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Sample records for mcnp nova aproximacao

  1. MCNP and GADRAS Comparisons

    SciTech Connect

    Klasky, Marc Louis; Myers, Steven Charles; James, Michael R.

    2016-04-19

    To facilitate the timely execution of System Threat Reviews (STRs) for DNDO, and also to develop a methodology for performing STRs, LANL performed comparisons of several radiation transport codes (MCNP, GADRAS, and Gamma-Designer) that have been previously utilized to compute radiation signatures. While each of these codes has strengths, it is of paramount interest to determine the limitations of each of the respective codes and also to identify the most time efficient means by which to produce computational results, given the large number of parametric cases that are anticipated in performing STR's. These comparisons serve to identify regions of applicabilitymore » for each code and provide estimates of uncertainty that may be anticipated. Furthermore, while performing these comparisons, examination of the sensitivity of the results to modeling assumptions was also examined. These investigations serve to enable the creation of the LANL methodology for performing STRs. Given the wide variety of radiation test sources, scenarios, and detectors, LANL calculated comparisons of the following parameters: decay data, multiplicity, device (n,γ) leakages, and radiation transport through representative scenes and shielding. This investigation was performed to understand potential limitations utilizing specific codes for different aspects of the STR challenges.« less

  2. Recurrent novae

    NASA Technical Reports Server (NTRS)

    Hack, Margherita; Selvelli, Pierluigi

    1993-01-01

    Recurrent novae seem to be a rather inhomogeneous group: T CrB is a binary with a M III companion; U Sco probably has a late dwarf as companion. Three are fast novae; two are slow novae. Some of them appear to have normal chemical composition; others may present He and CNO excess. Some present a mass-loss that is lower by two orders of magnitude than classical novae. However, our sample is too small for saying whether there are several classes of recurrent novae, which may be related to the various classes of classical novae, or whether the low mass-loss is a general property of the class or just a peculiarity of one member of the larger class of classical novae and recurrent novae.

  3. Nova remnants

    NASA Astrophysics Data System (ADS)

    Warner, B.

    1985-06-01

    The brightest nova remnants and nova-like variables (which are possible candidates for membership of the class of nova remnants) are reviewed. Several nova remnants show multiple periodicities: V603 Aql, HR Del, CP Pup and possibly V1500 Cyg have differing photometric and spectroscopic periods. The cause of this is not known, but there is a similarity with the superhump phenomenon in SU UMa stars. The RR Pic shows changes in structure, 50 yr after the outburst.

  4. Dwarf novae

    NASA Technical Reports Server (NTRS)

    Ladous, Constanze

    1993-01-01

    Dwarf novae are defined on grounds of their semi-regular brightness variations of some two to five magnitudes on time scales of typically 10 to 100 days. Historically several different classification schemes have been used. Today, dwarf novae are divided into three sub-classes: the U Geminorum stars, the SU Ursae Majoris stars, and the Z Camelopardalis stars. Outbursts of dwarf novae occur at semi-periodic intervals of time, typically every 10 to 100 days; amplitudes range from typically 2 to 5 mag. Within certain limits values are characteristic for each object. Relations between the outburst amplitude, or the total energy released during outburst, and the recurrence time have been found, as well as relations between the orbital period and the outburst decay time, the absolute magnitude during outburst maximum, and the widths of long and short outbursts, respectively. Some dwarf novae are known to have suspended their normal outburst activity altogether for a while. They later resumed it without having undergone any observable changes. The optical colors of dwarf novae all are quite similar during outburst, considerably bluer than during the quiescent state. During the outburst cycle, characteristic loops in the two color diagram are performed. At a time resolution on the order of minutes, strictly periodic photometric changes due to orbital motion become visible in the light curves of dwarf novae. These are characteristic for each system. Remarkably little is known about orbital variations during the course of an outburst. On time-scales of minutes and seconds, further more or less periodic types of variability are seen in dwarf novae. Appreciable flux is emitted by dwarf novae at all wavelengths from the X-rays to the longest IR wavelengths, and in some cases even in the radio. Most dwarf novae exhibit strong emission line spectra in the optical and UV during quiescence, although some have only very weak emissions in the optical and/or weak absorptions at UV

  5. MCNP6 Fission Multiplicity with FMULT Card

    SciTech Connect

    Wilcox, Trevor; Fensin, Michael Lorne; Hendricks, John S.

    2012-06-18

    With the merger of MCNPX and MCNP5 into MCNP6, MCNP6 now provides all the capabilities of both codes allowing the user to access all the fission multiplicity data sets. Detailed in this paper is: (1) the new FMULT card capabilities for accessing these different data sets; (2) benchmark calculations, as compared to experiment, detailing the results of selecting these separate data sets for thermal neutron induced fission on U-235.

  6. MatMCNP V. 3.0

    SciTech Connect

    2015-10-19

    A code for generating MCNP material cards (MatMCNP) has been written and verified for naturally occurring, stable isotopes. The program allows for material specification as either atomic or weight percent (fractions). MatMCNP also permits the specification of enriched lithium, boron, and/or uranium. In addition to producing the material cards for MCNP, the code calculates the atomic (or number) density in atoms/barn-cm as well as the multiplier that should be used to convert neutron and gamma fluences into dose in the material specified.

  7. How to Build MCNP 6.2

    SciTech Connect

    Bull, Jeffrey S.

    2017-11-13

    This presentation describes how to build MCNP 6.2. MCNP®* 6.2 can be compiled on Macs, PCs, and most Linux systems. It can also be built for parallel execution using both OpenMP and Messing Passing Interface (MPI) methods. MCNP6 requires Fortran, C, and C++ compilers to build the code.

  8. Status Report on the MCNP 2020 Initiative

    SciTech Connect

    Brown, Forrest B.; Rising, Michael Evan

    2017-10-02

    The discussion below provides a status report on the MCNP 2020 initiative. It includes discussion of the history of MCNP 2020, accomplishments during 2013-17, priorities for near-term development, other related efforts, a brief summary, and a list of references for the plans and work accomplished.

  9. MCNP Version 6.2 Release Notes

    SciTech Connect

    Werner, Christopher John; Bull, Jeffrey S.; Solomon, C. J.

    2018-02-05

    Monte Carlo N-Particle or MCNP ® is a general-purpose Monte Carlo radiation-transport code designed to track many particle types over broad ranges of energies. This MCNP Version 6.2 follows the MCNP6.1.1 beta version and has been released in order to provide the radiation transport community with the latest feature developments and bug fixes for MCNP. Since the last release of MCNP major work has been conducted to improve the code base, add features, and provide tools to facilitate ease of use of MCNP version 6.2 as well as the analysis of results. These release notes serve as a general guidemore » for the new/improved physics, source, data, tallies, unstructured mesh, code enhancements and tools. For more detailed information on each of the topics, please refer to the appropriate references or the user manual which can be found at http://mcnp.lanl.gov. This release of MCNP version 6.2 contains 39 new features in addition to 172 bug fixes and code enhancements. There are still some 33 known issues the user should familiarize themselves with (see Appendix).« less

  10. MatMCNP: A Code for Producing Material Cards for MCNP

    SciTech Connect

    DePriest, Kendall Russell; Saavedra, Karen C.

    2014-09-01

    A code for generating MCNP material cards (MatMCNP) has been written and verified for naturally occurring, stable isotopes. The program allows for material specification as either atomic or weight percent (fractions). MatMCNP also permits the specification of enriched lithium, boron, and/or uranium. In addition to producing the material cards for MCNP, the code calculates the atomic (or number) density in atoms/barn-cm as well as the multiplier that should be used to convert neutron and gamma fluences into dose in the material specified.

  11. Magnetic novae

    NASA Astrophysics Data System (ADS)

    Zemko, Polina; Orio, Marina

    2016-07-01

    We present the results of optical and X-ray observations of two quiescent novae, V2491 Cyg and V4743 Sgr. Our observations suggest the intriguing possibility of localization of hydrogen burning in magnetic novae, in which accretion is streamed to the polar caps. V2491 Cyg was observed with Suzaku more than 2 years after the outburst and V4743 Sgr was observed with XMM Newton 2 and 3.5 years after maximum. In the framework of a monitoring program of novae previously observed as super soft X-ray sources we also obtained optical spectra of V4743 Sgr with the SALT telescope 11.5 years after the eruption and of V2491 Cyg with the 6m Big Azimutal Telescope 4 and 7 years post-outburst. In order to confirm the possible white dwarf spin period of V2491 Cyg measured in the Suzaku observations we obtained photometric data using the 90cm WIYN telescope at Kitt Peak and the 1.2 m telescope in Crimea. We found that V4743 Sgr is an intermediate polar (IP) and V2491 Cyg is a strong IP candidate. Both novae show modulation of their X-ray light curves and have X-ray spectra typical of IPs. The Suzaku and XMM Newton exposures revealed that the spectra of both novae have a very soft blackbody-like component with a temperature close to that of the hydrogen burning white dwarfs in their SSS phases, but with flux by at least two orders of magnitude lower, implying a possible shrinking of emitting regions in the thin atmosphere that is heated by nuclear burning underneath it. In quiescent IPs, independently of the burning, an ultrasoft X-ray flux component originates at times in the polar regions irradiated by the accretion column, but the soft component of V4743 Sgr disappeared in 2006, indicating that the origin may be different from accretion. We suggest it may have been due to an atmospheric temperature gradient on the white dwarf surface, or to continuing localized thermonuclear burning at the bottom of the envelope, before complete turn-off. The optical spectra of V2491 Cyg and V

  12. Firework Nova

    NASA Image and Video Library

    2017-12-08

    Nova Stars are essentially giant fusion reactions occurring in the vacuum of space. Because stars have so much mass, they possess powerful gravitational force—but they don’t collapse because of the outward force generated by nuclear fusion, continually converting hydrogen atoms to helium. Sometimes stars begin orbiting each other, forming a binary star system. Typically this involves a white dwarf star and a red giant. Orbiting the red giant like a moon, the dwarf star rips matter from its companion until it essentially gags on the excess, coughing hot gas and radiation into space. This dramatic phenomenon is relatively common, and the white dwarf is not destroyed in the resulting nova. To learn more about x-ray emissions, read about NASA’s Chandra mission: www.nasa.gov/mission_pages/chandra/main/ --- Original caption: In Hollywood blockbusters, explosions are often among the stars of the show. In space, explosions of actual stars are a focus for scientists who hope to better understand their births, lives, and deaths and how they interact with their surroundings. Using NASA’s Chandra X-ray Observatory, astronomers have studied one particular explosion that may provide clues to the dynamics of other, much larger stellar eruptions. A team of researchers pointed the telescope at GK Persei, an object that became a sensation in the astronomical world in 1901 when it suddenly appeared as one of the brightest stars in the sky for a few days, before gradually fading away in brightness. Today, astronomers cite GK Persei as an example of a “classical nova,” an outburst produced by a thermonuclear explosion on the surface of a white dwarf star, the dense remnant of a Sun-like star. Read Full Article: www.nasa.gov/mission_pages/chandra/mini-supernova-explosi... NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a

  13. Firework Nova

    NASA Image and Video Library

    2015-07-02

    In Hollywood blockbusters, explosions are often among the stars of the show. In space, explosions of actual stars are a focus for scientists who hope to better understand their births, lives, and deaths and how they interact with their surroundings. Using NASA’s Chandra X-ray Observatory, astronomers have studied one particular explosion that may provide clues to the dynamics of other, much larger stellar eruptions. A team of researchers pointed the telescope at GK Persei, an object that became a sensation in the astronomical world in 1901 when it suddenly appeared as one of the brightest stars in the sky for a few days, before gradually fading away in brightness. Today, astronomers cite GK Persei as an example of a “classical nova,” an outburst produced by a thermonuclear explosion on the surface of a white dwarf star, the dense remnant of a Sun-like star.

  14. Classical novae and recurrent novae: General properties

    NASA Technical Reports Server (NTRS)

    Hack, Margherita; Selvelli, Pierluigi; Duerbeck, Hilmar W.

    1993-01-01

    We describe the observable characteristics of classical novae and recurrent novae obtained by different techniques (photometry, spectroscopy, and imaging) in all the available spectral ranges. We consider the three stages in the life of a nova: quiescence (pre- and post-outburst), outburst, final decline and nebular phase. We describe the photometric properties during the quiescent phase. We describe the photometric properties during outburst, the classification according the rate of decline (magnitudes per day), which permits us to define very fast, fast, intermediate, slow, and very slow novae and the correlation between luminosity and speed class. We report the scanty data on the spectra of the few known prenovae and those on the spectra of old novae and those of dwarf novae and nova-like, which, however, are almost undistinguishable. We describe the typical spectra appearing from the beginning of the outburst, just before maximum, up to the nebular phase and the correlation between spectral type at maximum, expansional velocity, and speed class of the nova. We report the existing infrared observations, which permit us to explain some of the characteristics of the outburst light curve, and give evidence of the formation of a dust shell in slow and intermediate novae (with the important exception of the very slow nova HR Del 1967) and its absence or quasi-absence in fast novae. The ultraviolet and X-ray observations are described. The X ray observations of novae, mainly from the two satellites EINSTEIN and EXOSAT, are reported. Observations of the final decline and of the envelopes appearing several months after outburst are also reported.

  15. Typical examples of classical novae

    NASA Technical Reports Server (NTRS)

    Hack, Margherita; Selvelli, Pierluigi; Bianchini, Antonio; Duerbeck, Hilmar W.

    1993-01-01

    Because of the very complicated individualistic behavior of each nova, we think it necessary to review the observations of a few well-observed individuals. We have selected a few objects of different speed classes, which have been extensively observed. They are: V1500 Cygni 1975, a very fast nova; V603 Aql 1918, fast nova; CP Pup 1942, fast nova; GK Per 1901, fast nova; V 1668 Cyg 1979, moderately fast nova; FH Ser 1970, slow nova; DQ Her 1934, slow nova; T Aur 1891, slow nova; RR Pic 1925, slow nova; and HR Del 1967, very slow nova.

  16. Typical examples of classical novae

    NASA Astrophysics Data System (ADS)

    Hack, Margherita; Selvelli, Pierluigi; Bianchini, Antonio; Duerbeck, Hilmar W.

    1993-09-01

    Because of the very complicated individualistic behavior of each nova, we think it necessary to review the observations of a few well-observed individuals. We have selected a few objects of different speed classes, which have been extensively observed. They are: V1500 Cygni 1975, a very fast nova; V603 Aql 1918, fast nova; CP Pup 1942, fast nova; GK Per 1901, fast nova; V 1668 Cyg 1979, moderately fast nova; FH Ser 1970, slow nova; DQ Her 1934, slow nova; T Aur 1891, slow nova; RR Pic 1925, slow nova; and HR Del 1967, very slow nova.

  17. Using Machine Learning to Predict MCNP Bias

    SciTech Connect

    Grechanuk, Pavel Aleksandrovi

    2018-01-09

    For many real-world applications in radiation transport where simulations are compared to experimental measurements, like in nuclear criticality safety, the bias (simulated - experimental k eff) in the calculation is an extremely important quantity used for code validation. The objective of this project is to accurately predict the bias of MCNP6 [1] criticality calculations using machine learning (ML) algorithms, with the intention of creating a tool that can complement the current nuclear criticality safety methods. In the latest release of MCNP6, the Whisper tool is available for criticality safety analysts and includes a large catalogue of experimental benchmarks, sensitivity profiles,more » and nuclear data covariance matrices. This data, coming from 1100+ benchmark cases, is used in this study of ML algorithms for criticality safety bias predictions.« less

  18. Criticality Calculations with MCNP6 - Practical Lectures

    SciTech Connect

    Brown, Forrest B.; Rising, Michael Evan; Alwin, Jennifer Louise

    2016-11-29

    These slides are used to teach MCNP (Monte Carlo N-Particle) usage to nuclear criticality safety analysts. The following are the lecture topics: course information, introduction, MCNP basics, criticality calculations, advanced geometry, tallies, adjoint-weighted tallies and sensitivities, physics and nuclear data, parameter studies, NCS validation I, NCS validation II, NCS validation III, case study 1 - solution tanks, case study 2 - fuel vault, case study 3 - B&W core, case study 4 - simple TRIGA, case study 5 - fissile mat. vault, criticality accident alarm systems. After completion of this course, you should be able to: Develop an input modelmore » for MCNP; Describe how cross section data impact Monte Carlo and deterministic codes; Describe the importance of validation of computer codes and how it is accomplished; Describe the methodology supporting Monte Carlo codes and deterministic codes; Describe pitfalls of Monte Carlo calculations; Discuss the strengths and weaknesses of Monte Carlo and Discrete Ordinants codes; The diffusion theory model is not strictly valid for treating fissile systems in which neutron absorption, voids, and/or material boundaries are present. In the context of these limitations, identify a fissile system for which a diffusion theory solution would be adequate.« less

  19. Novae as distance indicators

    NASA Technical Reports Server (NTRS)

    Ford, Holland C.; Ciardullo, Robin

    1988-01-01

    Nova shells are characteristically prolate with equatorial bands and polar caps. Failure to account for the geometry can lead to large errors in expansion parallaxes for individual novae. When simple prescriptions are used for deriving expansion parallaxes from an ensemble of randomly oriented prolate spheroids, the average distance will be too small by factors of 10 to 15 percent. The absolute magnitudes of the novae will be underestimated and the resulting distance scale will be too small by the same factors. If observations of partially resolved nova shells select for large inclinations, the systematic error in the resulting distance scale could easily be 20 to 30 percent. Extinction by dust in the bulge of M31 may broaden and shift the intrinsic distribution of maximum nova magnitudes versus decay rates. We investigated this possibility by projecting Arp's and Rosino's novae onto a composite B - 6200A color map of M31's bulge. Thirty two of the 86 novae projected onto a smooth background with no underlying structure due to the presence of a dust cloud along the line of sight. The distribution of maximum magnitudes versus fade rates for these unreddened novae is indistinguishable from the distribution for the entire set of novae. It is concluded that novae suffer very little extinction from the filamentary and patchy distribution of dust seen in the bulge of M31. Time average B and H alpha nova luminosity functions are potentially powerful new ways to use novae as standard candles. Modern CCD observations and the photographic light curves of M31 novae found during the last 60 years were analyzed to show that these functions are power laws. Consequently, unless the eruption times for novae are known, the data cannot be used to obtain distances.

  20. MCNP Output Data Analysis with ROOT (MODAR)

    NASA Astrophysics Data System (ADS)

    Carasco, C.

    2010-06-01

    MCNP Output Data Analysis with ROOT (MODAR) is a tool based on CERN's ROOT software. MODAR has been designed to handle time-energy data issued by MCNP simulations of neutron inspection devices using the associated particle technique. MODAR exploits ROOT's Graphical User Interface and functionalities to visualize and process MCNP simulation results in a fast and user-friendly way. MODAR allows to take into account the detection system time resolution (which is not possible with MCNP) as well as detectors energy response function and counting statistics in a straightforward way. Program summaryProgram title: MODAR Catalogue identifier: AEGA_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEGA_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 155 373 No. of bytes in distributed program, including test data, etc.: 14 815 461 Distribution format: tar.gz Programming language: C++ Computer: Most Unix workstations and PC Operating system: Most Unix systems, Linux and windows, provided the ROOT package has been installed. Examples where tested under Suse Linux and Windows XP. RAM: Depends on the size of the MCNP output file. The example presented in the article, which involves three two-dimensional 139×740 bins histograms, allocates about 60 MB. These data are running under ROOT and include consumption by ROOT itself. Classification: 17.6 External routines: ROOT version 5.24.00 ( http://root.cern.ch/drupal/) Nature of problem: The output of an MCNP simulation is an ASCII file. The data processing is usually performed by copying and pasting the relevant parts of the ASCII file into Microsoft Excel. Such an approach is satisfactory when the quantity of data is small but is not efficient when the size of the simulated data is large, for example when time

  1. MCNP output data analysis with ROOT (MODAR)

    NASA Astrophysics Data System (ADS)

    Carasco, C.

    2010-12-01

    MCNP Output Data Analysis with ROOT (MODAR) is a tool based on CERN's ROOT software. MODAR has been designed to handle time-energy data issued by MCNP simulations of neutron inspection devices using the associated particle technique. MODAR exploits ROOT's Graphical User Interface and functionalities to visualize and process MCNP simulation results in a fast and user-friendly way. MODAR allows to take into account the detection system time resolution (which is not possible with MCNP) as well as detectors energy response function and counting statistics in a straightforward way. New version program summaryProgram title: MODAR Catalogue identifier: AEGA_v1_1 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEGA_v1_1.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 150 927 No. of bytes in distributed program, including test data, etc.: 4 981 633 Distribution format: tar.gz Programming language: C++ Computer: Most Unix workstations and PCs Operating system: Most Unix systems, Linux and windows, provided the ROOT package has been installed. Examples where tested under Suse Linux and Windows XP. RAM: Depends on the size of the MCNP output file. The example presented in the article, which involves three two dimensional 139×740 bins histograms, allocates about 60 MB. These data are running under ROOT and include consumption by ROOT itself. Classification: 17.6 Catalogue identifier of previous version: AEGA_v1_0 Journal reference of previous version: Comput. Phys. Comm. 181 (2010) 1161 External routines: ROOT version 5.24.00 ( http://root.cern.ch/drupal/) Does the new version supersede the previous version?: Yes Nature of problem: The output of a MCNP simulation is an ascii file. The data processing is usually performed by copying and pasting the relevant parts of the ascii

  2. The MCNP6 Analytic Criticality Benchmark Suite

    SciTech Connect

    Brown, Forrest B.

    2016-06-16

    Analytical benchmarks provide an invaluable tool for verifying computer codes used to simulate neutron transport. Several collections of analytical benchmark problems [1-4] are used routinely in the verification of production Monte Carlo codes such as MCNP® [5,6]. Verification of a computer code is a necessary prerequisite to the more complex validation process. The verification process confirms that a code performs its intended functions correctly. The validation process involves determining the absolute accuracy of code results vs. nature. In typical validations, results are computed for a set of benchmark experiments using a particular methodology (code, cross-section data with uncertainties, and modeling)more » and compared to the measured results from the set of benchmark experiments. The validation process determines bias, bias uncertainty, and possibly additional margins. Verification is generally performed by the code developers, while validation is generally performed by code users for a particular application space. The VERIFICATION_KEFF suite of criticality problems [1,2] was originally a set of 75 criticality problems found in the literature for which exact analytical solutions are available. Even though the spatial and energy detail is necessarily limited in analytical benchmarks, typically to a few regions or energy groups, the exact solutions obtained can be used to verify that the basic algorithms, mathematics, and methods used in complex production codes perform correctly. The present work has focused on revisiting this benchmark suite. A thorough review of the problems resulted in discarding some of them as not suitable for MCNP benchmarking. For the remaining problems, many of them were reformulated to permit execution in either multigroup mode or in the normal continuous-energy mode for MCNP. Execution of the benchmarks in continuous-energy mode provides a significant advance to MCNP verification methods.« less

  3. Benchmarking MCNP and TRIPOLI with PGNAA measurements

    NASA Astrophysics Data System (ADS)

    Carasco, C.; Perot, B.; Sikora, A.; Mauerhofer, E.; Havenith, A.; Payan, E.; Kettler, J.; Kring, T.; Ma, J. L.

    2014-06-01

    The French Alternative Energies and Atomic Energy Commission (CEA Cadarache), the Forschungszentrum Jülich GmbH (FZJ), and the RWTH Aachen University (RWTH) are involved in a cooperation aiming at characterizing toxic and reactive elements in radioactive waste packages by means of Prompt Gamma Neutron Activation Analysis (PGNAA). The design of an optimized measurement system and the assessment of its performances for realistic scenarios can be conveniently studied by numerical Monte Carlo simulation, provided the model and nuclear data offer a sufficient precision. Previous studies performed with MCNP have shown that when the nuclear data libraries lack of precision, relevant results can still be obtained by performing calculations in multiple steps (by first determining the radiative capture rate, and transporting the induced gamma toward the detector) and by injecting valid gamma-ray production data in-between [1]. In such cases, it is interesting to compare the results obtained with different codes. In the present paper, we propose to compare the MCNP and TRIPOLI codes with measurements obtained in MEDINA (Multi Element Detection based on Instrumental Neutron Activation), which is the new FZJ PGNAA facility [2]. The aim of the measurement campaign is to assess capture gamma rays of toxic elements that can be found in 200 L waste drums which are expected for geological repository.

  4. Semi-Analytical Benchmarks for MCNP6

    SciTech Connect

    Grechanuk, Pavel Aleksandrovi

    2016-11-07

    Code verification is an extremely important process that involves proving or disproving the validity of code algorithms by comparing them against analytical results of the underlying physics or mathematical theory on which the code is based. Monte Carlo codes such as MCNP6 must undergo verification and testing upon every release to ensure that the codes are properly simulating nature. Specifically, MCNP6 has multiple sets of problems with known analytic solutions that are used for code verification. Monte Carlo codes primarily specify either current boundary sources or a volumetric fixed source, either of which can be very complicated functions of space,more » energy, direction and time. Thus, most of the challenges with modeling analytic benchmark problems in Monte Carlo codes come from identifying the correct source definition to properly simulate the correct boundary conditions. The problems included in this suite all deal with mono-energetic neutron transport without energy loss, in a homogeneous material. The variables that differ between the problems are source type (isotropic/beam), medium dimensionality (infinite/semi-infinite), etc.« less

  5. Nova-like variables

    NASA Technical Reports Server (NTRS)

    Ladous, Constanze

    1993-01-01

    On grounds of different observable characteristics five classes of nova-like objects are distinguished: the UX Ursae Majoris stars, the antidwarf novae, the DQ Herculis stars, the AM Herculis stars, and the AM Canum Venaticorum stars. Some objects have not been classified specifically. Nova-like stars share most observable features with dwarf novae, except for the outburst behavior. The understanding is that dwarf novae, UX Ursae Majoris stars, and anti-dwarf novae are basically the same sort of objects. The difference between them is that in UX Ursae Majoris stars the mass transfer through the accretion disc always is high so the disc is stationary all the time; in anti-dwarf novae for some reason the mass transfer occasionally drops considerably for some time, and in dwarf novae it is low enough for the disc to undergo semiperiodic changes between high and low accretion events. DQ Herculis stars are believed to possess weakly magnetic white dwarfs which disrupt the inner disc at some distance from the central star; the rotation of the white dwarf can be seen as an additional photometric period. In AM Herculis stars, a strongly magnetic white dwarf entirely prevents the formation of an accretion disk and at the same time locks the rotation of the white dwarf to the binary orbit. Finally, AM Canum Venaticorum stars are believed to be cataclysmic variables that consist of two white dwarf components.

  6. Enhancements to the MCNP6 background source

    SciTech Connect

    McMath, Garrett E.; McKinney, Gregg W.

    2015-10-19

    The particle transport code MCNP has been used to produce a background radiation data file on a worldwide grid that can easily be sampled as a source in the code. Location-dependent cosmic showers were modeled by Monte Carlo methods to produce the resulting neutron and photon background flux at 2054 locations around Earth. An improved galactic-cosmic-ray feature was used to model the source term as well as data from multiple sources to model the transport environment through atmosphere, soil, and seawater. A new elevation scaling feature was also added to the code to increase the accuracy of the cosmic neutronmore » background for user locations with off-grid elevations. Furthermore, benchmarking has shown the neutron integral flux values to be within experimental error.« less

  7. Lecture Notes on Criticality Safety Validation Using MCNP & Whisper

    SciTech Connect

    Brown, Forrest B.; Rising, Michael Evan; Alwin, Jennifer Louise

    2016-03-11

    Training classes for nuclear criticality safety, MCNP documentation. The need for, and problems surrounding, validation of computer codes and data area considered first. Then some background for MCNP & Whisper is given--best practices for Monte Carlo criticality calculations, neutron spectra, S(α,β) thermal neutron scattering data, nuclear data sensitivities, covariance data, and correlation coefficients. Whisper is computational software designed to assist the nuclear criticality safety analyst with validation studies with the Monte Carlo radiation transport package MCNP. Whisper's methodology (benchmark selection – C k's, weights; extreme value theory – bias, bias uncertainty; MOS for nuclear data uncertainty – GLLS) and usagemore » are discussed.« less

  8. Light echoes - Novae

    NASA Technical Reports Server (NTRS)

    Schaefer, Bradley E.

    1988-01-01

    The sudden brilliance of a nova eruption will be reflected on surrounding dust grains to create a phantom nebula. Previous searches for these light echoes have used relatively short exposures with photograhic detectors. This paper reports on a search around eight recent novae with long exposures using a CCD camera. Despite an increase of sensitivity by over an order of magnitude, no light echoes were detected. It is found that the average grain density must be less than about 10 to the -9th per cu cm for distances from 0.1 pc to 1000 pc from the novae. The light echo around Nova Persei 1901 was caused by reflection off clouds with grain densities of several times 10 to the -9th per cu cm which are at distances between 0.1 pc and 10 pc. Echoes from dust in a circumstellar shell or ejected during a previous eruption will be effectively unobservable.

  9. Delta-ray Production in MCNP 6.2.0

    SciTech Connect

    Anderson, Casey Alan; McKinney, Gregg Walter; Tutt, James Robert

    2017-10-26

    Secondary electrons in the form of delta-rays, also referred to as knock-on electrons, have been a feature of MCNP for electron and positron transport for over 20 years. While MCNP6 now includes transport for a suite of heavy-ions and charged particles from its integration with MCNPX, the production of delta-rays was still limited to electron and positron transport. In the newest release of MCNP6, version 6.2.0, delta-ray production has now been extended for all energetic charged particles. The basis of this production is the analytical formulation from Rossi and ICRU Report 37. As a result, this paper discusses the MCNP6more » heavy charged-particle implementation and provides production results for several benchmark/test problems.« less

  10. MCNP-model for the OAEP Thai Research Reactor

    SciTech Connect

    Gallmeier, F.X.; Tang, J.S.; Primm, R.T. III

    1998-06-01

    An MCNP input was prepared for the Thai Research Reactor, making extensive use of the MCNP geometry`s lattice feature that allows a flexible and easy rearrangement of the core components and the adjustment of the control elements. The geometry was checked for overdefined or undefined zones by two-dimensional plots of cuts through the core configuration with the MCNP geometry plotting capabilities, and by a three-dimensional view of the core configuration with the SABRINA code. Cross sections were defined for a hypothetical core of 67 standard fuel elements and 38 low-enriched uranium fuel elements--all filled with fresh fuel. Three test calculationsmore » were performed with the MCNP4B-code to obtain the multiplication factor for the cases with control elements fully inserted, fully withdrawn, and at a working position.« less

  11. An ancient nova shell around the dwarf nova Z Camelopardalis.

    PubMed

    Shara, Michael M; Martin, Christopher D; Seibert, Mark; Rich, R Michael; Salim, Samir; Reitzel, David; Schiminovich, David; Deliyannis, Constantine P; Sarrazine, Angela R; Kulkarni, Shri R; Ofek, Eran O; Brosch, Noah; Lépine, Sebastien; Zurek, David; De Marco, Orsola; Jacoby, George

    2007-03-08

    Cataclysmic variables (classical novae and dwarf novae) are binary star systems in which a red dwarf transfers hydrogen-rich matter, by way of an accretion disk, to its white dwarf companion. In dwarf novae, an instability is believed to episodically dump much of the accretion disk onto the white dwarf. The liberation of gravitational potential energy then brightens these systems by up to 100-fold every few weeks or months. Thermonuclear-powered eruptions thousands of times more luminous occur in classical novae, accompanied by significant mass ejection and formation of clearly visible shells from the ejected material. Theory predicts that the white dwarfs in all dwarf novae must eventually accrete enough mass to undergo classical nova eruptions. Here we report a shell, an order of magnitude more extended than those detected around many classical novae, surrounding the prototypical dwarf nova Z Camelopardalis. The derived shell mass matches that of classical novae, and is inconsistent with the mass expected from a dwarf nova wind or a planetary nebula. The shell observationally links the prototypical dwarf nova Z Camelopardalis with an ancient nova eruption and the classical nova process.

  12. Verification of MCNP6.2 for Nuclear Criticality Safety Applications

    SciTech Connect

    Brown, Forrest B.; Rising, Michael Evan; Alwin, Jennifer Louise

    2017-05-10

    Several suites of verification/validation benchmark problems were run in early 2017 to verify that the new production release of MCNP6.2 performs correctly for nuclear criticality safety applications (NCS). MCNP6.2 results for several NCS validation suites were compared to the results from MCNP6.1 [1] and MCNP6.1.1 [2]. MCNP6.1 is the production version of MCNP® released in 2013, and MCNP6.1.1 is the update released in 2014. MCNP6.2 includes all of the standard features for NCS calculations that have been available for the past 15 years, along with new features for sensitivity-uncertainty based methods for NCS validation [3]. Results from the benchmark suitesmore » were compared with results from previous verification testing [4-8]. Criticality safety analysts should consider testing MCNP6.2 on their particular problems and validation suites. No further development of MCNP5 is planned. MCNP6.1 is now 4 years old, and MCNP6.1.1 is now 3 years old. In general, released versions of MCNP are supported only for about 5 years, due to resource limitations. All future MCNP improvements, bug fixes, user support, and new capabilities are targeted only to MCNP6.2 and beyond.« less

  13. Rapid Acute Dose Assessment Using MCNP6

    NASA Astrophysics Data System (ADS)

    Owens, Andrew Steven

    Acute radiation doses due to physical contact with a high-activity radioactive source have proven to be an occupational hazard. Multiple radiation injuries have been reported due to manipulating a radioactive source with bare hands or by placing a radioactive source inside a shirt or pants pocket. An effort to reconstruct the radiation dose must be performed to properly assess and medically manage the potential biological effects from such doses. Using the reference computational phantoms defined by the International Commission on Radiological Protection (ICRP) and the Monte Carlo N-Particle transport code (MCNP6), dose rate coefficients are calculated to assess doses for common acute doses due to beta and photon radiation sources. The research investigates doses due to having a radioactive source in either a breast pocket or pants back pocket. The dose rate coefficients are calculated for discrete energies and can be used to interpolate for any given energy of photon or beta emission. The dose rate coefficients allow for quick calculation of whole-body dose, organ dose, and/or skin dose if the source, activity, and time of exposure are known. Doses are calculated with the dose rate coefficients and compared to results from the International Atomic Energy Agency (IAEA) reports from accidents that occurred in Gilan, Iran and Yanango, Peru. Skin and organ doses calculated with the dose rate coefficients appear to agree, but there is a large discrepancy when comparing whole-body doses assessed using biodosimetry and whole-body doses assessed using the dose rate coefficients.

  14. The Galactic Nova Rate Revisited

    NASA Astrophysics Data System (ADS)

    Shafter, A. W.

    2017-01-01

    Despite its fundamental importance, a reliable estimate of the Galactic nova rate has remained elusive. Here, the overall Galactic nova rate is estimated by extrapolating the observed rate for novae reaching m≤slant 2 to include the entire Galaxy using a two component disk plus bulge model for the distribution of stars in the Milky Way. The present analysis improves on previous work by considering important corrections for incompleteness in the observed rate of bright novae and by employing a Monte Carlo analysis to better estimate the uncertainty in the derived nova rates. Several models are considered to account for differences in the assumed properties of bulge and disk nova populations and in the absolute magnitude distribution. The simplest models, which assume uniform properties between bulge and disk novae, predict Galactic nova rates of ˜50 to in excess of 100 per year, depending on the assumed incompleteness at bright magnitudes. Models where the disk novae are assumed to be more luminous than bulge novae are explored, and predict nova rates up to 30% lower, in the range of ˜35 to ˜75 per year. An average of the most plausible models yields a rate of {50}-23+31 yr-1, which is arguably the best estimate currently available for the nova rate in the Galaxy. Virtually all models produce rates that represent significant increases over recent estimates, and bring the Galactic nova rate into better agreement with that expected based on comparison with the latest results from extragalactic surveys.

  15. Depletion analysis of the UMLRR reactor core using MCNP6

    NASA Astrophysics Data System (ADS)

    Odera, Dim Udochukwu

    Accurate knowledge of the neutron flux and temporal nuclide inventory in reactor physics calculations is necessary for a variety of application in nuclear engineering such as criticality safety, safeguards, and spent fuel storage. The Monte Carlo N- Particle (MCNP6) code with integrated buildup depletion code (CINDER90) provides a high-fidelity tool that can be used to perform 3D, full core simulation to evaluate fissile material utilization, and nuclide inventory calculations as a function of burnup. The University of Massachusetts Lowell Research Reactor (UMLRR) reactor has been modeled with the deterministic based code, VENTURE and with an older version of MCNP (MCNP5). The MIT developed MCODE (MCNP ORIGEN DEPLETION CODE) was used previously to perform some limited depletion calculations. This work chronicles the use of MCNP6, released in June 2013, to perform coupled neutronics and depletion calculation. The results are compared to previously benchmarked results. Furthermore, the code is used to determine the ratio of fission products 134Cs and 137Cs (burnup indicators), and the resultant ratio is compared to the burnup of the UMLRR.

  16. School Psychology in Nova Scotia

    ERIC Educational Resources Information Center

    King, Sara; McGonnell, Melissa; Noyes, Amira

    2016-01-01

    Registration as a psychologist in Nova Scotia can be at the master's or doctoral level; however, the Nova Scotia Board of Examiners in Psychology has announced a move to the doctoral degree as the entry-level to practice. Many school psychologists in Nova Scotia practice at the master's level; therefore, this change could affect school psychology…

  17. NOVA HIGH SCHOOL.

    ERIC Educational Resources Information Center

    Broward County Schools, Fort Lauderdale, FL.

    NOVA HIGH SCHOOL OPENED IN SEPTEMBER 1963 AS A UNIT OF THE SOUTH FLORIDA EDUCATIONAL CENTER. IT IS EXPERIMENTAL IN CONCEPT, BUT NOT IN CURRICULUM. ITS CONSTRUCTION, FEATURES, EQUIPMENT, TEACHING AIDS, AND INSTRUCTIONAL METHODS HAVE BEEN TESTED AND PROVED IN OTHER SCHOOL SYSTEMS. ITS PHILOSOPHY REPRESENTS A RETURN TO FUNDAMENTAL EDUCATION, BUT ITS…

  18. SCIENCE AT NOVA.

    ERIC Educational Resources Information Center

    Broward County Schools, Fort Lauderdale, FL.

    THE SCIENCE PROGRAM AT NOVA HIGH SCHOOL IS STRUCTURED TO MEET THE NEEDS OF A SCIENTIFIC SOCIETY. THE JUNIOR HIGH PROGRAM EMPHASIZES THE ACCUMLATION, TABULATION, AND ANALYSIS OF DATA. THE SENIOR HIGH PROGRAM MAKES USE OF THESE PROCESSES IN THE INVESTIGATION OF VARIOUS SUBJECT AREAS. THE UNITS COMPOSING THE HIGH SCHOOL CURRICULUM ARE DESCRIBED. UNIT…

  19. MCNP speed advances for boron neutron capture therapy

    SciTech Connect

    Goorley, J.T.; McKinney, G.; Adams, K.

    1998-04-01

    The Boron Neutron Capture Therapy (BNCT) treatment planning process of the Beth Israel Deaconess Medical Center-M.I.T team relies on MCNP to determine dose rates in the subject`s head for various beam orientations. In this time consuming computational process, four or five potential beams are investigated. Of these, one or two final beams are selected and thoroughly evaluated. Recent advances greatly decreased the time needed to do these MCNP calculations. Two modifications to the new MCNP4B source code, lattice tally and tracking enhancements, reduced the wall-clock run times of a typical one million source neutrons run to one hour twenty fivemore » minutes on a 200 MHz Pentium Pro computer running Linux and using the GNU FORTRAN compiler. Previously these jobs used a special version of MCNP4AB created by Everett Redmond, which completed in two hours two minutes. In addition to this 30% speedup, the MCNP4B version was adapted for use with Parallel Virtual Machine (PVM) on personal computers running the Linux operating system. MCNP, using PVM, can be run on multiple computers simultaneously, offering a factor of speedup roughly the same as the number of computers used. With two 200 MHz Pentium Pro machines, the run time was reduced to forty five minutes, a 1.9 factor of improvement over the single Linux computer. While the time of a single run was greatly reduced, the advantages associated with PVM derive from using computational power not already used. Four possible beams, currently requiring four separate runs, could be run faster when each is individually run on a single machine under Windows NT, rather than using Linux and PVM to run one after another with each multiprocessed across four computers. It would be advantageous, however, to use PVM to distribute the final two beam orientations over four computers.« less

  20. Accelerating Pseudo-Random Number Generator for MCNP on GPU

    NASA Astrophysics Data System (ADS)

    Gong, Chunye; Liu, Jie; Chi, Lihua; Hu, Qingfeng; Deng, Li; Gong, Zhenghu

    2010-09-01

    Pseudo-random number generators (PRNG) are intensively used in many stochastic algorithms in particle simulations, artificial neural networks and other scientific computation. The PRNG in Monte Carlo N-Particle Transport Code (MCNP) requires long period, high quality, flexible jump and fast enough. In this paper, we implement such a PRNG for MCNP on NVIDIA's GTX200 Graphics Processor Units (GPU) using CUDA programming model. Results shows that 3.80 to 8.10 times speedup are achieved compared with 4 to 6 cores CPUs and more than 679.18 million double precision random numbers can be generated per second on GPU.

  1. Reactor physics verification of the MCNP6 unstructured mesh capability

    SciTech Connect

    Burke, T. P.; Kiedrowski, B. C.; Martz, R. L.

    2013-07-01

    The Monte Carlo software package MCNP6 has the ability to transport particles on unstructured meshes generated from the Computed-Aided Engineering software Abaqus. Verification is performed using benchmarks with features relevant to reactor physics - Big Ten and the C5G7 computational benchmark. Various meshing strategies are tested and results are compared to reference solutions. Computational performance results are also given. The conclusions show MCNP6 is capable of producing accurate calculations for reactor physics geometries and the computational requirements for small lattice benchmarks are reasonable on modern computing platforms. (authors)

  2. Monte Carlo N-Particle Transport Code System Including MCNP6.1.1BETA, MCNP6.1, MCNP5-1.60, MCNPX-2.7.0 and Data Libraries.

    SciTech Connect

    2014-09-01

    Version 01 MCNP6™ is a general-purpose, continuous-energy, generalized-geometry, time-dependent, Monte Carlo radiation-transport code designed to track many particle types over broad ranges of energies. This MCNP6.1.1Beta is a follow-on to the MCNP6.1 production version which itself was the culmination of a multi-year effort to merge the MCNP5™ [X-503] and MCNPX™ [PEL11] codes into a single product. This MCNP6.1.1 beta has been released in order to provide the radiation transport community with the latest feature developments and bug fixes in the code. MCNP6.1.1 has taken input from a group of people, residing in the Los Alamos National Laboratory's (LANL) X Computationalmore » Physics Division, Radiation Transport Group (XCP-3), and Nuclear Engineering and Nonproliferation Division, Systems Design and Analysis Group (NEN-5). They have combined their code development efforts to produce this next evolution of MCNP. For those familiar with previous versions of MCNP, you will discover the code has been expanded to handle a multitude of particles and to include model physics options for energies above the cross-section table range, a material burnup feature, and delayed particle production. Expanded and/or new tally, source, and variance-reduction options are available to the user as well as an improved plotting capability. The capability to calculate keff eigenvalues for fissile systems remains a standard feature. Although MCNP6 is simply and accurately described as the merger of MCNP5 and MCNPX capabilities, the result is much more than the sum of these two computer codes. MCNP6 is the result of five years of effort by the MCNP5 and MCNPX code development teams.« less

  3. MCNP6. Simulating Correlated Data in Fission Events

    SciTech Connect

    Rising, Michael Evan; Sood, Avneet

    2015-12-03

    This report is a series of slides discussing the MCNP6 code and its status in simulating fission. Applications of interest include global security and nuclear nonproliferation, detection of special nuclear material (SNM), passive and active interrogation techniques, and coincident neutron and photon leakage.

  4. Duplicating MC-15 Output with Python and MCNP

    SciTech Connect

    McSpaden, Alexander Thomas

    2017-08-23

    Two Python scripts have been written that process the output files of MCNP6 into a format that mimics the list-mode output of Los Alamos National Laboratory’s MC-15 and NPOD neutron detection systems. This report details the methods implemented in these scripts and instructions on their use.

  5. Possible Improvements to MCNP6 and its CEM/LAQGSM Event-Generators

    SciTech Connect

    Mashnik, Stepan Georgievich

    2015-08-04

    This report is intended to the MCNP6 developers and sponsors of MCNP6. It presents a set of suggested possible future improvements to MCNP6 and to its CEM03.03 and LAQGSM03.03 event-generators. A few suggested modifications of MCNP6 are quite simple, aimed at avoiding possible problems with running MCNP6 on various computers, i.e., these changes are not expected to change or improve any results, but should make the use of MCNP6 easier; such changes are expected to require limited man-power resources. On the other hand, several other suggested improvements require a serious further development of nuclear reaction models, are expected to improvemore » significantly the predictive power of MCNP6 for a number of nuclear reactions; but, such developments require several years of work by real experts on nuclear reactions.« less

  6. Geometry creation for MCNP by Sabrina and XSM

    SciTech Connect

    Van Riper, K.A.

    1994-02-01

    The Monte Carlo N-Particle transport code MCNP is based on a surface description of 3-dimensional geometry. Cells are defined in terms of boolean operations on signed quadratic surfaces. MCNP geometry is entered as a card image file containing coefficients of the surface equations and a list of surfaces and operators describing cells. Several programs are available to assist in creation of the geometry specification, among them Sabrina and the new ``Smart Editor`` code XSM. We briefly describe geometry creation in Sabrina and then discuss XSM in detail. XSM is under development; our discussion is based on the state of XSMmore » as of January 1, 1994.« less

  7. The MCNP{trademark}/LCS{trademark} merger project

    SciTech Connect

    Hughes, H.G.; Adams, K.J.; Chadwick, M.B.

    1997-10-01

    The MCNP code is written and maintained by Group X-TM at Los Alamos National Laboratory. In response to a variety of needs, and particularly in support of the Accelerator Production of Tritium (APT) program, the authors have recently undertaken a major effort to expand the capabilities of MCNP to increase the set of transportable particles; to make use of newly evaluated high energy nuclear data tables for neutrons, protons, and potentially other particles; and to incorporate physics models for use where tabular data are unavailable. A preliminary version of the expanded code, called MCNPX, has now been issued for testing.more » The new code includes all existing LAHET physics modules, and has the ability to utilize the 150 MeV data libraries that have recently been released by LANL Group T-2.« less

  8. MCNP modelling of a combined neutron/gamma counter

    NASA Astrophysics Data System (ADS)

    Bourva, L. C.-A.; Croft, S.; Ottmar, H.; Weaver, D. R.

    1999-05-01

    A series of Monte Carlo neutron calculations for a combined gamma/passive neutron coincidence counter has been performed. This type of device, part of a suite of non-destructive assay instruments utilised for the enforcement of the Euratom nuclear safeguards within the European Union, is to be used for high accuracy measurements of the plutonium content of small samples of nuclear materials. The multi-purpose Monte Carlo N-particle (MCNP) code version 4B has been used to model in detail the neutron coincidence detector and to investigate the leakage self-multiplication of PuO 2 and mixed U-Pu oxide (MOX) reference samples used to calibrate the instrument. The MCNP calculations have been used together with a neutron coincidence counting interpretative model to determine characteristic parameters of the detector. A comparative study to both experimental and previous numerical results has been performed. Sensitivity curves of the variation of the detector's efficiency, ɛ, to, α, the ratio of (α,n) to spontaneous fission neutron emission rate and to f R, the reals coincidence gate utilisation factor, are presented. Sources of the inaccuracy in the calculations have not yet been fully investigated, because of the vast parameter space to be considered, but values of the coincidence gate utilisation factor derived directly from the MCNP data have been found to be overestimated by about 8.2%. Once bias-corrected, the trends of the real coincidence counts rate as a function of sample mass for three types of sample could be matched to experimental results within 0.33%. This result confirms the possible use of MCNP to calculate response trends accurately for a wide variety of source materials, given a limited experimental calibration set.

  9. NOVA Fall 2002 Teacher's Guide.

    ERIC Educational Resources Information Center

    Ransick, Kristina; Rosene, Dale; Sammons, James; Turck, Mary

    This NOVA teacher's guide presents activities, information, and teaching ideas from the Public Broadcasting System's (PBS) NOVA television program series. Episodes include: (1) "Mysterious Life of Caves" which investigates the role microbes play in the creation of some limestone caves; (2) "Lost Roman Treasure" which follows…

  10. Benchmark study of TRIPOLI-4 through experiment and MCNP codes

    SciTech Connect

    Michel, M.; Coulon, R.; Normand, S.

    2011-07-01

    Reliability on simulation results is essential in nuclear physics. Although MCNP5 and MCNPX are the world widely used 3D Monte Carlo radiation transport codes, alternative Monte Carlo simulation tools exist to simulate neutral and charged particles' interactions with matter. Therefore, benchmark are required in order to validate these simulation codes. For instance, TRIPOLI-4.7, developed at the French Alternative Energies and Atomic Energy Commission for neutron and photon transport, now also provides the user with a full feature electron-photon electromagnetic shower. Whereas the reliability of TRIPOLI-4.7 for neutron and photon transport has been validated yet, the new development regarding electron-photon mattermore » interaction needs additional validation benchmarks. We will thus demonstrate how accurately TRIPOLI-4's 'deposited spectrum' tally can simulate gamma spectrometry problems, compared to MCNP's 'F8' tally. The experimental setup is based on an HPGe detector measuring the decay spectrum of an {sup 152}Eu source. These results are then compared with those given by MCNPX 2.6d and TRIPOLI-4 codes. This paper deals with both the experimental aspect and simulation. We will demonstrate that TRIPOLI-4 is a potential alternative to both MCNPX and MCNP5 for gamma-electron interaction simulation. (authors)« less

  11. Yankee Rowe isotopics benchmark using MCNP-XT

    SciTech Connect

    Xu, Z.; Whitmer, C.

    2013-07-01

    The Yankee Rowe spent fuel isotopic data provides a valuable source to benchmark the burnup calculations as part of verification and validation (V and V) efforts for the TerraPower's Monte Carlo depletion code, MCNP-XT. A total of 71 fuel rods were selected in the Yankee Rowe isotopic measurements covering a burnup range up to 44 MWd/kg ({approx}4.4%) under both the asymptotic spectrum and the non-asymptotic spectrum. The MCNP-XT pin cell depletion provides a comparison against the asymptotic spectrum measurement; and full assembly depletion with 322 depletion materials provides comparisons against various non-asymptotic depletion conditions. All calculations are performed based onmore » the recent ENDF/B-VII.O data. Furthermore, the Monte Carlo depletion uncertainties and biases were examined showing their effect as insignificant. The set of burnup calculations cover the scattered experimental measurements demonstrating excellent agreement with the measured values. This benchmark exercise demonstrates the depletion analysis capability of the MCNP-XT code and validates the low burnup range. (authors)« less

  12. MCNP6 fragmentation of light nuclei at intermediate energies

    NASA Astrophysics Data System (ADS)

    Mashnik, Stepan G.; Kerby, Leslie M.

    2014-11-01

    Fragmentation reactions induced on light target nuclei by protons and light nuclei of energies around 1 GeV/nucleon and below are studied with the latest Los Alamos Monte Carlo transport code MCNP6 and with its cascade-exciton model (CEM) and Los Alamos version of the quark-gluon string model (LAQGSM) event generators, version 03.03, used as stand-alone codes. Such reactions are involved in different applications, like cosmic-ray-induced single event upsets (SEU's), radiation protection, and cancer therapy with proton and ion beams, among others; therefore, it is important that MCNP6 simulates them as well as possible. CEM and LAQGSM assume that intermediate-energy fragmentation reactions on light nuclei occur generally in two stages. The first stage is the intranuclear cascade (INC), followed by the second, Fermi breakup disintegration of light excited residual nuclei produced after the INC. Both CEM and LAQGSM account also for coalescence of light fragments (complex particles) up to 4He from energetic nucleons emitted during INC. We investigate the validity and performance of MCNP6, CEM, and LAQGSM in simulating fragmentation reactions at intermediate energies and discuss possible ways of further improving these codes.

  13. Olivier Chesneau's Work on Novae

    NASA Astrophysics Data System (ADS)

    Millour, F.; Lagadec, E.

    2015-12-01

    Olivier Chesneau founded a brand new field of observational astrophysics with his attempts to resolve the novae expanding fireball from the very first days of the explosion. With the images he could get, he showed that novae do indeed explode in an aspherical way, leading to a change of paradigm for the physics of these yet-poorly understood catastrophic systems. He also set the stage for a new way of estimating novae distances, by directly measuring the sky-size of the fireball and comparing it with spectroscopic scales, taking into account the tremendous effects of the fireball geometry.

  14. Comparison of CAP88 and MCNP for Overhead Gamma-emitting Plumes

    SciTech Connect

    Mcnaughton, Michael; Gillis, Jessica Mcdonnel; McClory, Aysha Reede

    2016-01-08

    The purpose of this paper is to use the Monte Carlo N-Particle Code (MCNP) to investigate the dose from gamma-emitting radionuclides such as Carbon-11 when a plume passes overhead. MCNP results are compared with results from the EPA program, CAP88. In some cases, typically near the source during stable conditions, the CAP88 results are less than the MCNP results. However, in the case of a receptor 800 m from a source at the Los Alamos Neutron Science Center (LANSCE), the CAP88 result is greater than the MCNP result.

  15. Review of Heavy Charged Particle Transport in MCNP6.2

    DOE PAGES

    Zieb, Kristofer James Ekhart; Hughes, Henry Grady III; Xu, X. George; ...

    2018-01-05

    The release of version 6.2 of the MCNP6 radiation transport code is imminent. To complement the newest release, a summary of the heavy charged particle physics models used in the 1 MeV to 1 GeV energy regime is presented. Several changes have been introduced into the charged particle physics models since the merger of the MCNP5 and MCNPX codes into MCNP6. Here, this article discusses the default models used in MCNP6 for continuous energy loss, energy straggling, and angular scattering of heavy charged particles. Explanations of the physics models’ theories are included as well.

  16. Review of heavy charged particle transport in MCNP6.2

    NASA Astrophysics Data System (ADS)

    Zieb, K.; Hughes, H. G.; James, M. R.; Xu, X. G.

    2018-04-01

    The release of version 6.2 of the MCNP6 radiation transport code is imminent. To complement the newest release, a summary of the heavy charged particle physics models used in the 1 MeV to 1 GeV energy regime is presented. Several changes have been introduced into the charged particle physics models since the merger of the MCNP5 and MCNPX codes into MCNP6. This paper discusses the default models used in MCNP6 for continuous energy loss, energy straggling, and angular scattering of heavy charged particles. Explanations of the physics models' theories are included as well.

  17. Monte Carlo N-Particle Transport Code System Including MCNP6.1, MCNP5-1.60, MCNPX-2.7.0 and Data Libraries.

    SciTech Connect

    GOORLEY, TIM

    2013-07-16

    Version 01 US DOE 10CFR810 Jurisdiction. MCNP6™ is a general-purpose, continuous-energy, generalized-geometry, time-dependent, Monte Carlo radiation-transport code designed to track many particle types over broad ranges of energies. MCNP6 represents the culmination of a multi-year effort to merge the MCNP5™ [X-503] and MCNPX™ [PEL11] codes into a single product comprising all features of both. For those familiar with previous versions of MCNP, you will discover the code has been expanded to handle a multitude of particles and to include model physics options for energies above the cross-section table range, a material burnup feature, and delayed particle production. Expanded and/or newmore » tally, source, and variance-reduction options are available to the user as well as an improved plotting capability. The capability to calculate keff eigenvalues for fissile systems remains a standard feature. Although MCNP6 is simply and accurately described as the merger of MCNP5 and MCNPX capabilities, the result is much more than the sum of these two computer codes. MCNP6 is the result of five years of effort by the MCNP5 and MCNPX code development teams. These groups of people, residing in the Los Alamos National Laboratory's (LANL) X Computational Physics Division, Monte Carlo Codes Group (XCP-3), and Nuclear Engineering and Nonproliferation Division, Systems Design and Analysis Group (NEN-5, formerly D-5), have combined their code development efforts to produce the next evolution of MCNP. While maintenance and bug fixes will continue for MCNP5 v.1.60 and MCNPX v.2.7.0 for upcoming years, new code development capabilities will be developed and released only in MCNP6. In fact, this initial production release of MCNP6 (v. 1.0) contains 16 new features not previously found in either code. These new features include (among others) the abilities to import unstructured mesh geometries from the finite element code Abaqus, to transport photons down to 1.0 eV, to model

  18. Monte Carlo N-Particle Transport Code System Including MCNP6.1, MCNP5-1.60, MCNPX-2.7.0 and Data Libraries.

    SciTech Connect

    GOORLEY, TIM

    2013-07-16

    Version 00 US DOE 10CFR810 Jurisdiction. MCNP6™ is a general-purpose, continuous-energy, generalized-geometry, time-dependent, Monte Carlo radiation-transport code designed to track many particle types over broad ranges of energies. MCNP6 represents the culmination of a multi-year effort to merge the MCNP5™ [X-503] and MCNPX™ [PEL11] codes into a single product comprising all features of both. For those familiar with previous versions of MCNP, you will discover the code has been expanded to handle a multitude of particles and to include model physics options for energies above the cross-section table range, a material burnup feature, and delayed particle production. Expanded and/or newmore » tally, source, and variance-reduction options are available to the user as well as an improved plotting capability. The capability to calculate keff eigenvalues for fissile systems remains a standard feature. Although MCNP6 is simply and accurately described as the merger of MCNP5 and MCNPX capabilities, the result is much more than the sum of these two computer codes. MCNP6 is the result of five years of effort by the MCNP5 and MCNPX code development teams. These groups of people, residing in the Los Alamos National Laboratory's (LANL) X Computational Physics Division, Monte Carlo Codes Group (XCP-3), and Nuclear Engineering and Nonproliferation Division, Systems Design and Analysis Group (NEN-5, formerly D-5), have combined their code development efforts to produce the next evolution of MCNP. While maintenance and bug fixes will continue for MCNP5 v.1.60 and MCNPX v.2.7.0 for upcoming years, new code development capabilities will be developed and released only in MCNP6. In fact, this initial production release of MCNP6 (v. 1.0) contains 16 new features not previously found in either code. These new features include (among others) the abilities to import unstructured mesh geometries from the finite element code Abaqus, to transport photons down to 1.0 eV, to model

  19. Argonne's Vilas Pol on NOVA!

    ScienceCinema

    None

    2017-12-09

    Can innovations in materials science help clean up our world? Argonne's material scientist Vilas Pol guest starred on NOVA's "Making Stuff: Cleaner," where David Pogue explored the rapidly-developing science and business of clean energy.

  20. MCNP Techniques for Modeling Sodium Iodide Spectra of Kiwi Surveys

    SciTech Connect

    Robert B. Hayes

    2007-11-01

    This work demonstrates how MCNP can be used to predict the response of mobile search and survey equipment from base principles. The instrumentation evaluated comes from the U.S. Department of Energy’s Aerial Measurement Systems. Through reconstructing detector responses to various point-source measurements, detector responses to distributed sources can be estimated through superposition. Use of this methodology for currently deployed systems allows predictive determinations of activity levels and distributions for common configurations of interest. This work helps determine the quality and efficacy of certain surveys in fully characterizing an effected site following a radiological event of national interest.

  1. Testing the Delayed Gamma Capability in MCNP6

    SciTech Connect

    Weldon, Robert A.; Fensin, Michael L.; McKinney, Gregg W.

    2015-10-28

    systems. We examine five different decay chains (two-stage decay to stable) and show the predictability of the MCNP6 delayed gamma feature. Results do show that while the default delayed gamma calculations available in the MCNP6 1.0 release can give accurate results for some isotopes (e.g., 137Ba), the percent differences between the closed form analytic solutions and the MCNP6 calculations were often >40% ( 28Mg, 28Al, 42K, 47Ca, 47Sc, 60Co). With the MCNP6 1.1 Beta release, the tenth entry on the DBCN card allows improved calculation within <5% as compared to the closed form analytic solutions for immediate parent emissions and transient equilibrium systems. While the tenth entry on the DBCN card for MCNP6 1.1 gives much better results for transient equilibrium systems and parent emissions in general, it does little to improve daughter emissions of secular equilibrium systems. Finally, hypotheses were presented as to why daughter emissions of secular equilibrium systems might be mispredicted in some cases and not in others.« less

  2. RECURRENT NOVAE IN M31

    SciTech Connect

    Shafter, A. W.; Henze, M.; Rector, T. A.

    2015-02-01

    The reported positions of 964 suspected nova eruptions in M31 recorded through the end of calendar year 2013 have been compared in order to identify recurrent nova (RN) candidates. To pass the initial screen and qualify as a RN candidate, two or more eruptions were required to be coincident within 0.′1, although this criterion was relaxed to 0.′15 for novae discovered on early photographic patrols. A total of 118 eruptions from 51 potential RN systems satisfied the screening criterion. To determine what fraction of these novae are indeed recurrent, the original plates and published images of the relevant eruptions havemore » been carefully compared. This procedure has resulted in the elimination of 27 of the 51 progenitor candidates (61 eruptions) from further consideration as RNe, with another 8 systems (17 eruptions) deemed unlikely to be recurrent. Of the remaining 16 systems, 12 candidates (32 eruptions) were judged to be RNe, with an additional 4 systems (8 eruptions) being possibly recurrent. It is estimated that ∼4% of the nova eruptions seen in M31 over the past century are associated with RNe. A Monte Carlo analysis shows that the discovery efficiency for RNe may be as low as 10% that for novae in general, suggesting that as many as one in three nova eruptions observed in M31 arise from progenitor systems having recurrence times ≲100 yr. For plausible system parameters, it appears unlikely that RNe can provide a significant channel for the production of Type Ia supernovae.« less

  3. Spectroscopic authentication of very old nova candidates

    NASA Astrophysics Data System (ADS)

    Shara, Michael M.; Moffat, Anthony F. J.; Potter, Michael

    1990-08-01

    Results are reported from spectroscopic observations of four objects which have been identified as possible quiescent novae. Spectra obtained using the 1.0-m telescope at SAAO, the 4-m telescope at CTIO, and the 3.6-m Canada-France-Hawaii telescope during 1988-1989 are presented for T Boo (Nova 1860), U Leo (Nova 1855), Nova Pup 1673, and E2000 + 223 (an Einstein Observatory X-ray source supposed to be an old nova shell). No certain evidence is found that any of these candidates are the blue mass-transferring binaries predicted by theoretical models of classical novae.

  4. Revisiting Nova Cyg III 1920

    NASA Astrophysics Data System (ADS)

    Cline, J. Donald; Castelaz, M. W.; Barker, T. H.

    2009-05-01

    Nova Cyg III 1920 (Denning 1920, The Observatory, 43, 328) is one of the brightest and fastest galactic observed, increasing in brightness nearly 13.5 magnitudes and declining 3 magnitudes in 16 days. Baldwin (1943, Pub. Obs. Mich., 8, 61) states that Nova Cyg III 1920 is the only nova where emission velocities in the nebular stage don't agree with the velocity of the principal spectrum. Knots of emission are observed by Slavin et al (1995, MNRAS, 276, 353). The time of formation of the knots is unclear, although the early spectra suggest the knots formed during outburst. In order to clarify these sets of observations, we re-measured the velocities of the lines of 45 spectroscopic plates which have a dispersion of 40 Angstroms/mm and taken with the Ann Arbor 37.5-inch telescope from 23 August 1920 to 4 October 1920, using modern digitization and image processing techniques. The spectrographs were scanned at the Astronomical Photographic Data Archive located at Pisgah Astronomical Research Institute with a transmission scanner that has a resolution of 0.23 Angstroms/pixel. Each scanned image includes a titanium comparison lamp spectrum and nova spectrum for wavelength calibration. In addition, the interstellar H and K lines are easily detected and used as one method to measure the velocities of the nova H and K lines. We will present the complex spectra and discuss the line profiles in terms of the possibility of early formation of emission knots.

  5. Addressing Fission Product Validation in MCNP Burnup Credit Criticality Calculations

    SciTech Connect

    Mueller, Don; Bowen, Douglas G; Marshall, William BJ J

    2015-01-01

    The US Nuclear Regulatory Commission (NRC) Division of Spent Fuel Storage and Transportation issued Interim Staff Guidance (ISG) 8, Revision 3 in September 2012. This ISG provides guidance for NRC staff members’ review of burnup credit (BUC) analyses supporting transport and dry storage of pressurized water reactor spent nuclear fuel (SNF) in casks. The ISG includes guidance for addressing validation of criticality (k eff) calculations crediting the presence of a limited set of fission products and minor actinides (FP&MAs). Based on previous work documented in NRC Regulatory Guide (NUREG) Contractor Report (CR)-7109, the ISG recommends that NRC staff members acceptmore » the use of either 1.5 or 3% of the FP&MA worth—in addition to bias and bias uncertainty resulting from validation of k eff calculations for the major actinides in SNF—to conservatively account for the bias and bias uncertainty associated with the specified unvalidated FP&MAs. The ISG recommends (1) use of 1.5% of the FP&MA worth if a modern version of SCALE and its nuclear data are used and (2) 3% of the FP&MA worth for well qualified, industry standard code systems other than SCALE with the Evaluated Nuclear Data Files, Part B (ENDF/B),-V, ENDF/B-VI, or ENDF/B-VII cross sections libraries. The work presented in this paper provides a basis for extending the use of the 1.5% of the FP&MA worth bias to BUC criticality calculations performed using the Monte Carlo N-Particle (MCNP) code. The extended use of the 1.5% FP&MA worth bias is shown to be acceptable by comparison of FP&MA worths calculated using SCALE and MCNP with ENDF/B-V, -VI, and -VII–based nuclear data. The comparison supports use of the 1.5% FP&MA worth bias when the MCNP code is used for criticality calculations, provided that the cask design is similar to the hypothetical generic BUC-32 cask model and that the credited FP&MA worth is no more than 0.1 Δk eff (ISG-8, Rev. 3, Recommendation 4).« less

  6. Spectroscopy of novae and supernovae

    NASA Astrophysics Data System (ADS)

    Prabhu, T. P.

    1993-09-01

    Many novae have been studied spectroscopically since 1975 and many supernovae since 1980 using the telescopes at Vainu Bappu Observatory (VBO). The program on novae has intensified since 1985, and that on supernovae has found renewed interest since SN 1987A. The availability of the CCD detector in 1989 and of the Boller & Chivens spectrograph at the Vainu Bappu Telescope (VBT) in 1991 have added impetus to these studies. The motivation for these studies are summarized in this review together with some of the important results obtained with the VBT. The desirable improvements at the VBT are summarized at the end.

  7. Experimental validation of lead cross sections for scale and MCNP

    SciTech Connect

    Henrikson, D.J.

    1995-12-01

    Moving spent nuclear fuel between facilities often requires the use of lead-shielded casks. Criticality safety that is based upon calculations requires experimental validation of the fuel matrix and lead cross section libraries. A series of critical experiments using a high-enriched uranium-aluminum fuel element with a variety of reflectors, including lead, has been identified. Twenty-one configurations were evaluated in this study. The fuel element was modelled for KENO V.a and MCNP 4a using various cross section sets. The experiments addressed in this report can be used to validate lead-reflected calculations. Factors influencing calculated k{sub eff} which require further study include diametersmore » of styrofoam inserts and homogenization.« less

  8. Visualizing MCNP Tally Segment Geometry and Coupling Results with ABAQUS

    SciTech Connect

    J. R. Parry; J. A. Galbraith

    2007-11-01

    The Advanced Graphite Creep test, AGC-1, is planned for irradiation in the Advanced Test Reactor (ATR) in support of the Next Generation Nuclear Plant program. The experiment requires very detailed neutronics and thermal hydraulics analyses to show compliance with programmatic and ATR safety requirements. The MCNP model used for the neutronics analysis required hundreds of tally regions to provide the desired detail. A method for visualizing the hundreds of tally region geometries and the tally region results in 3 dimensions has been created to support the AGC-1 irradiation. Additionally, a method was created which would allow ABAQUS to access themore » results directly for the thermal analysis of the AGC-1 experiment.« less

  9. Heart simulation with surface equations for using on MCNP code

    SciTech Connect

    Rezaei-Ochbelagh, D.; Salman-Nezhad, S.; Asadi, A.

    2011-12-26

    External photon beam radiotherapy is carried out in a way to achieve an 'as low as possible' a dose in healthy tissues surrounding the target. One of these surroundings can be heart as a vital organ of body. As it is impossible to directly determine the absorbed dose by heart, using phantoms is one way to acquire information around it. The other way is Monte Carlo method. In this work we have presented a simulation of heart geometry by introducing of different surfaces in MCNP code. We used 14 surface equations in order to determine human heart modeling. Those surfacesmore » are borders of heart walls and contents.« less

  10. Performance upgrades to the MCNP6 burnup capability for large scale depletion calculations

    DOE PAGES

    Fensin, M. L.; Galloway, J. D.; James, M. R.

    2015-04-11

    The first MCNP based inline Monte Carlo depletion capability was officially released from the Radiation Safety Information and Computational Center as MCNPX 2.6.0. With the merger of MCNPX and MCNP5, MCNP6 combined the capability of both simulation tools, as well as providing new advanced technology, in a single radiation transport code. The new MCNP6 depletion capability was first showcased at the International Congress for Advancements in Nuclear Power Plants (ICAPP) meeting in 2012. At that conference the new capabilities addressed included the combined distributive and shared memory parallel architecture for the burnup capability, improved memory management, physics enhancements, and newmore » predictability as compared to the H.B Robinson Benchmark. At Los Alamos National Laboratory, a special purpose cluster named “tebow,” was constructed such to maximize available RAM per CPU, as well as leveraging swap space with solid state hard drives, to allow larger scale depletion calculations (allowing for significantly more burnable regions than previously examined). As the MCNP6 burnup capability was scaled to larger numbers of burnable regions, a noticeable slowdown was realized.This paper details two specific computational performance strategies for improving calculation speedup: (1) retrieving cross sections during transport; and (2) tallying mechanisms specific to burnup in MCNP. To combat this slowdown new performance upgrades were developed and integrated into MCNP6 1.2.« less

  11. Comparisons between MCNP, EGS4 and experiment for clinical electron beams

    NASA Astrophysics Data System (ADS)

    Jeraj, Robert; Keall, Paul J.; Ostwald, Patricia M.

    1999-03-01

    Understanding the limitations of Monte Carlo codes is essential in order to avoid systematic errors in simulations, and to suggest further improvement of the codes. MCNP and EGS4, Monte Carlo codes commonly used in medical physics, were compared and evaluated against electron depth dose data and experimental backscatter results obtained using clinical radiotherapy beams. Different physical models and algorithms used in the codes give significantly different depth dose curves and electron backscattering factors. The default version of MCNP calculates electron depth dose curves which are too penetrating. The MCNP results agree better with experiment if the ITS-style energy-indexing algorithm is used. EGS4 underpredicts electron backscattering for high- Z materials. The results slightly improve if optimal PRESTA-I parameters are used. MCNP simulates backscattering well even for high- Z materials. To conclude the comparison, a timing study was performed. EGS4 is generally faster than MCNP and use of a large number of scoring voxels dramatically slows down the MCNP calculation. However, use of a large number of geometry voxels in MCNP only slightly affects the speed of the calculation.

  12. A real light echo - Nova Persei 1901

    NASA Technical Reports Server (NTRS)

    Felten, J. E.

    1988-01-01

    Observations of Nova Persei 1901, a light echo from SN 1987A, are reviewed. The large broken outer ring and bright inner ring of the nova are examined. The outer ring has been shown to increase its radius at a speed of about 11 arcmin/year. Since the distance to Nova Persei 1901 is about 400-600 pc, the apparent projected velocity of expansion is about 4-5 c, making the nova the first observed superluminal cosmic source.

  13. Observations of classical novae in outburst

    NASA Technical Reports Server (NTRS)

    Starrfield, S.; Stryker, L. L.; Sonneborn, G.; Sparks, Warren M.; Ferland, Gary; Wagner, R. M.; Williams, R. E.; Gehrz, Robert D.; Ney, Edward P.; Kenyon, Scott

    1988-01-01

    The IUE obtained ultraviolet data on novae in outburst. The characteristics of every one of the outbursts are different. Optical and infrared data on many of the same novae were also obtained. Three members of the carbon-oxygen class of novae are presented.

  14. Swift Observations of OGLE-2018-NOVA-01

    NASA Astrophysics Data System (ADS)

    Page, K. L.; Kuin, N. P. M.; Henze, M.

    2018-03-01

    OGLE-2018-NOVA-01, a recurrent nova explosion of Nova LMC 1996, erupted on 2018 Feb 27.07770 UT, but was only discovered and announced on 2018 Mar 08. Observations by the Neil Gehrels Swift Observatory began shortly after, on 2018 Mar 09. UVOT grism data were collected on Mar 09 (day 10.7-10.8 after outburst).

  15. MCNP(TM) Release 6.1.1 beta: Creating and Testing the Code Distribution

    SciTech Connect

    Cox, Lawrence J.; Casswell, Laura

    2014-06-12

    This report documents the preparations for and testing of the production release of MCNP6™1.1 beta through RSICC at ORNL. It addresses tests on supported operating systems (Linux, MacOSX, Windows) with the supported compilers (Intel, Portland Group and gfortran). Verification and Validation test results are documented elsewhere. This report does not address in detail the overall packaging of the distribution. Specifically, it does not address the nuclear and atomic data collection, the other included software packages (MCNP5, MCNPX and MCNP6) and the collection of reference documents.

  16. Nova Superposed on Yavine Corona

    NASA Image and Video Library

    1998-06-04

    The view from NASA's Magellan spacecraft shows a 100-km-wide nova superposed on Yavine Corona. Coronae are roughly circular, volcanic features believed to form over hot upwellings of magma within the Venusian mantle. http://photojournal.jpl.nasa.gov/catalog/PIA00150

  17. NOVA Fall 1998 Teacher's Guide.

    ERIC Educational Resources Information Center

    Colombo, Luann

    This teacher's guide is designed to accompany the PBS television program "NOVA." Six science activities correspond to: (1) "Lost at Sea: The Search for Longitude,, which researches and charts the shortest course to circumnavigate the globe; (2) "Chasing El Nino," which formulates a question and designs an experiment to…

  18. An observational case against nova hibernation

    NASA Technical Reports Server (NTRS)

    Naylor, T.; Charles, P. A.; Mukai, K.; Evans, A.

    1992-01-01

    We use WHT spectroscopy and imaging to show that nova Vul 1670 (= CK Vul) has been incorrectly identified, and thus its luminosity cannot be used as evidence that novae fade into a 'hibernation' phase within 300 yr of their outbursts. INT spectroscopy is used to correct the magnitude of nova Sge 1783 (= WY Sge) for inclination, this result also implying that novae do not fade significantly. We therefore suggest that, while novae decline in the first 60 yr after outburst, thereafter their luminosity remains constant, and they never undergo a 'hibernation' phase. We show that this idea is consistent with the space density of novae and novalike variables, the outburst interval of SS Cyg and the current luminosities of old novae.

  19. Comparison of CdZnTe neutron detector models using MCNP6 and Geant4

    NASA Astrophysics Data System (ADS)

    Wilson, Emma; Anderson, Mike; Prendergasty, David; Cheneler, David

    2018-01-01

    The production of accurate detector models is of high importance in the development and use of detectors. Initially, MCNP and Geant were developed to specialise in neutral particle models and accelerator models, respectively; there is now a greater overlap of the capabilities of both, and it is therefore useful to produce comparative models to evaluate detector characteristics. In a collaboration between Lancaster University, UK, and Innovative Physics Ltd., UK, models have been developed in both MCNP6 and Geant4 of Cadmium Zinc Telluride (CdZnTe) detectors developed by Innovative Physics Ltd. Herein, a comparison is made of the relative strengths of MCNP6 and Geant4 for modelling neutron flux and secondary γ-ray emission. Given the increasing overlap of the modelling capabilities of MCNP6 and Geant4, it is worthwhile to comment on differences in results for simulations which have similarities in terms of geometries and source configurations.

  20. A Patch to MCNP5 for Multiplication Inference: Description and User Guide

    SciTech Connect

    Solomon, Jr., Clell J.

    2014-05-05

    A patch to MCNP5 has been written to allow generation of multiple neutrons from a spontaneous-fission event and generate list-mode output. This report documents the implementation and usage of this patch.

  1. Identifying and quantifying recurrent novae masquerading as classical novae

    SciTech Connect

    Pagnotta, Ashley; Schaefer, Bradley E., E-mail: pagnotta@amnh.org

    2014-06-20

    Recurrent novae (RNe) are cataclysmic variables with two or more nova eruptions within a century. Classical novae (CNe) are similar systems with only one such eruption. Many of the so-called CNe are actually RNe for which only one eruption has been discovered. Since RNe are candidate Type Ia supernova progenitors, it is important to know whether there are enough in our Galaxy to provide the supernova rate, and therefore to know how many RNe are masquerading as CNe. To quantify this, we collected all available information on the light curves and spectra of a Galactic, time-limited sample of 237 CNemore » and the 10 known RNe, as well as exhaustive discovery efficiency records. We recognize RNe as having (1) outburst amplitude smaller than 14.5 – 4.5 × log (t {sub 3}), (2) orbital period >0.6 days, (3) infrared colors of J – H > 0.7 mag and H – K > 0.1 mag, (4) FWHM of Hα > 2000 km s{sup –1}, (5) high excitation lines, such as Fe X or He II near peak, (6) eruption light curves with a plateau, and (7) white dwarf mass greater than 1.2 M {sub ☉}. Using these criteria, we identify V1721 Aql, DE Cir, CP Cru, KT Eri, V838 Her, V2672 Oph, V4160 Sgr, V4643 Sgr, V4739 Sgr, and V477 Sct as strong RN candidates. We evaluate the RN fraction among the known CNe using three methods to get 24% ± 4%, 12% ± 3%, and 35% ± 3%. With roughly a quarter of the 394 known Galactic novae actually being RNe, there should be approximately a hundred such systems masquerading as CNe.« less

  2. Identifying and Quantifying Recurrent Novae Masquerading as Classical Novae

    NASA Astrophysics Data System (ADS)

    Pagnotta, Ashley; Schaefer, Bradley E.

    2014-06-01

    Recurrent novae (RNe) are cataclysmic variables with two or more nova eruptions within a century. Classical novae (CNe) are similar systems with only one such eruption. Many of the so-called CNe are actually RNe for which only one eruption has been discovered. Since RNe are candidate Type Ia supernova progenitors, it is important to know whether there are enough in our Galaxy to provide the supernova rate, and therefore to know how many RNe are masquerading as CNe. To quantify this, we collected all available information on the light curves and spectra of a Galactic, time-limited sample of 237 CNe and the 10 known RNe, as well as exhaustive discovery efficiency records. We recognize RNe as having (1) outburst amplitude smaller than 14.5 - 4.5 × log (t 3), (2) orbital period >0.6 days, (3) infrared colors of J - H > 0.7 mag and H - K > 0.1 mag, (4) FWHM of Hα > 2000 km s-1, (5) high excitation lines, such as Fe X or He II near peak, (6) eruption light curves with a plateau, and (7) white dwarf mass greater than 1.2 M ⊙. Using these criteria, we identify V1721 Aql, DE Cir, CP Cru, KT Eri, V838 Her, V2672 Oph, V4160 Sgr, V4643 Sgr, V4739 Sgr, and V477 Sct as strong RN candidates. We evaluate the RN fraction among the known CNe using three methods to get 24% ± 4%, 12% ± 3%, and 35% ± 3%. With roughly a quarter of the 394 known Galactic novae actually being RNe, there should be approximately a hundred such systems masquerading as CNe.

  3. Identifying and Quantifying Recurrent Novae Masquerading as Classical Novae

    NASA Astrophysics Data System (ADS)

    Pagnotta, Ashley; Schaefer, B. E.

    2014-01-01

    Recurrent novae (RNe) are cataclysmic variables with two or more nova eruptions within a century. Classical novae (CNe) are similar systems with only one such eruption. Many of the so-called ‘CNe’ are actually RNe for which only one eruption has been discovered. Since RNe are candidate Type Ia supernova progenitors, it is important to know whether there are enough in our galaxy to provide the supernova rate, and therefore to know how many RNe are masquerading as CNe. To quantify this, we collected all available information on the light curves and spectra of a time-limited sample of 237 Galactic CNe and the 10 known RNe, as well as exhaustive discovery efficiency records. We recognize RNe as having (a) FWHM of Hα > 2000 km s-1, (b) high excitation lines such as Fe X or He II near peak, (c) eruption light curves with a plateau, (d) infrared colors of J - H > 0.7 mag and H - K > 0.1 mag, (e) orbital period >0.6 days, (f) outburst amplitude smaller than 14.5-4.5×log(t3), and (g) white dwarf mass greater than 1.2M⊙. Using these criteria, we identify V1721 Aql, DE Cir, CP Cru, KT Eri, V838 Her, V2672 Oph, V4160 Sgr, V4643 Sgr, V4739 Sgr, and V477 Sct as strong RN candidates. We evaluate the RN fraction amongst the known CNe using three methods to get 24%±4%, 12%±3%, and 35%. With roughly a quarter of the 394 known novae actually being RNe, there should be approximately a hundred such systems masquerading as CNe.

  4. Nova LMC 2005 - Nova in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Waagen, Elizabeth O.

    2005-11-01

    AAVSO Alert Notice 330 announces the discovery of a nova in the Large Magellanic Cloud - Nova LMC 2005 - by William Liller (Vina del Mar, Chile) at magnitude 11.5 V (Tech Pan film, unfiltered, using a 0.2-m Schmidt camera) on 2005 November 26.164 UT. Peter Nelson (Ellinbank, Victoria, Australia) forwards the following position measured from a CCD image taken by him on November 27.5833 UT: R.A. = 05h 10m 32.68s (2000.0) Decl. = -69o 12' 35.7" (2000.0).Please note that this position is not the one given by B. Allen in IAU Circular 8635; that position is incorrect. A low-resolution spectrogram taken Nov. 28.28 UT by F. M. Walter (Stony Brook University), A. Pasten (CCTIO), and H. E. Bond (STScI) indicates a classical nova near maximum (IAU Circular 8635, ed. D.W.E. Green). Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

  5. Methodology, verification, and performance of the continuous-energy nuclear data sensitivity capability in MCNP6

    SciTech Connect

    Kiedrowski, B. C.; Brown, F. B.

    2013-07-01

    A continuous-energy sensitivity coefficient capability has been introduced into MCNP6. The methods for generating energy-resolved and energy-integrated sensitivity profiles are discussed. Results from the verification exercises that were performed are given, and these show that MCNP6 compares favorably with analytic solutions, direct density perturbations, and comparisons to TSUNAMI-3D and MONK. Run-time and memory requirements are assessed for typical applications, and these are shown to be reasonable with modern computing resources. (authors)

  6. Verification of Unstructured Mesh Capabilities in MCNP6 for Reactor Physics Problems

    SciTech Connect

    Burke, Timothy P.; Martz, Roger L.; Kiedrowski, Brian C.

    2012-08-22

    New unstructured mesh capabilities in MCNP6 (developmental version during summer 2012) show potential for conducting multi-physics analyses by coupling MCNP to a finite element solver such as Abaqus/CAE[2]. Before these new capabilities can be utilized, the ability of MCNP to accurately estimate eigenvalues and pin powers using an unstructured mesh must first be verified. Previous work to verify the unstructured mesh capabilities in MCNP was accomplished using the Godiva sphere [1], and this work attempts to build on that. To accomplish this, a criticality benchmark and a fuel assembly benchmark were used for calculations in MCNP using both the Constructivemore » Solid Geometry (CSG) native to MCNP and the unstructured mesh geometry generated using Abaqus/CAE. The Big Ten criticality benchmark [3] was modeled due to its geometry being similar to that of a reactor fuel pin. The C5G7 3-D Mixed Oxide (MOX) Fuel Assembly Benchmark [4] was modeled to test the unstructured mesh capabilities on a reactor-type problem.« less

  7. AT Cnc: A SECOND DWARF NOVA WITH A CLASSICAL NOVA SHELL

    SciTech Connect

    Shara, Michael M.; Mizusawa, Trisha; Zurek, David

    2012-10-20

    We are systematically surveying all known and suspected Z Cam-type dwarf novae for classical nova shells. This survey is motivated by the discovery of the largest known classical nova shell, which surrounds the archetypal dwarf nova Z Camelopardalis. The Z Cam shell demonstrates that at least some dwarf novae must have undergone classical nova eruptions in the past, and that at least some classical novae become dwarf novae long after their nova thermonuclear outbursts, in accord with the hibernation scenario of cataclysmic binaries. Here we report the detection of a fragmented 'shell', 3 arcmin in diameter, surrounding the dwarf novamore » AT Cancri. This second discovery demonstrates that nova shells surrounding Z Cam-type dwarf novae cannot be very rare. The shell geometry is suggestive of bipolar, conical ejection seen nearly pole-on. A spectrum of the brightest AT Cnc shell knot is similar to that of the ejecta of the classical nova GK Per, and of Z Cam, dominated by [N II] emission. Galaxy Evolution Explorer FUV imagery reveals a similar-sized, FUV-emitting shell. We determine a distance of 460 pc to AT Cnc, and an upper limit to its ejecta mass of {approx}5 Multiplication-Sign 10{sup -5} M {sub Sun }, typical of classical novae.« less

  8. Searching for nova shells around cataclysmic variables

    NASA Astrophysics Data System (ADS)

    Sahman, D. I.; Dhillon, V. S.; Knigge, C.; Marsh, T. R.

    2015-08-01

    We present the results of a search for nova shells around 101 cataclysmic variables (CVs), using H α images taken with the 4.2-m William Herschel Telescope (WHT) and the 2.5-m Isaac Newton Telescope Photometric H α Survey of the Northern Galactic Plane (IPHAS). Both telescopes are located on La Palma. We concentrated our WHT search on nova-like variables, whilst our IPHAS search covered all CVs in the IPHAS footprint. We found one shell out of the 24 nova-like variables we examined. The newly discovered shell is around V1315 Aql and has a radius of ˜2.5 arcmin, indicative of a nova eruption approximately 120 yr ago. This result is consistent with the idea that the high mass-transfer rate exhibited by nova-like variables is due to enhanced irradiation of the secondary by the hot white dwarf following a recent nova eruption. The implications of our observations for the lifetime of the nova-like variable phase are discussed. We also examined four asynchronous polars, but found no new shells around any of them, so we are unable to confirm that a recent nova eruption is the cause of the asynchronicity in the white dwarf spin. We find tentative evidence of a faint shell around the dwarf nova V1363 Cyg. In addition, we find evidence for a light echo around the nova V2275 Cyg, which erupted in 2001, indicative of an earlier nova eruption ˜300 yr ago, making V2275 Cyg a possible recurrent nova.

  9. Gamma Spectroscopy by Artificial Neural Network Coupled with MCNP

    NASA Astrophysics Data System (ADS)

    Sahiner, Huseyin

    While neutron activation analysis is widely used in many areas, sensitivity of the analysis depends on how the analysis is conducted. Even though the sensitivity of the techniques carries error, compared to chemical analysis, its range is in parts per million or sometimes billion. Due to this sensitivity, the use of neutron activation analysis becomes important when analyzing bio-samples. Artificial neural network is an attractive technique for complex systems. Although there are neural network applications on spectral analysis, training by simulated data to analyze experimental data has not been made. This study offers an improvement on spectral analysis and optimization on neural network for the purpose. The work considers five elements that are considered as trace elements for bio-samples. However, the system is not limited to five elements. The only limitation of the study comes from data library availability on MCNP. A perceptron network was employed to identify five elements from gamma spectra. In quantitative analysis, better results were obtained when the neural fitting tool in MATLAB was used. As a training function, Levenberg-Marquardt algorithm was used with 23 neurons in the hidden layer with 259 gamma spectra in the input. Because the interest of the study deals with five elements, five neurons representing peak counts of five isotopes in the input layer were used. Five output neurons revealed mass information of these elements from irradiated kidney stones. Results showing max error of 17.9% in APA, 24.9% in UA, 28.2% in COM, 27.9% in STRU type showed the success of neural network approach in analyzing gamma spectra. This high error was attributed to Zn that has a very long decay half-life compared to the other elements. The simulation and experiments were made under certain experimental setup (3 hours irradiation, 96 hours decay time, 8 hours counting time). Nevertheless, the approach is subject to be generalized for different setups.

  10. Predicting a Luminous Red Nova

    NASA Astrophysics Data System (ADS)

    Van Noord, Daniel; Molnar, Larry; Kinemuchi, Karen; Steenwyk, Steven; Alexander, Cara; Spedden, Chris; Kobulnicky, Henry

    2016-05-01

    Luminous Red Novae (LRN) are rare transient events believed to be caused by the merger of a main sequence contact binary. Since the discovery of the prototype, V838 Mon, only a handful of LRN events have been observed. Tylenda et al. (2011) analyzed the OGLE data preceding the 2008 Novae of V1309 Sco and found that it exhibited a similar light curve to that of a contact binary with one interesting exception, the orbital period of V1309 Sco showed exponential period change going to zero. Unfortunately the system was discovered to be a binary after the merger, preventing any targeted observations to narrow down how the system entered this unusual state. However the extreme period change observed in V1309 Sco gives us a signature to look for in other contact binaries, allowing the discovery of merger candidates for follow up. We will present an analysis of light curves and spectra of KIC 9832227 (NSVS 5597755) that show it is a contact binary system with a negative period derivative that is becoming more extreme with time. These data span more than 15 years and are taken from the NSVS, ASAS, WASP, and Kepler surveys, with ongoing measurements from the Calvin College Observatory and the Apache Point Observatory. The ongoing period change observed in the system is consistent with the exponential model fit from V1309 Sco and the rate of period change has surpassed that of all other measured contact binaries with the exception of V1309 Sco. If the exponential period decay continues the system will likely merge between 2019 and 2022 resulting in a naked eye nova. If this event occurs, this star will present the unprecedented opportunity to study a LRN progenitor and to follow the evolution of the merger.

  11. Simulating Thermonuclear Runaway in Novae

    NASA Astrophysics Data System (ADS)

    Dursi, L. J.; Truran, J.; Zingale, M.; Calder, A. C.; Fryxell, B.; Olson, K.; Ricker, P.; Rosner, R.; Timmes, F. X.; Tufo, H. M.; MacNeice, P.

    2000-12-01

    A nova is a thought to result from a partially degenerate thermonuclear runaway on the surface of a white dwarf. Material from the underlying white dwarf must be dredged up into the atmosphere in order to produce an explosion with the observed energies; the carbon and oxygen serve as catalysts for the hydrogen burning, allowing the much more temperature-sensitive CNO burning to occur. In order to understand this dredge-up problem, we are running two different types of simulations. The first are large-scale simulations with the FLASH code (Fryxell et al., 2000), using a one-dimensional set of initial conditions of a nova about to undergo runaway created by Ami Glasner. These initial conditions have been used in previous multidimensional simulations (Glasner et al. 1997; Kercek et al. 1998), but these simulations have given widely different results because of different mixing behaviors in the two codes. Our set of simulations will shed some light on this discrepancy; since our code has adaptive mesh refinement (MacNeice et al., 2000), we can afford to highly refine the region of the star where the mixing occurs, without the cost of highly refining the entire region. Because these large-scale computations are extremely compute-intensive, they are not appropriate for broad exploration of initial conditions. To do this, we use a One-Dimensional Turbulence (ODT) model which has been used in astrophysical models previously (Niemeyer & Kerstein, 1997). This allows us to use ODT simulations of the nova as experiments to guide us to interesting regimes to study further with multidimensional FLASH code simulations. This work was supported in part by the Department of Energy Grant No. B341495 to the Center for Astrophysical Thermonuclear Flashes at the University of Chicago under the ASCI Strategic Alliances Program and by NASA/Goddard Space Flight Center

  12. Identification of Recurrent Novae in M31

    NASA Astrophysics Data System (ADS)

    Shafter, Allen W.; Rector, T. A.; Schweizer, F.; Bryan, J.

    2014-01-01

    Over roughly the past century a total of more than 900 optical transient events have been recorded in M31, the vast majority of which are believed to represent eruptions of classical novae. The impressive dataset of nova positions put together by Pietsch (http://www.mpe.mpg.de m31novae/opt/m31/) provides the opportunity to search for multiple nova outbursts from the same progenitor system, and thus to characterize the population of recurrent novae (RNe) in M31. In order to identify RNe candidates, we have searched for spatial near coincidences among the 945 recorded novae given in the Pietsch catalog through the end of August 2013. Given that the positions of many of the early novae are quite uncertain, we have set our initial screen to include nova pairs with nominal separations less than or equal to 6 arcsec. We have identified a total of 102 novae that pass this coarse screen. Of these, 78 novae form 39 pairs, 15 form five triples, four novae are part of a quad, and five novae form a quint. As demonstrated by Shafter, Rice and Daub (2009, presented at the "Wild Stars in the Old West II" conference, mintaka.sdsu.edu/faculty/shafter/extragalactic_novae/RNePoster4.pdf), the majority of the 102 novae surviving our initial screen are expected to be associated with chance positional near coincidences (especially near the nucleus), and are not RNe. To decide which candidates are indeed RNe, we have undertaken a study to locate the original discovery plates, CCD images or published finding charts, and to perform the necessary astrometry to identify which of our candidate RNe are chance positional coincidences, and which are RNe. For each candidate, we estimate the probability that the object is a chance positional coincidence as in Shafter et al. (2009). To date, we have been successful in identifying finding charts or original images for most of the candidates, and have found a total of 23 nova outbursts in M31 associated with 10 systems that are almost certainly RNe.

  13. Novae a theoretical and observational study

    NASA Astrophysics Data System (ADS)

    Soraisam, Monika D.

    2016-02-01

    In this thesis, we present studies relating to novae that include both theoretical and ob- servational aspects. Being hosted by accreting white dwarfs (WDs), they have drawn attention in the context of the supernova Ia (SN Ia) progenitor problem. In the case of the nova explosion, the WD host is not disrupted. Instead, it continues to supply energy, even after the optical outbust, via stable nuclear burning of the remnant hydrogen envelope that survived the outburst. Accordingly, nova emission progresses toward the harder part of the electromagnetic spectrum, where it lasts longer than in the optical regime. As a consequence, novae are found to constitute the majority of the observed supersoft X-ray sources (SSSs). This is particularly well established for the galaxy M31. For high mass accretion rates in the unstable nuclear burning regime (or nova regime), there is evidence that significant mass accumulation by the WD is possible. This paved the way for SN Ia progenitor models in the single degenerate (SD) scenario involving novae. Based on the statistics of novae in M31, which is the most frequently used target for nova surveys, we investigate the role that novae may play in producing SNe Ia. Using multicycle nova evolution models and the observationally inferred nova rate in M31, we estimate the maximal SN Ia rate that novae can produce, assuming that all of the involved WDs reach the Chandrasekhar mass. Comparing this rate to the observationally inferred SN Ia rate for M31 constrains the contribution of the nova channel to the SN Ia rate to 2-7%. Additionally, we demonstrate that a more powerful diagnostic can be obtained from statistics of fast novae, which are characterized by decline times t2 10 days. Most novae resulting from a typical SD SN Ia progenitor accreting in the nova regime are fast. Specifically, as the WD in the nova grows in mass, it produces novae more frequently and with decreasing decline times. We therefore investigate how efficiently fast

  14. Terra Nova Bay Polynya, Antarctica

    NASA Technical Reports Server (NTRS)

    2007-01-01

    In Terra Nova Bay, off the Scott Coast of Victoria Land, Antarctica, a large pocket of open water persists throughout most of the Southern Hemisphere winter, even while most of the rest of the Antarctic coastline is firmly embraced by the frozen Southern Ocean. This pocket of open water--a polynya--results from exceptionally strong winds that blow downslope from the Trans-Antarctic Mountains. These fierce katabatic winds drive the sea ice eastward. Since the dominant ice drift pattern in the area is northward, the Drygalski Ice Tongue prevents the bay from being re-populated with sea ice. This image of the Terra Nova Bay polynya was captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite on October 16, 2007. Sea ice sits over the Ross Sea like a cracked and crumbling windshield. Blue-tinged glaciers flow down from the Trans-Antarctic Mountains. Although glaciers can appear blue because of melt water, they can also get that tint when the wind scours and polishes the ice surface. Given the strength of the katabatic winds along this part of the Antarctic coast, it is likely that the blue color of these glaciers is a result of their having been swept clean of snow. The large image has a spatial resolution (level of detail) of 250 meters per pixel.

  15. Shear mixing in classical Novae

    NASA Astrophysics Data System (ADS)

    Alexakis, A.; Calder, A. C.; Dursi, L. J.; Times, F. X.; Truran, J. W.; Rosner, R.; Lamb, D. M.; Mignone, A.; Fryxel, B.; Zingale, M.; Olson, K.; Ricker, P.

    2003-03-01

    The mixing of white dwarf material with the accretion envelope in classical novae scenarios is essential for the later evolution and the outburst. One of the plausible mechanisms for the enrichment involves the coupling of large scale flows like convection or accretion with the breaking interfacial waves at the white dwarf surface. We examine how the interaction of accretion wind with a white dwarf surface can lead to a substantial C/O enrichment that can power a novae. We use the FLASH code to perform two and three dimensional simulations of wind driven gravity waves and investigate their growth and non-linear development for a variety of wind profiles. Our results show that even weak winds generate gravity waves through a resonant mechanism with the wind that grow nonlinear and break leading to spray formation and mixing. The total amount of white dwarf material mixed at late times, is shown to be proportional to the square of the maximum wind velocity, inversely proportional to gravity and independent of the functional form of the wind profile. This work has been supported by the DOE ASCI/Alliances program at the University of Chicago under grant No. B341495.

  16. Hiroshima Air-Over-Ground Analysis: Comparison of DORT and MCNP Calculations

    SciTech Connect

    Santoro, RT

    2001-09-04

    Monte Carlo (MCNP4B) and Discrete Ordinates (DORT) calculations were carried out to estimate {sup 60}Co and {sup 152}Eu activation as a function of ground range due to neutrons emitted from the Hiroshima A-bomb. Results of ORNL DORT and MCNP calculations using RZ cylindrical air-over-ground models are compared with LANL MCNP results obtained with an XYZ air-over-ground model. All of the calculations were carried out using ENDF/B-VI cross-section data and detailed angle and energy resolved neutron emission spectra from the weapon. Favorable agreement was achieved for the {sup 60}Co and {sup 152}Eu activation for ground ranges out to 1000m from themore » three calculations.« less

  17. MCNP benchmark analyses of critical experiments for the Space Nuclear Thermal Propulsion program

    NASA Astrophysics Data System (ADS)

    Selcow, Elizabeth C.; Cerbone, Ralph J.; Ludewig, Hans; Mughabghab, Said F.; Schmidt, Eldon; Todosow, Michael; Parma, Edward J.; Ball, Russell M.; Hoovler, Gary S.

    1993-01-01

    Benchmark analyses have been performed of Particle Bed Reactor (PBR) critical experiments (CX) using the MCNP radiation transport code. The experiments have been conducted at the Sandia National Laboratory reactor facility in support of the Space Nuclear Thermal Propulsion (SNTP) program. The test reactor is a nineteen element water moderated and reflected thermal system. A series of integral experiments have been carried out to test the capabilities of the radiation transport codes to predict the performance of PBR systems. MCNP was selected as the preferred radiation analysis tool for the benchmark experiments. Comparison between experimental and calculational results indicate close agreement. This paper describes the analyses of benchmark experiments designed to quantify the accuracy of the MCNP radiation transport code for predicting the performance characteristics of PBR reactors.

  18. MCNP benchmark analyses of critical experiments for the Space Nuclear Thermal Propulsion program

    NASA Astrophysics Data System (ADS)

    Selcow, E. C.; Cerbone, R. J.; Ludewig, H.; Mughabghab, S. F.; Schmidt, E.; Todosow, M.; Parma, E. J.; Ball, R. M.; Hoovler, G. S.

    Benchmark analyses have been performed of Particle Bed Reactor (PBR) critical experiments (CX) using the MCNP radiation transport code. The experiments have been conducted at the Sandia National Laboratory reactor facility in support of the Space Nuclear Thermal Propulsion (SNTP) program. The test reactor is a nineteen element water moderated and reflected thermal system. A series of integral experiments have been carried out to test the capabilities of the radiation transport codes to predict the performance of PBR systems. MCNP was selected as the preferred radiation analysis tool for the benchmark experiments. Comparison between experimental and calculational results indicate very good agreement. This paper describes the analyses of benchmark experiments designed to quantify the accuracy of the MCNP radiation transport code for predicting the performance characteristics of PBR reactors.

  19. MCNP Capabilities at the Dawn of the 21st Century: Neutron-Gamma Applications

    NASA Astrophysics Data System (ADS)

    Selcow, E. C.; McKinney, G. W.; Booth, T. E.; Briesmeister, J. F.; Cox, L. J.; Forster, R. A.; Hendricks, J. S.; Mosteller, R. D.; Prael, R. E.; Sood, A.; White, S. W.

    The Los Alamos National Laboratory Monte Carlo N-Particle radiation transport code, MCNP, has become an international standard for a wide spectrum of neutron-gamma radiation transport applications. These include nuclear criticality safety, radiation shielding, nuclear safeguards, nuclear oil-well logging, fission and fusion reactor design, accelerator target design, detector design and analysis, health physics, medical radiation therapy and imaging, radiography, decontamination and decommissioning, and waste storage and disposal. The latest version of the code, MCNP4C [1], was released to the Radiation Safety Information Computational Center (RSICC) in February 2000. This paper describes the new features and capabilities of the code, and discusses the specific applicability to neutron-gamma problems. We will also discuss some of the future directions for MCNP code development.

  20. Verification of MCNP simulation of neutron flux parameters at TRIGA MK II reactor of Malaysia.

    PubMed

    Yavar, A R; Khalafi, H; Kasesaz, Y; Sarmani, S; Yahaya, R; Wood, A K; Khoo, K S

    2012-10-01

    A 3-D model for 1 MW TRIGA Mark II research reactor was simulated. Neutron flux parameters were calculated using MCNP-4C code and were compared with experimental results obtained by k(0)-INAA and absolute method. The average values of φ(th),φ(epi), and φ(fast) by MCNP code were (2.19±0.03)×10(12) cm(-2)s(-1), (1.26±0.02)×10(11) cm(-2)s(-1) and (3.33±0.02)×10(10) cm(-2)s(-1), respectively. These average values were consistent with the experimental results obtained by k(0)-INAA. The findings show a good agreement between MCNP code results and experimental results. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. BVRJK observations of Northern Hemisphere old novae

    NASA Technical Reports Server (NTRS)

    Szkody, Paula

    1994-01-01

    BVR photometry has been accomplished for 65 objects in the Duerbeck atlas along with J photometry of 52 and K of 30 objects. The (B - V), (V - R), and (V - J) colors are compiled with those available in the literature to assess the color change of novae as a function of time since outburst. Using available reddening values results in a list of 42 (B - V), 28 (V - R), and 38 (V - J) dereddened colors for novae that are from 1 to 319 years past outburst. The results indicate all the colors cluster about zero, with no obvious transition to red values as would be expected for novae undergoing a hibernation scenario. This indicates the accretion disk is sustained for at least 200 years after outburst. It is also apparent that red novae with giant secondaries and/or unusual properties readily stand out from the normal novae in color.

  2. Automated Searches for Extragalactic Novae

    NASA Astrophysics Data System (ADS)

    Darnley, M. J.

    2005-06-01

    Classical novae (CNe) are interacting binary systems in which the white dwarf undergoes unpredictable explosive outbursts. The energy of a nova outburst is only surpassed by that of gamma-ray bursts, supernovae and a small number of luminous blue variables. However, the outbursts of CNe are far more common than any of these other stars. Due to their brightness and occurrence in both Population I and Population II systems, novae are potentially important as extragalactic distance indicators and tools in the exploration of binary star evolution in galaxies. The POINT-AGAPE survey is an optical search for gravitational micro-lensing events towards the Andromeda galaxy (M31). As well as micro-lensing, the survey is sensitive to many different classes of variable stars and transients, including CNe. In this work we describe the automated detection and selection pipeline used to identify M31 CNe and we present the resulting catalogue of 20 strong CN candidates observed over three seasons. The CNe we discover are observed both in the M31 bulge region as well as over a wide area of the M31 disc. Nine of the CNe are caught during the final rise phase (which is often missed in Galactic novae) and all are well sampled in at least two colours. The excellent light-curve coverage has allowed us to detect and classify CNe over a wide range of speed classes, from very fast to very slow. Among the light curves is, for example, a moderately fast CN exhibiting entry into a deep transition minimum, followed by its final decline. We have also observed in detail a very slow CN which faded by only 0.01 mag day^{-1} over a 150 day period. The CN catalogue constitutes a uniquely well-sampled and objectively-selected data set with which to study the statistical properties of CNe in M31. As a by-product, we have detected other interesting variable objects, including one of the longest period and most luminous Mira variables. An analysis of the MMRD relationship in M31 was performed using the

  3. Analysis of JSI TRIGA MARK II reactor physical parameters calculated with TRIPOLI and MCNP.

    PubMed

    Henry, R; Tiselj, I; Snoj, L

    2015-03-01

    New computational model of the JSI TRIGA Mark II research reactor was built for TRIPOLI computer code and compared with existing MCNP code model. The same modelling assumptions were used in order to check the differences of the mathematical models of both Monte Carlo codes. Differences between the TRIPOLI and MCNP predictions of keff were up to 100pcm. Further validation was performed with analyses of the normalized reaction rates and computations of kinetic parameters for various core configurations. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Nova Scotia Fetal Risk Project

    PubMed Central

    Hebb, Michael; Macpherson, Iain; Cudmore, Douglas; Scott, Kenneth; Weldon, Lawrence; Smart, Marilyn; Ley, Elsie

    1980-01-01

    Family physicians delivering obstetrical care in Nova Scotia were invited to participate in a fetal risk project, conducted from 1971 to 1975. Thirty percent of the physicians participated, and data were collected on 17,270 patients, using the Goodwin, Dunne and Thomas4 fetal risk scoring system. Patients scoring four to ten on the entire system accounted for 60% of stillbirths and 68% of neonatal deaths; when the 68% of neonatal deaths; when the non-gestational portion alone was used, patients scoring three to six accounted for 52% of stillbirths and 57% of neonatal deaths. When the scoring system was altered, patients scoring three to six accounted for 61% of stillbirths and 62% of neonatal deaths. Patients of participants did not appear to fare better than those of non-participants. PMID:20469319

  5. Circumstellar Dust in Symbiotic Novae

    NASA Astrophysics Data System (ADS)

    Jurkic, T.; Kotnik-Karuza, D.

    2015-12-01

    We present a model of inner dust regions around the cool Mira component of the two symbiotic novae, RR Tel and HM Sge, based on the near-IR photometry, ISO spectra and mid-IR interferometry. The dust properties were determined using the DUSTY code. A compact circumstellar silicate dust shell with inner dust shell temperatures between 900 K and 1300 K and of moderate optical depth can explain all the observations. RR Tel shows the presence of an equatorially enhanced dust density during minimum obscuration. Obscuration events are explained by an increase in optical depth caused by the newly condensed dust. The mass loss rates are significantly higher than in intermediate-period single Miras but in agreement with longer-period O-rich AGB stars.

  6. Nova V2214 Ophiuchi 1988 - A magnetic nova inside the period gap

    NASA Technical Reports Server (NTRS)

    Baptista, R.; Jablonski, F. J.; Cieslinski, D.; Steiner, J. E.

    1993-01-01

    The discovery of a coherent photometric modulation in Nova Oph 1988 with period 0.117515 +/- 0.000002 d, which is associated with the orbital period of the underlying binary, is reported. On the basis of photometric observations, it is concluded that Nova V2214 Oph 1988 is a magnetic nova with an orbital period inside the period gap. The inclusion of this system in the statistics of novae suggests that there is no period gap for novae and that there is a clear correlation between the occurrence of novae with short orbital periods and the presence of magnetic white dwarfs. It is suggested that funneling of the accretion flow onto the magnetic poles favors the conditions for a thermonuclear runaway, increasing the frequency of eruptions for magnetic systems.

  7. TORT/MCNP coupling method for the calculation of neutron flux around a core of BWR.

    PubMed

    Kurosawa, Masahiko

    2005-01-01

    For the analysis of BWR neutronics performance, accurate data are required for neutron flux distribution over the In-Reactor Pressure Vessel equipments taking into account the detailed geometrical arrangement. The TORT code can calculate neutron flux around a core of BWR in a three-dimensional geometry model, but has difficulties in fine geometrical modelling and lacks huge computer resource. On the other hand, the MCNP code enables the calculation of the neutron flux with a detailed geometry model, but requires very long sampling time to give enough number of particles. Therefore, a TORT/MCNP coupling method has been developed to eliminate the two problems mentioned above in each code. In this method, the TORT code calculates angular flux distribution on the core surface and the MCNP code calculates neutron spectrum at the points of interest using the flux distribution. The coupling method will be used as the DOT-DOMINO-MORSE code system. This TORT/MCNP coupling method was applied to calculate the neutron flux at points where induced radioactivity data were measured for 54Mn and 60Co and the radioactivity calculations based on the neutron flux obtained from the above method were compared with the measured data.

  8. Evaluation of the AP1000 delayed neutron parameters using MCNP6

    NASA Astrophysics Data System (ADS)

    Sembiring, T. M.; Susilo, J.; Pinem, S.

    2018-02-01

    The MCNP6 code contains numerous features, one of those is to determine the delayed neutron parameters. The accuracy of calculated delayed neutron parameters affect the accuracy of transient or dynamic condition. The objective of this paper is to determine the delayed neutron parameters of the advance PWR reactor, AP1000, using MCNP6 code with the recent ENDF/B evaluated nuclear data file ENDF/B-VII.1. The MCNP6 calculation results shows that the maximum difference occurred in the βi and λi parameters are 38.30% and 45.63%, respectively. The superiority of MCNP6 can be seen in the change of prompt neutron life time (ℓ) parameters that cannot be obtained by the deterministic code, so it can be used in the sensitivity analysis of the delayed neutron parameters. Based on this research work, the accident analysis of the AP1000 reactor use the effective delayed neutron fraction (β eff) of0.0051 and the prompt neutron life time (ℓ) of 19.5 μs for the first cycle.

  9. Validation of the MCNP computational model for neutron flux distribution with the neutron activation analysis measurement

    NASA Astrophysics Data System (ADS)

    Tiyapun, K.; Chimtin, M.; Munsorn, S.; Somchit, S.

    2015-05-01

    The objective of this work is to demonstrate the method for validating the predication of the calculation methods for neutron flux distribution in the irradiation tubes of TRIGA research reactor (TRR-1/M1) using the MCNP computer code model. The reaction rate using in the experiment includes 27Al(n, α)24Na and 197Au(n, γ)198Au reactions. Aluminium (99.9 wt%) and gold (0.1 wt%) foils and the gold foils covered with cadmium were irradiated in 9 locations in the core referred to as CT, C8, C12, F3, F12, F22, F29, G5, and G33. The experimental results were compared to the calculations performed using MCNP which consisted of the detailed geometrical model of the reactor core. The results from the experimental and calculated normalized reaction rates in the reactor core are in good agreement for both reactions showing that the material and geometrical properties of the reactor core are modelled very well. The results indicated that the difference between the experimental measurements and the calculation of the reactor core using the MCNP geometrical model was below 10%. In conclusion the MCNP computational model which was used to calculate the neutron flux and reaction rate distribution in the reactor core can be used for others reactor core parameters including neutron spectra calculation, dose rate calculation, power peaking factors calculation and optimization of research reactor utilization in the future with the confidence in the accuracy and reliability of the calculation.

  10. Using NJOY to Create MCNP ACE Files and Visualize Nuclear Data

    SciTech Connect

    Kahler, Albert Comstock

    2016-10-14

    We provide lecture materials that describe the input requirements to create various MCNP ACE files (Fast, Thermal, Dosimetry, Photo-nuclear and Photo-atomic) with the NJOY Nuclear Data Processing code system. Input instructions to visualize nuclear data with NJOY are also provided.

  11. CCD observations of old nova fields

    NASA Technical Reports Server (NTRS)

    Downes, Ronald A.; Szkody, Paula

    1989-01-01

    The discovery of CK Vulpeculae (Nova 1670) has prompted a major review of ideas concerning the long-term development of novae. Unfortunately, there are very few recovered novae old enough to provide confirmation (or rejection) of the new 'hibernation' scenario. CCD images of seven old nova fields, and R band photometry for four fields, have been obtained in an attempt to recover these objects in quiescence. A strong candidate for U Leonis, and a possible counterpart for T Bootis, are found. For three other fields, weak candidates have been found. Finding charts and colors are presented for the seven fields observed. The R light curves of U Leo, indicating an orbital period of 192.5 or 385.0 min, are shown.

  12. Old Novae and the SW Sextantis Phenomenon

    NASA Astrophysics Data System (ADS)

    Schmidtobreick, L.; Tappert, C.

    2014-12-01

    From a large observing campaign, we found that nearly all non- or weakly magnetic cataclysmic variables (CVs) in the orbital period range between 2.8 and 4 hours are of SW Sex type and as such experience very high mass transfer rates. The exceptions seem to be some old novae that have periods around 3.5 h. Their spectra do not show the typical SW Sex characteristics but rather resemble those of dwarf novae with low mass transfer rates. The presence of old novae in this period range of SW Sex stars that do not follow the trend but show instead rather low mass transfer rates is interpreted as evidence for an effect of the nova eruption on the mass transfer rate of the underlying CV similar to the hibernation scenario.

  13. Dust formation in Nova Del 2013

    NASA Astrophysics Data System (ADS)

    Shenavrin, V. I.; Taranova, O. G.; Tatarnikov, A. M.

    2013-09-01

    We present the result of the IR photometry of Nova Del 2013 obtained at the Crimean Station (Nauchny, Ukraine) of the Sternberg Astronomical Institute. JHKLM photometry was carried out with 125-cm telescope using a InSb-photometer on:

  14. High-energy observations of novae

    NASA Astrophysics Data System (ADS)

    Osborne, J.

    2014-07-01

    I will review the lessons learned from the last few years of high-energy observations of classical and recurrent novae. Some observations have reinforced previous ideas (such as ejecta dispersion revealing the hot white dwarf, and ejecta shocks), while others have revealed new behaviours still in the process of being understood. XMM-Newton, Chandra, Swift and Fermi have led the way, MAXI and Suzaku have also contributed. Novae in our own Galaxy can be studied in great detail, and M31 provides a wonderful nova-rich laboratory. The mass of the white dwarf appears to dominate many aspects of nova outbursts, the density of a companion star wind is another significant variable. Even so, there remain very high energy gamma-rays, short period QPOs, and an early soft X-ray phase of huge variability with no obvious correlates or very convincing models.

  15. Circumstellar dust in symbiotic novae

    NASA Astrophysics Data System (ADS)

    Jurkic, Tomislav; Kotnik-Karuza, Dubravka

    2015-08-01

    Physical properties of the circumstellar dust and associated physical mechanisms play an important role in understanding evolution of symbiotic binaries. We present a model of inner dust regions around the cool Mira component of the two symbiotic novae, RR Tel and HM Sge, based on the long-term near-IR photometry, infrared ISO spectra and mid-IR interferometry. Pulsation properties and long-term variabilities were found from the near-IR light curves. The dust properties were determined using the DUSTY code which solves the radiative transfer. No changes in pulsational parameters were found, but a long-term variations with periods of 20-25 years have been detected which cannot be attributed to orbital motion.Circumstellar silicate dust shell with inner dust shell temperatures between 900 K and 1300 K and of moderate optical depth can explain all the observations. RR Tel showed the presence of an optically thin CS dust envelope and an optically thick dust region outside the line of sight, which was further supported by the detailed modelling using the 2D LELUYA code. Obscuration events in RR Tel were explained by an increase in optical depth caused by the newly condensed dust leading to the formation of a compact dust shell. HM Sge showed permanent obscuration and a presence of a compact dust shell with a variable optical depth. Scattering of the near-IR colours can be understood by a change in sublimation temperature caused by the Mira variability. Presence of large dust grains (up to 4 µm) suggests an increased grain growth in conditions of increased mass loss. The mass loss rates of up to 17·10-6 MSun/yr were significantly higher than in intermediate-period single Miras and in agreement with longer-period O-rich AGB stars.Despite the nova outburst, HM Sge remained enshrouded in dust with no significant dust destruction. The existence of unperturbed dust shell suggests a small influence of the hot component and strong dust shielding from the UV flux. By the use

  16. X-ray Novae and Related Systems

    NASA Technical Reports Server (NTRS)

    Wheeler, J. Craig; Kim, Soonwook; Mineshige, Shin

    1992-01-01

    Accretion disk thermal instability models have been successful in accounting for the basic observations of dwarf novae and the steady behavior of nova-like systems. Models for the dwarf-nova like variability of the old nova and intermediate polar GK Per give good agreement with the burst amplitude, profile and recurrence time in the optical and UV. A month-long 'precursor plateau' in the UV is predicted for the expected 1992 outburst prior to the rise to maximum in the optical and UV. The models for the time scales of the outbursts and corresponding UV spectra at maximum are consistent with the inner edge of the accretion disk being essentially constant between quiescence and outburst and a factor of four larger than the co-rotation radius. These conclusions represent a challenge to the standard theory of magnetic accretion. Disk instability models have also given a good representation of the soft X-ray and optical outbursts of the X-ray novae A0620-00 and GS2000+25. Formation of coronae above the disk, heated by magneto-acoustic flux from the disk, may account for the temporal and spectral properties of the hard X-ray and gamma ray emission of related sources such as Cyg X-1, GS 2023+33 (V404 Cyg), IE 1740.7-2942 (the 'Galactic Center' Einstein Source), and GS 1124-683 (Nova Muscae).

  17. A nova outburst powered by shocks

    NASA Astrophysics Data System (ADS)

    Li, Kwan-Lok; Metzger, Brian D.; Chomiuk, Laura; Vurm, Indrek; Strader, Jay; Finzell, Thomas; Beloborodov, Andrei M.; Nelson, Thomas; Shappee, Benjamin J.; Kochanek, Christopher S.; Prieto, José L.; Kafka, Stella; Holoien, Thomas W.-S.; Thompson, Todd A.; Luckas, Paul J.; Itoh, Hiroshi

    2017-10-01

    Classical novae are runaway thermonuclear burning events on the surfaces of accreting white dwarfs in close binary star systems, sometimes appearing as new naked-eye sources in the night sky1. The standard model of novae predicts that their optical luminosity derives from energy released near the hot white dwarf, which is reprocessed through the ejected material2-5. Recent studies using the Fermi Large Area Telescope have shown that many classical novae are accompanied by gigaelectronvolt γ-ray emission6,7. This emission likely originates from strong shocks, providing new insights into the properties of nova outflows and allowing them to be used as laboratories for the study of the unknown efficiency of particle acceleration in shocks. Here, we report γ-ray and optical observations of the Milky Way nova ASASSN-16ma, which is among the brightest novae ever detected in γ-rays. The γ-ray and optical light curves show a remarkable correlation, implying that the majority of the optical light comes from reprocessed emission from shocks rather than the white dwarf8. The ratio of γ-ray to optical flux in ASASSN-16ma directly constrains the acceleration efficiency of non-thermal particles to be around 0.005, favouring hadronic models for the γ-ray emission9. The need to accelerate particles up to energies exceeding 100 gigaelectronvolts provides compelling evidence for magnetic field amplification in the shocks.

  18. Models for various aspects of dwarf novae and nova-like stars

    NASA Technical Reports Server (NTRS)

    Ladous, Constanze

    1993-01-01

    The first attempts to explain the nature of dwarf novae were based on the assumption of single-star phenomena, in which emission lines were assumed to be caused by circumstellar gas shells. The outburst behavior was tentatively ascribed to the kind of (also not understood) mechanism leading to nova outbursts. The realization that some, and possibly all, dwarf novae and nova-like stars (and novae) are binaries eventually led to models which bore more and more similarities to the modern interpretation on the basis of the Roche model. Not all cataclysmic variables are known binaries. In fact, with respect to the entire number of known objects, the proven binaries are still the minority, but all the brightest variables are in fact known to binaries. Not a single system is known which exhibits the usual characteristics of a cataclysmic variable and at the same time can be declared with certainty to be a single star. Two systems are known, the dwarf nova EY Cyg and the recurrent nova V1017 Sgr, in which, in spite of intensive search, no radial velocity variations have been found; but they still exhibit composite spectra consisting of a bright continuum, an emission spectrum, and a cool absorption spectrum. If the Roche model is correct, it is to be expected that a small percentage of objects is viewed pole-on, so orbital motions do not make themselves felt as Doppler shifts of spectral lines. So even these two systems support the hypothesis that all cataclysmic variables (with the possible exception of symbiotic stars) are binaries. In cataclysmic variables, it seems that the brightness changes observed in dwarf novae and nova-like stars in the optical and the UV are due directly to changes in the accretion disks. The study and understanding of accretion disks in these systems can bear potentially valuable consequences for many other fields in astronomy. The observed spectra of dwarf novae and nova-like stars comprise a fairly large range: pure emission spectra, pure

  19. When does an old nova become a dwarf nova? Kinematics and age of the nova shell of the dwarf nova AT Cancri

    NASA Astrophysics Data System (ADS)

    Shara, Michael M.; Drissen, Laurent; Martin, Thomas; Alarie, Alexandre; Stephenson, F. Richard

    2017-02-01

    The Z Cam-type dwarf nova AT Cancri (AT Cnc) displays a classical nova (CN) shell, demonstrating that mass transfer in cataclysmic binaries decreases substantially after a CN eruption. The hibernation scenario of cataclysmic binaries predicts such a decrease, on a time-scale of a few centuries. In order to measure the time since AT Cnc's last CN eruption, we have measured the radial velocities of a hundred clumps in its ejecta with SITELLE, Canada-France-Hawaii Telescope's recently commissioned imaging Fourier transform spectrometer. These range from -455 to +490 km s-1. Coupled with the known distance to AT Cnc of 460 pc, the size of AT Cnc's shell, and a simple model of nova ejecta deceleration, we determine that the last CN eruption of this system occurred 330_{-90}^{+135} yr ago. This is the most rapid transition from a high mass-transfer rate, nova-like variable to a low mass-transfer rate, dwarf nova yet measured, and in accord with the hibernation scenario of cataclysmic binaries. We conclude by noting the similarity in the deduced outburst date (within a century of 1686 CE) of AT Cnc to a `guest star' reported in the constellation Cancer by Korean observers in 1645 CE.

  20. Convection and Mixing in Classical Novae Precursors

    NASA Astrophysics Data System (ADS)

    Dursi, L. J.; Calder, A. C.; Alexakis, A.; Truran, J. W.; Zingale, M.; Times, F. X.; Ricker, P. M.; Fryxell, B.; Olson, K.; Rosner, R.; MacNeice, P.

    2002-06-01

    To explain observed abundances from classical nova outbursts, and to help explain their energetics, nova models must incorporate a mechanism that will dredge up the heavier white dwarf material into the lighter accreted atmosphere. One proposed mechanism relies on the fluid motions from an early convective phase to do the mixing. We present recent work investigating two aspects of this mechanism. We examine results from two-dimensional simulations of classical nova precursor models that demonstrate the beginning of a convective phase during the `simmering' of a nova precursor. We use a new hydrostatic equilibrium hydrodynamics module recently developed for the adaptive-mesh code FLASH. The two-dimensional models are based on the one-dimensional models of Ami Glasner (Glasner et al. 1997), and were evolved with FLASH from a pre-convective state to the onset of convection. The onset of convection induces a velocity field near the C,O/H,He interface, which can then cause mixing through interactions with gravity waves. We show results from simulations of these wind-wave interactions, and estimate whether the `wind' caused by the convection could induce sufficient dredge-up to power a classical novae. This research has been supported by the US. Department of Energy under grant no. B341495 to the ASCI Flash Center at the University of Chicago

  1. The Neon Nova. III. The Infrared Light Curves of Nova QU Vulpeculae (Nova VUL 1984#2)

    NASA Astrophysics Data System (ADS)

    Gehrz, R. D.; Jones, T. J.; Matthews, K.; Neugebauer, G.; Woodward, C. E.; Hayward, T. L.; Greenhouse, M. A.

    1995-07-01

    We report 1.25 to 19.5 μm broadband infrared (IR) photometric measurements acquired during an eight year period on the prototypical ONeMg "neon nova" QU Vulpeculae (Nova Vul 1984 #2). The energy distribution of the ejecta evolved through several phases. An early free-free emission phase was followed by an IR coronal phase characterized by the appearance of strong emission lines from forbidden atomic transitions. The lines of [Ne VI] at 7.6 μm, and [Ne II] at 12.8 μm were especially strong during the coronal phase. A small amount of silicate dust condensed in the ejecta after about a year. The evidence provided by our IR observations for high abundances of metals in the ejecta of QU Vul is reviewed. We present the IR light curves of QU Vul, and show that the temporal development of its persistent IR coronal emission phase was evident in the broadband K (2.3 μm) and L (3.6 μm) photometry. Using data from our previous studies of classical novae, we suggest that K and L photometry can distinguish between the slower ONeMg novae with persistent IR coronal activity and CO novae that produce copious quantities of circumstellar dust. The most striking signature is produced in the L band, which contains emission from [Mg VIII] at 3.02 m, [Al VI] at 3.66 μm, and [Si IX] at 3.92 μm. We comment on the peculiar tendency of the IR light curves of novae to decay exponentially.

  2. Using the MCNP Taylor series perturbation feature (efficiently) for shielding problems

    NASA Astrophysics Data System (ADS)

    Favorite, Jeffrey

    2017-09-01

    The Taylor series or differential operator perturbation method, implemented in MCNP and invoked using the PERT card, can be used for efficient parameter studies in shielding problems. This paper shows how only two PERT cards are needed to generate an entire parameter study, including statistical uncertainty estimates (an additional three PERT cards can be used to give exact statistical uncertainties). One realistic example problem involves a detailed helium-3 neutron detector model and its efficiency as a function of the density of its high-density polyethylene moderator. The MCNP differential operator perturbation capability is extremely accurate for this problem. A second problem involves the density of the polyethylene reflector of the BeRP ball and is an example of first-order sensitivity analysis using the PERT capability. A third problem is an analytic verification of the PERT capability.

  3. Validation of MCNP: SPERT-D and BORAX-V fuel

    SciTech Connect

    Crawford, C.; Palmer, B.

    1992-11-01

    This report discusses critical experiments involving SPERT-D[sup 1,2] fuel elements and BORAX-V[sup 3-8] fuel which have been modeled and calculations performed with MCNP. MCNP is a Monte Carlo based transport code. For this study continuous-energy nuclear data from the ENDF/B-V cross section library was used. The SPERT-D experiments consisted of various arrays of fuel elements moderated and reflected with either water or a uranyl nitrate solution. Some SPERT-D experiments used cadmium as a fixed neutron poison, while others were poisoned with various concentrations of boron in the moderating/reflecting solution. ne BORAX-V experiments were arrays of either boiling fuel rod assembliesmore » or superheater assemblies, both types of arrays were moderated and reflected with water. In one boiling fuel experiment, two fuel rods were replaced with borated stainless steel poison rods.« less

  4. Validation of MCNP: SPERT-D and BORAX-V fuel

    SciTech Connect

    Crawford, C.; Palmer, B.

    1992-11-01

    This report discusses critical experiments involving SPERT-D{sup 1,2} fuel elements and BORAX-V{sup 3-8} fuel which have been modeled and calculations performed with MCNP. MCNP is a Monte Carlo based transport code. For this study continuous-energy nuclear data from the ENDF/B-V cross section library was used. The SPERT-D experiments consisted of various arrays of fuel elements moderated and reflected with either water or a uranyl nitrate solution. Some SPERT-D experiments used cadmium as a fixed neutron poison, while others were poisoned with various concentrations of boron in the moderating/reflecting solution. ne BORAX-V experiments were arrays of either boiling fuel rod assembliesmore » or superheater assemblies, both types of arrays were moderated and reflected with water. In one boiling fuel experiment, two fuel rods were replaced with borated stainless steel poison rods.« less

  5. MCNPX{trademark} -- The LAHET{trademark}/MCNP{trademark} code merger

    SciTech Connect

    Hughes, H.G.; Adams, K.J.; Chadwick, M.B.

    1997-08-01

    The MCNP code is written and maintained by Group X-TM at Los Alamos National Laboratory. In response to the demands of the accelerator community, the authors have undertaken a major effort to expand the capabilities of MCNP to increase the set of transportable particles; to make use of newly evaluated high-energy nuclear data tables for neutrons, protons, and potentially other particles; and to incorporate physics models for use where tabular data are unavailable. A preliminary version of the expanded code, called MCNPX, has now been issued for testing. The new code includes all existing LAHET physics modules, and has themore » ability to utilize the 150-MeV data libraries that have recently been released by LANL Group T-2.« less

  6. Nova Discovery Efficiency 1890-2014; Only 43%±6% of the Brightest Nova Are Discovered

    NASA Astrophysics Data System (ADS)

    Schaefer, Bradley E.

    2014-06-01

    Galactic nova discovery has always been the domain of the best amateur astronomers, with the only substantial exception being the use of the Harvard plates from 1890-1947. (Modern CCD surveys have not produced any significant nova discoveries.) From 1890-1946, novae were discovered by gentlemen who deeply knew the stars in the sky and who checked for new stars on every clear night. This all changed when war surplus binoculars became commonly available, so the various organizations (e.g., AAVSO, BAA) instructed their hunters to use binoculars to regularly search small areas of the Milky Way. In the 1970s the hunters largely switched to blinking photographs, while they switched to CCD images in the 1990s, all exclusively in Milky Way regions. Currently, most hunters use 'go-to' scopes to look deeply only in the Milky Way, use weekly or monthly cadences, never go outside to look up at the light-polluted skies, and do not have the stars memorized at all. This situation is good for catching many faint novae, but is inefficient for catching the more isotropic and systematically-fast bright novae.I have made an exhaustive analysis of all known novae to isolate the effects on the relative discovery efficiency as a function of decade, the elongation from the Sun, the Moon's phase, the declination, the peak magnitude, and the duration of the peak. For example, the relative efficiency for novae south of declination -33° is 0.5 before 1953, 0.2 from 1953-1990, and 0.8 after 1990. My analysis gives the overall discovery efficiency to be 43%±6%, 30%, 22%, 12%, and 6% for novae peaking brighter than 2, 4, 6, 8, and 10 mag. Thus, the majority of first magnitude novae are being missed. The bright novae are lost because they are too close to the Sun, in the far south, and/or very fast. This is illustrated by the discovery rate for Vpeak<2 novae being once every five years before 1946, yet only one such nova (V1500 Cyg) has been seen in the last 68 years. A critical consequence of

  7. An investigation of MCNP6.1 beryllium oxide S(α, β) cross sections

    DOE PAGES

    Sartor, Raymond F.; Glazener, Natasha N.

    2016-03-08

    In MCNP6.1, materials are constructed by identifying the constituent isotopes (or elements in a few cases) individually. This list selects the corresponding microscopic cross sections calculated from the free-gas model to create the material macroscopic cross sections. Furthermore, the free-gas model and the corresponding material macroscopic cross sections assume that the interactions of atoms do not affect the nuclear cross sections.

  8. Validation and verification of MCNP6 against intermediate and high-energy experimental data and results by other codes

    SciTech Connect

    Mashnik, Stepan G

    2010-11-22

    MCNP6, the latest and most advanced LANL transport code representing a recent merger of MCNP5 and MCNPX, has been Validated and Verified (V and V) against a variety of intermediate and high-energy experimental data and against results by different versions of MCNPX and other codes. In the present work, we V andV MCNP6 using mainly the latest modifications of the Cascade-Exciton Model (CEM) and of the Los Alamos version of the Quark-Gluon String Model (LAQGSM) event generators CEM03.02 and LAQGSM03.03. We found that MCNP6 describes reasonably well various reactions induced by particles and nuclei at incident energies from 18 MeVmore » to about 1 TeV per nucleon measured on thin and thick targets and agrees very well with similar results obtained with MCNPX and calculations by CEM03.02, LAQGSM03.01 (03.03), INCL4 + ABLA, and Bertini INC + Dresner evaporation, EPAX, ABRABLA, HIPSE, and AMD, used as stand alone codes. Most of several computational bugs and more serious physics problems observed in MCNP6/X during our V and V have been fixed; we continue our work to solve all the known problems before MCNP6 is distributed to the public.« less

  9. Simulation of the GCR spectrum in the Mars curiosity rover's RAD detector using MCNP6.

    PubMed

    Ratliff, Hunter N; Smith, Michael B R; Heilbronn, Lawrence

    2017-08-01

    The paper presents results from MCNP6 simulations of galactic cosmic ray (GCR) propagation down through the Martian atmosphere to the surface and comparison with RAD measurements made there. This effort is part of a collaborative modeling workshop for space radiation hosted by Southwest Research Institute (SwRI). All modeling teams were tasked with simulating the galactic cosmic ray (GCR) spectrum through the Martian atmosphere and the Radiation Assessment Detector (RAD) on-board the Curiosity rover. The detector had two separate particle acceptance angles, 4π and 30 ° off zenith. All ions with Z = 1 through Z = 28 were tracked in both scenarios while some additional secondary particles were only tracked in the 4π cases. The MCNP6 4π absorbed dose rate was 307.3 ± 1.3 µGy/day while RAD measured 233 µGy/day. Using the ICRP-60 dose equivalent conversion factors built into MCNP6, the simulated 4π dose equivalent rate was found to be 473.1 ± 2.4 µSv/day while RAD reported 710 µSv/day. Copyright © 2017 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.

  10. Characteristics of Multihole Collimator Gamma Camera Simulation Modeled Using MCNP5

    NASA Astrophysics Data System (ADS)

    Saripan, M. I.; Hashim, S.; Mashohor, S.; Adnan, W. A. Wan; Marhaban, M. H.

    2008-05-01

    This paper describes the characteristics of the multihole collimator gamma camera that is simulated using the combination of the Monte Carlo N-Particles Code (MCNP) version 5 and in-house software. The model is constructed based on the GCA-7100A Toshiba Gamma Camera at the Royal Surrey County Hospital, Guildford, Surrey, UK. The characteristics are analyzed based on the spatial resolution of the images detected by the Sodium Iodide (NaI) detector. The result is recorded in a list-mode file referred to as a PTRAC file within MCNP5. All pertinent nuclear reaction mechanisms, such as Compton and Rayleigh scattering and photoelectric absorption are undertaken by MCNP5 for all materials encountered by each photon. The experiments were conducted on Tl-201, Co-57, Tc-99 m and Cr-51 radio nuclides. The comparison of full width half maximum value of each datasets obtained from experimental work, simulation and literature are also reported in this paper. The relationship of the simulated data is in agreement with the experimental results and data obtained in the literature. A careful inspection at each of the data points of the spatial resolution of Tc-99 m shows a slight discrepancy between these sets. However, the difference is very insignificant, i.e. less than 3 mm only, which corresponds to a size of less than 1 pixel only (of the segmented detector).

  11. MCNP6 Simulation of Reactions of Interest to FRIB, Medical, and Space Applications

    NASA Astrophysics Data System (ADS)

    Mashnik, Stepan G.

    The latest production-version of the Los Alamos Monte Carlo N-Particle transport code MCNP6 has been used to simulate a variety of particle-nucleus and nucleus-nucleus reactions of academic and applied interest to research subjects at the Facility for Rare Isotope Beams (FRIB), medical isotope production, space-radiation shielding, cosmic-ray propagation, and accelerator applications, including several reactions induced by radioactive isotopes, analyzing production of both stable and radioactive residual nuclei. Here, we discuss examples of validation and verification of MCNP6 by comparing with recent neutron spectra measured at the Heavy Ion Medical Accelerator in Chiba, Japan; spectra of light fragments from several reactions measured recently at GANIL, France; INFN Laboratori Nazionali del Sud, Catania, Italy; COSY of the Jülich Research Center, Germany; and cross sections of products from several reactions measured lately at GSI, Darmstadt, Germany; ITEP, Moscow, Russia; and, LANSCE, LANL, Los Alamos, U.S.A. As a rule, MCNP6 provides quite good predictions for most of the reactions we analyzed so far, allowing us to conclude that it can be used as a reliable and useful simulation tool for various applications for FRIB, medical, and space applications involving stable and radioactive isotopes.

  12. Evaluation of the Pool Critical Assembly Benchmark with Explicitly-Modeled Geometry using MCNP6

    SciTech Connect

    Kulesza, Joel A.; Martz, Roger Lee

    2017-03-01

    Despite being one of the most widely used benchmarks for qualifying light water reactor (LWR) radiation transport methods and data, no benchmark calculation of the Oak Ridge National Laboratory (ORNL) Pool Critical Assembly (PCA) pressure vessel wall benchmark facility (PVWBF) using MCNP6 with explicitly modeled core geometry exists. As such, this paper provides results for such an analysis. First, a criticality calculation is used to construct the fixed source term. Next, ADVANTG-generated variance reduction parameters are used within the final MCNP6 fixed source calculations. These calculations provide unadjusted dosimetry results using three sets of dosimetry reaction cross sections of varyingmore » ages (those packaged with MCNP6, from the IRDF-2002 multi-group library, and from the ACE-formatted IRDFF v1.05 library). These results are then compared to two different sets of measured reaction rates. The comparison agrees in an overall sense within 2% and on a specific reaction- and dosimetry location-basis within 5%. Except for the neptunium dosimetry, the individual foil raw calculation-to-experiment comparisons usually agree within 10% but is typically greater than unity. Finally, in the course of developing these calculations, geometry that has previously not been completely specified is provided herein for the convenience of future analysts.« less

  13. Simulation of the GCR spectrum in the Mars curiosity rover's RAD detector using MCNP6

    NASA Astrophysics Data System (ADS)

    Ratliff, Hunter N.; Smith, Michael B. R.; Heilbronn, Lawrence

    2017-08-01

    The paper presents results from MCNP6 simulations of galactic cosmic ray (GCR) propagation down through the Martian atmosphere to the surface and comparison with RAD measurements made there. This effort is part of a collaborative modeling workshop for space radiation hosted by Southwest Research Institute (SwRI). All modeling teams were tasked with simulating the galactic cosmic ray (GCR) spectrum through the Martian atmosphere and the Radiation Assessment Detector (RAD) on-board the Curiosity rover. The detector had two separate particle acceptance angles, 4π and 30 ° off zenith. All ions with Z = 1 through Z = 28 were tracked in both scenarios while some additional secondary particles were only tracked in the 4π cases. The MCNP6 4π absorbed dose rate was 307.3 ± 1.3 μGy/day while RAD measured 233 μGy/day. Using the ICRP-60 dose equivalent conversion factors built into MCNP6, the simulated 4π dose equivalent rate was found to be 473.1 ± 2.4 μSv/day while RAD reported 710 μSv/day.

  14. Nonradial Pulsations in Post-outburst Novae

    NASA Astrophysics Data System (ADS)

    Wolf, William M.; Townsend, Richard H. D.; Bildsten, Lars

    2018-03-01

    After an optical peak, a classical or recurrent nova settles into a brief (days to years) period of quasi-stable thermonuclear burning in a compact configuration nearly at the white dwarf (WD) radius. During this time, the underlying WD becomes visible as a strong emitter of supersoft X-rays. Observations during this phase have revealed oscillations in the X-ray emission with periods on the order of tens of seconds. A proposed explanation for the source of these oscillations is internal gravity waves excited by nuclear reactions at the base of the hydrogen-burning layer. In this work, we present the first models exhibiting unstable surface g-modes with periods similar to oscillation periods found in galactic novae. However, when comparing mode periods of our models to the observed oscillations of several novae, we find that the modes that are excited have periods shorter than that observed.

  15. NUCLEAR MIXING METERS FOR CLASSICAL NOVAE

    SciTech Connect

    Kelly, Keegan J.; Iliadis, Christian; Downen, Lori

    2013-11-10

    Classical novae are caused by mass transfer episodes from a main-sequence star onto a white dwarf via Roche lobe overflow. This material possesses angular momentum and forms an accretion disk around the white dwarf. Ultimately, a fraction of this material spirals in and piles up on the white dwarf surface under electron-degenerate conditions. The subsequently occurring thermonuclear runaway reaches hundreds of megakelvin and explosively ejects matter into the interstellar medium. The exact peak temperature strongly depends on the underlying white dwarf mass, the accreted mass and metallicity, and the initial white dwarf luminosity. Observations of elemental abundance enrichments in thesemore » classical nova events imply that the ejected matter consists not only of processed solar material from the main-sequence partner but also of material from the outer layers of the underlying white dwarf. This indicates that white dwarf and accreted matter mix prior to the thermonuclear runaway. The processes by which this mixing occurs require further investigation to be understood. In this work, we analyze elemental abundances ejected from hydrodynamic nova models in search of elemental abundance ratios that are useful indicators of the total amount of mixing. We identify the abundance ratios ΣCNO/H, Ne/H, Mg/H, Al/H, and Si/H as useful mixing meters in ONe novae. The impact of thermonuclear reaction rate uncertainties on the mixing meters is investigated using Monte Carlo post-processing network calculations with temperature-density evolutions of all mass zones computed by the hydrodynamic models. We find that the current uncertainties in the {sup 30}P(p, γ){sup 31}S rate influence the Si/H abundance ratio, but overall the mixing meters found here are robust against nuclear physics uncertainties. A comparison of our results with observations of ONe novae provides strong constraints for classical nova models.« less

  16. Nova Serpentis 1983. [Light curve and spectra

    SciTech Connect

    Schlegel, E.M.; Honeycutt, R.K.; Kaitchuck, R.H.

    1985-11-01

    A spectrum of Nova Serpentis 1983 has been obtained using the IIDS spectrograph attached to the 2.1-meter telescope at Kitt Peak. A series of 10 spectra were co-added to produce a single spectrum covering the wavelengths in the range 4250-4950 A. The integration time was 300 seconds using an 8.4 arcsec aperture. The photometric and spectroscopic characteristics of the spectrum are discussed in detail. A table listing the spectral line emission intensities of H-beta, H-gamma, and N III in the spectrum of Nova Serpentis 1983 is given, and the photometric light curve is reproduced in graphic form. 16 references.

  17. Ultraviolet observations of LMC nova 1988

    NASA Technical Reports Server (NTRS)

    Starrfield, S.; Stryker, L. L.; Sonneborn, G.; Sparks, Warren M.; Sion, E. M.; Wagner, R. M.; Ferland, Gary; Gallagher, J. S.; Wade, R.; Williams, R. E.

    1988-01-01

    The IUE obtained ultraviolet spectra of a nova in an external galaxy. The spectral features do not seem unusual for a nova at maximum but it is hoped to be able to follow it for a long enough time to be able to study the high ionization lines that appear when the density drops to lower values (the nebular stage). A high dispersion spectrum was also obtained to assist in the line identification and to study the line of sight to the LMC 1 deg of arc away from SN 1987A.

  18. New optical nova candidate in M 31

    NASA Astrophysics Data System (ADS)

    Burwitz, V.; Pietsch, W.; Henze, M.; Rodriguez, J.; Haswell, C. A.; Holmes, S.; Kolb, U.; Lucas, R.

    2010-06-01

    We report the discovery of a possible nova in M 31 on a 5x120s stacked unfiltered CCD image obtained with the 0.35-m f/11 OU/OAM PIRATE Schmidt-Cassegrain telescope (+ SBIG STL-1001E CCD camera) at Costitx, Mallorca, Spain on 2010 June 26.084 UT with a corresponding R magnitude of 17.8. The position for the nova candidate is RA = 00h44m04.48s, Dec = +41d28'34.2" (J2000, accuracy of 0.3"), which is 902" east and 746" north of the core of M 31.

  19. PAH emission from Nova Cen 1986

    NASA Technical Reports Server (NTRS)

    Hyland, A. R. Harry; Mcgregor, P. J.

    1989-01-01

    The discovery of broad emission features between 3.2 and 3.6 microns were reported in the spectrum of Nova Cen 1986 (V842 Cen) some 300 days following outburst and remaining prominent for several months. The general characteristics of these features are similar to those attributed to polycyclic hydrocarbon (PAH) molecules in other dusty sources, although the relative strengths are different, and these observations provide the first clear evidence for molecular constituents other than graphite particles in the ejecta of novae.

  20. V&V of MCNP 6.1.1 Beta Against Intermediate and High-Energy Experimental Data

    SciTech Connect

    Mashnik, Stepan G

    2014-09-08

    This report presents a set of validation and verification (V&V) MCNP 6.1.1 beta results calculated in parallel, with MPI, obtained using its event generators at intermediate and high-energies compared against various experimental data. It also contains several examples of results using the models at energies below 150 MeV, down to 10 MeV, where data libraries are normally used. This report can be considered as the forth part of a set of MCNP6 Testing Primers, after its first, LA-UR-11-05129, and second, LA-UR-11-05627, and third, LA-UR-26944, publications, but is devoted to V&V with the latest, 1.1 beta version of MCNP6. The MCNP6more » test-problems discussed here are presented in the /VALIDATION_CEM/and/VALIDATION_LAQGSM/subdirectories in the MCNP6/Testing/directory. README files that contain short descriptions of every input file, the experiment, the quantity of interest that the experiment measures and its description in the MCNP6 output files, and the publication reference of that experiment are presented for every test problem. Templates for plotting the corresponding results with xmgrace as well as pdf files with figures representing the final results of our V&V efforts are presented. Several technical “bugs” in MCNP 6.1.1 beta were discovered during our current V&V of MCNP6 while running it in parallel with MPI using its event generators. These “bugs” are to be fixed in the following version of MCNP6. Our results show that MCNP 6.1.1 beta using its CEM03.03, LAQGSM03.03, Bertini, and INCL+ABLA, event generators describes, as a rule, reasonably well different intermediate- and high-energy measured data. This primer isn’t meant to be read from cover to cover. Readers may skip some sections and go directly to any test problem in which they are interested.« less

  1. The Long-Term Behavior of Known & Suspected Novae

    NASA Astrophysics Data System (ADS)

    Pagnotta, A.

    2017-03-01

    The long-term evolution of classical novae is poorly understood. I discuss here an in-progress project designed to better understand the post-eruption behavior of novae and test the Hibernation theory of nova evolution. The project has two main parts: (1) a modern survey of Galactic nova magnitudes, and (2) construction of long-term light curves using primarily archival photographic plates.

  2. Mira variables masquerading as Novae in M 31

    NASA Astrophysics Data System (ADS)

    Taneva, Nina; Valcheva, Antoniya; Ovcharov, Evgeni; Nedialkov, Petko

    Mira variables are often masquerading as novae in the nearby galaxies. In this paper we discuss this problem and focus on two Mira variables in M31 galaxy, one of them classified as nova by our team during novae search in M31 galaxy. Astrometry and photometry data, finding charts and light curves are presented.

  3. Novae. Fermi establishes classical novae as a distinct class of gamma-ray sources.

    PubMed

    2014-08-01

    A classical nova results from runaway thermonuclear explosions on the surface of a white dwarf that accretes matter from a low-mass main-sequence stellar companion. In 2012 and 2013, three novae were detected in γ rays and stood in contrast to the first γ-ray-detected nova V407 Cygni 2010, which belongs to a rare class of symbiotic binary systems. Despite likely differences in the compositions and masses of their white dwarf progenitors, the three classical novae are similarly characterized as soft-spectrum transient γ-ray sources detected over 2- to 3-week durations. The γ-ray detections point to unexpected high-energy particle acceleration processes linked to the mass ejection from thermonuclear explosions in an unanticipated class of Galactic γ-ray sources. Copyright © 2014, American Association for the Advancement of Science.

  4. Models of classical and recurrent novae

    NASA Technical Reports Server (NTRS)

    Friedjung, Michael; Duerbeck, Hilmar W.

    1993-01-01

    The behavior of novae may be divided roughly into two separate stages: quiescence and outburst. However, at closer inspection, both stages cannot be separated. It should be attempted to explain features in both stages with a similar model. Various simple models to explain the observed light and spectral observations during post optical maximum activity are conceivable. In instantaneous ejection models, all or nearly all material is ejected in a time that is short compared with the duration of post optical maximum activity. Instantaneous ejection type 1 models are those where the ejected material is in a fairly thin shell, the thickness of which remains small. In the instantaneous ejection type 2 model ('Hubble Flow'), a thick envelope is ejected instantaneously. This envelope remains thick as different parts have different velocities. Continued ejection models emphasize the importance of winds from the nova after optical maximum. Ejection is supposed to occur from one of the components of the central binary, and one can imagine a general swelling of one of the components, so that something resembling a normal, almost stationary, stellar photosphere is observed after optical maximum. The observed characteristics of recurrent novae in general are rather different from those of classical novae, thus, models for these stars need not be the same.

  5. NOVA HIGH SCHOOL--SYSTEM ANALYSIS.

    ERIC Educational Resources Information Center

    COGSWELL, JOHN F.

    A SYSTEMS ANALYSIS WAS MADE OF A 10TH-GRADE SOCIAL STUDIES COURSE IN AMERICAN HISTORY TAUGHT AT THE NOVA HIGH SCHOOL, FORT LAUDERDALE, FLORIDA, TO EVALUATE THE COURSE AS AN INSTRUCTIONAL SYSTEM. THE ANALYSIS WAS CONCERNED WITH SUCH PROBLEM AREAS AS TEACHER ROLES, THE EFFECTS OF MEDIA ON STUDENT-TEACHER RELATIONSHIPS, INFORMATION REQUIREMENTS, THE…

  6. NOVA[R] Spring 2002 Teacher's Guide.

    ERIC Educational Resources Information Center

    Armstrong, Peter; Ransick, Kristi; Rosene, Dale; Sammons, James

    The guide presents lesson plans from "NOVA" which targets middle school and junior high school students and meet the National Science Education Standards. Lessons include: (1) "Neanderthals on Trial"; (2) "Fireworks"; (3) "Secrets, Lies and Atomic Spies"; (4) "Bioterror"; (5) "The Missing…

  7. NOVA[R] Fall 2001 Teacher's Guide.

    ERIC Educational Resources Information Center

    WGBH-TV, Boston, MA.

    This teacher guide includes activity information for the program NOVA, Fall 2001. Background for each activity is provided along with its correlation to the national science standards. Activities include: (1) "Search for a Safe Cigarette"; (2) "18 Ways To Make a Baby"; (3) "Secrets of Mind"; (4) "Neanderthals on…

  8. Fast food and deprivation in Nova Scotia.

    PubMed

    Jones, Jennifer; Terashima, Mikiko; Rainham, Daniel

    2009-01-01

    To examine the relationship between density of fast food restaurants and measures of social and material deprivation at the community level in Nova Scotia, Canada. Census information on population and key variables required for the calculation of deprivation indices were obtained for 266 communities in Nova Scotia. The density of fast food restaurants per 1000 individuals for each community was calculated and communities were divided into quintiles of material and psychosocial deprivation. One-way analysis of variance was used to investigate associations between fast food outlet densities and deprivation scores at the community level. A statistically significant inverse association was found between community-level material deprivation and the mean number of fast food restaurants per 1000 people for Nova Scotia (p < 0.000). Significant positive relationships were found between density of fast food restaurants and psychosocial deprivation (p < 0.000). Both associations were principally linear with greater fast food outlet density occurring as material deprivation decreased and as psychosocial deprivation increased. Community-level deprivation in Nova Scotia is associated with fast food outlet density and lends support for environmental explanations for variations in the prevalence of obesity. Such findings are valuable to population health intervention initiatives targeting the modification of environmental determinants of obesity.

  9. Nova Scotia. Reference Series No. 32.

    ERIC Educational Resources Information Center

    Department of External Affairs, Ottawa (Ontario).

    This booklet, one of a series featuring the Canadian provinces, presents a brief overview of Nova Scotia and is suitable for teacher reference or student reading. Separate sections discuss the geography and climate, history, economic development, fishing, agriculture, forestry, mining, manufacturing, energy, education, arts and culture, and…

  10. NOvA: Exploring Neutrino Mysteries

    ScienceCinema

    Vahle, Tricia; Messier, Mark

    2018-01-16

    Neutrinos are a mystery to physicists. They exist in three different flavors and mass states and may be able to give hints about the origins of the matter-dominated universe. A new long-baseline experiment led by Fermilab called NOvA may provide some answers.

  11. Clinical and laboratory features of Nocardia nova.

    PubMed Central

    Wallace, R J; Brown, B A; Tsukamura, M; Brown, J M; Onyi, G O

    1991-01-01

    Recent studies have shown that Nocardia asteroides isolates have five major antibiotic resistance patterns; one of these patterns identifies isolates of Nocardia farcinica. In the current study, we investigated a second pattern characterized by susceptibility to ampicillin and erythromycin. This pattern was seen in 17% of 223 clinical isolates identified by standard techniques as N. asteroides and associated with diseases typical for nocardiae. Biochemically, isolates with this drug pattern were relatively homogeneous and identical to the type strain and previous descriptions of Nocardia nova. The strains studied were unique among nocardiae in having both alpha- and beta-esterase activity (85 and 95%, respectively). However, the arylsulfatase activity at 14 days (75%) and antimicrobial susceptibility patterns, including susceptibility to erythromycin (100%), were the only routinely available methods that would separate N. nova strains from other members of N. asteroides. N. asteroides should be considered a complex because current clinical identification schemes include isolates of N. farcinica and N. nova and may well include additional species. This is the first detailed description of N. nova as a pathogen in humans. PMID:1774244

  12. Stress and the Nova Scotia Teacher.

    ERIC Educational Resources Information Center

    Fergusson, Norman H.

    This study obtained information about the factors which cause stress for 406 teachers in Nova Scotia and determined possible differences by sub-groups. Noteworthy differences were found by size of school, gender, experience, type of school, administrator/non-administrator, and a few by license category. Results indicated that one teacher in four…

  13. The expanding fireball of Nova Delphini 2013

    NASA Astrophysics Data System (ADS)

    Schaefer, G. H.; Brummelaar, T. Ten; Gies, D. R.; Farrington, C. D.; Kloppenborg, B.; Chesneau, O.; Monnier, J. D.; Ridgway, S. T.; Scott, N.; Tallon-Bosc, I.; McAlister, H. A.; Boyajian, T.; Maestro, V.; Mourard, D.; Meilland, A.; Nardetto, N.; Stee, P.; Sturmann, J.; Vargas, N.; Baron, F.; Ireland, M.; Baines, E. K.; Che, X.; Jones, J.; Richardson, N. D.; Roettenbacher, R. M.; Sturmann, L.; Turner, N. H.; Tuthill, P.; van Belle, G.; von Braun, K.; Zavala, R. T.; Banerjee, D. P. K.; Ashok, N. M.; Joshi, V.; Becker, J.; Muirhead, P. S.

    2014-11-01

    A classical nova occurs when material accreting onto the surface of a white dwarf in a close binary system ignites in a thermonuclear runaway. Complex structures observed in the ejecta at late stages could result from interactions with the companion during the common-envelope phase. Alternatively, the explosion could be intrinsically bipolar, resulting from a localized ignition on the surface of the white dwarf or as a consequence of rotational distortion. Studying the structure of novae during the earliest phases is challenging because of the high spatial resolution needed to measure their small sizes. Here we report near-infrared interferometric measurements of the angular size of Nova Delphini 2013, starting one day after the explosion and continuing with extensive time coverage during the first 43 days. Changes in the apparent expansion rate can be explained by an explosion model consisting of an optically thick core surrounded by a diffuse envelope. The optical depth of the ejected material changes as it expands. We detect an ellipticity in the light distribution, suggesting a prolate or bipolar structure that develops as early as the second day. Combining the angular expansion rate with radial velocity measurements, we derive a geometric distance to the nova of 4.54 +/- 0.59 kiloparsecs from the Sun.

  14. The expanding fireball of Nova Delphini 2013.

    PubMed

    Schaefer, G H; ten Brummelaar, T; Gies, D R; Farrington, C D; Kloppenborg, B; Chesneau, O; Monnier, J D; Ridgway, S T; Scott, N; Tallon-Bosc, I; McAlister, H A; Boyajian, T; Maestro, V; Mourard, D; Meilland, A; Nardetto, N; Stee, P; Sturmann, J; Vargas, N; Baron, F; Ireland, M; Baines, E K; Che, X; Jones, J; Richardson, N D; Roettenbacher, R M; Sturmann, L; Turner, N H; Tuthill, P; van Belle, G; von Braun, K; Zavala, R T; Banerjee, D P K; Ashok, N M; Joshi, V; Becker, J; Muirhead, P S

    2014-11-13

    A classical nova occurs when material accreting onto the surface of a white dwarf in a close binary system ignites in a thermonuclear runaway. Complex structures observed in the ejecta at late stages could result from interactions with the companion during the common-envelope phase. Alternatively, the explosion could be intrinsically bipolar, resulting from a localized ignition on the surface of the white dwarf or as a consequence of rotational distortion. Studying the structure of novae during the earliest phases is challenging because of the high spatial resolution needed to measure their small sizes. Here we report near-infrared interferometric measurements of the angular size of Nova Delphini 2013, starting one day after the explosion and continuing with extensive time coverage during the first 43 days. Changes in the apparent expansion rate can be explained by an explosion model consisting of an optically thick core surrounded by a diffuse envelope. The optical depth of the ejected material changes as it expands. We detect an ellipticity in the light distribution, suggesting a prolate or bipolar structure that develops as early as the second day. Combining the angular expansion rate with radial velocity measurements, we derive a geometric distance to the nova of 4.54 ± 0.59 kiloparsecs from the Sun.

  15. NOVA[R] Spring 2001 Teacher's Guide.

    ERIC Educational Resources Information Center

    WGBH-TV, Boston, MA.

    This teacher's guide is designed to accompany the PBS television program "NOVA" and features six activities. "Sultan's Lost Treasure" presents the attempts of an archaeologist and his team to salvage an ancient ship wreck. "Vanished!" investigates what happened to the Stardust airliner in 1947 which disappeared during…

  16. First optical candidate for a recovered classical nova in a globular cluster - Nova 1938 in M14

    NASA Technical Reports Server (NTRS)

    Shara, Michael M.; Potter, Michael; Moffat, Anthony F. J.; Hogg, Helen S.; Wehlau, Amelia

    1986-01-01

    U, B, V, R, and H-alpha CCD frames of the field of the nova which appeared in the globular cluster M14 in 1938 have been compared with the nova discovery images. On the basis of positional coincidence, brightness, and blue color, a candidate nova was identified and its right ascension and declination to within 1 arcsec each. Confirmation of the candidate and detailed study of the quiescent nova will probably require Hubble Space Telescope observations.

  17. Radio Observations of Nova Muscae 2018 and Nova Carinae 2018 (ASASSN-18fv)

    NASA Astrophysics Data System (ADS)

    Ryder, S. D.; Kool, E. C.; Chomiuk, L.

    2018-04-01

    The two optically-bright Galactic novae in Musca (CBET #4473, ATel #11183, #11201, #11212, #11296) and in Carina (ATel #11454, #11456, #11457, #11460, #11468) were observed at radio wavelengths using the Australia Telescope Compact Array (ATCA) on 2018 Apr 3.3 UT. Nova Muscae 2018 has faded by a factor of 3 at 9.0 and 5.5 GHz since peaking at > 30 mJy/bm in mid-March.

  18. NOVA making stuff: Season 2

    SciTech Connect

    Leombruni, Lisa; Paulsen, Christine Andrews

    2014-12-12

    Over the course of four weeks in fall 2013, 11.7 million Americans tuned in to PBS to follow host David Pogue as he led them in search of engineering and scientific breakthroughs poised to change our world. Levitating trains, quantum computers, robotic bees, and bomb-detecting plants—these were just a few of the cutting-edge innovations brought into the living rooms of families across the country in NOVA’s four-part series, Making Stuff: Faster, Wilder, Colder, and Safer. Each of the four one-hour programs gave viewers a behind-the-scenes look at novel technologies poised to change our world—showing them how basic research and scientificmore » discovery can hold the keys to transforming how we live. Making Stuff Season 2 (MS2) combined true entertainment with educational value, creating a popular and engaging series that brought accessible science into the homes of millions. NOVA’s goal to engage the public with such technological innovation and basic research extended beyond the broadcast series, including a variety of online, educational, and promotional activities: original online science reporting, web-only short-form videos, a new online quiz-game, social media engagement and promotion, an educational outreach “toolkit” for science educators to create their own “makerspaces,” an online community of practice, a series of nationwide Innovation Cafés, educator professional development, a suite of teacher resources, an “Idealab,” participation in national conferences, and specialized station relation and marketing. A summative evaluation of the MS2 project indicates that overall, these activities helped make a significant impact on the viewers, users, and participants that NOVA reached. The final evaluation conducted by Concord Evaluation Group (CEG) confidently concluded that the broadcast, website, and outreach activities were successful at achieving the project’s intended impacts. CEG reported that the MS2 series and website content

  19. FUSE Observations of Galactic and LMC Novae in Outburst

    NASA Technical Reports Server (NTRS)

    Huschildt, P. H.

    2001-01-01

    This document is a collection of five abstracts from papers written on the 'FUSE Observations of Galactic and LMC Novae in Outburst'. The titles are the following: (1) Analyzing FUSE Observations of Galactic and LMC Novae; (2) Detailed NLTE Model Atmospheres for Novae during Outburst: Modeling Optical and Ultraviolet Observations for Nova LMC 1988; (3) Numerical Solution of the Expanding Stellar Atmosphere Problem; (4) A Non-LTE Line-Blanketed Expanding Atmosphere Model for A-supergiant Alpha Cygni; and (5) Non-LTE Model Atmosphere Analysis of the Early Ultraviolet Spectra of Nova Andromedae 1986. A list of journal publications is also included.

  20. MCNP efficiency calculations of INEEL passive active neutron assay system for simulated TRU waste assays

    SciTech Connect

    Yoon, W.Y.; Meachum, T.R.; Blackwood, L.G.

    2000-07-01

    The Idaho National Engineering and Environmental Laboratory Stored Waste Examination Pilot Plant (SWEPP) passive active neutron (PAN) radioassay system is used to certify transuranic (TRU) waste drums in terms of quantifying plutonium and other TRU element activities. Depending on the waste form involved, significant systematic and random errors need quantification in addition to the counting statistics. To determine the total uncertainty of the radioassay results, a statistical sampling and verification approach has been developed. In this approach, the total performance of the PAN nondestructive assay system is simulated using the computer models of the assay system, and the resultant outputmore » is compared with the known input to assess the total uncertainty. The supporting steps in performing the uncertainty analysis for the passive assay measurements in particular are as follows: (1) Create simulated waste drums and associated conditions; (2) Simulate measurements to determine the basic counting data that would be produced by the PAN assay system under the conditions specified; and (3) Apply the PAN assay system analysis algorithm to the set of counting data produced by simulating measurements to determine the measured plutonium mass. The validity of this simulation approach was verified by comparing simulated output against results from actual measurements using known plutonium sources and surrogate waste drums. The computer simulation of the PAN system performance uses the Monte Carlo N-Particle (MCNP) Code System to produce a neutron transport calculation for a simulated waste drum. Specifically, the passive system uses the neutron coincidence counting technique, utilizing the spontaneous fission of {sup 240}Pu. MCNP application to the SWEPP PAN assay system uncertainty analysis has been very useful for a variety of waste types contained in 208-{ell} drums measured by a passive radioassay system. The application of MCNP to the active radioassay system

  1. Input files with ORNL—mathematical phantoms of the human body for MCNP-4B

    NASA Astrophysics Data System (ADS)

    Krstić, D.; Nikezić, D.

    2007-01-01

    Protection against ionizing radiation requires information on the absorbed doses in organs of the human body. Implantation of many dosimeters in the human body is undesirable (or impossible), so the doses in organs are not measurable and some kind of dose calculation has to be applied. Calculation of doses in organs requests: (a) an exact description of the geometry of organs, (b) the chemical constitution of tissues, and (c) appropriate computer programs. The first two items, (a) and (b), make a so-called "phantom". In another words, the "phantom of a human body" is a mathematical representation of the human body including all other relevant information. All organs are represented with geometrical bodies (like cylinders, ellipsoids, tori, cones etc.), which are described with suitable mathematical equations. A corresponding chemical constitution for various types of organ tissues is also defined. MCNP-4B ( Monte Carlo N- Particle) is often used as transport code. Users of this software prepare an "input file" providing all necessary information for program execution. This information includes: (a) source definition—type of ionizing radiation, energy spectrum, and geometry of the source; (b) target definition—material constitution, geometry, location in respect to the source etc.; (c) characterization of absorbing media between the source and target; (d) output tally, etc. This paper presents input files with "human phantoms" for the MCNP-4B code. The input files with "phantoms" were prepared based on publications issued by the Oak Ridge National Laboratory (ORNL). Seven input files relating to different age groups (newborn, 1, 5, 10, 15 years, as well as, male and female adults) are presented here. A test example and comparison with other data found in literature are also given. Program summaryTitle of program: INPUT FILES, AMALE, AFEMALE, AGE15, AGE10, AGE5, AGE01, NEWB Catalogue identifier:ADYF_v1_0 Program summary URL

  2. Development of Multi-physics (Multiphase CFD + MCNP) simulation for generic solution vessel power calculation

    SciTech Connect

    Kim, Seung Jun; Buechler, Cynthia Eileen

    2017-07-17

    The current study aims to predict the steady state power of a generic solution vessel and to develop a corresponding heat transfer coefficient correlation for a Moly99 production facility by conducting a fully coupled multi-physics simulation. A prediction of steady state power for the current application is inherently interconnected between thermal hydraulic characteristics (i.e. Multiphase computational fluid dynamics solved by ANSYS-Fluent 17.2) and the corresponding neutronic behavior (i.e. particle transport solved by MCNP6.2) in the solution vessel. Thus, the development of a coupling methodology is vital to understand the system behavior at a variety of system design and postulated operatingmore » scenarios. In this study, we report on the k-effective (keff) calculation for the baseline solution vessel configuration with a selected solution concentration using MCNP K-code modeling. The associated correlation of thermal properties (e.g. density, viscosity, thermal conductivity, specific heat) at the selected solution concentration are developed based on existing experimental measurements in the open literature. The numerical coupling methodology between multiphase CFD and MCNP is successfully demonstrated, and the detailed coupling procedure is documented. In addition, improved coupling methods capturing realistic physics in the solution vessel thermal-neutronic dynamics are proposed and tested further (i.e. dynamic height adjustment, mull-cell approach). As a key outcome of the current study, a multi-physics coupling methodology between MCFD and MCNP is demonstrated and tested for four different operating conditions. Those different operating conditions are determined based on the neutron source strength at a fixed geometry condition. The steady state powers for the generic solution vessel at various operating conditions are reported, and a generalized correlation of the heat transfer coefficient for the current application is discussed. The assessment of

  3. New Tools to Prepare ACE Cross-section Files for MCNP Analytic Test Problems

    SciTech Connect

    Brown, Forrest B.

    2016-06-17

    Monte Carlo calculations using one-group cross sections, multigroup cross sections, or simple continuous energy cross sections are often used to: (1) verify production codes against known analytical solutions, (2) verify new methods and algorithms that do not involve detailed collision physics, (3) compare Monte Carlo calculation methods with deterministic methods, and (4) teach fundamentals to students. In this work we describe 2 new tools for preparing the ACE cross-section files to be used by MCNP ® for these analytic test problems, simple_ace.pl and simple_ace_mg.pl.

  4. Calculation of self–shielding factor for neutron activation experiments using GEANT4 and MCNP

    SciTech Connect

    Romero–Barrientos, Jaime, E-mail: jaromero@ing.uchile.cl; Universidad de Chile, DFI, Facultad de Ciencias Físicas Y Matemáticas, Avenida Blanco Encalada 2008, Santiago; Molina, F.

    2016-07-07

    The neutron self–shielding factor G as a function of the neutron energy was obtained for 14 pure metallic samples in 1000 isolethargic energy bins from 1·10{sup −5}eV to 2·10{sup 7}eV using Monte Carlo simulations in GEANT4 and MCNP6. The comparison of these two Monte Carlo codes shows small differences in the final self–shielding factor mostly due to the different cross section databases that each program uses.

  5. Studying factors affecting the indoor gamma radiation dose using the MCNP5 simulation software.

    PubMed

    Orabi, M

    2016-12-01

    Different factors and parameters affecting the indoor gamma radiation dose are considered and investigated. The change of the dose with different positions inside the room is discussed. The relative doses are also calculated for different changes; with different room dimensions, different wall thicknesses, and different building material densities. Some other factors are also discussed. The study is carried out by executing some models designed by the MCNP version 5 simulation software. The calculations of the dose rates are performed by adopting a simple and convenient calculation model which is based on the obtained relative changes of the dose rates with the different factors. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Multiwavelength observations of nova SMCN 2016-10a - one of the brightest novae ever observed

    NASA Astrophysics Data System (ADS)

    Aydi, E.; Page, K. L.; Kuin, N. P. M.; Darnley, M. J.; Walter, F. M.; Mróz, P.; Buckley, D. A. H.; Mohamed, S.; Whitelock, P.; Woudt, P.; Williams, S. C.; Orio, M.; Williams, R. E.; Beardmore, A. P.; Osborne, J. P.; Kniazev, A.; Ribeiro, V. A. R. M.; Udalski, A.; Strader, J.; Chomiuk, L.

    2018-02-01

    We report on multiwavelength observations of nova Small Magellanic Cloud Nova 2016-10a. The present observational set is one of the most comprehensive for any nova in the Small Magellanic Cloud, including low-, medium-, and high-resolution optical spectroscopy and spectropolarimetry from Southern African Large Telescope, Folded Low-Order Yte-Pupil Double-Dispersed Spectrograph, and Southern Astrophysical Research; long-term Optical Gravitational Lensing Experiment V- and I-bands photometry dating back to 6 yr before eruption; Small and Moderate Aperture Research Telescope System optical and near-IR photometry from ˜11 d until over 280 d post-eruption; Swift satellite X-ray and ultraviolet observations from ˜6 d until 319 d post-eruption. The progenitor system contains a bright disc and a main sequence or a sub-giant secondary. The nova is very fast with t2 ≃ 4.0 ± 1.0 d and t3 ≃ 7.8 ± 2.0 d in the V band. If the nova is in the SMC, at a distance of ˜61 ± 10 kpc, we derive MV, max ≃ -10.5 ± 0.5, making it the brightest nova ever discovered in the SMC and one of the brightest on record. At day 5 post-eruption the spectral lines show a He/N spectroscopic class and an Full Width at Half Maximum of ˜3500 km s-1, indicating moderately high ejection velocities. The nova entered the nebular phase ˜20 d post-eruption, predicting the imminent super-soft source turn-on in the X-rays, which started ˜28 d post-eruption. The super-soft source properties indicate a white dwarf mass between 1.2 and 1.3 M⊙ in good agreement with the optical conclusions.

  7. The effects of nuclear data library processing on Geant4 and MCNP simulations of the thermal neutron scattering law

    NASA Astrophysics Data System (ADS)

    Hartling, K.; Ciungu, B.; Li, G.; Bentoumi, G.; Sur, B.

    2018-05-01

    Monte Carlo codes such as MCNP and Geant4 rely on a combination of physics models and evaluated nuclear data files (ENDF) to simulate the transport of neutrons through various materials and geometries. The grid representation used to represent the final-state scattering energies and angles associated with neutron scattering interactions can significantly affect the predictions of these codes. In particular, the default thermal scattering libraries used by MCNP6.1 and Geant4.10.3 do not accurately reproduce the ENDF/B-VII.1 model in simulations of the double-differential cross section for thermal neutrons interacting with hydrogen nuclei in a thin layer of water. However, agreement between model and simulation can be achieved within the statistical error by re-processing ENDF/B-VII.I thermal scattering libraries with the NJOY code. The structure of the thermal scattering libraries and sampling algorithms in MCNP and Geant4 are also reviewed.

  8. Terra Nova breaks new ground for alliances

    SciTech Connect

    Ghiselin, D.

    1996-08-01

    This paper reviews the development of alliances to help develop the Terra Nova oil and gas field in the offshore Atlantic areas of Canada. Largely attributed to BP, the strategic alliance concept got its start in the North Sea and on the North Slope of Alaska. BP saw it as the best way to take advantage of economy-of-scale, mitigate risk, and achieve outsourcing goals while retaining their core competencies. This paper reviews the methods of developing the alliances, the developing of a development plan for the Terra Nova field, and how the alliance plans to maximize the profittability of themore » operation for all involved.« less

  9. Strong earthquakes, novae and cosmic ray environment

    NASA Technical Reports Server (NTRS)

    Yu, Z. D.

    1985-01-01

    Observations about the relationship between seismic activity and astronomical phenomena are discussed. First, after investigating the seismic data (magnitude 7.0 and over) with the method of superposed epochs it is found that world seismicity evidently increased after the occurring of novae with apparent magnitude brighter than 2.2. Second, a great many earthquakes of magnitude 7.0 and over occurred in the 13th month after two of the largest ground level solar cosmic ray events (GLEs). The causes of three high level phenomena of global seismic activity in 1918-1965 can be related to these, and it is suggested that according to the information of large GLE or bright nova predictions of the times of global intense seismic activity can be made.

  10. Progress in Modeling Classical Nova Outbursts

    NASA Astrophysics Data System (ADS)

    Calder, A. C.; Alexakis, A.; Dursi, L. J.; Mignone, A.; Timmes, F. X.; Truran, J. W.; Rosner, R.; Lamb, D. Q.; Brown, E.; Fryxell, B.; Zingale, M.; Ricker, P.; Olson, K.

    2003-03-01

    We report on progress in modeling many facets of Classical Novae. These include magnetohydrodynamical simulations of the accretion phase (for the case of magnetic white dwarfs) and hydrodynamical simulations of the mixing of white dwarf material into the hydrogen-rich envelope by resonant gravity wave breaking at the surface of the white dwarf (See also Alexakis, et al.). We also report on initial efforts at the development of a sub-grid enrichment model based on these results as well as results of one-dimensional simulations with mixing length convection of the enrichment process exploring the long-term behavior of the enriched region. Finally, we present two-dimensional simulations of the onset and development of convection in nova precursor models and during the runaway. This work was supported by the DOE ASCI/Alliances program at the University of Chicago under grant No. B341495.

  11. The Christmas Star, Novae, and Pulsars

    NASA Astrophysics Data System (ADS)

    Hoffleit, Dorrit

    1984-06-01

    A ceiling painting in the Priscilla catacomb in Rome appears to represent a star map showing the Christmas Star. If so, this might be a portrait of the nova or comet of 5 B. C., or it could be Venus in 6 B. C. It could not represent the conjunction of Jupiter and Saturn in 7 B. C., which occurred in a different part of the sky.

  12. Swift observations of Nova Scuti 2017

    NASA Astrophysics Data System (ADS)

    Kuin, N. P. M.; Page, K. L.; Williams, S. C.; Darnley, M. J.; Nelson, T. J.; Osborne, J.

    2017-08-01

    Nova Sct 2017 (ASASSN-17hx/ASASSN-17ib) went into eruption on 2017-06-19.41 (hereafter taken as Day 0), as reported on the ASAS SN transient page (see also ATEL #10523,#10524) Spectroscopic confirmation (ATEL #10527,#10542) observed emission in H and He I, and in N II as well as Fe II. The ASASSN light curve data show a peak of V = 8.75 on 2017, July 30, day 40.867.

  13. The awakening of a classical nova from hibernation

    NASA Astrophysics Data System (ADS)

    Mróz, Przemek; Udalski, Andrzej; Pietrukowicz, Paweł; Szymański, Michał K.; Soszyński, Igor; Wyrzykowski, Łukasz; Poleski, Radosław; Kozłowski, Szymon; Skowron, Jan; Ulaczyk, Krzysztof; Skowron, Dorota; Pawlak, Michał

    2016-09-01

    Cataclysmic variable stars—novae, dwarf novae, and nova-likes—are close binary systems consisting of a white dwarf star (the primary) that is accreting matter from a low-mass companion star (the secondary). From time to time such systems undergo large-amplitude brightenings. The most spectacular eruptions, with a ten-thousandfold increase in brightness, occur in classical novae and are caused by a thermonuclear runaway on the surface of the white dwarf. Such eruptions are thought to recur on timescales of ten thousand to a million years. In between, the system’s properties depend primarily on the mass-transfer rate: if it is lower than a billionth of a solar mass per year, the accretion becomes unstable and the matter is dumped onto the white dwarf during quasi-periodic dwarf nova outbursts. The hibernation hypothesis predicts that nova eruptions strongly affect the mass-transfer rate in the binary, keeping it high for centuries after the event. Subsequently, the mass-transfer rate should significantly decrease for a thousand to a million years, starting the hibernation phase. After that the nova awakes again—with accretion returning to the pre-eruption level and leading to a new nova explosion. The hibernation model predicts cyclical evolution of cataclysmic variables through phases of high and low mass-transfer. The theory gained some support from the discovery of ancient nova shells around the dwarf novae Z Camelopardalis and AT Cancri, but direct evidence for considerable mass-transfer changes prior, during and after nova eruptions has not hitherto been found. Here we report long-term observations of the classical nova V1213 Cen (Nova Centauri 2009) covering its pre- and post-eruption phases and precisely documenting its evolution. Within the six years before the explosion, the system revealed dwarf nova outbursts indicative of a low mass-transfer rate. The post-nova is two orders of magnitude brighter than the pre-nova at minimum light with no trace of

  14. Development of Monteburns: A Code That Links MCNP and ORIGEN2 in an Automated Fashion for Burnup Calculations

    SciTech Connect

    Holly R. Trellue

    1998-12-01

    Monteburns is a fully automated tool that links the Monte Carlo transport code MCNP with the radioactive decay and burnup code 0RIGEN2. Monteburns produces many criticality and burnup computational parameters based on material feed/removal specifications, power(s), and time intervals. This code processes input from the user indicating the system geometry, initial material compositions, feed/removal, and other code-specific parameters. Results from MCNP, 0RIGEN2, and other calculations are then output successively as the code runs. The principle function of monteburns is to first transfer one-group cross sections and fluxes from MCNP to 0RIGEN2, and then transfer the resulting material compositions (after irradiationmore » and/or decay) from 0RIGEN2 back to MCNP in a repeated, cyclic fashion. The main requirement of the code is that the user have a working MCNP input file and other input parameters; all interaction with 0RIGEN2 and other calculations are performed by monteburns. This report presents the results obtained from the benchmarking of monteburns to measured and previously obtained data from traditional Light Water Reactor systems. The majority of the differences seen between the two were less than five percent. These were primarily a result of variances in cross sections between MCNP, cross section libraries used by other codes, and observed values. With this understanding, this code can now be used with confidence for burnup calculations in three-dimensional systems. It was designed for use in the Accelerator Transmutation of Waste project at Los Alamos National Laboratory but is also being applied to the analysis of isotopic production/destruction of transuranic actinides in a reactor system. The code has now been shown to sufficiently support these calculations.« less

  15. Total reaction cross sections in CEM and MCNP6 at intermediate energies

    DOE PAGES

    Kerby, Leslie M.; Mashnik, Stepan G.

    2015-05-14

    Accurate total reaction cross section models are important to achieving reliable predictions from spallation and transport codes. The latest version of the Cascade Exciton Model (CEM) as incorporated in the code CEM03.03, and the Monte Carlo N-Particle transport code (MCNP6), both developed at Los Alamos National Laboratory (LANL), each use such cross sections. Having accurate total reaction cross section models in the intermediate energy region (50 MeV to 5 GeV) is very important for different applications, including analysis of space environments, use in medical physics, and accelerator design, to name just a few. The current inverse cross sections used inmore » the preequilibrium and evaporation stages of CEM are based on the Dostrovsky et al. model, published in 1959. Better cross section models are now available. Implementing better cross section models in CEM and MCNP6 should yield improved predictions for particle spectra and total production cross sections, among other results.« less

  16. Fission products detection in irradiated TRIGA fuel by means of gamma spectroscopy and MCNP calculation.

    PubMed

    Cagnazzo, M; Borio di Tigliole, A; Böck, H; Villa, M

    2018-05-01

    Aim of this work was the detection of fission products activity distribution along the axial dimension of irradiated fuel elements (FEs) at the TRIGA Mark II research reactor of the Technische Universität (TU) Wien. The activity distribution was measured by means of a customized fuel gamma scanning device, which includes a vertical lifting system to move the fuel rod along its vertical axis. For each investigated FE, a gamma spectrum measurement was performed along the vertical axis, with steps of 1 cm, in order to determine the axial distribution of the fission products. After the fuel elements underwent a relatively short cooling down period, different fission products were detected. The activity concentration was determined by calibrating the gamma detector with a standard calibration source of known activity and by MCNP6 simulations for the evaluation of self-absorption and geometric effects. Given the specific TRIGA fuel composition, a correction procedure is developed and used in this work for the measurement of the fission product Zr 95 . This measurement campaign is part of a more extended project aiming at the modelling of the TU Wien TRIGA reactor by means of different calculation codes (MCNP6, Serpent): the experimental results presented in this paper will be subsequently used for the benchmark of the models developed with the calculation codes. Copyright © 2018 Elsevier Ltd. All rights reserved.

  17. Integration of the Super Nova Early Warning System with the NOvA Trigger

    NASA Astrophysics Data System (ADS)

    Habig, Alec; Zirnstein, Jan

    2015-12-01

    The NOvA experiment, with a baseline of 810km, samples Fermilab's upgraded NuMI beam with a Near Detector on-site and a Far Detector (FD) at Ash River, MN, to observe oscillations of muon neutrinos. The 344,064 liquid scintillator-filled cells of the 14kton FD provide high granularity of a large detector mass and enable us to also study non-accelerator based neutrinos with our Data Driven Trigger framework. This paper will focus on the real time integration of the SNEWS with the NOvA Trigger where we have set up an XML-RPC based messaging system to inject the SNEWS signal directly into our trigger. This presents a departure from the E-Mail based notification mechanism used by SNEWS in the past and allows NOvA more control over propagation and transmission timing.

  18. Integration of the Super Nova early warning system with the NOvA Trigger

    DOE PAGES

    Habig, Alec; Zirnstein, Jan

    2015-12-23

    The NOvA experiment, with a baseline of 810km, samples Fermilab’s upgraded NuMI beam with a Near Detector on-site and a Far Detector (FD) at Ash River, MN, to observe oscillations of muon neutrinos. The 344,064 liquid scintillator-filled cells of the 14 kton FD provide high granularity of a large detector mass and enable us to also study non-accelerator based neutrinos with our Data Driven Trigger framework. This paper will focus on the real time integration of the SNEWS with the NOvA Trigger where we have set up an XML-RPC based messaging system to inject the SNEWS signal directly into ourmore » trigger. In conclusion, this presents a departure from the E-Mail based notification mechanism used by SNEWS in the past and allows NOvA more control over propagation and transmission timing.« less

  19. Investigation of the Nebular Remnants of Novae

    NASA Astrophysics Data System (ADS)

    Ribeiro, Valério A. R. M.

    2011-01-01

    Classical and recurrent nova outbursts occur on the surface of a white dwarf in a close binary system. It is widely established that the outburst is due to a thermonuclear runaway. Their study provides a real-time laboratory for the understanding of a wide range of astrophysical phenomena. These include for example, mass transfer in close binary systems, nuclear powered outbursts, dust formation, mass loss from red giants, and many others. Recurrent novae have also been suggested as the progenitors of Type Ia Supernovae. This thesis concentrates on investigating the nebular remnants of novae by studying both resolved imaging (where available) and spectroscopic evolution and combining this with detailed modelling. Such studies have wider implications for example in our understanding of the shaping of proto-Planetary Nebulae. Here, using a morpho-kinematical code, the true 3D geometry, from which information such as the remnant's inclination angle and expansion velocity can be derived, of the recurrent nova RS Ophiuchi and classical novae V2491 Cygni, V2672 Ophiuchi and KT Eridani are established and related to other characteristics of each system. Each of the classical novae have also been suggested as a recurrent nova candidate. Furthermore, several enhancements to the modelling code were implemented prompted by the work described in this thesis. The RS Oph work entailed detailed modelling of Hubble Space Telescope resolved imaging combined with ground-based spectroscopic observations. Here it was shown that the bipolar morphology of RS Oph consisted of two distinct components with an outer dumbbell and an inner hour glass overdensity, which were required to reproduce both the observed images and spectra. This morphology was suggested to arise due to the interaction between the pre-existing anisotropic red-giant wind and the ejecta. The observed asymmetry in the ACS/HRC image was shown to be due to the finite width and offset from the [OIII] line's rest wavelength

  20. Extinction, ejecta masses, and radial velocities of novae

    NASA Technical Reports Server (NTRS)

    Williams, Robert E.

    1994-01-01

    Interstellar reddening is determined for a number of recent novae based upon emission-line ratios which are generally observable using CCDs. Large values of extinction are found for most systems, possibly indicative of an intrinsic component of reddening in postoutburst novae. The unusual characteristics of the (O I) lines in novae, which are strong and optically thick, require a large population of very dense globules which are the likely sites of dust formation. These pyroclasts must be ejected from the white dwarf. The total mass of the neutral gas in the globules in some of the objects is substantially larger than the masses normally derived for the ionized ejecta of novae. The distribution of radial velocities of Galactic novae in the Tololo sample, although uncertain, shows an asymmetry in having predominantly negative values. Either high internal absorption in the expanding ejecta skews the emission lines to bluer wavelengths, or most of the novae are moving out from the center of the Galaxy.

  1. A SPITZER SURVEY OF NOVAE IN M31

    SciTech Connect

    Shafter, A. W.; Rubin, M.; Bode, M. F.

    2011-01-20

    We report the results of the first infrared survey of novae in M31. Both photometric and spectroscopic observations of a sample of 10 novae (M31N 2006-09c, 2006-10a, 2006-10b, 2006-11a, 2007-07f, 2007-08a, 2007-08d, 2007-10a, 2007-11d, and 2007-11e) were obtained with the Spitzer Space Telescope. The observations, which were obtained between {approx}3 and {approx}7 months after discovery, revealed evidence for dust formation in two of the novae: M31N 2006-10a and (possibly) 2007-07f, and [Ne II] 12.8 {mu}m line emission in a third (2007-11e). The Spitzer observations were supplemented with ground-based optical photometric and spectroscopic data that were used to determine the speedmore » classes and spectroscopic types of the novae. After including data for dust-forming Galactic novae, we show that dust formation timescales are correlated with nova speed class in that dust typically forms earlier in faster novae. Our failure to detect the signature of dust formation in most of our M31 sample is likely a result of the relatively long delay between nova eruption and our Spitzer observations. The two novae for which we found evidence of dust formation were the two 'slowest' novae in our sample. Finally, as expected, we found that the majority of the novae in our sample belong to the Fe II spectroscopic class, with only one clear example of the He/N class (M31N 2006-10b). Typical of an He/N system, M31N 2006-10b was the fastest nova in our sample, not detected with the IRS, and just barely detected in three of the IRAC bands when it was observed {approx}4 months after eruption.« less

  2. The UBV color evolution of classical novae. I. Nova-giant sequence in the color-color diagram

    SciTech Connect

    Hachisu, Izumi; Kato, Mariko, E-mail: hachisu@ea.c.u-tokyo.ac.jp, E-mail: mariko@educ.cc.keio.ac.jp

    2014-04-20

    We identified a general course of classical nova outbursts in the B – V versus U – B color-color diagram. It is reported that novae show spectra similar to those of A-F supergiants near optical light maximum. However, they do not follow the supergiant sequence in the color-color diagram, neither the blackbody nor the main-sequence sequence. Instead, we found that novae evolve along a new sequence in the pre-maximum and near-maximum phases, which we call 'the nova-giant sequence'. This sequence is parallel to but Δ(U – B) ≈ –0.2 mag bluer than the supergiant sequence. This is because the massmore » of a nova envelope is much (∼10{sup –4} times) less than that of a normal supergiant. After optical maximum, its color quickly evolves back blueward along the same nova-giant sequence and reaches the point of free-free emission (B – V = –0.03, U – B = –0.97), which coincides with the intersection of the blackbody sequence and the nova-giant sequence, and remains there for a while. Then the color evolves leftward (blueward in B – V but almost constant in U – B), owing mainly to the development of strong emission lines. This is the general course of nova outbursts in the color-color diagram, which was deduced from eight well-observed novae in various speed classes. For a nova with unknown extinction, we can determine a reliable value of the color excess by matching the observed track of the target nova with this general course. This is a new and convenient method for obtaining the color excesses of classical novae. Using this method, we redetermined the color excesses of 20 well-observed novae. The obtained color excesses are in reasonable agreement with the previous results, which in turn support the idea of our general track of nova outbursts. Additionally, we estimated the absolute V magnitudes of about 30 novae using a method for time-stretching nova light curves to analyze the distance-reddening relations of the novae.« less

  3. Nova M33N 2012-10a

    NASA Astrophysics Data System (ADS)

    Alothman, Nourah

    In this thesis I present a study and measurement of a Nova in M33 galaxy type N 2012-10a (which is type of binary star) using data that were collected by the ROTSE IIIb robotic telescope and another observatory. I study the fundamental properties of the light curve and determined the brightness and the velocity of this type of nova. I analyzed the spectra that were measured by the Hobby-Eberly Telescope (HET) at the McDonald Observatory. In addition, I compared this type of nova to other types of Novae.

  4. Search for X-ray emission from Nova Cygni 1975

    NASA Technical Reports Server (NTRS)

    Hoffman, J. A.; Lewin, W. H. G.; Brecher, K.; Buff, J.; Clark, G. W.; Joss, P. C.; Matilsky, T.

    1976-01-01

    A search for X-rays from Nova Cygni 1975 was carried out before, during, and after the time of optical maximum. No X-rays were detected over the spectral range 0.1-50 keV. On the basis of these results a strong upper limit of .0001 has been placed on the ratio of X-ray to optical luminosity for this nova, consistent with effective temperatures of about 10,000 K. If Nova Cygni 1975 is a virgin nova, its low mass exchange rate would imply that any associated X-ray emission would not be detectable by present techniques.

  5. Recent progress in understanding the eruptions of classical novae

    NASA Technical Reports Server (NTRS)

    Shara, Michael M.

    1988-01-01

    Dramatic progress has occurred in the last two decades in understanding the physical processes and events leading up to, and transpiring during the eruption of a classical nova. The mechanism whereby a white dwarf accreting hydrogen-rich matter from a low-mass main-sequence companion produces a nova eruption has been understood since 1970. The mass-transferring binary stellar configuration leads inexorably to thermonuclear runaways detected at distances of megaparsecs. Summarized here are the efforts of many researchers in understanding the physical processes which generate nova eruptions; the effects upon nova eruptions of different binary-system parameters (e.g., chemical composition or mass of the white dwarf, different mass accretion rates); the possible metamorphosis from dwarf to classical novae and back again; and observational diagnostics of novae, including x ray and gamma ray emission, and the characteristics and distributions of novae in globular clusters and in extragalactic systems. While the thermonuclear-runaway model remains the successful cornerstone of nova simulation, it is now clear that a wide variety of physical processes, and three-dimensional hydrodynamic simulations, will be needed to explain the rich spectrum of behavior observed in erupting novae.

  6. NOVA: a software to analyze complexome profiling data.

    PubMed

    Giese, Heiko; Ackermann, Jörg; Heide, Heinrich; Bleier, Lea; Dröse, Stefan; Wittig, Ilka; Brandt, Ulrich; Koch, Ina

    2015-02-01

    We introduce nova, a software for the analysis of complexome profiling data. nova supports the investigation of the composition of complexes, cluster analysis of the experimental data, visual inspection and comparison of experiments and many other features. nova is licensed under the Artistic License 2.0. It is freely available at http://www.bioinformatik.uni-frankfurt.de. nova requires at least Java 7 and runs under Linux, Microsoft Windows and Mac OS. ina.koch@bioinformatik.uni-frankfurt.de. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  7. The comparison of two MCNP models used for prompt gamma in vivo detection of cadmium and mercury

    NASA Astrophysics Data System (ADS)

    Atanackovic, J.; Grinyer, J.; Chettle, D. R.; Byun, S. H.

    2007-10-01

    In vivo detection of trace elements is one of the most important research areas at the Medical Physics and Applied Radiation Sciences Department at McMaster University. Prompt gamma neutron activation analysis (PGNAA) used for detection of cadmium and mercury takes place simultaneously at two different experimental sites; the McMaster Nuclear Reactor (MNR) and the 238Pu/Be neutron source site. This particular study consists of two parts. In the first part the water phantoms (125 mL) were used in MCNP simulations. The water phantoms were doped with different concentrations of Cd, Hg and HCl. This is done in order to compare the (n, γ) prompt gamma reaction rate; in fact, the rate of neutron capture by the nuclides of interest; 113Cd, 199Hg and 35Cl. The second part involves, the neutron and photon dosimetry calculations that were performed for both sites using MCNP compatible body builder software developed in Los Alamos. The output of this program is the actual MCNP geometry description for various human anthropomorphic phantoms (different sex and ages). This phantom geometry output is incorporated into the original MCNP geometry and the dosimetry calculations were performed for various organs at risk.

  8. Discovery of a Probable Nova in M81 and Photometry of Three M81 Novae

    NASA Astrophysics Data System (ADS)

    Hornoch, K.; Errmann, R.; Carlisle, Ch.; Vaduvescu, O.

    2015-02-01

    We report the discovery of a probable nova in M81 on a co-added 1600-s narrow-band H-alpha CCD image taken with the 2.5-m Isaac Newton Telescope (INT) + WFC at La Palma under ~1.6" seeing on 2015 Jan.

  9. Expanded Very Large Array Nova Project Observations of the Classical NovaV1723 Aquilae

    NASA Technical Reports Server (NTRS)

    Krauss, Miriam I.; Chomiuk, Laura; Rupen, Michael; Roy, Nirupam; Mioduszewski, Amy J.; Sokoloski, J. L.; Nelson, Thomas; Mukai, Koji; Bode, M. F.; Eyres, S. P. S.; hide

    2011-01-01

    We present radio light curves and spectra of the classical nova VI723 Aql obtained with the Expanded Very Large Array (EVLA). This is the first paper to showcase results from the EVLA Nova Project, which comprises a team of observers and theorists utilizing the greatly enhanced sensitivity and frequency coverage of EVLA radio observations, along with observations at other wavelengths, to reach a deeper understanding of the energetics, morphology, and temporal characteristics of nova explosions. Our observations of VI723 Aql span 1-37 GHz in frequency, and we report on data from 14 to 175 days following the time of the nova explosion. The broad frequency coverage and frequent monitoring show that the radio behavior of VI723 Aql does not follow the classic Hubble-flow model of homologous spherically expanding thermal ejecta. The spectra are always at least partially optically thin, and the flux rises on faster timescales than can be reproduced with linear expansion. Therefore, any description of the underlying physical processes must go beyond this simple picture. The unusual spectral properties and light curve evolution might be explained by multiple emitting regions or shocked material. Indeed, X-ray observations from Swift reveal that shocks are likely present.

  10. Discovery of a New Classical Nova Shell Around a Nova-like Cataclysmic Variable

    NASA Astrophysics Data System (ADS)

    Guerrero, Martín A.; Sabin, Laurence; Tovmassian, Gagik; Santamaría, Edgar; Michel, Raul; Ramos-Larios, Gerardo; Alarie, Alexandre; Morisset, Christophe; Bermúdez Bustamante, Luis C.; González, Chantal P.; Wright, Nick J.

    2018-04-01

    The morphology and optical spectrum of IPHASX J210204.7+471015, a nebula classified as a possible planetary nebula are, however, strikingly similar to those of AT Cnc, a classical nova shell around a dwarf nova. To investigate its true nature, we have obtained high-resolution narrowband [O III] and [N II] images and deep optical spectra. The nebula shows an arc of [N II]-bright knots notably enriched in nitrogen, while an [O III]-bright bow shock is progressing throughout the ISM. Diagnostic line ratios indicate that shocks are associated with the arc and bow shock. The central star of this nebula has been identified by its photometric variability. Time-resolved photometric and spectroscopic data of this source reveal a period of 4.26 hr, which is attributed to a binary system. The optical spectrum is notably similar to that of RW Sex, a cataclysmic variable star (CV) of the UX UMa nova-like (NL) type. Based on these results, we propose that IPHASX J210204.7 + 471015 is a classical nova shell observed around a CV-NL system in quiescence.

  11. Radio Detection of Nova Muscae 2018

    NASA Astrophysics Data System (ADS)

    Ryder, S. D.; Kool, E. C.; Chomiuk, L.

    2018-02-01

    The optically-bright Galactic nova in Musca (CBET #4473, ATel #11183, #11201, #11221) was detected at radio wavelengths using the Australia Telescope Compact Array (ATCA) on 2018 Feb 5.8 UT. It was detected at 5 sigma at 5 GHz (0.10 mJy), while at 9 GHz it was observed to have a flux density of 0.22 +/- 0.02 mJy. The radio spectral energy distribution is therefore consistent with an optically thick, brightening source.

  12. UBVJHKLM photometry of Nova Del 2013

    NASA Astrophysics Data System (ADS)

    Burlak, A. M.; Shenavrin, I. V.; Tatarnikov, M. A.; Tatarnikova, A. A.

    2013-08-01

    We present the results of the optical and IR photometry of Nova Del 2013 obtained at the Crimean Station (Nauchny, Ukraine) of the Sternberg Astronomical Institute. UBV photometry was carried out with 60-cm Zeiss telescope using a photoelectric photometer on August 15.94 UT: U=4.54+/-0.02, B=5.07+/-0.01, V=5.05+/-0.01; on August 16.80 UT: U=4.54+/-0.01, B=4.85+/-0.02, V=4.68+/-0.01; on August 16.86 UT: U=4.66+/-0.01, B=4.92+/-0.01, V=4.73+/-0.01.

  13. New disk nova candidate in M 31

    NASA Astrophysics Data System (ADS)

    Henze, M.; Pietsch, W.; Burwitz, V.; Rodriguez, J.; Bochinski, J.; Busuttil, R.; Haswell, C. A.; Holmes, S.; Kolb, U.

    2012-02-01

    We report the discovery of a possible nova in the south-western disk of M 31 on a 5x120s dithered stacked CCD image obtained with the Open University PIRATE Planewave CDK17 0.43m Dall-Kirkham f/6.7 telescope at the Observatorio Astronomico de Mallorca (Costitx, Spain), using an SBIG STX 16803 CCD Camera (with a Kodak 4k x 4k chip with 9 microns sq. pixels) and Baader clear filter, on 2012 Feb 15.803 UT with a R magnitude of 17.5 (accuracy of 0.2 mag).

  14. New nova candidate in M81

    NASA Astrophysics Data System (ADS)

    Henze, M.; Sala, G.; Jose, J.; Figueira, J.; Hernanz, M.

    2016-06-01

    We report the discovery of a new nova candidate in the M81 galaxy on 16x200s stacked R filter CCD images, obtained with the 80 cm Ritchey-Chretien F/9.6 Joan Oro telescope at Observatori Astronomic del Montsec, owned by the Catalan Government and operated by the Institut d'Estudis Espacials de Catalunya, Spain, using a Finger Lakes PL4240-1-BI CCD Camera (with a Class 1 Basic Broadband coated 2k x 2k chip with 13.5 microns sq. pixels).

  15. Simulations of neutron transport at low energy: a comparison between GEANT and MCNP.

    PubMed

    Colonna, N; Altieri, S

    2002-06-01

    The use of the simulation tool GEANT for neutron transport at energies below 20 MeV is discussed, in particular with regard to shielding and dose calculations. The reliability of the GEANT/MICAP package for neutron transport in a wide energy range has been verified by comparing the results of simulations performed with this package in a wide energy range with the prediction of MCNP-4B, a code commonly used for neutron transport at low energy. A reasonable agreement between the results of the two codes is found for the neutron flux through a slab of material (iron and ordinary concrete), as well as for the dose released in soft tissue by neutrons. These results justify the use of the GEANT/MICAP code for neutron transport in a wide range of applications, including health physics problems.

  16. Monte Carlo simulation of prompt gamma neutron activation analysis using MCNP code.

    PubMed

    Evans, C J; Ryde, S J; Hancock, D A; al-Agel, F

    1998-01-01

    Prompt gamma neutron activation analysis (PGNAA) is the most direct method of measuring total-body nitrogen. In combination with internal hydrogen standardisation, it is possible to reduce the dependence on body habitus. The uniformity of activation and detection, however, cannot be optimised sufficiently to eliminate the dependence entirely, and so further corrections are essential. The availability of the powerful Monte Carlo code MCNP(4A) has allowed a more accurate analysis of the activation facility, and yields corrections for body habitus and superficial fat layers. The accuracy of the correction is retained as the source-to-skin distance is reduced, although the activation uniformity is thereby degraded. This allows the use of a 252Cf source with lower activity and hence reduces the running cost of the facility.

  17. Image enhancement using MCNP5 code and MATLAB in neutron radiography.

    PubMed

    Tharwat, Montaser; Mohamed, Nader; Mongy, T

    2014-07-01

    This work presents a method that can be used to enhance the neutron radiography (NR) image for objects with high scattering materials like hydrogen, carbon and other light materials. This method used Monte Carlo code, MCNP5, to simulate the NR process and get the flux distribution for each pixel of the image and determines the scattered neutron distribution that caused image blur, and then uses MATLAB to subtract this scattered neutron distribution from the initial image to improve its quality. This work was performed before the commissioning of digital NR system in Jan. 2013. The MATLAB enhancement method is quite a good technique in the case of static based film neutron radiography, while in neutron imaging (NI) technique, image enhancement and quantitative measurement were efficient by using ImageJ software. The enhanced image quality and quantitative measurements were presented in this work. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Neutron and photon shielding benchmark calculations by MCNP on the LR-0 experimental facility.

    PubMed

    Hordósy, G

    2005-01-01

    In the framework of the REDOS project, the space-energy distribution of the neutron and photon flux has been calculated over the pressure vessel simulator thickness of the LR-0 experimental reactor, Rez, Czech Republic. The results calculated by the Monte Carlo code MCNP4C are compared with the measurements performed in the Nuclear Research Institute, Rez. The spectra have been measured at the barrel, in front of, inside and behind the pressure vessel in different configurations. The neutron measurements were performed in the energy range 0.1-10 MeV. This work has been done in the frame of the 5th Frame Work Programme of the European Community 1998-2002.

  19. MCNP study for epithermal neutron irradiation of an isolated liver at the Finnish BNCT facility.

    PubMed

    Kotiluoto, P; Auterinen, I

    2004-11-01

    A successful boron neutron capture treatment (BNCT) of a patient with multiple liver metastases has been first given in Italy, by placing the removed organ into the thermal neutron column of the Triga research reactor of the University of Pavia. In Finland, FiR 1 Triga reactor with an epithermal neutron beam well suited for BNCT has been extensively used to irradiate patients with brain tumors such as glioblastoma and recently also head and neck tumors. In this work we have studied by MCNP Monte Carlo simulations, whether it would be beneficial to treat an isolated liver with epithermal neutrons instead of thermal ones. The results show, that the epithermal field penetrates deeper into the liver and creates a build-up distribution of the boron dose. Our results strongly encourage further studying of irradiation arrangement of an isolated liver with epithermal neutron fields.

  20. Gas Core Reactor Numerical Simulation Using a Coupled MHD-MCNP Model

    NASA Technical Reports Server (NTRS)

    Kazeminezhad, F.; Anghaie, S.

    2008-01-01

    Analysis is provided in this report of using two head-on magnetohydrodynamic (MHD) shocks to achieve supercritical nuclear fission in an axially elongated cylinder filled with UF4 gas as an energy source for deep space missions. The motivation for each aspect of the design is explained and supported by theory and numerical simulations. A subsequent report will provide detail on relevant experimental work to validate the concept. Here the focus is on the theory of and simulations for the proposed gas core reactor conceptual design from the onset of shock generations to the supercritical state achieved when the shocks collide. The MHD model is coupled to a standard nuclear code (MCNP) to observe the neutron flux and fission power attributed to the supercritical state brought about by the shock collisions. Throughout the modeling, realistic parameters are used for the initial ambient gaseous state and currents to ensure a resulting supercritical state upon shock collisions.

  1. EBR-II Static Neutronic Calculations by PHISICS / MCNP6 codes

    SciTech Connect

    Paolo Balestra; Carlo Parisi; Andrea Alfonsi

    2016-02-01

    The International Atomic Energy Agency (IAEA) launched a Coordinated Research Project (CRP) on the Shutdown Heat Removal Tests (SHRT) performed in the '80s at the Experimental fast Breeder Reactor EBR-II, USA. The scope of the CRP is to improve and validate the simulation tools for the study and the design of the liquid metal cooled fast reactors. Moreover, training of the next generation of fast reactor analysts is being also considered the other scope of the CRP. In this framework, a static neutronic model was developed, using state-of-the art neutron transport codes like SCALE/PHISICS (deterministic solution) and MCNP6 (stochastic solution).more » Comparison between both solutions is briefly illustrated in this summary.« less

  2. Thorium-based mixed oxide fuel in a pressurized water reactor: A feasibility analysis with MCNP

    NASA Astrophysics Data System (ADS)

    Tucker, Lucas Powelson

    This dissertation investigates techniques for spent fuel monitoring, and assesses the feasibility of using a thorium-based mixed oxide fuel in a conventional pressurized water reactor for plutonium disposition. Both non-paralyzing and paralyzing dead-time calculations were performed for the Portable Spectroscopic Fast Neutron Probe (N-Probe), which can be used for spent fuel interrogation. Also, a Canberra 3He neutron detector's dead-time was estimated using a combination of subcritical assembly measurements and MCNP simulations. Next, a multitude of fission products were identified as candidates for burnup and spent fuel analysis of irradiated mixed oxide fuel. The best isotopes for these applications were identified by investigating half-life, photon energy, fission yield, branching ratios, production modes, thermal neutron absorption cross section and fuel matrix diffusivity. 132I and 97Nb were identified as good candidates for MOX fuel on-line burnup analysis. In the second, and most important, part of this work, the feasibility of utilizing ThMOX fuel in a pressurized water reactor (PWR) was first examined under steady-state, beginning of life conditions. Using a three-dimensional MCNP model of a Westinghouse-type 17x17 PWR, several fuel compositions and configurations of a one-third ThMOX core were compared to a 100% UO2 core. A blanket-type arrangement of 5.5 wt% PuO2 was determined to be the best candidate for further analysis. Next, the safety of the ThMOX configuration was evaluated through three cycles of burnup at several using the following metrics: axial and radial nuclear hot channel factors, moderator and fuel temperature coefficients, delayed neutron fraction, and shutdown margin. Additionally, the performance of the ThMOX configuration was assessed by tracking cycle length, plutonium destroyed, and fission product poison concentration.

  3. The SSS classical nova V5116 Sgr

    NASA Astrophysics Data System (ADS)

    Sala, G.; Ness, J.; Greiner, J.; Hernanz, M.

    2017-10-01

    XMM-Newton observed the nova V5116 Sgr during its supersoft phase (SSS). V5116 Sgr showed a decrease of the flux by a factor around 8 during 2/3 of the orbital period. The broad band EPIC spectra remain unchanged during the different flux phases, suggesting an occultation of the central source in a high inclination system. While the global SED does not change significantly, the RGS spectrum is changing between the high and the low flux phases. The non-occultation phase shows a typical white dwarf atmosphere spectrum, dominated by absorption lines. During the low flux periods an extra component of emission lines is superimposed to the soft X-ray continuum. This supports the picture of V5116 Sgr as the clearest example of a system switching between the SSa class of SSS novae, with spectra dominated by absorption lines, and the SSe class, showing an emission lines component. In addition, the simultaneous OM images allow us to find a phase solution for the X-ray light-curve. A thick rim of the accretion disk as the one developed for the SSSs CAL 87, RX J0019.8, and RX J0513.9 could provide a plausible model both for the optical and the X-ray light curve of V5116 Sgr.

  4. V390 Nor = Nova Normae 2007

    NASA Astrophysics Data System (ADS)

    Waagen, Elizabeth O.

    2007-06-01

    Nova Normae 2007 was discovered photographically by William Liller on June 15.086 UT at magnitude 9.4. Precise position measured by G. Bolt from his unfiltered CCD image of June 16.7 UT: 16:32:11.51 -45:09:13.4 (2000.0). Giorgio Di Scala reported to the AAVSO that a low-resolution spectrum indicates a nova a week or so after outburst, with strong H-alpha emission. E. Kazarovets, Sternberg Astronomical Institute, reports that N Nor 07 has been assigned the name V390 Nor. Discovery originally announced in IAU Central Bureau Electronic Telegram 982 (Daniel W. E. Green) and AAVSO Special Notice #49 (Arne Henden). Information in this Alert Notice was received at AAVSO from William Liller, Giorgio Di Scala, or via IAU Circular No. 8850, ed. Daniel W. E. Green. A chart for V390 Nor is available via the Variable Star Plotter (VSP). Go to: http://www.aavso.org/observing/charts/vsp/ and enter the name V390 NOR.

  5. Lyalpha Absorption in Quiescent Dwarf Novae

    NASA Astrophysics Data System (ADS)

    Holm, A.; Lanning, H.; Mattei, J.; Nelan, E.

    1993-05-01

    International Ultraviolet Explorer (IUE) observations of dwarf novae RX And, TZ Per, WZ Sge, and SS Cyg in quiescence show broad absorption at Lyalpha . These features can be modeled reasonably well by the predicted spectrum of a hydrogen atmosphere white dwarf. RX And is best fit by a 35,000deg K model, TZ Per by a 18,000deg K model modified by an empirically determined disk contribution, and SS Cyg by a 34,000deg K model. The spectrum of WZ Sge following its December 1978 outburst is fit by a series of successively cooler white dwarf atmospheres, starting at 28,000deg K on 1979 Jan 1 and decreasing to 14,000deg K on 1987 July 5. Other dwarf novae, including SU UMa, EX Hya, and Z Cam, did not show absorption at Lyalpha at minimum. RX And, WZ Sge, and TZ Per also show strong absorption at 1400 Angstroms. If the observed far ultraviolet spectrum and the temperatures derived from the Lyalpha fitting are assumed to correspond to the white dwarf component, the 1400 Angstroms feature could be Si IV in RX And, but both WZ Sge and TZ Per would be too cool for Si IV. This raises questions about a photospheric origin for any of these features.

  6. Discovery of an Apparent Nova in M81

    NASA Astrophysics Data System (ADS)

    Hornoch, K.; Kucakova, H.; Williams, S. C.; Henze, M.; Sala, G.; Jose, J.; Figueira, J.; Sin, P.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

    2017-12-01

    The M81 nova monitoring collaboration reports the discovery of an apparent nova in M81 on a co-added 3150-s unfiltered CCD frame taken on 2017 Dec. 2.127 UT with the 0.65-m telescope at Ondrejov (OND).

  7. Independent Discovery of a Probable Nova in M81

    NASA Astrophysics Data System (ADS)

    Kucakova, H.; Hornoch, K.; Williams, S. C.; Henze, M.; Sala, G.; Jose, J.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

    2018-03-01

    The M81 nova monitoring collaboration reports the independent discovery of a probable nova in M81 on a co-added 1350-s unfiltered CCD frame taken on 2018 Mar. 21.952 UT with the 0.65-m telescope at Ondrejov.

  8. Discovery of a Probable Nova in M81

    NASA Astrophysics Data System (ADS)

    Hornoch, K.; Kucakova, H.; Williams, S. C.; Henze, M.; Sala, G.; Jose, J.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

    2018-01-01

    The M81 nova monitoring collaboration reports the discovery of a probable nova in M81 on a co-added 3150-s unfiltered CCD frame taken on 2018 Jan. 30.776 UT with the 0.65-m telescope at Ondrejov (OND).

  9. Independent Discovery of an Apparent Nova in M81

    NASA Astrophysics Data System (ADS)

    Hornoch, K.; Kucakova, H.; Williams, S. C.; Henze, M.; Sala, G.; Jose, J.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

    2018-02-01

    The M81 nova monitoring collaboration reports the independent discovery of an apparent nova in M81 on a co-added 2700-s unfiltered CCD frame taken on 2018 Feb. 19.039 UT with the 0.65-m telescope at Ondrejov (OND).

  10. Discovery of a Probable Nova in M81

    NASA Astrophysics Data System (ADS)

    Hornoch, K.; Kucakova, H.; Williams, S. C.; Henze, M.; Sala, G.; Jose, J.; Figueira, J.; Sin, P.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

    2017-12-01

    The M81 nova monitoring collaboration reports the discovery of a probable nova in M81 on a co-added 2610-s unfiltered CCD frame taken on 2017 Dec. 26.016 UT with the 0.65-m telescope at Ondrejov (OND).

  11. Results of Statewide TerraNova Testing, Fall 1998.

    ERIC Educational Resources Information Center

    La Marca, Paul M.

    This summary provides key findings about state, district, and school level performance on the TerraNova examinations (CTB/McGraw Hill) in Nevada in 1998-1999. The TerraNova tests are used to assess students in grades 4, 8, and 10 as stipulated by Nevada law. Within this summary, a description of performance as measured by national percentile…

  12. Independent Discovery of a Probable Luminous Nova in M81

    NASA Astrophysics Data System (ADS)

    Hornoch, K.; Kucakova, H.; Williams, S. C.; Henze, M.; Sala, G.; Jose, J.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

    2018-04-01

    The M81 nova monitoring collaboration reports the independent discovery of a probable luminous nova in M81 on a co-added 4410-s unfiltered CCD frame taken on 2018 Apr. 9.044 UT with the 0.65-m telescope at Ondrejov.

  13. Independent Discovery of a Probable Nova in M81

    NASA Astrophysics Data System (ADS)

    Hornoch, K.; Kucakova, H.; Williams, S. C.; Henze, M.; Sala, G.; Jose, J.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

    2018-04-01

    The M81 nova monitoring collaboration reports the independent discovery of a probable nova in M81 on a co-added 2700-s unfiltered CCD frame taken on 2018 Apr. 2.815 UT with the 0.65-m telescope at Ondrejov.

  14. Studies of Novae in the 20th Century

    NASA Astrophysics Data System (ADS)

    Starrfield, Sumner

    2002-11-01

    A nova outburst is not only the third most violent explosion that can occur in a galaxy, it is the largest hydrogen bomb in the Universe. The last meeting devoted purely to studies of novae was held in Madrid in 1989. At that time IUE spectra of novae were just beginning to be analyzed in detail, the EXOSAT x-ray results had just been published, and ROSAT had yet to be launched. Since that time, the IUE studies of novae in the LMC (known distance and small reddening) showed that all fast novae exceed the Eddington luminosity at maximum which was not predicted by numerical hydrodynamic simulations. A number of novae have now been observed in x-rays with ROSAT, BEPPOSAX, ASCA, CHANDRA, and XMM (plus others). The x-ray studies determined the turn off times for several classical novae, showed that at maximum x-ray light they resemble the Super Soft Sources, and found rapid variations in the x-ray light curves of two novae. There have been abundance analyses of V838 Her (oxygen poor, sulfur rich), LMC 1991, and other classical and recurrent novae. Infrared studies have resulted in a number of puzzling results such as the same nova producing both carbon (first) and silicate (later) dust at different times during its outburst. There have been advances in theoretical modeling and most studies now include large nuclear reaction networks combined with the hydrodynamic calculations. One perplexing problem produced by the simulations is that they predict that much less mass is ejected in the outburst than is observed, and the problem has worsened as the input physics has improved. Nevertheless we have made significant progress in the past 100 years and I will present some of the more important developments that have occurred over the past century. I will end with a list of questions to be answered.

  15. Observations and simulations of nova Vul 1984 no. 2: A nova with ejecta rich in oxygen, neon, and magnesium

    NASA Technical Reports Server (NTRS)

    Starrfield, S.; Sonneborn, G.; Stryker, L. L.; Sparks, Warren M.; Truran, James W.; Ferland, Gary; Wagner, R. M.; Gallagher, J. S.; Wade, R.; Williams, R. E.

    1988-01-01

    Nova Vul 1984 no. 2 was observed with IUE from Dec. 1984 through Nov. 1987. The spectra are characterized by strong lines from Mg, Ne, C, Si, O, N, and other elements. Data obtained in the ultraviolet, infrared, and optical show that this nova is ejecting material rich in oxygen, neon, and magnesium.

  16. Mining the Stony Brook/SMARTS Atlas of (mostly) Southern Novae: Photometric Studies of Dust Formation in Novae

    NASA Astrophysics Data System (ADS)

    Walter, Frederick M.; Fernandez, D.

    2014-01-01

    The Stony Brook/SMARTS Atlas of (mostly) Southern Novae contains broadband B through K photometry of over 70 novae. More than half of these have sufficient photometric coverage during their first few months that we can investigate the statistics of dust formation. Photometry in the optical alone is sensitive only to dust which forms on the line of sight; near-IR photometry is also sensitive to warm dust in other locations. None of 9 He-N novae were observed to have near-IR excesses interpretable as thermal dust emission, while 80% of classical novae do have excesses at JHK attributable to thermal dust emission. Only 40% of these show evidence for dust dips in the optical, suggesting the dust formation is non-spherical. We shall discuss thermal dust temperatures, masses, formation timescales, and the correlations of dust with optical spectra and nova types.

  17. Very high-energy γ -ray observations of novae and dwarf novae with the MAGIC telescopes

    DOE PAGES

    Ahnen, M. L.

    2015-10-01

    In the last five years the Fermi Large Area Telescope (LAT) instrument detected GeV γ-ray emission from five novae. The GeV emission can be interpreted in terms of an inverse Compton process of electrons accelerated in a shock. In this case it is expected that protons in the same conditions can be accelerated to much higher energies. Consequently they may produce a second component in the γ-ray spectrum at TeV energies.

  18. Why do Some Dwarf Novae Stand Still?

    NASA Technical Reports Server (NTRS)

    Sonneborn, George (Technical Monitor); Long, Knox

    2005-01-01

    The papers published through support of NASA. "Why do Some DwarfNovae Stand Still?" Preliminary results were published in the form of an abstract as part of Joint Discussion 5, at the IAU meeting in Sydney. The complete reference is: Hartley, L. E., Long, K. S., Froning, C.-S., & Drew, J. E. 2003, "The White Dwarf and Accretion Stream in Z Cam", presented as part of Joint Discussion 5, "White Dwarfs: Galactic and Cosmologic Probes, at 25th meeting of the MU, Joint Discussion 5 , 16-17 July 2003, Sydney, Australia Our final results were published in the Astrophysical Journal this year. Hartley, L. E., Long, K. S., Froning, C. S., & Drew, J. E. 2005, "The Far-Ultraviolet Spectrum of Z Camelopardalis in Quiescence and Standstill", ApJ, 623,425.

  19. Production of energetic light fragments in extensions of the CEM and LAQGSM event generators of the Monte Carlo transport code MCNP6 [Production of energetic light fragments in CEM, LAQGSM, and MCNP6

    DOE PAGES

    Mashnik, Stepan Georgievich; Kerby, Leslie Marie; Gudima, Konstantin K.; ...

    2017-03-23

    We extend the cascade-exciton model (CEM), and the Los Alamos version of the quark-gluon string model (LAQGSM), event generators of the Monte Carlo N-particle transport code version 6 (MCNP6), to describe production of energetic light fragments (LF) heavier than 4He from various nuclear reactions induced by particles and nuclei at energies up to about 1 TeV/nucleon. In these models, energetic LF can be produced via Fermi breakup, preequilibrium emission, and coalescence of cascade particles. Initially, we study several variations of the Fermi breakup model and choose the best option for these models. Then, we extend the modified exciton model (MEM)more » used by these codes to account for a possibility of multiple emission of up to 66 types of particles and LF (up to 28Mg) at the preequilibrium stage of reactions. Then, we expand the coalescence model to allow coalescence of LF from nucleons emitted at the intranuclear cascade stage of reactions and from lighter clusters, up to fragments with mass numbers A ≤ 7, in the case of CEM, and A ≤ 12, in the case of LAQGSM. Next, we modify MCNP6 to allow calculating and outputting spectra of LF and heavier products with arbitrary mass and charge numbers. The improved version of CEM is implemented into MCNP6. Lastly, we test the improved versions of CEM, LAQGSM, and MCNP6 on a variety of measured nuclear reactions. The modified codes give an improved description of energetic LF from particle- and nucleus-induced reactions; showing a good agreement with a variety of available experimental data. They have an improved predictive power compared to the previous versions and can be used as reliable tools in simulating applications involving such types of reactions.« less

  20. ORIGINS OF ABSORPTION SYSTEMS OF CLASSICAL NOVA V2659 CYG (NOVA CYG 2014)

    SciTech Connect

    Arai, A.; Kawakita, H.; Shinnaka, Y.

    2016-10-10

    We report on high-dispersion spectroscopy results of a classical nova V2659 Cyg (Nova Cyg 2014) that are taken 33.05 days after the V -band maximum. The spectrum shows two distinct blueshifted absorption systems originating from H i, Fe ii, Ca ii, etc. The radial velocities of the absorption systems are −620 km s{sup −1}, and −1100 to −1500 km s{sup −1}. The higher velocity component corresponds to the P-Cygni absorption features frequently observed in low-resolution spectra. Much larger numbers of absorption lines are identified at the lower velocity. These mainly originate from neutral or singly ionized Fe-peak elements (Fe i,more » Ti ii, Cr ii, etc.). Based on the results of our spectroscopic observations, we discuss the structure of the ejecta of V2659 Cyg. We conclude that the low- and high-velocity components are likely to be produced by the outflow wind and the ballistic nova ejecta, respectively.« less

  1. Non-detection of nova shells around asynchronous polars

    NASA Astrophysics Data System (ADS)

    Pagnotta, Ashley; Zurek, David

    2016-05-01

    Asynchronous polars (APs) are accreting white dwarfs (WDs) that have different WD and orbital angular velocities, unlike the rest of the known polars, which rotate synchronously (I.e. their WD and orbital angular velocities are the same). Past nova eruptions are the predicted cause of the asynchronicity, in part due to the fact that one of the APs, V1500 Cyg, was observed to undergo a nova eruption in 1975. We used the Southern African Large Telescope 10 m class telescope and the MDM 2.4 m Hiltner telescope to search for nova shells around three of the remaining four APs (V1432 Aql, BY Cam, and CD Ind) as well as one Intermediate Polar with a high asynchronicity (EX Hya). We found no evidence of nova shells in any of our images. We therefore cannot say that any of the systems besides V1500 Cyg had nova eruptions, but because not all post-nova systems have detectable shells, we also cannot exclude the possibility of a nova eruption occurring in any of these systems and knocking the rotation out of sync.

  2. Calculation of the store house worker dose in a lost wax foundry using MCNP-4C.

    PubMed

    Alegría, Natalia; Legarda, Fernando; Herranz, Margarita; Idoeta, Raquel

    2005-01-01

    Lost wax casting is an industrial process which permits the transmutation into metal of models made in wax. The wax model is covered with a silicaceous shell of the required thickness and once this shell is built the set is heated and wax melted. Liquid metal is then cast into the shell replacing the wax. When the metal is cool, the shell is broken away in order to recover the metallic piece. In this process zircon sands are used for the preparation of the silicaceous shell. These sands have varying concentrations of natural radionuclides: 238U, 232Th and 235U together with their progenics. The zircon sand is distributed in bags of 50 kg, and 30 bags are on a pallet, weighing 1,500 kg. The pallets with the bags have dimensions 80 cm x 120 cm x 80 cm, and constitute the radiation source in this case. The only pathway of exposure to workers in the store house is external radiation. In this case there is no dust because the bags are closed and covered by plastic, the store house has a good ventilation rate and so radon accumulation is not possible. The workers do not touch with their hands the bags and consequently skin contamination will not take place. In this study all situations of external irradiation to the workers have been considered; transportation of the pallets from vehicle to store house, lifting the pallets to the shelf, resting of the stock on the shelf, getting down the pallets, and carrying the pallets to production area. Using MCNP-4C exposure situations have been simulated, considering that the source has a homogeneous composition, the minimum stock in the store house is constituted by 7 pallets, and the several distances between pallets and workers when they are at work. The photons flux obtained by MCNP-4C is multiplied by the conversion factor of Flux to Kerma for air by conversion factor to Effective Dose by Kerma unit, and by the number of emitted photons. Those conversion factors are obtained of ICRP 74 table 1 and table 17 respectively. This

  3. Using MCNP6 to Estimate Fission Neutron Properties of a Reflected Plutonium Sphere

    SciTech Connect

    Clark, Alexander Rich; Nelson, Mark Andrew; Hutchinson, Jesson D.

    2017-08-08

    The purpose of this project was to determine the fission multiplicity distribution, p(v), for the Beryllium Reflected Plutonium (BeRP) ball and to determine whether or not it changed appreciably for various High Density Polyethylene (HDPE) reflected configurations. The motivation for this project was to determine whether or not the average number of neutrons emitted per fission, v, changed significantly enough to reduce the discrepancy between MCNP6 and Robba, Dowdy, Atwater (RDA) point kinetic model estimates of multiplication. The energy spectrum of neutrons that induced fissions in the BeRP ball, NIF (E), was also computed in order to determine the averagemore » energy of neutrons inducing fissions, NIF . p(v) was computed using the FMULT card, NIF (E) and NIF were computed using an F4 tally with an FM tally modifier (F4/FM) card, and the multiplication factor, k eff, was computed using the KCODE card. Although NIF (E) changed significantly between bare and HDPE reflected configurations of the BeRP ball, the change in p(v), and thus the change in v, was insignificant. This is likely due to a difference between the way that NIF is computed using the FMULT and F4/FM cards. The F4/FM card indicated that NIF (E) was essentially Watt-fission distributed for a bare configuration and highly thermalized for all HDPE reflected configurations, while the FMULT card returned an average energy between 1 and 2 MeV for all configurations, which would indicate that the spectrum is Watt-fission distributed, regardless of the amount of HDPE reflector. The spectrum computed with the F4/FM cards is more physically meaningful and so the discrepancy between it and the FMULT card result is being investigated. It is hoped that resolving the discrepancy between the FMULT and F4/FM card estimates of NIF(E) will provide better v estimates that will lead to RDA multiplication estimates that are in better agreement with MCNP6 simulations.« less

  4. Determination of {beta}{sub eff} using MCNP-4C2 and application to the CROCUS and PROTEUS reactors

    SciTech Connect

    Vollaire, J.; Plaschy, M.; Jatuff, F.

    2006-07-01

    A new Monte Carlo method for the determination of {beta}{sub eff} has been recently developed and tested using appropriate models of the experimental reactors CROCUS and PROTEUS. The current paper describes the applied methodology and highlights the resulting improvements compared to the simplest MCNP approach, i.e. the 'prompt method' technique. In addition, the flexibility advantages of the developed method are presented. Specifically, the possibility to obtain the effective delayed neutron fraction {beta}{sub eff} per delayed neutron group, per fissioning nuclide and per reactor region is illustrated. Finally, the MCNP predictions of {beta}{sub eff} are compared to the results of deterministicmore » calculations. (authors)« less

  5. SU-F-T-140: Assessment of the Proton Boron Fusion Reaction for Practical Radiation Therapy Applications Using MCNP6

    SciTech Connect

    Adam, D; Bednarz, B

    2016-06-15

    Purpose: The proton boron fusion reaction is a reaction that describes the creation of three alpha particles as the result of the interaction of a proton incident upon a 11B target. Theoretically, the proton boron fusion reaction is a desirable reaction for radiation therapy applications in that, with the appropriate boron delivery agent, it could potentially combine the localized dose delivery protons exhibit (Bragg peak) and the local deposition of high LET alpha particles in cancerous sites. Previous efforts have shown significant dose enhancement using the proton boron fusion reaction; the overarching purpose of this work is an attempt tomore » validate previous Monte Carlo results of the proton boron fusion reaction. Methods: The proton boron fusion reaction, 11B(p, 3α), is investigated using MCNP6 to assess the viability for potential use in radiation therapy. Simple simulations of a proton pencil beam incident upon both a water phantom and a water phantom with an axial region containing 100ppm boron were modeled using MCNP6 in order to determine the extent of the impact boron had upon the calculated energy deposition. Results: The maximum dose increase calculated was 0.026% for the incident 250 MeV proton beam scenario. The MCNP simulations performed demonstrated that the proton boron fusion reaction rate at clinically relevant boron concentrations was too small in order to have any measurable impact on the absorbed dose. Conclusion: For all MCNP6 simulations conducted, the increase of absorbed dose of a simple water phantom due to the 11B(p, 3α) reaction was found to be inconsequential. In addition, it was determined that there are no good evaluations of the 11B(p, 3α) reaction for use in MCNPX/6 and further work should be conducted in cross section evaluations in order to definitively evaluate the feasibility of the proton boron fusion reaction for use in radiation therapy applications.« less

  6. Tally and geometry definition influence on the computing time in radiotherapy treatment planning with MCNP Monte Carlo code.

    PubMed

    Juste, B; Miro, R; Gallardo, S; Santos, A; Verdu, G

    2006-01-01

    The present work has simulated the photon and electron transport in a Theratron 780 (MDS Nordion) (60)Co radiotherapy unit, using the Monte Carlo transport code, MCNP (Monte Carlo N-Particle), version 5. In order to become computationally more efficient in view of taking part in the practical field of radiotherapy treatment planning, this work is focused mainly on the analysis of dose results and on the required computing time of different tallies applied in the model to speed up calculations.

  7. Microstructures of Rare Silicate Stardust from Nova and Supernovae

    NASA Technical Reports Server (NTRS)

    Nguyen, A. N.; Keller, L. P.; Rahman, Z.; Messenger, S

    2011-01-01

    Most silicate stardust analyzed in the laboratory and observed around stellar environments derives from O-rich red giant and AGB stars [1,2]. Supernova (SN) silicates and oxides are comparatively rare, and fewer than 10 grains from no-va or binary star systems have been identified to date. Very little is known about dust formation in these stellar environments. Mineralogical studies of only three O-rich SN [3-5] and no nova grains have been performed. Here we report the microstructure and chemical makeup of two SN silicates and one nova grain.

  8. Liquid Scintillator Production for the NOvA Experiment

    DOE PAGES

    Mufson, S.; Baugh, B.; Bower, C.; ...

    2015-04-15

    The NOvA collaboration blended and delivered 8.8 kt (2.72M gal) of liquid scintillator as the active detector medium to its near and far detectors. The composition of this scintillator was specifically developed to satisfy NOvA's performance requirements. A rigorous set of quality control procedures was put in place to verify that the incoming components and the blended scintillator met these requirements. The scintillator was blended commercially in Hammond, IN. The scintillator was shipped to the NOvA detectors using dedicated stainless steel tanker trailers cleaned to food grade.

  9. SOFIA: A Promising Resource for Future Nova Studies

    NASA Astrophysics Data System (ADS)

    Helton, L. A.; Sofia Science Team

    2014-12-01

    The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a 2.5-m telescope carried on board a Boeing 747-SP aircraft. Optimized for observations from infrared through sub-mm wavelengths, SOFIA observes from an altitude of 37,000 - 45,000 feet, above 99% of the atmospheric water vapor. The Observatory's complement of instruments possesses a broad range of capabilities, many of which are especially well suited for observations of classical novae, recurrent novae, and other cataclysmic variables. Here we present a selection of the instruments available on board SOFIA that may prove to be very useful for future novae studies.

  10. MCNP6.1 simulations for low-energy atomic relaxation: Code-to-code comparison with GATEv7.2, PENELOPE2014, and EGSnrc

    NASA Astrophysics Data System (ADS)

    Jung, Seongmoon; Sung, Wonmo; Lee, Jaegi; Ye, Sung-Joon

    2018-01-01

    Emerging radiological applications of gold nanoparticles demand low-energy electron/photon transport calculations including details of an atomic relaxation process. Recently, MCNP® version 6.1 (MCNP6.1) has been released with extended cross-sections for low-energy electron/photon, subshell photoelectric cross-sections, and more detailed atomic relaxation data than the previous versions. With this new feature, the atomic relaxation process of MCNP6.1 has not been fully tested yet with its new physics library (eprdata12) that is based on the Evaluated Atomic Data Library (EADL). In this study, MCNP6.1 was compared with GATEv7.2, PENELOPE2014, and EGSnrc that have been often used to simulate low-energy atomic relaxation processes. The simulations were performed to acquire both photon and electron spectra produced by interactions of 15 keV electrons or photons with a 10-nm-thick gold nano-slab. The photon-induced fluorescence X-rays from MCNP6.1 fairly agreed with those from GATEv7.2 and PENELOPE2014, while the electron-induced fluorescence X-rays of the four codes showed more or less discrepancies. A coincidence was observed in the photon-induced Auger electrons simulated by MCNP6.1 and GATEv7.2. A recent release of MCNP6.1 with eprdata12 can be used to simulate the photon-induced atomic relaxation.

  11. Comparison of MCNP4C and EGSnrc Monte Carlo codes in depth-dose calculation of low energy clinical electron beams

    NASA Astrophysics Data System (ADS)

    Jabbari, N.; Hashemi-Malayeri, B.; Farajollahi, A. R.; Kazemnejad, A.; Shafaei, A.; Jabbari, S.

    2007-08-01

    Comparison of different Monte Carlo codes for understanding their limitations is essential to avoid systematic errors in the simulation, and to suggest further improvement for the codes. MCNP4C and EGSnrc, two Monte Carlo codes commonly used in medical physics, were compared and evaluated against electron depth-dose data and experimental results obtained using clinical radiotherapy beams. Different physical models and algorithms used in the codes give significantly different depth-dose curves. The default version of MCNP4C calculates electron depth-dose curves which are too much penetrating. The MCNP4C results agree better with the experiment if the Integrated Tiger Series-style energy-indexing algorithm is used. EGSnrc uses a class II-Condensed History (CH) scheme for the simulation of electron transport. To conclude the comparison, a timing study was performed. It was noted that EGSnrc is generally faster than MCNP4C and the use of a large number of scoring voxels dramatically slows down the MCNP4C calculation. However, the use of a large number of geometry voxels in MCNP4C only slightly affects the speed of the calculation.

  12. Comparison of MCNP6 and experimental results for neutron counts, Rossi-{alpha}, and Feynman-{alpha} distributions

    SciTech Connect

    Talamo, A.; Gohar, Y.; Sadovich, S.

    2013-07-01

    MCNP6, the general-purpose Monte Carlo N-Particle code, has the capability to perform time-dependent calculations by tracking the time interval between successive events of the neutron random walk. In fixed-source calculations for a subcritical assembly, the zero time value is assigned at the moment the neutron is emitted by the external neutron source. The PTRAC and F8 cards of MCNP allow to tally the time when a neutron is captured by {sup 3}He(n, p) reactions in the neutron detector. From this information, it is possible to build three different time distributions: neutron counts, Rossi-{alpha}, and Feynman-{alpha}. The neutron counts time distributionmore » represents the number of neutrons captured as a function of time. The Rossi-a distribution represents the number of neutron pairs captured as a function of the time interval between two capture events. The Feynman-a distribution represents the variance-to-mean ratio, minus one, of the neutron counts array as a function of a fixed time interval. The MCNP6 results for these three time distributions have been compared with the experimental data of the YALINA Thermal facility and have been found to be in quite good agreement. (authors)« less

  13. Validation of MCNP4A for UO{sub 2}-ThO{sub 2} systems in water

    SciTech Connect

    Revolinski, S.M.; Biswas, D.

    1996-12-31

    The Receiving Basin for Offsite Fuel (RBOF) at the Savannah River Site is a facility for receipt and storage of many varieties of spent nuclear fuels from off-site reactors. The purpose of this paper is to validate MCNP4A with the ENDF/B-V pointwise cross-section set with two sets of critical experiments using UO{sub 2}-ThO{sub 2} fuel rods in water and thereby develop a bias for use in the nuclear criticality safety studies involving Elk River Reactor (ERR) and Dresden fuels (also containing UO{sub 2}-ThO{sub 2}) stored in RBOF. Five Thorium Uranium Physics Experiments (TUPE), as documented in the Babcock & Wilcoxmore » (BAW-1191) report, and five Consolidated Edison Thorium Reactor (CETR) Criticals, as documented in the Babcock & Wilcox (BAW-1191) report, are identified as having the constituents desired for this validation as well as sufficient experimental details to allow accurate construction of MCNP4A calculation models. The validation has been performed on IBM RISC 6000 machines with the configuration-controlled version of the MCNP4A code. Of particular interest is an evaluation of the state of ENDF/B-V {sup 232}Th cross-section data for criticality safety studies.« less

  14. Observations and simulations of recurrent novae: U Sco and V394 CrA

    NASA Technical Reports Server (NTRS)

    Starrfield, S.; Sonneborn, G.; Sparks, Warren M.; Shaviv, G.; Williams, R. E.; Heathcote, S.; Ferland, Gary; Gehrz, Robert D.; Ney, Edward P.; Kenyon, Scott

    1988-01-01

    Observations and analysis of the Aug. 1987 outburst of the recurrent nova V394 CrA are presented. This nova is extremely fast and its outburst characteristics closely resemble those of the recurrent nova U Sco. Hydrodynamic simulations of the outbursts of recurrent novae were performed. Results as applied to the outbursts of V394 CrA and U Sco are summarized.

  15. Optimization of Shielding- Collimator Parameters for ING-27 Neutron Generator Using MCNP5

    NASA Astrophysics Data System (ADS)

    Hegazy, Aya Hamdy; Skoy, V. R.; Hossny, K.

    2018-04-01

    Neutron generators are now used in various fields. They produce only fast neutrons; D-D neutron generator produces 2.45 MeV neutrons and D-T produces 14.1 MeV neutrons. In order to optimize shielding-collimator parameters to achieve higher neutron flux at the investigated sample (The signal) with lower neutron and gamma rays flux at the area of the detectors, design iterations are widely used. This work was applied to ROMASHA setup, TANGRA project, FLNP, Joint Institute for Nuclear Research. The studied parameters were; (1) shielding-collimator material, (2) Distance between the shielding-collimator assembly first plate and center of the neutron beam, and (3) thickness of collimator sheets. MCNP5 was used to simulate ROMASHA setup after it was validated on the experimental results of irradiation of Carbon-12 sample for one hour to detect its 4.44 MeV characteristic gamma line. The ratio between the signal and total neutron flux that enters each detector was calculated and plotted, concluding that the optimum shielding-collimator assembly is Tungsten of 5 cm thickness for each plate, and a distance of 2.3 cm. Also, the ratio between the signal and total gamma rays flux was calculated and plotted for each detector, leading to the previous conclusion but the distance was 1 cm.

  16. Multi-group Fokker-Planck proton transport in MCNP{trademark}

    SciTech Connect

    Adams, K.J.

    1997-11-01

    MCNP has been enhanced to perform proton transport using a multigroup Fokker Planck (MGFP) algorithm with primary emphasis on proton radiography simulations. The new method solves the Fokker Planck approximation to the Boltzmann transport equation for the small angle multiple scattering portion of proton transport. Energy loss is accounted for by applying a group averaged stopping power over each transport step. Large angle scatter and non-inelastic events are treated as extinction. Comparisons with the more rigorous LAHET code show agreement to a few per cent for the total transmitted currents. The angular distributions through copper and low Z compounds showmore » good agreement between LAHET and MGFP with the MGFP method being slightly less forward peaked and without the large angle tails apparent in the LAHET simulation. Suitability of this method for proton radiography simulations is shown for a simple problem of a hole in a copper slab. LAHET and MGFP calculations of position, angle and energy through more complex objects are presented.« less

  17. Performance of the MTR core with MOX fuel using the MCNP4C2 code.

    PubMed

    Shaaban, Ismail; Albarhoum, Mohamad

    2016-08-01

    The MCNP4C2 code was used to simulate the MTR-22 MW research reactor and perform the neutronic analysis for a new fuel namely: a MOX (U3O8&PuO2) fuel dispersed in an Al matrix for One Neutronic Trap (ONT) and Three Neutronic Traps (TNTs) in its core. Its new characteristics were compared to its original characteristics based on the U3O8-Al fuel. Experimental data for the neutronic parameters including criticality relative to the MTR-22 MW reactor for the original U3O8-Al fuel at nominal power were used to validate the calculated values and were found acceptable. The achieved results seem to confirm that the use of MOX fuel in the MTR-22 MW will not degrade the safe operational conditions of the reactor. In addition, the use of MOX fuel in the MTR-22 MW core leads to reduce the uranium fuel enrichment with (235)U and the amount of loaded (235)U in the core by about 34.84% and 15.21% for the ONT and TNTs cases, respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. A Hubble Space Telescope survey for novae in M87.I. light and color curves, spatial distributions, and the nova rate

    DOE PAGES

    Shara, Michael M.; Doyle, Trisha F.; Lauer, Tod R.; ...

    2016-11-08

    The Hubble Space Telescope has imaged the central part of M87 over a 10 week span, leading to the discovery of 32 classical novae (CNe) and nine fainter, likely very slow, and/or symbiotic novae. In this first paper of a series, we present the M87 nova finder charts, and the light and color curves of the novae. We demonstrate that the rise and decline times, and the colors of M87 novae are uncorrelated with each other and with position in the galaxy. The spatial distribution of the M87 novae follows the light of the galaxy, suggesting that novae accreted by M87 during cannibalistic episodes are well-mixed. Conservatively using only the 32 brightest CNe we derive a nova rate for M87:more » $${363}_{-45}^{+33}$$ novae yr –1. We also derive the luminosity-specific classical nova rate for this galaxy, which is $${7.88}_{-2.6}^{+2.3}\\,{\\mathrm{yr}}^{-1}/{10}^{10}\\,{L}_{\\odot }{,}_{K}$$. Both rates are 3–4 times higher than those reported for M87 in the past, and similarly higher than those reported for all other galaxies. As a result, we suggest that most previous ground-based surveys for novae in external galaxies, including M87, miss most faint, fast novae, and almost all slow novae near the centers of galaxies.« less

  19. Implementation of On-the-Fly Doppler Broadening in MCNP5 for Multiphysics Simulation of Nuclear Reactors

    SciTech Connect

    William Martin

    2012-11-16

    A new method to obtain Doppler broadened cross sections has been implemented into MCNP, removing the need to generate cross sections for isotopes at problem temperatures. Previous work had established the scientific feasibility of obtaining Doppler-broadened cross sections "on-the-fly" (OTF) during the random walk of the neutron. Thus, when a neutron of energy E enters a material region that is at some temperature T, the cross sections for that material at the exact temperature T are immediately obtained by interpolation using a high order functional expansion for the temperature dependence of the Doppler-broadened cross section for that isotope at themore » neutron energy E. A standalone Fortran code has been developed that generates the OTF library for any isotope that can be processed by NJOY. The OTF cross sections agree with the NJOY-based cross sections for all neutron energies and all temperatures in the range specified by the user, e.g., 250K - 3200K. The OTF methodology has been successfully implemented into the MCNP Monte Carlo code and has been tested on several test problems by comparing MCNP with conventional ACE cross sections versus MCNP with OTF cross sections. The test problems include the Doppler defect reactivity benchmark suite and two full-core VHTR configurations, including one with multiphysics coupling using RELAP5-3D/ATHENA for the thermal-hydraulic analysis. The comparison has been excellent, verifying that the OTF libraries can be used in place of the conventional ACE libraries generated at problem temperatures. In addition, it has been found that using OTF cross sections greatly reduces the complexity of the input for MCNP, especially for full-core temperature feedback calculations with many temperature regions. This results in an order of magnitude decrease in the number of input lines for full-core configurations, thus simplifying input preparation and reducing the potential for input errors. Finally, for full-core problems with

  20. Ocean and Coastal Acidification off New England and Nova Scotia

    EPA Science Inventory

    New England coastal and adjacent Nova Scotia shelf waters have a reduced buffering capacity because of significant freshwater input, making the region’s waters potentially more vulnerable to coastal acidification. Nutrient loading and heavy precipitation events further acid...

  1. X ray and gamma ray emission from classical nova outbursts

    NASA Technical Reports Server (NTRS)

    Truran, James W.; Starrfield, Sumner; Sparks, Warren M.

    1992-01-01

    The outbursts of classical novae are now recognized to be consequences of thermonuclear runaways proceeding in accreted hydrogen-rich shells on white dwarfs in close binary systems. For the conditions that are known to exist in these environments, it is expected that soft x-rays can be emitted, and indeed x-rays were detected from a number of novae. The circumstances for which we expect novae to produce significant x-ray fluxes and provide estimates of the luminosities and effective temperatures are described. It is also known that at the high temperatures that are known to be achieved in this explosive hydrogen-burning environment, significant production of both Na-22 and Al-26 will occur. In this context, we identify the conditions for which gamma-ray emission may be expected to result from nova outbursts.

  2. Nova Sagittarii 2015 No. 2 = PNV J18365700-2855420

    NASA Astrophysics Data System (ADS)

    Waagen, Elizabeth O.

    2015-03-01

    The discovery of Nova Sgr 2015 No. 2 = PNV J18365700-2855420 [V5668 Sgr] is announced. The nova was discovered by John Seach (Chatsworth Island, NSW, Australia) at magnitude: 6.0 using DSLR and 50mm f/1.0 lens on 2015 March 15.634 UT. Position (2000): R.A. 18 36 56.84 Dec. -28 55 39.8. An optical spectrum by S. C. Williams et al. (ATel #7230) indicate N Sgr 2015 No. 2 is a classical Fe II nova; a low-resolution spectrum by J. Powles (PJOC, Latham, ACT, Australia) appears to be that of a Fe II nova shortly after maximum. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

  3. A Comprehensive Review of Nova-Like Variable Stars

    NASA Astrophysics Data System (ADS)

    Sion, Edward

    2016-07-01

    A comprehensive review of nova-like variable stars of the VY Sculptoris and UX Ursa Majoris subtypes is presented. All that has been learned, up to the present time, from observations in the X-ray, far ultraviolet, optical and infrared bandpasses will be discussed. Spectroscopic analyses of high optical brightness states and low optical brightness states of nova-like variables will be summarized. The application of standard and non-standard accretion disk models as well as boundary layer structure will be discussed. The results of searches for nova shells, the evolutionary state of nova-likes as well as new spectroscopic results on BZ Cam (the bow shock CV) and BB Dor will also be included. This work is supported by NASA ADP grants NNX13AF12G and NNX13AF11G to Villanova University.

  4. Water recycling at the Nova Scotia Hospital Central Laundry.

    PubMed

    Bligh, David; Dingwell, Dylan

    2017-03-01

    A water recycling system was installed at the Nova Scotia Hospital Central Laundry in Dartmouth, Nova Scotia in the spring of 2014. The consequent reductions in the consumption of water and steam at this facility have been measured over a 20-month period and are presented here in nominal units and as a financial analysis. Cumulative savings over this period have been calculated to be $351,567, representing a 53% annual return on investment after accounting for annual operating and maintenance costs.

  5. Synthesis of C-rich dust in CO nova outbursts

    NASA Astrophysics Data System (ADS)

    José, Jordi; Halabi, Ghina M.; El Eid, Mounib F.

    2016-09-01

    Context. Classical novae are thermonuclear explosions that take place in the envelopes of accreting white dwarfs in stellar binary systems. The material transferred onto the white dwarf piles up under degenerate conditions, driving a thermonuclear runaway. In these outbursts, about 10-7-10-3 M⊙, enriched in CNO and sometimes other intermediate-mass elements (e.g., Ne, Na, Mg, or Al for ONe novae) are ejected into the interstellar medium. The large concentrations of metals spectroscopically inferred in the nova ejecta reveal that the solar-like material transferred from the secondary mixes with the outermost layers of the underlying white dwarf. Aims: Most theoretical models of nova outbursts reported to date yield, on average, outflows characterized by O > C, from which, in principle, only oxidized condensates (e.g., O-rich grains) would be expected. Methods: To specifically address whether CO novae can actually produce C-rich dust, six different hydrodynamic nova models have been evolved, from accretion to the expansion and ejection stages, with different choices for the composition of the substrate with which the solar-like accreted material mixes. Updated chemical profiles inside the H-exhausted core have been used, based on stellar evolution calculations for a progenitor of 8 M⊙ through H- and He-burning phases. Results: We show that these profiles lead to C-rich ejecta after the nova outburst. This extends the possible contribution of novae to the inventory of presolar grains identified in meteorites, particularly in a number of carbonaceous phases (I.e., nanodiamonds, silicon carbides, and graphites).

  6. ON THE SPECTROSCOPIC CLASSES OF NOVAE IN M33

    SciTech Connect

    Shafter, A. W.; Darnley, M. J.; Bode, M. F.

    2012-06-20

    We report the initial results from an ongoing multi-year spectroscopic survey of novae in M33. The survey resulted in the spectroscopic classification of six novae (M33N 2006-09a, 2007-09a, 2009-01a, 2010-10a, 2010-11a, and 2011-12a) and a determination of rates of decline (t{sub 2} times) for four of them (2006-09a, 2007-09a, 2009-01a, and 2010-10a). When these data are combined with existing spectroscopic data for two additional M33 novae (2003-09a and 2008-02a), we find that five of the eight novae with available spectroscopic class appear to be members of either the He/N or Fe IIb (hybrid) classes, with only two clear members ofmore » the Fe II spectroscopic class. This initial finding is very different from what would be expected based on the results for M31 and the Galaxy where Fe II novae dominate, and the He/N and Fe IIb classes together make up only {approx}20% of the total. It is plausible that the increased fraction of He/N and Fe IIb novae observed in M33 thus far may be the result of the younger stellar population that dominates this galaxy, which is expected to produce novae that harbor generally more massive white dwarfs than those typically associated with novae in M31 or the Milky Way.« less

  7. On Presolar Stardust Grains from CO Classical Novae

    NASA Astrophysics Data System (ADS)

    Iliadis, Christian; Downen, Lori N.; José, Jordi; Nittler, Larry R.; Starrfield, Sumner

    2018-03-01

    About 30%–40% of classical novae produce dust 20–100 days after the outburst, but no presolar stardust grains from classical novae have been unambiguously identified yet. Although several studies claimed a nova paternity for certain grains, the measured and simulated isotopic ratios could only be reconciled, assuming that the grains condensed after the nova ejecta mixed with a much larger amount of close-to-solar matter. However, the source and mechanism of this potential post-explosion dilution of the ejecta remains a mystery. A major problem with previous studies is the small number of simulations performed and the implied poor exploration of the large nova parameter space. We report the results of a different strategy, based on a Monte Carlo technique, that involves the random sampling over the most important nova model parameters: the white dwarf composition; the mixing of the outer white dwarf layers with the accreted material before the explosion; the peak temperature and density; the explosion timescales; and the possible dilution of the ejecta after the outburst. We discuss and take into account the systematic uncertainties for both the presolar grain measurements and the simulation results. Only those simulations that are consistent with all measured isotopic ratios of a given grain are accepted for further analysis. We also present the numerical results of the model parameters. We identify 18 presolar grains with measured isotopic signatures consistent with a CO nova origin, without assuming any dilution of the ejecta. Among these, the grains G270_2, M11-334-2, G278, M11-347-4, M11-151-4, and Ag26 have the highest probability of a CO nova paternity.

  8. Detecting Nova Shells around known Cataclysmic Variable systems

    NASA Astrophysics Data System (ADS)

    Xhakaj, Enia; Kupfer, Thomas; Prince, Thomas A.

    2017-01-01

    Nova shells are hydrogen-rich nebulae around Cataclysmic Variables that are created when a Nova outburst takes place. Learning more about Nova shells can help us get a better understanding of the long-term evolution of white dwarfs in active Cataclysmic Variables. In this project, we present the search for Nova shells around 1700 Cataclysmic Variables, using Hα images from the Palomar Transient Factory (PTF) survey. The PTF Hα survey started in 2009 using the 48’’ Oschin telescope at Palomar Observatory and is the first of its type covering the whole northern hemisphere while reaching 18 mags in 60 seconds of exposure. We concentrated our search on the IAU catalogue of Historical Novae, as well as on the SDSS and the Ritter-Kolb catalogue of Cataclysmic Variables. We numerically analyzed radial profiles centered on the target sources to search for excess emission potentially associated with the shells. Out of 1700 Cataclysmic Variables present in these catalogues, we detected 25 Nova shells, out of which 20 are not observed before.

  9. Can isolated single black holes produce X-ray novae?

    NASA Astrophysics Data System (ADS)

    Matsumoto, Tatsuya; Teraki, Yuto; Ioka, Kunihito

    2018-03-01

    Almost all black holes (BHs) and BH candidates in our Galaxy have been discovered as soft X-ray transients, so-called X-ray novae. X-ray novae are usually considered to arise from binary systems. Here, we propose that X-ray novae are also caused by isolated single BHs. We calculate the distribution of the accretion rate from interstellar matter to isolated BHs, and find that BHs in molecular clouds satisfy the condition of the hydrogen-ionization disc instability, which results in X-ray novae. The estimated event rate is consistent with the observed one. We also check an X-ray novae catalogue (Corral-Santana et al.) and find that 16/59 ˜ 0.27 of the observed X-ray novae are potentially powered by isolated BHs. The possible candidates include IGR J17454-2919, XTE J1908-094, and SAX J1711.6-3808. Near-infrared photometric and spectroscopic follow-ups can exclude companion stars for a BH census in our Galaxy.

  10. Novae as a Class of Transient X-ray Sources

    NASA Technical Reports Server (NTRS)

    Mukai, K.; Orio, M.; Valle, M. Della

    2007-01-01

    Motivated by the recently discovered class of faint (10(exp 34)-10(exp 35) ergs/s) X-ray transients in the Galactic Center region, we investigate the 2-10 keV properties of classical and recurrent novae. Existing data are consistent with the idea that all classical novae are transient X-ray sources with durations of months to years and peak luminosities in the 10(exp 34)-10(exp 35)ergs/s range. This makes classical novae a viable candidate class for the faint Galactic Center transients. We estimate the rate of classical novae within a 15 arcmin radius region centered on the Galactic Center (roughly the field of view of XMM-Newton observations centered on Sgr A*) to be approx.0.1 per year. Therefore, it is plausible that some of the Galactic Center transients that have been announced to date are unrecognized classical novae. The continuing monitoring of the Galactic Center region carried out by Chandra and XMM-Newton may therefore provide a new method to detect classical novae in this crowded and obscured region, an

  11. T Pyxidis: death by a thousand novae

    NASA Astrophysics Data System (ADS)

    Patterson, Joseph; Oksanen, Arto; Kemp, Jonathan; Monard, Berto; Rea, Robert; Hambsch, Franz-Josef; McCormick, Jennie; Nelson, Peter; Allen, William; Krajci, Thomas; Lowther, Simon; Dvorak, Shawn; Borgman, Jordan; Richards, Thomas; Myers, Gordon; Harlingten, Caisey; Bolt, Greg

    2017-04-01

    We report a 20-yr campaign to track the 1.8 h photometric (and orbital) wave in the recurrent nova T Pyxidis. Before and after the 2011 eruption, the period increased on a time-scale P/dot{P} = 3 × 105 yr. This suggests a mass transfer rate in quiescence of ˜10-7 M⊙ yr-1, in substantial agreement with the accretion rate based on the star's luminosity. During the eruption itself, a rapid period increase of 0.0054(7) per cent occurred. This is probably a measure of the mass ejected in the outburst. For a plausible choice of binary parameters, that mass is at least 3 × 10-5 M⊙, and probably more. This represents >300 yr of accretion at the pre-outburst rate, but the time between outbursts was only 45 yr. Thus, the erupting white dwarf (WD) seems to have ejected at least six times more mass than it accreted. If this eruption is typical, the WD must be eroding, rather than growing, in mass. Unless the present series of eruptions is a short-lived episode, the binary dynamics will evaporate the secondary in ˜105 yr. This could be a major channel by which short-period cataclysmic variables are removed from the population.

  12. Aminoglycoside binding to Oxytricha Nova Telomeric DNA

    PubMed Central

    Ranjan, Nihar; Andreasen, Katrine F.; Kumar, Sunil; Hyde-volpe, David; Arya, Dev P.

    2012-01-01

    Telomeric DNA sequences have been at the center stage of drug design for cancer treatment in recent years. The ability of these DNA structures to form four stranded nucleic acid structures, called G-quadruplexes, has been perceived as target for inhibiting telomerase activity vital for the longevity of cancer cells. Being highly diverse in structural forms, these G-quadruplexes are subjects of detailed studies of ligand–DNA interactions of different classes, which will pave the way for logical design of more potent ligands in future. The binding of aminoglycosides were investigated with Oxytricha Nova quadruplex forming DNA sequence (GGGGTTTTGGGG)2. Isothermal Titration calorimetry (ITC) determined ligand to quadruplex binding ratio shows 1:1 neomycin:quadruplex binding with association constants (Ka ) ~ 105M−1 while paromomycin was found to have a two-fold weaker affinity than neomycin. The CD titration experiments with neomycin resulted in minimal changes in the CD signal. FID assays, performed to determine the minimum concentration required to displace half of the fluorescent probe bound, showed neomycin as the best of the all aminoglycosides studied for quadruplex binding. Initial NMR footprint suggests that ligand-DNA interactions occur in the wide groove of the quadruplex. Computational docking studies also indicate that aminoglycosides bind in the wide groove of the quadruplex. PMID:20886815

  13. Validation of MCNP6 Version 1.0 with the ENDF/B-VII.1 Cross Section Library for Uranium Metal, Oxide, and Solution Systems on the High Performance Computing Platform Moonlight

    SciTech Connect

    Chapman, Bryan Scott; MacQuigg, Michael Robert; Wysong, Andrew Russell

    2016-04-21

    In this document, the code MCNP is validated with ENDF/B-VII.1 cross section data under the purview of ANSI/ANS-8.24-2007, for use with uranium systems. MCNP is a computer code based on Monte Carlo transport methods. While MCNP has wide reading capability in nuclear transport simulation, this validation is limited to the functionality related to neutron transport and calculation of criticality parameters such as k eff.

  14. A voxel-based mouse for internal dose calculations using Monte Carlo simulations (MCNP)

    NASA Astrophysics Data System (ADS)

    Bitar, A.; Lisbona, A.; Thedrez, P.; Sai Maurel, C.; LeForestier, D.; Barbet, J.; Bardies, M.

    2007-02-01

    Murine models are useful for targeted radiotherapy pre-clinical experiments. These models can help to assess the potential interest of new radiopharmaceuticals. In this study, we developed a voxel-based mouse for dosimetric estimates. A female nude mouse (30 g) was frozen and cut into slices. High-resolution digital photographs were taken directly on the frozen block after each section. Images were segmented manually. Monoenergetic photon or electron sources were simulated using the MCNP4c2 Monte Carlo code for each source organ, in order to give tables of S-factors (in Gy Bq-1 s-1) for all target organs. Results obtained from monoenergetic particles were then used to generate S-factors for several radionuclides of potential interest in targeted radiotherapy. Thirteen source and 25 target regions were considered in this study. For each source region, 16 photon and 16 electron energies were simulated. Absorbed fractions, specific absorbed fractions and S-factors were calculated for 16 radionuclides of interest for targeted radiotherapy. The results obtained generally agree well with data published previously. For electron energies ranging from 0.1 to 2.5 MeV, the self-absorbed fraction varies from 0.98 to 0.376 for the liver, and from 0.89 to 0.04 for the thyroid. Electrons cannot be considered as 'non-penetrating' radiation for energies above 0.5 MeV for mouse organs. This observation can be generalized to radionuclides: for example, the beta self-absorbed fraction for the thyroid was 0.616 for I-131; absorbed fractions for Y-90 for left kidney-to-left kidney and for left kidney-to-spleen were 0.486 and 0.058, respectively. Our voxel-based mouse allowed us to generate a dosimetric database for use in preclinical targeted radiotherapy experiments.

  15. Testing actinide fission yield treatment in CINDER90 for use in MCNP6 burnup calculations

    DOE PAGES

    Fensin, Michael Lorne; Umbel, Marissa

    2015-09-18

    Most of the development of the MCNPX/6 burnup capability focused on features that were applied to the Boltzman transport or used to prepare coefficients for use in CINDER90, with little change to CINDER90 or the CINDER90 data. Though a scheme exists for best solving the coupled Boltzman and Bateman equations, the most significant approximation is that the employed nuclear data are correct and complete. Thus, the CINDER90 library file contains 60 different actinide fission yields encompassing 36 fissionable actinides (thermal, fast, high energy and spontaneous fission). Fission reaction data exists for more than 60 actinides and as a result, fissionmore » yield data must be approximated for actinides that do not possess fission yield information. Several types of approximations are used for estimating fission yields for actinides which do not possess explicit fission yield data. The objective of this study is to test whether or not certain approximations of fission yield selection have any impact on predictability of major actinides and fission products. Further we assess which other fission products, available in MCNP6 Tier 3, result in the largest difference in production. Because the CINDER90 library file is in ASCII format and therefore easily amendable, we assess reasons for choosing, as well as compare actinide and major fission product prediction for the H. B. Robinson benchmark for, three separate fission yield selection methods: (1) the current CINDER90 library file method (Base); (2) the element method (Element); and (3) the isobar method (Isobar). Results show that the three methods tested result in similar prediction of major actinides, Tc-99 and Cs-137; however, certain fission products resulted in significantly different production depending on the method of choice.« less

  16. Neutron Fluence And DPA Rate Analysis In Pebble-Bed HTR Reactor Vessel Using MCNP

    NASA Astrophysics Data System (ADS)

    Hamzah, Amir; Suwoto; Rohanda, Anis; Adrial, Hery; Bakhri, Syaiful; Sunaryo, Geni Rina

    2018-02-01

    In the Pebble-bed HTR reactor, the distance between the core and the reactor vessel is very close and the media inside are carbon and He gas. Neutron moderation capability of graphite material is theoretically lower than that of water-moderated reactors. Thus, it is estimated much more the fast neutrons will reach the reactor vessel. The fast neutron collisions with the atoms in the reactor vessel will result in radiation damage and could be reducing the vessel life. The purpose of this study was to obtain the magnitude of neutron fluence in the Pebble-bed HTR reactor vessel. Neutron fluence calculations in the pebble-bed HTR reactor vessel were performed using the MCNP computer program. By determining the tally position, it can be calculated flux, spectrum and neutron fluence in the position of Pebble-bed HTR reactor vessel. The calculations results of total neutron flux and fast neutron flux in the reactor vessel of 1.82x108 n/cm2/s and 1.79x108 n/cm2/s respectively. The fast neutron fluence in the reactor vessel is 3.4x1017 n/cm2 for 60 years reactor operation. Radiation damage in stainless steel material caused by high-energy neutrons (> 1.0 MeV) will occur when it has reached the neutron flux level of 1.0x1024 n/cm2. The neutron fluence results show that there is no radiation damage in the Pebble-bed HTR reactor vessel, so it is predicted that it will be safe to operate at least for 60 years.

  17. A calibration method for realistic neutron dosimetry in radiobiological experiments assisted by MCNP simulation.

    PubMed

    Shahmohammadi Beni, Mehrdad; Krstic, Dragana; Nikezic, Dragoslav; Yu, Kwan Ngok

    2016-09-01

    Many studies on biological effects of neutrons involve dose responses of neutrons, which rely on accurately determined absorbed doses in the irradiated cells or living organisms. Absorbed doses are difficult to measure, and are commonly surrogated with doses measured using separate detectors. The present work describes the determination of doses absorbed in the cell layer underneath a medium column (D A ) and the doses absorbed in an ionization chamber (D E ) from neutrons through computer simulations using the MCNP-5 code, and the subsequent determination of the conversion coefficients R (= D A /D E ). It was found that R in general decreased with increase in the medium thickness, which was due to elastic and inelastic scattering. For 2-MeV neutrons, conspicuous bulges in R values were observed at medium thicknesses of about 500, 1500, 2500 and 4000 μm, and these were attributed to carbon, oxygen and nitrogen nuclei, and were reflections of spikes in neutron interaction cross sections with these nuclei. For 0.1-MeV neutrons, no conspicuous bulges in R were observed (except one at ~2000 μm that was due to photon interactions), which was explained by the absence of prominent spikes in the interaction cross-sections with these nuclei for neutron energies <0.1 MeV. The ratio R could be increased by ~50% for small medium thickness if the incident neutron energy was reduced from 2 MeV to 0.1 MeV. As such, the absorbed doses in cells (D A ) would vary with the incident neutron energies, even when the absorbed doses shown on the detector were the same. © The Author 2016. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

  18. A calibration method for realistic neutron dosimetry in radiobiological experiments assisted by MCNP simulation

    PubMed Central

    Shahmohammadi Beni, Mehrdad; Krstic, Dragana; Nikezic, Dragoslav; Yu, Kwan Ngok

    2016-01-01

    Many studies on biological effects of neutrons involve dose responses of neutrons, which rely on accurately determined absorbed doses in the irradiated cells or living organisms. Absorbed doses are difficult to measure, and are commonly surrogated with doses measured using separate detectors. The present work describes the determination of doses absorbed in the cell layer underneath a medium column (DA) and the doses absorbed in an ionization chamber (DE) from neutrons through computer simulations using the MCNP-5 code, and the subsequent determination of the conversion coefficients R (= DA/DE). It was found that R in general decreased with increase in the medium thickness, which was due to elastic and inelastic scattering. For 2-MeV neutrons, conspicuous bulges in R values were observed at medium thicknesses of about 500, 1500, 2500 and 4000 μm, and these were attributed to carbon, oxygen and nitrogen nuclei, and were reflections of spikes in neutron interaction cross sections with these nuclei. For 0.1-MeV neutrons, no conspicuous bulges in R were observed (except one at ~2000 μm that was due to photon interactions), which was explained by the absence of prominent spikes in the interaction cross-sections with these nuclei for neutron energies <0.1 MeV. The ratio R could be increased by ~50% for small medium thickness if the incident neutron energy was reduced from 2 MeV to 0.1 MeV. As such, the absorbed doses in cells (DA) would vary with the incident neutron energies, even when the absorbed doses shown on the detector were the same. PMID:27380801

  19. SU-E-T-212: Comparison of TG-43 Dosimetric Parameters of Low and High Energy Brachytherapy Sources Obtained by MCNP Code Versions of 4C, X and 5

    SciTech Connect

    Zehtabian, M; Zaker, N; Sina, S

    2015-06-15

    Purpose: Different versions of MCNP code are widely used for dosimetry purposes. The purpose of this study is to compare different versions of the MCNP codes in dosimetric evaluation of different brachytherapy sources. Methods: The TG-43 parameters such as dose rate constant, radial dose function, and anisotropy function of different brachytherapy sources, i.e. Pd-103, I-125, Ir-192, and Cs-137 were calculated in water phantom. The results obtained by three versions of Monte Carlo codes (MCNP4C, MCNPX, MCNP5) were compared for low and high energy brachytherapy sources. Then the cross section library of MCNP4C code was changed to ENDF/B-VI release 8 whichmore » is used in MCNP5 and MCNPX codes. Finally, the TG-43 parameters obtained using the MCNP4C-revised code, were compared with other codes. Results: The results of these investigations indicate that for high energy sources, the differences in TG-43 parameters between the codes are less than 1% for Ir-192 and less than 0.5% for Cs-137. However for low energy sources like I-125 and Pd-103, large discrepancies are observed in the g(r) values obtained by MCNP4C and the two other codes. The differences between g(r) values calculated using MCNP4C and MCNP5 at the distance of 6cm were found to be about 17% and 28% for I-125 and Pd-103 respectively. The results obtained with MCNP4C-revised and MCNPX were similar. However, the maximum difference between the results obtained with the MCNP5 and MCNP4C-revised codes was 2% at 6cm. Conclusion: The results indicate that using MCNP4C code for dosimetry of low energy brachytherapy sources can cause large errors in the results. Therefore it is recommended not to use this code for low energy sources, unless its cross section library is changed. Since the results obtained with MCNP4C-revised and MCNPX were similar, it is concluded that the difference between MCNP4C and MCNPX is their cross section libraries.« less

  20. Tally modifying of MCNP and post processing of pile-up simulation with time convolution method in PGNAA

    NASA Astrophysics Data System (ADS)

    Asghar Mowlavi, Ali; Koohi-Fayegh, Rahim

    2005-11-01

    Time convolution method has been employed for pile-up simulation in prompt gamma neutron activation analysis with an Am-Be neutron source and a 137Cs gamma source. A TALLYX subroutine has been written to design a new tally in the MCNP code. This tally records gamma particle information for the detector cell into an output file to be processed later. The times at which the particles are emitted by the source have been randomly generated following an exponential decay time distribution. A time convolution program was written to process the data produced and simulate more realistic pile-up. This method can be applied in optimization studies.

  1. π0 mass reconstruction in NOvA Far Detector.

    NASA Astrophysics Data System (ADS)

    Edayath, Sijith

    2017-01-01

    NOvA is a long-baseline neutrino oscillation experiment with functionally identical, segmented, tracking calorimeter Near and Far detectors. The detectors lie 14.6 mrad off-axis from the Fermilab NuMI beam, with a well-defined peak in neutrino energy at 2 GeV. The absolute calibration of the energy scale of the detectors is a major systematic uncertainty in long-baseline oscillation search in NOvA. Neutrino detectors make use of some standard candles for absolute energy calibration. Stopping muon energy distributions, Michel electron energy distributions, and invariant π0 mass are among them. In this talk, we cover NOvA's use of a new method to identify π0 with cosmic origins in the NOvA Far Detector. We employ a computer vision based particle identifier using convolutional neural networks (CVN) to identify π0s, complementing an existing strategy to identify π0 from the neutrino beam using more traditional methods in the Near Detector. Registered for PhD at Cochin University of Science and Technology, India and doing research in NOvA experiment at Fermilab.

  2. A Hubble Space Telescope Survey for Novae in M87. II. Snuffing out the Maximum Magnitude–Rate of Decline Relation for Novae as a Non-standard Candle, and a Prediction of the Existence of Ultrafast Novae

    SciTech Connect

    Shara, Michael M.; Doyle, Trisha; Zurek, David

    2017-04-20

    The extensive grid of numerical simulations of nova eruptions from the work of Yaron et al. first predicted that some classical novae might significantly deviate from the Maximum Magnitude–Rate of Decline (MMRD) relation, which purports to characterize novae as standard candles. Kasliwal et al. have announced the observational detection of a new class of faint, fast classical novae in the Andromeda galaxy. These objects deviate strongly from the MMRD relationship, as predicted by Yaron et al. Recently, Shara et al. reported the first detections of faint, fast novae in M87. These previously overlooked objects are as common in the giantmore » elliptical galaxy M87 as they are in the giant spiral M31; they comprise about 40% of all classical nova eruptions and greatly increase the observational scatter in the MMRD relation. We use the extensive grid of the nova simulations of Yaron et al. to identify the underlying causes of the existence of faint, fast novae. These are systems that have accreted, and can thus eject, only very low-mass envelopes, of the order of 10{sup −7}–10{sup −8} M {sub ⊙}, on massive white dwarfs. Such binaries include, but are not limited to, the recurrent novae. These same models predict the existence of ultrafast novae that display decline times, t {sub 2,} to be as short as five hours. We outline a strategy for their future detection.« less

  3. A Hubble Space Telescope survey for Novae in M87. II. Snuffing out the maximum magnitude–rate of decline relation for novae as a non-standard candle, and a prediction of the existence of ultrafast novae

    DOE PAGES

    Shara, Michael M.; Doyle, Trisha; Lauer, Tod R.; ...

    2017-04-20

    The extensive grid of numerical simulations of nova eruptions first predicted that some classical novae might significantly deviate from the Maximum Magnitude–Rate of Decline (MMRD) relation, which purports to characterize novae as standard candles. Kasliwal et al. have announced the observational detection of a new class of faint, fast classical novae in the Andromeda galaxy. These objects deviate strongly from the MMRD relationship, as predicted by Yaron et al. Recently, Shara et al. reported the first detections of faint, fast novae in M87. These previously overlooked objects are as common in the giant elliptical galaxy M87 as they are inmore » the giant spiral M31; they comprise about 40% of all classical nova eruptions and greatly increase the observational scatter in the MMRD relation. We use the extensive grid of the nova simulations of Yaron et al. to identify the underlying causes of the existence of faint, fast novae. These are systems that have accreted, and can thus eject, only very low-mass envelopes, of the order of 10 –7–10 –8 M ⊙, on massive white dwarfs. Such binaries include, but are not limited to, the recurrent novae. As a result, these same models predict the existence of ultrafast novae that display decline times, t 2, to be as short as five hours. We outline a strategy for their future detection.« less

  4. Nova V2362 Cygni (Nova Cygni 2006): Spitzer, Swift, and Ground-Based Spectral Evolution

    NASA Technical Reports Server (NTRS)

    Lynch, David K.; Venturini, Catherine C.; Mazuk, S.; Woodward, Charles; Gehrz, Robert; Rayner, John; Helton, L.A.; Ness, Jan-Uwe; Starrfield, Sumner; Rudy, Richard J.; hide

    2008-01-01

    Nova V2362 Cygni has undergone a number of very unusual changes. Ground-based spectroscopy initially revealed a normal sequence of events: the object faded and its near-infrared emission lines gradually shifted to higher excitation conditions until about day 100 when the optical fading reversed and the object slowly brightened. This was accompanied by a rise in the Swift X-ray telescope flux and a sudden shift in excitation of the visible and IR spectrum back to low levels. The new lower excitation spectrum revealed broad line widths and many P-Cygni profiles, all indicative of the ejection of a second shell. Eventually, dust formed, the X-ray brightness -- apparently unaffected by dust formation -- peaked and then declined, and the object faded at all wavelengths. The Spitzer dust spectra revealed a number of solid-state emission features that, at this time, are not identified.

  5. High Energy Neutrino Physics with NOvA

    SciTech Connect

    Coan, Thomas

    2016-09-09

    Knowledge of the position of energy deposition in “hit” detector cells of the NOvA neutrino detector is required by algorithms for pattern reconstruction and particle identification necessary to interpret the raw data. To increase the accuracy of this process, the majority of NOvA's 350 000 far detector cell shapes, including distortions, were measured as they were constructed. Using a special laser scanning system installed at the site of the NOvA far detector in Ash River, MN, we completed algorithmic development and measured shape parameters for the far detector. The algorithm and the measurements are “published” in NOνA’s document database (docmore » #10389, “Cell Center Finder for the NOνA Far Detector Modules”).« less

  6. Model Atmospheres for Novae in Outburst: Summary of Research

    NASA Technical Reports Server (NTRS)

    Hauschildt, Peter H.

    1999-01-01

    This paper presents a final report and summary of research on Model Atmospheres for Novae in Outburst. Some of the topics include: 1) Detailed NLTE (non-local thermodynamic equilibrium) Model Atmospheres for Novae during Outburst: II. Modeling optical and ultraviolet observations of Nova LMC 1988 #1; 2) A Non-LTE Line-Blanketed Stellar Atmosphere Model of the Early B Giant epsilon CMa; 3) Spectroscopy of Low Metallicity Stellar atmospheres; 4) Infrared Colors at the Stellar/Substellar Boundary; 5) On the abundance of Lithium in T CrB; 6) Numerical Solution of the Expanding Stellar Atmosphere Problem; and 7) The NextGen Model Atmosphere grid for 3000 less than or equal to T (sub eff) less than or equal to 10000K.

  7. Nova Monocerotis 2012 = PNV J06393874+0553520

    NASA Astrophysics Data System (ADS)

    Waagen, Elizabeth O.

    2012-08-01

    The discovery is reported of Nova Monocerotis 2012 = PNV J06393874+0553520 by Shigehisa Fujikawa (Kanonji City, Kagawa Prefecture, Japan, reported by Mitsuru Soma, National Astronomical Observatory of Japan) at magnitude C=9.4 on 2012 Aug. 09.8048 UT. Coordinates: 06 39 38.74 +05 53 52.0 (2000.0). Spectroscopy by multiple teams indicate a classical nova evolving toward the nebular phase. Announced on IAU CBAT Central Bureau Electronic Telegram 3202 (Daniel W. E. Green, ed.). Finder charts with sequence may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details, particularly regarding spectra and nearby stars, and observations of Nova Mon 2012 already reported to the AAVSO.

  8. Ultrastructure of extrusomes in hypotrichous ciliate Pseudourostyla nova

    NASA Astrophysics Data System (ADS)

    Zhou, Yao; Wang, Zhengjun; Zhang, Jun; Gu, Fukang

    2011-01-01

    The ultrastructure of extrusomes of the hypotrichous ciliate Pseudourostyla nova was observed in scanning and transmission electron microscopy and enzyme-cytochemistry. The results show that the distribution, morphological characteristics, morphogenesis process, and extrusive process of the extrusomes in P. nova are different from the trichocysts in Paramecium, suggesting that the extrusomes of P. nova can respond to environmental stimuli, play an important role in the defense of this species, and cannot be regarded as "trichocysts". The results also suggest that the extrusomes might be originated from the Golgi apparatus and mature in the cytoplasm; after the extrusion of mature extrusomes, the residual substance might be reabsorbed and reused by the ciliate cell via food vacuoles, and take part in material recycling of the cell.

  9. The spectroscopic evolution of the γ-ray emitting classical nova Nova Mon 2012. I. Implications for the ONe subclass of classical novae

    NASA Astrophysics Data System (ADS)

    Shore, S. N.; De Gennaro Aquino, I.; Schwarz, G. J.; Augusteijn, T.; Cheung, C. C.; Walter, F. M.; Starrfield, S.

    2013-05-01

    Aims: Among the classical novae, the ONe subgroup, distinguished by their large overabundance of neon, are thought to occur on the most massive white dwarfs. Nova Mon 2012 was the first classical nova to be detected as a high energy γ-ray transient, by Fermi-LAT, before its optical discovery. The first optical spectra obtained about 55 days after γ-ray peak, were strikingly similar to the ONe class after the transition to the nebular (optically thin) spectrum. The current paper presents our subsequent optical and ultraviolet observations. Methods: A time sequence of optical echelle spectra (3700-7400 Å) with the Nordic Optical Telescope (NOT) began on 2012 Aug. 16, immediately following the optical announcement, and are continuing. The nova was observed almost simultaneously with the NOT on 2012 Nov. 21, with the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope at medium echelle resolution (1150-3050 Å) on Nov. 20, and with the CHIRON CTIO/SMARTS echelle spectrograph at medium resolution (4500-8900 Å) on Nov. 22. We used plasma diagnostics (e.g. [O III] and Hβ line flux) to constrain electron densities and temperatures, and the filling factor, for the ejecta. Using Monte Carlo modeling, we derived the structure from comparisons to the optical and ultraviolet line profiles. We also compared observed fluxes for Nova Mon 2012 with those predicted by photoionization modeling with Cloudy using element abundances derived for other ONe novae, the parameters derived from the line profile modeling and multiwavelength continuum measurements. Results: Nova Mon 2012 is confirmed as an ONe nova first observed spectroscopically in the nebular stage. We derive an extinction of E(B - V) = 0.85 ± 0.05 and hydrogen column density NH ≈ 5 × 1021 cm-2. The corrected continuum luminosity is nearly the same in the entire observed energy range compared to V1974 Cyg, V382 Mon, and Nova LMC 2000 at the same epoch after outburst. The distance, about 3

  10. The geographic accessibility of pharmacies in Nova Scotia.

    PubMed

    Law, Michael R; Heard, Deborah; Fisher, Judith; Douillard, Jay; Muzika, Greg; Sketris, Ingrid S

    2013-01-01

    Geographic proximity is an important component of access to primary care and the pharmaceutical services of community pharmacies. Variations in access to primary care have been found between rural and urban areas in Canadian and international jurisdictions. We studied access to community pharmacies in the province of Nova Scotia. We used information on the locations of 297 community pharmacies operating in Nova Scotia in June 2011. Population estimates at the census block level and network analysis were used to study the number of Nova Scotia residents living within 800 m (walking) and 2 km and 5 km (driving) distances of a pharmacy. We then simulated the impact of pharmacy closures on geographic access in urban and rural areas. We found that 40.3% of Nova Scotia residents lived within walking distance of a pharmacy; 62.6% and 78.8% lived within 2 km and 5 km, respectively. Differences between urban and rural areas were pronounced: 99.2% of urban residents lived within 5 km of a pharmacy compared with 53.3% of rural residents. Simulated pharmacy closures had a greater impact on geographic access to community pharmacies in rural areas than urban areas. The majority of Nova Scotia residents lived within walking or short driving distance of at least 1 community pharmacy. While overall geographic access appears to be lower than in the province of Ontario, the difference appears to be largely driven by the higher proportion of rural dwellers in Nova Scotia. Further studies should examine how geographic proximity to pharmacies influences patients' access to traditional and specialized pharmacy services, as well as health outcomes and adherence to therapy. Can Pharm J 2013;146:39-46.

  11. The geographic accessibility of pharmacies in Nova Scotia

    PubMed Central

    Heard, Deborah; Fisher, Judith; Douillard, Jay; Muzika, Greg; Sketris, Ingrid S.

    2013-01-01

    Introduction: Geographic proximity is an important component of access to primary care and the pharmaceutical services of community pharmacies. Variations in access to primary care have been found between rural and urban areas in Canadian and international jurisdictions. We studied access to community pharmacies in the province of Nova Scotia. Methods: We used information on the locations of 297 community pharmacies operating in Nova Scotia in June 2011. Population estimates at the census block level and network analysis were used to study the number of Nova Scotia residents living within 800 m (walking) and 2 km and 5 km (driving) distances of a pharmacy. We then simulated the impact of pharmacy closures on geographic access in urban and rural areas. Results: We found that 40.3% of Nova Scotia residents lived within walking distance of a pharmacy; 62.6% and 78.8% lived within 2 km and 5 km, respectively. Differences between urban and rural areas were pronounced: 99.2% of urban residents lived within 5 km of a pharmacy compared with 53.3% of rural residents. Simulated pharmacy closures had a greater impact on geographic access to community pharmacies in rural areas than urban areas. Conclusion: The majority of Nova Scotia residents lived within walking or short driving distance of at least 1 community pharmacy. While overall geographic access appears to be lower than in the province of Ontario, the difference appears to be largely driven by the higher proportion of rural dwellers in Nova Scotia. Further studies should examine how geographic proximity to pharmacies influences patients’ access to traditional and specialized pharmacy services, as well as health outcomes and adherence to therapy. Can Pharm J 2013;146:39-46. PMID:23795168

  12. The Orbital Period of the Classical Nova V458 Vul

    NASA Astrophysics Data System (ADS)

    Goranskij, V. P.; Metlova, N. V.; Barsukova, E. A.; Burenkov, A. N.; Soloviev, V. Ya.

    2008-07-01

    Classical nova V458 Vul (N Vul 2007 No.1) was detected as a supersoft X-ray source (SSS) by the Swift XRT several times in the time range between 2007 October 18 and 2008 June 18 (J. Drake et al., ATel #1246 and #1603). Our V photometry shows the plateau in the light curve continued since January till June 2008. This feature accompanies usually the SSS phases in some classical novae. The fragmentary monitoring during plateau shows night- to-night variability with the amplitudes between 1.2 and 0.4 mag and rapid variability by 0.1 mag in the time scale of an hour.

  13. Bipolar gas outflow from the nova V458 Vul

    NASA Astrophysics Data System (ADS)

    Goranskij, V. P.; Barsukova, E. A.; Fatkhullin, T. A.

    2010-06-01

    Classical nova V458 Vul (N Vul 2007 No.1) was detected as a supersoft X-ray source by the Swift XRT (ATel#1246, #1603). This star is interesting with its spectral class change: features of Fe II class nova completely changed by features of He/N class in the SSS phase (T.N. Tarasova, IBVS No.5807). We performed spectral observations of V458 Vul with the Russian 6-m telescope BTA and spectral camera SCORPIO on 2010 June 9.84 UT.

  14. Nova in Ophiuchus - TCP J17394608-2457555

    NASA Astrophysics Data System (ADS)

    Waagen, Elizabeth O.

    2017-05-01

    AAVSO Alert Notice 576 announces the discovery of a galactic nova in Ophiuchus, TCP J17394608-2457555, by Koichi Itagaki (Yamagata, Japan) at unfiltered CCD magnitude 13.6 on 2017 May 08.7511 UT. Spectroscopy indicating that TCP J17394608-2457555 is an FeII nova (highly reddened) was obtained 2017 May 11.15 UT by S. C. Wiliams (Lancaster) and M. J. Darnley (LJMU) (ATel #10366). Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

  15. NOVA: A new multi-level logic simulator

    NASA Technical Reports Server (NTRS)

    Miles, L.; Prins, P.; Cameron, K.; Shovic, J.

    1990-01-01

    A new logic simulator that was developed at the NASA Space Engineering Research Center for VLSI Design was described. The simulator is multi-level, being able to simulate from the switch level through the functional model level. NOVA is currently in the Beta test phase and was used to simulate chips designed for the NASA Space Station and the Explorer missions. A new algorithm was devised to simulate bi-directional pass transistors and a preliminary version of the algorithm is presented. The usage of functional models in NOVA is also described and performance figures are presented.

  16. Nova in Scorpius - PNV J16521887-3754189

    NASA Astrophysics Data System (ADS)

    Waagen, Elizabeth O.

    2017-02-01

    Announces the discovery of Nova Sco 2017(PNV J16521887-3754189) [V1657 Sco] by Hideo Nishimura (Shizuoka-ken, Japan) at unfiltered CCD magnitude 11.7 on 2017 February 1.862 UT. Spectroscopy indicating that PNV J16521887-3754189 is an He/N nova was obtained 2017 February 12.3 UT by J. Strader (Michigan State Univ.) et al. (ATel #10071). Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

  17. Cross Check of NOvA Oscillation Probabilities

    SciTech Connect

    Parke, Stephen J.; Messier, Mark D.

    2018-01-12

    In this note we perform a cross check of the programs used by NOvA to calculate the 3-flavor oscillation probabilities with a independent program using a different method. The comparison is performed at 6 significant figures and the agreement,more » $$|\\Delta P|/P$$ is better than $$10^{-5}$$, as good as can be expected with 6 significant figures. In addition, a simple and accurate alternative method to calculate the oscillation probabilities is outlined and compared in the L/E range and matter density relevant for the NOvA experiment.« less

  18. Voxel2MCNP: a framework for modeling, simulation and evaluation of radiation transport scenarios for Monte Carlo codes.

    PubMed

    Pölz, Stefan; Laubersheimer, Sven; Eberhardt, Jakob S; Harrendorf, Marco A; Keck, Thomas; Benzler, Andreas; Breustedt, Bastian

    2013-08-21

    The basic idea of Voxel2MCNP is to provide a framework supporting users in modeling radiation transport scenarios using voxel phantoms and other geometric models, generating corresponding input for the Monte Carlo code MCNPX, and evaluating simulation output. Applications at Karlsruhe Institute of Technology are primarily whole and partial body counter calibration and calculation of dose conversion coefficients. A new generic data model describing data related to radiation transport, including phantom and detector geometries and their properties, sources, tallies and materials, has been developed. It is modular and generally independent of the targeted Monte Carlo code. The data model has been implemented as an XML-based file format to facilitate data exchange, and integrated with Voxel2MCNP to provide a common interface for modeling, visualization, and evaluation of data. Also, extensions to allow compatibility with several file formats, such as ENSDF for nuclear structure properties and radioactive decay data, SimpleGeo for solid geometry modeling, ImageJ for voxel lattices, and MCNPX's MCTAL for simulation results have been added. The framework is presented and discussed in this paper and example workflows for body counter calibration and calculation of dose conversion coefficients is given to illustrate its application.

  19. SMITHERS: An object-oriented modular mapping methodology for MCNP-based neutronic–thermal hydraulic multiphysics

    DOE PAGES

    Richard, Joshua; Galloway, Jack; Fensin, Michael; ...

    2015-04-04

    A novel object-oriented modular mapping methodology for externally coupled neutronics–thermal hydraulics multiphysics simulations was developed. The Simulator using MCNP with Integrated Thermal-Hydraulics for Exploratory Reactor Studies (SMITHERS) code performs on-the-fly mapping of material-wise power distribution tallies implemented by MCNP-based neutron transport/depletion solvers for use in estimating coolant temperature and density distributions with a separate thermal-hydraulic solver. The key development of SMITHERS is that it reconstructs the hierarchical geometry structure of the material-wise power generation tallies from the depletion solver automatically, with only a modicum of additional information required from the user. In addition, it performs the basis mapping from themore » combinatorial geometry of the depletion solver to the required geometry of the thermal-hydraulic solver in a generalizable manner, such that it can transparently accommodate varying levels of thermal-hydraulic solver geometric fidelity, from the nodal geometry of multi-channel analysis solvers to the pin-cell level of discretization for sub-channel analysis solvers.« less

  20. Simulation of irradiation exposure of electronic devices due to heavy ion therapy with Monte Carlo Code MCNP6

    NASA Astrophysics Data System (ADS)

    Lapins, Janis; Guilliard, Nicole; Bernnat, Wolfgang; Buck, Arnulf

    2017-09-01

    During heavy ion irradiation therapy the patient has to be located exactly at the right position to make sure that the Bragg peak occurs in the tumour. The patient has to be moved in the range of millimetres to scan the ill tissue. For that reason a special table was developed which allows exact positioning. The electronic control can be located outside the surgery. But that has some disadvantage for the construction. To keep the system compact it would be much more comfortable to put the electronic control inside the surgery. As a lot of high energetic secondary particles are produced during the therapy causing a high dose in the room it is important to find positions with low dose rates. Therefore, investigations are needed where the electronic devices should be located to obtain a minimum of radiation, help to prevent the failure of sensitive devices. The dose rate was calculated for carbon ions with different initial energy and protons over the entire therapy room with Monte Carlo particle tracking using MCNP6. The types of secondary particles were identified and the dose rate for a thin silicon layer and an electronic mixture material was determined. In addition, the shielding effect of several selected material layers was calculated using MCNP6.

  1. Thermal Scattering Law Data: Implementation and Testing Using the Monte Carlo Neutron Transport Codes COG, MCNP and TART

    SciTech Connect

    Cullen, D E; Hansen, L F; Lent, E M

    2003-05-17

    Recently we implemented the ENDF/B-VI thermal scattering law data in our neutron transport codes COG and TART. Our objective was to convert the existing ENDF/B data into double differential form in the Livermore ENDL format. This will allow us to use the ENDF/B data in any neutron transport code, be it a Monte Carlo, or deterministic code. This was approached as a multi-step project. The first step was to develop methods to directly use the thermal scattering law data in our Monte Carlo codes. The next step was to convert the data to double-differential form. The last step was tomore » verify that the results obtained using the data directly are essentially the same as the results obtained using the double differential data. Part of the planned verification was intended to insure that the data as finally implemented in the COG and TART codes, gave the same answer as the well known MCNP code, which includes thermal scattering law data. Limitations in the treatment of thermal scattering law data in MCNP have been uncovered that prevented us from performing this part of our verification.« less

  2. Background-Source Cosmic-Photon Elevation Scaling and Cosmic-Neutron/Photon Date Scaling in MCNP6

    SciTech Connect

    Tutt, James Robert; Anderson, Casey Alan; McKinney, Gregg Walter

    2017-10-26

    Here, cosmic neutron and photon fluxes are known to scale exponentially with elevation. Consequently, cosmic neutron elevation scaling was implemented for use with the background-source option shortly after its introduction into MCNP6, whereby the neutron flux weight factor was adjusted by the elevation scaling factor when the user-specified elevation differed from the selected background.dat grid-point elevation. At the same time, an elevation scaling factor was suggested for the cosmic photon flux, however, cosmic photon elevation scaling is complicated by the fact that the photon background consists of two components: cosmic and terrestrial. Previous versions of the background.dat file did notmore » provide any way to separate these components. With Rel. 4 of this file in 2015, two new columns were added that provide the energy grid and differential cosmic photon flux separately from the total photon flux. Here we show that the cosmic photon flux component can now be scaled independently and combined with the terrestrial component to form the total photon flux at a user-specified elevation in MCNP6.« less

  3. Spectroscopic confirmation and photometry of the first reported nova in NGC 147

    NASA Astrophysics Data System (ADS)

    Fabrika, S.; Vinokurov, A.; Solovyeva, Yu.; Valeev, A. F.; Makarov, D. I.; Hornoch, K.; Kucakova, H.; Korotkiy, S.; Henze, M.; Shafter, A. W.

    2017-12-01

    We report optical spectroscopic confirmation of the recent nova TCP J00333837+4836022 in the Local Group dwarf spheroidal galaxy NGC 147. The nova was discovered 2017 Dec. 22.4056 UT by K. Itagaki (Yamagata, Japan).

  4. Benchmarking ENDF/B-VII.1, JENDL-4.0 and JEFF-3.1.1 with MCNP6

    SciTech Connect

    Marck, Steven C. van der, E-mail: vandermarck@nrg.eu

    2012-12-15

    Recent releases of three major world nuclear reaction data libraries, ENDF/B-VII.1, JENDL-4.0, and JEFF-3.1.1, have been tested extensively using benchmark calculations. The calculations were performed with the latest release of the continuous energy Monte Carlo neutronics code MCNP, i.e. MCNP6. Three types of benchmarks were used, viz. criticality safety benchmarks, (fusion) shielding benchmarks, and reference systems for which the effective delayed neutron fraction is reported. For criticality safety, more than 2000 benchmarks from the International Handbook of Criticality Safety Benchmark Experiments were used. Benchmarks from all categories were used, ranging from low-enriched uranium, compound fuel, thermal spectrum ones (LEU-COMP-THERM), tomore » mixed uranium-plutonium, metallic fuel, fast spectrum ones (MIX-MET-FAST). For fusion shielding many benchmarks were based on IAEA specifications for the Oktavian experiments (for Al, Co, Cr, Cu, LiF, Mn, Mo, Si, Ti, W, Zr), Fusion Neutronics Source in Japan (for Be, C, N, O, Fe, Pb), and Pulsed Sphere experiments at Lawrence Livermore National Laboratory (for {sup 6}Li, {sup 7}Li, Be, C, N, O, Mg, Al, Ti, Fe, Pb, D2O, H2O, concrete, polyethylene and teflon). The new functionality in MCNP6 to calculate the effective delayed neutron fraction was tested by comparison with more than thirty measurements in widely varying systems. Among these were measurements in the Tank Critical Assembly (TCA in Japan) and IPEN/MB-01 (Brazil), both with a thermal spectrum, two cores in Masurca (France) and three cores in the Fast Critical Assembly (FCA, Japan), all with fast spectra. The performance of the three libraries, in combination with MCNP6, is shown to be good. The results for the LEU-COMP-THERM category are on average very close to the benchmark value. Also for most other categories the results are satisfactory. Deviations from the benchmark values do occur in certain benchmark series, or in isolated cases within benchmark

  5. A Hubble Space Telescope Survey for Novae in M87. I. Light and Color Curves, Spatial Distributions, and the Nova Rate

    NASA Astrophysics Data System (ADS)

    Shara, Michael M.; Doyle, Trisha F.; Lauer, Tod R.; Zurek, David; Neill, J. D.; Madrid, Juan P.; Mikołajewska, Joanna; Welch, D. L.; Baltz, Edward A.

    2016-11-01

    The Hubble Space Telescope has imaged the central part of M87 over a 10 week span, leading to the discovery of 32 classical novae (CNe) and nine fainter, likely very slow, and/or symbiotic novae. In this first paper of a series, we present the M87 nova finder charts, and the light and color curves of the novae. We demonstrate that the rise and decline times, and the colors of M87 novae are uncorrelated with each other and with position in the galaxy. The spatial distribution of the M87 novae follows the light of the galaxy, suggesting that novae accreted by M87 during cannibalistic episodes are well-mixed. Conservatively using only the 32 brightest CNe we derive a nova rate for M87: {363}-45+33 novae yr‑1. We also derive the luminosity-specific classical nova rate for this galaxy, which is {7.88}-2.6+2.3 {yr}}-1/{10}10 {L}ȯ {,}K. Both rates are 3–4 times higher than those reported for M87 in the past, and similarly higher than those reported for all other galaxies. We suggest that most previous ground-based surveys for novae in external galaxies, including M87, miss most faint, fast novae, and almost all slow novae near the centers of galaxies. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555.

  6. Pre-Discovery Light Curve of OGLE-2018-NOVA-01 from ASAS-SN

    NASA Astrophysics Data System (ADS)

    Chomiuk, L.; Strader, J.; Stanek, K. Z.; Kochanek, C. S.; Shields, J. V.; Thompson, T. A.; Shappee, B. J.; Holoien, T. W.-S.; Prieto, J. L.; Dong, Subo; Stritzinger, M.

    2018-03-01

    ASAS-SN monitoring of the LMC provides a high-quality light curve of the newly discovered recurrent nova OGLE-2018-NOVA-01 (ATel #11384, #11390). The nova is located in a crowded region of the LMC, and was undetected before 2018 Feb 25 (V > 16.3 mag).

  7. NovaChip pilot project : Route 5, Waterboro, Brownfield, & Fryeburg.

    DOT National Transportation Integrated Search

    2011-02-01

    In July & August, 2010, MaineDOT conducted experimental applications of NovaChip on 16 miles : of highway in western Maine. Novachip is a proprietary pavement process that applies an ultrathin, : gap-graded, hot mix wearing course over a polymer rich...

  8. High Speed Photometry and Spectroscopy of Novae at Quiescence

    NASA Astrophysics Data System (ADS)

    Egan, J. M.; Woudt, P. A.; Warner, B.; Williams, R. E.; Steeghs, D. T. H.; Ribeiro, V. A. R. M.

    2014-12-01

    We present spectroscopy of Nova Velorum 1999 (V382 Vel) and Nova Sagittarii 1936c (V630 Sgr) obtained with the Southern African Large Telescope in May and July 2012 as part of our ongoing observing campaign of old novae. The SALT spectrum of V382 Vel is dominated by broad Hα emission associated with the nova shell. The other Balmer lines in the spectrum are narrower and single-peaked, with Hβ at similar line strength as He II 4686Å. The SALT spectrum of V630 Sgr is dominated by He II 4686Å, emission lines are double-peaked (except the lines of the He II Pickering series) and show clear variations in multiple spectra obtained over one-quarter of the binary orbit. Additional high speed photometry of V382 Vel has been obtained in 2012 using the new SHOC photometer of the South African Astronomical Observatory. It shows the emergence of large amplitude quasi-periodic variability with periodicities around ˜ 30 minutes, not seen previously.

  9. Nova Lup 2016 during the X-ray decay phase

    NASA Astrophysics Data System (ADS)

    Orio, Marina; Beardmore, Andrew; Page, Kim; Osborne, Julian

    2017-09-01

    Nova Lup 2016 (ASASSN-16kt; see ATel #9538, #9539, #8550, #9554, #9587, #9594 and #9644) has been regularly monitored with Swift since the observations published in ATel #10632 that revealed a luminous supersoft X-ray source with a peak XRT count rate of 61.1(+-)0.1 cts/s on 2017/2/22.

  10. Hydrodynamic studies of oxygen, neon, and magnesium novae

    NASA Technical Reports Server (NTRS)

    Starrfield, Sumner; Sparks, W. M.; Truran, J. W.

    1987-01-01

    Results are presented from recent theoretical studies that have examined the properties of nova outbursts on ONeMg white dwarfs. These outbursts are much more violent and occur much more frequently than outbursts on CO white dwarfs. Hydrodynamic simulations of both kinds of outbursts are in excellent agreement with the observations.

  11. NOvA: Building a Next Generation Neutrino Experiment

    ScienceCinema

    Perko, John; Williams, Ron; Miller, Bill

    2018-01-16

    The NOvA neutrino experiment is searching for the answers to some of the most fundamental questions of the universe. This video documents how collaboration between government research institutions like Fermilab, academia and industry can create one of the largest neutrino detectors in the world.

  12. Non-LTE model atmosphere analysis of Nova Cygni 1992

    NASA Technical Reports Server (NTRS)

    Hauschildt, P. H.; Starrfield, S.; Austin, S.; Wagner, R. M.; Shore, S. N.; Sonneborn, G.

    1994-01-01

    We use spherically symmetric non-local thermodynamic equilibrium (non-LTE), line-blanketed, expanding model atmospheres to analyze the International Ultraviolet Explorer (IUE) and optical spectra of Nova Cygni 1992 during the early phases of its outburst. We find that the first IUE spectrum obtained just after discovery on 1992 February 20, is best reproduced by a model atmosphere with a steep density gradient and homologous expansion, whereas the IUE and optical spectra obtained on February 24 show an extended, optically thick, wind structure. Therefore, we distinguish two phases of the early evolution of the nova photosphere: the initial, rapid, 'fireball' phase and the subsequent, much longer, optically thick 'wind' phase. The importance of line-blanketing in nova spectra is demonstrated. Our preliminary abundance analysis implies that hydrogen is depeleted in the ejecta, corresponding to abundance enhancements of Fe by a factor of approximately 2 and of CNO by more than a factor of 10 when compared to solar abundances. The synthetic spectra reproduce both the observed pseudo-continua as well as most of the observed features from the UV to the optical spectral range and demonstrate the importance of obtaining nearly simultaneous UV and optical spectra for performing accurate analyses of expanding stellar atmospheres (for both novae and supernovae).

  13. NovaChip pilot project : Route 5, Waterboro, Hiram & Brownfield.

    DOT National Transportation Integrated Search

    2013-04-01

    In July & August, 2010, MaineDOT conducted experimental applications of NovaChip on 16 miles of highway : in western Maine. Novachip is a proprietary pavement process that applies an ultrathin, gap-graded, hot mix : wearing course over a polymer rich...

  14. The Nova Upgrade Facility for ICF ignition and gain

    NASA Astrophysics Data System (ADS)

    Lowdermilk, W. H.; Campbell, E. M.; Hunt, J. T.; Murray, J. R.; Storm, E.; Tobin, M. T.; Trenholme, J. B.

    1992-01-01

    Research on Inertial Confinement Fusion (ICF) is motivated by its potential defense and civilian applications, including ultimately the generation of electric power. The U.S. ICF Program was reviewed recently by the National Academy of Science (NAS) and the Fusion Policy Advisory Committee (FPAC). Both committees issued final reports in 1991 which recommended that first priority in the ICF program be placed on demonstrating fusion ignition and modest gain (G less than 10). The U.S. Department of Energy and Lawrence Livermore National Laboratory (LLNL) have proposed an upgrade of the existing Nova Laser Facility at LLNL to accomplish these goals. Both the NAS and FPAC have endorsed the upgrade of Nova as the optimal path to achieving ignition and gain. Results from Nova Upgrade Experiments will be used to define requirements for driver and target technology both for future high-yield military applications, such as the Laboratory Microfusion Facility (LMF) proposed by the Department of Energy, and for high-gain energy applications leading to an ICF engineering test facility. The central role and modifications which Nova Upgrade would play in the national ICF strategy are described.

  15. Slow magnetic monopoles search in NOvA

    NASA Astrophysics Data System (ADS)

    Antoshkin, Alexander; Frank, Martin

    2018-04-01

    The NOvA far detector is well suited for finding exotic particles due to its technical features (see [1]). One type of those exotic particles is a "slow" magnetic monopole. It is assumed that the energy deposition of such monopoles should be enough to be registered (see [2]). Measurement of the expected signals was performed on the NOvA test bench at JINR (see [3]). Result of this measurement allows us to perform slow monopole's research using NOvA software and hardware with high efficiency. As a whole, the research can lead to a discovery, or it can limit the existence of monopoles in a wide range of parameters, previously unreachable in other experiments (MACRO, SLIM, RICE, IceCube). Several special software tools have been developed. Slow Monopole Trigger has been created and implemented in the NOvA Data-Driven-Trigger system. Also, an online reconstruction algorithm has been developed and tested on 5% of the data. A technical description of these tools and current results of the analysis are presented in this work.

  16. Model atmospheres for Novae in the SSS phase

    NASA Astrophysics Data System (ADS)

    van Rossum, D.

    2014-07-01

    One of the fascinating things about novae is the diversity with which they appear in the sky. In X-rays, high-quality datasets obtained with XMM-Newton and Chandra present a wealth of detailed information about the physical conditions deep inside the nova. With all the diversity in the X-ray datasets, the grating spectra have one thing in common: they exhibit blue-shifted absorption lines. Apparently, these observations exhibit the basis of the nova where a mix of accreted, processed, and dredged-up material continues to leave the system. In this talk, I give an overview on different hydro-static and expanding model atmospheres that are used to interpret the X-ray data, and compare their synthetic spectra. I will show how the models are constrained by details in X-ray grating spectra and how they enable us to determine from the observations what the physical conditions are in deep layers of novae in outburst.

  17. Discovery of a Probable Nova in M31

    NASA Astrophysics Data System (ADS)

    Hornoch, K.; Kucakova, H.; Vrastil, J.

    2018-04-01

    We report the discovery of a probable nova in M31 on a co-added 720-s R-band CCD frame taken on 2018 Apr. 3.788 UT with the 0.65-m telescope at Ondrejov. The object designated PNV J00425509+4119009 is located at R.A. = 0h42m55s.09, Decl.

  18. Maria Helena Novaes--Creative Person, Creative Life

    ERIC Educational Resources Information Center

    de Alencar, Eunice M. L. Soriano

    2014-01-01

    This article describes the characteristics and accomplishments of Maria Helena Novaes, one of the most creative school psychologists of Brazil. It identifies the people who influenced her and some of the factors that may have contributed to her achievements and rise to eminence. It highlights the numerous opportunities she received during her life…

  19. Discovery of an Apparent Nova in M81

    NASA Astrophysics Data System (ADS)

    Hornoch, K.; Alfaro, M. Diaz; Ordonez-Etxeberria, I.; Vaduvescu, O.

    2015-01-01

    We report the discovery of an apparent nova in M81 on a co-added 1600-s narrow-band H-alpha CCD image taken with the 2.5-m Isaac Newton Telescope (INT) + WFC at La Palma under ~2.4" seeing on 2015 Jan. 15.126 UT.

  20. Optical and ultraviolet observations of nova Vul 1987

    NASA Technical Reports Server (NTRS)

    Starrfield, S.; Stryker, L. L.; Sonneborn, G.; Sparks, Warren M.; Wagner, R. M.; Ferland, Gary; Gallagher, J. S.; Wade, R.; Williams, R. E.; Gehrz, Robert D.

    1988-01-01

    The outburst for a nova discovered in Nov. 1987 and followed since then is summarized. Although it was possible to observe it with the IUE at maximum, its ultraviolet energy faded rapidly, and after the first 2 weeks it was impossible to observe it at IUE wavelengths. It is observed to form a thick dust shell and is in the nebular stage.

  1. A SHORT DESCRIPTION OF THE PLAN OF NOVA HIGH SCHOOL.

    ERIC Educational Resources Information Center

    HIERS, NAN

    THE NOVA HIGH SCHOOL IS AN EDUCATIONAL EXPERIMENT TO MAKE LEARNING AND ACHIEVEMENT INTERESTING, CHALLENGING, AND EXCITING TO THE STUDENT. THE PROGRAM IS BASED ON THE CONCEPT OF INDIVIDUAL PROGRESS WITH EMPHASIS ON QUALITY EDUCATION. FEATURES OF THE SCHOOL ENVIRONMENT INCLUDE AIR-CONDITIONING, CARPETING, MULTIPURPOSE CLASSROOMS, INDIVIDUAL STUDY…

  2. Spectroscopic confirmation of ASASSN-18ca as a nova

    NASA Astrophysics Data System (ADS)

    Raj, Ashish; Sahu, D. K.; Kiran, B. S.; Anupama, G. C.

    2018-02-01

    We report optical spectroscopic observations of nova ASASSN-18ca (ATel #11275) on Feb 9.58 UT. The spectrum was obtained using the HFOSC instrument mounted on the 2m Himalayan Chandra Telescope (HCT) of the Indian Astronomical Observatory, Hanle, India, in the 380-850nm wavelength range.

  3. Initiation of Convection in a Classical Nova Precursor

    NASA Astrophysics Data System (ADS)

    Dursi, L. J.; Calder, A. C.; Ricker, P. M.; Truran, J. W.; Zingale, M.; Fryxell, B.; Olson, K.; Rosner, R.; Timmes, F. X.; Tufo, H.; MacNeice, P.

    2001-12-01

    Classical Novae result from the explosive thermonuclear burning of material accreted from a companion star onto the surface of a white dwarf. Observed abundances and explosion energies estimated from observations indicate that there must be significant mixing of the heavier material of the white dwarf (C/O) into the lighter accreted material (H/He). Accordingly, nova models must incorporate a mechanism that will dredge up the heavier white dwarf material, and fluid motions from an early convection phase is one proposed mechanism. We present results from two-dimensional simulations of classical nova precursor models that demonstrate the beginning of a convective phase during the `simmering' of a Nova precursor. We use a new hydrostatic equilibrium hydrodynamics module recently developed for the adaptive-mesh code FLASH. The two-dimensional models are based on the one-dimensional models of Ami Glasner (Glasner et al. 1997), and were evolved with FLASH from a pre-convective state to the onset of convection. In addition, we present the details of the hydrostatic equilibrium module and the hydrostatic boundary conditions used in the simulations. This research has been supported by the U.S. Department of Energy under grant no. B341495 to the ASCI Flash Center at the University of Chicago.

  4. The political economy of wilderness designation in Nova Scotia

    Treesearch

    Glyn Bissix; Leah Levac; Peter Horvath

    2002-01-01

    This paper traces the various policy stimuli shaping the development of the Nova Scotia Wilderness Areas Protection Act (December, 1998). It does so by examining international, national, provincial, and local influences on wilderness designation, legislative structure, and implementation issues that influenced, or are likely to influence, wilderness area management. By...

  5. Grazing Eclipsing Dwarf Nova CW Monocerotis: Dwarf Nova-Type Outburst in a Possible Intermediate Polar?

    NASA Astrophysics Data System (ADS)

    Kato, Taichi; Uemura, Makoto; Kiyota, Seiichiro; Tanabe, Kenji; Koizumi, Mitsuo; Kida, Mayumi; Nishi, Yuichi; Tanaka, Sawa; Ueoka, Rie; Yasui, Hideki; Vanmunster, Tonny; Nogami, Daisaku; Yamaoka, Hitoshi

    2003-04-01

    We observed the 2002 October-November outburst of the dwarf nova CW Mon.The outburst showed a clear signature of a premaximum halt, and a more rapid decline after reaching the outburst maximum.On two separate occasions, during the premaximum stage and near the outburst maximum, shallow eclipses were recorded. This finding confirms the previously suggested possibility of the grazing eclipsing nature of this system.The separate occurrence of the eclipses and the premaximum halt can be understood as being the result of a combination of a two-step ignition of an outburst and the inside-out propagation of the heating wave.We detected a coherent short-period (0.02549d) signal on two subsequent nights around the optical maximum.This signal was likely present during the maximum phase of the 2000 January outburst.We interpret this signal as being a signature of the intermediate polar (IP) type pulses.The rather strange outburst properties, strong and hard X-ray emission, and the low luminosity of the outburst maximum might be understood as a consequence of the supposed IP nature.The ratio between the suggested spin period and the orbital period, however, is rather unusual for a system having an orbital period of ˜ 0.176 d.

  6. A Hubble Space Telescope survey for novae in M87 - III. Are novae good standard candles 15 d after maximum brightness?

    NASA Astrophysics Data System (ADS)

    Shara, Michael M.; Doyle, Trisha F.; Pagnotta, Ashley; Garland, James T.; Lauer, Tod R.; Zurek, David; Baltz, Edward A.; Goerl, Ariel; Kovetz, Attay; Machac, Tamara; Madrid, Juan P.; Mikołajewska, Joanna; Neill, J. D.; Prialnik, Dina; Welch, D. L.; Yaron, Ofer

    2018-02-01

    Ten weeks of daily imaging of the giant elliptical galaxy M87 with the Hubble Space Telescope (HST) has yielded 41 nova light curves of unprecedented quality for extragalactic cataclysmic variables. We have recently used these light curves to demonstrate that the observational scatter in the so-called maximum-magnitude rate of decline (MMRD) relation for classical novae is so large as to render the nova-MMRD useless as a standard candle. Here, we demonstrate that a modified Buscombe-de Vaucouleurs hypothesis, namely that novae with decline times t2 > 10 d converge to nearly the same absolute magnitude about two weeks after maximum light in a giant elliptical galaxy, is supported by our M87 nova data. For 13 novae with daily sampled light curves, well determined times of maximum light in both the F606W and F814W filters, and decline times t2 > 10 d we find that M87 novae display M606W,15 = -6.37 ± 0.46 and M814W,15 = -6.11 ± 0.43. If very fast novae with decline times t2 < 10 d are excluded, the distances to novae in elliptical galaxies with stellar binary populations similar to those of M87 should be determinable with 1σ accuracies of ± 20 per cent with the above calibrations.

  7. A Hubble Space Telescope survey for novae in M87 – III. Are novae good standard candles 15 d after maximum brightness?

    SciTech Connect

    Shara, Michael M.; Doyle, Trisha F.; Pagnotta, Ashley

    2017-11-16

    Ten weeks of daily imaging of the giant elliptical galaxy M87 with the Hubble Space Telescope (HST) has yielded 41 nova light curves of unprecedented quality for extragalactic cataclysmic variables. We have recently used these light curves to demonstrate that the observational scatter in the so-called maximum-magnitude rate of decline (MMRD) relation for classical novae is so large as to render the nova-MMRD useless as a standard candle. Here in this paper, we demonstrate that a modified Buscombe–de Vaucouleurs hypothesis, namely that novae with decline times t2 > 10 d converge to nearly the same absolute magnitude about two weeksmore » after maximum light in a giant elliptical galaxy, is supported by our M87 nova data. For 13 novae with daily sampled light curves, well determined times of maximum light in both the F606W and F814W filters, and decline times t 2 > 10 d we find that M87 novae display M606W,15 = -6.37 ± 0.46 and M814W,15 = -6.11 ± 0.43. If very fast novae with decline times t 2 < 10 d are excluded, the distances to novae in elliptical galaxies with stellar binary populations similar to those of M87 should be determinable with 1σ accuracies of ± 20 percent with the above calibrations.« less

  8. SU-E-T-521: Investigation of the Uncertainties Involved in Secondary Neutron/gamma Production in Geant4/MCNP6 Monte Carlo Codes for Proton Therapy Application

    SciTech Connect

    Mirzakhanian, L; Enger, S; Giusti, V

    2015-06-15

    Purpose: A major concern in proton therapy is the production of secondary neutrons causing secondary cancers, especially in young adults and children. Most utilized Monte Carlo codes in proton therapy are Geant4 and MCNP. However, the default versions of Geant4 and MCNP6 do not have suitable cross sections or physical models to properly handle secondary particle production in proton energy ranges used for therapy. In this study, default versions of Geant4 and MCNP6 were modified to better handle production of secondaries by adding the TENDL-2012 cross-section library. Methods: In-water proton depth-dose was measured at the “The Svedberg Laboratory” in Uppsalamore » (Sweden). The proton beam was mono-energetic with mean energy of 178.25±0.2 MeV. The measurement set-up was simulated by Geant4 version 10.00 (default and modified version) and MCNP6. Proton depth-dose, primary and secondary particle fluence and neutron equivalent dose were calculated. In case of Geant4, the secondary particle fluence was filtered by all the physics processes to identify the main process responsible for the difference between the default and modified version. Results: The proton depth-dose curves and primary proton fluence show a good agreement between both Geant4 versions and MCNP6. With respect to the modified version, default Geant4 underestimates the production of secondary neutrons while overestimates that of gammas. The “ProtonInElastic” process was identified as the main responsible process for the difference between the two versions. MCNP6 shows higher neutron production and lower gamma production than both Geant4 versions. Conclusion: Despite the good agreement on the proton depth dose curve and primary proton fluence, there is a significant discrepancy on secondary neutron production between MCNP6 and both versions of Geant4. Further studies are thus in order to find the possible cause of this discrepancy or more accurate cross-sections/models to handle the nuclear

  9. Benchmark of Atucha-2 PHWR RELAP5-3D control rod model by Monte Carlo MCNP5 core calculation

    SciTech Connect

    Pecchia, M.; D'Auria, F.; Mazzantini, O.

    2012-07-01

    Atucha-2 is a Siemens-designed PHWR reactor under construction in the Republic of Argentina. Its geometrical complexity and peculiarities require the adoption of advanced Monte Carlo codes for performing realistic neutronic simulations. Therefore core models of Atucha-2 PHWR were developed using MCNP5. In this work a methodology was set up to collect the flux in the hexagonal mesh by which the Atucha-2 core is represented. The scope of this activity is to evaluate the effect of obliquely inserted control rod on neutron flux in order to validate the RELAP5-3D{sup C}/NESTLE three dimensional neutron kinetic coupled thermal-hydraulic model, applied by GRNSPG/UNIPI formore » performing selected transients of Chapter 15 FSAR of Atucha-2. (authors)« less

  10. MCNP modelling of vaginal and uterine applicators used in intracavitary brachytherapy and comparison with radiochromic film measurements

    NASA Astrophysics Data System (ADS)

    Ceccolini, E.; Gerardy, I.; Ródenas, J.; van Dycke, M.; Gallardo, S.; Mostacci, D.

    Brachytherapy is an advanced cancer treatment that is minimally invasive, minimising radiation exposure to the surrounding healthy tissues. Microselectron© Nucletron devices with 192Ir source can be used for gynaecological brachytherapy, in patients with vaginal or uterine cancer. Measurements of isodose curves have been performed in a PMMA phantom and compared with Monte Carlo calculations and TPS (Plato software of Nucletron BPS 14.2) evaluation. The isodose measurements have been performed with radiochromic films (Gafchromic EBT©). The dose matrix has been obtained after digitalisation and use of a dose calibration curve obtained with a 6 MV photon beam provided by a medical linear accelerator. A comparison between the calculated and the measured matrix has been performed. The calculated dose matrix is obtained with a simulation using the MCNP5 Monte Carlo code (F4MESH tally).

  11. The H-alpha light curves of novae in M31

    NASA Technical Reports Server (NTRS)

    Ciardullo, Robin; Shafter, Allen W.; Ford, Holland C.; Neill, James D.; Shara, Michael M.

    1990-01-01

    H-alpha and B light curves are presented for 11 M31 novae, four of which were well observed near maximum. These data, along with the H-alpha light curves of two Galactic novae, demonstrate that a nova's maximum H-alpha flux occurs days or weeks after its continuum maximum at a monochromatic intensity 1-2 magnitudes above its peak flux in B. Moreover, after this maximum is achieved, a typical nova will radiate a third as many photons in H-alpha as in the entire B bandpass. The most interesting part of a nova's H-alpha light curve, however, is its decline. It is found that, regardless of a nova's speed, its H-alpha decay rate after maximum is almost identical to its decay rate in B. This behavior suggests that most of a nova's optical luminosity during early decline is continuum emission from the nebula, rather than direct radiation from the central source.

  12. 3D element imaging using NSECT for the detection of renal cancer: a simulation study in MCNP.

    PubMed

    Viana, R S; Agasthya, G A; Yoriyaz, H; Kapadia, A J

    2013-09-07

    This work describes a simulation study investigating the application of neutron stimulated emission computed tomography (NSECT) for noninvasive 3D imaging of renal cancer in vivo. Using MCNP5 simulations, we describe a method of diagnosing renal cancer in the body by mapping the 3D distribution of elements present in tumors using the NSECT technique. A human phantom containing the kidneys and other major organs was modeled in MCNP5. The element composition of each organ was based on values reported in literature. The two kidneys were modeled to contain elements reported in renal cell carcinoma (RCC) and healthy kidney tissue. Simulated NSECT scans were executed to determine the 3D element distribution of the phantom body. Elements specific to RCC and healthy kidney tissue were then analyzed to identify the locations of the diseased and healthy kidneys and generate tomographic images of the tumor. The extent of the RCC lesion inside the kidney was determined using 3D volume rendering. A similar procedure was used to generate images of each individual organ in the body. Six isotopes were studied in this work - (32)S, (12)C, (23)Na, (14)N, (31)P and (39)K. The results demonstrated that through a single NSECT scan performed in vivo, it is possible to identify the location of the kidneys and other organs within the body, determine the extent of the tumor within the organ, and to quantify the differences between cancer and healthy tissue-related isotopes with p ≤ 0.05. All of the images demonstrated appropriate concentration changes between the organs, with some discrepancy observed in (31)P, (39)K and (23)Na. The discrepancies were likely due to the low concentration of the elements in the tissue that were below the current detection sensitivity of the NSECT technique.

  13. 3D element imaging using NSECT for the detection of renal cancer: a simulation study in MCNP

    NASA Astrophysics Data System (ADS)

    Viana, R. S.; Agasthya, G. A.; Yoriyaz, H.; Kapadia, A. J.

    2013-09-01

    This work describes a simulation study investigating the application of neutron stimulated emission computed tomography (NSECT) for noninvasive 3D imaging of renal cancer in vivo. Using MCNP5 simulations, we describe a method of diagnosing renal cancer in the body by mapping the 3D distribution of elements present in tumors using the NSECT technique. A human phantom containing the kidneys and other major organs was modeled in MCNP5. The element composition of each organ was based on values reported in literature. The two kidneys were modeled to contain elements reported in renal cell carcinoma (RCC) and healthy kidney tissue. Simulated NSECT scans were executed to determine the 3D element distribution of the phantom body. Elements specific to RCC and healthy kidney tissue were then analyzed to identify the locations of the diseased and healthy kidneys and generate tomographic images of the tumor. The extent of the RCC lesion inside the kidney was determined using 3D volume rendering. A similar procedure was used to generate images of each individual organ in the body. Six isotopes were studied in this work—32S, 12C, 23Na, 14N, 31P and 39K. The results demonstrated that through a single NSECT scan performed in vivo, it is possible to identify the location of the kidneys and other organs within the body, determine the extent of the tumor within the organ, and to quantify the differences between cancer and healthy tissue-related isotopes with p ≤ 0.05. All of the images demonstrated appropriate concentration changes between the organs, with some discrepancy observed in 31P, 39K and 23Na. The discrepancies were likely due to the low concentration of the elements in the tissue that were below the current detection sensitivity of the NSECT technique.

  14. A Hubble Space Telescope Survey for Novae in M87. II. Snuffing out the Maximum Magnitude-Rate of Decline Relation for Novae as a Non-standard Candle, and a Prediction of the Existence of Ultrafast Novae

    NASA Astrophysics Data System (ADS)

    Shara, Michael M.; Doyle, Trisha; Lauer, Tod R.; Zurek, David; Baltz, Edward A.; Kovetz, Attay; Madrid, Juan P.; Mikołajewska, Joanna; Neill, J. D.; Prialnik, Dina; Welch, D. L.; Yaron, Ofer

    2017-04-01

    The extensive grid of numerical simulations of nova eruptions from the work of Yaron et al. first predicted that some classical novae might significantly deviate from the Maximum Magnitude-Rate of Decline (MMRD) relation, which purports to characterize novae as standard candles. Kasliwal et al. have announced the observational detection of a new class of faint, fast classical novae in the Andromeda galaxy. These objects deviate strongly from the MMRD relationship, as predicted by Yaron et al. Recently, Shara et al. reported the first detections of faint, fast novae in M87. These previously overlooked objects are as common in the giant elliptical galaxy M87 as they are in the giant spiral M31; they comprise about 40% of all classical nova eruptions and greatly increase the observational scatter in the MMRD relation. We use the extensive grid of the nova simulations of Yaron et al. to identify the underlying causes of the existence of faint, fast novae. These are systems that have accreted, and can thus eject, only very low-mass envelopes, of the order of 10-7-10-8 M ⊙, on massive white dwarfs. Such binaries include, but are not limited to, the recurrent novae. These same models predict the existence of ultrafast novae that display decline times, t 2, to be as short as five hours. We outline a strategy for their future detection. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under the NASA contract NAS 5-26555.

  15. Nova Centauri 2013 = PNV J13544700-5909080

    NASA Astrophysics Data System (ADS)

    Waagen, Elizabeth O.

    2013-12-01

    Announces the discovery of V1369 Cen = Nova Cen 2013 = PNV J13544700-5909080 by John Seach (Chatsworth Island, NSW, Australia) at unfiltered magnitude 5.5 on 2013 December 02.692 UT. Low-resolution spectra obtained by Locke on Dec. 03.3776 UT and by Kaufman on Dec. 03.621 UT show strong Ha and Hb emission lines, indicating the object is a nova. Announced on IAU CBAT Central Bureau Electronic Telegram 3732 (Daniel W. E. Green, ed.). Finder charts with sequences may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details and observations.

  16. Milli-Arcsecond Infrared Observations of the Nova RS Ophiuchi

    NASA Technical Reports Server (NTRS)

    Barry, Richard K.; Danchi, W. C.; Koresko, C.; Kuchner, M.; Traub, W. A.; Monnier, J. D.; Serabyn, E.; Mennesson, B.; Greenhouse, M. A.; Colavita, M. M.; hide

    2007-01-01

    We report on infrared interferometric measurements of the 2006 outburst of Nova RS Oph in H, K, and N bands. These measurements, conducted using the Infrared and Optical Telescope Array, the Palomar Testbed Interferometer, and the Keck Interferometer, show a small variation in the 3 mas size if this resolved source during the first 65 days of the outburst. Additionally, using interferometric closure phases, these observations show an unambiguous departure from point symmetry of the object. We also describe simultaneous N-band observations of the nova in two separate milli-arcsecond spatial regimes on day four in which we detect line emission indicating onset of the optically thin phase. These data represent the first science from the Keck Interferometer's nulling mode.

  17. Discovery of three nova candidates in M81

    NASA Astrophysics Data System (ADS)

    Williams, S. C.; Hornoch, K.; Kucakova, H.; Henze, M.; Sala, G.; Jose, J.; Figueira, J.; Sin, P.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

    2017-12-01

    The M81 nova monitoring collaboration reports the discovery of three M81 nova candidates in H & alpha; imaging from the 2-m Liverpool Telescope (LT) taken, 2017 Dec 27.091 UT. They are M81N 2017-12c at RA = 9h54m54.87s, Dec. = +69 & deg;06'33.6", M81N 2017-12d at RA = 9h55m35.89s, Dec. = +69 & deg;03'37.6" and M81N 2017-12e at RA = 9h55m18.20s, Dec. = +69 & deg;04'31.1" (All J2000 and 1 & sigma; error 0.2").

  18. Deep optical imaging of nova remnants: a southern sky sample

    NASA Astrophysics Data System (ADS)

    Gill, C. D.; O'Brien, T. J.

    1998-10-01

    We present an optical imaging study of 20 southern sky nova remnants which has resulted in the discovery of four previously unknown nova shells - those of V842 Cen, RR Cha, DY Pup and HS Pup. The study has also revealed previously unobserved features in three other known shells - those of BT Mon, CP Pup and RR Pic. The images of BT Mon, V842 Cen, RR Cha, DY Pup and HS Pup have been processed using several deconvolution algorithms (Richardson-Lucy, maximum entropy and CLEAN) in addition to straightforward point-source subtraction in an attempt to resolve the shells from the central stars. The use of four different methods enables us to make a qualitative judgment of the results. Notably, the shell of RR Pic displays tails extending outwards from clumps in the main ejecta similar to those previously detected in DQ Her.

  19. A multiwavelength study of Nova QU Vulpeculae 1984

    NASA Technical Reports Server (NTRS)

    Saizar, Pedro; Starrfield, Sumner; Ferland, Gary J.; Wagner, R. M.; Truran, James W.; Kenyon, Scott J.; Sparks, Warren M.; Williams, Robert E.; Stryker, L. L.

    1992-01-01

    We have combined ground-based optical and satellite ultraviolet spectrophotometric data to study the ejected shell of Nova Vulpecula 1984 No. 2 (QU Vul). Substantial uncertainties concerning the nature of the ionizing continuum, and the role played by density inhomogeneities, now exist. Because of these uncertainties, the chemical composition is deduced from emission-line pairs chosen to minimize the effects of variations in temperature, density, and ionization. We find that the chemical composition of the ejected shell show enhancements of several elements relative to hydrogen, namely, He, N, O, Ne, Mg, Al, and Si, as is expected for an outburst occurring on an ONeMg white dwarf. It is also shown that QU Vul ejected a large amount of aluminum into the interstellar medium, and it is estimated that only a small fraction of slow novae of this type can account for the observed abundance of aluminum in the Galaxy.

  20. PW Vul: A classical nova with nearly solar abundances

    NASA Technical Reports Server (NTRS)

    Saizar, P.; Starrfield, Sumner G.; Austin, S.; Ferland, G. J.; Wagner, R. M.; Truran, J. W.; Sonneborn, George; Kenyon, S. J.; Sparks, W. M.; Williams, R. E.

    1990-01-01

    Ultraviolet and optical spectrophotometric data are combined in order to determine the physical parameters in the expanding shell of Nova PW Vul 1984. Ultraviolet data obtained with the International Ultraviolet Explorer (IUE) satellite from August 2, 1984 (a few days after discovery) until it became too faint to study with the satellite is presented. The last IUE exposure was obtained in June 1988 but it was continually followed with ground based optical telescopes. A plot showing the variation of electron density and temperature as a function of time is presented. Analysis of the emission line intensities show that the abundances of this very slow nova are solar for helium, carbon, and oxygen while nitrogen is 50 times solar. The CLOUDY code of Ferland is used to model the emission line intensities and find good agreement with the observations. Plots representative of IUE and optical spectra are displayed.

  1. Waiting Points in Nova and X-ray burst Nucleosynthesis

    SciTech Connect

    Sunayama, Tomomi; Oak Ridge Institute for Science Education, Oak Ridge, Tennessee 37831-0117; Smith, Michael S.

    2008-05-21

    In nova and X-ray burst nucleosynthesis, waiting points are nuclei in the reaction path which delay the nuclear flow towards heavier nuclei, typically because of a weak proton capture reaction and a long {beta}{sup +} lifetime. Waiting points can influence the energy generation and final abundances synthesized in these explosions. We have constructed a systematic, quantitative set of criteria to identify rp-process waiting points, and use them to search for waiting points in post-processing simulations of novae and X-ray bursts. These criteria have been incorporated into the Computational Infrastructure for Nuclear Astrophysics, online at nucastrodata.org, to enable anyone to runmore » customized searches for waiting points.« less

  2. Waiting Points in Nova and X-ray Burst Nucleosynthesis

    SciTech Connect

    Sunayama, Tomomi; Smith, Michael Scott; Lingerfelt, Eric J

    2008-01-01

    In nova and X-ray burst nucleosynthesis, waiting points are nuclei in the reaction path which interrupt the nuclear flow towards heavier nuclei, typically because of a weak proton capture reaction and a long beta+ lifetime. Waiting points can influence the energy generation and final abundances synthesized in these explosions. We have constructed a systematic, quantitative set of criteria to identify rp-process waiting points, and use them to search for waiting points in post-processing simulations of novae and X-ray bursts. These criteria have been incorporated into the Computational Infrastructure for Nuclear Astrophysics, online at nucastrodata.org, to enable anyone to run customizedmore » searches for waiting points.« less

  3. V3661 Ophiuchi = Nova Oph 2016 = PNV 17355050-2934240

    NASA Astrophysics Data System (ADS)

    Waagen, Elizabeth O.

    2016-03-01

    AAVSO Alert Notice 541 announces the independent discovery of V3661 Oph = Nova Oph 2016 = PNV 17355050-2934240 by Minoru Yamamoto (Okazaki, Aichi-ken, Japan) at unfiltered magnitude 10.6 on 2016 March 11.80-11.82 UT, and by Yuji Nakamura (Kameyama, Mie, Japan) at unfiltered CCD magnitude 10.6 on 2016 Mar. 11.832 UT. Spectroscopy obtained by U. Sollecchia (central Italy) on Mar. 14.15 UT through clouds indicates the object as a nova (reported by U. Munari (Padova Observatory)). Munari notes that N Oph 2016 is highly reddened, reinforced by photometry he obtained with F.-J. Hambsch and A. Frigo on March 12-14.Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

  4. Gamma-ray emission from internal shocks in novae

    NASA Astrophysics Data System (ADS)

    Martin, P.; Dubus, G.; Jean, P.; Tatischeff, V.; Dosne, C.

    2018-04-01

    Context. Gamma-ray emission at energies ≥100 MeV has been detected from nine novae using the Fermi Large Area Telescope (LAT), and can be explained by particle acceleration at shocks in these systems. Eight out of these nine objects are classical novae in which interaction of the ejecta with a tenuous circumbinary material is not expected to generate detectable gamma-ray emission. Aim. We examine whether particle acceleration at internal shocks can account for the gamma-ray emission from these novae. The shocks result from the interaction of a fast wind radiatively-driven by nuclear burning on the white dwarf with material ejected in the initial runaway stage of the nova outburst. Methods: We present a one-dimensional model for the dynamics of a forward and reverse shock system in a nova ejecta, and for the associated time-dependent particle acceleration and high-energy gamma-ray emission. Non-thermal proton and electron spectra are calculated by solving a time-dependent transport equation for particle injection, acceleration, losses, and escape from the shock region. The predicted emission is compared to LAT observations of V407 Cyg, V1324 Sco, V959 Mon, V339 Del, V1369 Cen, and V5668 Sgr. Results: The ≥100 MeV gamma-ray emission arises predominantly from particles accelerated up to 100 GeV at the reverse shock and undergoing hadronic interactions in the dense cooling layer downstream of the shock. The emission rises within days after the onset of the wind, quickly reaches a maximum, and its subsequent decrease reflects mostly the time evolution of the wind properties. Comparison to gamma-ray data points to a typical scenario where an ejecta of mass 10-5-10-4 M⊙ expands in a homologous way with a maximum velocity of 1000-2000 km s-1, followed within a day by a wind with a velocity <2000 km s-1 and a mass-loss rate of 10-4-10-3 M⊙ yr-1 declining over a time scale of a few days. Because of the large uncertainties in the measurements, many parameters of the

  5. From RoboNova to HUBO: Platforms for Robot Dance

    NASA Astrophysics Data System (ADS)

    Grunberg, David; Ellenberg, Robert; Kim, Youngmoo E.; Oh, Paul Y.

    A robot with the ability to dance in response to music could lead to novel and interesting interactions with humans. For example, such a robot could be used to augment live performances alongside human dancers. This paper describes a system enabling humanoid robots to move in synchrony with music. A small robot, the Hitec RoboNova, was initially used to develop smooth sequences of complex gestures used in human dance. The system uses a real-time beat prediction algorithm so that the robot’s movements are synchronized with the audio. Finally, we implemented the overall system on a much larger robot, HUBO, to establish the validity of the smaller RoboNova as a useful prototyping platform.

  6. VERITAS Observations of the Nova in V407 Cygni

    NASA Technical Reports Server (NTRS)

    Aliu, E.; Archambault, S.; Arlen, T.; Aune, T.; Beilicke, M.; Benbow, W.; Bouvier, A.; Bradbury, S. M.; Buckley, J. H.; Bugaev, V.; hide

    2012-01-01

    We report on very high energy (E > 100 GeV) gamma-ray observations of V407 Cygni, a symbiotic binary that underwent a nova outburst producing 0.1- 10 GeV gamma rays during 2010 March 10-26. Observations were made with the Very Energetic Radiation Imaging Telescope Array System during 2010 March 19-26 at relatively large zenith angles, due to the position of V407 Cyg. An improved reconstruction technique for large zenith angle observations is presented and used to analyze the data. We do not detect V407 Cygni and place a differential upper limit on the flux at 1.6 TeV of 2.3 10(exp -12) erg/sq cm/s (at the 95% confidence level). When considered jointly with data from Fermi-LAT, this result places limits on the acceleration of very high energy particles in the nova.

  7. Pre-nova Mixing at the Surface of White Dwarfs

    NASA Astrophysics Data System (ADS)

    Rosner, R.; Young, Y. N.; Alexakis, A.; Dursi, L. J.; Truran, J.; Calder, A. C.; Fryxell, B.; Olson, K.; Ricker, P. M.; Timmes, F. X.; Zingale, M.; Tufo, H. M.; MacNeice, P.

    2000-12-01

    We report on studies of shear-driven mixing at the interface between a hydrogen-helium envelope and the carbon-oxygen surface of a pre-nova outburst white dwarf. Linear theory shows distinct regimes of unstable gravity surface waves and Kelvin-Helmholtz modes, which we follow into the weakly nonlinear regime by analytical techniques; we then follow the fully nonlinear evolution to the point of wave breaking, using the Chicago Flash Code. We also report on estimates of the mixing efficiency resulting from the combination of weakly driven convection and wave breaking; and discuss their implications for nova outbursts. This work was supported by the DOE ASCI/Alliances program at the University of Chicago, under grant No. B341495.

  8. 110-day Spectral Record of the Classical Nova Delphini 2013

    NASA Astrophysics Data System (ADS)

    Wiethoff, William; Mooers, H. D.; Habig, A. T.

    2014-01-01

    The August 14, 2013 eruption of Nova Delphini 2013 presented a unique opportunity for amateur astronomers to study the evolution of a classical nova. We present a 110-day spectral record of the evolution of this nova acquired with a low-resolution 100 line per millimeter grating and a commercially available CCD camera mounted on an 14” Schmidt Cassegrain telescope. Records were acquired beginning one day after discovery. At the time of writing this abstract 44 spectra over 110 days have been acquired and analyzed. Raw data were calibrated against star 29vul a type A0V with clear H-Balmer lines. Spectra were then corrected for instrument response and analyzed with commercially available software from Field Tested Systems (R-Spec ®). Earliest spectra highlight characterizes of the fireball phase with a bright continuum and clear H-Balmer emission lines. The transition to the Iron Curtain phase is uncertain in our spectra because of lack of sensitivity in the UV. By +6 days the expanding gas shell has cooled to the point where various emission lines appear prominently; particularly H-α, Hβ , and Fe II. Elemental oxygen (O I) at 7773 and 8446 Å also emerges from the continuum and by +10 day dominate the near-IR. Further progression shows the C III and N III complex at 4640 Å and He I at 7065 Å. Further evolution of the phases of Nova Delphini 2013 is clearly defined in the emission spectra. Lyman-β pumping of O I at 8446 Å is clearly evident by +17 days and drops precipitously between days 48 and 49. The nebular phase becomes apparent when O III at 5007 Å becomes obvious.

  9. Disk irradiation and light curves of x ray novae

    NASA Technical Reports Server (NTRS)

    Kim, S.-W.; Wheeler, J. C.; Mineshige, S.

    1994-01-01

    We study the disk instability and the effect of irradiation on outbursts in the black hole X-ray nova system. In both the optical and soft X-rays, the light curves of several X-ray novae, A0620-00, GH 2000+25, Nova Muscae 1991 (GS 1124-68), and GRO J0422+32, show a main peak, a phase of exponential decline, a secondary maximum or reflare, and a final bump in the late decay followed by a rapid decline. Basic disk thermal limit cycle instabilities can account for the rapid rise and overall decline, but not the reflare and final bump. The rise time of the reflare, about 10 days, is too short to represent a viscous time, so this event is unlikely to be due to increased mass flow from the companion star. We explore the possibility that irradiation by X-rays produced in the inner disk can produce these secondary effects by enhancing the mass flow rate within the disk. Two plausible mechanisms of irradiation of the disk are considered: direct irradiation from the inner hot disk and reflected radiation from a corona or other structure above the disk. Both of these processes will be time dependent in the context of the disk instability model and result in more complex time-dependent behavior of the disk structure. We test both disk instability and mass transfer burst models for the secondary flares in the presence of irradiation.

  10. An evaluation of Nova Scotia's alcohol ignition interlock program.

    PubMed

    Vanlaar, Ward G M; Mainegra Hing, Marisela; Robertson, Robyn D

    2017-03-01

    Alcohol ignition interlock programs for offenders aim to reduce recidivism among convicted drink drivers. This study presents an evaluation of Nova Scotia's interlock program implemented in 2008 in order to assess its effectiveness to reduce impaired driving and to help identify areas for improvement. Data used include conviction and crash records of individual participants; provincial monthly counts of alcohol-related charges, convictions and fatal and serious crashes; and interlock logged events. Methods used include descriptive statistics, survival analysis, time series and logistic regression analysis. With respect to specific deterrence (i.e., preventing recidivism) there was a 90% reduction in recidivism among voluntary participants since participation in the interlock program and a 79% reduction after these participants exited from the program. With respect to general deterrence (i.e., referring to a preventative effect on the entire population of drivers in Nova Scotia) there were temporary decreases in the numbers of alcohol-related charges (13.32%) and convictions (9.93%) and a small significant decrease in the number of fatal and serious injury alcohol-related crashes, following the implementation of the program. The evidence suggests the interlock program was better at preventing harm due to alcohol-impaired driving than the alternative of not using the interlock program. Recommendations were formulated supporting the continuation of the interlock program in Nova Scotia. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. The early spectral evolution of Nova Cassiopeiae 1993

    NASA Technical Reports Server (NTRS)

    Hauschildt, Peter H.; Starrfield, Sumner; Shore, Steven N.; Gonzalez-Riestra, Rosario; Sonneborn, George; Allard, France

    1994-01-01

    In this paper we describe the evolution of Nova Cas 1993 over the first two months of its outburst. We present an ultraviolet light curve that covers the period from announcement to just after dust began forming in the ejecta (1994 Feb. 15) and International Ultraviolet Explorer (IUE) spacecraft constraints forced us to halt our observations. We have used spherical, expanding, Non-local Thermodynamic Equilibrium (NLTE) stellar atmospheres to compute synthetic spectra and have compared the results to combined ultraviolet (low-resolution 1200-3400 A and high-resolution 2400-3300 A) spectra. Our fits show that the effective temperature of the ejecta increased from approx. 8000 to about approx. 16 000 K between 1993 Dec. 12 and 1993 Dec. 26. The temperature then increased more slowly to approx. 24 000 on 1994 Jan. 28. A preliminary abundance analysis shows evidence for hydrogen depletion, as we also found for Nova V1974 Cygni; however we find a larger enhancement of carbon, nitrogen, and oxygen. We also show that the principal mechanism for mass ejection in this nova is a radiation pressure driven wind and that mechanical driving is not necessary.

  12. Nova, Carbide file for cracker and PE permits

    SciTech Connect

    Morris, G.D.L.

    1996-11-20

    Nova chemicals has filed for regulatory permits for a 2-billion lbs/year joint venture cracker with Union Carbide to be built at Nova`s complex at Joffre, AB. Officials at Joffre expect to have permits for the project by April 1997 and anticipate breaking ground next September or October. Startup is slated for 2000. The C$825-million ($600 million) plant will increase on-site ethylene capacity to 5 billion lbs/year. Downstream, Carbide has filed for permits for a 1.2-billion lbs/year Unipol-process linear low-density polyethylene plant to be built at its Prentiss site, a few miles northeast of Joffre. Prentiss plant manager Cory Kaminsky saysmore » he hopes to have permits for that project by mid-1997. {open_quotes}We need to be ready with the polymer plant when the cracker comes onstream,{close_quotes} he says. {open_quotes}We don`t want to have to hold back that plant or have to flare ethylene.{close_quotes} 1 fig.« less

  13. Nova Sgr 2015 No. 2 fading as dust production rises

    NASA Astrophysics Data System (ADS)

    Waagen, Elizabeth O.

    2015-06-01

    V5668 Sgr (Nova Sgr 2015 No. 2 = PNV J18365700-2855420; see AAVSO Alert Notice 512) is undergoing a significant fading visually as its infrared excess increases, indicating that substantial dust production is underway. Nova Sgr 2015 No. 2 was discovered by John Seach (Chatsworth Island, NSW, Australia) at DSLR magnitude 6.0 on 2015 March 15.634 UT. It brightened to V=4.3 by March 21, and has undergone five subsequent re-brightenings, the last to V=5.7 on June 1. Since then it has faded steadily to V=8.2 on June 15, 1.6 magnitudes fainter than its faintest previous minimum since outburst. The Spitzer Space Telescope may observe this classical nova if it can be diverted from its current mode and target. Several professional astronomers are planning observations with other instrumentation. Photometry and visual observations, spectroscopy, and polarimetry are strongly encouraged. Near-infrared observations (J and H bands) would be particularly helpful. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

  14. Nova Sgr 2015 No. 4 = PNV J18225925-1914148

    NASA Astrophysics Data System (ADS)

    Waagen, Elizabeth O.

    2015-11-01

    AAVSO Alert Notice 534 announces the independent discovery of Nova Sgr 2015 No. 4 = PNV J18225925-1914148 = V5850 Sgr by Shigehisa Fujikawa (Kan'onji, Kagawa, Japan) at unfiltered magnitude 11.8 on 2015 October 31.386 UT; by Hideo Nishimura (Kakegawa, Shizuoka-ken, Japan) at unfiltered magnitude 11.5 on 2015 October 31.376 UT; and by Minoru Yamamoto (Okazaki, Aichi-ken, Japan) at unfiltered magnitude 11.0 on 2015 October 31.392 UT. Spectra obtained by M. Fujii on 2015 November 2.417 UT and November 3.389 UT, and by U. Munari and U. Sollecchia on Nov. 2.758 UT indicate the object to be a nova. Munari also obtained a low-resolution spectrogram on Nov 3.718 that indicates the object has the typical spectrum of a He/N nova (CBET 4159). Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

  15. Nova Sagittarii 2014 = PNV J18250860-2236024 AND Erratum

    NASA Astrophysics Data System (ADS)

    Waagen, Elizabeth O.

    2014-02-01

    Details of discovery of Nova Sagittarii 2014 (PNV J18250860-2236024) and procedures for observing and reporting observations are announced. Discovered by Sigeru Furuyama (Tone-machi, Ibaraki-ken, Japan) andreported by S. Nakano (Sumoto, Japan) at unfiltered CCD magnitude 8.7 on 2014 Jan. 26.857 UT. Coordinates: R.A. 18 25 08.60 Decl. = -22 36 02.4 (2000.0). Nova Sgr 2014 is Fe II-type classical nova past maximum, per low-resolution spectra obtained by A. Arai on 2014 Jan. 30.87 UT. Announced in IAU CBAT CBET 3802 (D. W. E. Green, ed.). Finder charts with sequence may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details and observations. Also, an Erratum is reported. In AAVSO Alert Notice 496, Mati Morel (MMAT, Thornton, NSW, Australia) was credited with the discovery of the 1989 outburst of V745 Sco. The discoverer was William Liller (LIW, Vina del Mar, Chile), who observed V745 Sco on 1989 July 30.08 UT at magnitude 9.7 (PROBLICOM discovery using 2415 film with orange filter).

  16. Search for gamma-ray emission from Galactic novae with the Fermi -LAT

    NASA Astrophysics Data System (ADS)

    Franckowiak, A.; Jean, P.; Wood, M.; Cheung, C. C.; Buson, S.

    2018-02-01

    Context. A number of novae have been found to emit high-energy gamma rays (>100 MeV). However, the origin of this emission is not yet understood. We report on the search for gamma-ray emission from 75 optically detected Galactic novae in the first 7.4 years of operation of the Fermi Large Area Telescope using the Pass 8 data set. Aims: We compile an optical nova catalog including light curves from various resources and estimate the optical peak time and optical peak magnitude in order to search for gamma-ray emission to determine whether all novae are gamma-ray emitters. Methods: We repeated the analysis of the six novae previously identified as gamma-ray sources and developed a unified analysis strategy that we then applied to all novae in our catalog. We searched for emission in a 15 day time window in two-day steps ranging from 20 days before to 20 days after the optical peak time. We performed a population study with Monte Carlo simulations to set constraints on the properties of the gamma-ray emission of novae. Results: Two new novae candidates have been found at 2σ global significance. Although these two novae candidates were not detected at a significant level individually, taking them together with the other non-detected novae, we found a sub-threshold nova population with a cumulative 3σ significance. We report the measured gamma-ray flux for detected sources and flux upper limits for novae without significant detection. Our results can be reproduced by several gamma-ray emissivity models (e.g., a power-law distribution with a slope of 2), while a constant emissivity model (i.e., assuming novae are standard candles) can be rejected.

  17. Near-infrared and optical studies of the highly obscured nova V1831 Aquilae (Nova Aquilae 2015)

    NASA Astrophysics Data System (ADS)

    Banerjee, D. P. K.; Srivastava, Mudit K.; Ashok, N. M.; Munari, U.; Hambsch, F.-J.; Righetti, G. L.; Maitan, A.

    2018-01-01

    Near-infrared (NIR) and optical photometry and spectroscopy are presented for the nova V1831 Aquilae, covering the early decline and dust-forming phases during the first ∼90 d after its discovery. The nova is highly reddened due to interstellar extinction. Based solely on the nature of the NIR spectrum, we are able to classify the nova to be of the Fe II class. The distance and extinction to the nova are estimated to be 6.1 ± 0.5 kpc and Av ∼ 9.02, respectively. Lower limits of the electron density, emission measure and ionized ejecta mass are made from a Case B analysis of the NIR Brackett lines, while the neutral gas mass is estimated from the optical [O I] lines. We discuss the cause of the rapid strengthening of the He I 1.0830-μm line during the early stages. V1831 Aql formed a modest amount of dust fairly early (∼19.2 d after discovery); the dust shell is not seen to be optically thick. Estimates of the dust temperature, dust mass and grain size are made. Dust formation commences around day 19.2 at a condensation temperature of 1461 ± 15 K, suggestive of a carbon composition, following which the temperature is seen to decrease gradually to 950 K. The dust mass shows a rapid initial increase, which we interpret as being due to an increase in the number of grains, followed by a period of constancy, suggesting the absence of grain destruction processes during this latter time. A discussion of the evolution of these parameters is made, including certain peculiarities seen in the grain radius evolution.

  18. RZ Leonis Minoris bridging between ER Ursae Majoris-type dwarf nova and nova-like system

    NASA Astrophysics Data System (ADS)

    Kato, Taichi; Ishioka, Ryoko; Isogai, Keisuke; Kimura, Mariko; Imada, Akira; Miller, Ian; Masumoto, Kazunari; Nishino, Hirochika; Kojiguchi, Naoto; Kawabata, Miho; Sakai, Daisuke; Sugiura, Yuki; Furukawa, Hisami; Yamamura, Kenta; Kobayashi, Hiroshi; Matsumoto, Katsura; Wang, Shiang-Yu; Chou, Yi; Ngeow, Chow-Choong; Chen, Wen-Ping; Panwar, Neelam; Lin, Chi-Sheng; Hsiao, Hsiang-Yao; Guo, Jhen-Kuei; Lin, Chien-Cheng; Omarov, Chingis; Kusakin, Anatoly; Krugov, Maxim; Starkey, Donn R.; Pavlenko, Elena P.; Antonyuk, Kirill A.; Sosnjvskij, Aleksei A.; Antonyuk, Oksana I.; Pit, Nikolai V.; Baklanov, Alex V.; Babina, Julia V.; Itoh, Hiroshi; Padovan, Stefano; Akazawa, Hidehiko; Kafka, Stella; de Miguel, Enrique; Pickard, Roger D.; Kiyota, Seiichiro; Shugarov, Sergey Yu.; Chochol, Drahomir; Krushevska, Viktoriia; Sekeráš, Matej; Pikalova, Olga; Sabo, Richard; Dubovsky, Pavol A.; Kudzej, Igor; Ulowetz, Joseph; Dvorak, Shawn; Stone, Geoff; Tordai, Tamás; Dubois, Franky; Logie, Ludwig; Rau, Steve; Vanaverbeke, Siegfried; Vanmunster, Tonny; Oksanen, Arto; Maeda, Yutaka; Kasai, Kiyoshi; Katysheva, Natalia; Morelle, Etienne; Neustroev, Vitaly V.; Sjoberg, George

    2016-12-01

    We observed RZ LMi, which is renowned for its extremely short (˜19 d) supercycle and is a member of a small, unusual class of cataclysmic variables called ER UMa-type dwarf novae, in 2013 and 2016. In 2016, the supercycles of this object substantially lengthened in comparison to the previous measurements to 35, 32, and 60 d for three consecutive superoutbursts. We consider that the object virtually experienced a transition to the nova-like state (permanent superhumper). This observed behavior reproduced the prediction of the thermal-tidal instability model extremely well. We detected a precursor in the 2016 superoutburst and detected growing (stage A) superhumps with a mean period of 0.0602(1) d in 2016 and in 2013. Combined with the period of superhumps immediately after the superoutburst, the mass ratio is not as small as in WZ Sge-type dwarf novae, having orbital periods similar to RZ LMi. By using least absolute shrinkage and selection operator (Lasso) two-dimensional power spectra, we detected possible negative superhumps with a period of 0.05710(1) d. We estimated an orbital period of 0.05792 d, which suggests a mass ratio of 0.105(5). This relatively large mass ratio is even above that of ordinary SU UMa-type dwarf novae, and it is also possible that the exceptionally high mass-transfer rate in RZ LMi may be a result of a stripped secondary with an evolved core in a system evolving toward an AM CVn-type object.

  19. HUBBLE SEES CHANGES IN GAS SHELL AROUND NOVA CYGNI 1992

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The European Space Agency's ESA Faint Object Camera utilizing the corrective optics provided by NASA's COSTAR (Corrective Optics Space Telescope Axial Replacement), has given astronomers their best look yet at a rapidly ballooning bubble of gas blasted off a star. The shell surrounds Nova Cygni 1992, which erupted on February 19, 1992. A nova is a thermonuclear explosion that occurs on the surface of a white dwarf star in a double star system. The new HST image [right] reveals an elliptical and slightly lumpy ring-like structure. The ring is the edge of a bubble of hot gas blasted into space by the nova. The shell is so thin that the FOC does not resolve its true thickness, even with HST's restored vision. An HST image taken on May 31 1993, [left] 467 days after the explosion, provided the first glimpse of the ring and a mysterious bar-like structure. But the image interpretation was severely hampered by HST's optical aberration, that scattered light from the central star which contaminated the ring's image. A comparison of the pre and post COSTAR/FOC images reveals that the ring has evolved in the seven months that have elapsed between the two observations. The ring has expanded from a diameter of approximately 74 to 96 billion miles. The bar-like structure seen in the earlier HST image has disappear. These changes might confirm theories that the bar was produced by a dense layer of gas thrown off in the orbital plane of the double star system. The gas has subsequently grown more tenuous and so the bar has faded. The ring has also grown noticeably more oblong since the earlier image. This suggests the hot gas is escaping more rapidly above and below the system's orbital plane. As the gas continues escaping the ring should grow increasingly egg-shaped in the coming years. HST's newly improved sensitivity and high resolution provides a unique opportunity to understand the novae by resolving the effects of the explosion long before they can be resolved in ground

  20. Nova Ophiuchus 2017 as a Probe of 13C Nucleosynthesis and Carbon Monoxide Formation and Destruction in Classical Novae

    NASA Astrophysics Data System (ADS)

    Joshi, Vishal; Banerjee, D. P. K.; Srivastava, Mudit

    2017-12-01

    We present a series of near-infrared spectra of Nova Ophiuchus 2017 in the K band that record the evolution of the first overtone CO emission in unprecedented detail. Starting from 11.7 days after maximum, when CO is first detected at great strength, the spectra track the CO emission to +25.6 days by which time it is found to have rapidly declined in strength by almost a factor of ∼35. The cause for the rapid destruction of CO is examined in the framework of different mechanisms for CO destruction, namely, an increase in photoionizating flux, chemical pathways of destruction, or destruction by energetic nonthermal particles created in shocks. From LTE modeling of the CO emission, the 12C/13C ratio is determined to be 1.6 ± 0.3. This is consistent with the expected value of this parameter from nucleosynthesis theory for a nova eruption occuring on a low mass (∼ 0.6 {M}ȯ ) carbon–oxygen core white dwarf. The present 12C/13C estimate constitutes one of the most secure estimates of this ratio in a classical nova.

  1. Possible systematization of classic novae by types of light curves. I. Type signs.

    NASA Astrophysics Data System (ADS)

    Rozenbush, A. Eh.

    1999-02-01

    Visual light curves of novae built in axies "outburst amplitude vs logarithm of shell radius" have differences yielding to systematization. As a result of review of more than 90 novae were distinguished groups of novae typical by light curve shape: DQ Her, CP Pup, RR Pic, PU Vul, V1974 Cyg, CP Lac, CQ Mus. Sign of light curve sometimes is added other characteristics. The DQ Her group includes only novae with a dust condensation in the ejected shell. The GQ Mus group includes novae with a smooth light curve. These novae are divided into subgroups by an outburst amplitude and by a length of light curve part before the transition, but with the equal inclination of linear part of light curves.

  2. Chandra Discovers Eruption and Pulsation in Nova Outburst

    NASA Astrophysics Data System (ADS)

    2001-09-01

    NASA's Chandra X-ray Observatory has discovered a giant outburst of X-rays and unusual cyclical pulsing from a white dwarf star that is closely orbiting another star -- the first time either of these phenomena has been seen in X-rays. The observations are helping scientists better understand the thermonuclear explosions that occur in certain binary star systems. The observations of Nova Aquilae were reported today at the "Two Years of Science with Chandra" symposium by an international team led by Sumner Starrfield of Arizona State University. "We found two important results in our Chandra observations. The first was an underlying pulsation every 40 minutes in the X-ray brightness, which we believe comes from the cyclical expansion and contraction of the outer layers of the white dwarf," said Starrfield. "The other result was an enormous flare of X-rays that lasted for 15 minutes. Nothing like this has been seen before from a nova, and we don't know how to explain it." Novas occur on a white dwarf (a star which used up all its nuclear fuel and shrank to roughly the size of the Earth) that is orbiting a normal size star. Strong gravity tides drag hydrogen gas off the normal star and onto the white dwarf, where it can take more than 100,000 years for enough hydrogen to accumulate to ignite nuclear fusion reactions. Gradually, these reactions intensify until a cosmic-sized hydrogen bomb blast results. The outer layers of the white dwarf are then blown away, producing a nova outburst that can be observed for a period of months to years as the material expands into space. "Chandra has allowed us to see deep into the gases ejected by this giant explosion and extract unparalleled information on the evolution of the white dwarf whose surface is exploding," said Jeremy Drake of the Harvard-Smithsonian Center for Astrophysics. The brightening of Nova Aquilae was first detected by optical astronomers in December 1999. "Although this star is at a distance of more than 6

  3. Binary Orbits as the Driver of Gamma-Ray Emission and Mass Ejection in Classical Novae

    NASA Technical Reports Server (NTRS)

    Chomiuk, Laura; Linford, Justin D.; Yang, Jun; O'Brien, T. J.; Paragi, Zsolt; Mioduszewski, Amy J.; Beswick, R. J.; Cheung, C. C.; Mukai, Koji; Nelson, Thomas

    2014-01-01

    Classical novae are the most common astrophysical thermonuclear explosions, occurring on the surfaces of white dwarf stars accreting gas from companions in binary star systems. Novae typically expel about 10 (sup -4) solar masses of material at velocities exceeding 1,000 kilometers per second.However, the mechanism of mass ejection in novae is poorly understood, and could be dominated by the impulsive flash of thermonuclear energy, prolonged optically thick winds or binary interaction with the nova envelope. Classical novae are now routinely detected at giga-electronvolt gamma-ray wavelengths, suggesting that relativistic particles are accelerated by strong shocks in the ejecta. Here we report high-resolution radio imaging of the gamma-ray-emitting nova V959 Mon. We find that its ejecta were shaped by the motion of the binary system: some gas was expelled rapidly along the poles as a wind from the white dwarf, while denser material drifted out along the equatorial plane, propelled by orbital motion..At the interface between the equatorial and polar regions, we observe synchrotron emission indicative of shocks and relativistic particle acceleration, thereby pinpointing the location of gamma-ray production. Binary shaping of the nova ejecta and associated internal shocks are expected to be widespread among novae, explaining why many novae are gamma-ray emitters.

  4. Binary orbits as the driver of γ-ray emission and mass ejection in classical novae.

    PubMed

    Chomiuk, Laura; Linford, Justin D; Yang, Jun; O'Brien, T J; Paragi, Zsolt; Mioduszewski, Amy J; Beswick, R J; Cheung, C C; Mukai, Koji; Nelson, Thomas; Ribeiro, Valério A R M; Rupen, Michael P; Sokoloski, J L; Weston, Jennifer; Zheng, Yong; Bode, Michael F; Eyres, Stewart; Roy, Nirupam; Taylor, Gregory B

    2014-10-16

    Classical novae are the most common astrophysical thermonuclear explosions, occurring on the surfaces of white dwarf stars accreting gas from companions in binary star systems. Novae typically expel about 10(-4) solar masses of material at velocities exceeding 1,000 kilometres per second. However, the mechanism of mass ejection in novae is poorly understood, and could be dominated by the impulsive flash of thermonuclear energy, prolonged optically thick winds or binary interaction with the nova envelope. Classical novae are now routinely detected at gigaelectronvolt γ-ray wavelengths, suggesting that relativistic particles are accelerated by strong shocks in the ejecta. Here we report high-resolution radio imaging of the γ-ray-emitting nova V959 Mon. We find that its ejecta were shaped by the motion of the binary system: some gas was expelled rapidly along the poles as a wind from the white dwarf, while denser material drifted out along the equatorial plane, propelled by orbital motion. At the interface between the equatorial and polar regions, we observe synchrotron emission indicative of shocks and relativistic particle acceleration, thereby pinpointing the location of γ-ray production. Binary shaping of the nova ejecta and associated internal shocks are expected to be widespread among novae, explaining why many novae are γ-ray emitters.

  5. DISCOVERY OF A NEW PHOTOMETRIC SUB-CLASS OF FAINT AND FAST CLASSICAL NOVAE

    SciTech Connect

    Kasliwal, M. M.; Kulkarni, S. R.; Ofek, E. O.

    2011-07-10

    We present photometric and spectroscopic follow-up of a sample of extragalactic novae discovered by the Palomar 60 inch telescope during a search for 'Fast Transients In Nearest Galaxies' (P60-FasTING). Designed as a fast cadence (1 day) and deep (g < 21 mag) survey, P60-FasTING was particularly sensitive to short-lived and faint optical transients. The P60-FasTING nova sample includes 10 novae in M 31, 6 in M 81, 3 in M 82, 1 in NGC 2403, and 1 in NGC 891. This significantly expands the known sample of extragalactic novae beyond the Local Group, including the first discoveries in a starburstmore » environment. Surprisingly, our photometry shows that this sample is quite inconsistent with the canonical maximum-magnitude-rate-of-decline (MMRD) relation for classical novae. Furthermore, the spectra of the P60-FasTING sample are indistinguishable from classical novae. We suggest that we have uncovered a sub-class of faint and fast classical novae in a new phase space in luminosity-timescale of optical transients. Thus, novae span two orders of magnitude in both luminosity and time. Perhaps the MMRD, which is characterized only by the white dwarf mass, was an oversimplification. Nova physics appears to be characterized by a relatively rich four-dimensional parameter space in white dwarf mass, temperature, composition, and accretion rate.« less

  6. Discovery of a New Photometric Sub-class of Faint and Fast Classical Novae

    NASA Astrophysics Data System (ADS)

    Kasliwal, M. M.; Cenko, S. B.; Kulkarni, S. R.; Ofek, E. O.; Quimby, R.; Rau, A.

    2011-07-01

    We present photometric and spectroscopic follow-up of a sample of extragalactic novae discovered by the Palomar 60 inch telescope during a search for "Fast Transients In Nearest Galaxies" (P60-FasTING). Designed as a fast cadence (1 day) and deep (g < 21 mag) survey, P60-FasTING was particularly sensitive to short-lived and faint optical transients. The P60-FasTING nova sample includes 10 novae in M 31, 6 in M 81, 3 in M 82, 1 in NGC 2403, and 1 in NGC 891. This significantly expands the known sample of extragalactic novae beyond the Local Group, including the first discoveries in a starburst environment. Surprisingly, our photometry shows that this sample is quite inconsistent with the canonical maximum-magnitude-rate-of-decline (MMRD) relation for classical novae. Furthermore, the spectra of the P60-FasTING sample are indistinguishable from classical novae. We suggest that we have uncovered a sub-class of faint and fast classical novae in a new phase space in luminosity-timescale of optical transients. Thus, novae span two orders of magnitude in both luminosity and time. Perhaps the MMRD, which is characterized only by the white dwarf mass, was an oversimplification. Nova physics appears to be characterized by a relatively rich four-dimensional parameter space in white dwarf mass, temperature, composition, and accretion rate.

  7. CLASSICAL NOVAE IN ANDROMEDA: LIGHT CURVES FROM THE PALOMAR TRANSIENT FACTORY AND GALEX

    SciTech Connect

    Cao Yi; Lou Yuqing; Kasliwal, Mansi M.

    2012-06-20

    We present optical light curves of 29 novae in M31 during the 2009 and 2010 observing seasons of the Palomar Transient Factory (PTF). The dynamic and rapid cadences in PTF monitoring of M31, from one day to ten minutes, provide excellent temporal coverage of nova light curves, enabling us to record the photometric evolution of M31 novae in unprecedented detail. We also detect eight of these novae in the near-ultraviolet (UV) band with the Galaxy Evolution Explorer (GALEX) satellite. Novae M31N 2009-10b and M31N 2010-11a show prominent UV emission peaking a few days prior to their optical maxima, possibly implyingmore » aspherical outbursts. Additionally, our blueshifted spectrum of the recent outburst of PT And (M31N 2010-12a) indicates that it is a recurrent nova in M31 and not a dwarf nova in the Milky Way as was previously assumed. Finally, we systematically searched for novae in all confirmed globular clusters (GCs) of M31 and found only M31N 2010-10f associated with Bol 126. The specific nova rate in the M31 GC system is thus about one per year, which is not enhanced relative to the rate outside the GC system.« less

  8. MCNP6 simulation of radiographs generated from megaelectron volt X-rays for characterizing a computed tomography system

    NASA Astrophysics Data System (ADS)

    Dooraghi, Alex A.; Tringe, Joseph W.

    2018-04-01

    To evaluate conventional munition, we simulated an x-ray computed tomography (CT) system for generating radiographs from nominal x-ray energies of 6 or 9 megaelectron volts (MeV). CT simulations, informed by measured data, allow for optimization of both system design and acquisition techniques necessary to enhance image quality. MCNP6 radiographic simulation tools were used to model ideal detector responses (DR) that assume either (1) a detector response proportional to photon flux (N) or (2) a detector response proportional to energy flux (E). As scatter may become significant with MeV x-ray systems, simulations were performed with and without the inclusion of object scatter. Simulations were compared against measurements of a cylindrical munition component principally composed of HMX, tungsten and aluminum encased in carbon fiber. Simulations and measurements used a 6 MeV peak energy x-ray spectrum filtered with 3.175 mm of tantalum. A detector response proportional to energy which includes object scatter agrees to within 0.6 % of the measured line integral of the linear attenuation coefficient. Exclusion of scatter increases the difference between measurement and simulation to 5 %. A detector response proportional to photon flux agrees to within 20 % when object scatter is included in the simulation and 27 % when object scatter is excluded.

  9. System design and as-built MCNP model comparison for the Lujan Center target moderator reflector system

    SciTech Connect

    Muhrer, G.; Ferguson, P.D.; Russell, G.J.

    2000-07-01

    During the design of the Manuel Lujan, Jr., Neutron Scattering Center target, a simplified Monte Carlo model was used to estimate target system performance and to aid engineers as decisions were made regarding the construction of the target system. Although the simplified model ideally would perfectly reflect the as-built system performance, assumptions were made in the model during the design process that may result in deviations between the model predictions and the as-built system performance. Now that the Lujan Center target system has been completed, a more detailed, as-built, model of the target system has been completed. The purpose ofmore » this work is to investigate differences between the predicted target system performance of the simplified model and the as-built model from the standpoint of time-averaged moderator brightness. Calculated discrepancies between the two models have been isolated to a few key issues. Figure 1 shows MCNP geometric plots of the simplified and as-built models. Major differences between these two models include details in the moderator designs (plena) and piping, full versus partial moderator canisters (only in the direction of the extracted neutron beam for the simplified model), and reflector details including cooling pipes and engineering tolerance gaps. In addition, Fig. 1 demonstrates that the detailed model includes shielding and additional material beyond that which was modeled by the original simplified model.« less

  10. Inter-comparison of Dose Distributions Calculated by FLUKA, GEANT4, MCNP, and PHITS for Proton Therapy

    NASA Astrophysics Data System (ADS)

    Yang, Zi-Yi; Tsai, Pi-En; Lee, Shao-Chun; Liu, Yen-Chiang; Chen, Chin-Cheng; Sato, Tatsuhiko; Sheu, Rong-Jiun

    2017-09-01

    The dose distributions from proton pencil beam scanning were calculated by FLUKA, GEANT4, MCNP, and PHITS, in order to investigate their applicability in proton radiotherapy. The first studied case was the integrated depth dose curves (IDDCs), respectively from a 100 and a 226-MeV proton pencil beam impinging a water phantom. The calculated IDDCs agree with each other as long as each code employs 75 eV for the ionization potential of water. The second case considered a similar condition of the first case but with proton energies in a Gaussian distribution. The comparison to the measurement indicates the inter-code differences might not only due to different stopping power but also the nuclear physics models. How the physics parameter setting affect the computation time was also discussed. In the third case, the applicability of each code for pencil beam scanning was confirmed by delivering a uniform volumetric dose distribution based on the treatment plan, and the results showed general agreement between each codes, the treatment plan, and the measurement, except that some deviations were found in the penumbra region. This study has demonstrated that the selected codes are all capable of performing dose calculations for therapeutic scanning proton beams with proper physics settings.

  11. MCNP6 unstructured mesh application to estimate the photoneutron distribution and induced activity inside a linac bunker

    NASA Astrophysics Data System (ADS)

    Juste, B.; Morató, S.; Miró, R.; Verdú, G.; Díez, S.

    2017-08-01

    Unwanted neutrons in radiation therapy treatments are typically generated by photonuclear reactions. High-energy beams emitted by medical Linear Accelerators (LinAcs) interact with high atomic number materials situated in the accelerator head and release neutrons. Since neutrons have a high relative biological effectiveness, even low neutron doses may imply significant exposure of patients. It is also important to study radioactivity induced by these photoneutrons when interacting with the different materials and components of the treatment head facility and the shielding room walls, since persons not present during irradiation (e.g. medical staff) may be exposed to them even when the accelerator is not operating. These problems are studied in this work in order to contribute to challenge the radiation protection in these treatment locations. The work has been performed by simulation using the latest state of the art of Monte-Carlo computer code MCNP6. To that, a detailed model of particles transport inside the bunker and treatment head has been carried out using a meshed geometry model. The LinAc studied is an Elekta Precise accelerator with a treatment photon energy of 15 MeV used at the Hospital Clinic Universitari de Valencia, Spain.

  12. Optimization of Neutron Spectrum in Northwest Beam Tube of Tehran Research Reactor for BNCT, by MCNP Code

    SciTech Connect

    Zamani, M.; End of North Kargar st, Atomic Energy Organization of Iran, P.O. Box: 14155-1339, Tehran; Kasesaz, Y.

    2015-07-01

    In order to gain the neutron spectrum with proper components specification for BNCT, it is necessary to design a Beam Shape Assembling (BSA), include of moderator, collimator, reflector, gamma filter and thermal neutrons filter, in front of the initial radiation beam from the source. According to the result of MCNP4C simulation, the Northwest beam tube has the most optimized neuron flux between three north beam tubes of Tehran Research Reactor (TRR). So, it has been chosen for this purpose. Simulation of the BSA has been done in four above mentioned phases. In each stage, ten best configurations of materials withmore » different length and width were selected as the candidates for the next stage. The last BSA configuration includes of: 78 centimeters of air as an empty space, 40 centimeters of Iron plus 52 centimeters of heavy-water as moderator, 30 centimeters of water or 90 centimeters of Aluminum-Oxide as a reflector, 1 millimeters of lithium (Li) as thermal neutrons filter and finally 3 millimeters of Bismuth (Bi) as a filter of gamma radiation. The result of Calculations shows that if we use this BSA configuration for TRR Northwest beam tube, then the best neutron flux and spectrum will be achieved for BNCT. (authors)« less

  13. Shielding calculations for industrial 5/7.5MeV electron accelerators using the MCNP Monte Carlo Code

    NASA Astrophysics Data System (ADS)

    Peri, Eyal; Orion, Itzhak

    2017-09-01

    High energy X-rays from accelerators are used to irradiate food ingredients to prevent growth and development of unwanted biological organisms in food, and by that extend the shelf life of the products. The production of X-rays is done by accelerating 5 MeV electrons and bombarding them into a heavy target (high Z). Since 2004, the FDA has approved using 7.5 MeV energy, providing higher production rates with lower treatments costs. In this study we calculated all the essential data needed for a straightforward concrete shielding design of typical food accelerator rooms. The following evaluation is done using the MCNP Monte Carlo code system: (1) Angular dependence (0-180°) of photon dose rate for 5 MeV and 7.5 MeV electron beams bombarding iron, aluminum, gold, tantalum, and tungsten targets. (2) Angular dependence (0-180°) spectral distribution simulations of bremsstrahlung for gold, tantalum, and tungsten bombarded by 5 MeV and 7.5 MeV electron beams. (3) Concrete attenuation calculations in several photon emission angles for the 5 MeV and 7.5 MeV electron beams bombarding a tantalum target. Based on the simulation, we calculated the expected increase in dose rate for facilities intending to increase the energy from 5 MeV to 7.5 MeV, and the concrete width needed to be added in order to keep the existing dose rate unchanged.

  14. FAR ULTRAVIOLET SPECTROSCOPY OF THE RECURRENT NOVA T PYXIDIS.

    PubMed

    Godon, Patrick; Sion, Edward M; Starrfield, Sumner; Livio, Mario; Williams, Robert E; Woodward, Charles E; Kuin, Paul; Page, Kim L

    2014-04-01

    With six recorded nova outbursts, the prototypical recurrent nova T Pyxidis (T Pyx) is the ideal cataclysmic variable system to assess the net change of the white dwarf mass within a nova cycle. Recent estimates of the mass ejected in the 2011 outburst ranged from a few ~10 -5 M ⊙ to 3.3 × 10 -4 M ⊙ , and assuming a mass accretion rate of 10 -8 -10 -7 M ⊙ yr -1 for 44 yr, it has been concluded that the white dwarf in T Pyx is actually losing mass. Using NLTE disk modeling spectra to fit our recently obtained Hubble Space Telescope COS and STIS spectra, we find a mass accretion rate of up to two orders of magnitude larger than previously estimated. Our larger mass accretion rate is due mainly to the newly derived distance of T Pyx (4.8 kpc, larger than the previous 3.5 kpc estimate), our derived reddening of E ( B - V ) = 0.35 (based on combined IUE and GALEX spectra), and NLTE disk modeling (compared to blackbody and raw flux estimates in earlier works). We find that for most values of the reddening (0.25 ≤ E ( B - V ) ≤ 0.50) and white dwarf mass (0.70 M ⊙ ≤ M wd ≤ 1.35 M ⊙ ) the accreted mass is larger than the ejected mass. Only for a low reddening (~0.25 and smaller) combined with a large white dwarf mass (0.9 M ⊙ and larger) is the ejected mass larger than the accreted one. However, the best results are obtained for a larger value of reddening.

  15. LABORATORY ANALYSIS OF PRESOLAR SILICATE STARDUST FROM A NOVA

    SciTech Connect

    Leitner, J.; Kodolanyi, J.; Hoppe, P.

    2012-08-01

    We report the major element as well as the oxygen, magnesium, and silicon isotope composition of a unique presolar silicate grain found in the fine-grained fraction of the Antarctic CR2 chondrite Graves Nunataks 95229. The grain is characterized by an extremely high {sup 17}O/{sup 16}O ratio (6.3 {+-} 0.2 Multiplication-Sign 10{sup -3}) relative to solar values, whereas its {sup 18}O/{sup 16}O ratio is solar within measurement uncertainty. It also shows enrichments in {sup 25,26}Mg and a significant excess in {sup 30}Si relative to solar system compositions, with {delta}{sup 25}Mg = 79 {+-} 21 per mille , {delta}{sup 26}Mg = 70more » {+-} 20 per mille , and {delta}{sup 30}Si = 379 {+-} 92 per mille . This isotopic composition is consistent with an origin in the ejecta of a {approx}1.3-1.4 M{sub Sun} ONe nova with large contributions of material from a main-sequence companion star of roughly solar metallicity. However, many details of the stellar source remain undetermined, owing to the uncertainties of current nova nucleosynthesis models. Auger electron spectroscopic analyses identify O, Mg, Si, and Fe as the grain's major constituents. Its (Mg+Fe)/Si atomic ratios are lower than that of olivine and correspond on average to Fe-Mg-pyroxene. A complex texture and heterogeneous major element distribution within the grain attest to condensation under non-equilibrium conditions, which is consistent with the proposed nova origin.« less

  16. Searches for sterile neutrinos with NOvA

    DOE PAGES

    Davies, Gavin S.; Aurisano, Adam; Kafka, Gareth K.; ...

    2016-11-15

    Contradictory evidence has been presented on the issue of neutrino mixing between the three known active neutrinos and light sterile neutrino species. Apparent short-baseline neutrino oscillations observed by the LSND and MiniBooNE experiments, the collective evidence of the reactor neutrino anomaly, and the gallium anomaly all point towards sterile neutrinos with mass at the 1 eV level. While these results are tantalizing, they are not conclusive as they are in tension with null results from other short-baseline experiments, and with disappearance searches in longbaseline and atmospheric experiments. The NOvA (NuMI Off-Axis v e Appearance) experiment may help clarify the situationmore » by searching for disappearance of active neutrinos from the NuMI (Neutrinos from the Main Injector) beam over a baseline of 810 km. We describe the method used by NOvA to look for oscillations into sterile neutrinos at the Far Detector (FD) through the disappearance of neutral-current (NC) neutrino events, including preliminary results of this search. In addition, the Near Detector (ND) is well suited for searching for anomalous short-baseline oscillations and probing the LSND and MiniBooNE sterile neutrino allowed regions using a variety of final states. We also present a novel method for selecting samples with high purity at the ND using convolutional neural networks. Furthermore, based on this method, the sensitivity to anomalous short-baseline nt appearance are shown, and searches for anomalous v e appearance and v μ disappearance at the NOvA ND are presented.« less

  17. Coatings for high energy applications. The Nova laser

    NASA Astrophysics Data System (ADS)

    Wirtenson, G. R.

    The combined requirements of energy density, multiple wavelength, and aperture make the coatings for the Nova Inertial Confinement Fusion (ICF) laser unique. This ten beam neodymium glass laser system, built at the Lawrence Livermore National Laboratory (LLNL), has over a thousand major optical components; some larger than one meter in diameter and weighing 380 Kg. The laser operates at 1054 nm and can be frequency doubled to 527 nm or tripled to 351 nm by means of full aperture potassium dihydrogen phosphate (KDP) crystal arrays. The 1.0 nsec fluence varies along the laser chain, sometimes reaching values as high as 16 J/cm(2) at the input lens to one of the spatial filters. The design specifications of this massive optical system were changed several times as the state-of-the-art advanced. Each change required redesign of the optical coatings even as vendors were preparing for production runs. Frequency conversion to include shorter wavelengths mandated the first major coating redesign and was followed almost immediately by a second redesign to reduce solarization effects in borosilicate crown glass. The conventional thermal evaporation process although successful for the deposition of mirror coatings, was not able to produce antireflection coatings able to survive the locally high chain fluences. As a consequence it became necessary to develop another technique. Solution produced coatings were developed having transmissions exceeding 99% per part and damage threshold values equal to the bare substrate. The unique requirement of the Nova laser necessitated special deposition and metrology equipment. These programmatic developments will be reviewed in the context of the cooperative working relationship developed between LLNL and its vendors. It was this excellent relationship which has enabled LLNL to obtain these highly specialized coatings for the Nova laser.

  18. Discovery of Five Probable Novae in M81

    NASA Astrophysics Data System (ADS)

    Hornoch, K.; Errmann, R.; Sowicka, P.; Humphries, N.; Vaduvescu, O.

    2015-10-01

    We report the discovery of five probable novae in M81 on a co-added 2000-s narrow-band H-alpha CCD image taken with the 2.5-m Isaac Newton Telescope (INT) + WFC at La Palma under ~1.5" seeing on 2015 Oct. 14.198 UT. The new objects are well visible on the co-added image (see the finding charts linked below), but are not present on numerous narrow-band H-alpha archival images from the INT down to limiting magnitude as faint as H-alpha = 22.3.

  19. The peculiar dust shell of Nova DZ Cru (2003).

    SciTech Connect

    Evans, A.; Gehrz, R. D.; Woodward, C. E.

    2010-01-01

    We present Spitzer Space Telescope observations of the 'peculiar variable' DZ Cru, identified by Rushton et al. as a classical nova. A dust shell, on which are superimposed a number of features, is prominent in the 5-35 {micro}m range some 4 yr after eruption. We suggest that the dust in DZ Cru is primarily hydrogenated amorphous carbon in which aliphatic bands currently predominate and which may become either predominantly aromatic as the dust is photoprocessed by ultraviolet radiation from the stellar remnant or more likely completely destroyed.

  20. X-ray detection of Nova Del 2013 with Swift

    NASA Astrophysics Data System (ADS)

    Castro-Tirado, Alberto J.; Martin-Carrillo, Antonio; Hanlon, Lorraine

    2013-08-01

    Continuous X-ray monitoring by Swift of Nova Del 2013 (see CBET #3628) shows an increase of X-ray emission at the source location compared to previous observations (ATEL #5283, ATEL #5305) during a 3.9 ksec observation at UT 2013-08-22 12:05. With the XRT instrument operating in window timing mode, 744 counts were extracted from a 50 pixel long source region and 324 counts from a similar box for a background region, resulting in a 13-sigma detection with a net count rate of 0.11±0.008 counts/sec.

  1. New optical nova candidate in the M 31 disk

    NASA Astrophysics Data System (ADS)

    Henze, M.; Sala, G.; Jose, J.; Figueira, J.; Hernanz, M.; Pietsch, W.,

    2014-07-01

    We report the discovery of a possible nova in the disk of M 31 on two 4x200s stacked R filter CCD images, obtained with the the 80 cm Ritchey-Chretien F/9.6 Joan Oro telescope at Observatori Astronomic del Montsec, owned by the Catalan Government and operated by the Institut d'Estudis Espacials de Catalunya, Spain, using a Finger Lakes PL4240-1-BI CCD Camera (with a Class 1 Basic Broadband coated 2k x 2k chip with 13.5 microns sq.

  2. Naval Observatory Vector Astrometry Software (NOVAS) Version 3.1:Fortran, C, and Python Editions

    NASA Astrophysics Data System (ADS)

    Kaplan, G. H.; Bangert, J. A.; Barron, E. G.; Bartlett, J. L.; Puatua, W.; Harris, W.; Barrett, P.

    2012-08-01

    The Naval Observatory Vector Astrometry Software (NOVAS) is a source - code library that provides common astrometric quantities and transformations to high precision. The library can supply, in one or two subroutine or function calls, the instantaneous celestial position of any star or planet in a variety of coordinate systems. NOVAS also provides access to all of the building blocks that go into such computations. NOVAS is used for a wide variety of applications, including the U.S. portions of The Astronomical Almanac and a number of telescope control systems. NOVAS uses IAU recommended models for Earth orientation, including the IAU 2006 precession theory, the IAU 2000A and 2000B nutation series, and diurnal rotation based on the celestial and terrestrial intermediate origins. Equinox - based quantities, such as sidereal time, are also supported. NOVAS Earth orientation calculations match those from SOFA at the sub - microarcsecond level for comparable transformations. NOVAS algorithms for aberration an d gravitational light deflection are equivalent, at the microarcsecond level, to those inherent in the current consensus VLBI delay algorithm. NOVAS can be easily connected to the JPL planetary/lunar ephemerides (e.g., DE405), and connections to IMCCE and IAA planetary ephemerides are planned. NOVAS Version 3.1 introduces a Python edition alongside the Fortran and C editions. The Python edition uses the computational code from the C edition and currently mimics the function calls of the C edition. Future versions will expand the functionality of the Python edition to exploit the object - oriented features of Python. In the Version 3.1 C edition, the ephemeris - access functions have been revised for use on 64 - bit systems and for improved performance in general. NOVAS source code, auxiliary files, and documentation are available from the USNO website (http://aa.usno.navy.mil/software/novas/novas_info.php).

  3. A LIGHT CURVE ANALYSIS OF CLASSICAL NOVAE: FREE-FREE EMISSION VERSUS PHOTOSPHERIC EMISSION

    SciTech Connect

    Hachisu, Izumi; Kato, Mariko, E-mail: hachisu@ea.c.u-tokyo.ac.jp, E-mail: mariko@educ.cc.keio.ac.jp

    2015-01-10

    We analyzed light curves of seven relatively slower novae, PW Vul, V705 Cas, GQ Mus, RR Pic, V5558 Sgr, HR Del, and V723 Cas, based on an optically thick wind theory of nova outbursts. For fast novae, free-free emission dominates the spectrum in optical bands rather than photospheric emission, and nova optical light curves follow the universal decline law. Faster novae blow stronger winds with larger mass-loss rates. Because the brightness of free-free emission depends directly on the wind mass-loss rate, faster novae show brighter optical maxima. In slower novae, however, we must take into account photospheric emission because of theirmore » lower wind mass-loss rates. We calculated three model light curves of free-free emission, photospheric emission, and their sum for various white dwarf (WD) masses with various chemical compositions of their envelopes and fitted reasonably with observational data of optical, near-IR (NIR), and UV bands. From light curve fittings of the seven novae, we estimated their absolute magnitudes, distances, and WD masses. In PW Vul and V705 Cas, free-free emission still dominates the spectrum in the optical and NIR bands. In the very slow novae, RR Pic, V5558 Sgr, HR Del, and V723 Cas, photospheric emission dominates the spectrum rather than free-free emission, which makes a deviation from the universal decline law. We have confirmed that the absolute brightnesses of our model light curves are consistent with the distance moduli of four classical novae with known distances (GK Per, V603 Aql, RR Pic, and DQ Her). We also discussed the reason why the very slow novae are about ∼1 mag brighter than the proposed maximum magnitude versus rate of decline relation.« less

  4. Monte Carlo determination of the conversion coefficients Hp(3)/Ka in a right cylinder phantom with 'PENELOPE' code. Comparison with 'MCNP' simulations.

    PubMed

    Daures, J; Gouriou, J; Bordy, J M

    2011-03-01

    This work has been performed within the frame of the European Union ORAMED project (Optimisation of RAdiation protection for MEDical staff). The main goal of the project is to improve standards of protection for medical staff for procedures resulting in potentially high exposures and to develop methodologies for better assessing and for reducing, exposures to medical staff. The Work Package WP2 is involved in the development of practical eye-lens dosimetry in interventional radiology. This study is complementary of the part of the ENEA report concerning the calculations with the MCNP-4C code of the conversion factors related to the operational quantity H(p)(3). In this study, a set of energy- and angular-dependent conversion coefficients (H(p)(3)/K(a)), in the newly proposed square cylindrical phantom made of ICRU tissue, have been calculated with the Monte-Carlo code PENELOPE and MCNP5. The H(p)(3) values have been determined in terms of absorbed dose, according to the definition of this quantity, and also with the kerma approximation as formerly reported in ICRU reports. At a low-photon energy (up to 1 MeV), the two results obtained with the two methods are consistent. Nevertheless, large differences are showed at a higher energy. This is mainly due to the lack of electronic equilibrium, especially for small angle incidences. The values of the conversion coefficients obtained with the MCNP-4C code published by ENEA quite agree with the kerma approximation calculations obtained with PENELOPE. We also performed the same calculations with the code MCNP5 with two types of tallies: F6 for kerma approximation and *F8 for estimating the absorbed dose that is, as known, due to secondary electrons. PENELOPE and MCNP5 results agree for the kerma approximation and for the absorbed dose calculation of H(p)(3) and prove that, for photon energies larger than 1 MeV, the transport of the secondary electrons has to be taken into account.

  5. Spectroscopy of the nova-like system UX UMa and two classical novae: V603 Aql and BT Mon

    NASA Astrophysics Data System (ADS)

    Arenas, J.

    2001-05-01

    This dissertation involves the study of three interacting binary stars: V603 Aql (Nova Aquilae 1918), BT Mon (Nova Monocerotis 1939) and UX UMa. UX UMa is the prototype-star of a major sub-class of nova-like systems. Using time-resolved spectroscopic data on V603 Aql, and time-resolved spectrophotometric data on UX UMa and BT Mon, I performed photometric and spectroscopic analyses, as well as Doppler tomographic studies and Eclipse mapping of these three CVs. In V603 Aql, I found evidence, for the first time in spectroscopy, for negative and positive superhump periods in the emission lines and the continuum. The superhump periods found in the continuum and line variations in V603 Aql are consistent with other, photometric, observations. The structure of the accretion disc in UX UMa, based on the models used in this dissertation, is characterized by two regions. An inner accretion disc which is characterized by a blue continuum with absorption lines, which cross over to emission with increasing disc radius. In the case of BT Mon, in my data, the system shows evidence of an accretion disc which is eclipsed by the secondary producing the broad eclipses observed, but a large fraction of the luminosity came from an accretion spot. This can explain the single-peaked emission lines observed in the spectra. Some authors have identified V603 Aql as permanent superhumper (PSH) based on the fact that the photometric period (Psh) is different from the spectroscopic period (Porb), and it has been suggested that the PSHs may represent a subgroup of CVs with mass ratios q<0.3 and high mass transfer rates. My results confirm that V603 Aql shows evidence of instabilities associated with the accretion disc which are the cause of the variations observed.

  6. The Mid-Infrared Evolution of Nova V1974 Cygni

    NASA Astrophysics Data System (ADS)

    Hayward, T. L.; Saizar, P.; Gehrz, R. D.; Benjamin, R. A.; Mason, C. G.; Houck, J. R.; Miles, J. W.; Gull, G. E.; Schoenwald, J.

    1996-10-01

    We observed nova V1974 Cygni (1992) at mid-infrared wavelengths λ = 7.5-13 μm nine times between 1992 April (54 days after the outburst) and 1994 July (day 882). Low- and medium-resolution spectra recorded the evolution of hydrogen recombination lines, free-free continuum emission, and the [Ne II] 12.8 μm, [Ne VI] 7.6 μm, and [Mg VII] 9.0 μm forbidden lines through the nebular and coronal line phases of this event. We interpret the spectra in terms of a series of CLOUDY models that evolve in a physically realistic way throughout the period of observation. The models indicate the presence in the ejecta of three major components of differing densities, but with masses, geometries, and expansion velocities that are consistent with values indicated by optical and UV observations of the nova. In our models the abundances of neon and magnesium relative to hydrogen are 50 and 5 times their solar values, respectively, and significant overabundances of other metals are also implied. We discuss many effects such as the increase of line widths with ionization and the origin of coronal line emission as they are represented by our modeling.

  7. A remarkable recurrent nova in M 31: The optical observations

    NASA Astrophysics Data System (ADS)

    Darnley, M. J.; Williams, S. C.; Bode, M. F.; Henze, M.; Ness, J.-U.; Shafter, A. W.; Hornoch, K.; Votruba, V.

    2014-03-01

    Context. In late Nov. 2013 the fifth eruption in five years of the M 31 recurrent nova M 31N 2008-12a was announced. Aims: In this Letter we address the optical lightcurve and progenitor system of M 31N 2008-12a. Methods: Optical imaging data of the 2013 eruption from the Liverpool Telescope, La Palma; Danish 1.54 m Telescope, La Silla; and archival Hubble Space Telescope near-IR, optical, and near-UV data are astrometrically and photometrically analysed. Results: Photometry of the 2013 eruption, combined with three previous eruptions, enabled construction of a template lightcurve of a very fast nova (t2(V)≃4 days). The archival data allowed recovery of the progenitor system in optical and near-UV data, indicating a red-giant secondary with bright accretion disk, or alternatively a system with a sub-giant secondary but dominated by a disk. Conclusions: The eruptions of M 31N 2008-12a, and a number of historic X-ray detections, indicate a unique system with a recurrence timescale of ~1 yr. This implies the presence of a very high-mass white dwarf and a high accretion rate. The recovered progenitor system is consistent with such an elevated rate of accretion. We encourage additional observations, especially towards the end of 2014.

  8. E-health leads Nova Scotia's healthcare transformation.

    PubMed

    Powers, Patrick

    2009-01-01

    Nova Scotia's healthcare policy direction seems well-defined and well-established for the foreseeable future. This is the case, despite the recent electoral transition from a Progressive Conservative to a New Democratic Party government for the first time in the province's history; and despite the threat of the province's net direct debt increasing through 2012, after eight years of declining net direct debt as a percentage of the province's gross domestic product. As well, little public consideration is being given to disrupting the current regional healthcare organizational structure by further consolidating the province's nine district health authorities (DHA), as occurred last year in Alberta and New Brunswick. Moreover, the Health Information Technology Services Program of Nova Scotia (HITS-NS), the province's shared IT services or provincial service delivery organization, is steadily expanding the inventory of clinical, financial, and administrative software applications hosted for eight DHAs on a common Meditech Client-Server platform, as well as some applications for Capital Health DHA 9 (CDHA) and IWK Health Centre (IWK), the province's consolidated women's and children's hospital located in Halifax.

  9. Sterile Neutrino Search in the NOvA Far Detector

    SciTech Connect

    Edayath, Sijith; Aurisano, Adam; Sousa, Alexandre

    2017-10-03

    The majority of neutrino oscillation experiments have obtained evidence for neutrino oscillations that are compatible with the three-flavor model. Explaining anomalous results from short-baseline experiments, such as LSND and MiniBooNE, in terms of neutrino oscillations requires the existence of sterile neutrinos. The search for sterile neutrino mixing conducted in NOvA uses a long baseline of 810 km between Near Detector (ND) at Fermilab and Far Detector (FD) in Minnesota. The signal for sterile neutrino oscillations is a deficit of neutral-current neutrino interactions at the FD with respect to the ND prediction. In this document, We will present the analysis improvementsmore » that we are implementing for future NC sterile neutrino searches with NOvA. These include: improved modelling of our detector response; the inclusion of NC 2p2h interaction modelling; implementing a better energy reconstruction techniques; and including possible oscillation due to sterile neutrinos in the ND . This improvements enable us to do a simultaneous ND-FD shape fit of the NC energy spectrum covering a wider sterile mass range than previous analyses.« less

  10. Seroprevalence of HIV infection in childbearing women in Nova Scotia.

    PubMed

    Johnston, B L; Haase, D A; Armson, B A; Lee, S H; Manley, K; Hazell, P

    1997-01-01

    To determine the prevalence of HIV-1 infection in childbearing women in Nova Scotia. An anonymous, unlinked seroprevalence study using "leftover" cord bloods. The study was done in 2 stages: I-Halifax Co. women delivering between February 1, 1992 and December 31, 1993; II-non-Halifax Co. women delivering between November 15, 1993 and December 15, 1994. Of 9,115 deliveries during stage I and 5,515 during stage II, specimens were tested from 8,864 (97.2%) and 5,219 (95%) respectively. Halifax Co. women were older, more often married and more often reported a STD than the non-Halifax Co. participants with 20% under age 20 reporting a history of STD. There was one EIA and WB positive result among Halifax Co. women (seroprevalence 1/10,000; 95% CI 0.03-6.29) and one EIA positive, WB indeterminant result among non-Halifax Co. women (seroprevalence 0/10,000; 95% CI 0-5.7). There is a low prevalence of HIV infection among Nova Scotia childbearing women. However, a substantial number, especially those < age 20, reported a history of STD.

  11. The physics of black hole x ray novae

    NASA Technical Reports Server (NTRS)

    Wheeler, J. C.; Kim, S.-W.; Moscoso, M. D.; Mineshige, S.

    1994-01-01

    X-ray transients that are established or plausible black hole candidates have been discovered at a rate of about one per year in the galaxy for the last five years. There are now well over a dozen black hole candidates, most being in the category of X-ray novae with low-mass companions. There may be hundreds of such transient systems in the galaxy yet to be discovered. Classic black hole candidates like Cygnus X-1 with massive companions are in the minority, and their census in the galaxy and magellanic clouds is likely to be complete. The black hole X-ray novae (BHXN) do not represent only the most common environment in which to discover black holes. Their time dependence gives a major new probe with which to study the physics of accretion into black holes. The BHXN show both a soft X-ray flux from an optically thick disk and a hard power law tail that is reminiscent of AGN spectra. The result may be new insight into the classical systems like Cyg X-1 and LMC X-1 that show similar power law tails, but also to accretion into supermassive black holes and AGN.

  12. Event Reconstruction in the NOvA Experiment

    SciTech Connect

    Behera, Biswaranjan; Davies, Gavin; Psihas, Fernanda

    2017-10-10

    The NOvA experiment observes oscillations in two channels (electron-neutrino appearance and muon-neutrino disappearance) using a predominantly muon-neutrino NuMI beam. The Near Detector records multiple overlapping neutrino interactions in each event and the Far Detector has a large background of cosmic rays due to being located on the surface. The oscillation analyses rely on the accurate reconstruction of neutrino interactions in order to precisely measure the neutrino energy and identify the neutrino flavor and interaction mode. Similarly, measurements of neutrino cross sections using the Near Detector require accurate identification of the particle content of each interaction. A series of pattern recognitionmore » techniques have been developed to split event records into individual spatially and temporally separated interactions, to estimate the interaction vertex, and to isolate and classify individual particles within the event. This combination of methods to achieve full event reconstruction in the NOvA detectors has discussed.« less

  13. NOvA Short-Baseline Tau Neutrino Appearance Search

    SciTech Connect

    Keloth, Rijeesh; Aurisano, Adam; Sousa, Alexander

    2017-10-01

    Standard three-flavor neutrino oscillations have well explained by a wide range of neutrino experiments. However, the anomalous results, such as electron-antineutrino excess seen by LSND and MiniBooNE do not fit the three-flavor paradigm. This can be explained by an additional fourth flavor sterile neutrino at a larger scale than the existing three flavor neutrinos. The NOvA experiment consists of two finely segmented, liquid scintillator detectors operating 14 .6 mrad off-axis from the NuMI muon-neutrino beam. The Near Detector is located on the Fermilab campus, 1 km from the NuMI target, while the Far Detector is located at Ash River, MN,more » 810 km from the NuMI target. The NOvA experiment is primarily designed to measure electron-neutrino appearance at the Far Detector using the Near Detector to control systematic uncertainties; however, the Near Detector is well suited for searching for anomalous short-baseline oscillations. This poster will present a novel method for selecting tau neutrino interactions with high purity at the Near Detector using a convolutional neural network. Using this method, the sensitivity to anomalous short-baseline tau-neutrino appearance due to sterile neutrino oscillations will be presented.« less

  14. 3D photoionization models of nova V723 Cas

    NASA Astrophysics Data System (ADS)

    Takeda, L.; Diaz, M.; Campbell, R.; Lyke, J.

    2018-01-01

    We present modelling and analysis of the ejecta of nova V723 Cas based on spatially resolved infrared spectroscopic data from Keck-OSIRIS, with LGSAO (adaptive optics module). The 3D photoionization models include the shell geometry taken from the observations and an anisotropic radiation field, composed by a spherical central source and an accretion disc. Our simulations indicate revised abundances log(NAl/NH) = -5.4, log(NCa/NH) = -6.4 and log(NSi/NH) = -4.7 in the shell. The total ejected mass was found as Mshell = 1.1 × 10-5 M⊙ and the central source temperature and luminosity are T = 280 000 K and L = 1038 erg s-1. The 3D models are compared to basic 1D simulations to demonstrate the importance of using more realistic treatments, stressing the differences in the shell mass, abundances and characterization of the central source. The possibility of V723 Cas being a neon nova and the puzzling central source features found are discussed.

  15. Classical Rayleigh-Taylor instability experiments at Nova

    SciTech Connect

    Budil, K.S.; Remington, B.A.; Weber, S.V.

    1997-11-10

    The evolution of the Rayleigh-Taylor (RT) instability at an embedded, or classical, interface is examined in a series of experiments at the Nova laserfacility .[reference for Nova] These experiments focused on the transition from the linear to nonlinear regimes for both single- and multimode initialperturbations. The development of a single mode at the embedded interface is compared to its evolution at an ablation front and the effect of ablativestabilization is experimentally demonstrated. The multimode experiments have shown evidence of the process of bubble competition, whereinneighboring structures either continue to rise or are washed downstream in the flow depending upon theirmore » relative size. The experiments with simulations performed with either the LASNEX are comparedcode [G. B.Zimmerman and W. L. Kruer, Comments Plasma Phys. Controlled Fusion 2,51 (1975).], a two-dimensional Lagrangian radiation-hydrodynamics code, or CALE [R. Tipton, reference for CALE], a two-dimensional arbitrary Lagrange-Eulerian radiation-hydrodynamics code.« less

  16. > ATCA Radio Monitoring of Nova Lup 2016 (ASAS-SN 16kt)

    NASA Astrophysics Data System (ADS)

    Ryder, S. D.; Kool, E. C.; Chomiuk, L.

    2016-10-01

    The bright Galactic nova in Lupus (ATel #9538, #9539, #9550, CBET #4322) was observed two weeks after discovery using the Australia Telescope Compact Array (ATCA) at 19 GHz on 2016 Oct 9.1 UT. No radio emission was detected at the nova's location, to a 3-sigma upper limit of 0.08 milliJy.

  17. Naval Observatory Vector Astrometry Software (NOVAS) Version 3.1, Introducing a Python Edition

    NASA Astrophysics Data System (ADS)

    Barron, Eric G.; Kaplan, G. H.; Bangert, J.; Bartlett, J. L.; Puatua, W.; Harris, W.; Barrett, P.

    2011-01-01

    The Naval Observatory Vector Astrometry Software (NOVAS) is a source-code library that provides common astrometric quantities and transformations. NOVAS calculations are accurate at the sub-milliarcsecond level. The library can supply, in one or two subroutine or function calls, the instantaneous celestial position of any star or planet in a variety of coordinate systems. NOVAS also provides access to all of the building blocks that go into such computations. NOVAS Version 3.1 introduces a Python edition alongside the Fortran and C editions. The Python edition uses the computational code from the C edition and, currently, mimics the function calls of the C edition. Future versions will expand the functionality of the Python edition to harness the object-oriented nature of the Python language, and will implement the ability to handle large quantities of objects or observers using the array functionality in NumPy (a third-party scientific package for Python). NOVAS 3.1 also adds a module to transform GCRS vectors to the ITRS; the ITRS to GCRS transformation was already provided in NOVAS 3.0. The module that corrects an ITRS vector for polar motion has been modified to undo that correction upon demand. In the C edition, the ephemeris-access functions have been revised for use on 64-bit systems and for improved performance in general. NOVAS, including documentation, is available from the USNO website (http://www.usno.navy.mil/USNO/astronomical-applications/software-products/novas).

  18. The Potential of NovaNET Communications for Education and Instruction.

    ERIC Educational Resources Information Center

    Steinberg, Esther R.

    Intended to suggest ways of implementing the potential of NovaNet beyond its current applications, this report begins with an overview of current educational applications of telecommunications systems. It is noted that NovaNET is not only a successful computer system for presenting instructional courseware, but that it also supports…

  19. Dust formation in Nova Oph 2017 (TCP J17394608-2457555)

    NASA Astrophysics Data System (ADS)

    Joshi, Vishal; Banerjee, D. P. K.; Srivastava, Mudit

    2017-06-01

    Ongoing NIR observations of Nova Oph 2017 indicate the possible onset of dust formation in Nova Oph 2017. Monitoring in the JHKs bands shows a steady rise in the J-K color from around 1.4 on 5 June 2017 to 2.0 on 13 June 2017.

  20. CNO abundances and the strengths of nova outbursts and hydrogen flashes on accreting white dwarfs

    NASA Astrophysics Data System (ADS)

    MacDonald, J.

    1983-04-01

    Simple theories of the accretion phase and expansion phase of hydrogen shell flashes on accreting white dwarfs are used to find the conditions under which classical novae occur. Particular attention is paid to the possibility that the CNO abundances in the accreted envelope are greatly enhanced relative to the Sun. It is shown that such an enhancement is necessary for fast novae, yet slow novae, such as DQ Her, can still occur with large CNO enhancements. An analysis of the observed properties of nova ejecta indicates that the white dwarfs in nova systems have masses in the range 1.02-1.18 Msun. It is found that in some novae, including RR Pic, CP Lac, and V603 Aql, the accretion rate deduced from the optical luminosity in quiescence is too high to allow accretion of sufficient envelope material to get the strong hydrogen flash needed for the nova outburst. Some possible resolutions of this problem are discussed. We also find it unlikely that recurrent novae are thermonuclear runaways on accreting white dwarfs.

  1. ASAS-SN Discovery of A Likely Galactic Nova ASASSN-16ma on the Rise

    NASA Astrophysics Data System (ADS)

    Stanek, K. Z.; Kochanek, C. S.; Brown, J. S.; Holoien, T. W.-S.; Shields, J.; Shappee, B. J.; Prieto, J. L.; Bersier, D.; Dong, Subo; Bose, S.; Chen, Ping; Chomiuk, L.; Strader, J.; Brimacombe, J.

    2016-10-01

    During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"), using data from the quadruple 14-cm "Cassius" telescope in CTIO, Chile, we detect a new transient source, most likely a classical nova, near the Galactic center Object RA (J2000) DEC (J2000) Gal l (deg) Gal b (deg) Disc.

  2. ASAS-SN Discovery of A Likely, Heavily-Obscured Galactic Nova ASASSN-16ig

    NASA Astrophysics Data System (ADS)

    Stanek, K. Z.; Kiyota, S.; Kochanek, C. S.; Brown, J. S.; Holoien, T. W.-S.; Shields, J.; Shappee, G. Simonian B. J.; Prieto, J. L.; Bersier, D.; Dong, Subo; Bose, S.; Chen, Ping; Chomiuk, L.; Strader, J.; Brimacombe, J.

    2016-08-01

    During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"), using data from the quadruple 14-cm "Cassius" telescope in CTIO, Chile, we detect a new transient source, most likely a classical nova, near the Galactic center.

  3. ASAS-SN Discovery of A Likely Galactic Nova ASASSN-16kd

    NASA Astrophysics Data System (ADS)

    Stanek, K. Z.; Kochanek, C. S.; Brown, J. S.; Holoien, T. W.-S.; Shields, J.; Shappee, G. Simonian B. J.; Prieto, J. L.; Bersier, D.; Dong, Subo; Bose, S.; Chen, Ping; Chomiuk, L.; Strader, J.; Brimacombe, J.

    2016-09-01

    During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"), using data from the quadruple 14-cm "Cassius" telescope in Cerro Tololo, Chile, we detect a new transient source, most likely a classical nova, near the Galactic center.

  4. ASAS-SN Discovery of A Likely Galactic Nova ASASSN-17gk on the Rise

    NASA Astrophysics Data System (ADS)

    Stanek, K. Z.; Kochanek, C. S.; Chomiuk, L.; Strader, J.; Brown, J. S.; Holoien, T. W.-S.; Shields, J. V.; Thompson, T. A.; Shappee, B. J.; Prieto, J. L.; Bersier, D.; Dong, Subo; Bose, S.; Chen, Ping; Brimacombe, J.

    2017-05-01

    During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"), using data from the quadruple 14-cm "Cassius" telescope in CTIO, Chile, we detect a very bright, new transient source, most likely a classical nova, near the Galactic plane Object RA (J2000) DEC (J2000) Gal l (deg) Gal b (deg) Disc.

  5. Innovation and Skills Development in the Rural Voluntary Sector in Nova Scotia

    ERIC Educational Resources Information Center

    Canadian Rural Partnership, 2002

    2002-01-01

    This report is a summary of discussions that took place at the Rural Voluntary Sector Leaders' Dialogue, entitled "Innovation and Skills Development in the Rural Voluntary Sector in Nova Scotia", held in Truro, Nova Scotia on September 20, 2002. Many of the discussions took place in brainstorming sessions at which no limits were placed…

  6. ASASSN-18gb: Discovery of A Probable Nova in NGC 3109

    NASA Astrophysics Data System (ADS)

    Brimacombe, J.; Vallely, P.; Stanek, K. Z.; Kochanek, C. S.; Brown, J. S.; Shields, J.; Thompson, T. A.; Shappee, B. J.; Holoien, T. W.-S.; Prieto, J. L.; Bersier, D.; Dong, Subo; Bose, S.; Chen, Ping; Stritzinger, M.; Holmbo, S.

    2018-03-01

    During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN, Shappee et al. 2014), using data from the quadruple 14-cm "Payne-Gaposchkin" telescope in Sutherland, South Africa, we discovered a new transient source, most likely a nova, in the Local Group galaxy NGC 3109.

  7. ASAS-SN Discovery of a Possible Galactic Nova ASASSN-18fs

    NASA Astrophysics Data System (ADS)

    Stanek, K. Z.; Kochanek, C. S.; Shields, J. V.; Thompson, T. A.; Chomiuk, L.; Strader, J.; Shappee, B. J.; Holoien, T. W.-S.; Prieto, J. L.; Dong, Subo; Stritzinger, M.

    2018-03-01

    During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN, Shappee et al. 2014), using data from the quadruple 14-cm "Cassius" telescope in CTIO, Chile, we detect a new transient source, possibly a classical nova (could also be a CV), near the Galactic plane Object RA (J2000) DEC (J2000) Gal l (deg) Gal b (deg) Disc.

  8. ASAS-SN Discovery of a Possible, Very Bright Galactic Nova ASASSN-18fv

    NASA Astrophysics Data System (ADS)

    Stanek, K. Z.; Holoien, T. W.-S.; Kochanek, C. S.; Shields, J. V.; Thompson, T. A.; Chomiuk, L.; Strader, J.; Shappee, B. J.; Prieto, J. L.; Dong, Subo; Stritzinger, M.

    2018-03-01

    During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN, Shappee et al. 2014), using data from the quadruple 14-cm "Cassius" telescope in CTIO, Chile, we detect a new transient source, possibly a classical nova, near the Galactic plane Object RA (J2000) DEC (J2000) Gal l (deg) Gal b (deg) Disc.

  9. Detection of Highly-Absorbed X-rays from Nova Mus 2018 with Swift

    NASA Astrophysics Data System (ADS)

    Nelson, Thomas; Kuin, Paul; Mukai, Koji; Page, Kim; Chomiuk, Laura; Kawash, Adam; Sokoloski, J. L.; Linford, Justin; Rupen, Michael P.; Mioduszewski, Amy

    2018-03-01

    We report the detection of X-rays from Nova Mus 2018 with the Swift XRT instrument. We have been carrying out weekly monitoring of the nova with Swift since its discovery on 2018 Jan 15 (see ATel #11220), and observations up to 2018 Feb 24 yielded X-ray non-detections.

  10. Beryllium detection in the very fast nova ASASSN-16kt (V407 Lupi)

    NASA Astrophysics Data System (ADS)

    Izzo, L.; Molaro, P.; Bonifacio, P.; Della Valle, M.; Cano, Z.; de Ugarte Postigo, A.; Prieto, J. L.; Thöne, C.; Vanzi, L.; Zapata, A.; Fernandez, D.

    2018-02-01

    We present high-resolution spectroscopic observations of the fast nova ASASSN-16kt (V407 Lup). A close inspection of spectra obtained at early stages has revealed the presence of low-ionization lines, and among the others we have identified the presence of the ionised 7Be doublet in a region relatively free from possible contaminants. After studying their intensities, we have inferred that ASASSN-16kt has produced (5.9 - 7.7)× 10-9 M⊙ of 7Be. The identification of bright Ne lines may suggest that the nova progenitor is a massive (1.2 M⊙) oxygen-neon white dwarf. The high outburst frequency of oxygen-neon novae implies that they likely produce an amount of Be similar, if not larger, to that produced by carbon-oxygen novae, then confirming that classical novae are among the main factories of lithium in the Galaxy.

  11. On the possibility of systematizing classical novae by light curve type. I. Type criteria

    NASA Astrophysics Data System (ADS)

    Rosenbush, A. E.

    1999-01-01

    Nova light curves, plotted on “outburst amplitude-logarithm of main shell radius” axes, have differences that can be systematized. As a result of a survey of over 90 novae, nova groups that are typical in light curve shape have been distinguished: DQ Her, CP Pup, RR Pic, PU Vul, V1974 Cyg, CP Lac, and GQ Mus. The light curve criterion is supplemented by other characteristics. The DQ Her group includes only novae having dust formation in the ejected shell. The GQ Mus group combines certain novae with smooth light curves that are separated into several subgroups with respect to outburst amplitude and the duration of the light curve section before the transitional stage, but for which the linear section of the light curve has the same slope.

  12. Quantitative comparison between PGNAA measurements and MCNP calculations in view of the characterization of radioactive wastes in Germany and France

    NASA Astrophysics Data System (ADS)

    Mauerhofer, E.; Havenith, A.; Carasco, C.; Payan, E.; Kettler, J.; Ma, J. L.; Perot, B.

    2013-04-01

    The Forschungszentrum Jülich GmbH (FZJ), together with the Aachen University Rheinisch-Westfaelische Technische Hochschule (RWTH) and the French Alternative Energies and Atomic Energy Commission (CEA Cadarache) are involved in a cooperation aiming at characterizing toxic and reactive elements in radioactive waste packages by means of Prompt Gamma Neutron Activation Analysis (PGNAA) [1]. The French and German waste management agencies have indeed defined acceptability limits concerning these elements in view of their projected geological repositories. A first measurement campaign was performed in the new Prompt Gamma Neutron Activation Analysis (PGNAA) facility called MEDINA, at FZJ, to assess the capture gamma-ray signatures of some elements of interest in large samples up to waste drums with a volume of 200 liter. MEDINA is the acronym for Multi Element Detection based on Instrumental Neutron Activation. This paper presents MCNP calculations of the MEDINA facility and quantitative comparison between measurement and simulation. Passive gamma-ray spectra acquired with a high purity germanium detector and calibration sources are used to qualify the numerical model of the crystal. Active PGNAA spectra of a sodium chloride sample measured with MEDINA then allow for qualifying the global numerical model of the measurement cell. Chlorine indeed constitutes a usual reference with reliable capture gamma-ray production data. The goal is to characterize the entire simulation protocol (geometrical model, nuclear data, and postprocessing tools) which will be used for current measurement interpretation, extrapolation of the performances to other types of waste packages or other applications, as well as for the study of future PGNAA facilities.

  13. Quantitative comparison between PGNAA measurements and MCNP calculations in view of the characterization of radioactive wastes in Germany and France

    SciTech Connect

    Mauerhofer, E.; Havenith, A.; Kettler, J.

    2013-04-19

    The Forschungszentrum Juelich GmbH (FZJ), together with the Aachen University Rheinisch-Westfaelische Technische Hochschule (RWTH) and the French Alternative Energies and Atomic Energy Commission (CEA Cadarache) are involved in a cooperation aiming at characterizing toxic and reactive elements in radioactive waste packages by means of Prompt Gamma Neutron Activation Analysis (PGNAA). The French and German waste management agencies have indeed defined acceptability limits concerning these elements in view of their projected geological repositories. A first measurement campaign was performed in the new Prompt Gamma Neutron Activation Analysis (PGNAA) facility called MEDINA, at FZJ, to assess the capture gamma-ray signatures of somemore » elements of interest in large samples up to waste drums with a volume of 200 liter. MEDINA is the acronym for Multi Element Detection based on Instrumental Neutron Activation. This paper presents MCNP calculations of the MEDINA facility and quantitative comparison between measurement and simulation. Passive gamma-ray spectra acquired with a high purity germanium detector and calibration sources are used to qualify the numerical model of the crystal. Active PGNAA spectra of a sodium chloride sample measured with MEDINA then allow for qualifying the global numerical model of the measurement cell. Chlorine indeed constitutes a usual reference with reliable capture gamma-ray production data. The goal is to characterize the entire simulation protocol (geometrical model, nuclear data, and postprocessing tools) which will be used for current measurement interpretation, extrapolation of the performances to other types of waste packages or other applications, as well as for the study of future PGNAA facilities.« less

  14. The panchromatic spectroscopic evolution of the classical CO nova V339 Delphini (Nova Del 2013) until X-ray turnoff

    NASA Astrophysics Data System (ADS)

    Shore, S. N.; Mason, E.; Schwarz, G. J.; Teyssier, F. M.; Buil, C.; De Gennaro Aquino, I.; Page, K. L.; Osborne, J. P.; Scaringi, S.; Starrfield, S.; van Winckel, H.; Williams, R. E.; Woodward, C. E.

    2016-05-01

    Context. Classical novae are the product of thermonuclear runaway-initiated explosions occurring on accreting white dwarfs. Aims: V339 Del (Nova Delphinus 2013) was one of the brightest classical novae of the last hundred years. Spectroscopy and photometry are available from γ-rays through infrared at stages that have frequently not been observed well. The complete data set is intended to provide a benchmark for comparison with modeling and for understanding more sparsely monitored historical classical and recurrent novae. This paper is the first in the series of reports on the development of the nova. We report here on the early stages of the outburst, through the X-ray active stage. Methods: A time sequence of optical, flux calibrated high resolution spectra was obtained with the Nordic Optical Telescope (NOT) using FIES simultaneously, or contemporaneously, with the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope during the early stages of the outburst. These were supplemented with Mercator/HERMES optical spectra. High resolution IUE ultraviolet spectra of OS And 1986, taken during the Fe curtain phase, served as a template for the distance determination. We used standard plasma diagnostics (e.g., [O III] and [N II] line ratios, and the Hβ line flux) to constrain electron densities and temperatures of the ejecta. Using Monte Carlo modeling of the ejecta, we derived the structure, filling factor, and mass from comparisons of the optical and ultraviolet line profiles. Results: We derive an extinction of E(B - V) = 0.23 ± 0.05 from the spectral energy distribution, the interstellar absorption, and H I emission lines. The distance, about 4-4.5 kpc, is in agreement with the inferred distance from near infrared interferometry. The maximum velocity was about 2500 km s-1, measured from the UV resonance and optical profiles. The ejecta showed considerable fine structure in all transitions, much of which persisted as emission knots. The

  15. Outflows from Compact Objects in Supernovae and Novae

    NASA Astrophysics Data System (ADS)

    Vlasov, Andrey Dmitrievich

    Originally thought of as a constant and unchanging place, the Universe is full of dramas of stars emerging, dying, eating each other, colliding, etc. One of the first transient phenomena noticed were called novae (the name means "new" in Latin). Years later, supernovae were discovered. Despite their names, both novae and supernovae are events in relatively old stars, with supernovae marking the point of stellar death. Known for thousands of years, supernovae and novae remain among the most studied events in our Universe. Supernovae strongly influence the circumstellar medium, enriching it with heavy elements and shocking it, facilitating star formation. Cosmic rays are believed to be accelerated in shocks from supernovae, with small contribution possibly coming from novae. Even though the basic physics of novae is understood, many questions remain unanswered. These include the geometry of the ejecta, why some novae are luminous radio or gamma-ray sources and others are not, what is the ultimate fate of recurrent novae, etc. Supernova explosions are the primary sources of elements heavier than hydrogen and helium. The elements up to nuclear masses A around 100 can form through successive nuclear fusion in the cores of stars starting with hydrogen. Beyond iron, the fusion becomes endothermic instead of exothermic. In addition, for these nuclear masses the temperatures required to overcome the Coulomb barriers are so high that the nuclei are dissociated into alpha particles and free nucleons. Hence all elements heavier than A around 100 should have formed by some other means. These heavier nuclear species are formed by neutron capture on seed nuclei close to or heavier than iron-group nuclei. Depending on the ratio between neutron-capture timescale and beta-decay timescale, neutron-capture processes are called rapid or slow (r- and s-processes, respectively). The s-process, which occurs near the valley of stable isotopes, terminates at Bi (Z=83), because after Bi

  16. Polarimetry and spectroscopy of the "oxygen flaring" DQ Herculis-like nova: V5668 Sagittarii (2015)

    NASA Astrophysics Data System (ADS)

    Harvey, E. J.; Redman, M. P.; Darnley, M. J.; Williams, S. C.; Berdyugin, A.; Piirola, V. E.; Fitzgerald, K. P.; O'Connor, E. G. P.

    2018-03-01

    Context. Classical novae are eruptions on the surface of a white dwarf in a binary system. The material ejected from the white dwarf surface generally forms an axisymmetric shell of gas and dust around the system. The three-dimensional structure of these shells is difficult to untangle when viewed on the plane of the sky. In this work a geometrical model is developed to explain new observations of the 2015 nova V5668 Sagittarii. Aim. We aim to better understand the early evolution of classical nova shells in the context of the relationship between polarisation, photometry, and spectroscopy in the optical regime. To understand the ionisation structure in terms of the nova shell morphology and estimate the emission distribution directly following the light curve's dust-dip. Methods: High-cadence optical polarimetry and spectroscopy observations of a nova are presented. The ejecta is modelled in terms of morpho-kinematics and photoionisation structure. Results: Initially observational results are presented, including broadband polarimetry and spectroscopy of V5668 Sgr nova during eruption. Variability over these observations provides clues towards the evolving structure of the nova shell. The position angle of the shell is derived from polarimetry, which is attributed to scattering from small dust grains. Shocks in the nova outflow are suggested in the photometry and the effect of these on the nova shell are illustrated with various physical diagnostics. Changes in density and temperature as the super soft source phase of the nova began are discussed. Gas densities are found to be of the order of 109 cm-3 for the nova in its auroral phase. The blackbody temperature of the central stellar system is estimated to be around 2.2 × 105 K at times coincident with the super soft source turn-on. It was found that the blend around 4640 Å commonly called "nitrogen flaring" is more naturally explained as flaring of the O II multiplet (V1) from 4638-4696 Å, i.e. "oxygen flaring

  17. First Measurement of Electron Neutrino Appearance in NOvA

    NASA Astrophysics Data System (ADS)

    Adamson, P.; Ader, C.; Andrews, M.; Anfimov, N.; Anghel, I.; Arms, K.; Arrieta-Diaz, E.; Aurisano, A.; Ayres, D. S.; Backhouse, C.; Baird, M.; Bambah, B. A.; Bays, K.; Bernstein, R.; Betancourt, M.; Bhatnagar, V.; Bhuyan, B.; Bian, J.; Biery, K.; Blackburn, T.; Bocean, V.; Bogert, D.; Bolshakova, A.; Bowden, M.; Bower, C.; Broemmelsiek, D.; Bromberg, C.; Brunetti, G.; Bu, X.; Butkevich, A.; Capista, D.; Catano-Mur, E.; Chase, T. R.; Childress, S.; Choudhary, B. C.; Chowdhury, B.; Coan, T. E.; Coelho, J. A. B.; Colo, M.; Cooper, J.; Corwin, L.; Cronin-Hennessy, D.; Cunningham, A.; Davies, G. S.; Davies, J. P.; Del Tutto, M.; Derwent, P. F.; Deepthi, K. N.; Demuth, D.; Desai, S.; Deuerling, G.; Devan, A.; Dey, J.; Dharmapalan, R.; Ding, P.; Dixon, S.; Djurcic, Z.; Dukes, E. C.; Duyang, H.; Ehrlich, R.; Feldman, G. J.; Felt, N.; Fenyves, E. J.; Flumerfelt, E.; Foulkes, S.; Frank, M. J.; Freeman, W.; Gabrielyan, M.; Gallagher, H. R.; Gebhard, M.; Ghosh, T.; Gilbert, W.; Giri, A.; Goadhouse, S.; Gomes, R. A.; Goodenough, L.; Goodman, M. C.; Grichine, V.; Grossman, N.; Group, R.; Grudzinski, J.; Guarino, V.; Guo, B.; Habig, A.; Handler, T.; Hartnell, J.; Hatcher, R.; Hatzikoutelis, A.; Heller, K.; Howcroft, C.; Huang, J.; Huang, X.; Hylen, J.; Ishitsuka, M.; Jediny, F.; Jensen, C.; Jensen, D.; Johnson, C.; Jostlein, H.; Kafka, G. K.; Kamyshkov, Y.; Kasahara, S. M. S.; Kasetti, S.; Kephart, K.; Koizumi, G.; Kotelnikov, S.; Kourbanis, I.; Krahn, Z.; Kravtsov, V.; Kreymer, A.; Kulenberg, Ch.; Kumar, A.; Kutnink, T.; Kwarciancy, R.; Kwong, J.; Lang, K.; Lee, A.; Lee, W. M.; Lee, K.; Lein, S.; Liu, J.; Lokajicek, M.; Lozier, J.; Lu, Q.; Lucas, P.; Luchuk, S.; Lukens, P.; Lukhanin, G.; Magill, S.; Maan, K.; Mann, W. A.; Marshak, M. L.; Martens, M.; Martincik, J.; Mason, P.; Matera, K.; Mathis, M.; Matveev, V.; Mayer, N.; McCluskey, E.; Mehdiyev, R.; Merritt, H.; Messier, M. D.; Meyer, H.; Miao, T.; Michael, D.; Mikheyev, S. P.; Miller, W. H.; Mishra, S. R.; Mohanta, R.; Moren, A.; Mualem, L.; Muether, M.; Mufson, S.; Musser, J.; Newman, H. B.; Nelson, J. K.; Niner, E.; Norman, A.; Nowak, J.; Oksuzian, Y.; Olshevskiy, A.; Oliver, J.; Olson, T.; Paley, J.; Pandey, P.; Para, A.; Patterson, R. B.; Pawloski, G.; Pearson, N.; Perevalov, D.; Pershey, D.; Peterson, E.; Petti, R.; Phan-Budd, S.; Piccoli, L.; Pla-Dalmau, A.; Plunkett, R. K.; Poling, R.; Potukuchi, B.; Psihas, F.; Pushka, D.; Qiu, X.; Raddatz, N.; Radovic, A.; Rameika, R. A.; Ray, R.; Rebel, B.; Rechenmacher, R.; Reed, B.; Reilly, R.; Rocco, D.; Rodkin, D.; Ruddick, K.; Rusack, R.; Ryabov, V.; Sachdev, K.; Sahijpal, S.; Sahoo, H.; Samoylov, O.; Sanchez, M. C.; Saoulidou, N.; Schlabach, P.; Schneps, J.; Schroeter, R.; Sepulveda-Quiroz, J.; Shanahan, P.; Sherwood, B.; Sheshukov, A.; Singh, J.; Singh, V.; Smith, A.; Smith, D.; Smolik, J.; Solomey, N.; Sotnikov, A.; Sousa, A.; Soustruznik, K.; Stenkin, Y.; Strait, M.; Suter, L.; Talaga, R. L.; Tamsett, M. C.; Tariq, S.; Tas, P.; Tesarek, R. J.; Thayyullathil, R. B.; Thomsen, K.; Tian, X.; Tognini, S. C.; Toner, R.; Trevor, J.; Tzanakos, G.; Urheim, J.; Vahle, P.; Valerio, L.; Vinton, L.; Vrba, T.; Waldron, A. V.; Wang, B.; Wang, Z.; Weber, A.; Wehmann, A.; Whittington, D.; Wilcer, N.; Wildberger, R.; Wildman, D.; Williams, K.; Wojcicki, S. G.; Wood, K.; Xiao, M.; Xin, T.; Yadav, N.; Yang, S.; Zadorozhnyy, S.; Zalesak, J.; Zamorano, B.; Zhao, A.; Zirnstein, J.; Zwaska, R.; NOvA Collaboration

    2016-04-01

    We report results from the first search for νμ→νe transitions by the NOvA experiment. In an exposure equivalent to 2.74 ×1020 protons on target in the upgraded NuMI beam at Fermilab, we observe 6 events in the Far Detector, compared to a background expectation of 0.99 ±0.11 (syst) events based on the Near Detector measurement. A secondary analysis observes 11 events with a background of 1.07 ±0.14 (syst) . The 3.3 σ excess of events observed in the primary analysis disfavors 0.1 π <δC P<0.5 π in the inverted mass hierarchy at the 90% C.L.

  18. Was HV 8005 (NSV 213) a Nova?: Erratum

    NASA Astrophysics Data System (ADS)

    Kazarovets, E. V.; Samus, N. N.; Hazen, M. L.; Williams, D. B.; Denissenko, D. V.

    2005-08-01

    In the paper "Was HV 8005 (NSV 213) a Nova?" by E. V. Kazarovets, N. N. Samus, M. L. Hazen, D. B. Williams, and D. V. Denissenko (JAAVSO, 2004, 32, 108-109), there is a misprint in the coordinates of the image found on the Bruce plate of September 26/27, 1929. The correct coordinates are 00h 34m 39.s1 -67° 58' 27'' (J2000.0). All the conclusions are based on correct coordinates and remain unaffected. Also, the field of Figure 1 is 8' x 8', not 15' x 15'. The authors apologize for these mistakes and wish to thank Brian Skiff for turning our attention to them.

  19. IUE observations of the dwarf novae OY Car in superoutburst

    NASA Technical Reports Server (NTRS)

    Hassall, B. J. M.; Naylor, T.; Charles, P. A.; Bath, G. T.; Sonneborn, G.

    1986-01-01

    The May 1985 superoutburst of OY Car, an eclipsing member of the SU UMa subclass of dwarf novae, was observed extensively with IUE to obtain phase-resolved spectra throughout several orbital cycles, when the superhump was well developed and lay close in phase to the eclipse. The UV lines and continuum vary with orbital phase and show a strong UV eclipse coincident with the optical eclipse. This implies that the superhump source at eclipse is not a strong contributor in the ultraviolet. The UV emission line spectrum and lack of X-ray eclipse suggest the presence of an extended coronal region. The flux evolution observed is unusual in that gross changes occur during the decline from superoutburst. The later spectra actually appear hotter than spectra earlier in the decline, and suggest that, early on, the inner disk is obscured from view.

  20. One Thousand New Dwarf Novae from the OGLE Survey

    NASA Astrophysics Data System (ADS)

    Mróz, P.; Udalski, A.; Poleski, R.; Pietrukowicz, P.; Szymański, M. K.; Soszyński, I.; Wyrzykowski, Ł.; Ulaczyk, K.; Kozłowski, S.; Skowron, J.

    2015-12-01

    We present one of the largest collections of dwarf novae (DNe) containing 1091 objects that have been discovered in the long-term photometric data from the Optical Gravitational Lensing Experiment (OGLE) survey. They were found in the OGLE fields toward the Galactic bulge and the Magellanic Clouds. We analyze basic photometric properties of all systems and tentatively find a population of DNe from the Galactic bulge. We identify several dozen of WZ Sge-type DN candidates, including two with superhump periods longer than 0.09 d. Other interesting objects include SU UMa-type stars with "early" precursor outbursts or a Z Cam-type star showing outbursts during standstills. We also provide a list of DNe which will be observed during the K2 Campaign 9 microlensing experiment in 2016. Finally, we present the new OGLE-IV real-time data analysis system: CVOM, which has been designed to provide continuous real time photometric monitoring of selected CVs.

  1. First Measurement of Electron Neutrino Appearance in NOvA.

    PubMed

    Adamson, P; Ader, C; Andrews, M; Anfimov, N; Anghel, I; Arms, K; Arrieta-Diaz, E; Aurisano, A; Ayres, D S; Backhouse, C; Baird, M; Bambah, B A; Bays, K; Bernstein, R; Betancourt, M; Bhatnagar, V; Bhuyan, B; Bian, J; Biery, K; Blackburn, T; Bocean, V; Bogert, D; Bolshakova, A; Bowden, M; Bower, C; Broemmelsiek, D; Bromberg, C; Brunetti, G; Bu, X; Butkevich, A; Capista, D; Catano-Mur, E; Chase, T R; Childress, S; Choudhary, B C; Chowdhury, B; Coan, T E; Coelho, J A B; Colo, M; Cooper, J; Corwin, L; Cronin-Hennessy, D; Cunningham, A; Davies, G S; Davies, J P; Del Tutto, M; Derwent, P F; Deepthi, K N; Demuth, D; Desai, S; Deuerling, G; Devan, A; Dey, J; Dharmapalan, R; Ding, P; Dixon, S; Djurcic, Z; Dukes, E C; Duyang, H; Ehrlich, R; Feldman, G J; Felt, N; Fenyves, E J; Flumerfelt, E; Foulkes, S; Frank, M J; Freeman, W; Gabrielyan, M; Gallagher, H R; Gebhard, M; Ghosh, T; Gilbert, W; Giri, A; Goadhouse, S; Gomes, R A; Goodenough, L; Goodman, M C; Grichine, V; Grossman, N; Group, R; Grudzinski, J; Guarino, V; Guo, B; Habig, A; Handler, T; Hartnell, J; Hatcher, R; Hatzikoutelis, A; Heller, K; Howcroft, C; Huang, J; Huang, X; Hylen, J; Ishitsuka, M; Jediny, F; Jensen, C; Jensen, D; Johnson, C; Jostlein, H; Kafka, G K; Kamyshkov, Y; Kasahara, S M S; Kasetti, S; Kephart, K; Koizumi, G; Kotelnikov, S; Kourbanis, I; Krahn, Z; Kravtsov, V; Kreymer, A; Kulenberg, Ch; Kumar, A; Kutnink, T; Kwarciancy, R; Kwong, J; Lang, K; Lee, A; Lee, W M; Lee, K; Lein, S; Liu, J; Lokajicek, M; Lozier, J; Lu, Q; Lucas, P; Luchuk, S; Lukens, P; Lukhanin, G; Magill, S; Maan, K; Mann, W A; Marshak, M L; Martens, M; Martincik, J; Mason, P; Matera, K; Mathis, M; Matveev, V; Mayer, N; McCluskey, E; Mehdiyev, R; Merritt, H; Messier, M D; Meyer, H; Miao, T; Michael, D; Mikheyev, S P; Miller, W H; Mishra, S R; Mohanta, R; Moren, A; Mualem, L; Muether, M; Mufson, S; Musser, J; Newman, H B; Nelson, J K; Niner, E; Norman, A; Nowak, J; Oksuzian, Y; Olshevskiy, A; Oliver, J; Olson, T; Paley, J; Pandey, P; Para, A; Patterson, R B; Pawloski, G; Pearson, N; Perevalov, D; Pershey, D; Peterson, E; Petti, R; Phan-Budd, S; Piccoli, L; Pla-Dalmau, A; Plunkett, R K; Poling, R; Potukuchi, B; Psihas, F; Pushka, D; Qiu, X; Raddatz, N; Radovic, A; Rameika, R A; Ray, R; Rebel, B; Rechenmacher, R; Reed, B; Reilly, R; Rocco, D; Rodkin, D; Ruddick, K; Rusack, R; Ryabov, V; Sachdev, K; Sahijpal, S; Sahoo, H; Samoylov, O; Sanchez, M C; Saoulidou, N; Schlabach, P; Schneps, J; Schroeter, R; Sepulveda-Quiroz, J; Shanahan, P; Sherwood, B; Sheshukov, A; Singh, J; Singh, V; Smith, A; Smith, D; Smolik, J; Solomey, N; Sotnikov, A; Sousa, A; Soustruznik, K; Stenkin, Y; Strait, M; Suter, L; Talaga, R L; Tamsett, M C; Tariq, S; Tas, P; Tesarek, R J; Thayyullathil, R B; Thomsen, K; Tian, X; Tognini, S C; Toner, R; Trevor, J; Tzanakos, G; Urheim, J; Vahle, P; Valerio, L; Vinton, L; Vrba, T; Waldron, A V; Wang, B; Wang, Z; Weber, A; Wehmann, A; Whittington, D; Wilcer, N; Wildberger, R; Wildman, D; Williams, K; Wojcicki, S G; Wood, K; Xiao, M; Xin, T; Yadav, N; Yang, S; Zadorozhnyy, S; Zalesak, J; Zamorano, B; Zhao, A; Zirnstein, J; Zwaska, R

    2016-04-15

    We report results from the first search for ν_{μ}→ν_{e} transitions by the NOvA experiment. In an exposure equivalent to 2.74×10^{20} protons on target in the upgraded NuMI beam at Fermilab, we observe 6 events in the Far Detector, compared to a background expectation of 0.99±0.11(syst) events based on the Near Detector measurement. A secondary analysis observes 11 events with a background of 1.07±0.14(syst). The 3.3σ excess of events observed in the primary analysis disfavors 0.1π<δ_{CP}<0.5π in the inverted mass hierarchy at the 90% C.L.

  2. Nova Scorpii 2015 == PNV J17032620-3504140

    NASA Astrophysics Data System (ADS)

    Templeton, Matthew R.

    2015-02-01

    AAVSO Alert Notice 508 announces the discovery of Nova Scorpii 2015 = PNV J17032620-3504140 [V1535 Sco] by Tadashi Kojima (Gunma-ken, Japan) at unfiltered DSLR magnitude 8.1, using a 150-mm f/2.8 lens and digital camera, on 2015 February 11.837 UT. Coordinates: RA: 17 03 26.18 , Decl: -35 04 17.6 (2000.0). Echelle spectra by Frederick Walter (Stony Brook University) taken on 2015 February 13.40 UT and reported in Astronomer's Telegram #7060 indicate the presence of strong H-alpha with FWHM of 2000 km/s, along with several other emission features. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

  3. Visible Sensor Development for the SuperNovaAcceleration Probe

    NASA Astrophysics Data System (ADS)

    Roe, N. A.; SNAP Collaboration

    2005-12-01

    Recent progress on the development of radiation-tolerant, red-sensitive CCDs for the SuperNova Acceleration Probe (SNAP) satellite is presented. These CCDs are fully-depleted, thick (200-300 micron), p-channel devices fabricated on high-resistivity n-type silicon. The latest generation of SNAP CCDs can be operated at high substrate voltage (>100V), reducing diffusion and improving the PSF. The improved PSF is important for the precision of shear measurements for the SNAP weak lensing survey. New measurements of diffusion using a "virtual knife edge" technique are presented that verify the predicted improvement, achieving an rms diffusion of 4 microns. In addition, new results on device performance after irradiation with protons and gamma rays are presented. The application of the CCDs designed for the SNAP satellite to ground-based astronomy is also described.

  4. The classical nova hibernation scenario: a definitive confirmation

    NASA Astrophysics Data System (ADS)

    Gaensicke, Boris

    2017-08-01

    The detached white dwarf plus M-dwarf binary LL Eri exhibits truly unique behaviour within this class of compact binaries. As part of a COS snapshot survey, we detected large-amplitude variability in the ultraviolet flux of the white dwarf, confirmed by extensive ground-based blue-band photometry. The three independent frequencies detected in the light curves clearly identify this variability as non-radial pulsations of the white dwarf. However, with a hydrogen atmosphere and Teff=17200K, this white dwarf is nearly 5000K hotter than the canonical instability strip.The COS spectrum, albeit noisy, reveals that the metal lines typically detected in this class of stars, arising from material captured from the M-dwarf wind, are very broad. If interpreted as rotationally broadened, they imply a spin of only a few minutes. Such a short period could be explained by a past phase of intense accretion of mass and angular momentum. It has been postulated for over thirty years that classical nova eruptions on the white dwarf could cause such switching from a semi-detached to a detached binary configuration, during which the system hibernates - yet, to date no hibernating nova has been identified. However, the broad lines could also be due to pulsation-driven surface velocity fields, in which case the nature and past evolution of LL Eri would not be easily linked to any exisiting scenario for compact binary evolution. We propose to obtain a deeper COS observations to unambiguosly determine whether the cause of the observed line broadening is due to rapid rotation, which would unequivocally confirm the hibernation scenario.

  5. Prediction of a Red Nova Outburst in KIC 9832227

    NASA Astrophysics Data System (ADS)

    Molnar, Lawrence A.; Van Noord, Daniel M.; Kinemuchi, Karen; Smolinski, Jason P.; Alexander, Cara E.; Cook, Evan M.; Jang, Byoungchan; Kobulnicky, Henry A.; Spedden, Christopher J.; Steenwyk, Steven D.

    2017-05-01

    We present the first identification of a candidate precursor for an imminent red nova. Our prediction is based on the example of the precursor to the red nova V1309 Sco, which was retrospectively found to be a contact binary with an exponentially decreasing period. We explore the use of this distinctive timing signature to identify precursors, developing the observational and analysis steps needed. We estimate that our Galaxy has roughly 1-10 observable precursors. Specifically, we lay out the observational case for KIC 9832227, which we identified as a tentative candidate two years ago (Molnar et al. 2015, AAS Meeting #225 Abstracts 415.05). Orbital timing over the past two years has followed the tentative exponential fit. As of late 2015, the period time derivative went beyond the range found in other systems (\\dot{P}< | 1× {10}-8| ), a necessary criterion for a serious candidate. We estimate time of merger is the year 2022.2 ± 0.7. Double absorption line spectra confirm directly the 0.458-day light-curve is the orbital period of a contact binary system and yield a mass ratio {m}B/{m}A=0.228+/- 0.003. Closer analysis of the Kepler timing data shows evidence of a component C with orbital period {P}C=590+/- 8 days and {m}C\\sin {I}C=0.11 {M}⊙ . An alternative interpretation of the long-term timing trend, that is, a light travel-time delay due to the orbit around a distant component D, is ruled out by the spectroscopic data for any nondegenerate star. Additional measurements are needed to test further the merging hypothesis and to use fully this fortuitous opportunity.

  6. The Radio Light Curve of the Gamma-Ray Nova in V407 CYG: Thermal Emission from the Ionized Symbiotic Envelope, Devoured from Within by the Nova Blast

    NASA Technical Reports Server (NTRS)

    Chomiuk, Laura; Krauss, Miriam I.; Rupen, Michael P.; Nelson, Thomas; Roy, Nirupam; Sokoloski, Jennifer L.; Mukai, Koji; Munari, Ulisse; Mioduszewski, Amy; Weston, Jeninfer; hide

    2012-01-01

    We present multi-frequency radio observations of the 2010 nova event in the symbiotic binary V407 Cygni, obtained with the Karl G. Jansky Very Large Array (VLA) and spanning 1.45 GHz and 17.770 days following discovery. This nova.the first ever detected in gamma rays.shows a radio light curve dominated by the wind of the Mira giant companion, rather than the nova ejecta themselves. The radio luminosity grewas the wind became increasingly ionized by the nova outburst, and faded as the wind was violently heated from within by the nova shock. This study marks the first time that this physical mechanism has been shown to dominate the radio light curve of an astrophysical transient. We do not observe a thermal signature from the nova ejecta or synchrotron emission from the shock, due to the fact that these components were hidden behind the absorbing screen of the Mira wind. We estimate a mass-loss rate for the Mira wind of .Mw approximately equals 10(exp -6) Solar mass yr(exp -1). We also present the only radio detection of V407 Cyg before the 2010 nova, gleaned from unpublished 1993 archival VLA data, which shows that the radio luminosity of the Mira wind varies by a factor of 20 even in quiescence. Although V407 Cyg likely hosts a massive accreting white dwarf, making it a candidate progenitor system for a Type Ia supernova, the dense and radially continuous circumbinary material surrounding V407 Cyg is inconsistent with observational constraints on the environments of most Type Ia supernovae.

  7. Evaluation of computational models and cross sections used by MCNP6 for simulation of characteristic X-ray emission from thick targets bombarded by kiloelectronvolt electrons

    NASA Astrophysics Data System (ADS)

    Poškus, A.

    2016-09-01

    This paper evaluates the accuracy of the single-event (SE) and condensed-history (CH) models of electron transport in MCNP6.1 when simulating characteristic Kα, total K (=Kα + Kβ) and Lα X-ray emission from thick targets bombarded by electrons with energies from 5 keV to 30 keV. It is shown that the MCNP6.1 implementation of the CH model for the K-shell impact ionization leads to underestimation of the K yield by 40% or more for the elements with atomic numbers Z < 15 and overestimation of the Kα yield by more than 40% for the elements with Z > 25. The Lα yields are underestimated by more than an order of magnitude in CH mode, because MCNP6.1 neglects X-ray emission caused by electron-impact ionization of L, M and higher shells in CH mode (the Lα yields calculated in CH mode reflect only X-ray fluorescence, which is mainly caused by photoelectric absorption of bremsstrahlung photons). The X-ray yields calculated by MCNP6.1 in SE mode (using ENDF/B-VII.1 library data) are more accurate: the differences of the calculated and experimental K yields are within the experimental uncertainties for the elements C, Al and Si, and the calculated Kα yields are typically underestimated by (20-30)% for the elements with Z > 25, whereas the Lα yields are underestimated by (60-70)% for the elements with Z > 49. It is also shown that agreement of the experimental X-ray yields with those calculated in SE mode is additionally improved by replacing the ENDF/B inner-shell electron-impact ionization cross sections with the set of cross sections obtained from the distorted-wave Born approximation (DWBA), which are also used in the PENELOPE code system. The latter replacement causes a decrease of the average relative difference of the experimental X-ray yields and the simulation results obtained in SE mode to approximately 10%, which is similar to accuracy achieved with PENELOPE. This confirms that the DWBA inner-shell impact ionization cross sections are significantly more

  8. Evaluation of the new electron-transport algorithm in MCNP6.1 for the simulation of dose point kernel in water

    NASA Astrophysics Data System (ADS)

    Antoni, Rodolphe; Bourgois, Laurent

    2017-12-01

    In this work, the calculation of specific dose distribution in water is evaluated in MCNP6.1 with the regular condensed history algorithm the "detailed electron energy-loss straggling logic" and the new electrons transport algorithm proposed the "single event algorithm". Dose Point Kernel (DPK) is calculated with monoenergetic electrons of 50, 100, 500, 1000 and 3000 keV for different scoring cells dimensions. A comparison between MCNP6 results and well-validated codes for electron-dosimetry, i.e., EGSnrc or Penelope, is performed. When the detailed electron energy-loss straggling logic is used with default setting (down to the cut-off energy 1 keV), we infer that the depth of the dose peak increases with decreasing thickness of the scoring cell, largely due to combined step-size and boundary crossing artifacts. This finding is less prominent for 500 keV, 1 MeV and 3 MeV dose profile. With an appropriate number of sub-steps (ESTEP value in MCNP6), the dose-peak shift is almost complete absent to 50 keV and 100 keV electrons. However, the dose-peak is more prominent compared to EGSnrc and the absorbed dose tends to be underestimated at greater depths, meaning that boundaries crossing artifact are still occurring while step-size artifacts are greatly reduced. When the single-event mode is used for the whole transport, we observe the good agreement of reference and calculated profile for 50 and 100 keV electrons. Remaining artifacts are fully vanished, showing a possible transport treatment for energies less than a hundred of keV and accordance with reference for whatever scoring cell dimension, even if the single event method initially intended to support electron transport at energies below 1 keV. Conversely, results for 500 keV, 1 MeV and 3 MeV undergo a dramatic discrepancy with reference curves. These poor results and so the current unreliability of the method is for a part due to inappropriate elastic cross section treatment from the ENDF/B-VI.8 library in those

  9. Two new supersoft X-ray sources in M31 identified as classical novae

    NASA Astrophysics Data System (ADS)

    Nelson, T.; Liu, J. F.; di Stefano, R.; Orio, M.; Patel, B.; Primini, F.; Shafter, A. W.

    2008-08-01

    We report the identification of two previously unpublished supersoft X-ray sources (SSS) in M31 as classical novae. The X-ray sources were discovered during a comprehensive search of all archival Chandra/ACIS images of M31 for so-called "Very Soft Sources" (VSS, see Di Stefano & Kong 2003 ApJ, 592, 884). The identification with classical novae was made as part of a larger campaign aimed at optical identification and classification of SSS in M31, and made use of the list of novae in M31 compiled by Pietsch et al.

  10. A comparative study of the neutron flux spectra in the MNSR irradiation sites for the HEU and LEU cores using the MCNP4C code.

    PubMed

    Dawahra, S; Khattab, K; Saba, G

    2015-10-01

    A comparative study for fuel conversion from the HEU to LEU in the Miniature Neutron Source Reactor (MNSR) has been performed in this paper using the MCNP4C code. The neutron energy and lethargy flux spectra in the first inner and outer irradiation sites of the MNSR reactor for the existing HEU fuel (UAl4-Al, 90% enriched) and the potential LEU fuels (U3Si2-Al, U3Si-Al, U9Mo-Al, 19.75% enriched and UO2, 12.6% enriched) were investigated using the MCNP4C code. The neutron energy flux spectra for each group was calculated by dividing the neutron flux by the width of each energy group. The neutron flux spectra per unit lethargy was calculated by multiplying the neutron energy flux spectra for each energy group by the average energy of each group. The thermal neutron flux was calculated by summing the neutron fluxes from 0.0 to 0.625 eV, the fast neutron flux was calculated by summing the neutron fluxes from 0.5 MeV to 10 MeV for the existing HEU and potential LEU fuels. Good agreements have been noticed between the flux spectra for the potential LEU fuels and the existing HEU fuels with maximum relative differences less than 10% and 8% in the inner and outer irradiation sites. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. The design of a multisource americium-beryllium (Am-Be) neutron irradiation facility using MCNP for the neutronic performance calculation.

    PubMed

    Sogbadji, R B M; Abrefah, R G; Nyarko, B J B; Akaho, E H K; Odoi, H C; Attakorah-Birinkorang, S

    2014-08-01

    The americium-beryllium neutron irradiation facility at the National Nuclear Research Institute (NNRI), Ghana, was re-designed with four 20 Ci sources using Monte Carlo N-Particle (MCNP) code to investigate the maximum amount of flux that is produced by the combined sources. The results were compared with a single source Am-Be irradiation facility. The main objective was to enable us to harness the maximum amount of flux for the optimization of neutron activation analysis and to enable smaller sample sized samples to be irradiated. Using MCNP for the design construction and neutronic performance calculation, it was realized that the single-source Am-Be design produced a thermal neutron flux of (1.8±0.0007)×10(6) n/cm(2)s and the four-source Am-Be design produced a thermal neutron flux of (5.4±0.0007)×10(6) n/cm(2)s which is a factor of 3.5 fold increase compared to the single-source Am-Be design. The criticality effective, k(eff), of the single-source and the four-source Am-Be designs were found to be 0.00115±0.0008 and 0.00143±0.0008, respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Implementation and testing of the on-the-fly thermal scattering Monte Carlo sampling method for graphite and light water in MCNP6

    DOE PAGES

    Pavlou, Andrew T.; Ji, Wei; Brown, Forrest B.

    2016-01-23

    Here, a proper treatment of thermal neutron scattering requires accounting for chemical binding through a scattering law S(α,β,T). Monte Carlo codes sample the secondary neutron energy and angle after a thermal scattering event from probability tables generated from S(α,β,T) tables at discrete temperatures, requiring a large amount of data for multiscale and multiphysics problems with detailed temperature gradients. We have previously developed a method to handle this temperature dependence on-the-fly during the Monte Carlo random walk using polynomial expansions in 1/T to directly sample the secondary energy and angle. In this paper, the on-the-fly method is implemented into MCNP6 andmore » tested in both graphite-moderated and light water-moderated systems. The on-the-fly method is compared with the thermal ACE libraries that come standard with MCNP6, yielding good agreement with integral reactor quantities like k-eigenvalue and differential quantities like single-scatter secondary energy and angle distributions. The simulation runtimes are comparable between the two methods (on the order of 5–15% difference for the problems tested) and the on-the-fly fit coefficients only require 5–15 MB of total data storage.« less

  13. Uranium, radium and thorium in soils with high-resolution gamma spectroscopy, MCNP-generated efficiencies, and VRF non-linear full-spectrum nuclide shape fitting

    NASA Astrophysics Data System (ADS)

    Metzger, Robert; Riper, Kenneth Van; Lasche, George

    2017-09-01

    A new method for analysis of uranium and radium in soils by gamma spectroscopy has been developed using VRF ("Visual RobFit") which, unlike traditional peak-search techniques, fits full-spectrum nuclide shapes with non-linear least-squares minimization of the chi-squared statistic. Gamma efficiency curves were developed for a 500 mL Marinelli beaker geometry as a function of soil density using MCNP. Collected spectra were then analyzed using the MCNP-generated efficiency curves and VRF to deconvolute the 90 keV peak complex of uranium and obtain 238U and 235U activities. 226Ra activity was determined either from the radon daughters if the equilibrium status is known, or directly from the deconvoluted 186 keV line. 228Ra values were determined from the 228Ac daughter activity. The method was validated by analysis of radium, thorium and uranium soil standards and by inter-comparison with other methods for radium in soils. The method allows for a rapid determination of whether a sample has been impacted by a man-made activity by comparison of the uranium and radium concentrations to those that would be expected from a natural equilibrium state.

  14. Comparison of penumbra regions produced by ancient Gamma knife model C and Gamma ART 6000 using Monte Carlo MCNP6 simulation.

    PubMed

    Banaee, Nooshin; Asgari, Sepideh; Nedaie, Hassan Ali

    2018-02-08

    The accuracy of penumbral measurements in radiotherapy is pivotal because dose planning computers require accurate data to adequately modeling the beams, which in turn are used to calculate patient dose distributions. Gamma knife is a non-invasive intracranial technique based on principles of the Leksell stereotactic system for open deep brain surgeries, invented and developed by Professor Lars Leksell. The aim of this study is to compare the penumbra widths of Leksell Gamma Knife model C and Gamma ART 6000. Initially, the structure of both systems were simulated by using Monte Carlo MCNP6 code and after validating the accuracy of simulation, beam profiles of different collimators were plotted. MCNP6 beam profile calculations showed that the penumbra values of Leksell Gamma knife model C and Gamma ART 6000 for 18, 14, 8 and 4 mm collimators are 9.7, 7.9, 4.3, 2.6 and 8.2, 6.9, 3.6, 2.4, respectively. The results of this study showed that since Gamma ART 6000 has larger solid angle in comparison with Gamma Knife model C, it produces better beam profile penumbras than Gamma Knife model C in the direct plane. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Monitoring of Northern dwarf novae for radio jets campaign

    NASA Astrophysics Data System (ADS)

    Waagen, Elizabeth O.

    2014-10-01

    Ms. Deanne Coppejans (PhD candidate, Radboud University Nijmegen (Netherlands) and University of Cape Town) and colleagues have requested AAVSO observer assistance in monitoring nine Northern dwarf novae in support of their campaign to observe them in outburst with the Very Large Array (VLA) to search for radio jets. They will observe 5 targets from the following list: U Gem*, EX Dra, Z Cam*, RX And*, EM Cyg, AB Dra, SY Cnc, SU UMa*, and YZ Cnc*. Stars with an asterisk (*) will be given higher priority. The campaign will begin now, starting with monitoring of RX And and EM Cyg, and run through September 2015, or until all five VLA triggers have been used. This campaign is similar to previous AAVSO campaigns, namely the 2007 campaign to monitor a sample of 10 dwarf novae (AAVSO Alert Notice 345), which resulted in the first detection of a radio jet in a dwarf nova system (Koerding et al. 2008, Science, 320, 1318), and the ones carried out at the request of Dr. James Miller-Jones and colleagues on SS Cyg in 2010-2011 (AAVSO Special Notices #204, #206, Alert Notice 445). The latter resulted in an accurate distance determination to SS Cyg, thereby reconciling its behavior with our understanding of accretion disc theory in accreting compact objects (Miller-Jones et al. 2013, Science, 340, 950). Ms. Coppejans writes: "The relation between accretion and outflow is one of the basic problems in modern astrophysics. It has long been thought that CVs are the only accreting systems that do not produce jets, and this notion has even been used to constrain jet models. However, there are now some indications that CVs do show jets, possibly allowing a universal link between accretion and ejection. Radio observations provide the best unambiguous tracer of the corresponding jet or directed outflow, but there are only two clear detections. By observing a more extensive sample of cataclysmic variables in outburst we will determine the existence of jets or other outflows in these

  16. Discovery of an old nova shell surrounding the cataclysmic variable V1315 Aql

    NASA Astrophysics Data System (ADS)

    Sahman, D. I.; Dhillon, V. S.; Littlefair, S. P.; Hallinan, G.

    2018-04-01

    Following our tentative discovery of a faint shell around V1315 Aql reported in Sahman et al. (2015), we undertook deep Hα imaging and intermediate-resolution spectroscopy of the shell. We find that the shell has its geometric centre located on V1315 Aql. The mass, spectral features and density of the shell are consistent with other nova shells, rather than planetary nebulae or supernova remnants. The radial velocity of the shell is consistent with the systemic velocity of V1315 Aql. We believe this evidence strongly suggests that the shell originates from an earlier nova event. This is the first nova shell discovered around a novalike, and supports the theory of nova-induced cycles in mass transfer rates (hibernation theory) first proposed by Shara et al. (1986).

  17. Fermi Establishes Classical Novae as a Distinct Class of Gamma-ray Sources

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Ajello, M.; Albert, A.; Baldini, L.; Ballet, J.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; hide

    2014-01-01

    A classical nova results from runaway thermonuclear explosions on the surface of a white dwarf that accretes matter from a low-mass main-sequence stellar companion. In 2012 and 2013, three novae were detected in gamma rays and stood in contrast to the first gamma-ray detected nova V407 Cygni 2010, which belongs to a rare class of symbiotic binary systems. Despite likely differences in the compositions and masses of their white dwarf progenitors, the three classical novae are similarly characterized as soft spectrum transient gamma-ray sources detected over 2-3 week durations. The gamma-ray detections point to unexpected high-energy particle acceleration processes linked to the mass ejection from thermonuclear explosions in an unanticipated class of Galactic gamma-ray sources.

  18. Fermi establishes classical novae as a distinct class of gamma-ray sources

    DOE PAGES

    Cheung, C. C.

    2014-07-31

    A classical nova results from runaway thermonuclear explosions on the surface of a white dwarf that accretes matter from a low-mass main-sequence stellar companion. In 2012 and 2013, three novae were detected in γ rays and stood in contrast to the first γ-ray detected nova V407 Cygni 2010, which belongs to a rare class of symbiotic binary systems. Despite likely differences in the compositions and masses of their white dwarf progenitors, the three classical novae are similarly characterized as soft spectrum transient γ-ray sources detected over 2-3 week durations. The γ-ray detections point to unexpected high-energy particle acceleration processes linkedmore » to the mass ejection from thermonuclear explosions in an unanticipated class of Galactic γ-ray sources.« less

  19. Gamma-Ray Emission Concurrent with the Nova in the Symbiotic Binary V407 Cygni

    DOE PAGES

    Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

    2010-08-13

    Novae are thermonuclear explosions on a white dwarf surface fueled by mass accreted from a companion star. Current physical models posit that shocked expanding gas from the nova shell can produce x-ray emission, but emission at higher energies has not been widely expected. Here in this paper, we report the Fermi Large Area Telescope detection of variable γ-ray emission (0.1 to 10 billion electron volts) from the recently detected optical nova of the symbiotic star V407 Cygni. We propose that the material of the nova shell interacts with the dense ambient medium of the red giant primary and that particlesmore » can be accelerated effectively to produce π 0 decay γ-rays from proton-proton interactions. Lastly, emission involving inverse Compton scattering of the red giant radiation is also considered and is not ruled out.« less

  20. MINOR MALFORMATIONS AND PHYSICAL MEASURES IN AUTISM: DATA FROM NOVA SCOTIA. (R824758)

    EPA Science Inventory

    In the context of an epidemiological study of autism in Nova Scotia, subjects were evaluated for minor physical anomalies and physical measurements. Normal control children, children with autism and their siblings, and children with developmental disabilities and their siblings w...

  1. Emission line flaring in the SW Sex old nova V533 Herculis

    NASA Astrophysics Data System (ADS)

    Rodríguez-Gil, Pablo; Martínez-Pais, Ignacio G.

    2002-11-01

    We present high time resolution spectroscopy of the non-eclipsing old nova V533 Herculis (N Her 1963). It is the second nova remnant affected by the `SW Sex syndrome'. A modulation of the equivalent width of the emission lines with a period of 23.33 min has been detected. This, together with the strong He II λ4686 emission characteristic of magnetic systems, leads us to link this period to the spin of a magnetic white dwarf. Similar flaring activity has been recorded in other SW Sex stars, namely, the old nova BT Mon, LS Peg and DW UMa, supporting the idea of these systems being magnetic accretors. Stationary emission features are also observed in the Balmer lines, which we attribute to the ejected nova shell.

  2. V533 Herculis: the second SW Sex old nova displaying emission-line flaring

    NASA Astrophysics Data System (ADS)

    Rodríguez-Gil, P.; Martínez-Pais, I. G.

    2002-11-01

    We present high-time-resolution spectroscopy of the non-eclipsing old nova V533 Herculis (N Her 1963). It is the second nova remnant affected by the `SW Sex syndrome'. A modulation of the equivalent width of the emission lines with a period of 23.33 min has been detected. This, together with the strong He IIλ4686 emission characteristic of magnetic systems, leads us to link this period to the spin of a magnetic white dwarf. Similar flaring activity has been recorded in other SW Sex stars, namely, the old nova BT Mon, LS Peg and DW UMa, supporting the idea of these systems being magnetic accretors. Stationary emission features are also observed in the Balmer lines, which we attribute to the ejected nova shell.

  3. Gamma-ray emission concurrent with the nova in the symbiotic binary V407 Cygni.

    PubMed

    Abdo, A A; Ackermann, M; Ajello, M; Atwood, W B; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Bechtol, K; Bellazzini, R; Berenji, B; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A W; Bouvier, A; Brandt, T J; Bregeon, J; Brez, A; Brigida, M; Bruel, P; Buehler, R; Burnett, T H; Buson, S; Caliandro, G A; Cameron, R A; Caraveo, P A; Carrigan, S; Casandjian, J M; Cecchi, C; Celik, O; Charles, E; Chaty, S; Chekhtman, A; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Conrad, J; Corbel, S; Corbet, R; DeCesar, M E; den Hartog, P R; Dermer, C D; de Palma, F; Digel, S W; Donato, D; do Couto e Silva, E; Drell, P S; Dubois, R; Dubus, G; Dumora, D; Favuzzi, C; Fegan, S J; Ferrara, E C; Fortin, P; Frailis, M; Fuhrmann, L; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Germani, S; Giglietto, N; Giordano, F; Giroletti, M; Glanzman, T; Godfrey, G; Grenier, I A; Grondin, M-H; Grove, J E; Guiriec, S; Hadasch, D; Harding, A K; Hayashida, M; Hays, E; Healey, S E; Hill, A B; Horan, D; Hughes, R E; Itoh, R; Jean, P; Jóhannesson, G; Johnson, A S; Johnson, R P; Johnson, T J; Johnson, W N; Kamae, T; Katagiri, H; Kataoka, J; Kerr, M; Knödlseder, J; Koerding, E; Kuss, M; Lande, J; Latronico, L; Lee, S-H; Lemoine-Goumard, M; Garde, M Llena; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Makeev, A; Mazziotta, M N; McConville, W; McEnery, J E; Mehault, J; Michelson, P F; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nakamori, T; Naumann-Godo, M; Nestoras, I; Nolan, P L; Norris, J P; Nuss, E; Ohno, M; Ohsugi, T; Okumura, A; Omodei, N; Orlando, E; Ormes, J F; Ozaki, M; Paneque, D; Panetta, J H; Parent, D; Pelassa, V; Pepe, M; Pesce-Rollins, M; Piron, F; Porter, T A; Rainò, S; Rando, R; Ray, P S; Razzano, M; Razzaque, S; Rea, N; Reimer, A; Reimer, O; Reposeur, T; Ripken, J; Ritz, S; Romani, R W; Roth, M; Sadrozinski, H F-W; Sander, A; Parkinson, P M Saz; Scargle, J D; Schinzel, F K; Sgrò, C; Shaw, M S; Siskind, E J; Smith, D A; Smith, P D; Sokolovsky, K V; Spandre, G; Spinelli, P; Stawarz, Ł; Strickman, M S; Suson, D J; Takahashi, H; Takahashi, T; Tanaka, T; Tanaka, Y; Thayer, J B; Thayer, J G; Thompson, D J; Tibaldo, L; Torres, D F; Tosti, G; Tramacere, A; Uchiyama, Y; Usher, T L; Vandenbroucke, J; Vasileiou, V; Vilchez, N; Vitale, V; Waite, A P; Wallace, E; Wang, P; Winer, B L; Wolff, M T; Wood, K S; Yang, Z; Ylinen, T; Ziegler, M; Maehara, H; Nishiyama, K; Kabashima, F; Bach, U; Bower, G C; Falcone, A; Forster, J R; Henden, A; Kawabata, K S; Koubsky, P; Mukai, K; Nelson, T; Oates, S R; Sakimoto, K; Sasada, M; Shenavrin, V I; Shore, S N; Skinner, G K; Sokoloski, J; Stroh, M; Tatarnikov, A M; Uemura, M; Wahlgren, G M; Yamanaka, M

    2010-08-13

    Novae are thermonuclear explosions on a white dwarf surface fueled by mass accreted from a companion star. Current physical models posit that shocked expanding gas from the nova shell can produce x-ray emission, but emission at higher energies has not been widely expected. Here, we report the Fermi Large Area Telescope detection of variable gamma-ray emission (0.1 to 10 billion electron volts) from the recently detected optical nova of the symbiotic star V407 Cygni. We propose that the material of the nova shell interacts with the dense ambient medium of the red giant primary and that particles can be accelerated effectively to produce pi(0) decay gamma-rays from proton-proton interactions. Emission involving inverse Compton scattering of the red giant radiation is also considered and is not ruled out.

  4. Optical and Near-infrared Study of Nova V2676 Oph 2012

    NASA Astrophysics Data System (ADS)

    Raj, A.; Das, R. K.; Walter, F. M.

    2017-02-01

    We present optical spectrophotometric and near-infrared (NIR) photometric observations of the nova V2676 Oph covering the period from 2012 March 29 through 2015 May 8. The optical spectra and photometry of the nova have been taken from SMARTS and Asiago; the NIR photometry was obtained from SMARTS and Mt. Abu. The spectra were dominated by strong H I lines from the Balmer series, Fe II, N I, and [O I] lines in the initial days, typical of an Fe II type nova. The measured FWHM for the Hβ and Hα lines was 800-1200 km s-1. There was pronounced dust formation starting 90 days after the outburst. The J - K color was the largest among recent dust-forming novae.

  5. Continuing ARAS visible spectroscopic monitoring of the slow classical nova Sct 2017 = ASASSN-17hx

    NASA Astrophysics Data System (ADS)

    Guarro, Joan; Berardi, Paolo; Sollecchia, Umberto; Lester, Tim; Bohlsen, Terry; Luckas, Paul; Campos, Fran; Franco, Lorenzo; Garde, Olivier; Buil, Christian; Edlin, Jim; Teyssier, François

    2017-09-01

    We report the results of our continuing spectroscopic monitoring of the slow classical nova Sct 2017 = ASASSN-17hx (Atel# 10523, #10524, #10527, #10558, #10736) as part of the ongoing program by members of the ARAS group.

  6. Constraints on the neutrino flux in NOvA using the near detector data

    DOE PAGES

    Maan, Kuldeep K.

    2016-12-19

    NOvA, a long-baseline neutrino oscillation experiment at Fermilab, is designed to measure electron-neutrino appearance and muon-neutrino disappearance in the NuMI beam. NOvA comprises of two finely segmented liquid scintillator detectors at 14 mrad off-axis in the NuMI beam. An accurate prediction of the neutrino flux is needed for precision oscillation and cross-section measurements. Data from the hadron-production experiments and, importantly, from the NOvA Near Detector provide powerful constraints on the muon-neutrino and electron-neutrino fluxes. In particular, the measurement of the neutrino-electron elastic scattering provides an in situ constraint on the absolute flux. Lastly, this poster presents the data-driven predictions ofmore » the NOvA muonneutrino and electron-neutrino flux, and outlines future improvements in the flux determination.« less

  7. Optical and Near-infrared Study of Nova V2676 Oph 2012

    SciTech Connect

    Raj, A.; Das, R. K.; Walter, F. M., E-mail: ashish.raj@iiap.res.in

    2017-02-01

    We present optical spectrophotometric and near-infrared (NIR) photometric observations of the nova V2676 Oph covering the period from 2012 March 29 through 2015 May 8. The optical spectra and photometry of the nova have been taken from SMARTS and Asiago; the NIR photometry was obtained from SMARTS and Mt. Abu. The spectra were dominated by strong H i lines from the Balmer series, Fe ii, N i, and [O i] lines in the initial days, typical of an Fe ii type nova. The measured FWHM for the H β and H α lines was 800–1200 km s{sup −1}. There wasmore » pronounced dust formation starting 90 days after the outburst. The J − K color was the largest among recent dust-forming novae.« less

  8. Field experience silvicultural cleaning project in young spruce and fir stands in central Nova Scotia

    Treesearch

    Theodore C. Tryon; Thomas W. Hartranft

    1977-01-01

    Silvicultural cleaning production varied from .15 to .34 acres per man day using light weight chain saws in young Spruce and Fir stands in Central Nova Scotia. Direct labor and saw costs, in cleaning young softwood stands in Nova Scotia, can be expected to range generally from $55.00 to $90.00 per acre, depending on crew experience, stand density, and equipment used....

  9. MASTER-ICATE constraints on the outburst time of OGLE-2012-NOVA-002

    NASA Astrophysics Data System (ADS)

    Levato, H.; Saffe, C.; Mallamaci, C.; Lopez, C.; Denisenko, F. Podest D.; Gorbovskoy, E.; Lipunov, V.; Balanutsa, P.; Tiurina, N.; Kornilov, V.; Belinski, A.; Shatskiy, N.; Chazov, V.; Kuznetsov, A.; Zimnukhov, D.; Krushinsky, V.; Zalozhnih, I.; Popov, A.; Bourdanov, A.; Punanova, A.; Ivanov, K.; Yazev, S.; Budnev, N.; Konstantinov, E.; Chuvalaev, O.; Poleshchuk, V.; Gress, O.; Parkhomenko, A.; Tlatov, A.; Dormidontov, D.; Senik, V.; Yurkov, V.; Sergienko, Y.; Varda, D.; Sinyakov, E.; Shumkov, V.; Shurpakov, S.; Podvorotny, P.

    2012-10-01

    MASTER-ICATE very wide field camera (72-mm f/1.2 lens + 11 Mpx CCD) located at Observatorio Astronomico Felix Aguilar (OAFA) near San Juan, Argentina, has observed the position of possible Nova OGLE-2012-NOVA-002 reported by L. Wyrzykowski et al. (ATel #4483) several times before 2012 May 20 and then again after 2012 July 03. MASTER-WFC is continuously imaging the areas of sky (24x16 sq. deg. field of view) with 5-sec unfiltered exposures.

  10. School Gardens: Cultivating Food Security in Nova Scotia Public Schools?

    PubMed

    Carlsson, Liesel; Williams, Patricia L; Hayes-Conroy, Jessica S; Lordly, Daphne; Callaghan, Edith

    2016-09-01

    A small but growing body of peer-reviewed research suggests that school gardens can play a role in building community food security (CFS); however, to date little research exploring the role of school gardens in supporting CFS is available. This paper begins to address this gap in the literature. A qualitative, exploratory, single-case study design was used. The focus of this case study was the school food garden at an elementary school in the River Valley, Nova Scotia, school community. Results provide useful information about potential CFS effects of school gardens in addition to the environmental effects on school gardens important to their effectiveness as CFS tools. Findings suggest children gained food-related knowledge, skills, and values that support long-term CFS. A local social and political landscape at the community, provincial, and school board level were key to strengthening this garden's contributions to CFS. We support Dietitians of Canada's nomination of school gardens as an indicator of CFS with theoretical and practical evidence, underscore the importance of a supportive environment, and need for further research in this area. Health professionals and community organizations provide critical support, helping to weave gardens into a greater movement towards building CFS.

  11. Surface Current Measurements In Terra Nova Bay By Hf Radar

    NASA Astrophysics Data System (ADS)

    Flocco, D.; Falco, P.; Wadhams, P.; Spezie, G.

    We present the preliminary results of a field experiment carried out within frame- work of the CLIMA project of the Italian National Programme for Antarctic Research (PNRA) and in cooperation with the Scott Polar Research Institute of Cambridge. Dur- ing the second period (02/12/1999-23/01/2000) of the XV Italian expedition a coastal radar was used to characterize the current field in the area of Terra Nova Bay (TNB). One of the aims of the CLIMA (Climatic Long-term Interactions for the Mass balance in Antarctica) project is to determine the role of the polynya in the sea ice mass bal- ance, water structure and local climate. The OSCR-II experiment was planned in order to provide surface current measurements in the area of TNB polynya, one of the most important coastal polynya of the Ross Sea. OSCR (Ocean Surface Current Radar) is a shore based, remote sensing system designed to measure sea surface currents in coastal waters. Two radar sites (a master and a slave) provide with radial current mea- surements; data combined from both sites yield the total current vector. Unfortunately the master and slave stations did not work together throughout the whole period of the experiment. A description of the experiment and a discussion of the results, will be proposed.

  12. Weather impacts on leisure activities in Halifax, Nova Scotia.

    PubMed

    Spinney, Jamie E L; Millward, Hugh

    2011-03-01

    The aim of this study was to investigate the impact of daily atmospheric weather conditions on daily leisure activity engagement, with a focus on physically active leisure. The methods capitalize on time diary data that were collected in Halifax, Nova Scotia to calculate objective measures of leisure activity engagement. Daily meteorological data from Environment Canada and daily sunrise and sunset times from the National Research Council of Canada are used to develop objective measures of the natural atmospheric environment. The time diary data were merged with the meteorological data in order to quantify the statistical association between daily weather conditions and the type, participation rate, frequency, and duration of leisure activity engagement. The results indicate that inclement and uncomfortable weather conditions, especially relating to thermal comfort and mechanical comfort, pose barriers to physically active leisure engagement, while promoting sedentary and home-based leisure activities. Overall, daily weather conditions exhibit modest, but significant, effects on leisure activity engagement; the strongest associations being for outdoor active sports and outdoor active leisure time budgets. In conclusion, weather conditions influence the type, participation rate, frequency, and duration of leisure activity engagement, which is an important consideration for health-promotion programming.

  13. Geology of Terra Nova oil field, Grand Banks, Newfoundland

    SciTech Connect

    Dwyer, J.D.; Sullivan, G.W.; Park, J.

    1986-05-01

    Oil was discovered at the Petro-Canada et al Terra Nova K-08 well in May 1984. The well was drilled in the Jeanne d'Arc subbasin, 340 km east of St. John's, Newfoundland, and 35 km southeast of the giant Hibernia oil field. Follow-up wells provided log correlations and core data that have been used with a three-dimensional seismic survey to construct a geologic model. Mapping the field demonstrated a combination structural-stratigraphic trap. The reservoir is within the lower part of the Jeanne d'Arc sequence (Upper Jurassic). This conglomeratic sandstone is interpreted as having been deposited in a nearshore to fluvial settingmore » by basinward, northward progradation of fan-delta systems. The reservoir has a depositional limit updip to the south, and is overstepped and sealed by transgressive shales of the upper Jeanne d'Arc. Oil source is from the underlying Egret (Oxfordian-Kimmeridgian) argillaceous limestones. The geologic model and seismic interpretation have been tested by appraisal drilling.« less

  14. Weather impacts on leisure activities in Halifax, Nova Scotia

    NASA Astrophysics Data System (ADS)

    Spinney, Jamie E. L.; Millward, Hugh

    2011-03-01

    The aim of this study was to investigate the impact of daily atmospheric weather conditions on daily leisure activity engagement, with a focus on physically active leisure. The methods capitalize on time diary data that were collected in Halifax, Nova Scotia to calculate objective measures of leisure activity engagement. Daily meteorological data from Environment Canada and daily sunrise and sunset times from the National Research Council of Canada are used to develop objective measures of the natural atmospheric environment. The time diary data were merged with the meteorological data in order to quantify the statistical association between daily weather conditions and the type, participation rate, frequency, and duration of leisure activity engagement. The results indicate that inclement and uncomfortable weather conditions, especially relating to thermal comfort and mechanical comfort, pose barriers to physically active leisure engagement, while promoting sedentary and home-based leisure activities. Overall, daily weather conditions exhibit modest, but significant, effects on leisure activity engagement; the strongest associations being for outdoor active sports and outdoor active leisure time budgets. In conclusion, weather conditions influence the type, participation rate, frequency, and duration of leisure activity engagement, which is an important consideration for health-promotion programming.

  15. NSV 1907 - A new eclipsing, nova-like cataclysmic variable

    NASA Astrophysics Data System (ADS)

    Hümmerich, Stefan; Gröbel, Rainer; Hambsch, Franz-Josef; Dubois, Franky; Ashley, Richard; Gänsicke, Boris T.; Vanaverbeke, Siegfried; Bernhard, Klaus; Wils, Patrick

    2017-01-01

    NSV 1907, formerly listed as an irregular variable in variability catalogues, was classified as an Algol-type eclipsing binary in the Catalina Surveys Periodic Variable Star Catalogue. We have identified NSV 1907 as an ultraviolet (UV) bright source using measurements from the GALEX space telescope and detected obvious out-of-eclipse variability in archival photometric data from the Catalina Sky Survey, which instigated a closer examination of the object. A spectrum and extensive multicolour photometric observations were acquired, from which we deduce that NSV 1907 is a deeply eclipsing, nova-like cataclysmic variable. Apart from the orbital variations (deep eclipses with a period of P ≈ 6.63 hours), changes in mean brightness and irregular short-term variability (flickering) were observed. The presence of a secondary minimum at phase φ ≈ 0.5 was established, which indicates a significant contribution of the companion star to the optical flux of the system. We find possible evidence for sinusoidal variations with a period of P ≈ 4.2 d, which we interpret as the nodal precession period of the accretion disc. No outbursts or VY Scl-like drops in brightness were detected either by the CSS or during our photometric monitoring. Because of its spectral characteristics and the observed variability pattern, we propose NSV 1907 as a new moderately bright long-period SW Sextantis star. Further photometric and spectroscopic observations are encouraged.

  16. Nova-like Cataclysmic Variables in the Infrared

    NASA Astrophysics Data System (ADS)

    Hoard, D. W.; Long, Knox S.; Howell, Steve B.; Wachter, Stefanie; Brinkworth, Carolyn S.; Knigge, Christian; Drew, J. E.; Szkody, Paula; Kafka, S.; Belle, Kunegunda; Ciardi, David R.; Froning, Cynthia S.; van Belle, Gerard T.; Pretorius, M. L.

    2014-05-01

    Nova-like (NL) cataclysmic variables have persistently high mass transfer rates and prominent steady state accretion disks. We present an analysis of infrared observations of 12 NLs obtained from the Two Micron All Sky Survey, the Spitzer Space Telescope, and the Wide-field Infrared Survey Explorer All Sky Survey. The presence of an infrared excess at λ >~ 3-5 μm over the expectation of a theoretical steady state accretion disk is ubiquitous in our sample. The strength of the infrared excess is not correlated with orbital period, but shows a statistically significant correlation (but shallow trend) with system inclination that might be partially (but not completely) linked to the increasing view of the cooler outer accretion disk and disk rim at higher inclinations. We discuss the possible origin of the infrared excess in terms of emission from bremsstrahlung or circumbinary dust, with either mechanism facilitated by the mass outflows (e.g., disk wind/corona, accretion stream overflow, and so on) present in NLs. Our comparison of the relative advantages and disadvantages of either mechanism for explaining the observations suggests that the situation is rather ambiguous, largely circumstantial, and in need of stricter observational constraints.

  17. A DWARF NOVA IN THE GLOBULAR CLUSTER M13

    SciTech Connect

    Servillat, M.; Van den Berg, M.; Grindlay, J.

    2011-06-01

    Dwarf novae (DNe) in globular clusters (GCs) seem to be rare with only 13 detections in the 157 known Galactic GCs. We report the identification of a new DN in M13, the 14th DN identified in a GC to date. Using the 2 m Faulkes Telescope North, we conducted a search for stars in M13 that show variability over a year (2005-2006) on timescales of days and months. This led to the detection of one DN showing several outbursts. A Chandra X-ray source is coincident with this DN and shows both a spectrum and variability consistent with that expected frommore » a DN, thus supporting the identification. We searched for a counterpart in Hubble Space Telescope Advanced Camera for Surveys/Wide Field Camera archived images and found at least 11 candidates, of which we could characterize only the 7 brightest, including one with a 3{sigma} H{alpha} excess and a faint blue star. The detection of one DN when more could have been expected likely indicates that our knowledge of the global Galactic population of cataclysmic variables is too limited. The proportion of DNe may be lower than found in catalogs, or they may have a much smaller mean duty cycle ({approx}1%) as proposed by some population synthesis models and recent observations in the field.« less

  18. NASA Opportunities in Visualization, Art, and Science (NOVAS)

    NASA Astrophysics Data System (ADS)

    Fillingim, M. O.; Zevin, D.; Croft, S.; Thrall, L.; Raftery, C. L.; Shackelford, R. L., III

    2014-12-01

    Led by members of UC Berkeley's Multiverse education team at the Space Sciences Laboratory (http://multiverse.ssl.berkeley.edu/), in partnership with UC Berkeley Astronomy, NASA Opportunities in Visualization, Art and Science (NOVAS) is a NASA-funded program mainly for high school students that explores NASA science through art and highlights the need for and uses of art and visualizations in science. The project's aim is to motivate more diverse young people (especially African Americans) to consider Science, Technology, Engineering, and Mathematics (STEM) careers. The program offers intensive summer workshops at community youth centers, afterschool workshops at a local high school, a year-round internship for those who have taken part in one or more of our workshops, public and school outreach, and educator professional development workshops. By adding art (and multimedia) to STEM learning, we wanted to try a unique "STEAM" approach, highlighting how scientists and artists often collaborate, and why scientists need visualization experts. The program values the rise of the STEAM teaching concept, particularly that art and multimedia projects can help communicate science concepts more effectively. We also promote the fact that art and visualization skills can lead to jobs and broader participation in science, and we frequently work with and showcase scientific illustrators and other science visualization professionals.

  19. First neutrino oscillation measurements in NOvA

    DOE PAGES

    Messier, M. D.

    2016-04-20

    In this study, the NOvA experiment uses the Fermilab NuMI neutrino beam and a newly constructed 14 kt detector to address several open questions in neutrino oscillations including the neutrino mass hierarchy, the precise value of the angle θ 23, and the CP-violating phase δ CP. The experiment has been running since 2014 and has recently released its first results from an equivalent exposure of 2.74 × 10 20 protons-on-target equal to 8% of the eventual data set. Measurements of ν μ → ν μ oscillations find Δm 2 32 = (2.52 +0.2 –0.18) × 10 -3 eV 2 andmore » 0.38 < sin 2θ 23 < 0.65 for the normal neutrino mass hierarchy. The experiment has observed ν μ → ν e oscillations at 3.3 σ C.L. in this early data and disfavors the inverted neutrino mass hierarchy in the range 0.1π < δ CP < 0.5π at the 90% C.L.« less

  20. Concerning the origin of novae and U Geminorum stars

    NASA Technical Reports Server (NTRS)

    Bath, G. T.

    1971-01-01

    The dynamical stability of the contact component in a semi-detached binary system is investigated by a linear time dependent analysis. The boundary condition imposed on the photosphere by the Roche lobe is assumed to be one of constant pressure over the whole surface of the lobe, which is treated as being spherically symmetric. The eigenvalues of the linear equation of motion are evaluated for sequences of stellar envelope models under the constraint of this boundary condition. An extensive region in the Hertzprung-Russell diagram is found to be dynamically unstable. This region coincides almost precisely with that predicted by a previous quasi-static study. Time scales for the growth of the instability are also evaluated. Color observations of several novae and U Geminorum stars are discussed in an attempt to provide semi-empirical tests of the proposed theoretical model of the outbursts. In particular the track in the H-R diagram of the U Geminorum star, EM Cygni, is shown to be consistent with an outburst which is purely a temperature change at constant radius, as is demanded by the theory.

  1. Cyclic Period Oscillation of the Eclipsing Dwarf Nova DV UMa

    NASA Astrophysics Data System (ADS)

    Han, Z.-T.; Qian, S.-B.; Irina, Voloshina; Zhu, L.-Y.

    2017-05-01

    DV UMa is an eclipsing dwarf nova with an orbital period of ˜2.06 hr, which lies just at the bottom edge of the period gap. To detect its orbital period changes, we present 12 new mid-eclipse times by using our CCD photometric data and archival data. The latest version of the O-C diagram, combined with the published mid-eclipse times in quiescence, and spanning ˜30 years, was obtained and analyzed. The best fit to those available eclipse timings shows that the orbital period of DV UMa is undergoing a cyclic oscillation with a period of 17.58(+/- 0.52) years and an amplitude of 71.1(+/- 6.7) s. The periodic variation most likely arises from the light-travel-time effect via the presence of a circumbinary object, because the required energy to drive the Applegate mechanism is too high in this system. The mass of the unseen companion was derived as {M}3\\sin I\\prime =0.025(+/- 0.004) {M}⊙ . If the third body is in the orbital plane (I.e., I\\prime =I=82\\buildrel{\\circ}\\over{.} 9) of the eclipsing pair, this would indicate it is a brown dwarf. This hypothetical brown dwarf is orbiting its host star at a separation of ˜8.6 au in an eccentric orbit (e = 0.44).

  2. Ultraviolet studies of nova-like variables with the IUE

    NASA Technical Reports Server (NTRS)

    Guinan, E. F.

    1983-01-01

    KQ Mon is a new UX UMa-type nova-like variable. Optical spectra taken in 1978 reveal very shallow Balmer absorption lines and He I (wavelength 4471) absorption. There was no evidence of orbital variations but the appearance of the optical spectrum and the presence of low amplitude flickering suggested a strong similarity to CD-42 degrees 14462 (=V3885 Sgr) and other members of the UX UMa class. KQ Mon was observed at low dispersion with the IUE satellite. Six spectra taken with the short wavelength prime (SWP) camera are dominated by strong broad absorption lines due to N V, O I, Si III, Si IV, C IV, He II, N IV, and A1 III. There is little evidence of orbital phase modulation over the time baseline of the observations. Unlike UV observations of other UX UMa-type objects, KQ Mon exhibits no emission lines or P Cygni-type profiles and the velocity displacements appear to be smaller, suggesting the absence of a hot, high velocity wind characterizing other UX UMa stars. The relationship of KQ Mon to other UX UMa disk stars is discussed and a model is suggested to explain their observed properties and the lack of major outbursts.

  3. IUD (Nova-T) insertion following induced abortion.

    PubMed

    Bitsch, M; Jakobsen, A B; Prien-Larsen, J C; Frølund, C; Sederberg-Olsen, J

    1990-09-01

    In a prospective study, 86 women who had an IUD (Nova-T) inserted immediately after induced abortion were compared to 95 abortion patients who started another contraception (control I). Additionally, the rate of complications following IUD insertion in a Family Planning Clinic (control II) were studied in 83 non-pregnant women. The overall infection rate for post-abortion patients was 4.4% (5.8% in the study group, 3.2% in control I). No infections were observed in control group II. Confidence limits (95%) for the three groups were overlapping. Among the women in the study group, bleeding and pain were not more frequent, but if one of these complications occurred, it tended to be more serious and the duration was longer. The number of days before resumption of work after abortion was 3-4 days in both abortion groups. After three months, the continuation rate was 83% (71 of 86) in the study group, 76% (72 of 95) in control I and 93% (77 of 83) in control II. Sixty-nine of the 181 women admitted for legal abortion had been admitted for the same reason previously. In this study, the recurrence rate after 12 months was 0% in the study group and 4.2% (4 of 95) in control group I. The insertion of an IUD at the time of abortion seems to be an effective and acceptable solution to the problem of recurrent abortion.

  4. Photometry of the long period dwarf nova GY Hya

    NASA Astrophysics Data System (ADS)

    Bruch, Albert; Monard, Berto

    2017-08-01

    Although comparatively bright, the cataclysmic variable GY Hya has not attracted much attention in the past. As part of a project to better characterize such systems photometrically, we observed light curves in white light, each spanning several hours, at Bronberg Observatory, South Africa, in 2004 and 2005, and at the Observatório do Pico dos Dias, Brazil, in 2014 and 2016. These data permit to study orbital modulations and their variations from season to season. The orbital period, already known from spectroscopic observations of Peters and Thorstensen (2005), is confirmed through strong ellipsoidal variations of the mass donor star in the system and the presence of eclipses of both components. A refined period of 0.34723972 (6) days and revised ephemeries are derived. Seasonal changes in the average orbital light curve can qualitatively be explained by variations of the contribution of a hot spot to the system light together with changes of the disk radius. The amplitude of the ellipsoidal variations and the eclipse contact phases permit to put some constraints on the mass ratio, orbital inclination and the relative brightness of the primary and secondary components. There are some indications that the disk radius during quiescence, expressed in units of the component separation, is smaller than in other dwarf novae.

  5. An Emerging Wine Region in Nova Scotia, Canada: Terroir Trials and Tribulations

    NASA Astrophysics Data System (ADS)

    Cameron, B. I.; Ketter, B. S.; Karakis, S.

    2012-12-01

    Nova Scotia, strategically located on Canada's east coast, is an emerging wine region, whose distinctive wines are garnering international acclaim. Nova Scotia has a long and rich tradition of growing grapes for wine dating back as far as 1611. Nova Scotia's mesoclimates, glacial soils, and proximity to the Atlantic Ocean form a complex alliance to create a unique and expressive terroir. Tidal Bay is a new appellation wine for Nova Scotia stylistically defined as a fresh, crisp and high-acid blend of white grapes. There are four main wine-growing regions in Nova Scotia, all influenced by the warming effects of the Bay of Fundy and Atlantic Ocean: Malagash Peninsula, Annapolis Valley, Bear River Valley and the South Shore. Nova Scotia currently has 14 producing wineries with many more in the development stage. Nova Scotia grape growers not only have had success developing mature and consistent hybrids, but in recent years several vinifera have flourished in this cool climate area. The white hybrids include L'Acadie Blanc, New York Muscat, Seyval Blanc, and Vidal Blanc. The white vinifera include chardonnay, riesling, pinot gris, and sauvignon blanc. Red hybrids are Baco Noir, Leon Millet, Lucie Kuhlmann, and Marechal Foch, whereas the only red vinifera is pinot noir. Nova Scotia has nearly perfect climatic conditions for making world class icewines and sparkling wines. A preliminary GIS analysis of climate, topographic, geology and soil data helps to define Nova Scotia's terroir. Annual precipiatation varies from 10 to 21.6 cm/year with a vast majority of the wineries located in regions with the lowest rainfall. Daily average temperature ranges from 5.5 to 7.5°C, degree growing days above 5°C from 1382 to 1991, and mean August temperature from 15.6 to 19.3 °C. Wineries cluster in the warmest regions based on these temperature measures to assist grape ripening. Soils in these diverse wine regions can range from silty, sandy and clay loams to more gravel-rich sandy

  6. MCNP Simulations of Measurement of Insulation Compaction in the Cryogenic Rocket Fuel Tanks at Kennedy Space Center by Fast/Thermal Neutron Techniques

    NASA Technical Reports Server (NTRS)

    Livingston, R. A.; Schweitzer, J. S.; Parsons, A. M.; Arens, E. E.

    2010-01-01

    MCNP simulations have been run to evaluate the feasibility of using a combination of fast and thermal neutrons as a nondestructive method to measure of the compaction of the perlite insulation in the liquid hydrogen and oxygen cryogenic storage tanks at John F. Kennedy Space Center (KSC). Perlite is a feldspathic volcanic rock made up of the major elements Si, AI, Na, K and 0 along with some water. When heated it expands from four to twenty times its original volume which makes it very useful for thermal insulation. The cryogenic tanks at Kennedy Space Center are spherical with outer diameters of 69-70 feet and lined with a layer of expanded perlite with thicknesses on the order of 120 cm. There is evidence that some of the perlite has compacted over time since the tanks were built 1965, affecting the thermal properties and possibly also the structural integrity of the tanks. With commercially available portable neutron generators it is possible to produce simultaneously fluxes of neutrons in two energy ranges: fast (14 Me V) and thermal (25 me V). The two energy ranges produce complementary information. Fast neutrons produce gamma rays by inelastic scattering, which is sensitive to Fe and O. Thermal neutrons produce gamma rays by prompt gamma neutron activation (PGNA) and this is sensitive to Si, Al, Na, K and H. The compaction of the perlite can be measured by the change in gamma ray signal strength which is proportional to the atomic number densities of the constituent elements. The MCNP simulations were made to determine the magnitude of this change. The tank wall was approximated by a I-dimensional slab geometry with an 11/16" outer carbon steel wall, an inner stainless wall and 120 cm thick perlite zone. Runs were made for cases with expanded perlite, compacted perlite or with various void fractions. Runs were also made to simulate the effect of adding a moderator. Tallies were made for decay-time analysis from t=0 to 10 ms; total detected gamma

  7. Transient Gamma Ray Spectrometer Observations of Gamma-Ray Lines from Novae. I. Limits on the Positron Annihilation Line in Five Individual Novae

    NASA Astrophysics Data System (ADS)

    Harris, M. J.; Naya, J. E.; Teegarden, B. J.; Cline, T. L.; Gehrels, N.; Palmer, D. M.; Ramaty, R.; Seifert, H.

    1999-09-01

    The Transient Gamma Ray Spectrometer (TGRS) on board the Wind spacecraft has spent most of the interval 1995-1997 in a high-altitude orbit where γ-ray backgrounds are low. Its high-resolution Ge spectrometer is thus able to detect weak lines that are slightly offset from stronger background features. One such line is predicted from nucleosynthesis in classical novae, where β decays on a timescale of a few hours in an expanding envelope produce positrons that annihilate to generate a line that is blueshifted by a few keV away from the background annihilation line at 511 keV. The broad TGRS field of view contained five known Galactic novae during 1995 January-1997 June, and we have searched the spectra taken around the times of these events for the blueshifted nova annihilation line. Although no definite detections were made, the method is shown to be sensitive enough to detect novae occurring on ONeMg-rich white dwarfs out to about 2.5 kpc.

  8. The Extraordinary Abundances in QSO Broad Absorption Line Regions: A Matter of Novae?

    NASA Astrophysics Data System (ADS)

    Shields, G. A.

    1995-12-01

    The gas producing the broad absorption lines (BALs) of QSOs appears to have heavy element abundances one to two orders-of-magnitude great than solar (Turnshek 1995, ESO Workshop on QSO Absorption Lines; Korista et al. 1995, Ap. J., in press). Junkarrinen et al. (1995, B.A.A.S., 27, 872; also Junkarrinen 1995, personal communic.) find P/C about 65 times solar in one BAL QSO. Abundances of C, N, O, and Si estimated for a small sample of BAL QSOs are consistent with the distribution of abundances in Galactic novae {Andrea et al. 1994, Astr. Ap., 291, 869). The high P/C ratio is consistent with theoretical models of nova explosions on O-Ne-Mg white dwarfs (Politano et al., Ap. J., 448, 807). This raises the possibility that the BAL gas may largely consist of the ejecta of novae occuring ~ 10(18) cm from the central source. This gas presumably is accelerated to high outflow velocities by the radiation pressure of the QSO luminosity or a fast moving wind. Ordinary novae in an extremely massive nuclear star cluster may produce sufficient material to explain the ~ 10 percent incidence of BALs among all QSOs. The combination of high metallicity and small mass per event helps novae to be competitive with other sources of material, such as planetary nebulae, supernovae, and stellar winds. Alternatively, accretion onto solitary white dwarfs passing through an accretion disk surrounding a supermassive black hole may fuel nova outbursts (... Artymowicz et al. 1993, Ap. J., 409, 592.). This mechanism may provide sufficent nova material with a relatively modest nuclear star cluster if the cluster is substantially corotating with the accretion disk.

  9. COMPREHENSIVE PHOTOMETRIC HISTORIES OF ALL KNOWN GALACTIC RECURRENT NOVAE

    SciTech Connect

    Schaefer, Bradley E.

    2010-04-01

    I collect virtually all photometry of the 10 known galactic recurrent novae (RNe) and their 37 known eruptions. This consists of my modern measures of nearly all archival plates (providing the only data for half of 37 known eruptions), my own 10,000 CCD magnitudes from 1987 to present (providing virtually all of the magnitudes in quiescence for seven RNe), over 140,000 visual magnitude estimates recorded by amateur astronomers (who discovered half the known eruptions), and the small scattering of magnitudes from all the literature. From this, I produce various uniform products: (1) BVRIJHK comparison star magnitudes and BV comparison starmore » sequences to cover the entire range of eruption; (2) complete light curves for all eruptions; (3) best-fit B and V light curve templates; (4) orbital periods for all but one RN; (5) exhaustive searches for all missed eruptions; (6) measured discovery efficiencies since 1890; (7) true recurrence time scales; (8) predicted next eruption dates; (9) variations on time scales of minutes, hours, days, months, years, decades, and century; (10) uniform distances and extinctions to all RNe; (11) BV colors at peak and UBVRIJHK colors at minimum, all with extinction corrections; and (12) the spectral energy distributions over UBVRIJHK. Highlights of this work include the discoveries of one new RN, six previously unknown eruptions, and the orbital periods for half the RNe. The goal of this work is to provide uniform demographics for answering questions like the 'What is the death rate of RNe in our Galaxy?' and 'Are the white dwarfs gaining or losing mass over each eruption cycle?.' An important use of this work is for the question of whether RNe can be the progenitors of Type Ia supernovae.« less

  10. Light Curves Analysis of Deeply Eclipsed Dwarf Nova GY Cnc

    NASA Astrophysics Data System (ADS)

    Voloshina, I.; Khruzina, T.

    2017-03-01

    The results of photometric observations of the dwarf nova GY Cnc in the Rc filter in 2013-2016 are presented, including observations during its outburst in April 2014. The orbital ephemerides of the system have been determined more accurately using these numerous data. The orbital period has not significantly changed during the ˜ 30000 orbital cycles since the earlier observations; no systematic variations of O-C were found out. The fluctuations within the limits 0.004d on a timescale of 1500-2000 Porb were detected. A combined model is used to solve for the parameters of GY Cnc for both states of the system. The donor star temperature, T2˜ 3667 K (Sp M0.2 V) varies between 3440 and 3900 K (Sp K8.8-M1.7 V). The semi-major axis of the disk is a˜0.22a0, on average. In quiet state, a varies within ˜ 40%. The disk has a considerable eccentricity (e˜0.2-0.3) for the small a values, a≤0.2a0. With increasing a the disk shape becomes more circular (e<0.1). The GY Cnc outburst is due to a sharp growth of the disk luminosity because of a diminution of αg parameter (which is related to the viscosity of the disk material) up to 0.1-0.2, and the temperature of the disk interiors increasing twofold to Tin ˜ 95000 K. These changes were probably due to infall of matter onto the surface of white dwarf as the outburst developed. For all accretion disk parameters in a quiet state considerable variations about their mean values are typical.

  11. Visible and Infrared Spectroscopic Evolution of Nova V2467 Cygni

    NASA Astrophysics Data System (ADS)

    Lynch, David K.; Russell, R. W.; Rudy, R. J.; Woodward, C. E.

    2009-01-01

    We present a nineteen-spectrum time series that documents the visible and infrared (0.8 - 5.0 microns) evolution of novae V2467 Cygni. Observations were made using SpeX on the IRTF, and VNIRIS at Lick and spanned the period from 30 Apr 2007 to 12 Aug 2008 UT. Peak brightness (discovery) was mag 7.4 on 15 Mar 2007 UT. The decline rates t2 and t3 were 7.3 and 15.1 days, respectively. Except for some early, low amplitude periodic oscillations, the light curve declined monotonically and showed no evidence of dust formation as of this writing (Oct 1, 2008). The spectrum quickly moved from low excitation on 7 May 2007 UT to showing coronal lines of [Si VI], [Si VII], [Ca VIII], [S VIII] and [S IX] by May 31 2007. At least 5 Rydberg emission lines were present in the latter spectrum and all of the coronal lines had complex profiles. An interstellar reddening of E(B-V) = 1.5. was derived from the Lyman beta-fluoresced OI lines. By 14 Dec 2007 the object displayed many high-excitation emission lines. Coronal lines of [SI VII], [Ca VIII], [Si X], and [S XI] showed notched, doubled line profiles and lines of H I, He I, He II, weak OI, and Rydberg lines were still present. On June 15, 2008 the spectrum was dominated by coronal lines. [Mg VIII] at 3.03 microns was the brightest emission line in the infrared spectrum, and lines from four separate ionization states of silicon were present: [Si VI], [Si VII], [Si IX], [Si X]. Other species displaying coronal emission lines included [P VIII], [S VIII], [S IX], [Ca VII], [Ca VIII] and possibly [Ni X]. The 12 Aug 2008 spectrum was virtually identical to the 15 June 2008 spectrum only fainter.

  12. Outburst-related period changes of recurrent nova CI aquilae

    SciTech Connect

    Wilson, R. E.; Honeycutt, R. K., E-mail: honey@astro.indiana.edu, E-mail: rewilson@ufl.edu

    2014-11-01

    Pre-outburst and post-outburst light curves and post-outburst eclipse timings are analyzed to measure any period (P) change related to nova CI Aql's outburst of early 2000 and a mean post-outburst dP/dt, which then lead to estimates of the accreting component's rate of mass (M) change and its overall outburst-related change of mass over roughly a decade of observations. We apply a recently developed procedure for unified analysis of three timing-related data types (light curves, radial velocities, and eclipse timings), although with only light curves and timings in this case. Fits to the data are reasonably good without need for amore » disk in the light-curve model, although the disk certainly exists and has an important role in our post-outburst mass flow computations. Initial experiments showed that, although there seems to be an accretion hot spot, it has essentially no effect on derived outburst-related ΔP or on post-outburst dP/dt. Use of atomic time (HJED) in place of HJD also has essentially nil effect on ΔP and dP/dt. We find ΔP consistently negative in various types of solutions, although at best only marginally significant statistically in any one experiment. Pre-outburst HJD {sub 0} and P results are given, as are post-outburst HJD {sub 0}, P, and dP/dt, with light curves and eclipse times as joint input, and also with only eclipse time input. Post-outburst dP/dt is negative at about 2.4σ. Explicit formulae for mass transfer rates and epoch-to-epoch mass change are developed and applied. A known offset in the magnitude zero point for 1991-1994 is corrected.« less

  13. NASA Opportunities in Visualization, Art, and Science (NOVAS)

    NASA Astrophysics Data System (ADS)

    Fillingim, M. O.; Zevin, D.; Croft, S.; Thrall, L.; Shackelford, R. L., III

    2015-12-01

    Led by members of UC Berkeley's Multiverse education team at the Space Sciences Laboratory (http://multiverse.ssl.berkeley.edu/), in partnership with UC Berkeley Astronomy, NASA Opportunities in Visualization, Art and Science (NOVAS) is a NASA-funded program mainly for high school students that explores NASA science through art and highlights the need for and uses of art and visualizations in science. The project's aim is to motivate more diverse young people (especially African Americans) to consider Science, Technology, Engineering, and Mathematics (STEM) careers. The program offers intensive summer workshops at community youth centers, afterschool workshops at a local high school, a year-round internship for those who have taken part in one or more of our workshops, public and school outreach, and educator professional development workshops. By adding Art (fine art, graphic art, multimedia, design, and "maker/tinkering" approaches) to STEM learning, we wanted to try a unique combination of what's often now called the "STEAM movement" in STEM education. We've paid particular attention to highlighting how scientists and artists/tinkerers often collaborate, and why scientists need visualization and design experts. The program values the rise of the STEAM teaching concept, particularly that art, multimedia, design, and maker projects can help communicate science concepts more effectively. We also promote the fact that art, design, and visualization skills can lead to jobs and broader participation in science, and we frequently work with and showcase scientific illustrators and other science visualization professionals. This presentation will highlight the significant findings from our multi-year program.

  14. Acceleration of MCNP calculations for small pipes configurations by using Weigth Windows Importance cards created by the SN-3D ATTILA

    NASA Astrophysics Data System (ADS)

    Castanier, Eric; Paterne, Loic; Louis, Céline

    2017-09-01

    In the nuclear engineering, you have to manage time and precision. Especially in shielding design, you have to be more accurate and efficient to reduce cost (shielding thickness optimization), and for this, you use 3D codes. In this paper, we want to see if we can easily applicate the CADIS methods for design shielding of small pipes which go through large concrete walls. We assess the impact of the WW generated by the 3D-deterministic code ATTILA versus WW directly generated by MCNP (iterative and manual process). The comparison is based on the quality of the convergence (estimated relative error (σ), Variance of Variance (VOV) and Figure of Merit (FOM)), on time (computer time + modelling) and on the implement for the engineer.

  15. Calculations of the thermal and fast neutron fluxes in the Syrian miniature neutron source reactor using the MCNP-4C code.

    PubMed

    Khattab, K; Sulieman, I

    2009-04-01

    The MCNP-4C code, based on the probabilistic approach, was used to model the 3D configuration of the core of the Syrian miniature neutron source reactor (MNSR). The continuous energy neutron cross sections from the ENDF/B-VI library were used to calculate the thermal and fast neutron fluxes in the inner and outer irradiation sites of MNSR. The thermal fluxes in the MNSR inner irradiation sites were also measured experimentally by the multiple foil activation method ((197)Au (n, gamma) (198)Au and (59)Co (n, gamma) (60)Co). The foils were irradiated simultaneously in each of the five MNSR inner irradiation sites to measure the thermal neutron flux and the epithermal index in each site. The calculated and measured results agree well.

  16. Self-absorption correction in determining the 238U activity of soil samples via 63.3 keV gamma ray using MCNP5 code.

    PubMed

    Huy, Ngo Quang; Binh, Do Quang; An, Vo Xuan; Loan, Truong Thi Hong; Can, Nguyen Thanh

    2013-01-01

    The essential issue in analyzing the activity of (238)U in an HPGe detector based gamma spectrometer via 63.3 keV line is relating to the strong self-absorption of this weak gamma ray in sample material. The present work suggests a method of the self-absorption corrections for 63.3 keV gamma rays by a combination of experimental measurements and Monte Carlo MCNP5 calculations. The effects of sample chemical composition, density and geometry were calculated in terms of self-attenuation factors. The method, developed for a cylindrical sample geometry, accounted for variable sample heights and densities. The analysis of (238)U activity was applied for three main soil types in Vietnam, which are grey, alluvial and red soils. The results obtained with the above outlined method were in good agreement with those derived by other methods. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Bias estimates used in lieu of validation of fission products and minor actinides in MCNP K eff calculations for PWR burnup credit casks

    SciTech Connect

    Mueller, Don E.; Marshall, William J.; Wagner, John C.

    2015-09-01

    The U.S. Nuclear Regulatory Commission (NRC) Division of Spent Fuel Storage and Transportation recently issued Interim Staff Guidance (ISG) 8, Revision 3. This ISG provides guidance for burnup credit (BUC) analyses supporting transport and storage of PWR pressurized water reactor (PWR) fuel in casks. Revision 3 includes guidance for addressing validation of criticality (k eff) calculations crediting the presence of a limited set of fission products and minor actinides (FP&MA). Based on previous work documented in NUREG/CR-7109, recommendation 4 of ISG-8, Rev. 3, includes a recommendation to use 1.5 or 3% of the FP&MA worth to conservatively cover the biasmore » due to the specified FP&MAs. This bias is supplementary to the bias and bias uncertainty resulting from validation of k eff calculations for the major actinides in SNF and does not address extension to actinides and fission products beyond those identified herein. The work described in this report involves comparison of FP&MA worths calculated using SCALE and MCNP with ENDF/B-V, -VI, and -VII based nuclear data and supports use of the 1.5% FP&MA worth bias when either SCALE or MCNP codes are used for criticality calculations, provided the other conditions of the recommendation 4 are met. The method used in this report may also be applied to demonstrate the applicability of the 1.5% FP&MA worth bias to other codes using ENDF/B V, VI or VII based nuclear data. The method involves use of the applicant s computational method to generate FP&MA worths for a reference SNF cask model using specified spent fuel compositions. The applicant s FP&MA worths are then compared to reference values provided in this report. The applicants FP&MA worths should not exceed the reference results by more than 1.5% of the reference FP&MA worths.« less

  18. An approach to design a 90Sr radioisotope thermoelectric generator using analytical and Monte Carlo methods with ANSYS, COMSOL, and MCNP.

    PubMed

    Khajepour, Abolhasan; Rahmani, Faezeh

    2017-01-01

    In this study, a 90 Sr radioisotope thermoelectric generator (RTG) with power of milliWatt was designed to operate in the determined temperature (300-312K). For this purpose, the combination of analytical and Monte Carlo methods with ANSYS and COMSOL software as well as the MCNP code was used. This designed RTG contains 90 Sr as a radioisotope heat source (RHS) and 127 coupled thermoelectric modules (TEMs) based on bismuth telluride. Kapton (2.45mm in thickness) and Cryotherm sheets (0.78mm in thickness) were selected as the thermal insulators of the RHS, as well as a stainless steel container was used as a generator chamber. The initial design of the RHS geometry was performed according to the amount of radioactive material (strontium titanate) as well as the heat transfer calculations and mechanical strength considerations. According to the Monte Carlo simulation performed by the MCNP code, approximately 0.35 kCi of 90 Sr is sufficient to generate heat power in the RHS. To determine the optimal design of the RTG, the distribution of temperature as well as the dissipated heat and input power to the module were calculated in different parts of the generator using the ANSYS software. Output voltage according to temperature distribution on TEM was calculated using COMSOL. Optimization of the dimension of the RHS and heat insulator was performed to adapt the average temperature of the hot plate of TEM to the determined hot temperature value. This designed RTG generates 8mW in power with an efficiency of 1%. This proposed approach of combination method can be used for the precise design of various types of RTGs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Research Developments in Li-Paczyński Novae (II): Observational Aspect

    NASA Astrophysics Data System (ADS)

    Shan-qin, Wang; Zi-gao, Dai; Xue-feng, Wu

    2016-10-01

    Since the LP-Nova models were proposed, and the short gamma-ray burst (SGRB) afterglows were confirmed, people have actively made searches for the evidence of the existence of LP-Novae among the optical (or near-infrared) counterparts of SGRBs. In this paper, we first summarize these observational progresses before 2012 in Section 2. In Section 3 and 4, we respectively introduce the basic properties of GRBs 130603B and 060614, as well as the theoretical interpretation for their near-infrared (NIR) counterparts, and their NIR excess may be the signature of the existence of LP-Novae. In Section 5, we describe the basic properties of GRB 080503, and the theoretical interpretation for its optical and X-ray counterparts, and the later re-brightening of its optical and X-ray light curves is explained as the ejecta radiation (merger-nova radiation) of magnetar heating after the neutron star merging. If the interpretations for the SGRB-associated optical and infrared counterparts are correct, they may provide the first series of direct evidence to show that SGRBs and some special LGRBs are originated from the compact star mergers. Besides LP-novae (and merger-novae), the high-speed orbital motion before the compact star merging and the merger itself will produce strong gravitational-wave bursts (GWBs). In the coming era of gravitational wave detection, the theoretical and observational studies on the electromagnetic counterparts of compact star mergers will receive more and more attentions. Due to the larger uncertainty of GWB's location, the LP-Novae associated with GWBs can serve as the best candidates for the precise location of GWBs. The fast developing high-cadence and wide-field optical-NIR surveys will make effective explorations on the LP-Novae and similar phenomena, and interact the detection and research of gravitational waves. Therefore, in the last section we present the methods for the future detections of LP-Novae, and the prospect of their multi

  20. Synthetic Spectral Analysis of the Far Ultraviolet Spectra of the Old Nova HR Del

    NASA Astrophysics Data System (ADS)

    Robertson, Jordan; Sion, E.

    2012-05-01

    We present a synthetic spectral analysis of the archival IUE far ultraviolet spectra of the post-nova, HR Del (Nova Del 1967). The system has an estimated white dwarf mass of 0.55 Msun (Ritter and Kolb 2003), orbital period P_orb = 0.214165 days, estimated orbital inclination of 40 degrees (Keurster 1988) and distance determinations in the literature ranging from 970 pc to 285 pc. The spectra reveal P Cygni profiles indicative of wind outflow from the disk and closely resemble the IUE spectra of UX UMa nova-likes, which have never had recorded outbursts. We de-reddened the archival IUE spectra using E(B-V) = 0.16. Our synthetic spectral analysis utilized optically thick, steady state accretion disk models and white dwarf model atmospheres that we constructed using TLUSTY and SYNSPEC (Hubeny 1988, Hubeny and Lanz (1995). Our input parameters were the white dwarf mass, inclination and a range of accretion rates for which we found the best-fitting model. We report the results of our model fitting and compare HR Del with other post-novae at comparable times past their nova outburst. This work was supported by NSF grant 0807892 to Villanova University

  1. Searching for Magnetar-powered Merger-novae from Short GRBS

    NASA Astrophysics Data System (ADS)

    Gao, He; Zhang, Bing; Lü, Hou-Jun; Li, Ye

    2017-03-01

    The merger of a double neutron star (NS-NS) binary may result in a rapidly rotating massive NS with an extremely strong magnetic field (I.e., a millisecond magnetar). In this case, the magnetic spin-down of the NS remnant provides an additional source of sustained energy injection, which would continuously power the merger ejecta. The thermal emission from the merger ejecta would give rise to a bright optical “magnetar-powered merger-nova.” In this work, we carry out a complete search for magnetar-powered merger-nova from a Swift short gamma-ray burst sample. We focus on short GRBs with extended emission or internal plateau, which may signify the presence of magnetars as the central engine. We eventually find three candidates of magnetar-powered merger-nova from the late observations of GRB 050724, GRB 070714B, and GRB 061006. With standard parameter values, the magnetar remnant scenario could well interpret the multi-band data of all three bursts, including the extended emission and their late chromatic features in the optical and X-ray data. The peak luminosities of these merger-novae reach several times {10}42 {erg} {{{s}}}-1, more than one order of magnitude brighter than the traditional “kilo-novae” with peak luminosity of ˜ {10}41 {erg} {{{s}}}-1. Intense, multi-color, late-time observations of short GRBs are encouraged to identify more merger-novae in the future.

  2. SIMULATIONS OF THE SYMBIOTIC RECURRENT NOVA V407 CYG. I. ACCRETION AND SHOCK EVOLUTIONS

    SciTech Connect

    Pan, Kuo-Chuan; Ricker, Paul M.; Taam, Ronald E., E-mail: kuo-chuan.pan@unibas.ch, E-mail: pmricker@illinois.edu, E-mail: r-taam@northwestern.edu, E-mail: taam@asiaa.sinica.edu.tw

    2015-06-10

    The shock interaction and evolution of nova ejecta with wind from a red giant (RG) star in a symbiotic binary system are investigated via three-dimensional hydrodynamics simulations. We specifically model the 2010 March outburst of the symbiotic recurrent nova V407 Cygni from its quiescent phase to its eruption phase. The circumstellar density enhancement due to wind–white-dwarf interaction is studied in detail. It is found that the density-enhancement efficiency depends on the ratio of the orbital speed to the RG wind speed. Unlike another recurrent nova, RS Ophiuchi, we do not observe a strong disk-like density enhancement, but instead observe anmore » aspherical density distribution with ∼20% higher density in the equatorial plane than at the poles. To model the 2010 outburst, we consider several physical parameters, including the RG mass-loss rate, nova eruption energy, and ejecta mass. A detailed study of the shock interaction and evolution reveals that the interaction of shocks with the RG wind generates strong Rayleigh–Taylor instabilities. In addition, the presence of the companion and circumstellar density enhancement greatly alter the shock evolution during the nova phase. Depending on the model, the ejecta speed after sweeping out most of the circumstellar medium decreases to ∼100–300 km s{sup −1}, which is consistent with the observed extended redward emission in [N ii] lines in 2011 April.« less

  3. M31N 2008-12a: The Remarkable Recurrent Nova in the Andromeda Galaxy

    NASA Astrophysics Data System (ADS)

    Shafter, Allen W.; Darnley, Matthew; Henze, Martin; Williams, Steven C.

    2017-08-01

    The recurrent nova M31N 2008-12a in M31 has the shortest interoutburst time of any known recurrent nova. Since its discovery in December 2008 by two Japanese amateur astronomers, Koichi Nishiyama and Fujio Kabashima, a total of 8 subsequent outbursts have been observed. The mean time between observed eruptions (all observed between late August and December) is 364+/-52 days. M31 is close to the sun in March through May, so it is likely that any eruptions that may have occurred during this period have been missed and the recurrence period could be as short as 6 months. Models of thermonuclear runaways on white dwarfs show that only near Chandrasekhar mass white dwarfs accreting at a few times 10-7 solar masses per year can produce nova outbursts with a recurrence time of a year, or less. Furthermore, the models show that during the interval between each nova event the accreted mass is expected to be greater than the expelled mass. The white dwarf mass must therefore be growing, and is predicted to reach the Chandrasekhar mass in of order 500,000 years. Thus, M31N 2008-12a is destined either to become a Type Ia supernova (if the white dwarf has a CO composition) or to form a neutron star in an accretion-induced collapse (if the white dwarf has an ONe composition). In this poster, I will describe the latest observations of this fascinating nova.

  4. PRESOLAR GRAINS FROM NOVAE: EVIDENCE FROM NEON AND HELIUM ISOTOPES IN COMET DUST COLLECTIONS

    SciTech Connect

    Pepin, Robert O.; Palma, Russell L.; Gehrz, Robert D.

    2011-12-01

    Presolar grains in meteorites and interplanetary dust particles carry non-solar isotopic signatures pointing to origins in supernovae, giant stars, and possibly other stellar sources. There have been suggestions that some of these grains condensed in the ejecta of classical nova outbursts, but the evidence is ambiguous. We report neon and helium compositions in particles captured on stratospheric collectors flown to sample materials from comets 26P/Grigg-Skjellerup and 55P/Tempel-Tuttle that point to condensation of their gas carriers in the ejecta of a neon (ONe) nova. The absence of detectable {sup 3}He in these particles indicates space exposure to solar wind irradiation ofmore » a few decades at most, consistent with origins in cometary dust streams. Measured {sup 4}He/{sup 20}Ne, {sup 20}Ne/{sup 22}Ne, {sup 21}Ne/{sup 22}Ne, and {sup 20}Ne/{sup 21}Ne isotope ratios, and a low upper limit on {sup 3}He/{sup 4}He, are in accord with calculations of nucleosynthesis in neon nova outbursts. Of these, the uniquely low {sup 4}He/{sup 20}Ne and high {sup 20}Ne/{sup 22}Ne ratios are the most diagnostic, reflecting the large predicted {sup 20}Ne abundances in the ejecta of such novae. The correspondence of measured Ne and He compositions in cometary matter with theoretical predictions is evidence for the presence of presolar grains from novae in the early solar system.« less

  5. Ultraviolet Flashers in M87: Rapidly Recurring Novae as SNIa Progenitors

    NASA Astrophysics Data System (ADS)

    Shara, Michael

    2016-10-01

    The recent discovery of a recurrent nova erupting every six months in M31, and simultaneous development of a consistent theoretical/numerical model for growing white dwarfs (WDs) to the Chandrasekhar limit, points the way to locating UV-bright SNIa progenitors in galaxies. We propose to monitor M87 with a cadence of 5 days over a 9 month-long span to 1) detect all the NUV-bright, near-Chandrasekhar mass WDs accreting at high enough rates to become SNIa in the next 200,000 years; 2) determine their eruption frequency distribution, which is diagnostic of the underlying white dwarf accretion rates; 3) test nova modelers' prediction that recurrent novae can never erupt more frequently that once in 45 days; 4) definitively determine the rate Rnova of nova eruptions in M87; 5) confront population synthesis models predictions of Rnova with our observationally determined value; and 6) check the claim (observed in M31) that 20-41% of all nova WDs have red giant secondaries. A free bonus of these observations will be the deepest-ever NUV image of the M87 jet, and the highest cadence ever sequence of images of the jet, which includes knots mysteriously varying in brightness by up to 5 magnitudes.

  6. Modelling sea ice formation in the Terra Nova Bay polynya

    NASA Astrophysics Data System (ADS)

    Sansiviero, M.; Morales Maqueda, M. Á.; Fusco, G.; Aulicino, G.; Flocco, D.; Budillon, G.

    2017-02-01

    Antarctic sea ice is constantly exported from the shore by strong near surface winds that open leads and large polynyas in the pack ice. The latter, known as wind-driven polynyas, are responsible for significant water mass modification due to the high salt flux into the ocean associated with enhanced ice growth. In this article, we focus on the wind-driven Terra Nova Bay (TNB) polynya, in the western Ross Sea. Brine rejected during sea ice formation processes that occur in the TNB polynya densifies the water column leading to the formation of the most characteristic water mass of the Ross Sea, the High Salinity Shelf Water (HSSW). This water mass, in turn, takes part in the formation of Antarctic Bottom Water (AABW), the densest water mass of the world ocean, which plays a major role in the global meridional overturning circulation, thus affecting the global climate system. A simple coupled sea ice-ocean model has been developed to simulate the seasonal cycle of sea ice formation and export within a polynya. The sea ice model accounts for both thermal and mechanical ice processes. The oceanic circulation is described by a one-and-a-half layer, reduced gravity model. The domain resolution is 1 km × 1 km, which is sufficient to represent the salient features of the coastline geometry, notably the Drygalski Ice Tongue. The model is forced by a combination of Era Interim reanalysis and in-situ data from automatic weather stations, and also by a climatological oceanic dataset developed from in situ hydrographic observations. The sensitivity of the polynya to the atmospheric forcing is well reproduced by the model when atmospheric in situ measurements are combined with reanalysis data. Merging the two datasets allows us to capture in detail the strength and the spatial distribution of the katabatic winds that often drive the opening of the polynya. The model resolves fairly accurately the sea ice drift and sea ice production rates in the TNB polynya, leading to

  7. [A physician demand and supply forecast model for Nova Scotia].

    PubMed

    Basu, Kisalaya; Gupta, Anil

    2005-01-01

    There is well-founded concern about the current and future availability of Health Human Resources (HHR). Demographic trends are magnifying this concern -- an ageing population will require more medical interventions at a time when the HHR workforce itself is ageing. The lengthy and costly training period for most health care workers, especially physicians, poses a real challenge that requires planning these activities well in advance. Hence, there is definite need for a good HHR forecasting model. To present a physician forecasting model that projects the Full-Time Equivalent (FTE) demand for and supply of physicians in Nova Scotia to the year 2020 for three specialties: general practitioners, medical, and surgical. The model enables gap analysis and assessment of alternative policy options designed to close the gaps. The methodology for estimating demand fo physician services involves three steps: (i) Establishing the FT for each physician. To this end we calculate the income of each physician using Physician Billings Data and then identify the 40th and 60th percentile income levels for each of the 40 specialties. The income levels are then used to calculate the FTE using a formula developed at Health Canada; (ii) Calculating the FTE for each service by distributing the FTE of each physician at the service level (i.e., by patient age, sex, most responsible diagnosis, and hospital status group); and (iii) Using Statistics Canada's population projections to project future demand for three broad medical disciplines: general practitioners, medical specialist, and surgical specialists. The supply side of the model employs a stock/flow approach and exploits time-series and other data for variables, such as emigration, international medical graduates (IMGs), medical school entrants, retirements, mortality, and so on, which in turn allow us to access a host of policy parameters. Under the status quo assumption, demand for physician services will outstrip the growth in

  8. The Convolutional Visual Network for Identification and Reconstruction of NOvA Events

    SciTech Connect

    Psihas, Fernanda

    2017-11-22

    In 2016 the NOvA experiment released results for the observation of oscillations in the vμ and ve channels as well as ve cross section measurements using neutrinos from Fermilab’s NuMI beam. These and other measurements in progress rely on the accurate identification and reconstruction of the neutrino flavor and energy recorded by our detectors. This presentation describes the first application of convolutional neural network technology for event identification and reconstruction in particle detectors like NOvA. The Convolutional Visual Network (CVN) Algorithm was developed for identification, categorization, and reconstruction of NOvA events. It increased the selection efficiency of the ve appearancemore » signal by 40% and studies show potential impact to the vμ disappearance analysis.« less

  9. A randomized trial of three copper IUDs (MLCu250, MLCu375 and Nova-T).

    PubMed

    Bratt, H; Skjeldestad, F E; Cullberg Valentin, K

    1988-01-01

    A randomized prospective trial of three copper IUDs, Nova-T, MLCu375 and MLCu250, including 200 of each, is presented. Insertion was done at the hospital outpatient clinic on normally menstruating women and on women in puerperio. Follow-up was scheduled after 12, 24 and 36 months. Pregnancy rates were low for all 3 models. Pearl indices after 3 years were 0.5, 0.9 and 0.8 for Nova-T, MLCu375 and MLCu250 respectively (NS). Abnormal bleeding and/or pain was the most frequent termination cause. Minor differences in the termination rates because of abnormal bleeding and/or pain were found and are discussed. The continuation rates based on all medically relevant IUD removals were 74%, 73% and 81% after 3 years for Nova-T, MLCu375 and MLCu250 respectively. No important difference in clinical performance between the three copper IUDs could be demonstrated.

  10. SOFIA Target of Opportunity (ToO) Observations of Bright Classical Novae in Outburst

    NASA Astrophysics Data System (ADS)

    Gehrz, Robert

    2013-10-01

    Galactic classical novae (CNe) contribute to Galactic chemical evolution by injecting dust grains and gases into the interstellar medium (ISM). We have been selected for SOFIA Cycle 1 FORCAST and FLITECAM Target of Opportunity (ToO) grism observations of the temporal development of bright CNe. Here, we propose to extend our program into Cycle 2 to cover the continued temporal development of bright CNe that go into outburst during Cycle 1 and to initiate temporal coverage of bright CNe that go into outburst during Cycle 2. The proposed observations can determine critical physical parameters that characterize the explosion and the effect of CNe on ISM abundances. In particular, our observations will yield the mass ejected, the mineralogy and abundance of the dust grains, and gas phase abundances of CNONeMgAl metals in the ejecta. The 5 to 37 micron spectral range of FORCAST grisms enables complete and simultaneous access to the many dust and gas emission features that must be examined to derive these parameters. Supplemental FLITECAM observations of a dusty ToO nova are requested to assess the hydrocarbon component of nova dust. Any new nova brighter than 8th magnitude at visual maximum can trigger our ToO program when supporting optical/IR ground-based observations indicate that the nova is in 1) a dust formation and growth phase, 2) a coronal emission development phase, or 3) the early free-free expansion phase. The timescales for SOFIA ToO follow-up observations for a nova that triggers our ToO program can range from weeks, months, and years for cases 1) and 2), to days and weeks for case 3).

  11. SOFIA Target of Opportunity (ToO) Observations of Bright Classical Novae in Outburst

    NASA Astrophysics Data System (ADS)

    Gehrz, Robert

    2012-10-01

    Galactic classical nova (CN) explosions inject dust grains and gases into the interstellar medium (ISM). We propose SOFIA FORCAST Target of Opportunity (ToO) grism observations of the temporal development of bright classical novae (CNe) that can be used to determine critical physical paramters that characterize the explosion and the extent to which CNe ejecta affect ISM abundances on both local and global scales. The proposed observations of CNe discovered during SOFIA Cycle 1 will yield the mass ejected, the mineralogy and abundance of the dust condensed in the ejecta, and gas phase abundances of CNONeMgAl metals in the ejecta. The 5 to 37 micron spectral range to FORCAST will enable complete and simultaneous access to many dust and gas emission features that must be examined to derive these parameters. Supplemental FLITECAM observations of a dusty ToO nova are requested to assess the organic component of nova dust. Any new nova brighter that 8th magnitude at visual maximum can trigger our ToO program when supporting optical/IR ground-based observations from the observatories for which we have guaranteed observing time (Steward Observatory, University of Minnesota O'Brien Observatory and Mt. Lemmon Observing Facility) indicate that the nova is in 1) a dust formation and growth phase, 2) a coronal emission development phase, or 3) the early free-free expansion phase. The timescales for SOFIA ToO observations following a trigger point range from weeks and months for cases 1) and 2), to days and weeks for case 3).

  12. SOFIA Target of Opportunity (ToO) Observations of Bright Classical Novae in Outburst

    NASA Astrophysics Data System (ADS)

    Gehrz, Robert

    2014-10-01

    Galactic classical novae (CNe) contribute to Galactic chemical evolution by injecting dust grains and gases into the interstellar medium (ISM). We were awarded time for SOFIA Cycle 1 and 2 FORCAST and FLITECAM Target of Opportunity (ToO) grism observations of the temporal development of bright CNe. Here, we propose to extend our program into Cycle 3 to cover the continued development of CNe that became active during Cycle 2 and to initiate coverage of CNe that go into outburst during Cycle 3. The proposed observations can determine critical physical parameters that characterize the explosion and the effect of CNe on ISM abundances. In particular, our observations will yield the mass ejected, the mineralogy and abundance of the dust grains, and gas phase abundances of CNONeMgAl metals in the ejecta. The 5 to 37 micron spectral range of FORCAST grisms enables complete and simultaneous access to the many dust and gas emission features that must be examined to derive these parameters. Supplemental FLITECAM observations of a dusty ToO nova are requested to assess the hydrocarbon component of nova dust. Any new nova brighter than 8th magnitude at visual maximum can trigger our ToO program when supporting optical/IR ground-based observations indicate that the nova is in 1) a dust formation and growth phase, 2) a coronal emission development phase, or 3) the early free-free expansion phase. The timescales for SOFIA ToO follow-up observations for a nova that triggers our ToO program can range from weeks, months, and years for cases 1) and 2), to days and weeks for case 3).

  13. Multiwavelength observations of the 2015 nova in the Local Group irregular dwarf galaxy IC 1613

    NASA Astrophysics Data System (ADS)

    Williams, S. C.; Darnley, M. J.; Henze, M.

    2017-12-01

    A nova in the Local Group irregular dwarf galaxy IC 1613 was discovered on 2015 September 10 and is the first nova in that galaxy to be spectroscopically confirmed. We conducted a detailed multiwavelength observing campaign of the eruption with the Liverpool Telescope, the LCO 2 m telescope at Siding Spring Observatory, and Swift, the results of which we present here. The nova peaked at MV = -7.93 ± 0.08 and was fast-fading, with decline times of t2(V) = 13 ± 2 and t3(V) = 26 ± 2 d. The overall light-curve decline was relatively smooth, as often seen in fast-fading novae. Swift observations spanned 40-332 d post-discovery, but no X-ray source was detected. Optical spectra show the nova to be a member of the hybrid spectroscopic class, simultaneously showing Fe II and N II lines of similar strength during the early decline phase. The spectra cover the eruption from the early optically thick phase, through the early decline and into the nebular phase. The Hγ absorption minimum from the optically thick spectrum indicates an expansion velocity of 1200 ± 200 km s-1. The full width at half-maximum of the Hα emission line between 10.54 and 57.51 d post-discovery shows no significant evolution and remains at ∼1750 km s-1, although the morphology of this line does show some evolution. The nova appears close to a faint stellar source in archival imaging; however, we find the most likely explanation for this is simply a chance alignment.

  14. X-Ray Study of Rekindled Accretion in the Classical Nova V2491 Cygni

    NASA Astrophysics Data System (ADS)

    Takei, Dai; Ness, Jan-Uwe; Tsujimoto, Masahiro; Kitamoto, Shunji; Drake, Jeremy J.; Osborne, Julian P.; Takahashi, Hiromitsu; Kinugasa, Kenzo

    2011-11-01

    We conducted an X-ray spectroscopic study of the classical nova V2491 Cygni using our target-of-opportunity observation data with the Suzaku and XMM-Newton satellites as well as archived data with the Swift satellite. Medium-resolution (R ˜ 10-50) spectra were obtained using the X-ray CCD spectrometers at several post-nova epochs on days 9, 29, 40, 50, and 60-150 in addition to a pre-nova interval between days -322 and ->100, all relative to the time when the classical nova was spotted. We found remarkable changes in the time series of the spectra: (a) In the pre-nova phase and on day 9, the 6.7 keV emission line from Fe XXV was significantly detected. (b) On day 29, no such emission line was found. (c) On day 40, the 6.7 keV emission line emerged again. (d) On days 50 and 60-150, three emission lines at 6.4, 6.7, and 7.0 keV, respectively, from quasi-neutral Fe, Fe XXV, and Fe XXVI were found. Statistically significant changes of the Fe K line intensities were confirmed between days 29 and 50. Based on these phenomena, we conclude that: (1) the post-nova evolution can be divided into two different phases, (2) ejecta is responsible for the X-ray emission in the earlier phase, while rekindled accretion is responsible for the later phase, and (3) the accretion process is considered to be reestablished as early as day 50 when the quasi-neutral Fe emission line emerged, which is a common signature of accretion from magnetic cataclysmic variables.

  15. Fermi-LAT Gamma-ray Observations of Nova Lupus 2016 (ASASSN-16kt)

    NASA Astrophysics Data System (ADS)

    Cheung, C. C.; Jean, P.; Shore, S. N.; Fermi Large Area Telescope Collaboration

    2016-10-01

    The Fermi Gamma-ray Space Telescope performed a ~6-day Target of Opportunity (ToO) observation of Nova Lupus 2016 (ATel #9538, #9539, CBET #4322) that commenced on September 28. Considering earlier all-sky survey Large Area Telescope (LAT) observations as well, preliminary analysis indicates gamma-ray emission at ~2 sigma was detected around 1 to 2 days after the optical peak on September 25th (pre-validated AAVSO visual lightcurve; ATel #9550, CBET #4322) when the optical spectra show opaque ejecta, similar to previous gamma-ray detected novae (Fermi-LAT collaboration, 2014 Science 345, 554; Cheung et al. 2016 ApJ 826, 142).

  16. Johannes Kepler and David Fabricius: Their Discussion on the Nova of 1604

    NASA Astrophysics Data System (ADS)

    Granada, Miguel A.

    David Fabricius (1564-1617) was one of the most important astronomers in the period between 1596, the year of publication of Kepler's Mysterium cosmographicum, and 1609, the year of publication of the Astronomia nova.1 Kepler praised Fabricius as the most accurate observational astronomer after Tycho Brahe's death in 1601.2 Fabricius was a Reformed pastor in Ostfriesland (East Frisia), his remote natal region, and a vocational astronomer. He published nothing in the field of astronomy except for the short treatises between 1604 and 1606 concerning the nova that appeared in October 1604 in Serpentarius.

  17. Constraints on oscillation parameters from v e appearance and v μ disappearance in NOvA

    DOE PAGES

    Adamson, P.; Aliaga, L.; Ambrose, D.; ...

    2017-06-05

    Results are reported from an improved measurement of ν μ → ν e transitions by the NOvA experiment. Using an exposure equivalent to 6.05 × 10 20 protons on target, 33 νe candidates are observed with a background of 8.2 ± 0.8 (syst.). In this paper, combined with the latest NOvA νμ disappearance data and external constraints from reactor experiments on sin 22θ 13, the hypothesis of inverted mass hierarchy with θ 23 in the lower octant is disfavored at greater than 93% C.L. for all values of δ CP.

  18. The White Dwarf Mass and the Accretion Rate of Recurrent Novae: An X-ray Perspective

    NASA Technical Reports Server (NTRS)

    Mukai, Koji; Sokoloski, Jennifer L.; Nelson, Thomas; Luna, Gerardo J. M.

    2011-01-01

    We present recent results of quiescent X-ray observations of recurrent novae (RNe) and related objects. Several RNe are luminous hard X-ray sources in quiescence, consistent with accretion onto a near Chandrasekhar mass white dwarf. Detection of similar hard X-ray emissions in old novae and other cataclysmic variables may lead to identification of additional RN candidates. On the other hand, other RNe are found to be comparatively hard X-ray faint. We present several scenarios that may explain this dichotomy, which should be explored further.

  19. CK Vul: a smorgasbord of hydrocarbons rules out a 1670 nova (and much else besides)

    NASA Astrophysics Data System (ADS)

    Evans, A.; Gehrz, R. D.; Woodward, C. E.; Sarre, P. J.; van Loon, J. T.; Helton, L. A.; Starrfield, S.; Eyres, S. P. S.

    2016-04-01

    We present observations of CK Vul obtained with the Spitzer Space Telescope. The infrared spectrum reveals a warm dust continuum with nebular, molecular hydrogen and HCN lines superimposed, together with the `Unidentified Infrared' features. The nebular lines are consistent with emission by a low-density gas. We conclude that the Spitzer data, combined with other information, are incompatible with CK Vul being a classical nova remnant in `hibernation' after the event of 1670, a `very late thermal pulse', a `Luminous Red Variable', such as V838 Mon, or a `diffusion-induced nova'. The true nature of CK Vul remains a mystery.

  20. The electrification of Nova Scotia, 1884--1973: Technological modernization as a response to regional disparity

    NASA Astrophysics Data System (ADS)

    King, Lionel Bradley

    This dissertation investigates local attempts to use technology as a force for regional rehabilitation in the economically-depressed Maritime region of Canada. At the time of Confederation in 1867, the Maritime province of Nova Scotia was prosperous, progressive, and cultured. By the end of the 1910s, the province had entered a long period of economic and social decline. Recent historiography has shown that, far from passively accepting their fate, Nova Scotians and other Maritimers, actively resisted marginalization with political, cultural, or social action. The thesis expands upon that literature by exploring technology-based strategies of provincial rehabilitation using Thomas P. Hughes's systems perspective and David E. Nye's semiotic approach. In doing so, it applies methods from the social constructivist school of the history of technology to the larger concerns of Maritime Canadian historiography. In large part, the North American culture of technology determined the ways in which Nova Scotians applied technological solutions to provincial concerns. Technology has long been central to the Western idea of progress. As the "high technology" of the late nineteenth and early twentieth centuries, electricity reinforced that view: its ephemeral nature and silent efficiency led people to endow it with transformative, even mystical, powers. As a result, Nova Scotians, adopted a program of electrical modernization in the late 1910s as a remedy for regional disparity. The Nova Scotia government's first step was the creation of an Ontario-style hydroelectric commission designed to bring order to the province's fragmented and inefficient electrical network. Over the next few decades, the Nova Scotia Power Commission implemented rural electrification, home modernization, and regional system-building models that had already proven successful in Ontario and the United States. The system-building philosophies behind these programs were adapted to local conditions and

  1. EXQUISITE NOVA LIGHT CURVES FROM THE SOLAR MASS EJECTION IMAGER (SMEI)

    SciTech Connect

    Hounsell, R.; Bode, M. F.; Darnley, M. J.

    2010-11-20

    We present light curves of three classical novae (CNe; KT Eridani, V598 Puppis, V1280 Scorpii) and one recurrent nova (RS Ophiuchi) derived from data obtained by the Solar Mass Ejection Imager (SMEI) on board the Coriolis satellite. SMEI provides near complete skymap coverage with precision visible-light photometry at 102 minute cadence. The light curves derived from these skymaps offer unprecedented temporal resolution around, and especially before, maximum light, a phase of the eruption normally not covered by ground-based observations. They allow us to explore fundamental parameters of individual objects including the epoch of the initial explosion, the reality and durationmore » of any pre-maximum halt (found in all three fast novae in our sample), the presence of secondary maxima, speed of decline of the initial light curve, plus precise timing of the onset of dust formation (in V1280 Sco) leading to estimation of the bolometric luminosity, white dwarf mass, and object distance. For KT Eri, Liverpool Telescope SkyCamT data confirm important features of the SMEI light curve and overall our results add weight to the proposed similarities of this object to recurrent rather than to CNe. In RS Oph, comparison with hard X-ray data from the 2006 outburst implies that the onset of the outburst coincides with extensive high-velocity mass loss. It is also noted that two of the four novae we have detected (V598 Pup and KT Eri) were only discovered by ground-based observers weeks or months after maximum light, yet these novae reached peak magnitudes of 3.46 and 5.42, respectively. This emphasizes the fact that many bright novae per year are still overlooked, particularly those of the very fast speed class. Coupled with its ability to observe novae in detail even when relatively close to the Sun in the sky, we estimate that as many as five novae per year may be detectable by SMEI.« less

  2. Ultraviolet photometry of Nova Cygni 1992 obtained with the high speed photometer

    NASA Technical Reports Server (NTRS)

    Taylor, M.; Bless, R. C.; Oegelman, H.; Elliot, J. L.; Gallagher, J. S.; Nelson, M. J.; Percival, J. W.; Robinson, E. L.; Van Citters, G. W.

    1994-01-01

    In this Letter we present the first high-speed ultraviolet photometry of an active, classical nova, Nova Cygni 1992. The 45 minute observation shows significant evidence for power at frequencies that correspond to periods of about 565 and 900 s. Each of these periods has an amplitude of about 3 mmag. Since this data set is short, we cannot establish the nature of the detected variability and so, we discuss possible physical mechanisms ranging from short-lived phenomena to stable periodic modulations that could result in the observed variations.

  3. ASASSN-18ca: Discovery of A Probable Nova in M31

    NASA Astrophysics Data System (ADS)

    Brimacombe, J.; Vallely, P.; Stanek, K. Z.; Kochanek, C. S.; Brown, J. S.; Shields, J.; Thompson, T. A.; Shappee, B. J.; Holoien, T. W.-S.; Prieto, J. L.; Bersier, D.; Dong, Subo; Bose, S.; Chen, Ping; Stritzinger, M.; Holmbo, S.

    2018-02-01

    During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"), using data from the quadruple 14-cm "Leavitt" telescope in Fort Davis, Texas, we discovered a new transient source, most likely a nova, in the nearby galaxy M31. ASASSN-18ca (AT 2018pp) was discovered in images obtained on UT 2018-02-08.07 at g 16.5 mag. We do not detect (g > 18.6) the object in images taken on UT 2018-02-06.12 and before.

  4. Spatio-temporal analysis of Nova virus, a divergent hantavirus circulating in the European mole in Belgium.

    PubMed

    Laenen, Lies; Dellicour, Simon; Vergote, Valentijn; Nauwelaers, Inne; De Coster, Sarah; Verbeeck, Ina; Vanmechelen, Bert; Lemey, Philippe; Maes, Piet

    2016-12-01

    Over the last decade, the recognized host range of hantaviruses has expanded considerably with the discovery of distinct hantaviruses in shrews, moles and bats. Unfortunately, in-depth studies of these viruses have been limited. Here we describe a comprehensive analysis of the spatial distribution, genetic diversity and evolution of Nova virus, a hantavirus that has the European mole as its natural host. Our analysis demonstrated that Nova virus has a high prevalence and widespread distribution in Belgium. While Nova virus displayed relatively high nucleotide diversity in Belgium, amino acid changes were limited. The nucleocapsid protein was subjected to strong purifying selection, reflecting the strict evolutionary constraints placed upon Nova virus by its host. Spatio-temporal analysis using Bayesian evolutionary inference techniques demonstrated that Nova virus had efficiently spread in the European mole population in Belgium, forming two distinct clades, representing east and west of Belgium. The influence of landscape barriers, in the form of the main waterways, on the dispersal velocity of Nova virus was assessed using an analytical framework for comparing Bayesian viral phylogenies with environmental landscape data. We demonstrated that waterways did not act as an environmental resistance factor slowing down Nova virus diffusion in the mole population. With this study, we provide information about the spatial diffusion of Nova virus and contribute sequence information that can be applied in further functional studies. © 2016 John Wiley & Sons Ltd.

  5. ASAS-SN Discovery of A Likely Galactic Nova ASASSN-16kt at V=9.1

    NASA Astrophysics Data System (ADS)

    Stanek, K. Z.; Kochanek, C. S.; Brown, J. S.; Holoien, T. W.-S.; Shields, J.; Shappee, B. J.; Prieto, J. L.; Bersier, D.; Dong, Subo; Bose, S.; Chen, Ping; Chomiuk, L.; Strader, J.; Brimacombe, J.

    2016-09-01

    During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"), using data from the quadruple 14-cm "Cassius" telescope in CTIO, Chile, we detect a new, very bright transient source, most likely a classical nova, fairly close to the the Galactic plane Object RA (J2000) DEC (J2000) Gal l (deg) Gal b (deg) Disc.

  6. NovaNET 2008-09 Evaluation. Impact Evaluation. E&R Report No. 09.36

    ERIC Educational Resources Information Center

    Bulgakov-Cook, Dina

    2010-01-01

    NovaNET is a technology-based teacher-facilitated educational approach used at schools to support students at risk of not meeting graduation requirements to accrue credits in a variety of subjects. NovaNET contributes to the WCPSS goal of closing achievement gaps and creating opportunities for all students to graduate on time. In 2008-09, 38…

  7. 78 FR 7850 - Notice of Availability of Finding of No Significant Impact for the Proposed NOVA Chemicals Inc...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-04

    ... Facility would not have a significant impact on the quality of the human environment. The Finding of No... Impact for the Proposed NOVA Chemicals Inc. Line 20 Facility Conversion Project SUMMARY: The purpose of... Significant Impact on the proposed NOVA Chemicals Inc. Line 20 Facilities Conversion Project. Under E.O. 13337...

  8. Supersoft X-rays reveal a classical nova in the M 31 globular cluster Bol 126

    NASA Astrophysics Data System (ADS)

    Henze, M.; Pietsch, W.; Haberl, F.; Della Valle, M.; Riffeser, A.; Sala, G.; Hatzidimitriou, D.; Hofmann, F.; Hartmann, D. H.; Koppenhoefer, J.; Seitz, S.; Williams, G. G.; Hornoch, K.; Itagaki, K.; Kabashima, F.; Nishiyama, K.; Xing, G.; Lee, C. H.; Magnier, E.; Chambers, K.

    2013-01-01

    Context. Classical novae (CNe) represent the main class of supersoft X-ray sources (SSSs) in the central region of our neighbouring galaxy M 31. Only three confirmed novae and three SSSs have been discovered in globular clusters (GCs) of any galaxy so far, of which one nova and two SSSs (including the nova) were found in M 31 GCs. Aims: To study the SSS state of CNe we carried out a high-cadence X-ray monitoring of the M 31 central area with XMM-Newton and Chandra. This project is supplemented by regular optical monitoring programmes at various observatories. Methods: We analysed X-ray and optical monitoring data of a new transient X-ray source in the M 31 GC Bol 126, discovered serendipitously in Swift observations. Our optical data set was based on regular M 31 monitoring programmes from five different small telescopes and was reduced using a homogeneous method. Additionally, we made use of Pan-STARRS 1 data obtained during the PAndromeda survey. We extracted light curves of the source in the optical and X-rays, as well as X-ray spectra. Results: Our observations reveal that the X-ray source in Bol 126 is the third SSS in an M 31 GC and can be confirmed as the second CN in the M 31 GC system. This nova is named M31N 2010-10f. Its properties in the X-ray (high black-body temperature, short SSS phase) and optical (relatively high maximum magnitude, fast decline) regimes agree with a massive white dwarf (MWD ≳ 1.3 M⊙) in the binary system. Incorporating the data on previously found (suspected) novae in M 31 GCs we used our high-cadence X-ray monitoring observations to estimate a tentative nova rate in the M 31 GC system of 0.05 yr-1 GC-1. An optical estimate, based on the recent 10.5-year WeCAPP survey, gives a lower nova rate, which is compatible with the X-ray rate on the 95% confidence level. Conclusions: Although still based on small-number statistics, there is growing evidence that the nova rate in GCs is higher than expected from primordial binary

  9. Range expansion of Northern Hawk Owls (Surnia ulula) and Boreal Owls (Aegolius funereus) in Nova Scotia

    Treesearch

    Randy F. Lauff

    1997-01-01

    The Northern Hawk Owl (Surnia ulula) has never been recorded to breed in Nova Scotia (and only once in recent history in all of the Maritimes). Three pairs of hawk owls were found within 4 km² of woods in 1996, and of these, young were found with two pairs. The first provincial summer record for the Boreal Owl (Aegolius funereus...

  10. Isospin mixing reveals 30P(p, γ) 31S resonance influencing nova nucleosynthesis

    DOE PAGES

    Bennett, M. B.; Wrede, C.; Brown, B. A.; ...

    2016-03-08

    Here, the thermonuclear 30P(p, γ) 31S reaction rate is critical for modeling the final elemental and isotopic abundances of ONe nova nucleosynthesis, which affect the calibration of proposed nova thermometers and the identification of presolar nova grains, respectively. Unfortunately, the rate of this reaction is essentially unconstrained experimentally, because the strengths of key 31S proton capture resonance states are not known, largely due to uncertainties in their spins and parities. Using the β decay of 31Cl, we have observed the β-delayed γ decay of a 31S state at E x = 6390.2(7) keV, with a 30P(p, γ) 31S resonance energymore » of E r = 259.3(8) keV, in the middle of the 30P(p, γ) 31S Gamow window for peak nova temperatures. This state exhibits isospin mixing with the nearby isobaric analog state at E x = 6279.0(6) keV, giving it an unambiguous spin and parity of 3/2 + and making it an important l = 0 resonance for proton capture on 30P.« less

  11. NovaNET: Basic Skills Lessons for Middle School, High School and Adult Basic Education Students.

    ERIC Educational Resources Information Center

    Silver, Dorothy Z., Comp.

    An overview of the NovaNET Computer System, a time-sharing networking computer system for the delivery of computer-based education, is followed by a description of the SYS IV system, which is used for management and record keeping in mathematics, reading, language arts, and spelling curricula. A description of lesson design features follows, along…

  12. A search for sterile neutrinos at the NOvA Far Detector

    NASA Astrophysics Data System (ADS)

    Aurisano, Adam; Davies, Gavin S.; Kafka, Gareth K.; Sousa, Alex; Suter, Louise; Yang, Shaokai

    2017-09-01

    NOvA is the current United States flagship long-baseline neutrino experiment designed to study the properties of neutrino oscillations. It consists of two functionally identical detectors each located 14.6 mrad off the central axis from the Fermilab NuMI neutrino beam. The Near Detector is located 1 km downstream from the beam source, and the Far Detector is located 810 km away in Ash River, Minnesota. This long baseline, combined with the ability of the NuMI facility to switch between nearly pure neutrino and anti-neutrino beams, allows NOvA to make precision measurements of neutrino mixing angles, potentially determine the neutrino mass hierarchy, and begin searching for CP violating effects in the lepton sector. However, NOvA can also probe more exotic scenarios, such as oscillations between the known active neutrinos and new sterile species. We will showcase the first search for sterile neutrinos in a 3 + 1 model at NOvA. The analysis presented searches for a deficit in the rate of neutral current events at the Far Detector using the Near Detector to constrain the predicted spectrum. This analysis was performed using data taken between February 2014 and May 2016 corresponding to 6.05 × 1020 protons on target.

  13. Changes and Possibilities: A Case Study of Nova Scotia Classroom Assessment Policies

    ERIC Educational Resources Information Center

    Van Zoost, Steven

    2011-01-01

    Although numerous writers have identified a different set of skills needed for employment in New Times, little analytic attention has been paid to how educational assessment policies contribute to envisioning such future citizens. This case study illustrates how Nova Scotia classroom assessment policy for Grades 7-9 English classes envisions young…

  14. CONCURRENT FORMATION OF CARBON AND SILICATE DUST IN NOVA V1280 SCO

    SciTech Connect

    Sakon, Itsuki; Onaka, Takashi; Usui, Fumihiko

    2016-02-01

    We present infrared multi-epoch observations of the dust-forming nova V1280 Sco over ∼2000 days from the outburst. The temporal evolution of the infrared spectral energy distributions at 1272, 1616, and 1947 days can be explained by the emissions produced by amorphous carbon dust of mass (6.6–8.7) × 10{sup −8} M{sub ⊙} with a representative grain size of 0.01 μm and astronomical silicate dust of mass (3.4–4.3) × 10{sup −7} M{sub ⊙} with a representative grain size of 0.3–0.5 μm. Both of these dust species travel farther away from the white dwarf without apparent mass evolution throughout those later epochs. The dust formation scenario around V1280more » Sco suggested from our analyses is that the amorphous carbon dust is formed in the nova ejecta followed by the formation of silicate dust either in the expanding nova ejecta or as a result of the interaction between the nova wind and the circumstellar medium.« less

  15. Hubble Space Telescope STIS Spectroscopy of Long-Period Dwarf Novae in Quiescence

    NASA Astrophysics Data System (ADS)

    Sion, Edward M.; Gänsicke, Boris T.; Long, Knox S.; Szkody, Paula; Knigge, Christian; Hubeny, Ivan; deMartino, Domitilla; Godon, Patrick

    2008-07-01

    We present the results of a synthetic spectral analysis of HST STIS spectra of five long-period dwarf novae obtained during their quiescence to determine the properties of their white dwarfs, which are little known for systems above the CV period gap. The five systems, TU Men, BD Pav, SS Aur, TT Crt, and V442 Cen, were observed as part of an HST Snapshot project. The spectra are described and fitted with combinations of white dwarf photospheres and accretion disks. We provide evidence that the white dwarfs in all five systems are at least partially exposed. We discuss the evolutionary implications of our model-fitting results and compare these dwarf novae to previously analyzed FUV spectra of other dwarf novae above the period gap. The dispersion in CV WD temperatures above the period gap is substantially greater than one finds below the period gap, where there is a surprisingly narrow dispersion in temperatures around 15,000 K. There appears to be a larger spread of surface temperatures in dwarf novae above the period than is seen below the gap.

  16. NOVA: Spring 2003 Teacher's Guide. Battle of the X-Planes.

    ERIC Educational Resources Information Center

    WGBH Educational Foundation, Boston, MA.

    This teacher's guide contains supplemental activities to go along with the NOVA television program on PBS. Activities include: (1) "Last Flight of Bomber 31"; (2) "Ancient Creature of the Deep"; (3) "Battle of the X-Planes"; (4) "Mountain of Ice"; (5) "Lost Treasures of Tibet"; and (6)…

  17. Nova Mus 2018 (PNV J11261220-6531086) Is Forming Dust

    NASA Astrophysics Data System (ADS)

    Walter, Frederick M.

    2018-02-01

    Nova Mus 2018 (PNV J11261220-6531086) was discovered by R Kaufman on 2018 Jan 14.486, and reported by P. Schmeer in vsnet-alert 21772. The first detection was 2018 Jan 3.24 (ASAS-SN, reported in the TOCP).

  18. The Shape of Long Outbursts in U Gem Type Dwarf Novae from AAVSO Data

    NASA Technical Reports Server (NTRS)

    Cannizzo, John K.

    2012-01-01

    We search the American Association of Variable Star Observers (AAVSO) archives of the two best studied dwarf novae in an attempt to find light curves for long out bursts that are extremely well-characterized. The systems are U Gem and S8 Cyg. Our goal is to search for embedded precursors such as those that have been found recently in the high fidelity Kepler data for superoutbursts of some members of the 8U UMa subclass of dwarf novae. For the vast majority of AAV80 data, the combination of low data cadence and large errors associated with individual measurements precludes one from making any strong statement about the shape of the long outbursts. However, for a small number of outbursts, extensive long term monitoring with digital photometry yields high fidelity light curves. We report the finding of embedded precursors in two of three candidate long outbursts. This reinforces van Paradijs' finding that long outbursts in dwarf novae above the period gap and superoutbursts in systems below the period gap constitute a unified class. The thermal-tidal instability to account for superoutbursts in the SU UMa stars predicts embedded precursors only for short orbital period dwarf novae, therefore the presence of embedded precursors in long orbital period systems - U Gem and SS Cyg - argues for a more general mechanism to explain long outbursts.

  19. XMM-Newton X-ray spectra of V407 Lup (Nova Lup 2016)

    NASA Astrophysics Data System (ADS)

    Ness, Jan-Uwe; Starrfield, Sumner; Woodward, Chick E.; Kuin, Paul; Page, Kim; Beardmore, Andy; Osborne, Julian; Sala, Gloria; Hernanz, Margarita; Orio, Marina; Williams, Bob

    2017-09-01

    Nova Lup 2016 (V407 Lup) was observed by XMM-Newton from 11 March 2017, 11:45 to 17:08 UT, 168 days after outburst (ATel #9538) with an exposure duration of 23,000 s. The EPIC pn was operated in Timing Mode with Medium filter.

  20. Optical and near-IR spectroscopy of nova Oph 2017 (TCP J17394608-2457555)

    NASA Astrophysics Data System (ADS)

    Raj, Ashish; Pavana, M.; Anupama, G. C.; Bhowmick, Anirban; Dar, Rahul; Kumar, S. Pramod

    2017-05-01

    We report optical and near-IR spectroscopic observations of the nova Oph 2017 (ATel #10366, #10367, #10369). The optical spectrum on May 11, 2017 was obtained using the HFOSC instrument mounted on the 2m Himalayan Chandra Telescope (HCT) of the Indian Astronomical Observatory, Hanle, India, in the 380-800nm wavelength range.