WorldWideScience

Sample records for radiation environment model

  1. Galactic cosmic radiation environment models

    Science.gov (United States)

    Badhwar, G. D.; O'Neill, P. M.; Troung, A. G.

    2001-02-01

    Models of the radiation environment in free space and in near earth orbits are required to estimate the radiation dose to the astronauts for Mars, Space Shuttle, and the International Space Station missions, and to estimate the rate of single event upsets and latch-ups in electronic devices. Accurate knowledge of the environment is critical for the design of optimal shielding during both the cruise phase and for a habitat on Mars or the Moon. Measurements of the energy spectra of galactic cosmic rays (GCR) have been made for nearly four decades. In the last decade, models have been constructed that can predict the energy spectra of any GCR nuclei to an accuracy of better than 25%. Fresh and more accurate measurements have been made in the last year. These measurements can lead to more accurate models. Improvements in these models can be made in determining the local interstellar spectra and in predicting the level of solar modulation. It is the coupling of the two that defines a GCR model. This paper reviews of two of the more widely used models, and a comparison of their predictions with new proton and helium data from the Alpha Magnetic Spectrometer (AMS), and spectra of beryllium to iron in the ~40 to 500 MeV/n acquired by the Advanced Composition Explorer (ACE) during the 1997-98 solar minimum. Regressions equations relating the IMP-8 helium count rate to the solar modulation deceleration parameter calculated using the Climax neutron monitor rate have been developed and may lead to improvements in the predictive capacity of the models. .

  2. The dynamic radiation environment assimilation model (DREAM)

    Energy Technology Data Exchange (ETDEWEB)

    Reeves, Geoffrey D [Los Alamos National Laboratory; Koller, Josef [Los Alamos National Laboratory; Tokar, Robert L [Los Alamos National Laboratory; Chen, Yue [Los Alamos National Laboratory; Henderson, Michael G [Los Alamos National Laboratory; Friedel, Reiner H [Los Alamos National Laboratory

    2010-01-01

    The Dynamic Radiation Environment Assimilation Model (DREAM) is a 3-year effort sponsored by the US Department of Energy to provide global, retrospective, or real-time specification of the natural and potential nuclear radiation environments. The DREAM model uses Kalman filtering techniques that combine the strengths of new physical models of the radiation belts with electron observations from long-term satellite systems such as GPS and geosynchronous systems. DREAM includes a physics model for the production and long-term evolution of artificial radiation belts from high altitude nuclear explosions. DREAM has been validated against satellites in arbitrary orbits and consistently produces more accurate results than existing models. Tools for user-specific applications and graphical displays are in beta testing and a real-time version of DREAM has been in continuous operation since November 2009.

  3. Geant4 models for space radiation environment.

    Science.gov (United States)

    Ivantchenko, Anton; Nieminen, Petteri; Incerti, Sebastien; Santin, Giovanni; Ivantchenko, Vladimir; Grichine, Vladimir; Allison, John

    The space radiation environment includes wide varieties of particles from electrons to heavy ions. In order to correctly predict the dose received by astronauts and devices the simulation models must have good applicability and produce accurate results from 10 MeV/u up to 10 GeV/u, where the most radioactive hazardous particles are present in the spectra. Appropriate models should also provide a good description of electromagnetic interactions down to very low energies (10 eV/u - 10 MeV/u) for understanding the damage mechanisms due to long-term low doses. Predictions of biological dose during long interplanetary journeys also need models for hadronic interactions of energetic heavy ions extending higher energies (10 GeV/u - 100 GeV/u, but possibly up to 1 TeV/u). Geant4 is a powerful toolkit, which in some areas well surpasses the needs from space radiation studies, while in other areas is being developed and/or validated to properly cover the modelling requirements outlined above. Our activities in ESA projects deal with the research and development of both Geant4 hadronic and electromagnetic physics. Recently the scope of verification tests and benchmarks has been extended. Hadronic tests and benchmarks run proton, pion, and ion interactions with matter at various energies. In the Geant4 hadronic sub-libraries, the most accurate cross sections have been identified and selected as a default for all particle types relevant to space applications. Significant developments were carried out for ion/ion interaction models. These now allow one to perform Geant4 simulations for all particle types and energies relevant to space applications. For the validation of ion models the hadronic testing suite for ion interactions was significantly extended. In this work the results of benchmarking versus data in a wide energy range for projectile protons and ions will be shown and discussed. Here we show results of the tests runs and their precision. Recommendations for Geant4

  4. Radiation Belt Environment Model: Application to Space Weather and Beyond

    Science.gov (United States)

    Fok, Mei-Ching H.

    2011-01-01

    Understanding the dynamics and variability of the radiation belts are of great scientific and space weather significance. A physics-based Radiation Belt Environment (RBE) model has been developed to simulate and predict the radiation particle intensities. The RBE model considers the influences from the solar wind, ring current and plasmasphere. It takes into account the particle drift in realistic, time-varying magnetic and electric field, and includes diffusive effects of wave-particle interactions with various wave modes in the magnetosphere. The RBE model has been used to perform event studies and real-time prediction of energetic electron fluxes. In this talk, we will describe the RBE model equation, inputs and capabilities. Recent advancement in space weather application and artificial radiation belt study will be discussed as well.

  5. Recent Developments in the Radiation Belt Environment Model

    Science.gov (United States)

    Fok, M.-C.; Glocer, A.; Zheng, Q.; Horne, R. B.; Meredith, N. P.; Albert, J. M.; Nagai, T.

    2010-01-01

    The fluxes of energetic particles in the radiation belts are found to be strongly controlled by the solar wind conditions. In order to understand and predict the radiation particle intensities, we have developed a physics-based Radiation Belt Environment (RBE) model that considers the influences from the solar wind, ring current and plasmasphere. Recently, an improved calculation of wave-particle interactions has been incorporated. In particular, the model now includes cross diffusion in energy and pitch-angle. We find that the exclusion of cross diffusion could cause significant overestimation of electron flux enhancement during storm recovery. The RBE model is also connected to MHD fields so that the response of the radiation belts to fast variations in the global magnetosphere can be studied.Weare able to reproduce the rapid flux increase during a substorm dipolarization on 4 September 2008. The timing is much shorter than the time scale of wave associated acceleration.

  6. A space radiation shielding model of the Martian radiation environment experiment (MARIE)

    Science.gov (United States)

    Atwell, W.; Saganti, P.; Cucinotta, F. A.; Zeitlin, C. J.

    2004-01-01

    The 2001 Mars Odyssey spacecraft was launched towards Mars on April 7, 2001. Onboard the spacecraft is the Martian radiation environment experiment (MARIE), which is designed to measure the background radiation environment due to galactic cosmic rays (GCR) and solar protons in the 20-500 MeV/n energy range. We present an approach for developing a space radiation-shielding model of the spacecraft that includes the MARIE instrument in the current mapping phase orientation. A discussion is presented describing the development and methodology used to construct the shielding model. For a given GCR model environment, using the current MARIE shielding model and the high-energy particle transport codes, dose rate values are compared with MARIE measurements during the early mapping phase in Mars orbit. The results show good agreement between the model calculations and the MARIE measurements as presented for the March 2002 dataset. c2003 COSPAR. Published by Elsevier Ltd. All rights reserved.

  7. Modeling of the Martian Environment for Radiation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    De Angelis, G. [Istituto Superiore di Sanit, Rome, I-00161 (Italy); Badavi, F.F. [Christopher Newport University, Newport News, VA 23606 (United States); Blattnig, S.R.; Clowdsley, M.S. [NASA Langley Research Center, Hampton, VA 23681 (United States); Nealy, J.E. [Old Dominion University, Norfolk, VA 23508 (United States); Qualls, G.D.; Singleterry, R.C.; Tripathi, R.K.; Wilson, J.W. [NASA Langley Research Center, Hampton, VA 23681 (United States)

    2007-04-15

    Results for the radiation environment to be found on the planet Mars due to Galactic Cosmic Rays (GCR) and Solar Particle Events (SPE) has been obtained. Primary particle environments computed for Martian conditions are transported within the Mars atmosphere, modeled in a time-dependent way in terms of density, pressure, and temperature vs. altitude, down to the surface, with topography and backscattering patterns taken into account. The atmospheric chemical and isotopic composition has been modeled over results from the in-situ Viking Lander measurements for both major and minor components. The surface topography has been determined by using a model based on the data provided by the Mars Orbiter Laser Altimeter (MOLA) instrument on board the Mars Global Surveyor (MGS) spacecraft. The surface itself has been modeled in both the dry ('regolith') and volatile components. Mars regolith composition has been modeled based on the measurements obtained with orbiter and lander spacecraft from which an average composition has been derived. The volatile inventory properties, both in the regolith and in the seasonal and perennial polar caps, has been taken into account by modeling the deposition of volatiles and its variations with geography and time all throughout the Martian year, from results from imaging data of orbiter spacecraft. Results are given in terms of fluxes, doses and LET, for most kinds of particles, namely protons, neutrons, alpha particles, heavy ions, pions, and muons for various soil compositions.

  8. Modeling Background Radiation in our Environment Using Geochemical Data

    Energy Technology Data Exchange (ETDEWEB)

    Malchow, Russell L.; Marsac, Kara [University of Nevada, Las Vegas; Burnley, Pamela [University of Nevada, Las Vegas; Hausrath, Elisabeth [Uniiversity of Nevada, Las Vegas; Haber, Daniel [University of Nevada, Las Vegas; Adcock, Christopher [University of Nevada, Las Vegas

    2015-02-01

    Radiation occurs naturally in bedrock and soil. Gamma rays are released from the decay of the radioactive isotopes K, U, and Th. Gamma rays observed at the surface come from the first 30 cm of rock and soil. The energy of gamma rays is specific to each isotope, allowing identification. For this research, data was collected from national databases, private companies, scientific literature, and field work. Data points were then evaluated for self-consistency. A model was created by converting concentrations of U, K, and Th for each rock and soil unit into a ground exposure rate using the following equation: D=1.32 K+ 0.548 U+ 0.272 Th. The first objective of this research was to compare the original Aerial Measurement System gamma ray survey to results produced by the model. The second objective was to improve the method and learn the constraints of the model. Future work will include sample data analysis from field work with a goal of improving the geochemical model.

  9. The Los Alamos dynamic radiation environment assimilation model (DREAM) for space weather specification and forecasting

    Energy Technology Data Exchange (ETDEWEB)

    Reeves, Geoffrey D [Los Alamos National Laboratory; Friedel, Reiner H W [Los Alamos National Laboratory; Chen, Yue [Los Alamos National Laboratory; Koller, Josef [Los Alamos National Laboratory; Henderson, Michael G [Los Alamos National Laboratory

    2008-01-01

    The Dynamic Radiation Environment Assimilation Model (DREAM) was developed at Los Alamos National Laboratory to assess, quantify, and predict the hazards from the natural space environment and the anthropogenic environment produced by high altitude nuclear explosions (HANE). DREAM was initially developed as a basic research activity to understand and predict the dynamics of the Earth's Van Allen radiation belts. It uses Kalman filter techniques to assimilate data from space environment instruments with a physics-based model of the radiation belts. DREAM can assimilate data from a variety of types of instruments and data with various levels of resolution and fidelity by assigning appropriate uncertainties to the observations. Data from any spacecraft orbit can be assimilated but DREAM was designed to function with as few as two spacecraft inputs: one from geosynchronous orbit and one from GPS orbit. With those inputs, DREAM can be used to predict the environment at any satellite in any orbit whether space environment data are available in those orbits or not. Even with very limited data input and relatively simple physics models, DREAM specifies the space environment in the radiation belts to a high level of accuracy. DREAM has been extensively tested and evaluated as we transition from research to operations. We report here on one set of test results in which we predict the environment in a highly-elliptical polar orbit. We also discuss long-duration reanalysis for spacecraft design, using DREAM for real-time operations, and prospects for 1-week forecasts of the radiation belt environment.

  10. Integration of the Radiation Belt Environment Model Into the Space Weather Modeling Framework

    Science.gov (United States)

    Glocer, A.; Toth, G.; Fok, M.; Gombosi, T.; Liemohn, M.

    2009-01-01

    We have integrated the Fok radiation belt environment (RBE) model into the space weather modeling framework (SWMF). RBE is coupled to the global magnetohydrodynamics component (represented by the Block-Adaptive-Tree Solar-wind Roe-type Upwind Scheme, BATS-R-US, code) and the Ionosphere Electrodynamics component of the SWMF, following initial results using the Weimer empirical model for the ionospheric potential. The radiation belt (RB) model solves the convection-diffusion equation of the plasma in the energy range of 10 keV to a few MeV. In stand-alone mode RBE uses Tsyganenko's empirical models for the magnetic field, and Weimer's empirical model for the ionospheric potential. In the SWMF the BATS-R-US model provides the time dependent magnetic field by efficiently tracing the closed magnetic field-lines and passing the geometrical and field strength information to RBE at a regular cadence. The ionosphere electrodynamics component uses a two-dimensional vertical potential solver to provide new potential maps to the RBE model at regular intervals. We discuss the coupling algorithm and show some preliminary results with the coupled code. We run our newly coupled model for periods of steady solar wind conditions and compare our results to the RB model using an empirical magnetic field and potential model. We also simulate the RB for an active time period and find that there are substantial differences in the RB model results when changing either the magnetic field or the electric field, including the creation of an outer belt enhancement via rapid inward transport on the time scale of tens of minutes.

  11. The Martian surface radiation environment – a comparison of models and MSL/RAD measurements

    Directory of Open Access Journals (Sweden)

    Matthiä Daniel

    2016-01-01

    Full Text Available Context: The Radiation Assessment Detector (RAD on the Mars Science Laboratory (MSL has been measuring the radiation environment on the surface of Mars since August 6th 2012. MSL-RAD is the first instrument to provide detailed information about charged and neutral particle spectra and dose rates on the Martian surface, and one of the primary objectives of the RAD investigation is to help improve and validate current radiation transport models. Aims: Applying different numerical transport models with boundary conditions derived from the MSL-RAD environment the goal of this work was to both provide predictions for the particle spectra and the radiation exposure on the Martian surface complementing the RAD sensitive range and, at the same time, validate the results with the experimental data, where applicable. Such validated models can be used to predict dose rates for future manned missions as well as for performing shield optimization studies. Methods: Several particle transport models (GEANT4, PHITS, HZETRN/OLTARIS were used to predict the particle flux and the corresponding radiation environment caused by galactic cosmic radiation on Mars. From the calculated particle spectra the dose rates on the surface are estimated. Results: Calculations of particle spectra and dose rates induced by galactic cosmic radiation on the Martian surface are presented. Although good agreement is found in many cases for the different transport codes, GEANT4, PHITS, and HZETRN/OLTARIS, some models still show large, sometimes order of magnitude discrepancies in certain particle spectra. We have found that RAD data is helping to make better choices of input parameters and physical models. Elements of these validated models can be applied to more detailed studies on how the radiation environment is influenced by solar modulation, Martian atmosphere and soil, and changes due to the Martian seasonal pressure cycle. By extending the range of the calculated particle

  12. Genesis Radiation Environment

    Science.gov (United States)

    Minow, Joseph I.; Altstatt, Richard L.; Skipworth, William C.

    2007-01-01

    The Genesis spacecraft launched on 8 August 2001 sampled solar wind environments at L1 from 2001 to 2004. After the Science Capsule door was opened, numerous foils and samples were exposed to the various solar wind environments during periods including slow solar wind from the streamer belts, fast solar wind flows from coronal holes, and coronal mass ejections. The Survey and Examination of Eroded Returned Surfaces (SEERS) program led by NASA's Space Environments and Effects program had initiated access for the space materials community to the remaining Science Capsule hardware after the science samples had been removed for evaluation of materials exposure to the space environment. This presentation will describe the process used to generate a reference radiation Genesis Radiation Environment developed for the SEERS program for use by the materials science community in their analyses of the Genesis hardware.

  13. Implications for space radiation environment models from CREAM & CREDO measurements over half a solar cycle.

    Science.gov (United States)

    Dyer, C S; Truscott, P R; Peerless, C L; Watson, C J; Evans, H E; Knight, P; Cosby, M; Underwood, C; Cousins, T; Noulty, R; Maag, C

    1999-10-01

    Flight data obtained between 1990 and 1997 from the Cosmic Radiation Environment Monitors CREAM & CREDO carried on UoSAT-3, Space Shuttle, STRV-1a (Space Technology Research Vehicle) and APEX (Advanced Photovoltaic and Electronics Experiment Spacecraft) provide coverage over half a solar cycle. The modulation of cosmic rays and evolution of the South Atlantic Anomaly are observed, the former comprising a factor of three increase at high latitudes and the latter a general increase accompanied by a north-westward drift. Comparison of particle fluxes and linear energy transfer (LET) spectra is made with improved environment & radiation transport calculations which account for shield distributions and secondary particles. While there is an encouraging convergence between predictions and observations, significant improvements are still required, particularly in the treatment of locally produced secondary particles. Solar-particle events during this time period have LET spectra significantly below the October 1989 event which has been proposed as a worst case model.

  14. The Chandra X-Ray Observatory's Radiation Environment and the AP-8/AE-8 Model

    CERN Document Server

    Virani, S N; Plucinsky, P P; Butt, Y M; Virani, Shanil N.; Mueller-Mellin, Reinhold; Plucinsky, Paul P.; Butt, Yousaf M.

    2000-01-01

    The Chandra X-ray Observatory (CXO) was launched on July 23, 1999 and reached its final orbit on August 7, 1999. The CXO is in a highly elliptical orbit, approximately 140,000 km x 10,000 km, and has a period of approximately 63.5 hours (~ 2.65 days). It transits the Earth's Van Allen belts once per orbit during which no science observations can be performed due to the high radiation environment. The Chandra X-ray Observatory Center (CXC) currently uses the National Space Science Data Center's ``near Earth'' AP-8/AE-8 radiation belt model to predict the start and end times of passage through the radiation belts. However, our scheduling software uses only a simple dipole model of the Earth's magnetic field. The resulting B, L magnetic coordinates, do not always give sufficiently accurate predictions of the start and end times of transit of the Van Allen belts. We show this by comparing to the data from Chandra's on-board radiation monitor, the EPHIN (Electron, Proton, Helium Instrument particle detector) instr...

  15. Space weather circulation model of plasma clouds as background radiation medium of space environment.

    Science.gov (United States)

    Kalu, A. E.

    A model for Space Weather (SW) Circulation with Plasma Clouds as background radiation medium of Space Environment has been proposed and discussed. Major characteristics of the model are outlined and the model assumes a baroclinic Space Environment in view of observed pronounced horizontal electron temperature gradient with prevailing weak vertical temperature gradient. The primary objective of the study is to be able to monitor and realistically predict on real- or near real-time SW and Space Storms (SWS) affecting human economic systems on Earth as well as the safety and Physiologic comfort of human payload in Space Environment in relation to planned increase in human space flights especially with reference to the ISS Space Shuttle Taxi (ISST) Programme and other prolonged deep Space Missions. Although considerable discussions are now available in the literature on SW issues, routine Meteorological operational applications of SW forecast data and information for Space Environment are still yet to receive adequate attention. The paper attempts to fill this gap in the literature of SW. The paper examines the sensitivity and variability in 3-D continuum of Plasmas in response to solar radiation inputs into the magnetosphere under disturbed Sun condition. Specifically, the presence of plasma clouds in the form of Coronal Mass Ejections (CMEs) is stressed as a major source of danger to Space crews, spacecraft instrumentation and architecture charging problems as well as impacts on numerous radiation - sensitive human economic systems on Earth. Finally, the paper considers the application of model results in the form of effective monitoring of each of the two major phases of manned Spaceflights - take-off and re-entry phases where all-time assessment of spacecraft transient ambient micro-incabin and outside Space Environment is vital for all manned Spaceflights as recently evidenced by the loss of vital information during take-off of the February 1, 2003 US Columbia

  16. PABLM. Accumulated Environment Radiation Dose

    Energy Technology Data Exchange (ETDEWEB)

    Napier, B.A.; Kennedy, W.E.Jr.; Soldat, J.K. [Pacific Northwest Lab., Richland, WA (United States)

    1981-04-01

    PABLM calculates internal radiation doses to man from radionuclides in food products and external radiation doses from radionuclides in the environment. Radiation doses from radionuclides in the environment may be calculated from deposition on the soil or plants during an atmospheric or liquid release, or from exposure to residual radionuclides after the releases have ended. Radioactive decay is considered during the release, after deposition, and during holdup of food after harvest. The radiation dose models consider exposure to radionuclides deposited on the ground or crops from contaminated air or irrigation water, radionuclides in contaminated drinking water, aquatic foods raised in contaminated water, and radionuclides in bodies of water and sediments where people might fish, boat, or swim. For vegetation, the radiation dose model considers both direct deposition and uptake through roots. Doses may be calculated for either a maximum-exposed individual or for a population group. The program is designed to calculate accumulated radiation doses from the chronic ingestion of food products that contain radionuclides and doses from the external exposure to radionuclides in the environment. A first-year committed dose is calculated as well as an integrated dose for a selected number of years.

  17. Transfer of Real-time Dynamic Radiation Environment Assimilation Model; Research to Operation

    Science.gov (United States)

    Cho, K. S. F.; Hwang, J.; Shin, D. K.; Kim, G. J.; Morley, S.; Henderson, M. G.; Friedel, R. H.; Reeves, G. D.

    2015-12-01

    Real-time Dynamic Radiation Environment Assimilation Model (rtDREAM) was developed by LANL for nowcast of energetic electrons' flux at the radiation belt to quantify potential risks from radiation damage at the satellites. Assimilated data are from multiple sources including LANL assets (GEO, GPS). For transfer from research to operation of the rtDREAM code, LANL/KSWC/NOAA makes a Memorandum Of Understanding (MOU) on the collaboration between three parts. By this MOU, KWSC/RRA provides all the support for transitioning the research version of DREAM to operations. KASI is primarily responsible for providing all the interfaces between the current scientific output formats of the code and useful space weather products that can be used and accessed through the web. In the second phase, KASI will be responsible in performing the work needed to transform the Van Allen Probes beacon data into "DREAM ready" inputs. KASI will also provide the "operational" code framework and additional data preparation, model output, display and web page codes back to LANL and SWPC. KASI is already a NASA partnering ground station for the Van Allen Probes' space weather beacon data and can here show use and utility of these data for comparison between rtDREAM and observations by web. NOAA has offered to take on some of the data processing tasks specific to the GOES data.

  18. Thermal Analysis of a Finite Element Model in a Radiation Dominated Environment

    Science.gov (United States)

    Page, Arthur T.

    2001-07-01

    This paper presents a brief overview of thermal analysis, evaluating the University of Arizona mirror design, for the Next Generation Space Telescope (NGST) Pre-Phase A vehicle concept. Model building begins using Thermal Desktop(TM), by Cullimore and Ring Technologies, to import a NASTRAN bulk data file from the structural model of the mirror assembly. Using AutoCAD(R) capabilities, additional surfaces are added to simulate the thermal aspects of the problem which, for due reason, are not part of the structural model. Surfaces are then available to accept thermophysical and thermo-optical properties. Thermal Desktop(TM) calculates radiation conductors using Monte Carlo simulations. Then Thermal Desktop(TM) generates the SINDA input file having a one-to-one correspondence with the NASTRAN node and element definitions. A model is now available to evaluate the mirror design in the radiation dominated environment, conduct parametric trade studies of the thermal design, and provide temperatures to the finite element structural model.

  19. Lunar radiation environment

    Science.gov (United States)

    Schwadron, Nathan; Spence, Harlan; Wilson, Jody

    One of the goals of the CRaTER investigation is to characterize the radiation environment near the Moon in order to enable exploration. The state-of-the-art understanding developed thus far during the LRO mission is documented in a special issue of the Spaceweather Journal entitled “Space Weather: Building the observational foundation to deduce biological effects of space radiation” (Schwadron et al., 2013a). This recently published CRaTER work probes deeper into the physics of the radiation environment at the Moon. It motivates and provides the scientific basis for new investigations in the next phase of the LRO mission. The effects of Galactic Cosmic Rays (GCRs) and Solar Energetic Particles (SEPs) range from chemical modification of the regolith, the generation of a radiation albedo that is increasingly illuminating chemical properties of the regolith, causing charging of the regolith and hazards to human explorers and robotic missions. Low-lunar orbit provides a platform for measuring SEP anisotropy over timescales of 2 hours both parallel and perpendicular to the ecliptic plane, and so far we have observed more than 18 SEP events with time-variable anisotropies during the LRO mission. Albedo proton maps of the Moon from CRaTER indicate that the flux of lunar albedo protons is correlated with elemental abundances at the lunar surface. The yield of albedo protons from the maria is 1% higher than the yield from the highlands, and there are localized peaks with even higher contrast (that may be co-located with peaks in trace elemental abundances as measured by the Lunar Prospector Gamma Ray Spectrometer). The Moon’s radiation environment both charges and affects the chemistry in the Moon’s polar regions, particularly in PSRs. This makes these regions a prime target for new CRaTER observations, since CRaTER measures GCRs and SEPs that penetrate the regolith down to 10s of cm. Thus, we review emerging discoveries from LRO/CRaTER’s remarkable exploration of

  20. Radiative Transfer Model of Dust Attenuation Curves in Clumpy, Galactic Environments

    CERN Document Server

    Seon, Kwang-Il

    2016-01-01

    The attenuation of starlight by dust in galactic environments is investigated through models of radiative transfer in a spherical, clumpy ISM. Extinction properties for MW, LMC, and SMC dust types are considered. It is illustrated that the attenuation curves are primarily determined by the wavelength dependence of absorption rather than by the underlying extinction (absorption+scattering) curve. Attenuation curves consistent with the "Calzetti attenuation curve" are found by assuming the silicate-carbonaceous dust model for the MW, but with the 2175A absorption bump suppressed or absent. The discrepancy between our results and previous work that claimed the SMC-type dust to be the most likely origin of the Calzetti curve is ascribed to the difference in adopted albedos; this study uses the theoretically calculated albedos whereas the previous ones adopted empirically derived albedos from observations of reflection nebulae. It is also found that the model attenuation curves calculated with the MW dust are well...

  1. Dependence of the Martian radiation environment on atmospheric depth: Modeling and measurement

    Science.gov (United States)

    Guo, Jingnan; Slaba, Tony C.; Zeitlin, Cary; Wimmer-Schweingruber, Robert F.; Badavi, Francis F.; Böhm, Eckart; Böttcher, Stephan; Brinza, David E.; Ehresmann, Bent; Hassler, Donald M.; Matthiä, Daniel; Rafkin, Scot

    2017-02-01

    The energetic particle environment on the Martian surface is influenced by solar and heliospheric modulation and changes in the local atmospheric pressure (or column depth). The Radiation Assessment Detector (RAD) on board the Mars Science Laboratory rover Curiosity on the surface of Mars has been measuring this effect for over four Earth years (about two Martian years). The anticorrelation between the recorded surface Galactic Cosmic Ray-induced dose rates and pressure changes has been investigated by Rafkin et al. (2014) and the long-term solar modulation has also been empirically analyzed and modeled by Guo et al. (2015). This paper employs the newly updated HZETRN2015 code to model the Martian atmospheric shielding effect on the accumulated dose rates and the change of this effect under different solar modulation and atmospheric conditions. The modeled results are compared with the most up-to-date (from 14 August 2012 to 29 June 2016) observations of the RAD instrument on the surface of Mars. Both model and measurements agree reasonably well and show the atmospheric shielding effect under weak solar modulation conditions and the decline of this effect as solar modulation becomes stronger. This result is important for better risk estimations of future human explorations to Mars under different heliospheric and Martian atmospheric conditions.

  2. Space Flight Ionizing Radiation Environments

    Science.gov (United States)

    Koontz, Steve

    2017-01-01

    The space-flight ionizing radiation (IR) environment is dominated by very high-kinetic energy-charged particles with relatively smaller contributions from X-rays and gamma rays. The Earth's surface IR environment is not dominated by the natural radioisotope decay processes. Dr. Steven Koontz's lecture will provide a solid foundation in the basic engineering physics of space radiation environments, beginning with the space radiation environment on the International Space Station and moving outward through the Van Allen belts to cislunar space. The benefits and limitations of radiation shielding materials will also be summarized.

  3. Overview of the Martian radiation environment experiment

    Energy Technology Data Exchange (ETDEWEB)

    Zeitlin, C.; Cleghorn, T.F.; Cucinotta, F.A.; Saganti, P.; Andersen, V.; Lee, K.T.; Pinsky, L.S.; Atwell, W.; Turner, R.; Badhwar, G.

    2004-12-01

    Space radiation presents a hazard to astronauts, particularly those journeying outside the protective influence of the geomagnetosphere. Crews on future missions to Mars will be exposed to the harsh radiation environment of deep space during the transit between Earth and Mars. Once on Mars, they will encounter radiation that is only slightly reduced, compared to free space, by the thin Martian atmosphere. NASA is obliged to minimize, where possible, the radiation exposures received by astronauts. Thus, as a precursor to eventual human exploration, it is necessary to measure the Martian radiation environment in detail. The MARIE experiment, aboard the 2001 Mars Odyssey spacecraft, is returning the first data that bear directly on this problem. Here we provide an overview of the experiment, including introductory material on space radiation and radiation dosimetry, a description of the detector, model predictions of the radiation environment at Mars, and preliminary dose-rate data obtained at Mars.

  4. Radiation Environment for the Jupiter Europa Orbiter

    Science.gov (United States)

    Jun, Insoo

    2008-09-01

    One of the major challenges for the Jupiter Europa Orbiter (JEO) mission would be that the spacecraft should be designed to survive an intense radiation environment expected at Jupiter and Europa. The proper definition of the radiation environments is the important first step, because it could affect almost every aspects of mission and spacecraft design. These include optimizing the trajectory to minimize radiation exposure, determining mission lifetime, selecting parts, materials, detectors and sensors, shielding design, etc. The radiation environments generated for the 2008 JEO study will be covered, emphasizing the radiation environment mainly responsible for the total ionizing dose (TID) and displacement damage dose (DDD). The latest models developed at JPL will be used to generate the TID and DDD environments. Finally, the major radiation issues will be summarized, and a mitigation plan will be discussed.

  5. Evaluation of standard radiation atmosphere aerosol models for a coastal environment

    Science.gov (United States)

    Whitlock, C. H.; Suttles, J. T.; Sebacher, D. I.; Fuller, W. H.; Lecroy, S. R.

    1986-01-01

    Calculations are compared with data from an experiment to evaluate the utility of standard radiation atmosphere (SRA) models for defining aerosol properties in atmospheric radiation computations. Initial calculations with only SRA aerosols in a four-layer atmospheric column simulation allowed a sensitivity study and the detection of spectral trends in optical depth, which differed from measurements. Subsequently, a more detailed analysis provided a revision in the stratospheric layer, which brought calculations in line with both optical depth and skylight radiance data. The simulation procedure allows determination of which atmospheric layers influence both downwelling and upwelling radiation spectra.

  6. Modeling Electrostatic Fields Generated by Internal Charging of Materials in Space Radiation Environments

    Science.gov (United States)

    Minow, Joseph I.

    2011-01-01

    Internal charging is a risk to spacecraft in energetic electron environments. DICTAT, NU MIT computational codes are the most widely used engineering tools for evaluating internal charging of insulator materials exposed to these environments. Engineering tools are designed for rapid evaluation of ESD threats, but there is a need for more physics based models for investigating the science of materials interactions with energetic electron environments. Current tools are limited by the physics included in the models and ease of user implementation .... additional development work is needed to improve models.

  7. Computer modeling characterization, and applications of Gallium Arsenide Gunn diodes in radiation environments

    Energy Technology Data Exchange (ETDEWEB)

    El- Basit, Wafaa Abd; El-Ghanam, Safaa Mohamed; Kamh, Sanaa Abd El-Tawab [Electronics Research Laboratory, Physics Department, Faculty of Women for Arts, Science and Education, Ain-Shams University, Cairo (Egypt); Abdel-Maksood, Ashraf Mosleh; Soliman, Fouad Abd El-Moniem Saad [Nuclear Materials Authority, Cairo (Egypt)

    2016-10-15

    The present paper reports on a trial to shed further light on the characterization, applications, and operation of radar speed guns or Gunn diodes on different radiation environments of neutron or γ fields. To this end, theoretical and experimental investigations of microwave oscillating system for outer-space applications were carried out. Radiation effects on the transient parameters and electrical properties of the proposed devices have been studied in detail with the application of computer programming. Also, the oscillation parameters, power characteristics, and bias current were plotted under the influence of different γ and neutron irradiation levels. Finally, shelf or oven annealing processes were shown to be satisfactory techniques to recover the initial characteristics of the irradiated devices.

  8. Computer Modeling, Characterization, and Applications of Gallium Arsenide Gunn Diodes in Radiation Environments

    Directory of Open Access Journals (Sweden)

    Wafaa Abd El-Basit

    2016-10-01

    Full Text Available The present paper reports on a trial to shed further light on the characterization, applications, and operation of radar speed guns or Gunn diodes on different radiation environments of neutron or γ fields. To this end, theoretical and experimental investigations of microwave oscillating system for outer-space applications were carried out. Radiation effects on the transient parameters and electrical properties of the proposed devices have been studied in detail with the application of computer programming. Also, the oscillation parameters, power characteristics, and bias current were plotted under the influence of different γ and neutron irradiation levels. Finally, shelf or oven annealing processes were shown to be satisfactory techniques to recover the initial characteristics of the irradiated devices.

  9. Improvement of the equivalent sphere model for better estimates of skin or eye dose in space radiation environments

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Z.W., E-mail: linz@ecu.ed [Department of Physics, East Carolina University, C-209 Howell Science Complex, Greenville, NC 27858-4353 (United States)

    2011-04-15

    It is often useful to get a quick estimate of the dose or dose equivalent of an organ, such as blood-forming organs, the eye or the skin, in a radiation field. Sometimes an equivalent sphere is used to represent the organ for this purpose. For space radiation environments, recently it has been shown that the equivalent sphere model does not work for the eye or the skin in solar particle event environments. In this study, we improve the representation of the eye and the skin using a two-component equivalent sphere model. Motivated by the two-peak structure of the body organ shielding distribution for the eye and the skin, we use an equivalent sphere with two radius parameters, for example a partial spherical shell of a smaller thickness over a proper fraction of the full solid angle combined with a concentric partial spherical shell of a larger thickness over the rest of the full solid angle, to represent the eye or the skin. We find that using an equivalent sphere with two radius parameters instead of one drastically improves the accuracy of the estimates of dose and dose equivalent in space radiation environments. For example, in solar particle event environments the average error in the estimate of the skin dose equivalent using an equivalent sphere with two radius parameters is about 8%, while the average error of the conventional equivalent sphere model using one radius parameter is around 100%.

  10. Development of MAAP5.0.3 Dose Model for Radiation Environment Effect Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Mi Ro [KHNP-CRI, Daejeon (Korea, Republic of)

    2015-10-15

    The equipment survivability assessment under the severe accident conditions should be performed. For the environmental conditions such as the pressure and temperature, they can be calculated using MAAP (Modular Accident Analysis Program) code. However, since MAAP itself cannot calculate the radiation DOSE, MAAP5 DOSE model should be developed in order to calculate the DOSE rate during the severe accidents. In this study, we developed the MAAP5 DOSE model for spent fuel pool of OPR1000 type NPP and calculated the DOSE to assess the survivability of the facilities in spent fuel pool and fuel handling region. Until now, there are so many uncertainties in the analysis for radiation effect during the severe accident. However, in terms of the establishment of the severe accident management strategy, quantitative analysis in order to find the general trend for radiation increase during the severe accident is useful. For the radiation environmental effect analysis, the previous studies are mainly focused inside the containment. However, after the Fukushima accident, the severe accident phenomena in the SFP have been the great issues in the nuclear industry including Korea. So, in this study, the dose rate for spent fuel building when the severe accident happens in the SFP is calculated using MAAP5 DOSE. As expected, the dose rate is increased right after the spent fuel is partially uncovered. However, the amount of dose is less significant since the rate of temperature increase is much faster than the rate of dose increase.

  11. The space radiation environment

    Energy Technology Data Exchange (ETDEWEB)

    Robbins, D.E.

    1997-04-30

    There are three primary sources of space radiation: galactic cosmic rays (GCR), trapped belt radiation, and solar particle events (SPE). All are composed of ions, the nuclei of atoms. Their energies range from a few MeV u{sup -1} to over a GeV u{sup -1}. These ions can fragment when they interact with spacecraft materials and produce energetic neutrons and ions of lower atomic mass. Absorbed dose rates inside a typical spacecraft (like the Space Shuttle) in a low inclination (28.5 degrees) orbit range between 0.05 and 2 mGy d{sup -1} depending on the altitude and flight inclination (angle of orbit with the equator). The quality factor of radiation in orbit depends on the relative contributions of trapped belt radiation and GCR, and the dose rate varies both with orbital altitude and inclination. The corresponding equivalent dose rate ranges between 0.1 and 4 mSv d{sup -1}. In high inclination orbits, like that of the Mir Space Station and as is planned for the International Space Station, blood-forming organ (BFO) equivalent dose rates as high as 1.5 mSv d{sup -1}. Thus, on a 1 y mission, a crew member could obtain a total dose of 0.55 Sv. Maximum equivalent dose rates measured in high altitude passes through the South Atlantic Anomaly (SAA) were 10 mSv h{sup -1}. For an interplanetary space mission (e.g., to Mars) annual doses from GCR alone range between 150 mSv y{sup -1} at solar maximum and 580 mSv y{sup -1} at solar minimum. Large SPE, like the October 1989 series, are more apt to occur in the years around solar maximum. In free space, such an event could contribute another 300 mSv, assuming that a warning system and safe haven can be effectively used with operational procedures to minimize crew exposures. Thus, the total dose for a 3 y mission to Mars could exceed 2 Sv.

  12. Advances in environmental radiation protection: re-thinking animal-environment interaction modelling for wildlife dose assessment

    Energy Technology Data Exchange (ETDEWEB)

    Wood, Michael D. [School of Environment and Life Sciences, University of Salford, Manchester, M4 4WT (United Kingdom); Beresford, Nicholas A. [School of Environment and Life Sciences, University of Salford, Manchester, M4 4WT (United Kingdom); Centre for Ecology and Hydrology, Bailrigg, Lancaster, LA1 4AP (United Kingdom); Bradshaw, Clare [Department of Ecology, Environment and Plant Sciences, Stockholm University, 10691 Stockholm (Sweden); Gashchak, Sergey [Chornobyl Centre for Nuclear Safety, Radioactive Waste and Radioecology, 07100 Slavutych (Ukraine); Hinton, Thomas G. [Institut de Radioprotection et de Surete Nucleaire (IRSN), Centre de Cadarache, 13115 Saint Paul-lez-Durance (France)

    2014-07-01

    Current wildlife dose assessment models adopt simplistic approaches to the representation of animal-environment interaction. The simplest approaches are to assume either that environmental media (e.g. soil, sediment or water) are uniformly contaminated or relating organism exposure to activity concentrations in media collected at the point of sampling of the animal. The external exposure of a reference organism is then estimated by defining the geometric relationship between the organism and the medium. For example, a reference organism within the soil would have a 4p exposure geometry and a reference organism on the soil would have a 2p exposure geometry. At best, the current modelling approaches recognise differences in media activity concentrations by calculating exposure for different areas of contamination and then estimating the fraction of time that an organism spends in each area. In other fields of pollution ecology, for example wildlife risk assessment for chemical pollution, more advanced approaches are being implemented to model animal-environment interaction and estimate exposure. These approaches include individual-based movement modelling and random walk modelling and a variety of software tools have been developed to facilitate the implementation of these models. Although there are more advanced animal-environment interaction modelling approaches that are available, it is questionable whether these should be adopted for use in environmental radiation protection. Would their adoption significantly reduce uncertainty within the assessment process and, if so, by how much? These questions are being addressed within the new TREE (TRansfer - Exposure - Effects) research programme funded by the United Kingdom Natural Environment Research Council (NERC) and within Working Group (WG) 8 of the International Atomic Energy Agency's MODARIA programme. MODARIA WG8 is reviewing some of the alternative approaches that have been developed for animal-environment

  13. Web-based description of the space radiation environment using the Bethe-Bloch model

    Science.gov (United States)

    Cazzola, Emanuele; Calders, Stijn; Lapenta, Giovanni

    2016-01-01

    Space weather is a rapidly growing area of research not only in scientific and engineering applications but also in physics education and in the interest of the public. We focus especially on space radiation and its impact on space exploration. The topic is highly interdisciplinary, bringing together fundamental concepts of nuclear physics with aspects of radiation protection and space science. We give a new approach to presenting the topic by developing a web-based application that combines some of the fundamental concepts from these two fields into a single tool that can be used in the context of advanced secondary or undergraduate university education. We present DREADCode, an outreach or teaching tool to rapidly assess the current conditions of the radiation field in space. DREADCode uses the available data feeds from a number of ongoing space missions (ACE, GOES-13, GOES-15) to produce a first order approximation of the radiation dose an astronaut would receive during a mission of exploration in deep space (i.e. far from the Earth’s shielding magnetic field and from the radiation belts). DREADCode is based on an easy-to-use GUI interface available online from the European Space Weather Portal (www.spaceweather.eu/dreadcode). The core of the radiation transport computation to produce the radiation dose from the observed fluence of radiation observed by the spacecraft fleet considered is based on a relatively simple approximation: the Bethe-Bloch equation. DREADCode also assumes a simplified geometry and material configuration for the shields used to compute the dose. The approach is approximate and sacrifices some important physics on the altar of rapid execution time, which allows a real-time operation scenario. There is no intention here to produce an operational tool for use in space science and engineering. Rather, we present an educational tool at undergraduate level that uses modern web-based and programming methods to learn some of the most important

  14. Web-based description of the space radiation environment using the Bethe-Bloch model

    CERN Document Server

    Cazzola, Emanuele; Lapenta, Giovanni

    2015-01-01

    Space weather is a rapidly growing area not only in scientific and engineering applications but also in physics education and in the interest of the public. We focus especially on space radiation and its impact on space exploration. The topic is highly interdisciplinary bringing together fundamental concepts of nuclear physics with aspects of radiation protection and space science. We present a new approach to presenting the topic by developing a web-based tool that combines some of the fundamental concepts from these two fields in a single tool that can be developed in the context of advanced secondary or undergraduate university education. We present DREADCode, an outreach or teaching tool to asses rapidly the current conditions of the radiation field in space. DREADCode uses the available data feeds from a number of ongoing space missions to produce a first order approximation of the dose an astronaut would receive during a mission of exploration in deep space. DREADcode is based on a intuitive GUI interfa...

  15. Radiation effects in the environment

    Energy Technology Data Exchange (ETDEWEB)

    Begay, F.; Rosen, L.; Petersen, D.F.; Mason, C.; Travis, B. [Los Alamos National Lab., NM (United States); Yazzie, A. [Navajo Nation, Window Rock, AZ (United States). Dept. of History; Isaac, M.C.P.; Seaborg, G.T. [Lawrence Berkeley National Lab., CA (United States); Leavitt, C.P. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Physics and Astronomy

    1999-04-01

    Although the Navajo possess substantial resource wealth-coal, gas, uranium, water-this potential wealth has been translated into limited permanent economic or political power. In fact, wealth or potential for wealth has often made the Navajo the victims of more powerful interests greedy for the assets under limited Navajo control. The primary focus for this education workshop on the radiation effects in the environment is to provide a forum where scientists from the nuclear science and technology community can share their knowledge toward the advancement and diffusion of nuclear science and technology issues for the Navajo public. The scientists will make an attempt to consider the following basic questions; what is science; what is mathematics; what is nuclear radiation? Seven papers are included in this report: Navajo view of radiation; Nuclear energy, national security and international stability; ABC`s of nuclear science; Nuclear medicine: 100 years in the making; Radon in the environment; Bicarbonate leaching of uranium; and Computational methods for subsurface flow and transport. The proceedings of this workshop will be used as a valuable reference materials in future workshops and K-14 classrooms in Navajo communities that need to improve basic understanding of nuclear science and technology issues. Results of the Begay-Stevens research has revealed the existence of strange and mysterious concepts in the Navajo Language of nature. With these research results Begay and Stevens prepared a lecture entitled The Physics of Laser Fusion in the Navajo language. This lecture has been delivered in numerous Navajo schools, and in universities and colleges in the US, Canada, and Alaska.

  16. Radiation Belt and Plasma Model Requirements

    Science.gov (United States)

    Barth, Janet L.

    2005-01-01

    Contents include the following: Radiation belt and plasma model environment. Environment hazards for systems and humans. Need for new models. How models are used. Model requirements. How can space weather community help?

  17. Ionizing Radiation Environments and Exposure Risks

    Science.gov (United States)

    Kim, M. H. Y.

    2015-12-01

    Space radiation environments for historically large solar particle events (SPE) and galactic cosmic rays (GCR) are simulated to characterize exposures to radio-sensitive organs for missions to low-Earth orbit (LEO), moon, near-Earth asteroid, and Mars. Primary and secondary particles for SPE and GCR are transported through the respective atmospheres of Earth or Mars, space vehicle, and astronaut's body tissues using NASA's HZETRN/QMSFRG computer code. Space radiation protection methods, which are derived largely from ground-based methods recommended by the National Council on Radiation Protection and Measurements (NCRP) or International Commission on Radiological Protections (ICRP), are built on the principles of risk justification, limitation, and ALARA (as low as reasonably achievable). However, because of the large uncertainties in high charge and energy (HZE) particle radiobiology and the small population of space crews, NASA develops distinct methods to implement a space radiation protection program. For the fatal cancer risks, which have been considered the dominant risk for GCR, the NASA Space Cancer Risk (NSCR) model has been developed from recommendations by NCRP; and undergone external review by the National Research Council (NRC), NCRP, and through peer-review publications. The NSCR model uses GCR environmental models, particle transport codes describing the GCR modification by atomic and nuclear interactions in atmospheric shielding coupled with spacecraft and tissue shielding, and NASA-defined quality factors for solid cancer and leukemia risk estimates for HZE particles. By implementing the NSCR model, the exposure risks from various heliospheric conditions are assessed for the radiation environments for various-class mission types to understand architectures and strategies of human exploration missions and ultimately to contribute to the optimization of radiation safety and well-being of space crewmembers participating in long-term space missions.

  18. AE9/AP9/SPM Radiation Environment Model: User’s Guide

    Science.gov (United States)

    2014-02-18

    of this document, and [ Seltzer , 1994]. The values in the ‘Shield Depths’ list may be displayed in units of ‘g/cm2’, ‘mm’ or ‘mils’. Using the drop...Energetic Particle and Space Plasma Environment,” Space Science Reviews, [http://dx.doi.org/10.1007/s11214-013-9964-y], March 2013. Seltzer , Stephen

  19. Radiation exposure in the moon environment

    Science.gov (United States)

    Reitz, Guenther; Berger, Thomas; Matthiae, Daniel

    2012-12-01

    During a stay on the moon humans are exposed to elevated radiation levels due to the lack of substantial atmospheric and magnetic shielding compared to the Earth's surface. The absence of magnetic and atmospheric shielding allows cosmic rays of all energies to impinge on the lunar surface. Beside the continuous exposure to galactic cosmic rays (GCR), which increases the risk of cancer mortality, exposure through particles emitted in sudden nonpredictable solar particle events (SPE) may occur. SPEs show an enormous variability in particle flux and energy spectra and have the potential to expose space crew to life threatening doses. On Earth, the contribution to the annual terrestrial dose of natural ionizing radiation of 2.4 mSv by cosmic radiation is about 1/6, whereas the annual exposure caused by GCR on the lunar surface is roughly 380 mSv (solar minimum) and 110 mSv (solar maximum). The analysis of worst case scenarios has indicated that SPE may lead to an exposure of about 1 Sv. The only efficient measure to reduce radiation exposure is the provision of radiation shelters. Measurements on the lunar surface performed during the Apollo missions cover only a small energy band for thermal neutrons and are not sufficient to estimate the exposure. Very recently some data were added by the Radiation Dose Monitoring (RADOM) instrument operated during the Indian Chandrayaan Mission and the Cosmic Ray Telescope (CRaTER) instrument of the NASA LRO (Lunar Reconnaisance Orbiter) mission. These measurements need to be complemented by surface measurements. Models and simulations that exist describe the approximate radiation exposure in space and on the lunar surface. The knowledge on the radiation exposure at the lunar surface is exclusively based on calculations applying radiation transport codes in combination with environmental models. Own calculations are presented using Monte-Carlo simulations to calculate the radiation environment on the moon and organ doses on the

  20. An Irreversible Thermodynamics Model for Graphite Sublimation in Intense Radiation Environments.

    Science.gov (United States)

    1980-09-15

    AD-AOG9 405 AEROSPACE CORP EL SEGUNDO CA VEHICLE ENGINEERING DIV F/IG 7/4 AN IRREVERSIBLE THERMODYNAMICS MODEL FOR GRAPHITE SUBLIMATION I--ETC(U) SEP...approved for The Aerospace Corporation by E. G. Hertler of the Vehicle Engineering Division and W. P. Thompson of the Space Plans Directorate. The Air Force...reason for this nonuniqueness is illustrated in Fig. 3. The sum of the species partial pressures and the sum of the species vapor pressures are shown

  1. Radiation Hardened Electronics for Extreme Environments

    Science.gov (United States)

    Keys, Andrew S.; Watson, Michael D.

    2007-01-01

    The Radiation Hardened Electronics for Space Environments (RHESE) project consists of a series of tasks designed to develop and mature a broad spectrum of radiation hardened and low temperature electronics technologies. Three approaches are being taken to address radiation hardening: improved material hardness, design techniques to improve radiation tolerance, and software methods to improve radiation tolerance. Within these approaches various technology products are being addressed including Field Programmable Gate Arrays (FPGA), Field Programmable Analog Arrays (FPAA), MEMS Serial Processors, Reconfigurable Processors, and Parallel Processors. In addition to radiation hardening, low temperature extremes are addressed with a focus on material and design approaches.

  2. Radiation Effects in the Space Telecommunications Environment

    Energy Technology Data Exchange (ETDEWEB)

    Fleetwood, Daniel M.; Winokur, Peter S.

    1999-05-17

    Trapped protons and electrons in the Earth's radiation belts and cosmic rays present significant challenges for electronics that must operate reliably in the natural space environment. Single event effects (SEE) can lead to sudden device or system failure, and total dose effects can reduce the lifetime of a telecommmiications system with significant space assets. One of the greatest sources of uncertainty in developing radiation requirements for a space system is accounting for the small but finite probability that the system will be exposed to a massive solar particle event. Once specifications are decided, standard laboratory tests are available to predict the total dose response of MOS and bipolar components in space, but SEE testing of components can be more challenging. Prospects are discussed for device modeling and for the use of standard commercial electronics in space.

  3. Verification of a Monte-Carlo planetary surface radiation environment model using gamma-ray data from Lunar Prospector and 2001 Mars Odyssey

    Energy Technology Data Exchange (ETDEWEB)

    Skidmore, M.S., E-mail: mss16@star.le.ac.u [Space Research Centre, Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH (United Kingdom); Ambrosi, R.M. [Space Research Centre, Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH (United Kingdom)

    2010-01-01

    Characterising a planetary radiation environment is important to: (1) assess the habitability of a planetary body for indigenous life; (2) assess the risks associated with manned exploration missions to a planetary body and (3) predict/interpret the results that remote sensing instrumentation may obtain from a planetary body (e.g. interpret the gamma-ray emissions from a planetary surface produced by radioactive decay or via the interaction of galactic cosmic rays to obtain meaningful estimates of the concentration of certain elements on the surface of a planet). The University of Leicester is developing instrumentation for geophysical applications that include gamma-ray spectroscopy, gamma-ray densitometry and radiometric dating. This paper describes the verification of a Monte-Carlo planetary radiation environment model developed using the MCNPX code. The model is designed to model the radiation environments of Mars and the Moon, but is applicable to other planetary bodies, and will be used to predict the performance of the instrumentation being developed at Leicester. This study demonstrates that the modelled gamma-ray data is in good agreement with gamma-ray data obtained by the gamma-ray spectrometers on 2001 Mars Odyssey and Lunar Prospector, and can be used to accurately model geophysical instrumentation for planetary science applications.

  4. Behaviour of organic materials in radiation environment

    CERN Document Server

    Tavlet, M

    2000-01-01

    Radiation effects in polymers are reminded together with the ageing factors. Radiation-ageing results are mainly discussed about thermosetting insulators, structural composites and cable-insulating materials. Some hints are given about high-voltage insulations, cooling fluids, organic scintillators and light-guides. Some parameters to be taken into account for the estimate of the lifetime of components in radiation environment are also shown. (23 refs).

  5. A system for protecting the environment from ionising radiation. Selecting reference fauna and flora, and the possible dose models and environmental geometries that could be applied to them

    Energy Technology Data Exchange (ETDEWEB)

    Pentreath, R.J. [Environmental Systems Science Centre, University of Reading, Whiteknights, P.O. Box 227, RG6 6AB Reading (United Kingdom); Woodhead, D.S. [Centre for Environment, Fisheries and Aquaculture Science, CEFAS Lowestoft Laboratory, Pakefield Road, Suffolk NR33 0HT Lowestoft (United Kingdom)

    2001-09-28

    In order to demonstrate, explicitly, that the environment can be protected with respect to controlled sources of ionising radiation, it is essential to have a systematic framework within which dosimetry models for fauna and flora can be used. And because of the practical limitations on what could reasonably be modelled and the amount of information that could reasonably be obtained, it is also necessary to limit the application of such models to a 'set' of fauna and flora within a 'reference' context. This paper, therefore, outlines the factors that will need to be considered to select such 'reference' fauna and flora, and describes some of the factors and constraints necessary to develop the associated dosimetry models. It also describes some of the most basic environmental geometries within which the dose models could be set in order to make comparisons amongst different radiation sources.

  6. Modeling the effectiveness of shielding in the earth-moon-mars radiation environment using PREDICCS: five solar events in 2012

    Directory of Open Access Journals (Sweden)

    Quinn Philip R.

    2017-01-01

    Full Text Available Radiation in the form of solar energetic particles (SEPs presents a severe risk to the short-term health of astronauts and the success of human exploration missions beyond Earth’s protective shielding. Modeling how shielding mitigates the dose accumulated by astronauts is an essential step toward reducing these risks. PREDICCS (Predictions of radiation from REleASE, EMMREM, and Data Incorporating the CRaTER, COSTEP, and other SEP measurements is an online tool for the near real-time prediction of radiation exposure at Earth, the Moon, and Mars behind various levels of shielding. We compare shielded dose rates from PREDICCS with dose rates from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER onboard the Lunar Reconnaissance Orbiter (LRO at the Moon and from the Radiation Assessment Detector (RAD on the Mars Science Laboratory (MSL during its cruise phase to Mars for five solar events in 2012 when Earth, MSL, and Mars were magnetically well connected. Calculations of the accumulated dose demonstrate a reasonable agreement between PREDICCS and RAD ranging from as little as 2% difference to 54%. We determine mathematical relationships between shielding levels and accumulated dose. Lastly, the gradient of accumulated dose between Earth and Mars shows that for the largest of the five solar events, lunar missions require aluminum shielding between 1.0 g cm−2 and 5.0 g cm−2 to prevent radiation exposure from exceeding the 30-day limits for lens and skin. The limits were not exceeded near Mars.

  7. Natural radiation environment III. [Lead Abstract

    Energy Technology Data Exchange (ETDEWEB)

    Gesell, T.F.; Lowder, W.M. (eds.)

    1980-01-01

    Separate abstracts were prepared for the 52 research papers presented at this symposium in April 1978. The major topics in this volume deal with penetrating radiation measurements, radiation surveys and population exposure, radioactivity in the indoor environment, and technologically enhanced natural radioactivity. (KRM)

  8. Evaluations of Risks from the Lunar and Mars Radiation Environments

    Science.gov (United States)

    Kim, Myung-Hee; Hayat, Matthew J.; Feiveson, Alan H.; Cucinotta, Francis A.

    2008-01-01

    Protecting astronauts from the space radiation environments requires accurate projections of radiation in future space missions. Characterization of the ionizing radiation environment is challenging because the interplanetary plasma and radiation fields are modulated by solar disturbances and the radiation doses received by astronauts in interplanetary space are likewise influenced. The galactic cosmic radiation (GCR) flux for the next solar cycle was estimated as a function of interplanetary deceleration potential, which has been derived from GCR flux and Climax neutron monitor rate measurements over the last 4 decades. For the chaotic nature of solar particle event (SPE) occurrence, the mean frequency of SPE at any given proton fluence threshold during a defined mission duration was obtained from a Poisson process model using proton fluence measurements of SPEs during the past 5 solar cycles (19-23). Analytic energy spectra of 34 historically large SPEs were constructed over broad energy ranges extending to GeV. Using an integrated space radiation model (which includes the transport codes HZETRN [1] and BRYNTRN [2], and the quantum nuclear interaction model QMSFRG[3]), the propagation and interaction properties of the energetic nucleons through various media were predicted. Risk assessment from GCR and SPE was evaluated at the specific organs inside a typical spacecraft using CAM [4] model. The representative risk level at each event size and their standard deviation were obtained from the analysis of 34 SPEs. Risks from different event sizes and their frequency of occurrences in a specified mission period were evaluated for the concern of acute health effects especially during extra-vehicular activities (EVA). The results will be useful for the development of an integrated strategy of optimizing radiation protection on the lunar and Mars missions. Keywords: Space Radiation Environments; Galactic Cosmic Radiation; Solar Particle Event; Radiation Risk; Risk

  9. Solar radiation models - review

    Directory of Open Access Journals (Sweden)

    M. Jamil Ahmad, G.N. Tiwari

    2010-05-01

    Full Text Available In the design and study of solar energy, information on solar radiation and its components at a given location is very essential. Solar radiation data are required by solar engineers, architects, agriculturists and hydrologists for many applications such as solar heating, cooking, drying and interior illumination of buildings. For this purpose, in the past, several empirical correlations have been developed in order to estimate the solar radiation around the world. The main objective of this study is to review the global solar radiation models available in the literature. There are several formulae which relate global radiation to other climatic parameters such as sunshine hours, relative humidity and maximum temperature. The most commonly used parameter for estimating global solar radiation is sunshine duration. Sunshine duration can be easily and reliably measured and data are widely available.

  10. The Radiation Environment of Exoplanet Atmospheres

    Directory of Open Access Journals (Sweden)

    Jeffrey L. Linsky

    2014-10-01

    Full Text Available Exoplanets are born and evolve in the radiation and particle environment created by their host star. The host star’s optical and infrared radiation heats the exoplanet’s lower atmosphere and surface, while the ultraviolet, extreme ultraviolet and X-radiation control the photochemistry and mass loss from the exoplanet’s upper atmosphere. Stellar radiation, especially at the shorter wavelengths, changes dramatically as a host star evolves leading to changes in the planet’s atmosphere and habitability. This paper reviews the present state of our knowledge concerning the time-dependent radiation emitted by stars with convective zones, that is stars with spectral types F, G, K, and M, which comprise nearly all of the host stars of detected exoplanets.

  11. NPS-SCAT CONOPS and Radiation Environment

    Science.gov (United States)

    2012-06-01

    interference with communication and other electronic hardware due to scintillation and wave refraction. The LEO plasma environment is at lower energy...effects include measurable changes in properties of semiconductors and a deterioration of the thermal radiation properties of materials due to the

  12. ATHENA radiation model

    Energy Technology Data Exchange (ETDEWEB)

    Shumway, R.W.

    1987-10-01

    The ATHENA computer program has many features that make it desirable to use as a space reactor evaluation tool. One of the missing features was a surface-to-surface thermal radiation model. A model was developed that allows any of the regular ATHENA heat slabs to radiate to any other heat slab. The view factors and surface emissivities must be specified by the user. To verify that the model was properly accounting for radiant energy transfer, two different types of test calculations were performed. Both calculations have excellent results. The updates have been used on both the INEL CDC-176 and the Livermore Cray. 7 refs., 2 figs., 6 tabs.

  13. A Comparison of Van Allen Belt Radiation Environment Modeling Programs: AE8/AP8 Legacy, AE9/AP9, and SPENVIS

    Science.gov (United States)

    Reed, Evan; Pellish, Jonathan

    2016-01-01

    In the space surrounding Earth there exists an active radiation environment consisting mostly of electrons and protons that have been trapped by Earths magnetic field. This radiation, also known as the Van Allen Belts, has the potential to damage man-made satellites in orbit; thus, proper precautions must be taken to shield NASA assets from this phenomenon. Data on the Van Allen Belts has been collected continuously by a multitude of space-based instruments since the beginning of space exploration. Subsequently, using theory to fill in the gaps in the collected data, computer models have been developed that take in the orbital information of a hypothetical mission and output the expected particle fluence and flux for that orbit. However, as new versions of the modeling system are released, users are left wondering how the new version differs from the old. Therefore, we performed a comparison of three different editions of the modeling system: AE8/AP8 (legacy), which is included in the model 9 graphical user interface as an option for ones calculations, AE9/AP9, and the Space Environment Information System (SPENVIS), which is an online-based form of AE8/AP8 developed by NASA and the European Space Agency that changed the code to allow the program to extrapolate data to predict fluence and flux at higher energies. Although this evaluation is still ongoing, it is predicted that the model 8 (legacy) and SPENVIS version will have identical outputs with the exception of the extended energy levels from SPENVIS, while model 9 will provide different fluences than model 8 based on additional magnetic field descriptions and on-orbit data.

  14. PABLM; accumulated environment radiation dose. [UNIVAC1100; FORTRAN

    Energy Technology Data Exchange (ETDEWEB)

    Fowler, T.B.; Tobias, M.L.; Fox, J.N.; Lawler, B.E.; Koppel, J.U.; Triplett, J.R.; Lynn, L.L.; Waldman, L.A.; Goldberg, I.; Greebler, P.; Kelley, M.D.; Davis, R.A.; Keck, C.E.; Redfield, J.A.; Murphy,; Soldat, J.K.

    PABLM calculates internal radiation doses to man from radionuclides in food products and external radiation doses from radionuclides in the environment. Radiation doses from radionuclides in the environment may be calculated from deposition on the soil or plants during an atmospheric or liquid release, or from exposure to residual radionuclides after the releases have ended. Radioactive decay is considered during the release, after deposition, and during holdup of food after harvest. The radiation dose models consider exposure to radionuclides deposited on the ground or crops from contaminated air or irrigation water, radionuclides in contaminated drinking water, aquatic foods raised in contaminated water, and radionuclides in bodies of water and sediments where people might fish, boat, or swim. For vegetation, the radiation dose model considers both direct deposition and uptake through roots. Doses may be calculated for either a maximum-exposed individual or for a population group. The program is designed to calculate accumulated radiation doses from the chronic ingestion of food products that contain radionuclides and doses from the external exposure to radionuclides in the environment. A first-year committed dose is calculated as well as an integrated dose for a selected number of years.UNIVAC1100; FORTRAN; EXEC8; 80,000 words of memory are required to execute the PABLM program.

  15. Radiation resistence of microorganisms from radiation sterilization processing environments

    Science.gov (United States)

    Sabovljev, Svetlana A.; Žunić, Zora S.

    The radiation resistance of microorganisms was examined on the samples of dust collected from the radiation sterilization processing environments including assembly, storage, and sterilization plant areas. The isolation of radiation resistant strains was performed by irradiation with screening doses ranging from 10 to 35 kGy and test pieces containing 10 6 to 10 8 CFU in dried serum-broth, representing 100 to 5000 colonies of primary cultures of microorganisms from 7 different sites. In an examination of 16900 colonies of aerobic microorganisms from 3 hygienically controlled production sites and 4 uncontrolled ones, 30 strains of bacteria were isolated. Of those 15 were classified as genus Bacillus, 9 as Micrococcus and 6 as Sarcina. All of the 15 strains of Gram positive sporeforming aerobic rods exhibited an exponential decrease in the surviving fraction as a function of dose, indicating that the inactivation of spores of aerobic rods is a consequence of a single energy deposition into the target. All strains were found to be moderately resistant to radiation with D-6 values (dose required to reduce survival to 6 log cycles) between 18 and 26 kGy. All of the isolated Gram positive cocci showed inactivation curves having a shoulder, indicating that different processes are involved in the inactivation of these cells, e.g. accumulation of sublethal lesions, or final repair capacity of potential lethal lesions. Moderate radiation resistance was observed in 13 strains with D-6 values between 16 to 30 kGy. Two slow-growing, red pigmented strains tentatively classified as genus Micrococcus isolated from uncontrolled sites (human dwellings) were exceptionally resistant with D-6 more than 45 kGy. For hygienically controlled sites, Gram positive spereforming rods composed two thirds of the resistant microflora, while Gram positive cocci comprised one third. For hygienically uncontrolled sites this ratio was reversed. An assumption is made that one isolated strain has grown

  16. Contribution to developing the environment radiation protection methodology

    Energy Technology Data Exchange (ETDEWEB)

    Oudalova, A. [Institute of Atomic Power Engineering NRNU MEPhI (Russian Federation); Alexakhin, R.; Dubynina, M. [Russian Institute of Agricultural Radiology and Agroecology (Russian Federation)

    2014-07-01

    The environment sustainable development and biota protection, including the environment radiation protection are issues of nowadays interest in the society. An activity is ongoing on the development of a system of radiation protection for non-human biota. Anthropocentric and eco-centric principles are widely discussed. ICRP Publications 103, 108, 114 and many other reports and articles refer to the topic of environmental protection, reference animals and plants set, corresponding transfer parameters, dose models and derived consideration reference levels. There is still an open field for discussion of methods and approaches to get well-established procedure to assess environmental risks of radiation impacts to different organisms, populations and ecosystems. A huge work has been done by the ICRP and other organizations and research groups to develop and systematize approaches for this difficult subject. This activity, however, is not everywhere well-known and perceived, and more efforts are needed to bring ideas of eco-centric strategy in the environment radiation protection not only to public but to specialists in many countries as well. One of the main points of interest is an assessment of critical doses and doses rates for flora and fauna species. Some aspects of a possible procedure to find their estimates are studied in this work, including criteria for datasets of good quality, models of dose dependence, sensitivity of different umbrella endpoints and methods of original massive datasets treatment. Estimates are done based on information gathered in a database on radiation-induced effects in plants. Data on biological effects in plants (umbrella endpoints of reproductive potential, survival, morbidity, morphological, biochemical, and genetic effects) in dependence on dose and dose rates of ionizing radiation have been collected from reviewed publications and maintained in MS Access format. The database now contains about 7000 datasets and 25000 records

  17. Modeling Radiation Fog

    Science.gov (United States)

    K R, Sreenivas; Mohammad, Rafiuddin

    2016-11-01

    Predicting the fog-onset, its growth and dissipation helps in managing airports and other modes of transport. After sunset, occurrence of fog requires moist air, low wind and clear-sky conditions. Under these circumstances radiative heat transfer plays a vital role in the NBL. Locally, initiation of fog happens when the air temperature falls below the dew-point. Thus, to predict the onset of fog at a given location, one has to compute evolution of vertical temperature profile. Earlier,our group has shown that the presence of aerosols and vertical variation in their number density determines the radiative-cooling and hence development of vertical temperature profile. Aerosols, through radiation in the window-band, provides an efficient path for air layers to lose heat to the cold, upper atmosphere. This process creates cooler air layer between warmer ground and upper air layers and resulting temperature profile facilitate the initiation of fog. Our results clearly indicates that accounting for the presence of aerosols and their radiative-transfer is important in modeling micro-meteorological process of fog formation and its evolution. DST, Govt. INDIA.

  18. Space Environment Modeling

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes presentation materials and outputs from operational space environment models produced by the NOAA Space Weather Prediction Center (SWPC) and...

  19. High-Performance, Radiation-Hardened Electronics for Space Environments

    Science.gov (United States)

    Keys, Andrew S.; Watson, Michael D.; Frazier, Donald O.; Adams, James H.; Johnson, Michael A.; Kolawa, Elizabeth A.

    2007-01-01

    The Radiation Hardened Electronics for Space Environments (RHESE) project endeavors to advance the current state-of-the-art in high-performance, radiation-hardened electronics and processors, ensuring successful performance of space systems required to operate within extreme radiation and temperature environments. Because RHESE is a project within the Exploration Technology Development Program (ETDP), RHESE's primary customers will be the human and robotic missions being developed by NASA's Exploration Systems Mission Directorate (ESMD) in partial fulfillment of the Vision for Space Exploration. Benefits are also anticipated for NASA's science missions to planetary and deep-space destinations. As a technology development effort, RHESE provides a broad-scoped, full spectrum of approaches to environmentally harden space electronics, including new materials, advanced design processes, reconfigurable hardware techniques, and software modeling of the radiation environment. The RHESE sub-project tasks are: SelfReconfigurable Electronics for Extreme Environments, Radiation Effects Predictive Modeling, Radiation Hardened Memory, Single Event Effects (SEE) Immune Reconfigurable Field Programmable Gate Array (FPGA) (SIRF), Radiation Hardening by Software, Radiation Hardened High Performance Processors (HPP), Reconfigurable Computing, Low Temperature Tolerant MEMS by Design, and Silicon-Germanium (SiGe) Integrated Electronics for Extreme Environments. These nine sub-project tasks are managed by technical leads as located across five different NASA field centers, including Ames Research Center, Goddard Space Flight Center, the Jet Propulsion Laboratory, Langley Research Center, and Marshall Space Flight Center. The overall RHESE integrated project management responsibility resides with NASA's Marshall Space Flight Center (MSFC). Initial technology development emphasis within RHESE focuses on the hardening of Field Programmable Gate Arrays (FPGA)s and Field Programmable Analog

  20. Saturn Ring Radiation Environment for the Cassini Grand Finale Orbits

    Science.gov (United States)

    Cooper, John F.; Kollmann, Peter; Johnson, Robert E.; Roussos, Elias; Sittler, Edward C.; Sturner, Steven J.

    2016-10-01

    Grand Finale (proximal) orbits of Cassini from April to September 2017 will provide an unprecedented opportunity for further in-situ exploration of the energetic radiation environment primarily arising from galactic cosmic ray interactions with the main rings. Improved modeling of these interactions contributes to ring mass properties, radiation chemistry, and source modeling for trapped radiation within and beyond the rings. Our new GEANT simulations show that these interactions produce very substantial fluxes of secondary gamma rays, neutrons, electrons, protons, and more short-lived particles. Cosmic ray albedo neutron decay from ring neutron emissions provides the primary source of trapped protons near and above 10 MeV in the radiation belts extending from beyond the F ring to the orbit of Tethys. Fluxes of these high-energy trapped protons increased as expected with declining solar activity from 2004 through 2009, consistent with decreasing modulation of the galactic cosmic ray protons and heavier ions by the solar wind. In 2017 solar activity and modulation will again be declining from earlier maximum levels in 2012 - 2014, while solar illumination of the rings will be near solstice levels. There may then be similarities in the ring radiation and plasma environment to conditions in 2004. In comparison, the 1979 traversal of the main rings by Pioneer 11 occurred during peak solar activity but declining cosmic ray flux. The questions are then what radiation environment we might expect to find during the Grand Finale orbits, how would the Cassini MIMI LEMMS sensor respond to this environment, and how might these new measurements change our understanding of the rings? During SOI flyover of the rings, LEMMS nominal data showed intensities higher than those from Pioneer 11 to an extent that cannot be explained by the updated interaction model. LEMMS more likely responded to penetrating high-energy radiation at energies outside its nominal ranges for electrons and

  1. Radiation environment at LEO orbits: MC simulation and experimental data.

    Science.gov (United States)

    Zanini, Alba; Borla, Oscar; Damasso, Mario; Falzetta, Giuseppe

    The evaluations of the different components of the radiation environment in spacecraft, both in LEO orbits and in deep space is of great importance because the biological effect on humans and the risk for instrumentation strongly depends on the kind of radiation (high or low LET). That is important especially in view of long term manned or unmanned space missions, (mission to Mars, solar system exploration). The study of space radiation field is extremely complex and not completely solved till today. Given the complexity of the radiation field, an accurate dose evaluation should be considered an indispensable part of any space mission. Two simulation codes (MCNPX and GEANT4) have been used to assess the secondary radiation inside FO-TON M3 satellite and ISS. The energy spectra of primary radiation at LEO orbits have been modelled by using various tools (SPENVIS, OMERE, CREME96) considering separately Van Allen protons, the GCR protons and the GCR alpha particles. This data are used as input for the two MC codes and transported inside the spacecraft. The results of two calculation meth-ods have been compared. Moreover some experimental results previously obtained on FOTON M3 satellite by using TLD, Bubble dosimeter and LIULIN detector are considered to check the performances of the two codes. Finally the same experimental device are at present collecting data on the ISS (ASI experiment BIOKIS -nDOSE) and at the end of the mission the results will be compared with the calculation.

  2. High Radiation Environment Nuclear Fragment Separator Magnet

    Energy Technology Data Exchange (ETDEWEB)

    Kahn, Stephen [Muons, Inc., Batavia, IL (United States); Gupta, Ramesh [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2016-01-31

    Superconducting coils wound with HTS conductor can be used in magnets located in a high radiation environment. NbTi and Nb3Sn superconductors must operate at 4.5 K or below where removal of heat is less efficient. The HTS conductor can carry significant current at higher temperatures where the Carnot efficiency is significantly more favorable and where the coolant heat capacity is much larger. Using the HTS conductor the magnet can be operated at 40 K. This project examines the use of HTS conductor for the Michigan State University Facility For Rare Isotope Beams (FRIB) fragment separator dipole magnet which bends the beam by 30° and is located in a high radiation region that will not be easily accessible. Two of these magnets are needed to select the chosen isotope. There are a number of technical challenges to be addressed in the design of this magnet. The separator dipole is 2 m long and subtends a large angle. The magnet should keep a constant transverse field profile along its beam reference path. Winding coils with a curved inner segment is difficult as the conductor will tend to unwind during the process. In the Phase I project two approaches to winding the conductor were examined. The first was to wind the coils with curved sections on the inner and outer segments with the inner segment wound with negative curvature. The alternate approach was to use a straight segment on the inner segment to avoid negative curvature. In Phase I coils with a limited number of turns were successfully wound and tested at 77 K for both coil configurations. The Phase II program concentrated on the design, coil winding procedures, structural analysis, prototyping and testing of an HTS curved dipole coil at 40 K with a heat load representative of the radiation environment. One of the key criteria of the design of this magnet is to avoid the use of organic materials that would degrade rapidly in radiation. The Lorentz forces expected from the coils interacting with the

  3. Reliability of computer memories in radiation environment

    Directory of Open Access Journals (Sweden)

    Fetahović Irfan S.

    2016-01-01

    Full Text Available The aim of this paper is examining a radiation hardness of the magnetic (Toshiba MK4007 GAL and semiconductor (AT 27C010 EPROM and AT 28C010 EEPROM computer memories in the field of radiation. Magnetic memories have been examined in the field of neutron radiation, and semiconductor memories in the field of gamma radiation. The obtained results have shown a high radiation hardness of magnetic memories. On the other side, it has been shown that semiconductor memories are significantly more sensitive and a radiation can lead to an important damage of their functionality. [Projekat Ministarstva nauke Republike Srbije, br. 171007

  4. The ST environment: Expected charged particle radiation levels

    Science.gov (United States)

    Stassinopoulos, E. G.

    1978-01-01

    The external (surface incident) charged particle radiation, predicted for the ST satellite at the three different mission altitudes, was determined in two ways: (1) by orbital flux-integration and (2) by geographical instantaneous flux-mapping. The latest standard models of the environment were used in this effort. Magnetic field definitions for three nominal circular trajectories and for the geographic mapping positions were obtained from a current field model. Spatial and temporal variations or conditions affecting the static environment models were considered and accounted for, wherever possible. Limited shielding and dose evaluations were performed for a simple geometry. Results, given in tabular and graphical form, are analyzed, explained, and discussed. Conclusions are included.

  5. Predictive aging results in radiation environments

    Science.gov (United States)

    Gillen, Kenneth T.; Clough, Roger L.

    1993-06-01

    We have previously derived a time-temperature-dose rate superposition methodology, which, when applicable, can be used to predict polymer degradation versus dose rate, temperature and exposure time. This methodology results in predictive capabilities at the low dose rates and long time periods appropriate, for instance, to ambient nuclear power plant environments. The methodology was successfully applied to several polymeric cable materials and then verified for two of the materials by comparisons of the model predictions with 12 year, low-dose-rate aging data on these materials from a nuclear environment. In this paper, we provide a more detailed discussion of the methodology and apply it to data obtained on a number of additional nuclear power plant cable insulation (a hypalon, a silicone rubber and two ethylene-tetrafluoroethylenes) and jacket (a hypalon) materials. We then show that the predicted, low-dose-rate results for our materials are in excellent agreement with long-term (7-9 year) low-dose-rate results recently obtained for the same material types actually aged under bnuclear power plant conditions. Based on a combination of the modelling and long-term results, we find indications of reasonably similar degradation responses among several different commercial formulations for each of the following "generic" materials: hypalon, ethylene-tetrafluoroethylene, silicone rubber and PVC. If such "generic" behavior can be further substantiated through modelling and long-term results on additional formulations, predictions of cable life for other commercial materials of the same generic types would be greatly facilitated.

  6. On the Radiation Protection of the Environment

    Energy Technology Data Exchange (ETDEWEB)

    Soberhart, L. J.; Clausse, A.; D' Amato, E.

    2004-07-01

    Over the last decade, substantial advances in what is know as legal protection of the environment, -as a different matter from human being protection- have been made. Some national legislations include serious penalties against environmental damage. It is becoming customary to consider a serious offence any excess in the prescribed limits of radioactive materials release to the environment. What these limits mean, however, is not completely clear nowadays. According to the International Commission on Radiological Protection (ICRP) the standards of environmental control needed to protect man to the degree currently thought desirable will ensure that other species are not put at risk, although, occasionally, individual members of non human species might be harmed. However the use of limits of radioactive releases resulting from the direct application of ICRP recommend limits as legal references for the applicable offences in environmental protection is certainly a misconception. In this paper a conceptual framework for the calculation of legal limits for environmental radioprotection are presented. The approach is based on an ecosystem perspective, assessing the impact of radioactive releases on the ecosystem dynamics and equilibrium. The method is based on functional groups models -i.e. groups of species that are selected from a number of criteria such as play similar rules in the chain of nutrients or have the same radiosensitivity- providing the basis for prescribed limits of the radioactive material release to the environment. The methodology is applied to a system of three functional groups in equilibrium, with is affected by radioactive intrusion. Different impacts on the equilibrium can be identified, depending on the amount of radioactive material released to the environment. It is shown how the concept of equilibrium breakdown can be applied in order to assess the radiological impact. (Author) 8 refs.

  7. Status of Galileo interim radiation electron model

    Science.gov (United States)

    Garrett, H. B.; Jun, I.; Ratliff, J. M.; Evans, R. W.; Clough, G. A.; McEntire, R. W.

    2003-01-01

    Measurements of the high energy, omni-directional electron environment by the Galileo spacecraft Energetic Particle Detector (EDP) were used to develop a new model of Jupiter's trapped electron radiation in the jovian equatorial plane for the range 8 to 16 Jupiter radii.

  8. Evaluation of the Radiation Environment of the LHCb Experiment

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00341385; Corti, Gloria

    The unprecedented radiation levels of the Large Hadron Collider (LHC) during high-energy proton-proton collisions will have an impact on the operation of its experiments’ detectors and electronics. LHCb, one of the 4 major LHC experiments, has started operation in 2009 and from 2011 onward it has been collecting data at and above its design luminosity. Detectors and associated detector electronics are prone to damage if the radiation levels exceed the expected values. It is essential to monitor the radiation environment of the experimental area and compare it with predictions obtained from simulation studies in order to assess the situation and take corrective action in case of need. Understanding the existing radiation environment will also provide important input to the planning of maintenance and for operation at upgrade luminosity. A set of radiation detectors has been installed in the LHCb experimental area to measure different aspects of its radiation environment. Passive dosimeters including Thermo-L...

  9. Internal Charging Design Environments for the Earths Radiation Belts

    Science.gov (United States)

    Minow, Joseph I.; Edwards, David L.

    2009-01-01

    Relativistic electrons in the Earth's radiation belts are a widely recognized threat to spacecraft because they penetrate lightly shielded vehicle hulls and deep into insulating materials where they accumulate to sufficient levels to produce electrostatic discharges. Strategies for evaluating the magnitude of the relativistic electron flux environment and its potential for producing ESD events are varied. Simple "rule of thumb" estimates such as the widely used 10(exp 10) e-/sq cm fluence within 10 hour threshold for the onset of pulsing in dielectric materials provide a quick estimate of when to expect charging issues. More sophisticated strategies based on models of the trapped electron flux within the Earth s magnetic field provide time dependent estimates of electron flux along spacecraft orbits and orbit integrate electron flux. Finally, measurements of electron flux can be used to demonstrate mean and extreme relativistic electron environments. This presentation will evaluate strategies used to specify energetic electron flux and fluence environments along spacecraft trajectories in the Earth s radiation belts.

  10. The Martian Radiation Environment Experiment -- Results and Status

    Science.gov (United States)

    Zeitlin, C.; Cleghorn, T. F.; Cucinotta, F. A.; Saganti, P.; Andersen, V.; Lee, K. T.; Pinsky, L. S.; Atwell, W.; Turner, R.

    2004-05-01

    Ionizing radiation in space presents a potentially serious health hazard to astronauts on long-duration missions. Missions that take humans outside the geomagnetosphere (which provides significant shielding for crews in low-Earth orbit) are of particular concern. A mission to Mars would expose a crew to a substantial radiation dose from high-energy heavy ions in the Galactic Cosmic Radiation (GCR). Though not expected to cause acute effects, such exposures might endanger the long-term health of crewmembers, leading to increased risk of late effects such as cancer and cataract. Since the biological effects of these ions are not well understood, NASA cannot yet specify career limits for deep-space missions. While ground-based research in radiobiology continues, it is necessary to characterize the radiation field on the Martian surface. This is determined by the radiation incident on the top of the Martian atmosphere, the transmission properties of the atmosphere, and the production of secondary particles (neutrons in particular) in the upper part of the surface. The Martian Radiation Environment Experiment (MARIE), aboard the 2001 Mars Odyssey spacecraft, has returned the first detailed measurements of the radiation field incident on the atmosphere. MARIE consists of a stack of silicon charged-particle detectors, designed to measure the nearly-constant flux of energetic Galactic Cosmic Rays (GCR) and intermittent Solar Particle Events (SPE). The detector is optimized for the detection of solar protons and helium in the energy range from 30 to 75 MeV/nucleon, though higher energies and heavier ions are also detected. Despite considerable uncertainties in data normalization, the measured dose agrees with model calculations, to an accuracy well within the (conservatively) estimated errors. As of this writing (Feb. 2004), MARIE is off, having sustained damage during the large Solar Particle Event of Oct. 29, 2003. Attempts to recover the instrument will resume in the

  11. Emergency Medical Rescue in a Radiation Environment

    Energy Technology Data Exchange (ETDEWEB)

    Briesmeister, L.; Ellington, Y.; Hollis, R.; Kunzman, J.; McNaughton, M.; Ramsey, G.; Somers, B.; Turner, A.; Finn, J.

    1999-09-14

    Previous experience with emergency medical rescues in the presence of radiation or contamination indicates that the training provided to emergency responders is not always appropriate. A new course developed at Los Alamos includes specific procedures for emergency response in a variety of radiological conditions.

  12. Diamond based detectors for high temperature, high radiation environments

    Science.gov (United States)

    Metcalfe, A.; Fern, G. R.; Hobson, P. R.; Smith, D. R.; Lefeuvre, G.; Saenger, R.

    2017-01-01

    Single crystal CVD diamond has many desirable properties as a radiation detector; exceptional radiation hardness and physical hardness, chemical inertness, low Z (close to human tissue, good for dosimetry and transmission mode applications), wide bandgap (high temperature operation with low noise and solar blind), an intrinsic pathway to fast neutron detection through the 12C(n,α)9Be reaction. This combination of radiation hardness, temperature tolerance and ability to detect mixed radiation types with a single sensor makes diamond particularly attractive as a detector material for harsh environments such as nuclear power station monitoring (fission and fusion) and oil well logging. Effective exploitation of these properties requires the development of a metallisation scheme to give contacts that remain stable over extended periods at elevated temperatures (up to 250°C in this instance). Due to the cost of the primary detector material, computational modelling is essential to best utilise the available processing methods for optimising sensor response through geometry and conversion media configurations and to fully interpret experimental data. Monte Carlo simulations of our diamond based sensor have been developed, using MCNP6 and FLUKA2011, assessing the sensor performance in terms of spectral response and overall efficiency as a function of the detector and converter geometry. Sensors with varying metallisation schemes for high temperature operation have been fabricated at Brunel University London and by Micron Semiconductor Limited. These sensors have been tested under a varied set of conditions including irradiation with fast neutrons and alpha particles at high temperatures. The presented study indicates that viable metallisation schemes for high temperature contacts have been successfully developed and the modelling results, supported by preliminary experimental data from partners, indicate that the simulations provide a reasonable representation of

  13. Radiative shocks create environments for dust formation in novae

    CERN Document Server

    Derdzinski, Andrea M; Lazzati, Davide

    2016-01-01

    Classical novae commonly show evidence of rapid dust formation within months of the outburst. However, it is unclear how molecules and grains are able to condense within the ejecta given the potentially harsh environment created by ionizing radiation from the white dwarf. Motivated by the evidence for powerful radiative shocks within nova outflows, we propose that dust formation occurs within the cool, dense shell behind these shocks. We incorporate a simple molecular chemistry network and classical nucleation theory with a model for the thermodynamic evolution of the post-shock gas to demonstrate the formation of both carbon and forsterite ($\\rm Mg_2SiO_4$) grains. The high densities due to radiative shock compression ($n \\sim 10^{14}$ cm$^{-3}$) result in CO saturation and rapid dust nucleation. Grains grow efficiently to large sizes $\\gtrsim 0.1\\mu$m, in agreement with IR observations of dust-producing novae, and with total dust masses sufficient to explain massive extinction events such as V705 Cas. As in...

  14. Radiation Environments and their Impact at the CERN's Injector Chain

    CERN Document Server

    De Carvalho Saraiva, Joao Pedro; CERN. Geneva. ATS Department

    2015-01-01

    Mixed particle and energy radiation fields present at the Large Hadron Collider (LHC) and its Injector Chain are responsible for failures on electronic devices located in the vicinity of the accelerator beam lines. These radiation effects on electronics and, more generally, the overall radiation damage issues have a direct impact on component and system lifetimes, as well as on maintenance requirements and radiation exposure to personnel who have to intervene and fix the faults. This note describes the different radiation environments present along the CERN’s Injector Chain and the expected evolution over the next years with the ongoing LHC Injectors Upgrade (LIU) project. The available dosimetry and beam monitoring systems used to assess radiation levels are presented, outlining their respective pros and cons. The interplay between Monte Carlo simulations and the available radiation monitoring in the Injectors is also presented.

  15. The JPL Neptune Radiation Model (NMOD)

    Science.gov (United States)

    Garrett, Henry; Evans, Robin

    2017-01-01

    The objective of this study is the development of a comprehensive radiation model of the Neptunian environment for JPL mission planning. The ultimate goal is to provide a description of the high-energy electron and proton environments and the magnetic field at Neptune that can be used for engineering design. The JPL Neptune Radiation Model (NMOD) models the high-energy electrons and protons between 0.025 MeV and 5 MeV based on the California Institute of Technology's Cosmic Ray Subsystem and the Applied Physics Laboratory's Low Energy Charged Particle Detector on Voyager 2. As in previous JPL radiation models, the form of the Neptunian model is based on magnetic field coordinates and requires a conversion from spacecraft coordinates to Neptunian-centered magnetic "B-L" coordinates. Two types of magnetic field models have been developed for Neptune: 1) simple "offset, tilted dipoles" (OTD), and 2) a complex, multi-pole expansion model ("O8"). A review of the existing data on Neptune and a search of the NASA Planetary Data System (PDS) were completed to obtain the most current descriptions of the Neptunian high-energy particle environment. These data were fit in terms of the O8 B-L coordinates to develop the electron and proton flux models. The flux predictions of the new model were used to estimate the total ionizing dose (TID) rate along the Neptunian equator, meridional flux contours for the electrons and protons, and for flux and dose comparisons with the other radiation belts in the Solar System.

  16. Atmospheric, Ionospheric, and Energetic Radiation Environments of Saturn's Rings

    Science.gov (United States)

    Cooper, J. F.; Kollmann, P.; Sittler, E. C., Jr.; Johnson, R. E.; Sturner, S. J.

    2015-12-01

    Planetary magnetospheric and high-energy cosmic ray interactions with Saturn's rings were first explored in-situ during the Pioneer 11 flyby in 1979. The following Voyager flybys produced a wealth of new information on ring structure and mass, and on spatial structure of the radiation belts beyond the main rings. Next came the Cassini Orbiter flyover of the rings during Saturn Orbital Insertion in 2004 with the first in-situ measurements of the ring atmosphere and plasma ionosphere. Cassini has since fully explored the radiation belt and magnetospheric plasma region beyond the main rings, discovering how Enceladus acts as a source of water group neutrals and water ions for the ion plasma. But do the main rings also substantially contribute by UV photolysis to water group plasma (H+, O+, OH+, H2O+, H3O+, O2+) and neutrals inwards from Enceladus? More massive rings, than earlier inferred from Pioneer 11 and Voyager observations, would further contribute by bulk ring ice radiolysis from interactions of galactic cosmic ray particles. Products of these interactions include neutron-decay proton and electron injection into the radiation belts beyond the main rings. How does radiolysis from moon and ring sweeping of the radiation belt particles compare with direct gas and plasma sources from the main rings and Enceladus? Can the magnetospheric ion and electron populations reasonably be accounted for by the sum of the ring-neutron-decay and outer magnetospheric inputs? Pioneer 11 made the deepest radial penetration into the C-ring, next followed by Cassini SOI. What might Cassini's higher-inclination proximal orbits reveal about the atmospheric, ionospheric, and energetic radiation environments in the D-ring and the proximal gap region? Recent modeling predicts a lower-intensity innermost radiation belt extending from the gap to the inner D-ring. Other remaining questions include the lifetimes of narrow and diffuse dust rings with respect to plasma and energetic particle

  17. Designing Equipment for Use in Gamma Radiation Environments

    Energy Technology Data Exchange (ETDEWEB)

    Vandergriff, K.U.

    1990-01-01

    High levels of gamma radiation are known to cause degradation in a variety of materials and components. When designing systems to operate in a high radiation environment, special precautions and procedures should be followed. This report (1) outlines steps that should be followed in designing equipment and (2) explains the general effects of radiation on various engineering materials and components. Much information exists in the literature on radiation effects upon materials. However, very little information is available to give the designer a step-by-step process for designing systems that will be subject to high levels of gamma radiation, such as those found in a nuclear fuel reprocessing facility. In this report, many radiation effect references are relied upon to aid in the design of components and systems.

  18. Research on environment monitoring of radiation emergency

    CERN Document Server

    Ito, Y; Otani, N

    2003-01-01

    In a case of a nuclear accident at nuclear facilities, strong radiation such as g-rays and neutrons might radiate at a burst in the initial stage. For the establishment of dose estimation system for such accidents, the experiments were done using the He sup + sup 2 beam accelerated by Tandem in the W-MAST. The following results were obtained. 1) Neutron measurements using a rem counter yielded that dose equivalent was about 9.4 mSv/h at a position 100 cm from the Be target when the beam current of 15 MeV He sup 2 sup + was 0.8 mu A. Neutron measurement by means of Au and In foil activation method and by use of TLD element revealed that dose equivalents were to be 16-27 mu Sv/h for thermal neutron, and 30-41 mu Sv/h for sub-fast neutron (20 keV). Therefore, it was concluded that neutron field was mainly composed by fast neutron. 2) Linearity of the rem-counter out put vs neutron flux was valid under the condition that the count rate of the rem-counter was less than 10 kcps. 3) Computer simulation using NRESP c...

  19. Research on environment monitoring of radiation emergency

    CERN Document Server

    Ito, Y

    2002-01-01

    In a case of a nuclear accident at nuclear facilities, radiation such as gamma-rays and neutrons might radiate at a burst in the initial stage. For the establishment of dose estimation system for such accidents, the experiments were carried out using the Tandem/Synchrotron accelerator. The following results were obtained: (1) Measurements of the gamma-ray emission using the NaI detector together with pile up rejection system revealed that the good signals without the pile up phenomena could be obtained in case of count rate less than 7 kc/s. On assumption that energy distribution function of the gamma-rays was proportional to be E exp(- E/T sub e sub f sub f), the effective temperature T sub e sub f sub f was estimated to be 0.8 - 0.9 MeV by use of non-linear least squares. (2) Doses of gamma-rays were measured using the TLD elements shielded by Pb sheets with various widths. The effective temperature T sub e sub f sub f estimated under the same experimental conditions described in (1) was 0.6-3 MeV. In an ac...

  20. The development of advanced robotics technology in high radiation environment

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yong Bum; Cho, Jaiwan; Lee, Nam Ho; Choi, Young Soo; Park, Soon Yong; Lee, Jong Min; Park, Jin Suk; Kim, Seung Ho; Kim, Byung Soo; Moon, Byung Soo

    1997-07-01

    In the tele-operation technology using tele-presence in high radiation environment, stereo vision target tracking by centroid method, vergence control of stereo camera by moving vector method, stereo observing system by correlation method, horizontal moving axis stereo camera, and 3 dimensional information acquisition by stereo image is developed. Also, gesture image acquisition by computer vision and construction of virtual environment for remote work in nuclear power plant. In the development of intelligent control and monitoring technology for tele-robot in hazardous environment, the characteristics and principle of robot operation. And, robot end-effector tracking algorithm by centroid method and neural network method are developed for the observation and survey in hazardous environment. 3-dimensional information acquisition algorithm by structured light is developed. In the development of radiation hardened sensor technology, radiation-hardened camera module is designed and tested. And radiation characteristics of electric components is robot system is evaluated. Also 2-dimensional radiation monitoring system is developed. These advanced critical robot technology and telepresence techniques developed in this project can be applied to nozzle-dam installation /removal robot system, can be used to realize unmanned remotelization of nozzle-dam installation / removal task in steam generator of nuclear power plant, which can be contributed for people involved in extremely hazardous high radioactivity area to eliminate their exposure to radiation, enhance their task safety, and raise their working efficiency. (author). 75 refs., 21 tabs., 15 figs.

  1. Inclusion of Radiation Environment Variability in Total Dose Hardness Assurance Methodology

    Science.gov (United States)

    Xapsos, M. A.; Stauffer, C.; Phan, A.; McClure, S. S.; Ladbury, R. L.; Pellish, J. A.; Campola, M. J.; LaBel, K. A.

    2015-01-01

    Variability of the space radiation environment is investigated with regard to parts categorization for total dose hardness assurance methods. It is shown that it can have a significant impact. A modified approach is developed that uses current environment models more consistently and replaces the design margin concept with one of failure probability.

  2. Radiation Belt Modeling for Spacecraft Design: Model Comparisons for Common Orbits

    Science.gov (United States)

    Lauenstein, J.-M.; Barth, J. L.

    2005-01-01

    We present the current status of radiation belt modeling, providing model details and comparisons with AP-8 and AE-8 for commonly used orbits. Improved modeling of the particle environment enables smarter space system design.

  3. Simulation and analysis of antennas radiating in a complex environment

    Science.gov (United States)

    Kim, J. J.; Burnside, W. D.

    1986-01-01

    A numerical procedure for computing the high-frequency radiation patterns of antennas mounted on curved surfaces is described. The procedure utilizes the uniform geometrical theory of diffraction to examine the antenna system's performance, which is dependent on antenna radiation patterns. Composite ellipsoid models of fuselage shapes are developed and the formation of geodesic paths on the models is studied; the shape of the fuselage affects the radiation patterns. The actual field radiated by the source and scattered by the structure is calculated using the ray field technique. The numerical solution is applied to the analysis of the antenna radiation patterns of a military aircraft, private aircraft, and the Space Shuttle orbiter. Good correlation between the calculated and measured radiation patterns is noted verifying the usefulness and accuracy of the numerical procedure.

  4. Radiative shocks create environments for dust formation in classical novae

    Science.gov (United States)

    Derdzinski, Andrea M.; Metzger, Brian D.; Lazzati, Davide

    2017-08-01

    Classical novae commonly show evidence of rapid dust formation within months of the outburst. However, it is unclear how molecules and grains are able to condense within the ejecta, given the potentially harsh environment created by ionizing radiation from the white dwarf. Motivated by the evidence for powerful radiative shocks within nova outflows, we propose that dust formation occurs within the cool, dense shell behind these shocks. We incorporate a simple molecular chemistry network and classical nucleation theory with a model for the thermodynamic evolution of the post-shock gas, in order to demonstrate the formation of both carbon and forsterite (Mg2SiO4) grains. The high densities due to radiative shock compression (n ∼ 1014 cm-3) result in CO saturation and rapid dust nucleation. Grains grow efficiently to large sizes ≳ 0.1 μm, in agreement with IR observations of dust-producing novae, and with total dust masses sufficient to explain massive extinction events such as V705 Cas. As in dense stellar winds, dust formation is CO-regulated, with carbon-rich flows producing carbon-rich grains and oxygen-rich flows primarily forming silicates. CO is destroyed by non-thermal particles accelerated at the shock, allowing additional grain formation at late times, but the efficiency of this process appears to be low. Given observations showing that individual novae produce both carbonaceous and silicate grains, we concur with previous works attributing this bimodality to chemical heterogeneity of the ejecta. Nova outflows are diverse and inhomogeneous, and the observed variety of dust formation events can be reconciled by different abundances, the range of shock properties, and the observer viewing angle. The latter may govern the magnitude of extinction, with the deepest extinction events occurring for observers within the binary equatorial plane.

  5. Monte Carlo simulations of the radiation environment for the CMS Experiment

    CERN Document Server

    Mallows, Sophie

    2015-01-01

    Monte Carlo radiation transport codes are used by the CMS Beam Radiation Instrumentation and Luminosity (BRIL) project to estimate the radiation levels due to proton-proton collisions and machine induced background. Results are used by the CMS collaboration for various applications: comparison with detector hit rates, pile-up studies, predictions of radiation damage based on various models (Dose, NIEL, DPA), shielding design, estimations of residual dose environment. Simulation parameters, and the maintenance of the input files are summarised, and key results are presented. Furthermore, an overview of additional programs developed by the BRIL project to meet the specific needs of CMS community is given.

  6. Monte Carlo simulations of the radiation environment for the CMS experiment

    Energy Technology Data Exchange (ETDEWEB)

    Mallows, S., E-mail: sophie.mallows@cern.ch [KIT, Karlsruhe (Germany); Azhgirey, I.; Bayshev, I. [IHEP, Protvino (Russian Federation); Bergstrom, I.; Cooijmans, T.; Dabrowski, A.; Glöggler, L.; Guthoff, M. [CERN, Geneva (Switzerland); Kurochkin, I. [IHEP, Protvino (Russian Federation); Vincke, H.; Tajeda, S. [CERN, Geneva (Switzerland)

    2016-07-11

    Monte Carlo radiation transport codes are used by the CMS Beam Radiation Instrumentation and Luminosity (BRIL) project to estimate the radiation levels due to proton–proton collisions and machine induced background. Results are used by the CMS collaboration for various applications: comparison with detector hit rates, pile-up studies, predictions of radiation damage based on various models (Dose, NIEL, DPA), shielding design, estimations of residual dose environment. Simulation parameters, and the maintenance of the input files are summarized, and key results are presented. Furthermore, an overview of additional programs developed by the BRIL project to meet the specific needs of CMS community is given.

  7. Using Space Weather Variability in Evaluating the Radiation Environment Design Specifications for NASA's Constellation Program

    Science.gov (United States)

    Coffey, Victoria N.; Blackwell, William C.; Minow, Joseph I.; Bruce, Margaret B.; Howard, James W.

    2007-01-01

    NASA's Constellation program, initiated to fulfill the Vision for Space Exploration, will create a new generation of vehicles for servicing low Earth orbit, the Moon, and beyond. Space radiation specifications for space system hardware are necessarily conservative to assure system robustness for a wide range of space environments. Spectral models of solar particle events and trapped radiation belt environments are used to develop the design requirements for estimating total ionizing radiation dose, displacement damage, and single event effects for Constellation hardware. We first describe the rationale using the spectra chosen to establish the total dose and single event design environmental specifications for Constellation systems. We then compare variability of the space environment to the spectral design models to evaluate their applicability as conservative design environments and potential vulnerabilities to extreme space weather events

  8. Status Report of Simulated Space Radiation Environment Facility

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Phil Hyun; Nho, Young Chang; Jeun, Joon Pyo; Choi, Jae Hak; Lim, Youn Mook; Jung, Chan Hee; Jeon, Young Kyu

    2007-11-15

    The technology for performance testing and improvement of materials which are durable at space environment is a military related technology and veiled and securely regulated in advanced countries such as US and Russia. This core technology cannot be easily transferred to other country too. Therefore, this technology is the most fundamental and necessary research area for the successful establishment of space environment system. Since the task for evaluating the effects of space materials and components by space radiation plays important role in satellite lifetime extension and running failure percentage decrease, it is necessary to establish simulated space radiation facility and systematic testing procedure. This report has dealt with the status of the technology to enable the simulation of space environment effects, including the effect of space radiation on space materials. This information such as the fundamental knowledge of space environment and research status of various countries as to the simulation of space environment effects of space materials will be useful for the research on radiation hardiness of the materials. Furthermore, it will be helpful for developer of space material on deriving a better choice of materials, reducing the design cycle time, and improving safety.

  9. Assessment of radiation awareness training in immersive virtual environments

    Science.gov (United States)

    Whisker, Vaughn E., III

    The prospect of new nuclear power plant orders in the near future and the graying of the current workforce create a need to train new personnel faster and better. Immersive virtual reality (VR) may offer a solution to the training challenge. VR technology presented in a CAVE Automatic Virtual Environment (CAVE) provides a high-fidelity, one-to-one scale environment where areas of the power plant can be recreated and virtual radiation environments can be simulated, making it possible to safely expose workers to virtual radiation in the context of the actual work environment. The use of virtual reality for training is supported by many educational theories; constructivism and discovery learning, in particular. Educational theory describes the importance of matching the training to the task. Plant access training and radiation worker training, common forms of training in the nuclear industry, rely on computer-based training methods in most cases, which effectively transfer declarative knowledge, but are poor at transferring skills. If an activity were to be added, the training would provide personnel with the opportunity to develop skills and apply their knowledge so they could be more effective when working in the radiation environment. An experiment was developed to test immersive virtual reality's suitability for training radiation awareness. Using a mixed methodology of quantitative and qualitative measures, the subjects' performances before and after training were assessed. First, subjects completed a pre-test to measure their knowledge prior to completing any training. Next they completed unsupervised computer-based training, which consisted of a PowerPoint presentation and a PDF document. After completing a brief orientation activity in the virtual environment, one group of participants received supplemental radiation awareness training in a simulated radiation environment presented in the CAVE, while a second group, the control group, moved directly to the

  10. Mars' surface radiation environment measured with the Mars Science Laboratory's Curiosity rover.

    Science.gov (United States)

    Hassler, Donald M; Zeitlin, Cary; Wimmer-Schweingruber, Robert F; Ehresmann, Bent; Rafkin, Scot; Eigenbrode, Jennifer L; Brinza, David E; Weigle, Gerald; Böttcher, Stephan; Böhm, Eckart; Burmeister, Soenke; Guo, Jingnan; Köhler, Jan; Martin, Cesar; Reitz, Guenther; Cucinotta, Francis A; Kim, Myung-Hee; Grinspoon, David; Bullock, Mark A; Posner, Arik; Gómez-Elvira, Javier; Vasavada, Ashwin; Grotzinger, John P

    2014-01-24

    The Radiation Assessment Detector (RAD) on the Mars Science Laboratory's Curiosity rover began making detailed measurements of the cosmic ray and energetic particle radiation environment on the surface of Mars on 7 August 2012. We report and discuss measurements of the absorbed dose and dose equivalent from galactic cosmic rays and solar energetic particles on the martian surface for ~300 days of observations during the current solar maximum. These measurements provide insight into the radiation hazards associated with a human mission to the surface of Mars and provide an anchor point with which to model the subsurface radiation environment, with implications for microbial survival times of any possible extant or past life, as well as for the preservation of potential organic biosignatures of the ancient martian environment.

  11. ISS Radiation Shielding and Acoustic Simulation Using an Immersive Environment

    Science.gov (United States)

    Verhage, Joshua E.; Sandridge, Chris A.; Qualls, Garry D.; Rizzi, Stephen A.

    2002-01-01

    The International Space Station Environment Simulator (ISSES) is a virtual reality application that uses high-performance computing, graphics, and audio rendering to simulate the radiation and acoustic environments of the International Space Station (ISS). This CAVE application allows the user to maneuver to different locations inside or outside of the ISS and interactively compute and display the radiation dose at a point. The directional dose data is displayed as a color-mapped sphere that indicates the relative levels of radiation from all directions about the center of the sphere. The noise environment is rendered in real time over headphones or speakers and includes non-spatial background noise, such as air-handling equipment, and spatial sounds associated with specific equipment racks, such as compressors or fans. Changes can be made to equipment rack locations that produce changes in both the radiation shielding and system noise. The ISSES application allows for interactive investigation and collaborative trade studies between radiation shielding and noise for crew safety and comfort.

  12. Wireless Communication Enhancement Methods for Mobile Robots in Radiation Environments

    CERN Document Server

    Nattanmai Parasuraman, Ramviyas; Ferre, Manuel

    In hostile environments such as in scientific facilities where ionising radiation is a dominant hazard, reducing human interventions by increasing robotic operations are desirable. CERN, the European Organization for Nuclear Research, has around 50 km of underground scientific facilities, where wireless mobile robots could help in the operation of the accelerator complex, e.g. in conducting remote inspections and radiation surveys in different areas. The main challenges to be considered here are not only that the robots should be able to go over long distances and operate for relatively long periods, but also the underground tunnel environment, the possible presence of electromagnetic fields, radiation effects, and the fact that the robots shall in no way interrupt the operation of the accelerators. Having a reliable and robust wireless communication system is essential for successful execution of such robotic missions and to avoid situations of manual recovery of the robots in the event that the robot runs ...

  13. Three keys to the radiation of angiosperms into freezing environments.

    Science.gov (United States)

    Zanne, Amy E; Tank, David C; Cornwell, William K; Eastman, Jonathan M; Smith, Stephen A; FitzJohn, Richard G; McGlinn, Daniel J; O'Meara, Brian C; Moles, Angela T; Reich, Peter B; Royer, Dana L; Soltis, Douglas E; Stevens, Peter F; Westoby, Mark; Wright, Ian J; Aarssen, Lonnie; Bertin, Robert I; Calaminus, Andre; Govaerts, Rafaël; Hemmings, Frank; Leishman, Michelle R; Oleksyn, Jacek; Soltis, Pamela S; Swenson, Nathan G; Warman, Laura; Beaulieu, Jeremy M

    2014-02-06

    Early flowering plants are thought to have been woody species restricted to warm habitats. This lineage has since radiated into almost every climate, with manifold growth forms. As angiosperms spread and climate changed, they evolved mechanisms to cope with episodic freezing. To explore the evolution of traits underpinning the ability to persist in freezing conditions, we assembled a large species-level database of growth habit (woody or herbaceous; 49,064 species), as well as leaf phenology (evergreen or deciduous), diameter of hydraulic conduits (that is, xylem vessels and tracheids) and climate occupancies (exposure to freezing). To model the evolution of species' traits and climate occupancies, we combined these data with an unparalleled dated molecular phylogeny (32,223 species) for land plants. Here we show that woody clades successfully moved into freezing-prone environments by either possessing transport networks of small safe conduits and/or shutting down hydraulic function by dropping leaves during freezing. Herbaceous species largely avoided freezing periods by senescing cheaply constructed aboveground tissue. Growth habit has long been considered labile, but we find that growth habit was less labile than climate occupancy. Additionally, freezing environments were largely filled by lineages that had already become herbs or, when remaining woody, already had small conduits (that is, the trait evolved before the climate occupancy). By contrast, most deciduous woody lineages had an evolutionary shift to seasonally shedding their leaves only after exposure to freezing (that is, the climate occupancy evolved before the trait). For angiosperms to inhabit novel cold environments they had to gain new structural and functional trait solutions; our results suggest that many of these solutions were probably acquired before their foray into the cold.

  14. Travel for the 2004 American Statistical Association Biannual Radiation Meeting: "Radiation in Realistic Environments: Interactions Between Radiation and Other Factors

    Energy Technology Data Exchange (ETDEWEB)

    Brenner, David J.

    2009-07-21

    The 16th ASA Conference on Radiation and Health, held June 27-30, 2004 in Beaver Creek, CO, offered a unique forum for discussing research related to the effects of radiation exposures on human health in a multidisciplinary setting. The Conference furnishes investigators in health related disciplines the opportunity to learn about new quantitative approaches to their problems and furnishes statisticians the opportunity to learn about new applications for their discipline. The Conference was attended by about 60 scientists including statisticians, epidemiologists, biologists and physicists interested in radiation research. For the first time, ten recipients of Young Investigator Awards participated in the conference. The Conference began with a debate on the question: “Do radiation doses below 1 cGy increase cancer risks?” The keynote speaker was Dr. Martin Lavin, who gave a banquet presentation on the timely topic “How important is ATM?” The focus of the 2004 Conference on Radiation and Health was Radiation in Realistic Environments: Interactions Between Radiation and Other Risk Modifiers. The sessions of the conference included: Radiation, Smoking, and Lung Cancer Interactions of Radiation with Genetic Factors: ATM Radiation, Genetics, and Epigenetics Radiotherapeutic Interactions The Conference on Radiation and Health is held bi-annually, and participants are looking forward to the 17th conference to be held in 2006.

  15. International Space Station Radiation Shielding Model Development

    Science.gov (United States)

    Qualls, G. D.; Wilson, J. W.; Sandridge, C.; Cucinotta, F. A.; Nealy, J. E.; Heinbockel, J. H.; Hugger, C. P.; Verhage, J.; Anderson, B. M.; Atwell, W.

    2001-01-01

    The projected radiation levels within the International Space Station (ISS) have been criticized by the Aerospace Safety Advisory Panel in their report to the NASA Administrator. Methods for optimal reconfiguration and augmentation of the ISS shielding are now being developed. The initial steps are to develop reconfigurable and realistic radiation shield models of the ISS modules, develop computational procedures for the highly anisotropic radiation environment, and implement parametric and organizational optimization procedures. The targets of the redesign process are the crew quarters where the astronauts sleep and determining the effects of ISS shadow shielding of an astronaut in a spacesuit. The ISS model as developed will be reconfigurable to follow the ISS. Swapping internal equipment rack assemblies via location mapping tables will be one option for shield optimization. Lightweight shield augmentation materials will be optimally fit to crew quarter areas using parametric optimization procedures to minimize the augmentation shield mass. The optimization process is being integrated into the Intelligence Synthesis Environment s (ISE s) immersive simulation facility at the Langley Research Center and will rely on High Performance Computing and Communication (HPCC) for rapid evaluation of shield parameter gradients.

  16. Simulating protostellar evolution and radiative feedback in the cluster environment

    CERN Document Server

    Klassen, Mikhail; Peters, Thomas

    2011-01-01

    Radiative feedback is among the most important consequences of clustered star formation inside molecular clouds. At the onset of star formation, radiation from massive stars heats the surrounding gas, which suppresses the formation of many low-mass stars. When simulating pre-main-sequence stars, their stellar properties must be defined by a prestellar model. Different approaches to prestellar modeling may yield quantitatively different results. In this paper, we compare two existing prestellar models under identical initial conditions to gauge whether the choice of model has any significant effects on the final population of stars. The first model treats stellar radii and luminosities with a ZAMS model, while separately estimating the accretion luminosity by interpolating to published prestellar tracks. The second, more accurate prestellar model self-consistently evolves the radius and luminosity of each star under highly variable accretion conditions. Each is coupled to a raytracing-based radiative feedback ...

  17. Adaptation of radiation shielding code to space environment

    Energy Technology Data Exchange (ETDEWEB)

    Okuno, Koichi; Hara, Akihisa (Hazama Corp., Tokyo (Japan))

    1992-12-01

    Recently, the trend to the development of space has heightened. To the development of space, many problems are related, and as one of them, there is the protection from cosmic ray. The cosmic ray is the radiation having ultrahigh energy, and there was not the radiation shielding design code that copes with cosmic ray so far. Therefore, the high energy radiation shielding design code for accelerators was improved so as to cope with the peculiarity that cosmic ray possesses. Moreover, the calculation of the radiation dose equivalent rate in the moon base to which the countermeasures against cosmic ray were taken was simulated by using the improved code. As the important countermeasures for the safety protection from radiation, the covering with regolith is carried out, and the effect of regolith was confirmed by using the improved code. Galactic cosmic ray, solar flare particles, radiation belt, the adaptation of the radiation shielding code HERMES to space environment, the improvement of the three-dimensional hadron cascade code HETCKFA-2 and the electromagnetic cascade code EGS 4-KFA, and the cosmic ray simulation are reported. (K.I.).

  18. Local Heliospheric and Interstellar Radiation Environment of Planet X

    Science.gov (United States)

    Cooper, John

    2017-01-01

    The orbit and aphelion direction of the putative Planet X at mass 10 ME has been inferred earlier from orbital modeling of Sedna and other distant Kuiper Belt Objects. The centroid of possible aphelion locations at 103 AU lies within the heliotail potentially extending thousands of AU downstream from the direction of interstellar neutral flow into the heliosphere. The only spacecraft now heading in that general direction is Pioneer 10, long silent since last contact in January 2003 at 82 AU from the Sun. The Interstellar Background Explorer (IBEX) has from Earth orbit, however, been mapping energetic neutral atom (ENA) emissions from the outer heliosphere, including in the heliotail direction. Angular resolutions of the IBEX ENA maps are too coarse to resolve Planet X itself but could inform on larger-scale particle flux environments of distant objects within the heliotail. Present Voyager 1 energetic particle measurements in the outer heliosheath will eventually be joined by Voyager 2 bulk plasma measurements at ion energies below 10 keV for more complete characterization of particle flux distributions. These distributions can then be used to model external radiation interactions with the more distant objects of our solar system, potentially including Planet X.

  19. Basic mechanisms of radiation effects in the natural space radiation environment

    Energy Technology Data Exchange (ETDEWEB)

    Schwank, J.R.

    1994-06-01

    Four general topics are covered in respect to the natural space radiation environment: (1) particles trapped by the earth`s magnetic field, (2) cosmic rays, (3) radiation environment inside a spacecraft, (4) laboratory radiation sources. The interaction of radiation with materials is described by ionization effects and displacement effects. Total-dose effects on MOS devices is discussed with respect to: measurement techniques, electron-hole yield, hole transport, oxide traps, interface traps, border traps, device properties, case studies and special concerns for commercial devices. Other device types considered for total-dose effects are SOI devices and nitrided oxide devices. Lastly, single event phenomena are discussed with respect to charge collection mechanisms and hard errors. (GHH)

  20. The radiation environment in Sweden; Straalmiljoen i Sverige

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, Paal; Carlsson, Monica; Falk, Rolf; Hubbard, Lynn; Leitz, Wolfram; Mjoenes, Lars; Moere, Hans; Nyblom, Leif; Soederman, Ann-Louise; Yuen Lasson, Katarina; Aakerblom, Gustav; Oehlen, Elisabeth

    2007-01-15

    The report describes, and reports data from, the monitoring of the radiation environment which has been conducted in Sweden since the 1950s. Average doses to the general public as well as to special groups of the public are also reported. Environmental monitoring concerning radiation has to a great extent focused on deposition and occurrence of radioactive elements originating from the atmospheric nuclear weapon tests and the Chernobyl accident. The average dose from {sup 137}Cs is very low, although it is somewhat higher in the group 'reindeer herders'. Surveys of naturally occurring radioactive elements in soil, drinking water and indoor air show that radiation from soil and building materials constitutes, besides medical use of radiation, the main part of the average total dose to the population. The dose from drinking water from drilled wells or from radon in indoor air may dominate the total dose in certain cases. Smoking increases the risk of radon considerably. UV-radiation has increased with 10 percent over the last 22 years at the location of the monitoring station. This is mainly explained by a decreased cloudiness. The exposure for UV is however more dependent on behaviour, and approximately 25 percent of the total exposure takes place abroad. Presently there are no time series concerning electromagnetic fields in the outdoor environment. However, measurements indicate levels well below the reference values.

  1. Radiation Belt Storm Probes—Observatory and Environments

    Science.gov (United States)

    Kirby, Karen; Artis, David; Bushman, Stewart; Butler, Michael; Conde, Rich; Cooper, Stan; Fretz, Kristen; Herrmann, Carl; Hill, Adrian; Kelley, Jeff; Maurer, Richard; Nichols, Richard; Ottman, Geffrey; Reid, Mark; Rogers, Gabe; Srinivasan, Dipak; Troll, John; Williams, Bruce

    2013-11-01

    The National Aeronautics and Space Administration's (NASA's) Radiation Belt Storm Probe (RBSP) is an Earth-orbiting mission that launched August 30, 2012, and is the latest science mission in NASA's Living with a Star Program. The RBSP mission will investigate, characterize and understand the physical dynamics of the radiation belts, as well as the influence of the Sun on the Earth's environment, by measuring particles, electric and magnetic fields and waves that comprise geospace. The mission is composed of two identically instrumented spinning observatories in an elliptical orbit around earth with 600 km perigee, 30,000 km apogee and 10∘ inclination to provide full sampling of the Van Allen radiation belts. The twin RBSP observatories (recently renamed the Van Allen Probes) will follow slightly different orbits and will lap each other four times per year, offering simultaneous measurements over a range of observatory separation distances. A description of the observatory environment is provided along with protection for sensitive electronics to support operations in the harsh radiation belt environment. Spacecraft and subsystem key characteristics and instrument accommodations are included that allow the RBSP science objectives to be met.

  2. Combined injury syndrome in space-related radiation environments

    Science.gov (United States)

    Dons, R. F.; Fohlmeister, U.

    The risk of combined injury (CI) to space travelers is a function of exposure to anomalously large surges of a broad spectrum of particulate and photon radiations, conventional trauma (T), and effects of weightlessness including decreased intravascular fluid volume, and myocardial deconditioning. CI may occur even at relatively low doses of radiation which can synergistically enhance morbidity and mortality from T. Without effective countermeasures, prolonged residence in space is expected to predispose most individuals to bone fractures as a result of calcium loss in the microgravity environment. Immune dysfunction may occur from residence in space independent of radiation exposure. Thus, wound healing would be compromised if infection were to occur. Survival of the space traveler with CI would be significantly compromised if there were delays in wound closure or in the application of simple supportive medical or surgical therapies. Particulate radiation has the potential for causing greater gastrointestinal injury than photon radiation, but bone healing should not be compromised at the expected doses of either type of radiation in space.

  3. RADIATION ENVIRONMENT, ORGANIZATION AND PROVIDING OF POPULATION RADIATION PROTECTION CONTROL IN ST. PETBURG

    Directory of Open Access Journals (Sweden)

    I. A. Rakitin

    2008-01-01

    Full Text Available The article presents the analysis of radiation environment and work experience of Rospotrebnadzor Administration in St. Petersburg in the field of organizing of population radiation protection control and interaction with the local government executive bodies. It shows the level and structure of the city population collective doses from the main dose forming ionizing irradiation sources. It emphasizes the integrated method of solving the population exposure limitation issues based on the results of radiation-hygienic passport system and on the data from Uniform State System for Doses Control and Registration. The evaluation of the work being carried out is given.

  4. Inner Radiation Belt Representation of the Energetic Electron Environment: Model and Data Synthesis Using the Salammbo Radiation Belt Transport Code and Los Alamos Geosynchronous and GPS Energetic Particle Data

    Science.gov (United States)

    Friedel, R. H. W.; Bourdarie, S.; Fennell, J.; Kanekal, S.; Cayton, T. E.

    2004-01-01

    The highly energetic electron environment in the inner magnetosphere (GEO inward) has received a lot of research attention in resent years, as the dynamics of relativistic electron acceleration and transport are not yet fully understood. These electrons can cause deep dielectric charging in any space hardware in the MEO to GEO region. We use a new and novel approach to obtain a global representation of the inner magnetospheric energetic electron environment, which can reproduce the absolute environment (flux) for any spacecraft orbit in that region to within a factor of 2 for the energy range of 100 KeV to 5 MeV electrons, for any levels of magnetospheric activity. We combine the extensive set of inner magnetospheric energetic electron observations available at Los Alamos with the physics based Salammbo transport code, using the data assimilation technique of "nudging". This in effect input in-situ data into the code and allows the diffusion mechanisms in the code to interpolate the data into regions and times of no data availability. We present here details of the methods used, both in the data assimilation process and in the necessary inter-calibration of the input data used. We will present sample runs of the model/data code and compare the results to test spacecraft data not used in the data assimilation process.

  5. A Monte Carlo transport code study of the space radiation environment using FLUKA and ROOT

    CERN Document Server

    Wilson, T; Carminati, F; Brun, R; Ferrari, A; Sala, P; Empl, A; MacGibbon, J

    2001-01-01

    We report on the progress of a current study aimed at developing a state-of-the-art Monte-Carlo computer simulation of the space radiation environment using advanced computer software techniques recently available at CERN, the European Laboratory for Particle Physics in Geneva, Switzerland. By taking the next-generation computer software appearing at CERN and adapting it to known problems in the implementation of space exploration strategies, this research is identifying changes necessary to bring these two advanced technologies together. The radiation transport tool being developed is tailored to the problem of taking measured space radiation fluxes impinging on the geometry of any particular spacecraft or planetary habitat and simulating the evolution of that flux through an accurate model of the spacecraft material. The simulation uses the latest known results in low-energy and high-energy physics. The output is a prediction of the detailed nature of the radiation environment experienced in space as well a...

  6. Comparison of the performance of net radiation calculation models

    DEFF Research Database (Denmark)

    Kjærsgaard, Jeppe Hvelplund; Cuenca, R H; Martinez-Cob, A

    2009-01-01

    values of net radiation were calculated using three net outgoing long-wave radiation models and compared to measured values. Four meteorological datasets representing two climate regimes, a sub-humid, high-latitude environment and a semi-arid mid-latitude environment, were used to test the models...... meteorological input data is limited. Model predictions were found to have a higher bias and scatter when using summed calculated hourly time steps compared to using daily input data.......Daily values of net radiation are used in many applications of crop-growth modeling and agricultural water management. Measurements of net radiation are not part of the routine measurement program at many weather stations and are commonly estimated based on other meteorological parameters. Daily...

  7. A virtual environment for medical radiation collaborative learning.

    Science.gov (United States)

    Bridge, Pete; Trapp, Jamie V; Kastanis, Lazaros; Pack, Darren; Parker, Jacqui C

    2015-06-01

    A software-based environment was developed to provide practical training in medical radiation principles and safety. The Virtual Radiation Laboratory application allowed students to conduct virtual experiments using simulated diagnostic and radiotherapy X-ray generators. The experiments were designed to teach students about the inverse square law, half value layer and radiation protection measures and utilised genuine clinical and experimental data. Evaluation of the application was conducted in order to ascertain the impact of the software on students' understanding, satisfaction and collaborative learning skills and also to determine potential further improvements to the software and guidelines for its continued use. Feedback was gathered via an anonymous online survey consisting of a mixture of Likert-style questions and short answer open questions. Student feedback was highly positive with 80 % of students reporting increased understanding of radiation protection principles. Furthermore 72 % enjoyed using the software and 87 % of students felt that the project facilitated collaboration within small groups. The main themes arising in the qualitative feedback comments related to efficiency and effectiveness of teaching, safety of environment, collaboration and realism. Staff and students both report gains in efficiency and effectiveness associated with the virtual experiments. In addition students particularly value the visualisation of "invisible" physical principles and increased opportunity for experimentation and collaborative problem-based learning. Similar ventures will benefit from adopting an approach that allows for individual experimentation while visualizing challenging concepts.

  8. The radiation environment in underground workplaces of the LHC

    CERN Document Server

    Theis, C; Kindl, Peter

    2007-01-01

    Active dose-monitoring of workplaces is crucial in order to operate a high-energy particle accelerator safely. As the mixed radiation fields that are expected in the environment of the Large Hadron Collider (LHC) are very different from standard use-cases like in nuclear power plants, it is of highest importance to characterize and calibrate radiation monitoring equipment appropriately for their use in high energy mixed radiation fields. Due to their sensitivity to different particle types over a larger energy range high-pressure ionization chambers have already been used at CERN and they are foreseen to be included within the radiation monitoring system of the LHC. In the framework of this thesis a new method was developed which allows for appropriate field-specific calibration of these detectors using Monte Carlo simulations. Therefore, the application of common 238Pu-Be source based calibration in mixed radiation fields was studied and compared to more accurate field specific calibration based on FLUKA Mon...

  9. Methodology for estimating radiation dose rates to freshwater biota exposed to radionuclides in the environment

    Energy Technology Data Exchange (ETDEWEB)

    Blaylock, B.G.; Frank, M.L.; O`Neal, B.R.

    1993-08-01

    The purpose of this report is to present a methodology for evaluating the potential for aquatic biota to incur effects from exposure to chronic low-level radiation in the environment. Aquatic organisms inhabiting an environment contaminated with radioactivity receive external radiation from radionuclides in water, sediment, and from other biota such as vegetation. Aquatic organisms receive internal radiation from radionuclides ingested via food and water and, in some cases, from radionuclides absorbed through the skin and respiratory organs. Dose rate equations, which have been developed previously, are presented for estimating the radiation dose rate to representative aquatic organisms from alpha, beta, and gamma irradiation from external and internal sources. Tables containing parameter values for calculating radiation doses from selected alpha, beta, and gamma emitters are presented in the appendix to facilitate dose rate calculations. The risk of detrimental effects to aquatic biota from radiation exposure is evaluated by comparing the calculated radiation dose rate to biota to the U.S. Department of Energy`s (DOE`s) recommended dose rate limit of 0.4 mGy h{sup {minus}1} (1 rad d{sup {minus}1}). A dose rate no greater than 0.4 mGy h{sup {minus}1} to the most sensitive organisms should ensure the protection of populations of aquatic organisms. DOE`s recommended dose rate is based on a number of published reviews on the effects of radiation on aquatic organisms that are summarized in the National Council on Radiation Protection and Measurements Report No. 109 (NCRP 1991). DOE recommends that if the results of radiological models or dosimetric measurements indicate that a radiation dose rate of 0. 1 mGy h{sup {minus}1} will be exceeded, then a more detailed evaluation of the potential ecological consequences of radiation exposure to endemic populations should be conducted.

  10. Methodology for estimating radiation dose rates to freshwater biota exposed to radionuclides in the environment

    Energy Technology Data Exchange (ETDEWEB)

    Blaylock, B.G.; Frank, M.L.; O`Neal, B.R.

    1993-08-01

    The purpose of this report is to present a methodology for evaluating the potential for aquatic biota to incur effects from exposure to chronic low-level radiation in the environment. Aquatic organisms inhabiting an environment contaminated with radioactivity receive external radiation from radionuclides in water, sediment, and from other biota such as vegetation. Aquatic organisms receive internal radiation from radionuclides ingested via food and water and, in some cases, from radionuclides absorbed through the skin and respiratory organs. Dose rate equations, which have been developed previously, are presented for estimating the radiation dose rate to representative aquatic organisms from alpha, beta, and gamma irradiation from external and internal sources. Tables containing parameter values for calculating radiation doses from selected alpha, beta, and gamma emitters are presented in the appendix to facilitate dose rate calculations. The risk of detrimental effects to aquatic biota from radiation exposure is evaluated by comparing the calculated radiation dose rate to biota to the U.S. Department of Energy`s (DOE`s) recommended dose rate limit of 0.4 mGy h{sup {minus}1} (1 rad d{sup {minus}1}). A dose rate no greater than 0.4 mGy h{sup {minus}1} to the most sensitive organisms should ensure the protection of populations of aquatic organisms. DOE`s recommended dose rate is based on a number of published reviews on the effects of radiation on aquatic organisms that are summarized in the National Council on Radiation Protection and Measurements Report No. 109 (NCRP 1991). DOE recommends that if the results of radiological models or dosimetric measurements indicate that a radiation dose rate of 0. 1 mGy h{sup {minus}1} will be exceeded, then a more detailed evaluation of the potential ecological consequences of radiation exposure to endemic populations should be conducted.

  11. Radiation effects on materials in high-radiation environments: A workshop summary

    Science.gov (United States)

    Weber, W. J.; Mansur, L. K.; Clinard, F. W.; Parkin, D. M.

    1991-08-01

    A workshop on Radiation Effects on Materials in High-Radiation Environments was held in Salt Lake City, Utah (USA) from August 13 to 15, 1990 under the auspices of the Division of Materials Sciences, Office of Basic Energy Sciences, US Department of Energy. The workshop focused on ceramics, alloys, and intermetallics and covered research needs and capabilities, recent experimental data, theory, and computer simulations. It was concluded that there is clearly a continuing scientific and technological need for fundamental knowledge on the underlying causes of radiation-induced property changes in materials. Furthermore, the success of many current and emerging nuclear-related technologies critically depend on renewed support for basic radiation-effects research, irradiation facilities, and training of scientists. The highlights of the workshop are reviewed and specific recommendations are made regarding research needs.

  12. PABLM: a computer program to calculate accumulated radiation doses from radionuclides in the environment

    Energy Technology Data Exchange (ETDEWEB)

    Napier, B.A.; Kennedy, W.E. Jr.; Soldat, J.K.

    1980-03-01

    A computer program, PABLM, was written to facilitate the calculation of internal radiation doses to man from radionuclides in food products and external radiation doses from radionuclides in the environment. This report contains details of mathematical models used and calculational procedures required to run the computer program. Radiation doses from radionuclides in the environment may be calculated from deposition on the soil or plants during an atmospheric or liquid release, or from exposure to residual radionuclides in the environment after the releases have ended. Radioactive decay is considered during the release of radionuclides, after they are deposited on the plants or ground, and during holdup of food after harvest. The radiation dose models consider several exposure pathways. Doses may be calculated for either a maximum-exposed individual or for a population group. The doses calculated are accumulated doses from continuous chronic exposure. A first-year committed dose is calculated as well as an integrated dose for a selected number of years. The equations for calculating internal radiation doses are derived from those given by the International Commission on Radiological Protection (ICRP) for body burdens and MPC's of each radionuclide. The radiation doses from external exposure to contaminated water and soil are calculated using the basic assumption that the contaminated medium is large enough to be considered an infinite volume or plane relative to the range of the emitted radiations. The equations for calculations of the radiation dose from external exposure to shoreline sediments include a correction for the finite width of the contaminated beach.

  13. Modelling Virtual Environments for Geovisualization

    DEFF Research Database (Denmark)

    Bodum, Lars

    2005-01-01

    The use of virtual environments in geovisualization has become a major topic within the last few years. The main reason for this interest in the growing use of 3D models and visual realizations in a wide range of applications concerned with the geographic element of information. The implementation....... The two variables used for the categorization in this chapter are level of abstraction and the temporal characteristics of the model....

  14. [Effect of the ISS Russian segment configuration on the service module radiation environment].

    Science.gov (United States)

    Mitrikas, V G

    2011-01-01

    Mathematical modeling of variations in the Service module radiation environment as a function of ISS Russian segment configuration was carried out using models of the RS modules and a spherical humanoid phantom. ISS reconfiguration impacted significantly only the phantom brought into the transfer compartment (ExT). The Radiation Safety Service prohibition for cosmonauts to stay in this compartment during solar flare events remains valid. In all other instances, error of dose estimation is higher as compared to dose value estimation with consideration for ISS RS reconfiguration.

  15. GEM detectors development for radiation environment: neutron tests and simulations

    Science.gov (United States)

    Chernyshova, Maryna; Jednoróg, Sławomir; Malinowski, Karol; Czarski, Tomasz; Ziółkowski, Adam; Bieńkowska, Barbara; Prokopowicz, Rafał; Łaszyńska, Ewa; Kowalska-Strzeciwilk, Ewa; Poźniak, Krzysztof T.; Kasprowicz, Grzegorz; Zabołotny, Wojciech; Wojeński, Andrzej; Krawczyk, Rafał D.; Linczuk, Paweł; Potrykus, Paweł; Bajdel, Barcel

    2016-09-01

    One of the requests from the ongoing ITER-Like Wall Project is to have diagnostics for Soft X-Ray (SXR) monitoring in tokamak. Such diagnostics should be focused on tungsten emission measurements, as an increased attention is currently paid to tungsten due to a fact that it became a main candidate for the plasma facing material in ITER and future fusion reactor. In addition, such diagnostics should be able to withstand harsh radiation environment at tokamak during its operation. The presented work is related to the development of such diagnostics based on Gas Electron Multiplier (GEM) technology. More specifically, an influence of neutron radiation on performance of the GEM detectors is studied both experimentally and through computer simulations. The neutron induced radioactivity (after neutron source exposure) was found to be not pronounced comparing to an impact of other secondary neutron reaction products (during the exposure).

  16. 飞机进近着陆电磁环境建模与辐射分布分析%Modeling of electromagnetic environment and radiation distribution analysis for aircraft approaching and landing

    Institute of Scientific and Technical Information of China (English)

    王磊; 苏东林; 谢树果; 赵子华

    2012-01-01

    Electromagnetic field, terrain and obstacle are three vital elements which constitute electro- magnetic environment in aerodrome terminal. Because of their inhomogeneity in topology, physics and seman- teme, it is difficult to express the characteristic of the electromagnetic environment for aircraft approaching and landing with determined model. Based on the attribute of hierarchy and the coupling interrelation of those three elements, a multi-layer fused electromagnetic environment model frame for aerodrome terminal was put for- ward. In order to reduce the computation error induced by the non-regulation boundary variation of electromag- netic field, a combination of method of moment(MoM) and ray tracing methods was used to simulate the radi- ation pattern and wave propagation, and radiation intensity expression and distribution computation flow in ap- proaching and landing area were described. Simulation experiment of the radiation computation in approaching area based on one aerodrome dataset shows the validity of the modeling method.%机场终端区电磁、地形和地物在拓扑、物理和语义上的异构性导致进近着陆电磁环境构成机理复杂,很难用单尺度解析模型表征电磁环境的本质属性.在分析终端区多要素层次构成机理和关联耦合特征的基础上,提出一种多层融合的进近着陆电磁环境模型架构.综合采用矩量法和射线追踪法模拟台站辐射特性和地空电波传播模式,建立进近着陆区域电磁辐射强度量化表征与空间分布计算模型,有效降低了场边界特性不规则时空变化带来的电波预测误差.结合某机场地形和航向台数据,对终端区主航道和余隙航道的电磁辐射强度和覆盖范围进行计算和对比分析.仿真结果验证了本建模与分析方法的有效性.

  17. Buckling analysis of a cylindrical shell, under neutron radiation environment

    Energy Technology Data Exchange (ETDEWEB)

    Arani, A. Ghorbanpour [Department of Mechanical Engineering, School of Engineering, University of Kashan, Kashan (Iran, Islamic Republic of); Ahmadi, M. [School of Research and Development of Nuclear Reactors and Accelerators, Nuclear Science and Technology (Iran, Islamic Republic of); Ahmadi, A. [Department of Management, University of Tehran, Tehran (Iran, Islamic Republic of); Rastgoo, A. [Department of Mechanical Engineering, School of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Sepyani, H.A., E-mail: hosepiani@yahoo.com [Department of Mechanical Engineering, School of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer The work investigates the buckling of a shell in the neutron radiation environment. Black-Right-Pointing-Pointer Radiation induced porosity in elastic materials affects the material's properties. Black-Right-Pointing-Pointer The data based technique was used to determine the volume fraction porosity. Black-Right-Pointing-Pointer The theoretical formulations are presented based on the classical shell theory (CST). Black-Right-Pointing-Pointer It was concluded that both T and neutron induced swelling have significant effects. - Abstract: This research investigates the buckling of a cylindrical shell in the neutron radiation environment, subjected to combined static and periodic axial forces. Radiation induced porosity in elastic materials affects the thermal, electrical and mechanical properties of the materials. In this study, the data based technique was used to determine the volume fraction porosity, P, of shell material. A least-squares fit of the Young's module data yielded the estimated Young's modulus. The shell assumed made of iron irradiated in the range of 2-15e-7 dPa/s at 345-650 Degree-Sign C and theoretical formulations are presented based on the classical shell theory (CST). The research deals with the problem theoretically; keeping in mind that one means of generating relevant design data is to investigate prototype structures. A parametric study is followed and the stability of shell is discussed. It is concluded that both temperature and neutron induced swelling have significant effects on the buckling load.

  18. Radiation Hardened Electronics Destined For Severe Nuclear Reactor Environments

    Energy Technology Data Exchange (ETDEWEB)

    Holbert, Keith E. [Arizona State Univ., Tempe, AZ (United States); Clark, Lawrence T. [Arizona State Univ., Tempe, AZ (United States)

    2016-02-19

    Post nuclear accident conditions represent a harsh environment for electronics. The full station blackout experience at Fukushima shows the necessity for emergency sensing capabilities in a radiation-enhanced environment. This NEET (Nuclear Energy Enabling Technologies) research project developed radiation hardened by design (RHBD) electronics using commercially available technology that employs commercial off-the-shelf (COTS) devices and present generation circuit fabrication techniques to improve the total ionizing dose (TID) hardness of electronics. Such technology not only has applicability to severe accident conditions but also to facilities throughout the nuclear fuel cycle in which radiation tolerance is required. For example, with TID tolerance to megarads of dose, electronics could be deployed for long-term monitoring, inspection and decontamination missions. The present work has taken a two-pronged approach, specifically, development of both board and application-specific integrated circuit (ASIC) level RHBD techniques. The former path has focused on TID testing of representative microcontroller ICs with embedded flash (eFlash) memory, as well as standalone flash devices that utilize the same fabrication technologies. The standalone flash devices are less complicated, allowing better understanding of the TID response of the crucial circuits. Our TID experiments utilize biased components that are in-situ tested, and in full operation during irradiation. A potential pitfall in the qualification of memory circuits is the lack of rigorous testing of the possible memory states. For this reason, we employ test patterns that include all ones, all zeros, a checkerboard of zeros and ones, an inverse checkerboard, and random data. With experimental evidence of improved radiation response for unbiased versus biased conditions, a demonstration-level board using the COTS devices was constructed. Through a combination of redundancy and power gating, the demonstration

  19. Directions in Radiation Transport Modelling

    Directory of Open Access Journals (Sweden)

    P Nicholas Smith

    2016-12-01

    More exciting advances are on the horizon to increase the power of simulation tools. The advent of high performance computers is allowing bigger, higher fidelity models to be created, if the challenges of parallelization and memory management can be met. 3D whole core transport modelling is becoming possible. Uncertainty quantification is improving with large benefits to be gained from more accurate, less pessimistic estimates of uncertainty. Advanced graphical displays allow the user to assimilate and make sense of the vast amounts of data produced by modern modelling tools. Numerical solvers are being developed that use goal-based adaptivity to adjust the nodalisation of the system to provide the optimum scheme to achieve the user requested accuracy on the results, thus removing the need to perform costly convergence studies in space and angle etc. More use is being made of multi-physics methods in which radiation transport is coupled with other phenomena, such as thermal-hydraulics, structural response, fuel performance and/or chemistry in order to better understand their interplay in reactor cores.

  20. Effect of ionizing radiation on the waste package environment

    Energy Technology Data Exchange (ETDEWEB)

    Reed, D.T. [Argonne National Lab., IL (USA); Van Konynenburg, R.A. [Lawrence Livermore National Lab., CA (USA)

    1991-05-01

    The radiolytic production of nitrogen oxides, nitrogen acids and ammonia are discussed in relation to the expected environment in a high-level waste repository that may be constructed at the Yucca Mountain site if it is found to be suitable. Both literature data and repository-relevant data are summarized for air-water vapor systems. The limiting cases of a dry air and a pure water vapor gas phase are also discussed. Design guidelines and recommendations, based solely on the potential consequence of radiation enhancement of corrosion, are given. 13 refs., 5 figs., 1 tab.

  1. Planetary and Interplanetary Environmental Models for Radiation Analysis

    Science.gov (United States)

    DeAngelis, G.; Cucinotta, F. A.

    2005-01-01

    The essence of environmental modeling is presented as suited for radiation analysis purposes. The variables of fundamental importance for radiation environmental assessment are discussed. The characterization is performed by dividing modeling into three areas, namely the interplanetary medium, the circumplanetary environment, and the planetary or satellite surface. In the first area, the galactic cosmic rays (GCR) and their modulation by the heliospheric magnetic field as well as and solar particle events (SPE) are considered, in the second area the magnetospheres are taken into account, and in the third area the effect of the planetary environment is also considered. Planetary surfaces and atmospheres are modeled based on results from the most recent targeted spacecraft. The results are coupled with suited visualization techniques and radiation transport models in support of trade studies of health risks for future exploration missions.

  2. Cryogenic Si detectors for ultra radiation hardness in SLHC environment

    Science.gov (United States)

    Li, Zheng; Abreu, M.; Anbinderis, P.; Anbinderis, T.; Ambrosio, N. D.'.; de Boer, W.; Borchi, E.; Borer, K.; Bruzzi, M.; Buontempo, S.; Chen, W.; Cindro, V.; Dierlamm, A.; Eremin, V.; Gaubas, E.; Gorbatenko, V.; Grigoriev, E.; Hauler, F.; Heijne, E.; Heising, S.; Hempel, O.; Herzog, R.; Härkönen, J.; Ilyashenko, I.; Janos, S.; Jungermann, L.; Kalesinskas, V.; Kapturauskas, J.; Laiho, R.; Luukka, P.; Mandic, I.; De Masi, Rita; Menichelli, D.; Mikuz, M.; Militaru, O.; Niinikosky, T. O.; Shea, V. O.'.; Pagano, S.; Paul, S.; Piotrzkowski, K.; Pretzl, K.; Rato Mendes, P.; Rouby, X.; Ruggiero, G.; Smith, K.; Sonderegger, P.; Sousa, P.; Tuominen, E.; Tuovinen, E.; Verbitskaya, E.; Vaitkus, J.; Wobst, E.; Zavrtanik, M.

    2007-09-01

    Radiation hardness up to 10 16 neq/cm 2 is required in the future HEP experiments for most inner detectors. However, 10 16 neq/cm 2 fluence is well beyond the radiation tolerance of even the most advanced semiconductor detectors fabricated by commonly adopted technologies: the carrier trapping will limit the charge collection depth to an effective range of 20-30 μm regardless of depletion depth. Significant improvement of the radiation hardness of silicon sensors has been taken place within RD39. Fortunately the cryogenic tool we have been using provides us a convenient way to solve the detector charge collection efficiency (CCE) problem at SLHC radiation level (10 16 neq/cm 2). There are two key approaches in our efforts: (1) use of the charge/current injection to manipulate the detector internal electric field in such a way that it can be depleted at a modest bias voltage at cryogenic temperature range (⩽230 K); and (2) freezing out of the trapping centers that affects the CCE at cryogenic temperatures lower than that of the LN 2 temperature. In our first approach, we have developed the advanced radiation hard detectors using charge or current injection, the current injected diodes (CID). In a CID, the electric field is controlled by injected current, which is limited by the space charge, yielding a nearly uniform electric field in the detector, independent of the radiation fluence. In our second approach, we have developed models of radiation-induced trapping levels and the physics of their freezing out at cryogenic temperatures. In this approach, we intend to study the trapping effect at temperatures below LN 2 temperature. A freeze-out of trapping can certainly help in the development of ultra-radiation hard Si detectors for SLHC. A detector CCE measurement system using ultra-fast picosecond laser with a He cryostat has been built at CERN. This system can be used to find out the practical cryogenic temperature range that can be used to freeze out the

  3. Cryogenic Si detectors for ultra radiation hardness in SLHC environment

    Energy Technology Data Exchange (ETDEWEB)

    Li Zheng [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Abreu, M. [LIP, Av. E. Garcia, P-1000 Lisbon (Portugal); Anbinderis, P.; Anbinderis, T. [University of Vilnius, Institute of Materials Science and Applied Research, 2040 Vilnius (Lithuania); Ambrosio, N.D' . [Instiuto di Cibernetica ' E. Caianiello' , 80078 Pozzuoli (Italy); Boer, W. de [IEKP University of Karlsruhe, D-76128 Karlsruhe (Germany); Borchi, E. [Dipartimento di Energetica, Universita di Firenze, I-50139 Florence (Italy); Borer, K. [Laboratorium fuer Hochenergiephysik der Universitaet Bern, Sidlerstarsse 5, CH-3012 Bern (Switzerland); Bruzzi, M. [Dipartimento di Energetica, Universita di Firenze, I-50139 Firenze (Italy); Buontempo, S. [Instiuto di Cibernetica ' E. Caianiello' , 80078 Pozzuoli (Italy); Chen, W. [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Cindro, V. [Jozef Stefan Institute, Exp. Particle Physics Department, PO. Box 3000, 1001 Ljubljana (Slovenia); Dierlamm, A. [IEKP University of Karlsruhe, D-76128 Karlsruhe (Germany); Eremin, V. [Ioffe Physico-Technical Institute, Russian Academy of Sciences, St. Petersburg 194021 (Russian Federation); Gaubas, E.; Gorbatenko, V. [University of Vilnius, Institute of Materials Science and Applied Research, 2040 Vilnius (Lithuania); Grigoriev, E. [IEKP University of Karlsruhe, D-76128 Karlsruhe (Germany); Department de Radiologie, Universite de Geneve, CH-1211 Geneva (Switzerland); Hauler, F. [IEKP University of Karlsruhe, D-76128 Karlsruhe (Germany); Heijne, E. [CERN, CH-1211 Geneva (Switzerland); Heising, S. [IEKP University of Karlsruhe, D-76128 Karlsruhe (Germany)] (and others)

    2007-09-01

    Radiation hardness up to 10{sup 16} n{sub eq}/cm{sup 2} is required in the future HEP experiments for most inner detectors. However, 10{sup 16} n{sub eq}/cm{sup 2} fluence is well beyond the radiation tolerance of even the most advanced semiconductor detectors fabricated by commonly adopted technologies: the carrier trapping will limit the charge collection depth to an effective range of 20-30 {mu}m regardless of depletion depth. Significant improvement of the radiation hardness of silicon sensors has been taken place within RD39. Fortunately the cryogenic tool we have been using provides us a convenient way to solve the detector charge collection efficiency (CCE) problem at SLHC radiation level (10{sup 16} n{sub eq}/cm{sup 2}). There are two key approaches in our efforts: (1) use of the charge/current injection to manipulate the detector internal electric field in such a way that it can be depleted at a modest bias voltage at cryogenic temperature range ({<=}230 K); and (2) freezing out of the trapping centers that affects the CCE at cryogenic temperatures lower than that of the LN{sub 2} temperature. In our first approach, we have developed the advanced radiation hard detectors using charge or current injection, the current injected diodes (CID). In a CID, the electric field is controlled by injected current, which is limited by the space charge, yielding a nearly uniform electric field in the detector, independent of the radiation fluence. In our second approach, we have developed models of radiation-induced trapping levels and the physics of their freezing out at cryogenic temperatures. In this approach, we intend to study the trapping effect at temperatures below LN{sub 2} temperature. A freeze-out of trapping can certainly help in the development of ultra-radiation hard Si detectors for SLHC. A detector CCE measurement system using ultra-fast picosecond laser with a He cryostat has been built at CERN. This system can be used to find out the practical

  4. Polymer materials and component evaluation in acidic-radiation environments

    Science.gov (United States)

    Celina, M.; Gillen, K. T.; Malone, G. M.; Clough, R. L.; Nelson, W. H.

    2001-07-01

    Polymeric materials used for cable/wire insulation, electrical connectors, O-rings, seals, and in critical components such as motors, level switches and resistive thermo-devices were evaluated under accelerated degradation conditions in combined radiation-oxidative elevated-temperature acidic-vapor (nitric/oxalic) environments relevant to conditions in isotope processing facilities. Experiments included the assessment of individual materials such as PEEK, polyimides, polyolefin based cable insulation, EPDM rubbers, various epoxy systems, commercial caulking materials as well as some functional testing of components. We discuss how to conduct laboratory experiments to simulate such complex hostile environments, describe some degradation effects encountered, and evaluate the impact on appropriate material and component selection.

  5. A New Vertical JFET Power Device for Harsh Radiation Environments

    Directory of Open Access Journals (Sweden)

    Pablo Fernández-Martínez

    2017-02-01

    Full Text Available An increasing demand for power electronic devices able to be operative in harsh radiation environments is now taking place. Specifically, in High Energy Physics experiments the required power devices are expected to withstand very high radiation levels which are normally too hard for most of the available commercial solutions. In this context, a new vertical junction field effect transistor (JFET has been designed and fabricated at the Instituto de Microelectrónica de Barcelona, Centro Nacional de Microelectrónica (IMB-CNM, CSIC. The new silicon V-JFET devices draw upon a deep-trenched technology to achieve volume conduction and low switch-off voltage, together with a moderately high voltage capability. The first batches of V-JFET prototypes have been already fabricated at the IMB-CNM clean room, and several aspects of their design, fabrication and the outcome of their characterization are summarized and discussed in this paper. Radiation hardness of the fabricated transistors have been tested both with gamma and neutron irradiations, and the results are also included in the contribution.

  6. Cabin Environment Physics Risk Model

    Science.gov (United States)

    Mattenberger, Christopher J.; Mathias, Donovan Leigh

    2014-01-01

    This paper presents a Cabin Environment Physics Risk (CEPR) model that predicts the time for an initial failure of Environmental Control and Life Support System (ECLSS) functionality to propagate into a hazardous environment and trigger a loss-of-crew (LOC) event. This physics-of failure model allows a probabilistic risk assessment of a crewed spacecraft to account for the cabin environment, which can serve as a buffer to protect the crew during an abort from orbit and ultimately enable a safe return. The results of the CEPR model replace the assumption that failure of the crew critical ECLSS functionality causes LOC instantly, and provide a more accurate representation of the spacecraft's risk posture. The instant-LOC assumption is shown to be excessively conservative and, moreover, can impact the relative risk drivers identified for the spacecraft. This, in turn, could lead the design team to allocate mass for equipment to reduce overly conservative risk estimates in a suboptimal configuration, which inherently increases the overall risk to the crew. For example, available mass could be poorly used to add redundant ECLSS components that have a negligible benefit but appear to make the vehicle safer due to poor assumptions about the propagation time of ECLSS failures.

  7. Measurements of the radiation environment from CREDO-II on STRV & APEX

    Science.gov (United States)

    Dyer, C. S.; Watson, C. J.; Peerless, C. L.; Sims, A. J.; Barth, J.

    1996-12-01

    The Cosmic Radiation Environment and Dosimetry experiments (CREDO) have now been operational in complementary orbits onboard the Advanced Photovoltaics & Electronics Experiment Spacecraft and Space Technology Research Vehicle since the summer of 1994 enabling extensive comparisons of measured dose and linear energy transfer (LET) spectra with the standard environment models. Measurements have been made at a range of shielding depths and detailed spacecraft models are employed. Significant discrepancies are seen for the outer-belt electron component which shows large time variations. Shielding effects are shown to be highly significant for both dose and LET spectra. Even allowing for this the measured LET spectra are somewhat below the predictions for solar minimum.

  8. A Prediction Model of MF Radiation in Environmental Assessment

    Institute of Scientific and Technical Information of China (English)

    HE-SHAN GE; YAN-FENG HONG

    2006-01-01

    Objective To predict the impact of MF radiation on human health.Methods The vertical distribution of field intensity was estimated by analogism on the basis of measured values from simulation measurement. Results A kind of analogism on the basis of geometric proportion decay pattern is put forward in the essay. It showed that with increasing of height the field intensity increased according to geometric proportion law. Conclusion This geometric proportion prediction model can be used to estimate the impact of MF radiation on inhabited environment, and can act as a reference pattern in predicting the environmental impact level of MF radiation.

  9. CONSTRAINING THE RADIATION AND PLASMA ENVIRONMENT OF THE KEPLER CIRCUMBINARY HABITABLE-ZONE PLANETS

    Energy Technology Data Exchange (ETDEWEB)

    Zuluaga, Jorge I. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Mason, Paul A. [New Mexico State University—DACC, Las Cruces, NM 88003 (United States); Cuartas-Restrepo, Pablo A. [FACom—Instituto de Física—FCEN, Universidad de Antioquia, Calle 70 No. 52-21, Medellín (Colombia)

    2016-02-20

    The discovery of many planets using the Kepler telescope includes 10 planets orbiting eight binary stars. Three binaries, Kepler-16, Kepler-47, and Kepler-453, have at least one planet in the circumbinary habitable zone (BHZ). We constrain the level of high-energy radiation and the plasma environment in the BHZ of these systems. With this aim, BHZ limits in these Kepler binaries are calculated as a function of time, and the habitability lifetimes are estimated for hypothetical terrestrial planets and/or moons within the BHZ. With the time-dependent BHZ limits established, a self-consistent model is developed describing the evolution of stellar activity and radiation properties as proxies for stellar aggression toward planetary atmospheres. Modeling binary stellar rotation evolution, including the effect of tidal interaction between stars in binaries, is key to establishing the environment around these systems. We find that Kepler-16 and its binary analogs provide a plasma environment favorable for the survival of atmospheres of putative Mars-sized planets and exomoons. Tides have modified the rotation of the stars in Kepler-47, making its radiation environment less harsh in comparison to the solar system. This is a good example of the mechanism first proposed by Mason et al. Kepler-453 has an environment similar to that of the solar system with slightly better than Earth radiation conditions at the inner edge of the BHZ. These results can be reproduced and even reparameterized as stellar evolution and binary tidal models progress, using our online tool http://bhmcalc.net.

  10. Constraining the Radiation and Plasma Environment of the Kepler Circumbinary Habitable-zone Planets

    Science.gov (United States)

    Zuluaga, Jorge I.; Mason, Paul A.; Cuartas-Restrepo, Pablo A.

    2016-02-01

    The discovery of many planets using the Kepler telescope includes 10 planets orbiting eight binary stars. Three binaries, Kepler-16, Kepler-47, and Kepler-453, have at least one planet in the circumbinary habitable zone (BHZ). We constrain the level of high-energy radiation and the plasma environment in the BHZ of these systems. With this aim, BHZ limits in these Kepler binaries are calculated as a function of time, and the habitability lifetimes are estimated for hypothetical terrestrial planets and/or moons within the BHZ. With the time-dependent BHZ limits established, a self-consistent model is developed describing the evolution of stellar activity and radiation properties as proxies for stellar aggression toward planetary atmospheres. Modeling binary stellar rotation evolution, including the effect of tidal interaction between stars in binaries, is key to establishing the environment around these systems. We find that Kepler-16 and its binary analogs provide a plasma environment favorable for the survival of atmospheres of putative Mars-sized planets and exomoons. Tides have modified the rotation of the stars in Kepler-47, making its radiation environment less harsh in comparison to the solar system. This is a good example of the mechanism first proposed by Mason et al. Kepler-453 has an environment similar to that of the solar system with slightly better than Earth radiation conditions at the inner edge of the BHZ. These results can be reproduced and even reparameterized as stellar evolution and binary tidal models progress, using our online tool http://bhmcalc.net.

  11. Space Radiation Environment Prediction for VLSI microelectronics devices onboard a LEO Satellite using OMERE-Trad Software

    Science.gov (United States)

    Sajid, Muhammad

    This tutorial/survey paper presents the assessment/determination of level of hazard/threat to emerging microelectronics devices in Low Earth Orbit (LEO) space radiation environment with perigee at 300 Km, apogee at 600Km altitude having different orbital inclinations to predict the reliability of onboard Bulk Built-In Current Sensor (BBICS) fabricated in 350nm technology node at OptMA Lab. UFMG Brazil. In this context, the various parameters for space radiation environment have been analyzed to characterize the ionizing radiation environment effects on proposed BBICS. The Space radiation environment has been modeled in the form of particles trapped in Van-Allen radiation belts(RBs), Energetic Solar Particles Events (ESPE) and Galactic Cosmic Rays (GCR) where as its potential effects on Device- Under-Test (DUT) has been predicted in terms of Total Ionizing Dose (TID), Single-Event Effects (SEE) and Displacement Damage Dose (DDD). Finally, the required mitigation techniques including necessary shielding requirements to avoid undesirable effects of radiation environment at device level has been estimated /determined with assumed standard thickness of Aluminum shielding. In order to evaluate space radiation environment and analyze energetic particles effects on BBICS, OMERE toolkit developed by TRAD was utilized.

  12. Modeling Space Radiation with Radiomimetic Agent Bleomycin

    Science.gov (United States)

    Lu, Tao

    2017-01-01

    Space radiation consists of proton and helium from solar particle events (SPE) and high energy heavy ions from galactic cosmic ray (GCR). This mixture of radiation with particles at different energy levels has different effects on biological systems. Currently, majority studies of radiation effects on human were based on single-source radiation due to the limitation of available method to model effects of space radiation on living organisms. While NASA Space Radiation Laboratory is working on advanced switches to make it possible to have a mixed field radiation with particles of different energies, the radiation source will be limited. Development of an easily available experimental model for studying effects of mixed field radiation could greatly speed up our progress in our understanding the molecular mechanisms of damage and responses from exposure to space radiation, and facilitate the discovery of protection and countermeasures against space radiation, which is critical for the mission to Mars. Bleomycin, a radiomimetic agent, has been widely used to study radiation induced DNA damage and cellular responses. Previously, bleomycin was often compared to low low Linear Energy Transfer (LET) gamma radiation without defined characteristics. Our recent work demonstrated that bleomycin could induce complex clustered DNA damage in human fibroblasts that is similar to DNA damage induced by high LET radiation. These type of DNA damage is difficult to repair and can be visualized by gamma-H2Ax staining weeks after the initial insult. The survival ratio between early and late plating of human fibroblasts after bleomycin treatment is between low LET and high LET radiation. Our results suggest that bleomycin induces DNA damage and other cellular stresses resembling those resulted from mixed field radiation with both low and high LET particles. We hypothesize that bleomycin could be used to mimic space radiation in biological systems. Potential advantages and limitations of

  13. Constraining the Radiation and Plasma Environment of the Kepler Circumbinary Habitable Zone Planets

    CERN Document Server

    Zuluaga, Jorge I; Cuartas, Pablo A

    2015-01-01

    The remarkable discovery of many planets and candidates using the Kepler telescope even includes ten planets orbiting eight binaries. Three out of the eight, Kepler 16, Kepler 47, and KIC 9632895, have at least one planet in the circumbinary habitable zone (BHZ). In previous work (Mason et al. 2013), we investigated the potential habitability of Earth-like circumbinary planets. In particular, we highlighted the role of mutual stellar tidal interaction and the resulting impact on terrestrial planet habitability. The Kepler binaries with planets in the BHZ are studied in order to constrain the high energy radiation and plasma environment of potentially habitable circumbinary planets. The limits of the BHZ in these binaries as a function of time are estimated and the habitability lifetime is calculated. A self-consistent model of the evolution of stellar rotation including the effect of tidal interaction is key to establishing the plasma and radiation environment. A comprehensive model of the evolution of stella...

  14. MARS15 Simulation of Radiation Environment at the ESS Linac

    Energy Technology Data Exchange (ETDEWEB)

    Mokhov, N. V. [Fermilab; Eidelman, Yu. I. [Euclid Techlabs, Solon; Rakhno, I. L. [Fermilab; Tchelidze, L. [ESS, Lund; Tropin, I. S. [Fermilab

    2016-12-01

    Comprehensive studies with the MARS15(2016) Monte-Carlo code are described on evaluation of prompt and residual radiation levels induced by nominal and accidental beam losses in the 5-MW, 2-GeV European Spallation Source (ESS) Linac. These are to provide a basis for radiation shielding design verification through the accelerator complex. The calculation model is based on the latest engineering design and includes a sophisticated algorithm for particle tracking in the machine RF cavities as well as a well-established model of the beam loss. Substantial efforts were put in solving the deep-penetration problem for the thick shielding around the tunnel with numerous complex penetrations. It allowed us to study in detail not only the prompt dose, but also component and air activation, radiation loads on the soil outside the tunnel, and skyshine studies for the complicated 3-D surface above the machine. Among the other things, the newest features in MARS15 (2016), such as a ROOT-based beamline builder and a TENDL-based event generator for nuclear interactions below 100 MeV, were very useful in this challenging application

  15. Assessing the effects of ultraviolet radiation on the photosynthetic potential in Archean marine environments

    Science.gov (United States)

    Avila-Alonso, Dailé; Baetens, Jan M.; Cardenas, Rolando; de Baets, Bernard

    2017-07-01

    In this work, the photosynthesis model presented by Avila et al. in 2013 is extended and more scenarios inhabited by ancient cyanobacteria are investigated to quantify the effects of ultraviolet (UV) radiation on their photosynthetic potential in marine environments of the Archean eon. We consider ferrous ions as blockers of UV during the Early Archean, while the absorption spectrum of chlorophyll a is used to quantify the fraction of photosynthetically active radiation absorbed by photosynthetic organisms. UV could have induced photoinhibition at the water surface, thereby strongly affecting the species with low light use efficiency. A higher photosynthetic potential in early marine environments was shown than in the Late Archean as a consequence of the attenuation of UVC and UVB by iron ions, which probably played an important role in the protection of ancient free-floating bacteria from high-intensity UV radiation. Photosynthetic organisms in Archean coastal and ocean environments were probably abundant in the first 5 and 25 m of the water column, respectively. However, species with a relatively high efficiency in the use of light could have inhabited ocean waters up to a depth of 200 m and show a Deep Chlorophyll Maximum near 60 m depth. We show that the electromagnetic radiation from the Sun, both UV and visible light, could have determined the vertical distribution of Archean marine photosynthetic organisms.

  16. BNCT-RTPE: BNCT radiation treatment planning environment

    Energy Technology Data Exchange (ETDEWEB)

    Wessol, D.E.; Wheeler, F.J. [Idaho National Engineering Lab., Idaho Fall, ID (United States); Babcock, R.S. [and others

    1995-11-01

    Several improvements have been developed for the BNCT radiation treatment planning environment (BNCT-Rtpe) during 1994. These improvements have been incorporated into Version 1.0 of BNCT-Rtpe which is currently installed at the INEL, BNL, Japanese Research Center (JRC), and Finland`s Technical Research Center. Platforms supported by this software include Hewlett-Packard (HP), SUN, International Business Machines (IBM), and Silicon Graphics Incorporated (SGI). A draft version of the BNCT-Rtpe user manual is available. Version 1.1 of BNCT-Rtpe is scheduled for release in March 1995. It is anticipated that Version 2.x of BNCT-Rtpe, which includes the nonproprietary NURBS library and data structures, will be released in September 1995.

  17. The radiation environment near the lunar surface: CRaTER observations and Geant4 simulations

    National Research Council Canada - National Science Library

    M D Looper; J E Mazur; J B Blake; H E Spence; N A Schwadron; M J Golightly; A W Case; J C Kasper; L W Townsend

    2013-01-01

      At the start of the Lunar Reconnaissance Orbiter mission in 2009, its Cosmic Ray Telescope for the Effects of Radiation instrument measured the radiation environment near the Moon during the recent...

  18. Methodology for Estimating Radiation Dose Rates to Freshwater Biota Exposed to Radionuclides in the Environment

    Energy Technology Data Exchange (ETDEWEB)

    Blaylock, B.G.

    1993-01-01

    The purpose of this report is to present a methodology for evaluating the potential for aquatic biota to incur effects from exposure to chronic low-level radiation in the environment. Aquatic organisms inhabiting an environment contaminated with radioactivity receive external radiation from radionuclides in water, sediment, and from other biota such as vegetation. Aquatic organisms receive internal radiation from radionuclides ingested via food and water and, in some cases, from radionuclides absorbed through the skin and respiratory organs. Dose rate equations, which have been developed previously, are presented for estimating the radiation dose rate to representative aquatic organisms from alpha, beta, and gamma irradiation from external and internal sources. Tables containing parameter values for calculating radiation doses from selected alpha, beta, and gamma emitters are presented in the appendix to facilitate dose rate calculations. The risk of detrimental effects to aquatic biota from radiation exposure is evaluated by comparing the calculated radiation dose rate to biota to the U.S. Department of Energy's (DOE's) recommended dose rate limit of 0.4 mGy h{sup -1} (1 rad d{sup -1}). A dose rate no greater than 0.4 mGy h{sup -1} to the most sensitive organisms should ensure the protection of populations of aquatic organisms. DOE's recommended dose rate is based on a number of published reviews on the effects of radiation on aquatic organisms that are summarized in the National Council on Radiation Protection and Measurements Report No. 109 (NCRP 1991). The literature identifies the developing eggs and young of some species of teleost fish as the most radiosensitive organisms. DOE recommends that if the results of radiological models or dosimetric measurements indicate that a radiation dose rate of 0.1 mGy h{sup -1} will be exceeded, then a more detailed evaluation of the potential ecological consequences of radiation exposure to endemic

  19. Methodology for Estimating Radiation Dose Rates to Freshwater Biota Exposed to Radionuclides in the Environment

    Energy Technology Data Exchange (ETDEWEB)

    Blaylock, B.G.

    1993-01-01

    The purpose of this report is to present a methodology for evaluating the potential for aquatic biota to incur effects from exposure to chronic low-level radiation in the environment. Aquatic organisms inhabiting an environment contaminated with radioactivity receive external radiation from radionuclides in water, sediment, and from other biota such as vegetation. Aquatic organisms receive internal radiation from radionuclides ingested via food and water and, in some cases, from radionuclides absorbed through the skin and respiratory organs. Dose rate equations, which have been developed previously, are presented for estimating the radiation dose rate to representative aquatic organisms from alpha, beta, and gamma irradiation from external and internal sources. Tables containing parameter values for calculating radiation doses from selected alpha, beta, and gamma emitters are presented in the appendix to facilitate dose rate calculations. The risk of detrimental effects to aquatic biota from radiation exposure is evaluated by comparing the calculated radiation dose rate to biota to the U.S. Department of Energy's (DOE's) recommended dose rate limit of 0.4 mGy h{sup -1} (1 rad d{sup -1}). A dose rate no greater than 0.4 mGy h{sup -1} to the most sensitive organisms should ensure the protection of populations of aquatic organisms. DOE's recommended dose rate is based on a number of published reviews on the effects of radiation on aquatic organisms that are summarized in the National Council on Radiation Protection and Measurements Report No. 109 (NCRP 1991). The literature identifies the developing eggs and young of some species of teleost fish as the most radiosensitive organisms. DOE recommends that if the results of radiological models or dosimetric measurements indicate that a radiation dose rate of 0.1 mGy h{sup -1} will be exceeded, then a more detailed evaluation of the potential ecological consequences of radiation exposure to endemic

  20. A Physical Model of Electron Radiation Belts of Saturn

    Science.gov (United States)

    Lorenzato, L.; Sicard-Piet, A.; Bourdarie, S.

    2012-04-01

    Radiation belts causes irreversible damages on on-board instruments materials. That's why for two decades, ONERA proposes studies about radiation belts of magnetized planets. First, in the 90's, the development of a physical model, named Salammbô, carried out a model of the radiation belts of the Earth. Then, for few years, analysis of the magnetosphere of Jupiter and in-situ data (Pioneer, Voyager, Galileo) allow to build a physical model of the radiation belts of Jupiter. Enrolling on the Cassini age and thanks to all information collected, this study permits to adapt Salammbô jovian radiation belts model to the case of Saturn environment. Indeed, some physical processes present in the kronian magnetosphere are similar to those present in the magnetosphere of Jupiter (radial diffusion; interaction of energetic electrons with rings, moons, atmosphere; synchrotron emission). However, some physical processes have to be added to the kronian model (compared to the jovian model) because of the particularity of the magnetosphere of Saturn: interaction of energetic electrons with neutral particles from Enceladus, and wave-particle interaction. This last physical process has been studied in details with the analysis of CASSINI/RPWS (Radio and Plasma Waves Science) data. The major importance of the wave particles interaction is now well known in the case of the radiation belts of the Earth but it is important to investigate on its role in the case of Saturn. So, importance of each physical process has been studied and analysis of Cassini MIMI-LEMMS and CAPS data allows to build a model boundary condition (at L = 6). Finally, results of this study lead to a kronian electrons radiation belts model including radial diffusion, interactions of energetic electrons with rings, moons and neutrals particles and wave-particle interaction (interactions of electrons with atmosphere particles and synchrotron emission are too weak to be taken into account in this model). Then, to

  1. Impurity radiation in DEMO systems modelling

    Energy Technology Data Exchange (ETDEWEB)

    Lux, H., E-mail: Hanni.Lux@ccfe.ac.uk [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Kemp, R.; Ward, D.J. [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Sertoli, M. [Max-Planck-Institut für Plasma Physik, D-85748 Garching (Germany)

    2015-12-15

    Highlights: • Solving the exhaust problem is crucial for DEMO. • Here, we discuss the new impurity radiation model in the systems code PROCESS. • Furthermore, we assess its effect on DEMO design. • More appropriate scalings will significantly enhance predictions for DEMO. • The controllability of highly radiative scenarios remains to be shown. - Abstract: For fusion reactors with ITER divertor technology, it will be imperative to significantly reduce the heat flux into the divertor e.g. by seeded impurity radiation. This has to be done without affecting the accessibility of a high performance scenario. To assess the implications of seeded plasma impurities on DEMO design, we have developed an impurity radiation model for radiation inside the separatrix. Evaluating the validity of our model, we find the assumption of a local ionisation equilibrium to be appropriate for our purposes and the assumption of flat impurity profiles – even though not satisfactory – to represent the best currently possible. Benchmarking our model against other codes highlights the need to use up to date atomic loss function data. From the impurity radiation perspective, the main uncertainties in current DEMO design stem from the lack of confinement and L-H-threshold scalings that can be robustly extrapolated to highly radiative DEMO scenarios as well as the lack of appropriate models for the power flow from the separatrix into the divertor that include radiation in the scrape off layer. Despite these uncertainties in the model we can exclude that significant fuel dilution through seeded impurities (with Z ≥ Z{sub Ar}) will be an issue for DEMO, but the controllability of highly radiative scenarios still needs to be coherently shown.

  2. Application of Improved Radiation Modeling to General Circulation Models

    Energy Technology Data Exchange (ETDEWEB)

    Michael J Iacono

    2011-04-07

    This research has accomplished its primary objectives of developing accurate and efficient radiation codes, validating them with measurements and higher resolution models, and providing these advancements to the global modeling community to enhance the treatment of cloud and radiative processes in weather and climate prediction models. A critical component of this research has been the development of the longwave and shortwave broadband radiative transfer code for general circulation model (GCM) applications, RRTMG, which is based on the single-column reference code, RRTM, also developed at AER. RRTMG is a rigorously tested radiation model that retains a considerable level of accuracy relative to higher resolution models and measurements despite the performance enhancements that have made it possible to apply this radiation code successfully to global dynamical models. This model includes the radiative effects of all significant atmospheric gases, and it treats the absorption and scattering from liquid and ice clouds and aerosols. RRTMG also includes a statistical technique for representing small-scale cloud variability, such as cloud fraction and the vertical overlap of clouds, which has been shown to improve cloud radiative forcing in global models. This development approach has provided a direct link from observations to the enhanced radiative transfer provided by RRTMG for application to GCMs. Recent comparison of existing climate model radiation codes with high resolution models has documented the improved radiative forcing capability provided by RRTMG, especially at the surface, relative to other GCM radiation models. Due to its high accuracy, its connection to observations, and its computational efficiency, RRTMG has been implemented operationally in many national and international dynamical models to provide validated radiative transfer for improving weather forecasts and enhancing the prediction of global climate change.

  3. Spacecraft Internal Acoustic Environment Modeling

    Science.gov (United States)

    Chu, SShao-sheng R.; Allen, Christopher S.

    2009-01-01

    carried out by acquiring octave band microphone data simultaneously at ten fixed locations throughout the mockup. SPLs (Sound Pressure Levels) predicted by our SEA model match well with measurements for our CM mockup, with a more complicated shape. Additionally in FY09, background NC noise (Noise Criterion) simulation and MRT (Modified Rhyme Test) were developed and performed in the mockup to determine the maximum noise level in CM habitable volume for fair crew voice communications. Numerous demonstrations of simulated noise environment in the mockup and associated SIL (Speech Interference Level) via MRT were performed for various communities, including members from NASA and Orion prime-/sub-contractors. Also, a new HSIR (Human-Systems Integration Requirement) for limiting pre- and post-landing SIL was proposed.

  4. Lunar radiation environment and space weathering from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER)

    Science.gov (United States)

    Schwadron, N. A.; Baker, T.; Blake, B.; Case, A. W.; Cooper, J. F.; Golightly, M.; Jordan, A.; Joyce, C.; Kasper, J.; Kozarev, K.; Mislinski, J.; Mazur, J.; Posner, A.; Rother, O.; Smith, S.; Spence, H. E.; Townsend, L. W.; Wilson, J.; Zeitlin, C.

    2012-03-01

    The Cosmic Ray Telescope for the Effects of Radiation (CRaTER) measures linear energy transfer by Galactic Cosmic Rays (GCRs) and Solar Energetic Particles (SEPs) on the Lunar Reconnaissance Orbiter (LRO) Mission in a circular, polar lunar orbit. GCR fluxes remain at the highest levels ever observed during the space age. One of the largest SEP events observed by CRaTER during the LRO mission occurred on June 7, 2011. We compare model predictions by the Earth-Moon-Mars Radiation Environment Module (EMMREM) for both dose rates from GCRs and SEPs during this event with results from CRaTER. We find agreement between these models and the CRaTER dose rates, which together demonstrate the accuracy of EMMREM, and its suitability for a real-time space weather system. We utilize CRaTER to test forecasts made by the Relativistic Electron Alert System for Exploration (REleASE), which successfully predicts the June 7th event. At the maximum CRaTER-observed GCR dose rate (˜11.7 cGy/yr where Gy is a unit indicating energy deposition per unit mass, 1 Gy = 1 J/kg), GCRs deposit ˜88 eV/molecule in water over 4 billion years, causing significant change in molecular composition and physical structure (e.g., density, color, crystallinity) of water ice, loss of molecular hydrogen, and production of more complex molecules linking carbon and other elements in the irradiated ice. This shows that space weathering by GCRs may be extremely important for chemical evolution of ice on the Moon. Thus, we show comprehensive observations from the CRaTER instrument on the Lunar Reconnaissance Orbiter that characterizes the radiation environment and space weathering on the Moon.

  5. Experimental investigation of the radiation shielding efficiency of a MCP detector in the radiation environment near Jupiter's moon Europa

    Science.gov (United States)

    Tulej, M.; Meyer, S.; Lüthi, M.; Lasi, D.; Galli, A.; Piazza, D.; Desorgher, L.; Reggiani, D.; Hajdas, W.; Karlsson, S.; Kalla, L.; Wurz, P.

    2016-09-01

    Neutral Ion Mass spectrometer (NIM) is one of the instruments in the Particle Environmental Package (PEP) designed for the JUICE mission of ESA to the Jupiter system. NIM, equipped with a sensitive MCP ion detector, will conduct detailed measurements of the chemical composition of Jovian icy moons exospheres. To achieve high sensitivity of the instrument, radiation effects due to the high radiation background (high-energy electrons and protons) around Jupiter have to be minimised. We investigate the performance of an Al-Ta-Al composite stack as a potential shielding against high-energy electrons. Experiments were performed at the PiM1 beam line of the High Intensity Proton Accelerator Facilities located at the Paul Scherrer Institute, Villigen, Switzerland. The facility delivers a particle beam containing e-, μ- and π- with momentum from 17.5 to 345 MeV/c (Hajdas et al., 2014). The measurements of the radiation environment generated during the interaction of primary particles with the Al-Ta-Al material were conducted with dedicated beam diagnostic methods and with the NIM MCP detector. In parallel, modelling studies using GEANT4 and GRAS suites were performed to identify products of the interaction and predict ultimate fluxes and particle rates at the MCP detector. Combination of experiment and modelling studies yields detailed characterisation of the radiation fields produced by the interaction of the incident e- with the shielding material in the range of the beam momentum from 17.5 to 345 MeV/c. We derived the effective MCP detection efficiency to primary and secondary radiation and effective shielding transmission coefficients to incident high-energy electron beam in the range of applied beam momenta. This study shows that the applied shielding attenuates efficiently high-energy electrons. Nevertheless, owing to nearly linear increase of the bremsstrahlung production rate with incident beam energy, above 130 MeV their detection rates measured by the MCP

  6. Handbook of anatomical models for radiation dosimetry

    CERN Document Server

    Eckerman, Keith F

    2010-01-01

    Covering the history of human model development, this title presents the major anatomical and physical models that have been developed for human body radiation protection, diagnostic imaging, and nuclear medicine therapy. It explores how these models have evolved and the role that modern technologies have played in this development.

  7. The NIAID Radiation Countermeasures Program business model.

    Science.gov (United States)

    Hafer, Nathaniel; Maidment, Bert W; Hatchett, Richard J

    2010-12-01

    The National Institute of Allergy and Infectious Diseases (NIAID) Radiation/Nuclear Medical Countermeasures Development Program has developed an integrated approach to providing the resources and expertise required for the research, discovery, and development of radiation/nuclear medical countermeasures (MCMs). These resources and services lower the opportunity costs and reduce the barriers to entry for companies interested in working in this area and accelerate translational progress by providing goal-oriented stewardship of promising projects. In many ways, the radiation countermeasures program functions as a "virtual pharmaceutical firm," coordinating the early and mid-stage development of a wide array of radiation/nuclear MCMs. This commentary describes the radiation countermeasures program and discusses a novel business model that has facilitated product development partnerships between the federal government and academic investigators and biopharmaceutical companies.

  8. Chromosome aberrations as biomarkers of radiation exposure: Modelling basic mechanisms

    Science.gov (United States)

    Ballarini, F.; Ottolenghi, A.

    The space radiation environment is a mixed field consisting of different particles having different energies, including high charge and energy (HZE) ions. Conventional measurements of absorbed doses may not be sufficient to completely characterise the radiation field and perform reliable estimates of health risks. Biological dosimetry, based on the observation of specific radiation-induced endpoints (typically chromosome aberrations), can be a helpful approach in case of monitored exposure to space radiation or other mixed fields, as well as in case of accidental exposure. Furthermore, various ratios of aberrations (e.g. dicentric chromosomes to centric rings and complex exchanges to simple exchanges) have been suggested as possible fingerprints of radiation quality, although all of them have been subjected to some criticisms. In this context a mechanistic model and a Monte Carlo code for the simulation of chromosome aberration induction were developed. The model, able to provide dose-responses for different aberrations (e.g. dicentrics, rings, fragments, translocations, insertions and other complex exchanges), was further developed to assess the dependence of various ratios of aberrations on radiation quality. The predictions of the model were compared with available data, whose experimental conditions were faithfully reproduced. Particular attention was devoted to the scoring criteria adopted in different laboratories and to possible biases introduced by interphase death and mitotic delay. This latter aspect was investigated by taking into account both metaphase data and data obtained with Premature Chromosome Condensation (PCC).

  9. Degradation mechanisms of cable insulation materials during radiation-thermal ageing in radiation environment

    Science.gov (United States)

    Seguchi, Tadao; Tamura, Kiyotoshi; Ohshima, Takeshi; Shimada, Akihiko; Kudoh, Hisaaki

    2011-02-01

    Radiation and thermal degradation of ethylene-propylene rubber (EPR) and crosslinked polyethylene (XLPE) as cable insulation materials were investigated by evaluating tensile properties, gel-fraction, and swelling ratio, as well as by the infrared (FTIR) analysis. The activation energy of thermal oxidative degradation changed over the range 100-120 °C for both EPR and XLPE. This may be attributed to the fact that the content of an antioxidant used as the stabilizer for polymers decreases by evaporation during thermal ageing at high temperatures. The analysis of antioxidant content and oxidative products in XLPE as a model sample showed that a small amount of antioxidant significantly reduced the extent of thermal oxidation, but was not effective for radiation induced oxidation. The changes in mechanical properties were well reflected by the degree of oxidation. A new model of polymer degradation mechanisms was proposed where the degradation does not take place by chain reaction via peroxy radical and hydro-peroxide. The role of the antioxidant in the polymer is the reduction of free radical formation in the initiation step in thermal oxidation, and it could not stop radical reactions for either radiation or thermal oxidation.

  10. Degradation mechanisms of cable insulation materials during radiation-thermal ageing in radiation environment

    Energy Technology Data Exchange (ETDEWEB)

    Seguchi, Tadao, E-mail: seguchi@aj.wakwak.co [Japan Atomic Energy Agency, Tokai 319-1195 (Japan); Tamura, Kiyotoshi; Ohshima, Takeshi; Shimada, Akihiko [Japan Atomic Energy Agency, Tokai 319-1195 (Japan); Kudoh, Hisaaki [University of Tokyo, Tokai 319-1195 (Japan)

    2011-02-15

    Radiation and thermal degradation of ethylene-propylene rubber (EPR) and crosslinked polyethylene (XLPE) as cable insulation materials were investigated by evaluating tensile properties, gel-fraction, and swelling ratio, as well as by the infrared (FTIR) analysis. The activation energy of thermal oxidative degradation changed over the range 100-120 {sup o}C for both EPR and XLPE. This may be attributed to the fact that the content of an antioxidant used as the stabilizer for polymers decreases by evaporation during thermal ageing at high temperatures. The analysis of antioxidant content and oxidative products in XLPE as a model sample showed that a small amount of antioxidant significantly reduced the extent of thermal oxidation, but was not effective for radiation induced oxidation. The changes in mechanical properties were well reflected by the degree of oxidation. A new model of polymer degradation mechanisms was proposed where the degradation does not take place by chain reaction via peroxy radical and hydro-peroxide. The role of the antioxidant in the polymer is the reduction of free radical formation in the initiation step in thermal oxidation, and it could not stop radical reactions for either radiation or thermal oxidation.

  11. Synchrotron radiation lithography system in an atmospheric environment (invited)

    Science.gov (United States)

    Okada, K.; Kouno, E.; Nomura, E.; Suzuki, K.; Fujii, K.; Tanaka, Y.; Iwata, J.; Kawase, Y.

    1989-07-01

    The atmospheric environmental exposure system for synchrotron radiation (SR) lithography has been integrated using the Photon Factory storage ring (2.5 GeV). The system, composed of a highly reliable beamline, an SR extracting chamber and a prototype SR stepper, aims at attaining higher accuracy and throughput. Based on a fail-safe mechanism notion, a double-vacuum protection system, in which two sets of a fast closing valve and acoustic delay line are installed in the main beamline and branch beamline, respectively, has been organized. Vacuum breakdown tests indicated that any vacuum breakdown, a beryllium (Be) window rupture in the worst case, exerts little influence on the storage ring ultrahigh vacuum. The SR extracting chamber, equipped with a Be window and an extraction window, is filled with helium at atmospheric pressure. Particularly, the 50-μm-thick, 35-mm-diam Be window, vacuum-sealed by a Viton O-ring, was preliminarily employed and, so far, has operated successfully, giving a 25-mm square exposure area. In terms of practical availability and simplicity, the SR stepper in an atmospheric environment has been constructed. A novel differential mode linear Fresnel zone plate alignment method, which can detect an alignment error between a mask and a wafer during exposure, was developed.

  12. Modeling Impaired Hippocampal Neurogenesis after Radiation Exposure.

    Science.gov (United States)

    Cacao, Eliedonna; Cucinotta, Francis A

    2016-03-01

    Radiation impairment of neurogenesis in the hippocampal dentate gyrus is one of several factors associated with cognitive detriments after treatment of brain cancers in children and adults with radiation therapy. Mouse models have been used to study radiation-induced changes in neurogenesis, however the models are limited in the number of doses, dose fractions, age and time after exposure conditions that have been studied. The purpose of this study is to develop a novel predictive mathematical model of radiation-induced changes to neurogenesis using a system of nonlinear ordinary differential equations (ODEs) to represent the time, age and dose-dependent changes to several cell populations participating in neurogenesis as reported in mouse experiments exposed to low-LET radiation. We considered four compartments to model hippocampal neurogenesis and, consequently, the effects of radiation treatment in altering neurogenesis: (1) neural stem cells (NSCs), (2) neuronal progenitor cells or neuroblasts (NB), (3) immature neurons (ImN) and (4) glioblasts (GB). Because neurogenesis is decreasing with increasing mouse age, a description of the age-related dynamics of hippocampal neurogenesis is considered in the model, which is shown to be an important factor in comparisons to experimental data. A key feature of the model is the description of negative feedback regulation on early and late neuronal proliferation after radiation exposure. The model is augmented with parametric descriptions of the dose and time after irradiation dependences of activation of microglial cells and a possible shift of NSC proliferation from neurogenesis to gliogenesis reported at higher doses (∼10 Gy). Predictions for dose-fractionation regimes and for different mouse ages, and prospects for future work are then discussed.

  13. Dark Radiation Confronting LHC in Z' Models

    CERN Document Server

    Solaguren-Beascoa, A

    2012-01-01

    Recent cosmological data favour additional relativistic degrees of freedom beyond the three active neutrinos and photons, often referred to as "dark radiation". Extensions of the SM involving TeV-scale Z' gauge bosons generically contain superweakly interacting light right-handed neutrinos which can constitute this dark radiation. In this letter we confront the requirement on the parameters of the E6 Z' models to account for the present evidence of dark radiation with the already existing constraints from searches for new neutral gauge bosons at LHC7.

  14. An Evolution Model of Space Debris Environment

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Various types of models including engineering models andevolution models have been developed to understand space debris environment since 1960s. Evolution model, consisting of a set of supporting models such as Launch Model, Breakup Model and Atmosphere Model, can reliably predicts the evolution of space debris environment. Of these supporting models, Breakup Model is employed to describe the distribution of debris and debris cloud during a explosion or collision case which is one of the main factors affecting the amount of total space debris. An analytical orbit debris environment model referred to as the “Particles-In-Boxes" model has been introduced. By regarding the orbit debris as the freedom particles running in the huge volume, the sources and sinks mechanism is established. Then the PIB model is expanded to the case of multiple-species in multiple-tier system. Combined with breakup model, the evolution of orbit debris environment is predicted.

  15. Modeling the Inner Magnetosphere: Radiation Belts, Ring Current, and Composition

    Science.gov (United States)

    Glocer, Alex

    2011-01-01

    The space environment is a complex system defined by regions of differing length scales, characteristic energies, and physical processes. It is often difficult, or impossible, to treat all aspects of the space environment relative to a particular problem with a single model. In our studies, we utilize several models working in tandem to examine this highly interconnected system. The methodology and results will be presented for three focused topics: 1) Rapid radiation belt electron enhancements, 2) Ring current study of Energetic Neutral Atoms (ENAs), Dst, and plasma composition, and 3) Examination of the outflow of ionospheric ions. In the first study, we use a coupled MHD magnetosphere - kinetic radiation belt model to explain recent Akebono/RDM observations of greater than 2.5 MeV radiation belt electron enhancements occurring on timescales of less than a few hours. In the second study, we present initial results of a ring current study using a newly coupled kinetic ring current model with an MHD magnetosphere model. Results of a dst study for four geomagnetic events are shown. Moreover, direct comparison with TWINS ENA images are used to infer the role that composition plays in the ring current. In the final study, we directly model the transport of plasma from the ionosphere to the magnetosphere. We especially focus on the role of photoelectrons and and wave-particle interactions. The modeling methodology for each of these studies will be detailed along with the results.

  16. A Preliminary Study on the Radiation dose Distribution in the Pyroprocess Hot Cell Environment

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chankyu; Kim, Myung Soo; Kim, Giyoon; Lee, Eunjoong; Lee, Jeong Tae; Cho, Gyuseong [KAIST, Daejeon (Korea, Republic of); Ahn, Seongkyu; Park, Sehwan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    Pyroprocessing is the promising technology for treatment of spent fuels. Because it is based on the collective recovery of TRU, it has an advantage in proliferation resistance compared to conventional aqueous processes. Development of pyroprocessing has positive effects to the public through reduction of the high-level radioactive waste and the effective use of energy resources. In Korea, Korea Atomic Energy Research Institute (KAERI) has researched pyroprocessing since 1997. The engineering scale integrated inactive pyroprocess facility (PRIDE) was constructed and test operation has been performed. A study on the preliminary conceptual design and cost estimation for a larger-scale model facility is in progress. The safeguards are essential in the pyroprocessing facility for proliferation resistance. To establish the reliable safeguards, the preliminary studies on radiation resistance requirements, assessment of the safeguards system applicability, and shielding of the safeguards equipment are required. Therefore, first of all, the radiation flux and dose distribution in hot cell environment have to be studied. The previous studies focused on the neutron flux at the pyroprocessing however they are limited to the individual unit process. In this study, the flux and dose distribution of neutron and gamma-ray in the hot cell environment of the pilot pyroprocessing facility are investigated. Based on the simplified material flow of pyroprocess, the material distribution model is established. In this study, the radiation flux and dose distribution in the hot cell environment of the pilot-scale pyroprocessing facility model is investigated preliminarily by the MCNP6 simulation. Based on the established material flow model, the material composition at each stage is calculated and used for the simulation. The simple hot cell structure and process batch size were assumed based on the previous studies.

  17. Experimental investigation of the radiation shielding of a MCP detector in the radiation environment near Europa

    Science.gov (United States)

    Tulej, Marek; Wurz, Peter; Meyer, Stefan; Lasi, Davide; Lüthi, Matthias; Galli, André; Piazza, Daniele; Desorgher, Laurent; Hajdas, Wojciech; Reggiani, Davide; Karlsson, Stefan; Kalla, Leif

    2016-04-01

    The Neutral Ion Mass spectrometer (NIM) is one of the six instruments in the Particle Environmental Package (PEP) designed for the JUICE mission of ESA to the Jupiter system. NIM will conduct detailed measurements of chemical composition of Jovian moon exospheres and is equipped with a sensitive MCP ion detector. To maintain high sensitivity of the NIM instrument, background signals arising from the presence of a large background of penetrating radiation (mostly high-energy electrons and protons) in Jupiter's magnetosphere have to be minimised. We investigate the performance of a layered-Z radiation shield, an Al-Ta-Al sandwich, as a potential shielding against high-energy electrons. The experimental investigations were performed at the PiM1 beam line of the High Intensity Proton Accelerator Facilities located at the Paul Scherrer Institute (PSI), Villigen, Switzerland. The facility delivers a particle beam containing e,  and  with an adjustable momentum ranging from 17.5 to 345 MeV/c. The measurements of the induced radiation background generated during the interaction of primary particles with Al-Ta-Al sandwich were conducted by beam diagnostic methods and a MCP detector. Diagnostic methods provided for the characterisation of the beam parameters (beam geometry, flux and intensity) and identification of individual particles in the primary beam and in the flux of secondary particles. The MCP detector measurements provided information on the effects of radiation and the results of these measurements define the performance of the shielding material in reducing the background arising from penetrating radiation. In parallel, we performed modelling studies using GEANT 4 and GRASS methods to identify products of the interaction and predict their fluxes and particle rates at the MCP detector. Combination of the experiment and modelling studies yields detailed characterisation of the radiation effects produced by the interaction of the incident e- in the

  18. Research on Dependable Ionizing Radiation Protection based on Model i*

    Directory of Open Access Journals (Sweden)

    Tan Hai

    2013-07-01

    Full Text Available The software’s unreliability mostly attributes to an erroneous analysis on the requirements done at the beginning. In this paper, we apply the tool of i* frame requirement modeling and build early requirement model against ionizing radiation. After finding out possible risks and corresponding solutions during the process of modeling analysis, we propose reasoning models against ionizing radiation. The radiation protection system  with  the  above models  can  figure out  the  purpose  of agents  related  to radiant source and provide normal service even when the environment software system is being interfered. It can serve the ecological and economical society with stability and development.  The model is divided into several sections. Section 1 gives the outline of the dependant software. Section 2 illustrates the  i* frame  technology. Section 3, 4 and 5 cover the topic of dependant security requirement analysis, SD&SR model on ionizing radiation respectively. Section 6 gives the conclusion.

  19. RRTM: A rapid radiative transfer model

    Energy Technology Data Exchange (ETDEWEB)

    Mlawer, E.J.; Taubman, S.J.; Clough, S.A. [Atmospheric and Environmental Research, Inc., Cambridge, MA (United States)

    1996-04-01

    A rapid radiative transfer model (RRTM) for the calculation of longwave clear-sky fluxes and cooling rates has been developed. The model, which uses the correlated-k method, is both accurate and computationally fast. The foundation for RRTM is the line-by-line radiative transfer model (LBLRTM) from which the relevant k-distributions are obtained. LBLRTM, which has been extensively validated against spectral observations e.g., the high-resolution sounder and the Atmospheric Emitted Radiance Interferometer, is used to validate the flux and cooling rate results from RRTM. Validations of RRTM`s results have been performed for the tropical, midlatitude summer, and midlatitude winter atmospheres, as well as for the four Intercomparison of Radiation Codes in Climate Models (ICRCCM) cases from the Spectral Radiance Experiment (SPECTRE). Details of some of these validations are presented below. RRTM has the identical atmospheric input module as LBLRTM, facilitating intercomparisons with LBLRTM and application of the model at the Atmospheric Radiation Measurement Cloud and Radiation Testbed sites.

  20. Effects of Polarization-Maintaining Fibre Degrading on Precision of Fibre Optic Gyroscopes in Radiation Environment

    Institute of Scientific and Technical Information of China (English)

    XIAO Wen; LIU De-Wen; LIU Yang; YI Xiao-Su; CONG Lin

    2008-01-01

    @@ In the space environment, the precision of fibre optic gyroscopes (FOGs) degrades because of space radiation.Photonic components of FOGs axe affected by radiation, especially the polaxization-maintaining (PM) fibre coil.In relation to the space radiation environment characteristic, we have carried out a series of radiation experiments on a PM fibre coil with 60Co radiation source at different dose rates. Based on the experimental results, the formula between the PM-fibre loss and radiation dose rata is built, and the relation between the precision of FOG and radiation dose is obtained accordingly. The results strongly show that the precision of our FOG degrades owing to the attenuation of the polarization-maintaining fibre, which provides theoretical foundation for the radiation-resistant design of the FOG.

  1. Validation of a Solid Rocket Motor Internal Environment Model

    Science.gov (United States)

    Martin, Heath T.

    2017-01-01

    In a prior effort, a thermal/fluid model of the interior of Penn State University's laboratory-scale Insulation Test Motor (ITM) was constructed to predict both the convective and radiative heat transfer to the interior walls of the ITM with a minimum of empiricism. These predictions were then compared to values of total and radiative heat flux measured in a previous series of ITM test firings to assess the capabilities and shortcomings of the chosen modeling approach. Though the calculated fluxes reasonably agreed with those measured during testing, this exercise revealed means of improving the fidelity of the model to, in the case of the thermal radiation, enable direct comparison of the measured and calculated fluxes and, for the total heat flux, compute a value indicative of the average measured condition. By replacing the P1-Approximation with the discrete ordinates (DO) model for the solution of the gray radiative transfer equation, the radiation intensity field in the optically thin region near the radiometer is accurately estimated, allowing the thermal radiation flux to be calculated on the heat-flux sensor itself, which was then compared directly to the measured values. Though the fully coupling the wall thermal response with the flow model was not attempted due to the excessive computational time required, a separate wall thermal response model was used to better estimate the average temperature of the graphite surfaces upstream of the heat flux gauges and improve the accuracy of both the total and radiative heat flux computations. The success of this modeling approach increases confidence in the ability of state-of-the-art thermal and fluid modeling to accurately predict SRM internal environments, offers corrections to older methods, and supplies a tool for further studies of the dynamics of SRM interiors.

  2. Canonical Ensemble Model for Black Hole Radiation

    Indian Academy of Sciences (India)

    Jingyi Zhang

    2014-09-01

    In this paper, a canonical ensemble model for the black hole quantum tunnelling radiation is introduced. In this model the probability distribution function corresponding to the emission shell is calculated to second order. The formula of pressure and internal energy of the thermal system is modified, and the fundamental equation of thermodynamics is also discussed.

  3. Complex composite engineering architectures for nuclear and high-radiation environments

    Energy Technology Data Exchange (ETDEWEB)

    Kornreich, Drew E [Los Alamos National Laboratory; Vaidya, Rajendra U [Los Alamos National Laboratory; Ammerman, Curtt N [Los Alamos National Laboratory

    2010-01-01

    Integrated Computational Materials Engineering (ICME) is a novel overarching approach to bridge length and time scales in computational materials science and engineering. This approach integrates all elements of multi-scale modeling (including various empirical and science-based models) with materials informatics to provide users the opportunity to tailor material selections based on stringent application needs. Typically, materials engineering has focused on structural requirements (stress, strain, modulus, fracture toughness etc.) while multi-scale modeling has been science focused (mechanical threshold strength model, grain-size models, solid-solution strengthening models etc.). Materials informatics (mechanical property inventories) on the other hand, is extensively data focused. All of these elements are combined within the framework of ICME to create architecture for the development, selection and design new composite materials for challenging environments. We propose development of the foundations for applying ICME to composite materials development for nuclear and high-radiation environments (including nuclear-fusion energy reactors, nuclear-fission reactors, and accelerators). We expect to combine all elements of current material models (including thermo-mechanical and finite-element models) into the ICME framework. This will be accomplished through the use of a various mathematical modeling constructs. These constructs will allow the integration of constituent models, which in tum would allow us to use the adaptive strengths of using a combinatorial scheme (fabrication and computational) for creating new composite materials. A sample problem where these concepts are used is provided in this summary.

  4. Infrared radiation models for atmospheric ozone

    Science.gov (United States)

    Kratz, David P.; Ces, Robert D.

    1988-01-01

    A hierarchy of line-by-line, narrow-band, and broadband infrared radiation models are discussed for ozone, a radiatively important atmospheric trace gas. It is shown that the narrow-band (Malkmus) model is in near-precise agreement with the line-by-line model, thus providing a means of testing narrow-band Curtis-Godson scaling, and it is found that this scaling procedure leads to errors in atmospheric fluxes of up to 10 percent. Moreover, this is a direct consequence of the altitude dependence of the ozone mixing ratio. Somewhat greater flux errors arise with use of the broadband model, due to both a lesser accuracy of the broadband scaling procedure and to inherent errors within the broadband model, despite the fact that this model has been tuned to the line-by-line model.

  5. Automated Environment Generation for Software Model Checking

    Science.gov (United States)

    Tkachuk, Oksana; Dwyer, Matthew B.; Pasareanu, Corina S.

    2003-01-01

    A key problem in model checking open systems is environment modeling (i.e., representing the behavior of the execution context of the system under analysis). Software systems are fundamentally open since their behavior is dependent on patterns of invocation of system components and values defined outside the system but referenced within the system. Whether reasoning about the behavior of whole programs or about program components, an abstract model of the environment can be essential in enabling sufficiently precise yet tractable verification. In this paper, we describe an approach to generating environments of Java program fragments. This approach integrates formally specified assumptions about environment behavior with sound abstractions of environment implementations to form a model of the environment. The approach is implemented in the Bandera Environment Generator (BEG) which we describe along with our experience using BEG to reason about properties of several non-trivial concurrent Java programs.

  6. Model for a Healthy Work Environment.

    Science.gov (United States)

    Blevins, Jamie

    2016-01-01

    The Healthy Work Environment (HWE) Model, considered a model of standards of professional behaviors, was created to help foster an environment that is happy, healthy, realistic, and feasible. The model focuses on areas of PEOPLE and PRACTICE, where each letter of these words identifies core, professional qualities and behaviors to foster an environment amenable and conducive to accountability for one's behavior and action. Each of these characteristics is supported from a Christian, biblical perspective. The HWE Model provides a mental and physical checklist of what is important in creating and sustaining a healthy work environment in education and practice.

  7. MCC: A Model Transformation Environment

    NARCIS (Netherlands)

    Kleppe, A.G.

    2006-01-01

    In the model driven software development process, software is built by constructing one or more models and transforming these into other models. In turn these output models may be transformed into another set of models until finally the output consists of program code that can be executed. Ultimatel

  8. The Ultraviolet Radiation Environment Around M dwarf Exoplanet Host Stars

    CERN Document Server

    France, Kevin; Linsky, Jeffrey L; Roberge, Aki; Stocke, John T; Tian, Feng; Bushinsky, Rachel; Desert, Jean-Michel; Mauas, Pablo; Vieytes, Mariela; Walkowicz, Lucianne M

    2012-01-01

    The spectral and temporal behavior of exoplanet host stars is a critical input to models of the chemistry and evolution of planetary atmospheres. At present, little observational or theoretical basis exists for understanding the ultraviolet spectra of M dwarfs, despite their critical importance to predicting and interpreting the spectra of potentially habitable planets as they are obtained in the coming decades. Using observations from the Hubble Space Telescope, we present a study of the UV radiation fields around nearby M dwarf planet hosts that covers both FUV and NUV wavelengths. The combined FUV+NUV spectra are publically available in machine-readable format. We find that all six exoplanet host stars in our sample (GJ 581, GJ 876, GJ 436, GJ 832, GJ 667C, and GJ 1214) exhibit some level of chromospheric and transition region UV emission. No "UV quiet" M dwarfs are observed. The bright stellar Ly-alpha emission lines are reconstructed, and we find that the Ly-alpha line fluxes comprise ~37-75% of the tota...

  9. Modeling the radiation pattern of LEDs.

    Science.gov (United States)

    Moreno, Ivan; Sun, Ching-Cherng

    2008-02-01

    Light-emitting diodes (LEDs) come in many varieties and with a wide range of radiation patterns. We propose a general, simple but accurate analytic representation for the radiation pattern of the light emitted from an LED. To accurately render both the angular intensity distribution and the irradiance spatial pattern, a simple phenomenological model takes into account the emitting surfaces (chip, chip array, or phosphor surface), and the light redirected by both the reflecting cup and the encapsulating lens. Mathematically, the pattern is described as the sum of a maximum of two or three Gaussian or cosine-power functions. The resulting equation is widely applicable for any kind of LED of practical interest. We accurately model a wide variety of radiation patterns from several world-class manufacturers.

  10. A body temperature model for lizards as estimated from the thermal environment

    NARCIS (Netherlands)

    Fei, T.; Skidmore, A.K.; Venus, V.; Wang, T.; Schlerf, M.; Toxopeus, A.G.; Overjijk, van S.; Bian, B.M.; Liu, Y.

    2012-01-01

    A physically based model was built to predict the transient body temperature of lizards in a thermally heterogeneous environment. Six heat transfer terms were taken into account in this model: solar radiation, convective heat flow, longwave radiation, conductive heat flow, metabolic heat gain and re

  11. A body temperature model for lizards as estimated from the thermal environment

    NARCIS (Netherlands)

    Fei, T.; Skidmore, A.K.; Venus, V.; Wang, T.; Schlerf, M.; Toxopeus, A.G.; Overjijk, van S.; Bian, B.M.; Liu, Y.

    2012-01-01

    A physically based model was built to predict the transient body temperature of lizards in a thermally heterogeneous environment. Six heat transfer terms were taken into account in this model: solar radiation, convective heat flow, longwave radiation, conductive heat flow, metabolic heat gain and re

  12. Fracture model of radiation blistering

    Energy Technology Data Exchange (ETDEWEB)

    Kamada, K.; Higashida, Y.

    1979-06-01

    The formation process of blisters is interpreted by a fracture model on the basis of the stress fields around a lenticular bubble calculated in a previous paper. This model implicitly presumes a microcrack nucleated at a depth near the projected range of the ions. Two factors are separated theoretically to explain the blister formation: One is a geometrical factor which depends only on the ratio of size to depth, from a free surface, and the other factor is proportional to the square of the ratio between the internal gas pressure of the bubble to plastic yield stress of the target materials, depending entirely on the physical and chemical properties of the materials and gas atoms. The relation between the blister diameter and the cover thickness must be basically linear as expected from the first factor, but is modulated by the second factor, giving a slight departure from linearity as observed by experiment. The ratio of the gas pressure to the yield stress must be 0.02--0.2 in magnitude and depends on the ion energy and the target materials. This value leads to an estimation that the amount of gas atoms contained in the blister is about 10% of the injected ions. Griffith's criterion for the crack propagation in the subsurface layer with taking into account of ductility of the materials near the crack tip was derived, and showed that the estimated internal pressure of the blister is far smaller than the necessary pressure to satisfy the criterion. The objections against the gas-pressure model were criticized on the basis of the present model.

  13. The Chandra X-Ray Observatory Radiation Environmental Model Update

    Science.gov (United States)

    Blackwell, William C.; Minow, Joseph I.; ODell, Stephen L.; Cameron, Robert A.; Virani, Shanil N.

    2003-01-01

    CRMFLX (Chandra Radiation Model of ion FLUX) is a radiation environment risk mitigation tool for use as a decision aid in planning the operation times for Chandra's Advanced CCD Imaging Spectrometer (ACIS) detector. The accurate prediction of the proton flux environment with energies of 100 - 200 keV is needed in order to protect the ACIS detector against proton degradation. Unfortunately, protons of this energy are abundant in the region of space where Chandra must operate. In addition, on-board particle detectors do not measure proton flux levels of the required energy range. CRMFLX is an engineering environment model developed to predict the proton flux in the solar wind, magnetosheath, and magnetosphere phenomenological regions of geospace. This paper describes the upgrades to the ion flux databases for the magnetosphere, magnetosheath, and solar wind regions. These data files were created by using Geotail and Polar spacecraft flux measurements only when the Advanced Composition Explorer (ACE) spacecraft's 0.14 MeV particle flux was below a threshold value. This new database allows for CRMFLX output to be correlated with both the geomagnetic activity level, as represented by the Kp index, as well as with solar proton events. Also, reported in this paper are results of analysis leading to a change in Chandra operations that successfully mitigates the false trigger rate for autonomous radiation events caused by relativistic electron flux contamination of proton channels.

  14. Activation and radiation damage in the environment of hadron accelerators

    CERN Document Server

    Kiselev, Daniela

    2013-01-01

    A component which suffers radiation damage usually also becomes radioactive, since the source of activation and radiation damage is the interaction of the material with particles from an accelerator or with reaction products. However, the underlying mechanisms of the two phenomena are different. These mechanisms are described here. Activation and radiation damage can have far-reaching consequences. Components such as targets, collimators, and beam dumps are the first candidates for failure as a result of radiation damage. This means that they have to be replaced or repaired. This takes time, during which personnel accumulate dose. If the dose to personnel at work would exceed permitted limits, remote handling becomes necessary. The remaining material has to be disposed of as radioactive waste, for which an elaborate procedure acceptable to the authorities is required. One of the requirements of the authorities is a complete nuclide inventory. The methods used for calculation of such inventories are presented,...

  15. Space radiation environment prediction for VLSI microelectronics devices onboard a LEO satellite using OMERE-TRAD software

    Science.gov (United States)

    Sajid, Muhammad; Chechenin, N. G.; Torres, Frank Sill; Khan, E. U.; Agha, Shahrukh

    2015-07-01

    Space radiation environment at Low Earth Orbits (LEO) with perigee at 300 km, apogee at 600 km altitude having different orbital inclinations was modeled in the form of electrons and protons trapped in Van Allen Earth Radiation Belts (ERBs), heavy ions and protons in Galactic Cosmic Rays (GCRs), and Energetic Solar Particles (ESP) Events during solar maximum period. The co-relation between various shielding thicknesses and particles transport flux was analyzed for this specific orbit. We observed that there is an optimum shield thickness above which the attenuation of the transmitted flux of incident particles is negligible. To estimate the orbit average differential and integral fluxes to be encountered by onboard devices an appropriate radiation environment models were chosen in OMERE-TRAD toolkit and the impact of various shielding thickness for different orbital inclinations on integral Linear-Energy-Transfer (LET) spectra were determined.

  16. Evaluation of the effects of solar radiation on glass. [space environment simulation

    Science.gov (United States)

    Firestone, R. F.; Harada, Y.

    1979-01-01

    The degradation of glass used on space structures due to electromagnetic and particulate radiation in a space environment was evaluated. The space environment was defined and a simulated space exposure apparatus was constructed. Four optical materials were exposed to simulated solar and particulate radiation in a space environment. Sapphire and fused silica experienced little change in transmittance, while optical crown glass and ultra low expansion glass darkened appreciably. Specimen selection and preparation, exposure conditions, and the effect of simulated exposure are discussed. A selective bibliography of the effect of radiation on glass is included.

  17. Qualification of the radiation environment in the TCC2 experimental test area.

    CERN Document Server

    Fynbo, C A

    2000-01-01

    This report qualifies the radiation environment to be found in the area behind the beam dump in the TCC2 experimental hall where tests are being performed on the radiation hardness and sensitivity to Single Event Upsets of electronics to be installed near the LHC machine. A comparison is made with the radiation environment expected for the LHC, and we conclude that the environment found in the test area matches that of LHC such that tests performed here will provide a valid simulation of electronics performance under LHC running conditions.

  18. Radiatively induced quark and lepton mass model

    Science.gov (United States)

    Nomura, Takaaki; Okada, Hiroshi

    2016-10-01

    We propose a radiatively induced quark and lepton mass model in the first and second generation with extra U (1) gauge symmetry and vector-like fermions. Then we analyze the allowed regions which simultaneously satisfy the FCNCs for the quark sector, LFVs including μ- e conversion, the quark mass and mixing, and the lepton mass and mixing. Also we estimate the typical value for the (g - 2) μ in our model.

  19. Radiative transfer model for Solar System ices

    Science.gov (United States)

    Andrieu, F.; Schmidt, F.; Douté, S.; Schmitt, B.; Brissaud, O.

    2015-10-01

    We developed a radiative transfer model [1] that simulates the bidirectional reflectance of a contaminated slab layer of ice overlaying a granular medium, under geometrical optics conditions. Designed for planetary studies, this model has a fast computer implementation and thus is suitable for planetary high spatial/spectral resolution hyperspectral data analysis. We will present here its principles, its numerical and experimental validations and its possible applications.

  20. Role of the UV external radiation field on the presence of astrophysical ices in protostellars environments

    Science.gov (United States)

    Robson Monteiro Rocha, Will; Pilling, Sergio

    2016-07-01

    The astrophysical ices survival is directly related with the temperature and ionizing radiation field in protostellars environments such as disks and envelopes. Computational models has shown that pure volatile molecules like CO and CH _{4} should survive only inside densest regions of molecular clouds or protoplanetary disks On the other hand, solid molecules such as H _{2}O and CH _{3}OH can be placed around 5 - 10 AU from the central protostar. Unlike of the previous models, we investigate the role of the UV external radiation field on the presence of ices in disks and envelopes. Once that a star-forming region is composed by the formation of many protostars, the external radiation field should be an important component to understand the real localization of the ices along the sight line. To address this topic it was employed the radiative transfer code RADMC-3D based on the Monte Carlo method. The code was used to model the spectrum and the near-infrared image of Elias 29. The initial parameters of the disk and envelope was taken from our previous paper (Rocha & Pilling (2015), ApJ 803:18). The opacities of the ices were calculated from the complex refractive index obtained at laboratory experiments perfomed at Grand Accélerateur National d'Íons Lourds (GANIL), by using the NKABS code from Rocha & Pilling (2014), SAA 123:436. The partial conclusions that we have obtained shows that pure CO volatile molecule cannot be placed at disk or envelope of Elias 29, unlike shown in our paper about Elias 29. Once it was observed in Elias 29 spectrum obtained with Infrared Space Observatory (ISO) between 2.5 - 190 μm, this molecule should be placed in foreground molecular clouds or trapped in the water ice matrix. The next calculations will be able to show where are placed the ices such as CH _{3}OH and CH _{3}CHO observed in Elias 29 spectrum.

  1. THE ULTRAVIOLET RADIATION ENVIRONMENT AROUND M DWARF EXOPLANET HOST STARS

    Energy Technology Data Exchange (ETDEWEB)

    France, Kevin; Froning, Cynthia S.; Stocke, John T.; Bushinsky, Rachel [Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309 (United States); Linsky, Jeffrey L. [JILA, University of Colorado and NIST, 440 UCB, Boulder, CO 80309 (United States); Roberge, Aki [Exoplanets and Stellar Astrophysics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Tian, Feng [Center for Earth System Sciences, Tsinghua University, Beijing 100084 (China); Desert, Jean-Michel [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Mauas, Pablo; Vieytes, Mariela [Instituto de Astronomsica del Espacio (CONICET-UBA), C.C. 67 Sucursal 28, 1428 Buenos Aires (Argentina); Walkowicz, Lucianne M., E-mail: kevin.france@colorado.edu [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

    2013-02-15

    The spectral and temporal behavior of exoplanet host stars is a critical input to models of the chemistry and evolution of planetary atmospheres. Ultraviolet photons influence the atmospheric temperature profiles and production of potential biomarkers on Earth-like planets around these stars. At present, little observational or theoretical basis exists for understanding the ultraviolet spectra of M dwarfs, despite their critical importance to predicting and interpreting the spectra of potentially habitable planets as they are obtained in the coming decades. Using observations from the Hubble Space Telescope, we present a study of the UV radiation fields around nearby M dwarf planet hosts that covers both far-UV (FUV) and near-UV (NUV) wavelengths. The combined FUV+NUV spectra are publicly available in machine-readable format. We find that all six exoplanet host stars in our sample (GJ 581, GJ 876, GJ 436, GJ 832, GJ 667C, and GJ 1214) exhibit some level of chromospheric and transition region UV emission. No 'UV-quiet' M dwarfs are observed. The bright stellar Ly{alpha} emission lines are reconstructed, and we find that the Ly{alpha} line fluxes comprise {approx}37%-75% of the total 1150-3100 A flux from most M dwarfs; {approx}>10{sup 3} times the solar value. We develop an empirical scaling relation between Ly{alpha} and Mg II emission, to be used when interstellar H I attenuation precludes the direct observation of Ly{alpha}. The intrinsic unreddened flux ratio is F(Ly{alpha})/F(Mg II) = 10 {+-} 3. The F(FUV)/F(NUV) flux ratio, a driver for abiotic production of the suggested biomarkers O{sub 2} and O{sub 3}, is shown to be {approx}0.5-3 for all M dwarfs in our sample, >10{sup 3} times the solar ratio. For the four stars with moderate signal-to-noise Cosmic Origins Spectrograph time-resolved spectra, we find UV emission line variability with amplitudes of 50%-500% on 10{sup 2}-10{sup 3} s timescales. This effect should be taken into account in future UV

  2. The Ultraviolet Radiation Environment around M Dwarf Exoplanet Host Stars

    Science.gov (United States)

    France, Kevin; Froning, Cynthia S.; Linsky, Jeffrey L.; Roberge, Aki; Stocke, John T.; Tian, Feng; Bushinsky, Rachel; Desert, Jean-Michel; Mauas, Pablo; Mauas, Pablo; Walkowicz, Lucianne M.

    2013-01-01

    The spectral and temporal behavior of exoplanet host stars is a critical input to models of the chemistry and evolution of planetary atmospheres. Ultraviolet photons influence the atmospheric temperature profiles and production of potential biomarkers on Earth-like planets around these stars. At present, little observational or theoretical basis exists for understanding the ultraviolet spectra of M dwarfs, despite their critical importance to predicting and interpreting the spectra of potentially habitable planets as they are obtained in the coming decades. Using observations from the Hubble Space Telescope, we present a study of the UV radiation fields around nearby M dwarf planet hosts that covers both far-UV (FUV) and near-UV (NUV) wavelengths. The combined FUV+NUV spectra are publicly available in machine-readable format. We find that all six exoplanet host stars in our sample (GJ 581, GJ 876, GJ 436, GJ 832, GJ 667C, and GJ 1214) exhibit some level of chromospheric and transition region UV emission. No "UV-quiet" M dwarfs are observed. The bright stellar Lyman-alpha emission lines are reconstructed, and we find that the Lyman-alpha line fluxes comprise approximately 37%-75% of the total 1150-3100 A flux from most M dwarfs; approximately greater than 10(exp3) times the solar value. We develop an empirical scaling relation between Lyman-alpha and Mg II emission, to be used when interstellar H I attenuation precludes the direct observation of Lyman-alpha. The intrinsic unreddened flux ratio is F(Lyman-alpha)/F(Mg II) = 10(exp3). The F(FUV)/F(NUV) flux ratio, a driver for abiotic production of the suggested biomarkers O2 and O3, is shown to be approximately 0.5-3 for all M dwarfs in our sample, greather than 10(exp3) times the solar ratio. For the four stars with moderate signal-to-noise Cosmic Origins Spectrograph time-resolved spectra, we find UV emission line variability with amplitudes of 50%.500% on 10(exp2)-10(exp3) s timescales. This effect should be taken

  3. Spacecraft Internal Acoustic Environment Modeling

    Science.gov (United States)

    Chu, S. Reynold; Allen, Chris

    2009-01-01

    The objective of the project is to develop an acoustic modeling capability, based on commercial off-the-shelf software, to be used as a tool for oversight of the future manned Constellation vehicles. The use of such a model will help ensure compliance with acoustic requirements. Also, this project includes modeling validation and development feedback via building physical mockups and conducting acoustic measurements to compare with the predictions.

  4. Simulation model for plant growth in controlled environment systems

    Science.gov (United States)

    Raper, C. D., Jr.; Wann, M.

    1986-01-01

    The role of the mathematical model is to relate the individual processes to environmental conditions and the behavior of the whole plant. Using the controlled-environment facilities of the phytotron at North Carolina State University for experimentation at the whole-plant level and methods for handling complex models, researchers developed a plant growth model to describe the relationships between hierarchial levels of the crop production system. The fundamental processes that are considered are: (1) interception of photosynthetically active radiation by leaves, (2) absorption of photosynthetically active radiation, (3) photosynthetic transformation of absorbed radiation into chemical energy of carbon bonding in solube carbohydrates in the leaves, (4) translocation between carbohydrate pools in leaves, stems, and roots, (5) flow of energy from carbohydrate pools for respiration, (6) flow from carbohydrate pools for growth, and (7) aging of tissues. These processes are described at the level of organ structure and of elementary function processes. The driving variables of incident photosynthetically active radiation and ambient temperature as inputs pertain to characterization at the whole-plant level. The output of the model is accumulated dry matter partitioned among leaves, stems, and roots; thus, the elementary processes clearly operate under the constraints of the plant structure which is itself the output of the model.

  5. LHCb: Evaluation of the Radiation Environment of the LHCb Experiment

    CERN Multimedia

    Karacson, M

    2011-01-01

    The characterization of all aspects of the radiation field of the LHCb experiment is needed to understand the impact of the unprecedented radiation levels to which its detector and electronics are exposed to. The methodology on how this is done is described. Analysis of the measurements of active and passive sensors of various types which are distributed in and around the detector will be carried out. Appropriate cross calibrations will be applied and comparisons between them will be performed. Critical comparisons with simulation results obtained with the FLUKA Monte Carlo code are also an essential element of the study.

  6. Seasonal radiative modeling of Titan's stratosphere

    Science.gov (United States)

    Bézard, Bruno; Vinatier, Sandrine; Achterberg, Richard

    2016-10-01

    We have developed a seasonal radiative model of Titan's stratosphere to investigate the time variation of stratospheric temperatures in the 10-3 - 5 mbar range as observed by the Cassini/CIRS spectrometer. The model incorporates gas and aerosol vertical profiles derived from Cassini/CIRS spectra to calculate the heating and cooling rate profiles as a function of time and latitude. In the equatorial region, the radiative equilibrium profile is warmer than the observed one. Adding adiabatic cooling in the energy equation, with a vertical velocity profile decreasing with depth and having w ≈ 0.4 mm sec-1 at 1 mbar, allows us to reproduce the observed profile. The model predicts a 5 K decrease at 1 mbar between 2008 and 2016 as a result of orbit eccentricity, in relatively good agreement with the observations. At other latitudes, as expected, the radiative model predicts seasonal variations of temperature larger than observed, pointing to latitudinal redistribution of heat by dynamics. Vertical velocities seasonally varying between -0.4 and 1.2 mm sec-1 at 1 mbar provide adiabatic cooling and heating adequate to reproduce the time variation of 1-mbar temperatures from 2005 to 2016 at 30°N and S. The model is also used to investigate the role of the strong compositional changes observed at high southern latitudes after equinox in the concomitant rapid cooling of the stratosphere.

  7. Thermal modeling environment for TMT

    Science.gov (United States)

    Vogiatzis, Konstantinos

    2010-07-01

    In a previous study we had presented a summary of the TMT Aero-Thermal modeling effort to support thermal seeing and dynamic loading estimates. In this paper a summary of the current status of Computational Fluid Dynamics (CFD) simulations for TMT is presented, with the focus shifted in particular towards the synergy between CFD and the TMT Finite Element Analysis (FEA) structural and optical models, so that the thermal and consequent optical deformations of the telescope can be calculated. To minimize thermal deformations and mirror seeing the TMT enclosure will be air conditioned during day-time to the expected night-time ambient temperature. Transient simulations with closed shutter were performed to investigate the optimum cooling configuration and power requirements for the standard telescope parking position. A complete model of the observatory on Mauna Kea was used to calculate night-time air temperature inside the enclosure (along with velocity and pressure) for a matrix of given telescope orientations and enclosure configurations. Generated records of temperature variations inside the air volume of the optical paths are also fed into the TMT thermal seeing model. The temperature and heat transfer coefficient outputs from both models are used as input surface boundary conditions in the telescope structure and optics FEA models. The results are parameterized so that sequential records several days long can be generated and used by the FEA model to estimate the observing spatial and temporal temperature range of the structure and optics.

  8. Exploration Technology Developments Program's Radiation Hardened Electronics for Space Environments (RHESE) Project Overview

    Science.gov (United States)

    Keys, Andrew S.; Adams, James H.; Darty, Ronald C.; Patrick, Marshall C.; Johnson, Michael A.; Cressler, John D.

    2008-01-01

    Primary Objective: 1) A computational tool to accurately predict electronics performance in the presence of space radiation in support of spacecraft design: a) Total dose; b) Single Event Effects; and c) Mean Time Between Failure. (Developed as successor to CR ME96.) Secondary Objectives: 2) To provide a detailed description of the natural radiation environment in support of radiation health and instrument design: a) In deep space; b) Inside the magnetosphere; and c) Behind shielding.

  9. Spacecraft Environments Interactive: Space Radiation and Its Effects on Electronic System

    Science.gov (United States)

    Howard, J. W., Jr.; Hardage, D. M.

    1999-01-01

    The natural space environment is characterized by complex and subtle phenomena hostile to spacecraft. Effects of these phenomena impact spacecraft design, development, and operation. Space systems become increasingly susceptible to the space environment as use of composite materials and smaller, faster electronics increases. This trend makes an understanding of space radiation and its effects on electronic systems essential to accomplish overall mission objectives, especially in the current climate of smaller/better/cheaper faster. This primer outlines the radiation environments encountered in space, discusses regions and types of radiation, applies the information to effects that these environments have on electronic systems, addresses design guidelines and system reliability, and stresses the importance of early involvement of radiation specialists in mission planning, system design, and design review (part-by-part verification).

  10. CAUSA - An Environment For Modeling And Simulation

    Science.gov (United States)

    Dilger, Werner; Moeller, Juergen

    1989-03-01

    CAUSA is an environment for modeling and simulation of dynamic systems on a quantitative level. The environment provides a conceptual framework including primitives like objects, processes and causal dependencies which allow the modeling of a broad class of complex systems. The facility of simulation allows the quantitative and qualitative inspection and empirical investigation of the behavior of the modeled system. CAUSA is implemented in Knowledge-Craft and runs on a Symbolics 3640.

  11. Benchmarking Ionizing Space Environment Models

    Science.gov (United States)

    Bourdarie, S.; Inguimbert, C.; Standarovski, D.; Vaillé, J.-R.; Sicard-Piet, A.; Falguere, D.; Ecoffet, R.; Poivey, C.; Lorfèvre, E.

    2017-08-01

    In-flight feedback data are collected, such as displacement damage doses, ionizing doses, and cumulated Single Event upset (SEU) on board various space vehicles and are compared to predictions performed with: 1) proton measurements performed with spectrometers data on board the same spacecraft if any and 2) protons spectrum predicted by the legacy AP8min model and the AP9 and Onera Proton Altitude Low models. When an accurate representation of the 3-D spacecraft shielding as well as appropriate ground calibrations are considered in the calculations, such comparisons provide powerful metrics to investigate engineering model accuracy. To describe >30 MeV trapped protons fluxes, the AP8 min model is found to provide closer predictions to observations than AP9 V1.30.001 (mean and perturbed mean).

  12. Thermal modeling environment for TMT

    OpenAIRE

    Vogiatzis, Konstantinos

    2010-01-01

    In a previous study we had presented a summary of the TMT Aero-Thermal modeling effort to support thermal seeing and dynamic loading estimates. In this paper a summary of the current status of Computational Fluid Dynamics (CFD) simulations for TMT is presented, with the focus shifted in particular towards the synergy between CFD and the TMT Finite Element Analysis (FEA) structural and optical models, so that the thermal and consequent optical deformations of the telescope can be calculated. T...

  13. Principles of the radiative ablation modeling

    Science.gov (United States)

    Saillard, Yves; Arnault, Philippe; Silvert, Virginie

    2010-12-01

    Indirectly driven inertial confinement fusion (ICF) rests on the setting up of a radiation temperature within a laser cavity and on the optimization of the capsule implosion ablated by this radiation. In both circumstances, the ablation of an optically thick medium is at work. The nonlinear radiation conduction equations that describe this phenomenon admit different kinds of solutions called generically Marshak waves. In this paper, a completely analytic model is proposed to describe the ablation in the subsonic regime relevant to ICF experiments. This model approximates the flow by a deflagrationlike structure where Hugoniot relations are used in the stationary part from the ablation front up to the isothermal sonic Chapman-Jouguet point and where the unstationary expansion from the sonic point up to the external boundary is assumed quasi-isothermal. It uses power law matter properties. It can also accommodate arbitrary boundary conditions provided the ablation wave stays very subsonic and the surface temperature does not vary too quickly. These requirements are often met in realistic situations. Interestingly, the ablated mass rate, the ablation pressure, and the absorbed radiative energy depend on the time history of the surface temperature, not only on the instantaneous temperature values. The results compare very well with self-similar solutions and with numerical simulations obtained by hydrodynamic code. This analytic model gives insight into the physical processes involved in the ablation and is helpful for optimization and sensitivity studies in many situations of interest: radiation temperature within a laser cavity, acceleration of finite size medium, and ICF capsule implosion, for instance.

  14. Modelling in nuclear energy environments

    Directory of Open Access Journals (Sweden)

    M. Samaras

    2008-12-01

    Full Text Available Producing energy to supply the demands of our societies is reaching a critical limit. To tackle this issue, there is a slow renaissance of fission reactors and the push to realise fusion reactors. The safe, reliable and optimal performance of fusion and fission plants is dependent on the choice of suitable materials used as components and fuels. As these materials are degraded by their exposure to high temperatures, irradiation and a corrosive environment, it is necessary to address the issue of long term degradation of materials under service exposure in advanced plants. A higher confidence in life-time assessments of these materials requires an understanding of the related physical phenomena on a range of scales from the atomic level of single defect energetics all the way up to macroscopic effects.

  15. Mars' surface radiation environment measured with the Mars science laboratory's curiosity rover

    NARCIS (Netherlands)

    Hassler, D.M.; Zeitlin, C.; Wimmer-Schweingruber, R.F.; Ehresmann, B.; Rafkin, S.; Eigenbrode, J.L.; Brinza, D.E.; Weigle, G.; Böttcher, S.; Böhm, E.; Burmeister, S.; Guo, J.; Köhler, J.; Martin, C.; Reitz, G.; Cucinotta, F.A.; Kim, M.-H.; Grinspoon, D.; Bullock, M.A.; Posner, A.; Gómez-Elvira, J.; Vasavada, A.; Grotzinger, J.P.; MSL Science Team, the

    2014-01-01

    The Radiation Assessment Detector (RAD) on the Mars Science Laboratory’s Curiosity rover began making detailed measurements of the cosmic ray and energetic particle radiation environment on the surface of Mars on 7 August 2012. We report and discuss measurements of the absorbed dose and dose equival

  16. Mars' surface radiation environment measured with the Mars science laboratory's curiosity rover

    NARCIS (Netherlands)

    Hassler, D.M.; Zeitlin, C.; Wimmer-Schweingruber, R.F.; Ehresmann, B.; Rafkin, S.; Eigenbrode, J.L.; Brinza, D.E.; Weigle, G.; Böttcher, S.; Böhm, E.; Burmeister, S.; Guo, J.; Köhler, J.; Martin, C.; Reitz, G.; Cucinotta, F.A.; Kim, M.-H.; Grinspoon, D.; Bullock, M.A.; Posner, A.; Gómez-Elvira, J.; Vasavada, A.; Grotzinger, J.P.; MSL Science Team, the

    2014-01-01

    The Radiation Assessment Detector (RAD) on the Mars Science Laboratory’s Curiosity rover began making detailed measurements of the cosmic ray and energetic particle radiation environment on the surface of Mars on 7 August 2012. We report and discuss measurements of the absorbed dose and dose equival

  17. Sample Environment in Experiments using X-Ray Synchrotron Radiation

    DEFF Research Database (Denmark)

    Buras, B

    1984-01-01

    Modern electron (positron) storage rings are able to emit very intense X-ray radiation with a continuous spectrum extending to 0.1 A, from bending magnets and insertion devices (wavelength shifters and multipole wigglers). It can be used directly for white beam experiments and/or for monochromati...

  18. Diamond and silicon pixel detectors in high radiation environments

    Energy Technology Data Exchange (ETDEWEB)

    Tsung, Jieh-Wen

    2012-10-15

    Diamond pixel detector is a promising candidate for tracking of collider experiments because of the good radiation tolerance of diamond. The diamond pixel detector must withstand the radiation damage from 10{sup 16} particles per cm{sup 2}, which is the expected total fluence in High Luminosity Large Hadron Collider. The performance of diamond and silicon pixel detectors are evaluated in this research in terms of the signal-to-noise ratio (SNR). Single-crystal diamond pixel detectors with the most recent readout chip ATLAS FE-I4 are produced and characterized. Based on the results of the measurement, the SNR of diamond pixel detector is evaluated as a function of radiation fluence, and compared to that of planar-silicon ones. The deterioration of signal due to radiation damage is formulated using the mean free path of charge carriers in the sensor. The noise from the pixel readout circuit is simulated and calculated with leakage current and input capacitance to the amplifier as important parameters. The measured SNR shows good agreement with the calculated and simulated results, proving that the performance of diamond pixel detectors can exceed the silicon ones if the particle fluence is more than 10{sup 15} particles per cm{sup 2}.

  19. Development of a new Global RAdiation Belt model: GRAB

    Science.gov (United States)

    Sicard-Piet, Angelica; Lazaro, Didier; Maget, Vincent; Rolland, Guy; Ecoffet, Robert; Bourdarie, Sébastien; Boscher, Daniel; Standarovski, Denis

    2016-07-01

    The well known AP8 and AE8 NASA models are commonly used in the industry to specify the radiation belt environment. Unfortunately, there are some limitations in the use of these models, first due to the covered energy range, but also because in some regions of space, there are discrepancies between the predicted average values and the measurements. Therefore, our aim is to develop a radiation belt model, covering a large region of space and energy, from LEO altitudes to GEO and above, and from plasma to relativistic particles. The aim for the first version is to correct the AP8 and AE8 models where they are deficient or not defined. At geostationary, we developed ten years ago for electrons the IGE-2006 model which was proven to be more accurate than AE8, and used commonly in the industry, covering a broad energy range, from 1keV to 5MeV. From then, a proton model for geostationary orbit was also developed for material applications, followed by the OZONE model covering a narrower energy range but the whole outer electron belt, a SLOT model to asses average electron values for 2file system to switch between models, in order to obtain at each location in space and energy point the most reliable value. Of course, the way the model is developed is well suited to add new local developments or to include international partnership. This model will be called the GRAB model, as Global Radiation Belt model. We will present first beta version during this conference.

  20. The transient observation-based particle (TOP model and its potential application in radiation effects evaluation

    Directory of Open Access Journals (Sweden)

    Benck Sylvie

    2013-01-01

    Full Text Available The evaluation of the radiation hazards on components used in space environment is based on the knowledge of the radiation level encountered on orbit. The models that are widely used to assess the near-Earth environment for a given mission are empirical trapped radiation models derived from a compilation of spacecraft measurements. However, these models are static and hence are not suited for describing the short timescale variations of geomagnetic conditions. The transient observation-based particle (TOP-model tends to break with this classical approach by introducing dynamic features based on the observation and characterization of transient particle flux events in addition to classical mapping of steady-state flux levels. In order to get a preliminary version of an operational model (actually only available for electrons at low Earth orbit, LEO, (i the steady-state flux level, (ii the flux enhancements probability distribution functions, and (iii the flux decay-time constants (at given energy and positions in space were determined, and an original dynamic model skeleton with these input parameters has been developed. The methodology is fully described and first flux predictions from the model are presented. In order to evaluate the net effects of radiation on a component, it is important to have an efficient tool that calculates the transfer of the outer radiation environment through the spacecraft material, toward the location of the component under investigation. Using the TOP-model space radiation fluxes and the transmitted radiation environment characteristics derived through GEANT4 calculations, a case study for electron flux/dose variations in a small silicon volume is performed. Potential cases are assessed where the dynamic of the spacecraft radiation environment may have an impact on the observed radiation effects.

  1. Inflation model selection meets dark radiation

    Science.gov (United States)

    Tram, Thomas; Vallance, Robert; Vennin, Vincent

    2017-01-01

    We investigate how inflation model selection is affected by the presence of additional free-streaming relativistic degrees of freedom, i.e. dark radiation. We perform a full Bayesian analysis of both inflation parameters and cosmological parameters taking reheating into account self-consistently. We compute the Bayesian evidence for a few representative inflation scenarios in both the standard ΛCDM model and an extension including dark radiation parametrised by its effective number of relativistic species Neff. Using a minimal dataset (Planck low-l polarisation, temperature power spectrum and lensing reconstruction), we find that the observational status of most inflationary models is unchanged. The exceptions are potentials such as power-law inflation that predict large values for the scalar spectral index that can only be realised when Neff is allowed to vary. Adding baryon acoustic oscillations data and the B-mode data from BICEP2/Keck makes power-law inflation disfavoured, while adding local measurements of the Hubble constant H0 makes power-law inflation slightly favoured compared to the best single-field plateau potentials. This illustrates how the dark radiation solution to the H0 tension would have deep consequences for inflation model selection.

  2. Radiative torques: Analytical Model and Basic Properties

    CERN Document Server

    Lazarian, Alex

    2007-01-01

    We attempt to get a physical insight into grain alignment processes by studying basic properties of radiative torques (RATs). For this purpose we consider a simple toy model of a helical grain that reproduces well the basic features of RATs. The model grain consists of a spheroidal body with a mirror attached at an angle to it. Being very simple, the model allows analytical description of RATs that act upon it. We show a good correspondence of RATs obtained for this model and those of irregular grains calculated by DDSCAT. Our analysis of the role of different torque components for grain alignment reveals that one of the three RAT components does not affect the alignment, but induces only for grain precession. The other two components provide a generic alignment with grain long axes perpendicular to the radiation direction, if the radiation dominates the grain precession, and perpendicular to magnetic field, otherwise. We study a self-similar scaling of RATs as a function of $\\lambda/a_{eff}$. We show that th...

  3. Micronuclei as biomarkers of genotoxicity of gamma radiation in aquatic environments

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Luanna R.S.; Silva, Edvane B.; Melo, Ana M.M.A. [Universidade Federal de Pernambuco (GERAR/DEN/UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear. Grupo de Estudos em Radioprotecao e Radioecologia; Silva, Ronaldo C. da [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Genetica; Amancio, Francisco F. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Biofisica e Radiobiologia. Lab. de Radiobiologia

    2011-07-01

    Ionizing radiation is a genotoxic agent, inducing gene mutations and cellular death. Several efforts have been defendants in the development of techniques for measurement of radiation damage in biological systems. Among these techniques, micronuclei test has been showing as a great bio marker of DNA damage, being used in environmental monitoring to detect genotoxic agents in the environment. Additionally, organisms as Biomphalaria glabrata, freshwater molluscs, presents itself as an excellent model to assess damage caused by physical and chemical agents, due their biological and environmental characteristics. The snails were divided into groups of 5 individuals exposed to doses of 0 (control), 25, 35, 45 and 55 Gy of {sup 60}Co. After 48 hours of irradiation, the hemo lymph was collected and prepared the slides, which were stained with Giemsa and analyzed the cellular changes in haemocytes Statistical analysis was accomplished through chi-square test, ANOVA and Tukey test (p< 0,05). The results indicated that B. glabrata showed to be sensitive to gamma radiation. The snails irradiated with 35 Gy showed a decrease of haemocytes, while that of 55 Gy increased. Cellular and morphological changes were observed at doses of 35, 45 and 55 Gy and the dose of 55 Gy, the most radiotoxic. (author)

  4. Extended Higgs sectors in radiative neutrino models

    Directory of Open Access Journals (Sweden)

    Oleg Antipin

    2017-05-01

    Full Text Available Testable Higgs partners may be sought within the extensions of the SM Higgs sector aimed at generating neutrino masses at the loop level. We study a viability of extended Higgs sectors for two selected models of radiative neutrino masses: a one-loop mass model, providing the Higgs partner within a real triplet scalar representation, and a three-loop mass model, providing it within its two-Higgs-doublet sector. The Higgs sector in the one-loop model may remain stable and perturbative up to the Planck scale, whereas the three-loop model calls for a UV completion around 106 GeV. Additional vector-like lepton and exotic scalar fields, which are required to close one- and three-loop neutrino-mass diagrams, play a decisive role for the testability of the respective models. We constrain the parameter space of these models using LHC bounds on diboson resonances.

  5. Biologically based multistage modeling of radiation effects

    Energy Technology Data Exchange (ETDEWEB)

    William Hazelton; Suresh Moolgavkar; E. Georg Luebeck

    2005-08-30

    This past year we have made substantial progress in modeling the contribution of homeostatic regulation to low-dose radiation effects and carcinogenesis. We have worked to refine and apply our multistage carcinogenesis models to explicitly incorporate cell cycle states, simple and complex damage, checkpoint delay, slow and fast repair, differentiation, and apoptosis to study the effects of low-dose ionizing radiation in mouse intestinal crypts, as well as in other tissues. We have one paper accepted for publication in ''Advances in Space Research'', and another manuscript in preparation describing this work. I also wrote a chapter describing our combined cell-cycle and multistage carcinogenesis model that will be published in a book on stochastic carcinogenesis models edited by Wei-Yuan Tan. In addition, we organized and held a workshop on ''Biologically Based Modeling of Human Health Effects of Low dose Ionizing Radiation'', July 28-29, 2005 at Fred Hutchinson Cancer Research Center in Seattle, Washington. We had over 20 participants, including Mary Helen Barcellos-Hoff as keynote speaker, talks by most of the low-dose modelers in the DOE low-dose program, experimentalists including Les Redpath (and Mary Helen), Noelle Metting from DOE, and Tony Brooks. It appears that homeostatic regulation may be central to understanding low-dose radiation phenomena. The primary effects of ionizing radiation (IR) are cell killing, delayed cell cycling, and induction of mutations. However, homeostatic regulation causes cells that are killed or damaged by IR to eventually be replaced. Cells with an initiating mutation may have a replacement advantage, leading to clonal expansion of these initiated cells. Thus we have focused particularly on modeling effects that disturb homeostatic regulation as early steps in the carcinogenic process. There are two primary considerations that support our focus on homeostatic regulation. First, a number of

  6. Modelling in environments without numbers

    NARCIS (Netherlands)

    Grigoraş, D.R.; Hoede, C.

    2008-01-01

    In order to study how students are handling modelling situations, we address the type of tasks without an obvious mathematical character. The mathematical elements are somehow hidden and are to be elaborated by the students, if their solving strategy goes in that direction. The main reason why we el

  7. Nuclear Radiation Fields on the Mars Surface: Risk Analysis for Long-term Living Environment

    Science.gov (United States)

    Anderson, Brooke M.; Clowdsley, Martha S.; Qualls, Garry D.; Nealy, John E.

    2005-01-01

    Mars, our nearest planet outward from the sun, has been targeted for several decades as a prospective site for expanded human habitation. Background space radiation exposures on Mars are expected to be orders of magnitude higher than on Earth. Recent risk analysis procedures based on detailed dosimetric techniques applicable to sensitive human organs have been developed along with experimental data regarding cell mutation rates resulting from exposures to a broad range of particle types and energy spectra. In this context, simulated exposure and subsequent risk for humans in residence on Mars are examined. A conceptual habitat structure, CAD-modeled with duly considered inherent shielding properties, has been implemented. Body self-shielding is evaluated using NASA standard computerized male and female models. The background environment is taken to consist not only of exposure from incident cosmic ray ions and their secondaries, but also include the contribution from secondary neutron fields produced in the tenuous atmosphere and the underlying regolith.

  8. Functional Traits in Parallel Evolutionary Radiations and Trait-Environment Associations in the Cape Floristic Region of South Africa.

    Science.gov (United States)

    Mitchell, Nora; Moore, Timothy E; Mollmann, Hayley Kilroy; Carlson, Jane E; Mocko, Kerri; Martinez-Cabrera, Hugo; Adams, Christopher; Silander, John A; Jones, Cynthia S; Schlichting, Carl D; Holsinger, Kent E

    2015-04-01

    Evolutionary radiations with extreme levels of diversity present a unique opportunity to study the role of the environment in plant evolution. If environmental adaptation played an important role in such radiations, we expect to find associations between functional traits and key climatic variables. Similar trait-environment associations across clades may reflect common responses, while contradictory associations may suggest lineage-specific adaptations. Here, we explore trait-environment relationships in two evolutionary radiations in the fynbos biome of the highly biodiverse Cape Floristic Region (CFR) of South Africa. Protea and Pelargonium are morphologically and evolutionarily diverse genera that typify the CFR yet are substantially different in growth form and morphology. Our analytical approach employs a Bayesian multiple-response generalized linear mixed-effects model, taking into account covariation among traits and controlling for phylogenetic relationships. Of the pairwise trait-environment associations tested, 6 out of 24 were in the same direction and 2 out of 24 were in opposite directions, with the latter apparently reflecting alternative life-history strategies. These findings demonstrate that trait diversity within two plant lineages may reflect both parallel and idiosyncratic responses to the environment, rather than all taxa conforming to a global-scale pattern. Such insights are essential for understanding how trait-environment associations arise and how they influence species diversification.

  9. Performances of Kevlar and Polyethylene as radiation shielding on-board the International Space Station in high latitude radiation environment.

    Science.gov (United States)

    Narici, Livio; Casolino, Marco; Di Fino, Luca; Larosa, Marianna; Picozza, Piergiorgio; Rizzo, Alessandro; Zaconte, Veronica

    2017-05-10

    Passive radiation shielding is a mandatory element in the design of an integrated solution to mitigate the effects of radiation during long deep space voyages for human exploration. Understanding and exploiting the characteristics of materials suitable for radiation shielding in space flights is, therefore, of primary importance. We present here the results of the first space-test on Kevlar and Polyethylene radiation shielding capabilities including direct measurements of the background baseline (no shield). Measurements are performed on-board of the International Space Station (Columbus modulus) during the ALTEA-shield ESA sponsored program. For the first time the shielding capability of such materials has been tested in a radiation environment similar to the deep-space one, thanks to the feature of the ALTEA system, which allows to select only high latitude orbital tracts of the International Space Station. Polyethylene is widely used for radiation shielding in space and therefore it is an excellent benchmark material to be used in comparative investigations. In this work we show that Kevlar has radiation shielding performances comparable to the Polyethylene ones, reaching a dose rate reduction of 32 ± 2% and a dose equivalent rate reduction of 55 ± 4% (for a shield of 10 g/cm(2)).

  10. new model for solar radiation estimation from measured air ...

    African Journals Online (AJOL)

    HOD

    Nigerian Meteorological Agency (NIMET) were used as inputs to the ANFIS model and monthly mean global solar radiation was ... models were used to predict solar radiation in Nigeria by. [12-15]. .... calculate them as total output [32] and [34].

  11. Modeling of the radiative field in complex geometries using computerized graphical tools. Application to comfort characterization in environments equipped with important radiative sources; Modelisation du champ radiatif dans des geometries complexes a l`aide d`outils infographiques. Application a la caracterisation du confort dans les ambiances munies de sources radiatives importantes

    Energy Technology Data Exchange (ETDEWEB)

    Manolescu, M.; Sperandio, M.; Allard, F. [La Rochelle Universite, 17 - La Rochelle, LEPTAB (France)

    1996-12-31

    Bibliographic studies in the domain of radiant heat transfers in complex geometries demonstrate the impossibility of resolving such problems using classical analytical methods. The numerical analysis can theoretically be performed successfully but requires enormous computer means. The contribution of this study consists in using computerized graphical techniques to treat general problems of radiant heat transfers in complex geometries. This paper presents the model used, the calculation technique and the optimizations that allow to greatly reduce the computer memory required and the calculation time. The code developed uses evocative images for the synthetic presentation of results which facilitate the searcher`s and conceiver`s choices. Finally, an application to the characterization of thermal comfort in residential environments is developed to illustrate the potentialities of this method. (J.S.) 19 refs.

  12. VCHP Radiators for Lunar and Martian Environments Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Long-term Lunar and Martian systems present challenges to thermal control systems, including changes in thermal load, and large changes in the thermal environment...

  13. VCHP Radiators for Lunar and Martian Environments Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Long-term Lunar and Martian systems present challenges to thermal systems, including changes in thermal load, and large changes in the thermal environment between...

  14. Atmospheric radiation environment analyses based-on CCD camera at various mountain altitudes and underground sites

    Directory of Open Access Journals (Sweden)

    Li Cavoli Pierre

    2016-01-01

    Full Text Available The purpose of this paper is to discriminate secondary atmospheric particles and identify muons by measuring the natural radiative environment in atmospheric and underground locations. A CCD camera has been used as a cosmic ray sensor. The Low Noise Underground Laboratory of Rustrel (LSBB, France gives the access to a unique low-noise scientific environment deep enough to ensure the screening from the neutron and proton radiative components. Analyses of the charge levels in pixels of the CCD camera induced by radiation events and cartographies of the charge events versus the hit pixel are proposed.

  15. Service Oriented Spacecraft Modeling Environment Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The I-Logix team proposes development of the Service Oriented Spacecraft Modeling Environment (SOSME) to allow faster and more effective spacecraft system design...

  16. Radiation beamline testbeds for the simulation of planetary and spacecraft environments for human and robotic mission risk assessment

    Science.gov (United States)

    Wilkins, Richard

    The Center for Radiation Engineering and Science for Space Exploration (CRESSE) at Prairie View A&M University, Prairie View, Texas, USA, is establishing an integrated, multi-disciplinary research program on the scientific and engineering challenges faced by NASA and the inter-national space community caused by space radiation. CRESSE focuses on space radiation research directly applicable to astronaut health and safety during future long term, deep space missions, including Martian, lunar, and other planetary body missions beyond low earth orbit. The research approach will consist of experimental and theoretical radiation modeling studies utilizing particle accelerator facilities including: 1. NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory; 2. Proton Synchrotron at Loma Linda University Med-ical Center; and 3. Los Alamos Neutron Science Center (LANSCE) at Los Alamos National Laboratory. Specifically, CRESSE investigators are designing, developing, and building experimental test beds that simulate the lunar and Martian radiation environments for experiments focused on risk assessment for astronauts and instrumentation. The testbeds have been designated the Bioastronautics Experimental Research Testbeds for Environmental Radiation Nostrum Investigations and Education (BERT and ERNIE). The designs of BERT and ERNIE will allow for a high degree of flexibility and adaptability to modify experimental configurations to simulate planetary surface environments, planetary habitats, and spacecraft interiors. In the nominal configuration, BERT and ERIE will consist of a set of experimental zones that will simulate the planetary atmosphere (Solid CO2 in the case of the Martian surface.), the planetary surface, and sub-surface regions. These experimental zones can be used for dosimetry, shielding, biological, and electronic effects radiation studies in support of space exploration missions. BERT and ERNIE are designed to be compatible with the

  17. Radiation Beamline Testbeds for the Simulation of Planetary and Spacecraft Environments for Human and Robotic Mission Risk Assessment

    Science.gov (United States)

    Wilkins, Richard

    2010-01-01

    The Center for Radiation Engineering and Science for Space Exploration (CRESSE) at Prairie View A&M University, Prairie View, Texas, USA, is establishing an integrated, multi-disciplinary research program on the scientific and engineering challenges faced by NASA and the international space community caused by space radiation. CRESSE focuses on space radiation research directly applicable to astronaut health and safety during future long term, deep space missions, including Martian, lunar, and other planetary body missions beyond low earth orbit. The research approach will consist of experimental and theoretical radiation modeling studies utilizing particle accelerator facilities including: 1. NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory; 2. Proton Synchrotron at Loma Linda University Medical Center; and 3. Los Alamos Neutron Science Center (LANSCE) at Los Alamos National Laboratory. Specifically, CRESSE investigators are designing, developing, and building experimental test beds that simulate the lunar and Martian radiation environments for experiments focused on risk assessment for astronauts and instrumentation. The testbeds have been designated the Bioastronautics Experimental Research Testbeds for Environmental Radiation Nostrum Investigations and Education (BERT and ERNIE). The designs of BERT and ERNIE will allow for a high degree of flexibility and adaptability to modify experimental configurations to simulate planetary surface environments, planetary habitats, and spacecraft interiors. In the nominal configuration, BERT and ERIE will consist of a set of experimental zones that will simulate the planetary atmosphere (Solid CO2 in the case of the Martian surface.), the planetary surface, and sub-surface regions. These experimental zones can be used for dosimetry, shielding, biological, and electronic effects radiation studies in support of space exploration missions. BERT and ERNIE are designed to be compatible with the

  18. Bullying among radiation therapists: effects on job performance and work environment.

    Science.gov (United States)

    Trad, Megan; Johnson, Jordan

    2014-01-01

    To identify the effects of workplace bullying in the radiation therapy department on job performance and explore the environment and morale of individuals who work with a bully. A quantitative research study was designed to assess the prevalence and effects of bullying in the radiation therapy workplace. A total of 308 radiation therapists participated in the study for a return rate of 46%. Of those, 194 indicated that workplace bullying was present either in their current workplace or in a previous radiation therapy environment and that it negatively affected job performance and satisfaction. Findings of this study indicate a need for evaluation of the radiation therapy workplace, education on how to identify and prevent bullying behavior, and better communication among members of the radiation therapy environment. Participants indicated that working in a hostile environment led to forgetfulness, ineffective communication, and perceived discrepancies in promotion and treatment by management. Any bullying behavior contributes to an overall toxic work environment, which is unhealthy and unsafe for patients and therapists. Those who manage therapists should promote a culture of safety and embrace their staff's independence.

  19. Analysis of the solar radiation data for Beer Sheva, Israel, and its environs

    Energy Technology Data Exchange (ETDEWEB)

    Kudish, A.I. (Ben-Gurion Univ. of the Negev, Beer Sheva (Israel)); Ianetz, A. (Israel Meteorological Service, Bet-Dagan (Israel))

    1992-01-01

    The solar radiation climate of Beer Sheva, Israel, is reported upon in detail. The database utilized in this analysis consisted of global radiation on a horizontal surface, normal incidence beam radiation, and global radiation on a south-facing surface tilted at 40{degree}. Monthly-average hourly and daily values are reported for each of these three types of measured radiations, together with the calculated monthly-average daily values for the components of the global radiation, viz. the horizontal beam and diffuse radiations. The monthly-average hourly and daily clearness index values have also been calculated and analyzed. Monthly-average daily frequency distributions of the clearness index values are reported for each month. The solar radiation climate of Beer Sheva has also been compared to those reported for a number of countries in this region. The annual-average daily global radiation incident on a horizontal surface is 18.91 MG/m{sup 2} and that for normal incidence beam radiation is 21.17 MG/m{sup 2}. The annual-average daily fraction of the horizontal global radiation that is beam is 0.72. The annual-average daily value for the clearness index is 0.587 and the average frequency of clear days annually is 58.6%. The authors conclude, based upon the above analysis, that Beer Sheva and its environs are characterized by relatively high, average-daily irradiation rates, both global and beam, and a relatively high frequency of clear days.

  20. The charged particle radiation environment on Mars measured by MSL/RAD from November 15, 2015 to January 15, 2016

    Science.gov (United States)

    Ehresmann, Bent; Zeitlin, Cary J.; Hassler, Donald M.; Matthiä, Daniel; Guo, Jingnan; Wimmer-Schweingruber, Robert F.; Appel, Jan K.; Brinza, David E.; Rafkin, Scot C. R.; Böttcher, Stephan I.; Burmeister, Sönke; Lohf, Henning; Martin, Cesar; Böhm, Eckart; Reitz, Günther

    2017-08-01

    The Radiation Assessment Detector (RAD) on board the Mars Science Laboratory (MSL) Curiosity rover has been measuring the radiation environment in Gale crater on Mars since August, 2012. These first in-situ measurements provide an important data set for assessing the radiation-associated health risks for future manned missions to Mars. Mainly, the radiation field on the Martian surface stems from Galactic Cosmic Rays (GCRs) and secondary particles created by the GCRs' interactions with the Martian atmosphere and soil. RAD is capable of measuring differential particle fluxes for lower-energy ions and isotopes of hydrogen and helium (up to hundreds of MeV/nuc). Additionally, RAD also measures integral particle fluxes for higher energies of these ions. Besides providing insight on the current Martian radiation environment, these fluxes also present an essential input for particle transport codes that are used to model the radiation to be encountered during future manned missions to Mars. Comparing simulation results with actual ground-truth measurements helps to validate these transport codes and identify potential areas of improvements in the underlying physics of these codes. At the First Mars Radiation Modeling Workshop (June 2016 in Boulder, CO), different groups of modelers were asked to calculate the Martian surface radiation environment for the time of November 15, 2015 to January 15, 2016. These model results can then be compared with in-situ measurements of MSL/RAD conducted during the same time frame. In this publication, we focus on presenting the charged particle fluxes measured by RAD between November 15, 2015 and January 15, 2016, providing the necessary data set for the comparison to model outputs from the modeling workshop. We also compare the fluxes to initial GCR intensities, as well as to RAD measurements from an earlier time period (August 2012 to January 2013). Furthermore, we describe how changes and updates in RAD on board processing and the on

  1. Radiation Safety Management Guidelines for PET-CT: Focus on Behavior and Environment

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Jin Wook [Cancer Imaging Center, National University Cancer Hospital, Seoul (Korea, Republic of); Han, Eun Ok [Dept. of Radiological Technology, Daegu Health College, Seoul (Korea, Republic of)

    2011-09-15

    Our purpose is to specify behavior and environmental factors aimed at reducing the exposed dosage caused by PET-CT and to develop radiation safety management guidelines adequate for domestic circumstances. We have used a multistep-multimethod as the methodological approach to design and to carry out the research both in quality and quantity, including an analysis on previous studies, professional consultations and a survey. The survey includes responses from 139 practitioners in charged of 109 PET-CTs installed throughout Korea(reported by the Korean Society of Nuclear Medicine, 2010). The research use 156 questions using Cronbach's {alpha} (alpha) coefficients which were: 0.818 for 'the necessity of setting and installing the radiation protective environment'; 0.916 for 'the necessity of radiation protection', 'setting and installing the radiation protective environment'; and 0.885 for 'radiation protection'. The check list, derived from the radiation safety management guidelines focused on behavior and environment, was composed of 20 items for the radiation protective environment: including 5 items for the patient; 4 items for the guardian; 3 items for the radiologist; and 8 items applied to everyone involved; for a total of 26 items for the radiation protective behavior including: 12 items for the patient; 1 item for the guardian, 7 items for the radiologist; and 6 items applied to everyone involved. The specific check list is shown in (Table 5-6). Since our country has no safety management guidelines of its own to reduce the exposed dosage caused by PET-CTs, we believe the guidelines developed through this study means great deal to the field as it is not only appropriate for domestic circumstances, but also contains specific check lists for each target who may be exposed to radiation in regards to behavior and environment.

  2. On-site radiated emissions measurements in Semi-reverberant environments

    NARCIS (Netherlands)

    Vogt-Ardatjew, Robert; Lundgren, Urban; Fernandez-Romero, Sergio; Leferink, Frank

    2016-01-01

    Radiated emission tests are generally performed in either free space, reflection-free environments, such as an open area test site or semi- or full-anechoic chambers, or in reverberation chambers. This paper describes measurements in semireflecting environments such as an office, a workshop of a lar

  3. Theoretical Modelling of Sound Radiation from Plate

    Science.gov (United States)

    Zaman, I.; Rozlan, S. A. M.; Yusoff, A.; Madlan, M. A.; Chan, S. W.

    2017-01-01

    Recently the development of aerospace, automotive and building industries demands the use of lightweight materials such as thin plates. However, the plates can possibly add to significant vibration and sound radiation, which eventually lead to increased noise in the community. So, in this study, the fundamental concept of sound pressure radiated from a simply-supported thin plate (SSP) was analyzed using the derivation of mathematical equations and numerical simulation of ANSYS®. The solution to mathematical equations of sound radiated from a SSP was visualized using MATLAB®. The responses of sound pressure level were measured at far field as well as near field in the frequency range of 0-200 Hz. Result shows that there are four resonance frequencies; 12 Hz, 60 Hz, 106 Hz and 158 Hz were identified which represented by the total number of the peaks in the frequency response function graph. The outcome also indicates that the mathematical derivation correlated well with the simulation model of ANSYS® in which the error found is less than 10%. It can be concluded that the obtained model is reliable and can be applied for further analysis such as to reduce noise emitted from a vibrating thin plate.

  4. High-performing simulations of the space radiation environment for the International Space Station and Apollo Missions

    Science.gov (United States)

    Lund, Matthew Lawrence

    The space radiation environment is a significant challenge to future manned and unmanned space travels. Future missions will rely more on accurate simulations of radiation transport in space through spacecraft to predict astronaut dose and energy deposition within spacecraft electronics. The International Space Station provides long-term measurements of the radiation environment in Low Earth Orbit (LEO); however, only the Apollo missions provided dosimetry data beyond LEO. Thus dosimetry analysis for deep space missions is poorly supported with currently available data, and there is a need to develop dosimetry-predicting models for extended deep space missions. GEANT4, a Monte Carlo Method, provides a powerful toolkit in C++ for simulation of radiation transport in arbitrary media, thus including the spacecraft and space travels. The newest version of GEANT4 supports multithreading and MPI, resulting in faster distributive processing of simulations in high-performance computing clusters. This thesis introduces a new application based on GEANT4 that greatly reduces computational time using Kingspeak and Ember computational clusters at the Center for High Performance Computing (CHPC) to simulate radiation transport through full spacecraft geometry, reducing simulation time to hours instead of weeks without post simulation processing. Additionally, this thesis introduces a new set of detectors besides the historically used International Commission of Radiation Units (ICRU) spheres for calculating dose distribution, including a Thermoluminescent Detector (TLD), Tissue Equivalent Proportional Counter (TEPC), and human phantom combined with a series of new primitive scorers in GEANT4 to calculate dose equivalence based on the International Commission of Radiation Protection (ICRP) standards. The developed models in this thesis predict dose depositions in the International Space Station and during the Apollo missions showing good agreement with experimental measurements

  5. A Radiative Transport Model for Blazars

    Science.gov (United States)

    Lewis, Tiffany; Justin, Finke; Becker, Peter A.

    2017-01-01

    Blazars are observed across the electromagnetic spectrum, often with strong variability throughout. The underlying electron distribution associated with the observed emission is typically not computed from first principles. We start from first-principles to build up a transport model, whose solution is the electron distribution, rather than assuming a convenient functional form. Our analytical transport model considers shock acceleration, adiabatic expansion, stochastic acceleration, Bohm diffusion, and synchrotron radiation. We use this solution to generate predictions for the X-ray spectrum and time lags, and compare the results with data products from BeppoSAX observations of X-ray flares from Mrk 421. This new self-consistent model provides an unprecedented view into the jet physics at play in this source, especially the strength of the shock and stochastic acceleration components and the size of the acceleration region.More recently, we augmented the transport model to incorporate Compton scattering, including Klein-Nishina effects. In this case, an analytical solution cannot be derived, and therefore we obtain the steady-state electron distribution computationally. We compare the resulting radiation spectrum with multi-wavelength data for 3C 279. We show that our new Compton + synchrotron blazar model is the first to successfully fit the FermiLAT gamma-ray data for this source based on a first-principles physical calculation.

  6. Conceptual Model of Dynamic Geographic Environment

    Directory of Open Access Journals (Sweden)

    Martínez-Rosales Miguel Alejandro

    2014-04-01

    Full Text Available In geographic environments, there are many and different types of geographic entities such as automobiles, trees, persons, buildings, storms, hurricanes, etc. These entities can be classified into two groups: geographic objects and geographic phenomena. By its nature, a geographic environment is dynamic, thus, it’s static modeling is not sufficient. Considering the dynamics of geographic environment, a new type of geographic entity called event is introduced. The primary target is a modeling of geographic environment as an event sequence, because in this case the semantic relations are much richer than in the case of static modeling. In this work, the conceptualization of this model is proposed. It is based on the idea to process each entity apart instead of processing the environment as a whole. After that, the so called history of each entity and its spatial relations to other entities are defined to describe the whole environment. The main goal is to model systems at a conceptual level that make use of spatial and temporal information, so that later it can serve as the semantic engine for such systems.

  7. A temporal forecast of radiation environments for future space exploration missions.

    Science.gov (United States)

    Kim, Myung-Hee Y; Cucinotta, Francis A; Wilson, John W

    2007-06-01

    The understanding of future space radiation environments is an important goal for space mission operations, design, and risk assessment. We have developed a solar cycle statistical model in which sunspot number is coupled to space-related quantities, such as the galactic cosmic radiation (GCR) deceleration potential (phi) and the mean occurrence frequency of solar particle events (SPEs). Future GCR fluxes were derived from a predictive model, in which the temporal dependence represented by phi was derived from GCR flux and ground-based Climax neutron monitor rate measurements over the last four decades. These results showed that the point dose equivalent inside a typical spacecraft in interplanetary space was influenced by solar modulation by up to a factor of three. It also has been shown that a strong relationship exists between large SPE occurrences and phi. For future space exploration missions, cumulative probabilities of SPEs at various integral fluence levels during short-period missions were defined using a database of proton fluences of past SPEs. Analytic energy spectra of SPEs at different ranks of the integral fluences for energies greater than 30 MeV were constructed over broad energy ranges extending out to GeV for the analysis of representative exposure levels at those fluences. Results will guide the design of protection systems for astronauts during future space exploration missions.

  8. Radiation therapists' and radiation oncology medical physicists' perceptions of work and the working environment in Australia: a qualitative study.

    Science.gov (United States)

    Halkett, G K B; McKay, J; Hegney, D G; Breen, Lauren J; Berg, M; Ebert, M A; Davis, M; Kearvell, R

    2016-05-05

    Workforce recruitment and retention are issues in radiation oncology. The working environment is likely to have an impact on retention; however, there is a lack of research in this area. The objectives of this study were to: investigate radiation therapists' (RTs) and radiation oncology medical physicists' (ROMPs) perceptions of work and the working environment; and determine the factors that influence the ability of RTs and ROMPs to undertake their work and how these factors affect recruitment and retention. Semi-structured interviews were conducted and thematic analysis was used. Twenty-eight RTs and 21 ROMPs participated. The overarching themes were delivering care, support in work, working conditions and lifestyle. The overarching themes were mostly consistent across both groups; however, the exemplars reflected the different roles and perspectives of RTs and ROMPs. Participants described the importance they placed on treating patients and improving their lives. Working conditions were sometimes difficult with participants reporting pressure at work, large workloads and longer hours and overtime. Insufficient staff numbers impacted on the effectiveness of staff, the working environment and intentions to stay. Staff satisfaction is likely to be improved if changes are made to the working environment. We make recommendations that may assist departments to support RTs and ROMPs.

  9. Inflation Model Selection meets Dark Radiation

    CERN Document Server

    Tram, Thomas; Vennin, Vincent

    2016-01-01

    We investigate how inflation model selection is affected by the presence of additional free-streaming relativistic degrees of freedom, i.e. dark radiation. We perform a full Bayesian analysis of both inflation parameters and cosmological parameters taking reheating into account self-consistently. We compute the Bayesian evidence for a few representative inflation scenarios in both the standard $\\Lambda\\mathrm{CDM}$ model and an extension including dark radiation parametrised by its effective number of relativistic species $N_\\mathrm{eff}$. We find that the observational status of most inflationary models is unchanged, with the exception of potentials such as power-law inflation that predict a value for the scalar spectral index that is too large in $\\Lambda\\mathrm{CDM}$ but which can be accommodated when $N_\\mathrm{eff}$ is allowed to vary. In this case, cosmic microwave background data indicate that power-law inflation is one of the best models together with plateau potentials. However, contrary to plateau p...

  10. Solar radiation practical modeling for renewable energy applications

    CERN Document Server

    Myers, Daryl Ronald

    2013-01-01

    Written by a leading scientist with over 35 years of experience working at the National Renewable Energy Laboratory (NREL), Solar Radiation: Practical Modeling for Renewable Energy Applications brings together the most widely used, easily implemented concepts and models for estimating broadband and spectral solar radiation data. The author addresses various technical and practical questions about the accuracy of solar radiation measurements and modeling. While the focus is on engineering models and results, the book does review the fundamentals of solar radiation modeling and solar radiation m

  11. Low-radiation environment affects the development of protection mechanisms in V79 cells.

    Science.gov (United States)

    Fratini, E; Carbone, C; Capece, D; Esposito, G; Simone, G; Tabocchini, M A; Tomasi, M; Belli, M; Satta, L

    2015-05-01

    Very little is known about the influence of environmental radiation on living matter. In principle, important information can be acquired by analysing possible differences between parallel biological systems, one in a reference-radiation environment (RRE) and the other in a low-radiation environment (LRE). We took advantage of the unique opportunity represented by the cell culture facilities at the Gran Sasso National Laboratories of the Istituto Nazionale di Fisica Nucleare, where environment dose rate reduction factors in the underground (LRE), with respect to the external laboratory (RRE), are as follows: 10(3) for neutrons, 10(7) for directly ionizing cosmic rays and 10 for total γ-rays. Chinese hamster V79 cells were cultured for 10 months in both RRE and LRE. At the end of this period, all the cultures were kept in RRE for another 6 months. Changes in the activities of antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT; glutathione peroxidase, GPX) and spontaneous mutation frequency at the hypoxanthine-guanine phosphoribosyl transferase (hprt) locus were investigated. The results obtained suggest that environmental radiation might act as a trigger of defence mechanisms in V79 cells, specifically those in reference conditions, showing a higher degree of defence against endogenous damage as compared to cells grown in a very low-radiation environment. Our findings corroborate the hypothesis that environmental radiation contributes to the development of defence mechanisms in today living organisms/systems.

  12. Hardening electronic devices against very high total dose radiation environments

    Science.gov (United States)

    Buchanan, B.; Shedd, W.; Roosild, S.; Dolan, R.

    1972-01-01

    The possibilities and limitations of hardening silicon semiconductor devices to the high neutron and gamma radiation levels and greater than 10 to the eighth power rads required for the NERVA nuclear engine development are discussed. A comparison is made of the high dose neutron and gamma hardening potential of bipolar, metal insulator semiconductors and junction field effect transistors. Experimental data is presented on device degradation for the high neutron and gamma doses. Previous data and comparisons indicate that the JFET is much more immune to the combined neutron displacement and gamma ionizing effects than other transistor types. Experimental evidence is also presented which indicates that p channel MOS devices may be able to meet the requirements.

  13. Survey of current situation in radiation belt modeling

    Science.gov (United States)

    Fung, Shing F.

    2004-01-01

    The study of Earth's radiation belts is one of the oldest subjects in space physics. Despite the tremendous progress made in the last four decades, we still lack a complete understanding of the radiation belts in terms of their configurations, dynamics, and detailed physical accounts of their sources and sinks. The static nature of early empirical trapped radiation models, for examples, the NASA AP-8 and AE-8 models, renders those models inappropriate for predicting short-term radiation belt behaviors associated with geomagnetic storms and substorms. Due to incomplete data coverage, these models are also inaccurate at low altitudes (e.g., radiation data from modern space missions and advancement in physical modeling and data management techniques have now allowed the development of new empirical and physical radiation belt models. In this paper, we will review the status of modern radiation belt modeling. Published by Elsevier Ltd on behalf of COSPAR.

  14. Security Management Model in Cloud Computing Environment

    OpenAIRE

    2016-01-01

    In the cloud computing environment, cloud virtual machine (VM) will be more and more the number of virtual machine security and management faced giant Challenge. In order to address security issues cloud computing virtualization environment, this paper presents a virtual machine based on efficient and dynamic deployment VM security management model state migration and scheduling, study of which virtual machine security architecture, based on AHP (Analytic Hierarchy Process) virtual machine de...

  15. Modeling cell dynamics under mobile phone radiation.

    Science.gov (United States)

    Minelli, Tullio Antonio; Balduzzo, Maurizio; Milone, Francesco Ferro; Nofrate, Valentina

    2007-04-01

    Perturbations by pulse-modulated microwave radiation from GSM mobile phones on neuron cell membrane gating and calcium oscillations have been suggested as a possible mechanism underlying activation of brain states and electroencephalographic epiphenomena. As the employ of UMTS phones seems to reveal other symptoms, a unified phenomenological framework is needed. In order to explain possible effects of mobile phone radiation on cell oscillations, GSM and UMTS low-frequency envelopes have been detected, recorded and used as input in cell models. Dynamical systems endowed with contiguous regular and chaotic regimes suitable to produce stochastic resonance can both account for the perturbation of the neuro-electrical activity and even for the low intensity of the signal perceived by high sensitive subjects. Neuron models of this kind can be employed as a reductionist hint for the mentioned phenomenology. The Hindmarsh-Rose model exhibits frequency enhancement and regularization phenomena induced by weak GSM and UMTS. More realistic simulations of cell membrane gating and calcium oscillations have been performed with the help of an adaptation of the Chay-Keizer dynamical system. This scheme can explain the suspected subjective sensitivity to mobile phone signals under the thermal threshold, in terms of cell calcium regularity mechanisms. Concerning the two kinds of emission, the stronger occupation of the ELF band of last generation UMTS phones is compensated by lower power emitted.

  16. A 331 WIMPy dark radiation model

    Energy Technology Data Exchange (ETDEWEB)

    Kelso, Chris [University of Utah, Department of Physics and Astronomy, Salt Lake City, UT (United States); Pires, C.A. de S.; Rodrigues da Silva, P.S. [Universidade Federal da Paraiba, Departamento de Fisica, Caixa Postal 5008, Joao Pessoa, PB (Brazil); Profumo, Stefano; Queiroz, Farinaldo S. [University of California, Department of Physics and Santa Cruz Institute for Particle Physics, Santa Cruz, CA (United States)

    2014-03-15

    Recent observations suggest that the number of relativistic degrees of freedom in the early universe might exceed what is predicted in the standard cosmological model. If even a small, percent-level fraction of dark matter particles are produced relativistically, they could mimic the effect of an extra realistic species at matter-radiation equality while obeying BBN, CMB and Structure Formation bounds. We show that this scenario is quite naturally realized with a weak-scale dark matter particle and a high-scale ''mother'' particle within a well-motivated 3-3-1 gauge model, which is particularly interesting for being consistent with electroweak precision measurements, with recent LHC results, and for offering a convincing explanation for the number of generations in the Standard Model. (orig.)

  17. Radiation Protection of Environment under the Light of the New Concept of Radiation Protection of Non-Human Species

    Energy Technology Data Exchange (ETDEWEB)

    Hansruedi Voelkle [Swiss Federal Office of Public Health, Environmental Radioactivity Section, c/o Physics Department, University of Fribourg Chemin du Musee 3, 1700 Fribourg (Switzerland)

    2006-07-01

    The purpose of this presentation is to discuss the question of whether radiation protection should be extended to plants and animals. Until now the recommendations of ICRP have been focused exclusively on the protection of man from ionizing radiation. It was assumed that, if man is protected, the quality of the living environment is not impaired. In recent years adequate principles, recommendations and laws have become necessary in order to protect the environment from man made toxins. These recommendations aimed to conserve plants and animals, to maintain the diversity of species, the health and status of natural habitats and the natural resources of our planet, to warrant natural evolution and selection processes in order to transmit a healthy world to future generations. Reflections have been made as to whether particular protection of fauna and flora from ionizing radiation should be included. This article presents some considerations from the point of view of operational radiation protection and some comments to the work already done by ICRP committee 5. The final purpose is to invite the audience to make its own reflections and to communicate any criticisms, comments or suggestions to committee 5 of ICRP. (author)

  18. Polar firn layering in radiative transfer models

    Science.gov (United States)

    Linow, Stefanie; Hoerhold, Maria

    2016-04-01

    For many applications in the geosciences, remote sensing is the only feasible method of obtaining data from large areas with limited accessibility. This is especially true for the cryosphere, where light conditions and cloud coverage additionally limit the use of optical sensors. Here, instruments operating at microwave frequencies become important, for instance in polar snow parameters / SWE (snow water equivalent) mapping. However, the interaction between snow and microwave radiation is a complex process and still not fully understood. RT (radiative transfer) models to simulate snow-microwave interaction are available, but they require a number of input parameters such as microstructure and density, which are partly ill-constrained. The layering of snow and firn introduces an additional degree of complexity, as all snow parameters show a strong variability with depth. Many studies on RT modeling of polar firn deal with layer variability by using statistical properties derived from previous measurements, such as the standard deviations of density and microstructure, to configure model input. Here, the variability of microstructure parameters, such as density and particle size, are usually assumed to be independent of each other. However, in the case of the firn pack of the polar ice sheets, we observe that microstructure evolution depends on environmental parameters, such as temperature and snow deposition. Accordingly, density and microstructure evolve together within the snow and firn. Based on CT (computer tomography) microstructure measurements of antarctic firn, we can show that: first, the variability of density and effective grain size are linked and can thus be implemented in the RT models as a coupled set of parameters. Second, the magnitude of layering is captured by the measured standard deviation. Based on high-resolution density measurements of an Antarctic firn core, we study the effect of firn layering at different microwave wavelengths. By means of

  19. Organization and operation of the Sixth International Symposium on the Natural Radiation Environment (NRE VI)

    Energy Technology Data Exchange (ETDEWEB)

    Hopke, P.K.

    1996-10-01

    An important source of human exposure to radiation is the natural world including cosmic rays, cosmogenic radionuclides, natural terrestrial radionuclides, and radon isotopes and its decay products. Considerable effort is being expended on a worldwide basis to characterize the exposure to the natural radiation environment and determine the important pathways for the exposure to result in the dose to tissue that leads to injury and disease. The problem of background exposure to naturally occurring radioactivity has been the subject of research since the initial discovery of the radioactivity of uranium and thorium. However, with the advent of artificial sources of radiation with both benefits and harm the nature and magnitude of the natural radiation environment and the effects on various populations are important in the development of overall public health strategies as ALARA principles are applied to the situation.

  20. Using Space Weather Variability in Evaluation the Radiation Environment Specifications for NASA's Constellation Program

    Science.gov (United States)

    Coffey, Victoria N.; Minow, Joseph I.; Bruce, Margaret; Howard, James W.

    2008-01-01

    Hardware design environments for NASA's Constellation Program-the Vision for Space Exploration program to design and build new vehicles for servicing low Earth orbit and the Moon and beyond-have been developed that are necessarily conservative in nature to assure robust hardware design and development required to build space systems which will meet operational goals in a wide range of space environments, This presentation will describe the rationale used to establish the space radiation and plasma design environments specified for a variety of applications including total ionizing radiation dose, dose rate effects, and spacecraft charging and will compare the design environments with "space weather" variability to evaluate the applicability of the design environments and potential vulnerabilities of the system to extreme space weather events.

  1. Design and Modeling of a Variable Heat Rejection Radiator

    Science.gov (United States)

    Miller, Jennifer R.; Birur, Gajanana C.; Ganapathi, Gani B.; Sunada, Eric T.; Berisford, Daniel F.; Stephan, Ryan

    2011-01-01

    Variable Heat Rejection Radiator technology needed for future NASA human rated & robotic missions Primary objective is to enable a single loop architecture for human-rated missions (1) Radiators are typically sized for maximum heat load in the warmest continuous environment resulting in a large panel area (2) Large radiator area results in fluid being susceptible to freezing at low load in cold environment and typically results in a two-loop system (3) Dual loop architecture is approximately 18% heavier than single loop architecture (based on Orion thermal control system mass) (4) Single loop architecture requires adaptability to varying environments and heat loads

  2. The national operational environment model (NOEM)

    Science.gov (United States)

    Salerno, John J.; Romano, Brian; Geiler, Warren

    2011-06-01

    The National Operational Environment Model (NOEM) is a strategic analysis/assessment tool that provides insight into the complex state space (as a system) that is today's modern operational environment. The NOEM supports baseline forecasts by generating plausible futures based on the current state. It supports what-if analysis by forecasting ramifications of potential "Blue" actions on the environment. The NOEM also supports sensitivity analysis by identifying possible pressure (leverage) points in support of the Commander that resolves forecasted instabilities, and by ranking sensitivities in a list for each leverage point and response. The NOEM can be used to assist Decision Makers, Analysts and Researchers with understanding the inter-workings of a region or nation state, the consequences of implementing specific policies, and the ability to plug in new operational environment theories/models as they mature. The NOEM is built upon an open-source, license-free set of capabilities, and aims to provide support for pluggable modules that make up a given model. The NOEM currently has an extensive number of modules (e.g. economic, security & social well-being pieces such as critical infrastructure) completed along with a number of tools to exercise them. The focus this year is on modeling the social and behavioral aspects of a populace within their environment, primarily the formation of various interest groups, their beliefs, their requirements, their grievances, their affinities, and the likelihood of a wide range of their actions, depending on their perceived level of security and happiness. As such, several research efforts are currently underway to model human behavior from a group perspective, in the pursuit of eventual integration and balance of populace needs/demands within their respective operational environment and the capacity to meet those demands. In this paper we will provide an overview of the NOEM, the need for and a description of its main components

  3. Measurement and modelling of neon radiation profiles in radiating boundary discharges in ASDEX upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Dux, R.; Kallenbach, A.; Bessenrodt-Weberpals, M.; Behringer, K.; Bosch, H.S.; Fuchs, J.C.; Gehre, O.; Mast, F.; Poschenrieder, W.; Murmann, H.; Salzmann, H.; Schweinzer, J.; Suttrop, W. [MPI fuer Plasmaphysik, EURATOM Association, Garching and Berlin (Germany); ASDEX Upgrade- and NI-Team

    1996-02-01

    The radiation and transport characteristics of ASDEX Upgrade discharges with a neon driven radiative mantle are modelled using a 1-D radial impurity transport code that has been coupled to a simple divertor model describing particle recycling and pumping. The code is well suited to describe the measured impurity line radiation, total, soft X-ray and bremsstrahlung radiation in regions of the plasma which are not dominated by two dimensional effects. The recycling and pumping behaviour of neon as well as the bulk transport of neon for radiative boundary scenarios are discussed. (orig.)

  4. A study on the life extension of polymer materials under radiation environment

    Energy Technology Data Exchange (ETDEWEB)

    Park, K. J.; Park, S. W.; Cho, S. H.; Hong, S. S

    2000-12-01

    The object of this study is to improve the stability and the economic profit by reducing the radiation-induced degradation rate of polymer material used under the radiation environment. So far, the resistance to radiation-induced oxidation of a polymer has been improved by the stabilizers. They can play an important role in the anti-oxidants that interrupt the radical-mediated oxidation chain reaction. The stabilization effect could be larger than that achieved in an inert-atmosphere irradiation. Stabilization is a function of stabilizer concentration up to a certain threshold, but it is not further improved above this concentration. Beyond the threshold, the rate of radiation-induced oxidation goes up to the rate that is characteristic for the unstabilized polymer. To make up for this weakness, a technique depositing a thin layer of diamond-like carbon (DLC) on the polymer surface was developed for protecting the radiation-induced oxidation in the air.

  5. Interactive Visual Intervention Planning: Interactive Visualization for Intervention Planning in Particle Accelerator Environments with Ionizing Radiation

    CERN Document Server

    Fabry, Thomas; Feral, Bruno

    2013-01-01

    Intervention planning is crucial for maintenance operations in particle accelerator environments with ionizing radiation, during which the radiation dose contracted by maintenance workers should be reduced to a minimum. In this context, we discuss the visualization aspects of a new software tool, which integrates interactive exploration of a scene depicting an accelerator facility augmented with residual radiation level simulations, with the visualization of intervention data such as the followed trajectory and maintenance tasks. The visualization of each of these aspects has its effect on the final predicted contracted radiation dose. In this context, we explore the possible benefits of a user study, with the goal of enhancing the visual conditions in which the intervention planner using the software tool is minimizing the radiation dose.

  6. The Diurnal Cycle of the Boundary Layer, Convection, Clouds, and Surface Radiation in a Coastal Monsoon Environment (Darwin Australia)

    Energy Technology Data Exchange (ETDEWEB)

    May, Peter T.; Long, Charles N.; Protat, Alain

    2012-08-01

    The diurnal variation of convection and associated cloud and radiative properties remains a significant issue in global NWP and climate models. This study analyzes observed diurnal variability of convection in a coastal monsoonal environment examining the interaction of convective rain clouds, their associated cloud properties, and the impact on the surface radiation and corresponding boundary layer structure during periods where convection is suppressed or active on the large scale. The analysis uses data from the Tropical Warm Pool International Cloud Experiment (TWP-ICE) as well as routine measurements from the Australian Bureau of Meteorology and the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program. Both active monsoonal and large-scale suppressed (buildup and break) conditions are examined and demonstrate that the diurnal variation of rainfall is much larger during the break periods and the spatial distribution of rainfall is very different between the monsoon and break regimes. During the active monsoon the total net radiative input to the surface is decreased by more than 3 times the amount than during the break regime - this total radiative cloud forcing is found to be dominated by the shortwave (SW) cloud effects because of the much larger optical thicknesses and persistence of long-lasting anvils and cirrus cloud decks associated with the monsoon regime. These differences in monsoon versus break surface radiative energy contribute to low-level air temperature differences in the boundary layer over the land surfaces.

  7. A model to calculate solar radiation fluxes on the Martian surface

    Directory of Open Access Journals (Sweden)

    Vicente-Retortillo Álvaro

    2015-01-01

    Full Text Available We present a new comprehensive radiative transfer model to study the solar irradiance that reaches the surface of Mars in the spectral range covered by MetSIS, a sensor aboard the Mars MetNet mission that will measure solar irradiance in several bands from the ultraviolet (UV to the near infrared (NIR. The model includes up-to-date wavelength-dependent radiative properties of dust, water ice clouds, and gas molecules. It enables the characterization of the radiative environment in different spectral regions under different scenarios. Comparisons between the model results and MetSIS observations will allow for the characterization of the temporal variability of atmospheric optical depth and dust size distribution, enhancing the scientific return of the mission. The radiative environment at the Martian surface has important implications for the habitability of Mars as well as a strong impact on its atmospheric dynamics and climate.

  8. Realistic model for radiation-matter interaction

    CERN Document Server

    Pakula, R A

    2004-01-01

    This paper presents a realistic model that describes radiation-matter interactions. This is achieved by a generalization of first quantization, where the Maxwell equations are interpreted as the electromagnetic component of the Schrodinger equation. This picture is complemented by the consideration of electrons and photons as real particles in three-dimensional space, following guiding conditions derived from the particle-wave-functions to which they are associated. The guiding condition for the electron is taken from Bohmian mechanics, while the photon velocity is defined as the ratio between the Poynting vector and the electromagnetic energy density. The case of many particles is considered, taking into account their statistical properties. The formalism is applied to a two level system, providing an intuitive description for spontaneous emission, Lamb shift, scattering, absorption, dispersion, resonance fluorescence and vacuum fields. This model describes quantum jumps by the entanglement between the photo...

  9. Radiative Effects in the Standard Model Extension

    CERN Document Server

    Zhukovskii, V C; Murchikova, E M

    2006-01-01

    The possibility of radiative effects induced by the Lorentz and CPT non-invariant interaction term for fermions in the Standard Model Extension is investigated. In particular, electron-positron photo-production and photon emission by electrons and positrons were studied. The rates of these processes were calculated in the Furry picture. It was demonstrated that the rates obtained in the framework of the model adopted strongly depend on the polarization states of the particles involved. Indeed, ultra-relativistic particles should occupy states with a preferred spin orientation, i.e., photons have the sign of polarization opposite to the sign of the effective potential, while charged particle are preferably in the state with the helicity coinciding with the sign of the effective potential. This leads to evident spatial asymmetries which may have certain consequences observable in astrophysical and cosmological studies.

  10. STARLIFE - An International Campaign to Study the Role of Galactic Cosmic Radiation in Astrobiological Model Systems

    Science.gov (United States)

    Moeller, Ralf; Raguse, Marina; Leuko, Stefan; Berger, Thomas; Hellweg, Christine Elisabeth; Fujimori, Akira; Okayasu, Ryuichi; Horneck, Gerda

    2017-02-01

    In-depth knowledge regarding the biological effects of the radiation field in space is required for assessing the radiation risks in space. To obtain this knowledge, a set of different astrobiological model systems has been studied within the STARLIFE radiation campaign during six irradiation campaigns (2013-2015). The STARLIFE group is an international consortium with the aim to investigate the responses of different astrobiological model systems to the different types of ionizing radiation (X-rays, γ rays, heavy ions) representing major parts of the galactic cosmic radiation spectrum. Low- and high-energy charged particle radiation experiments have been conducted at the Heavy Ion Medical Accelerator in Chiba (HIMAC) facility at the National Institute of Radiological Sciences (NIRS) in Chiba, Japan. X-rays or γ rays were used as reference radiation at the German Aerospace Center (DLR, Cologne, Germany) or Beta-Gamma-Service GmbH (BGS, Wiehl, Germany) to derive the biological efficiency of different radiation qualities. All samples were exposed under identical conditions to the same dose and qualities of ionizing radiation (i) allowing a direct comparison between the tested specimens and (ii) providing information on the impact of the space radiation environment on currently used astrobiological model organisms.

  11. Radiation Belt Electron Dynamics: Modeling Atmospheric Losses

    Science.gov (United States)

    Selesnick, R. S.

    2003-01-01

    The first year of work on this project has been completed. This report provides a summary of the progress made and the plan for the coming year. Also included with this report is a preprint of an article that was accepted for publication in Journal of Geophysical Research and describes in detail most of the results from the first year of effort. The goal for the first year was to develop a radiation belt electron model for fitting to data from the SAMPEX and Polar satellites that would provide an empirical description of the electron losses into the upper atmosphere. This was largely accomplished according to the original plan (with one exception being that, for reasons described below, the inclusion of the loss cone electrons in the model was deferred). The main concerns at the start were to accurately represent the balance between pitch angle diffusion and eastward drift that determines the dominant features of the low altitude data, and then to accurately convert the model into simulated data based on the characteristics of the particular electron detectors. Considerable effort was devoted to achieving these ends. Once the model was providing accurate results it was applied to data sets selected from appropriate periods in 1997, 1998, and 1999. For each interval of -30 to 60 days, the model parameters were calculated daily, thus providing good short and long term temporal resolution, and for a range of radial locations from L = 2.7 to 3.9. .

  12. FAME - A Flexible Appearance Modelling Environment

    DEFF Research Database (Denmark)

    Stegmann, Mikkel Bille; Ersbøll, Bjarne Kjær; Larsen, Rasmus

    2003-01-01

    applications within medicine and describes a public domain implementation, namely the Flexible Appearance Modelling Environment (FAME). We give guidelines for the use of this research platform, and show that the optimisation techniques used renders it applicable to interactive medical applications. To increase....... Source code and annotated data sets needed to reproduce the results are put in the public domain for further investigation....

  13. Marketing research model of competitive environment

    Directory of Open Access Journals (Sweden)

    Krasilya Dmitriy

    2015-11-01

    Full Text Available To support its competitive advantages in current market conditions, each company needs to choose better ways of guaranteeing its favorable competitive position. In this regard, considerable interest lies in the structuring and algorithmization of marketing research processes that provide the information background of such choice. The article is devoted to modeling the process of marketing research of competitive environment.

  14. Habitability in High Radiation Environments: The Case for Gaia at Europa

    Science.gov (United States)

    Cooper, J. F.

    2004-12-01

    In the paper of Cooper et al. (2001) we concluded, in relation to our work on magnetospheric irradiation of Europa and the other icy galilean moons of Jupiter, that 'icy satellites with significant heat, irradiation, and subsurface water resources may provide common abodes for life throughout the universe'. This expanded the original proposal of Chyba (2000) and his later works that radiolytic production of oxidants and simple hydrocarbons on Europa's icy surface could support evolution and survival of life within a Europan subsurface ocean. In the general case of icy planets and moons the radiation environment does not have to interact directly with the surface but could also provide energy for life through radiation-induced chemistry in thick atmospheres chemically coupled to icy surfaces with hydrocarbon reservoirs as on Titan. The Gaia model for Earth implies that the entire planet operates with atmospheric, geologic, and geochemical processes conducive to life. Essential requirements for Gaia are an oxidizing atmospheric environment at planetary surfaces, where oxidants like molecular oxygen are produced by radiation processes (mediated by photosynthetic chemistry on Earth but more directly produced by radiolysis on Europa), reservoirs of liquid water and hydrocarbons on or below the surface, other reduced materials in the interior, and geologic processes which drive chemical exchange between the chemically oxidized surface and reduced interior environments. At Europa a thin oxygen atmosphere is observed and arises from magnetospheric interaction, and there is much evidence for active resurfacing likely related to solid-state convection and diapiric processes within a thick crust of soft ice overlying a liquid ocean. These processes on Europa are analogous to that of the tectonic conveyer belt that continually recycles carbon, oxygen, and other essential materials for life between the atmosphere, surface, and interior on Earth. The ice crust at Europa could be

  15. Ultraviolet radiation therapy and UVR dose models

    Energy Technology Data Exchange (ETDEWEB)

    Grimes, David Robert, E-mail: davidrobert.grimes@oncology.ox.ac.uk [School of Physical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland and Cancer Research UK/MRC Oxford Institute for Radiation Oncology, Gray Laboratory, University of Oxford, Old Road Campus Research Building, Oxford OX3 7DQ (United Kingdom)

    2015-01-15

    Ultraviolet radiation (UVR) has been an effective treatment for a number of chronic skin disorders, and its ability to alleviate these conditions has been well documented. Although nonionizing, exposure to ultraviolet (UV) radiation is still damaging to deoxyribonucleic acid integrity, and has a number of unpleasant side effects ranging from erythema (sunburn) to carcinogenesis. As the conditions treated with this therapy tend to be chronic, exposures are repeated and can be high, increasing the lifetime probability of an adverse event or mutagenic effect. Despite the potential detrimental effects, quantitative ultraviolet dosimetry for phototherapy is an underdeveloped area and better dosimetry would allow clinicians to maximize biological effect whilst minimizing the repercussions of overexposure. This review gives a history and insight into the current state of UVR phototherapy, including an overview of biological effects of UVR, a discussion of UVR production, illness treated by this modality, cabin design and the clinical implementation of phototherapy, as well as clinical dose estimation techniques. Several dose models for ultraviolet phototherapy are also examined, and the need for an accurate computational dose estimation method in ultraviolet phototherapy is discussed.

  16. Radiation Observations from CREAM & CREDO and Comparison with Standard Models

    Science.gov (United States)

    Dyer, C.; Watson, C.; Truscott, P.; Peerless, C.

    1996-12-01

    The Cosmic Radiation Environment and Activation Monitor (CREAM) has flown on six Shuttle flights between September 1991 and February 1995, covering the full range of inclinations as well as altitudes between 210 and 550 km. Meanwhile the Cosmic Radiation Environment and Dosimetry experiment (CREDO) has operated continuously on UOSAT-3 in 800 km, 98.7 degree orbit since April 1990. Similar detectors were launched on KITSAT-1 (1330 km, 66 degree inclination) in August 1992 and POSAT-l (790 km, 98.7 degree inclination) in September 1993. Since the summer of 1994, CREDO-II versions have been operating on APEX in an eccentric orbit (350x2486 km) at 70 degree inclination, and on STRV in geostationary transfer orbit (298x35953 km, 7 degree inclination). These experiments are designed to measure protons, cosmic rays and accumulated dose. Through the variety of missions employed they have now achieved wide coverage of the magnetosphere as well as a significant portion of a solar cycle. The LEO observations have shown the Westward drift of the South Atlantic Anomaly, new regimes of trapped protons in the region of L=2.6 following solar flare events in March 1991 and October 1992, and an altitude dependence of trapped protons which is at variance with AP8. On STRV the background channel of the Cold Ion Detector serves as a complementary electron detector and shows the extreme time variability of the outer radiation belt, while the total dose is significantly less than AE8 predictions. In addition to the data on trapped radiation, important results are being obtained on the linear energy transfer spectra from cosmic rays. Detailed shielding models of the APEX and STRV spacecraft have been constructed and used to compare the observations of dose and LET spectra with predictions from AE8, AP8 and CREME for a variety of shielding depths. Consistent results on the LET spectra are obtained from APEX and STRV when data are selected by cut-off rigidity. The influence of spacecraft

  17. Approach to reducing the effect of bone-coal power station on radiation environment

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The effect of two bone-coal power stations (6 MWe) on environment wasinvestigated within the scope of the dose contribution caused by various radionucildes in different ways. It is found that the best measures to reduce the effect of bone-coal power station on radiation environment include to select a fine boiler system and a comprehensive utilization of the bone-coal cinder (BCC), soot and ash in the catchers.

  18. Approach to reducing the effect of bone—coal power station on radiation environment

    Institute of Scientific and Technical Information of China (English)

    NIShi-Ying; GUPei-Long; 等

    2002-01-01

    The effect of two bone-coal power stations(6MWe) on environment was investigated within the scope of the dose contribution caused by various radionucildes in different ways.It is found that the best measures to reduce the effect of bone-coal power station on radiation environment include to select a fine boiler system and a comprehensive utilization of the bone-coal cinder(BCC),soot and ash in the catchers.

  19. Statistical Modeling for Radiation Hardness Assurance: Toward Bigger Data

    Science.gov (United States)

    Ladbury, R.; Campola, M. J.

    2015-01-01

    New approaches to statistical modeling in radiation hardness assurance are discussed. These approaches yield quantitative bounds on flight-part radiation performance even in the absence of conventional data sources. This allows the analyst to bound radiation risk at all stages and for all decisions in the RHA process. It also allows optimization of RHA procedures for the project's risk tolerance.

  20. A mathematical model for radiation hydrodynamics

    Directory of Open Access Journals (Sweden)

    Sebastiano Pennisi

    1990-11-01

    Full Text Available We adopt here the idea of describing a radiation field by means of the radiation energy density E and the radiative flux vector F which must satisfy a set of evolution equations; in these equations an unknown tensorial function P(E,F appears that is determined by the methods of extended thermodynamics.

  1. Radiation transport modeling and assessment to better predict radiation exposure, dose, and toxicological effects to human organs on long duration space flights

    Science.gov (United States)

    Denkins, P.; Badhwar, G.; Obot, V.; Wilson, B.; Jejelewo, O.

    2001-01-01

    NASA is very interested in improving its ability to monitor and forecast the radiation levels that pose a health risk to space-walking astronauts as they construct the International Space Station and astronauts that will participate in long-term and deep-space missions. Human exploratory missions to the moon and Mars within the next quarter century, will expose crews to transient radiation from solar particle events which include high-energy galactic cosmic rays and high-energy protons. Because the radiation levels in space are high and solar activity is presently unpredictable, adequate shielding is needed to minimize the deleterious health effects of exposure to radiation. Today, numerous models have been developed and used to predict radiation exposure. Such a model is the Space Environment Information Systems (SPENVIS) modeling program, developed by the Belgian Institute for Space Aeronautics. SPENVIS, which has been assessed to be an excellent tool in characterizing the radiation environment for microelectronics and investigating orbital debris, is being evaluated for its usefulness with determining the dose and dose-equivalent for human exposure. Thus far. the calculations for dose-depth relations under varying shielding conditions have been in agreement with calculations done using HZETRN and PDOSE, which are well-known and widely used models for characterizing the environments for human exploratory missions. There is disagreement when assessing the impact of secondary radiation particles since SPENVIS does a crude estimation of the secondary radiation particles when calculating LET versus Flux. SPENVIS was used to model dose-depth relations for the blood-forming organs. Radiation sickness and cancer are life-threatening consequences resulting from radiation exposure. In space. exposure to radiation generally includes all of the critical organs. Biological and toxicological impacts have been included for discussion along with alternative risk mitigation

  2. Flavour Dependent Gauged Radiative Neutrino Mass Model

    CERN Document Server

    Baek, Seungwon; Yagyu, Kei

    2015-01-01

    We propose a one-loop induced radiative neutrino mass model with anomaly free flavour dependent gauge symmetry: $\\mu$ minus $\\tau$ symmetry $U(1)_{\\mu-\\tau}$. A neutrino mass matrix satisfying current experimental data can be obtained by introducing a weak isospin singlet scalar boson that breaks $U(1)_{\\mu-\\tau}$ symmetry, an inert doublet scalar field, and three right-handed neutrinos in addition to the fields in the standard model. We find that a characteristic structure appears in the neutrino mass matrix: two-zero texture form which predicts three non-zero neutrino masses and three non-zero CP-phases which can be determined five well measured experimental inputs of two squared mass differences and three mixing angles. Furthermore, it is clarified that only the inverted mass hierarchy is allowed in our model. In a favored parameter set from the neutrino sector, the discrepancy in the muon anomalous magnetic moment between the experimental data and the the standard model prediction can be explained by the ...

  3. Near Field Environment Process Model Report

    Energy Technology Data Exchange (ETDEWEB)

    R.A. Wagner

    2000-11-14

    Waste emplacement and activities associated with construction of a repository system potentially will change environmental conditions within the repository system. These environmental changes principally result from heat generated by the decay of the radioactive waste, which elevates temperatures within the repository system. Elevated temperatures affect distribution of water, increase kinetic rates of geochemical processes, and cause stresses to change in magnitude and orientation from the stresses resulting from the overlying rock and from underground construction activities. The recognition of this evolving environment has been reflected in activities, studies and discussions generally associated with what has been termed the Near-Field Environment (NFE). The NFE interacts directly with waste packages and engineered barriers as well as potentially changing the fluid composition and flow conditions within the mountain. As such, the NFE defines the environment for assessing the performance of a potential Monitored Geologic Repository at Yucca Mountain, Nevada. The NFe evolves over time, and therefore is not amenable to direct characterization or measurement in the ambient system. Analysis or assessment of the NFE must rely upon projections based on tests and models that encompass the long-term processes of the evolution of this environment. This NFE Process Model Report (PMR) describes the analyses and modeling based on current understanding of the evolution of the near-field within the rock mass extending outward from the drift wall.

  4. Experimental Characterization of a Composite Morphing Radiator Prototype in a Relevant Thermal Environment

    Science.gov (United States)

    Bertagne, Christopher L.; Chong, Jorge B.; Whitcomb, John D.; Hartl, Darren J.; Erickson, Lisa R.

    2017-01-01

    For future long duration space missions, crewed vehicles will require advanced thermal control systems to maintain a desired internal environment temperature in spite of a large range of internal and external heat loads. Current radiators are only able to achieve turndown ratios (i.e. the ratio between the radiator's maximum and minimum heat rejection rates) of approximately 3:1. Upcoming missions will require radiators capable of 12:1 turndown ratios. A radiator with the ability to alter shape could significantly increase turndown capacity. Shape memory alloys (SMAs) offer promising qualities for this endeavor, namely their temperature-dependent phase change and capacity for work. In 2015, the first ever morphing radiator prototype was constructed in which SMA actuators passively altered the radiator shape in response to a thermal load. This work describes a follow-on endeavor to demonstrate a similar concept using highly thermally conductive composite materials. Numerous versions of this new concept were tested in a thermal vacuum environment and successfully demonstrated morphing behavior and variable heat rejection, achieving a turndown ratio of 4.84:1. A summary of these thermal experiments and their results are provided herein.

  5. Radiation protection of the environment: anthropocentric and eco-centric principles

    Energy Technology Data Exchange (ETDEWEB)

    Alexakhin, R.M.; Fesenko, S.V. [Russian Institute of Agricultural Radiology and Agroecology, RAAS, Obninsk (Russian Federation)

    2004-07-01

    The second half of the 20. century was dominated in the field of radiation protection by the anthropocentric concept stated by the International Commission on Radiological Protection (ICRP). According to this concept 'if radiation standards protect man then biota are also adequately protected from ionizing radiation'. At the end of the 20. beginning of the 21. centuries in the area of radiation protection of nature an eco-centric strategy is beginning to develop where emphasis has swung to the protection of biota in their environment. Inadequacy of ICRP's anthropocentric concept is reported. Issues are discussed such as ecological dosimetry, non-equi-dose irradiation of man and biota, criteria for estimating radiation induced changes in biota and man, as well as the need to harmonize permissible exposure doses to man and biota. An urgent need is stressed to develop a single (synthetic) concept of radiation protection which simultaneously ensures protection of human health and biota well-being in their environment. This concept is to be based on the recognition of the integrity of socio-natural ecosystems where man and biota are considered as a unity. (author)

  6. Radiative and dynamical modeling of Jupiter's atmosphere

    Science.gov (United States)

    Guerlet, Sandrine; Spiga, Aymeric

    2016-04-01

    Jupiter's atmosphere harbours a rich meteorology, with alternate westward and eastward zonal jets, waves signatures and long-living storms. Recent ground-based and spacecraft measurements have also revealed a rich stratospheric dynamics, with the observation of thermal signatures of planetary waves, puzzling meridional distribution of hydrocarbons at odds with predictions of photochemical models, and a periodic equatorial oscillation analogous to the Earth's quasi-biennal oscillation and Saturn's equatorial oscillation. These recent observations, along with the many unanswered questions (What drives and maintain the equatorial oscillations? How important is the seasonal forcing compared to the influence of internal heat? What is the large-scale stratospheric circulation of these giant planets?) motivated us to develop a complete 3D General Circulation Model (GCM) of Saturn and Jupiter. We aim at exploring the large-scale circulation, seasonal variability, and wave activity from the troposphere to the stratosphere of these giant planets. We will briefly present how we adapted our existing Saturn GCM to Jupiter. One of the main change is the addition of a stratospheric haze layer made of fractal aggregates in the auroral regions (poleward of 45S and 30N). This haze layer has a significant radiative impact by modifying the temperature up to +/- 15K in the middle stratosphere. We will then describe the results of radiative-convective simulations and how they compare to recent Cassini and ground-based temperature measurements. These simulations reproduce surprisingly well some of the observed thermal vertical and meridional gradients, but several important mismatches at low and high latitudes suggest that dynamics also plays an important role in shaping the temperature field. Finally, we will present full GCM simulations and discuss the main resulting features (waves and instabilities). We will also and discuss the impact of the choice of spatial resolution and

  7. Mathematical Models of Human Hematopoiesis Following Acute Radiation Exposure

    Science.gov (United States)

    2014-05-01

    the model predicts. Radiation dose from skin contamination can result in cutaneous injury leading to systemic responses and may im- pact the observed...medical and performance consequences from radiation and combined injuries , thereby enhancing our understanding of the potential impact of a nuclear...subsequently. In addition to the insight gained from combined injury modeling, the models of hematopoiesis and radiation alone provide clini- cally

  8. Stochastic modeling of p53-regulated apoptosis upon radiation damage

    CERN Document Server

    Bhatt, Divesh; Bahar, Ivet

    2011-01-01

    We develop and study the evolution of a model of radiation induced apoptosis in cells using stochastic simulations, and identified key protein targets for effective mitigation of radiation damage. We identified several key proteins associated with cellular apoptosis using an extensive literature survey. In particular, we focus on the p53 transcription dependent and p53 transcription independent pathways for mitochondrial apoptosis. Our model reproduces known p53 oscillations following radiation damage. The key, experimentally testable hypotheses that we generate are - inhibition of PUMA is an effective strategy for mitigation of radiation damage if the treatment is administered immediately, at later stages following radiation damage, inhibition of tBid is more effective.

  9. Adaptive response in frogs chronically exposed to low doses of ionizing radiation in the environment

    Energy Technology Data Exchange (ETDEWEB)

    Audette-Stuart, M., E-mail: stuartm@aecl.ca [Environmental Technologies Branch, Atomic Energy of Canada Limited, Chalk River Laboratories, Chalk River, Ontario, K0J 1P0 (Canada); Kim, S.B.; McMullin, D.; Festarini, A.; Yankovich, T.L.; Carr, J.; Mulpuru, S. [Environmental Technologies Branch, Atomic Energy of Canada Limited, Chalk River Laboratories, Chalk River, Ontario, K0J 1P0 (Canada)

    2011-06-15

    Using the micronucleus assay, decreased levels of DNA damage were found after high dose ionizing radiation exposure of liver cells taken from frogs inhabiting a natural environment with above-background levels of ionizing radiation, compared to cells taken from frogs inhabiting background areas. The data obtained from a small number of animals suggest that stress present in the above-background environment could induce an adaptive response to ionizing radiation. This study did not reveal harmful effects of exposure to low levels of radioactivity. On the contrary, stress present in the above-background area may serve to enhance cellular defense mechanisms. - Highlights: > Frogs were collected from background and higher tritium level habitats. > The micronucleus assay was conducted on liver cells obtained from the frogs. > No detrimental effects were noted in frogs exposed to elevated tritium. > Adaptive responses were observed in frogs exposed to elevated tritium.

  10. Radiation Impact to Environment of Non-nuclear Industry in Hunan,Hubei and Jiangxi Provinces

    Institute of Scientific and Technical Information of China (English)

    SONG; Wei-jie; CHENG; Wei-ya

    2015-01-01

    According to the gas,liquid effluent monitoring and survey results of non nuclear industry in Hunan,Hubei and Jiangxi provinces,the radiation effects of which on the surrounding environment were analysis and evaluation.Evaluation industrials includes three coal-fired power plants,two rare earth ores,two cement factories,one

  11. A Method for Estimating the Probability of Floating Gate Prompt Charge Loss in a Radiation Environment

    Science.gov (United States)

    Edmonds, L. D.

    2016-01-01

    Since advancing technology has been producing smaller structures in electronic circuits, the floating gates in modern flash memories are becoming susceptible to prompt charge loss from ionizing radiation environments found in space. A method for estimating the risk of a charge-loss event is given.

  12. Interactions of Changing Solar Ultraviolet Radiation and Climate with Light Induced Chemical Reactions in Aquatic Environments

    Science.gov (United States)

    Changes in the ozone layer over the past two decades have resulted in increases in solar ultraviolet radiation that reach the surface of North American aquatic environments. Concurrent changes in atmospheric CO2 are resulting in changes in stratification and precipitation that ar...

  13. A model of radiatively induced quark and lepton mass model

    Science.gov (United States)

    Nomura, Takaaki

    2017-07-01

    We discuss a radiatively induced quark and lepton mass model in the rst and second generation introducing extra U(1) gauge symmetry, discrete Z 2 symmetry, vector-like fermions and exotic scalar elds. Then we analyze the allowed parameter regions which simultaneously satisfy the constraints of FCNCs for the quark sector and of LFVs including μ - e conversion, observed quark mass and mixing, and the lepton mass and mixing. In addition, the typical value for the (g - 2) μ in our model is presented. We also show extension of the model in which Majorana type neutrino masses are generated at the two loop level.

  14. Methodology for calculation of radiation doses in the environs from nuclear fuel cycle facilities

    Energy Technology Data Exchange (ETDEWEB)

    Soldat, J.K.

    1976-08-01

    Comparison of the impacts of various nuclear fuel cycle alternatives includes the evaluation of the radiological impacts. To evaluate the radiological impacts of fuel cycle alternatives, exposure to man must first be identified. The pathways of consequence by which man can be exposed to radiation from a nuclear facility are listed and are grouped into those associated with gaseous effluents, those associated with liquid effluents, and those involving exposure to direct radiation from the facility or from transportation of radioactive materials to or from the facility. Calculations for each pathway were made for those selected organs which could potentially receive the highest radiation dose. Some of the programs developed for calculating radiation doses from radionuclides in the environment are described. (CH)

  15. Electromagnetic and radiation environments: effects on pacemakers; Environnements electromagnetiques et radiatifs: effets sur les stimulateurs cardiaques

    Energy Technology Data Exchange (ETDEWEB)

    Mouton, J.; Trochet, R.; Vicrey, J.; Sauvage, M. [CEA Bruyeres-le-Chatel, 91 (France); Chauvenet, B.; Ostrovski, A.; Leroy, E. [Bureau National de Metrologie, LPRI, CEA Saclay, 91 - Gif-sur-Yvette (France); Haug, R. [Centre National de la Recherche Scientifique (CNRS), Lab. de Physique des Gaz et des Plasma, SUPELEC, 91 - Orsay (France); Dodinot, B. [Centre de Stimulation Cardiaque, CHU de Brabois, 54 - Vandoeuvre les Nancy (France); Joffre, F. [CEA Saclay, Dept. d' Electronique et d' Instrumentation Nucleaire, LETI, 91 - Gif-sur-Yvette (France)

    1999-07-01

    Nowadays, medical care development allows many people to share the benefits of implanted pacemakers (PM). PM can be perturbed and even fall in complete breakdowns in an electromagnetic and radiation environment. A stimuli-dependent patient can thus be seriously in danger. This article presents the effect of ionizing radiation from either a cobalt-60 source or from a linear accelerator (Saturne 43) on 12 pacemakers. It seems that technological progress make electronic circuits more sensitive to the cumulated dose of radiation. This survey shows that pacemakers have great difficulties to sustain ionizing radiation doses that are commonly delivered to patients during therapies. Usually perturbed functioning appears suddenly and means a strong shift of stimuli that might lead to heart failure.

  16. Systematics in the application of natural radiation environments to allowable launch burden and its distribution

    Science.gov (United States)

    Barengoltz, J.

    A central feature of the advanced planetary protection planning for missions to Europa is the credit for the reduction of the spacecraft microbial burden by the radiation belts of Jupiter. Although the United States National Aeronautics and Space Administration planetary protection program has not yet set requirements for missions to Europa, the Space Studies Board of the National Research Council has published guidelines. Whether the requirements will be the allowable probability of contamination of Europa or the allowable microbial burden at launch, it is reasonable to consider the natural radiation environment in the approach to compliance. The systematics of the analysis for the microbial reduction due to the proton and electron environments of Jupiter's radiation belts include: a "shielding" representation of the spacecraft; the external mission fluence spectra of each of the natural radiation environments for the mission trajectory; a radiation transport analysis in the "shielding" representation for each of the spectra; and established planetary protection specifications of appropriate classes of microbes and the D-values (dose for a one order of magnitude reduction in population) by protons and electrons for each class. The proton dose and the electron dose in discrete regions of the spacecraft, the "nodes" of the "shielding" representation, an intermediate product, is analogous to the design of shielding for the protection of the system electronics. The application of the D-values to determine a lethality factor at each node for each class of microbe is unique to planetary protection. From the outlined procedure, the relationship between the microbial population at launch and at Europa encounter (or after any specific trajectory in the Jupiter radiation environment) may be calculated. Details of this outline will be presented. The precedent of the shielding analysis for Project Galileo and the analogy to the thermal analysis for the Viking lander terminal

  17. Potential Models for Radiative Rare B Decays

    CERN Document Server

    Ahmad, S

    2002-01-01

    We compute the branching ratios for the radiative rare decays of B into K-Meson states and compare them to the experimentally determined branching ratio for inclusive decay b -> s gamma using non relativistic quark model, and form factor definitions consistent with HQET covariant trace formalism. Such calculations necessarily involve a potential model. In order to test the sensitivity of calculations to potential models we have used three different potentials, namely linear potential, screening confining potential and heavy quark potential as it stands in QCD.We find the branching ratios relative to the inclusive b ->s gamma decay to be (16.07\\pm 5.2)% for B -> K^* (892)gamma and (7.25\\pm 3.2)% for B -> K_2^* (1430)gamma for linear potential. In the case of the screening confining potential these values are (19.75\\pm 5.3)% and (4.74\\pm 1.2)% while those for the heavy quark potential are (11.18\\pm 4.6)% and (5.09\\pm 2.7)% respectively. All these values are consistent with the corresponding present CLEO experim...

  18. Landauer Transport Model for Hawking Radiation from a Black Hole

    CERN Document Server

    Nation, P D; Nori, Franco

    2010-01-01

    We investigate the Hawking radiation energy and entropy flow rates from a black hole viewed as a one-dimensional (1D) Landauer transport process. The conformal symmetry in the near-horizon region leads directly to radiation rates that are identical to those of a single 1D quantum channel connected to a thermal reservoir at the Hawking temperature. The particle statistics independence of the 1D energy and entropy currents is applied to a black hole radiating into vacuum as well as one near thermal equilibrium with its environment. The Hawking radiation entropy production ratio is also examined.

  19. Effects of ozone depletion and UV-B radiation on humans and the environment

    Energy Technology Data Exchange (ETDEWEB)

    Solomon, K.R. [Guelph Univ., ON (Canada). Centre for Toxicology

    2008-03-15

    This paper summarized current research related to the effects of ultraviolet (UV-B) radiation on human health and the environment. Effects included direct responses in human as well as effects on biogeochemistry and the environmental cycling of substances. UV radiation has many harmful effects on the skin, eyes, and immune systems of humans. Skin cancer is a leading cause of death among fair-skinned populations exposed to UV radiation. The role of UV radiation in cataract formation was discussed, as well as issues related to the suppression of immune responses. The link between sunlight exposure and vitamin D levels in human populations was examined. The effects of UV radiation on terrestrial and aquatic ecosystems were reviewed. Issues related to biogeochemistry and atmospheric processes were discussed. The review suggested that changes in the intensity of solar UV radiation due to ozone depletion will have important repercussions for all organisms on the planet. It was concluded that the combined effects of UV-B radiation and climate change will not be easy to predict. 201 refs., 4 figs.

  20. Terrain and Radiation Mapping in Post-Disaster Environments Using an Autonomous Helicopter

    Directory of Open Access Journals (Sweden)

    Kevin Kochersberger

    2012-07-01

    Full Text Available Recent events have highlighted the need for unmanned remote sensing in dangerous areas, particularly where structures have collapsed or explosions have occurred, to limit hazards to first responders and increase their efficiency in planning response operations. In the case of the Fukushima nuclear reactor explosion, an unmanned helicopter capable of obtaining overhead images, gathering radiation measurements, and mapping both the structural and radiation content of the environment would have given the response team invaluable data early in the disaster, thereby allowing them to understand the extent of the damage and areas where dangers to personnel existed. With this motivation, the Unmanned Systems Lab at Virginia Tech has developed a remote sensing system for radiation detection and aerial imaging using a 90 kg autonomous helicopter and sensing payloads for the radiation detection and imaging operations. The radiation payload, which is the sensor of focus in this paper, consists of a scintillating type detector with associated software and novel search algorithms to rapidly and effectively map and locate sources of high radiation intensity. By incorporating this sensing technology into an unmanned aerial vehicle system, crucial situational awareness can be gathered about a post-disaster environment and response efforts can be expedited. This paper details the radiation mapping and localization capabilities of this system as well as the testing of the various search algorithms using simulated radiation data. The various components of the system have been flight tested over a several-year period and a new production flight platform has been built to enhance reliability and maintainability. The new system is based on the Aeroscout B1-100 helicopter platform, which has a one-hour flight endurance and uses a COFDM radio system that gives the helicopter an effective range of 7 km.

  1. Agent—oriented Virtual Environment Modeling

    Institute of Scientific and Technical Information of China (English)

    HEYulin; ZHENGTaixion

    2002-01-01

    Virtual environment has been widely applied in scientific research and considered as an important tool of exploring science.But constructing a real virtual environment is rather difficult.The difficulty cannot be compared with developing general software,It has a high demand for sofware technology,Obviously traditional methods are not competent for the job.Fortunately with the development of agent-oriented technologies ,all problems seem to be solved.By classifying a virtual environment into four layers corresponding with real world and considering it as a collection of agents,the virtual objects can be mapped into agents and an agent model can be designed.Based on the idea that the state change of a system is caused by that of in dividuals and the mutual effect among them,a theory of agent behavior driven by event and belief is put for ward.Such agent-oriented modeling method can cope with the demand for handling multi-dimension information.It is an effective technique for constructing a large and complex virtual environment.

  2. Preliminary design of CERN Future Circular Collider tunnel: first evaluation of the radiation environment in critical areas for electronics

    Science.gov (United States)

    Infantino, Angelo; Alía, Rubén García; Besana, Maria Ilaria; Brugger, Markus; Cerutti, Francesco

    2017-09-01

    As part of its post-LHC high energy physics program, CERN is conducting a study for a new proton-proton collider, called Future Circular Collider (FCC-hh), running at center-of-mass energies of up to 100 TeV in a new 100 km tunnel. The study includes a 90-350 GeV lepton collider (FCC-ee) as well as a lepton-hadron option (FCC-he). In this work, FLUKA Monte Carlo simulation was extensively used to perform a first evaluation of the radiation environment in critical areas for electronics in the FCC-hh tunnel. The model of the tunnel was created based on the original civil engineering studies already performed and further integrated in the existing FLUKA models of the beam line. The radiation levels in critical areas, such as the racks for electronics and cables, power converters, service areas, local tunnel extensions was evaluated.

  3. Real-Time Aircraft Cosmic Ray Radiation Exposure Predictions from the NAIRAS Model

    Science.gov (United States)

    Mertens, C. J.; Tobiska, W.; Kress, B. T.; Xu, X.

    2012-12-01

    The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a prototype operational model for predicting commercial aircraft radiation exposure from galactic and solar cosmic rays. NAIRAS predictions are currently streaming live from the project's public website, and the exposure rate nowcast is also available on the SpaceWx smartphone app for iPhone, IPad, and Android. Cosmic rays are the primary source of human exposure to high linear energy transfer radiation at aircraft altitudes, which increases the risk of cancer and other adverse health effects. Thus, the NAIRAS model addresses an important national need with broad societal, public health and economic benefits. There is also interest in extending NAIRAS to the LEO environment to address radiation hazard issues for the emerging commercial spaceflight industry. The processes responsible for the variability in the solar wind, interplanetary magnetic field, solar energetic particle spectrum, and the dynamical response of the magnetosphere to these space environment inputs, strongly influence the composition and energy distribution of the atmospheric ionizing radiation field. Real-time observations are required at a variety of locations within the geospace environment. The NAIRAS model is driven by real-time input data from ground-, atmospheric-, and space-based platforms. During the development of the NAIRAS model, new science questions and observational data gaps were identified that must be addressed in order to obtain a more reliable and robust operational model of atmospheric radiation exposure. The focus of this talk is to present the current capabilities of the NAIRAS model, discuss future developments in aviation radiation modeling and instrumentation, and propose strategies and methodologies of bridging known gaps in current modeling and observational capabilities.

  4. Analytical-HZETRN Model for Rapid Assessment of Active Magnetic Radiation Shielding

    Science.gov (United States)

    Washburn, S. A.; Blattnig, S. R.; Singleterry, R. C.; Westover, S. C.

    2014-01-01

    The use of active radiation shielding designs has the potential to reduce the radiation exposure received by astronauts on deep-space missions at a significantly lower mass penalty than designs utilizing only passive shielding. Unfortunately, the determination of the radiation exposure inside these shielded environments often involves lengthy and computationally intensive Monte Carlo analysis. In order to evaluate the large trade space of design parameters associated with a magnetic radiation shield design, an analytical model was developed for the determination of flux inside a solenoid magnetic field due to the Galactic Cosmic Radiation (GCR) radiation environment. This analytical model was then coupled with NASA's radiation transport code, HZETRN, to account for the effects of passive/structural shielding mass. The resulting model can rapidly obtain results for a given configuration and can therefore be used to analyze an entire trade space of potential variables in less time than is required for even a single Monte Carlo run. Analyzing this trade space for a solenoid magnetic shield design indicates that active shield bending powers greater than 15 Tm and passive/structural shielding thicknesses greater than 40 g/cm2 have a limited impact on reducing dose equivalent values. Also, it is shown that higher magnetic field strengths are more effective than thicker magnetic fields at reducing dose equivalent.

  5. Predictive Model of Radiative Neutrino Masses

    CERN Document Server

    Babu, K S

    2013-01-01

    We present a simple and predictive model of radiative neutrino masses. It is a special case of the Zee model which introduces two Higgs doublets and a charged singlet. We impose a family-dependent Z_4 symmetry acting on the leptons, which reduces the number of parameters describing neutrino oscillations to four. A variety of predictions follow: The hierarchy of neutrino masses must be inverted; the lightest neutrino mass is extremely small and calculable; one of the neutrino mixing angles is determined in terms of the other two; the phase parameters take CP-conserving values with \\delta_{CP} = \\pi; and the effective mass in neutrinoless double beta decay lies in a narrow range, m_{\\beta \\beta} = (17.6 - 18.5) meV. The ratio of vacuum expectation values of the two Higgs doublets, tan\\beta, is determined to be either 1.9 or 0.19 from neutrino oscillation data. Flavor-conserving and flavor-changing couplings of the Higgs doublets are also determined from neutrino data. The non-standard neutral Higgs bosons, if t...

  6. Patient exposure and radiation environment of an extracorporeal shock wave lithotriptor system

    Energy Technology Data Exchange (ETDEWEB)

    Lin, P.J.; Hrejsa, A.F.

    1987-10-01

    Radiation exposures to the patient undergoing extracorporeal shock wave lithotripsy were assessed along with the scattered radiation levels around the lithotriptor systems. The data gathered from 2 Dornier lithotriptor systems suggest that the lead shieldings required for this particular make and model are minimal. Owing to the physical size of the lithotriptor system, the treatment room housing it may not require additional lead shielding when the walls are constructed with appropriate materials. Typical radiation exposures to the patient have been assessed from the experimental data. The total amount of radiation exposures a patient is likely to receive has been estimated to be approximately 26 roentgens, for example 21 roentgens from 3 to 4 minutes of fluoroscopic exposure and 5 roentgens from 8 frames of video spot filming. The scattered radiation has been found to be approximately 0.5 mR. per hour at 3 feet or 91 cm. from the center of the lithotriptor water tank.

  7. [Radiation protection of the environment: anthropocentric and eco-centric principles].

    Science.gov (United States)

    Aleksakhin, R M; Fesenko, S V

    2004-01-01

    The second half of the XX century was dominated in the field of radiation protection of the environment by the anthropocentric concept stated by the International Commission on Radiological Protection (ICRP). According to this concept "if man is adequately protected by radiological standards then biota are also adequately protected". At the end of the XX--beginning of the XXI centuries in the area of area of radiation protection of nature an ecocentric strategy is beginning to develop where emphasis has swung to the protection of biota in their environment. Inadequacy of ICRP's anthroposentric concept is reported. Issues are discussed such as ecological dosimetry, nonequidosal irradiation of man and biota, criteria for estimating radiation induced changes in biota and man, as well as the need to harmonize permissible exposure doses to man and biota. An urgent need is stressed to develop a single (synthetic) concept of radiation protection which simultaneously ensures protection of human health and biota well-being in their environment. This concept is to be based on the recognition of the integrity of socio-natural ecosystems where man and biota are considered as a unity.

  8. "BION-M" No.1 spacecraft radiation environment as observed in April-May 2013. Comparison with ISS data

    Science.gov (United States)

    Dachev, Tsvetan; Horneck, Gerda; Reitz, Guenther; Semkova, Jordanka; Schuster, Martin; Lebert, Michael; Malchev, Stefan; Tomov, Borislav; Matviichuk, Yury; Dimitrov, Plamen; Ivanova, Olga; Haeder, Donat-Peter; Bankov, Nikolai; Shurshakov, Vyacheslav; Benghin, Victor; K, Rositza

    Space radiation has been monitored in the period 19 April-13 May 2013 using RD3-B3 spectrometer-dosimeter on board the Russian recoverable satellite "BION-M" No.1. The instrument was mounted inside of the satellite pressurized volume together with biological objects and samples. RD3-B3 instrument is a battery operated version of the spare model of the R3D-B3 instrument developed and successfully worked on the ESA Biopan-6 facility on Foton M3 satellite in September 2007. Cosmic ionizing radiation has been monitored and separated in 256 deposited energy spectra, which were further used for determination of the absorbed dose rate and flux. The obtained history of accumulation and the daily and hourly values for the space radiation are presented in the paper ant they can contribute to a better understanding of the results from the biological experiments. Analogical data were obtained simultaneously on the International Space Station (ISS) using the Liulin-5 charged particle telescope. The paper summarizes the results for the global distribution of the Earth radiation environment at the altitude of the "BION-M" No.1 spacecraft and compares these data with the Liulin-5 data at the ISS and with AP/AE-8 MAX model.

  9. Effective UV radiation from model calculations and measurements

    Science.gov (United States)

    Feister, Uwe; Grewe, Rolf

    1994-01-01

    Model calculations have been made to simulate the effect of atmospheric ozone and geographical as well as meteorological parameters on solar UV radiation reaching the ground. Total ozone values as measured by Dobson spectrophotometer and Brewer spectrometer as well as turbidity were used as input to the model calculation. The performance of the model was tested by spectroradiometric measurements of solar global UV radiation at Potsdam. There are small differences that can be explained by the uncertainty of the measurements, by the uncertainty of input data to the model and by the uncertainty of the radiative transfer algorithms of the model itself. Some effects of solar radiation to the biosphere and to air chemistry are discussed. Model calculations and spectroradiometric measurements can be used to study variations of the effective radiation in space in space time. The comparability of action spectra and their uncertainties are also addressed.

  10. Architecture of the Product State Model Environment

    DEFF Research Database (Denmark)

    Holm Larsen, Michael; Lynggaard, Hans Jørgen B.

    2003-01-01

    This paper addresses the issue of using product models to support product lifecycle activities withparticular focus on the production phase. The motivation of the research is that products are producedmore costly and with longer lead-time than necessary.The paper provides a review of product...... modelling technologies and approaches, and the overallarchitecture for the Product State Model (PSM) Environment as a basis for quality monitoring.Especially, the paper focuses on the circumstances prevailing in a one-of-a-kind manufacturingenvironment like the shipbuilding industry, where product modelling...... technologies already haveproved their worth in the design and engineering phases of shipbuilding and in the operation phase.However, the handling of product information on the shop floor is not yet equally developed.The paper reports from the Brite-Euram project (No. BE97-4510) QualiGlobe focusing...

  11. Radiation Effects Investigations Based on Atmospheric Radiation Model (ATMORAD) Considering GEANT4 Simulations of Extensive Air Showers and Solar Modulation Potential.

    Science.gov (United States)

    Hubert, Guillaume; Cheminet, Adrien

    2015-07-01

    The natural radiative atmospheric environment is composed of secondary cosmic rays produced when primary cosmic rays hit the atmosphere. Understanding atmospheric radiations and their dynamics is essential for evaluating single event effects, so that radiation risks in aviation and the space environment (space weather) can be assessed. In this article, we present an atmospheric radiation model, named ATMORAD (Atmospheric Radiation), which is based on GEANT4 simulations of extensive air showers according to primary spectra that depend only on the solar modulation potential (force-field approximation). Based on neutron spectrometry, solar modulation potential can be deduced using neutron spectrometer measurements and ATMORAD. Some comparisons between our methodology and standard approaches or measurements are also discussed. This work demonstrates the potential for using simulations of extensive air showers and neutron spectroscopy to monitor solar activity.

  12. Dermatopathology effects of simulated solar particle event radiation exposure in the porcine model

    Science.gov (United States)

    Sanzari, Jenine K.; Diffenderfer, Eric S.; Hagan, Sarah; Billings, Paul C.; Gridley, Daila S.; Seykora, John T.; Kennedy, Ann R.; Cengel, Keith A.

    2015-07-01

    The space environment exposes astronauts to risks of acute and chronic exposure to ionizing radiation. Of particular concern is possible exposure to ionizing radiation from a solar particle event (SPE). During an SPE, magnetic disturbances in specific regions of the Sun result in the release of intense bursts of ionizing radiation, primarily consisting of protons that have a highly variable energy spectrum. Thus, SPE events can lead to significant total body radiation exposures to astronauts in space vehicles and especially while performing extravehicular activities. Simulated energy profiles suggest that SPE radiation exposures are likely to be highest in the skin. In the current report, we have used our established miniature pig model system to evaluate the skin toxicity of simulated SPE radiation exposures that closely resemble the energy and fluence profile of the September, 1989 SPE using either conventional radiation (electrons) or proton simulated SPE radiation. Exposure of animals to electron or proton radiation led to dose-dependent increases in epidermal pigmentation, the presence of necrotic keratinocytes at the dermal-epidermal boundary and pigment incontinence, manifested by the presence of melanophages in the derm is upon histological examination. We also observed epidermal hyperplasia and a reduction in vascular density at 30 days following exposure to electron or proton simulated SPE radiation. These results suggest that the doses of electron or proton simulated SPE radiation results in significant skin toxicity that is quantitatively and qualitatively similar. Radiation-induced skin damage is often one of the first clinical signs of both acute and non-acute radiation injury where infection may occur, if not treated. In this report, histopathology analyses of acute radiation-induced skin injury are discussed.

  13. Dermatopathology effects of simulated solar particle event radiation exposure in the porcine model.

    Science.gov (United States)

    Sanzari, Jenine K; Diffenderfer, Eric S; Hagan, Sarah; Billings, Paul C; Gridley, Daila S; Seykora, John T; Kennedy, Ann R; Cengel, Keith A

    2015-07-01

    The space environment exposes astronauts to risks of acute and chronic exposure to ionizing radiation. Of particular concern is possible exposure to ionizing radiation from a solar particle event (SPE). During an SPE, magnetic disturbances in specific regions of the Sun result in the release of intense bursts of ionizing radiation, primarily consisting of protons that have a highly variable energy spectrum. Thus, SPE events can lead to significant total body radiation exposures to astronauts in space vehicles and especially while performing extravehicular activities. Simulated energy profiles suggest that SPE radiation exposures are likely to be highest in the skin. In the current report, we have used our established miniature pig model system to evaluate the skin toxicity of simulated SPE radiation exposures that closely resemble the energy and fluence profile of the September, 1989 SPE using either conventional radiation (electrons) or proton simulated SPE radiation. Exposure of animals to electron or proton radiation led to dose-dependent increases in epidermal pigmentation, the presence of necrotic keratinocytes at the dermal-epidermal boundary and pigment incontinence, manifested by the presence of melanophages in the derm is upon histological examination. We also observed epidermal hyperplasia and a reduction in vascular density at 30 days following exposure to electron or proton simulated SPE radiation. These results suggest that the doses of electron or proton simulated SPE radiation results in significant skin toxicity that is quantitatively and qualitatively similar. Radiation-induced skin damage is often one of the first clinical signs of both acute and non-acute radiation injury where infection may occur, if not treated. In this report, histopathology analyses of acute radiation-induced skin injury are discussed.

  14. Second Law Analysis of the Earth System with a Radiative Model

    Directory of Open Access Journals (Sweden)

    Sean Wright

    2002-06-01

    Full Text Available Solar radiation provides the energy for many processes on Earth including processes that sustain living systems and circulation of the atmosphere and oceans. The Earth does not consume this energy; it is simply converted to outgoing thermal radiation. However, the entropy production rate of Earth causes energy degradation and the exergy destruction rate quantifies this degradation relative to a reference environment. The global entropy production rate also provides an additional constraint for comparison with atmospheric modeling results. In this paper a simplified expression for the global entropy production rate, associated with the absorbed portion of the solar flux, is presented based on a radiative model. The second purpose of this work is to investigate the exergetic analysis of the Earth. It is desirable to consider environment temperatures that are typical temperatures on Earth when comparing the total entropy production rate and irreversibility rate of the planet to those due to processes such as the global energy system; in other words, typical temperatures where these processes occur. However, multiplying the estimated global entropy production rate by an arbitrary environment temperature appears to result in irreversibility rates that violate the second law of thermodynamics. It is shown that the radiative interaction of the Earth with its surroundings can be theoretically modeled and tested in a laboratory environment showing that arbitrary environment temperature specifications should not cause these violations. These apparent violations are resolved through corrections to the energy, entropy and exergy calculations that are due to the specific character of radiative heat transfer. As a result, this analysis also provides an illustrative example of the implications of environment specifications on exergy analysis involving radiative heat transfer.

  15. Cloud radiative effects and changes simulated by the Coupled Model Intercomparison Project Phase 5 models

    Science.gov (United States)

    Shin, Sun-Hee; Kim, Ok-Yeon; Kim, Dongmin; Lee, Myong-In

    2017-07-01

    Using 32 CMIP5 (Coupled Model Intercomparison Project Phase 5) models, this study examines the veracity in the simulation of cloud amount and their radiative effects (CREs) in the historical run driven by observed external radiative forcing for 1850-2005, and their future changes in the RCP (Representative Concentration Pathway) 4.5 scenario runs for 2006-2100. Validation metrics for the historical run are designed to examine the accuracy in the representation of spatial patterns for climatological mean, and annual and interannual variations of clouds and CREs. The models show large spread in the simulation of cloud amounts, specifically in the low cloud amount. The observed relationship between cloud amount and the controlling large-scale environment are also reproduced diversely by various models. Based on the validation metrics, four models—ACCESS1.0, ACCESS1.3, HadGEM2-CC, and HadGEM2-ES—are selected as best models, and the average of the four models performs more skillfully than the multimodel ensemble average. All models project global-mean SST warming at the increase of the greenhouse gases, but the magnitude varies across the simulations between 1 and 2 K, which is largely attributable to the difference in the change of cloud amount and distribution. The models that simulate more SST warming show a greater increase in the net CRE due to reduced low cloud and increased incoming shortwave radiation, particularly over the regions of marine boundary layer in the subtropics. Selected best-performing models project a significant reduction in global-mean cloud amount of about -0.99% K-1 and net radiative warming of 0.46 W m-2 K-1, suggesting a role of positive feedback to global warming.

  16. Overshooting dynamics in a model adaptive radiation

    NARCIS (Netherlands)

    Meyer, J.R.; Schoustra, S.E.; LaChapelle, J.; Kassen, R.K.

    2011-01-01

    The history of life is punctuated by repeated periods of unusually rapid evolutionary diversification called adaptive radiation. The dynamics of diversity during a radiation reflect an overshooting pattern with an initial phase of exponential-like increase followed by a slower decline. Much

  17. Micro Penning Trap for Continuous Magnetic Field Monitoring in High Radiation Environments

    Science.gov (United States)

    Latorre, Javiera; Bollen, Georg; Gulyuz, Kerim; Ringle, Ryan; Bado, Philippe; Dugan, Mark; Lebit Team; Translume Collaboration

    2016-09-01

    As new facilities for rare isotope beams, like FRIB at MSU, are constructed, there is a need for new instrumentation to monitor magnetic fields in beam magnets that can withstand the higher radiation level. Currently NMR probes, the instruments used extensively to monitor magnetic fields, do not have a long lifespans in radiation-high environments. Therefore, a radiation-hard replacement is needed. We propose to use Penning trap mass spectrometry techniques to make high precision magnetic field measurements. Our Penning microtrap will be radiation resistant as all of the vital electronics will be at a safe distance from the radiation. The trap itself is made from materials not subject to radiation damage. Penning trap mass spectrometers can determine the magnetic field by measuring the cyclotron frequency of an ion with a known mass and charge. This principle is used on the Low Energy Beam Ion Trap (LEBIT) minitrap at NSCL which is the foundation for the microtrap. We have partnered with Translume, who specialize in glass micro-fabrication, to develop a microtrap in fused-silica glass. A microtrap is finished and ready for testing at NSCL with all of the electronic and hardware components setup. DOE Phase II SBIR Award No. DE-SC0011313, NSF Award Number 1062410 REU in Physics, NSF under Grant No. PHY-1102511.

  18. Guidelines for effective radiation transport for cable SGEMP modeling

    Energy Technology Data Exchange (ETDEWEB)

    Drumm, Clifton Russell [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Fan, Wesley C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Turner, C. David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-07-01

    This report describes experiences gained in performing radiation transport computations with the SCEPTRE radiation transport code for System Generated ElectroMagnetic Pulse (SGEMP) applications. SCEPTRE is a complex code requiring a fairly sophisticated user to run the code effectively, so this report provides guidance for analysts interested in performing these types of calculations. One challenge in modeling coupled photon/electron transport for SGEMP is to provide a spatial mesh that is sufficiently resolved to accurately model surface charge emission and charge deposition near material interfaces. The method that has been most commonly used to date to compute cable SGEMP typically requires a sub-micron mesh size near material interfaces, which may be difficult for meshing software to provide for complex geometries. We present here an alternative method for computing cable SGEMP that appears to substantially relax this requirement. The report also investigates the effect of refining the energy mesh and increasing the order of the angular approximation to provide some guidance on determining reasonable parameters for the energy/angular approximation needed for x-ray environments. Conclusions for γ-ray environments may be quite different and will be treated in a subsequent report. In the course of the energy-mesh refinement studies, a bug in the cross-section generation software was discovered that may cause underprediction of the result by as much as an order of magnitude for the test problem studied here, when the electron energy group widths are much smaller than those for the photons. Results will be presented and compared using cross sections generated before and after the fix. We also describe adjoint modeling, which provides sensitivity of the total charge drive to the source energy and angle of incidence, which is quite useful for comparing the effect of changing the source environment and for determining most stressing angle of incidence and source

  19. Guidelines for effective radiation transport for cable SGEMP modeling

    Energy Technology Data Exchange (ETDEWEB)

    Drumm, Clifton Russell [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Fan, Wesley C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Turner, C. David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-07-01

    This report describes experiences gained in performing radiation transport computations with the SCEPTRE radiation transport code for System Generated ElectroMagnetic Pulse (SGEMP) applications. SCEPTRE is a complex code requiring a fairly sophisticated user to run the code effectively, so this report provides guidance for analysts interested in performing these types of calculations. One challenge in modeling coupled photon/electron transport for SGEMP is to provide a spatial mesh that is sufficiently resolved to accurately model surface charge emission and charge deposition near material interfaces. The method that has been most commonly used to date to compute cable SGEMP typically requires a sub-micron mesh size near material interfaces, which may be difficult for meshing software to provide for complex geometries. We present here an alternative method for computing cable SGEMP that appears to substantially relax this requirement. The report also investigates the effect of refining the energy mesh and increasing the order of the angular approximation to provide some guidance on determining reasonable parameters for the energy/angular approximation needed for x-ray environments. Conclusions for -ray environments may be quite different and will be treated in a subsequent report. In the course of the energy-mesh refinement studies, a bug in the cross-section generation software was discovered that may cause under prediction of the result by as much as an order of magnitude for the test problem studied here, when the electron energy group widths are much smaller than those for the photons. Results will be presented and compared using cross sections generated before and after the fix. We also describe adjoint modeling, which provides sensitivity of the total charge drive to the source energy and angle of incidence, which is quite useful for comparing the effect of changing the source environment and for determining most stressing angle of incidence and

  20. Radiation environment of the LHCb Calorimeters in 2010-2013 (under review)

    CERN Document Server

    Corti, Gloria

    2017-01-01

    A set of passive and active radiation detectors has been installed around and in between the LHCb calorimeter subsystems to measure different aspects of the radiation environment. Cross calibrations between various types of measurements are performed and correlated with the evolving run conditions. Measurements are compared to FLUKA simulation estimates and an evaluation of the reliability of the simulation in different running scenarios is provided. The simulation is based on a detailed geometry of the LHCb experiment and reflects the conditions of Run1 with 7 and 8 TeV CM proton-proton collision energies. A carefully characterised simulation of radiation levels in the LHCb experiment is essential in providing input for technical choices in view of the planned upgrade of the experiment for operation at higher luminosity.

  1. Monte Carlo modeling in CT-based geometries: dosimetry for biological modeling experiments with particle beam radiation.

    Science.gov (United States)

    Diffenderfer, Eric S; Dolney, Derek; Schaettler, Maximilian; Sanzari, Jenine K; McDonough, James; Cengel, Keith A

    2014-03-01

    The space radiation environment imposes increased dangers of exposure to ionizing radiation, particularly during a solar particle event (SPE). These events consist primarily of low energy protons that produce a highly inhomogeneous dose distribution. Due to this inherent dose heterogeneity, experiments designed to investigate the radiobiological effects of SPE radiation present difficulties in evaluating and interpreting dose to sensitive organs. To address this challenge, we used the Geant4 Monte Carlo simulation framework to develop dosimetry software that uses computed tomography (CT) images and provides radiation transport simulations incorporating all relevant physical interaction processes. We found that this simulation accurately predicts measured data in phantoms and can be applied to model dose in radiobiological experiments with animal models exposed to charged particle (electron and proton) beams. This study clearly demonstrates the value of Monte Carlo radiation transport methods for two critically interrelated uses: (i) determining the overall dose distribution and dose levels to specific organ systems for animal experiments with SPE-like radiation, and (ii) interpreting the effect of random and systematic variations in experimental variables (e.g. animal movement during long exposures) on the dose distributions and consequent biological effects from SPE-like radiation exposure. The software developed and validated in this study represents a critically important new tool that allows integration of computational and biological modeling for evaluating the biological outcomes of exposures to inhomogeneous SPE-like radiation dose distributions, and has potential applications for other environmental and therapeutic exposure simulations.

  2. Modeling Radiative Heat Transfer and Turbulence-Radiation Interactions in Engines

    Energy Technology Data Exchange (ETDEWEB)

    Paul, Chandan [Pennsylvania State Univ., University Park, PA (United States); Sircar, Arpan [Pennsylvania State Univ., University Park, PA (United States); Ferreyro-Fernandez, Sebastian [Pennsylvania State Univ., University Park, PA (United States); Imren, Abdurrahman [Pennsylvania State Univ., University Park, PA (United States); Haworth, Daniel C [Pennsylvania State Univ., University Park, PA (United States); Roy, Somesh P [Marquette University (United States); Ge, Wenjun [University of California Merced (United States); Modest, Michael F [University of California Merced (United States)

    2017-04-26

    Detailed radiation modelling in piston engines has received relatively little attention to date. Recently, it is being revisited in light of current trends towards higher operating pressures and higher levels of exhaust-gas recirculation, both of which enhance molecular gas radiation. Advanced high-efficiency engines also are expected to function closer to the limits of stable operation, where even small perturbations to the energy balance can have a large influence on system behavior. Here several different spectral radiation property models and radiative transfer equation (RTE) solvers have been implemented in an OpenFOAM-based engine CFD code, and simulations have been performed for a full-load (peak pressure ~200 bar) heavy-duty diesel engine. Differences in computed temperature fields, NO and soot levels, and wall heat transfer rates are shown for different combinations of spectral models and RTE solvers. The relative importance of molecular gas radiation versus soot radiation is examined. And the influence of turbulence-radiation interactions is determined by comparing results obtained using local mean values of composition and temperature to compute radiative emission and absorption with those obtained using a particle-based transported probability density function method.

  3. Study on the mechanical property of polyimide film in space radiation environments

    Science.gov (United States)

    Shen, Zicai; Mu, Yongqiang; Ding, Yigang; Liu, Yuming; Zhao, Chunqing

    2016-01-01

    Polyimide films are widely used in spacecraft, but their mechanical properties would degrade in space environments, such as electron, proton, near ultraviolet or far ultraviolet, etc. The mechanical property and mechanism of polyimide film in electron, proton, near ultraviolet and far ultraviolet was studied by Φ800 combined space radiation test facility of Beijing Institute of Space Environment Engineering (BISSE. Rupture elongation of Kapton film decrease with the increase of the tensile deformation rate. The tensile strength and the rupture elongation of Kapton film decrease with the increase of electron and proton radiation, while tensile strength and the rupture elongation of Kapton film decrease firstly and then increase with near ultraviolet and far ultraviolet.

  4. Design Issues for Using Magnetic Materials in Radiation Environments at Elevated Temperature

    Science.gov (United States)

    Bowman, Cheryl L.

    2013-01-01

    One of the challenges of designing motors and alternators for use in nuclear powered space missions is accounting for the effects of radiation. Terrestrial reactor power plants use distance and shielding to minimize radiation damage but space missions must economize volume and mass. Past studies have shown that sufficiently high radiation levels can affect the magnetic response of hard and soft magnetic materials. Theoretical models explaining the radiation-induced degradation have been proposed but not verified. This paper reviews the literature and explains the cumulative effects of temperature, magnetic-load, and radiation-level on the magnetic properties of component materials. Magnetic property degradation is very specific to alloy choice and processing history, since magnetic properties are very much entwined with specific chemistry and microstructural features. However, there is basic theoretical as well as supportive experimental evidence that the negative impact to magnetic properties will be minimal if the bulk temperature of the material is less than fifty percent of the Curie temperature, the radiation flux is low, and the demagnetization field is small. Keywords: Magnets, Permanent Magnets, Power Converters, Nuclear Electric Power Generation, Radiation Tolerance.

  5. Influence of nonequilibrium radiation and shape change on aerothermal environment of a Jovian entry body

    Science.gov (United States)

    Tiwari, S. N.; Subramanian, S. V.

    1981-01-01

    The influence of nonequilibrium radiative energy transfer and the effect of probe configuration changes on the flow phenomena around a Jovian entry body are investigated. The radiating shock layer flow is assumed to be axisymmetric, viscous, laminar and in chemical equilibrium. The radiative transfer equations are derived under nonequilibrium conditions which include multilevel energy transitions. The equilibrium radiative transfer analysis is performed with an existing nongray radiation model which accounts for molecular band, atomic line, and continuum transitions. The nonequilibrium results are obtained with and without ablation injection in the shock layer. The nonequilibrium results are found to be greatly influenced by the temperature distribution in the shock layer. In the absence of ablative products, the convective and radiative heating to the entry body are reduced under nonequilibrium conditions. The influence of nonequilibrium is found to be greater at higher entry altitudes. With coupled ablation and carbon phenolic injection, 16 chemical species are used in the ablation layer for radiation absorption. Equilibrium and nonequilibrium results are compared under peak heating conditions.

  6. Modeling classical and quantum radiation from laser-plasma accelerators

    Directory of Open Access Journals (Sweden)

    M. Chen

    2013-03-01

    Full Text Available The development of models and the “Virtual Detector for Synchrotron Radiation” (vdsr code that accurately describe the production of synchrotron radiation are described. These models and code are valid in the classical and linear (single-scattering quantum regimes and are capable of describing radiation produced from laser-plasma accelerators (LPAs through a variety of mechanisms including betatron radiation, undulator radiation, and Thomson/Compton scattering. Previous models of classical synchrotron radiation, such as those typically used for undulator radiation, are inadequate in describing the radiation spectra from electrons undergoing small numbers of oscillations. This is due to an improper treatment of a mathematical evaluation at the end points of an integration that leads to an unphysical plateau in the radiation spectrum at high frequencies, the magnitude of which increases as the number of oscillation periods decreases. This is important for betatron radiation from LPAs, in which the betatron strength parameter is large but the number of betatron periods is small. The code vdsr allows the radiation to be calculated in this regime by full integration over each electron trajectory, including end-point effects, and this code is used to calculate betatron radiation for cases of experimental interest. Radiation from Thomson scattering and Compton scattering is also studied with vdsr. For Thomson scattering, radiation reaction is included by using the Sokolov method for the calculation of the electron dynamics. For Compton scattering, quantum recoil effects are considered in vdsr by using Monte Carlo methods. The quantum calculation has been benchmarked with the classical calculation in a classical regime.

  7. Methodologies in the modeling of combined chemo-radiation treatments

    Science.gov (United States)

    Grassberger, C.; Paganetti, H.

    2016-11-01

    The variety of treatment options for cancer patients has increased significantly in recent years. Not only do we combine radiation with surgery and chemotherapy, new therapeutic approaches such as immunotherapy and targeted therapies are starting to play a bigger role. Physics has made significant contributions to radiation therapy treatment planning and delivery. In particular, treatment plan optimization using inverse planning techniques has improved dose conformity considerably. Furthermore, medical physics is often the driving force behind tumor control and normal tissue complication modeling. While treatment optimization and outcome modeling does focus mainly on the effects of radiation, treatment modalities such as chemotherapy are treated independently or are even neglected entirely. This review summarizes the published efforts to model combined modality treatments combining radiation and chemotherapy. These models will play an increasing role in optimizing cancer therapy not only from a radiation and drug dosage standpoint, but also in terms of spatial and temporal optimization of treatment schedules.

  8. Environmental Radiation Effects on Mammals A Dynamical Modeling Approach

    CERN Document Server

    Smirnova, Olga A

    2010-01-01

    This text is devoted to the theoretical studies of radiation effects on mammals. It uses the framework of developed deterministic mathematical models to investigate the effects of both acute and chronic irradiation in a wide range of doses and dose rates on vital body systems including hematopoiesis, small intestine and humoral immunity, as well as on the development of autoimmune diseases. Thus, these models can contribute to the development of the system and quantitative approaches in radiation biology and ecology. This text is also of practical use. Its modeling studies of the dynamics of granulocytopoiesis and thrombocytopoiesis in humans testify to the efficiency of employment of the developed models in the investigation and prediction of radiation effects on these hematopoietic lines. These models, as well as the properly identified models of other vital body systems, could provide a better understanding of the radiation risks to health. The modeling predictions will enable the implementation of more ef...

  9. The external gamma radiation environment from the Kiwi Phoebus, and Pewee reactors

    Science.gov (United States)

    Malenfant, R. E.

    1972-01-01

    During the past few years, ground tests of high-powered propulsion-prototype reactors have provided several opportunities to observe the external radiation environment. Reactor tests have been conducted in free air and inside of open well shields. Measurements were taken over distances ranging from contact with the pressure vessel out to greater than 5000' both during operation and after shutdown. Some measurements characteristic of each of the systems are presented and compared with results of calculations.

  10. Treatment of cloud radiative effects in general circulation models

    Energy Technology Data Exchange (ETDEWEB)

    Wang, W.C.; Dudek, M.P.; Liang, X.Z.; Ding, M. [State Univ. of New York, Albany, NY (United States)] [and others

    1996-04-01

    We participate in the Atmospheric Radiation Measurement (ARM) program with two objectives: (1) to improve the general circulation model (GCM) cloud/radiation treatment with a focus on cloud verticle overlapping and layer cloud optical properties, and (2) to study the effects of cloud/radiation-climate interaction on GCM climate simulations. This report summarizes the project progress since the Fourth ARM Science Team meeting February 28-March 4, 1994, in Charleston, South Carolina.

  11. High Performance Processors for Space Environments: A Subproject of the NASA Exploration Missions Systems Directorate "Radiation Hardened Electronics for Space Environments" Technology Development Program

    Science.gov (United States)

    Johnson, M.; Label, K.; McCabe, J.; Powell, W.; Bolotin, G.; Kolawa, E.; Ng, T.; Hyde, D.

    2007-01-01

    Implementation of challenging Exploration Systems Missions Directorate objectives and strategies can be constrained by onboard computing capabilities and power efficiencies. The Radiation Hardened Electronics for Space Environments (RHESE) High Performance Processors for Space Environments project will address this challenge by significantly advancing the sustained throughput and processing efficiency of high-per$ormance radiation-hardened processors, targeting delivery of products by the end of FY12.

  12. Dust Environment Modelling of Comet 67P/Churyumov-Gerasimenko

    CERN Document Server

    Agarwal, Jessica; Gruen, Eberhard

    2010-01-01

    Dust is an important constituent in cometary comae; its analysis is one of the major objectives of ESA's Rosetta mission to comet 67P/Churyumov-Gerasimenko (C-G). Several instruments aboard Rosetta are dedicated to studying various aspects of dust in the cometary coma, all of which require a certain level of exposure to dust to achieve their goals. At the same time, impacts of dust particles can constitute a hazard to the spacecraft. To conciliate the demands of dust collection instruments and spacecraft safety, it is desirable to assess the dust environment in the coma even before the arrival of Rosetta. We describe the present status of modelling the dust coma of 67P/C-G and predict the speed and flux of dust in the coma, the dust fluence on a spacecraft along sample trajectories, and the radiation environment in the coma. The model will need to be refined when more details of the coma are revealed by observations. An overview of astronomical observations of 67P/C-G is given and model parameters are derived...

  13. Qualification of electronic components and systems in a LHC Tunnel Radiation Environment

    CERN Document Server

    Rausch, R; Wijnands, Thijs

    2002-01-01

    Around 10.200 electronic crates will be installed in the LHC underground areas of which some 4.200 will be connected to the machine control network. Some of the electronic equipment will be housed under the cryostats of the main dipoles inside the tunnel. Other equipment will be placed alongside the tunnel, in the alcoves or in galleries parallel to the machine. In the regular arcs and in the dispersion suppressors areas the expected annual dose is low, i.e. only a few Gy/y. However, preliminary radiation tests showed that electronic equipment fails even at such low dose rates. Since radiation qualification of all tunnel electronics is essential in order to guarantee its reliable operation over the lifetime of the machine, a LHC radiation test facility was commissioned in the North Experimental Area of the SPS accelerator. This paper presents the simulation study concerning the radiation environment of the LHC Radiation Test Facility and gives an overview of the various underground electronic systems as they ...

  14. 3D modeling of environments contaminated with chemical, biological, radiological and nuclear (CBRN) agents

    Science.gov (United States)

    Jasiobedzki, Piotr; Ng, Ho-Kong; Bondy, Michel; McDiarmid, Carl H.

    2008-04-01

    CBRN Crime Scene Modeler (C2SM) is a prototype 3D modeling system for first responders investigating environments contaminated with Chemical, Biological, Radiological and Nuclear agents. The prototype operates on board a small robotic platform or a hand-held device. The sensor suite includes stereo and high resolution cameras, a long wave infra red camera, chemical detector, and two gamma detectors (directional and non-directional). C2SM has been recently tested in field trials where it was teleoperated within an indoor environment with gamma radiation sources present. The system has successfully created multi-modal 3D models (geometry, colour, IR and gamma radiation), correctly identified location of radiation sources and provided high resolution images of these sources.

  15. A wildland fire modeling and visualization environment

    CERN Document Server

    Mandel, Jan; Kochanski, Adam K; Kondratenko, Volodymyr Y; Zhang, Lin; Anderson, Erik; Daniels, Joel; Silva, Claudio T; Johnson, Christopher R

    2011-01-01

    We present an overview of a modeling environment, consisting of a coupled atmosphere-wildfire model, utilities for visualization, data processing, and diagnostics, open source software repositories, and a community wiki. The fire model, called SFIRE, is based on a fire-spread model, implemented by the level-set method, and it is coupled with the Weather Research Forecasting (WRF) model. A version with a subset of the features is distributed with WRF 3.3 as WRF-Fire. In each time step, the fire module takes the wind as input and returns the latent and sensible heat fluxes. The software architecture uses WRF parallel infrastructure for massively parallel computing. Recent features of the code include interpolation from an ideal logarithmic wind profile for nonhomogeneous fuels and ignition from a fire perimeter with an atmosphere and fire spin-up. Real runs use online sources for fuel maps, fine-scale topography, and meteorological data, and can run faster than real time. Visualization pathways allow generating...

  16. Sunspot Modeling: From Simplified Models to Radiative MHD Simulations

    Directory of Open Access Journals (Sweden)

    Rolf Schlichenmaier

    2011-09-01

    Full Text Available We review our current understanding of sunspots from the scales of their fine structure to their large scale (global structure including the processes of their formation and decay. Recently, sunspot models have undergone a dramatic change. In the past, several aspects of sunspot structure have been addressed by static MHD models with parametrized energy transport. Models of sunspot fine structure have been relying heavily on strong assumptions about flow and field geometry (e.g., flux-tubes, "gaps", convective rolls, which were motivated in part by the observed filamentary structure of penumbrae or the necessity of explaining the substantial energy transport required to maintain the penumbral brightness. However, none of these models could self-consistently explain all aspects of penumbral structure (energy transport, filamentation, Evershed flow. In recent years, 3D radiative MHD simulations have been advanced dramatically to the point at which models of complete sunspots with sufficient resolution to capture sunspot fine structure are feasible. Here overturning convection is the central element responsible for energy transport, filamentation leading to fine-structure and the driving of strong outflows. On the larger scale these models are also in the progress of addressing the subsurface structure of sunspots as well as sunspot formation. With this shift in modeling capabilities and the recent advances in high resolution observations, the future research will be guided by comparing observation and theory.

  17. Implementing Badhwar-O'Neill Galactic Cosmic Ray Model for the Analysis of Space Radiation Exposure

    Science.gov (United States)

    Kim, Myung-Hee Y.; O'Neill, Patrick M.; Slaba, Tony C.

    2014-01-01

    For the analysis of radiation risks to astronauts and planning exploratory space missions, accurate energy spectrum of galactic cosmic radiation (GCR) is necessary. Characterization of the ionizing radiation environment is challenging because the interplanetary plasma and radiation fields are modulated by solar disturbances and the radiation doses received by astronauts in interplanetary space are likewise influenced. A model of the Badhwar-O'Neill 2011 (BO11) GCR environment, which is represented by GCR deceleration potential theta, has been derived by utilizing all of the GCR measurements from balloons, satellites, and the newer NASA Advanced Composition Explorer (ACE). In the BO11 model, the solar modulation level is derived from the mean international sunspot numbers with time-delay, which has been calibrated with actual flight instrument measurements to produce better GCR flux data fit during solar minima. GCR fluxes provided by the BO11 model were compared with various spacecraft measurements at 1 AU, and further comparisons were made for the tissue equivalent proportional counters measurements at low Earth orbits using the high-charge and energy transport (HZETRN) code and various GCR models. For the comparison of the absorbed dose and dose equivalent calculations with the measurements by Radiation Assessment Detector (RAD) at Gale crater on Mars, the intensities and energies of GCR entering the heliosphere were calculated by using the BO11 model, which accounts for time-dependent attenuation of the local interstellar spectrum of each element. The BO11 model, which has emphasized for the last 24 solar minima, showed in relatively good agreement with the RAD data for the first 200 sols, but it was resulted in to be less well during near the solar maximum of solar cycle 24 due to subtleties in the changing heliospheric conditions. By performing the error analysis of the BO11 model and the optimization in reducing overall uncertainty, the resultant BO13 model

  18. NASA Space Radiation Program Integrative Risk Model Toolkit

    Science.gov (United States)

    Kim, Myung-Hee Y.; Hu, Shaowen; Plante, Ianik; Ponomarev, Artem L.; Sandridge, Chris

    2015-01-01

    NASA Space Radiation Program Element scientists have been actively involved in development of an integrative risk models toolkit that includes models for acute radiation risk and organ dose projection (ARRBOD), NASA space radiation cancer risk projection (NSCR), hemocyte dose estimation (HemoDose), GCR event-based risk model code (GERMcode), and relativistic ion tracks (RITRACKS), NASA radiation track image (NASARTI), and the On-Line Tool for the Assessment of Radiation in Space (OLTARIS). This session will introduce the components of the risk toolkit with opportunity for hands on demonstrations. The brief descriptions of each tools are: ARRBOD for Organ dose projection and acute radiation risk calculation from exposure to solar particle event; NSCR for Projection of cancer risk from exposure to space radiation; HemoDose for retrospective dose estimation by using multi-type blood cell counts; GERMcode for basic physical and biophysical properties for an ion beam, and biophysical and radiobiological properties for a beam transport to the target in the NASA Space Radiation Laboratory beam line; RITRACKS for simulation of heavy ion and delta-ray track structure, radiation chemistry, DNA structure and DNA damage at the molecular scale; NASARTI for modeling of the effects of space radiation on human cells and tissue by incorporating a physical model of tracks, cell nucleus, and DNA damage foci with image segmentation for the automated count; and OLTARIS, an integrated tool set utilizing HZETRN (High Charge and Energy Transport) intended to help scientists and engineers study the effects of space radiation on shielding materials, electronics, and biological systems.

  19. Modeling Clinical Radiation Responses in the IMRT Era

    Science.gov (United States)

    Schwartz, J. L.; Murray, D.; Stewart, R. D.; Phillips, M. H.

    2014-03-01

    The purpose of this review is to highlight the critical issues of radiobiological models, particularly as they apply to clinical radiation therapy. Developing models of radiation responses has a long history that continues to the present time. Many different models have been proposed, but in the field of radiation oncology, the linear-quadratic (LQ) model has had the most impact on the design of treatment protocols. Questions have been raised as to the value of the LQ model given that the biological assumption underlying it has been challenged by molecular analyses of cell and tissue responses to radiation. There are also questions as to use of the LQ model for hypofractionation, especially for high dose treatments using a single fraction. While the LQ model might over-estimate the effects of large radiation dose fractions, there is insufficient information to fully justify the adoption of alternative models. However, there is increasing evidence in the literature that non-targeted and other indirect effects of radiation sometimes produce substantial deviations from LQ-like dose-response curves. As preclinical and clinical hypofractionation studies accumulate, new or refined dose-response models that incorporate high-dose/fraction non-targeted and indirect effects may be required, but for now the LQ model remains a simple, useful tool to guide the design of treatment protocols.

  20. Virtual Research Environments for Natural Hazard Modelling

    Science.gov (United States)

    Napier, Hazel; Aldridge, Tim

    2017-04-01

    The Natural Hazards Partnership (NHP) is a group of 17 collaborating public sector organisations providing a mechanism for co-ordinated advice to government and agencies responsible for civil contingency and emergency response during natural hazard events. The NHP has set up a Hazard Impact Model (HIM) group tasked with modelling the impact of a range of UK hazards with the aim of delivery of consistent hazard and impact information. The HIM group consists of 7 partners initially concentrating on modelling the socio-economic impact of 3 key hazards - surface water flooding, land instability and high winds. HIM group partners share scientific expertise and data within their specific areas of interest including hydrological modelling, meteorology, engineering geology, GIS, data delivery, and modelling of socio-economic impacts. Activity within the NHP relies on effective collaboration between partners distributed across the UK. The NHP are acting as a use case study for a new Virtual Research Environment (VRE) being developed by the EVER-EST project (European Virtual Environment for Research - Earth Science Themes: a solution). The VRE is allowing the NHP to explore novel ways of cooperation including improved capabilities for e-collaboration, e-research, automation of processes and e-learning. Collaboration tools are complemented by the adoption of Research Objects, semantically rich aggregations of resources enabling the creation of uniquely identified digital artefacts resulting in reusable science and research. Application of the Research Object concept to HIM development facilitates collaboration, by encapsulating scientific knowledge in a shareable format that can be easily shared and used by partners working on the same model but within their areas of expertise. This paper describes the application of the VRE to the NHP use case study. It outlines the challenges associated with distributed partnership working and how they are being addressed in the VRE. A case

  1. Modeling Virtual Meetings within Software Engineering Environment

    Directory of Open Access Journals (Sweden)

    Dr. Aiman Turani

    2014-04-01

    Full Text Available It is a common scenario to see project’s stakeholders, such as managers, team leaders, and developers carrying out their meeting in the online environment without a suitable preparation and facilitation For instance, stakeholders engaging in negotiation sessions trying to communicate system requirements in the virtual environment might face requirements misunderstanding which in turn might cause a whole project to fail. Usually a meeting agenda and design is implicit in the facilitator’s head. Conducting such meetings without obvious structure would potentially lead to various problems such as no one seemed to be in charge? Or there was no clear reason to meet or no agenda etc. In this paper, we are presenting a general framework to model group-based activities and meetings within software engineering field in a simplified and formal manner. Traditionally, managers submit their web-based group meeting information in a form of text-based instructions [1]. Then a group facilitator or chairperson will lead the group throughout the meeting to achieve the desired objectives. These types of meeting are relatively easy to manage in face-to-face environment where web based meeting in the other hand, is more challenging to facilitate and manage. Therefore, more and more specialized tools are immerging to manage and facilitate such meetings. For instance, Adobe Connect [2] is tool for facilitating web-based meetings. These tools usually allow facilitators to organize and prepare the meeting floor by inserting specific collaboration components such as chat, whiteboard, voting, etc. Then during the meeting the facilitator guides participants using the video or text component. This usually leads to undesirable outputs due to the lack of a clear structure or agenda in addition to the virtual distance that weakens the communication. In this paper a two level of modeling views are proposed, the static view and the dynamic view. The static view mainly

  2. Dark radiation from a unified dark fluid model

    CERN Document Server

    Geng, Chao-Qiang; Zhang, Xin

    2014-01-01

    We present a unified dark fluid model to describe the possible evolutionary behavior of $\\Delta N_\\mathrm{eff}$ in dark radiation. This model can be viewed as an interacting model for the dark sectors, in which dark matter interacts with dark radiation. We show that the evolution of $\\Delta N_\\mathrm{eff}$ can be nicely explained without some drawbacks, such as the blowup of $\\Delta N_\\mathrm{eff}$ at the late time and the interaction term at the early time.

  3. Modeling and analysis of ground target radiation cross section

    Institute of Scientific and Technical Information of China (English)

    SHI Xiang; LOU GuoWei; LI XingGuo

    2008-01-01

    Based on the analysis of the passive millimeter wave (MMW) radiometer detection, the ground target radiation cross section is modeled as the new token for the target MMW radiant characteristics. Its ap-plication and actual testing are discussed and analyzed. The essence of passive MMW stealth is target radiation cross section reduction.

  4. 3D Gray Radiative Properties of a Radiation Hydrodynamic Model of a YSO Accretion Shock

    Science.gov (United States)

    Ibgui, L.; de Sá, L.; Stehlé, C.; Chièze, J.-P.; Orlando, S.; Hubeny, I.; Lanz, T.; Matsakos, T.; González, M.; Bonito, R.

    2014-09-01

    We present preliminary results of radiative properties of a 1D gray radiation hydrodynamic (RHD) model of an accretion shock on a young stellar object (YSO). This model takes into account the transition between the collisional equilibrium regime (local thermodynamic equilibrium, LTE), and the coronal equilibrium regime. Based on the 1D planar structure, we built a 3D cylindrical one. Most notably, the post-shock region obtained in our case is far less extended (by a factor of 10 000) than the typical one obtained with models that assume gray optically thin radiative losses. Moreover, we find that the column is optically thin in its longitudinal dimension, and in the transverse dimension, except over an extremely narrow region (≲ 700 m). Consequently, still under the gray assumption, the photons emitted by the hot slab can propagate through the column and escape freely in all directions, including towards the chromosphere. The radiation flux has therefore components that are perpendicular to the accretion column, which demonstrates that a multidimensional (2D or 3D) radiative model is necessary for such a cylindrical structure. This study needs to be taken forward and expanded, by improving the radiative treatment of the RHD model, through relaxation of both the gray and the LTE approximations for the calculation of opacities, in order to clarify the structure of the post-shock region, which is a major source of emission probed by observations.

  5. Amazon Molly, Poecilia formosa, as a model for studies of the effects of ionizing radiation. [Radiosensitivity of Poecilia formosa, Carassius auratus, Ictalurus punctatus, and Oncorhynchus tshawytscha in laboratory environments

    Energy Technology Data Exchange (ETDEWEB)

    Woodhead, A.D.; Setlow, R.B.; Hart, R.W.

    1977-01-01

    It is suggested that the viviparous teleost, Poecilia formosa, (Amazon molly) may have wide potential use for aquatic radiation studies. The Amazon molly is a naturally occurring gynogenetic species, in which the eggs are activated after mating with the males of closely related species, without the subsequent genetic contribution from the male. The offspring of a single original female constitute a clone, having identical genotypes. Clones of the genetically homogeneous Amazon molly may prove to be equally as valuable to aquatic radiobiologists as the inbred rodent lines have been to mammalian studies. In many other respects the Amazon molly is a satisfactory laboratory animal. It is robust, easy to rear, and has large broods of young when fully grown. Maintenance costs are low. Details are given of the conditions under which colonies reproduce.

  6. Degradation of thermal control materials under a simulated radiative space environment

    Science.gov (United States)

    Sharma, A. K.; Sridhara, N.

    2012-11-01

    A spacecraft with a passive thermal control system utilizes various thermal control materials to maintain temperatures within safe operating limits. Materials used for spacecraft applications are exposed to harsh space environments such as ultraviolet (UV) and particle (electron, proton) irradiation and atomic oxygen (AO), undergo physical damage and thermal degradation, which must be considered for spacecraft thermal design optimization and cost effectiveness. This paper describes the effect of synergistic radiation on some of the important thermal control materials to verify the assumptions of beginning-of-life (BOL) and end-of-life (EOL) properties. Studies on the degradation in the optical properties (solar absorptance and infrared emittance) of some important thermal control materials exposed to simulated radiative geostationary space environment are discussed. The current studies are purely related to the influence of radiation on the degradation of the materials; other environmental aspects (e.g., thermal cycling) are not discussed. The thermal control materials investigated herein include different kind of second-surface mirrors, white anodizing, white paints, black paints, multilayer insulation materials, varnish coated aluminized polyimide, germanium coated polyimide, polyether ether ketone (PEEK) and poly tetra fluoro ethylene (PTFE). For this purpose, a test in the constant vacuum was performed reproducing a three year radiative space environment exposure, including ultraviolet and charged particle effects on North/South panels of a geostationary three-axis stabilized spacecraft. Reflectance spectra were measured in situ in the solar range (250-2500 nm) and the corresponding solar absorptance values were calculated. The test methodology and the degradations of the materials are discussed. The most important degradations among the low solar absorptance materials were found in the white paints whereas the rigid optical solar reflectors remained quite

  7. An Analytic Radiative-Convective Model for Planetary Atmospheres

    CERN Document Server

    Robinson, Tyler D; 10.1088/0004-637X/757/1/104

    2012-01-01

    We present an analytic 1-D radiative-convective model of the thermal structure of planetary atmospheres. Our model assumes that thermal radiative transfer is gray and can be represented by the two-stream approximation. Model atmospheres are assumed to be in hydrostatic equilibrium, with a power law scaling between the atmospheric pressure and the gray thermal optical depth. The convective portions of our models are taken to follow adiabats that account for condensation of volatiles through a scaling parameter to the dry adiabat. By combining these assumptions, we produce simple, analytic expressions that allow calculations of the atmospheric pressure-temperature profile, as well as expressions for the profiles of thermal radiative flux and convective flux. We explore the general behaviors of our model. These investigations encompass (1) worlds where atmospheric attenuation of sunlight is weak, which we show tend to have relatively high radiative-convective boundaries, (2) worlds with some attenuation of sunli...

  8. Radiation Transfer Model for Aerosol Events in the Earth Atmosphere

    Science.gov (United States)

    Mukai, Sonoyo; Yokomae, Takuma; Nakata, Makiko; Sano, Itaru

    Recently large scale-forest fire, which damages the Earth environment as biomass burning and emission of carbonaceous particles, frequently occurs due to the unstable climate and/or global warming tendency. It is also known that the heavy soil dust is transported from the China continent to Japan on westerly winds, especially in spring. Furthermore the increasing emis-sions of anthropogenic particles associated with continuing economic growth scatter serious air pollutants. Thus atmospheric aerosols, especially in Asia, are very complex and heavy loading, which is called aerosol event. In the case of aerosol events, it is rather difficult to do the sun/sky photometry from the ground, however satellite observation is an effective for aerosol monitoring. Here the detection algorithms from space for such aerosol events as dust storm or biomass burn-ing are dealt with multispectral satellite data as ADEOS-2/GLI, Terra/Aqua/MODIS and/or GOSAT/CAI first. And then aerosol retrieval algorithms are examined based on new radiation transfer code for semi-infinite atmosphere model. The derived space-based results are validated with ground-based measurements and/or model simulations. Namely the space-or surface-based measurements, multiple scattering calculations and model simulations are synthesized together for aerosol retrieval in this work.

  9. Radiation Environment at LEO in the frame of Space Monitoring Data Center at Moscow State University - recent, current and future missions

    Science.gov (United States)

    Myagkova, Irina; Kalegaev, Vladimir; Panasyuk, Mikhail; Svertilov, Sergey; Bogomolov, Vitaly; Bogomolov, Andrey; Barinova, Vera; Barinov, Oleg; Bobrovnikov, Sergey; Dolenko, Sergey; Mukhametdinova, Ludmila; Shiroky, Vladimir; Shugay, Julia

    2016-04-01

    Radiation Environment of Near-Earth space is one of the most important factors of space weather. Space Monitoring Data Center of Moscow State University provides operational control of radiation conditions at Low Earth's Orbits (LEO) of the near-Earth space using data of recent (Vernov, CORONAS series), current (Meteor-M, Electro-L series) and future (Lomonosov) space missions. Internet portal of Space Monitoring Data Center of Skobeltsyn Institute of Nuclear Physics of Lomonosov Moscow State University (SINP MSU) http://swx.sinp.msu.ru/ provides possibilities to control and analyze the space radiation conditions in the real time mode together with the geomagnetic and solar activity including hard X-ray and gamma- emission of solar flares. Operational data obtained from space missions at L1, GEO and LEO and from the Earth's magnetic stations are used to represent radiation and geomagnetic state of near-Earth environment. The models of space environment that use space measurements from different orbits were created. Interactive analysis and operational neural network forecast services are based on these models. These systems can automatically generate alerts on particle fluxes enhancements above the threshold values, both for SEP and relativistic electrons of outer Earth's radiation belt using data from GEO and LEO as input. As an example of LEO data we consider data from Vernov mission, which was launched into solar-synchronous orbit (altitude 640 - 83 0 km, inclination 98.4°, orbital period about 100 min) on July 8, 2014 and began to receive scientific information since July 20, 2014. Vernov mission have provided studies of the Earth's radiation belt relativistic electron precipitation and its possible connection with atmosphere transient luminous events, as well as the solar hard X-ray and gamma-emission measurements. Radiation and electromagnetic environment monitoring in the near-Earth Space, which is very important for space weather study, was also realised

  10. Nuisance Source Population Modeling for Radiation Detection System Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Sokkappa, P; Lange, D; Nelson, K; Wheeler, R

    2009-10-05

    A major challenge facing the prospective deployment of radiation detection systems for homeland security applications is the discrimination of radiological or nuclear 'threat sources' from radioactive, but benign, 'nuisance sources'. Common examples of such nuisance sources include naturally occurring radioactive material (NORM), medical patients who have received radioactive drugs for either diagnostics or treatment, and industrial sources. A sensitive detector that cannot distinguish between 'threat' and 'benign' classes will generate false positives which, if sufficiently frequent, will preclude it from being operationally deployed. In this report, we describe a first-principles physics-based modeling approach that is used to approximate the physical properties and corresponding gamma ray spectral signatures of real nuisance sources. Specific models are proposed for the three nuisance source classes - NORM, medical and industrial. The models can be validated against measured data - that is, energy spectra generated with the model can be compared to actual nuisance source data. We show by example how this is done for NORM and medical sources, using data sets obtained from spectroscopic detector deployments for cargo container screening and urban area traffic screening, respectively. In addition to capturing the range of radioactive signatures of individual nuisance sources, a nuisance source population model must generate sources with a frequency of occurrence consistent with that found in actual movement of goods and people. Measured radiation detection data can indicate these frequencies, but, at present, such data are available only for a very limited set of locations and time periods. In this report, we make more general estimates of frequencies for NORM and medical sources using a range of data sources such as shipping manifests and medical treatment statistics. We also identify potential data sources for industrial

  11. Use of COTS [commercial-off-the-shelf] Microelectronics in Radiation Environments

    Energy Technology Data Exchange (ETDEWEB)

    Winokur, P.S.; Lum, G.K.; Shaneyfelt, M.R.; Sexton, F.W.; Hash, G.L.; Scott, L.

    1999-07-07

    This paper addresses key issues for the cost-effective use of COTS microelectronics in radiation environments that enable circuit or system designers to manage risks and ensure mission success. COTS parts with low radiation tolerance should not be used when they degrade mission critical functions or lead to premature system failure. We review several factors and tradeoffs affecting the successful application of COTS parts including (1) hardness assurance and qualification issues, (2) system hardening techniques, and (3) life-cycle costs. The paper also describes several experimental studies that address trends in total-dose, transient, and single-event radiation hardness as COTS technology scales to smaller feature sizes. As an example, the level at which dose-rate upset occurs in Samsung SRAMS increases from 1.4x10{sup 8} rads(Si)/s for a 256K SRAM to 7.7x10{sup 9} rads(Si)/s for a 4M SRAM, indicating unintentional hardening improvements in the design or process of a commercial technology. Additional experiments were performed to quantify variations in radiation hardness for COTS parts. In one study, only small (10-15%) variations were found in the dose-rate upset and latchup thresholds for Samsung 4M SRAMS from three different date codes. In another study, irradiations of 4M SRAMS from Samsung, Hitachi, and Toshiba indicate large differences in total-dose radiation hardness. The paper attempts to carefully define terms and clear up misunderstandings about the definitions of ''COTS'' and ''radiation-hardened'' technology.

  12. Fiber Bragg gratings in the radiation environment: Change under the influence of radiolytic hydrogen

    Science.gov (United States)

    Butov, Oleg V.; Golant, Konstantin M.; Shevtsov, Igor'A.; Fedorov, Artem N.

    2015-08-01

    The change of the transmission spectra of fiber Bragg gratings written in the optical fibers, whose silica cores are doped with either germanium or nitrogen, is studied experimentally under the influence of gamma-radiation. The transmission spectra in the neighborhood of the resonance (Bragg) wavelengths were regularly recorded "in-situ" in the course of irradiation during 24 days. For this purpose, uncoated gratings were placed in a pool near the spent fuel rods of a nuclear reactor. The fibers with the gratings written in them were in immediate contact with water. The estimated total absorbed radiation dose of the fibers is approximately 5 MGy. Molecular hydrogen, which is produced by radiolysis of water and penetrates into the core of silica fiber, is found to interact with the defects of Ge-doped silica induced by gamma-radiation, thereby causing a strong impact on the parameters of the spectrum of the Bragg gratings. On the contrary, in the case of gratings inscribed in N-doped silica fibers, the hydrogen molecules interact with defects induced in the course of laser UV exposure during the grating writing only. The possible subsequent formation of additional defects in N-doped silica under the influence of gamma-radiation has no substantial impact on the transmission spectra of Bragg gratings, which remained stable. The obtained results suggest that a small amount of molecular hydrogen resided in the fiber core is the main source of radiation instability of Ge-doped fiber Bragg grating sensors in radiation environments. These hydrogen molecules can remain in the Bragg gratings, in particular, after the inscription process in the hydrogen-loaded fibers.

  13. Fiber Bragg gratings in the radiation environment: Change under the influence of radiolytic hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Butov, Oleg V., E-mail: obutov@mail.ru; Golant, Konstantin M. [Kotel' nikov Institute of Radio-Engineering and Electronics of RAS, 11-7 Mokhovaya Str., Moscow 125009 (Russian Federation); Shevtsov, Igor' A.; Fedorov, Artem N. [Prolog LLC, PO Box 3007, Obninsk, the Kaluga Region 249033 (Russian Federation)

    2015-08-21

    The change of the transmission spectra of fiber Bragg gratings written in the optical fibers, whose silica cores are doped with either germanium or nitrogen, is studied experimentally under the influence of gamma-radiation. The transmission spectra in the neighborhood of the resonance (Bragg) wavelengths were regularly recorded “in-situ” in the course of irradiation during 24 days. For this purpose, uncoated gratings were placed in a pool near the spent fuel rods of a nuclear reactor. The fibers with the gratings written in them were in immediate contact with water. The estimated total absorbed radiation dose of the fibers is approximately 5 MGy. Molecular hydrogen, which is produced by radiolysis of water and penetrates into the core of silica fiber, is found to interact with the defects of Ge-doped silica induced by gamma-radiation, thereby causing a strong impact on the parameters of the spectrum of the Bragg gratings. On the contrary, in the case of gratings inscribed in N-doped silica fibers, the hydrogen molecules interact with defects induced in the course of laser UV exposure during the grating writing only. The possible subsequent formation of additional defects in N-doped silica under the influence of gamma-radiation has no substantial impact on the transmission spectra of Bragg gratings, which remained stable. The obtained results suggest that a small amount of molecular hydrogen resided in the fiber core is the main source of radiation instability of Ge-doped fiber Bragg grating sensors in radiation environments. These hydrogen molecules can remain in the Bragg gratings, in particular, after the inscription process in the hydrogen-loaded fibers.

  14. Cloud-Aerosol-Radiation (CAR ensemble modeling system

    Directory of Open Access Journals (Sweden)

    X.-Z. Liang

    2013-04-01

    Full Text Available A Cloud-Aerosol-Radiation (CAR ensemble modeling system has been developed to incorporate the largest choices of alternative parameterizations for cloud properties (cover, water, radius, optics, geometry, aerosol properties (type, profile, optics, radiation transfers (solar, infrared, and their interactions. These schemes form the most comprehensive collection currently available in the literature, including those used by the world leading general circulation models (GCMs. The CAR provides a unique framework to determine (via intercomparison across all schemes, reduce (via optimized ensemble simulations, and attribute specific key factors for (via physical process sensitivity analyses the model discrepancies and uncertainties in representing greenhouse gas, aerosol and cloud radiative forcing effects. This study presents a general description of the CAR system and illustrates its capabilities for climate modeling applications, especially in the context of estimating climate sensitivity and uncertainty range caused by cloud-aerosol-radiation interactions. For demonstration purpose, the evaluation is based on several CAR standalone and coupled climate model experiments, each comparing a limited subset of the full system ensemble with up to 896 members. It is shown that the quantification of radiative forcings and climate impacts strongly depends on the choices of the cloud, aerosol and radiation schemes. The prevailing schemes used in current GCMs are likely insufficient in variety and physically biased in a significant way. There exists large room for improvement by optimally combining radiation transfer with cloud property schemes.

  15. Preliminary results of a three-dimensional radiative transfer model

    Energy Technology Data Exchange (ETDEWEB)

    O`Hirok, W. [Univ. of California, Santa Barbara, CA (United States)

    1995-09-01

    Clouds act as the primary modulator of the Earth`s radiation at the top of the atmosphere, within the atmospheric column, and at the Earth`s surface. They interact with both shortwave and longwave radiation, but it is primarily in the case of shortwave where most of the uncertainty lies because of the difficulties in treating scattered solar radiation. To understand cloud-radiative interactions, radiative transfer models portray clouds as plane-parallel homogeneous entities to ease the computational physics. Unfortunately, clouds are far from being homogeneous, and large differences between measurement and theory point to a stronger need to understand and model cloud macrophysical properties. In an attempt to better comprehend the role of cloud morphology on the 3-dimensional radiation field, a Monte Carlo model has been developed. This model can simulate broadband shortwave radiation fluxes while incorporating all of the major atmospheric constituents. The model is used to investigate the cloud absorption anomaly where cloud absorption measurements exceed theoretical estimates and to examine the efficacy of ERBE measurements and cloud field experiments. 3 figs.

  16. MODELING OF MICROMANIPULATION ROBOT IN VIRTUAL ENVIRONMENT

    Institute of Scientific and Technical Information of China (English)

    F.S.Tan; L.N.Sun; W.B.Rong; J.Zhu

    2004-01-01

    Micromanipulation has been recognized to be very difficult due to the inefficiency of traditional micromanipulation methods.The paper present a general framework for micromanipulation robot based on virtual reality technology.The significance of introducing virtual reality into micromanipulation is analyzed,and the current research in this field is reviewed.Based on this,we propose a micromanipulation system that integrates virtual environment with vision feedback and force feedback.The system realizes vision close-loop control and force close-loop control to enhance the performance of micromanipulation device.A graphics modelling method is proposed for a microassembly task.Hardware and software implementation is described and discussion about the research is presented.

  17. The Martian and extraterrestrial UV radiation environment. Part II: further considerations on materials and design criteria for artificial ecosystems.

    Science.gov (United States)

    Cockell, C S

    2001-12-01

    Ultraviolet radiation is an important natural physical influence on organism function and ecosystem interactions. The UV radiation fluxes in extraterrestrial environments are substantially different from those experienced on Earth. On Mars, the moon and in Earth orbit they are more biologically detrimental than on Earth. Based on previously presented fluxes and biologically weighted irradiances, this paper considers in more detail measures to mitigate UV radiation damage and methods to modify extraterrestrial UV radiation environments in artificial ecosystems that use natural sunlight. The transmission characteristics of a Martian material that will mimic the terrestrial UV radiation environment are presented. Transmissivity characteristics of other Martian and lunar materials are described. Manufacturing processes for the production of plastics and glass on the lunar and Martian surface are presented with special emphasis on photobiological requirements. Novel UV absorbing configurations are suggested.

  18. High temperature radiator materials for applications in the low Earth orbital environment

    Science.gov (United States)

    Rutledge, Sharon K.; Banks, Bruce A.; Mirtich, Michael J.; Lebed, Richard; Brady, Joyce; Hotes, Deborah; Kussmaul, Michael

    1987-01-01

    Radiators must be constructed of materials which have high emittance in order to efficiently radiate heat from high temperature space power systems. In addition, if these radiators are to be used for applications in the low Earth orbital environment, they must not be detrimentally affected by exposure to atomic oxygen. Four materials selected as candidate radiator materials (304 stainless steel, copper, titanium-6% aluminum-4% vanadium (Ti-6%Al-4%V), and niobium-1% zirconium (Nb-1%Zr)) were surface modified by acid etching, heat treating, abrading, sputter texturing, electrochemical etching, and combinations of the above in order to improve their emittance. Combination treatment techniques with heat treating as the second treatment provided about a factor of two improvement in emittance for 304 stainless steel, Ti-6%Al-4%V, and Nb-1%Zr. A factor of three improvement in emittance occurred for discharge chamber sputter textured copper. Exposure to atomic oxygen in an RF plasma asher did not significantly change the emittance of those samples that had been heat treated as part of their texturing process. An evaluation of oxygen penetration is needed to understand how oxidation affects the mechanical properties of these materials when heat treated.

  19. Real-time fibre optic radiation dosimeters for nuclear environment monitoring around thermonuclear reactors

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, A. Fernandez; Brichard, B. [SCK .CEN, Belgian Nuclear Research Centre, Boeretang 200, B-2400 Mol (Belgium); O' Keeffe, S.; Fitzpatrick, C.; Lewis, E. [Electronic and Computer Engineering Department, University of Limerick, Limerick (Ireland); Vaille, J.-R.; Dusseau, L. [CEM2-Universite Montpellier II, cc083 place E. Bataillon, 34095 Montpellier Cedex 05 (France); Jackson, D.A. [School of Physical Sciences, University of Kent, Kent CT2 7NR (United Kingdom); Ravotti, F.; Glaser, M. [European Organization for Nuclear Research CERN, TS-LEA-RAD/PH-DT2-SD, CH-1211 Geneva 23 (Switzerland); El-Rabii, H. [Laboratoire de Combustion et de Detonique, ENSMA/CNRS, 1 av. Clement Ader, 86961 Chasseneuil-Futuroscope (France)], E-mail: afernand@sckcen.be

    2008-01-15

    The ability of fibre optic sensors to operate in hazardous nuclear environments and their intrinsic immunity to electro-magnetic interference make fibre optic sensing a very promising technology for the future ITER thermonuclear fusion reactor. In this paper, we evaluate fibre optic sensing technology for monitoring radiation dose in the vicinity of ITER during its operation and during the maintenance periods. First, the performance of an OSL dosimeter interrogated remotely using radiation tolerant optical fibres is evaluated both for real-time and integrating measurements for doses exceeding 100 Gy. We demonstrate its satisfactory operation in a mixed gamma neutron field. Second, we discuss the successful calibration of a new scintillating fibre optic radiation probe based on CsI(TI) crystals for operation in the dose-rate range 0.3-3000 mGy/h. The CsI(TI) crystal scintillator is mounted at the end of a 10-m long multimode fibre transceiver link to allow for remote deployment. The probes can detect and measure gamma dose rates ranging from 1 to 1000 mGy/h. Finally, we investigate the possible use of commercially available PMMA plastic optical fibres as on-line dosimeters up to 34 kGy. The dose measurement is derived from the radiation-induced attenuation in the optical fibre itself. A novel interrogation scheme based on a ratiometric technique is proposed for real-time dosimetry.

  20. Fast and simple model for atmospheric radiative transfer

    NARCIS (Netherlands)

    Seidel, F.C.; Kokhanovsky, A.A.; Schaepman, M.E.

    2010-01-01

    Radiative transfer models (RTMs) are of utmost importance for quantitative remote sensing, especially for compensating atmospheric perturbation. A persistent trade-off exists between approaches that prefer accuracy at the cost of computational complexity, versus those favouring simplicity at the

  1. Radiative Transfer Model for Translucent Slab Ice on Mars

    Science.gov (United States)

    Andrieu, F.; Schmidt, F.; Douté, S.; Schmitt, B.; Brissaud, O.

    2016-09-01

    We developed a radiative transfer model that simulates in VIS/NIR the bidirectional reflectance of a contaminated slab layer of ice overlaying a granular medium, under geometrical optics conditions to study martian ices.

  2. Discrete Event Simulation Modeling of Radiation Medicine Delivery Methods

    Energy Technology Data Exchange (ETDEWEB)

    Paul M. Lewis; Dennis I. Serig; Rick Archer

    1998-12-31

    The primary objective of this work was to evaluate the feasibility of using discrete event simulation (DES) modeling to estimate the effects on system performance of changes in the human, hardware, and software elements of radiation medicine delivery methods.

  3. Parameterization of clouds and radiation in climate models

    Energy Technology Data Exchange (ETDEWEB)

    Roeckner, E. [Max Planck Institute for Meterology, Hamburg (Germany)

    1995-09-01

    Clouds are a very important, yet poorly modeled element in the climate system. There are many potential cloud feedbacks, including those related to cloud cover, height, water content, phase change, and droplet concentration and size distribution. As a prerequisite to studying the cloud feedback issue, this research reports on the simulation and validation of cloud radiative forcing under present climate conditions using the ECHAM general circulation model and ERBE top-of-atmosphere radiative fluxes.

  4. Validation of elastic cross section models for space radiation applications

    Science.gov (United States)

    Werneth, C. M.; Xu, X.; Norman, R. B.; Ford, W. P.; Maung, K. M.

    2017-02-01

    The space radiation field is composed of energetic particles that pose both acute and long-term risks for astronauts in low earth orbit and beyond. In order to estimate radiation risk to crew members, the fluence of particles and biological response to the radiation must be known at tissue sites. Given that the spectral fluence at the boundary of the shielding material is characterized, radiation transport algorithms may be used to find the fluence of particles inside the shield and body, and the radio-biological response is estimated from experiments and models. The fidelity of the radiation spectrum inside the shield and body depends on radiation transport algorithms and the accuracy of the nuclear cross sections. In a recent study, self-consistent nuclear models based on multiple scattering theory that include the option to study relativistic kinematics were developed for the prediction of nuclear cross sections for space radiation applications. The aim of the current work is to use uncertainty quantification to ascertain the validity of the models as compared to a nuclear reaction database and to identify components of the models that can be improved in future efforts.

  5. Modelling low energy electron interactions for biomedical uses of radiation

    Energy Technology Data Exchange (ETDEWEB)

    Fuss, M; Garcia, G [Instituto de Fisica Fundamental, Consejo Superior de Investigaciones CientIficas (CSIC), Serrano 113-bis, 28006 Madrid (Spain); Munoz, A; Oller, J C [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Avenida Complutense 22, 28040 Madrid (Spain); Blanco, F [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid, Avenida Complutense s.n., 28040 Madrid (Spain); Limao-Vieira, P [Departamento de Fisica, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Huerga, C; Tellez, M [Hospital Universitario La Paz, paseo de la Castellana 261, 28046 Madrid (Spain); Hubin-Fraskin, M J [Department of Chemistry, University of Liege, 4000 Liege 1 (Belgium); Nixon, K; Brunger, M, E-mail: g.garcia@imaff.cfmac.csic.e [School of Chemistry, Physics and Earth Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia)

    2009-11-15

    Current radiation based medical applications in the field of radiotherapy, radio-diagnostic and radiation protection require modelling single particle interactions at the molecular level. Due to their relevance in radiation damage to biological systems, special attention should be paid to include the effect of low energy secondary electrons. In this study we present a single track simulation procedure for photons and electrons which is based on reliable experimental and theoretical cross section data and the energy loss distribution functions derived from our experiments. The effect of including secondary electron interactions in this model will be discussed.

  6. Meteoroid Environment Modeling: the Meteoroid Engineering Model and Shower Forecasting

    Science.gov (United States)

    Moorhead, Althea V.

    2017-01-01

    The meteoroid environment is often divided conceptually into meteor showers plus a sporadic background component. The sporadic complex poses the bulk of the risk to spacecraft, but showers can produce significant short-term enhancements of the meteoroid flux. The Meteoroid Environment Office (MEO) has produced two environment models to handle these cases: the Meteoroid Engineering Model (MEM) and an annual meteor shower forecast. Both MEM and the forecast are used by multiple manned spaceflight projects in their meteoroid risk evaluation, and both tools are being revised to incorporate recent meteor velocity, density, and timing measurements. MEM describes the sporadic meteoroid complex and calculates the flux, speed, and directionality of the meteoroid environment relative to a user-supplied spacecraft trajectory, taking the spacecraft's motion into account. MEM is valid in the inner solar system and offers near-Earth and cis-lunar environments. While the current version of MEM offers a nominal meteoroid environment corresponding to a single meteoroid bulk density, the next version of MEMR3 will offer both flux uncertainties and a density distribution in addition to a revised near-Earth environment. We have updated the near-Earth meteor speed distribution and have made the first determination of uncertainty in this distribution. We have also derived a meteor density distribution from the work of Kikwaya et al. (2011). The annual meteor shower forecast takes the form of a report and data tables that can be used in conjunction with an existing MEM assessment. Fluxes are typically quoted to a constant limiting kinetic energy in order to comport with commonly used ballistic limit equations. For the 2017 annual forecast, the MEO substantially revised the list of showers and their characteristics using 14 years of meteor flux measurements from the Canadian Meteor Orbit Radar (CMOR). Defunct or insignificant showers were removed and the temporal profiles of many showers

  7. Crustaceous lichens sensitive monitor of caesium-137 radiation level in terrestrial environment

    Institute of Scientific and Technical Information of China (English)

    Du Chunguang; Zhao Ye; Zhang Jing; Xu Cuihua

    2005-01-01

    The activity of caesium-137 (Bq/kg) in the crustaceous lichens and other samples was determined to prove the feasibility that crustaceous lichens work as a sensitive biology monitor to record the caesium-137 (Bq/kg) radiation levels of terrestrial environment. The measurements were performed with GEM series HPGe (high-purity Germanium) coaxial detector system (ADCAM -100) made by EC & GORTEC Company in USA. It was found that the activity of caesium-137 (Bq/kg) in the crustaceous lichens was one order of magnitude higher than that found in surface soil,and was over three orders of magnitude higher than those found in the familiar biological samples. These results proved that crustaceous lichens may be one of the most sensitive biological monitors about the remote transmission and environmental radiation levels of caesium-137.

  8. Moon's Radiation Environment and Expected Performance of Solar Cells during Future Lunar Missions

    CERN Document Server

    Girish, T E

    2010-01-01

    Several lunar missions are planned ahead and there is an increasing demand for efficient photovoltaic power generation in the moon. The knowledge of solar cell operation in the lunar surface obtained during early seventies need to be updated considering current views on solar variability and emerging space solar cell technologies. In this paper some aspects of the solar cell performance expected under variable lunar radiation environment during future space missions to moon are addressed. We have calculated relative power expected from different types of solar cells under extreme solar proton irradiation conditions and high lunar daytime temperature. It is also estimated that 2-3 % of annual solar cell degradation is most probable during the future lunar missions. We have also discussed photovoltaic power generation in long term lunar bases emphasizing technological needs such as sunlight concentration, solar cell cooling and magnetic shielding of radiation for improving the efficiency of solar cells in the l...

  9. Meteoroid Environment Modeling: The Meteoroid Engineering Model and Shower Forecasting

    Science.gov (United States)

    Moorhead, Althea V.

    2017-01-01

    The meteoroid environment is often divided conceptually into meteor showers and the sporadic meteor background. It is commonly but incorrectly assumed that meteoroid impacts primarily occur during meteor showers; instead, the vast majority of hazardous meteoroids belong to the sporadic complex. Unlike meteor showers, which persist for a few hours to a few weeks, sporadic meteoroids impact the Earth's atmosphere and spacecraft throughout the year. The Meteoroid Environment Office (MEO) has produced two environment models to handle these cases: the Meteoroid Engineering Model (MEM) and an annual meteor shower forecast. The sporadic complex, despite its year-round activity, is not isotropic in its directionality. Instead, their apparent points of origin, or radiants, are organized into groups called "sources". The speed, directionality, and size distribution of these sporadic sources are modeled by the Meteoroid Engineering Model (MEM), which is currently in its second major release version (MEMR2) [Moorhead et al., 2015]. MEM provides the meteoroid flux relative to a user-provided spacecraft trajectory; it provides the total flux as well as the flux per angular bin, speed interval, and on specific surfaces (ram, wake, etc.). Because the sporadic complex dominates the meteoroid flux, MEM is the most appropriate model to use in spacecraft design. Although showers make up a small fraction of the meteoroid environment, they can produce significant short-term enhancements of the meteoroid flux. Thus, it can be valuable to consider showers when assessing risks associated with vehicle operations that are brief in duration. To assist with such assessments, the MEO issues an annual forecast that reports meteor shower fluxes as a function of time and compares showers with the time-averaged total meteoroid flux. This permits missions to do quick assessments of the increase in risk posed by meteor showers. Section II describes MEM in more detail and describes our current efforts

  10. Hybrid Models for Trajectory Error Modelling in Urban Environments

    Science.gov (United States)

    Angelatsa, E.; Parés, M. E.; Colomina, I.

    2016-06-01

    This paper tackles the first step of any strategy aiming to improve the trajectory of terrestrial mobile mapping systems in urban environments. We present an approach to model the error of terrestrial mobile mapping trajectories, combining deterministic and stochastic models. Due to urban specific environment, the deterministic component will be modelled with non-continuous functions composed by linear shifts, drifts or polynomial functions. In addition, we will introduce a stochastic error component for modelling residual noise of the trajectory error function. First step for error modelling requires to know the actual trajectory error values for several representative environments. In order to determine as accurately as possible the trajectories error, (almost) error less trajectories should be estimated using extracted nonsemantic features from a sequence of images collected with the terrestrial mobile mapping system and from a full set of ground control points. Once the references are estimated, they will be used to determine the actual errors in terrestrial mobile mapping trajectory. The rigorous analysis of these data sets will allow us to characterize the errors of a terrestrial mobile mapping system for a wide range of environments. This information will be of great use in future campaigns to improve the results of the 3D points cloud generation. The proposed approach has been evaluated using real data. The data originate from a mobile mapping campaign over an urban and controlled area of Dortmund (Germany), with harmful GNSS conditions. The mobile mapping system, that includes two laser scanner and two cameras, was mounted on a van and it was driven over a controlled area around three hours. The results show the suitability to decompose trajectory error with non-continuous deterministic and stochastic components.

  11. THE EFFECT OF SOLAR RADIATION ON AUTOMOBILE ENVIRONMENT THROUGH NATURAL CONVECTION AND MIXED CONVECTION

    Directory of Open Access Journals (Sweden)

    MD. FAISAL KADER

    2012-10-01

    Full Text Available In the present paper, the effect of solar radiation on automobiles has been studied by both experimentally and numerically. The numerical solution is done by an operation friendly and fast CFD code – SC/Tetra with a full scale model of a SM3 car and turbulence is modeled by the standard k-ε equation. Numerical analysis of the three-dimensional model predicts a detailed description of fluid flow and temperature distribution in the passenger compartment during both the natural convection due to the incoming solar radiation and mixed convection due to the flow from defrost nozzle and radiation. It can be seen that solar radiation is an important parameter to raise the compartment temperature above the ambient temperature during summer. During natural convection, the rate of heat transfer is fast at the initial period. In the mixed convection analyses, it is found that the temperature drops down to a comfortable range almost linearly at the initial stage. Experimental investigations are performed to determine the temperature contour on the windshield and the local temperature at a particular point for further validation of the numerical results.

  12. Real-time 3D radiation risk assessment supporting simulation of work in nuclear environments.

    Science.gov (United States)

    Szőke, I; Louka, M N; Bryntesen, T R; Bratteli, J; Edvardsen, S T; RøEitrheim, K K; Bodor, K

    2014-06-01

    This paper describes the latest developments at the Institute for Energy Technology (IFE) in Norway, in the field of real-time 3D (three-dimensional) radiation risk assessment for the support of work simulation in nuclear environments. 3D computer simulation can greatly facilitate efficient work planning, briefing, and training of workers. It can also support communication within and between work teams, and with advisors, regulators, the media and public, at all the stages of a nuclear installation's lifecycle. Furthermore, it is also a beneficial tool for reviewing current work practices in order to identify possible gaps in procedures, as well as to support the updating of international recommendations, dissemination of experience, and education of the current and future generation of workers.IFE has been involved in research and development into the application of 3D computer simulation and virtual reality (VR) technology to support work in radiological environments in the nuclear sector since the mid 1990s. During this process, two significant software tools have been developed, the VRdose system and the Halden Planner, and a number of publications have been produced to contribute to improving the safety culture in the nuclear industry.This paper describes the radiation risk assessment techniques applied in earlier versions of the VRdose system and the Halden Planner, for visualising radiation fields and calculating dose, and presents new developments towards implementing a flexible and up-to-date dosimetric package in these 3D software tools, based on new developments in the field of radiation protection. The latest versions of these 3D tools are capable of more accurate risk estimation, permit more flexibility via a range of user choices, and are applicable to a wider range of irradiation situations than their predecessors.

  13. Animal Models of Ionizing Radiation Damage

    Science.gov (United States)

    1992-01-01

    Haggbloom, and R.A. Gazzara, Effects of Hippocampal X-irradiation-Produced Granule-Cell Agenesis on Instrumental Runway Performance in Rats, Physiol...Bowden, and J.P. Wyatt, A Pathway To Pulmonary Fibrosis: An Ultrastructural Study Of Mouse and Rat Following Radiation to the Whole Body and Hemithorax...532-536, 1956. 27. Brooks, P.M., E.O. Richey, and J.E. Pickering, Prompt Pulmonary Ventilation and Oxygen Consumption Changes in Rhesus Monkeys

  14. Modeling radiative properties of nanoscale patterned wafers

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Temperature nonuniformity in rapid thermal processing of wafers is a critical problem facing the semiconductor industry. One cause of the problem is the nonuniform absorption of thermal radiation in patterned wafers where the optical properties vary across the wafer surface. This paper presents a parametric study of the radiative properties of patterned wafers, considering the effect of temperature, wavelength, and polarization. The finite-difference time-domain (FDTD) method is employed to examine the effect of various trench sizes on the radiative properties via numerically solving the Maxwell equations. The effective medium theory (EMT) is also used to help explain the absorptance prediction. The results show that in the cases with trench size variation, the resonance cavity effect may increase the absorptance as the trench width increases. And in the cases with trench size increasing at several different filling ratios, the absorptance does not change much at small filling ratio. The effects of the resonant cavity, diffraction, wave interferences on the spectral-directional absorptance were also discussed. This work is of great importance for optimization of advanced annealing techniques in semiconductor manufacturing.

  15. The influence of the solar radiation model on the calcutated solar radiation from a horizontal surface to a tilted surface

    DEFF Research Database (Denmark)

    Andersen, Elsa; Lund, Hans; Furbo, Simon

    2004-01-01

    in the calculation. The weather data are measured at the solar radiation measurement station, SMS at the Department of Civil Engineering at the Technical University of Denmark. In this study the weather data are combined with solar collector calculations based on solar collector test carried out at Solar Energy......Measured solar radiation data are most commonly available as total solar radiation on a horizontal surface. When using solar radiation measured on horizontal to calculate the solar radiation on tilted surfaces and thereby the thermal performance of different applications such as buildings and solar...... heating systems, different solar radiation models can be used. The calculation of beam radiation from a horizontal surface to a tilted surface can be done exactly whereas different solar radiation models can calculate the sky diffuse radiation. The sky diffuse radiation can either be assumed evenly...

  16. A simple model of space radiation damage in GaAs solar cells

    Science.gov (United States)

    Wilson, J. W.; Stith, J. J.; Stock, L. V.

    1983-01-01

    A simple model is derived for the radiation damage of shallow junction gallium arsenide (GaAs) solar cells. Reasonable agreement is found between the model and specific experimental studies of radiation effects with electron and proton beams. In particular, the extreme sensitivity of the cell to protons stopping near the cell junction is predicted by the model. The equivalent fluence concept is of questionable validity for monoenergetic proton beams. Angular factors are quite important in establishing the cell sensitivity to incident particle types and energies. A fluence of isotropic incidence 1 MeV electrons (assuming infinite backing) is equivalent to four times the fluence of normal incidence 1 MeV electrons. Spectral factors common to the space radiations are considered, and cover glass thickness required to minimize the initial damage for a typical cell configuration is calculated. Rough equivalence between the geosynchronous environment and an equivalent 1 MeV electron fluence (normal incidence) is established.

  17. Preliminary Results for the Radiation Environment Observed by RD3-B3 Radiometerdosimeter Inside Bion-M # 1 Spacecraft

    Science.gov (United States)

    Dachev, Tsvetan; Tomov, Borislav; Matviichuk, Yury; Dimitrov, Plamen; Bankov, Nikolay; Petrov, Vladisloav; Shurshakov, Viacheslav; Ivanova, Olga; Häder, Donat-Peter; Lebert, Michael; Schuster, Martin; Reitz, Günter; Horneck, Gerda; Ploc, Ondrej

    2013-12-01

    Space radiation has been monitored using the P#xd0bb;3-킑3 (further is used the Latin transcription RD3-B3) spectrometer-dosimeter on board a recent space flight on the Russian recoverable satellite 킑킍OH-M No.1 (further is used the Latin transcription BIONM No. 1). The instrument was mounted inside of the satellite in pressurized volume together with biological objects and samples. RD3-B3 instrument is a battery operated version of the spare model of the R3D-B3 instrument developed and built for the ESA BIOPAN-6 facility on Foton M3 satellite flown in September 2007. Cosmic ionizing radiation has been monitored and separated in 256 deposited energy spectra, which were further used for determination of the absorbed dose rate and flux. The report summarizes the first results for the Earth radiation environment at the altitude (253-585 km) of the BION-M No.1 spacecraft.

  18. A Monte Carlo-based radiation safety assessment for astronauts in an environment with confined magnetic field shielding.

    Science.gov (United States)

    Geng, Changran; Tang, Xiaobin; Gong, Chunhui; Guan, Fada; Johns, Jesse; Shu, Diyun; Chen, Da

    2015-12-01

    The active shielding technique has great potential for radiation protection in space exploration because it has the advantage of a significant mass saving compared with the passive shielding technique. This paper demonstrates a Monte Carlo-based approach to evaluating the shielding effectiveness of the active shielding technique using confined magnetic fields (CMFs). The International Commission on Radiological Protection reference anthropomorphic phantom, as well as the toroidal CMF, was modeled using the Monte Carlo toolkit Geant4. The penetrating primary particle fluence, organ-specific dose equivalent, and male effective dose were calculated for particles in galactic cosmic radiation (GCR) and solar particle events (SPEs). Results show that the SPE protons can be easily shielded against, even almost completely deflected, by the toroidal magnetic field. GCR particles can also be more effectively shielded against by increasing the magnetic field strength. Our results also show that the introduction of a structural Al wall in the CMF did not provide additional shielding for GCR; in fact it can weaken the total shielding effect of the CMF. This study demonstrated the feasibility of accurately determining the radiation field inside the environment and evaluating the organ dose equivalents for astronauts under active shielding using the CMF.

  19. Evaluating galactic cosmic ray environment models using RaD-X flight data

    Science.gov (United States)

    Norman, R. B.; Mertens, C. J.; Slaba, T. C.

    2016-10-01

    Galactic cosmic rays enter Earth's atmosphere after interacting with the geomagnetic field. The primary galactic cosmic rays spectrum is fundamentally changed as it interacts with Earth's atmosphere through nuclear and atomic interactions. At points deeper in the atmosphere, such as at airline altitudes, the radiation environment is a combination of the primary galactic cosmic rays and the secondary particles produced through nuclear interactions. The RaD-X balloon experiment measured the atmospheric radiation environment above 20 km during 2 days in September 2015. These experimental measurements were used to validate and quantify uncertainty in physics-based models used to calculate exposure levels for commercial aviation. In this paper, the Badhwar-O'Neill 2014, the International Organization for Standardization 15390, and the German Aerospace Company galactic cosmic ray environment models are used as input into the same radiation transport code to predict and compare dosimetric quantities to RaD-X measurements. In general, the various model results match the measured tissue equivalent dose well, with results generated by the German Aerospace Center galactic cosmic ray environment model providing the best comparison. For dose equivalent and dose measured in silicon, however, the models were compared less favorably to the measurements.

  20. Exascale Co-design for Modeling Materials in Extreme Environments

    Energy Technology Data Exchange (ETDEWEB)

    Germann, Timothy C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-07-08

    Computational materials science has provided great insight into the response of materials under extreme conditions that are difficult to probe experimentally. For example, shock-induced plasticity and phase transformation processes in single-crystal and nanocrystalline metals have been widely studied via large-scale molecular dynamics simulations, and many of these predictions are beginning to be tested at advanced 4th generation light sources such as the Advanced Photon Source (APS) and Linac Coherent Light Source (LCLS). I will describe our simulation predictions and their recent verification at LCLS, outstanding challenges in modeling the response of materials to extreme mechanical and radiation environments, and our efforts to tackle these as part of the multi-institutional, multi-disciplinary Exascale Co-design Center for Materials in Extreme Environments (ExMatEx). ExMatEx has initiated an early and deep collaboration between domain (computational materials) scientists, applied mathematicians, computer scientists, and hardware architects, in order to establish the relationships between algorithms, software stacks, and architectures needed to enable exascale-ready materials science application codes within the next decade. We anticipate that we will be able to exploit hierarchical, heterogeneous architectures to achieve more realistic large-scale simulations with adaptive physics refinement, and are using tractable application scale-bridging proxy application testbeds to assess new approaches and requirements. Such current scale-bridging strategies accumulate (or recompute) a distributed response database from fine-scale calculations, in a top-down rather than bottom-up multiscale approach.

  1. Occultation Modeling for Radiation Obstruction Effects on Spacecraft Systems

    Science.gov (United States)

    de Carufel, Guy; Li, Zu Qun; Harvey, Jason; Crues, Edwin Z.; Bielski, Paul

    2016-01-01

    A geometric occultation model has been developed to determine line-of-sight obstruction of radiation sources expected for different NASA space exploration mission designs. Example applications includes fidelity improvements for surface lighting conditions, radiation pressure, thermal and power subsystem modeling. The model makes use of geometric two dimensional shape primitives to most effectively model space vehicles. A set of these primitives is used to represent three dimensional obstructing objects as a two dimensional outline from the perspective of an observing point of interest. Radiation sources, such as the Sun or a Moon's albedo is represented as a collection of points, each of which is assigned a flux value to represent a section of the radiation source. Planetary bodies, such as a Martian moon, is represented as a collection of triangular facets which are distributed in spherical height fields for optimization. These design aspects and the overall model architecture will be presented. Specific uses to be presented includes a study of the lighting condition on Phobos for a possible future surface mission, and computing the incident flux on a spacecraft's solar panels and radiators from direct and reflected solar radiation subject to self-shadowing or shadowing by third bodies.

  2. Modeling Polarized Solar Radiation for Correction of Satellite Data

    Science.gov (United States)

    Sun, W.

    2014-12-01

    Reflected solar radiation from the Earth-atmosphere system is polarized. If a non-polarimetric sensor has some polarization dependence, it can result in errors in the measured radiance. To correct the polarization-caused errors in satellite data, the polarization state of the reflected solar light must be known. In this presentation, recent studies of the polarized solar radiation from the ocean-atmosphere system with the adding-doubling radiative-transfer model (ADRTM) are reported. The modeled polarized solar radiation quantities are compared with PARASOL satellite measurements and DISORT model results. Sensitivities of reflected solar radiation's polarization to various ocean-surface and atmospheric conditions are addressed. A novel super-thin cloud detection method based on polarization measurements is also discussed. This study demonstrates that the modeling can provide a reliable approach for making the spectral Polarization Distribution Models (PDMs) for satellite inter-calibration applications of NASA's future Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission. Key words: Reflected solar radiation, polarization, correction of satellite data.

  3. Simulation and modeling of solar radiation in Saudi Arabia

    Energy Technology Data Exchange (ETDEWEB)

    Zuhairy, A.A.; Sayigh, A.A.M. [Reading Univ. (United Kingdom). Dept. of Engineering

    1995-04-01

    A mathematical model is used to generate the hourly data for the total solar radiation on a horizontal surface. The generated data are based on the hourly recorded visibility data for 20 years (1970-1989). The model year technique was then applied to model the 20 years of hourly data of solar radiation into one statistically representative year. A model year of hourly data was then generated for the beam and diffuse components of solar radiation on a horizontal surface. Similarly, a model year of hourly data was also generated for the total solar radiation on tilted surfaces with different orientations with its beam, diffuse and reflected components. A simple methodology is proposed for calculating the solar radiation on vertical surfaces, based on a solar impact factor (SIF). Monthly means and daily totals of hourly sums for each month of the year are discussed. The hourly data of solar radiation for a typical day for each month of the year are presented. The data were generated for the four climatic zones of Saudi Arabia, the hot-dry (Riyadh), the warm-humid (Jeddah), the maritime inland desert climate (Dhahran) and the upland climate zone (Taif). The accuracy of the results is discussed and found to be above 90% representative. (author)

  4. Multijunction Solar Cell Efficiencies: Effect of Spectral Window, Optical Environment and Radiative Coupling

    Science.gov (United States)

    2014-09-04

    the photon  ux as a function of energy in the 1 sun AM1.5D spectrum, q is the charge of an electron, h is Planck’s constant, c is the speed of light, k...reduced photon  ux will decrease both photocurrent and voltage. This decline is still the most severe for B ¼ 0 because there is no radiative coupling to...optical environment dictate the performance of subcells in a multi- junction cell. As the number of subcells increases, the photon  ux each subcell

  5. Effect of ionizing radiation on the waste package environment; Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    Reed, D.T. [Argonne National Lab., IL (USA); Van Konynenburg, R.A. [Lawrence Livermore National Lab., CA (USA)

    1991-05-01

    The radiolytic production of nitrogen oxides, nitrogen acids and ammonia are discussed in relation to the expected environment in a high-level waste repository that may be constructed at the Yucca Mountain site if it is found to be suitable. Both literature data and repository-relevant data are summarized for air-water vapor systems. The limiting cases of a dry air and a pure water vapor gas phase are also discussed. Design guidelines and recommendations, based solely on the potential consequence of radiation enhancement of corrosion, are given. 13 refs., 5 figs., 1 tab.

  6. Radon measurements by etched track detectors applications in radiation protection, earth sciences and the environment

    CERN Document Server

    Durrani, Saeed A

    1997-01-01

    Exposure to radon gas, which is present in the environment naturally, constitutes over half the radiation dose received by the general public annually. At present, the most widely used method of measuring radon concentration levels throughout the world, both in dwellings and in the field, is by etched track detectors - also known as Solid State Nuclear Detectors (SSNTDs). Although this is not only the most widely used method but is also the simplest and the cheapest, yet there is at present no book available on the market globally, devoted exclusively or largely to the methodology of, and deal

  7. Improved Solar-Radiation-Pressure Models for GPS Satellites

    Science.gov (United States)

    Bar-Sever, Yoaz; Kuang, Da

    2006-01-01

    A report describes a series of computational models conceived as an improvement over prior models for determining effects of solar-radiation pressure on orbits of Global Positioning System (GPS) satellites. These models are based on fitting coefficients of Fourier functions of Sun-spacecraft- Earth angles to observed spacecraft orbital motions.

  8. Plasmonic-cavity model for radiating nano-rod antennas.

    Science.gov (United States)

    Peng, Liang; Mortensen, N Asger

    2014-01-23

    In this paper, we propose the analytical solution of nano-rod antennas utilizing a cylindrical harmonics expansion. By treating the metallic nano-rods as plasmonic cavities, we derive closed-form expressions for both the internal and the radiated fields, as well as the resonant condition and the radiation efficiency. With our theoretical model, we show that besides the plasmonic resonances, efficient radiation takes advantage of (a) rendering a large value of the rods' radius and (b) a central-fed profile, through which the radiation efficiency can reach up to 70% and even higher in a wide frequency band. Our theoretical expressions and conclusions are general and pave the way for engineering and further optimization of optical antenna systems and their radiation patterns.

  9. A Simplified Scheme of the Generalized Layered Radiative Transfer Model

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this paper, firstly, a simplified version (SGRTM) of the generalized layered radiative transfer model (GRTM) within the canopy, developed by us, is presented. It reduces the information requirement of inputted sky diffuse radiation, as well as of canopy morphology, and in turn saves computer resources. Results from the SGRTM agree perfectly with those of the GRTM. Secondly, by applying the linear superposition principle of the optics and by using the basic solutions of the GRTM for radiative transfer within the canopy under the condition of assumed zero soil reflectance, two sets of explicit analytical solutions of radiative transfer within the canopy with any soil reflectance magnitude are derived: one for incident diffuse, and the other for direct beam radiation. The explicit analytical solutions need two sets of basic solutions of canopy reflectance and transmittance under zero soil reflectance, run by the model for both diffuse and direct beam radiation. One set of basic solutions is the canopy reflectance αf (written as α1 for direct beam radiation) and transmittance βf (written as β1 for direction beam radiation) with zero soil reflectance for the downward radiation from above the canopy (i.e. sky), and the other set is the canopy reflectance (αb) and transmittanceβb for the upward radiation from below the canopy (i.e., ground). Under the condition of the same plant architecture in the vertical layers, and the same leaf adaxial and abaxial optical properties in the canopies for the uniform diffuse radiation, the explicit solutions need only one set of basic solutions, because under this condition the two basic solutions are equal, i.e., αf = αb and βf = βb. Using the explicit analytical solutions, the fractions of any kind of incident solar radiation reflected from (defined as surface albedo, or canopy reflectance),transmitted through (defined as canopy transmittance), and absorbed by (defined as canopy absorptance)the canopy and other properties

  10. The low Earth orbit radiation environment and its impact on the prompt background of hard x-ray focusing telescopes

    Science.gov (United States)

    Fioretti, V.; Bulgarelli, A.; Malaguti, G.; Bianchin, V.; Trifoglio, M.; Gianotti, F.

    2012-07-01

    The background minimization is a science-driven necessity in order to reach deep sensitivity levels in the hard X-ray band, one of the key scientific requirements for hard X-ray telescopes (e.g. NuSTAR, ASTRO-H). It requires a careful modeling of the radiation environment and new concepts of shielding systems. We exploit the Bologna Geant4 Multi-Mission Simulator (BoGEMMS) features to evaluate the impact of the Low Earth Orbit (LEO) radiation environment on the prompt background level for a hybrid Si/CdTe soft and hard X-ray detection assembly and a combined active and passive shielding system. For each class of particles, the spectral distribution of the background flux is simulated, exploring the effect of different materials (plastic vs inorganic active scintillator) and configurations (passive absorbers enclosing or surrounded by the active shielding) on the background count rate. While protons are efficiently removed by the active shielding, an external passive shielding causes the albedo electrons and positrons to be the primary source of background. Albedo neutrons are instead weakly interactive with the active shielding, and they cause an intense background level below 10 keV via elastic scattering. The best shielding configuration in terms of background and active shielding count rates is given by an inorganic scintillator placed inside the passive layers, with the addition of passive material to absorb the intense fluorescence lines of the active shielding and avoid escape peaks on the CdTe detector.

  11. Initiation-promotion model of tumor prevalence in mice from space radiation exposures.

    Science.gov (United States)

    Cucinotta, F A; Wilson, J W

    1995-08-01

    Exposures in space consist of low-level background components from galactic cosmic rays (GCR), occasional intense-energetic solar-particle events, periodic passes through geomagnetic-trapped radiation, and exposure from possible onboard nuclear-propulsion engines. Risk models for astronaut exposure from such diverse components and modalities must be developed to assure adequate protection in future NASA missions. The low-level background exposures (GCR), including relativistic heavy ions (HZE), will be the ultimate limiting factor for astronaut career exposure. We consider herein a two-mutation, initiation-promotion, radiation-carcinogenesis model in mice in which the initiation stage is represented by a linear kinetics model of cellular repair/misrepair, including the track-structure model for heavy ion action cross-sections. The model is validated by comparison with the harderian gland tumor experiments of Alpen et al. for various ion beams. We apply the initiation-promotion model to exposures from galactic cosmic rays, using models of the cosmic-ray environment and heavy ion transport, and consider the effects of the age of the mice prior to and after the exposure and of the length of time in space on predictions of relative risk. Our results indicate that biophysical models of age-dependent radiation hazard will provide a better understanding of GCR risk than models that rely strictly on estimates of the initial slopes of these radiations.

  12. Radiative and non-radiative recombinations in tensile strained Ge microstrips: Photoluminescence experiments and modeling

    Energy Technology Data Exchange (ETDEWEB)

    Virgilio, M., E-mail: virgilio@df.unipi.it [Dip. di Fisica “E. Fermi,” Università di Pisa, Largo Pontecorvo 3, 56127 Pisa (Italy); NEST, Istituto Nanoscienze-CNR, P.za San Silvestro 12, 56127 Pisa (Italy); Schroeder, T.; Yamamoto, Y. [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Capellini, G. [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Dip. di scienze, Università Roma Tre, viale G. Marconi 446, 00146 Roma (Italy)

    2015-12-21

    Tensile germanium microstrips are candidate as gain material in Si-based light emitting devices due to the beneficial effect of the strain field on the radiative recombination rate. In this work, we thoroughly investigate their radiative recombination spectra by means of micro-photoluminescence experiments at different temperatures and excitation powers carried out on samples featuring different tensile strain values. For sake of comparison, bulk Ge(001) photoluminescence is also discussed. The experimental findings are interpreted in light of a numerical modeling based on a multi-valley effective mass approach, taking in to account the depth dependence of the photo-induced carrier density and of the self-absorption effect. The theoretical modeling allowed us to quantitatively describe the observed increase of the photoluminescence intensity for increasing values of strain, excitation power, and temperature. The temperature dependence of the non-radiative recombination time in this material has been inferred thanks to the model calibration procedure.

  13. Accuracy of Analog Fiber-Optic Links in Pulsed Radiation Environments

    Energy Technology Data Exchange (ETDEWEB)

    E. K. Miller, G. S. Macrum, I. J. McKenna, et al.

    2007-12-01

    Interferometric fiber-optic links used in pulsed-power experiments are evaluated for accuracy in the presence of radiation fields which alter fiber transmission. Amplitude-modulated format (e.g., Mach-Zehnder) and phase-modulated formats are compared. Historically, studies of radiation effects on optical fibers have focused on degradation and recovery of the fibers transmission properties; such work is either in the context of survivability of fibers in catastrophic conditions or suitability of fibers installed for command and control systems within an experimental facility [1], [2]. In this work, we consider links used to transmit realtime diagnostic data, and we analyze the error introduced by radiation effects during the drive pulse. The result is increased uncertainties in key parameters required to unfold the sinusoidal transfer function. Two types of modulation are considered: amplitude modulation typical of a Mach-Zehnder (M-Z) modulator [3], and phase modulation, which offers more flexible demodulation options but relies on the spatiotemporal coherence of the light in the fiber. The M-Z link is shown schematically in Fig. 1, and the phase-modulated link is shown in Fig. 2. We present data from two experimental environments: one with intense, controlled radiation fields to simulate conditions expected at the next generation of pulsed-power facilities, and the second with radiation effects below the noise level of the recording system. In the first case, we intentionally expose three types of single-mode fiber (SMF) to ionizing radiation and study the response by simultaneously monitoring phase and amplitude of the transmitted light. The phase and amplitude effects are evidently dominated by different physical phenomena, as their recovery dynamics are markedly different; both effects, though, show similar short-term behavior during exposure, integrating the dose at the dose levels studied, from 1 to 300 kRad, over the exposure times of 50 ps and 30 ns. In the

  14. Free-streaming radiation in cosmological models with spatial curvature

    Science.gov (United States)

    Wilson, M. L.

    1982-01-01

    The effects of spatial curvature on radiation anisotropy are examined for the standard Friedmann-Robertson-Walker model universes. The effect of curvature is found to be very important when considering fluctuations with wavelengths comparable to the horizon. It is concluded that the behavior of radiation fluctuations in models with spatial curvature is quite different from that in spatially flat models, and that models with negative curvature are most strikingly different. It is therefore necessary to take the curvature into account in careful studies of the anisotropy of the microwave background.

  15. Atmospheric radiation modeling of galactic cosmic rays using LRO/CRaTER and the EMMREM model with comparisons to balloon and airline based measurements

    Science.gov (United States)

    Joyce, C. J.; Schwadron, N. A.; Townsend, L. W.; deWet, W. C.; Wilson, J. K.; Spence, H. E.; Tobiska, W. K.; Shelton-Mur, K.; Yarborough, A.; Harvey, J.; Herbst, A.; Koske-Phillips, A.; Molina, F.; Omondi, S.; Reid, C.; Reid, D.; Shultz, J.; Stephenson, B.; McDevitt, M.; Phillips, T.

    2016-09-01

    We provide an analysis of the galactic cosmic ray radiation environment of Earth's atmosphere using measurements from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) aboard the Lunar Reconnaissance Orbiter (LRO) together with the Badhwar-O'Neil model and dose lookup tables generated by the Earth-Moon-Mars Radiation Environment Module (EMMREM). This study demonstrates an updated atmospheric radiation model that uses new dose tables to improve the accuracy of the modeled dose rates. Additionally, a method for computing geomagnetic cutoffs is incorporated into the model in order to account for location-dependent effects of the magnetosphere. Newly available measurements of atmospheric dose rates from instruments aboard commercial aircraft and high-altitude balloons enable us to evaluate the accuracy of the model in computing atmospheric dose rates. When compared to the available observations, the model seems to be reasonably accurate in modeling atmospheric radiation levels, overestimating airline dose rates by an average of 20%, which falls within the uncertainty limit recommended by the International Commission on Radiation Units and Measurements (ICRU). Additionally, measurements made aboard high-altitude balloons during simultaneous launches from New Hampshire and California provide an additional comparison to the model. We also find that the newly incorporated geomagnetic cutoff method enables the model to represent radiation variability as a function of location with sufficient accuracy.

  16. An Instructional Method for the AutoCAD Modeling Environment.

    Science.gov (United States)

    Mohler, James L.

    1997-01-01

    Presents a command organizer for AutoCAD to aid new uses in operating within the 3-D modeling environment. Addresses analyzing the problem, visualization skills, nonlinear tools, a static view of a dynamic model, the AutoCAD organizer, environment attributes, and control of the environment. Contains 11 references. (JRH)

  17. An Instructional Method for the AutoCAD Modeling Environment.

    Science.gov (United States)

    Mohler, James L.

    1997-01-01

    Presents a command organizer for AutoCAD to aid new uses in operating within the 3-D modeling environment. Addresses analyzing the problem, visualization skills, nonlinear tools, a static view of a dynamic model, the AutoCAD organizer, environment attributes, and control of the environment. Contains 11 references. (JRH)

  18. Building Information Modelling for Smart Built Environments

    Directory of Open Access Journals (Sweden)

    Jianchao Zhang

    2015-01-01

    Full Text Available Building information modelling (BIM provides architectural 3D visualization and a standardized way to share and exchange building information. Recently, there has been an increasing interest in using BIM, not only for design and construction, but also the post-construction management of the built facility. With the emergence of smart built environment (SBE technology, which embeds most spaces with smart objects to enhance the building’s efficiency, security and comfort of its occupants, there is a need to understand and address the challenges BIM faces in the design, construction and management of future smart buildings. In this paper, we investigate how BIM can contribute to the development of SBE. Since BIM is designed to host information of the building throughout its life cycle, our investigation has covered phases from architecture design to facility management. Firstly, we extend BIM for the design phase to provide material/device profiling and the information exchange interface for various smart objects. Next, we propose a three-layer verification framework to assist BIM users in identifying possible defects in their SBE design. For the post-construction phase, we have designed a facility management tool to provide advanced energy management of smart grid-connected SBEs, where smart objects, as well as distributed energy resources (DERs are deployed.

  19. Measurement and Modeling of Particle Radiation in Coal Flames

    DEFF Research Database (Denmark)

    Bäckström, Daniel; Johansson, Robert; Andersson, Klas Jerker

    2014-01-01

    This work aims at developing a methodology that can provide information of in-flame particle radiation in industrial-scale flames. The method is based on a combination of experimental and modeling work. The experiments have been performed in the high-temperature zone of a 77 kWth swirling lignite...... properties. The in-flame particle radiation was measured with a Fourier transform infrared (FTIR) spectrometer connected to a water-cooled probe via fiber optics. In the cross-section of the flame investigated, the particles were found to be the dominating source of radiation. Apart from giving information...

  20. Ethics, genetics and dynamics: an emerging systematic approach to radiation protection of the environment.

    Science.gov (United States)

    Pentreath, R J

    2004-01-01

    There is now a general consensus of opinion that an explicit approach is necessary to demonstrate radiation protection of the environment, and that this approach needs to be developed in a systematic way. The framework that is emerging links ethical and moral issues (anthropocentric, biocentric, and ecocentric) to broad-based principles and objectives of environmental protection (sustainable development, maintaining biological diversity, and habitat protection) and then links these, in turn, to the needs of current environmental management practices, such as environmental exploitation, pollution control, and nature conservation. The relevance of this to radiation is that its effects (such as causing early mortality, morbidity, reduced reproductive success, as well as resulting in observable (scorable) cytogenetic damage) are those that may have a bearing on these same environmental management practices. The devise that would appear to be most useful to bridge the gap between our disparate data on radiation effects and the needs of environmental management, is that of adding to the concept of Reference Man in the shape of a small set of Reference Animals and Plants. This approach has now been adopted by the ICRP, adding new dynamics-the motive forces, both moral and physical-to the subject. The way is now clear for rapid progress to be made on a number of fronts.

  1. Ethics, genetics and dynamics: an emerging systematic approach to radiation protection of the environment

    Energy Technology Data Exchange (ETDEWEB)

    Pentreath, R.J

    2004-07-01

    There is now a general consensus of opinion that an explicit approach is necessary to demonstrate radiation protection of the environment, and that this approach needs to be developed in a systematic way. The framework that is emerging links ethical and moral issues (anthropocentric, biocentric, and ecocentric) to broad-based principles and objectives of environmental protection (sustainable development, maintaining biological diversity, and habitat protection) and then links these, in turn, to the needs of current environmental management practices, such as environmental exploitation, pollution control, and nature conservation. The relevance of this to radiation is that its effects (such as causing early mortality, morbidity, reduced reproductive success, as well as resulting in observable (scorable) cytogenetic damage) are those that may have a bearing on these same environmental management practices. The devise that would appear to be most useful to bridge the gap between our disparate data on radiation effects and the needs of environmental management, is that of adding to the concept of Reference Man in the shape of a small set of Reference Animals and Plants. This approach has now been adopted by the ICRP, adding new dynamics--the motive forces, both moral and physical--to the subject. The way is now clear for rapid progress to be made on a number of fronts.

  2. A Model for Hourly Solar Radiation Data Generation from Daily Solar Radiation Data Using a Generalized Regression Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Tamer Khatib

    2015-01-01

    Full Text Available This paper presents a model for predicting hourly solar radiation data using daily solar radiation averages. The proposed model is a generalized regression artificial neural network. This model has three inputs, namely, mean daily solar radiation, hour angle, and sunset hour angle. The output layer has one node which is mean hourly solar radiation. The training and development of the proposed model are done using MATLAB and 43800 records of hourly global solar radiation. The results show that the proposed model has better prediction accuracy compared to some empirical and statistical models. Two error statistics are used in this research to evaluate the proposed model, namely, mean absolute percentage error and root mean square error. These values for the proposed model are 11.8% and −3.1%, respectively. Finally, the proposed model shows better ability in overcoming the sophistic nature of the solar radiation data.

  3. SRADLIB: A C Library for Solar Radiation Modelling

    Energy Technology Data Exchange (ETDEWEB)

    Balenzategui, J. L. [Ciemat. Madrid (Spain)

    2000-07-01

    This document shows the result of an exhaustive study about the theoretical and numerical models available in the literature about solar radiation modelling. The purpose of this study is to develop or adapt mathematical models describing the solar radiation specifically for Spain locations as well as to create computer tools able to support the labour of researchers or engineers needing solar radiation data to solve or improve the technical or energetic performance of solar systems. As results of this study and revision, a C library (SRADLIB) is presented as a key for the compilation of the mathematical models from different authors, for the comparison among the different approaches and for its application in computer programs. Different topics related to solar radiation and its modelling are first discussed, including the assumptions and conventions adopted and describing the most accepted and used current state-of-the-art models. some typical problems in the numerical calculation of radiation values are also posed with the proposed solution. The document includes next a complete reference of the developed functions, with many examples of application and calculus. (Author) 24 refs.

  4. Markedly enhanced absorption and direct radiative forcing of black carbon under polluted urban environments

    Science.gov (United States)

    Peng, Jianfei; Hu, Min; Guo, Song; Du, Zhuofei; Zheng, Jing; Shang, Dongjie; Levy Zamora, Misti; Zeng, Limin; Shao, Min; Wu, Yu-Sheng; Zheng, Jun; Wang, Yuan; Glen, Crystal R.; Collins, Donald R.; Molina, Mario J.

    2016-04-01

    Black carbon (BC) exerts profound impacts on air quality and climate because of its high absorption cross-section over a broad range of electromagnetic spectra, but the current results on absorption enhancement of BC particles during atmospheric aging remain conflicting. Here, we quantified the aging and variation in the optical properties of BC particles under ambient conditions in Beijing, China, and Houston, United States, using a novel environmental chamber approach. BC aging exhibits two distinct stages, i.e., initial transformation from a fractal to spherical morphology with little absorption variation and subsequent growth of fully compact particles with a large absorption enhancement. The timescales to achieve complete morphology modification and an absorption amplification factor of 2.4 for BC particles are estimated to be 2.3 h and 4.6 h, respectively, in Beijing, compared with 9 h and 18 h, respectively, in Houston. Our findings indicate that BC under polluted urban environments could play an essential role in pollution development and contribute importantly to large positive radiative forcing. The variation in direct radiative forcing is dependent on the rate and timescale of BC aging, with a clear distinction between urban cities in developed and developing countries, i.e., a higher climatic impact in more polluted environments. We suggest that mediation in BC emissions achieves a cobenefit in simultaneously controlling air pollution and protecting climate, especially for developing countries.

  5. Group Modeling in Social Learning Environments

    Science.gov (United States)

    Stankov, Slavomir; Glavinic, Vlado; Krpan, Divna

    2012-01-01

    Students' collaboration while learning could provide better learning environments. Collaboration assumes social interactions which occur in student groups. Social theories emphasize positive influence of such interactions on learning. In order to create an appropriate learning environment that enables social interactions, it is important to…

  6. Radioactivity in food and the environment: calculations of UK radiation doses using integrated assessment methods

    Energy Technology Data Exchange (ETDEWEB)

    Camplin, W C; Brownless, G P; Round, G D; Winpenny, K; Hunt, G J [Centre for Environment, Fisheries and Aquaculture Science, CEFAS Laboratory, Lowestoft (United Kingdom)

    2002-12-01

    A new method for estimating radiation doses to UK critical groups is proposed for discussion. Amongst others, the Food Standards Agency (FSA) and the Scottish Environment Protection Agency (SEPA) undertake surveillance of UK food and the environment as a check on the effect of discharges of radioactive wastes. Discharges in gaseous and liquid form are made under authorisation by the Environment Agency and SEPA under powers in the Radioactive Substance Act. Results of surveillance by the FSA and SEPA are published in the Radioactivity in Food and the Environment (RIFE) report series. In these reports, doses to critical groups are normally estimated separately for gaseous and liquid discharge pathways. Simple summation of these doses would tend to overestimate doses actually received. Three different methods of combining the effects of both types of discharge in an integrated assessment are considered and ranked according to their ease of application, transparency, scientific rigour and presentational issues. A single integrated assessment method is then chosen for further study. Doses are calculated for surveillance data for the calendar year 2000 and compared with those from the existing RIFE method.

  7. Combined Injury Modeling: Radiation and Burn Workshop Report

    Science.gov (United States)

    2010-10-01

    when radiation exposure is combined with burn. For instance, in the Chernobyl accident, hepatic encephalopathy was a major cause of death in patients...for radiation injury that block apoptosis and have demonstrated increased survival in animal models (Whitnall and Pellmar 2007). Cell loss also... Animal studies are needed to resolve this information gap. However, Institutional Animal Care and Use Committee (IACUC) approval for these types

  8. Pharmacological doses of daily ascorbate protect tumours from radiation damage after a single dose of radiation in an intracranial mouse glioma model

    Directory of Open Access Journals (Sweden)

    Carole eGrasso

    2014-12-01

    Full Text Available Pharmacological ascorbate is currently used as an anti-cancer treatment, potentially in combination with radiation therapy, by integrative medicine practitioners. In the acidic, metal-rich tumour environment, ascorbate acts as a pro-oxidant, with a mode of action similar to that of ionising radiation; both treatments kill cells predominantly by free radical-mediated DNA damage. The brain tumour, glioblastoma multiforme (GBM, is very resistant to radiation; radiosensitising GBM cells will improve survival of GBM patients. Here we demonstrate that a single fraction (6 Gy of radiation combined with a one hour exposure to ascorbate (5 mM sensitised murine glioma GL261cells to radiation in survival and colony-forming assays in vitro. In addition, we report the effect of a single fraction (4.5 Gy of whole brain radiation combined with daily intra-peritoneal injections of ascorbate (1 mg/kg in an intra-cranial GL261 glioma mouse model. Tumour-bearing C57BL/6 mice were divided into four groups: one group received a single dose of 4.5 Gy to the brain eight days after tumour implantation, a second group received daily intra-peritoneal injections of ascorbate (day 8-45 after implantation, a third group received both treatments and a fourth control group received no treatment. While radiation delayed tumour progression, intra-peritoneal ascorbate alone had no effect on tumour progression. Tumour progression was faster in tumour-bearing mice treated with radiation and daily ascorbate than those treated with radiation alone. Histological analysis showed less necrosis in tumours treated with both radiation and ascorbate, consistent with a radio-protective effect of ascorbate in vivo. Discrepancies between our in vitro and in vivo results may be explained by differences in the tumour micro-environment which determines whether ascorbate remains outside the cell, acting as a pro-oxidant or whether it enters the cells and acts as an anti-oxidant.

  9. Using ecosystem science to improve protection of the environment from radiation

    Energy Technology Data Exchange (ETDEWEB)

    Bradshaw, C. [Stockholm University (Sweden); Brechignac, F. [IUR / IRSN (France); Barnthouse, L. [LWB Environmental Services Inc. (United States); Brown, J. [Norwegian Radiation Protection Authority - NRPA (Norway); Forbes, V. [University of Lincoln (United Kingdom); Kapustka, L. [LC LK Consultancy (Canada); Kautsky, U. [Svensk Kaernbraenslehantering AB - SKB (Sweden)

    2014-07-01

    The ecosystem approach (EA) involves considering the impacts of an anthropogenic stressor at the ecosystem level because this is usually the ultimate goal of environmental protection. As such, EA includes population, community and ecosystem effects, structural and functional effects, indirect effects due to ecological interactions between species, dynamic interactions, positive or negative feedback loops, and potential synergistic or antagonistic effects of multiple stressors (both anthropogenic and natural). All such effects better reflect the reality of the impact of a contamination scenario than if assessments are restricted to considering effects to individual organisms or species. Such effects may be greater or lesser than expected from studies of individual organisms or species, so not considering them may result in under- or overestimation of risk, respectively. EA is a term that is widely used in environmental assessment, management and legislation in a number of regulatory fields (e.g., radiation protection, chemicals legislation, fisheries policy, international biodiversity conventions). However, although its justification is now well established in a wide range of environment protection contexts, its practical use is still unclear due to poorly defined protection goals and assessment endpoints, making its implementation difficult. This paper presents the initial findings of a newly formed follow-up task group of the International Union of Radioecology whose aims are to identify ways to put the EA into practice when considering protection of the environment from radiation. Drawing on knowledge and experience from a range of fields, we summarise the types of ecosystem processes, goods and services that might be included when using this approach, the science that supports the use of the EA, and the methodological challenges that need to be addressed when implementing the EA in the field of radiation protection. Document available in abstract form only

  10. MagRad: A code to optimize the operation of superconducting magnets in a radiation environment

    Energy Technology Data Exchange (ETDEWEB)

    Yeaw, Christopher T. [Univ. of Wisconsin, Madison, WI (United States)

    1995-01-01

    A powerful computational tool, called MagRad, has been developed which optimizes magnet design for operation in radiation fields. Specifically, MagRad has been used for the analysis and design modification of the cable-in-conduit conductors of the TF magnet systems in fusion reactor designs. Since the TF magnets must operate in a radiation environment which damages the material components of the conductor and degrades their performance, the optimization of conductor design must account not only for start-up magnet performance, but also shut-down performance. The degradation in performance consists primarily of three effects: reduced stability margin of the conductor; a transition out of the well-cooled operating regime; and an increased maximum quench temperature attained in the conductor. Full analysis of the magnet performance over the lifetime of the reactor includes: radiation damage to the conductor, stability, protection, steady state heat removal, shielding effectiveness, optimal annealing schedules, and finally costing of the magnet and reactor. Free variables include primary and secondary conductor geometric and compositional parameters, as well as fusion reactor parameters. A means of dealing with the radiation damage to the conductor, namely high temperature superconductor anneals, is proposed, examined, and demonstrated to be both technically feasible and cost effective. Additionally, two relevant reactor designs (ITER CDA and ARIES-II/IV) have been analyzed. Upon addition of pure copper strands to the cable, the ITER CDA TF magnet design was found to be marginally acceptable, although much room for both performance improvement and cost reduction exists. A cost reduction of 10-15% of the capital cost of the reactor can be achieved by adopting a suitable superconductor annealing schedule. In both of these reactor analyses, the performance predictive capability of MagRad and its associated costing techniques have been demonstrated.

  11. MCNP model for the many KE-Basin radiation sources

    Energy Technology Data Exchange (ETDEWEB)

    Rittmann, P.D.

    1997-05-21

    This document presents a model for the location and strength of radiation sources in the accessible areas of KE-Basin which agrees well with data taken on a regular grid in September of 1996. This modelling work was requested to support dose rate reduction efforts in KE-Basin. Anticipated fuel removal activities require lower dose rates to minimize annual dose to workers. With this model, the effects of component cleanup or removal can be estimated in advance to evaluate their effectiveness. In addition, the sources contributing most to the radiation fields in a given location can be identified and dealt with.

  12. Different radiation impedance models for finite porous materials

    DEFF Research Database (Denmark)

    Nolan, Melanie; Jeong, Cheol-Ho; Brunskog, Jonas;

    2015-01-01

    coupled to the transfer matrix method (TMM). These methods are found to yield comparable results when predicting the Sabine absorption coefficients of finite porous materials. Discrepancies with measurement results can essentially be explained by the unbalance between grazing and non-grazing sound field...... the infinite case. Thus, in order to predict the Sabine absorption coefficients of finite porous samples, one can incorporate models of the radiation impedance. In this study, different radiation impedance models are compared with two experimental examples. Thomasson’s model is compared to Rhazi’s method when...

  13. Modelling of aircrew radiation exposure during solar particle events

    Energy Technology Data Exchange (ETDEWEB)

    Al Anid, H.; Lewis, B.J.; Bennett, L.G.I. [Royal Military College of Canada, Dept. of Chemistry and Chemical Engineering, Kingston, Ontario (Canada); Takada, M. [National Inst. of Radiological Science, International Space Radiation Lab., anagawa, Inage-Ku, Chiba (Japan)

    2010-07-01

    A transport code analysis using the Monte Carlo N-Particle eXtended code, MCNPX, has been used to propagate an extrapolated particle spectrum based on satellite measurements through the atmosphere to estimate radiation exposure during solar storms at high altitudes. Neutron monitor count rate data from stations around the world were used to benchmark the model calculations during a Ground Level Event. A comparison was made between the model predictions and actual flight measurements taken with various types of instruments used to measure the mixed radiation field during GLE 60. A computer-code has been developed to implement the model for routine analysis. (author)

  14. Modelling of aircrew radiation exposure during solar particle events

    Energy Technology Data Exchange (ETDEWEB)

    Al Anid, H.; Lewis, B.J.; Bennett, L.G.I. [Royal Military College of Canada, Dept. of Chemistry and Chemical Engineering, Kingston, Ontario (Canada); Takada, M. [National Inst. of Radiological Science, International Space Radiation Lab., Anagawa, Inage-Ku, Chiba (Japan)

    2011-03-15

    A transport code analysis using the Monte Carlo N-Particle eXtended code, MCNPX, has been used to propagate an extrapolated particle spectrum based on satellite measurements through the atmosphere to estimate radiation exposure during solar storms at high altitudes. Neutron monitor count rate data from stations around the world were used to benchmark the model calculations during a Ground Level Event. A comparison was made between the model predictions and actual flight measurements taken with various types of instruments used to measure the mixed radiation field during GLE 60. A computer-code has been developed to implement the model for routine analysis. (author)

  15. Modelling of aircrew radiation exposure from solar particle events

    Energy Technology Data Exchange (ETDEWEB)

    Al Anid, H.; Lewis, B.J.; Bennett, L.G.I. [Royal Military College of Canada, Dept. of Chemistry and Chemical Engineering, Kingston, Ontario (Canada)

    2008-07-01

    A transport code analysis using the Monte Carlo code, MCNPX, has been used to propagate an extrapolated particle spectrum based on GOES satellite measurements through the atmosphere to estimate aircrew radiation exposure due to solar particle events. Neutron monitor count rate data from ground stations around the world were used to benchmark the model calculations during several Ground Level Events (GLEs). In addition, a comparison was made between the model predictions and actual flight measurements made by some European investigators with various types of instrument used to measure the mixed radiation field during GLE 60 and 65. A computer-code has been further developed to implement the model for routine analysis. (author)

  16. Population-Development-Environment Modeling in the Philippines: A Review

    OpenAIRE

    1996-01-01

    This article surveys existing forecasting models in the Philippines and discusses several promising alternatives in the process of developing a methodological modeling. Investigation of CGE models leads to the findings of the absence of population-environment interactions.

  17. Modelling emission turbulence-radiation interaction by using a hybrid flamelet/stochastic Eulerian field method

    Science.gov (United States)

    Consalvi, Jean-Louis

    2017-01-01

    The time-averaged Radiative Transfer Equation (RTE) introduces two unclosed terms, known as `absorption Turbulence Radiation Interaction (TRI)' and `emission TRI'. Emission TRI is related to the non-linear coupling between fluctuations of the absorption coefficient and fluctuations of the Planck function and can be described without introduction any approximation by using a transported PDF method. In this study, a hybrid flamelet/ Stochastic Eulerian Field Model is used to solve the transport equation of the one-point one-time PDF. In this formulation, the steady laminar flamelet model (SLF) is coupled to a joint Probability Density Function (PDF) of mixture fraction, enthalpy defect, scalar dissipation rate, and soot quantities and the PDF transport equation is solved by using a Stochastic Eulerian Field (SEF) method. Soot production is modeled by a semi-empirical model and the spectral dependence of the radiatively participating species, namely combustion products and soot, are computed by using a Narrow Band Correlated-k (NBCK) model. The model is applied to simulate an ethylene/methane turbulent jet flame burning in an oxygen-enriched environment. Model results are compared with the experiments and the effects of taken into account Emission TRI on flame structure, soot production and radiative loss are discussed.

  18. High-energy radiation damage in zirconia: modeling results

    Energy Technology Data Exchange (ETDEWEB)

    Zarkadoula, Eva; Devanathan, Ram; Weber, William J.; Seaton, Michael; Todorov, Ilian; Nordlund, Kai; Dove, Martin T.; Trachenko, Kostya

    2014-02-28

    Zirconia has been viewed as a material of exceptional resistance to amorphization by radiation damage, and was consequently proposed as a candidate to immobilize nuclear waste and serve as a nuclear fuel matrix. Here, we perform molecular dynamics simulations of radiation damage in zirconia in the range of 0.1-0.5 MeV energies with the account of electronic energy losses. We find that the lack of amorphizability co-exists with a large number of point defects and their clusters. These, importantly, are largely disjoint from each other and therefore represent a dilute damage that does not result in the loss of long-range structural coherence and amorphization. We document the nature of these defects in detail, including their sizes, distribution and morphology, and discuss practical implications of using zirconia in intense radiation environments.

  19. High-energy radiation damage in zirconia: modeling results

    Energy Technology Data Exchange (ETDEWEB)

    Zarkadoula, Evangelia [Queen Mary, University of London; Devanathan, Ram [Pacific Northwest National Laboratory (PNNL); Weber, William J [ORNL; Seaton, M [Daresbury Laboratory, UK; Todorov, I T [Daresbury Laboratory, UK; Nordlund, Kai [University of Helsinki; Dove, Martin T [Queen Mary, University of London; Trachenko, Kostya [Queen Mary, University of London

    2014-01-01

    Zirconia is viewed as a material of exceptional resistance to amorphization by radiation damage, and consequently proposed as a candidate to immobilize nuclear waste and serve as an inert nuclear fuel matrix. Here, we perform molecular dynamics simulations of radiation damage in zirconia in the range of 0.1-0.5 MeV energies with account of electronic energy losses. We nd that the lack of amorphizability co-exists with a large number of point defects and their clusters. These, importantly, are largely isolated from each other and therefore represent a dilute damage that does not result in the loss of long-range structural coherence and amorphization. We document the nature of these defects in detail, including their sizes, distribution and morphology, and discuss practical implications of using zirconia in intense radiation environments.

  20. High-energy radiation damage in zirconia: Modeling results

    Energy Technology Data Exchange (ETDEWEB)

    Zarkadoula, E., E-mail: zarkadoulae@ornl.gov [School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); SEPnet, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Devanathan, R. [Nuclear Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Weber, W. J. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Seaton, M. A.; Todorov, I. T. [STFC Daresbury Laboratory, Scientific Computing Department, Keckwick Lane, Daresbury, Warrington, Cheshire WA4 4AD (United Kingdom); Nordlund, K. [University of Helsinki, P.O. Box 43, FIN-00014 Helsinki (Finland); Dove, M. T. [School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Trachenko, K. [School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); SEPnet, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom)

    2014-02-28

    Zirconia is viewed as a material of exceptional resistance to amorphization by radiation damage, and consequently proposed as a candidate to immobilize nuclear waste and serve as an inert nuclear fuel matrix. Here, we perform molecular dynamics simulations of radiation damage in zirconia in the range of 0.1–0.5 MeV energies with account of electronic energy losses. We find that the lack of amorphizability co-exists with a large number of point defects and their clusters. These, importantly, are largely isolated from each other and therefore represent a dilute damage that does not result in the loss of long-range structural coherence and amorphization. We document the nature of these defects in detail, including their sizes, distribution, and morphology, and discuss practical implications of using zirconia in intense radiation environments.

  1. Radiation risk estimation based on measurement error models

    CERN Document Server

    Masiuk, Sergii; Shklyar, Sergiy; Chepurny, Mykola; Likhtarov, Illya

    2017-01-01

    This monograph discusses statistics and risk estimates applied to radiation damage under the presence of measurement errors. The first part covers nonlinear measurement error models, with a particular emphasis on efficiency of regression parameter estimators. In the second part, risk estimation in models with measurement errors is considered. Efficiency of the methods presented is verified using data from radio-epidemiological studies.

  2. Modeling Based Decision Support Environment Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Phoenix Integration's vision is the creation of an intuitive human-in-the-loop engineering environment called Decision Navigator that leverages recent advances in...

  3. [Comparison of three daily global solar radiation models].

    Science.gov (United States)

    Yang, Jin-Ming; Fan, Wen-Yi; Zhao, Ying-Hui

    2014-08-01

    Three daily global solar radiation estimation models ( Å-P model, Thornton-Running model and model provided by Liu Ke-qun et al.) were analyzed and compared using data of 13 weather stations from 1982 to 2012 from three northeastern provinces and eastern Inner Mongolia. After cross-validation analysis, the result showed that mean absolute error (MAE) for each model was 1.71, 2.83 and 1.68 MJ x m(-2) x d(-1) respectively, showing that Å-P model and model provided by Liu Ke-qun et al. which used percentage of sunshine had an advantage over Thornton-Running model which didn't use percentage of sunshine. Model provided by Liu Ke-qun et al. played a good effect on the situation of non-sunshine, and its MAE and bias percentage were 18.5% and 33.8% smaller than those of Å-P model, respectively. High precision results could be obtained by using the simple linear model of Å-P. Å-P model, Thornton-Running model and model provided by Liu Ke-qun et al. overvalued daily global solar radiation by 12.2%, 19.2% and 9.9% respectively. MAE for each station varied little with the spatial change of location, and annual MAE decreased with the advance of years. The reason for this might be that the change of observation accuracy caused by the replacement of radiation instrument in 1993. MAEs for rainy days, non-sunshine days and warm seasons of the three models were greater than those for days without rain, sunshine days and cold seasons respectively, showing that different methods should be used for different weather conditions on estimating solar radiation with meteorological elements.

  4. Addressing ecological effects of radiation on populations and ecosystems to improve protection of the environment against radiation: Agreed statements from a Consensus Symposium☆

    Science.gov (United States)

    Bréchignac, François; Oughton, Deborah; Mays, Claire; Barnthouse, Lawrence; Beasley, James C.; Bonisoli-Alquati, Andrea; Bradshaw, Clare; Brown, Justin; Dray, Stéphane; Geras’kin, Stanislav; Glenn, Travis; Higley, Kathy; Ishida, Ken; Kapustka, Lawrence; Kautsky, Ulrik; Kuhne, Wendy; Lynch, Michael; Mappes, Tapio; Mihok, Steve; Møller, Anders P.; Mothersill, Carmel; Mousseau, Timothy A.; Otaki, Joji M.; Pryakhin, Evgeny; Rhodes, Olin E.; Salbu, Brit; Strand, Per; Tsukada, Hirofumi

    2016-01-01

    This paper reports the output of a consensus symposium organized by the International Union of Radioecology in November 2015. The symposium gathered an academically diverse group of 30 scientists to consider the still debated ecological impact of radiation on populations and ecosystems. Stimulated by the Chernobyl and Fukushima disasters’ accidental contamination of the environment, there is increasing interest in developing environmental radiation protection frameworks. Scientific research conducted in a variety of laboratory and field settings has improved our knowledge of the effects of ionizing radiation on the environment. However, the results from such studies sometimes appear contradictory and there is disagreement about the implications for risk assessment. The Symposium discussions therefore focused on issues that might lead to different interpretations of the results, such as laboratory versus field approaches, organism versus population and ecosystemic inference strategies, dose estimation approaches and their significance under chronic exposure conditions. The participating scientists, from across the spectrum of disciplines and research areas, extending also beyond the traditional radioecology community, successfully developed a constructive spirit directed at understanding discrepancies. From the discussions, the group has derived seven consensus statements related to environmental protection against radiation, which are supplemented with some recommendations. Each of these statements is contextualized and discussed in view of contributing to the orientation and integration of future research, the results of which should yield better consensus on the ecological impact of radiation and consolidate suitable approaches for efficient radiological protection of the environment. PMID:27058410

  5. Addressing ecological effects of radiation on populations and ecosystems to improve protection of the environment against radiation: Agreed statements from a Consensus Symposium.

    Science.gov (United States)

    Bréchignac, François; Oughton, Deborah; Mays, Claire; Barnthouse, Lawrence; Beasley, James C; Bonisoli-Alquati, Andrea; Bradshaw, Clare; Brown, Justin; Dray, Stéphane; Geras'kin, Stanislav; Glenn, Travis; Higley, Kathy; Ishida, Ken; Kapustka, Lawrence; Kautsky, Ulrik; Kuhne, Wendy; Lynch, Michael; Mappes, Tapio; Mihok, Steve; Møller, Anders P; Mothersill, Carmel; Mousseau, Timothy A; Otaki, Joji M; Pryakhin, Evgeny; Rhodes, Olin E; Salbu, Brit; Strand, Per; Tsukada, Hirofumi

    2016-07-01

    This paper reports the output of a consensus symposium organized by the International Union of Radioecology in November 2015. The symposium gathered an academically diverse group of 30 scientists to consider the still debated ecological impact of radiation on populations and ecosystems. Stimulated by the Chernobyl and Fukushima disasters' accidental contamination of the environment, there is increasing interest in developing environmental radiation protection frameworks. Scientific research conducted in a variety of laboratory and field settings has improved our knowledge of the effects of ionizing radiation on the environment. However, the results from such studies sometimes appear contradictory and there is disagreement about the implications for risk assessment. The Symposium discussions therefore focused on issues that might lead to different interpretations of the results, such as laboratory versus field approaches, organism versus population and ecosystemic inference strategies, dose estimation approaches and their significance under chronic exposure conditions. The participating scientists, from across the spectrum of disciplines and research areas, extending also beyond the traditional radioecology community, successfully developed a constructive spirit directed at understanding discrepancies. From the discussions, the group has derived seven consensus statements related to environmental protection against radiation, which are supplemented with some recommendations. Each of these statements is contextualized and discussed in view of contributing to the orientation and integration of future research, the results of which should yield better consensus on the ecological impact of radiation and consolidate suitable approaches for efficient radiological protection of the environment.

  6. Modern methods in collisional-radiative modeling of plasmas

    CERN Document Server

    2016-01-01

    This book provides a compact yet comprehensive overview of recent developments in collisional-radiative (CR) modeling of laboratory and astrophysical plasmas. It describes advances across the entire field, from basic considerations of model completeness to validation and verification of CR models to calculation of plasma kinetic characteristics and spectra in diverse plasmas. Various approaches to CR modeling are presented, together with numerous examples of applications. A number of important topics, such as atomic models for CR modeling, atomic data and its availability and quality, radiation transport, non-Maxwellian effects on plasma emission, ionization potential lowering, and verification and validation of CR models, are thoroughly addressed. Strong emphasis is placed on the most recent developments in the field, such as XFEL spectroscopy. Written by leading international research scientists from a number of key laboratories, the book offers a timely summary of the most recent progress in this area. It ...

  7. A coupled dynamical-radiational model of stratocumulus

    Science.gov (United States)

    Ye, Weizuo

    1990-05-01

    A model dealing with interactions between the air and low stratiform clouds is presented based on the mixed-layer model Lilly (1968) pioneered and on Deardorff's three dimensional numerical model results. Its main new aspects lie in 1) consideration of the natures of both the atmosphere and cloud; 2) a new entrainment velocity scheme with few arbitrary assumptions; 3) transition from one-mixed layer to two-mixed layer model; and 4) parameterization of radiation and precipitation calculations. The model results for radiation, moisture, and heat turbulent fluxes turn out to be in good agreement with those calculated or observed by Kawa (1988), Nicholls (1984), and Schmets et al. (1981) in California, the North Sea, and the North Atlantic, respectively. Basically, this paper furnishes the theoretical basis for a model to address questions concerning the time-evolution of thermodynamical profiles both in cloud and out of cloud. The applications of this model wil be in a separate paper.

  8. General analysis of dark radiation in sequestered string models

    Energy Technology Data Exchange (ETDEWEB)

    Cicoli, Michele [ICTP,Strada Costiera 11, Trieste 34014 (Italy); Dipartimento di Fisica e Astronomia, Università di Bologna,via Irnerio 46, 40126 Bologna (Italy); INFN, Sezione di Bologna,via Irnerio 46, 40126 Bologna (Italy); Muia, Francesco [Dipartimento di Fisica e Astronomia, Università di Bologna,via Irnerio 46, 40126 Bologna (Italy); INFN, Sezione di Bologna,via Irnerio 46, 40126 Bologna (Italy)

    2015-12-22

    We perform a general analysis of axionic dark radiation produced from the decay of the lightest modulus in the sequestered LARGE Volume Scenario. We discuss several cases depending on the form of the Kähler metric for visible sector matter fields and the mechanism responsible for achieving a de Sitter vacuum. The leading decay channels which determine dark radiation predictions are to hidden sector axions, visible sector Higgses and SUSY scalars depending on their mass. We show that in most of the parameter space of split SUSY-like models squarks and sleptons are heavier than the lightest modulus. Hence dark radiation predictions previously obtained for MSSM-like cases hold more generally also for split SUSY-like cases since the decay channel to SUSY scalars is kinematically forbidden. However the inclusion of string loop corrections to the Kähler potential gives rise to a parameter space region where the decay channel to SUSY scalars opens up, leading to a significant reduction of dark radiation production. In this case, the simplest model with a shift-symmetric Higgs sector can suppress the excess of dark radiation ΔN{sub eff} to values as small as 0.14, in perfect agreement with current experimental bounds. Depending on the exact mass of the SUSY scalars all values in the range 0.14≲ΔN{sub eff}≲1.6 are allowed. Interestingly dark radiation overproduction can be avoided also in the absence of a Giudice-Masiero coupling.

  9. Model of cell response to {\\alpha}-particle radiation

    CERN Document Server

    Liu, Longjian

    2012-01-01

    Starting from a general equation for organism (or cell system) growth and attributing additional cell death rate (besides the natural rate) to therapy, we derive an equation for cell response to {\\alpha} radiation. Different from previous models that are based on statistical theory, the present model connects the consequence of radiation with the growth process of a biosystem and each variable or parameter has meaning regarding the cell evolving process. We apply this equation to model the dose response for {\\alpha}-particle radiation. It interprets the results of both high and low linear energy transfer (LET) radiations. When LET is high, the additional death rate is a constant, which implies that the localized cells are damaged immediately and the additional death rate is proportional to the number of cells present. While at low LET, the additional death rate includes a constant term and a linear term of radiation dose, implying that the damage to some cell nuclei has a time accumulating effect. This model ...

  10. Short and long term ionizing radiation effects on charge-coupled devices in radiation environment of high-intensity heavy ion accelerators

    Science.gov (United States)

    Belousov, A.; Mustafin, E.; Ensinger, W.

    2012-11-01

    Radiation effects on semiconductor devices is a topical issue for high-intensity accelerator projects. In particular it concerns Charge-Coupled Device (CCD) cameras, which are widely used for beam profile monitoring and surveillance in high radiation environment. One should have a clear idea of short and long term radiation effects on such devices. To study these effects, a CCD camera was placed in positions less than half meter away from beam loss point. Primary heavy ion beam of 0.95GeV/n Uranium was dumped into a thick aluminium target creating high fluences of secondary particles (e.g., gammas, neutrons, protons). Effects of these particles on CCD camera were scored with LabView based acquisition software. Monte Carlo calculations with FLUKA code were performed to obtain fluence distributions for different particles and make relevant comparisons. Long term total ionising dose effects are represented by dark current increase, which was scored throughout experiment. Instant radiation effects are represented by creation of charge in CCD cells by ionising particles. Relation of this charge to beam intensity was obtained for different camera positions and fluences within 5 orders of magnitude ranges. With high intensities this charge is so high that it may dramatically influence data obtained from CCD camera used in high radiation environment. The linearity of described above relation confirms linear response of CCD to ionizing radiation. It gives an opportunity to find a new application to CCD cameras as beam loss monitors (BLM).

  11. Modelling radiation damage to ESA's Gaia satellite CCDs

    CERN Document Server

    Seabroke, G M; Cropper, M S

    2008-01-01

    The Gaia satellite is a high-precision astrometry, photometry and spectroscopic ESA cornerstone mission, currently scheduled for launch in late 2011. Its primary science drivers are the composition, formation and evolution of the Galaxy. Gaia will achieve its scientific requirements with detailed calibration and correction for radiation damage. Microscopic models of Gaia's CCDs are being developed to simulate the charge trapping effect of radiation damage, which causes charge transfer inefficiency. The key to calculating the probability of a photoelectron being captured by a trap is the 3D electron density within each CCD pixel. However, this has not been physically modelled for Gaia CCD pixels. In this paper, the first of a series, we motivate the need for such specialised 3D device modelling and outline how its future results will fit into Gaia's overall radiation calibration strategy.

  12. Modeling gravitational radiation from coalescing binary black holes

    CERN Document Server

    Baker, J; Loustó, C O; Takahashi, R

    2002-01-01

    With the goal of bringing theory, particularly numerical relativity, to bear on an astrophysical problem of critical interest to gravitational wave observers we introduce a model for coalescence radiation from binary black hole systems. We build our model using the "Lazarus approach", a technique that bridges far and close limit approaches with full numerical relativity to solve Einstein equations applied in the truly nonlinear dynamical regime. We specifically study the post-orbital radiation from a system of equal-mass non-spinning black holes, deriving waveforms which indicate strongly circularly polarized radiation of roughly 3% of the system's total energy and 12% of its total angular momentum in just a few cycles. Supporting this result we first establish the reliability of the late-time part of our model, including the numerical relativity and close-limit components, with a thorough study of waveforms from a sequence of black hole configurations varying from previously treated head-on collisions to rep...

  13. Investigation of innovative radiation imaging method and system for radiological environments

    Science.gov (United States)

    Nguyen, H.; Joung, J.; Kim, Y.; Lee, K.

    2017-03-01

    We have developed a novel imaging method that can be applied to most applications in the field of radiological environment imaging. It resolves either two-dimensional (2D) or three-dimensional (3D) distributions of radioactive sources in applications for homeland security, environmental monitoring, radiation contamination monitoring, baggage inspection, nuclear power plant monitoring, and more. The proposed imaging method uses a simple detector configured as a radiation-counting detector with spectroscopic capabilities. The detector module consists of two components: a flat field-of-view (FOV) collimator with a 30° FOV opening and a typical single-channel radiation detector made of a 2 in.×2 in. NaI(Tl) scintillator coupled to a 2 in photomultiplier tube (PMT). This simple detector module makes it possible to develop a cost-effective imaging system and provide design freedom in extending the system configuration to include one-dimensional (1D) or 2D detector-array shapes to meet the needs of various applications. One of most distinctive features of the new imaging method is that it uses only a pair of 2D projections to obtain a 3D reconstruction. The projections are measured by the proposed detector module at two positions orthogonal to one another; the measured projections are manipulated to enhance the resolution of the reconstructed 3D image. The imaging method comprises several steps performed consecutively: projection measurement, energy re-binning, projection separation, resolution and attenuation recovery, image reconstruction, and image consolidation and quantitative analysis. The resolution and attenuation recovery step provides the most distinctive and important processing by which the poor quality of projection data is enhanced. Such poor quality is mainly due to the use of a simple detector with a wide-opening flat FOV collimator. Simulation and experimental studies have been conducted to validate the proposed method. In this investigation, we

  14. Organization and operation of the sixth international symposium on the natural radiation environment (NRE VI). Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hopke, P.K.

    1995-12-31

    An important source of human exposure to radiation is the natural world including cosmic rays, cosmogonic radionuclides, natural terrestrial radionuclides, and radon isotopes and its decay products. Considerable effort is being expended on a worldwide basis to characterize the exposure to the natural radiation environment and determine the important pathways for the exposure to result in dose to tissue that leads to injury and disease. The problem of background exposure to naturally occurring radioactivity has been the subject of research since the initial discovery of the radioactivity of uranium and thorium. However, with the advent of artificial sources of radiation with both benefits (medical x-rays and nuclear medicine), and harm (Chernobyl fallout), the nature and magnitude of the natural radiation environment and the effects on various populations are important in the development of overall public health strategies as ALARA principles are applied. To facilitate the exchange of information and the review of uncertainties and scientific research priorities, a series of 5 international meetings on Natural Radiation Environment, 1963, 1987, 1991. This conference (Montreal, 1995) covers the range of natural radiation environments that give rise to human exposure and dose. This document is a program summary.

  15. Stationary radiation cataracts: an animal model

    Energy Technology Data Exchange (ETDEWEB)

    Holsclaw, D.S.; Merriam, G.R. Jr; Medvedovsky, C.; Worgul, B.V. (Columbia Univ., New York, NY (USA)); Rothstein, H. (Fordham Univ., New York, NY (USA))

    1989-03-01

    This report describes the induction of stationary radiation cataracts in postmetamorphic bullfrogs following ocular irradiation with a 10 Gy dose of X-rays. The eyes of non-irradiated animals and animals irradiated with 25 Gy served as controls. The 25 Gy irradiated lenses rapidly progressed to complete opacification (4+) by 26 weeks, while lenses exposed to 10 Gy advanced to the 2.5+ stage by 35 weeks and progressed no further. In the lower dose lenses, transparent cortex began to appear anteriorly and posteriorly between the capsule and opaque fibers at 45 weeks. As the clear fibers accumulated, the disrupted region came to occupy increasingly deeper cortex. Histologically, opacities in both groups were preceded by disorganization of the bow cytoarchitecture, meridional row disorganization, and the appearance in the lens epithelium of nuclear polymorphism, fragmented nuclei, micronuclei, clusters of nuclei, and abnormal mitotic figures. In the lenses exposed to the 25 Gy dose, this damage continued to worsen, so that the 4+ stage was characterized by extensive epithelial cell death, absence of the lens bow, degenerated fiber masses, and liquefied substrata. In contrast, prior to the appearance of transparent cortex in the 10 Gy group, the lens epithelial aberrations, arc of the bow, and meridional row disorganization were all observed to improve. Further, by 69 weeks, the lens epithelium appeared as a largely homogeneous population, and the meridional rows and the arc of the bow had become reestablished. (author).

  16. Statistical Modeling for Radiation Hardness Assurance

    Science.gov (United States)

    Ladbury, Raymond L.

    2014-01-01

    We cover the models and statistics associated with single event effects (and total ionizing dose), why we need them, and how to use them: What models are used, what errors exist in real test data, and what the model allows us to say about the DUT will be discussed. In addition, how to use other sources of data such as historical, heritage, and similar part and how to apply experience, physics, and expert opinion to the analysis will be covered. Also included will be concepts of Bayesian statistics, data fitting, and bounding rates.

  17. A Computational Model of Cellular Response to Modulated Radiation Fields

    Energy Technology Data Exchange (ETDEWEB)

    McMahon, Stephen J., E-mail: stephen.mcmahon@qub.ac.uk [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom); Butterworth, Karl T. [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom); McGarry, Conor K. [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom); Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Northern Ireland (United Kingdom); Trainor, Colman [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom); O' Sullivan, Joe M. [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom); Clinical Oncology, Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Belfast, Northern Ireland (United Kingdom); Hounsell, Alan R. [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom); Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Northern Ireland (United Kingdom); Prise, Kevin M. [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom)

    2012-09-01

    Purpose: To develop a model to describe the response of cell populations to spatially modulated radiation exposures of relevance to advanced radiotherapies. Materials and Methods: A Monte Carlo model of cellular radiation response was developed. This model incorporated damage from both direct radiation and intercellular communication including bystander signaling. The predictions of this model were compared to previously measured survival curves for a normal human fibroblast line (AGO1522) and prostate tumor cells (DU145) exposed to spatially modulated fields. Results: The model was found to be able to accurately reproduce cell survival both in populations which were directly exposed to radiation and those which were outside the primary treatment field. The model predicts that the bystander effect makes a significant contribution to cell killing even in uniformly irradiated cells. The bystander effect contribution varies strongly with dose, falling from a high of 80% at low doses to 25% and 50% at 4 Gy for AGO1522 and DU145 cells, respectively. This was verified using the inducible nitric oxide synthase inhibitor aminoguanidine to inhibit the bystander effect in cells exposed to different doses, which showed significantly larger reductions in cell killing at lower doses. Conclusions: The model presented in this work accurately reproduces cell survival following modulated radiation exposures, both in and out of the primary treatment field, by incorporating a bystander component. In addition, the model suggests that the bystander effect is responsible for a significant portion of cell killing in uniformly irradiated cells, 50% and 70% at doses of 2 Gy in AGO1522 and DU145 cells, respectively. This description is a significant departure from accepted radiobiological models and may have a significant impact on optimization of treatment planning approaches if proven to be applicable in vivo.

  18. Radiative transfer model for contaminated rough slabs

    CERN Document Server

    Andrieu, François; Schmidt, Frédéric; Schmitt, Bernard

    2015-01-01

    We present a semi-analytical model to simulate bidirectional reflectance distribution function (BRDF) spectra of a rough slab layer containing impurities. This model has been optimized for fast computation in order to analyze hyperspectral data. We designed it for planetary surfaces ices studies but it could be used for other purposes. It estimates the bidirectional reflectance of a rough slab of material containing inclusions, overlaying an optically thick media (semi-infinite media or stratified media, for instance granular material). The inclusions are supposed to be close to spherical, and of any type of other material than the ice matrix. It can be any type of other ice, mineral or even bubbles, defined by their optical constants. We suppose a low roughness and we consider the geometrical optics conditions. This model is thus applicable for inclusions larger than the considered wavelength. The scattering on the inclusions is assumed to be isotropic. This model has a fast computation implementation and th...

  19. Atmospheric transmittance model for photosynthetically active radiation

    Energy Technology Data Exchange (ETDEWEB)

    Paulescu, Marius; Stefu, Nicoleta; Gravila, Paul; Paulescu, Eugenia; Boata, Remus; Pacurar, Angel; Mares, Oana [Physics Department, West University of Timisoara, V Parvan 4, 300223 Timisoara (Romania); Pop, Nicolina [Department of Physical Foundations of Engineering, Politehnica University of Timisoara, V Parvan 2, 300223 Timisoara (Romania); Calinoiu, Delia [Mechanical Engineering Faculty, Politehnica University of Timisoara, Mihai Viteazu 1, 300222 Timisoara (Romania)

    2013-11-13

    A parametric model of the atmospheric transmittance in the PAR band is presented. The model can be straightforwardly applied for calculating the beam, diffuse and global components of the PAR solar irradiance. The required inputs are: air pressure, ozone, water vapor and nitrogen dioxide column content, Ångström's turbidity coefficient and single scattering albedo. Comparison with other models and ground measured data shows a reasonable level of accuracy for this model, making it suitable for practical applications. From the computational point of view the calculus is condensed into simple algebra which is a noticeable advantage. For users interested in speed-intensive computation of the effective PAR solar irradiance, a PC program based on the parametric equations along with a user guide are available online at http://solar.physics.uvt.ro/srms.

  20. A biokinetic model for zinc for use in radiation protection

    Energy Technology Data Exchange (ETDEWEB)

    Leggett, R.W., E-mail: rwl@ornl.gov

    2012-03-15

    The physiology of the essential trace element zinc has been studied extensively in human subjects using kinetic analysis of time-dependent measurements of administered zinc tracers. A number of biokinetic models describing zinc exchange between plasma and tissues and endogenous excretion of zinc have been derived as fits to data for specific study groups. More rudimentary biokinetic models for zinc have been developed to estimate radiation doses from internally deposited radioisotopes of zinc. The latter models are designed to provide broadly accurate estimates of cumulative decays of zinc radioisotopes in tissues and are not intended as realistic descriptions of the directions of movement of zinc in the body. This paper reviews biokinetic data for zinc and proposes a physiologically meaningful biokinetic model for systemic zinc for use in radiation protection. The proposed model bears some resemblance to zinc models developed in physiological studies but depicts a finer division of systemic zinc and is based on a broader spectrum of data than previous models. The proposed model and the model for zinc currently recommended by the International Commission on Radiological Protection yield reasonably similar estimates of total-body retention and effective dose for internally deposited radioisotopes of zinc but much different systemic distributions of activity and much different dose estimates for some individual tissues, particularly the liver. - Highlights: Black-Right-Pointing-Pointer Zinc is an essential trace element with numerous functions in the human body. Black-Right-Pointing-Pointer Several biokinetic models for zinc have been developed from tracer studies on humans. Black-Right-Pointing-Pointer More rudimentary biokinetic models for zinc have been developed in radiation protection. Black-Right-Pointing-Pointer Biokinetic data for zinc are reviewed and a new biokinetic model is proposed for radiation protection. Black-Right-Pointing-Pointer The proposed model

  1. Modelling the luminous efficacy of solar radiation

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, E. [Universidad Autonoma de Madrid (Spain). Dpto. de Fisica Aplicada; Soler, A.; Robledo, L. [Universidad de Madrid (Spain). Dpto. de Fisic a e Instalaciones Aplicadas

    2000-07-01

    The global and diffuse luminous efficacy models proposed in Muneer (1995), Muneer and Kinghorn (1997), have been tested with experimental data obtained in Madrid. When the models with local coefficients are statistically assessed with local data, global illuminance L{sub g} is estimated with an acceptable accuracy, but diffuse illuminance L{sub d} is overestimated for L{sub d} higher than about 25 klux. (author)

  2. Radiation Background and Attenuation Model Validation and Development

    Energy Technology Data Exchange (ETDEWEB)

    Peplow, Douglas E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Santiago, Claudio P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-08-05

    This report describes the initial results of a study being conducted as part of the Urban Search Planning Tool project. The study is comparing the Urban Scene Simulator (USS), a one-dimensional (1D) radiation transport model developed at LLNL, with the three-dimensional (3D) radiation transport model from ORNL using the MCNP, SCALE/ORIGEN and SCALE/MAVRIC simulation codes. In this study, we have analyzed the differences between the two approaches at every step, from source term representation, to estimating flux and detector count rates at a fixed distance from a simple surface (slab), and at points throughout more complex 3D scenes.

  3. Analytical Heat Transfer Modeling of a New Radiation Calorimeter

    CERN Document Server

    Ndong, Elysée Obame; Aitken, Frédéric

    2016-01-01

    This paper deals with an analytical modeling of heat transfers simulating a new radiation calorimeter operating in a temperature range from -50 {\\deg}C to 150 {\\deg}C. The aim of this modeling is the evaluation of the feasibility and performance of the calorimeter by assessing the measurement of power losses of some electrical devices by radiation, the influence of the geometry and materials. Finally a theoretical sensibility of the new apparatus is estimated at ~1 mW. From these results the calorimeter has been successfully implemented and patented.

  4. Continuum radiative transfer Modeling of Sagittarius B2

    OpenAIRE

    Schmiedeke, A.; Schilke, P.; Möller, Th.; Sánchez-Monge, Á.; Bergin, E.; Comito, C.; Csengeri, T.; Lis, D. C.; Molinari, S.; Qin, S.L.; Rolffs, R.

    2016-01-01

    We present results from radiative transfer modeling of the continuum emission towards Sagittarius B2 (hereafter Sgr B2). We have developed a radiative transfer framework – Pandora – that employs RADMC-3D (Dullemond 2012) for a self-consistent determination of the dust temperature. With this pipeline, we have set-up a single model that consistently reproduces the thermal dust and free-free continuum emission of Sgr B2 spanning four orders of magnitude in spatial scales (0.02–45 pc) and two ord...

  5. Managing a national radiation oncologist workforce: a workforce planning model.

    Science.gov (United States)

    Stuckless, Teri; Milosevic, Michael; de Metz, Catherine; Parliament, Matthew; Tompkins, Brent; Brundage, Michael

    2012-04-01

    The specialty of radiation oncology has experienced significant workforce planning challenges in many countries. Our purpose was to develop and validate a workforce-planning model that would forecast the balance between supply of, and demand for, radiation oncologists in Canada over a minimum 10-year time frame, to identify the model parameters that most influenced this balance, and to suggest how this model may be applicable to other countries. A forward calculation model was created and populated with data obtained from national sources. Validation was confirmed using a historical prospective approach. Under baseline assumptions, the model predicts a short-term surplus of RO trainees followed by a projected deficit in 2020. Sensitivity analyses showed that access to radiotherapy (proportion of incident cases referred), individual RO workload, average age of retirement and resident training intake most influenced balance of supply and demand. Within plausible ranges of these parameters, substantial shortages or excess of graduates is possible, underscoring the need for ongoing monitoring. Workforce planning in radiation oncology is possible using a projection calculation model based on current system characteristics and modifiable parameters that influence projections. The workload projections should inform policy decision making regarding growth of the specialty and training program resident intake required to meet oncology health services needs. The methods used are applicable to workforce planning for radiation oncology in other countries and for other comparable medical specialties. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  6. Daily total global solar radiation modeling from several meteorological data

    Science.gov (United States)

    Bilgili, Mehmet; Ozgoren, Muammer

    2011-05-01

    This paper investigates the modeling of the daily total global solar radiation in Adana city of Turkey using multi-linear regression (MLR), multi-nonlinear regression (MNLR) and feed-forward artificial neural network (ANN) methods. Several daily meteorological data, i.e., measured sunshine duration, air temperature and wind speed and date of the year, i.e., monthly and daily, were used as independent variables to the MLR, MNLR and ANN models. In order to determine the relationship between the total global solar radiation and other meteorological data, and also to obtain the best independent variables, the MLR and MNLR analyses were performed with the "Stepwise" method in the Statistical Packages for the Social Sciences (SPSS) program. Thus, various models consisting of the combination of the independent variables were constructed and the best input structure was investigated. The performances of all models in the training and testing data sets were compared with the measured daily global solar radiation values. The obtained results indicated that the ANN method was better than the other methods in modeling daily total global solar radiation. For the ANN model, mean absolute error (MAE), mean absolute percentage error (MAPE), correlation coefficient ( R) and coefficient of determination ( R 2) for the training/testing data set were found to be 0.89/1.00 MJ/m2 day, 7.88/9.23%, 0.9824/0.9751, and 0.9651/0.9508, respectively.

  7. Radiative transfer modeling of surface chemical deposits

    Science.gov (United States)

    Reichardt, Thomas A.; Kulp, Thomas J.

    2016-05-01

    Remote detection of a surface-bound chemical relies on the recognition of a pattern, or "signature," that is distinct from the background. Such signatures are a function of a chemical's fundamental optical properties, but also depend upon its specific morphology. Importantly, the same chemical can exhibit vastly different signatures depending on the size of particles composing the deposit. We present a parameterized model to account for such morphological effects on surface-deposited chemical signatures. This model leverages computational tools developed within the planetary and atmospheric science communities, beginning with T-matrix and ray-tracing approaches for evaluating the scattering and extinction properties of individual particles based on their size and shape, and the complex refractive index of the material itself. These individual-particle properties then serve as input to the Ambartsumian invariant imbedding solution for the reflectance of a particulate surface composed of these particles. The inputs to the model include parameters associated with a functionalized form of the particle size distribution (PSD) as well as parameters associated with the particle packing density and surface roughness. The model is numerically inverted via Sandia's Dakota package, optimizing agreement between modeled and measured reflectance spectra, which we demonstrate on data acquired on five size-selected silica powders over the 4-16 μm wavelength range. Agreements between modeled and measured reflectance spectra are assessed, while the optimized PSDs resulting from the spectral fitting are then compared to PSD data acquired from independent particle size measurements.

  8. A model of human physiology and comfort for assessing complex thermal environments

    Energy Technology Data Exchange (ETDEWEB)

    Huizenga, C.; Zhang Hui; Arens, E. [University of California, Berkeley, CA (United States). Center for Environmental Design Research

    2001-07-01

    The Berkeley Comfort Model is based on the Stolwijk model of human thermal regulation but includes several significant improvements. Our new model allows an unlimited body segment (compared to six in the Stolwijk model). Each segment is modeled as four body layers (core, muscle, fat, and skin tissues) and a clothing layer. Physiological mechanisms such as vasodilation, vasoconstriction, sweating, and metabolic heat production are explicitly considered. Convection, conduction (such as to a car seat or other surface in contact with any part of the body) and radiation between the body and the environment are treated independently. The model is capable of predicting human physiological response to transient, non-uniform thermal environments. This paper describes the physiological algorithms as well as the implementation of the model. (author)

  9. 1-D Radiative-Convective Model for Terrestrial Exoplanet Atmospheres

    Science.gov (United States)

    Leung, Cecilia W. S.; Robinson, Tyler D.

    2016-10-01

    We present a one dimensional radiative-convective model to study the thermal structure of terrestrial exoplanetary atmospheres. The radiative transfer and equilibrium chemistry in our model is based on similar methodologies in models used for studying Extrasolar Giant Planets (Fortney et al. 2005b.) We validated our model in the optically thin and thick limits, and compared our pressure-temperature profiles against the analytical solutions of Robinson & Catling (2012). For extrasolar terrestrial planets with pure hydrogen atmospheres, we evaluated the effects of H2-H2 collision induced absorption and identified the purely roto-translational band in our modeled spectra. We also examined how enhanced atmospheric metallicities affect the temperature structure, chemistry, and spectra of terrestrial exoplanets. For a terrestrial extrasolar planet whose atmospheric compostion is 100 times solar orbiting a sun-like star at 2 AU, our model resulted in a reducing atmosphere with H2O, CH4, and NH3 as the dominant greenhouse gases.

  10. A Study on the Response Characteristics of a Fiber-Optic Radiation Sensor Model Based on Cerenkov Principle

    Energy Technology Data Exchange (ETDEWEB)

    Han, Hwa Jeong; Kim, Beom Kyu; Park, Byung Gi [Soonchunhyang Univ., Asan (Korea, Republic of)

    2016-10-15

    In recent year, various fiber-optic radiation sensors using Cerenkov principle have been developed without employing any scintillators for measuring high-energy photon, electron, etc. The main advantages of the optical fibers are the remote transmission of the light signal and immunity to pressure and electromagnetic waves. Therefore, the sensors utilizing the optical fibers can be used in hazardous radiation environments, such as the high-level radiation areas of a nuclear facility. The study to be simulated a fiber-optic radiation sensor based on Cerenkov principle and to be analyzed the response characteristics of the sensor. For the aforementioned study, the GEANT simulation toolkit was used. It is able to take into all the optical properties of fibers and is found to be appropriate to realistically describe the response of fiber-optic radiation sensor. In the recently, the fiber-optic radiation sensor have been developed in nuclear industry. Because sensor can detect gamma ray in harsh nuclear environments. In this study, we analyzed response characteristics of the fiber-optic radiation sensor. We have simulated the Monte Carlo model, for detecting the Cerenkov radiation using the fiber-optic radiation sensor. And the y-axis distribution of Cerenkov photons was obtained using output file. Simulation is performed with reference to the method of the previous research, and then the simulation results exhibited a good agreement with the previous research.

  11. Rabbit model of radiation-induced lung injury

    Institute of Scientific and Technical Information of China (English)

    Zhen-Zong Du; Hua Ren; Jian-Fei Song; Li-Fei Zhang; Feng Lin; Hai-Yong Wang

    2013-01-01

    Objective:To explore the feasibility of establishing an animal model of chronic radiation-induced lung injury.Methods:Twenty-eightNewZealand white rabbits were randomly divided into3 groups(the right lung irradiation group, the whole lung irradiation group and the control group).Animal model of radiation-induced lung injury was established by high-does radiotherapy in the irradiation groups, then all rabbits underwentCT and pathological examinations at1,2,4,8,12,16 weeks, respectively after radiation.Results:Within4 weeks of irradiation, some rabbits in the right lung irradiation group and whole lung irradiation group died. CT and pathological examinations all showed acute radiation pneumonitis.At8-12 weeks after irradiation,CT scanning showed ground glass samples signs, patchy shadows and fibrotic stripes. Pathological examination showed the fibrosis pulmonary alveolar wall thickened obviously. Conclusions:The clinical animal model of chronic radiation-induced lung injury which corresponds to practical conditions in clinic can be successfully established.

  12. Acoustic radiation field of the truncated parametric source generated by a piston radiator model and experiment

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xiaoliang; ZHU Zhemin; DU Gonghuan; TANG Haiqing; LI Shui; MIAO Rongxing

    2001-01-01

    A theoretical model is presented to describe the parametric acoustic field generated by a piston radiator. In the model, the high-frequency primary wave interaction region that is truncated by a low-pass acoustic filter can be viewed as a cylindrical source within the Rayleigh distance of the piston. When the radius of the piston is much smaller than the length of the parametric region, this model is reduced to the Berketey's End-Fire Line Array model. Comparison between numerical calculations and experimental measurement show that the generated parametric sound field (especially near the axis) agrees well with the experiment results.

  13. Radiation Hydrodynamics Modeling of Hohlraum Energetics

    Science.gov (United States)

    Patel, Mehul V.; Mauche, Christopher W.; Jones, Ogden S.; Scott, Howard A.

    2015-11-01

    Attempts to model the energetics in NIF Hohlraums have been made with varying degrees of success, with discrepancies of 0-25% being reported for the X-ray flux (10-25% for the NIC ignition platform hohlraums). To better understand the cause(s) of these discrepancies, the effects of uncertainties in modeling thermal conduction, laser-plasma interactions, atomic mixing at interfaces, and NLTE kinetics of the high-Z wall plasma must be quantified. In this work we begin by focusing on the NLTE kinetics component. We detail a simulation framework for developing an integrated HYDRA hohlraum model with predefined tolerances for energetics errors due to numerical discretization errors or statistical fluctuations. Within this framework we obtain a model for a converged 1D spherical hohlraum which is then extended to 2D. The new model is used to reexamine physics sensitivities and improve estimates of the energetics discrepancy. Prepared by LLNL under Contract DE-AC52-07NA27344.

  14. Semi-holographic model including the radiation component

    CERN Document Server

    del Campo, Sergio; Magaña, Juan; Villanueva, J R

    2014-01-01

    In this letter we study the semi holographic model which corresponds to the radiative version of the model proposed by Zhang et al. (Phys. Lett. B 694 (2010), 177) and revisited by C\\'ardenas et al. (Mon. Not. Roy. Astron. Soc. 438 (2014), 3603). This inclusion makes the model more realistic, so allows us to test it with current observational data and then answer if the inconsistency reported by C\\'ardenas et al. is relaxed.

  15. Estimation of Hourly Solar Radiation at the Surface under Cloudless Conditions on the Tibetan Plateau Using a Simple Radiation Model

    Institute of Scientific and Technical Information of China (English)

    LIANG Hong; ZHANG Renhe; LIU Jingmiao; SUN Zhian; CHENG Xinghong

    2012-01-01

    In this study,the clear sky hourly global and net solar irradiances at the surface determined using SUNFLUX,a simple parameterization scheme,for three stations (Gaize,Naqu,and Lhasa) on the Tibetan Plateau were evaluated against observation data.Our modeled results agree well with observations.The correlation coefficients between modeled and observed values were >0.99 for all three stations.The relative error of modeled results,in average was < 7%,and the root-mean-square variance was < 27 W m-2.The solar irradiances in the radiation model were slightly overestimated compared with observation data;there were at least two likely causes.First,the radiative effects of aerosols were not included in the radiation model.Second,solar irradiances determined by thermopile pyranometers include a thermal offset error that causes solar radiation to be slightly underestimated.The solar radiation absorbed by the ozone and water vapor was estimated. The results show that monthly mean solar radiation absorbed by the ozone is < 2% of the global solar radiation (< 14 W m-2).Solar radiation absorbed by water vapor is stronger in summer than in winter.The maximum amount of monthly mean solar radiation absorbed by water vapor can be up to 13% of the global solar radiation (95W m-2).This indicates that water vapor measurements with high precision are very important for precise determination of solar radiation.

  16. Occupant modeling in the aerospace environment

    NARCIS (Netherlands)

    Yaklin, P.; Lim, T.; Marshall, R.

    1999-01-01

    Dynamic testing and occupant protection standards are a reality in the aerospace industry. Methods to model these situations are evolving. A method of modeling an occupant on a crew seat, in a drop test is presented. This method combines a rigid body occupant model with a finite element model of the

  17. Electromagnetic THz Radiation Modeling by DPSM

    Science.gov (United States)

    Rahani, Ehsan Kabiri; Kundu, Tribikram

    2012-03-01

    THz or T-ray imaging and spectroscopy are becoming increasingly popular nondestructive evaluation techniques for damage detection and characterization of materials. In order to understand the interaction between the T-ray electromagnetic waves and dielectric media a reliable model of electromagnetic wave propagation through dielectric materials must be developed. A recently developed semi-analytical method called the distributed point source method (DPSM) is extended to model electromagnetic wave propagation in THz range. Since T-ray signals generated by emitters or sources are close to Gaussian beams, the DPSM modeling is carried out for Gaussian beams generated by finite sized emitters. The DPSM generated results are compared with the analytical and experimental results. T-ray propagation in layered structures in absence of any anomaly and the interaction between the Gaussian beam and the spherical scatterer are also investigated.

  18. Influence of Stochastic Modelling in Aerospace in EMC Environment

    Science.gov (United States)

    Patier, Laurent; Lallechere, Sebastien; Bonnet, Pierre; Paladian, Francoise

    2016-05-01

    This paper aims to demonstrate the ability of stochastic collocation method (SCM) for electromagnetic compatibility (EMC) space applications. The increasing number of antennas embedded on spacecraft implies growth of potential EMC issues. Harsh constraints on antennas could spoil ideal radiating performances. Project management for spacecraft development requires deeper analyses (e.g., modifying locations of several radiators) between qualification and flight models. We propose here to quantify behaviour modifications using SCM in antennas and EMC frameworks.

  19. Markedly enhanced direct radiative forcing of black carbon particles under polluted urban environments

    Science.gov (United States)

    Peng, Jianfei; Hu, Min; Guo, Song; Du, Zhuofei; Zheng, Jing; Shang, Dongjie; Zamora, Misti; Zeng, Liming; Shao, Min; Wu, Yusheng; Zheng, Jun; Wang, Yuan; Collins, Don; Zhang, Renyi

    2016-04-01

    Black carbon (BC) particles, produced from incomplete fossil fuel combustion and biomass burning, are ubiquitous in the atmosphere and have profound impacts on air quality, human health, weather, and climate. For example, in areas identified as aerosol hotspots, which include many urban centers and megacities worldwide, solar heating by BC particles has been shown to be comparable to warming due to the greenhouse gases2. Although BC represents a key short-lived climate forcer, its direct radiative forcing remains highly uncertain. In particular, the available results of absorption enhancement of BC particles during atmospheric aging are conflicting from the previous studies, leading to a large uncertainty in global radiative transfer calculation. Here, we quantified the aging and variation in the optical properties of BC particles under ambient conditions in Beijing, China and Houston, US, using a novel chamber approach. BC aging exhibits two distinct stages - initial transformation from a fractal to spherical morphology with little absorption variation and the subsequent growth of fully compact particles with a maximum absorption enhancement factor of 2.4. The variation in BC direct radiative forcing is highly dependent of the rate and timescale of aging, with an estimated increase of 0.45 (0.21 - 0.80) W m-2 from fresh to fully aged particles. Our results reveal a high climatic impact in polluted environments due to rapid aging and a clear distinction between urban cities in developed and developing countries for BC particles, highlighting a larger than recognized co-benefit in air quality improvement and climate protection by BC mediation.

  20. Continuous electromagnetic radiation monitoring in the environment: analysis of the results in Greece.

    Science.gov (United States)

    Manassas, Athanasios; Boursianis, Achilles; Samaras, Theodoros; Sahalos, John N

    2012-09-01

    Non-ionising radiation-monitoring networks were initiated as a result of the public concerns about the potential health effects from telecommunication emissions. In the present study, the data acquired from such networks in Greece are used to assess the changes in the outdoor electromagnetic environment with respect to location and time. The study shows that there is a statistically significant difference between the urban (median electric field: 1.1 V m(-1)) and the rural (median electric field: 0.3 V m(-1)) installations of monitoring units and also shows that there is a median diurnal variation (daily maximum to minimum) of 20.2 and 33.8 % for the broadcasting and mobile telecommunication emissions, respectively. Moreover, there is a difference in the electric field between daytime and night, but not between morning and afternoon. The results are in line with previously published data from spot measurements, monitoring networks and personal exposimeter studies performed in several European countries.

  1. A Linear Regression Model for Global Solar Radiation on Horizontal Surfaces at Warri, Nigeria

    Directory of Open Access Journals (Sweden)

    Michael S. Okundamiya

    2013-10-01

    Full Text Available The growing anxiety on the negative effects of fossil fuels on the environment and the global emission reduction targets call for a more extensive use of renewable energy alternatives. Efficient solar energy utilization is an essential solution to the high atmospheric pollution caused by fossil fuel combustion. Global solar radiation (GSR data, which are useful for the design and evaluation of solar energy conversion system, are not measured at the forty-five meteorological stations in Nigeria. The dearth of the measured solar radiation data calls for accurate estimation. This study proposed a temperature-based linear regression, for predicting the monthly average daily GSR on horizontal surfaces, at Warri (latitude 5.020N and longitude 7.880E an oil city located in the south-south geopolitical zone, in Nigeria. The proposed model is analyzed based on five statistical indicators (coefficient of correlation, coefficient of determination, mean bias error, root mean square error, and t-statistic, and compared with the existing sunshine-based model for the same study. The results indicate that the proposed temperature-based linear regression model could replace the existing sunshine-based model for generating global solar radiation data. Keywords: air temperature; empirical model; global solar radiation; regression analysis; renewable energy; Warri

  2. Stimuli responsive deswelling of radiation synthesized collagen hydrogel in simulated physiological environment.

    Science.gov (United States)

    Zhang, Xiangmei; Xu, Ling; Wei, Shicheng; Zhai, Maolin; Li, Jiuqiang

    2013-08-01

    Collagen hydrogels were prepared via radiation crosslinking. The simulated physiological environmental effects related to their biomedical applications on the volume phase transition of collagen hydrogel were studied, that is stimuli response to ions, temperature, and pH. The deswelling behavior of collagen hydrogel depends on the salt concentration, temperature, pH, and the hydrogel preparation procedure. Meanwhile, hydrogel structure related to the volume phase transition was investigated by FTIR, fluorescence spectrum, and HR-MAS NMR. Deswelling in salt solution caused little change on collagen conformation, and a denser network led to more significant tyrosine-derived fluorescence quenching. Hydrogen bonding between hydrated water and collagen polypeptide chain was dissociated and the activity of hydrophobic side chain increased, inducing a higher extent of contraction with the increasing of salt concentration. Moreover, salt solution treatments weakened the electrostatic interactions, side chains interactions, and hydrogen bonding of collagen hydrogel, which reduced the thermal stability of collagen hydrogel. Comparing with cell-free collagen hydrogel contraction, fibroblasts did not aggravate contraction of collagen hydrogel significantly. This study elucidated the deswelling mechanism of radiation crosslinked collagen hydrogel in simulated physiological environment and provides strategies for controlling the stimuli response of collagen hydrogel in biomedical application.

  3. Beam test results of CMS RPCs at high eta region under high-radiation environment

    CERN Document Server

    Park, S; Bahk, S Y; Hong, B; Hong, S J; Kang, D H; Kang, T I; Kim, T J; Kim, Y J; Kim, Y U; Koo, D G; Lee, H W; Lee, K S; Lee, S J; Lim, J K; Moon, D H; Nam, S K; Oh, J K; Park, W J; Rhee, J T; Ryu, M S; Shim, H H; Sim, K S

    2004-01-01

    The Compact Muon Solenoid (CMS) forward resistivity plate chambers (RPCs) at the high eta region must be operated in presence of a radiation-induced rate as high as 1 kHz/cm**2. It is still unknown if the RPCs coated with linseed oil can be operated under such a high- radiation environment over the lifetime of CMS. Non-oiled RPCs may be one of the options since phenolic or melamine-coated bakelite is chemically stabler than linseed oil. We have constructed oiled and non-oiled RPCs at the high eta region of CMS using phenolic bakelite and tested them in the Gamma Irradiation Facility at CERN. While both RPCs show the same characteristics in the efficiency and the strip multiplicity, the non-oiled RPC generates an intrinsic noise rate of 50 Hz/cm**2, compared to only 5 Hz/cm**2 for the oiled RPC, both at 10.0kV which is about 100 V above the 95% knee of the efficiency curve.

  4. Design strength evaluation of RC beams under radiation environments for nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Won-Hee [Institute for Infrastructure Engineering, University of Western Sydney, Penrith, NSW 2751 (Australia); Kwon, Tae-Hyun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Hyeong-Tae [Department of Civil and Environmental Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Park, Kyoungsoo, E-mail: k-park@yonsei.ac.kr [Department of Civil and Environmental Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of)

    2016-05-15

    Neutron irradiation changes the behavior of construction materials such as strength and ductility, and thus structural design equations or their safety margins should accordingly be updated for the design of nuclear power plants (NPP) under irradiation. However, current design codes do not account for such changes in material strength. In this study, a framework is proposed to evaluate the change of the safety margins in design equations of reinforced concrete (RC) flexural members under radiation environments. Material strength changes are approximated on the basis of a collected test database, and the design strengths of RC beams are evaluated considering these material strength changes. The evaluation results demonstrate that the design strength of an under-reinforced flexural member can increase while the design strength of an over-reinforced member generally decreases. These results are associated with the material strength changes such that the yield strength of steel increases and the compressive strength of concrete decreases with the fluence of neutron radiation. Current NPP design codes need to further consider this un-conservative design possibility due to the design strength reduction of flexural members under irradiation.

  5. Hollow core and other infrared waveguides for instrumentation in intense radiation environments.

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, Jonathan David

    2007-11-01

    The purpose of this LDRD was to study the effect of steady-state neutron and gamma irradiation on the transmission of waveguides designed to operate well in the near- or mid-IR region of the electromagnetic spectrum. In this context, near-IR refers to the region between 1.3 {mu}m and about 2.4 {mu}m, and mid-IR between 3.0 {mu}m and 4.5 {mu}m. Such radiation environments could exist in nuclear power plants or nuclear weapons. Pulsed and steady-state radiation effects had been extensively studied on silica-based optical fibers because they have been the most readily available, most widely used in communications and sensing, and the least expensive. However, silica-based fibers do not transmit well beyond about 1.8 {mu}m and they are virtually opaque in the mid-IR. The mid-IR, as defined above, and beyond, is where vibrational spectroscopy is carried out. This type of sensing is one important application of infrared optical fibers.

  6. A Collaborative Model for Ubiquitous Learning Environments

    Science.gov (United States)

    Barbosa, Jorge; Barbosa, Debora; Rabello, Solon

    2016-01-01

    Use of mobile devices and widespread adoption of wireless networks have enabled the emergence of Ubiquitous Computing. Application of this technology to improving education strategies gave rise to Ubiquitous e-Learning, also known as Ubiquitous Learning. There are several approaches to organizing ubiquitous learning environments, but most of them…

  7. A Collaborative Model for Ubiquitous Learning Environments

    Science.gov (United States)

    Barbosa, Jorge; Barbosa, Debora; Rabello, Solon

    2016-01-01

    Use of mobile devices and widespread adoption of wireless networks have enabled the emergence of Ubiquitous Computing. Application of this technology to improving education strategies gave rise to Ubiquitous e-Learning, also known as Ubiquitous Learning. There are several approaches to organizing ubiquitous learning environments, but most of them…

  8. A biokinetic model for zinc for use in radiation protection

    Energy Technology Data Exchange (ETDEWEB)

    Leggett, Richard Wayne [ORNL

    2012-01-01

    The physiology of the essential trace element zinc has been studied extensively in human subjects using kinetic analysis of time-dependent measurements of administered zinc tracers. A number of biokinetic models describing zinc exchange between plasma and tissues and loss of systemic zinc in excreta have been developed from the derived data. More rudimentary biokinetic models for zinc have been developed to estimate radiation doses from internally deposited radioisotopes of zinc. The latter models are designed to provide broadly accurate estimates of cumulative decays of zinc radioisotopes in tissues and are not intended as realistic descriptions of the directions of movement of zinc in the body. This paper reviews biokinetic data for zinc and proposes a physiologically meaningful biokinetic model for systemic zinc for use in radiation protection. The proposed model bears some resemblance to zinc models developed in physiological studies but depicts a finer division of systemic zinc and is based on a broader spectrum of data than previous models. The proposed model and current radiation protection model for zinc yield broadly similar estimates of effective dose from internally deposited radioisotopes of zinc but substantially different dose estimates for several individual tissues, particularly the liver.

  9. Plasmonic-cavity model for radiating nano-rod antennas

    DEFF Research Database (Denmark)

    Peng, Liang; Mortensen, N. Asger

    2014-01-01

    In this paper, we propose the analytical solution of nano-rod antennas utilizing a cylindrical harmonics expansion. By treating the metallic nano-rods as plasmonic cavities, we derive closed-form expressions for both the internal and the radiated fields, as well as the resonant condition and the ......In this paper, we propose the analytical solution of nano-rod antennas utilizing a cylindrical harmonics expansion. By treating the metallic nano-rods as plasmonic cavities, we derive closed-form expressions for both the internal and the radiated fields, as well as the resonant condition...... and the radiation efficiency. With our theoretical model, we show that besides the plasmonic resonances, efficient radiation takes advantage of (a) rendering a large value of the rods' radius and (b) a central-fed profile, through which the radiation efficiency can reach up to 70% and even higher in a wide...... frequency band. Our theoretical expressions and conclusions are general and pave the way for engineering and further optimization of optical antenna systems and their radiation patterns....

  10. Radiative heating in global climate models

    Energy Technology Data Exchange (ETDEWEB)

    Baer, F.; Arsky, N.; Rocque, K. [Univ. of Maryland, College Park, MD (United States)

    1996-04-01

    LWR algorithms from various GCMs vary significantly from one another for the same clear sky input data. This variability becomes pronounced when clouds are included. We demonstrate this effect by intercomparing the various models` output using observed data including clouds from ARM/CART data taken in Oklahoma.

  11. Radiative transfer model for contaminated rough slabs.

    Science.gov (United States)

    Andrieu, François; Douté, Sylvain; Schmidt, Frédéric; Schmitt, Bernard

    2015-11-01

    We present a semi-analytical model to simulate the bidirectional reflectance distribution function (BRDF) of a rough slab layer containing impurities. This model has been optimized for fast computation in order to analyze massive hyperspectral data by a Bayesian approach. We designed it for planetary surface ice studies but it could be used for other purposes. It estimates the bidirectional reflectance of a rough slab of material containing inclusions, overlaying an optically thick media (semi-infinite media or stratified media, for instance granular material). The inclusions are assumed to be close to spherical and constituted of any type of material other than the ice matrix. It can be any other type of ice, mineral, or even bubbles defined by their optical constants. We assume a low roughness and we consider the geometrical optics conditions. This model is thus applicable for inclusions larger than the considered wavelength. The scattering on the inclusions is assumed to be isotropic. This model has a fast computation implementation and thus is suitable for high-resolution hyperspectral data analysis.

  12. Curve fitting methods for solar radiation data modeling

    Energy Technology Data Exchange (ETDEWEB)

    Karim, Samsul Ariffin Abdul, E-mail: samsul-ariffin@petronas.com.my, E-mail: balbir@petronas.com.my; Singh, Balbir Singh Mahinder, E-mail: samsul-ariffin@petronas.com.my, E-mail: balbir@petronas.com.my [Department of Fundamental and Applied Sciences, Faculty of Sciences and Information Technology, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak Darul Ridzuan (Malaysia)

    2014-10-24

    This paper studies the use of several type of curve fitting method to smooth the global solar radiation data. After the data have been fitted by using curve fitting method, the mathematical model of global solar radiation will be developed. The error measurement was calculated by using goodness-fit statistics such as root mean square error (RMSE) and the value of R{sup 2}. The best fitting methods will be used as a starting point for the construction of mathematical modeling of solar radiation received in Universiti Teknologi PETRONAS (UTP) Malaysia. Numerical results indicated that Gaussian fitting and sine fitting (both with two terms) gives better results as compare with the other fitting methods.

  13. Curve fitting methods for solar radiation data modeling

    Science.gov (United States)

    Karim, Samsul Ariffin Abdul; Singh, Balbir Singh Mahinder

    2014-10-01

    This paper studies the use of several type of curve fitting method to smooth the global solar radiation data. After the data have been fitted by using curve fitting method, the mathematical model of global solar radiation will be developed. The error measurement was calculated by using goodness-fit statistics such as root mean square error (RMSE) and the value of R2. The best fitting methods will be used as a starting point for the construction of mathematical modeling of solar radiation received in Universiti Teknologi PETRONAS (UTP) Malaysia. Numerical results indicated that Gaussian fitting and sine fitting (both with two terms) gives better results as compare with the other fitting methods.

  14. A Comparison of EAST Shock-Tube Radiation Measurements with a New Air Radiation Model

    Science.gov (United States)

    Johnston, Christopher O.

    2008-01-01

    This paper presents a comparison between the recent EAST shock tube radiation measurements (Grinstead et al., AIAA 2008-1244) and the HARA radiation model. The equilibrium and nonequilibrium radiation measurements are studied for conditions relevant to lunar-return shock-layers; specifically shock velocities ranging from 9 to 11 kilometers per second at initial pressures of 0.1 and 0.3 Torr. The simulated shock-tube flow is assumed one-dimensional and is calculated using the LAURA code, while a detailed nonequilibrium radiation prediction is obtained in an uncoupled manner from the HARA code. The measured and predicted intensities are separated into several spectral ranges to isolate significant spectral features, mainly strong atomic line multiplets. The equations and physical data required for the prediction of these strong atomic lines are reviewed and their uncertainties identified. The 700-1020 nm wavelength range, which accounts for roughly 30% of the radiative flux to a peak-heating lunar return shock-layer, is studied in detail and the measurements and predictions are shown to agree within 15% in equilibrium. The plus or minus 1.5% uncertainty on the measured shock velocity is shown to cause up to a plus or minus 30% difference in the predicted radiation. This band of predictions contains the measured values in almost all cases. For the highly nonequilibrium 0.1 Torr cases, the nonequilibrium radiation peaks are under-predicted by about half. This under-prediction is considered acceptable when compared to the order-of-magnitude over-prediction obtained using a Boltzmann population of electronic states. The reasonable comparison in the nonequilibrium regions provides validation for both the non-Boltzmann modeling in HARA and the thermochemical nonequilibrium modeling in LAURA. The N2 (+)(1-) and N2(2+) molecular band systems are studied in the 290 480 nm wavelength range for both equilibrium and nonequilibrium regimes. The non-Boltzmann rate models for these

  15. Turbulence radiation interaction modeling in hydrocarbon pool fire simulations

    Energy Technology Data Exchange (ETDEWEB)

    BURNS,SHAWN P.

    1999-12-01

    The importance of turbulent fluctuations in temperature and species concentration in thermal radiation transport modeling for combustion applications is well accepted by the radiation transport and combustion communities. A number of experimental and theoretical studies over the last twenty years have shown that fluctuations in the temperature and species concentrations may increase the effective emittance of a turbulent flame by as much as 50% to 300% over the value that would be expected from the mean temperatures and concentrations. With the possibility of such a large effect on the principal mode of heat transfer from a fire, it is extremely important for fire modeling efforts that turbulence radiation interaction be well characterized and possible modeling approaches understood. Toward this end, this report seeks to accomplish three goals. First, the principal turbulence radiation interaction closure terms are defined. Second, an order of magnitude analysis is performed to understand the relative importance of the various closure terms. Finally, the state of the art in turbulence radiation interaction closure modeling is reviewed. Hydrocarbon pool fire applications are of particular interest in this report and this is the perspective from which this review proceeds. Experimental and theoretical analysis suggests that, for this type of heavily sooting flame, the turbulent radiation interaction effect is dominated by the nonlinear dependence of the Planck function on the temperature. Additional effects due to the correlation between turbulent fluctuations in the absorptivity and temperature may be small relative to the Planck function effect for heavily sooting flames. This observation is drawn from a number of experimental and theoretical discussions. Nevertheless, additional analysis and data is needed to validate this observation for heavily sooting buoyancy dominated plumes.

  16. Interactive visual intervention planning in particle accelerator environments with ionizing radiation

    CERN Document Server

    Fabry, Thomas

    Radiation is omnipresent. It has many interesting applications: in medicine, where it allows curing and diagnosing patients; in communication, where modern communication systems make use of electromagnetic radiation; and in science, where it is used to discover the structure of materials; to name a few. Physically, radiation is a process in which particles or waves travel through any kind of material, usually air. Radiation can be very energetic, in which case it can break the atoms of ordinary matter (ionization). If this is the case, radiation is called ionizing. It is known that ionizing radiation can be far more harmful to living beings than non-ionizing radiation. In this dissertation, we are concerned with ionizing radiation. Naturally occurring ionizing radiation in the form of radioactivity is a most natural phenomenon. Almost everything is radioactive: there is radiation emerging from the soil, it is in the air, and the whole planet is constantly undergoing streams of energetic cosmic radiation. Sinc...

  17. On competitive Lotka–Volterra model in random environments

    National Research Council Canada - National Science Library

    Zhu, C; Yin, G

    2009-01-01

    Focusing on competitive Lotka-Volterra model in random environments, this paper uses regime-switching diffusions to model the dynamics of the population sizes of n different species in an ecosystem...

  18. nIFTy galaxy cluster simulations - II. Radiative models

    Science.gov (United States)

    Sembolini, Federico; Elahi, Pascal Jahan; Pearce, Frazer R.; Power, Chris; Knebe, Alexander; Kay, Scott T.; Cui, Weiguang; Yepes, Gustavo; Beck, Alexander M.; Borgani, Stefano; Cunnama, Daniel; Davé, Romeel; February, Sean; Huang, Shuiyao; Katz, Neal; McCarthy, Ian G.; Murante, Giuseppe; Newton, Richard D. A.; Perret, Valentin; Puchwein, Ewald; Saro, Alexandro; Schaye, Joop; Teyssier, Romain

    2016-07-01

    We have simulated the formation of a massive galaxy cluster (M_{200}^crit = 1.1 × 1015 h-1 M⊙) in a Λ cold dark matter universe using 10 different codes (RAMSES, 2 incarnations of AREPO and 7 of GADGET), modelling hydrodynamics with full radiative subgrid physics. These codes include smoothed-particle hydrodynamics (SPH), spanning traditional and advanced SPH schemes, adaptive mesh and moving mesh codes. Our goal is to study the consistency between simulated clusters modelled with different radiative physical implementations - such as cooling, star formation and thermal active galactic nucleus (AGN) feedback. We compare images of the cluster at z = 0, global properties such as mass, and radial profiles of various dynamical and thermodynamical quantities. We find that, with respect to non-radiative simulations, dark matter is more centrally concentrated, the extent not simply depending on the presence/absence of AGN feedback. The scatter in global quantities is substantially higher than for non-radiative runs. Intriguingly, adding radiative physics seems to have washed away the marked code-based differences present in the entropy profile seen for non-radiative simulations in Sembolini et al.: radiative physics + classic SPH can produce entropy cores, at least in the case of non cool-core clusters. Furthermore, the inclusion/absence of AGN feedback is not the dividing line -as in the case of describing the stellar content - for whether a code produces an unrealistic temperature inversion and a falling central entropy profile. However, AGN feedback does strongly affect the overall stellar distribution, limiting the effect of overcooling and reducing sensibly the stellar fraction.

  19. Analytical Models for Gravitating Radiating Systems

    Directory of Open Access Journals (Sweden)

    B. P. Brassel

    2015-01-01

    Full Text Available We analyse the gravitational behaviour of a relativistic heat conducting fluid in a shear-free spherically symmetric spacetime. We show that the isotropy of pressure is a consistency condition which realises a second order nonlinear ordinary differential equation with variable coefficients in the gravitational potentials. Several new classes of solutions are found to the governing equation by imposing various forms on one of the potentials. Interestingly, a complex transformation leads to an exact solution with only real metric functions. All solutions are written in terms of elementary functions. We demonstrate graphically that the fluid pressure, energy density, and heat flux are well behaved for the model, and the model is consistent with a core-envelope framework.

  20. Analytical models for gravitating radiating systems

    CERN Document Server

    Brassel, B P; Govender, G

    2015-01-01

    We analyse the gravitational behaviour of a relativistic heat conducting fluid in a shear-free spherically symmetric spacetime. We show that the isotropy of pressure is a consistency condition which realises a second order nonlinear ordinary differential equation with variable coefficients in the gravitational potentials. Several new classes of solutions are found to the governing equation by imposing various forms on one of the potentials. Interestingly, a complex transformation leads to an exact solution with only real metric functions. All solutions are written in terms of elementary functions. We demonstrate graphically that the fluid pressure, energy density and heat flux are well behaved for the model, and the model is consistent with a core-envelope framework.

  1. Radiative Transport Modelling of Thermal Barrier Coatings

    Science.gov (United States)

    2017-03-24

    traveled by signal and reference beam photons) is the result of signal photons travelling a distance L through the sample . Since this distance L is related...performed in both tasks together for convenience . First, we briefly discuss the random walk model, since it is relevant in the discussion on both the...Figure 7, whereby a collinear low coherence beam (shown as a red arrow) is considered to be incident onto the sample at normal incidence to the surface

  2. Automotive Underhood Thermal Management Analysis Using 3-D Coupled Thermal-Hydrodynamic Computer Models: Thermal Radiation Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Pannala, S; D' Azevedo, E; Zacharia, T

    2002-02-26

    The goal of the radiation modeling effort was to develop and implement a radiation algorithm that is fast and accurate for the underhood environment. As part of this CRADA, a net-radiation model was chosen to simulate radiative heat transfer in an underhood of a car. The assumptions (diffuse-gray and uniform radiative properties in each element) reduce the problem tremendously and all the view factors for radiation thermal calculations can be calculated once and for all at the beginning of the simulation. The cost for online integration of heat exchanges due to radiation is found to be less than 15% of the baseline CHAD code and thus very manageable. The off-line view factor calculation is constructed to be very modular and has been completely integrated to read CHAD grid files and the output from this code can be read into the latest version of CHAD. Further integration has to be performed to accomplish the same with STAR-CD. The main outcome of this effort is to obtain a highly scalable and portable simulation capability to model view factors for underhood environment (for e.g. a view factor calculation which took 14 hours on a single processor only took 14 minutes on 64 processors). The code has also been validated using a simple test case where analytical solutions are available. This simulation capability gives underhood designers in the automotive companies the ability to account for thermal radiation - which usually is critical in the underhood environment and also turns out to be one of the most computationally expensive components of underhood simulations. This report starts off with the original work plan as elucidated in the proposal in section B. This is followed by Technical work plan to accomplish the goals of the project in section C. In section D, background to the current work is provided with references to the previous efforts this project leverages on. The results are discussed in section 1E. This report ends with conclusions and future scope of

  3. Impacts of radiation exposure on the experimental microbial ecosystem: a particle-based model simulation approach

    Energy Technology Data Exchange (ETDEWEB)

    Doi, M.; Tanaka, N.; Fuma, S.; Kawabata, Z.

    2004-07-01

    Well-designed experimental model ecosystem could be a simple reference of the actual environment and complex ecological systems. For ecological toxicity test of radiation and other environmental toxicants, we investigated and aquatic microbial ecosystem (closed microcosm) in the test tube with initial substrates,autotroph flagellate algae (Euglena, G.), heterotroph ciliate protozoa (Tetrahymena T.) and saprotroph bacteria (E, coli). These species organizes by itself to construct the ecological system, that keeps the sustainable population dynamics for more than 2 years after inoculation only by adding light diurnally and controlling temperature at 25 degree Celsius. Objective of the study is to develop the particle-based computer simulation by reviewing interactions among microbes and environment, and analyze the ecological toxicities of radiation on the microcosm by replicating experimental results in the computer simulation. (Author) 14 refs.

  4. Modeling the survivability of brucella to exposure of Ultraviolet radiation and temperature

    Science.gov (United States)

    Howe, R.

    Accumulated summation of daily Ultra Violet-B (UV-B = 290? to 320 ? ) data? from The USDA Ultraviolet Radiation Monitoring Program show good correlation (R^2 = 77%) with daily temperature data during the five month period from February through June, 1998. Exposure of disease organisms, such as brucella to the effects of accumulated UV-B radiation, can be modeled for a 5 month period from February through June, 1998. Estimates of a lethal dosage for brucell of UV-B in the environment is dependent on minimum/maximum temperature and Solar Zenith Angle for the time period. The accumulated increase in temperature over this period also effects the decomposition of an aborted fetus containing brucella. Decomposition begins at some minimum daily temperature at 27 to 30 degrees C and peaks at 39 to 40C. It is useful to view the summation of temperature as a threshold for other bacteria growth, so that accumulated temperature greater than some value causes decomposition through competition with other bacteria and brucella die from the accumulated effects of UV-B, temperature and organism competition. Results of a study (Cook 1998) to determine survivability of brucellosis in the environment through exposure of aborted bovine fetuses show no one cause can be attributed to death of the disease agent. The combination of daily increase in temperature and accumulated UV-B radiation reveal an inverse correlation to survivability data and can be modeled as an indicator of brucella survivability in the environment in arid regions.

  5. Modeling of the Radiation Belt Dynamics During the Two Largest Geomagnetic Storms of Solar Cycle 24

    Science.gov (United States)

    Zheng, Y.; Rastaetter, L.; Kuznetsova, M. M.

    2016-12-01

    In this paper, radiation belt response to the two largest geomagnetic storms of Solar Cycle 24 (17 March 2015 and the 22 June 2015) is investigated in detail. Even though both storms are primarily CME driven, each has its own complexities [Liu et al., 2015, Kataoka et al., 2015]. Using the CCMC's run-on-request system, modeling results using the RBE (Radiation Belt Environment) model within the SWMF (Space Weather Modeling Framework) and the RBE model coupled with the SWMF and RCM (Rice Convection Model, which takes the ring current's contribution into consideration) will be examined. Comparative and comprehensive analyses of the same event from two different models and of two events from the same model/model suite will be provided. Focus will be specially given to impacts of different solar wind drivers on radiation belt dynamics and to the coupling and interactions of different plasma populations/physical processes within the region. Liu, Ying D., H. Hu, R. Wang, Z. Yang, B., Zhu, Y. A., Liu, J. G. Luhmann, J. D. Richardson (2015), Plasma and Magnetic Field Characteristics of Solar Coronal Mass Ejections in Relation to Geomagnetic Storm Intensity and Variability, The Astrophysical Journal Letters, Volume 809, Issue 2, article id. L34, 6 pp. doi:10.1088/2041-8205/809/2/L34. Kataoka, R., D. Shiota, E. Kilpua, and K. Keika (2015), Pileup accident hypothesis of magnetic storm on 17 March 2015, Geophys. Res. Lett., 42, 5155-5161, doi:10.1002/2015GL064816.

  6. Radiative striped wind model for gamma-ray bursts

    Science.gov (United States)

    Bégué, D.; Pe'er, A.; Lyubarsky, Y.

    2017-01-01

    In this paper we revisit the striped wind model in which the wind is accelerated by magnetic reconnection. In our treatment, radiation is included as an independent component, and two scenarios are considered. In the first one, radiation cannot stream efficiently through the reconnection layer, while the second scenario assumes that radiation is homogeneous in the striped wind. We show how these two assumptions affect the dynamics. In particular, we find that the asymptotic radial evolution of the Lorentz factor is not strongly modified whether radiation can stream through the reconnection layer or not. On the other hand, we show that the width, density and temperature of the reconnection layer are strongly dependent on these assumptions. We then apply the model to the gamma-ray burst context and find that photons cannot diffuse efficiently through the reconnection layer below radius r_D^{Δ } ˜ 10^{10.5} cm, which is about an order of magnitude below the photospheric radius. Above r_D^{Δ }, the dynamics asymptotes to the solution of the scenario in which radiation can stream through the reconnection layer. As a result, the density of the current sheet increases sharply, providing efficient photon production by the Bremsstrahlung process which could have profound influence on the emerging spectrum. This effect might provide a solution to the soft photon problem in GRBs.

  7. Soil-Vegetation-Atmosphere Radiative Transfer Model in Microwave Region

    Institute of Scientific and Technical Information of China (English)

    JIA Yuanyuan; LI Zhaoliang

    2008-01-01

    The radiative transfer is one of the significant theories that describe the processes of scattering,emission,and absorption of electromagnetic radiant intensity through scattering medium.It is the basis of the study on the quantitative remote sensing.In this paper,the radiative characteristics of soil,vegetation,and atmosphere were described respectively.The numerical solution of radiative transfer was accomplished by Successive Orders of Scattering (SOS).A radiative transfer model for simulating microwave brightness temperature over land surfaces was constructed,designed,and implemented.Analyzing the database generated from soil-vegetation-atmosphere radiative transfer model under Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) configuration showed that the atmospheric effects on microwave brightness temperature should not be neglected,particularly for higher frequency,and can be parameterized.At the same time,the relationship between the emissivities of the different channels was developed.The study results will promote the development of algorithm to retrieve geophysical parameters from microwave remotely sensed data.

  8. Nuclear model calculations and their role in space radiation research

    Science.gov (United States)

    Townsend, L. W.; Cucinotta, F. A.; Heilbronn, L. H.

    2002-01-01

    Proper assessments of spacecraft shielding requirements and concomitant estimates of risk to spacecraft crews from energetic space radiation requires accurate, quantitative methods of characterizing the compositional changes in these radiation fields as they pass through thick absorbers. These quantitative methods are also needed for characterizing accelerator beams used in space radiobiology studies. Because of the impracticality/impossibility of measuring these altered radiation fields inside critical internal body organs of biological test specimens and humans, computational methods rather than direct measurements must be used. Since composition changes in the fields arise from nuclear interaction processes (elastic, inelastic and breakup), knowledge of the appropriate cross sections and spectra must be available. Experiments alone cannot provide the necessary cross section and secondary particle (neutron and charged particle) spectral data because of the large number of nuclear species and wide range of energies involved in space radiation research. Hence, nuclear models are needed. In this paper current methods of predicting total and absorption cross sections and secondary particle (neutrons and ions) yields and spectra for space radiation protection analyses are reviewed. Model shortcomings are discussed and future needs presented. c2002 COSPAR. Published by Elsevier Science Ltd. All right reserved.

  9. Updated measurements from CREAM & CREDO & implications for environment & shielding models.

    Science.gov (United States)

    Dyer, C S; Truscott, P R; Peerless, C L; Watson, C J; Evans, H E; Knight, P; Cosby, M; Underwood, C; Cousins, T; Noulty, R

    1998-06-01

    Flight data obtained between 1995 and 1997 from the Cosmic Radiation Environment Monitors CREAM & CREDO carried on UoSat-3, Space Shuttle, STRV-1a (Space Technology Research Vehicle) and APEX (Advanced Photovoltaic and Electronics Experiment Spacecraft) have been added to the dataset affording coverage since 1990. The modulation of cosmic rays and evolution of the South Atlantic Anomaly are observed, the former comprising a factor three increase at high latitudes and the latter a general increase accompanied by a westward drift. Comparison of particle fluxes and linear energy transfer spectra is made with improved environment & radiation transport calculations which account for shield distributions and secondary particles. While there is an encouraging convergence between predictions and observations, significant improvements are still required, particularly in the treatrnent of locally produced secondary particles.

  10. Technical Evaluation of the NASA Model for Cancer Risk to Astronauts Due to Space Radiation

    Science.gov (United States)

    2012-01-01

    At the request of NASA, the National Research Council's (NRC's) Committee for Evaluation of Space Radiation Cancer Risk Model reviewed a number of changes that NASA proposes to make to its model for estimating the risk of radiation-induced cancer in astronauts. The NASA model in current use was last updated in 2005, and the proposed model would incorporate recent research directed at improving the quantification and understanding of the health risks posed by the space radiation environment. NASA's proposed model is defined by the 2011 NASA report Space Radiation Cancer Risk Projections and Uncertainties 2010 (Cucinotta et al., 2011). The committee's evaluation is based primarily on this source, which is referred to hereafter as the 2011 NASA report, with mention of specific sections or tables cited more formally as Cucinotta et al. (2011). The overall process for estimating cancer risks due to low linear energy transfer (LET) radiation exposure has been fully described in reports by a number of organizations. They include, more recently: (1) The "BEIR VII Phase 2" report from the NRC's Committee on Biological Effects of Ionizing Radiation (BEIR) (NRC, 2006); (2) Studies of Radiation and Cancer from the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR, 2006), (3) The 2007 Recommendations of the International Commission on Radiological Protection (ICRP), ICRP Publication 103 (ICRP, 2007); and (4) The Environmental Protection Agency s (EPA s) report EPA Radiogenic Cancer Risk Models and Projections for the U.S. Population (EPA, 2011). The approaches described in the reports from all of these expert groups are quite similar. NASA's proposed space radiation cancer risk assessment model calculates, as its main output, age- and gender-specific risk of exposure-induced death (REID) for use in the estimation of mission and astronaut-specific cancer risk. The model also calculates the associated uncertainties in REID. The general approach for

  11. Technical Evaluation of the NASA Model for Cancer Risk to Astronauts Due to Space Radiation

    Science.gov (United States)

    2012-01-01

    At the request of NASA, the National Research Council's (NRC's) Committee for Evaluation of Space Radiation Cancer Risk Model reviewed a number of changes that NASA proposes to make to its model for estimating the risk of radiation-induced cancer in astronauts. The NASA model in current use was last updated in 2005, and the proposed model would incorporate recent research directed at improving the quantification and understanding of the health risks posed by the space radiation environment. NASA's proposed model is defined by the 2011 NASA report Space Radiation Cancer Risk Projections and Uncertainties 2010 (Cucinotta et al., 2011). The committee's evaluation is based primarily on this source, which is referred to hereafter as the 2011 NASA report, with mention of specific sections or tables cited more formally as Cucinotta et al. (2011). The overall process for estimating cancer risks due to low linear energy transfer (LET) radiation exposure has been fully described in reports by a number of organizations. They include, more recently: (1) The "BEIR VII Phase 2" report from the NRC's Committee on Biological Effects of Ionizing Radiation (BEIR) (NRC, 2006); (2) Studies of Radiation and Cancer from the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR, 2006), (3) The 2007 Recommendations of the International Commission on Radiological Protection (ICRP), ICRP Publication 103 (ICRP, 2007); and (4) The Environmental Protection Agency s (EPA s) report EPA Radiogenic Cancer Risk Models and Projections for the U.S. Population (EPA, 2011). The approaches described in the reports from all of these expert groups are quite similar. NASA's proposed space radiation cancer risk assessment model calculates, as its main output, age- and gender-specific risk of exposure-induced death (REID) for use in the estimation of mission and astronaut-specific cancer risk. The model also calculates the associated uncertainties in REID. The general approach for

  12. Radiation therapy: model standards for determination of need

    Energy Technology Data Exchange (ETDEWEB)

    Lagasse, L.G.; Devins, T.B.

    1982-03-01

    Contents: Health planning process; Health care requirements (model for projecting need for megavoltage radiation therapy); Operational objectives (manpower, megavoltage therapy and treatment planning equipment, support services, management and evaluation of patient care, organization and administration); Compliance with other standards imposed by law; Financial feasibility and capability; Reasonableness of expenditures and costs; Relative merit; Environmental impact.

  13. Radiative breaking of conformal symmetry in the Standard Model

    Science.gov (United States)

    Arbuzov, A. B.; Nazmitdinov, R. G.; Pavlov, A. E.; Pervushin, V. N.; Zakharov, A. F.

    2016-02-01

    Radiative mechanism of conformal symmetry breaking in a comformal-invariant version of the Standard Model is considered. The Coleman-Weinberg mechanism of dimensional transmutation in this system gives rise to finite vacuum expectation values and, consequently, masses of scalar and spinor fields. A natural bootstrap between the energy scales of the top quark and Higgs boson is suggested.

  14. The MAPPINGS III Library of Fast Radiative Shock Models

    CERN Document Server

    Allen, Mark G; Dopita, Michael A; Sutherland, Ralph S; Kewley, Lisa J

    2008-01-01

    We present a new library of fully-radiative shock models calculated with the MAPPINGS III shock and photoionization code. The library consists of grids of models with shock velocities in the range v=100-1000 km/s and magnetic parameters B/sqrt(n) of 10^-4 - 10 muG cm^(3/2) for five different atomic abundance sets, and for a pre-shock density of 1.0 cm^(-3). Additionally, Solar abundance model grids have been calculated for densities of 0.01, 0.1, 10, 100, and 1000 cm^(-3) with the same range in v and B/sqrt(n). Each model includes components of both the radiative shock and its photoionized precursor, ionized by the EUV and soft X-ray radiation generated in the radiative gas. We present the details of the ionization structure, the column densities, and the luminosities of the shock and its precursor. Emission line ratio predictions are separately given for the shock and its precursor as well as for the composite shock+precursor structure to facilitate comparison with observations in cases where the shock and i...

  15. nIFTy galaxy cluster simulations II: radiative models

    CSIR Research Space (South Africa)

    Sembolini, F

    2016-04-01

    Full Text Available We have simulated the formation of a massive galaxy cluster (M(supcrit)(sub200) = 1.1×10(sup15)h(sup-1)M) in a CDM universe using 10 different codes (RAMSES, 2 incarnations of AREPO and 7 of GADGET), modeling hydrodynamics with full radiative...

  16. Modelling of UV radiation variations at different time scales

    Directory of Open Access Journals (Sweden)

    J. L. Borkowski

    2008-03-01

    Full Text Available Solar UV radiation variability in the period 1976–2006 is discussed with respect to the relative changes in the solar global radiation, ozone content, and cloudiness. All the variables were decomposed into separate components, representing variations of different time scales, using wavelet multi-resolution decomposition. The response of the UV radiation to the changes in the solar global radiation, ozone content, and cloudiness depends on the time scale, therefore, it seems reasonable to model separately the relation between UV and explanatory variables at different time scales. The wavelet components of the UV series are modelled and summed to obtain the fit of observed series. The results show that the coarser time scale components can be modelled with greater accuracy than fine scale components and the fitted values calculated by this method are in better agreement with observed values than values calculated by the regression method, in which variables were not decomposed. The residual standard error in the case of modelling with the use of wavelets is reduced by 14% in comparison to the regression method without decomposition.

  17. Unification of gauge couplings in radiative neutrino mass models

    DEFF Research Database (Denmark)

    Hagedorn, Claudia; Ohlsson, Tommy; Riad, Stella

    2016-01-01

    We investigate the possibility of gauge coupling unification in various radiative neutrino mass models, which generate neutrino masses at one- and/or two-loop level. Renormalization group running of gauge couplings is performed analytically and numerically at one- and two-loop order, respectively...

  18. Fast and simple model for atmospheric radiative transfer

    NARCIS (Netherlands)

    Seidel, F.C.; Kokhanovsky, A.A.; Schaepman, M.E.

    2010-01-01

    Radiative transfer models (RTMs) are of utmost importance for quantitative remote sensing, especially for compensating atmospheric perturbation. A persistent trade-off exists between approaches that prefer accuracy at the cost of computational complexity, versus those favouring simplicity at the cos

  19. Radiative decays of mesons in the NJL model

    CERN Document Server

    Epele, L N; Dumm, D G; Grunfeld, A G

    2001-01-01

    We revisit the theoretical predictions for anomalous radiative decays of pseudoscalar and vector mesons. Our analysis is performed in the framework of the Nambu-Jona-Lasinio model, introducing adequate parameters to account for the breakdown of chiral symmetry. The results are comparable with those obtained in previous approaches.

  20. A Space Radiation Test Model Study

    Science.gov (United States)

    1989-02-17

    approxiniationis fi iso - the course of the ssork. tit, other criterion was applied to the latirig the dominant contributions to the right-hand side of...these Iso end gics (t 17, ; .i rli rlc population ire assUrnd sufficietitv issues, at discussion oif eachi is necessary at the outset high rhir i7...Lopez, J. Geophys. Res., 92, 13485 , 1987. B-16 GEOPHYSICAL RESEARCH LETTERS, VOL. 14, NO. 11, PACES 1166-1169, NDVEM13ER 1981 A NONLINEAR MODEL OF WAVE

  1. Pharmacological doses of daily ascorbate protect tumors from radiation damage after a single dose of radiation in an intracranial mouse glioma model.

    Science.gov (United States)

    Grasso, Carole; Fabre, Marie-Sophie; Collis, Sarah V; Castro, M Leticia; Field, Cameron S; Schleich, Nanette; McConnell, Melanie J; Herst, Patries M

    2014-01-01

    Pharmacological ascorbate is currently used as an anti-cancer treatment, potentially in combination with radiation therapy, by integrative medicine practitioners. In the acidic, metal-rich tumor environment, ascorbate acts as a pro-oxidant, with a mode of action similar to that of ionizing radiation; both treatments kill cells predominantly by free radical-mediated DNA damage. The brain tumor, glioblastoma multiforme (GBM), is very resistant to radiation; radiosensitizing GBM cells will improve survival of GBM patients. Here, we demonstrate that a single fraction (6 Gy) of radiation combined with a 1 h exposure to ascorbate (5 mM) sensitized murine glioma GL261 cells to radiation in survival and colony-forming assays in vitro. In addition, we report the effect of a single fraction (4.5 Gy) of whole brain radiation combined with daily intraperitoneal injections of ascorbate (1 mg/kg) in an intracranial GL261 glioma mouse model. Tumor-bearing C57BL/6 mice were divided into four groups: one group received a single dose of 4.5 Gy to the brain 8 days after tumor implantation, a second group received daily intraperitoneal injections of ascorbate (day 8-45) after implantation, a third group received both treatments and a fourth control group received no treatment. While radiation delayed tumor progression, intraperitoneal ascorbate alone had no effect on tumor progression. Tumor progression was faster in tumor-bearing mice treated with radiation and daily ascorbate than in those treated with radiation alone. Histological analysis showed less necrosis in tumors treated with both radiation and ascorbate, consistent with a radio-protective effect of ascorbate in vivo. Discrepancies between our in vitro and in vivo results may be explained by differences in the tumor microenvironment, which determines whether ascorbate remains outside the cell, acting as