaboration/chroma.

  12. Our changing atmosphere: Trace gases and the greenhouse effect

    Rowland, F.S.

    1991-01-01

    A very important factor in the scientific evaluation of greenhouse warming during the last decade has been the realization that this is not just a problem of increasing CO 2 but is rather a more general problem of increasing concentrations of many trace gases. CFCs are increasing at 5% per year with CFC-113 going up at a more rapid rate; methane approximately 1% per year; CO 2 by 0.5% per year; N 2 O about 0.2% per year. These rates of increase have been fed into detailed models of the infrared absorbing characteristics of the atmosphere, and have provided the estimated relative contributions from the various trace gases. Carbon dioxide is still the major contributor to the greenhouse effect, and its yearly contribution appears to be increasing. An important question for dealing with the greenhouse effect will be the full understanding of these CO 2 concentration changes. The total amount of carbon from the burning of fossil fuel that is going into the atmosphere is considerably larger than the carbon dioxide increase registered in the atmosphere. Appreciable CO 2 contributions are also being received from the burning of the tropical forests. The procedures necessary to solve the chlorofluorocarbon problem have been put into place on an international scale and have begun to be implemented. We still have left for the future, however, efforts to reduce emissions of carbon dioxide, methane, and nitrous oxide

  13. Atmospheric turbulence and sensor system effects on biometric algorithm performance

    Espinola, Richard L.; Leonard, Kevin R.; Byrd, Kenneth A.; Potvin, Guy

    2015-05-01

    Biometric technologies composed of electro-optical/infrared (EO/IR) sensor systems and advanced matching algorithms are being used in various force protection/security and tactical surveillance applications. To date, most of these sensor systems have been widely used in controlled conditions with varying success (e.g., short range, uniform illumination, cooperative subjects). However the limiting conditions of such systems have yet to be fully studied for long range applications and degraded imaging environments. Biometric technologies used for long range applications will invariably suffer from the effects of atmospheric turbulence degradation. Atmospheric turbulence causes blur, distortion and intensity fluctuations that can severely degrade image quality of electro-optic and thermal imaging systems and, for the case of biometrics technology, translate to poor matching algorithm performance. In this paper, we evaluate the effects of atmospheric turbulence and sensor resolution on biometric matching algorithm performance. We use a subset of the Facial Recognition Technology (FERET) database and a commercial algorithm to analyze facial recognition performance on turbulence degraded facial images. The goal of this work is to understand the feasibility of long-range facial recognition in degraded imaging conditions, and the utility of camera parameter trade studies to enable the design of the next generation biometrics sensor systems.

  14. Prospects for very large, sensitive water Cherenkov detectors for proton decay and neutrino oscillations search

    Cline, D.B.

    1982-01-01

    We discuss the possibility of constructing large water Cherenkov detectors with mass 10 5 to 10 6 tons that would be sensitive to a few hundred MeV - few GeV energy release. The 10 5 ton detector would be suitable for a search for certain proton decay modes whereas the 10 6 ton detector would act as an active shield for the proton decay detector and as a nu/sub e/, nu/sub μ/ and possibly nu/sub tau/ interaction detector. The neutrino physics would include a sensitive search for neutrino oscillations using atmospheric neutrinos. The location of this detector could be in the deep ocean near Hawaii or in a deep trench between Cuba and Haiti or perhaps deep lakes like Superior or Baikal if flexible containers are used

  15. Modeling of Atmospheric Turbulence Effect on Terrestrial FSO Link

    A. Prokes

    2009-04-01

    Full Text Available Atmospheric turbulence results in many effects causing fluctuation in the received optical power. Terrestrial laser beam communication is affected above all by scintillations. The paper deals with modeling the influence of scintillation on link performance, using the modified Rytov theory. The probability of correct signal detection in direct detection system in dependence on many parameters such as link distance, power link margin, refractive-index structure parameter, etc. is discussed and different approaches to the evaluation of scintillation effect are compared. The simulations are performed for a horizontal-path propagation of the Gaussian-beam wave.

  16. Extremely frequency-widened terahertz wave generation using Cherenkov-type radiation.

    Suizu, Koji; Koketsu, Kaoru; Shibuya, Takayuki; Tsutsui, Toshihiro; Akiba, Takuya; Kawase, Kodo

    2009-04-13

    Terahertz (THz) wave generation based on nonlinear frequency conversion is promising way for realizing a tunable monochromatic bright THz-wave source. Such a development of efficient and wide tunable THz-wave source depends on discovery of novel brilliant nonlinear crystal. Important factors of a nonlinear crystal for THz-wave generation are, 1. High nonlinearity and 2. Good transparency at THz frequency region. Unfortunately, many nonlinear crystals have strong absorption at THz frequency region. The fact limits efficient and wide tunable THz-wave generation. Here, we show that Cherenkov radiation with waveguide structure is an effective strategy for achieving efficient and extremely wide tunable THz-wave source. We fabricated MgO-doped lithium niobate slab waveguide with 3.8 microm of thickness and demonstrated difference frequency generation of THz-wave generation with Cherenkov phase matching. Extremely frequency-widened THz-wave generation, from 0.1 to 7.2 THz, without no structural dips successfully obtained. The tuning frequency range of waveguided Cherenkov radiation source was extremely widened compare to that of injection seeded-Terahertz Parametric Generator. The tuning range obtained in this work for THz-wave generation using lithium niobate crystal was the widest value in our knowledge. The highest THz-wave energy obtained was about 3.2 pJ, and the energy conversion efficiency was about 10(-5) %. The method can be easily applied for many conventional nonlinear crystals, results in realizing simple, reasonable, compact, high efficient and ultra broad band THz-wave sources.

  17. Atmospheric greenhouse effect: more subtle than it looks like

    Dufresne, J.L.; Treiner, J.

    2011-01-01

    State-of-the-art radiative models can be used to calculate in a rigorous and accurate manner the atmospheric greenhouse effect, as well as its variation with concentration in water vapour or carbon dioxide. A simple explanation of this effect uses an analogy with the greenhouse effect produced by a glass window. While this analogy has pedagogical virtues and provides a first order explanation of the mean temperature of the Earth, it has an important drawback; it is not able to explain why the greenhouse effect increases with increasing carbon dioxide concentration. Indeed, absorption of infrared radiation by carbon dioxide is, under this scheme, almost at its maximum and depends very weakly on CO 2 concentration. It is said to be saturated. In this paper, we explore this question and propose an alternative model which, while remaining simple, correctly takes into account the various mechanisms and provides an understanding of the increasing greenhouse effect with CO 2 concentration, together with the corresponding climate warming. The role of the atmospheric temperature gradient is particularly stressed. (authors)

  18. Review of specific effects in atmospheric dispersion calculations

    Underwood, B.Y.; Cooper, P.J.; Holloway, N.J.; Kaiser, G.D.; Nixon, W.

    1984-01-01

    This report consists of a series of 7 individual review chapters -written between 1980 and 1983- together with a summary document linking and overviewing the work. The topics covered are as follows: ''atmospheric dispersion in urban environments''; ''topographical effects in nuclear safety studies''; coastal effects and transport over water''; ''time-varying meteorology in consequence assessment''; ''building effects in nuclear safety studies''; effect of variations in mixing height on atmospheric dispersion''; ''the effect of turning of the wind with height on lateral dispersion''. Although the reviews are, on the whole, general in approach, emphasis has been given where appropriate to the impact of various phenomena on the assessment of reactor accident consequences. In general the work focuses on the 0-100 km range of distance downwind of the source. The reviews fulfil several functions: they serve as introductions to the subject areas; they outline theoretical and experimental developments; they act as reference documents providing a copious source of references for more detailed investigation of particular points; they raise unresolved technical issues and attempt to indicate principal uncertainties; they point to areas requiring further development

  19. Measurement of atmospheric neutrino oscillations and matter effects with PINGU

    Coenders, Stefan; Euler, Sebastian; Krings, Kai; Vehring, Markus; Wallraff, Marius; Wiebusch, Christopher [RWTH Aachen Univ. (Germany). III. Physikalisches Inst.; Collaboration: IceCube-Collaboration

    2013-07-01

    With IceCube's low-energy extension DeepCore the first significant effects of atmospheric neutrino oscillations have been observed. The planned ''Precision Icecube Next Generation Upgrade'' (PINGU) inside DeepCore will lower the energy threshold to a few GeV, where matter effects of neutrino oscillations have to be taken into account. The Mikheyev-Smirnov-Wolfenstein (MSW) effect modifies the mixing between flavor and mass eigenstates of the neutrinos, resulting in stronger oscillations. Furthermore, neutrinos when passing through the Earth core experience parametric enhancement due to multiple discontinuities in the electron density. In this talk the effects of matter oscillations and the capabilities to measure these effects with PINGU are investigated.

  20. Atmospheric natural disasters in Serbia: Management experience and economic effects

    Nikolić Jugoslav

    2013-01-01

    Full Text Available Natural disasters occur as a result of an action of natural forces and represent limitations in spatial planning and efficient spatial development, with different consequences in terms of scope on humans, living things and tangible property. Consequences can be ecological, economic, in terms of health, demographic, social, psychological, etc. Weather modification management involves policies, methods, techniques and technologies that affect atmospheric features in order to make atmospheric water useful for humans, while eliminating its negative effects. Highly significant risk of natural disasters in Serbia is related to hailstorm disasters and droughts as atmospheric elementary disasters. The goal of this paper is to present certain methodologies and experience in Serbia in the weather modification management, mainly in the hailstorm processes. This paper provides analysis and critical review of the methodology of an action, with the analysis of the economic benefits. Cost-benefit analysis of a hail suppression project in Serbia was performed. The results point to the economic justification of some aspects of artificial influence on weather disasters.

  1. Confirmatory research program: effects of atmospheric contaminants on commercial charcoals

    Bellamy, R.R.; Dietz, V.R.

    1979-01-01

    The increased use of activated charcoals in engineered-safety-feature and normal ventilation systems of nuclear power stations to continually remove radioiodine from flowing air prior to release to the environment has added importance to the question of the effect of atmospheric contaminants on the useful life of the charcoal. In January of 1977 the Naval Research Laboratory (NRL) began an investigation to determine the extent to which atmospheric contaminants in ambient concentrations degrade the efficiency of various commercially-available charcoals for removing methyl iodide. The approach employed by NRL is two-fold. First, charcoal samples are exposed to unmodified outdoor air for periods of one to nine months, then examined for methyl iodide retention, increase in weight, and the pH of water extract. The atmospheric contaminants are identified by the NRL Air Quality Monitoring Station, and concentrations of the various contaminants (ozone, SO 2 , NO 2 , CO 2 , methane and total hydrocarbons) are also available. Second, additional charcoal samples are exposed to the same pollutants under controlled laboratory conditions in various pollutant combinations. Results indicate that the water vapor-charcoal interaction is an important factor in the degradation of the commercial charcoals. Laboratory results indicate the pollutant sulfur dioxide plus water vapor can result in significant charcoal deterioration, as did ozone plus water vapor. Conversely, carbon monoxide did not appear to affect the charcoal. Also, differences were observed for various charcoals

  2. Strategy implementation for the CTA Atmospheric monitoring program

    Doro Michele

    2015-01-01

    Full Text Available The Cherenkov Telescope Array (CTA is the next generation facility of Imaging Atmospheric Cherenkov Telescopes. It reaches unprecedented sensitivity and energy resolution in very-high-energy gamma-ray astronomy. CTA detects Cherenkov light emitted within an atmospheric shower of particles initiated by cosmic-gamma rays or cosmic rays entering the Earth's atmosphere. From the combination of images the Cherenkov light produces in the telescopes, one is able to infer the primary particle energy and direction. A correct energy estimation can be thus performed only if the local atmosphere is well characterized. The atmosphere not only affects the shower development itself, but also the Cherenkov photon transmission from the emission point in the particle shower, at about 10–20 km above the ground, to the detector. Cherenkov light on the ground is peaked in the UV-blue region, and therefore molecular and aerosol extinction phenomena are important. The goal of CTA is to control systematics in energy reconstruction to better than 10%. For this reason, a careful and continuous monitoring and characterization of the atmosphere is required. In addition, CTA will be operated as an observatory, with data made public along with appropriate analysis tools. High-level data quality can only be ensured if the atmospheric properties are consistently and continuously taken into account. In this contribution, we concentrate on discussing the implementation strategy for the various atmospheric monitoring instruments currently under discussion in CTA. These includes Raman lidars and ceilometers, stellar photometers and others available both from commercial providers and public research centers.

  3. Space weather effects measured in atmospheric radiation on aircraft

    Tobiska, W. K.; Bouwer, D.; Bailey, J. J.; Didkovsky, L. V.; Judge, K.; Wieman, S. R.; Atwell, W.; Gersey, B.; Wilkins, R.; Rice, D.; Schunk, R. W.; Bell, L. D.; Mertens, C. J.; Xu, X.; Wiltberger, M. J.; Wiley, S.; Teets, E.; Shea, M. A.; Smart, D. F.; Jones, J. B. L.; Crowley, G.; Azeem, S. I.; Halford, A. J.

    2016-12-01

    Space weather's effects upon the near-Earth environment are due to dynamic changes in the energy transfer processes from the Sun's photons, particles, and fields. Of the domains that are affected by space weather, the coupling between the solar and galactic high-energy particles, the magnetosphere, and atmospheric regions can significantly affect humans and our technology as a result of radiation exposure. Since 2013 Space Environment Technologies (SET) has been conducting observations of the atmospheric radiation environment at aviation altitudes using a small fleet of six instruments. The objective of this work is to improve radiation risk management in air traffic operations. Under the auspices of the Automated Radiation Measurements for Aerospace Safety (ARMAS) and Upper-atmospheric Space and Earth Weather eXperiment (USEWX) projects our team is making dose rate measurements on multiple aircraft flying global routes. Over 174 ARMAS and USEWX flights have successfully demonstrated the operation of a micro dosimeter on commercial aviation altitude aircraft that captures the radiation environment resulting from Galactic Cosmic Rays (GCRs), Solar Energetic Protons (SEPs), and outer radiation belt energetic electrons. The real-time radiation exposure is measured as an absorbed dose rate in silicon and then computed as an ambient dose equivalent rate for reporting dose relevant to radiative-sensitive organs and tissue in units of microsieverts per hour. ARMAS total ionizing absorbed dose is captured on the aircraft, downlinked in real-time, processed on the ground into ambient dose equivalent rates, compared with NASA's Langley Research Center (LaRC) most recent Nowcast of Atmospheric Ionizing Radiation System (NAIRAS) global radiation climatology model runs, and then made available to end users. Dose rates from flight altitudes up to 56,700 ft. are shown for flights across the planet under a variety of space weather conditions. We discuss several space weather

  4. The Greenhouse effect within an analytic model of the atmosphere

    Dehnen, Heinz [Konstanz Univ. (Germany). Fachbereich Physik

    2009-01-15

    Within a simplified atmospheric model the greenhouse effect is treated by analytical methods starting from physical first principles. The influence of solar radiation, absorption cross sections of the greenhouse molecules, and cloud formation on the earth's temperature is shown and discussed explicitly by mathematical formulae in contrast to the climate simulations. The application of our analytical results on the production of 20 .10{sup 9} t of CO{sub 2} per year yields an enlargement of the earth's surface temperature of 2.3 .10{sup -2} C per year in agreement with other estimations. (orig.)

  5. Development of an underwater high sensitivity Cherenkov detector: Sea Urchin

    Camerini, U.; McGibney, D.; Roberts, A.

    1982-01-01

    The need for a high gain, high sensitivity Cherenkov light sensor to be used in a deep underwater muon and neutrino detector (DUMAND) array has led to the design of the Sea Urchin detector. In this design a spherical photocathode PMTis optically coupled through a glass hemisphere to a large number of glass spines, each of which is filled with a wavelength-shifting (WLS) solution of a high quantum efficiency phosphor. The Cherenkov radiation is absorbed in the spine, isotropically re-radiated at a longer wavelength, and a fraction of the fluorescent light is internally reflected in the spine, and guided to the photomultiplier concentrically located in the glass hemisphere. Experiments measuring the optical characteristics of the spines and computer programs simulating light transformation and detection cross sections are described. Overall optical gains in the range 5-10 are achieved. The WLS solution is inexpensive, and may have other applications. (orig.)

  6. G-APDs in Cherenkov astronomy: The FACT camera

    Krähenbühl, T.; Anderhub, H.; Backes, M.; Biland, A.; Boller, A.; Braun, I.; Bretz, T.; Commichau, V.; Djambazov, L.; Dorner, D.; Farnier, C.; Gendotti, A.; Grimm, O.; Gunten, H. von; Hildebrand, D.; Horisberger, U.; Huber, B.; Kim, K.-S.; Köhne, J.-H.; Krumm, B.

    2012-01-01

    Geiger-mode avalanche photodiodes (G-APD, SiPM) are a much discussed alternative to photomultiplier tubes in Cherenkov astronomy. The First G-APD Cherenkov Telescope (FACT) collaboration builds a camera based on a hexagonal array of 1440 G-APDs and has now finalized its construction phase. A light-collecting solid PMMA cone is glued to each G-APD to eliminate dead space between the G-APDs by increasing the active area, and to restrict the light collection angle of the sensor to the reflector area in order to reduce the amount of background light. The processing of the signals is integrated in the camera and includes the digitization using the domino ring sampling chip DRS4.

  7. Study of a Cherenkov TOF-PET module

    Korpar, S.; Dolenec, R.; Križan, P.; Pestotnik, R.; Stanovnik, A.

    2013-12-01

    An apparatus, consisting of two PbF2 crystals, each coupled to a multichannel plate photomultiplier (MCP-PMT), has been constructed in order to measure the time-of-flight (TOF) of the two 511 keV annihilation photons produced in positron emission tomography (PET). Excellent timing is achieved by detecting the prompt Cherenkov photons produced by the absorption of the 511 keV gamma photons. The present work describes the measurement and image reconstruction of two 22Na point sources. In addition, the influence of the radiator thickness and the Cherenkov light absorption cut-off of the crystal on the efficiency and the timing resolution have been studied by Monte Carlo simulation.

  8. Dark matter searches with Cherenkov telescopes: nearby dwarf galaxies or local galaxy clusters?

    Sánchez-Conde, Miguel A. [SLAC National Laboratory and Kavli Institute for Particle Astrophysics and Cosmology, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Cannoni, Mirco; Gómez, Mario E. [Dpto. Física Aplicada, Facultad de Ciencias Experimentales, Universidad de Huelva, 21071 Huelva (Spain); Zandanel, Fabio; Prada, Francisco, E-mail: masc@stanford.edu, E-mail: mirco.cannoni@dfa.uhu.es, E-mail: fabio@iaa.es, E-mail: mario.gomez@dfa.uhu.es, E-mail: fprada@iaa.es [Instituto de Astrofísica de Andalucía (CSIC), E-18008, Granada (Spain)

    2011-12-01

    In this paper, we compare dwarf galaxies and galaxy clusters in order to elucidate which object class is the best target for gamma-ray DM searches with imaging atmospheric Cherenkov telescopes (IACTs). We have built a mixed dwarfs+clusters sample containing some of the most promising nearby dwarf galaxies (Draco, Ursa Minor, Wilman 1 and Segue 1) and local galaxy clusters (Perseus, Coma, Ophiuchus, Virgo, Fornax, NGC 5813 and NGC 5846), and then compute their DM annihilation flux profiles by making use of the latest modeling of their DM density profiles. We also include in our calculations the effect of DM substructure. Willman 1 appears as the best candidate in the sample. However, its mass modeling is still rather uncertain, so probably other candidates with less uncertainties and quite similar fluxes, namely Ursa Minor and Segue 1, might be better options. As for galaxy clusters, Virgo represents the one with the highest flux. However, its large spatial extension can be a serious handicap for IACT observations and posterior data analysis. Yet, other local galaxy cluster candidates with more moderate emission regions, such as Perseus, may represent good alternatives. After comparing dwarfs and clusters, we found that the former exhibit annihilation flux profiles that, at the center, are roughly one order of magnitude higher than those of clusters, although galaxy clusters can yield similar, or even higher, integrated fluxes for the whole object once substructure is taken into account. Even when any of these objects are strictly point-like according to the properties of their annihilation signals, we conclude that dwarf galaxies are best suited for observational strategies based on the search of point-like sources, while galaxy clusters represent best targets for analyses that can deal with rather extended emissions. Finally, we study the detection prospects for present and future IACTs in the framework of the constrained minimal supersymmetric standard model. We

  9. Dark Matter Searches with Cherenkov Telescopes: Nearby Dwarf Galaxies or Local Galaxy Clusters?

    Sanchez-Conde, Miguel A.; /KIPAC, Menlo Park /SLAC /IAC, La Laguna /Laguna U., Tenerife; Cannoni, Mirco; /Huelva U.; Zandanel, Fabio; /IAA, Granada; Gomez, Mario E.; /Huelva U.; Prada, Francisco; /IAA, Granada

    2012-06-06

    In this paper, we compare dwarf galaxies and galaxy clusters in order to elucidate which object class is the best target for gamma-ray DM searches with imaging atmospheric Cherenkov telescopes (IACTs). We have built a mixed dwarfs+clusters sample containing some of the most promising nearby dwarf galaxies (Draco, Ursa Minor, Wilman 1 and Segue 1) and local galaxy clusters (Perseus, Coma, Ophiuchus, Virgo, Fornax, NGC 5813 and NGC 5846), and then compute their DM annihilation flux profiles by making use of the latest modeling of their DM density profiles. We also include in our calculations the effect of DM substructure. Willman 1 appears as the best candidate in the sample. However, its mass modeling is still rather uncertain, so probably other candidates with less uncertainties and quite similar fluxes, namely Ursa Minor and Segue 1, might be better options. As for galaxy clusters, Virgo represents the one with the highest flux. However, its large spatial extension can be a serious handicap for IACT observations and posterior data analysis. Yet, other local galaxy cluster candidates with more moderate emission regions, such as Perseus, may represent good alternatives. After comparing dwarfs and clusters, we found that the former exhibit annihilation flux profiles that, at the center, are roughly one order of magnitude higher than those of clusters, although galaxy clusters can yield similar, or even higher, integrated fluxes for the whole object once substructure is taken into account. Even when any of these objects are strictly point-like according to the properties of their annihilation signals, we conclude that dwarf galaxies are best suited for observational strategies based on the search of point-like sources, while galaxy clusters represent best targets for analyses that can deal with rather extended emissions. Finally, we study the detection prospects for present and future IACTs in the framework of the constrained minimal supersymmetric standard model. We

  10. A quartz Cherenkov detector for polarimetry at the ILC

    Vauth, Annika

    2014-09-01

    At the proposed International Linear Collider (ILC), the use of polarised electron and positron beams is a key ingredient of the physics program. A measurement of the polarisation with a yet unprecedented precision of δP / P =0.25% is required. To achieve this, Compton polarimeter measurements in front of and behind the collision point are foreseen. In this thesis, a novel concept for a detector for ILC polarimetry is introduced to eliminate one of the dominating systematics limiting the previous best measurement of beam polarisation: a detector using quartz as Cherenkov medium could increase the tolerance against non-linear photodetector responses. The high refractive index of quartz results in a higher Cherenkov light yield compared to conventional Cherenkov gases. This could allow single-peak resolution in the Cherenkov photon spectra produced by the Compton electrons at the polarimeters. The detailed simulation studies presented in this work imply that such single-peak resolution is possible. Considerations for the choice of a suitable detector geometry are discussed. A four-channel prototype has been constructed and successfully operated in a first testbeam campaign at the DESY testbeam, confirming simulation predictions. Although further studies have to be considered to quantify all aspects of the detector response, the findings of the analysis of the data from the first testbeam are promising with regards to reaching the desired light yield. In the final part of this thesis, the application of a detector concept allowing single-peak resolution to the polarisation measurement at the ILC is examined. Two of the main sources of systematic uncertainties on the polarimeter measurements are detector non-linearities and misalignments. The performance of the suggested quartz detector concept in Monte Carlo studies promises a control of these systematics which meets the precision requirements for ILC polarimetry.

  11. The fluid systems for the SLD Cherenkov ring imaging detector

    Abe, K.; Hasegawa, K.; Hasegawa, Y.; Iwasaki, Y.; Suekane, F.; Yuta, H.; Baird, K.; Jacques, P.; Kalelkar, M.; Plano, R.; Stamer, P.; Word, G.; Bean, A.; Caldwell, D.O.; Duboscq, J.; Huber, J.; Lu, A.; Mathys, L.; McHugh, S.; Yellin, S.; Ben-David, R.; Manly, S.; Snyder, J.; Turk, J.; Cavalli-Sforza, M.; Coyle, P.; Coyne, D.; Gagnon, P.; Liu, X.; Schneider, M.; Williams, D.A.; Coller, J.; Shank, J.T.; Whitaker, J.S.; d'Oliveira, A.; Johnson, R.A.; Martinez, J.; Nussbaum, M.; Santha, A.K.S.; Sokoloff, M.D.; Stockdale, I.; Wilson, R.J.

    1992-10-01

    We describe the design and operation of the fluid delivery, monitor and control systems for the SLD barrel Cherenkov Ring Imaging Detector (CRID). The systems deliver drift gas (C 2 H 6 + TMAE), radiator gas (C 5 F 12 + N 2 ) and radiator liquid (C 6 F 14 ). Measured critical quantities such as electron lifetime in the drift gas and ultra-violet (UV) transparencies of the radiator fluids, together with the operational experience, are also reported

  12. The new Tunka-133 EAS Cherenkov array: Status of 2009

    Antokhonov, B.V.; Beregnev, S.F.; Budnev, N.M.; Chvalaev, O.B.; Chiavassa, A.; Gress, O.A.; Kalmykov, N.N.; Karpov, N.N.; Korosteleva, E.E.; Kozhin, V.A.; Kuzmichev, L.A.; Lubsandorzhiev, B.K.; Mirgazov, R.R.; Panasyuk, M.I.; Pankov, L.V.; Prosin, V.V.; Ptuskin, V.S.; Semeney, Yu.A.; Shaibonov, B.; Silaev, A.A.

    2011-01-01

    The deployment of the new Extensive air shower Cherenkov installation Tunka-133 with about 1 km 2 geometric acceptance area was completed in October 2009. The array will permit a detailed long-term study of the cosmic ray energy spectrum and mass composition in the energy range 10 15 -10 18 eV with a unique and more elaborate method. The array construction and data acquisition system, preliminary results and plans for future development are presented.

  13. Experimental and numerical investigations of a Cherenkov plasma maser

    Huet, D.; Pompier, F.; Vezinet, R.; Courtois, L.; Cubaynes, F.; Lalle, B.; Laporte, P.

    2005-01-01

    We are investigating the performances of a new tunable and low frequency (2-6 GHz band) Cherenkov plasma master driven by a 600 kV, 100 ns Tesla generator. We present experimental results in terms of energy and spectrum and their comparison with 2D computer simulations results versus voltage, plasma density and B field levels. The accelerator is presented in the first part of the paper [ru

  14. The Tunka-133 EAS Cherenkov light array: Status of 2011

    Berezhnev, S.F.; Besson, D.; Budnev, N.M.; Chiavassa, A.; Chvalaev, O.A.; Gress, O.A.; Dyachok, A.N.; Epimakhov, S.N.; Haungs, A.; Karpov, N.I.; Kalmykov, N.N.; Konstantinov, E.N.; Korobchenko, A.V.; Korosteleva, E.E.; Kozhin, V.A.; Kuzmichev, L.A.; Lubsandorzhiev, B.K.; Lubsandorzhiev, N.B.; Mirgazov, R.R.; Panasyuk, M.I.

    2012-01-01

    A new EAS Cherenkov light array, Tunka-133, with ∼1km 2 geometrical area has been installed at the Tunka Valley (50 km from Lake Baikal) in 2009. The array permits a detailed study of cosmic ray energy spectrum and mass composition in the energy range 10 16 –10 18 eV with a uniform method. We describe the array construction, DAQ and methods of the array calibration. The method of energy reconstruction and absolute calibration of measurements are discussed. The analysis of spatial and time structure of EAS Cherenkov light allows to estimate the depth of the EAS maximum X max . The results on the all particles energy spectrum and the mean depth of the EAS maximum X max vs. primary energy derived from the data of two winter seasons (2009–2011) are presented. Preliminary results of joint operation of the Cherenkov array with antennas for the detection of EAS radio signals are shown. Plans for future upgrades – deployment of remote clusters, radioantennas and a scintillator detector network and a prototype of the HiSCORE gamma-telescope – are discussed.

  15. Recent results from the DELPHI barrel ring imaging Cherenkov counter

    Anassontzis, E.G.; Ioannou, P.; Kalkanis, G.; Katsanevas, S.; Kontaxis, I.; Kourkoumelis, C.; Nounos, S.; Preve, P.; Resvanis, L.K.; Brunet, J.M.; Dolbeau, J.; Guglielmo, L.; Ledroit, F.; Poutot, D.; Tristram, G.

    1991-01-01

    The DELPHI detector, installed at LEP, is equipped with RICH (Ring Imaging Cherenkov) counters. The Barrel part incorporates a liquid (C 6 F 14 ) and a gaseous (C 5 F 12 ) radiator providing particle identification up to 20GeV/c. The Cherenkov protons of both radiators are detected by TPC-like photon detectors. The drift gas (75% CH 4 + 25% C 2 H 6 ) is doped with TMAE, but which the UV Cherenkov photons are converted into single free photo-electrons. These are drifted towards MWPC's at the end of the drift tubes and the space coordinates of the conversion point are determined. One half of the Barrel RICH is now equipped with drift tubes and has provided results from the liquid radiator since spring 1990. The gas radiator has been tested with C 2 F 6 as a preliminary filling since August 1990. The data obtained demonstrate the good particle identification potential. For the liquid radiator the number of detected photons per ring in hadron jets is N=8, whereas for muon pairs (single tracks) N=10 has been obtained. For the gas radiator 2.1 photons per track were observed, which demonstrates the good functioning of the focussing mirrors, as the C 2 F 6 this is close to the expected value

  16. Characterization of Multianode Photomultiplier Tubes for a Cherenkov Detector

    Benninghoff, Morgen; Turisini, Matteo; Kim, Andrey; Benmokhtar, Fatiha; Kubarovsky, Valery; Duquesne University Collaboration; Jefferson Lab Collaboration

    2017-09-01

    In the Fall of 2017, Jefferson Lab's CLAS12 (CEBAF Large Acceptance Spectrometer) detector is expecting the addition of a RICH (ring imaging Cherenkov) detector which will allow enhanced particle identification in the momentum range of 3 to 8 GeV/c. RICH detectors measure the velocity of charged particles through the detection of produced Cherenkov radiation and the reconstruction of the angle of emission. The emitted Cherenkov photons are detected by a triangular-shaped grid of 391 multianode photomultiplier tubes (MAPMTs) made by Hamamatsu. The custom readout electronics consist of MAROC (multianode read out chip) boards controlled by FPGA (Field Programmable Gate Array) boards, and adapters used to connect the MAROC boards and MAPMTs. The focus of this project is the characterization of the MAPMTs with the new front end electronics. To perform these tests, a black box setup with a picosecond diode laser was constructed with low and high voltage supplies. A highly automated procedure was developed to acquire data at different combinations of high voltage values, light intensities and readout electronics settings. Future work involves using the collected data in calibration procedures and analyzing that data to resolve the best location for each MAPMT. SULI, NSF.

  17. A Cherenkov viewing device for used-fuel verification

    Attas, E.M.; Chen, J.D.; Young, G.J.

    1990-01-01

    A Cherenkov viewing device (CVD) has been developed to help verify declared inventories of used nuclear fuel stored in water bays. The device detects and amplifies the faint ultraviolet Cherenkov glow from the water surrounding the fuel, producing a real-time visible image on a phosphor screen. Quartz optics, a UV-pass filter and a microchannel-plate image-intensifier tube serve to form the image, which can be photographed or viewed directly through an eyepiece. Normal fuel bay lighting does not interfere with the Cherenkov light image. The CVD has been successfully used to detect anomalous PWR, BWR and CANDU (CANada Deuterium Uranium: registered trademark) fuel assemblies in the presence of normal-burnup assemblies stored in used-fuel bays. The latest version of the CVD, known as Mark IV, is being used by inspectors from the International Atomic Energy agency for verification of light-water power-reactor fuel. Its design and operation are described, together with plans for further enhancements of the instrumentation. (orig.)

  18. Geodetic refraction effects of electromagnetic wave propagation through the atmosphere

    1984-01-01

    With very few exceptions, geodetic measurements use electro­ magnetic radiation in order to measure directions, distances, time delays, and Doppler frequency shifts, to name the main ter­ restrial and space observables. Depending on the wavelength of the radiation and the purpose of the measurements, the follow­ ing parameters of the electromagnetic wave are measured: ampli­ tude, phase, angle-of-arrival, polarisation and frequency. Ac­ curate corrections have to be applied to the measurements in order to take into account the effects of the intervening medium between transmitter and receiver. The known solutions use at­ mospheric models, special observation programs, remote sensing techniques and instrumental methods. It has been shown that the effects of the earth's atmospheric envelope present a fundamental limitation to the accuracy and precision of geodetic measurements. This applies equally to ter­ restrial and space applications. Instrumental accuracies are al­ ready below the atmospherically i...

  19. ATMOSPHERE PRESSURE EFFECT ON THE FIBER OPTIC GYROSCOPE OUTPUT SYGNAL

    Ilya A. Sharkov

    2017-05-01

    Full Text Available The paper describes research results of the atmospheric pressure effect on the output signal of a fiber optic gyroscope (FOG. In the course of experiments, FOG was placed into a hermetic chamber. The atmosphere pressure was varying in the range from 0.8 to 1.5 atm. All the data, including the FOG output signal, temperature, and data from the pressure sensor installed inside the FOG, were synchronously registered with the computer software. The separation of scale factor change from zero offset in the experiment was carried out by setting the sensitive FOG axis at 0°, 90° and 270° relative to the East (the FOG was set perpendicular to the horizon. After the data processing it was concluded that the FOG signal error associated with the pressure affects mainly on the additive component. The pressure effect on the multiplicative component appeared to be negligible at rotational velocities used in the experiment (0 - 130 /h. At the same time, the FOG signal has a high linear correlation coefficient with the derivative of pressure over time (in some cases, more than 0.9. The experiment was repeated several times and the high degree of the drift repeatability was shown. That makes it possible to implement the compensation algorithm. Application of the simplest algorithmic compensation based on the polynomial of the first degree (ax + b enabled to reduce the root-mean-square (RMS and drift of the signal by 2-9 times.

  20. Integrated Assessment of Ecosystem Effects of Atmospheric Deposition

    Ecosystems obtain a portion of their nutrients from the atmosphere. Following the Industrial Revolution, however, human activities have accelerated biogeochemical cycles, greatly enhancing the transport of substances among the atmosphere, water, soil, and living things. The atmos...

  1. On the permanent hip-stabilizing effect of atmospheric pressure.

    Prietzel, Torsten; Hammer, Niels; Schleifenbaum, Stefan; Kaßebaum, Eric; Farag, Mohamed; von Salis-Soglio, Georg

    2014-08-22

    Hip joint dislocations related to total hip arthroplasty (THA) are a common complication especially in the early postoperative course. The surgical approach, the alignment of the prosthetic components, the range of motion and the muscle tone are known factors influencing the risk of dislocation. A further factor that is discussed until today is atmospheric pressure which is not taken into account in the present THA concepts. The aim of this study was to investigate the impact of atmospheric pressure on hip joint stability. Five joint models (Ø 28-44 mm), consisting of THA components were hermetically sealed with a rubber capsule, filled with a defined amount of fluid and exposed to varying ambient pressure. Displacement and pressure sensors were used to record the extent of dislocation related to intraarticular and ambient pressure. In 200 experiments spontaneous dislocations of the different sized joint models were reliably observed once the ambient pressure was lower than 6.0 kPa. Increasing the ambient pressure above 6.0 kPa immediately and persistently reduced the joint models until the ambient pressure was lowered again. Displacement always exceeded half the diameter of the joint model and was independent of gravity effects. This experimental study gives strong evidence that the hip joint is permanently stabilized by atmospheric pressure, confirming the theories of Weber and Weber (1836). On basis of these findings the use of larger prosthetic heads, capsular repair and the deployment of an intracapsular Redon drain are proposed to substantially decrease the risk of dislocation after THA. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Effects of energetic particle precipitation on the atmospheric electric circuit

    Reagan, J.B.; Meyerott, R.E.; Evans, J.E.; Imhof, W.L.; Joiner, R.G.

    1983-01-01

    The solar particle event (SPE) of August 1972 is one of the largest that has occurred in the last 20 years. Since it is so well documented, it can serve as a good example of a major perturbation to the atmospheric electric system. In this paper, ion production rates and conductivities from the ground to 80 km at the peak intensity of the event on August 4 and for 30, 35, and 40 km for the 6-day duration of the event are presented. At the peak of the event, the proton and electron precipitation currents, the ohmic current, and the vertical electric field are calculated inside the polar cap. The particle precipitation currents at this time greatly exceed the normal air earth current at altitudes above 30 km and produce reversals in the vertical electric field at 28 km and above. Calculations are presented of the vertical electric field at altitudes near 30 km where balloon measurements were made. Good agreement between the calculated and the measured vertical electric field verifies our ability to calculate disturbed conductivities at these altitudes from satellite measurements of proton spectra incident on the atmosphere. Despite the fact that at the peak of the event the vertical electric field near 30 km was shorted out by the solar particles and that the current carried by the solar particles exceeded the fair weather air-earth current density in the stratosphere by large factors, it is concluded that the largest effect of an SPE of this magnitude on the atmospheric electric circuit is due to the Forbush decrease in the galactic cosmic ray flux rather than to the large increase in solar proton flux

  3. Visual sensations during megavoltage radiotherapy to the orbit attributable to Cherenkov radiation

    Newman, Francis; Asadi-Zeydabadi, Masoud; Durairaj, Vikram D.; Ding Meisong; Stuhr, Kelly; Kavanagh, Brian

    2008-01-01

    During megavoltage photon and electron beam radiotherapy treatment involving the eye, patients commonly report visual sensations; 'nerve stimulation' is the conventional explanation. We propose that the phenomenon can be attributed to Cherenkov radiation inside the eye. The threshold electron energy for Cherenkov radiation in water is 260 keV. The human retina is able to perceive approximately 5-14 visible photons in 0.001 s. A single 500 keV electron traversing 1 mm of water will induce nearly 15 Cherenkov visible range photons. We propose that a portal image involving the eye will produce sufficient Cherenkov radiation to be detected by the retina

  4. Rancho Seco building wake effects on atmospheric diffusion

    Start, G.E.; Cate, J.H.; Dickson, C.R.; Ricks, N.R.; Ackerman, G.R.; Sagendorf, J.F.

    1977-11-01

    A series of 23 paired gaseous tracer releases at the Rancho Seco Nuclear Power Station in 1975 was the third of several tests designed to investigate the diffusion characteristics of the atmosphere under conditions of low windspeed and temperature inversion. This test also evaluated the effects of flow around buildings upon dilution of pollutants. Gaseous tracers were laterally dispersed about six times more than the expected amounts from Pasquill--Gifford curves of sigma-y. Most of this increase could be related to observed variance of the horizontal wind direction (meandering). For ground-level releases the effective sigma-z values were 16 times greater than the corresponding values from the Pasquill--Gifford curves. Measured ground-level axial concentrations were about 75 times smaller than predicted by the Gaussian diffusion equation for a ground-level release when Pasquill--Gifford values of sigma-y and sigma-z were used

  5. Computer Modeling of the Effects of Atmospheric Conditions on Sound Signatures

    2016-02-01

    simulation. 11 5. References 1. Attenborough K. Sound propagation in the atmosphere. In: Rossing TD, editor. Springer handbook of...ARL-TR-7602 ● FEB 2016 US Army Research Laboratory Computer Modeling of the Effects of Atmospheric Conditions on Sound ...Laboratory Computer Modeling of the Effects of Atmospheric Conditions on Sound Signatures by Sarah Wagner Science and Engineering Apprentice

  6. Mars Atmosphere Effects on Arc Welds: Phase 1

    Courtright, Z. S.

    2016-01-01

    while on the surface of Mars. The Orion capsule is made primarily of AA2219-T87, and the water filtration system is primarily Ti-6Al-4V, so the effect of the Mars environment on welding those materials must be known to reduce potential mission risk. GTAW is a portable process that can weld a versatile group of metals, so it has many potential applications for welding on Mars. Thus, missions to colonize Mars will depend on the capability to weld a strong, leak-tight joint. Metals are also likely to be used in support structures made of a lightweight and durable material. For this reason, it is important to understand the implications of welding in a Mars environment. A comparison of the Martian and terrestrial atmospheres are provided in table 1. Based on the elemental compositions, simulation of the Martian atmosphere can be made using primarily CO2 gas.

  7. NECTAr0, a new high speed digitizer ASIC for the Cherenkov telescope array

    Delagnes, E.; Glicenstein, J.F.; Guilloux, F.; Bolmont, J.; Corona, P.; Naumann, C.L.; Nayman, P.; Tavemet, J.P.; Toussenel, F.; Vincent, P.; Dzahini, D.; Rarbi, F.; Feinstein, F.; Vorobiov, S.; Gascon, D.; Sanuy, A.

    2011-01-01

    H.E.S.S. and MAGIC experiments have demonstrated the high level of maturity of Imaging Atmospheric Cherenkov Telescopes (IACTs) dedicated to very-high-energy gamma ray astronomy domain. The astro-particle physics community is preparing the next generation of instruments, with sensitivity improved by an order of magnitude in the 10 GeV to 100 TeV range. To reach this goal, the Cherenkov Telescope Array (CTA) will consist in an array of 50-100 dishes of various sizes and various spacing, each equipped with a camera, made of few thousands fast photo-detectors and its associated front-end electronics. The total number of electronics channels will be larger than 100,000 to be compared to the total of 6,000 channels of the 5-telescopes H.E.S.S.-I H.E.S.S.-II array. To decrease the overall CTA cost, a consequent effort should be done to lower the cost of the electronics while keeping performance at least as good as the one demonstrated on the current experiments and simplifying its maintenance. This will be allowed by mass production, use of standardized modules and integration of front-end functions in ASICs. The 3-year NECTAr program started in 2009 addresses these two topics. Its final aim is to develop and test a demonstrator module of a generic CTA camera. The paper is mainly focused on one of the main components of this module, the NECTAr ASIC which samples the photo-detector signal in a circular analog memory at several GSPS and digitizes it over 12 bits after having received an external trigger. (authors)

  8. Velocity determination of neutron-rich projectile fragments with a ring-imaging Cherenkov detector

    Zeitelhack, K.

    1992-11-01

    For the velocity determination of relativistic heavy ions (A>100) in the energy range 300A.MeV ≤ E kin ≤ 2A.GeV a highly resolving, compact ring-imaging Cherenkov counter with large dynamical measurement range was developed. The Cherenkov light cone emitted in the flight of a relativistic heavy ion by a liquid layer (C 6 F 14 ) is focused on the entrance window of a one-dimensional position-resolving VUV-sensitive photon detector. This gas detector is operated at atmospheric pressure with a mixture of 90% methane and 10% isobutane with 0.04% TMAE as photosensitive admixture. For 725A.MeV 129 Xe ions a velocity resolution Δβ/β=1.8.10 -3 and a nuclear charge-number resolution ΔZ/Z=5.1.10 -2 was reached. The over the photon energy range 5.4 eV ≤ E γ ≤ 7.2 eV averaged detection efficiency of the detector system was determined to ε tot =2.8%>. At the 0deg magnet spectrometer Fragmentseparator of the GSI Darmstadt the RICH detector was for the first time applied for the identification of nuclear charge number and mass of heavy relativistic projectile fragments. In the experiment the production cross sections of very neutron-rich nuclei by fragmentation of 136 Xe projectiles in the reaction 76A.MeV 136 Xe on 27 Al were determined. From the measured production erates for the production of the double-magic nucleus 132 Zn in this reaction a cross section of σ=(0.4± 0.3 0.6 ) μbarn can be extrapolated. (orig./HSI) [de

  9. Development of a SiPM Camera for a Schwarzschild-Couder Cherenkov Telescope for the Cherenkov Telescope Array

    Otte, A N; Dickinson, H.; Funk, S.; Jogler, T.; Johnson, C.A.; Karn, P.; Meagher, K.; Naoya, H.; Nguyen, T.; Okumura, A.; Santander, M.; Sapozhnikov, L.; Stier, A.; Tajima, H.; Tibaldo, L.; Vandenbroucke, J.; Wakely, S.; Weinstein, A.; Williams, D.A.

    2015-01-01

    We present the development of a novel 11328 pixel silicon photomultiplier (SiPM) camera for use with a ground-based Cherenkov telescope with Schwarzschild-Couder optics as a possible medium-sized telescope for the Cherenkov Telescope Array (CTA). The finely pixelated camera samples air-shower images with more than twice the optical resolution of cameras that are used in current Cherenkov telescopes. Advantages of the higher resolution will be a better event reconstruction yielding improved background suppression and angular resolution of the reconstructed gamma-ray events, which is crucial in morphology studies of, for example, Galactic particle accelerators and the search for gamma-ray halos around extragalactic sources. Packing such a large number of pixels into an area of only half a square meter and having a fast readout directly attached to the back of the sensors is a challenging task. For the prototype camera development, SiPMs from Hamamatsu with through silicon via (TSV) technology are used. We give ...

  10. Non-equilibrium synergistic effects in atmospheric pressure plasmas.

    Guo, Heng; Zhang, Xiao-Ning; Chen, Jian; Li, He-Ping; Ostrikov, Kostya Ken

    2018-03-19

    Non-equilibrium is one of the important features of an atmospheric gas discharge plasma. It involves complicated physical-chemical processes and plays a key role in various actual plasma processing. In this report, a novel complete non-equilibrium model is developed to reveal the non-equilibrium synergistic effects for the atmospheric-pressure low-temperature plasmas (AP-LTPs). It combines a thermal-chemical non-equilibrium fluid model for the quasi-neutral plasma region and a simplified sheath model for the electrode sheath region. The free-burning argon arc is selected as a model system because both the electrical-thermal-chemical equilibrium and non-equilibrium regions are involved simultaneously in this arc plasma system. The modeling results indicate for the first time that it is the strong and synergistic interactions among the mass, momentum and energy transfer processes that determine the self-consistent non-equilibrium characteristics of the AP-LTPs. An energy transfer process related to the non-uniform spatial distributions of the electron-to-heavy-particle temperature ratio has also been discovered for the first time. It has a significant influence for self-consistently predicting the transition region between the "hot" and "cold" equilibrium regions of an AP-LTP system. The modeling results would provide an instructive guidance for predicting and possibly controlling the non-equilibrium particle-energy transportation process in various AP-LTPs in future.

  11. Atmospheric Pressure Effect of Retained Gas in High Level Waste

    Weber, A.H.

    1999-01-01

    Isolated high level waste tanks in H-Area have unexplained changes in waste-level which have been attributed to environmental effects including pressure, temperature, and relative humidity. Previous studies at SRS have considered waste-level changes from causes not including the presence of gas in the salt cake. This study was undertaken to determine the effect of atmospheric pressure on gas in the salt cake and resultant changes in the supernate level of Tank 41H, and to model that effect if possible. A simple theory has been developed to account for changes in the supernate level in a high level waste tank containing damp salt cake as the response of trapped gases to changes in the ambient pressure. The gas is modeled as an ideal gas retained as bubbles within the interstitial spaces in the salt cake and distributed uniformly throughout the tank. The model does not account for consistent long term increases or decreases in the tank level. Any such trend in the tank level is attributed to changes in the liquid content in the tank (from condensation, evaporation, etc.) and is removed from the data prior to the void estimation. Short term fluctuations in the tank level are explained as the response of the entrained gas volume to changes in the ambient pressure. The model uses the response of the tank level to pressure changes to estimate an average void fraction for the time period of interest. This estimate of the void is then used to predict the expected level response. The theory was applied to three separate time periods of the level data for tank 41H as follows: (1) May 3, 1993 through August 3, 1993, (2) January 23, 1994 through April 21, 1994, and (3) June 4, 1994 through August 24, 1994. A strong correlation was found between fluctuations in the tank level and variations in the ambient pressure. This correlation is a clear marker of the presence of entrained gases in the tank. From model calculations, an average void fraction of 11 percent was estimated to

  12. Modeling of inverse Cherenkov laser acceleration with axicon laser-beam focusing

    Romea, R.D.; Kimura, W.D.

    1990-01-01

    Acceleration of free electrons by the inverse Cherenkov effect using radially polarized laser light focused through an axicon [J. P. Fontana and R. H. Pantell, J. Appl. Phys. 54, 4285 (1983)] has been studied utilizing a Monte Carlo computer simulation and further theoretical analysis. The model includes effects, such as scattering of the electrons by the gas, and diffraction and interference effects of the axicon laser beam, that were not included in the original analysis of Fontana and Pantell. Its accuracy is validated using available experimental data. The model results show that effective acceleration is possible even with the effects of scattering. Sample results are given. The analysis includes examining the issues of axicon focusing, phase errors, energy gain, phase slippage, focusing of the e beam, and emittance growth

  13. Application of Cherenkov light observation to reactor measurements (3). Evaluation of spent fuel elements of LWRs with Cherenkov light estimation system

    Yamamoto, Keiichi; Takeuchi, Tomoaki; Tsuchiya, Kunihiko; Hayashi, Takayasu; Kosuge, Fumiaki

    2016-11-01

    Development of the reactor measurement system has been carried out to obtain the real-time in-core nuclear and thermal information, where the quantitative measurement of brightness of Cherenkov light was investigated. The system would be applied as a monitoring system in severe accidents and for the advanced operation management technology in existing LWRs. This report summarized the modification of Cherenkov light estimation system described JAEA-Testing 2015-001 and the result of the burn-up evaluation by Cherenkov light image emitted from spent fuel elements of LWRs with the modified system. (author)

  14. Effects of meteorite impacts on the atmospheric evolution of Mars.

    Pham, Lê Binh San; Karatekin, Ozgür; Dehant, Véronique

    2009-01-01

    Early in its history, Mars probably had a denser atmosphere with sufficient greenhouse gases to sustain the presence of stable liquid water at the surface. Impacts by asteroids and comets would have played a significant role in the evolution of the martian atmosphere, not only by causing atmospheric erosion but also by delivering material and volatiles to the planet. We investigate the atmospheric loss and the delivery of volatiles with an analytical model that takes into account the impact simulation results and the flux of impactors given in the literature. The atmospheric loss and the delivery of volatiles are calculated to obtain the atmospheric pressure evolution. Our results suggest that the impacts alone cannot satisfactorily explain the loss of significant atmospheric mass since the Late Noachian (approximately 3.7-4 Ga). A period with intense bombardment of meteorites could have increased the atmospheric loss; but to explain the loss of a speculative massive atmosphere in the Late Noachian, other factors of atmospheric erosion and replenishment also need to be taken into account.

  15. Atmospheric pressure loading effects on Global Positioning System coordinate determinations

    Vandam, Tonie M.; Blewitt, Geoffrey; Heflin, Michael B.

    1994-01-01

    Earth deformation signals caused by atmospheric pressure loading are detected in vertical position estimates at Global Positioning System (GPS) stations. Surface displacements due to changes in atmospheric pressure account for up to 24% of the total variance in the GPS height estimates. The detected loading signals are larger at higher latitudes where pressure variations are greatest; the largest effect is observed at Fairbanks, Alaska (latitude 65 deg), with a signal root mean square (RMS) of 5 mm. Out of 19 continuously operating GPS sites (with a mean of 281 daily solutions per site), 18 show a positive correlation between the GPS vertical estimates and the modeled loading displacements. Accounting for loading reduces the variance of the vertical station positions on 12 of the 19 sites investigated. Removing the modeled pressure loading from GPS determinations of baseline length for baselines longer than 6000 km reduces the variance on 73 of the 117 baselines investigated. The slight increase in variance for some of the sites and baselines is consistent with expected statistical fluctuations. The results from most stations are consistent with approximately 65% of the modeled pressure load being found in the GPS vertical position measurements. Removing an annual signal from both the measured heights and the modeled load time series leaves this value unchanged. The source of the remaining discrepancy between the modeled and observed loading signal may be the result of (1) anisotropic effects in the Earth's loading response, (2) errors in GPS estimates of tropospheric delay, (3) errors in the surface pressure data, or (4) annual signals in the time series of loading and station heights. In addition, we find that using site dependent coefficients, determined by fitting local pressure to the modeled radial displacements, reduces the variance of the measured station heights as well as or better than using the global convolution sum.

  16. Review of specific effects in atmospheric dispersion calculations

    Underwood, B.Y.; Cooper, P.J.; Holloway, N.J.; Kaiser, G.D.; Nixon, W.

    1985-01-01

    This work consists of a series of ten individual review Chapters - written between 1980 and 1983 - together with a summary document linking and overviewing the work. The topics covered are as follows: 'Plume Rise in Nuclear Safety Studies'; 'Dry Deposition'; 'Wet Deposition'; 'Atmospheric Dispersion in Urban Environments'; 'Topographical Effects in Nuclear Safety Studies'; 'Coastal Effects and Transport over Water'; 'Time-Varying Meteorology in Consequence Assessment'; 'Building Effects in Nuclear Safety Studies'; 'Effect of Turning of the Wind with Height on Lateral Dispersion'. Although the reviews are, on the whole, general in approach, emphasis has been given where appropriate to the impact of various phenomena on th assessment of reactor accident consequences. In general the work focusses on the 0-100 km range of distance downwind of the source. The reviews fulfil several functions: they serve as introductions to the subject areas; they outline theoretical and experimental developments; they act as reference documents providing a copious source of references for more detailed investigation of particular points; they raise unresolved technical issues and attempt to indicate principal uncertainties; they point to areas requiring further development. (author)

  17. Atmospheric contamination

    Gruetter, Juerg

    1997-01-01

    It is about the levels of contamination in center America, the population's perception on the problem, effects of the atmospheric contamination, effects in the environment, causes of the atmospheric contamination, possibilities to reduce the atmospheric contamination and list of Roeco Swisscontac in atmospheric contamination

  18. Modeling the effects of atmospheric emissions on groundwater composition

    Brown, T.J.

    1994-01-01

    A composite model of atmospheric, unsaturated and groundwater transport is developed to evaluate the processes determining the distribution of atmospherically derived contaminants in groundwater systems and to test the sensitivity of simulated contaminant concentrations to input parameters and model linkages. One application is to screen specific atmospheric emissions for their potential in determining groundwater age. Temporal changes in atmospheric emissions could provide a recognizable pattern in the groundwater system. The model also provides a way for quantifying the significance of uncertainties in the tracer source term and transport parameters on the contaminant distribution in the groundwater system, an essential step in using the distribution of contaminants from local, point source atmospheric emissions to examine conceptual models of groundwater flow and transport

  19. The forward ring imaging Cherenkov detector of DELPHI

    Adam, W.; Albrecht, E.; Ambec, I.; Augustinus, A.; Barnoux, C.; Bostjancic, B.; Botner, O.; Budziak, A.P.; Caloba, L.P.; Carecchio, P.; Cavalli, P.; Ceelie, L.; Cereseto, R.; Cerutti, G.; Dahl-Jensen, E.; Dam, P.; Damgaard, G.; Koning, N. de; De la Vega, A.S.; Dimitriou, N.; Dulinski, W.; Eek, L.O.; Ekeloef, T.; Erikson, J.; Florek, A.; Florek, B.; Fontanelli, F.; Fontenille, A.; Galuszka, K.; Garcia, J.; Gracco, V.; Hallgren, A.; Hao, W.; Henkes, T.; Isenhower, D.; Johansson, H.; Karvelas, E.; Kindblom, P.; Koene, B.; Korporaal, A.; Kostarakis, P.; Lenzen, G.; Lindqvist, L.E.; Lorenz, P.; Loukas, D.; Lund-Jensen, B.; Maltezos, A.; Markou, A.; Mattsson, L.; Medbo, J.; Michalowski, J.; Montano, F.; Nielsen, B.S.; Ostler, J.M.; Pakonski, K.; Perdikis, C.; Polok, G.; Robohm, A.; Sajot, G.; Sannino, M.; Saragas, E.; Schyns, E.; Squarcia, S.; Stavropoulos, G.; Stodulski, M.; Stopa, Z.; Thadome, J.; Theodosiou, G.E.; Traspedini, L.; Turala, M.; Ullaland, O.; Waerm, A.; Werner, J.; Xyroutsikos, S.; Zavrtanik, M.; Zevgolatakos, E.

    1994-01-01

    The Forward Ring Imaging Cherenkov detector of the DELPHI experiment at LEP provides hadron identification at polar angles 15 6 F 14 and a volume of gaseous C 4 F 10 , in combination provide coverage of momenta up to 40 GeV/c. A single array of photosensitive Time Projection Chambers registers the impact points of ultraviolet photons from both radiators. The design of the detector and of its readout system is described. First results obtained with a partly installed detector are reported. (orig.)

  20. Cherenkov Radiation from a Pseudospark-sourced Electron Beam

    Phelps, A.D.R.; Yin, H.; Cross, A.W.; He, W.; Ronald, K.

    2003-01-01

    Electron beam generation from a multi-gap pseudospark discharge was investigated. A pseudospark-sourced electron beam has two phases, an initial hollow cathode phase (HCP) beam followed by a conductive phase (CP) beam. The beam brightness was measured by a field-free collimator to be 109 and 1011 Am-2rad-2 for the hollow cathode phase (HCP) beam and the conductive phase (CP) beam respectively. The initial HCP beam from an eight-gap pseudospark discharge was applied in a Cherenkov interaction between the electron beam and the TM01 mode of a 60-cm long alumina-lined waveguide. It was found experimentally that significant microwave radiation was generated only when the dielectric was present in the interaction space. If there was no dielectric in the cylindrical waveguide, then a very small background microwave output was detected even when the guide B-field was absent. This demonstrated, in conjunction with the observation that the microwave output signal was independent of the guide magnetic field over the range 0.13 to 0.26 T, that the radiation from the experiment was due to the Cherenkov interaction mechanism. In addition, two components of the microwave pulse were observed corresponding to the two energy components of the electron beam during the pseudospark discharge breakdown. These results demonstrated that the microwave radiation was generated by Cherenkov amplification of the broadband emission from the pseudospark discharge itself. A background signal level of around 100 W was measured in the frequency range 20 - 50 GHz with a percentage of (2.7 ± 0.6)% in the frequency range 25.5 - 28.6 GHz, when the dielectric lining was removed from the maser. The frequency of the microwave output after the Cherenkov maser interaction was measured to be mainly around 25.5 GHz and the dominating mode was identified as being TM01. The duration of the microwave pulse was approximately 80 ns, with a peak power of around 2 ± 0.2 kW. The gain of this amplifier was measured

  1. Getting the traces (FADCs) of a water Cherenkov detector signal

    Ponce, E.; Salazar, H.; Martinez, O.; Moreno, E.

    2003-01-01

    In this work we present the electronics developed into a complete data acquisition system (DAS) for a water Cherenkov detector (WCD) in order to detect cosmic rays with energies from 1 x 1014 to 1 x 1016 eV. The components are: a high voltage source, a bleeder circuit for each photomultiplier, an electronic unit to amplify, compare, determine coincidence and sum the signals produced by the PMTs, a control circuit to digitalize and store the information corresponding to a valid event and finally an interface to a PC to record data for further analysis. The sampling rate of the system is 40 MHz

  2. Cherenkov Ring Imaging Detector front-end electronics

    Antilogus, P.; Aston, D.; Bienz, T.; Bird, F.; Dasu, S.; Dunwoodie, W.; Hallewell, G.; Kawahara, H.; Kwon, Y.; Leith, D.; Marshall, D.; Muller, D.; Nagamine, T.; Oxoby, G.; Ratcliff, B.; Rensing, P.; Schultz, D.; Shapiro, S.; Simopoulos, C.; Solodov, E.; Suekane, F.; Toge, N.; Va'Vra, J.; Williams, S.; Wilson, R.J.; Whitaker, J.S.; Bean, A.; Caldwell, D.; Duboscq, J.; Huber, J.; Lu, A.; Mathys, L.; McHugh, S.; Morrison, R.; Witherell, M.; Yellin, S.; Coyle, P.; Coyne, D.; Spencer, E.; d'Oliveira, A.; Johnson, R.A.; Martinez, J.; Nussbaum, M.; Santha, A.K.S.; Shoup, A.; Stockdale, I.; Jacques, P.; Plano, R.; Stamer, P.; Abe, K.; Hasegawa, K.; Yuta, H.

    1990-10-01

    The SLD Cherenkov Ring Imaging Detector use a proportional wire detector for which a single channel hybrid has been developed. It consists of a preamplifier, gain selectable amplifier, load driver amplifier, power switching, and precision calibrator. For this hybrid, a bipolar, semicustom integrated circuit has been designed which includes video operational amplifiers for two of the gain stages. This approach allows maximization of the detector volume, allows DC coupling, and enables gain selection. System tests show good noise performance, calibration precision, system linearity, and signal shape uniformity over the full dynamic range. 10 refs., 8 figs

  3. THGEM based photon detector for Cherenkov imaging applications

    Alexeev, M; Bradamante, F; Bressan, A; Chiosso, M; Ciliberti, P; Croci, G; Colantoni, M L; Dalla Torre, S; Duarte Pinto, S; Denisov, O; Diaz, V; Ferrero, A; Finger, M; Finger, M Jr; Fischer, H; Giacomini, G; Giorgi, M; Gobbo, B; Heinsius, F H; Herrmann, F; Jahodova, V; Königsmann, K; Lauser, L; Levorato, S; Maggiora, A; Martin, A; Menon, G; Nerling, F; Panzieri, D; Pesaro, G; Polak, J; Rocco, E; Ropelewski, L; Sauli, F; Sbrizzai, G; Schiavon, P; Schill, C; Schopferer, S; Slunecka, M; Sozzi, F; Steiger, L; Sulc, M; Takekawa, S; Tessarotto, F; Wollny, H

    2010-01-01

    We are developing a single photon detector for Cherenkov imaging counters. This detector is based on the use of THGEM electron multipliers in a multilayer design. The major goals of our project are ion feedback suppression down to a few per cent, large gain, fast response, insensitivity to magnetic fields, and a large detector size. We report about the project status and perspectives. In particular, we present a systematic study of the THGEM response as a function of geometrical parameters, production techniques and the gas mixture composition. The first figures obtained from measuring the response of a CsI coated THGEM to single photons are presented.

  4. Accounting for Chromatic Atmospheric Effects on Barycentric Corrections

    Blackman, Ryan T.; Szymkowiak, Andrew E.; Fischer, Debra A.; Jurgenson, Colby A., E-mail: ryan.blackman@yale.edu [Department of Astronomy, Yale University, 52 Hillhouse Avenue, New Haven, CT 06511 (United States)

    2017-03-01

    Atmospheric effects on stellar radial velocity measurements for exoplanet discovery and characterization have not yet been fully investigated for extreme precision levels. We carry out calculations to determine the wavelength dependence of barycentric corrections across optical wavelengths, due to the ubiquitous variations in air mass during observations. We demonstrate that radial velocity errors of at least several cm s{sup −1} can be incurred if the wavelength dependence is not included in the photon-weighted barycentric corrections. A minimum of four wavelength channels across optical spectra (380–680 nm) are required to account for this effect at the 10 cm s{sup −1} level, with polynomial fits of the barycentric corrections applied to cover all wavelengths. Additional channels may be required in poor observing conditions or to avoid strong telluric absorption features. Furthermore, consistent flux sampling on the order of seconds throughout the observation is necessary to ensure that accurate photon weights are obtained. Finally, we describe how a multiple-channel exposure meter will be implemented in the EXtreme PREcision Spectrograph (EXPRES).

  5. Effects of Mars Atmosphere on Arc Welds: Phase 2

    Courtright, Z. S.

    2018-01-01

    Gas tungsten arc welding (GTAW) is a vital fusion welding process widely used throughout the aerospace industry. Its use may be critical for the repair or manufacture of systems, rockets, or facilities on the Martian surface. Aluminum alloy AA2219-T87 and titanium alloy Ti-6Al-4V butt welds have been investigated for weldability and weld properties in a simulated Martian gas environment. The resulting simulated Martian welds were compared to welds made in a terrestrial atmosphere, all of which used argon shielding gas. It was found that GTAW is a process that may be used in a Martian gas environment, not accounting for pressure and gravitational effects, as long as adequate argon shielding gas is used to protect the weld metal. Simulated Martian welds exhibited higher hardness in all cases and higher tensile strength in the case of AA2219-T87. This has been attributed to the absorption of carbon into the fusion zone, causing carbide precipitates to form. These precipitates may act to pin dislocations upon tensile testing of AA2219-T87. Dissolved carbon may have also led to carburization, which may have caused the increase in hardness within the fusion zone of the welds. Based on the results of this experiment and other similar experiments, GTAW appears to be a promising process for welding in a Martian gas environment. Additional funding and experimentation is necessary to determine the effects of the low pressure and low gravity environment found on Mars on GTAW.

  6. Exposures to atmospheric effects in the entertainment industry.

    Teschke, Kay; Chow, Yat; van Netten, Chris; Varughese, Sunil; Kennedy, Susan M; Brauer, Michael

    2005-05-01

    Theatrical fogs are commonly used in the entertainment industry to create special atmospheric effects during filming and live productions. We examined exposures to mineral oil-and glycol-based theatrical fogs to determine what fluids and effects were commonly used, to measure the size distributions of the aerosols, and to identify factors associated with personal exposure levels. In nonperformance jobs in a range of production types (television, film, live theater, and concerts),we measured airborne concentrations of inhalable aerosol,aldehydes, and polycyclic aromatic hydrocarbons, and collected observations about the sites and tasks performed. Both mineral oil and glycols were observed in use on about one-half the production days in the study. The most common effect produced was a generalized haze over the entire set. Mean personal inhalable aerosol concentrations were 0.70 mg/m3(range 0.02 to 4.1). The mean proportion of total aerosol mass less than 3.5 microns in aerodynamic diameter was 61%. Exposures were higher when mineral oils, rather than glycols, were used to generate fogs. Higher exposures were also associated with movie and television productions, with using more than one fog machine, with increased time spent in visible fog, and for those employed as "grips." Decreased exposures were associated with increasing room temperature, with increasing distance from fog machines, and for those employed as "sound technicians." Exposures to theatrical fogs are just beginning to be measured. It is important to consider these exposures in light of any health effects observed, since existing occupational exposure limits were developed in other industries where the aerosol composition differs from that of theatrical fogs.

  7. Combined effects of γ-ray radiation and high atmospheric pressure on peripheral blood lymphocytes

    Zhu Bingchai; Lu Jiaben; Wang Zongwu; Chen Tiehe

    1989-01-01

    The combined effects of γ-ray radiation and high atmospheric pressure on chromosome aberration, micronucleus and transformation frequency in peripheral blood lymphocytes have been studied. The results indicated that there were no significant influence for effects of high atmospheric pressure on chromosome aberrations, transformation frequency in peripheral blood lymphocytes induced γ-ray radiation, and that high atmospheric pressure increased effect of micronucleus in human peripheral blood lymphocytes in vitro induced γ-ray radiation

  8. Effects in atmospheric electricity daily variation controlled by solar wind

    Ptitsyna, N.G.; Tyasto, M.I.; Levitin, A.E.; Gromova, L.A.; Tuomi, T.; AN SSSR, Moscow

    1995-01-01

    An analysis of fair weather atmospheric electricity, one of the environmental factors which affects the biosphere, is conducted. A distinct difference in the diurnal variation of atmospheric electric field at Helsinki is found between disturbed and extremely quiet conditions in the magnetosphere in winter before midnight. The comparison with the numerical model of the ionospheric electric field based on the solar wind parameters reveals that the maximum contribution of the magnetospheric-ionospheric generator to atmospheric electric field is about 100-150 v/m which assumes values of about 30% of the surface field. 8 refs.; 2 figs

  9. Health effects of acid aerosols formed by atmospheric mixtures

    Kleinman, M.T.; Phalen, R.F.; Mautz, W.J.; Mannix, R.C.; McClure, T.R.; Crocker, T.T.

    1989-01-01

    Under ambient conditions, sulfur and nitrogen oxides can react with photochemical products and airborne particles to form acidic vapors and aerosols. Inhalation toxicological studies were conducted, exposing laboratory animals, at rest and during exercise, to multicomponent atmospheric mixtures under conditions favorable to the formation of acidic reaction products. Effects of acid and ozone mixtures on early and late clearance of insoluble radioactive particles in the lungs of rats appeared to be dominated by the oxidant component (i.e., the mixture did cause effects that were significantly different from those of ozone alone). Histopathological evaluations showed that sulfuric acid particles alone did not cause inflammatory responses in centriacinar units of rat lung parenchyma (expressed in terms of percent lesion area) but did cause significant damage (cell killing followed by a wave of cell replication) in nasal respiratory epithelium, as measured by uptake of tritiated thymidine in the DNA of replicating cells. Mixtures of ozone and nitrogen dioxide, which form nitric acid, caused significant inflammatory responses in lung parenchyma (in excess of effects seen in rats exposed to ozone alone), but did not damage nasal epithelium. Mixtures containing acidic sulfate particles, ozone, and nitrogen dioxide damaged both lung parenchyma and nasal epithelia. In rats exposed at rest, the response of the lung appeared to be dominated by the oxidant gas-phase components, while responses in the nose were dominated by the acidic particles. In rats exposed at exercise, however, mixtures of ozone and sulfuric acid particles significantly (2.5-fold) elevated the degree of lung lesion formation over that seen in rats exposed to ozone alone under an identical exercise protocol

  10. Atmospheric Water Harvesting: Role of Surface Wettability and Edge Effect

    Jin, Yong

    2017-06-23

    Atmospheric water is emerging as an important potable water source. The present work experimentally and theoretically investigates water condensation and collection on flat surfaces with contrasting contact angles and contact angle hysteresis (CAH) to elucidate their roles on water mass collection efficiency. The experimental results indicate that a hydrophilic surface promotes nucleation and individual droplets growth, and a surface with a low CAH tends to let a smaller droplet to slide down, but the overall water mass collection efficiency is independent of both surface contact angle and CAH. The experimental results agree well with our theoretical calculations. During water condensation, a balance has to be struck between single droplet growth and droplet density on a surface so as to maintain a constant water droplet surface coverage ratio, which renders the role of both surface wettability and hysteresis insignificant to the ultimate water mass collection. Moreover, water droplets on the edges of a surface grow much faster than those on the non-edge areas and thus dominate the contribution to the water mass collection by the entire surface, directly pointing out the very important role of edge effect on water condensation and collection.

  11. Atmospheric effects of heat release at large power plants

    Kikuchi, Yukio

    1979-01-01

    In power plants, the thermal efficiency of generating electricity is generally 1/3, the rest 2/3 being carried away by cooling water. To release the heat, there are three alternative methods; i.e. cooling water released into sea, cooling water released into a cooling pond, and cooling of such water with a cooling tower. In the third method, cooling towers are stacks of 10m -- 80m bore, and warm cooling water flowing on the side wall is cooled with atmospheric air. The resultant heated air is discharged as plume from their top. Upon condensation, it becomes visible and then leads to the formation of clouds. In this manner, the weather around the sites of power plants is affected, such as reduction of insolation reaching ground and increase in precipitation. The following matters are described: cooling towers; phenomena and prediction methods of visible plume, cloud formation, increase of precipitation and deposition of drifting waterdrops; and effects of the group of power plants. (J.P.N.)

  12. Prompt atmospheric neutrino fluxes: perturbative QCD models and nuclear effects

    Bhattacharya, Atri [Department of Physics, University of Arizona,1118 E. 4th St. Tucson, AZ 85704 (United States); Space sciences, Technologies and Astrophysics Research (STAR) Institute,Université de Liège,Bât. B5a, 4000 Liège (Belgium); Enberg, Rikard [Department of Physics and Astronomy, Uppsala University,Box 516, SE-75120 Uppsala (Sweden); Jeong, Yu Seon [Department of Physics and IPAP, Yonsei University,50 Yonsei-ro Seodaemun-gu, Seoul 03722 (Korea, Republic of); National Institute of Supercomputing and Networking, KISTI,245 Daehak-ro, Yuseong-gu, Daejeon 34141 (Korea, Republic of); Kim, C.S. [Department of Physics and IPAP, Yonsei University,50 Yonsei-ro Seodaemun-gu, Seoul 03722 (Korea, Republic of); Reno, Mary Hall [Department of Physics and Astronomy, University of Iowa,Iowa City, Iowa 52242 (United States); Sarcevic, Ina [Department of Physics, University of Arizona,1118 E. 4th St. Tucson, AZ 85704 (United States); Department of Astronomy, University of Arizona,933 N. Cherry Ave., Tucson, AZ 85721 (United States); Stasto, Anna [Department of Physics, 104 Davey Lab, The Pennsylvania State University,University Park, PA 16802 (United States)

    2016-11-28

    We evaluate the prompt atmospheric neutrino flux at high energies using three different frameworks for calculating the heavy quark production cross section in QCD: NLO perturbative QCD, k{sub T} factorization including low-x resummation, and the dipole model including parton saturation. We use QCD parameters, the value for the charm quark mass and the range for the factorization and renormalization scales that provide the best description of the total charm cross section measured at fixed target experiments, at RHIC and at LHC. Using these parameters we calculate differential cross sections for charm and bottom production and compare with the latest data on forward charm meson production from LHCb at 7 TeV and at 13 TeV, finding good agreement with the data. In addition, we investigate the role of nuclear shadowing by including nuclear parton distribution functions (PDF) for the target air nucleus using two different nuclear PDF schemes. Depending on the scheme used, we find the reduction of the flux due to nuclear effects varies from 10% to 50% at the highest energies. Finally, we compare our results with the IceCube limit on the prompt neutrino flux, which is already providing valuable information about some of the QCD models.

  13. Effects of the different atmospheric steam curing processes on the ...

    hardness when exposed to different atmospheric steam curing temperatures. ... Use of self-compacting concretes (SCCs) lowered the noise level on the ... Although maximum temperature limit values in curing locations should be from 40 to ...

  14. Atmospheric Water Harvesting: Role of Surface Wettability and Edge Effect

    Jin, Yong; Zhang, Lianbin; Wang, Peng

    2017-01-01

    Atmospheric water is emerging as an important potable water source. The present work experimentally and theoretically investigates water condensation and collection on flat surfaces with contrasting contact angles and contact angle hysteresis (CAH

  15. INFN Camera demonstrator for the Cherenkov Telescope Array

    Ambrosi, G; Aramo, C.; Bertucci, B.; Bissaldi, E.; Bitossi, M.; Brasolin, S.; Busetto, G.; Carosi, R.; Catalanotti, S.; Ciocci, M.A.; Consoletti, R.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Lotto, B.; de Palma, F.; Desiante, R.; Di Girolamo, T.; Di Giulio, C.; Doro, M.; D'Urso, D.; Ferraro, G.; Ferrarotto, F.; Gargano, F.; Giglietto, N.; Giordano, F.; Giraudo, G.; Iacovacci, M.; Ionica, M.; Iori, M.; Longo, F.; Mariotti, M.; Mastroianni, S.; Minuti, M.; Morselli, A.; Paoletti, R.; Pauletta, G.; Rando, R.; Fernandez, G. Rodriguez; Rugliancich, A.; Simone, D.; Stella, C.; Tonachini, A.; Vallania, P.; Valore, L.; Vagelli, V.; Verzi, V.; Vigorito, C.

    2015-01-01

    The Cherenkov Telescope Array is a world-wide project for a new generation of ground-based Cherenkov telescopes of the Imaging class with the aim of exploring the highest energy region of the electromagnetic spectrum. With two planned arrays, one for each hemisphere, it will guarantee a good sky coverage in the energy range from a few tens of GeV to hundreds of TeV, with improved angular resolution and a sensitivity in the TeV energy region better by one order of magnitude than the currently operating arrays. In order to cover this wide energy range, three different telescope types are envisaged, with different mirror sizes and focal plane features. In particular, for the highest energies a possible design is a dual-mirror Schwarzschild-Couder optical scheme, with a compact focal plane. A silicon photomultiplier (SiPM) based camera is being proposed as a solution to match the dimensions of the pixel (angular size of ~ 0.17 degrees). INFN is developing a camera demonstrator made by 9 Photo Sensor Modules (PSMs...

  16. NECTAR: New electronics for the Cherenkov Telescope Array

    Naumann, Christopher Lindsay; Bolmont, J.; Corona, P.; Delagnes, E.; Dzahini, D.; Feinstein, F.; Gascon, D.; Glicenstein, J.-F.; Nayman, P.; Rarbi, F.; Ribo, M.; Sanuy, A.; Siero, X.; Tavernet, J.-P.; Toussenel, F.; Vincent, P.; Vorobiov, S.

    2012-12-01

    The international CTA consortium is currently in the preparatory phase for the development of the next-generation Cherenkov Telescope Array (CTA [1]), based on the return of experience from the three major current-generation arrays H.E.S.S., MAGIC and VERITAS. To achieve an unprecedented sensitivity and energy range for TeV gamma rays, a new kind of flexible and powerful yet inexpensive front-end hardware will be required for the order of 105 channels of photodetectors in up to 100 telescopes. One possible solution is the NECTAr (New Electronics for the Cherenkov Telescope Array) system, based on the integration of as much as possible of the front-end electronics (amplifiers, fast analogue samplers, memory and ADCs) into a single ASIC for very fast readout performance and a significant reduction of the cost and the lower consumption per channel, while offering a high degree of flexibility both for the triggering and the readout of the telescope. The current status of its development is presented, along with newest results from measurements and simulation studies.

  17. The On-Site Analysis of the Cherenkov Telescope Array

    Bulgarelli, Andrea; Zoli, Andrea; Aboudan, Alessio; Rodríguez-Vázquez, Juan José; De Cesare, Giovanni; De Rosa, Adriano; Maier, Gernot; Lyard, Etienne; Bastieri, Denis; Lombardi, Saverio; Tosti, Gino; Bergamaschi, Sonia; Beneventano, Domenico; Lamanna, Giovanni; Jacquemier, Jean; Kosack, Karl; Antonelli, Lucio Angelo; Boisson, Catherine; Borkowski, Jerzy; Buson, Sara; Carosi, Alessandro; Conforti, Vito; Colomé, Pep; Reyes, Raquel de los; Dumm, Jon; Evans, Phil; Fortson, Lucy; Fuessling, Matthias; Gotz, Diego; Graciani, Ricardo; Gianotti, Fulvio; Grandi, Paola; Hinton, Jim; Humensky, Brian; Inoue, Susumu; Knödlseder, Jürgen; Flour, Thierry Le; Lindemann, Rico; Malaguti, Giuseppe; Markoff, Sera; Marisaldi, Martino; Neyroud, Nadine; Nicastro, Luciano; Ohm, Stefan; Osborne, Julian; Oya, Igor; Rodriguez, Jerome; Rosen, Simon; Ribo, Marc; Tacchini, Alessandro; Schüssler, Fabian; Stolarczyk, Thierry; Torresi, Eleonora; Testa, Vincenzo; Wegner, Peter

    2015-01-01

    The Cherenkov Telescope Array (CTA) observatory will be one of the largest ground-based very high-energy gamma-ray observatories. The On-Site Analysis will be the first CTA scientific analysis of data acquired from the array of telescopes, in both northern and southern sites. The On-Site Analysis will have two pipelines: the Level-A pipeline (also known as Real-Time Analysis, RTA) and the level-B one. The RTA performs data quality monitoring and must be able to issue automated alerts on variable and transient astrophysical sources within 30 seconds from the last acquired Cherenkov event that contributes to the alert, with a sensitivity not worse than the one achieved by the final pipeline by more than a factor of 3. The Level-B Analysis has a better sensitivity (not be worse than the final one by a factor of 2) and the results should be available within 10 hours from the acquisition of the data: for this reason this analysis could be performed at the end of an observation or next morning. The latency (in part...

  18. Spectrometer of Cherenkov radiation rings with hodoscopic photomultipliers

    Abramov, V.V.; Alekseev, A.V.; Baldin, B.Yu.

    1983-01-01

    Characteristics of SKOCH Cherenkov radiation ring spectrometer intended for identification of π- and K-mesons and protons in a wide divergent beam in the pulse range of 5.5-30 GeV/s are investigated. The spectrometer detecting system is based on using the hodoscopic photoelectron multipliers (HPEM). The HPEM specific feature is that they have an extended cathode and permit to determine the coordinate of an incident photon by measuring the time of photoelectron drift to a dinode system. The spectrometer has been tested at the FODS facility in the secondary particle beam with angular divergence equal to 16x6 mrad and aperture of 400x200 mm in the pulse range of 6-20 GeV/s. The range of Cherenkov radiation angle detection is 40-100 mrad which corresponds to the particle velocity range of 0.996-1. The angular and radial aperture is 30 mrad, the diameter is 420 mm. The obtained velocity resolution is 6x10 -5

  19. Workshop on Non-Imaging Cherenkov at High Energy

    2013-01-01

    The non-Imaging Cherenkov air shower measurement technique holds great promise in furthering our understanding the Knee-to-Ankle region of the cosmic ray spectrum. In particular, this technique offers a unique way to determine the evolution of the cosmic ray nuclear composition, and an example is given by the recent spectrum results of the Tunka Collaboration. With this in mind, we are organizing a workshop, to be held at the University of Utah, to bring together the various practitioners of this cosmic ray measurement technique to share simulations, analyses, detector designs, and past experimental results amongst the community. The workshop will also be in support of our effort, NICHE, to extend the reach of the TA/TALE detector systems down to the Knee. We anticipate that the workshop will result in a white paper on the scientific importance of these high-energy cosmic ray measurements and on using the Cherenkov technique to accomplish them. Our goal is to have contributions from members of the previous ge...

  20. Estimation of primary cosmic ray characteristics with the help of EAS Cherenkov light

    Aleksandrov, L.; Brankova, M.; Kirov, I.; Mishev, A.; Stamenov, J.; Ushev, S.; Mavrodiev, S.

    1999-01-01

    A new method of estimating primary cosmic ray characteristics based on the registration and analysis of EAS Cherenkov light is proposed. The nature, energy and arrival direction of primaries are obtained as a solution of a nonlinear inverse problem. The applied mathematical model is created by analyzing 'Hotovo' telescope experimental data. The behaviour of model parameters is studied using CORSIKA code for the primary energy interval 30 GeV-3 TeV. This method could be applied successfully for a different kind of detector displacements of EAS arrays. Moreover, it is shown that the shower parameter estimation could be obtained more effectively and precisely in the case of detectors displacement according to a Spiral

  1. Massive Cherenkov neutrino facilities?their evolution, their future: Twenty-five years at these International Neutrino Conferences

    Sulak, Lawrence R.

    2005-01-01

    This review traces the evolution of massive water Cherenkov tracking calorimeters. Pioneering concepts, first presented in this conference a quarter of a century ago, have led to 1) IMB, the first large detector (10kT), which was designed primarily to search for proton decay, and secondarily to be sensitive to supernova neutrinos and atmospheric oscillations, and 2) Dumand, an attempt to initiate the search for TeV astrophysical neutrinos with a prototype for a 1 km 3 telescope. The concepts and initial work on IMB influenced subsequent detectors: Kamiokande, Super-K, SNO, and, in part, Kamland. These detectors have to their credit the elucidation of the physics of atmospheric, solar, reactor and supernova neutrinos. With the advent of the K2K beam, controlled accelerator neutrinos confirm the atmospheric studies. The path breaking developments of Dumand now are incorporated in the high-volume Amanda and Antares detectors, as well as their sequels, IceCube and the proposed Cubic Kilometer detector. The future (ultimate?) facilities have new physics challenges: A high-resolution megaton detector, eventually coupled with an intense accelerator neutrino source, is critical for precision studies of neutrino oscillation parameters and for the potential discovery of CP violation in the lepton sector. The Gigaton TeV neutrino telescopes (IceCube and Cubic Kilometer) seek to open high-energy neutrino astronomy, still an elusive goal. (Amanda, IceCube, and UNO, as well as Minos, Icarus and other large neutrino facilities using non-Cherenkov technologies, are treated in other contributions to this volume.)

  2. Atmospheric stability and topography effects on wind turbine performance and wake properties in complex terrain

    Han, Xingxing; Liu, Deyou; Xu, Chang

    2018-01-01

    This paper evaluates the influence of atmospheric stability and topography on wind turbine performance and wake properties in complex terrain. To assess atmospheric stability effects on wind turbine performance, an equivalent wind speed calculated with the power output and the manufacture power...... and topography have significant influences on wind turbine performance and wake properties. Considering effects of atmospheric stability and topography will benefit the wind resource assessment in complex terrain....

  3. Effects of atmospheric deposition of pesticides on terrestrial organisms in the Netherlands

    Jong FMW de; Luttik R; SEC

    2004-01-01

    At present there is much focus on the atmospheric dispersal of pesticides. However, there is very little known about the effects of atmospheric deposition, especially in terrestrial ecosystems. In the study described here, a start has been made to clarify the possible effects on terrestrial

  4. Effects of atmospheric inorganic nitrogen deposition on ocean biogeochemistry

    Krishnamurthy, Aparna; Moore, J. Keith; Zender, Charles S; Luo, Chao

    2007-01-01

     We perform a sensitivity study with the Biogeochemical Elemental Cycling (BEC) ocean model to understand the impact of atmospheric inorganic nitrogen deposition on marine biogeochemistry and air-sea CO2 exchange. Simulations involved examining the response to three different atmospheric inorganic nitrogen deposition scenarios namely, Pre-industrial (22 Tg N/year), 1990s (39 Tg N/year), and an Intergovernmental Panel on Climate Change (IPCC) prediction for 2100, IPCC-A1FI (69 Tg N/year). Glob...

  5. Cherenkov angle and charge reconstruction with the RICH detector of the AMS experiment

    Barão, F; Borges, J; Gonçalves, P; Pimenta, M; Pérez, I

    2003-01-01

    The Alpha Magnetic Spectrometer experiment to be installed on the International Space Station will be equipped with a proximity focusing Ring Imaging Cherenkov (RICH) detector, for measurements of particle electric charge and velocity. In this note, two possible methods for reconstructing the Cherenkov angle and the electric charge with the RICH are discussed. A Likelihood method for the Cherenkov angle reconstruction was applied leading to a velocity determination for protons with a resolution of around 0.1%. The existence of a large fraction of background photons which can vary from event to event implied a charge reconstruction method based on an overall efficiency estimation on an event-by-event basis.

  6. Cherenkov rings from aerogel detected by four large-area hybrid photodiodes

    Bellunato, T.; Braem, A.; Buzykaev, A.R.; Calvi, M.; Chesi, E.; Danilyuk, A.F.; Easo, S.; Jolly, S.; Joram, C.; Kravchenko, E.A.; Liko, D.; Matteuzzi, C.; Musy, M.; Negri, P.; Neufeld, N.; Onuchin, A.P.; Seguinot, J.; Wotton, S.

    2003-01-01

    We report on the results obtained using thick samples of silica aerogel as radiators for a Ring Imaging Cherenkov counter. Four large-diameter hybrid photodiodes with 2048 channels have been used as photon detectors. Pions and protons with momenta ranging from 6 to 10 GeV/c were separated and identified. The number of photoelectrons and the radius of the Cherenkov rings together with the Cherenkov angle resolution were measured. A comparison with a simulation program based on GEANT4 is discussed

  7. CHERENCUBE: Concept definition and implementation challenges of a Cherenkov-based detector block for PET

    Somlai-Schweiger, I.; Ziegler, S. I.

    2015-01-01

    Purpose: A new concept for a depth-of-interaction (DOI) capable time-of-flight (TOF) PET detector is defined, based only on the detection of Cherenkov photons. The proposed “CHERENCUBE” consists of a cubic Cherenkov radiator with position-sensitive photodetectors covering each crystal face. By means of the spatial distribution of the detected photons and their time of arrival, the point of interaction of the gamma-ray in the crystal can be determined. This study analyzes through theoretical calculations and Monte Carlo simulations the potential advantages of the concept toward reaching a Cherenkov-only detector for TOF-PET with DOI capability. Furthermore, an algorithm for the DOI estimation is presented and the requirements for a practical implementation of the proposed concept are defined. Methods: The Monte Carlo simulations consisted of a cubic crystal with one photodetector coupled to each one of the faces of the cube. The sensitive area of the detector matched exactly the crystal size, which was varied in 1 mm steps between 1 × 1 × 1 mm 3 and 10 × 10 × 10 mm 3 . For each size, five independent simulations of ten thousand 511 keV gamma-rays were triggered at a fixed distance of 10 mm. The crystal chosen was PbWO 4 . Its scintillation properties were simulated, but only Cherenkov photons were analyzed. Photodetectors were simulated having perfect photodetection efficiency and infinite time resolution. For every generated particle, the analysis considered its creation process, parent and daughter particles, energy, origin coordinates, trajectory, and time and position of detection. The DOI determination is based on the distribution of the emission time of all photons per event. These values are calculated as a function of the coordinates of detection and origin for every photon. The common origin is estimated by finding the distribution with the most similar emission time-points. Results: Detection efficiency increases with crystal size from 8.2% (1 × 1

  8. Delayed effects of cold atmospheric plasma on vascular cells

    Stoffels, Eva; Roks, Anton J. M.; Deelmm, Leo E.

    2008-01-01

    We investigated the long-term behaviour of vascular cells (endothelial and smooth muscle) after exposure to a cold atmospheric plasma source. The cells were treated through a gas-permeable membrane, in order to simulate intravenous treatment with a gas plasma-filled catheter. Such indirect treatment

  9. A major electronics upgrade for the H.E.S.S. Cherenkov telescopes 1-4

    Giavitto, G; Balzer, A.; Berge, D.; Brun, F.; Chaminade, T.; Delagnes, E.; Fontaine, G.; Füßling, M.; Giebels, B.; Glicenstein, J.F.; Gräber, T.; Hinton, J.A.; Jahnke, A.; Klepser, S.; Kossatz, M.; Kretzschmann, A.; Lefranc, V.; Leich, H.; Lüdecke, H.; Manigot, P.; Marandon, V.; Moulin, E.; de, M.; Nayman, P.; Penno, M.; Ross, D.; Salek, D.; Schade, M.; Schwab, T.; Simoni, R.; Stegmann, C.; Thornhill, J.; Toussenel, F.

    2015-01-01

    The High Energy Stereoscopic System (H.E.S.S.) is an array of imaging atmospheric Cherenkov telescopes (IACTs) located in the Khomas Highland in Namibia. It consists of four 12-m telescopes (CT1-4), which started operations in 2003, and a 28-m diameter one (CT5), which was brought online in 2012. It is the only IACT system featuring telescopes of different sizes, which provides sensitivity for gamma rays across a very wide energy range, from ~30 GeV up to ~100 TeV. Since the camera electronics of CT1-4 are much older than the one of CT5, an upgrade is being carried out; first deployment was in 2015, full operation is planned for 2016. The goals of this upgrade are threefold: reducing the dead time of the cameras, improving the overall performance of the array and reducing the system failure rate related to aging. Upon completion, the upgrade will assure the continuous operation of H.E.S.S. at its full sensitivity until and possibly beyond the advent of CTA. In the design of the new components, several CTA con...

  10. Ground-based VHE γ ray astronomy with air Cherenkov imaging telescopes

    Mirzoyan, R.

    2000-01-01

    The history of astronomy has been one of the scientific discovery following immediately the introduction of new technology. In this report, we will review shortly the basic development of the atmospheric air Cherenkov light detection technique, particularly the imaging telescope technique, which in the last years led to the firm establishment of a new branch in experimental astronomy, namely ground-based very high-energy (VHE) γ ray astronomy. Milestones in the technology and in the analysis of imaging technique will be discussed. The design of the 17 m diameter MAGIC Telescope, being currently under construction, is based on the development of new technologies for all its major parts and sets new standards in the performance of the ground-based γ detectors. MAGIC is one of the next major steps in the development of the technique being the first instrument that will allow one to carry out measurements also in the not yet investigated energy gap i.e. between 10 and 300 GeV

  11. Atmospheric Drag Effects on the Motion of an Artificial Earth Satellite

    TAKEUCHI, Sumio; 武内, 澄夫

    1982-01-01

    Perturbative effects of atmospheric drag on the motion of an artificial earth satellite are investigated in this paper. The atmosphere is considered to rotate with the same angular velocity as the earth. The altitudes of the satellite are given with reference to the standard earth-ellipsoid. The Lagrange planetary equations in Gaussian form are applied to determine the variations of the orbital elements. The atmospheric density at the satellite is regarded as a function of time. The density f...

  12. Effect of protective atmosphere on color of goose meat.

    Orkusz, A; Woloszyn, J; Haraf, G; Okruszek, A

    2013-08-01

    The objective of the work was to characterize the color of the of the goose breast meat packaged in protective atmosphere and stored in the refrigerated conditions. The aim was realized by determination of total heme pigment concentration; relative concentration of myoglobin, oxymyoglobin, and metmyoglobin; parameters of color L* (lightness), a* (redness), and b* (yellowness); and sensory evaluation of the surface color. The experimental material was White Kołuda goose boneless breast meat with the skin from industrial slaughter. The following 2 protective atmospheres were used in the study: vacuum and modified atmosphere (MA) consisting of 80% O2 and 20% CO2. The muscles packed in protective atmosphere were examined on d 4, 7, 11, and 14 of storage. A control sample was goose breast meat stored in air and tested after 24 h after slaughter. The total pigment concentration decreased gradually within 14 d of storage for samples packed in 2 types of atmospheres. The increase in relative concentration of metmyoglobin and the decrease in oxymyoglobin relative concentration in total heme pigments in the meat stored in MA was noticed. However, in all times of storage, the relative concentration of the 3 samples of myoglobin forms stored in vacuum was unchanged. The color parameters (L*, a*, b*) did not change for 14 d of storage in the muscles packed in vacuum. One can state a decrease of the value of the color parameter a* as well as an increase of the value of the color parameter b* in the samples packed in MA. From d 11 to 14 of storage, goose meat packed under MA had lower sensory evaluation intensity of color than muscles under vacuum. The obtained data indicated that the surface color of goose breast meat packed in MA (consisting of 80% O2, 20% CO2) or vacuum packed was maintained for 11 and 14 d, respectively.

  13. Measuring extensive air showers with Cherenkov light detectors of the Yakutsk array: the energy spectrum of cosmic rays

    Ivanov, A A; Knurenko, S P; Sleptsov, I Ye

    2009-01-01

    The energy spectrum of cosmic rays in the range E∼10 15 eV to 6x10 19 eV is studied in this paper using air Cherenkov light detectors of the Yakutsk array. The total flux of photons produced by the relativistic electrons (including positrons as well, hereafter) of extensive air showers in the atmosphere is used as an energy estimator of the primary particle initiating a shower. The resultant differential flux of cosmic rays exhibits, in agreement with previous measurements, a knee and ankle feature at energies of 3x10 15 and ∼10 19 eV, respectively. A comparison of observational data with simulations is made in the knee and ankle regions in order to choose the models of galactic and extragalactic components of cosmic rays that describe well the energy spectrum measured.

  14. Measuring extensive air showers with Cherenkov light detectors of the Yakutsk array: the energy spectrum of cosmic rays

    Ivanov, A A; Knurenko, S P; Sleptsov, I Ye [Shafer Institute for Cosmophysical Research and Aeronomy, Yakutsk 677980 (Russian Federation)], E-mail: ivanov@ikfia.ysn.ru

    2009-06-15

    The energy spectrum of cosmic rays in the range E{approx}10{sup 15} eV to 6x10{sup 19} eV is studied in this paper using air Cherenkov light detectors of the Yakutsk array. The total flux of photons produced by the relativistic electrons (including positrons as well, hereafter) of extensive air showers in the atmosphere is used as an energy estimator of the primary particle initiating a shower. The resultant differential flux of cosmic rays exhibits, in agreement with previous measurements, a knee and ankle feature at energies of 3x10{sup 15} and {approx}10{sup 19} eV, respectively. A comparison of observational data with simulations is made in the knee and ankle regions in order to choose the models of galactic and extragalactic components of cosmic rays that describe well the energy spectrum measured.

  15. Application of Geiger-mode photosensors in Cherenkov detectors

    Gamal, Ahmed, E-mail: gamal.ahmed@assoc.oeaw.ac.a [Stefan Meyer Institute for Subatomic Physics of the Austrian Academy of Sciences, Vienna (Austria); Al-Azhar University, Faculty of Science, Physics Department, Cairo (Egypt); Paul, Buehler; Michael, Cargnelli [Stefan Meyer Institute for Subatomic Physics of the Austrian Academy of Sciences, Vienna (Austria); Roland, Hohler [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Johann, Marton [Stefan Meyer Institute for Subatomic Physics of the Austrian Academy of Sciences, Vienna (Austria); Herbert, Orth [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Ken, Suzuki [Stefan Meyer Institute for Subatomic Physics of the Austrian Academy of Sciences, Vienna (Austria)

    2011-05-21

    Silicon-based photosensors (SiPMs) working in the Geiger-mode represent an elegant solution for the readout of particle detectors working at low-light levels like Cherenkov detectors. Especially the insensitivity to magnetic fields makes this kind of sensors suitable for modern detector systems in subatomic physics which are usually employing magnets for momentum resolution. We are characterizing SiPMs of different manufacturers for selecting sensors and finding optimum operating conditions for given applications. Recently we designed and built a light concentrator prototype with 8x8 cells to increase the active photon detection area of an 8x8 SiPM (Hamamatsu MPPC S10931-100P) array. Monte Carlo studies, measurements of the collection efficiency, and tests with the MPPC were carried out. The status of these developments are presented.

  16. On Tamm's problem in the Vavilov-Cherenkov radiation theory

    Afanas'ev, G.N.; Kartavenko, V.G.; Stepanovskij, Yu.P.

    1999-01-01

    We analyze the well-known Tamm's problem treating the charge motion on a finite space interval with the velocity exceeding light velocity in medium. By comparing Tamm's approximate formulae with the exact ones we prove that the former do not properly describe Cherenkov radiation terms. We also investigate Tamm's formula cos θ T = 1/βn defining the position of the maximum of the field strengths in the Fourier representation. Numerical analysis of the Fourier components of field strengths shows that they have a well pronounced maximum at θ = θ T only for the charge motion on the sufficiently small interval. As an interval grows, many maxima appear. For the charge motion on an infinite interval there is infinite number of maxima of the same amplitude. The quantum analysis of Tamm's formula leads to the same results

  17. All-fiber femtosecond Cherenkov laser at visible wavelengths

    Liu, Xiaomin; Lægsgaard, Jesper; Møller, Uffe Visbech

    2013-01-01

    -matching condition [1]. The resonant ultrafast wave conversion via the fiber-optic CR mechanism is instrumental for applications in biophotonics such as bio-imaging and microscopy [2]. In this work, we demonstrate a highly-stable all-fiber, fully monolithic CR system based on an Yb-fiber femtosecond laser, producing...... to be as low as -103 dBc/Hz. This is 2 orders of magnitudes lower noise as compared to spectrally-sliced supercontinuum, which is the current standard of ultrafast fiber-optic generation at visible wavelength. The layout of the laser system is shown in Fig. 1(a). The system consists of two parts: an all-fiber......Fiber-optic Cherenkov radiation (CR), also known as dispersive wave generation or non-solitonic radiation, is produced in small-core photonic crystal fibers (PCF) when a soliton perturbed by fiber higher-order dispersion co-propagates with a dispersive wave fulfilling a certain phase...

  18. Programmable trigger for electron pairs in ring image Cherenkov counters

    Glab, J.; Baur, R.; Manner, R.

    1990-01-01

    This paper describes a programmable trigger processor for the recognition of Cherenkov rings in a RICH counter. It identifies open electron pairs and suppresses close conversion and Dalitz pairs within 20 μs. More generally, the system can be used for correlating pixel images with pattern masks in order to locate all relatively well defined patterns of a certain type. The trigger processor consists of a systolic processor array of 160 x 176, i.e., 28,160 identical processing elements (PEs) that filter out open electron pairs, and a pseudo adder array that determines whether there was at least one such pair. The processor array is assembled of 20 x 22 VLSI chips containing 8 x 8 PEs each. The semi-custom chip has been developed in 2 μ CMOS standard cell technology

  19. Silicon photomultiplier as a detector of Cherenkov photons

    Korpar, S.; Dolenec, R.; Hara, K.; Iijima, T.; Krizan, P.; Mazuka, Y.; Pestotnik, R.; Stanovnik, A.; Yamaoka, M.

    2008-01-01

    A novel photon detector-i.e. the silicon photomultiplier-whose main advantage over conventional photomultiplier tubes is the operation in high magnetic fields, has been tested as a photon detector in a proximity focusing RICH with aerogel radiator. This type of RICH counter is proposed for the upgrade of the Belle detector at the KEK B-factory. Recently produced silicon photomultipliers show less noise and have larger size, which are important issues for a large area photon detector. We measured the single photon pulse height distribution, the timing resolution and the position sensitivity for different silicon photomultipliers (Hamamatsu MPPC HC025, HC050, and HC100). The silicon photomultipliers were then used to detect Cherenkov photons emitted by cosmic ray particles in a proximity focusing aerogel RICH. Various light guides were investigated in order to increase the detection efficiency

  20. The HERMES dual-radiator ring imaging Cherenkov detector

    Akopov, N; Bailey, K; Bernreuther, S; Bianchi, N; Capitani, G P; Carter, P; Cisbani, E; De Leo, R; De Sanctis, E; De Schepper, D; Dzhordzhadze, V; Filippone, B W; Frullani, S; Garibaldi, F; Hansen, J O; Hommez, B; Iodice, M; Jackson, H E; Jung, P; Kaiser, R; Kanesaka, J; Kowalczyk, R; Lagamba, L; Maas, A; Muccifora, V; Nappi, E; Negodaeva, K; Nowak, Wolf-Dieter; O'Connor, T; O'Neill, T G; Potterveld, D H; Ryckbosch, D; Sakemi, Y; Sato, F; Schwind, A; Shibata, T A; Suetsugu, K; Thomas, E; Tytgat, M; Urciuoli, G M; Van De Kerckhove, K; Van De Vyver, R; Yoneyama, S; Zhang, L F; Zohrabyan, H G

    2002-01-01

    The construction and use of a dual radiator Ring Imaging Cherenkov (RICH) detector is described. This instrument was developed for the HERMES experiment at DESY which emphasises measurements of semi-inclusive deep-inelastic scattering. It provides particle identification for pions, kaons, and protons in the momentum range from 2 to 15 GeV, which is essential to these studies. The instrument uses two radiators, C sub 4 F sub 1 sub 0 , a heavy fluorocarbon gas, and a wall of silica aerogel tiles. The use of aerogel in a RICH detector has only recently become possible with the development of clear, large, homogeneous and hydrophobic aerogel. A lightweight mirror was constructed using a newly perfected technique to make resin-coated carbon-fiber surfaces of optical quality. The photon detector consists of 1934 photomultiplier tubes (PMT) for each detector half, held in a soft steel matrix to provide shielding against the residual field of the main spectrometer magnet.

  1. SU-C-201-07: Towards Clinical Cherenkov Emission Dosimetry: Stopping Power-To-Cherenkov Power Ratios and Beam Quality Specification of Clinical Electron Beams

    Zlateva, Y; Seuntjens, J; El Naqa, I

    2016-01-01

    Purpose: We propose a Cherenkov emission (CE)-based reference dosimetry method, which in contrast to ionization chamber-based dosimetry, employs spectrum-averaged electron restricted mass collision stopping power-to-Cherenkov power ratios (SCRs), and we examine Monte Carlo-calculated SCRs and beam quality specification of clinical electron beams. Methods: The EGSnrc user code SPRRZnrc was modified to compute SCRs instead of stopping-power ratios (single medium: water; cut-off: CE threshold (observing Spencer-Attix conditions); CE power: Frank-Tamm). SCRs are calculated with BEAMnrc for realistic electron beams with nominal energies of 6–22 MeV from three Varian accelerators (TrueBeam Clinac 21EX, Clinac 2100C/D) and for mono-energetic beams of energies equal to the mean electron energy at the water surface. Sources of deviation between clinical and mono-energetic SCRs are analyzed quantitatively. A universal fit for the beam-quality index R_5_0 in terms of the depth of 50% CE C_5_0 is carried out. Results: SCRs at reference depth are overestimated by mono-energetic values by up to 0.2% for a 6-MeV beam and underestimated by up to 2.3% for a 22-MeV beam. The variation is mainly due to the clinical beam spectrum and photon contamination. Beam angular spread has a small effect across all depths and energies. The influence of the electron spectrum becomes increasingly significant at large depths, while at shallow depths and high beam energies photon contamination is predominant (up to 2.0%). The universal data fit reveals a strong linear correlation between R_5_0 and C_5_0 (ρ > 0.99999). Conclusion: CE is inherent to radiotherapy beams and can be detected outside the beam with available optical technologies, which makes it an ideal candidate for out-of-beam high-resolution 3D dosimetry. Successful clinical implementation of CE dosimetry hinges on the development of robust protocols for converting measured CE to radiation dose. Our findings constitute a key step

  2. Pre-selecting muon events in the camera server of the ASTRI telescopes for the Cherenkov Telescope Array

    Maccarone, Maria C.; Mineo, Teresa; Capalbi, Milvia; Conforti, Vito; Coffaro, Martina

    2016-08-01

    The Cherenkov Telescope Array (CTA) represents the next generation of ground based observatories for very high energy gamma ray astronomy. The CTA will consist of two arrays at two different sites, one in the northern and one in the southern hemisphere. The current CTA design foresees, in the southern site, the installation of many tens of imaging atmospheric Cherenkov telescopes of three different classes, namely large, medium, and small, so defined in relation to their mirror area; the northern hemisphere array would consist of few tens of the two larger telescope types. The telescopes will be equipped with cameras composed either of photomultipliers or silicon photomultipliers, and with different trigger and read-out electronics. In such a scenario, several different methods will be used for the telescopes' calibration. Nevertheless, the optical throughput of any CTA telescope, independently of its type, can be calibrated analyzing the characteristic image produced by local atmospheric highly energetic muons that induce the emission of Cherenkov light which is imaged as a ring onto the focal plane if their impact point is relatively close to the telescope optical axis. Large sized telescopes would be able to detect useful muon events under stereo coincidence and such stereo muon events will be directly addressed to the central CTA array data acquisition pipeline to be analyzed. For the medium and small sized telescopes, due to their smaller mirror area and large inter-telescope distance, the stereo coincidence rate will tend to zero; nevertheless, muon events will be detected by single telescopes that must therefore be able to identify them as possible useful calibration candidates, even if no stereo coincidence is available. This is the case for the ASTRI telescopes, proposed as pre-production units of the small size array of the CTA, which are able to detect muon events during regular data taking without requiring any dedicated trigger. We present two fast

  3. Prototype of a production system for Cherenkov Telescope Array with DIRAC

    Arrabito, L; Bregeon, J; Haupt, A; Graciani Diaz, R; Stagni, F; Tsaregorodtsev, A

    2015-01-01

    The Cherenkov Telescope Array (CTA) — an array of many tens of Imaging Atmospheric Cherenkov Telescopes deployed on an unprecedented scale — is the next generation instrument in the field of very high energy gamma-ray astronomy. CTA will operate as an open observatory providing data products to the scientific community. An average data stream of about 10 GB/s for about 1000 hours of observation per year, thus producing several PB/year, is expected. Large CPU time is required for data-processing as well for massive Monte Carlo simulations needed for detector calibration purposes. The current CTA computing model is based on a distributed infrastructure for the archive and the data off-line processing. In order to manage the off-line data-processing in a distributed environment, CTA has evaluated the DIRAC (Distributed Infrastructure with Remote Agent Control) system, which is a general framework for the management of tasks over distributed heterogeneous computing environments. In particular, a production system prototype has been developed, based on the two main DIRAC components, i.e. the Workload Management and Data Management Systems. After three years of successful exploitation of this prototype, for simulations and analysis, we proved that DIRAC provides suitable functionalities needed for the CTA data processing. Based on these results, the CTA development plan aims to achieve an operational production system, based on the DIRAC Workload Management System, to be ready for the start of CTA operation phase in 2017-2018. One more important challenge consists of the development of a fully automatized execution of the CTA workflows. For this purpose, we have identified a third DIRAC component, the so-called Transformation System, which offers very interesting functionalities to achieve this automatisation. The Transformation System is a ’data-driven’ system, allowing to automatically trigger data-processing and data management operations according to pre

  4. The Cherenkov Telescope Array production system for Monte Carlo simulations and analysis

    Arrabito, L.; Bernloehr, K.; Bregeon, J.; Cumani, P.; Hassan, T.; Haupt, A.; Maier, G.; Moralejo, A.; Neyroud, N.; pre="for the"> CTA Consortium, DIRAC Consortium,

    2017-10-01

    The Cherenkov Telescope Array (CTA), an array of many tens of Imaging Atmospheric Cherenkov Telescopes deployed on an unprecedented scale, is the next-generation instrument in the field of very high energy gamma-ray astronomy. An average data stream of about 0.9 GB/s for about 1300 hours of observation per year is expected, therefore resulting in 4 PB of raw data per year and a total of 27 PB/year, including archive and data processing. The start of CTA operation is foreseen in 2018 and it will last about 30 years. The installation of the first telescopes in the two selected locations (Paranal, Chile and La Palma, Spain) will start in 2017. In order to select the best site candidate to host CTA telescopes (in the Northern and in the Southern hemispheres), massive Monte Carlo simulations have been performed since 2012. Once the two sites have been selected, we have started new Monte Carlo simulations to determine the optimal array layout with respect to the obtained sensitivity. Taking into account that CTA may be finally composed of 7 different telescope types coming in 3 different sizes, many different combinations of telescope position and multiplicity as a function of the telescope type have been proposed. This last Monte Carlo campaign represented a huge computational effort, since several hundreds of telescope positions have been simulated, while for future instrument response function simulations, only the operating telescopes will be considered. In particular, during the last 18 months, about 2 PB of Monte Carlo data have been produced and processed with different analysis chains, with a corresponding overall CPU consumption of about 125 M HS06 hours. In these proceedings, we describe the employed computing model, based on the use of grid resources, as well as the production system setup, which relies on the DIRAC interware. Finally, we present the envisaged evolutions of the CTA production system for the off-line data processing during CTA operations and

  5. Coastal Zone Color Scanner atmospheric correction algorithm - Multiple scattering effects

    Gordon, Howard R.; Castano, Diego J.

    1987-01-01

    Errors due to multiple scattering which are expected to be encountered in application of the current Coastal Zone Color Scanner (CZCS) atmospheric correction algorithm are analyzed. The analysis is based on radiative transfer computations in model atmospheres, in which the aerosols and molecules are distributed vertically in an exponential manner, with most of the aerosol scattering located below the molecular scattering. A unique feature of the analysis is that it is carried out in scan coordinates rather than typical earth-sun coordinates, making it possible to determine the errors along typical CZCS scan lines. Information provided by the analysis makes it possible to judge the efficacy of the current algorithm with the current sensor and to estimate the impact of the algorithm-induced errors on a variety of applications.

  6. Exploring the Effects of Clouds on Hot Jupiter Atmospheres

    Robinson, Jenna; Line, Michael

    2018-01-01

    Secondary eclipse spectroscopy of transiting exoplanets allows us to probe the atmospheric properties on the daysides of tidally locked planets. Specifically, eclipse spectra combined with atmospheric retrieval models permit constraints on the molecular abundances and vertical thermal profiles of the planetary dayside. Eclipse spectra from HST WFC3 are typically interpreted assuming that all of the near infrared light is due solely to the thermal emission of the planet. However, recent evidence suggests that reflected stellar light from clouds on the planetary daysides might contaminate the near-IR spectrum. Here, we aim to explore how reflected light from clouds within in a simplified cloud framework will alter the shape of the near infrared spectra and how they will influence our determinations of dayside temperatures and abundances. Specifically, we will use atmospheric retrieval tools to determine the biases in abundances and temperature profiles if reflected light is not taken into account. We will explore the influence of reflected light on interpretation of WFC3 spectra of the well-observed exoplanets, HD209458b and WASP-43b. We will then investigate how reflected light in the near-IR will influence our interpretation of JWST spectra.

  7. Silica aerogel threshold Cherenkov counters for the JLab Hall A spectrometers: improvements and proposed modifications

    Lagamba, L; Colilli, S; Crateri, R; De Leo, R; Frullani, S; Garibaldi, F; Giuliani, F; Gricia, M; Iodice, M; Iommi, R; Leone, A; Lucentini, M; Mostarda, A; Nappi, E; Perrino, R; Pierangeli, L; Santavenere, F; Urciuoli, G M

    2001-01-01

    Recently approved experiments at Jefferson Lab Hall A require a clean kaon identification in a large electron, pion, and proton background environment. To this end, improved performance is required of the silica aerogel threshold Cherenkov counters installed in the focal plane of the two Hall A spectrometers. In this paper we propose two strategies to improve the performance of the Cherenkov counters which presently use a hydrophilic aerogel radiator, and convey Cherenkov photons towards the photomultipliers by means of mirrors with a parabolic shape in one direction and flat in the other. The first strategy is aerogel baking. In the second strategy we propose a modification of the counter geometry by replacing the mirrors with a planar diffusing surface and by displacing in a different way the photomultipliers. Tests at CERN with a 5 GeV/c multiparticle beam revealed that both the strategies are able to increase significantly the number of the detected Cherenkov photons and, therefore, the detector performan...

  8. Low-Noise Operation of All-Fiber Femtosecond Cherenkov Laser

    Liu, Xiaomin; Villanueva Ibáñez, Guillermo Eduardo; Lægsgaard, Jesper

    2013-01-01

    We investigate the noise properties of a femtosecond all-fiber Cherenkov radiation source with emission wavelength around 600 nm, based on an Yb-fiber laser and a highly-nonlinear photonic crystal fiber. A relative intensity noise as low as - 103 dBc/Hz, corresponding to 2.48 % pulse-to-pulse...... fluctuation in energy, was observed at the Cherenkov radiation output power of 4.3 mW, or 150 pJ pulse energy. This pulse-to-pulse fluctuation is at least 10.6 dB lower compared to spectrally-sliced supercontinuum sources traditionally used for ultrafast fiberbased generation at visible wavelengths. Low noise...... makes allfiber Cherenkov sources promising for biophotonics applications such as multi-photon microscopy, where minimum pulse-to-pulse energy fluctuation is required. We present the dependency of the noise figure on both the Cherenkov radiation output power and its spectrum....

  9. Effects of continental anthropogenic sources on organic aerosols in the coastal atmosphere of East China

    Shang, Dongjie; Hu, Min; Guo, Qingfeng; Zou, Qi; Zheng, Jing; Guo, Song

    2017-01-01

    Although organic compounds in marine atmospheric aerosols have significant effects on climate and marine ecosystems, they have rarely been studied, especially in the coastal regions of East China. To assess the origins of the organic aerosols in the East China coastal atmosphere, PM 2.5 samples were collected from the atmospheres of the Yellow Sea, the East China Sea, and Changdao Island during the CAPTAIN (Campaign of Air PolluTion At INshore Areas of Eastern China) field campaign in the spring of 2011. The marine atmospheric aerosol samples that were collected were grouped based on the backward trajectories of their air masses. The organic carbon concentrations in the PM 2.5 samples from the marine and Changdao Island atmospheres were 5.5 ± 3.1 μgC/m 3 and 6.9 ± 2.4 μgC/m 3 , respectively, which is higher than in other coastal water atmospheres. The concentration of polycyclic aromatic hydrocarbons (PAHs) in the marine atmospheric PM 2.5 samples was 17.0 ± 20.2 ng/m 3 , indicating significant continental anthropogenic influences. The influences of fossil fuels and biomass burning on the composition of organic aerosols in the coastal atmosphere of East China were found to be highly dependent on the origins of the air masses. Diesel combustion had a strong impact on air masses from the Yangtze River Delta (YRD), and gasoline emissions had a more significant impact on the “North China” marine atmospheric samples. The “Northeast China” marine atmospheric samples were most impacted by biomass burning. Coal combustion contributed significantly to the compositions of all of the atmospheric samples. The proportions of secondary compounds increased as samples aged in the marine atmosphere indicating that photochemical oxidation occured during transport. Our results quantified ecosystem effects on marine atmospheric aerosols and highlighted the uncertainties that arise when modeling marine atmospheric PM 2.5 without considering high spatial resolution

  10. Effects of tillage practice and atmospheric CO2 level on soil CO2 efflux

    Elevated atmospheric carbon dioxide (CO2) affects both the quantity and quality of plant tissues, which impacts the cycling and storage of carbon (C) within plant/soil systems and thus the rate of CO2 release back to the atmosphere. Research to accurately quantify the effects of elevated CO2 and as...

  11. The effect of atmospheric carbon dioxide elevation on plant growth in freshwater ecosystems

    Schippers, P.; Vermaat, J.; Klein, de J.J.M.; Mooij, W.M.

    2004-01-01

    The authors developed a dynamic model to investigate the effect of atmospheric carbon dioxide (CO2) increase on plant growth in freshwater ecosystems. Steady-state simulations were performed to analyze the response of phytoplankton and submerged macrophytes to atmospheric CO2 elevation from 350 to

  12. The effect of atmospheric carbon dioxide elevation on plant growth in freshwater ecosystems

    Schippers, P.; Vermaat, J.E.; de Klein, J.; Mooij, W.M.

    2004-01-01

    We developed a dynamic model to investigate the effect of atmospheric carbon dioxide (CO2) increase on plant growth in freshwater ecosystems. Steady-state simulations were performed to analyze the response of phytoplankton and submerged macrophytes to atmospheric CO2 elevation from 350 to 700 ppm.

  13. Atmospheric River Development and Effects on Southern California

    Harris, S. M.; Carvalho, L. V.

    2014-12-01

    Throughout most of southern California (SCA) annual precipitation totals occur from relatively few storms per season. Any changes to storm frequency or intensity may dramatically impact the region, as its landscapes are prone to various rainfall-induced hazards including landslides and floods. These hazards become more frequent following drought or fire events, conditions also reliant on precipitation and common in SCA. Rainfall forecasts are especially difficult to determine as regional precipitation is affected by numerous phenomena. On synoptic timescales, atmospheric rivers (ARs) are one such phenomenon known to impact SCA rainfall. ARs are channels of high water vapor content found within the lower atmosphere that transport moisture towards midlatitudes. In areas with varying topography, ARs often produce high-intensity precipitation due to orographic forcing. Although much insight has been gained in understanding AR climatology affecting North America's western coast, the spatiotemporal characteristics and atmospheric forcings driving ARs to SCA need to be further addressed. The goal of this work is to understand the characteristics of ARs that impact SCA and to distinguish them from ARs that impact northern latitudes. We investigate AR characteristics as well as atmospheric features prior to plume initiation for ARs impacting different landfall regions along North America's western coast between 1998-2008. Dates of AR events are organized according to landfall region using total precipitable water (TPW) fields from the National Oceanic and Atmospheric Administration's Climate Forecast System Reanalysis (CFSR). Additional CFSR fields are used to create anomaly composites of moist static energy, geopotential height, as well as upper-level zonal and low-level meridional winds for each landfall region on the day of and prior to AR occurrence. ARs that impact SCA display different TPW plume characteristics as well as wave train patterns throughout the AR

  14. Operating performance of the gamma-ray Cherenkov telescope: An end-to-end Schwarzschild–Couder telescope prototype for the Cherenkov Telescope Array

    Dournaux, J.L., E-mail: jean-laurent.dournaux@obspm.fr [GEPI, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Paris Cité, Université Paris Diderot, Place J. Janssen, 92190 Meudon (France); De Franco, A. [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Laporte, P. [GEPI, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Paris Cité, Université Paris Diderot, Place J. Janssen, 92190 Meudon (France); White, R. [Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); Greenshaw, T. [University of Liverpool, Oliver Lodge Laboratory, P.O. Box 147, Oxford Street, Liverpool L69 3BX (United Kingdom); Sol, H. [LUTH, Observatoire de Paris, PSL Research University, CNRS, Université Paris Diderot, Place J. Janssen, 92190 Meudon (France); Abchiche, A. [CNRS, Division technique DT-INSU, 1 Place Aristide Briand, 92190 Meudon (France); Allan, D. [Department of Physics and Centre for Advanced Instrumentation, Durham University, South Road, Durham DH1 3LE (United Kingdom); Amans, J.P. [GEPI, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Paris Cité, Université Paris Diderot, Place J. Janssen, 92190 Meudon (France); Armstrong, T.P. [Department of Physics and Centre for Advanced Instrumentation, Durham University, South Road, Durham DH1 3LE (United Kingdom); Balzer, A.; Berge, D. [GRAPPA, University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands); Boisson, C. [LUTH, Observatoire de Paris, PSL Research University, CNRS, Université Paris Diderot, Place J. Janssen, 92190 Meudon (France); and others

    2017-02-11

    The Cherenkov Telescope Array (CTA) consortium aims to build the next-generation ground-based very-high-energy gamma-ray observatory. The array will feature different sizes of telescopes allowing it to cover a wide gamma-ray energy band from about 20 GeV to above 100 TeV. The highest energies, above 5 TeV, will be covered by a large number of Small-Sized Telescopes (SSTs) with a field-of-view of around 9°. The Gamma-ray Cherenkov Telescope (GCT), based on Schwarzschild–Couder dual-mirror optics, is one of the three proposed SST designs. The GCT is described in this contribution and the first images of Cherenkov showers obtained using the telescope and its camera are presented. These were obtained in November 2015 in Meudon, France.

  15. Measurable difference in Cherenkov light between gamma and hadron induced EAS

    Cabot, H.; Meynadier, Ch. [Universite de Perpignan, Groupe de Physique Fondamentale, Perpignan (France); Sobczynska, D. [Experimental Physics Department, University of Lodz, Lodz (Poland); Szabelska, B. [Soltan Institute for Nuclear Studies, Lodz (Poland); Szabelski, J. [Universite de Perpignan, Groupe de Physique Fondamentale, Perpignan (France)]|[Soltan Institute for Nuclear Studies, Lodz (Poland); Wibig, T. [Experimental Physics Department, University of Lodz, Lodz (Poland)

    1997-12-31

    We describe the possibly measurable difference in the Cherenkov light component of EAS induced by en electromagnetic particle (i.e. e{sup +}, e{sup -} or {gamma}) and induced by a hadron (i.e. proton or heavier nuclei) in TeV range. The method can be applied in experiments which use wavefront sampling method of EAS Cherenkov light detection (e.g. THEMISTOCLE, ASGAT). (author) 16 refs, 9 figs

  16. Cherenkov radiation as a means of radio isotope diagnosis of eyeball tumors

    Moshnikov, O.S.; Kolesnichenko, V.N.

    1986-01-01

    Radiophosphorus indication of eye new-growths can be accomplished through registration of beta-particle or Cherenkov radiation. In both cases the criterion for the conclusion to be drawn from the experimental results is the relative increment of the count rate. The article analyses the specific features of the equipment aimed at recording Cherenkov radiation in the process of radiophosphorus studied in ophthalmology, and discusses the method for these studies. (orig.)

  17. Design and construction of a Cherenkov detector for Compton polarimetry at the ILC

    Bartels, Christoph

    2010-11-01

    This paper describes the design and construction of a Cherenkov detector conceived with regard to high energy Compton polarimeters for the International Linear Collider, where beam diagnostic systems of unprecedented precision must complement the interaction region detectors to pursue an ambitious physics programme. Besides the design of the Cherenkov detector, detailed simulation studies and first testbeam results are presented. Good agreement of beam data with expectations from Monte Carlo simulations is observed. (orig.)

  18. Design and construction of a Cherenkov detector for Compton polarimetry at the ILC

    Bartels, Christoph [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Hamburg Univ. (Germany). Inst. fuer Experimentalphysik; Ebert, Joachim; Hartin, Anthony; Helebrant, Christian; Kaefer, Daniela; List, Jenny [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2010-11-15

    This paper describes the design and construction of a Cherenkov detector conceived with regard to high energy Compton polarimeters for the International Linear Collider, where beam diagnostic systems of unprecedented precision must complement the interaction region detectors to pursue an ambitious physics programme. Besides the design of the Cherenkov detector, detailed simulation studies and first testbeam results are presented. Good agreement of beam data with expectations from Monte Carlo simulations is observed. (orig.)

  19. Performance of wireless optical communication systems under polarization effects over atmospheric turbulence

    Zhang, Jiankun; Li, Ziyang; Dang, Anhong

    2018-06-01

    It has been recntly shown that polarization state of propagation beam would suffer from polarization fluctuations due to the detrimental effects of atmospheric turbulence. This paper studies the performance of wireless optical communication (WOC) systems in the presence of polarization effect of atmosphere. We categorize the atmospheric polarization effect into polarization rotation, polarization-dependent power loss, and phase shift effect, with each effect described and modeled with the help of polarization-coherence theory and the extended Huygens-Fresnelprinciple. The channel matrices are derived to measure the cross-polarization interference of the system. Signal-to-noise ratio and bit error rate for polarization multiplexing system and polarization modulation system are obtained to assess the viability using the approach of M turbulence model. Monte Carlo simulation results show the performance of polarization based WOC systems to be degraded by atmospheric polarization effect, which could be evaluated precisely using the proposed model with given turbulent strengths.

  20. The performance of a prototype array of water Cherenkov detectors for the LHAASO project

    An, Q. [University of Science and Technology of China, Hefei 230026 (China); State Key Laboratory of Particle Detection and Electronics, Beijing 100049 (China); Bai, Y.X.; Bi, X.J.; Cao, Z. [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Chang, J.F. [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); State Key Laboratory of Particle Detection and Electronics, Beijing 100049 (China); Chen, G.; Chen, M.J. [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Chen, S.M. [Tsinghua University, Beijing 100084 (China); Chen, S.Z. [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Chen, T.L. [University of Tibet, Lhasa 851600 (China); Chen, X. [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Chen, Y.T. [University of Yunnan, Kunming 650091 (China); Cui, S.W. [Normal University of Hebei, Shijiazhuang 050016 (China); Dai, B.Z. [University of Yunnan, Kunming 650091 (China); Du, Q. [Tsinghua University, Beijing 100084 (China); Danzengluobu [University of Tibet, Lhasa 851600 (China); Feng, C.F. [University of Shandong, Jinan 250100 (China); Feng, S.H.; Gao, B. [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Gao, S.Q. [National Space Science Center, Chinese Academy of Sciences, Beijing 100190 (China); and others

    2013-10-01

    A large high-altitude air-shower observatory (LHAASO) is to be built at Shangri-La, Yunnan Province, China. This observatory is intended to conduct sub-TeV gamma astronomy, and as an important component of the LHAASO project, a water Cherenkov detector array (WCDA) is proposed. To investigate engineering issues and fully understand the water Cherenkov technique for detecting air showers, a prototype array at 1% scale of the LHAASO-WCDA has been built at Yang-Ba-Jing, Tibet, China. This paper introduces the prototype array setup and studies its performance by counting rate of each photomultiplier tube (PMT), trigger rates at different PMT multiplicities, and responses to air showers. Finally, the reconstructed shower directions and angular resolutions of the detected showers for the prototype array are given. -- Highlights: • The technique of the water Cherenkov array is studied. • Engineering issues of the water Cherenkov array are investigated. • The PMTs and electronics of the water Cherenkov array are tested. • Some key parameters of the water Cherenkov array are measured.

  1. The performance of a prototype array of water Cherenkov detectors for the LHAASO project

    An, Q.; Bai, Y.X.; Bi, X.J.; Cao, Z.; Chang, J.F.; Chen, G.; Chen, M.J.; Chen, S.M.; Chen, S.Z.; Chen, T.L.; Chen, X.; Chen, Y.T.; Cui, S.W.; Dai, B.Z.; Du, Q.; Danzengluobu; Feng, C.F.; Feng, S.H.; Gao, B.; Gao, S.Q.

    2013-01-01

    A large high-altitude air-shower observatory (LHAASO) is to be built at Shangri-La, Yunnan Province, China. This observatory is intended to conduct sub-TeV gamma astronomy, and as an important component of the LHAASO project, a water Cherenkov detector array (WCDA) is proposed. To investigate engineering issues and fully understand the water Cherenkov technique for detecting air showers, a prototype array at 1% scale of the LHAASO-WCDA has been built at Yang-Ba-Jing, Tibet, China. This paper introduces the prototype array setup and studies its performance by counting rate of each photomultiplier tube (PMT), trigger rates at different PMT multiplicities, and responses to air showers. Finally, the reconstructed shower directions and angular resolutions of the detected showers for the prototype array are given. -- Highlights: • The technique of the water Cherenkov array is studied. • Engineering issues of the water Cherenkov array are investigated. • The PMTs and electronics of the water Cherenkov array are tested. • Some key parameters of the water Cherenkov array are measured

  2. The effect of moving waves on neutral marine atmospheric boundary layer

    Sam Ali Al

    2014-01-01

    Full Text Available Large eddy simulations are performed to study the effects of wind-wave direction misalignment of the neutral marine atmospheric boundary layer over a wavy wall. The results show that the wind-wave misalignment has a significant effect on the velocity profiles and the pressure fluctuation over the wave surface. These effects are not confined to the near wave surface region but extend over the whole atmospheric surface layer.

  3. An on-line modelling study of the direct effect of atmospheric aerosols over Europe

    Palacios, L.; Baro, R.; Jimenez-Guerrero, P.

    2015-01-01

    Atmospheric aerosols affect human health, ecosystems, materials, visibility and Earth’s climate. Those effects are studied in this present work and depend mainly on the aerosol optical properties and how they influence the Earth’s radiation budget. Such properties can be divided on direct and semi-direct effect, produced by the scattering and absorption of radiation; and indirect effect, which influences the aerosols-cloud interactions. The aim of this work is to assess the direct effect through the study of the mean temperature; the radiation that reaches the Earth’s surface and at the top of the atmosphere; and the interaction of these meteorological variables with particulate matter (PM10). Results indicate decreases in temperature and radiation that reaches the Earth's surface, together with increases in the outgoing radiation at top of the atmosphere, and changes in the particulate matter, thus proving a colder climate due to the direct effect of atmospheric aerosols. (Author)

  4. An on-line modelling study of the direct effect of atmospheric aerosols over Europe

    Palacios, L.; Baro, R.; Jimenez-Guerrero, P.

    2015-07-01

    Atmospheric aerosols affect human health, ecosystems, materials, visibility and Earth’s climate. Those effects are studied in this present work and depend mainly on the aerosol optical properties and how they influence the Earth’s radiation budget. Such properties can be divided on direct and semi-direct effect, produced by the scattering and absorption of radiation; and indirect effect, which influences the aerosols-cloud interactions. The aim of this work is to assess the direct effect through the study of the mean temperature; the radiation that reaches the Earth’s surface and at the top of the atmosphere; and the interaction of these meteorological variables with particulate matter (PM10). Results indicate decreases in temperature and radiation that reaches the Earth's surface, together with increases in the outgoing radiation at top of the atmosphere, and changes in the particulate matter, thus proving a colder climate due to the direct effect of atmospheric aerosols. (Author)

  5. An on-line modelling study of the direct effect of atmospheric aerosols over Europe

    Palacios, L.; Baro, R.; Jimenez-Guerrero, P.

    2015-07-01

    Atmospheric aerosols affect human health, ecosystems, materials, visibility and Earths climate. Those effects are studied in this present work and depend mainly on the aerosol optical properties and how they influence the Earths radiation budget. Such properties can be divided on direct and semi-direct effect, produced by the scattering and absorption of radiation; and indirect effect, which influences the aerosols-cloud interactions. The aim of this work is to assess the direct effect through the study of the mean temperature; the radiation that reaches the Earths surface and at the top of the atmosphere; and the interaction of these meteorological variables with particulate matter (PM10). Results indicate decreases in temperature and radiation that reaches the Earth's surface, together with increases in the outgoing radiation at top of the atmosphere, and changes in the particulate matter, thus proving a colder climate due to the direct effect of atmospheric aerosols. (Author)

  6. Reversed Cherenkov emission of terahertz waves from an ultrashort laser pulse in a sandwich structure with nonlinear core and left-handed cladding.

    Bakunov, M I; Mikhaylovskiy, R V; Bodrov, S B; Luk'yanchuk, B S

    2010-01-18

    We propose a scheme for an experimental verification of the reversed Cherenkov effect in left-handed media. The scheme uses optical-to-terahertz conversion in a planar sandwichlike structure that consists of a nonlinear core cladded with a material that exhibits left-handedness at terahertz frequencies. The focused into a line femtosecond laser pulse propagates in the core and emits Cherenkov wedge of terahertz waves in the cladding. We developed a theory that describes terahertz generation in such a structure and calculated spatial distribution of the generated terahertz field, its energy spectrum, and optical-to-terahertz conversion efficiency. The proposed structure can be a useful tool for characterization of the electromagnetic properties of metamaterials in the terahertz frequency range.

  7. The effects of atmospheric processes on tehran smog forming.

    Mohammadi, H; Cohen, D; Babazadeh, M; Rokni, L

    2012-01-01

    Air pollution is one of the most important problems in urban areas that always threaten citizen's health. Photochemical smog is one of the main factors of air pollution in large cities like Tehran. Usually smog is not only a part of nature, but is being analyzed as an independent matter, which highly affects on the nature. It has been used as relationship between atmospheric elements such as temperature, pressure, relative humidity, wind speed with inversion in the time of smog forming and weather map in 500 Hpa level during 9 years descriptive static by using correlation coefficient in this analyze. Results show that there is a meaningful correlation between atmospheric elements and smog forming. This relation is seen between monthly average of these elements and monthly average of smog forming. However, when temperature decreases, corresponding pressure will increase and result of this will be smog forming. Usually smog increases in cold months of year due to enter cold high pressure air masses in Iran during December and January that is simultaneous with decreasing temperature and air pressure increases and inversion height distance decreases from the earth surface which cause to integrate air pollution under its surface, will cause to form smog in Tehran. It shows a meaningful and strong relation, based on resultant relations by correlation coefficient from inversion height and smog forming, so that obtained figure is more than 60% .

  8. Atmospheric Pressure Effects on Cryogenic Storage Tank Boil-Off

    Sass, J. P.; Frontier, C. R.

    2007-01-01

    The Cryogenics Test Laboratory (CTL) at the Kennedy Space Center (KSC) routinely utilizes cryostat test hardware to evaluate comparative and absolute thermal conductivities of a wide array of insulation systems. The test method is based on measurement of the flow rate of gas evolved due to evaporative boil-off of a cryogenic liquid. The gas flow rate typically stabilizes after a period of a couple of hours to a couple of days, depending upon the test setup. The stable flow rate value is then used to calculate the thermal conductivity for the insulation system being tested. The latest set of identical cryostats, 1,000-L spherical tanks, exhibited different behavior. On a macro level, the flow rate did stabilize after a couple of days; however the stable flow rate was oscillatory with peak to peak amplitude of up to 25 percent of the nominal value. The period of the oscillation was consistently 12 hours. The source of the oscillation has been traced to variations in atmospheric pressure due to atmospheric tides similar to oceanic tides. This paper will present analysis of this phenomenon, including a calculation that explains why other cryostats are not affected by it.

  9. The effects of atmospheric optical conditions on perceived scenic beauty

    Latimer, Douglas A.; Hogo, Henry; Daniel, Terry C.

    This paper describes the results from the first year of a currently on-going study, the objective of which is to investigate the relationships between atmospheric optical conditions and human perceptions of scenic beauty. Color photographs and atmospheric optical measurements, using telephotometers and nephelometers, were taken in the western U.S.A. (Grand Canyon National Park and Mt. Lemmon near Tucson, Arizona) and in the eastern United States (Great Smoky Mountains and Shenandoah national parks). Over 1300 individual observers rated color slides for either visual air quality or scenic beauty using a 10-point rating scale. Ratings were transformed to indices using standard psychophysical techniques. Relationships between these perceptual indices and physical parameters characteristic of the given landscape represented in the color slides were investigated using scatter plots, correlation analysis, and multiple linear regression. Physical parameters included visual range, horizon sky chromaticity and luminance, solar zenith and scattering angles, and cloud conditions. Results show that observers' ratings of visual air quality and scenic beauty are sensitive to visual range, sky color, and scattering angle. However, in some of the areas investigated, scenic beauty ratings were not affected by changes in visual range. The sensitivity of the scenic beauty of a vista to changes in the extinction coefficient may be useful for establishing visibility goals and priorities.

  10. Investigating the Cherenkov light lateral distribution function for primary proton and iron nuclei in extensive air showers

    Al-Rubaiee, A.A.; Hashim, U.; Al-Douri, Y.

    2015-01-01

    The lateral distribution function (LDF) of Cherenkov radiation in extensive air showers (EAS) was simulated by CORSIKA program for the conditions of Yakutsk Cherenkov array at high energy range (10 13 -10 16 eV) for two primary particles (p and Fe) for different zenith angles. Using Breit-Wigner function for analyzing Cherenkov light LDF, a parameterization of Cherenkov light LDF was reconstructed by depending on CORSIKA simulation as a function of primary energy. The comparison between the estimated Cherenkov light LDF and the LDF that was measured on the Yakutsk EAS array gives the ability of particle identification that initiated the shower and determination of particle's energy around the knee region. The extrapolation of approximated Cherenkov light LDF for energies 20 and 30 PeV was obtained for primary particles (p and Fe)

  11. Effects of Atmospheric Refraction on an Airborne Weather Radar Detection and Correction Method

    Lei Wang

    2015-01-01

    Full Text Available This study investigates the effect of atmospheric refraction, affected by temperature, atmospheric pressure, and humidity, on airborne weather radar beam paths. Using three types of typical atmospheric background sounding data, we established a simulation model for an actual transmission path and a fitted correction path of an airborne weather radar beam during airplane take-offs and landings based on initial flight parameters and X-band airborne phased-array weather radar parameters. Errors in an ideal electromagnetic beam propagation path are much greater than those of a fitted path when atmospheric refraction is not considered. The rates of change in the atmospheric refraction index differ with weather conditions and the radar detection angles differ during airplane take-off and landing. Therefore, the airborne radar detection path must be revised in real time according to the specific sounding data and flight parameters. However, an error analysis indicates that a direct linear-fitting method produces significant errors in a negatively refractive atmosphere; a piecewise-fitting method can be adopted to revise the paths according to the actual atmospheric structure. This study provides researchers and practitioners in the aeronautics and astronautics field with updated information regarding the effect of atmospheric refraction on airborne weather radar detection and correction methods.

  12. Cherenkov light imaging tests with state-of-the-art solid state photon counter for the CLAS12 RICH detector

    Balossino, Ilaria; Barion, L.; Contalbrigo, M.; Lenisa, P.; Lucherini, V.; Malaguti, R.; Mirazita, M.; Movsisyan, A.; Squerzanti, S.; Turisini, M.

    2017-12-01

    A large area ring-imaging Cherenkov detector will be operated for hadron identification in the 3 GeV / c to 8 GeV / c momentum range at the CLAS12 experiment at the upgraded continuous electron beam accelerator facility of Jefferson Lab. The detector, consisting of aerogel radiator, composite mirrors and photon counters, will be built with a hybrid optics design to allow the detection of Cherenkov light for both forward and large angle hadron tracks. The active area has to be densely packed and highly segmented, covering about 1m2 with pixels of 6mm2 , and to allow a time resolution of 1 ns. A technology that can offer a cost-effective solution and low material budget could be Silicon Photomultipliers (SiPM) thanks to their high gain at low bias voltage, fast timing, good single-photoelectron resolution and insensitivity to magnetic fields. An investigation is ongoing on samples of 3 × 3mm2 SiPM of different micro-cell size to assess the single photon detection capability in the presence of high dark count rate due to thermal generation effects, after-pulses or optical cross-talk and to study the response to the moderate radiation damage expected at CLAS12. In this work, a brief review of the latest and most interesting results from these studies will be shown.

  13. Effect of stress relief annealing temperature and atmosphere on the magnetic properties of silicon steel

    Paolinelli, Sebastiao C.; Cunha, Marco A. da

    2006-01-01

    Fully processed non-oriented silicon steel samples 0.50 mm thick were sheared and submitted to stress relief annealing under different conditions of temperature and atmosphere to investigate the effect of this treatment on the recovery of magnetic properties. Two different compositions were used, with different Si and Al contents. Temperature was varied in the range of 600-900 deg. C and four atmospheres were used: N 2 and N 2 +10%H 2 combined with dew points of -10 and 15 deg. C. The results showed that annealing atmosphere has very important effect on the magnetic properties and that the beneficial effect of stress relief annealing can be overcome by the detrimental effect of the atmosphere under certain conditions, due to oxidation and nitration

  14. SU-F-J-56: The Connection Between Cherenkov Light Emission and Radiation Absorbed Dose in Proton Irradiated Phantoms

    Darafsheh, A; Kassaee, A; Finlay, J [University of Pennsylvania, Philadelphia, PA (United States); Taleei, R [UT Southwestern Medical Center, Dallas, TX (United States)

    2016-06-15

    Purpose: Range verification in proton therapy is of great importance. Cherenkov light follows the photon and electron energy deposition in water phantom. The purpose of this study is to investigate the connection between Cherenkov light generation and radiation absorbed dose in a water phantom irradiated with proton beams. Methods: Monte Carlo simulation was performed by employing FLUKA Monte Carlo code to stochastically simulate radiation transport, ionizing radiation dose deposition, and Cherenkov radiation in water phantoms. The simulations were performed for proton beams with energies in the range 50–600 MeV to cover a wide range of proton energies. Results: The mechanism of Cherenkov light production depends on the initial energy of protons. For proton energy with 50–400 MeV energy that is below the threshold (∼483 MeV in water) for Cherenkov light production directly from incident protons, Cherenkov light is produced mainly from the secondary electrons liberated as a result of columbic interactions with the incident protons. For proton beams with energy above 500 MeV, in the initial depth that incident protons have higher energy than the Cherenkov light production threshold, the light has higher intensity. As the slowing down process results in lower energy protons in larger depths in the water phantom, there is a knee point in the Cherenkov light curve vs. depth due to switching the Cherenkov light production mechanism from primary protons to secondary electrons. At the end of the depth dose curve the Cherenkov light intensity does not follow the dose peak because of the lack of high energy protons to produce Cherenkov light either directly or through secondary electrons. Conclusion: In contrast to photon and electron beams, Cherenkov light generation induced by proton beams does not follow the proton energy deposition specially close to the end of the proton range near the Bragg peak.

  15. Atmospheric Monitoring at the Site of the MAGIC Telescopes

    Will Martin

    2017-01-01

    Full Text Available The MAGIC telescopes in La Palma, Canary Islands, measure the Cherenkov light emitted by gamma ray-induced extended air showers in the atmosphere. The good knowledge of the atmospheric parameters is important, both for the correct and safe operations of the telescopes, but also for subsequent data analysis. A weather station measures the state variables of the atmosphere, temperature, humidity and wind, an elastic Lidar system and an infrared pyrometer determine the optical transmission of the atmosphere. Using an AllSky camera, the cloud cover can be estimated. The measured values are completed by data from global atmospheric models based on numeric weather forecasts.

  16. WIMP search and a Cherenkov detector prototype for ILC polarimetry

    Bartels, Christoph

    2011-10-15

    The planned International Linear Collider (ILC) will be an essential experiment to precisely determine the properties and structure of physics at the TeV scale. An important feature of the ILC is the possibility to use polarized electrons and positrons. In part 1 of this thesis, a model independent search for Weakly Interacting Massive Particles (WIMPs) at ILC is presented. The signal channel under study is direct WIMP pair production with associated Initial State Radiation (ISR), e{sup +}e{sup -} {yields} {chi}{chi}{gamma}, where the WIMPs leave the detector without any further interaction, and only the emitted photon is detected. From the energy spectrum of the detected photons the coupling structure, cross sections, masses and the quantum number of the dominant partial wave in the production process can be inferred. The analysis includes the dominant SM, as well as machine-induced backgrounds, and is performed using a full simulation of the ILD detector concept. For an integrated luminosity of L=500 fb{sup -1}, the signal cross sections can be measured to a precision of 3%, dominated by systematic uncertainties on the polarization measurement of the initial electrons and positrons. Masses can be measured to a precision of up to 2% by a comparison of the data photon spectrum to parametrized template spectra. In part 2 of this thesis, a Cherenkov detector prototype for Compton polarimetry at ILC is presented. For the polarization measurement a systematic uncertainty of {delta} P/P = 0.25% or better is envisioned. To achieve this goal, the Cherenkov detector has to be precisely aligned with the fan of Compton scattered electrons and its signal response needs to be highly linear. For the detector prototype data driven alignment strategies have been developed by comparing data recorded at the Elsa accelerator in Bonn, Germany, with detailed Geant4 simulations. With the use of multi-anode photomultipliers, data driven alignment strategies promise to provide the

  17. New electronics for the Cherenkov Telescope Array (NECTAr)

    Naumann, C. L.; Delagnes, E.; Bolmont, J.; Corona, P.; Dzahini, D.; Feinstein, F.; Gascón, D.; Glicenstein, J.-F.; Guilloux, F.; Nayman, P.; Rarbi, F.; Sanuy, A.; Tavernet, J.-P.; Toussenel, F.; Vincent, P.; Vorobiov, S.

    2012-12-01

    The international CTA consortium has recently entered into its preparatory phase towards the construction of the next-generation Cherenkov Telescope Array CTA. This experiment will be a successor, and based on the return of experience from the three major current-generation arrays H.E.S.S., MAGIC and VERITAS, and aims to significantly improve upon the sensitivity as well as the energy range of its highly successful predecessors. Construction is planned to begin by 2013, and when finished, CTA will be able to explore the highest-energy gamma ray sky in unprecedented detail. To achieve this increase in sensitivity and energy range, CTA will employ the order of 100 telescopes of three different sizes on two sites, with around 1000-4000 channels per camera, depending on the telescope size. To equip and reliably operate the order of 100000 channels of photodetectors (compared to 6000 of the H.E.S.S. array), a new kind of flexible and powerful yet inexpensive front-end hardware will be required. One possible solution is pursued by the NECTAr (New Electronics for the Cherenkov Telescope Array) project. Its main feature is the integration of as much as possible of the front-end electronics (amplifiers, fast analogue samplers, memory and ADCs) into a single ASIC, which will allow very fast readout performances while significantly reducing the cost and the power consumption per channel. Also included is a low-cost FPGA for digital treatment and online data processing, as well as an Ethernet connection. Other priorities of NECTAr are the modularity of the system, a high degree of flexibility in the trigger system as well as the possibility of flexible readout modes to optimise the signal-to-noise ratio while at the same time allowing a significant reduction of data rates, both of which could improve the sensitivity of CTA compared to current detection systems. This paper gives an overview over the development work for the Nectar system, with particular focus on its main

  18. New electronics for the Cherenkov Telescope Array (NECTAr)

    Naumann, C.L.; Delagnes, E.; Bolmont, J.; Corona, P.; Dzahini, D.; Feinstein, F.; Gascón, D.; Glicenstein, J.-F.; Guilloux, F.; Nayman, P.; Rarbi, F.; Sanuy, A.; Tavernet, J.-P.; Toussenel, F.; Vincent, P.; Vorobiov, S.

    2012-01-01

    The international CTA consortium has recently entered into its preparatory phase towards the construction of the next-generation Cherenkov Telescope Array CTA. This experiment will be a successor, and based on the return of experience from the three major current-generation arrays H.E.S.S., MAGIC and VERITAS, and aims to significantly improve upon the sensitivity as well as the energy range of its highly successful predecessors. Construction is planned to begin by 2013, and when finished, CTA will be able to explore the highest-energy gamma ray sky in unprecedented detail. To achieve this increase in sensitivity and energy range, CTA will employ the order of 100 telescopes of three different sizes on two sites, with around 1000–4000 channels per camera, depending on the telescope size. To equip and reliably operate the order of 100000 channels of photodetectors (compared to 6000 of the H.E.S.S. array), a new kind of flexible and powerful yet inexpensive front-end hardware will be required. One possible solution is pursued by the NECTAr (New Electronics for the Cherenkov Telescope Array) project. Its main feature is the integration of as much as possible of the front-end electronics (amplifiers, fast analogue samplers, memory and ADCs) into a single ASIC, which will allow very fast readout performances while significantly reducing the cost and the power consumption per channel. Also included is a low-cost FPGA for digital treatment and online data processing, as well as an Ethernet connection. Other priorities of NECTAr are the modularity of the system, a high degree of flexibility in the trigger system as well as the possibility of flexible readout modes to optimise the signal-to-noise ratio while at the same time allowing a significant reduction of data rates, both of which could improve the sensitivity of CTA compared to current detection systems. This paper gives an overview over the development work for the Nectar system, with particular focus on its main

  19. New electronics for the Cherenkov Telescope Array (NECTAr)

    Naumann, C.L., E-mail: christopher.naumann@lpnhe.in2p3.fr [LPNHE, IN2P3/CNRS Universite Paris VI and Universite Paris VII and IN2P3/CNRS, Paris (France); Delagnes, E. [IRFU, CEA/DSM, Saclay, Gif-sur-Yvette (France); Bolmont, J.; Corona, P. [LPNHE, IN2P3/CNRS Universite Paris VI and Universite Paris VII and IN2P3/CNRS, Paris (France); Dzahini, D. [LPSC, Universite Joseph Fourier, INPG and IN2P3/CNRS, Grenoble (France); Feinstein, F. [LUPM, Universite Montpellier II and IN2P3/CNRS, Montpellier (France); Gascon, D. [ICC-UB, Universitat Barcelona (Spain); Glicenstein, J.-F.; Guilloux, F. [IRFU, CEA/DSM, Saclay, Gif-sur-Yvette (France); Nayman, P. [LPNHE, IN2P3/CNRS Universite Paris VI and Universite Paris VII and IN2P3/CNRS, Paris (France); Rarbi, F. [LPSC, Universite Joseph Fourier, INPG and IN2P3/CNRS, Grenoble (France); Sanuy, A. [ICC-UB, Universitat Barcelona (Spain); Tavernet, J.-P.; Toussenel, F.; Vincent, P. [LPNHE, IN2P3/CNRS Universite Paris VI and Universite Paris VII and IN2P3/CNRS, Paris (France); Vorobiov, S. [LUPM, Universite Montpellier II and IN2P3/CNRS, Montpellier (France); DESY Zeuthen, Platanenallee 6, 15738 Zeuthen (Germany)

    2012-12-11

    The international CTA consortium has recently entered into its preparatory phase towards the construction of the next-generation Cherenkov Telescope Array CTA. This experiment will be a successor, and based on the return of experience from the three major current-generation arrays H.E.S.S., MAGIC and VERITAS, and aims to significantly improve upon the sensitivity as well as the energy range of its highly successful predecessors. Construction is planned to begin by 2013, and when finished, CTA will be able to explore the highest-energy gamma ray sky in unprecedented detail. To achieve this increase in sensitivity and energy range, CTA will employ the order of 100 telescopes of three different sizes on two sites, with around 1000-4000 channels per camera, depending on the telescope size. To equip and reliably operate the order of 100000 channels of photodetectors (compared to 6000 of the H.E.S.S. array), a new kind of flexible and powerful yet inexpensive front-end hardware will be required. One possible solution is pursued by the NECTAr (New Electronics for the Cherenkov Telescope Array) project. Its main feature is the integration of as much as possible of the front-end electronics (amplifiers, fast analogue samplers, memory and ADCs) into a single ASIC, which will allow very fast readout performances while significantly reducing the cost and the power consumption per channel. Also included is a low-cost FPGA for digital treatment and online data processing, as well as an Ethernet connection. Other priorities of NECTAr are the modularity of the system, a high degree of flexibility in the trigger system as well as the possibility of flexible readout modes to optimise the signal-to-noise ratio while at the same time allowing a significant reduction of data rates, both of which could improve the sensitivity of CTA compared to current detection systems. This paper gives an overview over the development work for the Nectar system, with particular focus on its main

  20. Vacuum Cherenkov radiation for Lorentz-violating fermions

    Schreck, M.

    2017-11-01

    The current work focuses on the process of vacuum Cherenkov radiation for Lorentz-violating fermions that are described by the minimal standard-model extension (SME). To date, most considerations of this important hypothetical process have been restricted to Lorentz-violating photons, as the necessary theoretical tools for the SME fermion sector have not been available. With their development in a very recent paper, we are now in a position to compute the decay rates based on a modified Dirac theory. Two realizations of the Cherenkov process are studied. In the first scenario, the spin projection of the incoming fermion is assumed to be conserved, and in the second, the spin projection is allowed to flip. The first type of process is shown to be still forbidden for the dimensionful a and b coefficients where there are strong indications that it is energetically disallowed for the H coefficients, as well. However, it is rendered possible for the dimensionless c , d , e , f , and g coefficients. For large initial fermion energies, the decay rates for the c and d coefficients were found to grow linearly with momentum and to be linearly suppressed by the smallness of the Lorentz-violating coefficient where for the e , f , and g coefficients this suppression is even quadratic. The decay rates vanish in the vicinity of the threshold, as expected. The decay including a fermion spin-flip plays a role for the spin-nondegenerate operators and it was found to occur for the dimensionful b and H coefficients as well as for the dimensionless d and g . The characteristics of this process differ much from the properties of the spin-conserving one, e.g., there is no threshold. Based on experimental data of ultra-high-energy cosmic rays, new constraints on Lorentz violation in the quark sector are obtained from the thresholds. However, it does not seem to be possible to derive bounds from the spin-flip decays. This work reveals the usefulness of the quantum field theoretic methods

  1. WIMP search and a Cherenkov detector prototype for ILC polarimetry

    Bartels, Christoph

    2011-10-01

    The planned International Linear Collider (ILC) will be an essential experiment to precisely determine the properties and structure of physics at the TeV scale. An important feature of the ILC is the possibility to use polarized electrons and positrons. In part 1 of this thesis, a model independent search for Weakly Interacting Massive Particles (WIMPs) at ILC is presented. The signal channel under study is direct WIMP pair production with associated Initial State Radiation (ISR), e + e - → χχγ, where the WIMPs leave the detector without any further interaction, and only the emitted photon is detected. From the energy spectrum of the detected photons the coupling structure, cross sections, masses and the quantum number of the dominant partial wave in the production process can be inferred. The analysis includes the dominant SM, as well as machine-induced backgrounds, and is performed using a full simulation of the ILD detector concept. For an integrated luminosity of L=500 fb -1 , the signal cross sections can be measured to a precision of 3%, dominated by systematic uncertainties on the polarization measurement of the initial electrons and positrons. Masses can be measured to a precision of up to 2% by a comparison of the data photon spectrum to parametrized template spectra. In part 2 of this thesis, a Cherenkov detector prototype for Compton polarimetry at ILC is presented. For the polarization measurement a systematic uncertainty of δ P/P = 0.25% or better is envisioned. To achieve this goal, the Cherenkov detector has to be precisely aligned with the fan of Compton scattered electrons and its signal response needs to be highly linear. For the detector prototype data driven alignment strategies have been developed by comparing data recorded at the Elsa accelerator in Bonn, Germany, with detailed Geant4 simulations. With the use of multi-anode photomultipliers, data driven alignment strategies promise to provide the required precision. At ILC, these

  2. Atmospheric stability effects on potential radiological releases at a nuclear research facility in Romania: Characterising the atmospheric mixing state

    Chambers, Scott D.; Galeriu, Dan; Williams, Alastair G.; Melintescu, Anca; Griffiths, Alan D.; Crawford, Jagoda; Dyer, Leisa; Duma, Marin; Zorila, Bogdan

    2016-01-01

    A radon-based nocturnal stability classification scheme is developed for a flat inland site near Bucharest, Romania, characterised by significant local surface roughness heterogeneity, and compared with traditional meteorologically-based techniques. Eight months of hourly meteorological and atmospheric radon observations from a 60 m tower at the IFIN-HH nuclear research facility are analysed. Heterogeneous surface roughness conditions in the 1 km radius exclusion zone around the site hinder accurate characterisation of nocturnal atmospheric mixing conditions using conventional meteorological techniques, so a radon-based scheme is trialled. When the nocturnal boundary layer is very stable, the Pasquill–Gifford “radiation” scheme overestimates the atmosphere's capacity to dilute pollutants with near-surface sources (such as tritiated water vapour) by 20% compared to the radon-based scheme. Under these conditions, near-surface wind speeds drop well below 1 m s"−"1 and nocturnal mixing depths vary from ∼25 m to less than 10 m above ground level (a.g.l.). Combining nocturnal radon with daytime ceilometer data, we were able to reconstruct the full diurnal cycle of mixing depths. Average daytime mixing depths at this flat inland site range from 1200 to 1800 m a.g.l. in summer, and 500–900 m a.g.l. in winter. Using tower observations to constrain the nocturnal radon-derived effective mixing depth, we were able to estimate the seasonal range in the Bucharest regional radon flux as: 12 mBq m"−"2 s"−"1 in winter to 14 mBq m"−"2 s"−"1 in summer. - Highlights: • Site climatology accurately characterised by season and atmospheric stability class. • Comparison of "2"2"2Rn-based, Pasquill–Gifford and Richardson number stability indices. • Seasonal mixing depth estimates over the whole diurnal cycle by ceilometer and radon. • Seasonal variability in the regional radon source function well constrained.

  3. Extent and effects of atmospheric pollution on soils

    Oden, S

    1972-01-01

    Man's activities take place mainly in a thin layer of air near the ground, and both direct and indirect emissions into the air give rise to local, regional or even global distribution of man-made products. Radioactive substances, insecticides, hydrocarbons, heavy metals and exhaust products from industries and urban areas are thus emitted into the atmosphere and they may be distributed all over the Globe. This widespread distribution is now a well-known fact for some compounds such as radioactive isotopes, chlorinated hydrocarbons (DDT) and lead. For other substances the distribution pattern is more local - or seems to be more local due to lack of information. In the long run, however, all emissions will be globally distributed.

  4. The increased atmospheric greenhouse effect and regional climate change

    Groenaas, S. [Bergen Univ. (Norway)

    1996-03-01

    This paper was read at the workshop ``The Norwegian Climate and Ozone Research Programme`` held on 11-12 March 1996. The main information for predicting future climate changes comes from integrating coupled climate models of the atmosphere, ocean and cryosphere. Regional climate change may be studied from the global integrations, however, resolution is coarse because of insufficient computer power. Attempts are being made to get more regional details out of the global integrations by ``downscaling`` the latter. This can be done in two ways. Firstly, limited area models with high resolution are applied, driven by the global results as boundary values. Secondly, statistical relationships have been found between observed meteorological parameters, like temperature and precipitation, and analyzed large scale gridded fields. The derived relations are then used on similar data from climate runs to give local interpretations. A review is given of literature on recent observations of climate variations and on predicted regional climate change. 18 refs., 4 figs.

  5. Lithium spectral line formation in stellar atmospheres. The impact of convection and NLTE effects

    Klevas, J.; Kučinskas, A.; Steffen, M.; Caffau, E.; Ludwig, H. -G.

    2015-01-01

    Different simplified approaches are used to account for the non-local thermodynamic equilibrium (NLTE) effects with 3D hydrodynamical model atmospheres. In certain cases, chemical abundances are derived in 1D NLTE and corrected for the 3D effects by adding 3D-1D LTE abundance corrections (3D+NLTE approach). Alternatively, average model atmospheres are sometimes used to substitute for the full 3D hydrodynamical models. We tested whether the results obtained using these simplified schemes (i.e...

  6. Reflectance of Antarctic surfaces from multispectral radiometers: The correction of atmospheric effects

    Zibordi, G.; Maracci, G.

    1993-01-01

    Monitoring reflectance of polar icecaps has relevance in climate studies. In fact, climate changes produce variations in the morphology of ice and snow covers, which are detectable as surface reflectance change. Surface reflectance can be retrieved from remotely sensed data. However, absolute values independent of atmospheric turbidity and surface altitude can only be obtained after removing masking effects of the atmosphere. An atmospheric correction model, accounting for surface and sensor altitudes above sea level, is described and validated through data detected over Antarctic surfaces with a Barnes Modular Multispectral Radiometer having bands overlapping those of the Landsat Thematic Mapper. The model is also applied in a sensitivity analysis to investigate error induced in reflectance obtained from satellite data by indeterminacy in optical parameters of atmospheric constituents. Results show that indeterminacy in the atmospheric water vapor optical thickness is the main source of nonaccuracy in the retrieval of surface reflectance from data remotely sensed over Antarctic regions

  7. PPO-ethanol system as wavelength shifter for the Cherenkov counting technique using a liquid scintillation counter

    Takiue, M.; Fujii, H.; Ishikawa, H.

    1984-01-01

    2,5-diphenyloxazole (PPO) has been proposed as a wavelength shifter for Cherenkov counting. Since PPO is not incorporated with water, we have introduced the fluor into water in the form of micelle using a PPO-ethanol system. This technique makes it possible to obtain a high Cherenkov counting efficiency under stable sample conditions, attributed to the proper spectrometric features of the PPO. The 32 P Cherenkov counting efficiency (68.4%) obtained from this technique is 1.62 times as large as that measured with a conventional Cherenkov technique. (orig.)

  8. Impact of atmospheric effects on the energy reconstruction of air showers observed by the surface detectors of the Pierre Auger Observatory

    Aab, A.; Abreu, P.; Aglietta, M.; Blažek, Jiří; Boháčová, Martina; Chudoba, Jiří; Ebr, Jan; Mandát, Dušan; Palatka, Miroslav; Pech, Miroslav; Prouza, Michael; Řídký, Jan; Schovánek, Petr; Trávníček, Petr; Vícha, Jakub

    2017-01-01

    Roč. 12, č. 2 (2017), s. 1-23, č. článku P02006. ISSN 1748-0221 R&D Projects: GA MŠk LM2015038; GA MŠk LG15014; GA ČR(CZ) GA14-17501S Institutional support: RVO:68378271 Keywords : Cherenkov detectors * data analysis * large detector systems for particle and astroparticle physics * systematic effects Subject RIV: BF - Elementary Particles and High Energy Physics OBOR OECD: Particles and field physics Impact factor: 1.220, year: 2016

  9. The effect of atmospheric temperature and pressure on the occurrence of acute myocardial infarction in Kaunas.

    Radišauskas, Ričardas; Vaičiulis, Vidmantas; Ustinavičienė, Rūta; Bernotienė, Gailutė

    2013-01-01

    OBJECTIVE. The aim of the study was to evaluate the impact of meteorological variables (atmospheric temperature and pressure) on the daily occurrence of acute myocardial infarction (AMI). MATERIAL AND METHODS. The study used the daily values of atmospheric temperature and pressure in 2000-2007. The meteorological data were obtained from the Lithuanian Hydrometeorological Service for Kaunas. The relative risks of event occurrence were computed for 5°C atmospheric temperature and for 10-hPa atmospheric pressure variations by means of the Poisson regression model. RESULTS. The occurrence of AMI and atmospheric temperature showed an inverse linear relationship, while the occurrence of AMI and atmospheric pressure, a positive linear relationship. Among the youngest subjects (25-44 years old), no relationships were detected. Contrary, among the subjects aged 45-64 years and those aged 65 years and older, the occurrence of AMI significantly decreased with higher temperature (P=0.001 and P=0.002, respectively). A decrease in atmospheric temperature by 10ºC reduced the risk of AMI by 8.7% in the age groups of 45-64 and 65 years and older and by 19% in the age group of 25 years and older. Among the first AMI cases, the risk increased by 7.5% in the age group of 45-64-year olds and by 6.4% in the age group of 25-64-year olds. The relationship between atmospheric temperature and pressure, and AMI occurrence was found to be linear but inverse. An increase in atmospheric pressure by 10 hPa resulted in an increase in risk by 4% among the subjects aged 65 years and more and by 3% among the subjects aged 25 years and more. CONCLUSIONS. Atmospheric temperature and pressure variations had the greatest effect on middle-aged and aging subjects (starting from 45 years). At younger age, the effect of such factors on the AMI risk was considerably lower.

  10. Effects of continental anthropogenic sources on organic aerosols in the coastal atmosphere of East China.

    Shang, Dongjie; Hu, Min; Guo, Qingfeng; Zou, Qi; Zheng, Jing; Guo, Song

    2017-10-01

    Although organic compounds in marine atmospheric aerosols have significant effects on climate and marine ecosystems, they have rarely been studied, especially in the coastal regions of East China. To assess the origins of the organic aerosols in the East China coastal atmosphere, PM 2.5 samples were collected from the atmospheres of the Yellow Sea, the East China Sea, and Changdao Island during the CAPTAIN (Campaign of Air PolluTion At INshore Areas of Eastern China) field campaign in the spring of 2011. The marine atmospheric aerosol samples that were collected were grouped based on the backward trajectories of their air masses. The organic carbon concentrations in the PM 2.5 samples from the marine and Changdao Island atmospheres were 5.5 ± 3.1 μgC/m 3 and 6.9 ± 2.4 μgC/m 3 , respectively, which is higher than in other coastal water atmospheres. The concentration of polycyclic aromatic hydrocarbons (PAHs) in the marine atmospheric PM 2.5 samples was 17.0 ± 20.2 ng/m 3 , indicating significant continental anthropogenic influences. The influences of fossil fuels and biomass burning on the composition of organic aerosols in the coastal atmosphere of East China were found to be highly dependent on the origins of the air masses. Diesel combustion had a strong impact on air masses from the Yangtze River Delta (YRD), and gasoline emissions had a more significant impact on the "North China" marine atmospheric samples. The "Northeast China" marine atmospheric samples were most impacted by biomass burning. Coal combustion contributed significantly to the compositions of all of the atmospheric samples. The proportions of secondary compounds increased as samples aged in the marine atmosphere indicating that photochemical oxidation occured during transport. Our results quantified ecosystem effects on marine atmospheric aerosols and highlighted the uncertainties that arise when modeling marine atmospheric PM 2.5 without considering high spatial resolution source

  11. Effects of Bulk Composition on the Atmospheric Dynamics on Close-in Exoplanets

    Zhang, X.; Showman, A. P.

    2015-12-01

    Depending on the metallicity of the protoplanetary disk, the details of gas accretion during planetary formation, and atmospheric loss during planetary evolution, the atmospheres of sub-Jupiter-sized planets could exhibit a variety of bulk compositions. Examples include hydrogen-dominated atmospheres like Jupiter, more metal-rich atmospheres like Neptune, evaporated atmospheres dominated by helium, or of course carbon dioxide, water vapor, nitrogen, and other heavy molecules as exhibited by terrestrial planets in the solar system. Here we systematically investigate the effects of atmospheric bulk compositions on temperature and wind distributions for tidally locked sub-Jupiter-sized planets using an idealized three-dimensional general circulation model (GCM). Composition—in particular, the molecular mass and specific heat—affect the sound speed, gravity wave speeds, atmospheric scale height, and Rossby deformation radius, and therefore in principle can exert significant controls on the atmospheric circulation, including the day-night temperature difference and other observables. We performed numerous simulations exploring a wide range of molecular masses and molar specific heats. The effect of molecular weight dominates. We found that a higher-molecular-weight atmosphere tends to have a larger day-night temperature contrast, a smaller eastward phase shift in the thermal light curve, and a narrower equatorial super-rotating jet that occurs in a deeper atmosphere. The zonal-mean zonal wind is smaller and more prone to exhibit a latitudinally alternating pattern in a higher-molecular-weight atmosphere. If the vertical temperature profile is close to adiabatic, molar specific heat will play a significant role in controlling the transition from a divergent flow in the upper atmosphere to a jet-dominated flow in the lower atmosphere. We are also working on analytical theories to explain aspects of the simulations relevant for possible observables on tidally locked

  12. Challenges of arbitrary waveform signal detection by Silicon Photomultipliers as readout for Cherenkov fibre based beam loss monitoring systems

    Vinogradov, Sergey; Nebot del Busto, Eduardo; Kastriotou, Maria; Welsch, Carsten P

    2016-01-01

    Silicon Photomultipliers (SiPMs) are well recognised as very competitive photodetectors due to their exceptional photon number and time resolution, room-temperature low-voltage operation, insensitivity to magnetic fields, compactness, and robustness. Detection of weak light pulses of nanosecond time scale appears to be the best area for SiPM applications because in this case most of the SiPM drawbacks have a rather limited effect on its performance. In contrast to the more typical scintillation and Cherenkov detection applications, which demand information on the number of photons and/or the arrival time of the light pulse only, beam loss monitoring (BLM) systems utilising Cherenkov fibres with photodetector readout have to precisely reconstruct the temporal profile of the light pulse. This is a rather challenging task for any photon detector especially taking into account the high dynamic range of incident signals (100K – 1M) from a few photons to a few percents of destructive losses in a beam line and pre...

  13. Mass dependence of spectral and angular distributions of Cherenkov radiation from relativistic isotopes in solid radiators and its possible application as mass selector

    Bogdanov, O. V.; Rozhkova, E. I.; Pivovarov, Yu. L.; Kuzminchuk-Feuerstein, N.

    2018-02-01

    The first proof of principle experiment with a prototype of a Time-of-Flight (TOF) - Cherenkov detector of relativistic heavy ions (RHI) exploiting a liquid Iodine Naphthalene radiator has been performed at Cave C at GSI (Darmstadt, Germany). A conceptual design for a liquid Cherenkov detector was proposed as a prototype for the future TOF measurements at the Super-FRS by detection of total number of Cherenkov photons. The ionization energy loss of RHI in a liquid radiator decreases only slightly this number, while in a solid radiator changes sufficiently not the total number of ChR photons, but ChR angular and spectral distributions. By means of computer simulations, we showed that these distributions are very sensitive to the isotope mass, due to different stopping powers of isotopes with initial equal relativistic factors. The results of simulations for light (Li, Be) and heavy (Xe) isotopes at 500-1000 MeV/u are presented indicating the possibility to use the isotopic effect in ChR of RHI as the mass selector.

  14. SiPM as photon counter for Cherenkov detectors

    Roy, B.J.; Orth, H.; Schwarz, C.; Wilms, A.; Peters, K.

    2009-01-01

    Silicon photomultipliers (SiPMs) are very new type of photon counting devices that show great promise to be used as detection device in combination with scintillators/ Cherenkov radiators. SiPM is essentially an avalanche photo-diode operated in limited Geiger mode. They have been considered as potential readout devices for DIRC counter of the PANDA detector which is one of the large experiment at FAIR- the new international facility to be built at GSI, Darmstadt. In addition, the potential use of SiPM includes medical diagnosis, fluorescence measurement and high energy physics experiments. The SiPM module is a photon counting device capable of low light level detection. It is essentially an opto-semiconductor device with excellent photon counting capability and possesses great advantages over the conventional PMTs because of low voltage operation and insensitivity to magnetic fields. In many of the high energy physics experiments, the photon sensors are required to operate in high magnetic fields precluding the use of conventional PMTs. This problem can be over come with the use of SiPMs. With this motivation in mind, we have developed a SiPM test facility and have tested several commercially available SiPM for their performance study and comparison with other photon counting devices

  15. Prototype study of the Cherenkov imager of the AMS experiment

    Aguayo, P.; Aguilar-Benitez, M.; Arruda, L.; Barao, F.; Barreira, G.; Barrau, A.; Baret, B.; Belmont, E.; Berdugo, J.; Boudoul, G.; Borges, J.; Buenerd, M.; Casadei, D.; Casaus, J.; Delgado, C.; Diaz, C.; Derome, L.; Eraud, L.; Gallin-Martel, L.; Giovacchini, F.; Goncalves, P.; Lanciotti, E.; Laurenti, G.; Malinine, A.; Mana, C.; Marin, J.; Martinez, G.; Menchaca-Rocha, A.; Palomares, C.; Pereira, R.; Pimenta, M.; Protasov, K.; Sanchez, E.; Seo, E.-S.; Sevilla, I.; Torrento, A.; Vargas-Trevino, M.; Veziant, O.

    2006-01-01

    The AMS experiment includes a Cherenkov imager for mass and charge identification of charged cosmic rays. A second generation prototype has been constructed and its performances evaluated both with cosmic ray particles and with beam ions. In-beam tests have been performed using secondary nuclei from the fragmentation of 20GeV/c per nucleon Pb ions and 158GeV/c per nucleon In from the CERN SPS in 2002 and 2003. Partial results are reported. The performances of the prototype for the velocity and the charge measurements have been studied over the range of ion charge Z-bar 30. A sample of candidate silica aerogel radiators for the flight model of the detector has been tested. The measured velocity resolution of the detector was found to scale with Z -1 as expected, with a value σ(β)/β∼0.7-110 -3 for singly charged particles and an asymptotic limit in Z of 0.4-0.6x10 -4 . The measured charge resolution obtained for the n=1.05 aerogel radiator material selected for the flight model of the detector is σ(Z)=0.18 (statistical) -bar 0.015 (systematic), ensuring a good charge separation up to the iron element, for the prototype in the reported experimental conditions

  16. Optimization of the digital Silicon Photomultiplier for Cherenkov light detection

    Frach, T

    2012-01-01

    The Silicon Photomultiplier is a promising alternative to fast vacuum photodetectors. We developed a fully digital implementation of the Silicon Photomultiplier. The sensor is based on a single photon avalanche photodiode (SPAD) integrated in a standard CMOS process. Photons are detected directly by sensing the voltage at the SPAD anode using a dedicated cell electronics block next to each diode. This block also contains active quenching and recharge circuits as well as a one bit memory for the selective inhibit of detector cells. A balanced trigger network is used to propagate the trigger signal from all cells to the integrated time-to-digital converter. Photons are detected and counted as digital signals, thus making the sensor less susceptible to temperature variations and electronic noise. The integration with CMOS logic has the added benefit of low power consumption and possible integration of data post-processing in the sensor. In this paper, we discuss the sensor architecture together with its characteristics, and its possible optimizations for applications requiring the detection of Cherenkov light.

  17. TORCH—a Cherenkov based time-of-flight detector

    Dijk, M.W.U. van, E-mail: m.vandijk@bristol.ac.uk [H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Brook, N.H. [H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Castillo García, L. [European Organisation for Nuclear Research (CERN), CH-1211 Geneva 23 (Switzerland); Laboratory for High Energy Physics, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland); Cowie, E.N.; Cussans, D. [H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); D' Ambrosio, C. [European Organisation for Nuclear Research (CERN), CH-1211 Geneva 23 (Switzerland); Fopma, J. [Denys Wilkinson Laboratory, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Forty, R.; Frei, C. [European Organisation for Nuclear Research (CERN), CH-1211 Geneva 23 (Switzerland); Gao, R. [Denys Wilkinson Laboratory, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Gys, T. [European Organisation for Nuclear Research (CERN), CH-1211 Geneva 23 (Switzerland); Harnew, N.; Keri, T. [Denys Wilkinson Laboratory, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Piedigrossi, D. [European Organisation for Nuclear Research (CERN), CH-1211 Geneva 23 (Switzerland)

    2014-12-01

    TORCH is an innovative high-precision time-of-flight system to provide particle identification in the difficult intermediate momentum region up to 10 GeV/c. It is also suitable for large-area applications. The detector provides a time-of-flight measurement from the imaging of Cherenkov photons emitted in a 1 cm thick quartz radiator. The photons propagate by total internal reflection to the edge of the quartz plate and are then focused onto an array of photon detectors at the periphery. A time-of-flight resolution of about 10–15 ps per incident charged particle needs to be achieved to allow a three sigma kaon-pion separation up to 10 GeV/c momentum for the TORCH located 9.5 m from the interaction point. Given ∼30 detected photons per incident charged particle, this requires measuring the time-of-arrival of individual photons to about 70 ps. This paper will describe the design of a TORCH prototype involving a number of ground-breaking and challenging techniques.

  18. The effects of atmospheric multipollutants on modern concrete

    Marinoni, N.; Birelli, M.P.; Rostagno, C.; Pavese, A. [University of Milan, Milan (Italy)

    2003-10-01

    Concrete samples were collected from the indoor walls of a tunnel in Milan (Italy), erected at the beginning of the 20th century for railway subway. Since the second half of the 20th century, during the construction of Stazione Centrale (Central Railway Station) of Milan, the tunnel has been turned into an automobile and railway crossing, thus increasing the deposition of aggressive pollutants on building materials. Weathering layers (commonly known as black crusts) caused by deposition of atmospheric pollutants on concrete surfaces were analysed in order to investigate the main mechanisms responsible for deterioration. A mineralogical and physical-chemical characterisation of the concrete and black crusts was performed by optical microscopy, atomic absorption spectroscopy, X-ray powder diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and differential scanning calorimetry. The results attest that the main deterioration phenomenon affecting concrete is the sulphation process by dry deposition, leading to secondary salt crystallisation (gypsum formation) on the external surface of the samples. Moreover, concrete samples show widespread micro- and macro-cracking, high porosity, and corrosion phenomena at the aggregate binder interface (AAR). Airborne particulate matter produced by fuel (oil-derived and coal) combustion was found embedded in the gypsum matrix of black crusts, suggesting its catalytic role in sulphation process.

  19. Global Analysis of Climate Change Projection Effects on Atmospheric Rivers

    Espinoza, Vicky; Waliser, Duane E.; Guan, Bin; Lavers, David A.; Ralph, F. Martin

    2018-05-01

    A uniform, global approach is used to quantify how atmospheric rivers (ARs) change between Coupled Model Intercomparison Project Phase 5 historical simulations and future projections under the Representative Concentration Pathway (RCP) 4.5 and RCP8.5 warming scenarios. The projections indicate that while there will be 10% fewer ARs in the future, the ARs will be 25% longer, 25% wider, and exhibit stronger integrated water vapor transports (IVTs) under RCP8.5. These changes result in pronounced increases in the frequency (IVT strength) of AR conditions under RCP8.5: 50% (25%) globally, 50% (20%) in the northern midlatitudes, and 60% (20%) in the southern midlatitudes. The models exhibit systematic low biases across the midlatitudes in replicating historical AR frequency ( 10%), zonal IVT ( 15%), and meridional IVT ( 25%), with sizable intermodel differences. A more detailed examination of six regions strongly impacted by ARs suggests that the western United States, northwestern Europe, and southwestern South America exhibit considerable intermodel differences in projected changes in ARs.

  20. Initial effect of the Fukushima accident on atmospheric electricity

    Takeda, M.; Yamauchi, M.; Makino, M.; Owada, T.

    2011-08-01

    Vertical atmospheric DC electric field at ground level, or potential gradient (PG), suddenly dropped by one order of magnitude at Kakioka, 150 km southwest from the Fukushima Dai-ichi nuclear power plant (FNPP) right after the plant released a massive amount of radioactive material southward on 14 March, 2011. The PG stayed at this level for days with very small daily variations. Such a long-lasting near-steady low PG has never been observed at Kakioka. The sudden drop of PG with one-hour time scale is similar to those associated with rain-induced radioactive fallout after nuclear tests and the Chernobyl disaster. A comparison with the PG data with the radiation dose rate data at different places revealed that arrival of the radioactive dust by low-altitude wind caused the PG drop without rain. Furthermore, the PG might have reflected a minor release several hours before this release at the distance of 150 km. It is recommended that all nuclear power plant to have a network of PG observation surrounding the plant.

  1. Effect of annealing atmosphere on optic-electric properties of Zn O thin films

    Bueno, C.; Pacio, M.; Juarez, H.; Osorio, E.; Perez, R.

    2017-01-01

    In this work the study of structural, morphologic characteristics, optical and electrical properties of the thin films of Zn O in temperatures and annealing atmospheres different was realized. The films were obtained by the sol-gel method, utilizing zinc acetate dihydrate as the precursor, monoethanolamine (Mea) as a stabilizing agent and 2-methoxyethanol as a solvent and deposited by spin-coating. The films were crystallized at 600, 800 and 1000 degrees Celsius in oxygen and nitrogen atmospheres. The results obtained by XRD, Sem, photoluminescence and Hall effects of the Zn O films were related and depend strongly on the temperature and atmosphere annealing. (Author)

  2. Effect of annealing atmosphere on optic-electric properties of Zn O thin films

    Bueno, C. [Benemerita Universidad Autonoma de Puebla, Facultad de Ingenieria, Blvd. Valsequillo y Av. San Claudio s/n, 72570 Puebla (Mexico); Pacio, M.; Juarez, H. [Benemerita Universidad Autonoma de Puebla, Posgrado en Dispositivos Semiconductores, Av. San Claudio y 14 Sur, 72450 Puebla (Mexico); Osorio, E. [Universidad de Quinta Roo, Blvd. Bahia s/n, esquina Ignacio Comonfort, El Bosque, 77019 Chetumal, Quintana Roo (Mexico); Perez, R., E-mail: cba3009@gmail.com [Benemerita Universidad Autonoma de Puebla, Facultad de Ingenieria Quimica, Av. San Claudio y 18 Sur, 72570 Puebla (Mexico)

    2017-11-01

    In this work the study of structural, morphologic characteristics, optical and electrical properties of the thin films of Zn O in temperatures and annealing atmospheres different was realized. The films were obtained by the sol-gel method, utilizing zinc acetate dihydrate as the precursor, monoethanolamine (Mea) as a stabilizing agent and 2-methoxyethanol as a solvent and deposited by spin-coating. The films were crystallized at 600, 800 and 1000 degrees Celsius in oxygen and nitrogen atmospheres. The results obtained by XRD, Sem, photoluminescence and Hall effects of the Zn O films were related and depend strongly on the temperature and atmosphere annealing. (Author)

  3. Atmospheric effect on the ground-based measurements of broadband surface albedo

    T. Manninen

    2012-11-01

    Full Text Available Ground-based pyranometer measurements of the (clear-sky broadband surface albedo are affected by the atmospheric conditions (mainly by aerosol particles, water vapour and ozone. A new semi-empirical method for estimating the magnitude of the effect of atmospheric conditions on surface albedo measurements in clear-sky conditions is presented. Global and reflected radiation and/or aerosol optical depth (AOD at two wavelengths are needed to apply the method. Depending on the aerosol optical depth and the solar zenith angle values, the effect can be as large as 20%. For the cases we tested using data from the Cabauw atmospheric test site in the Netherlands, the atmosphere caused typically up to 5% overestimation of surface albedo with respect to corresponding black-sky surface albedo values.

  4. Virtual store atmosphere in internet retailing: Measuring virtual retail store layout effects on consumer buying behaviour

    Vrechopoulos, Adam P

    2001-01-01

    This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University. The research presented in this dissertation is concerned with the effects of the "virtual store atmosphere" on consumer buying behaviour within the context of Internet retailing. More specifically, the focus of this research is to investigate whether the virtual store layout, as a major virtual store atmosphere determinant, affects consumer buying behaviour during shopping activity w...

  5. The 'greenhouse effect' as a function of atmospheric mass

    Jelbring, Hans

    2003-07-01

    The main reason for claiming a scientific basis for 'Anthropogenic Greenhouse Warming (AGW)' is related to the use of 'radiative energy flux models' as a major tool for describing vertical energy fluxes within the atmosphere. Such models prescribe that the temperature difference between a planetary surface and the planetary average black body radiation temperature (commonly called the Greenhouse Effect, GE) is caused almost exclusively by the so called greenhouse gases. Here, using a different approach, it is shown that GE can be explained as mainly being a consequence of known physical laws describing the behaviour of ideal gases in a gravity field. A simplified model of Earth, along with a formal proof concerning the model atmosphere and evidence from real planetary atmospheres will help in reaching conclusions. The distinguishing premise is that the bulk part of a planetary GE depends on its atmospheric surface mass density. Thus the GE can be exactly calculated for an ideal planetary model atmosphere. In a real atmosphere some important restrictions have to be met if the gravity induced GE is to be well developed. It will always be partially developed on atmosphere bearing planets. A noteworthy implication is that the calculated values of AGW, accepted by many contemporary climate scientists, are thus irrelevant and probably quite insignificant (not detectable) in relation to natural processes causing climate change. (Author)

  6. Effect of controlled atmosphere on the mig-mag arc weldment properties

    Kacar, Ramazan; Koekemli, Koray

    2005-01-01

    Due to their higher welding speed, automation and weld pool protection against to the atmosphere gases, gas metal arc welding (GMAW) process is widely used in industry. Due to the less stable arc associated with the use of consumable electrodes, GMAW process is not clean as good as gas tungsten arc welding process. Furthermore, the greater arc length in GMAW process also reduces the protective effect of the shielding gas. Due to electrochemical and thermochemical reactions between weld pool and arc atmosphere, it is quite important, especially weld metal toughness and joining of reactive materials to entirely create inert atmosphere for GMAW process. Therefore, a controlled atmosphere cabinet was developed for GMAW process. Low carbon steel combinations were welded with classical GMAW process in argon atmosphere as well as controlled atmosphere cabinet by using similar welding parameters. The mechanical and metallurgical properties of both weldments were evaluated. Result shows that toughness of the weld metal that was obtained in the controlled atmosphere cabinet much higher than that of classical GMAW process. The metallographic examination also clarified that there was not any gas porosity and inclusion in the weld metal compared with classical process

  7. Spatial variation in the flux of atmospheric deposition and its ecological effects in arid Asia

    Jiao, Linlin; Wang, Xunming; Li, Danfeng

    2018-06-01

    Atmospheric deposition is one of the key land surface processes, and plays important roles in regional ecosystems and global climate change. Previous studies have focused on the magnitude of and the temporal and spatial variations in the flux of atmospheric deposition, and the composition of atmospheric deposition on a local scale. However, there have been no comprehensive studies of atmospheric deposition on a regional scale and its ecological effects in arid Asia. The temporal and spatial patterns, composition of atmospheric deposition, and its potential effects on regional ecosystems in arid Asia are investigated in this study. The results show that the annual deposition flux is high on the Turan Plain, Aral Sea Desert, and Tarim Basin. The seasonal deposition flux also varies remarkably among different regions. The Tarim Basin shows higher deposition flux in both spring and summer, southern Mongolian Plateau has a higher deposition flux in spring, and the deposition flux of Iran Plateau is higher in summer. Multiple sources of elements in deposited particles are identified. Calcium, iron, aluminum, and magnesium are mainly derived from remote regions, while zinc, copper and lead have predominantly anthropogenic sources. Atmospheric deposition can provide abundant nutrients to vegetation and consequently play a role in the succession of regional ecosystems by affecting the structure, function, diversity, and primary production of the vegetation, especially the exotic or short-lived opportunistic species in arid Asia. Nevertheless, there is not much evidence of the ecological effects of atmospheric deposition on the regional and local scale. The present results may help in further understanding the mechanism of atmospheric deposition as well as providing a motivation for the protection of the ecological environment in arid Asia.

  8. Atmospheric effects on low elevation transmission measurements at EOPACE

    Forand, J.L.; Duffy, M.; Zeisse, C.; Gathman, S.G.; Jong, A.N. de; Dion, D.

    1997-01-01

    An analysis is presented showing the effects of refraction, aerosol extinction, and molecular extinction on transmission measurements obtained during the EO Propagation Assessment in Coastal Environments (EOPACE) campaign carried out in San Diego during March and April 1996. Infrared transmission

  9. Effects of atmospheric deposition of energy-related pollutants on water quality: a review and assessment

    Davis, M.J.

    1981-05-01

    The effects on surface-water quality of atmospheric pollutants that are generated during energy production are reviewed and evaluated. Atmospheric inputs from such sources to the aquatic environment may include trace elements, organic compounds, radionuclides, and acids. Combustion is the largest energy-related source of trace-element emissions to the atmosphere. This report reviews the nature of these emissions from coal-fired power plants and discusses their terrestrial and aquatic effects following deposition. Several simple models for lakes and streams are developed and are applied to assess the potential for adverse effects on surface-water quality of trace-element emissions from coal combustion. The probability of acute impacts on the aquatic environment appears to be low; however, more subtle, chronic effects are possible. The character of acid precipitation is reviewed, with emphasis on aquatic effects, and the nature of existing or potential effects on water quality, aquatic biota, and water supply is considered. The response of the aquatic environment to acid precipitation depends on the type of soils and bedrock in a watershed and the chemical characteristics of the water bodies in question. Methods for identifying regions sensitive to acid inputs are reviewed. The observed impact of acid precipitation ranges from no effects to elimination of fish populations. Coal-fired power plants and various stages of the nuclear fuel cycle release radionuclides to the atmosphere. Radioactive releases to the atmosphere from these sources and the possible aquatic effects of such releases are examined. For the nuclear fuel cycle, the major releases are from reactors and reprocessing. Although aquatic effects of atmospheric releases have not been fully quantified, there seems little reason for concern for man or aquatic biota

  10. Coupling of magnetospheric electrical effects into the global atmospheric electrical circuit

    Hays, P.B.; Roble, R.G.

    1979-01-01

    A quasi-static model of global atmospheric electricity has been constructed (Hays and Roble, 1978) to study the electrical processes in the lower atmosphere and the coupling between solar- and upper- atmosphere-induced variations superimposed upon the global electrical circuit. The paper reviews the essential features of this model and discusses the results obtained thus far on the effects of magnetospheric convection and substorms on the global atmospheric electrical circuit. A schematic diagram of the global quasi-static model is given. It is assumed that thunderstorms act as dipole generators, each with a positive center at the top of the cloud and a negative center a few kilometers lower than the positive center

  11. Mechanism and degree of chemical elements effect on atmosphere corrosion resistance of steels

    Vu Din' Vuj

    1991-01-01

    It follows from the proposed regression equations that falourable effect of chemical elements on steel resistance to atmospheric corrosion is determined by their ability to increase interatom bond stability in iron crystal lattice and form corrosion products with high protection properties. Element positive influence on steel corrosion resistance decreases in the following order: S, P, Si, Mn, Cu, Cr, Ni, C in semiurban tropical atmosphere and S, Mn, Sr, Cu, Ni, Cr in coastal atmosphere. In the latter case C increases corrosion in a greater degree as compared to P. Small ammounts of Mo decrease steel resistance in semiurban atmosphere and almost do not influence it in the coastal one. Possible mechanisms of individual element influence on steel corrosion resistance are considered

  12. Atmospheric Electricity Effects of Eastern Mediterranean Dust Storms

    Katz, Shai; Yair, Yoav; Yaniv, Roy; Price, Colin

    2016-04-01

    We present atmospheric electrical measurements conducted at the Wise Observatory (WO) in Mizpe-Ramon (30035'N, 34045'E) and Mt. Hermon (30024'N, 35051'E), Israel, during two massive and unique dust storms that occurred over the Eastern Mediterranean region on February 10-11 and September 08-12, 2015. The first event transported Saharan dust from Egypt and the Sinai Peninsula in advance of a warm front of a Cyprus low pressure system. In the second event, dust particles were transported from the Syrian desert, which dominates the north-east border with Iraq, through flow associated with a shallow Persian trough system. In both events the concentrations of PM10 particles measured by the air-quality monitoring network of the Israeli Ministry of the Environment in Beer-Sheba reached values > 2200 μg m-3. Aerosol Optical Thickness (AOT) obtained from the AERONET station in Sde-Boker reached values up to 4.0. The gradual intensification of the first event reached peak values on the February 11th > 1200 μg m-3 and an AOT ~ 1.8, while the second dust storm commenced on September 8th with a sharp increase reaching peak values of 2225 μg m-3 and AOT of 4.0. Measurements of the fair weather vertical electric field (Ez) and of the vertical current density (Jz) were conducted continuously with a 1 minute temporal resolution. During the February event, very large fluctuations in the electrical parameters were measured at the WO. The Ez values changed between +1000 and +8000 V m-1 while the Jz fluctuated between -10 and +20 pA m-2 (this is an order of magnitude larger compared to the fair weather current density of ~2 pA m-2. In contrast, during the September event, Ez values registered at WO were between -430 and +10 V m-1 while the Jz fluctuated between -6 and +3 pA m2. For the September event the Hermon site showed Ez and Jz values fluctuating between -460 and +570 V m-1 and -14.5 and +18 pA m-2 respectively. The electric field and current variability, amplitude and the

  13. Redshift measurement of Fermi blazars for the Cherenkov telescope array

    Pita, S.; Goldoni, P.; Boisson, C.; Cotter, G.; Lefaucheur, J.; Lenain, J.-P.; Lindfors, E.; Williams, D. A.

    2017-01-01

    Blazars are active galactic nuclei, and the most numerous High Energy (HE) and Very High Energy (VHE) γ-ray emitters. Their optical emission is often dominated by non-thermal, and, in the case of BL Lacs, featureless continuum radiation. This makes the determination of their redshift extremely difficult. Indeed, as of today only about 50% of γ-ray blazars have a measured spectroscopic redshift. The knowledge of redshift is fundamental because it allows the precise modeling of the VHE emission and also of its interaction with the extragalactic background light (EBL). The beginning of the Cherenkov Telescope Array (CTA) operations in the near future will allow the detection of several hundreds of new blazars. Using the Fermi catalogue of sources above 50 GeV (2FHL), we performed simulations which indicate that a significant fraction of the 2FHL blazars detectable by CTA will not have a measured redshift. As a matter of fact, the organization of observing campaigns to measure the redshift of these blazars has been recognized as a necessary support for the AGN Key Science Project of CTA. We are planning such an observing campaign. In order to optimize our chances of success, we will perform preliminary deep imaging observations aimed at detecting or setting upper limits to the host galaxy. We will then take spectra of the candidates with the brightest host galaxies. Taking advantage of the recent success of an X-shooter GTO observing campaign, these observations will be different with respect to previous ones due to the use of higher resolution spectrographs and of 8 meter class telescopes. We are starting to submit proposals for these observations. In this paper we briefly describe how candidates are selected and the corresponding observation program.

  14. Effect of anthropogenic activities on atmospheric 14C content and radiocarbon chronologies of the future.

    Hajdas, Irka

    2017-04-01

    Radiocarbon (14C) is a naturally produced radioactive isotope of carbon (T1/2=5700 yrs), which is continuously produced in the atmosphere. This occur in a reaction of thermal neutrons, which are secondary particles, products of cosmic rays reactions with the atmosphere, with nitrogen that is commonly present in the atmosphere. Until the mid 19th century the natural concentration showed temporal variability around the mean value (14C / 12C ratio =1.8 x 10-12). However anthropogenic activity created 2 types effects that are changing the 14C concentration of the atmosphere. Industrial revolution triggered adding 14C free (old) carbon that originates from the burning of fossil fuels (Suess effect). This in the late 19th century and early 20th century atmosphere was becoming older. The nuclear tests in the 1950ties caused additional production of radiocarbon atoms (artificial). The effect has been almost double of the natural production and created an excess 14C activity in the atmosphere and in terrestrial carbon bearing materials. The bomb produced 14C has been identified soon after the tests started but the peak (ca. 100% above the normal levels) reached its maximum in 1963 in the northern Hemisphere where most of the tests took place. In the southern Hemisphere the bomb peak reached lower values (ca. 80 % of normal level) and was delayed by ca. 2 years. After the ban on nuclear tests the atmospheric 14C content began to decrease mainly due to the uptake by the ocean but also due to the above mentioned addition old carbon. Continuous monitoring of the atmospheric 14C ratio during the years that followed the nuclear tests, provide basis for environmental studies. Applications range from studies of ocean circulation, CO2 uptake, carbon storage in soils and peat, root turn over time to the medical, forensic and detection of forgeries. However, the so called ' 14C bomb peak' nearly disappeared due to the combined effect of ocean uptake of CO2 and an input to the

  15. A quartz Cherenkov detector for Compton-polarimetry at future e+e- colliders

    List, Jenny; Vauth, Annika; Vormwald, Benedikt; Hamburg Univ.

    2015-02-01

    Precision polarimetry is essential for future e + e - colliders and requires Compton polarimeters designed for negligible statistical uncertainties. In this paper, we discuss the design and construction of a quartz Cherenkov detector for such Compton polarimeters. The detector concept has been developed with regard to the main systematic uncertainties of the polarisation measurements, namely the linearity of the detector response and detector alignment. Simulation studies presented here imply that the light yield reachable by using quartz as Cherenkov medium allows to resolve in the Cherenkov photon spectra individual peaks corresponding to different numbers of Compton electrons. The benefits of the application of a detector with such single-peak resolution to the polarisation measurement are shown for the example of the upstream polarimeters foreseen at the International Linear Collider. Results of a first testbeam campaign with a four-channel prototype confirming simulation predictions for single electrons are presented.

  16. Neutrino superluminality without Cherenkov-like processes in Finslerian special relativity

    Chang Zhe; Li Xin; Wang Sai

    2012-01-01

    Recently, Cohen and Glashow [A.G. Cohen, S.L. Glashow, Phys. Rev. Lett. 107 (2011) 181803] pointed out that the superluminal neutrinos reported by the OPERA would lose their energy rapidly via the Cherenkov-like process. The Cherenkov-like process for the superluminal particles would be forbidden if the principle of special relativity holds in any frame instead violated with a preferred frame. We have proposed that the Finslerian special relativity could account for the data of the neutrino superluminality ( (arXiv:1110.6673 [hep-ph])). The Finslerian special relativity preserves the principle of special relativity and involves a preferred direction while consists with the causality. In this Letter, we prove that the energy-momentum conservation is preserved and the energy-momentum is well defined in Finslerian special relativity. The Cherenkov-like process is forbidden in the Finslerian special relativity. Thus, the superluminal neutrinos would not lose energy in their distant propagation.

  17. Measurement of high-energy electrons by means of a Cherenkov detector in ISTTOK tokamak

    Jakubowski, L., E-mail: lech.Jjakubowski@ipj.gov.p [Andrzej Soltan Institute for Nuclear Studies (IPJ), 05-400 Otwock-Swierk (Poland); Zebrowski, J. [Andrzej Soltan Institute for Nuclear Studies (IPJ), 05-400 Otwock-Swierk (Poland); Plyusnin, V.V. [Association Euratom/IST, Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Av. Rovisco Pais, 1049 - 001 Lisboa (Portugal); Malinowski, K.; Sadowski, M.J.; Rabinski, M. [Andrzej Soltan Institute for Nuclear Studies (IPJ), 05-400 Otwock-Swierk (Poland); Fernandes, H.; Silva, C.; Duarte, P. [Association Euratom/IST, Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Av. Rovisco Pais, 1049 - 001 Lisboa (Portugal)

    2010-10-15

    The paper concerns detectors of the Cherenkov radiation which can be used to measure high-energy electrons escaping from short-living plasma. Such detectors have high temporal (about 1 ns) and spatial (about 1 mm) resolution. The paper describes a Cherenkov-type detector which was designed, manufactured and installed in the ISTTOK tokamak in order to measure fast runaway electrons. The radiator of that detector was made of an aluminium nitride (AlN) tablet with a light-tight filter on its front surface. Cherenkov signals from the radiator were transmitted through an optical cable to a fast photomultiplier. It made possible to perform direct measurements of the runaway electrons of energy above 80 keV. The measured energy values and spatial characteristics of the recorded electrons appeared to be consistent with results of numerical modelling of the runaway electron generation process in the ISTTOK tokamak.

  18. Silica aerogel Cherenkov counter for the KEK B-factory experiment

    Sumiyoshi, T; Enomoto, R; Iijima, T; Suda, R; Leonidopoulos, C; Marlow, D R; Prebys, E; Kawabata, R; Kawai, H; Ooba, T; Nanao, M; Suzuki, K; Ogawa, S; Murakami, A; Khan, M H R

    1999-01-01

    Low-refractive-index silica aerogel is a convenient radiator for threshold-type Cherenkov counters, which are used for particle identification in high-energy physics experiments. For the BELLE detector at the KEK B-Factory we have produced about 2 m sup 3 of hydrophobic silica aerogels of n=1.01-1.03 using a new production method. The particle identification capability of the aerogel Cherenkov counters was tested and 3 sigma pion/proton separation has been achieved at 3.5 GeV/c. Radiation hardness of the aerogels was confirmed up to 9.8 Mrad. The Aerogel Cherenkov counter system (ACC) was successfully installed in the BELLE just before this conference.

  19. Effects of wind turbine wake on atmospheric sound propagation

    Barlas, Emre; Zhu, Wei Jun; Shen, Wen Zhong

    2017-01-01

    In this paper, we investigate the sound propagation from a wind turbine considering the effects of wake-induced velocity deficit and turbulence. In order to address this issue, an advanced approach was developed in which both scalar and vector parabolic equations in two dimensions are solved. Flow...

  20. Effect of Activebag® Modified Atmosphere Packaging on the ...

    SARAH

    2014-11-30

    Nov 30, 2014 ... 1University of Nairobi, Department of Plant Science and Crop Protection P.O Box ... Conclusion: Packaging mangoes in Activebag® after harvest at ripe stage was effective in delaying most of the ... to modify the O2 and CO2 levels within the package ... and sugar consumption in packaged commodities.

  1. Climate risks by radioactive krypton-85 from nuclear fission. Atmospheric-electrical and air-chemical effects of ionizing radiation in the atmosphere

    Kollert, R.

    1994-01-01

    The study shows that krypton-85 from nuclear fission enhances air ionization and, thus, interferes with the atmospheric-electrical system and the water balance of the earth atmosphere. This is reason for concern: There are unforeseeable effects for weather and climate if the krypton-85 content of the earth atmosphere continues to rise. There may be a krypton-specific greenhouse effect and a collapse of the natural atmospheric-electrical field. In addition, human well-being may be expected to be impaired as a result of the diminished atmospheric-electrical field. There is also the risk of radiochemical actions and effects caused-by krypton-85-containing plumes in other air-borne pollutants like the latters' transformation to aggressive oxidants. This implies radiation smog and more acid rain in the countries exposed. This study summarizes findings gained in these issues by various sciences, analyses them and elaborates hypotheses on the actions and effects of krypton-85 on the air, the atmosphere and the climate. (orig./HP) [de

  2. First data from IceAct, an imaging air Cherenkov telescope with SiPMs at the South Pole

    Auffenberg, Jan; Bretz, Thomas; Hansmann, Bengt; Hansmann, Tim; Hebbeker, Thomas; Kemp, Julian; Middendorf, Lukas; Niggemann, Tim; Raedel, Leif; Schaufel, Merlin; Schumacher, Johannes; Stahlberg, Martin; Werhan, Ansgar; Wiebusch, Christopher [RWTH Aachen University (Germany)

    2016-07-01

    IceCube-Gen2 is planned to extend the IceCube Neutrino Observatory at the geographic South Pole. For neutrino astronomy, a large background-free sample of well-reconstructed astrophysical neutrinos is essential. The main background for this signal are muons and neutrinos which are produced in cosmic-ray air showers in the Earth's atmosphere. The coincident detection of these air showers by the surface detector IceTop has been proven to be a powerful veto for atmospheric neutrinos and muons in the field of view of the Southern Hemisphere. This motivates a large extension of IceTop to more efficiently detect cosmic rays, IceVeto. Part of these extension plans is an array of imaging air Cherenkov telescopes, IceAct. A first IceAct prototype is consisting of an SiPM camera and lens optics optimized for harsh environments. Compared to IceTop stations, these telescopes potentially lower the detection threshold for air showers at the cost of a lower duty cycle. We present first data, taken during the commissioning of an IceAct prototype in December 2015 at the South Pole.

  3. TE/TM field solver for particle beam simulations without numerical Cherenkov radiation

    Igor Zagorodnov

    2005-04-01

    Full Text Available The Yee finite-difference time domain method (FDTD is commonly used in wake field and particle-in-cell simulations. However, in accelerator modeling the high energy particles can travel in vacuum faster than their own radiation. This effect is commonly referred to as numerical Cherenkov radiation and is a consequence of numerical grid dispersion. Several numerical approaches are proposed to reduce the dispersion for all angles and for a given frequency range, that justifies itself for domains big in all three directions. On the contrary, in accelerator modeling the transverse dimensions and transverse beam velocity are small, but it is extremely important to eliminate the dispersion error in the well-defined direction of the beam motion for all frequencies. In this paper we propose a new two-level economical conservative scheme for electromagnetic field calculations in three dimensions. The scheme does not have dispersion in the longitudinal direction and is staircase-free (second order convergent. Unlike the FDTD method, it is based on a “transversal-electric/transversal-magnetic” (TE/TM-like splitting of the field components in time. The scheme assures energy and charge conservation. Additionally, the usage of damping terms allows suppressing high frequency noise generated due to the transverse dispersion and the current fluctuations. The dispersion relation of the damping scheme is analyzed. As numerical examples show, the new scheme is much more accurate on the long-time scale than the conventional FDTD approach.

  4. Primary gamma ray selection in a hybrid timing/imaging Cherenkov array

    Postnikov E.B.

    2017-01-01

    Full Text Available This work is a methodical study on hybrid reconstruction techniques for hybrid imaging/timing Cherenkov observations. This type of hybrid array is to be realized at the gamma-observatory TAIGA intended for very high energy gamma-ray astronomy (> 30 TeV. It aims at combining the cost-effective timing-array technique with imaging telescopes. Hybrid operation of both of these techniques can lead to a relatively cheap way of development of a large area array. The joint approach of gamma event selection was investigated on both types of simulated data: the image parameters from the telescopes, and the shower parameters reconstructed from the timing array. The optimal set of imaging parameters and shower parameters to be combined is revealed. The cosmic ray background suppression factor depending on distance and energy is calculated. The optimal selection technique leads to cosmic ray background suppression of about 2 orders of magnitude on distances up to 450 m for energies greater than 50 TeV.

  5. Instrumentation development for an array of water Cherenkov detectors for extensive air shower experiments

    Sheidaei, F.; Bahmanabadi, M.; Keivani, A.; Samimi, J.

    2009-11-01

    A new small array of Cherenkov detectors has been deployed in Tehran, 1200 m above sea level. This array contains four tanks of distilled water with a diameter of 64 cm and a height of 130 cm. The effective area of each tank is about 1382 cm2. They are used to detect air showers and to record the arrival time of the secondary particles. We have collected about 640 000 extensive air showers (EAS) in 8298 h of observation time from November 2006 to October 2007. The distribution of air showers in zenith and azimuth angles has been studied and a cosnθ distribution with n = 6.02 ± 0.01 was obtained for the zenith angle distribution. An asymmetry has been observed in the azimuthal distribution of EAS of cosmic rays due to geomagnetic field. The first and second amplitudes of the asymmetry are AI = 0.183 ± 0.001 and AII = 0.038 ± 0.001. Since the recent results are in good agreement with our previous results of scintillation detectors, and tanks of distilled water are cheaper, we prefer to use them instead of scintillators in a future larger array. By simulation, we have improved the size of the detectors to yield the highest efficiency. The best dimensions for each tank with a photomultiplier tube in the center of its lid are 40 cm in diameter and 60 cm in height.

  6. Atmospheric effects on the NDVI - Strategies for its removal. [Normalized Difference Vegetation Index

    Kaufman, Y. J.; Tanre, D.; Holben, B. N.; Markham, B.; Gitelson, A.

    1992-01-01

    The compositing technique used to derive global vegetation index (NDVI) from the NOAA AVHRR radiances reduces the residual effect of water vapor and aerosol on the NDVI. The reduction in the atmospheric effect is shown using a comprehensive measured data set for desert conditions, and a simulation for grass with continental aerosol. A statistical analaysis of the probability of occurrence of aerosol optical thickness and precipitable water vapor measured in different climatic regimes is used for this simulation. It is concluded that for a long compositing period (e.g., 27 days), the residual aerosol optical thickness and precipitable water vapor are usually too small to be corrected. For a 9-day compositing, the residual average aerosol effect may be about twice the correction uncertainty. For Landsat TM or Earth Observing System Moderate Resolution Imaging Spectrometer (EOS-MODIS) data, the newly defined atmospherically resistant vegetation index (ARVI) is more promising than possible direct atmospheric correction schemes, except for heavy desert dust conditions.

  7. Measuring the attenuation length of water in the CHIPS-M water Cherenkov detector

    Amat, F.; Bizouard, P. [Aix Marseille University Saint-Jerome, 13013 Marseille (France); Bryant, J. [Department of Physics and Astronomy, UCL, Gower St, London WC1E 6BT (United Kingdom); Carroll, T.J.; Rijck, S. De [Department of Physics, University of Texas at Austin, Austin, TX 78712 (United States); Germani, S. [Department of Physics and Astronomy, UCL, Gower St, London WC1E 6BT (United Kingdom); Joyce, T. [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); Kriesten, B. [Department of Physics, College of William & Mary, Williamsburg, VA 23187 (United States); Marshak, M.; Meier, J. [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); Nelson, J.K. [Department of Physics, College of William & Mary, Williamsburg, VA 23187 (United States); Perch, A.J.; Pfützner, M.M. [Department of Physics and Astronomy, UCL, Gower St, London WC1E 6BT (United Kingdom); Salazar, R. [Department of Physics, University of Texas at Austin, Austin, TX 78712 (United States); Thomas, J., E-mail: jennifer.thomas@ucl.ac.uk [Department of Physics and Astronomy, UCL, Gower St, London WC1E 6BT (United Kingdom); Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Trokan-Tenorio, J. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Vahle, P. [Department of Physics, College of William & Mary, Williamsburg, VA 23187 (United States); Wade, R. [Avenir Consulting, Abingdon, Oxfordshire (United Kingdom); Wendt, C. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Whitehead, L.H. [Department of Physics and Astronomy, UCL, Gower St, London WC1E 6BT (United Kingdom); and others

    2017-02-01

    The water at the proposed site of the CHIPS water Cherenkov detector has been studied to measure its attenuation length for Cherenkov light as a function of filtering time. A scaled model of the CHIPS detector filled with water from the Wentworth 2W pit, proposed site of the CHIPS deployment, in conjunction with a 3.2 m vertical column filled with this water, was used to study the transmission of 405 nm laser light. Results consistent with attenuation lengths of up to 100 m were observed for this wavelength with filtration and UV sterilization alone.

  8. Monitor and control systems for the SLD Cherenkov Ring Imaging Detector

    Antilogus, P.; Aston, D.; Bienz, T.; Boston Univ., MA; California Univ., Santa Barbara, CA; California Univ., Santa Cruz, CA; Cincinnati Univ., OH; Rutgers--the State Univ., Piscataway, NJ; Tohoku Univ., Sendai

    1989-10-01

    To help ensure the stable long-term operation of a Cherenkov Ring Detector at high efficiency, a comprehensive monitor and control system is being developed. This system will continuously monitor and maintain the correct operating temperatures, and will provide an on-line monitor and maintain the correct operating temperatures, and will provide an on-line monitor of the pressures, flows, mixing, and purity of the various fluids. In addition the velocities and trajectories of Cherenkov photoelectrons drifting within the imaging chambers will be measured using a pulsed uv lamp and a fiberoptic light injection system. 9 refs., 6 figs

  9. A Cherenkov imager for the charge measurement of the elements of nuclear cosmic radiation

    Sallaz-Damaz, Y.

    2008-10-01

    A Cherenkov imager, CHERCAM (Cherenkov Camera) has been designed and built for the CREAM (Cosmic Ray Energetics and Mass) balloon-borne experiment. The instrument will perform charge measurements of nuclear cosmic-ray over a range extending from proton to iron in the energy domain from 10 10 to 10 15 eV. This work has focused on the development of CHERCAM by creating a simulation of the detector and on the aerogel plan characterization for the radiator. But it has also expanded on the technical aspects of the construction of the detector and its various tests, as well as the development of calibration software and data analysis. (author)

  10. Quality Assurance of Pixel Hybrid Photon Detectors for the LHCb Ring Imaging Cherenkov Counters

    Carson, Laurence

    Pion/kaon discrimination in the LHCb experiment will be provided by two Ring Imaging Cherenkov (RICH) counters. These use arrays of 484 Hybrid Photon Detectors (HPDs) to detect the Cherenkov photons emitted by charged particles traversing the RICH. The results from comprehensive quality assurance tests on the 550 HPDs manufactured for LHCb are described. Leakage currents, dead channel probabilities, dark count rates and ion feedback rates are reported. Furthermore, measurements carried out on a sample of tubes to determine the efficiency of the HPD pixel chip by measuring the summed analogue response from the backplane of the silicon sensor are described.

  11. Measuring the emulsion stability in Cherenkov radiation with insignificant modification of a liquid scintillation spectrometer

    Wiechen, A.; Lorenzen, P.Ch.; Reimerdes, E.H.

    1984-01-01

    A method is described by which the stability of emulsions can be measured by a modified liquid scintillation counter. The 226 Ra external standard source of a commercially available equipment, fixed in the measuring position, is used for the production of Cherenkov radiation in a sample of an emulsion. This Cherenkov radiation is absorbed by the sample due to its turbidity. The turbidity of emulsions follows a typical course with time designated as creaming-up-curve. These curves can be registered automatically in digital form. (author)

  12. The Effect of Varying Atmospheric Pressure upon Habitability and Biosignatures of Earth-like Planets.

    Keles, Engin; Grenfell, John Lee; Godolt, Mareike; Stracke, Barbara; Rauer, Heike

    2018-02-01

    Understanding the possible climatic conditions on rocky extrasolar planets, and thereby their potential habitability, is one of the major subjects of exoplanet research. Determining how the climate, as well as potential atmospheric biosignatures, changes under different conditions is a key aspect when studying Earth-like exoplanets. One important property is the atmospheric mass, hence pressure and its influence on the climatic conditions. Therefore, the aim of the present study is to understand the influence of atmospheric mass on climate, hence habitability, and the spectral appearance of planets with Earth-like, that is, N 2 -O 2 dominated, atmospheres orbiting the Sun at 1 AU. This work utilizes a 1D coupled, cloud-free, climate-photochemical atmospheric column model; varies atmospheric surface pressure from 0.5 to 30 bar; and investigates temperature and key species profiles, as well as emission and brightness temperature spectra in a range between 2 and 20 μm. Increasing the surface pressure up to 4 bar leads to an increase in the surface temperature due to increased greenhouse warming. Above this point, Rayleigh scattering dominates, and the surface temperature decreases, reaching surface temperatures below 273 K (approximately at ∼34 bar surface pressure). For ozone, nitrous oxide, water, methane, and carbon dioxide, the spectral response either increases with surface temperature or pressure depending on the species. Masking effects occur, for example, for the bands of the biosignatures ozone and nitrous oxide by carbon dioxide, which could be visible in low carbon dioxide atmospheres. Key Words: Planetary habitability and biosignatures-Atmospheres-Radiative transfer. Astrobiology 18, 116-132.

  13. The effects of gamma radiation in nitrogen and air atmosphere on the sterility of crocidolomia binotalis zell

    Sastradihardja, S.I.; Sutrisno, S.

    1979-01-01

    Doses of 0, 5, 10, 15, 20, 25, 30, 35, 40, and 45 Krad were given to six-day old sexed pupae in nitrogen and air atmosphere to study its effects on sterility. A dose of 45 Krad caused 100% sterility on male in both air and nitrogen atmosphere on females 100% sterility was found at a dose of 20 Krad in air atmosphere and 25 Krad in nitrogen atmosphere. (author)

  14. Effects of multiple scattering and atmospheric aerosol on the polarization of the twilight sky

    Ugolnikov, Oleg S.; Postylyakov, Oleg V.; Maslov, Igor A.

    2004-01-01

    The paper presents a review of a number of wide-angle polarization CCD-measurements of the twilight sky in V and R color bands with effective wavelengths 550 and 700nm. The basic factors affecting (usually decreasing) the polarization of the twilight sky are the atmospheric aerosol scattering and multiple scattering. These effects were distinguished from each other, and a method of multiple-scattering separation is discussed. The results are compared with the data of numerical simulation of radiative transfer in the atmosphere for different aerosol models. The whole twilight period is divided into different stages with different mechanisms forming the twilight-sky polarization properties

  15. CHERENCUBE: Concept definition and implementation challenges of a Cherenkov-based detector block for PET

    Somlai-Schweiger, I., E-mail: ian.somlai@tum.de; Ziegler, S. I. [Nuklearmedizinische Klinik und Poliklinik, Klinikum rechts der Isar, Technische Universität München, Ismaninger Strasse 22, München 81675 (Germany)

    2015-04-15

    Purpose: A new concept for a depth-of-interaction (DOI) capable time-of-flight (TOF) PET detector is defined, based only on the detection of Cherenkov photons. The proposed “CHERENCUBE” consists of a cubic Cherenkov radiator with position-sensitive photodetectors covering each crystal face. By means of the spatial distribution of the detected photons and their time of arrival, the point of interaction of the gamma-ray in the crystal can be determined. This study analyzes through theoretical calculations and Monte Carlo simulations the potential advantages of the concept toward reaching a Cherenkov-only detector for TOF-PET with DOI capability. Furthermore, an algorithm for the DOI estimation is presented and the requirements for a practical implementation of the proposed concept are defined. Methods: The Monte Carlo simulations consisted of a cubic crystal with one photodetector coupled to each one of the faces of the cube. The sensitive area of the detector matched exactly the crystal size, which was varied in 1 mm steps between 1 × 1 × 1 mm{sup 3} and 10 × 10 × 10 mm{sup 3}. For each size, five independent simulations of ten thousand 511 keV gamma-rays were triggered at a fixed distance of 10 mm. The crystal chosen was PbWO{sub 4}. Its scintillation properties were simulated, but only Cherenkov photons were analyzed. Photodetectors were simulated having perfect photodetection efficiency and infinite time resolution. For every generated particle, the analysis considered its creation process, parent and daughter particles, energy, origin coordinates, trajectory, and time and position of detection. The DOI determination is based on the distribution of the emission time of all photons per event. These values are calculated as a function of the coordinates of detection and origin for every photon. The common origin is estimated by finding the distribution with the most similar emission time-points. Results: Detection efficiency increases with crystal size from

  16. Seed disinfection effect of atmospheric pressure plasma and low pressure plasma on Rhizoctonia solani.

    Nishioka, Terumi; Takai, Yuichiro; Kawaradani, Mitsuo; Okada, Kiyotsugu; Tanimoto, Hideo; Misawa, Tatsuya; Kusakari, Shinichi

    2014-01-01

    Gas plasma generated and applied under two different systems, atmospheric pressure plasma and low pressure plasma, was used to investigate the inactivation efficacy on the seedborne pathogenic fungus, Rhizoctonia solani, which had been artificially introduced to brassicaceous seeds. Treatment with atmospheric plasma for 10 min markedly reduced the R. solani survival rate from 100% to 3% but delayed seed germination. The low pressure plasma treatment reduced the fungal survival rate from 83% to 1.7% after 10 min and the inactivation effect was dependent on the treatment time. The seed germination rate after treatment with the low pressure plasma was not significantly different from that of untreated seeds. The air temperature around the seeds in the low pressure system was lower than that of the atmospheric system. These results suggested that gas plasma treatment under low pressure could be effective in disinfecting the seeds without damaging them.

  17. Effective pollutant emission heights for atmospheric transport modelling based on real-world information.

    Pregger, Thomas; Friedrich, Rainer

    2009-02-01

    Emission data needed as input for the operation of atmospheric models should not only be spatially and temporally resolved. Another important feature is the effective emission height which significantly influences modelled concentration values. Unfortunately this information, which is especially relevant for large point sources, is usually not available and simple assumptions are often used in atmospheric models. As a contribution to improve knowledge on emission heights this paper provides typical default values for the driving parameters stack height and flue gas temperature, velocity and flow rate for different industrial sources. The results were derived from an analysis of the probably most comprehensive database of real-world stack information existing in Europe based on German industrial data. A bottom-up calculation of effective emission heights applying equations used for Gaussian dispersion models shows significant differences depending on source and air pollutant and compared to approaches currently used for atmospheric transport modelling.

  18. Water cycles in closed ecological systems: effects of atmospheric pressure.

    Rygalov, Vadim Y; Fowler, Philip A; Metz, Joannah M; Wheeler, Raymond M; Bucklin, Ray A

    2002-01-01

    In bioregenerative life support systems that use plants to generate food and oxygen, the largest mass flux between the plants and their surrounding environment will be water. This water cycle is a consequence of the continuous change of state (evaporation-condensation) from liquid to gas through the process of transpiration and the need to transfer heat (cool) and dehumidify the plant growth chamber. Evapotranspiration rates for full plant canopies can range from ~1 to 10 L m-2 d-1 (~1 to 10 mm m-2 d-1), with the rates depending primarily on the vapor pressure deficit (VPD) between the leaves and the air inside the plant growth chamber. VPD in turn is dependent on the air temperature, leaf temperature, and current value of relative humidity (RH). Concepts for developing closed plant growth systems, such as greenhouses for Mars, have been discussed for many years and the feasibility of such systems will depend on the overall system costs and reliability. One approach for reducing system costs would be to reduce the operating pressure within the greenhouse to reduce structural mass and gas leakage. But managing plant growth environments at low pressures (e.g., controlling humidity and heat exchange) may be difficult, and the effects of low-pressure environments on plant growth and system water cycling need further study. We present experimental evidence to show that water saturation pressures in air under isothermal conditions are only slightly affected by total pressure, but the overall water flux from evaporating surfaces can increase as pressure decreases. Mathematical models describing these observations are presented, along with discussion of the importance for considering "water cycles" in closed bioregenerative life support systems.

  19. Water cycles in closed ecological systems: effects of atmospheric pressure

    Rygalov, Vadim Y.; Fowler, Philip A.; Metz, Joannah M.; Wheeler, Raymond M.; Bucklin, Ray A.; Sager, J. C. (Principal Investigator)

    2002-01-01

    In bioregenerative life support systems that use plants to generate food and oxygen, the largest mass flux between the plants and their surrounding environment will be water. This water cycle is a consequence of the continuous change of state (evaporation-condensation) from liquid to gas through the process of transpiration and the need to transfer heat (cool) and dehumidify the plant growth chamber. Evapotranspiration rates for full plant canopies can range from 1 to 10 L m-2 d-1 (1 to 10 mm m-2 d-1), with the rates depending primarily on the vapor pressure deficit (VPD) between the leaves and the air inside the plant growth chamber. VPD in turn is dependent on the air temperature, leaf temperature, and current value of relative humidity (RH). Concepts for developing closed plant growth systems, such as greenhouses for Mars, have been discussed for many years and the feasibility of such systems will depend on the overall system costs and reliability. One approach for reducing system costs would be to reduce the operating pressure within the greenhouse to reduce structural mass and gas leakage. But managing plant growth environments at low pressures (e.g., controlling humidity and heat exchange) may be difficult, and the effects of low-pressure environments on plant growth and system water cycling need further study. We present experimental evidence to show that water saturation pressures in air under isothermal conditions are only slightly affected by total pressure, but the overall water flux from evaporating surfaces can increase as pressure decreases. Mathematical models describing these observations are presented, along with discussion of the importance for considering "water cycles" in closed bioregenerative life support systems.

  20. Remote Cherenkov imaging-based quality assurance of a magnetic resonance image-guided radiotherapy system.

    Andreozzi, Jacqueline M; Mooney, Karen E; Brůža, Petr; Curcuru, Austen; Gladstone, David J; Pogue, Brian W; Green, Olga

    2018-06-01

    Tools to perform regular quality assurance of magnetic resonance image-guided radiotherapy (MRIgRT) systems should ideally be independent of interference from the magnetic fields. Remotely acquired optical Cherenkov imaging-based dosimetry measurements in water were investigated for this purpose, comparing measures of dose accuracy, temporal dynamics, and overall integrated IMRT delivery. A 40 × 30.5 × 37.5 cm 3 water tank doped with 1 g/L of quinine sulfate was imaged using an intensified charge-coupled device (ICCD) to capture the Cherenkov emission while being irradiated by a commercial MRIgRT system (ViewRay™). The ICCD was placed down-bore at the end of the couch, 4 m from treatment isocenter and behind the 5-Gauss line of the 0.35-T MRI. After establishing optimal camera acquisition settings, square beams of increasing size (4.2 × 4.2 cm 2 , 10.5 × 10.5 cm 2 , and 14.7 × 14.7 cm 2 ) were imaged at 0.93 frames per second, from an individual cobalt-60 treatment head, to develop projection measures related to percent depth dose (PDD) curves and cross beam profiles (CPB). These Cherenkov-derived measurements were compared to ionization chamber (IC) and radiographic film dosimetry data, as well as simulation data from the treatment planning system (TPS). An intensity-modulated radiotherapy (IMRT) commissioning plan from AAPM TG-119 (C4:C-Shape) was also imaged at 2.1 frames per second, and the single linear sum image from 509 s of plan delivery was compared to the dose volume prediction generated by the TPS using gamma index analysis. Analysis of standardized test target images (1024 × 1024 pixels) yielded a pixel resolution of 0.37 mm/pixel. The beam width measured from the Cherenkov image-generated projection CBPs was within 1 mm accuracy when compared to film measurements for all beams. The 502 point measurements (i.e., pixels) of the Cherenkov image-based projection percent depth dose curves (pPDDs) were compared to p

  1. Effects of dissociative recombination on the composition of planetary atmospheres

    Fox, Jane L

    2005-01-01

    Because dissociative recombination (DR) reactions of molecular ions are often highly exothermic, in the thermospheres of the Earth and planets DR may be a source of translationally and internally excited fragments. DR is important, therefore, for thermospheric neutral heating; if the excited fragments radiate to space, however, DR may be also a source of thermospheric cooling. DR may produce metastable fragments, which may live long enough to participate in reactions that are not available to ground state species. It is rare, however, for DR to be a significant source of minor species in their ground states. An exception appears to be the DR of CO + 2 , which has recently been found to produce C + O 2 about 9% of the time by Seiersen et al.. Because of the significant rearrangement of bonds that must take place, the branching ratio for the latter channel has been assumed to be negligible, and DR of CO + 2 has been assumed to produce mainly CO + O. In order to test the effect of including the branching ratio of CO + 2 DR that produces C + O 2 on the ambient densities of thermal and escaping C in planetary thermospheres,we have we have constructed revised models of the thermospheres/ionospheres of Mars and Venus. Because of space limitations, we discuss here only the high solar activity models. For Mars, we find that DR of CO + 2 is the most important source of thermal C, but that the production rate of escaping C is not increased. There are important differences between the thermospheres of Venus and Mars, and we find that the inclusion of the C + O 2 channel in the Venus models increases the production rate of atomic carbon in the Venus thermosphere by only 10-16%. At high altitudes on Venus, C + is mostly produced by photoionization and electron-impact ionization of C, with some contribution from the charge transfer reaction, O + + C → C + + O. We compare our computed C density altitude profiles to those inferred by Paxton from Pioneer Venus Orbiter Ultraviolet

  2. The Effect of Atmospheric Scattering as Inferred from the Rocket-Borne UV Radiometer Measurements

    Jhoon Kim

    1997-06-01

    Full Text Available Radiometers in UV and visible wavelengths were onboard the Korean Sounding Rocket(KSR-1 and 2 which were launched on June 4th and September 1st, 1993. These radiometers were designed to capture the solar radiation during the ascending period of the rocket flight. The purpose of the instrument was to measure the vertical profiles of stratospheric ozone densities. Since the instrument measured the solar radiation from the ground to its apogee, it is possible to investigate the altitude variation of the measured intensity and to estimate the effect of atmospheric scattering by comparing the UV and visible intensity. The visible channel was a reference because the 450-nm wavelength is in the atmospheric window region, where the solar radiation is transmitted through the atmosphere without being absorbed by other atmospheric gases. The use of 450-nm channel intensity as a reference should be limited to the altitude ranges above the certain altitudes, say 20 to 25§° where the signals are not perturbed by atmospheric scattering effects.

  3. Effects of shrub and tree cover increase on the near-surface atmosphere in northern Fennoscandia

    J. H. Rydsaa

    2017-09-01

    Full Text Available Increased shrub and tree cover in high latitudes is a widely observed response to climate change that can lead to positive feedbacks to the regional climate. In this study we evaluate the sensitivity of the near-surface atmosphere to a potential increase in shrub and tree cover in the northern Fennoscandia region. We have applied the Weather Research and Forecasting (WRF model with the Noah-UA land surface module in evaluating biophysical effects of increased shrub cover on the near-surface atmosphere at a fine resolution (5.4 km  ×  5.4 km. Perturbation experiments are performed in which we prescribe a gradual increase in taller vegetation in the alpine shrub and tree cover according to empirically established bioclimatic zones within the study region. We focus on the spring and summer atmospheric response. To evaluate the sensitivity of the atmospheric response to inter-annual variability in climate, simulations were conducted for two contrasting years, one warm and one cold. We find that shrub and tree cover increase leads to a general increase in near-surface temperatures, with the highest influence seen during the snowmelt season and a more moderate effect during summer. We find that the warming effect is stronger in taller vegetation types, with more complex canopies leading to decreases in the surface albedo. Counteracting effects include increased evapotranspiration, which can lead to increased cloud cover, precipitation, and snow cover. We find that the strength of the atmospheric feedback is sensitive to snow cover variations and to a lesser extent to summer temperatures. Our results show that the positive feedback to high-latitude warming induced by increased shrub and tree cover is a robust feature across inter-annual differences in meteorological conditions and will likely play an important role in land–atmosphere feedback processes in the future.

  4. The Cherenkov Telescope Array Observatory: top level use cases

    Bulgarelli, A.; Kosack, K.; Hinton, J.; Tosti, G.; Schwanke, U.; Schwarz, J.; Colomé, P.; Conforti, V.; Khelifi, B.; Goullon, J.; Ong, R.; Markoff, S.; Contreras, J. L.; Lucarelli, F.; Antonelli, L. A.; Bigongiari, C.; Boisson, C.; Bosnjak, Z.; Brau-Nogué, S.; Carosi, A.; Chen, A.; Cotter, G.; Covino, S.; Daniel, M.; De Cesare, G.; de Ona Wilhelmi, E.; Della Volpe, M.; Di Pierro, F.; Fioretti, V.; Füßling, M.; Garczarczyk, M.; Gaug, M.; Glicenstein, J. F.; Goldoni, P.; Götz, D.; Grandi, P.; Heller, M.; Hermann, G.; Inoue, S.; Knödlseder, J.; Lenain, J.-P.; Lindfors, E.; Lombardi, S.; Luque-Escamilla, P.; Maier, G.; Marisaldi, M.; Mundell, C.; Neyroud, N.; Noda, K.; O'Brien, P.; Petrucci, P. O.; Martí Ribas, J.; Ribó, M.; Rodriguez, J.; Romano, P.; Schmid, J.; Serre, N.; Sol, H.; Schussler, F.; Stamerra, A.; Stolarczyk, T.; Vandenbrouck, J.; Vercellone, S.; Vergani, S.; Zech, A.; Zoli, A.

    2016-08-01

    Today the scientific community is facing an increasing complexity of the scientific projects, from both a technological and a management point of view. The reason for this is in the advance of science itself, where new experiments with unprecedented levels of accuracy, precision and coverage (time and spatial) are realised. Astronomy is one of the fields of the physical sciences where a strong interaction between the scientists, the instrument and software developers is necessary to achieve the goals of any Big Science Project. The Cherenkov Telescope Array (CTA) will be the largest ground-based very high-energy gamma-ray observatory of the next decades. To achieve the full potential of the CTA Observatory, the system must be put into place to enable users to operate the telescopes productively. The software will cover all stages of the CTA system, from the preparation of the observing proposals to the final data reduction, and must also fit into the overall system. Scientists, engineers, operators and others will use the system to operate the Observatory, hence they should be involved in the design process from the beginning. We have organised a workgroup and a workflow for the definition of the CTA Top Level Use Cases in the context of the Requirement Management activities of the CTA Observatory. Scientists, instrument and software developers are collaborating and sharing information to provide a common and general understanding of the Observatory from a functional point of view. Scientists that will use the CTA Observatory will provide mainly Science Driven Use Cases, whereas software engineers will subsequently provide more detailed Use Cases, comments and feedbacks. The main purposes are to define observing modes and strategies, and to provide a framework for the flow down of the Use Cases and requirements to check missing requirements and the already developed Use-Case models at CTA sub-system level. Use Cases will also provide the basis for the definition of

  5. Effects of Atmospheric Dynamics on CO2 Seepage at Mammoth Mountain, California USA

    Egemen Ogretim

    2013-12-01

    Full Text Available In the past few decades, atmospheric effects on the variation of seepage from soil have been studied in disciplines such as volcanology, environmental protection, safety and health hazard avoidance. Recently, monitoring of potential leakage from the geologic sequestration of carbon has been added to this list. Throughout these diverse fields, barometric pumping and presence of steady winds are the two most commonly investigated atmospheric factors. These two factors have the effect of pumping gas into and out of the unsaturated zone, and sweeping the gas in the porous medium. This study focuses on two new factors related to atmosphere in order to explain the CO2 seepage anomalies observed at the Horseshoe Lake tree kill near Mammoth Mountain, CA, where the temporal variation of seepage due to a storm event could not be explained by the two commonly studied effects. First, the interaction of the lower atmospheric dynamics and the ground topography is considered for its effect on the seepage variation over an area that is linked through high-porosity, high-permeability soils and/or fracture networks. Second, the regional pressure fronts that impose significant pressure oscillation over an area are studied. The comparison of the computer simulation results with the experimental measurements suggests that the seepage anomaly observed at the Horseshoe Lake Tree Kill could be due to the unsteady effects caused by regional pressure fronts.

  6. Enhanced Cherenkov phase matching terahertz wave generation via a magnesium oxide doped lithium niobate ridged waveguide crystal

    K. Takeya

    2017-01-01

    Full Text Available When combined with a nonlinear waveguide crystal, Cherenkov phase matching allows for highly effective generation of high power and broadband terahertz (THz waves. Using a ridged Lithium Niobate (LiNbO3 waveguide coupled with a specially designed silicon lens, we successfully generated THz waves with intensity of approximately three orders of magnitude stronger than those from conventional photoconductive antenna. The broadband spectrum was from 0.1 THz to 7 THz with a maximum dynamic range of 80 dB. The temporal shape of time domain pulse is a regular single cycle which could be used for high depth resolution time of flight tomography. The generated THz wave can also be easily monitored by compact room-temperature THz camera, enabling us to determine the spatial characteristics of the THz propagation.

  7. GEOSPATIAL ANALYSIS OF ATMOSPHERIC HAZE EFFECT BY SOURCE AND SINK LANDSCAPE

    T. Yu

    2017-09-01

    Full Text Available Based on geospatial analysis model, this paper analyzes the relationship between the landscape patterns of source and sink in urban areas and atmospheric haze pollution. Firstly, the classification result and aerosol optical thickness (AOD of Wuhan are divided into a number of square grids with the side length of 6 km, and the category level landscape indices (PLAND, PD, COHESION, LPI, FRAC_MN and AOD of each grid are calculated. Then the source and sink landscapes of atmospheric haze pollution are selected based on the analysis of the correlation between landscape indices and AOD. Next, to make the following analysis more efficient, the indices selected before should be determined through the correlation coefficient between them. Finally, due to the spatial dependency and spatial heterogeneity of the data used in this paper, spatial autoregressive model and geo-weighted regression model are used to analyze atmospheric haze effect by source and sink landscape from the global and local level. The results show that the source landscape of atmospheric haze pollution is the building, and the sink landscapes are shrub and woodland. PLAND, PD and COHESION are suitable for describing the atmospheric haze effect by source and sink landscape. Comparing these models, the fitting effect of SLM, SEM and GWR is significantly better than that of OLS model. The SLM model is superior to the SEM model in this paper. Although the fitting effect of GWR model is more unsuited than that of SLM, the influence degree of influencing factors on atmospheric haze of different geography can be expressed clearer. Through the analysis results of these models, following conclusions can be summarized: Reducing the proportion of source landscape area and increasing the degree of fragmentation could cut down aerosol optical thickness; And distributing the source and sink landscape evenly and interspersedly could effectively reduce aerosol optical thickness which represents

  8. Geospatial Analysis of Atmospheric Haze Effect by Source and Sink Landscape

    Yu, T.; Xu, K.; Yuan, Z.

    2017-09-01

    Based on geospatial analysis model, this paper analyzes the relationship between the landscape patterns of source and sink in urban areas and atmospheric haze pollution. Firstly, the classification result and aerosol optical thickness (AOD) of Wuhan are divided into a number of square grids with the side length of 6 km, and the category level landscape indices (PLAND, PD, COHESION, LPI, FRAC_MN) and AOD of each grid are calculated. Then the source and sink landscapes of atmospheric haze pollution are selected based on the analysis of the correlation between landscape indices and AOD. Next, to make the following analysis more efficient, the indices selected before should be determined through the correlation coefficient between them. Finally, due to the spatial dependency and spatial heterogeneity of the data used in this paper, spatial autoregressive model and geo-weighted regression model are used to analyze atmospheric haze effect by source and sink landscape from the global and local level. The results show that the source landscape of atmospheric haze pollution is the building, and the sink landscapes are shrub and woodland. PLAND, PD and COHESION are suitable for describing the atmospheric haze effect by source and sink landscape. Comparing these models, the fitting effect of SLM, SEM and GWR is significantly better than that of OLS model. The SLM model is superior to the SEM model in this paper. Although the fitting effect of GWR model is more unsuited than that of SLM, the influence degree of influencing factors on atmospheric haze of different geography can be expressed clearer. Through the analysis results of these models, following conclusions can be summarized: Reducing the proportion of source landscape area and increasing the degree of fragmentation could cut down aerosol optical thickness; And distributing the source and sink landscape evenly and interspersedly could effectively reduce aerosol optical thickness which represents atmospheric haze

  9. The effects of the diurnal atmospheric variability on entry, descent and landing on Mars

    Marčeta D.

    2014-01-01

    Full Text Available Landing on Mars is extremely challenging task due to the fact that the Martian atmosphere is the most hostile environment in the Solar system to perform the entry, descent and landing (EDL process, because it is thick enough to create substantial heating of the entry vehicle but not thick enough to reduce its velocity to the one necessary for safe landing. Beside this, the atmosphere is very dynamic mainly due to high eccentricity of the Martian orbit, obliquity of the orbital to the equatorial plane and close alignment of the winter solstice and the orbital perihelion. Although seasonal variations of atmospheric parameters are significantly larger than the diurnal, it is very important to analyze diurnal cycles as they can significantly change vertical and horizontal atmospheric profiles in very short time intervals. This can present a serious threat to missions which have very precise timings and specific requirements such as the requirement for the daytime landing to enable ground images acquisition during the descent and landing phase. A 3-degrees-of-freedom trajectory integration routine was combined with the Mars Global Reference Atmospheric Model (Mars-GRAM to identify the dependence of the EDL profiles on the diurnal cycles of atmospheric parameters throughout the Martian year. The obtained results show that the influence of the diurnal cycles is the largest at the equator and decreases relatively symmetrically towards the poles with a slightly stronger influence in the northern hemisphere. Also, there is a significant influence of the orbital position of Mars on the effect of diurnal atmospheric variations which causes that, around the orbital perihelion and winter solstice, there is some kind of inversion of the dependance of optimal entry timing on latitude of the landing site comparing to the rest of the Martian year. [Projekat Ministarstva nauke Republike Srbije, br. 176002

  10. Effect of Mechanical Alloying Atmospheres and Oxygen Concentration on Mechanical Properties of ODS Ferritic Steels

    Noh, Sanghoon; Choi, Byoungkwon; Han, Changhee; Kim, Kibaik; Kang, Sukhoon; Chun, Youngbum; Kim, Taekyu

    2013-01-01

    Finely dispersed nano-oxide particles with a high number density in the homogeneous grain matrix are essential to achieve superior mechanical properties at high temperatures, and these unique microstructures can be obtained through the mechanical alloying (MA) and hot consolidation process. The microstructure and mechanical property of ODS steel significantly depends on its powder property and the purity after the MA process. These contents should be carefully controlled to improve the mechanical property at elevated temperature. In particular, appropriate the control of oxygen concentration improves the mechanical property of ODS steel at high temperature. An effective method is to control the mechanical alloying atmosphere by high purity inert gas. In the present study, the effects of mechanical alloying atmospheres and oxygen concentration on the mechanical property of ODS steel were investigated. ODS ferritic alloys were fabricated in various atmospheres, and the HIP process was used to investigate the effects of MA atmospheres and oxygen concentration on the microstructure and mechanical property. ODS ferritic alloys milled in an Ar-H 2 mixture, and He is effective to reduce the excess oxygen concentration. The YH 2 addition made an extremely reduced oxygen concentration by the internal oxygen reduction reaction and resulted in a homogeneous microstructure and superior creep strength

  11. Environmental consequences of nuclear war (SCOPE 28), Vol. 1: Physical and atmospheric effects

    Pittock, A.B.; Ackerman, T.P.; Crutzen, P.J.; MacCracken, M.C.; Shapiro, C.S.; Turco, R.P.

    1986-01-01

    This book presents an interdisciplinary look at current scientific knowledge of the possible environmental consequences of a nuclear war. The authors assess the likely magnitude of changes in sunlight, temperature, precipitation, atmospheric chemistry, and more. Volume One reviews existing nuclear arsenals, war scenarios, immediate and subsequent effects

  12. Corrections for hydrostatic atmospheric models: radii and effective temperatures of Wolf Rayet stars

    Loore, C. de; Hellings, P.; Lamers, H.J.G.L.M.

    1982-01-01

    With the assumption of plane-parallel hydrostatic atmospheres, used generally for the computation of evolutionary models, the radii of WR stars are seriously underestimated. The true atmospheres may be very extended, due to the effect of the stellar wind. Instead of these hydrostatic atmospheres the authors consider dynamical atmospheres adopting a velocity law. The equation of the optical depth is integrated outwards using the equation of continuity. The ''hydrostatic'' radii are to be multiplied with a factor 2 to 8, and the effective temperatures with a factor 0.8 to 0.35 when Wolf Rayet characteristics for the wind are considered, and WR mass loss rates are used. With these corrections the effective temperatures of the theoretical models, which are helium burning Roche lobe overflow remnants, range between 30,000 K and 50,000 K. Effective temperatures calculated in the hydrostatic hypothesis can be as high as 150,000 K for helium burning RLOF-remnants with WR mass loss rates. (Auth.)

  13. The effect of external electron injection and the environment composition on development of atmospheric discharge investigation

    Bogachenkov, V.A.; Oginov, A.V.; Chajkovskij, S.A.; Shpakov, K.V.

    2012-01-01

    The effect of external electron injection (with energy about 150 keV) on initial phase development of the high-voltage (1.0-1.2 MV) long (500-700 mm) gas discharge is investigated. The experiments were conducted in atmospheric pressure air and in a mixture of air and water droplet phase [ru

  14. Comparison of solidification temperatures of different rare earth sesquioxides; effect of atmosphere

    Coutures, J.-P.; Verges, R.; Foex, M.

    1975-01-01

    The measurement of the solidification point of the rare earth sesquioxides shows anomalies for La 2 O 3 , Gd 2 O 3 , Lu 2 O 3 and allows to find the well known ceric group and yttric group. The effects of the atmosphere on the refractory character are generally low. An interpretation in order to explain the observed changes, is proposed [fr

  15. Monitoring the effects of atmospheric ethylene near polyethylene manufacturing plants with two sensitive plant species

    Tonneijck, A.E.G.; Berge, ten W.F.; Jansen, B.P.

    2003-01-01

    Data of a multi-year (1977-1983) biomonitoring programme with marigold and petunia around polyethylene manufacturing plants was analysed to assess plant responses to atmospheric ethylene and to determine the area at risk for the phytotoxic effects of this pollutant. In both species, flower formation

  16. Near-Surface Effects of Free Atmosphere Stratification in Free Convection

    Mellado, Juan Pedro; Heerwaarden, van C.C.; Garcia, Jade Rachele

    2016-01-01

    The effect of a linear stratification in the free atmosphere on near-surface properties in a free convective boundary layer (CBL) is investigated by means of direct numerical simulation. We consider two regimes: a neutral stratification regime, which represents a CBL that grows into a residual

  17. Differential cardiac effects in rats exposed to atmospheric smog generated from isoprene versus toluene

    The results of this study demonstrate that atmospheric smog generated from both isoprene and toluene cause cardiac effects in rats. In addition, it appears that smog from toluene is more toxic in terms of cardiac arrhythmogenicity. Smog, which is a comple...

  18. Effect of atmospheric organic complexation on iron-bearing dust solubility

    R. Paris

    2013-05-01

    Full Text Available Recent studies reported that the effect of organic complexation may be a potentially important process to be considered by models estimating atmospheric iron flux to the ocean. In this study, we investigated this process effect by a series of dissolution experiments on iron-bearing dust in the presence or the absence of various organic compounds (acetate, formate, oxalate, malonate, succinate, glutarate, glycolate, lactate, tartrate and humic acid as an analogue of humic like substances, HULIS typically found in atmospheric waters. Only 4 of tested organic ligands (oxalate, malonate, tartrate and humic acid caused an enhancement of iron solubility which was associated with an increase of dissolved Fe(II concentrations. For all of these organic ligands, a positive linear dependence of iron solubility to organic concentrations was observed and showed that the extent of organic complexation on iron solubility decreased in the following order: oxalate >malonate = tartrate > humic acid. This was attributed to the ability of electron donors of organic ligands and implies a reductive ligand-promoted dissolution. This study confirms that among the known atmospheric organic binding ligands of Fe, oxalate is the most effective ligand promoting dust iron solubility and showed, for the first time, the potential effect of HULIS on iron dissolution under atmospheric conditions.

  19. Fundamental remote sensing science research program. Part 1: Scene radiation and atmospheric effects characterization project

    Murphy, R. E.; Deering, D. W.

    1984-01-01

    Brief articles summarizing the status of research in the scene radiation and atmospheric effect characterization (SRAEC) project are presented. Research conducted within the SRAEC program is focused on the development of empirical characterizations and mathematical process models which relate the electromagnetic energy reflected or emitted from a scene to the biophysical parameters of interest.

  20. Comparative cardiopulmonary effects of particulate matter- and ozone-enhanced smog atmospheres in mice

    This study was conducted to compare the cardiac effects of particulate matter (PM)-enhanced and ozone(O3)-enhanced smog atmospheres in mice. We hypothesized that O3-enhanced smog would cause greater cardiac dysfunction than PM-enhanced smog due to the higher concentrations of irr...

  1. Effects of initiating anaerobic digestion of layer-hen poultry dung at sub-atmospheric pressure

    Ngumah, Chima C.; Ogbulie, Jude N.; Orji, Justina C.; Amadi, Ekperechi S.

    2013-01-01

    This study investigated the effects of initiating anaerobic digestion (AD) of dry layer-hen poultry dung at the sub-atmospheric pressure of -30 cmHg on biodegradation, biogasification, and biomethanation. The setup was performed as a batch process at an average ambient temperature of 29±2 ºC and a retention time of 15 days. Comparisons were made with two other experiments which were both begun at ambient atmospheric pressure; one was inoculated with digestate from a previous layer-hen dung AD...

  2. Effect of Atmospheric Pressure Plasma and Subsequent Enzymatic Treatment on Flax Fabrics

    Zhong Shaofeng; Yang Bin; Ou Qiongrong

    2015-01-01

    The objective is to investigate the effect of atmospheric pressure dielectric barrier discharge (APDBD) plasma and subsequent cellulase enzyme treatment on the properties of flax fabrics. The changes of surface morphology and structure, physico-mechanical properties, hydrophilicity, bending properties, whiteness, and dyeing properties of the treated substrate were investigated. The results indicated that atmospheric pressure dielectric barrier discharge plasma pre-treatment and subsequent cellulase enzyme treatment could diminish the hairiness of flax fabrics, endowing the flax fabrics with good bending properties, water uptake and fiber accessibility while keeping their good mechanical properties compared with those treated with cellulase enzyme alone. (paper)

  3. Theory for the effects of turbulence in a planetary atmosphere on radio occultation

    Woo, R.; Ishimaru, A.

    1974-01-01

    Rytov's method is used to formulate the correlation functions for log-amplitude and phase fluctuations for both spherical and plane wave propagation in a turbulent medium whose correlation function for refractive index fluctuations is described by the product of a function of the average coordinate and a function of the difference coordinate. The results are applied to the study of radio occultation effects due to the atmosphere of Venus in the case of a flyby space probe. It is assumed that turbulence of isotropic and smoothly varying characteristics occurs in the Venusian atmosphere.

  4. Effect of different sound atmospheres on SnO2:Sb thin films prepared by dip coating technique

    Kocyigit, Adem; Ozturk, Erhan; Ejderha, Kadir; Turgut, Guven

    2017-11-01

    Different sound atmosphere effects were investigated on SnO2:Sb thin films, which were deposited with dip coating technique. Two sound atmospheres were used in this study; one of them was nay sound atmosphere for soft sound, another was metallic sound for hard sound. X-ray diffraction (XRD) graphs have indicated that the films have different orientations and structural parameters in quiet room, metallic and soft sound atmospheres. It could be seen from UV-Vis spectrometer measurements that films have different band gaps and optical transmittances with changing sound atmospheres. Scanning electron microscope (SEM) and AFM images of the films have been pointed out that surfaces of films have been affected with changing sound atmospheres. The electrical measurements have shown that films have different I-V plots and different sheet resistances with changing sound atmospheres. These sound effects may be used to manage atoms in nano dimensions.

  5. Effects of sintering atmosphere and temperature on structural and magnetic properties of Ni-Cu-Zn ferrite nano-particles: Magnetic enhancement by a reducing atmosphere

    Gholizadeh, Ahmad, E-mail: gholizadeh@du.ac.ir; Jafari, Elahe, E-mail: ah_gh1359@yahoo.com

    2017-01-15

    In this work, effects of sintering atmosphere and temperature on structural and magnetic properties of Ni{sub 0.3}Cu{sub 0.2}Zn{sub 0.5}Fe{sub 2}O{sub 4} nanoparticles prepared by citrate precursor method have been studied. The structural characterization of the samples by X-ray powder diffraction and FT-IR spectroscopy is evidence for formation of a cubic structure with no presence of impurity phase. Calculated values of crystallite size and unit cell parameter show an increase with sintering temperature under different atmospheres. Variation of saturation magnetization with sintering temperature and atmosphere can be attributed to change of three factors: magnetic core size, inversion parameter and the change of Fe{sup 3+}-ion concentration due to the presence of Fe{sup 4+} and Fe{sup 2+} ions. The saturation magnetization gradually grows with sintering temperature due to increase of magnetic core size and a maximum 63 emu/g was achieved at 600 °C under carbon monoxide-ambient atmosphere. - Highlights: • Different sintering atmosphere and temperature cause substantial differences in Ni{sub 0.3}Cu{sub 0.2}Zn{sub 0.5}Fe{sub 2}O{sub 4} nanoparticles. • The saturation magnetization gradually grows. • A maximum 63 emu/g was achieved at 600 °C under a reducing atmosphere.

  6. Cherenkov and scintillation light separation on the CheSS experiment

    Caravaca, Javier; Land, Benjamin; Descamps, Freija; Orebi Gann, Gabriel D.

    2016-09-01

    Separation of the scintillation and Cherenkov light produced in liquid scintillators enables outstanding capabilities for future particle detectors, the most relevant being: particle directionality information in a low energy threshold detector and improved particle identification. The CheSS experiment uses an array of small, fast photomultipliers (PMTs) and state-of-the-art electronics to demonstrate the reconstruction of a Cherenkov ring in liquid scintillator using two techniques: based on the photon density and using the photon hit time information. A charged particle ionizing a scintillation medium produces a prompt Cherenkov cone and late isotropic scintillation light, typically delayed by several ns. The fast response of our PMTs and DAQ provides a precision well below the ns level, making possible the time separation. Furthermore, the usage of the new developed water-based liquid scintillators (WbLS) enhances the separation since it allows tuning of the Cherenkov/Scintillation ratio. Latest results on the separation for pure liquid scintillators and WbLS will be presented.

  7. Gaseous photomultipliers for the readout of scintillators and detection Cherenkov radiation

    Peskov, V.; Borovik-Romanov, A.

    1993-11-01

    The latest achievements in the development of gaseous detectors for registering UV and visible photons are described. Possible modifications of their design for some particular applications such as the readout of crystal scintillators. noble liquids, fibers and for large area Cherenkov detectors are discussed

  8. Features and performance of a large gas Cherenkov detector with threshold regulation

    Alberdi, J.; Alvarez-Taviel, J.; Asenjo, L.; Colino, N.; Diez-Hedo. F.; Duran, I.; Gonzalez, J.; Hernandez, J.J.; Ladron de Guevara, P.; Marquina, M.A.

    1988-01-15

    We present here the development, main features and calibration procedures for a new type of gas Cherenkov detector, based upon the ability to control its threshold by regulating the temperature of the gas used as radiator. We also include the performance of this detector in particle identification.

  9. An iterative method for the analysis of Cherenkov rings in the HERA-B RICH

    Staric, M.; Krizan, P.

    1999-01-01

    A new method is presented for the analysis of data recorded with a Ring Imaging Cherenkov (RICH) counter. The method, an iterative sorting of hits on the photon detector, is particularly useful for events where rings overlap considerably. The algorithm was tested on simulated data for the HERA-B experiment

  10. Construction and performance of two multicell Cherenkov counters used in FRAMM-NA1 spectrometer

    Amendolia, S.R.; Batignani, G.; Bedeschi, F.; Bertolucci, E.; Bettoni, D.; Bosisio, L.; Bottigli, U.; Bradaschia, C.; Budinich, M.; Dell'Orso, M.; Fidecaro, F.; Foa, L.; Focardi, E.; Giazotto, A.; Giorgi, M.A.; Liello, F.; Marrocchesi, P.S.; Mensa, A.; Menzione, A.; Ristori, L.; Rolandi, L.; Scribano, A.; Stanga, R.; Stefanini, A.; Tonelli, G.

    1983-01-01

    Two small dimension multicell Cherenkov counters have been built for FRAMM-NA1 multiparticle spectrometer to identify pions and kaons in the momentum range between 5 and 22 GeV/c. The performances achieved and the construction details are reported. (orig.)

  11. Discovery of high energy electrons in the radiation belt by devices with gas Cherenkov counters

    Kirillov-Ugryumov, V.G.; Galper, A.M.; Dmitrenko, V.V.

    1986-01-01

    A detailed study of the trapped electrons was undertaken with Bulgary-1300 satellite, the orbit altitude and the inclination being proportional900 km and 81 0 , respectively. The instrument axis in this case was perpendicular to the orbit plane. A scintillation-Cherenkov telescope, Electron, with parameters similar to that of Elena was used. (orig./HSI)

  12. Search for long-lived heavy charged particles using a ring imaging Cherenkov technique at LHCb

    Aaij, R.; Adeva, B.; Adinolfi, M.; Affolder, A.; Ajaltouni, Z.; Akar, S.; Albrecht, J.; Alessio, F.; Alexander, M.; Ali, S.; Alkhazov, G.; Cartelle, P. Alvarez; Alves, A. A., Jr.; Amato, S.; Amerio, S.; Amhis, Y.; Everse, LA; Anderlini, L.; Anderson, J.; Andreotti, M.; Andrews, J.E.; Appleby, R. B.; Gutierrez, O. Aquines; Archilli, F.; d'Argent, P.; Artamonov, A.; Artuso, M.; Aslanides, E.; Auriemma, G.; Baalouch, M.; Bachmann, S.; Back, J. J.; Badalov, A.; Baesso, C.; Baldini, W.; Barlow, R. J.; Barschel, C.; Barsuk, S.; Barter, W.; Batozskaya, V.; Battista, V.; Bay, A.; Beaucourt, L.; Beddow, J.; Bedeschi, F.; Bediaga, I.; Bel, L. J.; Belyaev, I.; Ben-Haim, E.; Bencivenni, G.; Benson, S.; Benton, J.; Berezhnoy, A.; Bernet, R.; Bertolin, A.; Bettler, M-O.; Van Beuzekom, Martin; Bien, A.; Bifani, S.; Bird, T.D.; Birnkraut, A.; Bizzeti, A.; Blake, T.; Blanc, F.; Blouw, J.; Blusk, S.; Bocci, V.; Bondar, A.; Bondar, N.; Bonivento, W.; Borghi, S.; Borgia, A.; Borsato, M.; Bowcock, T. J. V.; Bowen, E.; Bozzi, C.; Brett, D.; Britsch, M.; Britton, T.; Brodzicka, J.; Brook, N. H.; Bursche, A.; Buytaert, J.; Cadeddu, S.; Calabrese, R.; Calvi, M.; Calvo Gomez, M.; Campana, P.; Perez, D. H. Campora; Capriotti, L.; Carbone, A.; Carboni, G.; Cardinale, R.; Cardini, A.; Carniti, P.; Carson, L.; Carvalho Akiba, K.; Casanova Mohr, R.; Casse, G.; Cassina, L.; Garcia, L. Castillo; Cattaneo, M.; Cauet, Ch; Cavallero, G.; Cenci, R.; Charles, M.; Charpentier, Ph; Chefdeville, M.; Chen, S.; Cheung, S-F.; Chiapolini, N.; Chrzaszcz, M.; Vidal, X. Cid; Ciezarek, G.; Clarke, P. E. L.; Clemencic, M.; Cliff, H. V.; Closier, J.; Coco, V.; Cogan, J.; Cogneras, E.; Cogoni, V.; Cojocariu, L.; Collazuol, G.; Collins, P.; Comerma-Montells, A.; Contu, A.; Cook, A.; Coombes, M.; Coquereau, S.; Corti, G.; Corvo, M.; Counts, I.; Couturier, B.; Cowan, G. A.; Craik, D. C.; Crocombe, A.; CruzTorres, M.; Cunliffe, S.; Currie, C.R.; D'Ambrosio, C.; Dalseno, J.; David, P. N. Y.; Davis, A.; De Bruyn, K.; De Capua, S.; De Cian, M.; de Miranda, J. M.; Paula, L.E.; da-Silva, W.S.; De Simone, P.; Dean, C-T.; Decamp, D.; Deckenhoff, M.; Del Buono, L.; Deleage, N.; Derkach, D.; Deschamps, O.; Dettori, F.; Dey, B.; Di Canto, A.; Di Ruscio, F.; Dijkstra, H.; Donleavy, S.; Dordei, F.; Dorigo, M.; Dosil Suarez, A.; Dossett, D.; Dovbnya, A.; Dreimanis, K.; Dujany, G.; Dupertuis, F.; Durante, P.; Dzhelyadin, R.; Dziurda, A.; Dzyuba, A.; Easo, S.; Egede, U.; Egorychev, V.; Eidelman, S.; Eisenhardt, S.; Eitschberger, U.; Ekelhof, R.; Eklund, L.; ElRifai, I.; Elsasser, Ch.; Ely, S.; Esen, S.; Evans, H. M.; Evans, T. M.; Falabella, A.; Faerber, C.; Farinelli, C.; Farley, N.; Farry, S.; Fay, R.; Ferguson, D.; Fernandez Albor, V.; Ferrari, F.; Ferreira Rodrigues, F.; Ferro-Luzzi, M.; Filippov, S.; Fiore, M.; Fiorini, M.; Firlej, M.; Fitzpatrick, C.; Fiutowski, T.; Fol, P.; Fontana, Mark; Fontanelli, F.; Forty, R.; De Aguiar Francisco, O.; Frank, M.; Frei, C.; Frosini, M.; Fu, J.; Furfaro, E.; Torreira, A. Gallas; Galli, D.; Gallorini, S.; Gambetta, S.; Gandelman, M.; Gandini, P.; Gao, Y.; Garcia Pardinas, J.; Garofoli, J.; Tico, J. Garra; Garrido, L.; Gascon, D.; Carvalho-Gaspar, M.; Gauld, Rhorry; Gavardi, L.; Gazzoni, G.; Geraci, A.; Gerick, D.; Gersabeck, E.; Gersabeck, M.; Gershon, T. J.; Ghez, Ph; Gianelle, A.; Giani, S.; Gibson, V.; Giubega, L.; Gligorov, V. V.; Goebel, C.; Golubkov, D.; Golutvin, A.; Gomes, A.Q.; Gotti, C.; Gandara, M. Grabalosa; Diaz, R. Graciani; Cardoso, L. A. Granado; Grauges, E.; Graverini, E.; Graziani, G.; Grecu, A.; Greening, E.; Gregson, S.; Griffith, P.; Grillo, L.; Gruenberg, O.; Gui, B.; Gushchin, E.; Guz, Yu; Gys, T.; Hadjivasiliou, C.; Haefeli, G.; Haen, C.; Haines, S. C.; Hall, S.; Hamilton, B.; Hampson, T.; Han, X.; Hansmann-Menzemer, S.; Harnew, N.; Harnew, S. T.; Harrison, J.; He, J.; Head, T.; Heijne, V.; Hennessy, K.; Henrard, P.; Henry, L.; Hernando Morata, J. A.; van Herwijnen, E.; Hess, H.M.; Hicheur, A.; Hill, D.; Hoballah, M.; Hombach, C.; Hulsbergen, W.; Humair, T.; Hussain, N.; Hutchcroft, D. E.; Hynds, D.; Idzik, M.; Ilten, P.; Jacobsson, R.; Jaeger, A.; Jalocha, J.; Jans, E.; Jawahery, A.; Jing, F.; John, M.; Johnson, D.; Jones, C. R.; Joram, C.; Jost, B.; Jurik, N.; Kandybei, S.; Kanso, W.; Karacson, M.; Karbach, T. M.; Karodia, S.; Kelsey, M. H.; Kenyon, I. R.; Kenzie, M.; Ketel, T.; Khanji, B.; Khurewathanakul, C.; Klaver, S.M.; Klimaszewski, K.; Kochebina, O.; Kolpin, M.; Komarov, I.; Koopman, R. F.; Koppenburg, P.; Kravchuk, L.; Kreplin, K.; Kreps, M.; Krocker, G.; Krokovny, P.; Kruse, F.; Kucewicz, W.; Kucharczyk, M.; Kudryavtsev, V.; Kurek, K.; Kvaratskheliya, T.; La Thi, V. N.; Lacarrere, D.; Lafferty, G. D.; Lai, A.; Lambert, D.M.; Lambert, R. W.; Lanfranchi, G.; Langenbruch, C.; Langhans, B.; Latham, T. E.; Lazzeroni, C.; Le Gac, R.; van Leerdam, J.; Lees, J. P.; Lefevre, R.; Leflat, A.; Lefrancois, J.; Leroy, O.; Lesiak, T.; Leverington, B.; Li, Y.; Likhomanenko, T.; Liles, M.; Lindner, R.; Linn, S.C.; Lionetto, F.; Liu, B.; Lohn, S.; Longstaff, I.; Lopes, J. H.; Lucchesi, D.; Luo, H.; Lupato, A.; Luppi, E.; Lupton, O.; Machefert, F.; Machikhiliyan, I. V.; Maciuc, F.; Maev, O.; Malde, S.; Malinin, A.; Manca, G.; Mancinelli, G.; Manning, P.; Mapelli, A.; Maratas, J.; Marchand, J. F.; Marconi, U.; Marin Benito, C.; Marino, P.; Maerki, R.; Marks, J.; Martellotti, G.; Martinelli-Boneschi, F.; Santos, D. Martinez; Martinez-Vidal, F.; Martins Tostes, D.; Massafferri, A.; Matev, R.; Mathe, Z.; Matteuzzi, C.; Mauri, A.; Maurin, B.; Mazurov, A.; McCann, M.; McCarthy, J.; Mcnab, A.; McNulty, R.; McSkelly, B.; Meadows, B. T.; Meier, F.; Meissner, M.; Merk, M.; Milanes, D. A.; Minard, M. N.; Mitzel, D. S.; Molina Rodriguez, J.; Monteil, S.; Morandin, M.; Morawski, P.; Morda, A.; Morello, M. J.; Moron, J.; Morris, A. B.; Mountain, R.; Muheim, F.; Mueller, J.; Mueller, Karl; Mueller, V.; Mussini, M.; Muster, B.; Naik, P.; Nakada, T.; Nandakumar, R.; Nasteva, I.; Needham, M.; Neri, N.; Neubert, S.; Neufeld, N.; Neuner, M.; Nguyen, A. D.; Nguyen, T. D.; Nguyen-Mau, C.; Niess, V.; Niet, R.; Nikitin, N.; Nikodem, T.; Novoselov, A.; O'Hanlon, D. P.; Oblakowska-Mucha, A.; Obraztsov, V.; Ogilvy, S.; Okhrimenko, O.; Oldeman, R.; Onderwater, C. J. G.; Osorio Rodrigues, B.; Otalora Goicochea, J. M.; Otto, E.A.; Owen, R.P.; Oyanguren, A.; Palano, A.; Palombo, F.; Palutan, M.; Panman, J.; Papanestis, A.; Pappagallo, M.; Pappalardo, L.L.; Parkes, C.; Passaleva, G.; Patel, G. D.; Patel, M.; Patrignani, C.; Pearce, D.A.; Pellegrino, A.; Penso, G.; Altarelli, M. Pepe; Perazzini, S.; Perret, P.; Pescatore, L.; Petridis, K.; Petrolini, A.; Olloqui, E. Picatoste; Pietrzyk, B.; Pilar, T.; Pinci, D.; Pistone, A.; Playfer, S.; Plo Casasus, M.; Poikela, T.; Polci, F.; Poluektov, A.; Polyakov, I.; Polycarpo, E.; Popov, A.; Popov, D.; Popovici, B.; Potterat, C.; Price, M. E.; Price, J.D.; Prisciandaro, J.; Pritchard, C.A.; Prouve, C.; Pugatch, V.; Navarro, A. Puig; Punzi, G.; Qian, Y.W.; Quagliani, R.; Rachwal, B.; Rademacker, J. H.; Rakotomiaramanana, B.; Rama, M.; Rangel, M. S.; Raniuk, I.; Rauschmayr, N.; Raven, G.; Redi, F.; Reichert, S.; Reid, M.; dos Reis, A. C.; Ricciardi, S.; Richards, Jennifer S; Rihl, M.; Rinnert, K.; Rives Molina, V.; Robbe, P.; Rodrigues, A. B.; Rodrigues, L.E.T.; Perez, P. Rodriguez; Roiser, S.; Romanovsky, V.; Romero Vidal, A.; Rotondo, M.; Rouvinet, J.; Ruf, T.; Ruiz, van Hapere; Ruiz Valls, P.; Saborido Silva, J. J.; Sagidova, N.; Sail, P.; Saitta, B.; Salustino Guimaraes, V.; Sanchez Mayordomo, C.; Sanmartin Sedes, B.; Santacesaria, R.; Santamarina Rios, C.; Santovetti, E.; Sarti, A.; Satriano, C.; Satta, A.; Saunders, D. M.; Savrina, D.; Schiller, M.; Schindler, R. H.; Schlupp, M.; Schmelling, M.; Schmelzer, T.; Schmidt, B.; Schneider, O.; Schopper, A.; Schune, M. H.; Schwemmer, R.; Sciascia, B.; Sciubba, A.; Semennikov, A.; Sepp, I.; Serra, N.; Serrano, J.; Sestini, L.; Seyfert, P.; Shapkin, M.; Shapoval, I.; Shcheglov, Y.; Shears, T.; Shekhtman, L.; Shevchenko, V.; Shires, A.; Coutinho, R. Silva; Simi, G.; Sirendi, M.; Skidmore, N.; Skillicorn, I.; Skwarnicki, T.; Smith, E.; Smith, E.; Smith, J; Smith, M.; Snoek, H.; Sokoloff, M. D.; Soler, F. J. P.; Soomro, F.; de Souza, D.K.; Souza De Paula, B.; Spaan, B.; Spradlin, P.; Sridharan, S.; Stagni, F.; Stahl, M.; Stahl, S.; Steinkamp, O.; Stenyakin, O.; Sterpka, F.; Stevenson-Moore, P.; Stoica, S.; Stone, S.; Storaci, B.; Stracka, S.; Straticiuc, M.; Straumann, U.; Stroili, R.; Sun, L.; Sutcliffe, W.; Swientek, K.; Swientek, S.; Syropoulos, V.; Szczekowski, M.; Szczypka, P.; Szumlak, T.; T'Jampens, S.; Tekampe, T.; Teklishyn, M.; Tellarini, G.; Teubert, F.; Thomas, C.; Thomas, E.; van Tilburg, J.; Tisserand, V.; Tobin, M. N.; Todd, Jim; Tolk, S.; Tomassetti, L.; Tonelli, D.; Topp-Joergensen, S.; Torr, N.; Tournefier, E.; Tourneur, S.; Trabelsi, K.; Tran, N.T.M.T.; Tresch, M.; Trisovic, A.; Tsaregorodtsev, A.; Tsopelas, P.; Tuning, N.; Garcia, M. Ubeda; Ukleja, A.; Ustyuzhanin, A.; Uwer, U.; Vacca, C.; Vagnoni, V.; Valenti, G.; Vallier, A.; Gomez, R. Vazquez; Vazquez Regueiro, P.; Vazquez Sierra, C.; Vecchi, S.; Velthuis, M.J.; Veltri, M.; Veneziano, G.; Vesterinen, M.; Viaud, B.; Vieira, D.; Vieites Diaz, M.; Vilasis-Cardona, X.; Vollhardt, A.; Volyanskyy, D.; Voong, D.; Vorobyev, A.; Vorobyev, V.; Voss, C.; de Vries, J. A.; Waldi, R.; Wallace, C.; Wallace, R.; Walsh, John; Wandernoth, S.; Wang, J.; Ward, D. R.; Watson, N. K.; Websdale, D.; Weiden, A.; Whitehead, M.; Wiedner, D.; Wilkinson, G.; Wilkinson, M.; Williams, M.; Williams, M.P.; Williams, M.; Wilson, James F; Wimberley, J.; Wishahi, J.; Wislicki, W.; Witek, M.; Wormser, G.; Wotton, S. A.; Wright, S.J.; Wyllie, K.; Xie, Y.; Xu, Z.; Yang, Z.; Yuan, X.; Yushchenko, O.; Zangoli, M.; Zavertyaev, M.; Zhang, L.; Zhang, Y.; Zhelezov, A.; Zhokhov, A.; Zhong, L.

    2015-01-01

    A search is performed for heavy long-lived charged particles using 3.0 fb(-1) of proton-proton collisions collected at √s = 7 and 8 TeV with the LHCb detector. The search is mainly based on the response of the ring imaging Cherenkov detectors to distinguish the heavy, slow-moving particles from

  13. A long liquid Cherenkov counter for 300 to 460 MeV/c pion beams

    Zavrtanik, D.; Sever, F.; Plesko, M.; Music, M.; Kernel, G.

    1984-01-01

    A long liquid Cherenkov counter has been used to measure the proportion of muons in positive and negative pion beams in the momentum range between 300 and 460 MeV/c. A nine-parameter function fits all the spectra well. The data show a smooth dependence on incident momenta and agree with calculations of pion and muon pulse heights. (orig.)

  14. The Vavilov-Cherenkov radiation in a medium with a nonzero absorption coefficient

    Beshtoev, Kh.M.

    1997-01-01

    Distribution of the field around a charged relativistic particle in a medium is discussed. It is shown that the Vavilov-Cherenkov radiation exists in the case when the velocity of the charged particle is equal to the velocity of light in the medium. A simple approach is proposed to avoid singularity in the medium Electrodynamics

  15. Cherenkov-type diagnostics of fast electrons beams escaping from MCF facilities

    Jakubowski, L.; Malinowski, K.; Mirowski, R.; Rabinski, M.; Sadowski, M.J.; Zebrowski, J. [Institute for Nuclear Studies - IPJ, 05-400 Otwock-Swierk (Poland)

    2011-07-01

    The paper presents the feasibility study, the measuring system and the first experimental results of a new method developed for direct detection of high-energy (super-thermal, ripple-born and runaway) electrons generated in magnetic confinement fusion (MCF) facilities. The technique in question is based on registration of the Cherenkov radiation, emitted by energetic electrons, moving through a transparent medium (radiator) with a velocity higher than the velocity of light in this material. The main aim of our studies was to develop a diagnostic technique applicable for measurements of fast electron beams within MCF devices. The IPJ team proposed Cherenkov-type probes because of their high spatial- and temporal-resolutions. The most important results of applications of the presented Cherenkov-type diagnostics have proved that the one- and four-channel versions of the detecting head are useful for studies of the fast (ripple-born and runaway) electrons in different MCF experiments. Experience collected during the described studies allows to introduce some changes in the radiator configuration and to modify the Cherenkov probe design. This document is composed of a paper followed by a poster

  16. A Cherenkov radiator for FEL-synchronized VUV-pulses at a linac-based FEL

    Goloviznin, V. V.; Oepts, D.; van der Wiel, M. J.

    1997-01-01

    A possible way to carry out two-color IR+VUV pump-probe experiments at linac-based FELs is proposed. The idea is to supply an FEL facility with a gas cell filled with helium or hydrogen, so that the electron beam, upon passage through the undulator, could be used to generate ultraviolet Cherenkov

  17. A Cherenkov radiator for FEL-synchronized VUV-pulses at a linac-based FEL

    Goloviznin, V.V.; Oepts, W.; Wiel, van der M.J.

    1997-01-01

    A possible way to carry out two-color IR + VUV pump-probe experiments at linac-based FELs is proposed. The idea is to supply an FEL facility with a gas cell filled with helium or hydrogen, so that the electron beam, upon passage through the undulator, could be used to generate ultraviolet Cherenkov

  18. Effects of sintering atmosphere on the physical and mechanical properties of modified BOF slag glass

    Dai, Wen-bin; Li, Yu; Cang, Da-qiang; Zhou, Yuan-yuan; Fan, Yong

    2014-05-01

    This study proposes an efficient way to utilize all the chemical components of the basic oxygen furnace (BOF) slag to prepare high value-added glass-ceramics. A molten modified BOF slag was converted from the melting BOF slag by reducing it and separating out iron component in it, and the modified BOF slag was then quenched in water to form glasses with different basicities. The glasses were subsequently sintered in the temperature range of 600-1000°C in air or nitrogen atmosphere for 1 h. The effects of different atmospheres on the physical and mechanical properties of sintered samples were studied by using differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM) and by conducting experiment on evaluating the sintering shrinkage, water absorption and bulk density. It is found that the kinetics of the sintering process is significantly affected by sintering atmosphere. In particular, compared with sintering in air atmosphere, sintering in N2 atmosphere promotes the synergistic growth of pyroxene and melilite crystalline phases, which can contribute to better mechanical properties and denser microstructure.

  19. Effects of atmospheric correction and pansharpening on LULC classification accuracy using WorldView-2 imagery

    Chinsu Lin

    2015-05-01

    Full Text Available Changes of Land Use and Land Cover (LULC affect atmospheric, climatic, and biological spheres of the earth. Accurate LULC map offers detail information for resources management and intergovernmental cooperation to debate global warming and biodiversity reduction. This paper examined effects of pansharpening and atmospheric correction on LULC classification. Object-Based Support Vector Machine (OB-SVM and Pixel-Based Maximum Likelihood Classifier (PB-MLC were applied for LULC classification. Results showed that atmospheric correction is not necessary for LULC classification if it is conducted in the original multispectral image. Nevertheless, pansharpening plays much more important roles on the classification accuracy than the atmospheric correction. It can help to increase classification accuracy by 12% on average compared to the ones without pansharpening. PB-MLC and OB-SVM achieved similar classification rate. This study indicated that the LULC classification accuracy using PB-MLC and OB-SVM is 82% and 89% respectively. A combination of atmospheric correction, pansharpening, and OB-SVM could offer promising LULC maps from WorldView-2 multispectral and panchromatic images.

  20. Effectiveness of Emission Controls to Reduce the Atmospheric Concentrations of Mercury.

    Castro, Mark S; Sherwell, John

    2015-12-15

    Coal-fired power plants in the United States are required to reduce their emissions of mercury (Hg) into the atmosphere to lower the exposure of Hg to humans. The effectiveness of power-plant emission controls on the atmospheric concentrations of Hg in the United States is largely unknown because there are few long-term high-quality atmospheric Hg data sets. Here, we present the atmospheric concentrations of Hg and sulfur dioxide (SO2) measured from 2006 to 2015 at a relatively pristine location in western Maryland that is several (>50 km) kilometers downwind of power plants in Ohio, Pennsylvania, and West Virginia. Annual average atmospheric concentrations of gaseous oxidized mercury (GOM), SO2, fine particulate mercury (PBM2.5), and gaseous elemental mercury (GEM) declined by 75%, 75%, 43%, and 13%, respectively, and were strongly correlated with power-plant Hg emissions from the upwind states. These results provide compelling evidence that reductions in Hg emissions from power plants in the United States had their intended impact to reduce regional Hg pollution.

  1. Effects of atmospheric SO[sub 2] on Azolla and Anabaena symbiosis

    Hur, J.-S.; Wellburn, A.R. (Division of Biological Sciences, Institute of Environmental and Biological Sciences, Lancaster Univ., Lancaster (United Kingdom))

    1993-01-01

    The water fern Azolla pinnata R. Br. was fumigated for 1 week with either 25, 50 or 100 nl l[sup -1] SO[sub 2]. The symbiosis of Azolla with Anabaena azollae (spp.) was severely damaged by atmospheric SO[sub 2] even at the lowest concentration studied showing significant reductions in growth, reduction of C[sub 2]H[sub 2], NH[sub 3] assimilation, protein synthesis, and heterocyst development. These disturbances appear to be mainly responsible for the extreme sensitivity of this fern to atmospheric SO[sub 2]. Changes in violaxanthin/antheraxanthin and epoxylutein/lutein ratios also indicate that free radical products are induced by atmospheric SO[sub 2]. These results suggest that the Azolla-Anabeana symbiotic system is a very responsive and reliable lower plant model to study the detailed effects of total sulfur deposition upon the balances between various important plant metabolic processes.

  2. Effect of the atmospheric pressure nonequilibrium plasmas on the conformational changes of plasmid DNA

    Yan Xu; He Guangyuan; Shi Mengjun; Gao Xuan; Li Yin; Ma Fengyun; Yu Men; Wang Changdong; Wang Yuesheng; Yang Guangxiao; Zou Fei; Lu Xinpei; Xiong Qing; Xiong Zilan

    2009-01-01

    The cold atmospheric pressure plasma, which has been widely used for biomedical applications, may potentially affect the conformation of DNA. In this letter, an atmospheric pressure plasma plume is used to investigate its effects on the conformational changes of DNA of plasmid pAHC25. It is found that the plasma plume could cause plasmid DNA topology alteration, resulting in the percentage of the supercoiled plasmid DNA form decreased while that of the open circular and linearized form of plasmid DNA increased as detected by agrose gel electrophoresis. On the other hand, further investigation by using polymerase chain reaction method shows that the atmospheric pressure plasma jet treatments under proper conditions does not affect the genes of the plasmid DNA, which may have potential application in increasing the transformation frequency by genetic engineering.

  3. Spectroradiometric inspection of nuclear pollution in the atmosphere based on photochemical effects

    Chistyakova, Liliya K.; Kopytin, Yurii D.

    2005-07-01

    Results of theoretical and experimental investigations of remote monitoring methods based on secondary radioactivity effects including anomalous gaseous fields and their emissions in optical and microwave ranges are discussed. The feasibility of remote registration of secondary emission and absorption spectra from weakly ionized regions in the atmosphere above nuclear power engineering objects, dumps, and tailings dumps of nuclear wastes are examined. Based on the literature data on the excess concentrations of aerosol and gaseous components produced in radiation fields above their background levels, the diffusion parameters of radioactive emissions in the atmosphere are evaluated. The methods under consideration are shown to be promising for ecological monitoring of atmospheric radioactive pollution. High sensitivities of these methods enable pollutants to be detected at long distances. Simultaneous use of passive and active methods gives additional information on the parameters of radioactive pollution.

  4. Environmental assessment for the satellite power system concept development and evaluation program: atmospheric effects

    Rote, D.M.; Brubaker, K.L.; Lee, J.L.

    1980-11-01

    The US Department of Energy (DOE) has undertaken a preliminary, three-year program to investigate the impacts of the construction and operation of a satellite power system, of unprecedented scale. The Department of Energy's program, titled The Concept Development and Evaluation Program, focused its investigations on a Reference System description that calls for the use of either silicon (Si) or gallium aluminum-arsenide (GaAlAs) photovoltaic cells on 60 satellites to be constructed in GEO over a 30-yr period. Rectennas would be constructed on the ground to receive microwave energy from the satellites. Each satellite-rectenna pair is designed to produce 5 GW of power on an essentially continuous basis for use as a baseload power source for an electric power distribution system. The environmental assessment part of the program was divided into five interdependent task areas. The present document constitutes the final technical report on one of the five task areas, the Assessment of the Atmospheric Effects, and as such presents an in-depth summary of work performed during the assessment program. The issues associated with SPS activities in the troposphere are examined. These include tropospheric weather modification related to rectenna operations and rocket launches, and air quality impacts related to rocketlaunch ground clouds. Then progressing upward through the various levels of the atmosphere, the principal middle and upper atmospheric effects associated with rocket effluents are analyzed. Finally, all of the potential SPS atmospheric effects are summarized

  5. Simulated effect of calcification feedback on atmospheric CO2 and ocean acidification

    Zhang, Han; Cao, Long

    2016-01-01

    Ocean uptake of anthropogenic CO2 reduces pH and saturation state of calcium carbonate materials of seawater, which could reduce the calcification rate of some marine organisms, triggering a negative feedback on the growth of atmospheric CO2. We quantify the effect of this CO2-calcification feedback by conducting a series of Earth system model simulations that incorporate different parameterization schemes describing the dependence of calcification rate on saturation state of CaCO3. In a scenario with SRES A2 CO2 emission until 2100 and zero emission afterwards, by year 3500, in the simulation without CO2-calcification feedback, model projects an accumulated ocean CO2 uptake of 1462 PgC, atmospheric CO2 of 612 ppm, and surface pH of 7.9. Inclusion of CO2-calcification feedback increases ocean CO2 uptake by 9 to 285 PgC, reduces atmospheric CO2 by 4 to 70 ppm, and mitigates the reduction in surface pH by 0.003 to 0.06, depending on the form of parameterization scheme used. It is also found that the effect of CO2-calcification feedback on ocean carbon uptake is comparable and could be much larger than the effect from CO2-induced warming. Our results highlight the potentially important role CO2-calcification feedback plays in ocean carbon cycle and projections of future atmospheric CO2 concentrations. PMID:26838480

  6. Effect of Atmospheric Organics on Bioavailable Fe Lifetime in the Oceans

    Meskhidze, Nicholas; Hurley, David; Royalty, Taylor Michael; Johnson, Matthew S.

    2016-01-01

    The deposition of atmospheric aerosols is an important supply pathway of soluble iron (sol-Fe) to the global oceans influencing marine ecosystem processes and climate. Previous studies have shown that natural and anthropogenic acidic trace gases, when mixed with mineral dust, can lead to production of sol-Fe, leading to considerable increase in dust-Fe solubility. Recent studies have further highlighted the importance of atmospheric organic compounds/ligands in the production of sol-Fe during atmospheric transport and transformation of mineral aerosols. However, the actual scope of this aerosol sol-Fe for stimulating the primary productivity in the oceans is determined by both: the total atmospheric fluxes of sol-Fe and the lifetime of sol-Fe after its deposition to the ocean. In this study several atmospheric organic ligands were investigated for their effect on the lifetime of sol-Fe after mixing with seawater. Organic ligands were selected based on their abundance in the marine boundary layer and rainwater and their ability to form bidentate complexes with Fe. The results reveal that the tested organics had minor influence on Fe(II) lifetime in seawater. However, results also show that some organic acid considerably extended the lifetime of colloidal and aqueous Fe(III). Using these results we simulate aerosol sol-Fe lifetime in the ocean for different mineral dust deposition events in the presence and the absence of atmospheric organic ligands. The calculations suggest that when a large dust plume is assumed to contain Fe(II) alone, less than 15% of aerosol sol-Fe gets complexed with marine organic ligands. However, this fraction increases to over 90% when atmospheric Fe is allowed to bond with atmospheric organic acids prior to deposition to the oceans. Calculations also show that for the conditions when seawater organic ligands get titrated by Fe released from dust aerosol particles, retention of sol-Fe in the ocean depends on surface ocean mixing, i

  7. Investigation of the feasibility of an analytical method of accounting for the effects of atmospheric drag on satellite motion

    Bozeman, Robert E.

    1987-01-01

    An analytic technique for accounting for the joint effects of Earth oblateness and atmospheric drag on close-Earth satellites is investigated. The technique is analytic in the sense that explicit solutions to the Lagrange planetary equations are given; consequently, no numerical integrations are required in the solution process. The atmospheric density in the technique described is represented by a rotating spherical exponential model with superposed effects of the oblate atmosphere and the diurnal variations. A computer program implementing the process is discussed and sample output is compared with output from program NSEP (Numerical Satellite Ephemeris Program). NSEP uses a numerical integration technique to account for atmospheric drag effects.

  8. Signal intensity analysis and optimization for in vivo imaging of Cherenkov and excited luminescence

    LaRochelle, Ethan P. M.; Shell, Jennifer R.; Gunn, Jason R.; Davis, Scott C.; Pogue, Brian W.

    2018-04-01

    During external beam radiotherapy (EBRT), in vivo Cherenkov optical emissions can be used as a dosimetry tool or to excite luminescence, termed Cherenkov-excited luminescence (CEL) with microsecond-level time-gated cameras. The goal of this work was to develop a complete theoretical foundation for the detectable signal strength, in order to provide guidance on optimization of the limits of detection and how to optimize near real time imaging. The key parameters affecting photon production, propagation and detection were considered and experimental validation with both tissue phantoms and a murine model are shown. Both the theoretical analysis and experimental data indicate that the detection level is near a single photon-per-pixel for the detection geometry and frame rates commonly used, with the strongest factor being the signal decrease with the square of distance from tissue to camera. Experimental data demonstrates how the SNR improves with increasing integration time, but only up to the point where the dominance of camera read noise is overcome by stray photon noise that cannot be suppressed. For the current camera in a fixed geometry, the signal to background ratio limits the detection of light signals, and the observed in vivo Cherenkov emission is on the order of 100×  stronger than CEL signals. As a result, imaging signals from depths  <15 mm is reasonable for Cherenkov light, and depths  <3 mm is reasonable for CEL imaging. The current investigation modeled Cherenkov and CEL imaging of two oxygen sensing phosphorescent compounds, but the modularity of the code allows for easy comparison of different agents or alternative cameras, geometries or tissues.

  9. MO-A-BRD-06: In Vivo Cherenkov Video Imaging to Verify Whole Breast Irradiation Treatment

    Zhang, R; Glaser, A [Dartmouth College, Hanover, NH - New Hampshire (United States); Jarvis, L [Dartmouth-Hitchcock Medical Center, City Of Lebanon, New Hampshire (United States); Gladstone, D [Dartmouth-Hitchcock Medical Center, Hanover, City of Lebanon (Lebanon); Andreozzi, J; Hitchcock, W; Pogue, B [Dartmouth College, Hanover, NH (United States)

    2014-06-15

    Purpose: To show in vivo video imaging of Cherenkov emission (Cherenkoscopy) can be acquired in the clinical treatment room without affecting the normal process of external beam radiation therapy (EBRT). Applications of Cherenkoscopy, such as patient positioning, movement tracking, treatment monitoring and superficial dose estimation, were examined. Methods: In a phase 1 clinical trial, including 12 patients undergoing post-lumpectomy whole breast irradiation, Cherenkov emission was imaged with a time-gated ICCD camera synchronized to the radiation pulses, during 10 fractions of the treatment. Images from different treatment days were compared by calculating the 2-D correlations corresponding to the averaged image. An edge detection algorithm was utilized to highlight biological features, such as the blood vessels. Superficial dose deposited at the sampling depth were derived from the Eclipse treatment planning system (TPS) and compared with the Cherenkov images. Skin reactions were graded weekly according to the Common Toxicity Criteria and digital photographs were obtained for comparison. Results: Real time (fps = 4.8) imaging of Cherenkov emission was feasible and feasibility tests indicated that it could be improved to video rate (fps = 30) with system improvements. Dynamic field changes due to fast MLC motion were imaged in real time. The average 2-D correlation was about 0.99, suggesting the stability of this imaging technique and repeatability of patient positioning was outstanding. Edge enhanced images of blood vessels were observed, and could serve as unique biological markers for patient positioning and movement tracking (breathing). Small discrepancies exists between the Cherenkov images and the superficial dose predicted from the TPS but the former agreed better with actual skin reactions than did the latter. Conclusion: Real time Cherenkoscopy imaging during EBRT is a novel imaging tool that could be utilized for patient positioning, movement tracking

  10. The effect of synchrotron radiation on nicotiana tabacum-roots in oxygen atmosphere

    Avakyan, Ts.M.; Karagezyan, A.S.; Danielyan, A.Kh.

    1977-01-01

    The question of mutual action of sVnchrotron radiation (SR) and living objects and the influence of powerful radiations on the peculiarities of their functioning is a major problem in all fields where SR in applied, as well as in medicobiological aspects of space flights. The present report summarizes new experimental findings concerning the action of magnetic-inhibiting radiation on Nicotiana tabacum - roots in oxygen and helium atmosphere. Comparative studies have been carried out on ''oxygen effect'' of SR and X-ray radiation by traditional radiobiological equipment. The experiments have been performed on the 2 synchrotron channel of Yerevan Physical Institute Electron Accelerator. The circular current of the accelerator equals 1 ma at a maximal energy of electrons in the ring 4.5 GeV. Nonmonochromatized SR coming out from the beryllium window of the current conductor entered a special maylar chamber which was filled with oxygen and helium. 4-day old roots of tobacco seeds were radiated in the chamber. The radiation dose in X-ray, as well as in SR equals 500 rad/min. X-ray radiation was carried out with the use of a RUP-200/20 equipment at a regime of J=15 ma, E=183 kV. In applying 500, 00 and 2500 rad in oxygen atmosphere a marked maximum of chromosome aberration frequency was noted at 2500 rad. Comparative investigations have shown that in radiating the roots by X-ray in oxygen atmosphere, the percentage of chromosome aberrations constitutes 4.5 at 2500 rad, while in SR it equals 24. The ''oxygen effect'' has been demonstrated, and the protective effect in helium atmosphere. The question of dosimetry is discussed, and basing on modern views a working hypothesis is presented which explains the marked damaging effect of SR action in oxygen atmosphere

  11. Atmospheres and spectra of strongly magnetized neutron stars - II. The effect of vacuum polarization

    Ho, Wynn C. G.; Lai, Dong

    2003-01-01

    We study the effect of vacuum polarization on the atmosphere structure and radiation spectra of neutron stars with surface magnetic fields B= 1014-1015 G, as appropriate for magnetars. Vacuum polarization modifies the dielectric property of the medium and gives rise to a resonance feature in the opacity; this feature is narrow and occurs at a photon energy that depends on the plasma density. Vacuum polarization can also induce resonant conversion of photon modes via a mechanism analogous to the Mikheyev-Smirnov-Wolfenstein (MSW) mechanism for neutrino oscillation. We construct atmosphere models in radiative equilibrium with an effective temperature of a few ×106 K by solving the full radiative transfer equations for both polarization modes in a fully ionized hydrogen plasma. We discuss the subtleties in treating the vacuum polarization effects in the atmosphere models and present approximate solutions to the radiative transfer problem which bracket the true answer. We show from both analytic considerations and numerical calculations that vacuum polarization produces a broad depression in the X-ray flux at high energies (a few keV <~E<~ a few tens of keV) as compared to models without vacuum polarization; this arises from the density dependence of the vacuum resonance feature and the large density gradient present in the atmosphere. Thus the vacuum polarization effect softens the high-energy tail of the thermal spectrum, although the atmospheric emission is still harder than the blackbody spectrum because of the non-grey opacities. We also show that the depression of continuum flux strongly suppresses the equivalent width of the ion cyclotron line and therefore makes the line more difficult to observe.

  12. Effects of initiating anaerobic digestion of layer-hen poultry dung at sub-atmospheric pressure

    Chima C. Ngumah

    2013-12-01

    Full Text Available This study investigated the effects of initiating anaerobic digestion (AD of dry layer-hen poultry dung at the sub-atmospheric pressure of -30 cmHg on biodegradation, biogasification, and biomethanation. The setup was performed as a batch process at an average ambient temperature of 29±2 0C and a retention time of 15 days. Comparisons were made with two other experiments which were both begun at ambient atmospheric pressure; one was inoculated with digestate from a previous layer-hen dung AD, while the other was not inoculated. The bioreactors initiated at sub-atmospheric pressure, ambient atmospheric pressure without inoculum, and ambient atmospheric pressure with inoculum showed the following for biogas and biomethane yields respectively: 16.8 cm3 g-1 VS and 15.46 cm3 g 1 VS, 25.10 cm3 g-1 VS and 12.85 cm3 g-1 VS, 21.44 cm3 g-1 VS and 14.88 cm3 g 1 VS. In the same order, after AD, the following values were recorded for volatile solids and total viable counts (prokaryotes and fungi in the digestates: 40.33% and 23.22 x 106 cfu mL-1, 43.42% and 22.17 x 106 cfu mL-1, 41.11% and 13.3 x 106 cfu mL-1. The feedstock showed values of 83.93% and 3.98 x 106 cfu mL-1 for volatile solids and total viable count respectively. There was a slight difference in the volatile solids of the digestates of the three bioreactors after AD. The pH recorded for the feedstock slurry before AD was 7.9 at 30oC, while after AD, the digestates from all the three bioreactors showed the same pH of 5.9 at 29 0C. Statistical analysis using ANOVA showed no significant difference in biogas yields of the feedstock for the three bioreactors (A, B, C. ANOVA showed no significant difference for biomethane yields in the bioreactors initiated at sub-atmospheric pressure and for those initiated at ambient atmospheric pressure with inoculums. However, it showed significant difference in the bioreactor initiated at sub-atmospheric pressure and that initiated at ambient atmospheric

  13. Effect of atmospheric organic complexation on iron-bearing dust solubility

    Paris , R.; Desboeufs , K. V.

    2013-01-01

    International audience; Recent studies reported that the effect of organic complexation may be a potentially important process to be considered by models estimating atmospheric iron flux to the ocean. In this study, we investigated this process effect by a series of dissolution experiments on iron-bearing dust in the presence or the absence of various organic compounds (acetate, formate, oxalate, malonate, succinate, glutarate, glycolate, lactate, tartrate and humic acid as an analogue of hum...

  14. Observation of Cherenkov rings using a low-pressure parallel-plate chamber and a solid cesium-iodide photocathode

    Lockyer, N.S.; Millan, J.E.; Lu, C.; McDonald, K.T.; Lopez, A.

    1993-01-01

    We have observed Cherenkov rings from minimum-ionizing particles using a low-pressure, parallel-plate pad-chamber with a cesium-iodide solid photocathode. This detector is blind to minimum-ionizing particles, and sensitive to Cherenkov photons of wavelengths 170-210 nm. An average of 5 photoelectrons per Cherenkov ring were detected using a 2-cm-thick radiator of liquid C 6 F 14 . This paper reports on the chamber construction, photocathode preparation and testbeam results. (orig.)

  15. Stability and behavior of the outer array of small water Cherenkov detectors, outriggers, in the HAWC observatory

    Capistrán, T.; Torres, I.; Moreno, E.; collaboration, for the HAWC

    2017-01-01

    The High-Altitude Water Cherenkov (HAWC) Observatory is used for detecting TeV gamma rays. HAWC is operating at 4,100 meters above level sea on the slope of the Sierra Negra Volcano in the State of Puebla, Mexico, and consists of an array of 300 water Cherenkov detectors (WCDs) covering an area of 22,000 $m^2$. Each WCD is equipped with four photomultiplier tubes (PMTs) to detect Cherenkov emission in the water from secondary particles of extensive air-shower (EAS) that are produced in the in...

  16. Effect of Alloying Type and Lean Sintering Atmosphere on the Performance of PM Components

    Sundaram, M. Vattur; Shvab, R.; Millot, S.; Hryha, E.; Nyborg, L.

    2017-12-01

    In order to be cost effective and to meet increasing performance demands, powder metallurgy steel components require continuous improvement in terms of materials and process development. This study demonstrates the feasibility of manufacturing structural components using two different alloys systems, i.e. lean Cr-prealloyed and diffusion bonded water atomised powders with different processing conditions. The components were sintered at two different temperatures, i.e. 1120 and 1250 °C for 30 minutes in three different atmospheres: vacuum, N2- 10%H2 atmosphere as well as lean N2-5%H2-0.5%CO-(0.1-0.4)%CH4 sintering atmosphere. Components after sintering were further processed by either low pressure carburizing, sinterhardening or case hardening. All trials were performed in the industrial furnaces to simulate the actual production of the components. Microstructure, fractography, apparent and micro hardness analyses were performed close to the surface and in the middle of the sample to characterize the degree of sintering (temperature and atmosphere) and the effect of heat treatment. In all cases, components possess mostly martensitic microstructure with a few bainitic regions. The fracture surface shows well developed sinter necks. Inter- and trans-granular ductile and cleavage fracture modes are dominant and their fraction is determined by the alloy and processing route.

  17. Effect of atmosphere composition on the oxidation behavior of MCrAlY coatings

    Song, P.; Subanovic, M.; Toscano, J.; Naumenko, D.; Quadakkers, W.J. [Forschungszentrum Juelich GmbH, Institute for Energy Research (IEF-2), 52425 Juelich (Germany)

    2011-07-15

    In the present work the effect of atmosphere composition on the growth rate and adherence of the alumina scales was studied using free-standing MCrAlY-coatings and TBC-specimens with MCrAlY-bondcoats. The exposures comprised isothermal and cyclic exposures in laboratory air and Ar-H{sub 2}-H{sub 2}O at 1100 C. It is shown that minor Zr-addition to the bondcoat results in enhanced scale growth and internal oxidation. This effect is independent of the atmosphere composition. As a consequence of the rapid oxide formation the times to TBC failure on the Zr-containing bondcoat in both atmospheres were much shorter compared to those with Zr-free bondcoat. In the latter case the formation of a thin compact alumina TGO was slower in H{sub 2}/H{sub 2}O than in air resulting in significantly longer TBC-lifetime in the former atmosphere. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. The effect of the atmosphere and the role of pore filling on the sintering of aluminium

    Schaffer, G.B.; Hall, B.J.; Bonner, S.J.; Huo, S.H.; Sercombe, T.B.

    2006-01-01

    Alloys of Al-3.8Cu-1Mg-0.7Si, Al-4Cu-0.6Si-0.1Mg, Al-4Cu-1.2Mg and Al-1.9Mg-1.9Si were made using air atomised powder and conventional press-and-sinter powder metallurgy techniques. These were sintered under nitrogen with a controlled water content which varied from 3 to 630 ppm (a dew point of -69 to -25 deg. C), nitrogen-5%hydrogen, argon and argon-5%hydrogen, all at atmospheric pressure, or a vacuum of -2 torr. Dry nitrogen is the most efficacious atmosphere. Vacuum is more effective than argon while hydrogen, and thus water, is extremely prejudicial to sintered density. The minimum dew point for optimum sintering is -60 deg. C (10.5 ppm H 2 O). The key feature in the beneficial effect of nitrogen is the formation of aluminium nitride. This reduces the pressure in the pore spaces relative to the external atmosphere, which induces pore filling at grain sizes that are smaller than those required for sintering in inert atmospheres. It is suggested that pore filling is an important densification mechanism during the sintering of aluminium

  19. Effects of atmospheric and climate change at the timberline of the Central European Alps

    Wieser, Gerhard; Matyssek, Rainer; Luzian, Roland; Zwerger, Peter; Pindur, Peter; Oberhuber, Walter; Gruber, Andreas

    2011-01-01

    This review considers potential effects of atmospheric change and climate warming within the timberline ecotone of the Central European Alps. After focusing on the impacts of ozone (O3) and rising atmospheric CO2 concentration, effects of climate warming on the carbon and water balance of timberline trees and forests will be outlined towards conclusions about changes in tree growth and treeline dynamics. Presently, ambient ground-level O3 concentrations do not exert crucial stress on adult conifers at the timberline of the Central European Alps. In response to elevated atmospheric CO2 Larix decidua showed growth increase, whereas no such response was found in Pinus uncinata. Overall climate warming appears as the factor responsible for the observed growth stimulation of timberline trees. Increased seedling re-establishment in the Central European Alps however, resulted from invasion into potential habitats rather than upward migration due to climate change, although seedlings will only reach tree size upon successful coupling with the atmosphere and thus loosing the beneficial microclimate of low stature vegetation. In conclusion, future climate extremes are more likely than the gradual temperature increase to control treeline dynamics in the Central European Alps. PMID:21379395

  20. Effect of atmosphere on the fabrication of Si2N2O matrix composites

    Wei Li

    2018-03-01

    Full Text Available Si2N2O matrix composites were fabricated by solid/gas reaction in air or N2 atmosphere. The effects of atmosphere on the phase and microstructure of the composites were investigated. The reaction mechanism of Si2N2O system was discussed by analysing the variation of the Gibbs free energy with temperature. The effect of N2 and air on sintering of Si2N2O matrix composites was discussed in relation to observed kinetics and thermodynamic calculations. The results showed that gradient structure of Si2N2O matrix composites were obtained in N2 atmosphere. While high N2 concentration was useful for the formation of the pure β-Si3N4 ceramics, low N2 concentration was proposed to form the pure Si2N2O ceramics. However, in the air atmosphere, structure of the Si3N4/SiO2 composites is homogeneous without the gradient structure appearing. Its composition is a little different as the O2 concentration changes.

  1. Effective pollutant emission heights for atmospheric transport modelling based on real-world information

    Pregger, Thomas; Friedrich, Rainer

    2009-01-01

    Emission data needed as input for the operation of atmospheric models should not only be spatially and temporally resolved. Another important feature is the effective emission height which significantly influences modelled concentration values. Unfortunately this information, which is especially relevant for large point sources, is usually not available and simple assumptions are often used in atmospheric models. As a contribution to improve knowledge on emission heights this paper provides typical default values for the driving parameters stack height and flue gas temperature, velocity and flow rate for different industrial sources. The results were derived from an analysis of the probably most comprehensive database of real-world stack information existing in Europe based on German industrial data. A bottom-up calculation of effective emission heights applying equations used for Gaussian dispersion models shows significant differences depending on source and air pollutant and compared to approaches currently used for atmospheric transport modelling. - The comprehensive analysis of real-world stack data provides detailed default parameter values for improving vertical emission distribution in atmospheric modelling

  2. The effect of annealing atmosphere on the thermoluminescence of synthetic calcite

    Pagonis, Vasilis

    1998-01-01

    Samples of high purity calcite powder were annealed in air, nitrogen and carbon dioxide atmospheres in the temperature range 300-700 deg. C and in atmospheric pressure. The samples were subsequently irradiated and the effect of the annealing atmosphere and temperature on the thermoluminescence (TL) of the samples was studied. Our results show that both carbonate and oxygen ions play an important part in the TL of calcite annealed in this temperature range. The intensities of the TL signal in the nitrogen and carbon dioxide anneals rise continuously with the annealing temperature. For all annealing temperatures it was found that the carbon dioxide atmosphere caused an increase in the observed TL signal as compared with anneals in an inert nitrogen atmosphere, while the shape of the TL glow curves remained the same. This increase in the observed TL signal is explained via the surface adsorption of carbonate ions. The shape and location of the TL peaks suggest that samples annealed in air exhibit a different type of TL center than samples annealed in nitrogen and carbon dioxide atmospheres. A possible mechanism for the role of oxygen ions involves a surface adsorption process and a subsequent diffusion of oxygen ions in the bulk of the crystal. Annealing of the samples in air at temperatures T>600 deg. C causes a collapse of the TL signal, in agreement with previous studies of calcite powders. No such collapse of the TL signal is observed for the nitrogen and carbon dioxide anneals, suggesting that a different type of TL center and/or recombination center is involved in air anneals. Arrhenius plots for the air anneals yield an activation energy E=0.45±0.05 eV, while the carbon dioxide and nitrogen anneals yield a lower activation energy E=0.28±0.04 eV

  3. Effects of fuel and forest conservation on future levels of atmospheric carbon dioxide.

    Walker, J C; Kasting, J F

    1992-01-01

    We develop a numerical simulation of the global biogeochemical cycles of carbon that works over time scales extending from years to millions of years. The ocean is represented by warm and cold shallow water reservoirs, a thermocline reservoir, and deep Atlantic, Indian, and Pacific reservoirs. The atmosphere is characterized by a single carbon reservoir and the global biota by a single biomass reservoir. The simulation includes the rock cycle, distinguishing between shelf carbonate and pelagic carbonate precipitation, with distinct lysocline depths in the three deep ocean reservoirs. Dissolution of pelagic carbonates in response to decrease in lysocline depth is included. The simulation is tuned to reproduce the observed radiocarbon record resulting from atomic weapon testing. It is tuned also to reproduce the distribution of dissolved phosphate and total dissolved carbon between the ocean reservoirs as well as the carbon isotope ratios for both 13C and 14C in ocean and atmosphere. The simulation reproduces reasonably well the historical record of carbon dioxide partial pressure as well as the atmospheric isotope ratios for 13C and 14C over the last 200 yr as these have changed in response to fossil fuel burning and land use changes, principally forest clearance. The agreements between observation and calculation involves the assumption of a carbon dioxide fertilization effect in which the rate of production of biomass increases with increasing carbon dioxide partial pressure. At present the fertilization effect of increased carbon dioxide outweighs the effects of forest clearance, so the biota comprises an overall sink of atmospheric carbon dioxide sufficiently large to bring the budget approximately into balance. This simulation is used to examine the future evolution of carbon dioxide and its sensitivity to assumptions about the rate of fossil fuel burning and of forest clearance. Over times extending up to thousands of years, the results are insensitive to the

  4. Design concepts for the Cherenkov Telescope Array CTA: an advanced facility for ground-based high-energy gamma-ray astronomy

    Allekotte, I.; Arnaldi, H.; Asorey, H.; Gomez Berisso, M.; Sofo Haro, M.; Cillis, A.; Rovero, A.C.; Supanitsky, A.D.; Actis, M.; Antico, F.; Bottani, A.; Ochoa, I.; Ringegni, P.; Vallejo, G.; De La Vega, G.; Etchegoyen, A.; Videla, M.; Gonzalez, F.; Pallota, J.; Quel, E.; Ristori, P.; Romero, G.E.; Suarez, A.; Papyan, G.; Pogosyan, L.; Sahakian, V.; Bissaldi, E.; Egberts, K.; Reimer, A.; Reimer, O.; Shellard, R.C.; Santos, E.M.; De Gouveia Dal Pino, E.M.; Kowal, G.; De Souza, V.; Todero Peixoto, C.J.; Maneva, G.; Temnikov, P.; Vankov, H.; Golev, V.; Ovcharov, E.; Bonev, T.; Dimitrov, D.; Hrupec, D.; Nedbal, D.; Rob, L.; Sillanpaa, A.; Takalo, L.; Beckmann, V.; Benallou, M.; Boutonnet, C.; Corlier, M.; Courty, B.; Djannati-Atai, A.; Dufour, C.; Gabici, S.; Guglielmi, L.; Olivetto, C.; Pita, S.; Punch, M.; Selmane, S.; Terrier, R.; Yoffo, B.; Brun, P.; Carton, P.H.; Cazaux, S.; Corpace, O.; Delagnes, E.; Disset, G.; Durand, D.; Glicenstein, J.F.; Guilloux, F.; Kosack, K.; Medina, C.; Micolon, P.; Mirabel, F.; Moulin, E.; Peyaud, B.; Reymond, J.M.; Veyssiere, C.

    2011-01-01

    Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA. (authors)

  5. Research on the Effectively Building Patterns of Talent Incentive and Cultural Atmosphere for Modern Enterprise Management

    Zhang Penghui[1

    2016-01-01

    In this paper, we conduct research on the effectively building patterns of talent incentive and cultural atmosphere for modern enterprise management. Targeted incentive direction refers to the motivation, namely, to what kind of content to implement incentive. It has signifi cant effect on incentive effect. According to American psychologist Maslow’s hierarchy of needs theory, people’s behavior motives originated in fi ve kinds of need, namely: the physiological needs, security needs, belonging needs, respect for the needs and the self-actualization needs. People need not set in stone, which is a developing process from low to high, but the process is not a cascade of discontinuous jumping, but a continuous, the evolution of wave. Under this general basis, we propose the cultural atmosphere for modern enterprise management that is novel and innovative.

  6. Effects of vacuum and controlled atmosphere treatments on insect mortality and lettuce quality.

    Liu, Yong-Biao

    2003-08-01

    Laboratory studies were conducted to determine the effects of vacuum and controlled atmosphere on mortality of aphids, Nasonovia ribisnigri (Mosley) and Macrosiphum euphorbiae (Thomas), and leafminer, Liriomyza langei Frick, and on the visual quality of iceberg lettuce at three different temperatures. Vacuum at 50 mbar and controlled atmosphere with 6% CO2 were effective in controlling aphids and leafminer larvae. Complete control of N. ribisnigri and M. euphorbiae was achieved with vacuum treatments and 6% CO2 CA treatments at 5 degrees C in 4 d. Mortality was >96% when leafminer larvae were treated with vacuum and 6% CO2 CA treatments for 4 d. However, leafminer pupae were more tolerant to the treatments and highest mortality was close to 60% in 4 d with CO2 under vacuum. None of the treatments had negative effects on visual quality of iceberg lettuce. Results from this study are encouraging and warrant further and large-scale research.

  7. Real-time Cherenkov emission portal imaging during CyberKnife® radiotherapy

    Roussakis, Yiannis; Mason, Suzannah; Dehghani, Hamid; Zhang, Rongxiao; Heyes, Geoff; Webster, Gareth; Green, Stuart; Pogue, Brian

    2015-01-01

    The feasibility of real-time portal imaging during radiation therapy, through the Cherenkov emission (CE) effect is investigated via a medical linear accelerator (CyberKnife ® ) irradiating a partially-filled water tank with a 60 mm circular beam. A graticule of lead/plywood and a number of tissue equivalent materials were alternatively placed at the beam entrance face while the induced CE at the exit face was imaged using a gated electron-multiplying-intensified-charged-coupled device (emICCD) for both stationary and dynamic scenarios. This was replicated on an Elekta Synergy ® linear accelerator with portal images acquired using the iViewGT ™ system. Profiles across the acquired portal images were analysed to reveal the potential resolution and contrast limits of this novel CE based portal imaging technique and compared against the current standard. The CE resolution study revealed that using the lead/plywood graticule, separations down to 3.4  ±  0.5 mm can be resolved. A 28 mm thick tissue-equivalent rod with electron density of 1.69 relative to water demonstrated a CE contrast of 15% through air and 14% through water sections, as compared to a corresponding contrast of 19% and 12% using the iViewGT ™ system. For dynamic scenarios, video rate imaging with 30 frames per second was achieved. It is demonstrated that CE-based portal imaging is feasible to identify both stationary and dynamic objects within a CyberKnife ® radiotherapy treatment field. (note)

  8. Science with the ASTRI mini-array for the Cherenkov Telescope Array: blazars and fundamental physics

    Bonnoli, Giacomo; Tavecchio, Fabrizio; Giuliani, Andrea; Bigongiari, Ciro; Di Pierro, Federico; Stamerra, Antonio; Pareschi, Giovanni; Vercellone, Stefano; ASTRI Collaboration; CTA Consortium

    2016-05-01

    ASTRI (“Astronomia a Specchi con Tecnologia Replicante Italiana”) is a flagship project of the Italian Ministry of Research (MIUR), devoted to the realization, operation and scientific validation of an end-to-end prototype for the Small Size Telescope (SST) envisaged to become part of the Cherenkov Telescope Array (CTA). The ASTRI SST-2M telescope prototype is characterized by a dual mirror, Schwarzschild-Couder optical design and a compact camera based on silicon photo-multipliers. It will be sensitive to multi-TeV very high energy (VHE) gamma rays up to 100 TeV, with a PSF ~ 6’ and a wide (9.6°) unaberrated optical field of view. Right after validation of the design in single-dish observations at the Serra La Nave site (Sicily, Italy) during 2015, the ASTRI collaboration will be able to start deployment, at the final CTA southern site, of the ASTRI mini-array, proposed to constitute the very first CTA precursor. Counting 9 ASTRI SST-2M telescopes, the ASTRI mini-array will overtake current IACT systems in differential sensitivity above 5 TeV, thus allowing unprecedented observations of known and predicted bright TeV emitters in this band, including some extragalactic sources such as extreme high-peaked BL Lacs with hard spectra. We exploited the ASTRI scientific simulator ASTRIsim in order to understand the feasibility of observations tackling blazar and cosmic ray physics, including discrimination of hadronic and leptonic scenarios for the VHE emission from BL Lac relativistic jets and indirect measurements of the intergalactic magnetic field and of the extragalactic background light. We selected favorable targets, outlining observation modes, exposure times, multi-wavelength coverage needed and the results expected. Moreover, the perspectives for observation of effects due to the existence of axion-like particles or to Lorentz invariance violations have been investigated.

  9. Cherenkov imaging method for rapid optimization of clinical treatment geometry in total skin electron beam therapy

    Andreozzi, Jacqueline M., E-mail: Jacqueline.M.Andreozzi.th@dartmouth.edu, E-mail: Lesley.A.Jarvis@hitchcock.org; Glaser, Adam K. [Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755 (United States); Zhang, Rongxiao [Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755 (United States); Gladstone, David J.; Williams, Benjamin B.; Jarvis, Lesley A., E-mail: Jacqueline.M.Andreozzi.th@dartmouth.edu, E-mail: Lesley.A.Jarvis@hitchcock.org [Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03766 (United States); Pogue, Brian W. [Thayer School of Engineering and Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755 (United States)

    2016-02-15

    Purpose: A method was developed utilizing Cherenkov imaging for rapid and thorough determination of the two gantry angles that produce the most uniform treatment plane during dual-field total skin electron beam therapy (TSET). Methods: Cherenkov imaging was implemented to gather 2D measurements of relative surface dose from 6 MeV electron beams on a white polyethylene sheet. An intensified charge-coupled device camera time-gated to the Linac was used for Cherenkov emission imaging at sixty-two different gantry angles (1° increments, from 239.5° to 300.5°). Following a modified Stanford TSET technique, which uses two fields per patient position for full body coverage, composite images were created as the sum of two beam images on the sheet; each angle pair was evaluated for minimum variation across the patient region of interest. Cherenkov versus dose correlation was verified with ionization chamber measurements. The process was repeated at source to surface distance (SSD) = 441, 370.5, and 300 cm to determine optimal angle spread for varying room geometries. In addition, three patients receiving TSET using a modified Stanford six-dual field technique with 6 MeV electron beams at SSD = 441 cm were imaged during treatment. Results: As in previous studies, Cherenkov intensity was shown to directly correlate with dose for homogenous flat phantoms (R{sup 2} = 0.93), making Cherenkov imaging an appropriate candidate to assess and optimize TSET setup geometry. This method provided dense 2D images allowing 1891 possible treatment geometries to be comprehensively analyzed from one data set of 62 single images. Gantry angles historically used for TSET at their institution were 255.5° and 284.5° at SSD = 441 cm; however, the angles optimized for maximum homogeneity were found to be 252.5° and 287.5° (+6° increase in angle spread). Ionization chamber measurements confirmed improvement in dose homogeneity across the treatment field from a range of 24.4% at the initial

  10. Effects of sintering atmosphere and initial particle size on sintering of gadolinia-doped ceria

    Batista, Rafael Morgado

    2014-01-01

    The effects of the sintering atmosphere and initial particle size on the sintering of ceria containing 10 mol% gadolinia (GdO 1.5 ) were systematically investigated. The main physical parameter was the specific surface area of the initial powders. Nanometric powders with three different specific surface areas were utilized, 210 m 2 /g, 36,2 m 2 /g e 7,4 m 2 /g. The influence on the densification, and micro structural evolution were evaluated. The starting sintering temperature was verified to decrease with increasing on the specific surface area of raw powders. The densification was accelerated for the materials with smaller particle size. Sintering paths for crystallite growth were obtained. Master sintering curves for gadolinium-doped ceria were constructed for all initial powders. A computational program was developed for this purpose. The results for apparent activation energy showed noticeable dependence with specific surface area. In this work, the apparent activation energy for densification increased with the initial particle size of powders. The evolution of the particle size distributions on non isothermal sintering was investigated by WPPM method. It was verified that the grain growth controlling mechanism on gadolinia doped ceria is the pore drag for initial stage and beginning of intermediate stage. The effects of the sintering atmosphere on the stoichiometry deviation of ceria, densification, microstructure evolution, and electrical conductivity were analyzed. Inert, oxidizing, and reducing atmospheres were utilized on this work. Deviations on ceria stoichiometry were verified on the bulk materials. The deviation verified was dependent of the specific surface area and sintering atmosphere. Higher reduction potential atmospheres increase Ce 3+ bulk concentration after sintering. Accelerated grain growth and lower electrical conductivities were verified when reduction reactions are significantly present on sintering. (author)

  11. Atmospheric Electricity

    Aplin, Karen; Fischer, Georg

    2018-02-01

    Electricity occurs in atmospheres across the Solar System planets and beyond, spanning spectacular lightning displays in clouds of water or dust, to more subtle effects of charge and electric fields. On Earth, lightning is likely to have existed for a long time, based on evidence from fossilized lightning strikes in ancient rocks, but observations of planetary lightning are necessarily much more recent. The generation and observations of lightning and other atmospheric electrical processes, both from within-atmosphere measurements, and spacecraft remote sensing, can be readily studied using a comparative planetology approach, with Earth as a model. All atmospheres contain charged molecules, electrons, and/or molecular clusters created by ionization from cosmic rays and other processes, which may affect an atmosphere's energy balance both through aerosol and cloud formation, and direct absorption of radiation. Several planets are anticipated to host a "global electric circuit" by analogy with the circuit occurring on Earth, where thunderstorms drive current of ions or electrons through weakly conductive parts of the atmosphere. This current flow may further modulate an atmosphere's radiative properties through cloud and aerosol effects. Lightning could potentially have implications for life through its effects on atmospheric chemistry and particle transport. It has been observed on many of the Solar System planets (Earth, Jupiter, Saturn, Uranus, and Neptune) and it may also be present on Venus and Mars. On Earth, Jupiter, and Saturn, lightning is thought to be generated in deep water and ice clouds, but discharges can be generated in dust, as for terrestrial volcanic lightning, and on Mars. Other, less well-understood mechanisms causing discharges in non-water clouds also seem likely. The discovery of thousands of exoplanets has recently led to a range of further exotic possibilities for atmospheric electricity, though lightning detection beyond our Solar System

  12. Realisation and tests of a compressed gas Cherenkov counter. Study of the pollution of a beam (1961); Realisation et essais d'un compteur cherenkov a gaz comprime etude de la pollution d'un faisceau (1961)

    Duboc, J; Banaigs, J; Detoeuf, J F [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    The realisation of a compressed as Cherenkov counter permits the study of the pollution of a beam of {pi} mesons with momentum varying from 220 to 11000 MeV/c. (authors) [French] La realisation d'un compteur Cherenkov a gaz sous pression permet l'etude de la pollution d'un faisceau de mesons {pi} d'impulsions comprise entre 220 et 1100 MeV/c. (auteurs)

  13. Global Effects of Superparameterization on Hydrothermal Land-Atmosphere Coupling on Multiple Timescales

    Qin, Hongchen; Pritchard, Michael S.; Kooperman, Gabriel J.; Parishani, Hossein

    2018-02-01

    Many conventional General Circulation Models (GCMs) in the Global Land-Atmosphere Coupling Experiment (GLACE) tend to produce what is now recognized as overly strong land-atmosphere (L-A) coupling. We investigate the effects of cloud Superparameterization (SP) on L-A coupling on timescales beyond diurnal where it has been recently shown to have a favorable muting effect hydrologically. Using the Community Atmosphere Model v3.5 (CAM3.5) and its Superparameterized counterpart SPCAM3.5, we conducted soil moisture interference experiments following the GLACE and Atmospheric Model Intercomparison Project (AMIP) protocols. The results show that, on weekly-to-subseasonal timescales, SP also mutes hydrologic L-A coupling. This is detectable globally, and happens through the evapotranspiration-precipitation segment. But on seasonal timescales, SP does not exhibit detectable effects on hydrologic L-A coupling. Two robust regional effects of SP on thermal L-A coupling have also been explored. Over the Arabian Peninsula, SP reduces thermal L-A coupling through a straightforward control by mean rainfall reduction. More counterintuitively, over the Southwestern US and Northern Mexico, SP enhances the thermal L-A coupling in a way that is independent of rainfall and soil moisture. This signal is associated with a systematic and previously unrecognized effect of SP that produces an amplified Bowen ratio, and is detectable in multiple SP model versions and experiment designs. In addition to amplifying the present-day Bowen ratio, SP is found to amplify the climate sensitivity of Bowen ratio as well, which likely plays a role in influencing climate change predictions at the L-A interface.

  14. Effect of feed-gas humidity on nitrogen atmospheric-pressure plasma jet for biological applications.

    Stephan, Karl D; McLean, Robert J C; DeLeon, Gian; Melnikov, Vadim

    2016-11-14

    We investigate the effect of feed-gas humidity on the oxidative properties of an atmospheric-pressure plasma jet using nitrogen gas. Plasma jets operating at atmospheric pressure are finding uses in medical and biological settings for sterilization and other applications involving oxidative stress applied to organisms. Most jets use noble gases, but some researchers use less expensive nitrogen gas. The feed-gas water content (humidity) has been found to influence the performance of noble-gas plasma jets, but has not yet been systematically investigated for jets using nitrogen gas. Low-humidity and high-humidity feed gases were used in a nitrogen plasma jet, and the oxidation effect of the jet was measured quantitatively using a chemical dosimeter known as FBX (ferrous sulfate-benzoic acid-xylenol orange). The plasma jet using high humidity was found to have about ten times the oxidation effect of the low-humidity jet, as measured by comparison with the addition of measured amounts of hydrogen peroxide to the FBX dosimeter. Atmospheric-pressure plasma jets using nitrogen as a feed gas have a greater oxidizing effect with a high level of humidity added to the feed gas.

  15. Challenges in tracing the fate and effects of atmospheric polycyclic aromatic hydrocarbon deposition in vascular plants.

    Desalme, Dorine; Binet, Philippe; Chiapusio, Geneviève

    2013-05-07

    Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous organic pollutants that raise environmental concerns because of their toxicity. Their accumulation in vascular plants conditions harmful consequences to human health because of their position in the food chain. Consequently, understanding how atmospheric PAHs are taken up in plant tissues is crucial for risk assessment. In this review we synthesize current knowledge about PAH atmospheric deposition, accumulation in both gymnosperms and angiosperms, mechanisms of transfer, and ecological and physiological effects. PAHs emitted in the atmosphere partition between gas and particulate phases and undergo atmospheric deposition on shoots and soil. Most PAH concentration data from vascular plant leaves suggest that contamination occurs by both direct (air-leaf) and indirect (air-soil-root) pathways. Experimental studies demonstrate that PAHs affect plant growth, interfering with plant carbon allocation and root symbioses. Photosynthesis remains the most studied physiological process affected by PAHs. Among scientific challenges, identifying specific physiological transfer mechanisms and improving the understanding of plant-symbiont interactions in relation to PAH pollution remain pivotal for both fundamental and applied environmental sciences.

  16. Fate and potential environmental effects of methylenediphenyl diisocyanate and toluene diisocyanate released into the atmosphere.

    Tury, Bernard; Pemberton, Denis; Bailey, Robert E

    2003-01-01

    Information from a variety of sources has been collected and summarized to facilitate an overview of the atmospheric fate and potential environmental effects of emissions of methylenediphenyl diisocyanate (MDI) or toluene diisocyanate (TDI) to the atmosphere. Atmospheric emissions of both MDI and TDI are low, both in terms of concentration and mass, because of their low volatility and the need for careful control over all aspects of their lifecycle from manufacture through disposal. Typical emission losses for TDI are 25 g/t of TDI used in slabstock foam production. MDI emission losses are lower, often less than 1 g/t of MDI used. Dispersion modeling predicts that concentrations at the fenceline or beyond are very low for typical releases. Laboratory studies show that TDI (and by analogy MDI) does not react with water in the gas phase at a significant rate. The primary degradation reaction of these aromatic diisocyanates in the atmosphere is expected to be oxidation by OH radicals with an estimated half-life of one day. Laboratory studies also show that this reaction is not expected to result in increased ground-level ozone accumulation.

  17. Atmospheric effects of nuclar war aerosols in general circulation model simulations: Influence of smoke optical properties

    Thompson, S.L.; Ramaswamy, V.; Covey, C.

    1987-01-01

    A global atmospheric general circulation model (GCM) is modified to include radiative transfer parameterizations for the absorption and scattering of solar radiation and the absorption of thermal infrared (IR) radiation by smoke aerosols. The solar scattering modifications include a parameterization for diagnosing smoke optical properties as a function of the time- and space-dependent smoke particle radii. The aerosol IR modifications allow for both the ''grey'' absorber approximation and a broadband approximation that resolves the aerosol absorption in four spectral intervals. We examine the sensitivity of some GCM-simulated atmospheric and climatic effects to the optical properties and radiative transfer parameterizations used in studies of massive injections of smoke. Specifically, we test the model response to solar scattering versus nonscattering smoke, variations in prescribed smoke single scattering albedo and IR specific absorption, and interactive versus fixed smoke optical properties. Hypothetical nuclear war created smoke scenarios assume the July injection of 60 or 180 Tg of smoke over portions of the mid-latitude land areas of the northern hemisphere. Atmospheric transport and scavenging of the smoke are included. Nonscattering smoke cases produce roughly 40 Wm/sup -2/ more Earth-atmosphere solar irradiance absorption over the northern hemisphere, when compared to scattering smoke cases having equivalent specific absorption efficiencies. Varying the elemental carbon content of smoke over a plausible range produces a 4 0 --6 0 C change in average mid-latitude land surface temperature, and a variation of about 0.1 in zonally averaged planetary albedo in the northern hemisphere

  18. Synergistic effects of atmospheric pressure plasma-emitted components on DNA oligomers: a Raman spectroscopic study.

    Edengeiser, Eugen; Lackmann, Jan-Wilm; Bründermann, Erik; Schneider, Simon; Benedikt, Jan; Bandow, Julia E; Havenith, Martina

    2015-11-01

    Cold atmospheric-pressure plasmas have become of increasing importance in sterilization processes especially with the growing prevalence of multi-resistant bacteria. Albeit the potential for technological application is obvious, much less is known about the molecular mechanisms underlying bacterial inactivation. X-jet technology separates plasma-generated reactive particles and photons, thus allowing the investigation of their individual and joint effects on DNA. Raman spectroscopy shows that particles and photons cause different modifications in DNA single and double strands. The treatment with the combination of particles and photons does not only result in cumulative, but in synergistic effects. Profilometry confirms that etching is a minor contributor to the observed DNA damage in vitro. Schematics of DNA oligomer treatment with cold atmospheric-pressure plasma. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Irradiation and modified atmosphere packaging effects on residual nitrite, ascorbic acid, nitrosomyoglobin, and color in sausage.

    Ahn, Hyun-Joo; Jo, Cheorun; Lee, Ju-Woon; Kim, Jae-Hyun; Kim, Kee-Hyuk; Byun, Myung-Woo

    2003-02-26

    The present study was undertaken to evaluate the irradiation and modified atmosphere packaging effects on emulsion-type cooked pork sausage during storage for 4 weeks. CO(2) (100%), N(2) (100%), or 25% CO(2)/75% N(2) packaged sausage were irradiated at 0, 5, and 10 kGy, and residual nitrite, residual ascorbic acid, nitrosomyoglobin (NO-Mb), color values, and their correlation were observed. Irradiation significantly reduced the residual nitrite content and caused partial reduction of NO-Mb during storage. No difference was observed in ascorbic acid content by irradiation. Irradiation decreased the Hunter color a value of sausage. CO(2) or CO(2)/N(2) packaging were more effective for reducing residual nitrite and inhibiting the loss of the red color of sausage compared to N(2) packaging. Results indicated that the proper combination of irradiation and modified atmosphere packaging could reduce the residual nitrite in sausage with minimization of color change.

  20. On the Effects of Atmospheric Particles Contamination and Humidity on Tin Corrosion

    D’Angelo, L.; Verdingovas, V.; Ferrero, L.

    2017-01-01

    The effects of hygroscopic atmospheric particles are investigated in relation to the corrosion of tin. Surface insulation resistance test boards were directly contaminated both with ambient particles sampled in the field at Milan, Italy, and with pure saline particles generated in the laboratory....... An innovative particle deposition device was used to uniformly coat circular spots on to the test board surfaces. Deliquescence and crystallization of the water-soluble compounds were detected by observing the impedance response to varying relative humidity (RH) conditions with a gradual and continuous ramps....... The effects of the adsorption/desorption kinetics and of the temperature on the deliquescence and crystallization RH values were also investigated. Leakage current measurements at 5-V dc highlighted the ability of atmospheric particles to promote corrosion and electrochemical migration at RH levels far below...