New Improvements in Mixture Self-Shielding Treatment with APOLLO2 Code

International Nuclear Information System (INIS)

Coste-Delclaux, M.

2006-01-01

Full text of the presentation follows: APOLLO2 is a modular multigroup transport code developed at the CEA in Saclay (France). Previously, the self-shielding module could only treat one resonant isotope mixed with moderator isotopes. Consequently, the resonant mixture self-shielding treatment was an iterative one. Each resonant isotope of the mixture was treated separately, the other resonant isotopes of the mixture being then considered as moderator isotopes, that is to say non-resonant isotopes. This treatment could be iterated. Recently, we have developed a new method that consists in treating the resonant mixture as a unique entity. A main feature of APOLLO2 self-shielding module is that some implemented models are very general and therefore very powerful and versatile. We can give, as examples, the use of probability tables in order to describe the microscopic cross-section fluctuations or the TR slowing-down model that can deal with any resonance shape. The self-shielding treatment of a resonant mixture was developed essentially thanks to these two models. The goal of this paper is to describe the improvements on the self-shielding treatment of a resonant mixture and to present, as an application, the calculation of the ATRIUM-10 BWR benchmark. We will conclude by some prospects on remaining work in the self-shielding domain. (author)

Resonance self-shielding methodology of new neutron transport code STREAM

International Nuclear Information System (INIS)

Choi, Sooyoung; Lee, Hyunsuk; Lee, Deokjung; Hong, Ser Gi

2015-01-01

This paper reports on the development and verification of three new resonance self-shielding methods. The verifications were performed using the new neutron transport code, STREAM. The new methodologies encompass the extension of energy range for resonance treatment, the development of optimum rational approximation, and the application of resonance treatment to isotopes in the cladding region. (1) The extended resonance energy range treatment has been developed to treat the resonances below 4 eV of three resonance isotopes and shows significant improvements in the accuracy of effective cross sections (XSs) in that energy range. (2) The optimum rational approximation can eliminate the geometric limitations of the conventional approach of equivalence theory and can also improve the accuracy of fuel escape probability. (3) The cladding resonance treatment method makes it possible to treat resonances in cladding material which have not been treated explicitly in the conventional methods. These three new methods have been implemented in the new lattice physics code STREAM and the improvement in the accuracy of effective XSs is demonstrated through detailed verification calculations. (author)

The resonance self-shielding calculation with regularized random ladders

International Nuclear Information System (INIS)

Ribon, P.

1986-01-01

The straightforward method for calculation of resonance self-shielding is to generate one or several resonance ladders, and to process them as resolved resonances. The main drawback of Monte Carlo methods used to generate the ladders, is the difficulty of reducing the dispersion of data and results. Several methods are examined, and it is shown how one (a regularized sampling method) improves the accuracy. Analytical methods to compute the effective cross-section have recently appeared: they are basically exempt from dispersion, but are inevitably approximate. The accuracy of the most sophisticated one is checked. There is a neutron energy range which is improperly considered as statistical. An examination is presented of what happens when it is treated as statistical, and how it is possible to improve the accuracy of calculations in this range. To illustrate the results calculations have been performed in a simple case: nucleus 238 U, at 300 K, between 4250 and 4750 eV. (author)

URR [Unresolved Resonance Region] computer code: A code to calculate resonance neutron cross-section probability tables, Bondarenko self-shielding factors, and self-indication ratios for fissile and fertile nuclides

International Nuclear Information System (INIS)

Leal, L.C.; de Saussure, G.; Perez, R.B.

1989-01-01

The URR computer code has been developed to calculate cross-section probability tables, Bondarenko self-shielding factors, and self- indication ratios for fertile and fissile isotopes in the unresolved resonance region. Monte Carlo methods are utilized to select appropriate resonance parameters and to compute the cross sections at the desired reference energy. The neutron cross sections are calculated by the single-level Breit-Wigner formalism with s-, p-, and d-wave contributions. The cross-section probability tables are constructed by sampling the Doppler broadened cross-section. The various shelf-shielded factors are computed numerically as Lebesgue integrals over the cross-section probability tables. 6 refs

Resonance self-shielding effect analysis of neutron data libraries applied for the dual-cooled waste transmutation blanket of the fusion-driven subcritical system

International Nuclear Information System (INIS)

Liu Haibo; Wu Yican; Zheng Shanliang; Zhang Chunzao

2004-01-01

Based on the Fusion-Driven Subcritical System (FDS-I), the 25 groups, 175 groups and 620 groups neutron nuclear data libraries with/without resonance self-shielding correction are made with the Njoy and Transx codes, and the K eff and reaction rates are calculated with the Anisn code. The conclusion indicates that the resonance self-shielding effect affects the reaction rates strongly. (authors)

Uranium self-shielding in fast reactor blankets

Energy Technology Data Exchange (ETDEWEB)

Kadiroglu, O.K.; Driscoll, M.J.

1976-03-01

The effects of heterogeneity on resonance self-shielding are examined with particular emphasis on the blanket region of the fast breeder reactor and on its dominant reaction--capture in /sup 238/U. The results, however, apply equally well to scattering resonances, to other isotopes (fertile, fissile and structural species) and to other environments, so long as the underlying assumptions of narrow resonance theory apply. The heterogeneous resonance integral is first cast into a modified homogeneous form involving the ratio of coolant-to-fuel fluxes. A generalized correlation (useful in its own right in many other applications) is developed for this ratio, using both integral transport and collision probability theory to infer the form of correlation, and then relying upon Monte Carlo calculations to establish absolute values of the correlation coefficients. It is shown that a simple linear prescription can be developed for the flux ratio as a function of only fuel optical thickness and the fraction of the slowing-down source generated by the coolant. This in turn permitted derivation of a new equivalence theorem relating the heterogeneous self-shielding factor to the homogeneous self-shielding factor at a modified value of the background scattering cross section per absorber nucleus. A simple version of this relation is developed and used to show that heterogeneity has a negligible effect on the calculated blanket breeding ratio in fast reactors.

Elastic removal self-shielding factors for light and medium nuclides with strong-resonance scattering

International Nuclear Information System (INIS)

Nakagawa, Masayuki; Ishiguro, Yukio; Tokuno, Yukio.

1978-01-01

The self-shielding factors for elastic removal cross sections of light and medium weight nuclides were calculated for the parameter, σ 0 within the conventional concept of the group constant sets. The numerical study were performed for obtaining a simple and accurate method. The present results were compared with the exact values and the conventional ones, and shown to be remarkably improved. It became apparent that the anisotropy of the elastic scattering did not affect to the self-shielding factors though it did to the infinite dilution cross sections. With use of the present revised set, the neutron flux were calculated in an iron medium and in a prototype FBR and compared with those by the fine spectrum calculations and the conventional set. The present set showed the considerable improvement in the vicinity of the large resonance regions of sodium, iron and oxygen. (auth.)

Self-shielding models of MICROX-2 code: Review and updates

International Nuclear Information System (INIS)

Hou, J.; Choi, H.; Ivanov, K.N.

2014-01-01

Highlights: • The MICROX-2 code has been improved to expand its application to advanced reactors. • New fine-group cross section libraries based on ENDF/B-VII have been generated. • Resonance self-shielding and spatial self-shielding models have been improved. • The improvements were assessed by a series of benchmark calculations against MCNPX. - Abstract: The MICROX-2 is a transport theory code that solves for the neutron slowing-down and thermalization equations of a two-region lattice cell. The MICROX-2 code has been updated to expand its application to advanced reactor concepts and fuel cycle simulations, including generation of new fine-group cross section libraries based on ENDF/B-VII. In continuation of previous work, the MICROX-2 methods are reviewed and updated in this study, focusing on its resonance self-shielding and spatial self-shielding models for neutron spectrum calculations. The improvement of self-shielding method was assessed by a series of benchmark calculations against the Monte Carlo code, using homogeneous and heterogeneous pin cell models. The results have shown that the implementation of the updated self-shielding models is correct and the accuracy of physics calculation is improved. Compared to the existing models, the updates reduced the prediction error of the infinite multiplication factor by ∼0.1% and ∼0.2% for the homogeneous and heterogeneous pin cell models, respectively, considered in this study

Advances in the development of a subgroup method for the self-shielding of resonant isotopes in arbitrary geometries

International Nuclear Information System (INIS)

Hebert, A.

1997-01-01

The subgroup method is used to compute self-shielded cross sections defined over coarse energy groups in the resolved energy domain. The validity of the subgroup approach was extended beyond the unresolved energy domain by partially taking into account correlation effects between the slowing-down source with the collision probability terms of the transport equation. This approach enables one to obtain a pure subgroup solution of the self-shielding problem without relying on any form of equivalence in dilution. Specific improvements are presented on existing subgroup methods: an N-term rational approximation for the fuel-to-fuel collision probability, a new Pade deflation technique for computing probability tables, and the introduction of a superhomogenization correction. The absorption rates obtained after self-shielding are compared with exact values obtained using an elastic slowing-down calculation where each resonance is modeled individually in the resolved energy domain

Cross-section fluctuations and self-shielding effects in the unresolved resonance region - International Evaluation Co-operation volume 15

International Nuclear Information System (INIS)

Froehner, F.H.; Larson, Duane C.; Tagesen, Siegfried; Petrizzi, Luigi; Hasegawa, Akira; Nakagawa, Tsuneo; Hogenbirk, Alfred; Weigmann, H.

1995-01-01

A Working Party on International Evaluation Co-operation was established under the sponsorship of the OECD/NEA Nuclear Science Committee (NSC) to promote the exchange of information on nuclear data evaluations, validation, and related topics. Its aim is also to provide a framework for co-operative activities between members of the major nuclear data evaluation projects. This includes the possible exchange of scientists in order to encourage co-operation. Requirements for experimental data resulting from this activity are compiled. The Working Party determines common criteria for evaluated nuclear data files with a view to assessing and improving the quality and completeness of evaluated data. The Parties to the project are: ENDF (United States), JEFF/EFF (NEA Data Bank Member countries), and JENDL (Japan). Co-operation with evaluation projects of non-OECD countries are organised through the Nuclear Data Section of the International Atomic Energy Agency (IAEA). NEA/NSC Subgroup 15 has had the task to assess self-shielding effects in the unresolved resonance range of structural materials, in particular their importance at various energies, and possible ways to deal with them in shielding and activation work. The principal results achieved are summarised briefly, in particular: - New data base consisting of high-resolution transmission data measured at Oak Ridge and Geel; - Improved theoretical understanding of cross-section fluctuations, including their prediction, that has been derived from the Hauser-Feshbach theory; - Benchmark results on the importance of self-shielding in iron at various energies; - Consequences for information storage in evaluated nuclear data files; - Practical utilisation of self-shielding information from evaluated files. Benchmark results as well as the Hauser-Feshbach theory show that self-shielding effects are important up to a 4-or 5-MeV neutron energy. Fluctuation factors extracted from high-resolution total cross-section data can be

Radially and azimuthally dependent resonance self-shielding treatment for general multi-region geometry based on a unified theory

International Nuclear Information System (INIS)

Koike, Hiroki; Kirimura, Kazuki; Yamaji, Kazuya; Kosaka, Shinya; Yamamoto, Akio

2018-01-01

A unified resonance self-shielding method, which can treat general sub-divided fuel regions, is developed for lattice physics calculations in reactor physics field. In a past study, a hybrid resonance treatment has been developed by theoretically integrating equivalence theory and ultra-fine-group slowing-down calculation. It can be applied to a wide range of neutron spectrum conditions including low moderator density ranges in severe accident states, as long as each fuel region is not sub-divided. In order to extend the method for radially and azimuthally sub-divided multi-region geometry, a new resonance treatment is established by incorporating the essence of sub-group method. The present method is composed of two-step flux calculation, i.e. 'coarse geometry + fine energy' (first step) and 'fine geometry + coarse energy' (second step) calculations. The first step corresponds to a hybrid model of the equivalence theory and the ultra-fine-group calculation, and the second step corresponds to the sub-group method. From the verification results, effective cross-sections by the new method show good agreement with the continuous energy Monte-Carlo results for various multi-region geometries including non-uniform fuel compositions and temperature distributions. The present method can accurately generate effective cross-sections with short computation time in general lattice physics calculations. (author)

New improvements in the self-shielding formalism of the Apollo-2 code

International Nuclear Information System (INIS)

Coste, M.; Tellier, H.; Ribon, P.; Raepsaet, V.; Van der Gucht, C.

1993-01-01

One important modelization of a transport code working on a coarse energy mesh is the self-shielding. The French transport code APPOLO 2, developed at the Commissariat a l'Energie Atomique, uses a self-shielding formalism based on a double equivalence. First a homogenization gives the reaction rates in a heterogeneous geometry, and then a multigroup equivalence gives, once the reaction rates are known, the self-shielded cross-sections. The homogenization is a very sensitive part because it is the one which requires physical modelizations. We have added a new model which allows us to treat numerous narrow resonances statistically distributed in the same group of the multigroup mesh. It is important to notice that for a narrow resonance isolated in a group, that new model is equivalent to the previous narrow resonance model (NR)

CREST : a computer program for the calculation of composition dependent self-shielded cross-sections

International Nuclear Information System (INIS)

Kapil, S.K.

1977-01-01

A computer program CREST for the calculation of the composition and temperature dependent self-shielded cross-sections using the shielding factor approach has been described. The code includes the editing and formation of the data library, calculation of the effective shielding factors and cross-sections, a fundamental mode calculation to generate the neutron spectrum for the system which is further used to calculate the effective elastic removal cross-sections. Studies to explore the sensitivity of reactor parameters to changes in group cross-sections can also be carried out by using the facility available in the code to temporarily change the desired constants. The final self-shielded and transport corrected group cross-sections can be dumped on cards or magnetic tape in a suitable form for their direct use in a transport or diffusion theory code for detailed reactor calculations. The program is written in FORTRAN and can be accommodated in a computer with 32 K work memory. The input preparation details, sample problem and the listing of the program are given. (author)

Unresolved resonance range cross section, probability tables and self shielding factor

International Nuclear Information System (INIS)

Sublet, J.Ch.; Blomquist, R.N.; Goluoglu, S.; Mac Farlane, R.E.

2009-07-01

The performance and methodology of 4 processing codes have been compared in the unresolved resonance range of a selected set of isotopes. Those isotopes have been chosen to encompass most cases encountered in the unresolved energy range contained in major libraries like Endf/B-7 or Jeff-3.1.1. The code results comparison is accompanied by data format and formalism examinations and processing code fine-interpretation study. After some improvements, the results showed generally good agreement, although not perfect with infinite dilute cross-sections. However, much larger differences occur when shelf-shielded effective cross-sections are compared. The infinitely dilute cross-section are often plot checked but it is the probability table derived and shelf-shielded cross sections that are used and interpreted in criticality and transport calculations. This suggests that the current evaluation data format and formalism, in the unresolved resonance range should be tightened up, ambiguities removed. In addition production of the shelf shielded cross-sections should be converged to a much greater accuracy. (author)

Resonance self-shielding effect in uncertainty quantification of fission reactor neutronics parameters

International Nuclear Information System (INIS)

Chiba, Go; Tsuji, Masashi; Narabayashi, Tadashi

2014-01-01

In order to properly quantify fission reactor neutronics parameter uncertainties, we have to use covariance data and sensitivity profiles consistently. In the present paper, we establish two consistent methodologies for uncertainty quantification: a self-shielded cross section-based consistent methodology and an infinitely-diluted cross section-based consistent methodology. With these methodologies and the covariance data of uranium-238 nuclear data given in JENDL-3.3, we quantify uncertainties of infinite neutron multiplication factors of light water reactor and fast reactor fuel cells. While an inconsistent methodology gives results which depend on the energy group structure of neutron flux and neutron-nuclide reaction cross section representation, both the consistent methodologies give fair results with no such dependences.

Shield Optimization and Formulation of Regression Equations for Split-Ring Resonator

Directory of Open Access Journals (Sweden)

Tahir Ejaz

2016-01-01

Full Text Available Microwave resonators are widely used for numerous applications including communication, biomedical and chemical applications, material testing, and food grading. Split-ring resonators in both planar and nonplanar forms are a simple structure which has been in use for several decades. This type of resonator is characterized with low cost, ease of fabrication, moderate quality factor, low external noise interference, high stability, and so forth. Due to these attractive features and ease in handling, nonplanar form of structure has been utilized for material characterization in 1–5 GHz range. Resonant frequency and quality factor are two important parameters for determination of material properties utilizing perturbation theory. Shield made of conducting material is utilized to enclose split-ring resonator which enhances quality factor. This work presents a novel technique to develop shield around a predesigned nonplanar split-ring resonator to yield optimized quality factor. Based on this technique and statistical analysis regression equations have also been formulated for resonant frequency and quality factor which is a major outcome of this work. These equations quantify dependence of output parameters on various factors of shield made of different materials. Such analysis is instrumental in development of devices/designs where improved/optimum result is required.

RESONANCE SELF-SHIELDING EFFECT IN UNCERTAINTY QUANTIFICATION OF FISSION REACTOR NEUTRONICS PARAMETERS

Directory of Open Access Journals (Sweden)

GO CHIBA

2014-06-01

Full Text Available In order to properly quantify fission reactor neutronics parameter uncertainties, we have to use covariance data and sensitivity profiles consistently. In the present paper, we establish two consistent methodologies for uncertainty quantification: a self-shielded cross section-based consistent methodology and an infinitely-diluted cross section-based consistent methodology. With these methodologies and the covariance data of uranium-238 nuclear data given in JENDL-3.3, we quantify uncertainties of infinite neutron multiplication factors of light water reactor and fast reactor fuel cells. While an inconsistent methodology gives results which depend on the energy group structure of neutron flux and neutron-nuclide reaction cross section representation, both the consistent methodologies give fair results with no such dependences.

Adaptive algorithms for a self-shielding wavelet-based Galerkin method

International Nuclear Information System (INIS)

Fournier, D.; Le Tellier, R.

2009-01-01

The treatment of the energy variable in deterministic neutron transport methods is based on a multigroup discretization, considering the flux and cross-sections to be constant within a group. In this case, a self-shielding calculation is mandatory to correct sections of resonant isotopes. In this paper, a different approach based on a finite element discretization on a wavelet basis is used. We propose adaptive algorithms constructed from error estimates. Such an approach is applied to within-group scattering source iterations. A first implementation is presented in the special case of the fine structure equation for an infinite homogeneous medium. Extension to spatially-dependent cases is discussed. (authors)

The self shielding module of Apollo.II; Module d`autoprotection du code Apollo.II

Energy Technology Data Exchange (ETDEWEB)

Sanchez, R.

1994-06-01

This note discusses the methods used in the APOLLO.II code for the calculation of self shielded multigroup cross sections. Basically, the calculation consists in characterizing a heterogenous medium with a single parameter: the background cross section, which is in then used to interpolate reaction rates from pre tabulated values. Very fine multigroup slowing down calculations in homogenous media are used to generate these tables, which contain absorption, diffusion and production reaction rates per group, resonant isotope, temperature and background cross section. Multigroup self shielded cross sections are determined from an equivalence that preserves absorption rates at a slowing down problem with given sources. This article gives a detailed description of the PIC and ``dilution matrix`` formalisms that are used in the homogenization step, as well as the utilization of Bell macro-groups and the different quadrature formulas that may be used in the calculations. Self shielding techniques for isotopic resonant mixtures are also discussed. (author). 2 refs., 193 figs., 2 tabs.

New approximations for the Doppler broadening function applied to the calculation of resonance self-shielding factors

International Nuclear Information System (INIS)

Palma, Daniel A.; Goncalves, Alessandro C.; Martinez, Aquilino S.; Silva, Fernando C.

2008-01-01

The activation technique allows much more precise measurements of neutron intensity, relative or absolute. The technique requires the knowledge of the Doppler broadening function ψ(x,ξ) to determine the resonance self-shielding factors in the epithermal range G epi (τ,ξ). Two new analytical approximations for the Doppler broadening function ψ(x,ξ) are proposed. The approximations proposed are compared with other methods found in literature for the calculation of the ψ(x,ξ) function, that is, the 4-pole Pade method and the Frobenius method, when applied to the calculation of G epi (τ,ξ). The results obtained provided satisfactory accuracy. (authors)

New approximations for the Doppler broadening function applied to the calculation of resonance self-shielding factors

Energy Technology Data Exchange (ETDEWEB)

Palma, Daniel A. [CEFET QUIMICA de Nilopolis/RJ, Rio de Janeiro (Brazil); Goncalves, Alessandro C.; Martinez, Aquilino S.; Silva, Fernando C. [COPPE/UFRJ - Programa de Engenharia Nuclear, Rio de Janeiro (Brazil)

2008-07-01

The activation technique allows much more precise measurements of neutron intensity, relative or absolute. The technique requires the knowledge of the Doppler broadening function psi(x,xi) to determine the resonance self-shielding factors in the epithermal range G{sub epi} (tau,xi). Two new analytical approximations for the Doppler broadening function psi(x,xi) are proposed. The approximations proposed are compared with other methods found in literature for the calculation of the psi(x,xi) function, that is, the 4-pole Pade method and the Frobenius method, when applied to the calculation of G{sub epi} (tau,xi). The results obtained provided satisfactory accuracy. (authors)

Assessment of the MPACT Resonance Data Generation Procedure

Energy Technology Data Exchange (ETDEWEB)

Kim, Kang Seog [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Williams, Mark L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2016-12-26

Currently, heterogeneous models are being used to generate resonance self-shielded cross-section tables as a function of background cross sections for important nuclides such as ²³⁵U and ²³⁸U by performing the CENTRM (Continuous Energy Transport Model) slowing down calculation with the MOC (Method of Characteristics) spatial discretization and ESSM (Embedded Self-Shielding Method) calculations to obtain background cross sections. And then the resonance self-shielded cross section tables are converted into subgroup data which are to be used in estimating problem-dependent self-shielded cross sections in MPACT (Michigan Parallel Characteristics Transport Code). Although this procedure has been developed and thus resonance data have been generated and validated by benchmark calculations, assessment has never been performed to review if the resonance data are properly generated by the procedure and utilized in MPACT. This study focuses on assessing the procedure and a proper use in MPACT.

UNR. A code for processing unresolved resonance data for MCNP

International Nuclear Information System (INIS)

Hogenbirk, A.

1994-09-01

In neutron transport problems the correct treatment of self-shielding is important for those nuclei present in large concentrations. Monte Carlo calculations using continuous-energy cross section data, such as calculations with the code MCNP, offer the advantage that neutron transport is calculated in a very accurate way. Self-shielding in the resolved resonance region is taken into account exactly in MCNP. However, self-shielding in the unresolved resonance region can not be taken into account by MCNP, although the effect of it may be important in many applications. In this report a description is given of the computer code UNR. With this code problem-dependent cross section libraries can be produced for MCNP. In these libraries self-shielded cross section data in the unresolved resonance range are given, which are produced by NJOY-module UNRESR. It is noted, that the treatment for resonance self-shielding presented in this report is approximate. However, the current version of MCNP does not allow the use of probability tables, which would be a general solution. (orig.)

Self-Shielding Treatment to Perform Cell Calculation for Seed Furl In Th/U Pwr Using Dragon Code

Directory of Open Access Journals (Sweden)

Ahmed Amin El Said Abd El Hameed

2015-08-01

Full Text Available Time and precision of the results are the most important factors in any code used for nuclear calculations. Despite of the high accuracy of Monte Carlo codes, MCNP and Serpent, in many cases their relatively long computational time leads to difficulties in using any of them as the main calculation code. Usually, Monte Carlo codes are used only to benchmark the results. The deterministic codes, which are usually used in nuclear reactor’s calculations, have limited precision, due to the approximations in the methods used to solve the multi-group transport equation. Self- Shielding treatment, an algorithm that produces an average cross-section defined over the complete energy domain of the neutrons in a nuclear reactor, is responsible for the biggest error in any deterministic codes. There are mainly two resonance self-shielding models commonly applied: models based on equivalence and dilution and models based on subgroup approach. The fundamental problem with any self-shielding method is that it treats any isotope as there are no other isotopes with resonance present in the reactor. The most practical way to solve this problem is to use multi-energy groups (50-200 that are chosen in a way that allows us to use all major resonances without self-shielding. In this paper, we perform cell calculations, for a fresh seed fuel pin which is used in thorium/uranium reactors, by solving 172 energy group transport equation using the deterministic DRAGON code, for the two types of self-shielding models (equivalence and dilution models and subgroup models Using WIMS-D5 and DRAGON data libraries. The results are then tested by comparing it with the stochastic MCNP5 code.  We also tested the sensitivity of the results to a specific change in self-shielding method implemented, for example the effect of applying Livolant-Jeanpierre Normalization scheme and Rimman Integration improvement on the equivalence and dilution method, and the effect of using Ribbon

Investigating spatial self-shielding and temperature effects for homogeneous and double heterogeneous pebble models with MCNP

International Nuclear Information System (INIS)

Li, J.; Nuenighoff; Pohl, C.; Allelein, H.J.

2010-01-01

The gas-cooled, high temperature reactor (HTR) represents a valuable option for the future development of nuclear technology, because of its excellent safety features. One main safety feature is the negative temperature coefficient which is due to the Doppler broadening of the (n,y) resonance absorption cross section. A second important effect is the spatial self-shielding due to the double heterogeneous geometry of a pebble bed reactor. At FZ-Juelich two reactor analysis codes have been developed: VSOP for core design and MGT for transient analysis. Currently an update of the nuclear cross section libraries to ENDF/B-VII.0 of both codes takes place. In order to take the temperature dependency as well as the spatial self-shielding into account the absorption cross sections σ (n,y) for the resonance absorbers like 232 Th and 238 U have to be provided as function of incident neutron energy, temperature and nuclide concentration. There are two reasons for choosing the Monte-Carlo approach to calculate group wise cross sections. First, the former applied ZUT-DGL code to generate the resonance cross section tables for MGT is so far not able to handle the new resonance description based on Reich-Moore instead of Single-level Breit-Wigner. Second, the rising interest in PuO 2 fuel motivated an investigation on the generation of group wise cross sections describing thermal resonances of 240 Pu and 242 Pu. (orig.)

Heavy nucleus resonant absorption in heterogeneous lattices. I- Apollo 2 self-shielding formalism; Absorption resonnante des noyaux lourds dans les reseaux heterogenes. I -Formalisme du module d`autoprotection d`Apollo 2

Energy Technology Data Exchange (ETDEWEB)

Coste, M.

1994-01-01

This note gives in detailed way the self-shielding formalism which is used in the multigroup transport code APOLLO2. The self-shielded cross-sections are performed with the same scheme as in APOLLO1. We use two equivalencies, first an heterogeneous/homogeneous equivalence which gives the reaction rates and then a multigroup equivalence in order to obtain the cross-sections which preserve these reaction rates. However, numerous improvements were implemented, specially in the homogenization step. Homogenization can be performed group per group with different modelizations of the heavy slowing-down operator (statistical, intermediary and ``wide resonance`` models), which allows us to fit correctly the resonance shapes. Moreover, we can take exactly into account the spatial interferences between resonant isotopes with the background matrix model. Consequently, we are now able to perform, for instance, the radial distribution of the resonant absorption inside a fuel pin. (author). 7 refs., 3 figs.

Characteristic Determination Of Self Shielding Factor And Cadmium Ratio Of Cylindrical Probe

International Nuclear Information System (INIS)

Hamzah, Amir; Budi R, Ita; Pinem, Suriam

1996-01-01

Determination of thermal, epithermal and total self shielding factor and cadmium ratio of cylindrical probe has been done by measurement and calculation. Self shielding factor can be determined by dividing probe activity to Al-alloy probe activity. Due to the lack of cylindrical probe made of Al-alloy, self shielding factor can be determined by parabolic extrapolation of measured activities to 0 cm radius to divide those activities. Theoretically, self shielding factor can be determined by making numerical solution of two dimensional integral equations using Romberg method. To simplify, the calculation is based on single collision theory with the assumption of monoenergetic neutron and isotropic distribution. For gold cylindrical probe, the calculation results are quite close to the measurement one with the relative discrepancy for activities, cadmium ratio and self shielding factor of bare probe are less then 11.5%, 3,5% and 1.5% respectively. The program can be used for the calculation of other kinds of cylindrical probes. Due to dependency to radius, cylindrical probe made of copper has the best characteristic of self shielding factor and cadmium ratio

Calculation of self-shielding factors for cross-sections in the unresolved resonance region using the GRUCON applied program package

International Nuclear Information System (INIS)

Sinitsa, V.V.

1984-11-01

The author gives a scheme for the calculation of the self-shielding factors in the unresolved resonance region using the GRUCON applied program package. This package is especially created to be used in the conversion of evaluated neutron cross-section data, as available in existing data libraries, into multigroup microscopic constants. A detailed description of the formulae and algorithms used in the programs is given. Some typical examples of calculation are considered and the results are compared with those of other authors. The calculation accuracy is better than 2%

Excitation dependence of resonance line self-broadening at different atomic densities

OpenAIRE

Li, Hebin; Sautenkov, Vladimir A.; Rostovtsev, Yuri V.; Scully, Marlan O.

2009-01-01

We study the dipole-dipole spectral broadening of a resonance line at high atomic densities when the self-broadening dominates. The selective reflection spectrum of a weak probe beam from the interface of the cell window and rubidium vapor are recorded in the presence of a far-detuned pump beam. The excitation due to the pump reduces the self-broadening. We found that the self-broadening reduction dependence on the pump power is atomic density independent. These results provide experimental e...

Development and testing of multigroup library with correction of self-shielding effects in fusion-fission hybrid reactor

International Nuclear Information System (INIS)

Zou Jun; He Zhaozhong; Zeng Qin; Qiu Yuefeng; Wang Minghuang

2010-01-01

A multigroup library HENDL2.1/SS (Hybrid Evaluated Nuclear Data Library/Self-Shielding) based on ENDF/B-VII.0 evaluate data has been generated using Bondarenko and flux calculator method for the correction of self-shielding effect of neutronics analyses. To validate the reliability of the multigroup library HENDL2.1/SS, transport calculations for fusion-fission hybrid system FDS-I were performed in this paper. It was verified that the calculations with the HENDL2.1/SS gave almost the same results with MCNP calculations and were better than calculations with the HENDL2.0/MG which is another multigroup library without self-shielding correction. The test results also showed that neglecting resonance self-shielding caused underestimation of the K eff , neutron fluxes and waste transmutation ratios in the multigroup calculations of FDS-I.

Heavy nucleus resonant absorption in heterogeneous lattices

International Nuclear Information System (INIS)

Tellier, H.; Coste, M.; Raepsaet, C.; Van der Gucht, C.

1992-11-01

The new self shielding formalism which is implemented in the transport code APPOLO 2 allows to compute the space and the energy dependence of the resonant absorption rate inside a fuel rod. As it does not exist any experimental result to check such a computation, we used very sophisticated reference calculations to check the self shielding formalism. Two kinds of reference calculation were used: a multi-group slowing down calculation with a very detailed energy mesh and a MONTE CARLO computation with point wise cross sections. The purpose of this study is a comparison of the self-shielding result with the ones of the two reference calculations. The geometry of the fuel element is the one of a light water-reactor and the resonant nuclei are the most important self-shielded nuclei: 238U, 232Th or 240Pu. The reactor agreement between the three kinds of calculations is very satisfactory for the nominal water density and for a reduced water density which simulates incidental operating conditions

Self-shielding of hydrogen in the IGM during the epoch of reionization

Science.gov (United States)

Chardin, Jonathan; Kulkarni, Girish; Haehnelt, Martin G.

2018-04-01

We investigate self-shielding of intergalactic hydrogen against ionizing radiation in radiative transfer simulations of cosmic reionization carefully calibrated with Lyα forest data. While self-shielded regions manifest as Lyman-limit systems in the post-reionization Universe, here we focus on their evolution during reionization (redshifts z = 6-10). At these redshifts, the spatial distribution of hydrogen-ionizing radiation is highly inhomogeneous, and some regions of the Universe are still neutral. After masking the neutral regions and ionizing sources in the simulation, we find that the hydrogen photoionization rate depends on the local hydrogen density in a manner very similar to that in the post-reionization Universe. The characteristic physical hydrogen density above which self-shielding becomes important at these redshifts is about nH ˜ 3 × 10-3 cm-3, or ˜20 times the mean hydrogen density, reflecting the fact that during reionization photoionization rates are typically low enough that the filaments in the cosmic web are often self-shielded. The value of the typical self-shielding density decreases by a factor of 3 between redshifts z = 3 and 10, and follows the evolution of the average photoionization rate in ionized regions in a simple fashion. We provide a simple parameterization of the photoionization rate as a function of density in self-shielded regions during the epoch of reionization.

Heavy nucleus resonance absorption in heterogeneous lattices

International Nuclear Information System (INIS)

Coste, M.; Tellier, H.; Brienne-Raepsaet, C.; Van Der Gucht, C.

1992-01-01

To compute easily the neutron reaction rates in the resonance energy range, the reactor physicists use the self-shielding formalism and the effective cross-section concept. Usually, for these calculations, and equivalence process is used, in such a way that the absorption rate is correctly computed for the whole fuel pin. This procedure does not allow to preserve the spatial absorption rate distribution inside the pin. It is an important handicap if we want to reproduce the plutonium distribution in a spent fuel. To avoid this inconvenience, new improvements of the self-shielding formalism have been recently introduced in the new assembly calculation code of the French Atomic Energy Commission, APOLLO 2. With this improved formalism, it is now possible to represent the spatial and energetic dependence of the heavy nucleus absorption inside the fuel pin and to use a fine energy dependent equivalence process. As it does not exist clean experimental results for the spatial and energetic dependence of the absorption, the authors used reference calculations to qualify the self-shielding formalism. For the strongly self-shielded nuclei of interest in reactor physics, U238, Pu240 and Th232, the agreement between the self-shielding calculation and the reference ones is fairly good for the spatial and energetic dependence of the absorption rate

Effects of Aperture Size on Q factor and Shielding Effectiveness of a Cubic Resonator

Directory of Open Access Journals (Sweden)

S. Parr

2017-09-01

Full Text Available The EMC properties of a cubic metallic shield are highly affected by its resonances. At the resonant frequencies, the shielding effectiveness (SE collapses, which results in high field strengths inside the cavity. This can cause failure or even breakdown of electronic devices inside the shield. The resonant behaviour is mainly determined by the quality or Q factor of the shield. In this paper, the effects of the aperture size on the Q factor and the SE of an electrically large, cubic shield are analysed. At first, a method is developed in order to determine the Q factor based on the resonance behaviour of the shield in time domain. Only the first resonance of the shield is considered therefore. The results are evaluated for different aperture diameters and compared with theory for the Q factor. The dominant coupling mechanism of electromagnetic energy into the shield is thus identified. Then the effect of aperture size on the SE is analysed. The excitation of resonances is very probable if the interfering signal is an ultrawideband (UWB pulse, which constitutes a typical intentional electromagnetic interference (IEMI scenario. Therefore, the relation between aperture size and SE is analysed using the theory of the transient SE for a broadband signal with a constant spectral density distribution. The results show, that a worst case aperture size exists, where the SE has its minimum.

Optimized Shielding and Fabrication Techniques for TiN and Al Microwave Resonators

Science.gov (United States)

Kreikebaum, John Mark; Kim, Eunseong; Livingston, William; Dove, Allison; Calusine, Gregory; Hover, David; Rosenberg, Danna; Oliver, William; Siddiqi, Irfan

We present a systematic study of the effects of shielding and packaging on the internal quality factor (Qi) of Al and TiN microwave resonators designed for use in qubit readout. Surprisingly, Qi =1.3x106 TiN samples investigated at 100 mK exhibited no significant changes in linewidth when operated without magnetic shielding and in an open cryo-package. In contrast, Al resonators showed systematic improvement in Qi with each successive shield. Measurements were performed in an adiabatic demagnetization refrigerator, where typical ambient fields of 0.2 mT are present at the sample stage. We discuss the effect of 100 mK and 500 mK Cu radiation shields and cryoperm magnetic shielding on resonator Q as a function of temperature and input power in samples prepared with a variety of surface treatments, fabrication recipes, and embedding circuits. This research was supported by the ARO and IARPA.

Program RECENT (version 79-1): reconstruction of energy-dependent neutron cross sections from resonance parameters in the ENDF/B format

International Nuclear Information System (INIS)

Cullen, D.E.

1979-01-01

Program RECENT reconstructs energy-dependent neutron total, elastic, capture, and fission cross sections from a combination of resonance parameters and tabulated background cross sections in the ENDF/B format. Entire evaluations, not just cross sections, are written to the result file, which is in ENDF/B format. The output includes the original resonance parameters in a form that can be used in Doppler broadening and self-shielding calculations. A listing of the source deck is available on request. 5 figures, 5 tables

Validation of calculated self-shielding factors for Rh foils

Science.gov (United States)

Jaćimović, R.; Trkov, A.; Žerovnik, G.; Snoj, L.; Schillebeeckx, P.

2010-10-01

Rhodium foils of about 5 mm diameter were obtained from IRMM. One foil had thickness of 0.006 mm and three were 0.112 mm thick. They were irradiated in the pneumatic transfer system and in the carousel facility of the TRIGA reactor at the Jožef Stefan Institute. The foils were irradiated bare and enclosed in small cadmium boxes (about 2 g weight) of 1 mm thickness to minimise the perturbation of the local neutron flux. They were co-irradiated with 5 mm diameter and 0.2 mm thick Al-Au (0.1%) alloy monitor foils. The resonance self-shielding corrections for the 0.006 and 0.112 mm thick samples were calculated by the Monte Carlo simulation and amount to about 10% and 60%, respectively. The consistency of measurements confirmed the validity of self-shielding factors. Trial estimates of Q0 and k0 factors for the 555.8 keV gamma line of 104Rh were made and amount to 6.65±0.18 and (6.61±0.12)×10 -2, respectively.

A study of the effect of intermediate structure in the fission cross section of 239Pu on self-shielding factors

International Nuclear Information System (INIS)

Ganesan, S.

1978-01-01

A set of energy dependent fission widths of 1 + spin state corresponding to the recommended fission cross sections of Sowerby et al is evaluated by adjustment in the energy region 600 ev to 25 Kev. Corresponding to these mean fission widths of 1 + spin state, the intermediate resonance parameters based on Weigmann's formulation of Struitinsky's double humped fission barrier model are then obtained. Pseudorandom resonances are generated with and without the intermediate structure in the mean fission but leading to the same value of infinite dilution fission cross section. The effect of the intermediate structure on the self shielding factors was then investigated. (author)

Neutron cross sections in the unresolved resonance region

International Nuclear Information System (INIS)

Janeva, N.; Lukyanov, A.; Koyumdjieva, N.; Volev, K.

2005-01-01

In this work a development of the characteristic function model, created to reveal the resonance cross section structure in the unresolved resonance region is presented. The main advantage of this model is the calculation of resonance averaged self-shielding factors analytically. To determine average values of the cross sections and their functionals the function of joint statistical distribution of the R-matrix real and imaginary parts should be used. The characteristic function of such distribution is determined and the resonance ladder for the unresolved region is optimized to calculate the group averaged functionals in the same way as it is in the resolved resonance region. The main advantage of this model is the calculation of resonance averaged self-shielding factors analytically. The neutron width energy dependence leads to some deformation in the shape of resonances. This deformation is most apparent near the inelastic scattering threshold. For the case when the inelastic channel momentum is zero we present the formula for level shape bellow and over the inelastic threshold and the calculated resonance deformation in dependence of the position of the resonance in respect to the threshold. (authors)

Application of the characteristics method combined with advanced self-shielding models to an ACR-type cell

International Nuclear Information System (INIS)

Le Tellier, R.; Hebert, A.

2005-01-01

In this paper, we present the usage of the method of characteristics (MOC) with advanced self-shielding models for a fundamental lattice calculation on an ACR-type cell i.e. a cluster geometry with light water coolant and heavy water moderator. Comparison with the collision probability method (CP) show the consistency of the method of characteristics as implemented both in flux and self-shielding calculations. Acceleration techniques are tested in the different calculations and prove to be efficient. Comparisons with the Monte-Carlo code Tripoli4 show the advantage of a subgroup approach for self-shielding calculations : the difference in k eff is less than one standard deviation of the Tripoli4 calculation and in terms of total absorption rates, in the resolved resonances group, the maximum relative error is of the order of 3% localised in the most outer region of the central pin. (author)

Self-shielding characteristics of aqueous self-cooled blankets for next generation fusion devices

International Nuclear Information System (INIS)

Pelloni, S.; Cheng, E.T.; Embrechts, M.J.

1987-11-01

The present study examines self-shielding characteristics for two aqueous self-cooled tritium producing driver blankets for next generation fusion devices. The aqueous Self-Cooled Blanket concept (ASCB) is a very simple blanket concept that relies on just structural material and coolant. Lithium compounds are dissolved in water to provide for tritium production. An ASCB driver blanket would provide a low technology and low temperature environment for blanket test modules in a next generation fusion reactor. The primary functions of such a blanket would be shielding, energy removal and tritium production. One driver blanket considered in this study concept relates to the one proposed for the Next European Torus (NET), while the second concept is indicative for the inboard shield design for the Engineering Test Reactor proposed by the USA (TIBER II/ETR). The driver blanket for NET is based on stainless steel for the structural material and aqueous solution, while the inboard shielding blanket for TIBER II/ETR is based on a tungsten/aqueous solution combination. The purpose of this study is to investigate self-shielding and heterogeneity effects in aqueous self-cooled blankets. It is found that no significant gains in tritium breeding can be achieved in the stainless steel blanket if spatial and energy self-shielding effects are considered, and the heterogeneity effects are also insignificant. The tungsten blanket shows a 5 percent increase in tritium production in the shielding blanket when energy and spatial self-shielding effects are accounted for. However, the tungsten blanket shows a drastic increase in the tritium breeding ratio due to heterogeneity effects. (author) 17 refs., 9 figs., 9 tabs

Use of a radio frequency shield during 1.5 and 3.0 Tesla magnetic resonance imaging: experimental evaluation

Directory of Open Access Journals (Sweden)

Favazza CP

2014-10-01

Full Text Available Christopher P Favazza, Deirdre M King, Heidi A Edmonson, Joel P Felmlee, Phillip J Rossman, Nicholas J Hangiandreou, Robert E Watson, Krzysztof R Gorny Department of Radiology, Mayo Clinic, Rochester, MN, USA Abstract: Radiofrequency (RF shields have been recently developed for the purpose of shielding portions of the patient's body during magnetic resonance imaging (MRI examinations. We present an experimental evaluation of a commercially available RF shield in the MRI environment. All tests were performed on 1.5 T and 3.0 T clinical MRI scanners. The tests were repeated with and without the RF shield present in the bore, for comparison. Effects of the shield, placed within the scanner bore, on the RF fields generated by the scanner were measured directly using tuned pick-up coils. Attenuation, by as much as 35 dB, of RF field power was found inside the RF shield. These results were supported by temperature measurements of metallic leads placed inside the shield, in which no measurable RF heating was found. In addition, there was a small, simultaneous detectable increase (~1 dB of RF power just outside the edges of the shield. For these particular scanners, the autocalibrated RF power levels were reduced for scan locations prescribed just outside the edges of the shield, which corresponded with estimations based on the pick-up coil measurements. Additionally, no significant heating during MRI scanning was observed on the shield surface. The impact of the RF shield on the RF fields inside the magnet bore is likely to be dependent on the particular model of the RF shield or the MRI scanner. These results suggest that the RF shield could be a valuable tool for clinical MRI practices. Keywords: radiofrequency shield, magnetic resonance imaging, radiofrequency attenuation

Performance of advanced self-shielding models in DRAGON Version4 on analysis of a high conversion light water reactor lattice

International Nuclear Information System (INIS)

Karthikeyan, Ramamoorthy; Hebert, Alain

2008-01-01

A high conversion light water reactor lattice has been analysed using the code DRAGON Version4. This analysis was performed to test the performance of the advanced self-shielding models incorporated in DRAGON Version4. The self-shielding models are broadly classified into two groups - 'equivalence in dilution' and 'subgroup approach'. Under the 'equivalence in dilution' approach we have analysed the generalized Stamm'ler model with and without Nordheim model and Riemann integration. These models have been analysed also using the Livolant-Jeanpierre normalization. Under the 'subgroup approach', we have analysed Statistical self-shielding model based on physical probability tables and Ribon extended self-shielding model based on mathematical probability tables. This analysis will help in understanding the performance of advanced self-shielding models for a lattice that is tight and has a large fraction of fissions happening in the resonance region. The nuclear data for the analysis was generated in-house. NJOY99.90 was used for generating libraries in DRAGLIB format for analysis using DRAGON and A Compact ENDF libraries for analysis using MCNP5. The evaluated datafiles were chosen based on the recommendations of the IAEA Co-ordinated Research Project on the WIMS Library Update Project. The reference solution for the problem was obtained using Monte Carlo code MCNP5. It was found that the Ribon extended self-shielding model based on mathematical probability tables using correlation model performed better than all other models

A lumped parameter method of characteristics approach and multigroup kernels applied to the subgroup self-shielding calculation in MPACT

International Nuclear Information System (INIS)

Stimpson, Shane G.; Liu, Yuxuan; Collins, Benjamin S.; Clarno, Kevin T.

2017-01-01

An essential component of the neutron transport solver is the resonance self-shielding calculation used to determine equivalence cross sections. The neutron transport code, MPACT, is currently using the subgroup self-shielding method, in which the method of characteristics (MOC) is used to solve purely absorbing fixed-source problems. Recent efforts incorporating multigroup kernels to the MOC solvers in MPACT have reduced runtime by roughly 2×. Applying the same concepts for self-shielding and developing a novel lumped parameter approach to MOC, substantial improvements have also been made to the self-shielding computational efficiency without sacrificing any accuracy. These new multigroup and lumped parameter capabilities have been demonstrated on two test cases: (1) a single lattice with quarter symmetry known as VERA (Virtual Environment for Reactor Applications) Progression Problem 2a and (2) a two-dimensional quarter-core slice known as Problem 5a-2D. From these cases, self-shielding computational time was reduced by roughly 3–4×, with a corresponding 15–20% increase in overall memory burden. An azimuthal angle sensitivity study also shows that only half as many angles are needed, yielding an additional speedup of 2×. In total, the improvements yield roughly a 7–8× speedup. Furthermore given these performance benefits, these approaches have been adopted as the default in MPACT.

A lumped parameter method of characteristics approach and multigroup kernels applied to the subgroup self-shielding calculation in MPACT

Directory of Open Access Journals (Sweden)

Shane Stimpson

2017-09-01

Full Text Available An essential component of the neutron transport solver is the resonance self-shielding calculation used to determine equivalence cross sections. The neutron transport code, MPACT, is currently using the subgroup self-shielding method, in which the method of characteristics (MOC is used to solve purely absorbing fixed-source problems. Recent efforts incorporating multigroup kernels to the MOC solvers in MPACT have reduced runtime by roughly 2×. Applying the same concepts for self-shielding and developing a novel lumped parameter approach to MOC, substantial improvements have also been made to the self-shielding computational efficiency without sacrificing any accuracy. These new multigroup and lumped parameter capabilities have been demonstrated on two test cases: (1 a single lattice with quarter symmetry known as VERA (Virtual Environment for Reactor Applications Progression Problem 2a and (2 a two-dimensional quarter-core slice known as Problem 5a-2D. From these cases, self-shielding computational time was reduced by roughly 3–4×, with a corresponding 15–20% increase in overall memory burden. An azimuthal angle sensitivity study also shows that only half as many angles are needed, yielding an additional speedup of 2×. In total, the improvements yield roughly a 7–8× speedup. Given these performance benefits, these approaches have been adopted as the default in MPACT.

Influence of resonance parameters' correlations on the resonance integral uncertainty; 55Mn case

International Nuclear Information System (INIS)

Zerovnik, Gasper; Trkov, Andrej; Capote, Roberto; Rochman, Dimitri

2011-01-01

For nuclides with a large number of resonances the covariance matrix of resonance parameters can become very large and expensive to process in terms of the computation time. By converting covariance matrix of resonance parameters into covariance matrices of background cross-section in a more or less coarse group structure a considerable amount of computer time and memory can be saved. The question is how important is the information that is discarded in the process. First, the uncertainty of the 55 Mn resonance integral was estimated in narrow resonance approximation for different levels of self-shielding using Bondarenko method by random sampling of resonance parameters according to their covariance matrices from two different 55 Mn evaluations: one from Nuclear Research and Consultancy Group NRG (with large uncertainties but no correlations between resonances), the other from Oak Ridge National Laboratory (with smaller uncertainties but full covariance matrix). We have found out that if all (or at least significant part of the) resonance parameters are correlated, the resonance integral uncertainty greatly depends on the level of self-shielding. Second, it was shown that the commonly used 640-group SAND-II representation cannot describe the increase of the resonance integral uncertainty. A much finer energy mesh for the background covariance matrix would have to be used to take the resonance structure into account explicitly, but then the objective of a more compact data representation is lost.

A Wavelet-Based Finite Element Method for the Self-Shielding Issue in Neutron Transport

International Nuclear Information System (INIS)

Le Tellier, R.; Fournier, D.; Ruggieri, J. M.

2009-01-01

This paper describes a new approach for treating the energy variable of the neutron transport equation in the resolved resonance energy range. The aim is to avoid recourse to a case-specific spatially dependent self-shielding calculation when considering a broad group structure. This method consists of a discontinuous Galerkin discretization of the energy using wavelet-based elements. A Σ t -orthogonalization of the element basis is presented in order to make the approach tractable for spatially dependent problems. First numerical tests of this method are carried out in a limited framework under the Livolant-Jeanpierre hypotheses in an infinite homogeneous medium. They are mainly focused on the way to construct the wavelet-based element basis. Indeed, the prior selection of these wavelet functions by a thresholding strategy applied to the discrete wavelet transform of a given quantity is a key issue for the convergence rate of the method. The Canuto thresholding approach applied to an approximate flux is found to yield a nearly optimal convergence in many cases. In these tests, the capability of such a finite element discretization to represent the flux depression in a resonant region is demonstrated; a relative accuracy of 10 -3 on the flux (in L 2 -norm) is reached with less than 100 wavelet coefficients per group. (authors)

Self-Shielding Of Transmission Lines

Energy Technology Data Exchange (ETDEWEB)

Christodoulou, Christos [Univ. of New Mexico, Albuquerque, NM (United States)

2017-03-01

The use of shielding to contend with noise or harmful EMI/EMR energy is not a new concept. An inevitable trade that must be made for shielding is physical space and weight. Space was often not as much of a painful design trade in older larger systems as they are in today’s smaller systems. Today we are packing in an exponentially growing number of functionality within the same or smaller volumes. As systems become smaller and space within systems become more restricted, the implementation of shielding becomes more problematic. Often, space that was used to design a more mechanically robust component must be used for shielding. As the system gets smaller and space is at more of a premium, the trades starts to result in defects, designs with inadequate margin in other performance areas, and designs that are sensitive to manufacturing variability. With these challenges in mind, it would be ideal to maximize attenuation of harmful fields as they inevitably couple onto transmission lines without the use of traditional shielding. Dr. Tom Van Doren proposed a design concept for transmission lines to a class of engineers while visiting New Mexico. This design concept works by maximizing Electric field (E) and Magnetic Field (H) field containment between operating transmission lines to achieve what he called “Self-Shielding”. By making the geometric centroid of the outgoing current coincident with the return current, maximum field containment is achieved. The reciprocal should be true as well, resulting in greater attenuation of incident fields. Figure’s 1(a)-1(b) are examples of designs where the current centroids are coincident. Coax cables are good examples of transmission lines with co-located centroids but they demonstrate excellent field attenuation for other reasons and can’t be used to test this design concept. Figure 1(b) is a flex circuit design that demonstrate the implementation of self-shielding vs a standard conductor layout.

MPACT Subgroup Self-Shielding Efficiency Improvements

International Nuclear Information System (INIS)

Stimpson, Shane; Liu, Yuxuan; Collins, Benjamin S.; Clarno, Kevin T.

2016-01-01

Recent developments to improve the efficiency of the MOC solvers in MPACT have yielded effective kernels that loop over several energy groups at once, rather that looping over one group at a time. These kernels have produced roughly a 2x speedup on the MOC sweeping time during eigenvalue calculation. However, the self-shielding subgroup calculation had not been reevaluated to take advantage of these new kernels, which typically requires substantial solve time. The improvements covered in this report start by integrating the multigroup kernel concepts into the subgroup calculation, which are then used as the basis for further extensions. The next improvement that is covered is what is currently being termed as ''Lumped Parameter MOC''. Because the subgroup calculation is a purely fixed source problem and multiple sweeps are performed only to update the boundary angular fluxes, the sweep procedure can be condensed to allow for the instantaneous propagation of the flux across a spatial domain, without the need to sweep along all segments in a ray. Once the boundary angular fluxes are considered to be converged, an additional sweep that will tally the scalar flux is completed. The last improvement that is investigated is the possible reduction of the number of azimuthal angles per octant in the shielding sweep. Typically 16 azimuthal angles per octant are used for self-shielding and eigenvalue calculations, but it is possible that the self-shielding sweeps are less sensitive to the number of angles than the full eigenvalue calculation.

Monte Carlo validation of self shielding and void effect calculations

International Nuclear Information System (INIS)

Tellier, H.; Coste, M.; Raepsaet, C.; Soldevila, M.; Van der Gucht, C.

1995-01-01

The self shielding validation and the void effect are studied with Monte Carlo method. The satisfactory comparison obtained between the APOLLO 2 results of the self shielding effect and the TRIPOLI and MCNP results allows us to be confident in the multigroup transport code. (K.A.)

A Modeling of BWR-MOX assemblies based on the characteristics method combined with advanced self-shielding models

International Nuclear Information System (INIS)

Le Tellier, R.; Hebert, A.; Le Tellier, R.; Santamarina, A.; Litaize, O.

2008-01-01

Calculations based on the characteristics method and different self-shielding models are presented for 9 x 9 boiling water reactor (BWR) assemblies fully loaded with mixed-oxide (MOX) fuel. The geometry of these assemblies was recovered from the BASALA experimental program. We have focused our study on three configurations simulating the different voiding conditions that an assembly can undergo in a BWR pressure vessel. A parametric study was carried out with respect to the spatial discretization, the tracking parameters, and the anisotropy order. Comparisons with Monte Carlo calculations in terms of k eff , radiative capture, and fission rates were performed to validate the computational tools. The results are in good agreement between the stochastic and deterministic approaches. The mutual self-shielding model recently introduced within the framework of the Ribon extending self-shielding method appears to be useful for this type of assemblies. Indeed, in the calculation of these MOX benchmarks, the overlapping of resonances, especially between 238 U and 240 Pu, plays an important role due to the spectral strengthening of the flux as the voiding percentage is increased. The method of characteristics is shown to be adequate to perform accurate calculations handling a fine spatial discretization. (authors)

Self-shielding for thick slabs in a converging neutron beam

CERN Document Server

Mildner, D F R

1999-01-01

We have previously given a correction to the neutron self-shielding for a thin slab to account for the increased average path length through the slab when irradiated in a converging neutron beam. This expression overstates the case for the self-shielding for a thick (or highly absorbing) slab. We give a better approximation to the increase in effective shielding correction for a slab placed in a converging neutron beam. It is negligible at large absorption mean free paths. (author)

Measurements and Monte-Carlo simulations of the particle self-shielding effect of B4C grains in neutron shielding concrete

Science.gov (United States)

DiJulio, D. D.; Cooper-Jensen, C. P.; Llamas-Jansa, I.; Kazi, S.; Bentley, P. M.

2018-06-01

A combined measurement and Monte-Carlo simulation study was carried out in order to characterize the particle self-shielding effect of B4C grains in neutron shielding concrete. Several batches of a specialized neutron shielding concrete, with varying B4C grain sizes, were exposed to a 2 Å neutron beam at the R2D2 test beamline at the Institute for Energy Technology located in Kjeller, Norway. The direct and scattered neutrons were detected with a neutron detector placed behind the concrete blocks and the results were compared to Geant4 simulations. The particle self-shielding effect was included in the Geant4 simulations by calculating effective neutron cross-sections during the Monte-Carlo simulation process. It is shown that this method well reproduces the measured results. Our results show that shielding calculations for low-energy neutrons using such materials would lead to an underestimate of the shielding required for a certain design scenario if the particle self-shielding effect is not included in the calculations.

Heavy nucleus resonant absorption calculation benchmarks

International Nuclear Information System (INIS)

Tellier, H.; Coste, H.; Raepsaet, C.; Van der Gucht, C.

1993-01-01

The calculation of the space and energy dependence of the heavy nucleus resonant absorption in a heterogeneous lattice is one of the hardest tasks in reactor physics. Because of the computer time and memory needed, it is impossible to represent finely the cross-section behavior in the resonance energy range for everyday computations. Consequently, reactor physicists use a simplified formalism, the self-shielding formalism. As no clean and detailed experimental results are available to validate the self-shielding calculations, Monte Carlo computations are used as a reference. These results, which were obtained with the TRIPOLI continuous-energy Monte Carlo code, constitute a set of numerical benchmarks than can be used to evaluate the accuracy of the techniques or formalisms that are included in any reactor physics codes. Examples of such evaluations, for the new assembly code APOLLO2 and the slowing-down code SECOL, are given for cases of 238 U and 232 Th fuel elements

Set up of a method for the adjustment of resonance parameters on integral experiments; Mise au point d`une methode d`ajustement des parametres de resonance sur des experiences integrales

Energy Technology Data Exchange (ETDEWEB)

Blaise, P.

1996-12-18

Resonance parameters for actinides play a significant role in the neutronic characteristics of all reactor types. All the major integral parameters strongly depend on the nuclear data of the isotopes in the resonance-energy regions.The author sets up a method for the adjustment of resonance parameters taking into account the self-shielding effects and restricting the cross section deconvolution problem to a limited energy region. (N.T.).

Neutron flux calculations for criticality safety analysis using the narrow resonance approximations. Vol. 2

Energy Technology Data Exchange (ETDEWEB)

Hathout, A M [National Center for Nuclear Safety and Radiation Control, NC-NSRC, Atomic Energy Authority, Cairo (Egypt)

1996-03-01

The narrow resonance approximation is applicable for all low-energy resonances and the heaviest nuclides. It is of great importance in neutron calculations, hence, fertile isotopes do not undergo fission at resonance energies. The effect of overestimating the self shielded group averaged cross-section data for a given resonance nuclide can be fairly serious. In the present work, a detailed study, and derivation of the problem of self-shielding are carried-out through the information of Hansen-roach library which is used for criticality safety analysis. The intermediate neutron flux spectrum is analyzed, using the narrow resonance approximation. The resonance self-shielded values of various cross-sections are determined. 4 figs., 3 tabs.

Enhancement of thermal neutron self-shielding in materials surrounded by reflectors

International Nuclear Information System (INIS)

Cornelia Chilian; Gregory Kennedy

2012-01-01

Materials containing from 41 to 1124 mg chlorine and surrounded by polyethylene containers of various thicknesses, from 0.01 to 5.6 mm, were irradiated in a research reactor neutron spectrum and the 38 Cl activity produced was measured as a function of polyethylene reflector thickness. For the material containing the higher amount of chlorine, the 38 Cl specific activity decreased with increasing reflector thickness, indicating increased neutron self-shielding. It was found that the amount of neutron self-shielding increased by as much as 52% with increasing reflector thickness. This is explained by neutrons which have exited the material subsequently reflecting back into it and thus increasing the total mean path length in the material. All physical and empirical models currently used to predict neutron self-shielding have ignored this effect and need to be modified. A method is given for measuring the adjustable parameter of a self-shielding model for a particular sample size and combination of neutron reflectors. (author)

Study on 2D arbitrary geometry coupling resonance method

International Nuclear Information System (INIS)

He Lei; Wu Hongchun; Cao Liangzhi

2014-01-01

The paper firstly proposes a coupling resonance method in which subgroup method is employed in the serried peak energy region, and wavelet expansion method is employed in single peak energy region. The original subgroup model and wavelet expansion model are improved and coupled through the calculation of scattering source from subgroup to wavelet expansion, so that the self-shielding cross section in the whole energy region can be calculated accurately. To verify these theories and to prove the improvements, a PWR cell benchmark problem is calculated. It is demonstrated that, compared with other traditional multi-group resonance methods and continuous energy resonance method, this coupling resonance method has the ability to accurately calculate the whole energy region's self-shielding cross section while Keeping enough efficiency and finally has an ability to offer the accurate self-shielding parameters for latter transport, calculation. (authors)

Set up of a method for the adjustment of resonance parameters on integral experiments

International Nuclear Information System (INIS)

Blaise, P.

1996-01-01

Resonance parameters for actinides play a significant role in the neutronic characteristics of all reactor types. All the major integral parameters strongly depend on the nuclear data of the isotopes in the resonance-energy regions.The author sets up a method for the adjustment of resonance parameters taking into account the self-shielding effects and restricting the cross section deconvolution problem to a limited energy region. (N.T.)

Use of a radio frequency shield during 1.5 and 3.0 Tesla magnetic resonance imaging: experimental evaluation.

Science.gov (United States)

Favazza, Christopher P; King, Deirdre M; Edmonson, Heidi A; Felmlee, Joel P; Rossman, Phillip J; Hangiandreou, Nicholas J; Watson, Robert E; Gorny, Krzysztof R

2014-01-01

Radiofrequency (RF) shields have been recently developed for the purpose of shielding portions of the patient's body during magnetic resonance imaging (MRI) examinations. We present an experimental evaluation of a commercially available RF shield in the MRI environment. All tests were performed on 1.5 T and 3.0 T clinical MRI scanners. The tests were repeated with and without the RF shield present in the bore, for comparison. Effects of the shield, placed within the scanner bore, on the RF fields generated by the scanner were measured directly using tuned pick-up coils. Attenuation, by as much as 35 dB, of RF field power was found inside the RF shield. These results were supported by temperature measurements of metallic leads placed inside the shield, in which no measurable RF heating was found. In addition, there was a small, simultaneous detectable increase (∼1 dB) of RF power just outside the edges of the shield. For these particular scanners, the autocalibrated RF power levels were reduced for scan locations prescribed just outside the edges of the shield, which corresponded with estimations based on the pick-up coil measurements. Additionally, no significant heating during MRI scanning was observed on the shield surface. The impact of the RF shield on the RF fields inside the magnet bore is likely to be dependent on the particular model of the RF shield or the MRI scanner. These results suggest that the RF shield could be a valuable tool for clinical MRI practices.

Revisiting the stamm'ler self-shielding method

International Nuclear Information System (INIS)

Hebert, A.

2004-01-01

The generalized Stamm'ler method is been used in lattice codes such as PHOENIX, WIMS-AECL and DRAGON-IST for computing self-shielded cross sections, prior to the main flux calculation. This method is handicapped by deficiencies, such as its low accuracy and its inability to represent distributed self-shielding effects in a fuel rod or across a fuel bundle. The paper describes improvements that could be made to the generalized Stamm'ler method in order to mitigate these two defects. A validation is presented for the case of 238 U nuclides located in different geometries. The isotopic absorption rates obtained with the proposed numerical scheme are compared with exact values obtained with a fine-group elastic slowing-down calculation in the resolved energy domain. (author)

Validation of a new 39 neutron group self-shielded library based on the nucleonics analysis of the Lotus fusion-fission hybrid test facility performed with the Monte Carlo code

International Nuclear Information System (INIS)

Pelloni, S.; Cheng, E.T.

1985-02-01

The Swiss LOTUS fusion-fission hybrid test facility was used to investigate the influence of the self-shielding of resonance cross sections on the tritium breeding and on the thorium ratios. Nucleonic analyses were performed using the discrete-ordinates transport codes ANISN and ONEDANT, the surface-flux code SURCU, and the version 3 of the MCNP code for the Li 2 CO 3 and the Li 2 O blanket designs with lead, thorium and beryllium multipliers. Except for the MCNP calculation which bases on the ENDF/B-V files, all nuclear data are generated from the ENDF/B-IV basic library. For the deterministic methods three NJOY group libraries were considered. The first, a 39 neutron group self-shielded library, was generated at EIR. The second bases on the same group structure as the first does and consists of infinitely diluted cross sections. Finally the third library was processed at LANL and consists of coupled 30+12 neutron and gamma groups; these cross sections are not self-shielded. The Monte Carlo analysis bases on a continuous and on a discrete 262 group library from the ENDF/B-V evaluation. It is shown that the results agree well within 3% between the unshielded libraries and between the different transport codes and theories. The self-shielding of resonance cross sections results in a decrease of the thorium capture rate and in an increase of the tritium breeding of about 6%. The remaining computed ratios are not affected by the self-shielding of cross sections. (Auth.)

Neutron self-shielding with k0-NAA irradiations

International Nuclear Information System (INIS)

Chilian, C.; Chambon, R.; Kennedy, G.

2010-01-01

A sample of SMELS Type II reference material was mixed with powdered Cd-nitrate neutron absorber and analysed by k 0 NAA for 10 elements. The thermal neutron self-shielding effect was found to be 34.8%. When flux monitors were irradiated sufficiently far from the absorbing sample, it was found that the self-shielding could be corrected accurately using an analytical formula and an iterative calculation. When the flux monitors were irradiated 2 mm from the absorbing sample, the calculations over-corrected the concentrations by as much as 30%. It is recommended to irradiate flux monitors at least 14 mm from a 10 mm diameter absorbing sample.

Self shielding in cylindrical fissile sources in the APNea system

International Nuclear Information System (INIS)

Hensley, D.

1997-01-01

In order for a source of fissile material to be useful as a calibration instrument, it is necessary to know not only how much fissile material is in the source but also what the effective fissile content is. Because uranium and plutonium absorb thermal neutrons so Efficiently, material in the center of a sample is shielded from the external thermal flux by the surface layers of the material. Differential dieaway measurements in the APNea System of five different sets of cylindrical fissile sources show the various self shielding effects that are routinely encountered. A method for calculating the self shielding effect is presented and its predictions are compared with the experimental results

The effect of the 238U neutron strength function uncertainty on resonance structure calculations in unresolved regions

International Nuclear Information System (INIS)

Koshcheev, V.N.; Manturov, G.N.; Sinitsa, V.V.

1991-01-01

The effects of the neutron strength function uncertainties on the calculated values of the self-shielding factors and energy dependence of the total and capture 238 U cross-sections in the unresolved resonance region are investigated. (author). 26 refs, 5 figs

Self-shielding phenomenon modelling in multigroup transport code Apollo-2; Modelisation du phenomene d'autoprotection dans le code de transport multigroupe Apollo 2

Energy Technology Data Exchange (ETDEWEB)

Coste-Delclaux, M

2006-03-15

This document describes the improvements carried out for modelling the self-shielding phenomenon in the multigroup transport code APOLLO2. They concern the space and energy treatment of the slowing-down equation, the setting up of quadrature formulas to calculate reaction rates, the setting-up of a method that treats directly a resonant mixture and the development of a sub-group method. We validate these improvements either in an elementary or in a global way. Now, we obtain, more accurate multigroup reaction rates and we are able to carry out a reference self-shielding calculation on a very fine multigroup mesh. To end, we draw a conclusion and give some prospects on the remaining work. (author)

Self-shielding phenomenon modelling in multigroup transport code Apollo-2; Modelisation du phenomene d'autoprotection dans le code de transport multigroupe Apollo 2

Energy Technology Data Exchange (ETDEWEB)

Coste-Delclaux, M

2006-03-15

This document describes the improvements carried out for modelling the self-shielding phenomenon in the multigroup transport code APOLLO2. They concern the space and energy treatment of the slowing-down equation, the setting up of quadrature formulas to calculate reaction rates, the setting-up of a method that treats directly a resonant mixture and the development of a sub-group method. We validate these improvements either in an elementary or in a global way. Now, we obtain, more accurate multigroup reaction rates and we are able to carry out a reference self-shielding calculation on a very fine multigroup mesh. To end, we draw a conclusion and give some prospects on the remaining work. (author)

Self-shielding coefficient and thermal flux depression factor of voluminous sample in neutron activation analysis

International Nuclear Information System (INIS)

Noorddin Ibrahim; Rosnie Akang

2009-01-01

Full text: One of the major problems encountered during the irradiation of large inhomogeneous samples in performing activation analysis using neutron is the perturbation of the neutron field due to absorption and scattering of neutron within the sample as well as along the neutron guide in the case of prompt gamma activation analysis. The magnitude of this perturbation shown by self-shielding coefficient and flux depression depend on several factors including the average neutron energy, the size and shape of the sample, as well as the macroscopic absorption cross section of the sample. In this study, we use Monte Carlo N-Particle codes to simulate the variation of neutron self-shielding coefficient and thermal flux depression factor as a function of the macroscopic thermal absorption cross section. The simulation works was carried out using the high performance computing facility available at UTM while the experimental work was performed at the tangential beam port of Reactor TRIGA PUSPATI, Malaysia Nuclear Agency. The neutron flux measured along the beam port is found to be in good agreement with the simulated data. Our simulation results also reveal that total flux perturbation factor decreases as the value of absorption increases. This factor is close to unity for low absorbing sample and tends towards zero for strong absorber. In addition, sample with long mean chord length produces smaller flux perturbation than the shorter mean chord length. When comparing both the graphs of self-shielding factor and total disturbance, we can conclude that the total disturbance of the thermal neutron flux on the large samples is dominated by the self-shielding effect. (Author)

Gamma self-shielding correction factors calculation for aqueous bulk sample analysis by PGNAA technique

International Nuclear Information System (INIS)

Nasrabadi, M.N.; Mohammadi, A.; Jalali, M.

2009-01-01

In this paper bulk sample prompt gamma neutron activation analysis (BSPGNAA) was applied to aqueous sample analysis using a relative method. For elemental analysis of an unknown bulk sample, gamma self-shielding coefficient was required. Gamma self-shielding coefficient of unknown samples was estimated by an experimental method and also by MCNP code calculation. The proposed methodology can be used for the determination of the elemental concentration of unknown aqueous samples by BSPGNAA where knowledge of the gamma self-shielding within the sample volume is required.

MINX, Multigroup Cross-Sections and Self-Shielding Factors from ENDF/B for Program SPHINX

International Nuclear Information System (INIS)

Soran, P.D.; MacFarlane, R.E.; Harris, D.R.; LaBauve, R.J.; Hendricks, J.S.; Kidman, R.B.; Weisbin, C.R.; White, J.E.

1977-01-01

1 - Description of problem or function: MINX calculates fine-group averaged infinitely diluted cross sections and self-shielding factors from ENDF/B-IV data. Its primary purpose is to generate a pseudo-composition-independent multigroup library which is input to the SPHINX space-energy collapse program (2) (PSR-0129) through standard CCCC-III (8) interfaces. MINX incorporates and improves upon the resonance capabilities of existing codes such as ETOX (5) (NESC0388) and ENDRUN (9) and the high-order group-to-group transfer matrices of SUPERTOG (10) (PSR-0013) and ETOG (11). Fine group energy boundaries, Legendre expansion order, gross spectral shape component (in the Bondarenko flux model), temperatures and dilutions can all be used specifically. 2 - Method of solution: Infinitely dilute, un-broadened point cross sections are obtained from resolved resonance parameters using a modified version of the RESEND program (3) (NESC0465). The SIGMA1 (4) (IAEA0854) kernel-broadening method is used to Doppler broaden and thin the tabulated linearized pointwise cross sections at 0 K (outside of the unresolved energy region). Effective temperature- dependent self-shielded pointwise cross sections are derived from the formulation in the ETOX code. The primary modification to the ETOX algorithm is associated with the numerical quadrature scheme used to establish the mean values of the fluctuation intervals. The selection of energy mesh points, at which the effective cross sections are calculated, has been modified to include the energy points given in the ENDF/B file or, if the energy-independent formalism was employed, points at half-lethargy intervals. Infinitely dilute group cross sections and self-shielding factors are generated using the Bondarenko flux weighting model with the gross spectral shape under user control. The integral over energy for each group is divided into a set of panels defined by the union of the grid points describing the total cross section, the

ICRF antenna Faraday shield plasma sheath model

International Nuclear Information System (INIS)

Whealton, J.H.; Ryan, P.M.; Raridon, R.J.

1990-01-01

A two-dimensional nonlinear formulation that explicitly considers the plasma edge near a Faraday shield in a self-consistent manner is used in the modeling of the ion motion for a Faraday shield concept and model suggested by Perkins. Two models are considered that may provide significant insight into the generation of impurities for ion cyclotron resonance heating (ICRH) antennas. In one of these models a significant sheath periodically forms next to the Faraday screen, with ion acoustic waves heating the ions in the plasma. (orig.)

Determination of self shielding factors and gamma attenuation effects for tree ring samples

International Nuclear Information System (INIS)

Dagistan Sahin; Kenan Uenlue

2012-01-01

Determination of tree ring chemistry using Neutron Activation Analysis (NAA) is part of an ongoing research between Penn State University (PSU) and Cornell University, The Malcolm and Carolyn Wiener Laboratory for Aegean and Near Eastern Dendrochronology. Tree-ring chemistry yields valuable data for environmental event signatures. These signatures are a complex function of elemental concentration. To be certain about concentration of signature elements, it is necessary to perform the measurements and corrections with the lowest error and maximum accuracy possible. Accurate and precise values of energy dependent neutron flux at dry irradiation tubes and detector efficiency for tree ring sample are calculated for Penn State Breazeale Reactor (PSBR). For the calculation of energy dependent and self shielding corrected neutron flux, detailed model of the TRIGA Mark III reactor at PSU with updated fuel compositions was prepared using the MCNP utility for reactor evolution (MURE) libraries. Dry irradiation tube, sample holder and sample were also included in the model. The thermal flux self-shielding correction factors due to the sample holder and sample for were calculated and verified with previously published values. The Geant-4 model of the gamma spectroscopy system, developed at Radiation Science and Engineering Center (RSEC), was improved and absolute detector efficiency for tree-ring samples was calculated. (author)

Comparative study on the use of self-shielded packages or returnable shielding for the land disposal of radioactive wastes

International Nuclear Information System (INIS)

Fitzpatrick, J.; Verrall, S.M.

1985-01-01

A comparative study has been carried out on the two philosophies for providing the radiological protection necessary for the transport and handling of packaged intermediate level wastes from their sites of origin to disposal. The two philosophies are self shielding and returnable shielding. The approach taken was to assess the cost and radiological impact differentials of two respective representative waste management procedures. The comparison indicated the merits of each procedure. As a consequence, a hybrid procedure was identified which combines the advantages of each philosophy. This hybrid procedure was used for further comparison. The results of the study indicate that the use of self shielded packages throughout will incur considerable extra expense and give only a small saving in radiological impact. (author)

Theory of neutron resonance cross sections for safety applications

International Nuclear Information System (INIS)

Froehner, F.H.

1992-09-01

Neutron resonances exert a strong influence on the behaviour of nuclear reactors, especially on their response to the temperature changes accompanying power excursions, and also on the efficiency of shielding materials. The relevant theory of neutron resonance cross sections including the practically important approximations is reviewed, both for the resolved and the unresolved resonance region. Numerical techniques for Doppler broadening of resonances are presented, and the construction of group constants and especially of self-shielding factors for neutronics calculations is outlined. (orig.) [de

GROUPIE2007, Bondarenko Self-Shielded Cross sections from ENDF/B

International Nuclear Information System (INIS)

2007-01-01

1 - Description of problem or function - GROUPIE reads evaluated data in ENDF/B Format and uses these to calculate unshielded group averaged Cross sections, Bondarenko self-shielded Cross sections, and multiband parameters. The program allows the user to specify arbitrary energy groups and an arbitrary energy-dependent neutron spectrum (weighting function). IAEA0849/15: This version include the updates up to January 30, 2007. Changes in ENDF/B-VII Format and procedures, as well as the evaluations themselves, make it impossible for versions of the ENDF/B pre-processing codes earlier than PREPRO 2007 (2007 Version) to accurately process current ENDF/B-VII evaluations. The present code can handle all existing ENDF/B-VI evaluations through release 8, which will be the last release of ENDF/B-VI. 2 - Modifications from previous versions: Groupie VERS. 2007-1 (Jan. 2007): checked against all ENDF/B-VII; increased page size from 120,000 to 600,000 points. 3 - Method of solution: All integrals are performed analytically; in no case is iteration or any approximate form of integration used. GROUPIE reads either the 0 deg. Kelvin Cross sections or the Doppler broadened Cross sections to calculate the self-shielded Cross sections and multiband parameters for 25 values of the 'background' Cross sections (representing the combined effects of all other isotopes and of leakage). 4 - Restrictions on the complexity of the problem: GROUPIE requires that the energy-dependent neutron spectrum and all Cross sections be given in tabular form, with linear interpolation between tabulated values. There is no limit to the size of the table used to describe the spectrum, so the spectrum may be described in as much detail as required. - If only unshielded averages are calculated, the program can handle up to 3000 groups. If self-shielded averages and/or multiband parameters are calculated, the program can handle up to 175 groups. These limits can easily be extended. - The program only uses the

Computing Moment-Based Probability Tables for Self-Shielding Calculations in Lattice Codes

International Nuclear Information System (INIS)

Hebert, Alain; Coste, Mireille

2002-01-01

As part of the self-shielding model used in the APOLLO2 lattice code, probability tables are required to compute self-shielded cross sections for coarse energy groups (typically with 99 or 172 groups). This paper describes the replacement of the multiband tables (typically with 51 subgroups) with moment-based tables in release 2.5 of APOLLO2. An improved Ribon method is proposed to compute moment-based probability tables, allowing important savings in CPU resources while maintaining the accuracy of the self-shielding algorithm. Finally, a validation is presented where the absorption rates obtained with each of these techniques are compared with exact values obtained using a fine-group elastic slowing-down calculation in the resolved energy domain. Other results, relative to the Rowland's benchmark and to three assembly production cases, are also presented

Radiation monitoring in a self-shielded cyclotron installation

International Nuclear Information System (INIS)

Capaccioli, L.; Gori, C.; Mazzocchi, S.; Spano, G.

2002-01-01

As nuclear medicine is approaching a new era with the spectacular growth of PET diagnosis, the number of medical cyclotrons installed within the major hospitals is increasing accordingly. Therefore modern medical cyclotron are highly engineered and highly reliable apparatus, characterised with reduced accelerating energies (as the major goal is the production of fluorine 18) and often self-shielded. However specific dedicated monitors are still necessary in order to assure the proper radioprotection. At the Careggi University Hospital in Florence a Mini trace 10 MeV self-shielded cyclotron produced by General Electric has been installed in 2000. In a contiguous radiochemistry laboratory, the preparation and quality control of 1 8F DG and other radiopharmaceuticals takes place. Aim of this work is the characterisation and the proper calibration of the above mentioned monitors and control devices

License Application Design Selection Feature Report: Waste Package Self Shielding Design Feature 13

International Nuclear Information System (INIS)

Tang, J.S.

2000-01-01

In the Viability Assessment (VA) reference design, handling of waste packages (WPs) in the emplacement drifts is performed remotely, and human access to the drifts is precluded when WPs are present. This report will investigate the feasibility of using a self-shielded WP design to reduce the radiation levels in the emplacement drifts to a point that, when coupled with ventilation, will create an acceptable environment for human access. This provides the benefit of allowing human entry to emplacement drifts to perform maintenance on ground support and instrumentation, and carry out performance confirmation activities. More direct human control of WP handling and emplacement operations would also be possible. However, these potential benefits must be weighed against the cost of implementation, and potential impacts on pre- and post-closure performance of the repository and WPs. The first section of this report will provide background information on previous investigations of the self-shielded WP design feature, summarize the objective and scope of this document, and provide quality assurance and software information. A shielding performance and cost study that includes several candidate shield materials will then be performed in the subsequent section to allow selection of two self-shielded WP design options for further evaluation. Finally, the remaining sections will evaluate the impacts of the two WP self-shielding options on the repository design, operations, safety, cost, and long-term performance of the WPs with respect to the VA reference design

Iterative resonance self-shielding methods using resonance integral table in heterogeneous transport lattice calculations

International Nuclear Information System (INIS)

Hong, Ser Gi; Kim, Kang-Seog

2011-01-01

This paper describes the iteration methods using resonance integral tables to estimate the effective resonance cross sections in heterogeneous transport lattice calculations. Basically, these methods have been devised to reduce an effort to convert resonance integral table into subgroup data to be used in the physical subgroup method. Since these methods do not use subgroup data but only use resonance integral tables directly, these methods do not include an error in converting resonance integral into subgroup data. The effective resonance cross sections are estimated iteratively for each resonance nuclide through the heterogeneous fixed source calculations for the whole problem domain to obtain the background cross sections. These methods have been implemented in the transport lattice code KARMA which uses the method of characteristics (MOC) to solve the transport equation. The computational results show that these iteration methods are quite promising in the practical transport lattice calculations.

Self Shielding in Nuclear Fissile Assay Using LSDS

International Nuclear Information System (INIS)

Lee, Yong Deok; Park, Chang Je; Park, Geun Il; Song, Kee Chan

2012-01-01

The new technology for isotopic fissile material contents assay is under development at KAERI using lead slowing down spectrometer(LSDS). LSDS is very sensitive to distinguish fission signals from each fissile isotope in spent and recycled fuel. The accumulation of spent fuel is current big issue. The amount of spent fuels will reach the maximum storage capacity of the pools soon. Therefore, an interim storage must be searched and it should be optimized in design by applying accurate fissile content. When the storage has taken effect, all the nuclear materials must be also specified and verified for safety, economics and management. Generally, the spent fuel from PWR has unburned ∼1 % U235, produced ∼0.5 % plutonium from decay chain, ∼3 % fission products, ∼ 0.1 % minor actinides (MA) and uranium remainder. About 1.5 % fissile materials still exist in the spent fuel. Therefore, for reutilization of fissile materials in spent fuel at SFR, resource material is produced through pyro process. Fissile material contents in resource material must be analyzed before fabricating SFR fuel for reactor safety and economics. In assay of fissile content of spent fuel and recycled fuel, intense radiation background gives limitation on the direct analysis of fissile materials. However, LSDS is not influenced by such a radiation background in fissile assay. Based on the decided geometry setup, self shielding parameter was calculated at the fuel assay zone by introducing spent fuel or pyro produced nuclear material. When nuclear material is inserted into the assay area, the spent fuel assembly or pyro recycled fuel material perturbs the spatial distribution of the slowing down neutrons in lead and the prompt fast fission neutrons produced by fissile materials are also perturbed. The self shielding factor is interpreted as that how much of absorption is created inside the fuel area when it is in the lead. Self shielding effect provides a non-linear property in the isotopic

Properties and applications of HTS-shielded dielectric resonators: A state-of-the-art report

International Nuclear Information System (INIS)

Klein, N.; Scholen, A.; Tellmann, N.; Zuccaro, C.; Urban, K.W.

1996-01-01

High temperature superconductor (HTS) shielded dielectric resonators (DRs) have demonstrated to provide quality factors Q between 5 x 10 5 and several 10 6 at frequencies up to 20 GHz and levels of dissipated rf power in the range of Watts. As dielectric materials, high purity single crystals of sapphire, LaAlO 3 , and rutile exhibit sufficiently low microwave losses. There are two main areas of application which are considered to benefit from HTS-shielded DRs, namely low-phase-noise oscillators for radar systems and digital communication, and high-power filters for satellite communication. Projections for phase noise are -145 dBc/Hz at 1 kHz offset from the carrier frequency, a value of -110 dBc/Hz at 1 kHz was measured recently for an oscillator with a carrier frequency of 5.6 GHz. Modeling of filters based on resonators with Qs in the 10 6 range indicates their ability to reduce the rf power dissipation apparent in the output multiplexers of communication satellite payloads. Presently, schemes for resonator coupling and tuning while maintaining high Qs are under development

An ''exact'' treatment of self-shielding and covers in neutron spectra determinations

International Nuclear Information System (INIS)

Griffin, P.J.; Kelly, J.G.

1995-01-01

Most neutron spectrum determination methodologies ignore self-shielding effects in dosimetry foils and treat covers with an exponential attenuation model. This work provides a quantitative analysis of the approximations in this approach. It also provides a methodology for improving the fidelity of the treatment of the dosimetry sensor response to a level consistent with the user's spectrum characterization approach. A library of correction functions for the energy-dependent sensor response has been compiled that addresses dosimetry foils/configurations in use at the Sandia National Laboratories Radiation Metrology Laboratory

A fast resonance interference treatment scheme with subgroup method

International Nuclear Information System (INIS)

Cao, L.; He, Q.; Wu, H.; Zu, T.; Shen, W.

2015-01-01

A fast Resonance Interference Factor (RIF) scheme is proposed to treat the resonance interference effects between different resonance nuclides. This scheme utilizes the conventional subgroup method to evaluate the self-shielded cross sections of the dominant resonance nuclide in the heterogeneous system and the hyper-fine energy group method to represent the resonance interference effects in a simplified homogeneous model. In this paper, the newly implemented scheme is compared to the background iteration scheme, the Resonance Nuclide Group (RNG) scheme and the conventional RIF scheme. The numerical results show that the errors of the effective self-shielded cross sections are significantly reduced by the fast RIF scheme compared with the background iteration scheme and the RNG scheme. Besides, the fast RIF scheme consumes less computation time than the conventional RIF schemes. The speed-up ratio is ~4.5 for MOX pin cell problems. (author)

Nuclear data adjustment methodology utilizing resonance parameter sensitivities and uncertainties

International Nuclear Information System (INIS)

Broadhead, B.L.

1983-01-01

This work presents the development and demonstration of a Nuclear Data Adjustment Method that allows inclusion of both energy and spatial self-shielding into the adjustment procedure. The resulting adjustments are for the basic parameters (i.e. resonance parameters) in the resonance regions and for the group cross sections elsewhere. The majority of this development effort concerns the production of resonance parameter sensitivity information which allows the linkage between the responses of interest and the basic parameters. The resonance parameter sensitivity methodology developed herein usually provides accurate results when compared to direct recalculations using existng and well-known cross section processing codes. However, it has been shown in several cases that self-shielded cross sections can be very non-linear functions of the basic parameters. For this reason caution must be used in any study which assumes that a linear relatonship exists between a given self-shielded group cross section and its corresponding basic data parameters. The study also has pointed out the need for more approximate techniques which will allow the required sensitivity information to be obtained in a more cost effective manner

Reduction of entrance surface dose depending on shielding methods for panoramagraphy

Energy Technology Data Exchange (ETDEWEB)

Choi, Jung Hyun; Han, DongKyoon [Dept. of Radiological Science, The Graduate School, Eulji University, Sungnam (Korea, Republic of); Kim, Sung Chul [Dept. of Radiological, Science Gachon, University, Incheon (Korea, Republic of)

2015-09-15

Panoramagraphy was the second most used intraoral radiography utilized in Korea, resulting in 17.8% in university dental hospitals, 24.8% in dental hospitals, and 31.4% in dental clinics. Depending on increased demand like orthodontics and implant, panoromagraphy tends to consistently increase. This study were used lead glasses and lead shielding to reduce unnecessary radiation to the eyeballs and thyroid. ESD was 41.4% when radiation was shielded with the lead glasses while reducing 47.3% of ESD by shielding the X-ray tube area with shielding lead. There was no statistically significant difference. The lead glasses is appropriated to reduce unnecessary radiation exposure to the eyeballs.

Reduction of entrance surface dose depending on shielding methods for panoramagraphy

International Nuclear Information System (INIS)

Choi, Jung Hyun; Han, DongKyoon; Kim, Sung Chul

2015-01-01

Panoramagraphy was the second most used intraoral radiography utilized in Korea, resulting in 17.8% in university dental hospitals, 24.8% in dental hospitals, and 31.4% in dental clinics. Depending on increased demand like orthodontics and implant, panoromagraphy tends to consistently increase. This study were used lead glasses and lead shielding to reduce unnecessary radiation to the eyeballs and thyroid. ESD was 41.4% when radiation was shielded with the lead glasses while reducing 47.3% of ESD by shielding the X-ray tube area with shielding lead. There was no statistically significant difference. The lead glasses is appropriated to reduce unnecessary radiation exposure to the eyeballs

Insufficient self-shielding correction in VITAMIN-B6

International Nuclear Information System (INIS)

Konno, Chikara; Ochiai, Kentaro; Ohnishi, Seiki

2011-01-01

We carried out a simple benchmark calculation test with a multigroup cross-section library VITAMIN-B6 generated from ENDF/B-VI. The model of this test consisted of an iron sphere of 1 m in radius with an isotropic 20 MeV neutron source in the center. Neutron spectra in the sphere were calculated with an Sn code ANISN and VITAMIN-B6 or FENDL/MG-1.1. A calculation with MCNP and ENDF/B-VI was carried out as a reference. The neutron spectra with ANISN and FENDL/MG-1.1 agreed with those with MCNP, while those with ANISN and VITAMIN-B6 were at most 50% different from those with MCNP. We uncovered that the discrepancy came from insufficient self-shielding correction due to the followings; 1) The smallest background cross section of 56 Fe in VITAMIN-B6 is 1. 2) The weighting flux used in generating VITAMIN-B6 is not adequate. VITAMIN-B6 should be revised for adequate self-shielding correction. (author)

Self-consistent velocity dependent effective interactions

International Nuclear Information System (INIS)

Kubo, Takayuki; Sakamoto, Hideo; Kammuri, Tetsuo; Kishimoto, Teruo.

1993-09-01

The field coupling method is extended to a system with a velocity dependent mean potential. By means of this method, we can derive the effective interactions which are consistent with the mean potential. The self-consistent velocity dependent effective interactions are applied to the microscopic analysis of the structures of giant dipole resonances (GDR) of 148,154 Sm, of the first excited 2 + states of Sn isotopes and of the first excited 3 - states of Mo isotopes. It is clarified that the interactions play crucial roles in describing the splitting of the resonant structure of GDR peaks, in restoring the energy weighted sum rule values, and in reducing B (Eλ) values. (author)

Testing of cross-section functionals in the unresolved resonance region

International Nuclear Information System (INIS)

Koshcheev, V.N.; Krivtsov, A.S.; Sinitsa, V.V.; Ukraintsev, V.F.

1994-01-01

The results of a comparison of the GRUCON, MMK and NJOY data processing codes in the treatment of evaluated neutron data in the unresolved resonance region are presented. The sets of average resonance parameters of 238 U and 239 Pu isotopes, which have been published by Munos-Cobos et al., and Ribon et al., were used in this exercise. Average cross-sections, self-shielding factors and Doppler broadening self-shielding factors are compared with the original results presented by the above-mentioned authors. Conclusions regarding the reliability of the neutron data processing codes are made. (author). 6 refs, 7 tabs

Importance of resonance parameters of fertile nuclei and of 239Pu isotope for fast power reactors

International Nuclear Information System (INIS)

Barre, J.Y.; Khairallah, A.

1975-01-01

The importance of resonance parameters of fertile nuclei and of 239 Pu isotope for fast power reactors will be restricted, in this presentation, to mixed oxide-uranium-plutonium fuelled sodium-cooled and uranium-oxide-sodium reflected fast reactors. The power range lies between 200 and 2000 MWe. Among the topics of this specialist meeting, the isotopes to be considered are, primarly 239 Pu then 238 U and 240 Pu. Resonance parameters are mainly used in fast power reactor calculations through the well-known concept of self shielding factors. After a short description of the determination and the use of these self-shielding factors, their sensitivities to resonance parameters are characterized from some specific examples: those sensitivities are small. Then, the main design parameters sensitive to the amplitude of self-shielding factors are considered: critical enrichment, global breeding gain. The relative importance of isotope, reaction rate and energy range are mentionned. In a third part, the Doppler effect, sensitive to the temperature variation of self-shielding factors, is considered in the same way. Finally, it is concluded that the present knowledge of resonance parameters for 238 U, 239 Pu and 240 Pu is sufficient for fast power reactors from a designer point of view [fr

Importance of self-shielding for improving sensitivity coefficients in light water nuclear reactors

International Nuclear Information System (INIS)

Foad, Basma; Takeda, Toshikazu

2014-01-01

Highlights: • A new method has been developed for calculating sensitivity coefficients. • This method is based on the use of infinite dilution cross-sections instead of effective cross-sections. • The change of self-shielding factor due to cross-section perturbation has been considered. • SRAC and SAINT codes are used for calculating improved sensitivities, while MCNP code has been used for verification. - Abstract: In order to perform sensitivity analyzes in light water reactors where self-shielding effect becomes important, a new method has been developed for calculating sensitivity coefficient of core characteristics relative to the infinite dilution cross-sections instead of the effective cross-sections. This method considers the change of the self-shielding factor due to cross-section perturbation for different nuclides and reactions. SRAC and SAINT codes are used to calculate the improved sensitivity; while the accuracy of the present method has been verified by MCNP code and good agreement has been found

Multiconfigurational self-consistent field calculations of nuclear shieldings using London atomic orbitals

DEFF Research Database (Denmark)

Ruud, Kenneth; Helgaker, Trygve; Kobayashi, Rika

1994-01-01

to corresponding individual gauges for localized orbitals (IGLO) results. The London results show better basis set convergence than IGLO, especially for heavier atoms. It is shown that the choice of active space is crucial for determination of accurate nuclear shielding constants.......Nuclear shielding calculations are presented for multiconfigurational self-consistent field wave functions using London atomic orbitals (gauge invariant atomic orbitals). Calculations of nuclear shieldings for eight molecules (H2O, H2S, CH4, N2, CO, HF, F2, and SO2) are presented and compared...

RZ calculations for self shielded multigroup cross sections

Energy Technology Data Exchange (ETDEWEB)

Li, M.; Sanchez, R.; Zmijarevic, I.; Stankovski, Z. [Commissariat a l' Energie Atomique CEA, Direction de l' Energie Nucleaire, DEN/DM2S/SERMA/LENR, 91191 Gif-sur-Yvette Cedex (France)

2006-07-01

A collision probability method has been implemented for RZ geometries. The method accounts for white albedo, specular and translation boundary condition on the top and bottom surfaces of the geometry and for a white albedo condition on the outer radial surface. We have applied the RZ CP method to the calculation of multigroup self shielded cross sections for Gadolinia absorbers in BWRs. (authors)

RZ calculations for self shielded multigroup cross sections

International Nuclear Information System (INIS)

Li, M.; Sanchez, R.; Zmijarevic, I.; Stankovski, Z.

2006-01-01

A collision probability method has been implemented for RZ geometries. The method accounts for white albedo, specular and translation boundary condition on the top and bottom surfaces of the geometry and for a white albedo condition on the outer radial surface. We have applied the RZ CP method to the calculation of multigroup self shielded cross sections for Gadolinia absorbers in BWRs. (authors)

Calculation of the electron trajectory for 200 kV self-shielded electron accelerator

International Nuclear Information System (INIS)

Wang Shuiqing

2000-01-01

In order to calculate the electron trajectory of 200 kV self-shielded electron accelerator, the electric field is calculated with a TRAJ program. In this program, following electron track mash points one by one, the electron beam trajectories are calculated. Knowing the effect of grid voltage on electron optics and gaining grid voltage focusing effect in the various energy grades, the authors have gained scientific basis for adjusting grid voltage, and also accumulated a wealth of experience for designing self-shielded electron accelerator or electron curtain in future

Demonstration of suppressed phonon tunneling losses in phononic bandgap shielded membrane resonators for high-Q optomechanics.

Science.gov (United States)

Tsaturyan, Yeghishe; Barg, Andreas; Simonsen, Anders; Villanueva, Luis Guillermo; Schmid, Silvan; Schliesser, Albert; Polzik, Eugene S

2014-03-24

Dielectric membranes with exceptional mechanical and optical properties present one of the most promising platforms in quantum opto-mechanics. The performance of stressed silicon nitride nanomembranes as mechanical resonators notoriously depends on how their frame is clamped to the sample mount, which in practice usually necessitates delicate, and difficult-to-reproduce mounting solutions. Here, we demonstrate that a phononic bandgap shield integrated in the membrane's silicon frame eliminates this dependence, by suppressing dissipation through phonon tunneling. We dry-etch the membrane's frame so that it assumes the form of a cm-sized bridge featuring a 1-dimensional periodic pattern, whose phononic density of states is tailored to exhibit one, or several, full band gaps around the membrane's high-Q modes in the MHz-range. We quantify the effectiveness of this phononic bandgap shield by optical interferometry measuring both the suppressed transmission of vibrations, as well as the influence of frame clamping conditions on the membrane modes. We find suppressions up to 40 dB and, for three different realized phononic structures, consistently observe significant suppression of the dependence of the membrane's modes on sample clamping-if the mode's frequency lies in the bandgap. As a result, we achieve membrane mode quality factors of 5 × 10(6) with samples that are tightly bolted to the 8 K-cold finger of a cryostat. Q × f -products of 6 × 10(12) Hz at 300 K and 14 × 10(12) Hz at 8 K are observed, satisfying one of the main requirements for optical cooling of mechanical vibrations to their quantum ground-state.

Frequency dependence of magnetic shielding performance of HTS plates in mixed states

International Nuclear Information System (INIS)

Kamitani, Atsushi; Yokono, Takafumi; Yokono, Takafumi

2000-01-01

The magnetic shielding performance of the high-Tc superconducting (HTS) plate is investigated numerically. The behavior of the shielding current density in the HTS plate is expressed as the integral-differential equation with a normal component of the current vector potential as a dependent variable. The numerical code for solving the equation has been developed by using the combination of the Newton-Raphson method and the successive substitution method and, by use of the code, damping coefficients and shielding factors are evaluated for the various values of the frequency ω. The results of computations show that the HTS plate has a possibility of shielding the high-frequency magnetic field with ω > or approx. 1 kHz. (author)

Frequency dependence of magnetic shielding performance of HTS plates in mixed states

Energy Technology Data Exchange (ETDEWEB)

Kamitani, Atsushi; Yokono, Takafumi [Yamagata Univ., Yonezawa (Japan). Faculty of Engineering; Yokono, Takafumi [Tsukuba Univ., Ibaraki (Japan). Inst. of Information Sciences and Electronics

2000-06-01

The magnetic shielding performance of the high-Tc superconducting (HTS) plate is investigated numerically. The behavior of the shielding current density in the HTS plate is expressed as the integral-differential equation with a normal component of the current vector potential as a dependent variable. The numerical code for solving the equation has been developed by using the combination of the Newton-Raphson method and the successive substitution method and, by use of the code, damping coefficients and shielding factors are evaluated for the various values of the frequency {omega}. The results of computations show that the HTS plate has a possibility of shielding the high-frequency magnetic field with {omega} > or approx. 1 kHz. (author)

Thermal neutron self-shielding correction factors for large sample instrumental neutron activation analysis using the MCNP code

International Nuclear Information System (INIS)

Tzika, F.; Stamatelatos, I.E.

2004-01-01

Thermal neutron self-shielding within large samples was studied using the Monte Carlo neutron transport code MCNP. The code enabled a three-dimensional modeling of the actual source and geometry configuration including reactor core, graphite pile and sample. Neutron flux self-shielding correction factors derived for a set of materials of interest for large sample neutron activation analysis are presented and evaluated. Simulations were experimentally verified by measurements performed using activation foils. The results of this study can be applied in order to determine neutron self-shielding factors of unknown samples from the thermal neutron fluxes measured at the surface of the sample

Verification of effectiveness of borated water shield for a cyclotron type self-shielded; Verificacao da eficacia da blindagem de agua borada construida para um acelerador ciclotron do tipo autoblindado

Energy Technology Data Exchange (ETDEWEB)

Videira, Heber S.; Burkhardt, Guilherme M.; Santos, Ronielly S., E-mail: heber@cyclopet.com.br [Cyclopet Radiofarmacos Ltda., Curitiba, PR (Brazil); Passaro, Bruno M.; Gonzalez, Julia A.; Santos, Josefina; Guimaraes, Maria I.C.C. [Universidade de Sao Paulo (HCFMRP/USP), Sao Paulo, SP (Brazil). Faculdade de Medicina. Hospital das Clinicas; Lenzi, Marcelo K. [Universidade Federal do Parana (UFPR), Curitina (Brazil). Programa de Pos-Graduacao em Engenharia Quimica

2013-04-15

The technological advances in positron emission tomography (PET) in conventional clinic imaging have led to a steady increase in the number of cyclotrons worldwide. Most of these cyclotrons are being used to produce {sup 18}F-FDG, either for themselves as for the distribution to other centers that have PET. For there to be safety in radiological facilities, the cyclotron intended for medical purposes can be classified in category I and category II, ie, self-shielded or non-shielded (bunker). Therefore, the aim of this work is to verify the effectiveness of borated water shield built for a cyclotron accelerator-type Self-shielded PETtrace 860. Mixtures of water borated occurred in accordance with the manufacturer’s specifications, as well as the results of the radiometric survey in the vicinity of the self-shielding of the cyclotron in the conditions established by the manufacturer showed that radiation levels were below the limits. (author)

Bonderenko self-shielded cross sections and multiband parameters derived from the LLL Evaluated-Nuclear-Data Library (ENDL)

International Nuclear Information System (INIS)

Cullen, D.E.

1978-01-01

Bonderenko self-shielded cross sections and multiband parameters from the Lawrence Livermore Laboratory Evaluated-Nuclear-Data Library (ENDL) as of July 4, 1978 are presented. These data include total, elastic, capture, and fission cross sections in the TART 175 group structure. Multiband parameters are listed. Bonderenko self-shielded cross section and the multiband parameters are presented on microfiche

Success and prospects for low energy, self-shielded electron beam accelerators

International Nuclear Information System (INIS)

Laeuppi, U.V.

1988-01-01

The advantages of self-shielded, low energy, electron beam accelerators for electron beam processing are described. Applications of these accelerators for cross-linking plastic films, drying of coated materials and printing inks and for curing processes are discussed. (U.K.)

Resonance region neutronics of unit cells in fast and thermal reactors

International Nuclear Information System (INIS)

Salehi, A.A.; Driscoll, M.J.; Deutsch, O.L.

1977-05-01

A method has been developed for generating resonance-self-shielded cross sections based upon an improved equivalence theorem, which appears to allow extension of the self-shielding-factor (Bondarenko f-factor) method, now mainly applied to fast reactors, to thermal reactors as well. The method is based on the use of simple prescriptions for the ratio of coolant-to-fuel region-averaged fluxes, in the equations defining cell averaged cross sections. Linearization of the dependence of these functions on absorber optical thickness is found to be a necessary and sufficient condition for the existence of an equivalence theorem. Results are given for cylindrical, spherical and slab geometries. The functional form of the flux ratio relations is developed from theoretical considerations, but some of the parameters are adjusted to force-fit numerical results. Good agreement over the entire range of fuel and coolant optical thicknesses is demonstrated with numerical results calculated using the ANISN program in the S 8 P 1 option

An overview of the current status of resonance theory in reactor physics applications

International Nuclear Information System (INIS)

Hwang, R.N.

1993-01-01

The neutron resonance phenomena constitute one of the most fundamental subjects in nuclear physics as well as in reactor physics. It is the area where the concepts of nuclear interaction and the treatment of the neutronic balance in reactor lattices become intertwined. The later requires the detailed knowledge of resonance structures of many nuclide of practical interest to the development of nuclear energy. The key issue of the resonance treatment in reactor applications is directly associated with the use of the microscopic cross sections in the macroscopic reactor cells with a wide range of composition, temperature,and geometric configurations. It gives rise to the so called self-shielding effect. The accurate estimations of such a effect is essential not only in the calculation of the criticality of a reactor but also from the point of view of safety considerations. The latter manifests through the Doppler effect particularly crucial to the fast reactor development. The task of accurate treatment of the self-shielding effect, however, is by no means simple. In fact, it is perhaps the most complicated problem in neutron physics which, strictly speaking, requires the dependence of many physical variables. Two important elements of particular interest are : (1) a concise description of the resonance cross sections as a function of energy and temperature; (2) accurate estimation of the corresponding neutron flux where appropriate. These topics will be discussed from both the historical as well as the state-of-art perspectives

Self-shielding factors

International Nuclear Information System (INIS)

Kaul, D.C.

1982-01-01

Throughout the last two decades many efforts have been made to estimate the effect of body self-shielding on organ doses from externally incident neutrons and gamma rays. These began with the use of simple geometry phantoms and have culminated in the use of detailed anthropomorphic phantoms. In a recent effort, adjoint Monte Carlo analysis techniques have been used to determine dose and dose equivalent to the active marrow as a function of energy and angle of neutron fluence externally incident on an anthropomorphic phantom. When combined with fluences from actual nuclear devices, these dose-to-fluence factors result in marrow dose values that demonstrate great sensitivity to variations in device type, range, and body orientation. Under a state-of-the-art radiation transport analysis demonstration program for the Japanese cities, sponsored by the Defense Nuclear Agency at the request of the National Council on Radiation Protection and Measurements, the marrow dose study referred to above is being repeated to obtain spectral distributions within the marrow for externally incident neutrons and gamma rays of arbitrary energy and angle. This is intended to allow radiobiologists and epidemiologists to select and to modify numbers of merit for correlation with health effects and to permit a greater understanding of the relationship between human and laboratory subject dosimetry

Multifunctional Shielding and Self-Healing HybridSil Smart Composites for Space, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — NanoSonic has developed revolutionary multifunctional, super lightweight, self-healing and radiation shielding carbon fiber reinforced polymer (CFRP) composites as a...

Determination of Intermediate Resonance Parameter with RMET21 for nTRACER

International Nuclear Information System (INIS)

Sohail, Muhammad; Kim, Myung Hyun

2012-01-01

Ray Tracing based code nTRACER is being developed in Seoul National University that has the capability of 3-dimensional whole core neutron transport calculation. As a part of development of multi-group neutron cross section library for nTRACER, the current work is intended to accurately determine intermediate resonance parameters. Beside the systematic calculation of subgroup parameters for resonance self shielding calculation, intermediate resonance parameters itself can be as important as the multi-group neutron cross section in the library and its overall accuracy. In this paper lambda factors were computed using RMET21 from ENDF/B-VII.1 for nTRACER to investigate its dependence on temperature and background cross section and replaced with lambda factors from HELIOS multi-group library. The procedure used for determining the intermediate resonance parameter for the isotope under study is introduced in the next section. Oxygen being one of the primary nuclide in PWR fuel has been selected for intermediate resonance parameters calculation

Neutron radiation shielding properties of polymer incorporated self compacting concrete mixes.

Science.gov (United States)

Malkapur, Santhosh M; Divakar, L; Narasimhan, Mattur C; Karkera, Narayana B; Goverdhan, P; Sathian, V; Prasad, N K

2017-07-01

In this work, the neutron radiation shielding characteristics of a class of novel polymer-incorporated self-compacting concrete (PISCC) mixes are evaluated. Pulverized high density polyethylene (HDPE) material was used, at three different reference volumes, as a partial replacement to river sand in conventional concrete mixes. By such partial replacement of sand with polymer, additional hydrogen contents are incorporated in these concrete mixes and their effect on the neutron radiation shielding properties are studied. It has been observed from the initial set of experiments that there is a definite trend of reductions in the neutron flux and dose transmission factor values in these PISCC mixes vis-à-vis ordinary concrete mix. Also, the fact that quite similar enhanced shielding results are recorded even when reprocessed HDPE material is used in lieu of the virgin HDPE attracts further attention. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characteristics simulation of wireless power transfer system considering shielding distance

Energy Technology Data Exchange (ETDEWEB)

Lee, Yu Kyeong; Choi, Hyo Sang; Jung, Byung Ik; Jeong, In Sung [Chosun University, Gwangju (Korea, Republic of)

2015-03-15

Wireless power transfer technology is using the magnetic resonance recently drawing increased attention. It uses the resonance between transmitter and receiver coils to transfer power. Thus, it can improve the transfer distance and efficiency compared with the existing magnetic induction technique. The authors found from the previous study that the application of the superconductor coil to the magnetic resonance wireless power transfer system improved its efficiency. Its application to real life, however, requires the additional study on the effects of adjacent materials. In this study, the two resonance coils made by superconductor coils were used to aluminum and plastic shielding materials was placed between the coils. S-parameters were analyzed according to the position of the shielding material between the transmitter and receiver coils. As a result, the plastic of shielding material had no effect, but the aluminum of shielding material affected the wireless power transfer due to the shielding effectiveness.

Characteristics simulation of wireless power transfer system considering shielding distance

International Nuclear Information System (INIS)

Lee, Yu Kyeong; Choi, Hyo Sang; Jung, Byung Ik; Jeong, In Sung

2015-01-01

Wireless power transfer technology is using the magnetic resonance recently drawing increased attention. It uses the resonance between transmitter and receiver coils to transfer power. Thus, it can improve the transfer distance and efficiency compared with the existing magnetic induction technique. The authors found from the previous study that the application of the superconductor coil to the magnetic resonance wireless power transfer system improved its efficiency. Its application to real life, however, requires the additional study on the effects of adjacent materials. In this study, the two resonance coils made by superconductor coils were used to aluminum and plastic shielding materials was placed between the coils. S-parameters were analyzed according to the position of the shielding material between the transmitter and receiver coils. As a result, the plastic of shielding material had no effect, but the aluminum of shielding material affected the wireless power transfer due to the shielding effectiveness

Time dependent resonating Hartree-Bogoliubov theory

International Nuclear Information System (INIS)

Nishiyama, Seiya; Fukutome, Hideo.

1989-01-01

Very recently, we have developed a theory of excitations in superconducting Fermion systems with large quantum fluctuations that can be described by resonance of time dependent non-orthogonal Hartree-Bogoliubov (HB) wave functions with different correlation structures. We have derived a new kind of variation equation called the time dependent Resonating HB equation, in order to determine both the time dependent Resonating HB wave functions and coefficients of a superposition of the HB wave functions. Further we have got a new approximation for excitations from time dependent small fluctuations of the Resonating HB ground state, i.e., the Resonating HB RPA. The Res HB RPA equation is represented in a given single particle basis. It, however, has drawbacks that the constraints for the Res HB RPA amplitudes are not taken into account and the equation contains equations which are not independent. We shall derive another form of the Res HB RPA equation eliminating these drawbacks. The Res HB RPA gives a unified description of the vibrons and resonons and their interactions. (author)

Resonance self-shielding method using resonance interference factor library for practical lattice physics computations of LWRs

International Nuclear Information System (INIS)

Choi, Sooyoung; Khassenov, Azamat; Lee, Deokjung

2016-01-01

This paper presents a new method of resonance interference effect treatment using resonance interference factor for high fidelity analysis of light water reactors (LWRs). Although there have been significant improvements in the lattice physics calculations over the several decades, there exist still relatively large errors in the resonance interference treatment, in the order of ∼300 pcm in the reactivity prediction of LWRs. In the newly developed method, the impact of resonance interference to the multi-group cross-sections has been quantified and tabulated in a library which can be used in lattice physics calculation as adjustment factors of multi-group cross-sections. The verification of the new method has been performed with Mosteller benchmark, UO_2 and MOX pin-cell depletion problems, and a 17×17 fuel assembly loaded with gadolinia burnable poison, and significant improvements were demonstrated in the accuracy of reactivity and pin power predictions, with reactivity errors down to the order of ∼100 pcm. (author)

Glycan dependence of Galectin-3 self-association properties.

Directory of Open Access Journals (Sweden)

Hubert Halimi

Full Text Available Human Galectin-3 is found in the nucleus, the cytoplasm and at the cell surface. This lectin is constituted of two domains: an unfolded N-terminal domain and a C-terminal Carbohydrate Recognition Domain (CRD. There are still uncertainties about the relationship between the quaternary structure of Galectin-3 and its carbohydrate binding properties. Two types of self-association have been described for this lectin: a C-type self-association and a N-type self-association. Herein, we have analyzed Galectin-3 oligomerization by Dynamic Light Scattering using both the recombinant CRD and the full length lectin. Our results proved that LNnT induces N-type self-association of full length Galectin-3. Moreover, from Nuclear Magnetic Resonance (NMR and Surface Plasmon Resonance experiments, we observed no significant specificity or affinity variations for carbohydrates related to the presence of the N-terminal domain of Galectin-3. NMR mapping clearly established that the N-terminal domain interacts with the CRD. We propose that LNnT induces a release of the N-terminal domain resulting in the glycan-dependent self-association of Galectin-3 through N-terminal domain interactions.

Protective effect of blue-light shield eyewear for adults against light pollution from self-luminous devices used at night.

Science.gov (United States)

Ayaki, Masahiko; Hattori, Atsuhiko; Maruyama, Yusuke; Nakano, Masaki; Yoshimura, Michitaka; Kitazawa, Momoko; Negishi, Kazuno; Tsubota, Kazuo

2016-01-01

We investigated sleep quality and melatonin in 12 adults who wore blue-light shield or control eyewear 2 hours before sleep while using a self-luminous portable device, and assessed visual quality for the two eyewear types. Overnight melatonin secretion was significantly higher after using the blue-light shield (P light shield (P light shield as providing acceptable visual quality.

Analysis of mixed oxides critical experiments using the Hammer-Technion code with self-shielding treatment by Bondarenko method

International Nuclear Information System (INIS)

Abe, Alfredo Y.; Santos, Adimir dos

1995-01-01

The present work summarizes the verification of the treatment of self-shielding based on Bondarenko method in HAMMER-TECHNION cell code for the Pu O 2 -U O 2 critical system using JENDL-3 nuclear data library. The results obtained are in excellent agreement with the original treatment of self-shielding employed by HAMMER-TECHNION cell code. (author). 9 refs, 1 fig, 9 tabs

Resonant Raman spectroscopy of PAH-Os self-assembled multilayers

International Nuclear Information System (INIS)

Tognalli, N.; Fainstein, A.; Bonazzola, C.; Calvo, E.

2004-01-01

We present a resonant Raman scattering study of (PAH-Os/PVS) n and (PAH-Os/GOx) m self-assembled multilayers (n=1-11 and m=1-3). These Os polymer multilayers can be used in electrodes as efficient molecular wires for biomolecular recognition. The Raman intensity dependence on the number of self-assembly cycles provides information on the deposition process. The spectra are identical to that observed for PAH-Os in aqueous solution, indicating that the PAH-Os metal complex structure is conserved in the multilayers. We observe at ∼500 nm incoming and outgoing Raman resonances of osmium and bipyridine vibrational modes. These resonances are associated to the metal-to-ligand charge transfer (MLCT) transition. We study the evolution of these Raman modes as a function of the Os oxidation state during in situ electrochemistry. During the oxidation process, Os(II)→Os(III), the Raman resonance related to the MLCT disappears and the bipyridine related modes harden by ∼10 cm-1. These results are correlated with optical transmission measurements which show the disappearance of the visible region absorption when the Os complex is oxidized. We also find partial quenching of the Raman mode intensity after in situ voltamperometric cycles which demonstrates the existence of photo-electro-chemical processes

Background-cross-section-dependent subgroup parameters

International Nuclear Information System (INIS)

Yamamoto, Toshihisa

2003-01-01

A new set of subgroup parameters was derived that can reproduce the self-shielded cross section against a wide range of background cross sections. The subgroup parameters are expressed with a rational equation which numerator and denominator are expressed as the expansion series of background cross section, so that the background cross section dependence is exactly taken into account in the parameters. The advantage of the new subgroup parameters is that they can reproduce the self-shielded effect not only by group basis but also by subgroup basis. Then an adaptive method is also proposed which uses fitting procedure to evaluate the background-cross-section-dependence of the parameters. One of the simple fitting formula was able to reproduce the self-shielded subgroup cross section by less than 1% error from the precise evaluation. (author)

Situations of potential exposure in self-shielding electron accelerators

International Nuclear Information System (INIS)

Rios, D.A.S.; Rios, P.B.; Sordi, G.M.A.A.; Carneiro, J.C.G.G.

2017-01-01

The study discusses situations in the industrial environment that may lead to potential exposure of Occupationally Exposed Individuals and Public Individuals in self-shielding electron accelerators. Although these exposure situations are unlikely, simulation exercises can lead to improvements in the operating procedure as well as suggest changes in production line design in order to increase radiation protection at work. These studies can also be used in training and demonstrate a solid application of the ALARA principle in the daily activities of radiative installations

CO Self-Shielding as a Mechanism to Make 16O-Enriched Solids in the Solar Nebula

Directory of Open Access Journals (Sweden)

Joseph A. Nuth, III

2014-05-01

Full Text Available Photochemical self-shielding of CO has been proposed as a mechanism to produce solids observed in the modern, 16O-depleted solar system. This is distinct from the relatively 16O-enriched composition of the solar nebula, as demonstrated by the oxygen isotopic composition of the contemporary sun. While supporting the idea that self-shielding can produce local enhancements in 16O-depleted solids, we argue that complementary enhancements of 16O-enriched solids can also be produced via C16O-based, Fischer-Tropsch type (FTT catalytic processes that could produce much of the carbonaceous feedstock incorporated into accreting planetesimals. Local enhancements could explain observed 16O enrichment in calcium-aluminum-rich inclusions (CAIs, such as those from the meteorite, Isheyevo (CH/CHb, as well as in chondrules from the meteorite, Acfer 214 (CH3. CO self-shielding results in an overall increase in the 17O and 18O content of nebular solids only to the extent that there is a net loss of C16O from the solar nebula. In contrast, if C16O reacts in the nebula to produce organics and water then the net effect of the self-shielding process will be negligible for the average oxygen isotopic content of nebular solids and other mechanisms must be sought to produce the observed dichotomy between oxygen in the Sun and that in meteorites and the terrestrial planets. This illustrates that the formation and metamorphism of rocks and organics need to be considered in tandem rather than as isolated reaction networks.

FCXSEC: multigroup cross-section libraries for nuclear fuel cycle shielding calculations

International Nuclear Information System (INIS)

Ford, W.E. III; Webster, C.C.; Diggs, B.R.; Pevey, R.E.; Croff, A.G.

1980-05-01

Starting with the pseudo-composition-independent VITAMIN-C cross-sectin library, composition-dependent fine-(171n-36γ) and broad-group (22n-21γ) self-shielded AMPX master, broad-group microscopic ANISN-formatted, and broad-group macroscopic ANISN-formatted cross-section libraries were generated to be used for nuclear fuel cycle shielding calculations. The specifications for the data and the procedure used to prepare the libraries are described

Thermal shield support degradation in pressurized water reactors

International Nuclear Information System (INIS)

Sweeney, F.J.; Fry, D.N.

1986-01-01

Damage to the thermal shield support structures of three pressurized water reactors (PWRs) due to flow-induced vibrations was recently discovered during refueling. In two of the reactors, severe damage occurred to the thermal shield, and in one reactor the core support barrel (CSB) was damaged, necessitating extended outages for repairs. In all three reactors, several of the thermal shield supports were either loose, damaged, or missing. The three plants had been in operation for approximately 10 years before the damage was apparent by visual inspection. Because each of the three US PWR manufacturers have experienced thermal shield support degradation, the Nuclear Regulatory Commission requested that Oak Ridge National Laboratory analyze ex-core neutron detector noise data to determine the feasibility of detecting incipient thermal shield support degradation. Results of the noise data analysis indicate that thermal shield support degradation probably began early in the life of both severely damaged plants. The degradation was characterized by shifts in the resonant frequencies of core internal structures and the appearance of new resonances in the ex-core neutron detector noise. Both the data analyses and the finite element calculations indicate that these changes in resonant frequencies are less than 3 Hz. 11 refs., 16 figs

Heating profiles on ICRF antenna Faraday shields

International Nuclear Information System (INIS)

Taylor, D.J.; Baity, F.W.; Hahs, C.L. Riemer, B.W.; Ryan, D.M.; Williamson, D.E.

1992-01-01

Poor definition of the heating profiles that occur during normal operation of Faraday shields for ion cyclotron resonant frequency (ICRF) antennas has complicated the mechanical design of ICRF system components. This paper reports that at Oak Ridge National Laboratory (ORNL), Faraday shield analysis is being used in defining rf heating profiles. In recent numerical analyses of proposed hardware for the Burning Plasma Experiment (BPX) and DIII-D, rf magnetic fields at Faraday shield surfaces were calculated, providing realistic predictions of the induced skin currents flowing on the shield elements and the resulting dissipated power profile. Detailed measurements on mock-ups of the Faraday shields for DIII-D and the Tokamak Fusion Test Reactor (TFTR) confirmed the predicted magnetic field distributions. A conceptual design for an uncooled Faraday shield for the BPX ion cyclotron resonance heating (ICRH) antenna, which should withstand the proposed long-pulse operation, has been completed. The analytical effort is described in detail, with emphasis on the design work for the BPX ICRH antenna conceptual design and for the replacement Faraday shield for the DIII-D FWCD antenna. Results of analyses are shown, and configuration issues involved in component modeling are discussed

TIMS-1, Multigroup Cross-Sections of Heavy Isotope Mixture with Resonance from ENDF/B

International Nuclear Information System (INIS)

Takano, Hideki; Ishiguro, Yukio; Matsui, Yasushi

1984-01-01

1 - Description of problem or function: TIMS-1 is a code for calculating the group constants of heavy resonant nuclei by using ENDF/ B-4 format data. This code calculates infinitely dilute cross sections and self-shielding factors as a function of composition sigma-0 temperature T and R-parameter, where R is the ratio of ato- mic number density of two different resonant nuclei. 2 - Method of solution: In the unresolved resonance region, a ladder of resonance parameters and levels is generated with Monte Carlo method. The temperature dependent cross sections are calculated with the Breit-Wigner single-level and multi-level formula. The neutron spectrum is accurately calculated by solving numerically the neutron slowing down equation using a recurrence formula for neutron slowing down source. 3 - Restrictions on the complexity of the problem: The maximum numbers of energy groups, temperatures and compositions are 60, 4 and 10 respectively

Stochastic resonance and coherence resonance in groundwater-dependent plant ecosystems.

Science.gov (United States)

Borgogno, Fabio; D'Odorico, Paolo; Laio, Francesco; Ridolfi, Luca

2012-01-21

Several studies have shown that non-linear deterministic dynamical systems forced by external random components can give rise to unexpectedly regular temporal behaviors. Stochastic resonance and coherence resonance, the two best known processes of this type, have been studied in a number of physical and chemical systems. Here, we explore their possible occurrence in the dynamics of groundwater-dependent plant ecosystems. To this end, we develop two eco-hydrological models, which allow us to demonstrate that stochastic and coherence resonance may emerge in the dynamics of phreatophyte vegetation, depending on their deterministic properties and the intensity of external stochastic drivers. Copyright © 2011 Elsevier Ltd. All rights reserved.

REPOSITORY LAYOUT SUPPORTING DESIGN FEATURE NO.13 - WASTE PACKAGE SELF SHIELDING

International Nuclear Information System (INIS)

Owen, J.

1999-01-01

The objective of this analysis is to develop a repository layout, for Feature No. 13, that will accommodate self-shielding waste packages (WP) with an areal mass loading of 25 metric tons of uranium per acre (MTU/acre). The scope of this analysis includes determination of the number of emplacement drifts, amount of emplacement drift excavation required, and a preliminary layout for illustrative purposes

Evaluation of usability of the shielding effect for thyroid shield for peripheral dose during whole brain radiation therapy

Energy Technology Data Exchange (ETDEWEB)

Yang, Myung Sic; Park, Ju Kyeong; Lee, Seung Hun; Kim, Yang Su; Lee, Sun Young; Cha, Seok Yong [Dept. of Radiation Oncology, Chonbuk National University Hospital, Jeonju (Korea, Republic of)

2014-12-15

To reduce the radiation dose to the thyroid that is affected to scattered radiation, the shield was used. And we evaluated the shielding effect for the thyroid during whole brain radiation therapy. To measure the dose of the thyroid, 300cGy were delivered to the phantom using a linear accelerator(Clinac iX VARIAN, USA.)in the way of the 6MV X-ray in bilateral. To measure the entrance surface dose of the thyroid, five glass dosimeters were placed in the 10th slice's surface of the phantom with a 1.5 cm interval. The average values were calculated by measured values in five times each, using bismuth shield, 0.5 mmPb shield, self-made 1.0 mmPb shield and unshield. In the same location, to measure the depth dose of the thyroid, five glass dosimeters were placed in the 10th slice by 2.5 cm depth of the phantom with a 1.5 cm interval. The average values were calculated by measured values in five times each, using bismuth shield, 0.5 mmPb shield, self-made 1.0 mmPb shield and unshield. Entrance surface dose of the thyroid were respectively 44.89 mGy at the unshield, 36.03 mGy at the bismuth shield, 31.03 mGy at the 0.5 mmPb shield and 23.21 mGy at a self-made 1.0 mmPb shield. In addition, the depth dose of the thyroid were respectively 36.10 mGy at the unshield, 34.52 mGy at the bismuth shield, 32.28 mGy at the 0.5 mmPb shield and 25.50 mGy at a self-made 1.0 mmPb shield. The thyroid was affected by the secondary scattering dose and leakage dose outside of the radiation field during whole brain radiation therapy. When using a shield in the thyroid, the depth dose of thyroid showed 11-30% reduction effect and the surface dose of thyroid showed 20-48% reduction effect. Therefore, by using the thyroid shield, it is considered to effectively protect the thyroid and can perform the treatment.

Self-shielding flex-circuit drift tube, drift tube assembly and method of making

Science.gov (United States)

Jones, David Alexander

2016-04-26

The present disclosure is directed to an ion mobility drift tube fabricated using flex-circuit technology in which every other drift electrode is on a different layer of the flex-circuit and each drift electrode partially overlaps the adjacent electrodes on the other layer. This results in a self-shielding effect where the drift electrodes themselves shield the interior of the drift tube from unwanted electro-magnetic noise. In addition, this drift tube can be manufactured with an integral flex-heater for temperature control. This design will significantly improve the noise immunity, size, weight, and power requirements of hand-held ion mobility systems such as those used for explosive detection.

Radiation transport and shielding information, computer codes, and nuclear data for use in CTR neutronics research and development

International Nuclear Information System (INIS)

Santoro, R.T.; Maskewitz, B.F.; Roussin, R.W.; Trubey, D.K.

1976-01-01

The activities of the Radiation Shielding Information Center (RSIC) of the Oak Ridge National Laboratory are being utilized in support of fusion reactor technology. The major activities of RSIC include the operation of a computer-based information storage and retrieval system, the collection, packaging, and distribution of large computer codes, and the compilation and dissemination of processed and evaluated data libraries, with particular emphasis on neutron and gamma-ray cross-section data. The Center has acquired thirteen years of experience in serving fission reactor, weapons, and accelerator shielding research communities, and the extension of its technical base to fusion reactor research represents a logical progression. RSIC is currently working with fusion reactor researchers and contractors in computer code development to provide tested radiation transport and shielding codes and data library packages. Of significant interest to the CTR community are the 100 energy group neutron and 21 energy group gamma-ray coupled cross-section data package (DLC-37) for neutronics studies, a comprehensive 171 energy group neutron and 36 energy group gamma-ray coupled cross-section data base with retrieval programs, including resonance self-shielding, that are tailored to CTR application, and a data base for the generation of energy-dependent atomic displacement and gas production cross sections and heavy-particle-recoil spectra for estimating radiation damage to CTR structural components

Wake Shield Target Protection

International Nuclear Information System (INIS)

Valmianski, Emanuil I.; Petzoldt, Ronald W.; Alexander, Neil B.

2003-01-01

The heat flux from both gas convection and chamber radiation on a direct drive target must be limited to avoid target damage from excessive D-T temperature increase. One of the possibilities of protecting the target is a wake shield flying in front of the target. A shield will also reduce drag force on the target, thereby facilitating target tracking and position prediction. A Direct Simulation Monte Carlo (DSMC) code was used to calculate convection heat loads as boundary conditions input into ANSYS thermal calculations. These were used for studying the quality of target protection depending on various shapes of shields, target-shield distance, and protective properties of the shield moving relative to the target. The results show that the shield can reduce the convective heat flux by a factor of 2 to 5 depending on pressure, temperature, and velocity. The protective effect of a shield moving relative to the target is greater than the protective properties of a fixed shield. However, the protective effect of a shield moving under the drag force is not sufficient for bringing the heat load on the target down to the necessary limit. Some other ways of diminishing heat flux using a protective shield are discussed

Dependences of microstructure on electromagnetic interference shielding properties of nano-layered Ti3AlC2 ceramics.

Science.gov (United States)

Tan, Yongqiang; Luo, Heng; Zhou, Xiaosong; Peng, Shuming; Zhang, Haibin

2018-05-21

The microstructure dependent electromagnetic interference (EMI) shielding properties of nano-layered Ti 3 AlC 2 ceramics were presented in this study by comparing the shielding properties of various Ti 3 AlC 2 ceramics with distinct microstructures. Results indicate that Ti 3 AlC 2 ceramics with dense microstructure and coarse grains are more favourable for superior EMI shielding efficiency. High EMI shielding effectiveness over 40 dB at the whole Ku-band frequency range was achieved in Ti 3 AlC 2 ceramics by microstructure optimization, and the high shielding effectiveness were well maintained up to 600 °C. A further investigation reveals that only the absorption loss displays variations upon modifying microstructure by allowing more extensive multiple reflections in coarse layered grains. Moreover, the absorption loss of Ti 3 AlC 2 was found to be much higher than those of highly conductive TiC ceramics without layered structure. These results demonstrate that nano-layered MAX phase ceramics are promising candidates of high-temperature structural EMI shielding materials and provide insightful suggestions for achieving high EMI shielding efficiency in other ceramic-based shielding materials.

Neutron shieldings

International Nuclear Information System (INIS)

Tarutani, Kohei

1979-01-01

Purpose: To decrease the stresses resulted by the core bendings to the base of an entrance nozzle. Constitution: Three types of round shielding rods of different diameter are arranged in a hexagonal tube. The hexagonal tube is provided with several spacer pads receiving the loads from the core constrain mechanism at its outer circumference, a handling head for a fuel exchanger at its top and an entrance nozzle for self-holding the neutron shieldings and flowing heat-removing coolants at its bottom. The diameters for R 1 , R 2 and R 3 for the round shielding rods are designed as: 0.1 R 1 2 1 and 0.2 R 1 2 1 . Since a plurality of shielding rods of small diameter are provided, soft structure are obtained and a plurality of coolant paths are formed. (Furukawa, Y.)

Spiral MRI on a 9.4T Vertical-bore Superconducting Magnet Using Unshielded and Self-shielded Gradient Coils.

Science.gov (United States)

Kodama, Nao; Setoi, Ayana; Kose, Katsumi

2018-04-10

Spiral MRI sequences were developed for a 9.4T vertical standard bore (54 mm) superconducting magnet using unshielded and self-shielded gradient coils. Clear spiral images with 64-shot scan were obtained with the self-shielded gradient coil, but severe shading artifacts were observed for the spiral-scan images acquired with the unshielded gradient coil. This shading artifact was successfully corrected with a phase-correction technique using reference scans that we developed based on eddy current field measurements. We therefore concluded that spiral imaging sequences can be installed even for unshielded gradient coils if phase corrections are performed using the reference scans.

Measurement of the thermal neutron self shielding coefficient in the Syrian miniature neutron source reactor inner irradiation site using the dy soils

International Nuclear Information System (INIS)

Khattab, K.; Khamis, I.

2007-01-01

Measurement of the thermal self shielding coefficient ( Gth ) in the Syrian Miniature Neutron Source Reactor (MNSR) inner irradiation site using Dy foils is presented in this paper. The thermal self shielding coefficient is measured as a function of the foil thickness or numbers. The mathematical equation which calculates the average relative radioactivity (Bq/g) versus the foil number is found as well.

Self-similar regimes of fast ionization waves in shielded discharge tubes

International Nuclear Information System (INIS)

Gerasimov, D.N.; Sinkevich, O.A.

1999-01-01

An analytical self-similar solution to the problem of the propagation of a fast ionization wave (FIW) in a long shielded tube is constructed. An expression determining the influence of the device parameters on the FIW velocity is obtained; the velocity is found to be the nonmonotonic function of the working-gas pressure. The theoretical predictions are compared with the results of experiments carried out with helium and nitrogen. The calculation and experimental results agree within experimental errors

Evaluation of temperature dependent neutron resonance integrals

International Nuclear Information System (INIS)

Menon, S.V.G.; Sahni, D.C.

1975-01-01

The Fourier transform method is extended for evaluating temperature dependent resonance integrals and Doppler coefficients. With the temperature dependent cross-sections, the slowing-down equation is transformed into a Fredholm integral equation of second kind. A method of solution is presented using the familiar Gauss-Hermite quadrature formulae. As a byproduct of the above technique, a fast and accurate method for computing the resonance integral J-function is given. (orig.) [de

Self-shielding factors for TLD-600 and TLD-100 in an isotropic flux of thermal neutrons

International Nuclear Information System (INIS)

Horowitz, Y.S.; Dubi, A.; Ben Shahar, B.

1976-01-01

The applications of lithium fluoride thermoluminescent dosemeters in mixed n-γ environments, and the dependence of LiF-TL on linear energy transfer are both topics of current interest. Monte Carlo calculations have therefore been carried out to determine the thermal neutron absorption probability (and consequently the self-shielding factor) for an isotropic flux of neutrons impinging on different sized cylindrical samples of LiF TLD-100 and TLD-600. The calculations were performed for cylinders of radius up to 10 cm and heights of 0.1 to 1.5 cm. The Monte Carlo results were found to be significantly different from the analytic calculations for infinitely long cylinders, but, as expected, converged to the same value for (r/h) << 1. (U.K.)

Spiral MRI on a 9.4T Vertical-bore Superconducting Magnet Using Unshielded and Self-shielded Gradient Coils

Science.gov (United States)

Kodama, Nao; Setoi, Ayana; Kose, Katsumi

2018-01-01

Spiral MRI sequences were developed for a 9.4T vertical standard bore (54 mm) superconducting magnet using unshielded and self-shielded gradient coils. Clear spiral images with 64-shot scan were obtained with the self-shielded gradient coil, but severe shading artifacts were observed for the spiral-scan images acquired with the unshielded gradient coil. This shading artifact was successfully corrected with a phase-correction technique using reference scans that we developed based on eddy current field measurements. We therefore concluded that spiral imaging sequences can be installed even for unshielded gradient coils if phase corrections are performed using the reference scans. PMID:28367906

Self-other resonance, its control and prosocial inclinations: Brain-behavior relationships.

Science.gov (United States)

Christov-Moore, Leonardo; Iacoboni, Marco

2016-04-01

Humans seem to place a positive reward value on prosocial behavior. Evidence suggests that this prosocial inclination is driven by our reflexive tendency to share in the observed sensations, emotions and behavior of others, or "self-other resonance". In this study, we examine how neural correlates of self-other resonance relate to prosocial decision-making. Subjects performed two tasks while undergoing fMRI: observation of a human hand pierced by a needle, and observation and imitation of emotional facial expressions. Outside the scanner, subjects played the Dictator Game with players of low or high income (represented by neutral-expression headshots). Subjects' offers in the Dictator Game were correlated with activity in neural systems associated with self-other resonance and anticorrelated with activity in systems implicated in the control of pain, affect, and imitation. Functional connectivity between areas involved in self-other resonance and top-down control was negatively correlated with subjects' offers. This study suggests that the interaction between self-other resonance and top-down control processes are an important component of prosocial inclinations towards others, even when biological stimuli associated with self-other resonance are limited. These findings support a view of prosocial decision-making grounded in embodied cognition. © 2016 Wiley Periodicals, Inc.

Acoustic Metacages for Omnidirectional Sound Shielding

OpenAIRE

Shen, Chen; Xie, Yangbo; Li, Junfei; Cummer, Steven A.; Jing, Yun

2017-01-01

Conventional sound shielding structures typically prevent fluid transport between the exterior and interior. A design of a two-dimensional acoustic metacage with subwavelength thickness which can shield acoustic waves from all directions while allowing steady fluid flow is presented in this paper. The structure is designed based on acoustic gradient-index metasurfaces composed of open channels and shunted Helmholtz resonators. The strong parallel momentum on the metacage surface rejects in-pl...

Uncertainty of Doppler reactivity worth due to uncertainties of JENDL-3.2 resonance parameters

Energy Technology Data Exchange (ETDEWEB)

Zukeran, Atsushi [Hitachi Ltd., Hitachi, Ibaraki (Japan). Power and Industrial System R and D Div.; Hanaki, Hiroshi; Nakagawa, Tuneo; Shibata, Keiichi; Ishikawa, Makoto

1998-03-01

Analytical formula of Resonance Self-shielding Factor (f-factor) is derived from the resonance integral (J-function) based on NR approximation and the analytical expression for Doppler reactivity worth ({rho}) is also obtained by using the result. Uncertainties of the f-factor and Doppler reactivity worth are evaluated on the basis of sensitivity coefficients to the resonance parameters. The uncertainty of the Doppler reactivity worth at 487{sup 0}K is about 4 % for the PNC Large Fast Breeder Reactor. (author)

Homogenized boundary conditions and resonance effects in Faraday cages

Science.gov (United States)

Hewitt, I. J.

2016-01-01

We present a mathematical study of two-dimensional electrostatic and electromagnetic shielding by a cage of conducting wires (the so-called ‘Faraday cage effect’). Taking the limit as the number of wires in the cage tends to infinity, we use the asymptotic method of multiple scales to derive continuum models for the shielding, involving homogenized boundary conditions on an effective cage boundary. We show how the resulting models depend on key cage parameters such as the size and shape of the wires, and, in the electromagnetic case, on the frequency and polarization of the incident field. In the electromagnetic case, there are resonance effects, whereby at frequencies close to the natural frequencies of the equivalent solid shell, the presence of the cage actually amplifies the incident field, rather than shielding it. By appropriately modifying the continuum model, we calculate the modified resonant frequencies, and their associated peak amplitudes. We discuss applications to radiation containment in microwave ovens and acoustic scattering by perforated shells. PMID:27279775

Homogenized boundary conditions and resonance effects in Faraday cages

Science.gov (United States)

Hewett, D. P.; Hewitt, I. J.

2016-05-01

We present a mathematical study of two-dimensional electrostatic and electromagnetic shielding by a cage of conducting wires (the so-called `Faraday cage effect'). Taking the limit as the number of wires in the cage tends to infinity, we use the asymptotic method of multiple scales to derive continuum models for the shielding, involving homogenized boundary conditions on an effective cage boundary. We show how the resulting models depend on key cage parameters such as the size and shape of the wires, and, in the electromagnetic case, on the frequency and polarization of the incident field. In the electromagnetic case, there are resonance effects, whereby at frequencies close to the natural frequencies of the equivalent solid shell, the presence of the cage actually amplifies the incident field, rather than shielding it. By appropriately modifying the continuum model, we calculate the modified resonant frequencies, and their associated peak amplitudes. We discuss applications to radiation containment in microwave ovens and acoustic scattering by perforated shells.

Calculation of thermal neutron self-shielding correction factors for aqueous bulk sample prompt gamma neutron activation analysis using the MCNP code

International Nuclear Information System (INIS)

Nasrabadi, M.N.; Jalali, M.; Mohammadi, A.

2007-01-01

In this work thermal neutron self-shielding in aqueous bulk samples containing neutron absorbing materials is studied using bulk sample prompt gamma neutron activation analysis (BSPGNAA) with the MCNP code. The code was used to perform three dimensional simulations of a neutron source, neutron detector and sample of various material compositions. The MCNP model was validated against experimental measurements of the neutron flux performed using a BF 3 detector. Simulations were performed to predict thermal neutron self-shielding in aqueous bulk samples containing neutron absorbing solutes. In practice, the MCNP calculations are combined with experimental measurements of the relative thermal neutron flux over the sample's surface, with respect to a reference water sample, to derive the thermal neutron self-shielding within the sample. The proposed methodology can be used for the determination of the elemental concentration of unknown aqueous samples by BSPGNAA where knowledge of the average thermal neutron flux within the sample volume is required

Self esteem, dependency, self-efficacy and self-criticism in social anxiety disorder.

Science.gov (United States)

Iancu, Iulian; Bodner, Ehud; Ben-Zion, Itzhak Z

2015-04-01

Social anxiety disorder (SAD) is characterized by fear and avoidance in social situations where one perceives being in danger of scrutiny by others. Low self-esteem, low self-efficacy, high self-criticism and high dependency are additional potential features of SAD, and thus their examination is warranted, as is the elucidation of their inter-relationship. Thirty-two SAD subjects diagnosed with the Mini-International Neuropsychiatric Interview and 30 healthy controls, were administered the Liebowitz Social Anxiety Scale (LSAS), the Rosenberg Self Esteem Scale, the Depressive Experiences Questionnaire (DEQ) that assesses self-criticism, dependency and self-efficacy, and a socio-demographic questionnaire. We hypothesized that the SAD group would present higher scores of dependency and self-criticism and lower self-esteem and self-efficacy. We also hypothesized that low self-esteem, low self-efficacy, high self-criticism and high dependency will predict the severity of SAD. In line with the hypotheses, SAD patients had higher scores of self-criticism and dependency and lower scores of self-esteem. The social anxiety score correlated negatively with self-esteem and self-efficacy, and positively with dependency and self-criticism. Self-criticism, but not the other measures, predicted the total LSAS score. Self-esteem, self-criticism, dependency and self-efficacy are related to SAD and their relations should be examined in future studies that will employ larger samples. It is suggested to search for ways to affect these factors through cognitive-behavioral interventions and additional psychotherapeutic treatments. Research should also focus on the specific role of self-criticism in SAD. Copyright © 2014 Elsevier Inc. All rights reserved.

Optimal beta-ray shielding thicknesses for different therapeutic radionuclides and shielding materials

International Nuclear Information System (INIS)

Cho, Yong In; Kim, Ja Mee; Kim, Jung Hoon

2017-01-01

To better understand the distribution of deposited energy of beta and gamma rays according to changes in shielding materials and thicknesses when radionuclides are used for therapeutic nuclear medicine, a simulation was conducted. The results showed that due to the physical characteristics of each therapeutic radionuclide, the thicknesses of shielding materials at which beta-ray shielding takes place varied. Additional analysis of the shielding of gamma ray was conducted for radionuclides that emit both beta and gamma rays simultaneously with results showing shielding effects proportional to the atomic number and density of the shielding materials. Also, analysis of bremsstrahlung emission after beta-ray interactions in the simulation revealed that the occurrence of bremsstrahlung was relatively lower than theoretically calculated and varied depending on different radionuclides. (authors)

A simple method for correcting the neutron self-shielding effect of matrix and improving the analytical response in prompt gamma-ray neutron activation analysis

International Nuclear Information System (INIS)

Sudarshan, K.; Tripathi, R.; Nair, A.G.C.; Acharya, R.; Reddy, A.V.R.; Goswami, A.

2005-01-01

A simple method using an internal standard is proposed to correct for the self-shielding effect of B, Cd and Gd in a matrix. This would increase the linear dynamic range of PGNAA in analyzing samples containing these elements. The method is validated by analyzing synthetic samples containing large amounts of B, Cd, Hg and Gd, the elements having high neutron absorption cross-section, in aqueous solutions and solid forms. A simple Monte-Carlo simulation to find the extent of self-shielding in the matrix is presented. The method is applied to the analysis of titanium boride alloy containing large amount of boron. The satisfactory results obtained showed the efficacy of the method of correcting for the self-shielding effects in the sample

Disordered resonant media: Self-induced transparency versus light localization

Science.gov (United States)

Novitsky, Denis V.

2018-01-01

We propose a concept of disordered resonant media, which are characterized by random variations of their parameters along the light propagation direction. In particular, a simple model of disorder considered in the paper implies random change of the density of active particles (two-level atoms). Within this model, the effect of disorder on self-induced transparency (SIT) is analyzed using numerical simulations of light pulse propagation through the medium. The transition from the SIT to localization regime is revealed as well as its dependence on the disorder level, atom density, medium thickness, and period of random variations.

Infinite slab-shield dose calculations

International Nuclear Information System (INIS)

Russell, G.J.

1989-01-01

I calculated neutron and gamma-ray equivalent doses leaking through a variety of infinite (laminate) slab-shields. In the shield computations, I used, as the incident neutron spectrum, the leakage spectrum (<20 MeV) calculated for the LANSCE tungsten production target at 90 degree to the target axis. The shield thickness was fixed at 60 cm. The results of the shield calculations show a minimum in the total leakage equivalent dose if the shield is 40-45 cm of iron followed by 20-15 cm of borated (5% B) polyethylene. High-performance shields can be attained by using multiple laminations. The calculated dose at the shield surface is very dependent on shield material. 4 refs., 4 figs., 1 tab

Self-assembled Au nanoparticles on heated Corning glass by dc magnetron sputtering: size-dependent surface plasmon resonance tuning

Energy Technology Data Exchange (ETDEWEB)

Grammatikopoulos, S.; Pappas, S. D. [University of Patras, Laboratory of High-Tech Materials, School of Engineering (Greece); Dracopoulos, V. [Hellas-Institute of Chemical Engineering and High Temperature Chemical Processes, (FORTH/ICE-HT), Foundation for Research and Technology (Greece); Poulopoulos, P., E-mail: poulop@upatras.gr [University of Patras, Laboratory of High-Tech Materials, School of Engineering (Greece); Fumagalli, P. [Freie Universitaet Berlin, Institut fuer Experimentalphysik (Germany); Velgakis, M. J.; Politis, C. [University of Patras, Laboratory of High-Tech Materials, School of Engineering (Greece)

2013-02-15

We report on the growth of Au nanoparticles on Corning glass by direct current magnetron sputtering and on the optical absorption of the films. The substrate temperature was kept to relatively high temperatures of 100 or 450 Degree-Sign C. This lead to the growth of Au nanoparticles instead of smooth Au films as the surface energy of Au is much larger than the one of glass. The size of the particles depended on the substrate temperature and deposition time and was shown to follow a logarithmic normal distribution function. Both, the surface plasmon resonance position and bandwidth, were found to depend upon the average particle size. The surface plasmon resonance position showed a 75 nm continuous blue shift from 14 nm down to 2.5 nm average particle size. Thus, we have shown how to tune the nanoparticle size and surface plasmon resonance of Au by varying the substrate temperature and deposition time. The experimental results are reproduced reasonably using a method which is based on the size- and wavelength-dependent complex dielectric function of Au within the framework of the Mie theory for the optical properties of metallic nanospheres.

Revised neutral gas shielding model for pellet ablation - combined neutral and plasma shielding

International Nuclear Information System (INIS)

Houlberg, W.A.; Schuresko, D.D.; Attenberger, S.E.

1986-01-01

The ablation and penetration of pellets in early ORMAK and ISX-A experiments were reliably predicted by the neutral gas shielding model of Milora and Foster. These experiments demonstrated that the principle components of the model - a self-generated shield which reduces the heat flux at the plasma surface - were correct. In more recent experiments with higher temperature plasmas, this model consistently predicts greater penetration than observed in the experiments. Upgarding known limitations of the original model brings the predicted and observed penetration values into agreement. These improvements include: (1) treating the incident electrons as having distribution in energy rather than being monoenergetic; (2) including the shielding effects of cold, dense plasma extending along the magnetic field outside the neutral shield; and (3) modifying the finite plasma, self-limiting incident heat flux so that it represents a collisionless plasma limit rather than a collisional limit. Comparisons are made between the models for a selection of ISX-B Alcator-C, and TFTR shots. The net effect of the changes in the model is an increase in pellet ablation rates and decrease in penetration for current and future experiments

CO Self-Shielding as a Mechanism to Make O-16 Enriched Solids in the Solar Nebula

Science.gov (United States)

Nuth, Joseph A. III; Johnson, Natasha M.; Hill, Hugh G. M.

2014-01-01

Photochemical self-shielding of CO has been proposed as a mechanism to produce solids observed in the modern, O-16 depleted solar system. This is distinct from the relatively O-16 enriched composition of the solar nebula, as demonstrated by the oxygen isotopic composition of the contemporary sun. While supporting the idea that self-shielding can produce local enhancements in O-16 depleted solids, we argue that complementary enhancements of O-16 enriched solids can also be produced via CO-16 based, Fischer-Tropsch type (FTT) catalytic processes that could produce much of the carbonaceous feedstock incorporated into accreting planetesimals. Local enhancements could explain observed O-16 enrichment in calcium-aluminum-rich inclusions (CAIs), such as those from the meteorite, Isheyevo (CH/CHb), as well as in chondrules from the meteorite, Acfer 214 (CH3). CO selfshielding results in an overall increase in the O-17 and O-18 content of nebular solids only to the extent that there is a net loss of CO-16 from the solar nebula. In contrast, if CO-16 reacts in the nebula to produce organics and water then the net effect of the self-shielding process will be negligible for the average oxygen isotopic content of nebular solids and other mechanisms must be sought to produce the observed dichotomy between oxygen in the Sun and that in meteorites and the terrestrial planets. This illustrates that the formation and metamorphism of rocks and organics need to be considered in tandem rather than as isolated reaction networks.

Robust infrared-shielding coating films prepared using perhydropolysilazane and hydrophobized indium tin oxide nanoparticles with tuned surface plasmon resonance.

Science.gov (United States)

Katagiri, Kiyofumi; Takabatake, Ryuichi; Inumaru, Kei

2013-10-23

Robust infrared (IR)-shielding coating films were prepared by dispersing indium tin oxide (ITO) nanoparticles (NPs) in a silica matrix. Hydrophobized ITO NPs were synthesized via a liquid phase process. The surface plasmon resonance (SPR) absorption of the ITO NPs could be tuned by varying the concentration of Sn doping from 3 to 30 mol %. The shortest SPR wavelength and strongest SPR absorption were obtained for the ITO NPs doped with 10% Sn because they possessed the highest electron carrier density. Coating films composed of a continuous silica matrix homogeneously dispersed with ITO NPs were obtained using perhydropolysilazane (PHPS) as a precursor. PHPS was completely converted to silica by exposure to the vapor from aqueous ammonia at 50 °C. The prepared coating films can efficiently shield IR radiation even though they are more than 80% transparent in the visible range. The coating film with the greatest IR-shielding ability completely blocked IR light at wavelengths longer than 1400 nm. The pencil hardness of this coating film was 9H at a load of 750 g, which is sufficiently robust for applications such as automotive glass.

Self-consistent modelling of resonant tunnelling structures

DEFF Research Database (Denmark)

Fiig, T.; Jauho, A.P.

1992-01-01

We report a comprehensive study of the effects of self-consistency on the I-V-characteristics of resonant tunnelling structures. The calculational method is based on a simultaneous solution of the effective-mass Schrödinger equation and the Poisson equation, and the current is evaluated...... applied voltages and carrier densities at the emitter-barrier interface. We include the two-dimensional accumulation layer charge and the quantum well charge in our self-consistent scheme. We discuss the evaluation of the current contribution originating from the two-dimensional accumulation layer charges......, and our qualitative estimates seem consistent with recent experimental studies. The intrinsic bistability of resonant tunnelling diodes is analyzed within several different approximation schemes....

Neutral and plasma shielding model for pellet ablation

International Nuclear Information System (INIS)

Houlberg, W.A.; Milora, S.L.; Attenberger, S.E.

1987-10-01

The neutral gas shielding model for ablation of frozen hydrogenic pellets is extended to include the effects of an initial Maxwelliam distribution of incident electron energies; a cold plasma shield outside the neutral shield and extended along the magnetic field; energetic neutral beam ions and alpha particles; and self-limiting electron ablation in the collisionless plasma limit. Including the full electron distribution increases ablation, but adding the cold ionized shield reduces ablation; the net effect is a modest reduction in pellet penetration compared with the monoenergetic electron neutral shielding model with no plasma shield. Unlike electrons, fast ions can enter the neutral shield directly without passing through the cold ionized shield because their gyro-orbits are typically larger than the diameter of the cold plasma tube. Fast alpha particles should not enhance the ablation rate unless their population exceeds that expected from local classical thermalization. Fast beam ions, however, may enhance ablation in the plasma periphery if their population is high enough. Self-limiting ablation in the collisionless limit leads to a temporary distortion of the original plasma electron Maxwellian distribution function through preferential depopulation of the higher-energy electrons. 23 refs., 9 figs

Nuclear data for radiation shielding

International Nuclear Information System (INIS)

Miyasaka, Shunichi; Takahashi, Hiroshi.

1976-01-01

The third shielding expert conference was convened in Paris in Oct. 1975 for exchanging informations about the sensitivity evaluation of nuclear data in shielding calculation and integral bench mark experiment. The requirements about nuclear data presented at present from the field of nuclear design do not reflect sufficiently the requirements of shielding design, therefore it was the object to gather the requirements about nuclear data from the field of shielding. The nuclides used for shielding are numerous, and the nuclear data on these isotopes are required. Some of them cannot be ignored as the source of secondary γ-ray or in view of the radioactivation of materials. The requirements for the nuclear data of neutrons in the field of shielding are those concerning the reaction cross sections producing secondary γ-ray, the reaction cross sections including the production of secondary neutrons, elastic scattering cross sections, and total cross sections. The topics in the Paris conference about neutron shielding data are described, such as the methodology of sensitivity evaluation, the standardization of group constant libraries, the bench mark experiment on iron and sodium, and the cross section of γ-ray production. In the shielding of nuclear fission reactors, the γ-ray production owing to nuclear fission reaction is also important. In (d, t) fusion reactors, high energy neutrons are generated, and high energy γ-ray is emitted through giant E1 resonance. (Kako, I.)

Materials tests and analyses of Faraday shield tubes for ICRF [ion cyclotron resonant frequency] antennas

International Nuclear Information System (INIS)

King, J.F.; Baity, F.W.; Hoffman, D.J.; Walls, J.C.; Taylor, D.J.

1988-01-01

The ion cyclotron resonant frequency (ICRF) antennas for heating fusion plasmas require careful analysis of the materials selected for the design and the successful fabrication of high integrity braze bonds. Graphite tiles are brazed to Inconel 625 Faraday shield tubes to protect the antenna from the plasma. The bond between the graphite and Inconel tube is difficult to achieve due to the different coefficients of thermal expansion. A 2-D stress analysis showed the graphite could be bonded to Inconel with a Ag-Cu-Ti braze alloy without cracking the graphite. Brazing procedures and nondestructive examination methods have been developed for these joints. This paper presents the results of our joining development and proof testing. 2 refs., 3 figs

Self-resonant wakefield excitation by intense laser pulse in plasmas

International Nuclear Information System (INIS)

Andreev, N.E.; Pogosova, A.A.; Gorbunov, L.M.; Ramazashvili, R.R.; Kirsanov, V.I.

1993-01-01

It is demonstrated by theoretical analysis and numerical calculations that in an underdense plasma the process of three-dimensional evolution of the short and strong laser pulse (with duration equal to several plasma periods) leads to compression and self-modulation of the pulse, so that during a fairly long period of time beats of pulse amplitude generates resonantly a strong and stable plasma wakefield. The intensity of the wake-field is so high that it can provide a new promising outlook for the plasma based accelerator concept. Linear analysis of dispersion relation predicts that taking into account transverse component of wavenumber considerably increases the growth rate of resonance instability of the pulse. The numerical simulations demonstrate that considered self-focusing and resonant-modulation instability are essentially three dimensional processes. Laser field evolution in each transverse cross section of the pulse is synchronized by the regular structure of plasma wave that is excited by the pulse. The considered effect of resonant modulation has a threshold. For the pulses with the intensity below the threshold the refraction dominates and no modulation appears. The studied phenomenon can be referred to as the Self-Resonant Wakefield (SRWF) excitation that is driven by self-focusing and self-modulation of laser pulse with quite a moderate initial duration. In fact, this method of excitation differs from both suggested in Ref.1 (PBWA) and in Refs.2,3 (LWFA), being even more than the combination of these concepts. Unlike the first scheme it does not require initially the two-frequency laser pulse, since the modulation here appears in the most natural way due to evolution of the pulse. In contrast with the LWFA, the considered SRWF generation scheme gives the possibility to raise the intensity of wake-excitation due to pulse self-focusing ( initial stage) and self modulation (second stage)

Effect of interpolation error in pre-processing codes on calculations of self-shielding factors and their temperature derivatives

International Nuclear Information System (INIS)

Ganesan, S.; Gopalakrishnan, V.; Ramanadhan, M.M.; Cullan, D.E.

1986-01-01

We investigate the effect of interpolation error in the pre-processing codes LINEAR, RECENT and SIGMA1 on calculations of self-shielding factors and their temperature derivatives. We consider the 2.0347 to 3.3546 keV energy region for 238 U capture, which is the NEACRP benchmark exercise on unresolved parameters. The calculated values of temperature derivatives of self-shielding factors are significantly affected by interpolation error. The sources of problems in both evaluated data and codes are identified and eliminated in the 1985 version of these codes. This paper helps to (1) inform code users to use only 1985 versions of LINEAR, RECENT, and SIGMA1 and (2) inform designers of other code systems where they may have problems and what to do to eliminate their problems. (author)

Effect of interpolation error in pre-processing codes on calculations of self-shielding factors and their temperature derivatives

International Nuclear Information System (INIS)

Ganesan, S.; Gopalakrishnan, V.; Ramanadhan, M.M.; Cullen, D.E.

1985-01-01

The authors investigate the effect of interpolation error in the pre-processing codes LINEAR, RECENT and SIGMA1 on calculations of self-shielding factors and their temperature derivatives. They consider the 2.0347 to 3.3546 keV energy region for /sup 238/U capture, which is the NEACRP benchmark exercise on unresolved parameters. The calculated values of temperature derivatives of self-shielding factors are significantly affected by interpolation error. The sources of problems in both evaluated data and codes are identified and eliminated in the 1985 version of these codes. This paper helps to (1) inform code users to use only 1985 versions of LINEAR, RECENT, and SIGMA1 and (2) inform designers of other code systems where they may have problems and what to do to eliminate their problems

Radiation dose reduction by water shield

International Nuclear Information System (INIS)

Zeb, J.; Arshed, W.; Ahmad, S.S.

2007-06-01

This report is an operational manual of shielding software W-Shielder, developed at Health Physics Division (HPD), Pakistan Institute of Nuclear Science and Technology (PINSTECH), Pakistan Atomic Energy Commission. The software estimates shielding thickness for photons having their energy in the range 0.5 to 10 MeV. To compute the shield thickness, self absorption in the source has been neglected and the source has been assumed as a point source. Water is used as a shielding material in this software. The software is helpful in estimating the water thickness for safe handling, storage of gamma emitting radionuclide. (author)

Radiation shielding calculation using MCNP

International Nuclear Information System (INIS)

Masukawa, Fumihiro

2001-01-01

To verify the Monte Carlo code MCNP4A as a tool to generate the reference data in the shielding designs and the safety evaluations, various shielding benchmark experiments were analyzed using this code. These experiments were categorized in three types of the shielding subjects; bulk shielding, streaming, and skyshine. For the variance reduction technique, which is indispensable to get meaningful results with the Monte Carlo shielding calculation, we mainly used the weight window, the energy dependent Russian roulette and spitting. As a whole, our analyses performed enough small statistical errors and showed good agreements with these experiments. (author)

TIMS-1: a processing code for production of group constants of heavy resonant nuclei

International Nuclear Information System (INIS)

Takano, Hideki; Ishiguro, Yukio; Matsui, Yasushi.

1980-09-01

The TIMS-1 code calculates the infinitely dilute group cross sections and the temperature dependent self-shielding factors for arbitrary values of σ 0 and R, where σ 0 is the effective background cross section of potential scattering and R the ratio of the atomic number densities for two resonant nuclei if any. This code is specifically programmed to use the evaluated nuclear data file of ENDF/B or JENDL as input data. In the unresolved resonance region, the resonance parameters and the level spacings are generated by using Monte Carlo method from the Porter-Thomas and Wigner distributions respectively. The Doppler broadened cross sections are calculated on the ultra-fine lethargy meshes of about 10 -3 -- 10 -5 using the generated and resolved resonance parameters. The effective group constants are calculated by solving the neutron slowing down equation with the use of the recurrence formula for the neutron slowing down source. The output of the calculated results is given in a format being consistent with the JAERI-Fast set (JFS) or the Standard Reactor Analysis Code (SRAC) library. Both FACOM 230/75 and M200 versions of TIMS-1 are available. (author)

Resonance analysis and evaluation of the 235U neutron induced cross sections

International Nuclear Information System (INIS)

Leal, L.C.

1990-06-01

Neutron cross sections of fissile nuclei are of considerable interest for the understanding of parameters such as resonance absorption, resonance escape probability, resonance self-shielding,and the dependence of the reactivity on temperature. In the present study, new techniques for the evaluation of the 235 U neutron cross sections are described. The Reich-Moore formalism of the Bayesian computer code SAMMY was used to perform consistent R-matrix multilevel analyses of the selected neutron cross-section data. The Δ 3 -statistics of Dyson and Mehta, along with high-resolution data and the spin-separated fission cross-section data, have provided the possibility of developing a new methodology for the analysis and evaluation of neutron-nucleus cross sections. The results of the analysis consists of a set of resonance parameters which describe the 235 U neutron cross sections up to 500 eV. The set of resonance parameters obtained through a R-matrix analysis are expected to satisfy statistical properties which lead to information on the nuclear structure. The resonance parameters were tested and showed good agreement with the theory. It is expected that the parametrization of the 235 U neutron cross sections obtained in this dissertation represents the current state of art in data as well as in theory and, therefore, can be of direct use in reactor calculations. 44 refs., 21 figs., 8 tabs

Nd:YAG (2 omega) pumped dye laser using self-filtering unstable resonator

CERN Document Server

Rahimian, K; Hariri, H

2002-01-01

A self-filtering unstable resonator with a magnification of M=-3 in a Nd:YAG (2 omega) dye laser has been studied. The dye solution is Rhodamine 6 G in alcohol with the concentration of 5*10 sub - 3 Mol/lit. The spatial intensity distribution of the resonator has been compared has been compared with that of a plane-parallel resonator of equal length. The output energy in both configurations are comparable (20 mu J ,and 26 mu J ,respectively). A significant difference between these two resonators is the laser beam divergence, where beam divergences of 0.77 mrad for the self-filtering unstable resonator and 1.6 mrad for the plane-parallel resonator have been measured. The brightness corresponding to these two resonators are 1.5* 10 sub 1 1 and 2.2* 10 sub 1 0W.cm sub - 2.Sr sub - 1, and the pulse widths are 7 and 17 ns, respectively. These figures show clearly that laser resonator based on the self-filtering unstable resonator design an increase the laser brightness a factor of 10, with a beam divergence of a f...

Relativistic heavy-atom effects on heavy-atom nuclear shieldings

Science.gov (United States)

Lantto, Perttu; Romero, Rodolfo H.; Gómez, Sergio S.; Aucar, Gustavo A.; Vaara, Juha

2006-11-01

The principal relativistic heavy-atom effects on the nuclear magnetic resonance (NMR) shielding tensor of the heavy atom itself (HAHA effects) are calculated using ab initio methods at the level of the Breit-Pauli Hamiltonian. This is the first systematic study of the main HAHA effects on nuclear shielding and chemical shift by perturbational relativistic approach. The dependence of the HAHA effects on the chemical environment of the heavy atom is investigated for the closed-shell X2+, X4+, XH2, and XH3- (X =Si-Pb) as well as X3+, XH3, and XF3 (X =P-Bi) systems. Fully relativistic Dirac-Hartree-Fock calculations are carried out for comparison. It is necessary in the Breit-Pauli approach to include the second-order magnetic-field-dependent spin-orbit (SO) shielding contribution as it is the larger SO term in XH3-, XH3, and XF3, and is equally large in XH2 as the conventional, third-order field-independent spin-orbit contribution. Considering the chemical shift, the third-order SO mechanism contributes two-thirds of the difference of ˜1500ppm between BiH3 and BiF3. The second-order SO mechanism and the numerically largest relativistic effect, which arises from the cross-term contribution of the Fermi contact hyperfine interaction and the relativistically modified spin-Zeeman interaction (FC/SZ-KE), are isotropic and practically independent of electron correlation effects as well as the chemical environment of the heavy atom. The third-order SO terms depend on these factors and contribute both to heavy-atom shielding anisotropy and NMR chemical shifts. While a qualitative picture of heavy-atom chemical shifts is already obtained at the nonrelativistic level of theory, reliable shifts may be expected after including the third-order SO contributions only, especially when calculations are carried out at correlated level. The FC/SZ-KE contribution to shielding is almost completely produced in the s orbitals of the heavy atom, with values diminishing with the principal

Impact of MCNP unresolved resonance probability-table treatment on uranium and plutonium benchmarks

International Nuclear Information System (INIS)

Mosteller, R.D.; Little, R.C.

1998-01-01

Versions of MCNP up through and including 4B have not accurately modeled neutron self-shielding effects in the unresolved resonance energy region. Recently, a probability-table treatment has been incorporated into a developmental version of MCNP. This paper presents MCNP results for a variety of uranium and plutonium critical benchmarks, calculated with and without the probability-table treatment

Two-dimensional shielding benchmarks for iron at YAYOI, (1)

International Nuclear Information System (INIS)

Oka, Yoshiaki; An, Shigehiro; Kasai, Shigeru; Miyasaka, Shun-ichi; Koyama, Kinji.

The aim of this work is to assess the collapsed neutron and gamma multigroup cross sections for two dimensional discrete ordinate transport code. Two dimensional distributions of neutron flux and gamma ray dose through a 70cm thick and 94cm square iron shield were measured at the fast neutron source reactor ''YAYOI''. The iron shield was placed over the lead reflector in the vertical experimental column surrounded by heavy concrete wall. The detectors used in this experiment were threshold detectors In, Ni, Al, Mg, Fe and Zn, sandwitch resonance detectors Au, W and Co, activation foils Au for neutrons and thermoluminescence detectors for gamma ray dose. The experimental results were compared with the calculated ones by the discrete ordinate transport code ANISN and TWOTRAN. The region-wise, coupled neutron-gamma multigroup cross-sections (100n+20gamma, EURLIB structure) were generated from ENDF/B-IV library for neutrons and POPOP4 library for gamma-ray production cross-sections by using the code system RADHEAT. The effective microscopic neutron cross sections were obtained from the infinite dilution values applying ABBN type self-shielding factors. The gamma ray production multigroup cross-sections were calculated from these effective microscopic neutron cross-sections. For two-dimensional calculations the group constants were collapsed into 10 neutron groups and 3 gamma groups by using ANISN. (auth.)

Compensating amplitude-dependent tune-shift without driving fourth-order resonances

Science.gov (United States)

Ögren, J.; Ziemann, V.

2017-10-01

If octupoles are used in a ring to correct the amplitude-dependent tune-shift one normally tries to avoid that the octupoles drive additional resonances. Here we consider the optimum placement of octupoles that only affects the amplitude-dependent tune-shift, but does not drive fourth-order resonances. The simplest way turns out to place three equally powered octupoles with 60 ° phase advance between adjacent magnets. Using two such octupole triplets separated by a suitable phase advance cancels all fourth-order resonance driving terms and forms a double triplet we call a six-pack. Using three six-packs at places with different ratios of the beta functions allows to independently control all amplitude-dependent tune-shift terms without exciting additional fourth-order resonances in first order of the octupole excitation.

Magnetic shielding for MRI superconducting magnets

International Nuclear Information System (INIS)

Ishiyama, A.; Hirooka, H.

1991-01-01

This paper describes an optimal design of a highly homogeneous superconducting coil system with magnetic shielding for Magnetic Resonance Imaging (MRI). The presented optimal design method; which is originally proposed in our earlier papers, is a combination of the hybrid finite element and boundary element method for analysis of an axially symmetric nonlinear open boundary magnetic field problem, and the mathematical programming method for solving the corresponding optimization problem. In this paper, the multi-objective goal programming method and the nonlinear least squares method have been adopted. The optimal design results of 1.5- and 4.7-Tesla-magnet systems with different types of magnetic shielding for whole-body imaging are compared and the advantages of a combination of active and yoke shields are shown

Radiation transport and shielding information, computer codes, and nuclear data for use in CTR neutronics research and development

International Nuclear Information System (INIS)

Santoro, R.T.; Maskewitz, B.F.; Roussin, R.W.; Trubey, D.K.

1976-01-01

The activities of the Radiation Shielding Information Center (RSIC) of the Oak Ridge National Laboratory are being utilized in support of fusion reactor technology. The major activities of RSIC include the operation of a computer-based information storage and retrieval system, the collection, packaging, and distribution of large computer codes, and the compilation and dissemination of processed and evaluated data libraries, with particular emphasis on neutron and gamma-ray cross-section data. The Center has acquired thirteen years of experience in serving fission reactor, weapons, and accelerator shielding research communities, and the extension of its technical base to fusion reactor research represents a logical progression. RSIC is currently working with fusion reactor researchers and contractors in computer code development to provide tested radiation transport and shielding codes and data library packages. Of significant interest to the CTR community are the 100 energy group neutron and 21 energy group gamma-ray coupled cross-section data package (DLC-37) for neutronics studies, a comprehensive 171 energy group neutron and 36 energy group gamma-ray coupled cross-section data base with retrieval programs, including resonance self-shielding, that are tailored to CTR application, and a data base for the generation of energy-dependent atomic displacement and gas production cross sections and heavy-particle-recoil spectra for estimating radiation damage to CTR structural components. Since 1964, the Center has been involved in the international exchange of information, encouraged and supported by both government and interagency agreements; and to achieve an equally viable and successful program in fusion research, the reciprocal exchange of CTR data and computing technology is encouraged and welcomed

Effect of metal shielding on a wireless power transfer system

Science.gov (United States)

Li, Jiacheng; Huang, Xueliang; Chen, Chen; Tan, Linlin; Wang, Wei; Guo, Jinpeng

2017-05-01

In this paper, the effect of non-ferromagnetic metal shielding (NFMS) material on the resonator of wireless power transfer (WPT) is studied by modeling, simulation and experimental analysis. And, the effect of NFMS material on the power transfer efficiency (PTE) of WPT systems is investigated by circuit model. Meanwhile, the effect of ferromagnetic metal shielding material on the PTE of WPT systems is analyzed through simulation. A double layer metal shield structure is designed. Experimental results demonstrate that by applying the novel double layer metal shielding method, the system PTE increases significantly while the electromagnetic field of WPT systems declines dramatically.

Evaluation and analysis of nuclear resonance data

International Nuclear Information System (INIS)

Frohner, F.H.

2000-01-01

A probabilistic foundations of data evaluation are reviewed, with special emphasis on parameter estimation based on Bayes' theorem and a quadratic loss function, and on modern methods for the assignment of prior probabilities. The data reduction process leading from raw experimental data to evaluated computer files of nuclear reaction cross sections is outlined, with a discussion of systematic and statistical errors and their propagation and of the generalized least squares formalism including prior information and nonlinear theoretical models. It is explained how common errors induce correlations between data, what consequences they have for uncertainty propagation and sensitivity studies, and how evaluators can construct covariance matrices from the usual error information provided by experimentalists. New techniques for evaluation of inconsistent data are also presented. The general principles are then applied specifically to the analysis and evaluation of neutron resonance data in terms of theoretical models - R-matrix theory (and especially its practically used multi-level Breit-Wigner and Reich-Moore variants) in the resolved region, and resonance-averaged R-matrix theory (Hauser-Feshbach theory with width-fluctuation corrections) in the unresolved region. Complications arise because the measured transmission data, capture and fission yields, self-indication ratios and other observables are not yet the wanted cross sections. These are obtained only by means of parametrisation. The intervening effects - Doppler and resolution broadening, self-shielding, multiple scattering, backgrounds, sample impurities, energy-dependent detector efficiencies, inaccurate reference data etc - are therefore also discussed. (author)

Self-excited nonlinear plasma series resonance oscillations in geometrically symmetric capacitively coupled radio frequency discharges

International Nuclear Information System (INIS)

Donko, Z.; Schulze, J.; Czarnetzki, U.; Luggenhoelscher, D.

2009-01-01

At low pressures, nonlinear self-excited plasma series resonance (PSR) oscillations are known to drastically enhance electron heating in geometrically asymmetric capacitively coupled radio frequency discharges by nonlinear electron resonance heating (NERH). Here we demonstrate via particle-in-cell simulations that high-frequency PSR oscillations can also be excited in geometrically symmetric discharges if the driving voltage waveform makes the discharge electrically asymmetric. This can be achieved by a dual-frequency (f+2f) excitation, when PSR oscillations and NERH are turned on and off depending on the electrical discharge asymmetry, controlled by the phase difference of the driving frequencies

Experiments at the GELINA facility for the validation of the self-indication neutron resonance densitometry technique

Directory of Open Access Journals (Sweden)

Rossa Riccardo

2017-01-01

Full Text Available Self-Indication Neutron Resonance Densitometry (SINRD is a passive non-destructive method that is being investigated to quantify the 239Pu content in a spent fuel assembly. The technique relies on the energy dependence of total cross sections for neutron induced reaction. The cross sections show resonance structures that can be used to quantify the presence of materials in objects, e.g. the total cross-section of 239Pu shows a strong resonance close to 0.3 eV. This resonance will cause a reduction of the number of neutrons emitted from spent fuel when 239Pu is present. Hence such a reduction can be used to quantify the amount of 239Pu present in the fuel. A neutron detector with a high sensitivity to neutrons in this energy region is used to enhance the sensitivity to 239Pu. This principle is similar to self-indication cross section measurements. An appropriate detector can be realized by surrounding a 239Pu-loaded fission chamber with appropriate neutron absorbing material. In this contribution experiments performed at the GELINA time-of-flight facility of the JRC at Geel (Belgium to validate the simulations are discussed. The results confirm that the strongest sensitivity to the target material was achieved with the self-indication technique, highlighting the importance of using a 239Pu fission chamber for the SINRD measurements.

Shielding Factor Method for producing effective cross sections: MINX/SPHINX and the CCCC interface system

International Nuclear Information System (INIS)

MacFarlane, R.E.; Weisbin, C.R.; Paik, N.C.

1978-01-01

The Shielding Factor Method (SFM) is an economical designer-oriented method for producing the coarse-group space and energy self-shielded cross sections needed for reactor-core analysis. Extensive experience with the ETOX/1DX and ENDRUN/TDOWN systems has made the SFM the method of choice for most US fast-reactor design activities. The MINX/SPHINX system was designed to expand upon the capabilities of the older SFM codes and to incorporate the new standard interfaces for fast-reactor cross sections specified by the Committee for Computer Code Coordination (CCCC). MINX is the cross-section processor. It generates multigroup cross sections, shielding factors, and group-to-group transfer matriccs from ENDF/B-IV and writes them out as CCCC ISOTXS and BRKOXS files. It features detailed pointwise resonance reconstruction, accurate Doppler broadening, and an efficient treatment of anisotropic scattering. SPHINX is the space-and-energy shielding code. It uses specific mixture and geometry information together with equivalence principles to construct shielded macroscopic multigroup cross sections in as many as 240 groups. It then makes a flux calculation by diffusion or transport methods and collapses to an appropriate set of cell-averaged coarse-group effective cross sections. The integration of MINX and SPHINX with the CCCC interface system provides an efficient, accurate, and convenient system for producing effective cross sections for use in fast-reactor problems. The system has also proved useful in shielding and CTR applications. 3 figures, 4 tables

Radiation shielding lead shield

International Nuclear Information System (INIS)

Dei, Shoichi.

1991-01-01

The present invention concerns lead shields for radiation shielding. Shield boxes are disposed so as to surround a pipeline through which radioactive liquids, mists or like other objects are passed. Flanges are formed to each of the end edges of the shield boxes and the shield boxes are connected to each other by the flanges. Upon installation, empty shield boxes not charged with lead particles and iron plate shields are secured at first at the periphery of the pipeline. Then, lead particles are charged into the shield boxes. This attains a state as if lead plate corresponding to the depth of the box is disposed. Accordingly, operations for installation, dismantling and restoration can be conducted in an empty state with reduced weight to facilitate the operations. (I.S.)

SCALE Continuous-Energy Monte Carlo Depletion with Parallel KENO in TRITON

International Nuclear Information System (INIS)

Goluoglu, Sedat; Bekar, Kursat B.; Wiarda, Dorothea

2012-01-01

The TRITON sequence of the SCALE code system is a powerful and robust tool for performing multigroup (MG) reactor physics analysis using either the 2-D deterministic solver NEWT or the 3-D Monte Carlo transport code KENO. However, as with all MG codes, the accuracy of the results depends on the accuracy of the MG cross sections that are generated and/or used. While SCALE resonance self-shielding modules provide rigorous resonance self-shielding, they are based on 1-D models and therefore 2-D or 3-D effects such as heterogeneity of the lattice structures may render final MG cross sections inaccurate. Another potential drawback to MG Monte Carlo depletion is the need to perform resonance self-shielding calculations at each depletion step for each fuel segment that is being depleted. The CPU time and memory required for self-shielding calculations can often eclipse the resources needed for the Monte Carlo transport. This summary presents the results of the new continuous-energy (CE) calculation mode in TRITON. With the new capability, accurate reactor physics analyses can be performed for all types of systems using the SCALE Monte Carlo code KENO as the CE transport solver. In addition, transport calculations can be performed in parallel mode on multiple processors.

Magnetic shielding for superconducting RF cavities

Science.gov (United States)

Masuzawa, M.; Terashima, A.; Tsuchiya, K.; Ueki, R.

2017-03-01

Magnetic shielding is a key technology for superconducting radio frequency (RF) cavities. There are basically two approaches for shielding: (1) surround the cavity of interest with high permeability material and divert magnetic flux around it (passive shielding); and (2) create a magnetic field using coils that cancels the ambient magnetic field in the area of interest (active shielding). The choice of approach depends on the magnitude of the ambient magnetic field, residual magnetic field tolerance, shape of the magnetic shield, usage, cost, etc. However, passive shielding is more commonly used for superconducting RF cavities. The issue with passive shielding is that as the volume to be shielded increases, the size of the shielding material increases, thereby leading to cost increase. A recent trend is to place a magnetic shield in a cryogenic environment inside a cryostat, very close to the cavities, reducing the size and volume of the magnetic shield. In this case, the shielding effectiveness at cryogenic temperatures becomes important. We measured the permeabilities of various shielding materials at both room temperature and cryogenic temperature (4 K) and studied shielding degradation at that cryogenic temperature.

Superhydrophobic coatings on wood substrate for self-cleaning and EMI shielding

Science.gov (United States)

Xing, Yingjie; Xue, Yaping; Song, Jinlong; Sun, Yankui; Huang, Liu; Liu, Xin; Sun, Jing

2018-04-01

A layer of superhydrophobic coating having good electromagnetic shielding and self-cleaning performance was fabricated on a wood surface through an electroless copper plated process. The superhydrophobic property of the wood surface was measured by contact angle (CA) and roll-off angle (RA) measurements. The microstructure and chemical composition of the superhydrophobic coating were analyzed by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). The analysis revealed that the microscale particles were uniformly distributed on the wood surface and the main component of the coating is metallic copper. The as-prepared Cu coatings on wood substrate exhibit a good superhydrophobicity with water contact angle about 160° and rolling angle less than 5°.

Off-resonant vibrational excitation: Orientational dependence and spatial control of photofragments

DEFF Research Database (Denmark)

Machholm, Mette; Henriksen, Niels Engholm

2000-01-01

Off-resonant and resonant vibrational excitation with short intense infrared (IR) laser pulses creates localized oscillating wave packets, but differs by the efficiency of the excitation and surprisingly by the orientational dependence. Orientational selectivity of the vibrational excitation...... of randomly oriented heteronuclear diatomic molecules can be obtained under simultaneous irradiation by a resonant and an off-resonant intense IR laser pulse: Molecules with one initial orientation will be vibrationally excited, while those with the opposite orientation will be at rest. The orientation-dependent...... distribution. (C) 2000 American Institute of Physics....

Effect of metal shielding on a wireless power transfer system

Directory of Open Access Journals (Sweden)

Jiacheng Li

2017-05-01

Full Text Available In this paper, the effect of non-ferromagnetic metal shielding (NFMS material on the resonator of wireless power transfer (WPT is studied by modeling, simulation and experimental analysis. And, the effect of NFMS material on the power transfer efficiency (PTE of WPT systems is investigated by circuit model. Meanwhile, the effect of ferromagnetic metal shielding material on the PTE of WPT systems is analyzed through simulation. A double layer metal shield structure is designed. Experimental results demonstrate that by applying the novel double layer metal shielding method, the system PTE increases significantly while the electromagnetic field of WPT systems declines dramatically.

The new solid target system at UNAM in a self-shielded 11 MeV cyclotron

International Nuclear Information System (INIS)

Zarate-Morales, A.; Gaspar-Carcamo, R. E.; Lopez-Rodriguez, V.; Flores-Moreno, A.; Trejo-Ballado, F.; Avila-Rodriguez, Miguel A.

2012-01-01

A dual beam line (BL) self-shielded RDS 111 cyclotron for radionuclide production was installed at the School of Medicine of the National Autonomous University of Mexico in 2001. One of the BL’s was upgraded to Eclipse HP (Siemens) in 2008 and the second BL was recently upgraded (June 2011) to the same version with the option for the irradiation of solid targets for the production of metallic radioisotopes.

Technology development for radiation shielding analysis

International Nuclear Information System (INIS)

Ha, Jung Woo; Lee, Jae Kee; Kim, Jong Kyung

1986-12-01

Radiation shielding analysis in nuclear engineering fields is an important technology which is needed for the calculation of reactor shielding as well as radiation related safety problems in nuclear facilities. Moreover, the design technology required in high level radioactive waste management and disposal facilities is faced on serious problems with rapidly glowing nuclear industry development, and more advanced technology has to be developed for tomorrow. The main purpose of this study is therefore to build up the self supporting ability of technology development for the radiation shielding analysis in order to achieve successive development of nuclear industry. It is concluded that basic shielding calculations are possible to handle and analyze by using our current technology, but more advanced technology is still needed and has to be learned for the degree of accuracy in two-dimensional shielding calculation. (Author)

Deep-penetration calculations in concrete and iron for shielding of proton therapy accelerators

International Nuclear Information System (INIS)

Sheu, Rong-Jiun; Chen, Yen-Fu; Lin, Uei-Tyng; Jiang, Shiang-Huei

2012-01-01

Proton accelerators in the energy range of approximately 200 MeV have become increasingly popular for cancer treatment in recent years. These proton therapy facilities usually involve bulky concrete or iron in their shielding design or accelerator structure. Simple shielding data, such as source terms or attenuation lengths for various proton energies and materials are useful in designing accelerator shielding. Understanding the appropriateness or uncertainties associated with these data, which are largely generated from Monte Carlo simulations, is critical to the quality of a shielding design. This study demonstrated and investigated the problems of deep-penetration calculations on the estimation of shielding parameters through an extensive comparison between the FLUKA and MCNPX calculations for shielding against a 200-MeV proton beam hitting an iron target. Simulations of double-differential neutron production from proton bombardment were validated by comparison with experimental data. For the concrete shielding, the FLUKA calculated depth–dose distributions were consistent with the MCNPX results, except for some discrepancies in backward directions. However, for the iron shielding, if FLUKA is used inappropriately then overestimation of neutron attenuation can be expected as shown by this work because of the multigroup treatment for low-energy neutrons in FLUKA. Two neutron energy group structures, three degrees of self-shielding correction, and two iron compositions were considered in this study. Significant variation of the resulting attenuation lengths indicated the importance of problem-dependent multigroup cross sections and proper modeling of iron composition in deep-penetration calculations.

Development of neutron shielding concrete containing iron content materials

Science.gov (United States)

Sariyer, Demet; Küçer, Rahmi

2018-02-01

Concrete is one of the most important construction materials which widely used as a neutron shielding. Neutron shield is obtained of interaction with matter depends on neutron energy and the density of the shielding material. Shielding properties of concrete could be improved by changing its composition and density. High density materials such as iron or high atomic number elements are added to concrete to increase the radiation resistance property. In this study, shielding properties of concrete were investigated by adding iron, FeB, Fe2B, stainless - steel at different ratios into concrete. Neutron dose distributions and shield design was obtained by using FLUKA Monte Carlo code. The determined shield thicknesses vary depending on the densities of the mixture formed by the additional material and ratio. It is seen that a combination of iron rich materials is enhanced the neutron shielding of capabilities of concrete. Also, the thicknesses of shield are reduced.

Isotopic dependence of GCR fluence behind shielding

International Nuclear Information System (INIS)

Cucinotta, Francis A.; Wilson, John W.; Saganti, Premkumar; Hu, Xiaodong; Kim, Myung-Hee Y.; Cleghorn, Timothy; Zeitlin, Cary; Tripathi, Ram K.

2006-01-01

In this paper we consider the effects of the isotopic composition of the primary galactic cosmic rays (GCR), nuclear fragmentation cross sections, and isotopic-grid on the solution to transport models used for shielding studies. Satellite measurements are used to describe the isotopic composition of the GCR. For the nuclear interaction data-base and transport solution, we use the quantum multiple scattering theory of nuclear fragmentation (QMSFRG) and high-charge and energy (HZETRN) transport code, respectively. The QMSFRG model is shown to accurately describe existing fragmentation data including proper description of the odd-even effects as function of the iso-spin dependence on the projectile nucleus. The principle finding of this study is that large errors (±100%) will occur in the mass-fluence spectra when comparing transport models that use a complete isotopic-grid (∼170 ions) to ones that use a reduced isotopic-grid, for example the 59 ion-grid used in the HZETRN code in the past; however, less significant errors (<+/-20%) occur in the elemental-fluence spectra. Because a complete isotopic-grid is readily handled on small computer workstations and is needed for several applications studying GCR propagation and scattering, it is recommended that they be used for future GCR studies

Chemical dependency and adolescent self-esteem.

Science.gov (United States)

Wasson, D; Anderson, M A

1995-08-01

The purpose of this descriptive study is to determine whether self-esteem differs between chemically dependent adolescents and adolescents from the general high school population. The Self-Esteem Inventory (Coopersmith, 1987) was completed by 119 adolescents (31 inpatient, 31 aftercare, and 57 general high school students) aged 13 to 18. Findings suggest that inpatient, chemically dependent adolescents have lower self-esteem than the other two groups. For the chemically dependent adolescent, nursing case management with communication among and between health care providers, school professionals, and family may facilitate successful, long-term recovery. For adolescents at risk for development of chemical dependence, nursing health promotion behaviors, such as early assessment and implementation of self-esteem-building activities, may assist in prevention of chemical dependency.

Analysis of transmission efficiency of the superconducting resonance coil according the materials of cooling system

Energy Technology Data Exchange (ETDEWEB)

Lee, Yu Kyeong; Hwang, Jun Won; Choi, Hyo Sang [Chosun University, Gwangju (Korea, Republic of)

2016-03-15

The wireless power transfer (WPT) system using a magnetic resonance was based on magnetic resonance coupling of the transmission and the receiver coils. In these system, it is important to maintain a high quality-factor (Q-factor) to increase the transmission efficiency of WPT system. Our research team used a superconducting coil to increase the Q-factor of the magnetic resonance coil in WPT system. When the superconductor is applied in these system, we confirmed that transmission efficiency of WPT system was higher than normal conductor coil through a preceding study. The efficiency of the transmission and the receiver coil is affected by the magnetic shielding effect of materials around the coils. The magnetic shielding effect is dependent on the type, thickness, frequency, distance, shape of materials. Therefore, it is necessary to study the WPT system on the basis of these conditions. In this paper, the magnetic shield properties of the cooling system were analyzed using the High-Frequency Structure Simulation (HFSS, Ansys) program. We have used the shielding materials such as plastic, aluminum and iron, etc. As a result, when we applied the fiber reinforced polymer (FRP), the transmission efficiency of WPT was not affected because electromagnetic waves went through the FRP. On the other hand, in case of a iron and aluminum, transmission efficiency was decreased because of their electromagnetic shielding effect. Based on these results, the research to improve the transmission efficiency and reliability of WPT system is continuously necessary.

RADSHI: shielding calculation program for different geometries sources

International Nuclear Information System (INIS)

Gelen, A.; Alvarez, I.; Lopez, H.; Manso, M.

1996-01-01

A computer code written in pascal language for IBM/Pc is described. The program calculates the optimum thickness of slab shield for different geometries sources. The Point Kernel Method is employed, which enables the obtention of the ionizing radiation flux density. The calculation takes into account the possibility of self-absorption in the source. The air kerma rate for gamma radiation is determined, and with the concept of attenuation length through the equivalent attenuation length the shield is obtained. The scattering and the exponential attenuation inside the shield material is considered in the program. The shield materials can be: concrete, water, iron or lead. It also calculates the shield for point isotropic neutron source, using as shield materials paraffin, concrete or water. (authors). 13 refs

A self-consistent semiclassical sum rule approach to the average properties of giant resonances

International Nuclear Information System (INIS)

Li Guoqiang; Xu Gongou

1990-01-01

The average energies of isovector giant resonances and the widths of isoscalar giant resonances are evaluated with the help of a self-consistent semiclassical Sum rule approach. The comparison of the present results with the experimental ones justifies the self-consistent semiclassical sum rule approach to the average properties of giant resonances

Temperature dependence of the resonance frequency of thermogravimetric devices

NARCIS (Netherlands)

Iervolino, E.; Riccio, M.; Van Herwaarden, A.W.; Irace, A.; Breglio, G.; Van der Vlist, W.; Sarro, P.M.

2010-01-01

This paper investigates the temperature dependence of the resonance frequency of thermogravimetric (TG) devices for tip heating over the temperature range of View the MathML source 25–600?C. The resonance frequency of a fabricated TG device shows to be temperature independent for tip heating up to

Lack of dependence on resonant error field of locked mode island size in ohmic plasmas in DIII-D

Science.gov (United States)

La Haye, R. J.; Paz-Soldan, C.; Strait, E. J.

2015-02-01

DIII-D experiments show that fully penetrated resonant n = 1 error field locked modes in ohmic plasmas with safety factor q95 ≳ 3 grow to similar large disruptive size, independent of resonant error field correction. Relatively small resonant (m/n = 2/1) static error fields are shielded in ohmic plasmas by the natural rotation at the electron diamagnetic drift frequency. However, the drag from error fields can lower rotation such that a bifurcation results, from nearly complete shielding to full penetration, i.e., to a driven locked mode island that can induce disruption. Error field correction (EFC) is performed on DIII-D (in ITER relevant shape and safety factor q95 ≳ 3) with either the n = 1 C-coil (no handedness) or the n = 1 I-coil (with ‘dominantly’ resonant field pitch). Despite EFC, which allows significantly lower plasma density (a ‘figure of merit’) before penetration occurs, the resulting saturated islands have similar large size; they differ only in the phase of the locked mode after typically being pulled (by up to 30° toroidally) in the electron diamagnetic drift direction as they grow to saturation. Island amplification and phase shift are explained by a second change-of-state in which the classical tearing index changes from stable to marginal by the presence of the island, which changes the current density profile. The eventual island size is thus governed by the inherent stability and saturation mechanism rather than the driving error field.

Contribution to study of Dancoff effect in cylindrical systems; Prilog proucavanju Dancoffovog efekta u sistemima sa cilindricnom geometrijom

Energy Technology Data Exchange (ETDEWEB)

Remsak, S [Institute of Nuclear Sciences Boris Kidric, Vinca, Beograd (Yugoslavia)

1969-09-15

This paper deals with the affect od spatial interference between fuel elements and its influence on the resonance integral. General relation for correction of shielding dependent on the first collision portability was derived. Usual assumption about totally black resonance absorber was not taken into account and spatial distribution of elements was random. Shielding effect for two rods and self-shielding effect of tube was studied in detail. Analysis of standard Dancoff problem shows that the shielding correction function is dependent on all resonance parameters, temperature, size of rods and their mutual distance and properties of the moderator. Proposed method is based on the assumption of flat fluxes which enable analytical determination of first collision probability. Influence of interference scattering was taken into account afterwards and was not treated directly. System of balance equations was solved by applying IR approximation. In order to enable easier numerical calculation of shielding correction significant simplification of obtained results was done by applying P-L approximation of Bonaloumi. Obtained numerical results show good agreement with values obtained by applying Hellstrand empirical relation for resonance integral. A simple procedure is proposed for redefining some parameters and Asiu equations which enable more precise determination of transparency coefficient of tube element.

Heating profiles on ICRF antenna Faraday shields

International Nuclear Information System (INIS)

Taylor, D.J.; Baity, F.W.; Hahs, C.L.; Riemer, B.W.; Ryan, P.M.; Williamson, D.E.

1991-01-01

A conceptual design for an uncooled Faraday shield for the BPX ion cyclotron resonance heating (ICRH) antenna, which should withstand the proposed long-pulse operation, has been completed. A high-heat-flux, uncooled Faraday shield has also been designed for the fast-wave current drive (FWCD) antenna on D3-D. For both components, the improved understanding of the heating profiles made it possible to design for heat fluxes that would otherwise have been too close to mechanically established limits. The analytical effort is described in detail, with emphasis on the design work for the BPX ICRH antenna conceptual design and for the replacement Faraday shield for the D3-D FWCD antenna. Results of analyses are shown, and configuration issues involved in component modeling are discussed. 3 refs., 6 figs., 2 tabs

Self-resonance after inflation: Oscillons, transients, and radiation domination

Science.gov (United States)

Lozanov, Kaloian D.; Amin, Mustafa A.

2018-01-01

Homogeneous oscillations of the inflaton after inflation can be unstable to small spatial perturbations even without coupling to other fields. We show that for inflaton potentials ∝|ϕ |2n near |ϕ |=0 and flatter beyond some |ϕ |=M , the inflaton condensate oscillations can lead to self-resonance, followed by its complete fragmentation. We find that for nonquadratic minima (n >1 ), shortly after backreaction, the equation of state parameter, w →1 /3 . If M ≪mPl, radiation domination is established within less than an e -fold of expansion after the end of inflation. In this case self-resonance is efficient and the condensate fragments into transient, localised spherical objects which are unstable and decay, leaving behind them a virialized field with mean kinetic and gradient energies much greater than the potential energy. This end-state yields w =1 /3 . When M ˜mPl we observe slow and steady, self-resonance that can last many e -folds before backreaction eventually shuts it off, followed by fragmentation and w →1 /3 . We provide analytical estimates for the duration to w →1 /3 after inflation, which can be used as an upper bound (under certain assumptions) on the duration of the transition between the inflationary and the radiation dominated states of expansion. This upper bound can reduce uncertainties in CMB observables such as the spectral tilt ns, and the tensor-to-scalar ratio r . For quadratic minima (n =1 ), w →0 regardless of the value of M . This is because when M ≪mPl, long-lived oscillons form within an e -fold after inflation, and collectively behave as pressureless dust thereafter. For M ˜mPl, the self-resonance is inefficient and the condensate remains intact (ignoring long-term gravitational clustering) and keeps oscillating about the quadratic minimum, again implying w =0 .

A study of gamma shielding

International Nuclear Information System (INIS)

Roogtanakait, N.

1981-01-01

Gamma rays have high penetration power and its attenuation depends upon the thickness and the attenuation coefficient of the shield, so it is necessary to use the high density shield to attenuate the gamma rays. Heavy concrete is considered to be used for high radiation laboratory and the testing of the shielding ability and compressibility of various types of heavy concrete composed of baryte, hematite, ilmenite and galena is carried out. The results of this study show that baryte-ilmenite concrete is the most suitable for high radiation laboratory in Thailand

Resonant characteristics and sensitivity dependency on the contact surface in QCM-micropillar-based system of coupled resonator sensors

International Nuclear Information System (INIS)

Kashan, M A M; Kalavally, V; Ramakrishnan, N; Lee, H W

2016-01-01

We report the characteristics and sensitivity dependence over the contact surface in coupled resonating sensors (CRSs) made of high aspect ratio resonant micropillars attached to a quartz crystal microbalance (QCM). Through experiments and simulation, we observed that when the pillars of resonant heights were placed in maximum displacement regions the resonance frequency of the QCM increased following the coupled resonance characteristics, as the pillar offered elastic loading to the QCM surface. However, the same pillars when placed in relatively lower displacement regions, in spite of their resonant dimension, offered inertial loading and resulted in a decrease in QCM resonance frequency, as the displacement amplitude was insufficient to couple the vibrations from the QCM to the pillars. Accordingly, we discovered that the coupled resonance characteristics not only depend on the resonant structure dimensions but also on the contact regions in the acoustic device. Further analysis revealed that acoustic pressure at the contact surface also influences the resonance frequency characteristics and sensitivity of the CRS. To demonstrate the significance of the present finding for sensing applications, humidity sensing is considered as the example measurand. When a sensing medium made of resonant SU-8 pillars was placed in a maximum displacement region on a QCM surface, the sensitivity increased by 14 times in comparison to a resonant sensing medium placed in a lower displacement region of a QCM surface. (paper)

Malakit: an innovative pilot project to self-diagnose and self-treat malaria among illegal gold miners in the Guiana Shield.

Science.gov (United States)

Douine, Maylis; Sanna, Alice; Galindo, Muriel; Musset, Lise; Pommier de Santi, Vincent; Marchesini, Paola; Magalhaes, Edgard Dias; Suarez-Mutis, Martha; Hiwat, Helene; Nacher, Mathieu; Vreden, Stephen; Garancher, Laure

2018-04-10

Illegal gold miners in French Guiana, a French overseas territory ('département') located in Amazonia, often carry malaria parasites (up to 46.8%). While the Guiana Shield Region aims at malaria elimination, the high prevalence of Plasmodium in this hard-to-reach population in conjunction with frequent incorrect use of artemisinin-based anti-malarials could favour the emergence of resistant parasites. Due to geographical and regulatory issues in French Guiana, usual malaria control strategies cannot be implemented in this particular context. Therefore, new strategies targeting this specific population in the forest are required. Numerous discussions among health institutions and scientific partners from French Guiana, Brazil and Suriname have led to an innovative project based on the distribution of kits for self-diagnosis and self-treatment of Plasmodium infections. The kit-distribution will be implemented at "resting sites", which are areas across the border of French Guiana regularly frequented by gold miners. The main objective is to increase the appropriate use and complete malaria treatment after a positive malaria diagnosis with a rapid test, which will be evaluated with before-and-after cross-sectional studies. Monitoring indicators will be collected from health mediators at the time of kit distribution and during subsequent visits, and from illegal gold miners themselves, through a smartphone application. The project funding is multisource, including Ministries of Health of the three countries, WHO/PAHO, and the European Union. This project will start in April 2018 as a 18 month pilot study led by the Clinical Investigation Centre of Cayenne. Results should be available at the end of 2019. This innovative approach may have several limitations which should be taken into account, as potential side effects, kit misuse or resale, declarative main criteria, or no Plasmodium vivax curative treatment. Close monitoring is thus needed. This project may be the

Parametric Resonance in a Time-Dependent Harmonic Oscillator

Directory of Open Access Journals (Sweden)

P. N. Nesterov

2013-01-01

Full Text Available In this paper, we study the phenomenon of appearance of new resonances in a timedependent harmonic oscillator under an oscillatory decreasing force. The studied equation belongs to the class of adiabatic oscillators and arises in connection with the spectral problem for the one-dimensional Schr¨odinger equation with Wigner–von Neumann type potential. We use a specially developed method for asymptotic integration of linear systems of differential equations with oscillatory decreasing coefficients. This method uses the ideas of the averaging method to simplify the initial system. Then we apply Levinson’s fundamental theorem to get the asymptotics for its solutions. Finally, we analyze the features of a parametric resonance phenomenon. The resonant frequencies of perturbation are found and the pointwise type of the parametric resonance phenomenon is established. In conclusion, we construct an example of a time-dependent harmonic oscillator (adiabatic oscillator in which the parametric resonances, mentioned in the paper, may occur.

Frequency-difference-dependent stochastic resonance in neural systems

Science.gov (United States)

Guo, Daqing; Perc, Matjaž; Zhang, Yangsong; Xu, Peng; Yao, Dezhong

2017-08-01

Biological neurons receive multiple noisy oscillatory signals, and their dynamical response to the superposition of these signals is of fundamental importance for information processing in the brain. Here we study the response of neural systems to the weak envelope modulation signal, which is superimposed by two periodic signals with different frequencies. We show that stochastic resonance occurs at the beat frequency in neural systems at the single-neuron as well as the population level. The performance of this frequency-difference-dependent stochastic resonance is influenced by both the beat frequency and the two forcing frequencies. Compared to a single neuron, a population of neurons is more efficient in detecting the information carried by the weak envelope modulation signal at the beat frequency. Furthermore, an appropriate fine-tuning of the excitation-inhibition balance can further optimize the response of a neural ensemble to the superimposed signal. Our results thus introduce and provide insights into the generation and modulation mechanism of the frequency-difference-dependent stochastic resonance in neural systems.

Highly heat removing radiation shielding material

International Nuclear Information System (INIS)

Asano, Norio; Hozumi, Masahiro.

1990-01-01

Organic materials, inorganic materials or metals having excellent radiation shielding performance are impregnated into expanded metal materials, such as Al, Cu or Mg, having high heat conductivity. Further, the porosity of the expanded metals and combination of the expanded metals and the materials to be impregnated are changed depending on the purpose. Further, a plurality of shielding materials are impregnated into the expanded metal of the same kind, to constitute shielding materials. In such shielding materials, impregnated materials provide shielding performance against radiation rays such as neutrons and gamma rays, the expanded metals provide heat removing performance respectively and they act as shielding materials having heat removing performance as a whole. Accordingly, problems of non-informity and discontinuity in the prior art can be dissolved be provide materials having flexibility in view of fabrication work. (T.M.)

Self-oscillating resonant power converter

DEFF Research Database (Denmark)

2014-01-01

The present invention relates to resonant power converters and inverters comprising a self-oscillating feedback loop coupled from a switch output to a control input of a switching network comprising one or more semiconductor switches. The self-oscillating feedback loop sets a switching frequency...... of the power converter and comprises a first intrinsic switch capacitance coupled between a switch output and a control input of the switching network and a first inductor. The first inductor is coupled in-between a first bias voltage source and the control input of the switching network and has...... a substantially fixed inductance. The first bias voltage source is configured to generate an adjustable bias voltage applied to the first inductor. The output voltage of the power converter is controlled in a flexible and rapid manner by controlling the adjustable bias voltage....

Neutron shielding material based on colemanite and epoxy resin

International Nuclear Information System (INIS)

Okuno, K.

2005-01-01

In recent years, there has been a need for compact shielding design such as self-shielding of a PET cyclotron or up-gradation of radiation machinery in existing facilities. In these cases, high performance shielding materials are needed. Concrete or polyethylene have been used for a neutron shield. However, for compact shielding, they fall short in terms of performance or durability. Therefore, a new type of neutron shielding material based on epoxy resin and colemanite has been developed. Slab attenuation experiments up to 40 cm for the new shielding material were carried out using a 252 Cf neutron source. Measurement was carried out using a REM-counter, and compared with calculation. The results show that the shielding performance is better than concrete and polyethylene mixed with 10 wt% boron oxide. From the result, we confirmed that the performance of the new material is suitable for practical use. (authors)

Program GROUPIE (version 79-1): calculation of Bondarenko self-shielded neutron cross sections and multiband parameters from data in the ENDF/B format

International Nuclear Information System (INIS)

Cullen, D.E.

1980-01-01

Program GROUPIE reads evaluated data in the ENDF/B format and uses these data to calculate Bondarenko self-shielded cross sections and multiband parameters. To give as much generality as possible, the program allows the user to specify arbitrary energy groups and an arbitrary energy groups and an arbitrary energy-dependent neutron spectrum (weighing function). To guarantee the accuracy of the results, all integrals are performed analytically; in no case is iteration or any approximate form of integration used. The output from this program includes both listings and multiband parameters suitable for use either in a normal multigroup transport calculation or in a multiband transport calculation. A listing of the source deck is available on request

A comparative study of self-regulation in substance dependent and non-dependent individuals.

Science.gov (United States)

Bakhshani, Nour Mohammad; Hosseinbor, Mohsen

2013-08-05

Several factors influence the beginning and maintenance of substance use. The purpose of this study was to examine as well as to compare 'self-regulation' in both substance dependent and non-substance dependent individuals. In a cross-sectional study 228 (118 substance dependent and 110 with no history of using substance) participants aged 16-55 were recruited. All of the participants were asked to complete the Self-Regulation Inventory (SRI-25) and a demographic characteristics data checklist. Data was analyzed using descriptive statistics (frequency, mean and standard deviation) and the t-test. The results showed significant differences between substance dependent and non- substance dependent groups in all the scales of the self-regulation inventory including positive actions, controllability, expression of feelings and needs, assertiveness, and well-being seeking (p<0.01). Self-regulation and self-control skills in drug dependent individuals are lower than those without substance dependence individuals. It is concluded that substance use may related to a deficiency in self-control and regulation of feelings. Therefore, for prevention and treatment of substance dependence disorder, it is necessary to work out and exploit strategies that include the improvement of self-regulation.

Time dependence of resonance γ-radiation modulated by acoustic excitations

International Nuclear Information System (INIS)

Mkrtchyan, A.R.; Arakelyan, A.R.; Gabrielyan, R.G.; Kocharyan, L.A.; Grigoryan, G.R.; Slavinskii, M.M.

1984-01-01

Experimental investigations of the time dependence of the γ-resonance absorption line intensity in case of modulation by acoustic waves are presented. 57 Co was used as source and a stainless steel foil was chosen as an absorber. The time dependences of the counting rate of the resonant γ-quanta corresponding to excitations with 3400 Hz and with 1.5 or 7 V at the vibrosystem transducer are plotted. The measurements show that the method has principal advantages over the conventional Moessbauer spectroscopy

Isoscalar giant resonances and Landau parameters with density-dependent effective interactions

International Nuclear Information System (INIS)

Kohno, Michio; Ando, Kazuhiko

1979-01-01

Discussion is given on the relations between the Landau parameters and the isoscalar giant (quadrupole- and monopole-) resonance energies by using general density-dependent interactions. In the limit of infinite nuclear matter, the isoscalar giant quadrupole energy is shown to depend not only on the effective mass but also on the Landau parameter F 2 . Collective energies of the isoscalar giant resonances are calculated for 16 O and 40 Ca with four different effective interactions, G-0, B1, SII and SV, by using the scaling- and constrained Hartree-Fock-methods. It is shown that the dependence of the collective energies on the effective interactions is essentially determined by the Landau parameters. The G-0 force is found to be most successful in reproducing the giant resonance energies. Validity of the RPA-moment theorems is examined for the case of local density-dependent interactions. (author)

Neutron shielding material

International Nuclear Information System (INIS)

Suzuki, Shigenori; Iimori, Hiroshi; Kobori, Junzo.

1980-01-01

Purpose: To provide a neutron shielding material which incorporates preferable shielding capacity, heat resistance, fire resistance and workability by employing a mixture of thermosetting resin, polyethylene and aluminium hydroxide in special range ratio and curing it. Constitution: A mixture containing 20 to 60% by weight of thermosetting resin having preferable heat resistance, 10 to 40% by weight of polyethylene powder having high hydrogen atom density and 1000 to 60000 of molecular weight, and 15 to 55% by weight of Al(OH) 3 for imparting fire resistance and self-fire extinguishing property thereto is cured. At this time approx. 0.5 to 5% of curing catalyst of the thermosetting resin is contained in 100 parts by weight of the mixture. (Sekiya, K.)

Self-generation of dissipative solitons in magnonic quasicrystal active ring resonator

International Nuclear Information System (INIS)

Grishin, S. V.; Beginin, E. N.; Morozova, M. A.; Sharaevskii, Yu. P.; Nikitov, S. A.

2014-01-01

Self-generation of dissipative solitons in the magnonic quasicrystal (MQC) active ring resonator is studied theoretically and experimentally. The developed magnonic crystal has quasiperiodic Fibonacci type structure. Frequency selectivity of the MQC together with the parametric three-wave decay of magnetostatic surface spin wave (MSSW) leads to the dissipative soliton self-generation. The transfer matrix method is used to describe MQC transmission responses. Besides, the model of MQC active ring resonator is suggested. The model includes three coupled differential equations describing the parametric decay of MSSW and two differential equations of linear oscillators describing the frequency selectivity of MQC. Numerical simulation results of dissipative soliton self-generation are in a fair agreement with experimental data

Self-generation of dissipative solitons in magnonic quasicrystal active ring resonator

Energy Technology Data Exchange (ETDEWEB)

Grishin, S. V., E-mail: grishfam@sgu.ru; Beginin, E. N.; Morozova, M. A.; Sharaevskii, Yu. P. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation); Nikitov, S. A. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation); Kotel' nikov Institute of Radioengineering and Electronics, Russian Academy of Science, Moscow 125009 (Russian Federation)

2014-02-07

Self-generation of dissipative solitons in the magnonic quasicrystal (MQC) active ring resonator is studied theoretically and experimentally. The developed magnonic crystal has quasiperiodic Fibonacci type structure. Frequency selectivity of the MQC together with the parametric three-wave decay of magnetostatic surface spin wave (MSSW) leads to the dissipative soliton self-generation. The transfer matrix method is used to describe MQC transmission responses. Besides, the model of MQC active ring resonator is suggested. The model includes three coupled differential equations describing the parametric decay of MSSW and two differential equations of linear oscillators describing the frequency selectivity of MQC. Numerical simulation results of dissipative soliton self-generation are in a fair agreement with experimental data.

Improved algorithms for the calculation of resolved resonance cross sections with applications to the structural Doppler effect in fast reactors

International Nuclear Information System (INIS)

Hwang, R.N.; Toppel, B.J.; Henryson, H. II.

1980-10-01

Motivated by a need for an economical yet rigorous tool which can address the computation of the structural material Doppler effect, an extremely efficient improved RABANL capability has been developed utilizing the fact that the Doppler broadened line shape functions become essentially identical to the natural line shape functions or Lorentzian limits beyond about 100 Doppler widths from the resonance energy, or when the natural width exceeds about 200 Doppler widths. The computational efficiency has been further enhanced by preprocessing or screening a significant number of selected resonances during library preparation into composition and temperature independent smooth background cross sections. The resonances which are suitable for such pre-processing are those which are either very broad or those which are very weak. The former contribute very little to the Doppler effect and their self-shielding effect can readily be averaged into slowly varying background cross section data, while the latter contribute very little to either the Doppler or to self-shielding effects. To illustrate the accuracy and efficiency of the improved RABANL algorithms and resonance screening techniques, calculations have been performed for two systems, the first with a composition typical of the STF converter region and the second typical of an LMFBR core composition. Excellent agreement has been found for RABANL compared to the reference Monte Carlo solution obtained using the code VIM, and improved results have also been obtained for the narrow resonance approximation in the ultra-fine-group option of MC 2 -2

Graphs of neutron cross sections in JSD1000 for radiation shielding safety analysis

International Nuclear Information System (INIS)

Yamano, Naoki

1984-03-01

Graphs of neutron cross sections and self-shielding factors in the JSD1000 library are presented for radiation shielding safety analysis. The compilation contains various reaction cross sections for 42 nuclides from 1 H to 241 Am in the energy range from 3.51 x 10 -4 eV to 16.5 MeV. The Bondarenko-type self-shielding factors of each reaction are given by the background cross sections from σ 0 = 0 to σ 0 = 10000. (author)

RF MEMS Fractal Capacitors With High Self-Resonant Frequencies

KAUST Repository

Elshurafa, Amro M.; Emira, Ahmed; Radwan, Ahmed Gomaa; Salama, Khaled N.

2012-01-01

This letter demonstrates RF microelectromechanical systems (MEMS) fractal capacitors possessing the highest reported self-resonant frequencies (SRFs) in PolyMUMPS to date. Explicitly, measurement results show SRFs beyond 20 GHz. Furthermore, quality

Absorbed dose kernel and self-shielding calculations for a novel radiopaque glass microsphere for transarterial radioembolization.

Science.gov (United States)

Church, Cody; Mawko, George; Archambault, John Paul; Lewandowski, Robert; Liu, David; Kehoe, Sharon; Boyd, Daniel; Abraham, Robert; Syme, Alasdair

2018-02-01

Radiopaque microspheres may provide intraprocedural and postprocedural feedback during transarterial radioembolization (TARE). Furthermore, the potential to use higher resolution x-ray imaging techniques as opposed to nuclear medicine imaging suggests that significant improvements in the accuracy and precision of radiation dosimetry calculations could be realized for this type of therapy. This study investigates the absorbed dose kernel for novel radiopaque microspheres including contributions of both short and long-lived contaminant radionuclides while concurrently quantifying the self-shielding of the glass network. Monte Carlo simulations using EGSnrc were performed to determine the dose kernels for all monoenergetic electron emissions and all beta spectra for radionuclides reported in a neutron activation study of the microspheres. Simulations were benchmarked against an accepted 90 Y dose point kernel. Self-shielding was quantified for the microspheres by simulating an isotropically emitting, uniformly distributed source, in glass and in water. The ratio of the absorbed doses was scored as a function of distance from a microsphere. The absorbed dose kernel for the microspheres was calculated for (a) two bead formulations following (b) two different durations of neutron activation, at (c) various time points following activation. Self-shielding varies with time postremoval from the reactor. At early time points, it is less pronounced due to the higher energies of the emissions. It is on the order of 0.4-2.8% at a radial distance of 5.43 mm with increased size from 10 to 50 μm in diameter during the time that the microspheres would be administered to a patient. At long time points, self-shielding is more pronounced and can reach values in excess of 20% near the end of the range of the emissions. Absorbed dose kernels for 90 Y, 90m Y, 85m Sr, 85 Sr, 87m Sr, 89 Sr, 70 Ga, 72 Ga, and 31 Si are presented and used to determine an overall kernel for the

Resonance parameters of the 6.67-, 20.9-, and 36.8-eV levels in 238U

International Nuclear Information System (INIS)

Olsen, D.K.; de Saussure, G.; Perez, R.B.; Difilippo, F.C.

1976-01-01

The ENDF/B-IV 238 U cross sections (MAT-1262) yield an effective capture resonance integral in strongly self-shielded situations which is too high. This situation suggests that the ENDF/B capture widths for the first few s-wave levels may be too large. Recent ORELA measurements of transmission through 238 U have been analyzed with a multilevel formula to determine the parameters of the 6.67-, 20.9-, and 36.6-eV levels. These three levels provide 86 percent of the infinitely dilute capture resonance integral

Shielded transient self-interaction of a bunch entering a circle from a straight path

International Nuclear Information System (INIS)

Li, R.; Bohn, C.L.; Bisognano, J.J.

1997-01-01

When a short (mm-length) bunch with high (nC-regime) charge is transported through a magnetic bending system, self-interaction via coherent synchrotron radiation (CSR) and space charge may alter the bunch dynamics significantly. The authors consider a Gaussian rigid-line-charge bunch following a straight-path trajectory into a circle, with the trajectory centered between two infinite, parallel, perfectly conducting plates. Transients associated with CSR and space charge generated from source particles both on the straight path and the circle are calculated, and their net effect on the radiated power is contrasted with that of shielded steady-state CSR

Field-angle dependence of magnetic resonance in Pt/NiFe films

International Nuclear Information System (INIS)

Inoue, H.Y.; Harii, K.; Saitoh, E.

2007-01-01

Ferromagnetic resonance in NiFe/ amorphous Pt bilayer thin films was investigated with changing the external field direction. The spectral width of the ferromagnetic resonance depends critically on the external-magnetic-field direction. We found that the sample dependence of the spectral width is enhanced with deviation of external field direction from the direction along the film plain, implying an important role of spin directions in field-induced spin-decoherence mechanism in Pt

Time-dependent transport in interacting and noninteracting resonant-tunneling systems

DEFF Research Database (Denmark)

Jauho, Antti-Pekka; Wingreen, Ned S.; Meir, Yigal

1994-01-01

noninteracting resonant-tunneling system are presented. Due to the coherence between the leads and the resonant site, the current does not follow the driving signal adiabatically: a ''ringing'' current is found as a response to a voltage pulse, and a complex time dependence results in the case of harmonic......We consider a mesoscopic region coupled to two leads under the influence of external time-dependent voltages. The time dependence is coupled to source and drain contacts, the gates controlling the tunnel-barrier heights, or to the gates that define the mesoscopic region. We derive, with the Keldysh...... nonequilibrium-Green-function technique, a formal expression for the fully nonlinear, time-dependent current through the system. The analysis admits arbitrary interactions in the mesoscopic region, but the leads are treated as noninteracting. For proportionate coupling to the leads, the time-averaged current...

Josephson junctions array resonators

Energy Technology Data Exchange (ETDEWEB)

Gargiulo, Oscar; Muppalla, Phani; Mirzaei, Iman; Kirchmair, Gerhard [Institute for Quantum Optics and Quantum Information, Innsbruck (Austria)

2016-07-01

We present an experimental analysis of the self- and cross-Kerr effect of extended plasma resonances in Josephson junction chains. The chain consists of 1600 individual junctions and we can measure quality factors in excess of 10000. The Kerr effect manifests itself as a frequency shift that depends linearly on the number of photons in a resonant mode. By changing the input power we are able to measure this frequency shift on a single mode (self-kerr). By changing the input power on another mode while measuring the same one, we are able to evaluate the cross-kerr effect. We can measure the cross-Kerr effect by probing the resonance frequency of one mode while exciting another mode of the array with a microwave drive.

Design and characterization of a novel toroidal split-ring resonator

International Nuclear Information System (INIS)

Bobowski, J. S.; Nakahara, Hiroko

2016-01-01

The design and characterization of a novel toroidal split-ring resonator (SRR) are described in detail. In conventional cylindrical SRRs, there is a large magnetic flux within the bore of the resonator. However, there also exists a non-negligible magnetic flux in the free space surrounding the resonator. The energy losses associated with this radiated power diminish the resonator’s quality factor. In the toroidal SRR, on the other hand, the magnetic field lines are strongly confined within the bore of the resonator resulting in high intrinsic quality factors and stable resonance frequencies without requiring additional electromagnetic shielding. This paper describes the design and construction of a toroidal SRR as well as an experimental investigation of its cw response in the frequency-domain and its time-domain response to a rf pulse. Additionally, the dependence of the toroidal SRR’s resonant frequency and quality factor on the strength of inductive coupling to external circuits is investigated both theoretically and experimentally

Nonlinear self-precession and wavenumber shift of electromagnetic waves under resonance and of Alfven waves in plasmas

International Nuclear Information System (INIS)

Bhattacharyya, B.; Chakraborty, B.

1979-01-01

Nonlinear corrections of a left and a right circularly polarized electromagnetic wave of the same frequency, propagating in the direction of a static and uniform magnetic field in a cold and collisionally damped two-component plasma, have been evaluated. The nonlinearly correct dispersion relation, self-generating nonlinear precessional rotation of the polarization ellipse of the wave and the shift in a wave parameter depend on linear combinations of products of the amplitude components taken two at a time and hence on the energies of the waves. Both in the low frequency resonance (that is when the ion cyclotron frequency equals the wave frequency) and in the high frequency resonance (that is when the electron cyclotron frequency equals the wave frequency), the self-precessional rate and wavenumber shift are found to be large and so have the possibility of detection in laboratory experiments. Moreover, for the limit leading to Alfven waves, these nonlinear effects have been found to have some interesting and significant properties. (Auth.)

Q2 dependence of the spin structure function in the resonance region

International Nuclear Information System (INIS)

Li, Z.; Li, Z.

1994-01-01

In this paper, we show what we can learn from the CEBAF experiments on spin-structure functions, and the transition from the Drell-Hearn-Gerasimov sum rule in the real photon limit to the spin-dependent sum rules in deep inelastic scattering, and how the asymmetry A 1 (x,Q 2 ) approaches the scaling limit in the resonance region. The spin structure function in the resonance region alone cannot determine the spin-dependent sum rule due to the kinematic restriction of the resonance region. The integral ∫ 0 1 {A 1 (x,Q 2 )F 2 (x,Q 2 )/2x[1+R(x,Q 2 )]}dx is estimated from Q 2 =0--2.5 GeV 2 . The result shows that there is a region where both contributions from the baryon resonances and the deep inelastic scattering are important; thus it provides important information on the high twist effects on the spin-dependent sum rule

Secondary gamma-ray data for shielding calculation

International Nuclear Information System (INIS)

Miyasaka, Sunichi

1979-01-01

In deep penetration transport calculations, the integral design parameters is determined mainly by secondary particles which are produced by interactions of the primary radiation with materials. The shield thickness and the biological dose rate at a given point of a bulk shield are determined from the contribution from secondary gamma rays. The heat generation and the radiation damage in the structural and shield materials depend strongly on the secondary gamma rays. In this paper, the status of the secondary gamma ray data and its further problems are described from the viewpoint of shield design. The secondary gamma-ray data in ENDF/B-IV and POPOP4 are also discussed based on the test calculations made for several shield assemblies. (author)

Measurement of thermal neutron cross-section and resonance integral for the 165Ho(n,γ) 166gHo reaction using electron linac-based neutron source

Science.gov (United States)

Nguyen, Van Do; Pham, Duc Khue; Kim, Tien Thanh; Kim, Guinyun; Lee, Manwoo; Kim, Kyung Sook; Kang, Heung-Sik; Cho, Moo-Hyun; Ko, In Soo; Namkung, Won

2011-01-01

The thermal neutron cross-section and the resonance integral of the 165Ho(n,γ) 166gHo reaction have been measured by the activation method using a 197Au(n,γ) 198Au monitor reaction as a single comparator. The high-purity natural Ho and Au foils with and without a cadmium shield case of 0.5 mm thickness were irradiated in a neutron field of the Pohang neutron facility. The induced activities in the activated foils were measured with a calibrated p-type high-purity Ge detector. The correction factors for the γ-ray attenuation ( Fg), the thermal neutron self-shielding ( Gth), the resonance neutron self-shielding ( Gepi) effects, and the epithermal neutron spectrum shape factor ( α) were taken into account. The thermal neutron cross-section for the 165Ho(n,γ) 166gHo reaction has been determined to be 59.7 ± 2.5 barn, relative to the reference value of 98.65 ± 0.09 barn for the 197Au(n,γ) 198Au reaction. By assuming the cadmium cut-off energy of 0.55 eV, the resonance integral for the 165Ho(n,γ) 166gHo reaction is 671 ± 47 barn, which is determined relative to the reference value of 1550 ± 28 barn for the 197Au(n,γ) 198Au reaction. The present results are, in general, good agreement with most of the previously reported data within uncertainty limits.

Magnetic Field Dependence and Q of the Josephson Plasma Resonance

DEFF Research Database (Denmark)

Pedersen, Niels Falsig; Finnegan, T. F.; Langenberg, D. N.

1972-01-01

of supercurrent density which is not observed in conventional measurements of the field-dependent critical current. The frequency and field dependence of the plasma-resonance linewidth are interpreted as evidence that the previously unobserved quasiparticle-pair-interference tunnel current predicted by Josephson...

Self-induced parametric amplification arising from nonlinear elastic coupling in a micromechanical resonating disk gyroscope.

Science.gov (United States)

Nitzan, Sarah H; Zega, Valentina; Li, Mo; Ahn, Chae H; Corigliano, Alberto; Kenny, Thomas W; Horsley, David A

2015-03-12

Parametric amplification, resulting from intentionally varying a parameter in a resonator at twice its resonant frequency, has been successfully employed to increase the sensitivity of many micro- and nano-scale sensors. Here, we introduce the concept of self-induced parametric amplification, which arises naturally from nonlinear elastic coupling between the degenerate vibration modes in a micromechanical disk-resonator, and is not externally applied. The device functions as a gyroscope wherein angular rotation is detected from Coriolis coupling of elastic vibration energy from a driven vibration mode into a second degenerate sensing mode. While nonlinear elasticity in silicon resonators is extremely weak, in this high quality-factor device, ppm-level nonlinear elastic effects result in an order-of-magnitude increase in the observed sensitivity to Coriolis force relative to linear theory. Perfect degeneracy of the primary and secondary vibration modes is achieved through electrostatic frequency tuning, which also enables the phase and frequency of the parametric coupling to be varied, and we show that the resulting phase and frequency dependence of the amplification follow the theory of parametric resonance. We expect that this phenomenon will be useful for both fundamental studies of dynamic systems with low dissipation and for increasing signal-to-noise ratio in practical applications such as gyroscopes.

Double giant resonances in time-dependent relativistic mean-field theory

International Nuclear Information System (INIS)

Ring, P.; Podobnik, B.

1996-01-01

Collective vibrations in spherical nuclei are described in the framework of time-dependent relativistic mean-field theory (RMFT). Isoscalar quadrupole and isovector dipole oscillations that correspond to giant resonances are studied, and possible excitations of higher modes are investigated. We find evidence for modes which can be interpreted as double resonances. In a quantized RMFT they correspond to two-phonon states. (orig.)

Time-dependent resonant tunnelling for parallel-coupled double quantum dots

International Nuclear Information System (INIS)

Dong Bing; Djuric, Ivana; Cui, H L; Lei, X L

2004-01-01

We derive the quantum rate equations for an Aharonov-Bohm interferometer with two vertically coupled quantum dots embedded in each of two arms by means of the nonequilibrium Green function in the sequential tunnelling regime. Based on these equations, we investigate time-dependent resonant tunnelling under a small amplitude irradiation and find that the resonant photon-assisted tunnelling peaks in photocurrent demonstrate a combination behaviour of Fano and Lorentzian resonances due to the interference effect between the two pathways in this parallel configuration, which is controllable by threading the magnetic flux inside this device

The SWAN-SCALE code for the optimization of critical systems

International Nuclear Information System (INIS)

Greenspan, E.; Karni, Y.; Regev, D.; Petrie, L.M.

1999-01-01

The SWAN optimization code was recently developed to identify the maximum value of k eff for a given mass of fissile material when in combination with other specified materials. The optimization process is iterative; in each iteration SWAN varies the zone-dependent concentration of the system constituents. This change is guided by the equal volume replacement effectiveness functions (EVREF) that SWAN generates using first-order perturbation theory. Previously, SWAN did not have provisions to account for the effect of the composition changes on neutron cross-section resonance self-shielding; it used the cross sections corresponding to the initial system composition. In support of the US Department of Energy Nuclear Criticality Safety Program, the authors recently removed the limitation on resonance self-shielding by coupling SWAN with the SCALE code package. The purpose of this paper is to briefly describe the resulting SWAN-SCALE code and to illustrate the effect that neutron cross-section self-shielding could have on the maximum k eff and on the corresponding system composition

Sensitivity coefficients for the 238U neutron-capture shielded-group cross sections

International Nuclear Information System (INIS)

Munoz-Cobos, J.L.; de Saussure, G.; Perez, R.B.

1981-01-01

In the unresolved resonance region cross sections are represented with statistical resonance parameters. The average values of these parameters are chosen in order to fit evaluated infinitely dilute group cross sections. The sensitivity of the shielded group cross sections to the choice of mean resonance data has recently been investigated for the case of 235 U and 239 Pu by Ganesan and by Antsipov et al; similar sensitivity studies for 238 U are reported

Calculation of self-shielding coefficients, flux depression and cadmium factor for thermal neutron flux measurement of the IPEN/MB-01 reactor

International Nuclear Information System (INIS)

Marques, Andre Luis Ferreira; Ting, Daniel Kao Sun; Mendonca, Arlindo Gilson

1996-01-01

A calculation methodology of Flux Depression, Self-Shielding and Cadmium Factors is presented, using the ANISN code, for experiments conducted at the IPEN/MB-01 Research Reactor. The correction factors were determined considering thermal neutron flux and 0.125 e 0.250 mm diameter of 197 Au wires. (author)

Shielded transient self-interaction of a bunch entering a circle from a straight path

International Nuclear Information System (INIS)

Li, R.; Bohn, C.L.; Bisognano, J.J.

1997-01-01

Recent developments in electron-gun and injector technologies enable production of short (mm-length), high-charge (nC-regime) bunches. In this parameter regime, the curvature effect on the bunch self-interaction, by way of coherent synchrotron radiation (CSR) and space-charge forces as the beam traverses magnet bends, may cause serious emittance degradation. In this paper, the authors study an electron bunch orbiting between two infinite, parallel conducting plates. The bunch moves on a trajectory from a straight path to a circular orbit and begins radiating. Transient effects, arising from CSR and space-charge forces generated from source particles both on the bend and on the straight path prior to the bend, are analyzed using Lienard-Wiechert fields, and their overall net effect is obtained. The influence of the plates on the transients is contrasted to their shielding of the steady-state radiated power. Results for emittance degradation induced by this self-interaction are also presented

Double-layer neutron shield design as neutron shielding application

Science.gov (United States)

Sariyer, Demet; Küçer, Rahmi

2018-02-01

The shield design in particle accelerators and other high energy facilities are mainly connected to the high-energy neutrons. The deep penetration of neutrons through massive shield has become a very serious problem. For shielding to be efficient, most of these neutrons should be confined to the shielding volume. If the interior space will become limited, the sufficient thickness of multilayer shield must be used. Concrete and iron are widely used as a multilayer shield material. Two layers shield material was selected to guarantee radiation safety outside of the shield against neutrons generated in the interaction of the different proton energies. One of them was one meter of concrete, the other was iron-contained material (FeB, Fe2B and stainless-steel) to be determined shield thicknesses. FLUKA Monte Carlo code was used for shield design geometry and required neutron dose distributions. The resulting two layered shields are shown better performance than single used concrete, thus the shield design could leave more space in the interior shielded areas.

Automatic welding technologies for long-distance pipelines by use of all-position self-shielded flux cored wires

Directory of Open Access Journals (Sweden)

Zeng Huilin

2014-10-01

Full Text Available In order to realize the automatic welding of pipes in a complex operation environment, an automatic welding system has been developed by use of all-position self-shielded flux cored wires due to their advantages, such as all-position weldability, good detachability, arc's stability, low incomplete fusion, no need for welding protective gas or protection against wind when the wind speed is < 8 m/s. This system consists of a welding carrier, a guide rail, an auto-control system, a welding source, a wire feeder, and so on. Welding experiments with this system were performed on the X-80 pipeline steel to determine proper welding parameters. The welding technique comprises root welding, filling welding and cover welding and their welding parameters were obtained from experimental analysis. On this basis, the mechanical properties tests were carried out on welded joints in this case. Results show that this system can help improve the continuity and stability of the whole welding process and the welded joints' inherent quality, appearance shape, and mechanical performance can all meet the welding criteria for X-80 pipeline steel; with no need for windbreak fences, the overall welding cost will be sharply reduced. Meanwhile, more positive proposals were presented herein for the further research and development of this self-shielded flux core wires.

Influence of preheating on API 5L-X80 pipeline joint welding with self shielded flux-cored wire

International Nuclear Information System (INIS)

Cooper, R.; Silva, J. H. F.; Trevisan, R. E.

2004-01-01

The present work refers to the characterization of API 5L-X80 pipeline joints welded with self-shielded flux cored wire. This process was evaluated under preheating conditions, with an uniform and steady heat input. All joints were welded in flat position (1G), with the pipe turning and the torch still. Tube dimensions were 762 mm in external diameter and 16 mm in thickness. Welds were applied on single V-groove, with six weld beads, along with three levels of preheating temperatures (room temperature, 100 degree centigree, 160 degree centigree). These temperatures were maintained as inter pass temperature. The filler metal E71T8-K6 with mechanical properties different from parent metal was used in under matched conditions. The weld characterization is presented according to the mechanical test results of tensile strength, hardness and impact test. The mechanical tests were conducted according to API 1104, AWS and ASTM standards. API 1104 and API 51 were used as screening criteria. According to the results obtained, it was possible to remark that it is appropriate to weld API 5L-X80 steel ducts with Self-shielded Flux Cored wires, in conformance to the API standards and no preheat temperature is necessary. (Author) 22 refs

Parameter dependence of resonant spin torque magnetization reversal

International Nuclear Information System (INIS)

Fricke, L.; Serrano-Guisan, S.; Schumacher, H.W.

2012-01-01

We numerically study ultra fast resonant spin torque (ST) magnetization reversal in magnetic tunneling junctions (MTJ) driven by current pulses having a direct current (DC) and a resonant alternating current (AC) component. The precessional ST dynamics of the single domain MTJ free layer cell are modeled in the macro spin approximation. The energy efficiency, reversal time, and reversal reliability are investigated under variation of pulse parameters like direct and AC current amplitude, AC frequency and AC phase. We find a range of AC and direct current amplitudes where robust resonant ST reversal is obtained with faster switching time and reduced energy consumption per pulse compared to purely direct current ST reversal. However, for a certain range of AC and direct current amplitudes a strong dependence of the reversal properties on AC frequency and phase is found. Such regions of unreliable reversal must be avoided for ST memory applications.

Parameter dependence of resonant spin torque magnetization reversal

Science.gov (United States)

Fricke, L.; Serrano-Guisan, S.; Schumacher, H. W.

2012-04-01

We numerically study ultra fast resonant spin torque (ST) magnetization reversal in magnetic tunneling junctions (MTJ) driven by current pulses having a direct current (DC) and a resonant alternating current (AC) component. The precessional ST dynamics of the single domain MTJ free layer cell are modeled in the macro spin approximation. The energy efficiency, reversal time, and reversal reliability are investigated under variation of pulse parameters like direct and AC current amplitude, AC frequency and AC phase. We find a range of AC and direct current amplitudes where robust resonant ST reversal is obtained with faster switching time and reduced energy consumption per pulse compared to purely direct current ST reversal. However, for a certain range of AC and direct current amplitudes a strong dependence of the reversal properties on AC frequency and phase is found. Such regions of unreliable reversal must be avoided for ST memory applications.

MC²-3: Multigroup Cross Section Generation Code for Fast Reactor Analysis

Energy Technology Data Exchange (ETDEWEB)

Lee, C. H. [Argonne National Lab. (ANL), Argonne, IL (United States); Yang, W. S. [Argonne National Lab. (ANL), Argonne, IL (United States)

2013-11-08

The MC²-3 code is a Multigroup Cross section generation Code for fast reactor analysis, developed by improving the resonance self-shielding and spectrum calculation methods of MC²-2 and integrating the one-dimensional cell calculation capabilities of SDX. The code solves the consistent P1 multigroup transport equation using basic neutron data from ENDF/B data files to determine the fundamental mode spectra for use in generating multigroup neutron cross sections. A homogeneous medium or a heterogeneous slab or cylindrical unit cell problem is solved in ultrafine (~2000) or hyperfine (~400,000) group levels. In the resolved resonance range, pointwise cross sections are reconstructed with Doppler broadening at specified isotopic temperatures. The pointwise cross sections are directly used in the hyperfine group calculation whereas for the ultrafine group calculation, self-shielded cross sections are prepared by numerical integration of the pointwise cross sections based upon the narrow resonance approximation. For both the hyperfine and ultrafine group calculations, unresolved resonances are self-shielded using the analytic resonance integral method. The ultrafine group calculation can also be performed for two-dimensional whole-core problems to generate region-dependent broad-group cross sections. Multigroup cross sections are written in the ISOTXS format for a user-specified group structure. The code is executable on UNIX, Linux, and PC Windows systems, and its library includes all isotopes of the ENDF/BVII. 0 data.

Analysis and reduction of thermal magnetic noise in liquid-He dewar for sensitive low-field nuclear magnetic resonance measurements

International Nuclear Information System (INIS)

Hwang, S. M.; Yu, K. K.; Lee, Y. H.; Kang, C. S.; Kim, K.; Lee, S. J.

2013-01-01

For sensitive measurements of micro-Tesla nuclear magnetic resonance (μT-NMR) signal, a low-noise superconducting quantum interference device (SQUID) system is needed. We have fabricated a liquid He dewar for an SQUID having a large diameter for the pickup coil. The initial test of the SQUID system showed much higher low-frequency magnetic noise caused by the thermal magnetic noise of the aluminum plates used for the vapor-cooled thermal shield material. The frequency dependence of the noise spectrum showed that the noise increases with the decrease of frequency. This behavior could be explained from a two-layer model; one generating the thermal noise and the other one shielding the thermal noise by eddy-current shielding. And the eddy-current shielding effect is strongly dependent on the frequency through the skin-depth. To minimize the loop size for the fluctuating thermal noise current, we changed the thermal shield material into insulated thin Cu mesh. The magnetic noise of the SQUID system became flat down to 0.1 Hz with a white noise of 0.3 fT√ Hz, including the other noise contributions such as SQUID electronics and magnetically shielded room, etc, which is acceptable for low-noise μT-NMR experiments.

Resonant Self-Trapping and Absorption of Intense Bessel Beams

International Nuclear Information System (INIS)

Fan, J.; Parra, E.; Milchberg, H. M.

2000-01-01

We report the observation of resonant self-trapping and enhanced laser-plasma heating resulting from propagation of high intensity Bessel beams in neutral gas. The enhancement in absorption and plasma heating is directly correlated to the spatial trapping of laser radiation. (c) 2000 The American Physical Society

Evaluation of the room shielding thickness of Hi-Art tomotherapy system

International Nuclear Information System (INIS)

Liu Haikuan; Wu Jinhai; Gu Naigu; Gao Yiming; Wang Li; Huang Weiqin; Wang Fengxian

2010-01-01

In this paper, we calculate and evaluate the room shielding thickness of a Hi-Art tomotherapy system, which is a new type of radiotherapy facility. Due to the self-shielding of the accelerator,only scattered beam and beam leakage were considered in calculating the room shielding thickness. The radiation field of the tomotherapy system was used as the basic data to calculate the shielding thickness of every 15 degree solid angle. The maximum shielding thickness required of each shielding wall was at the position with the angle of 15 degree, and the calculated shielding thickness were 1023, 975, 917, 1460, 1147 and 1189 mm for the east wall,south wall,west wall, north wall, the roof and the floor,respectively. According to the calculation results, all shielding walls, ceiling and floor could meet the requirement of the radiation protection, but the north wall thickness of 1200 mm was a little thinner. (authors)

Optimization of the National Ignition Facility primary shield design

International Nuclear Information System (INIS)

Annese, C.E.; Watkins, E.F.; Greenspan, E.; Miller, W.F.

1993-10-01

Minimum cost design concepts of the primary shield for the National Ignition laser fusion experimental Facility (NIF) are searched with the help of the optimization code SWAN. The computational method developed for this search involves incorporating the time dependence of the delayed photon field within effective delayed photon production cross sections. This method enables one to address the time-dependent problem using relatively simple, time-independent transport calculations, thus significantly simplifying the design process. A novel approach was used for the identification of the optimal combination of constituents that will minimize the shield cost; it involves the generation, with SWAN, of effectiveness functions for replacing materials on an equal cost basis. The minimum cost shield design concept was found to consist of a mixture of polyethylene and low cost, low activation materials such as SiC, with boron added near the shield boundaries

An attempt to explain the uranium 238 resonance integral discrepancy

International Nuclear Information System (INIS)

Tellier, H.; Grandotto, M.

1978-01-01

Studies on uranium 238 resonance integral discrepancy were carried out for light water reactor physics. It was shown that using recently published resonance parameters and substituting a multilevel formalism to the usual Breit and Wigner formula reduced the well known discrepancy between two values of the uranium 238 effective resonance integral: the value calculated with the nuclear data and the one deduced from critical experiments. Since the cross section computed with these assumptions agrees quite well with the Oak-Ridge transmission data, it was used to obtain the self-shielding effect and the capture rate in light water lattices. The multiplication factor calculated with this method is found very close to the experimental value. Preliminary results for a set of benchmarks relative to several types of thermal neutron reactors lead to very low discrepancies. The reactivity loss is only 130 x 10 -5 instead of 650 x 10 -5 in the case of the usual libraries and the single level formula

Radio frequency self-resonant coil for contactless AC-conductivity in 100 T class ultra-strong pulse magnetic fields

Science.gov (United States)

Nakamura, D.; Altarawneh, M. M.; Takeyama, S.

2018-03-01

A contactless measurement system of electrical conductivity was developed for application under pulsed high magnetic fields over 100 T by using a self-resonant-type, high-frequency circuit. Electromagnetic fields in the circuit were numerically analysed by the finite element method, to show how the resonant power spectra of the circuit depends on the electrical conductivity of a sample set on the probe-coil. The performance was examined using a high-temperature cuprate superconductor, La2-x Sr x CuO4, in magnetic fields up to 102 T with a high frequency of close to 800 MHz. As a result, the upper critical field could be determined with a good signal-to-noise ratio.

Shielding practice

International Nuclear Information System (INIS)

Sauermann, P.F.

1985-08-01

The basis of shielding practice against external irradiation is shown in a simple way. For most sources of radiation (point sources) occurring in shielding practice, the basic data are given, mainly in the form of tables, which are required to solve the shielding problems. The application of these data is explained and discussed using practical examples. Thickness of shielding panes of glove boxes for α and β radiation; shielding of sealed γ-radiography sources; shielding of a Co-60 radiation source, and of the manipulator panels for hot cells; damping factors for γ radiation and neutrons; shielding of fast and thermal neutrons, and of bremsstrahlung (X-ray tubes, Kr-85 pressure gas cylinders, 42 MeV betatrons, 20 MeV linacs); two-fold shielding (lead glass windows for hot cells, 14 MeV neutron generators); shielding against scattered radiation. (orig./HP) [de

Contribution to the study of the unresolved resonance range of the neutrons cross sections

International Nuclear Information System (INIS)

Noguere, Gilles

2014-01-01

This document presents the statistical description of neutron cross sections in the unresolved resonance range. The modeling of the total cross section and of the 'shape - elastic' cross section is based on the 'average R-Matrix' formalism. The partial cross sections describing the radiative capture, elastic scattering, inelastic scattering and fission process are calculated using the Hauser-Feshbach formalism with width fluctuation corrections. In the unresolved resonance range, these models depend on the average resonance parameters (neutron strength function Sc, mean level spacing D c , average partial reaction widths Γ c , channel radius a c , effective radius R' and distant level parameter R-bar c ∞ ). The codes (NJOY, CALENDF...) dedicated to the processing of nuclear data libraries (JEFF, ENDF/B, JENDL, CENDL, BROND... ) use the average parameters to take into account the self-shielding phenomenon for the simulation of the neutron transport in Monte-Carlo (MCNP, TRIPOLI... ) and deterministic (APOLLO, ERANOS...) codes. The evaluation work consists in establishing a consistent set of average parameters as a function of the total angular momentum J of the system and of the orbital moment of the incident neutron l. The work presented in this paper aims to describe the links between the S-Matrix and the 'average R-Matrix' formalism for the calculation of Sc, R-bar c ∞ , ac and R'. (author) [fr

Shielding calculation for bremsstrahlung from β-emitters

International Nuclear Information System (INIS)

Ichimiya, Tsutomu

1990-01-01

Accompanying the revision of radiation injury prevention law, the shielding calculation method for photon corresponding to the dose equivalent was shown. However, regarding the electron from β decay nuclide and bremsstrahlung caused by shielding material, the shielding calculation method corresponding to the 1 cm dose equivalent has not been reported, hence, in this report, the spectrum of β-ray is calculated and the 1 cm dose equivalent transmission rate of the bremsstrahlung was calculated for three kinds of shielding materials (iron, lead, concrete). As the result of consideration, it is sufficient to think about the bremsstrahlung due to negative electron emission accompanying β-decay. In β-decay, electrons which constitute the continuous spectrum with maximum energy are emitted. The shape of the spectrum differs with nuclides. The maximum energy of β-ray of generally used nuclides is mostly below 3MeV and, besides, the electron ray itself is easily shielded, while the strength of bremsstrahlung depends on the atomic number of shielding materials and its generating mechanism is complicated. In this report, the actual shielding calculation method for bremsstrahlung is shown with regard to the most frequently used β-decay nuclides. (M.T.)

Anisotropic Pressure, Transport, and Shielding of Magnetic Perturbations

International Nuclear Information System (INIS)

Mynick, H.E.; Boozer, A.H.

2008-01-01

We compute the effect on a tokamak of applying a nonaxisymmetric magnetic perturbation (delta)B. An equilibrium with scalar pressure p yields zero net radial current, and therefore zero torque. Thus, the usual approach, which assumes scalar pressure, is not self-consistent, and masks the close connection which exists between that radial current and the in-surface currents, which provide shielding or amplification of (delta)B. Here, we analytically compute the pressure anisotropy, anisotropy, p # parallel#, p # perpendicular# and ≠ p, and from this, both the radial and in-surface currents. The surface-average of the radial current recovers earlier expressions for ripple transport, while the in-surface currents provide an expression for the amount of self-consistent shielding the plasma provides.

Development of neutron shielding material for cask

International Nuclear Information System (INIS)

Najima, K.; Ohta, H.; Ishihara, N.; Matsuoka, T.; Kuri, S.; Ohsono, K.; Hode, S.

2001-01-01

Since 1980's Mitsubishi Heavy Industries, Ltd (MHI) has established transport and storage cask design 'MSF series' which makes higher payload and reliability for long term storage. MSF series transport and storage cask uses new-developed neutron shielding material. This neutron shielding material has been developed for improving durability under high condition for long term. Since epoxy resin contains a lot of hydrogen and is comparatively resistant to heat, many casks employ epoxy base neutron shielding material. However, if the epoxy base neutron shielding material is used under high temperature condition for a long time, the material deteriorates and the moisture contained in it is released. The loss of moisture is in the range of several percents under more than 150 C. For this reason, our purpose was to develop a high durability epoxy base neutron shielding material which has the same self-fire-extinction property, high hydrogen content and so on as conventional. According to the long-time heating test, the weight loss of this new neutron shielding material after 5000 hours heating has been lower than 0.04% at 150 C and 0.35% at 170 C. A thermal test was also performed: a specimen of neutron shielding material covered with stainless steel was inserted in a furnace under condition of 800 C temperature for 30 minutes then was left to cool down in ambient conditions. The external view of the test piece shows that only a thin layer was carbonized

Benchmarking of EPRI-cell epithermal methods with the point-energy discrete-ordinates code (OZMA)

International Nuclear Information System (INIS)

Williams, M.L.; Wright, R.Q.; Barhen, J.; Rothenstein, W.

1982-01-01

The purpose of the present study is to benchmark E-C resonance-shielding and cell-averaging methods against a rigorous deterministic solution on a fine-group level (approx. 30 groups between 1 eV and 5.5 keV). The benchmark code used is OZMA, which solves the space-dependent slowing-down equations using continuous-energy discrete ordinates or integral transport theory to produce fine-group cross sections. Results are given for three water-moderated lattices - a mixed oxide, a uranium method, and a tight-pitch high-conversion uranium oxide configuration. The latter two lattices were chosen because of the strong self shielding of the 238 U resonances

Morphology-dependent resonances of a microsphere-optical fiber system

Science.gov (United States)

Griffel, Giora; Arnold, Stephen; Taskent, Dogan; Serpengüzel, Ali; Connolly, John; Morris, Nancy

1996-05-01

Morphology-dependent resonances of microspheres sitting upon an index-matched single-mode fiber half-coupler are excited by a tunable 753-nm distributed-feedback laser. Resonance peaks in the scattering spectra and associated dips in the transmission spectra for the TE and TM modes are observed. We present a new model that describes this interaction in terms of the fiber-sphere coupling coefficient and the microsphere's intrinsic quality factor Q0 . This model enables us to obtain expressions for the finesse and the Q factor of the composite particle-fiber system, the resonance width, and the depth of the dips measured in the transmission spectra. Our model shows that index matching improves the coupling efficiency by more than a factor of 2 compared with that of a non-index-matched system.

Radiation shielding device

International Nuclear Information System (INIS)

Nakagawa, Takahiro; Yamagami, Makoto.

1996-01-01

A fixed shielding member made of a radiation shielding material is constituted in perpendicular to an opening formed on radiation shielding walls. The fixed shielding member has one side opened and has other side, the upper portion and the lower portion disposed in close contact with the radiation shielding walls. Movable shielding members made of a radiation shielding material are each disposed openably on both side of the fixed shielding member. The movable shielding member has a shaft as a fulcrum on one side thereof for connecting it to the radiation shielding walls. The other side has a handle attached for opening/closing the movable shielding member. Upon access of an operator, when each one of the movable shielding members is opened/closed on every time, leakage of linear or scattered radiation can be prevented. Even when both of the movable shielding members are opened simultaneously, the fixed shielding member and the movable shielding members form labyrinth to prevent leakage of linear radioactivity. (I.N.)

An experimental investigation on the pressure characteristics of high speed self-resonating pulsed waterjets influenced by feeding pipe diameter

Energy Technology Data Exchange (ETDEWEB)

Li, Dong; Kang, Dong; Ding, Xiao Long; Wang, Xiao Huan; Fang, Zhen Long [School of Power and Mechanical Engineering, Wuhan University, Hubei Province (China)

2016-11-15

The destructive power of a continuous waterjet issuing from a nozzle can be greatly enhanced by generating self-resonance in the nozzle assembly to produce a Self-resonating pulsed waterjet (SRPW). To further improve the performance of SRPW, effects of feeding pipe diameter on the pressure characteristics were experimentally investigated by measuring and analyzing the axial pressure oscillation peaks and amplitudes. Four organ-pipe nozzles of different chamber lengths and three feeding pipes of different diameters were employed. Results show that feeding pipe diameter cannot change the feature of SRPW of having an optimum standoff distance, but it slightly changes the oscillating frequency of the jet. It is also found that feeding pipe diameter significantly affects the magnitudes of pressure oscillation peak and amplitude, largely depending on the pump pressure and standoff distance. The enhancement or attenuation of the pressure oscillation peak and amplitude can be differently affected by the same feeding pipe diameter.

Using natural local materials for developing special radiation shielding concretes, and deduction of its shielding characteristics

International Nuclear Information System (INIS)

Kharita, M. H.; Takeyeddin, M.; Al-Nassar, M.; Yousef, S.

2006-06-01

Concrete is considered as the most important material to be used for radiation shielding in facilities contain radioactive sources and radiation generating machines. The concrete shielding properties may vary depending on the construction of the concrete, which is highly relative to the composing aggregates i.e. aggregates consist about 70 - 80% of the total weight of normal concrete. In this project tow types of concrete used in Syria (in Damascus and Aleppo) had been studied and their shielding properties were defined for gamma ray from Cs-137 and Co-60 sources, and for neutrons from Am-Be source. About 10% reduction in HVL was found in the comparison between the tow concrete types for both neutrons and gammas. Some other types of concrete were studied using aggregates from different regions in Syria, to improve the shielding properties of concrete, and another 10% of reduction was achieved in comparison with Damascene concrete (20% in comparison with the concrete from Aleppo) for both neutrons and gamma rays. (author)

Concrete mix design for X-and gamma shielding

International Nuclear Information System (INIS)

Mohamad Pauzi Ismail; Noor Azreen Masenwat; Suhairy Sani; Abdul Bakhri Muhammad; Mohd Kamal Shah Shamsuddin; Rahmad Abd Rashid

2012-01-01

The design of X-ray or gamma ray radiographic exposure room requires some calculations on shielding to provide safe operation of the facility and minimum exposure to radiation workers. Careful design can lead to economical installations with minimal barriers. The design depends on such factors as: maximum energy, maximum intensity, permitted full-body dosage, workload, use factor, occupancy factor, maximum dose output and shielding materials. Choice of material for a barrier depends on convenience and cost. The radiographic exposure room is usually made of normal concrete with density of about 2.3 - 2.4 g/ cc. Normal concrete is often used for construction of exposure room because of cheap and ease of construction. This paper explained and discussed the optimum mix design for normal concrete used for X-and gamma shielding. (author)

Self-shielding and burn-out effects in the irradiation of strongly-neutron-absorbing material

International Nuclear Information System (INIS)

Sekine, T.; Baba, H.

1978-01-01

Self-shielding and burn-out effects are discussed in the evaluation of radioisotopes formed by neutron irradiation of a strongly-neutron-absorbing material. A method of the evaluation of such effects is developed both for thermal and epithermal neutrons. Gadolinium oxide uniformly mixed with graphite powder was irradiated by reactor-neutrons together with pieces of a Co-Al alloy wire (the content of Co being 0.475%) as the neutron flux monitor. The configuration of the samples and flux monitors in each of two irradiations is illustrated. The yields of activities produced in the irradiated samples were determined by the γ-spectrometry with a Ge(Li) detector of a relative detection efficiency of 8%. Activities at the end of irradiation were estimated by corrections due to pile-up, self-absorption, detection efficiency, branching ratio, and decay of the activity. Results of the calculation are discussed in comparison with the observed yields of 153 Gd, 160 Tb, and 161 Tb for the case of neutron irradiation of disc-shaped targets of gadolinium oxide. (T.G.)

Resonance phenomena in a time-dependent, three-dimensional model of an idealized eddy

Science.gov (United States)

Rypina, I. I.; Pratt, L. J.; Wang, P.; Äe; -zgökmen, T. M.; Mezic, I.

2015-08-01

We analyze the geometry of Lagrangian motion and material barriers in a time-dependent, three-dimensional, Ekman-driven, rotating cylinder flow, which serves as an idealization for an isolated oceanic eddy and other overturning cells with cylindrical geometry in the ocean and atmosphere. The flow is forced at the top through an oscillating upper lid, and the response depends on the frequency and amplitude of lid oscillations. In particular, the Lagrangian geometry changes near the resonant tori of the unforced flow, whose frequencies are rationally related to the forcing frequencies. Multi-scale analytical expansions are used to simplify the flow in the vicinity of resonant trajectories and to investigate the resonant flow geometries. The resonance condition and scaling can be motivated by simple physical argument. The theoretically predicted flow geometries near resonant trajectories have then been confirmed through numerical simulations in a phenomenological model and in a full solution of the Navier-Stokes equations.

Cost-benefit analysis of shieldings for pipes inspections at JPDR

International Nuclear Information System (INIS)

Furuta, Toshishiro; Matsuno, Kenji; Katoh, Shoohei; Anazawa, Yutaka

1979-01-01

During the test operations of JPDR-II(BWR), cracks were detected at primary pipe nozzle, and the inspections were made over about 2.5 years. In this report, the procedures such as shielding and removal of fuels which were taken to reduce radiation exposure during the inspections are summarized and the cost-benefit analysis of the shieldings were attempted to determine whether the optimum shieldings were made or not. The radiation doses was measured to be about 62 man.rem for 420 workers and the maximum individual dose was 1.3 rem. The average cost to reduce exposures at various working areas was calculated approximately 1.4 x 10 5 yen/man-rem. Especially, the provisional shielding at under core area reduced 61 man-rem and its reduction cost was 8.9 x 10 6 yen. Assuming that the economic and social detriment cost is 1,000 dollar/man-rem, it seems that the optimum shielding were taken, although the optimum conditions shifted depending on the economic and social detriment cost which cannot be simply determined. It was found that the optimum conditions depended on the order of combination of the provisional shields. (author)

Shielding plugs

International Nuclear Information System (INIS)

Makishima, Kenji.

1986-01-01

Purpose: In shielding plugs of an LMFBR type reactor, to restrain natural convection of heat in an annular space between a thermal shield layer and a shield shell, to prevent the lowering of heat-insulation performance, and to alleviate a thermal stress in a reactor container and the shield shell. Constitution: A ring-like leaf spring split in the direction of height is disposed in an annular space between a thermal shield layer and a shield shell. In consequence, the space is partitioned in the direction of height and, therefore, if axial temperature conditions and space width are the same and the space is low, the natural convection is hard to occur. Thus the rise of upper surface temperature of the shielding plugs can prevent the lowering of the heat insulation performance which will result in the increment of shielding plug cooling capacity, thereby improving reliability. In the meantime, since there is mounted an earthquake-resisting support, the thermal shield layer will move for a slight gap in case of an earthquake, being supported by the earthquake-resisting support, and the movement of the thermal shield layer is restricted, thereby maintaining integrity without increasing the stroke of the ring-like spring. (Kawakami, Y.)

SHIELDING OF A UNIFORM ALTERNATING MAGNETIC FIELD USING A CIRCULAR PASSIVE LOOP

Directory of Open Access Journals (Sweden)

V. S. Grinchenko

2015-04-01

Full Text Available The magnetic and electromagnetic shields are used to reduce the magnetic field in local spaces. Usually these shields are implemented in the form of a box or a cylinder. At the same time the magnetic field reduction in local spaces by means of passive loops is not considered in detail yet. So, the present study considers shielding capabilities of a circular passive loop. The authors have performed an analytical and numerical modeling of a process of a uniform harmonic magnetic field shielding. The simulated results permit to find out the spatial distribution of the shielded magnetic field. Dependencies of shielding effectiveness on the passive loop radius and cross-section are determined. Moreover, the non-monotonic behavior of the loop radius dependence is shown. We have substantiated that the shielded volume of a circular passive loop is advisable to limit by the sphere with a half loop radius. Presented results give parameters of the circular passive loop that reduces the rms value of the magnetic flux density by 30 %.

Experiment of enhancing critical current in Bi-2223/Ag tape by means of ferromagnetic shielding

Energy Technology Data Exchange (ETDEWEB)

Alamgir, A.K.M. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Beijing 100084 (China)]. E-mail: alam643@hotmail.com; Gu, C. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Beijing 100084 (China); Han, Z. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Beijing 100084 (China)

2005-11-15

Critical current in multifilamentary Ag-sheath Bi-2223 tape is enhanced to some extent by means of thin and narrow coating of pure nickel. The concept of enhancing critical current is based on the magnetic shielding effect resulting in redirection of self-field flux lines. The Ni coating was introduced at the edge regime of the tape in order to redirect the perpendicular component of self-field lines which is severe at the edges. Critical current in a typical Ag-sheath Bi-2223 tape was enhanced up to {approx}11% by 50 {mu}m thick and 0.4 mm long Ni coating without any change of self-field loss. This fact reveals that additional ferromagnetic loss could be compensated by the shielding effect and increased critical current of the tape. The degree of enhancement in critical current as well as ferromagnetic impact on ac losses depend on the length and thickness of ferromagnetic coating introduced. Therefore, it is very important to control the geometry of ferromagnetic coating in order to balance the critical current and ac loss for optimum superconductor performance. Introduction of ferromagnetic coating and its effect on electromagnetic properties in multifilamentary Bi-2223/Ag tape will be reported in this article.

Experiment of enhancing critical current in Bi-2223/Ag tape by means of ferromagnetic shielding

International Nuclear Information System (INIS)

Alamgir, A.K.M.; Gu, C.; Han, Z.

2005-01-01

Critical current in multifilamentary Ag-sheath Bi-2223 tape is enhanced to some extent by means of thin and narrow coating of pure nickel. The concept of enhancing critical current is based on the magnetic shielding effect resulting in redirection of self-field flux lines. The Ni coating was introduced at the edge regime of the tape in order to redirect the perpendicular component of self-field lines which is severe at the edges. Critical current in a typical Ag-sheath Bi-2223 tape was enhanced up to ∼11% by 50 μm thick and 0.4 mm long Ni coating without any change of self-field loss. This fact reveals that additional ferromagnetic loss could be compensated by the shielding effect and increased critical current of the tape. The degree of enhancement in critical current as well as ferromagnetic impact on ac losses depend on the length and thickness of ferromagnetic coating introduced. Therefore, it is very important to control the geometry of ferromagnetic coating in order to balance the critical current and ac loss for optimum superconductor performance. Introduction of ferromagnetic coating and its effect on electromagnetic properties in multifilamentary Bi-2223/Ag tape will be reported in this article

The use of portable shields in industrial radiography

International Nuclear Information System (INIS)

Oliveira e Silva, J.A. de.

1988-01-01

This paper shows techniques actually used to reduce radiations exposure taxes during examinations execution by gamma radiography in regions of high population density. A portable equipment of radiation shield for using in exams by gamma radiography in pipelines, that is an adjustable device in an object body that will be examined, joining a measured collimator and a shield geometrically arranged so that the radiation restrict to impress the radiographic film used in examination without reaching people, objects or self-movings injurious that are nearness. (C.M.) [pt

Nuclear reactions and self-shielding effects of gamma-ray database for nuclear materials

Energy Technology Data Exchange (ETDEWEB)

Fujita, Mitsutane; Noda, Tetsuji [National Research Institute for Metals, Tsukuba, Ibaraki (Japan)

2001-03-01

A database for transmutation and radioactivity of nuclear materials is required for selection and design of materials used in various nuclear reactors. The database based on the FENDL/A-2.0 on the Internet and the additional data collected from several references has been developed in NRIM site of 'Data-Free-Way' on the Internet. Recently, the function predicted self-shielding effect of materials for {gamma}-ray was added to this database. The user interface for this database has been constructed for retrieval of necessary data and for graphical presentation of the relation between the energy spectrum of neutron and neutron capture cross section. It is demonstrated that the possibility of chemical compositional change and radioactivity in a material caused by nuclear reactions can be easily retrieved using a browser such as Netscape or Explorer. (author)

Design of a control system for self-shielded irradiators with remote access capability

International Nuclear Information System (INIS)

Iyengar, R.D.; Verma, P.B.; Prasad, V.V.S.S.; George, Jain R.; Das, Tripti; Deshmukh, D.K.

2001-01-01

With self-shielded irradiators like Gamma chambers, and Blood irradiators are being sold by BRIT to customers both within and outside the country, it has become necessary to improve the quality of service without increasing the overheads. The recent advances in the field of communications and information technology can be exploited for improving the quality of service to the customers. A state of the art control system with remote accessibility has been designed for these irradiators enhancing their performance. This will provide an easy access to these units wherever they might be located, through the Internet. With this technology it will now be possible to attend to the needs of the customers, as regards fault rectification, error debugging, system software update, performance testing, data acquisition etc. This will not only reduce the downtime of these irradiators but also reduce the overheads. (author)

Nuclear reactions and self-shielding effects of gamma-ray database for nuclear materials

International Nuclear Information System (INIS)

Fujita, Mitsutane; Noda, Tetsuji

2001-01-01

A database for transmutation and radioactivity of nuclear materials is required for selection and design of materials used in various nuclear reactors. The database based on the FENDL/A-2.0 on the Internet and the additional data collected from several references has been developed in NRIM site of 'Data-Free-Way' on the Internet. Recently, the function predicted self-shielding effect of materials for γ-ray was added to this database. The user interface for this database has been constructed for retrieval of necessary data and for graphical presentation of the relation between the energy spectrum of neutron and neutron capture cross section. It is demonstrated that the possibility of chemical compositional change and radioactivity in a material caused by nuclear reactions can be easily retrieved using a browser such as Netscape or Explorer. (author)

Four-component relativistic density functional theory calculations of NMR shielding tensors for paramagnetic systems.

Science.gov (United States)

Komorovsky, Stanislav; Repisky, Michal; Ruud, Kenneth; Malkina, Olga L; Malkin, Vladimir G

2013-12-27

A four-component relativistic method for the calculation of NMR shielding constants of paramagnetic doublet systems has been developed and implemented in the ReSpect program package. The method uses a Kramer unrestricted noncollinear formulation of density functional theory (DFT), providing the best DFT framework for property calculations of open-shell species. The evaluation of paramagnetic nuclear magnetic resonance (pNMR) tensors reduces to the calculation of electronic g tensors, hyperfine coupling tensors, and NMR shielding tensors. For all properties, modern four-component formulations were adopted. The use of both restricted kinetically and magnetically balanced basis sets along with gauge-including atomic orbitals ensures rapid basis-set convergence. These approaches are exact in the framework of the Dirac-Coulomb Hamiltonian, thus providing useful reference data for more approximate methods. Benchmark calculations on Ru(III) complexes demonstrate good performance of the method in reproducing experimental data and also its applicability to chemically relevant medium-sized systems. Decomposition of the temperature-dependent part of the pNMR tensor into the traditional contact and pseudocontact terms is proposed.

Connection factor calculation for isotopic neutron flux measurements with foil detectors

International Nuclear Information System (INIS)

Avila L, J.

1987-01-01

Thermal and resonance neutron self-shielding factors, neutron flux distortion and edge effects as well as a connection factor for neutron flux profile around a foil detector have been calculated. A general expression for resonance self shielding factor is presented in order to take into account the most important resonances for a given isotope. A computer program SPRESYTER.BAS was written and results for In-115 and Au-197 foils are given

Dependency and self-criticism in treatments for depression.

Science.gov (United States)

Chui, Harold; Zilcha-Mano, Sigal; Dinger, Ulrike; Barrett, Marna S; Barber, Jacques P

2016-07-01

Dependency and self-criticism are vulnerability factors for depression. How these personality factors change with treatment for depression and how they relate to symptom change across different types of treatment require further research. In addition, cultural differences that interact with the dependency/self-criticism-depression relation remain underinvestigated. We randomly assigned 149 adults with major depression to receive active medication (MED; n = 50), supportive-expressive therapy (SET; n = 49), or placebo pill (PBO; n = 50). Participants completed the Depressive Experiences Questionnaire (DEQ; Blatt, D'Afflitti, & Quinlan, 1976) before and after treatment and completed the Hamilton Rating Scale for Depression (Hamilton, 1967) throughout the course of treatment. Self-criticism as measured on the DEQ decreased with treatment similarly across conditions. DEQ Dependency decreased in MED but remained unchanged in SET and PBO. Higher initial dependency, but not higher initial self-criticism, predicted poor treatment response across conditions. Greater reduction in self-criticism was associated with greater reduction in depressive symptoms, but the effect was weaker for racial minorities (vs. White). Increase in connectedness, an adaptive form of dependency, was associated with symptom improvement in SET but not MED. Hence, different pathways of change seem to be implicated in the treatment of depression depending on culture and type of intervention. Implications for future research are discussed. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Self-optimizing approach for automated laser resonator alignment

Science.gov (United States)

Brecher, C.; Schmitt, R.; Loosen, P.; Guerrero, V.; Pyschny, N.; Pavim, A.; Gatej, A.

2012-02-01

Nowadays, the assembly of laser systems is dominated by manual operations, involving elaborate alignment by means of adjustable mountings. From a competition perspective, the most challenging problem in laser source manufacturing is price pressure, a result of cost competition exerted mainly from Asia. From an economical point of view, an automated assembly of laser systems defines a better approach to produce more reliable units at lower cost. However, the step from today's manual solutions towards an automated assembly requires parallel developments regarding product design, automation equipment and assembly processes. This paper introduces briefly the idea of self-optimizing technical systems as a new approach towards highly flexible automation. Technically, the work focuses on the precision assembly of laser resonators, which is one of the final and most crucial assembly steps in terms of beam quality and laser power. The paper presents a new design approach for miniaturized laser systems and new automation concepts for a robot-based precision assembly, as well as passive and active alignment methods, which are based on a self-optimizing approach. Very promising results have already been achieved, considerably reducing the duration and complexity of the laser resonator assembly. These results as well as future development perspectives are discussed.

Temperature dependence of giant dipole resonance width

International Nuclear Information System (INIS)

Vdovin, A.I.; Storozhenko, A.N.

2005-01-01

The quasiparticle-phonon nuclear model extended to finite temperature within the framework of the thermo field dynamics is applied to calculate a temperature dependence of the spreading width Γ d own of a giant dipole resonance. Numerical calculations are made for 12S n and 208 Pb nuclei. It is found that the width Γ d own increases with T. The reason of this effect is discussed as well as a relation of the present approach to other ones existing in the literature

Tuner and radiation shield for planar electron paramagnetic resonance microresonators

International Nuclear Information System (INIS)

Narkowicz, Ryszard; Suter, Dieter

2015-01-01

Planar microresonators provide a large boost of sensitivity for small samples. They can be manufactured lithographically to a wide range of target parameters. The coupler between the resonator and the microwave feedline can be integrated into this design. To optimize the coupling and to compensate manufacturing tolerances, it is sometimes desirable to have a tuning element available that can be adjusted when the resonator is connected to the spectrometer. This paper presents a simple design that allows one to bring undercoupled resonators into the condition for critical coupling. In addition, it also reduces radiation losses and thereby increases the quality factor and the sensitivity of the resonator

Dynamical cancellation of pulse-induced transients in a metallic shielded room for ultra-low-field magnetic resonance imaging

International Nuclear Information System (INIS)

Zevenhoven, Koos C. J.; Ilmoniemi, Risto J.; Dong, Hui; Clarke, John

2015-01-01

Pulse-induced transients such as eddy currents can cause problems in measurement techniques where a signal is acquired after an applied preparatory pulse. In ultra-low-field magnetic resonance imaging, performed in magnetic fields typically of the order of 100 μT, the signal-to-noise ratio is enhanced in part by prepolarizing the proton spins with a pulse of much larger magnetic field and in part by detecting the signal with a Superconducting QUantum Interference Device (SQUID). The pulse turn-off, however, can induce large eddy currents in the shielded room, producing an inhomogeneous magnetic-field transient that both seriously distorts the spin dynamics and exceeds the range of the SQUID readout. It is essential to reduce this transient substantially before image acquisition. We introduce dynamical cancellation (DynaCan), a technique in which a precisely designed current waveform is applied to a separate coil during the later part and turn off of the polarizing pulse. This waveform, which bears no resemblance to the polarizing pulse, is designed to drive the eddy currents to zero at the precise moment that the polarizing field becomes zero. We present the theory used to optimize the waveform using a detailed computational model with corrections from measured magnetic-field transients. SQUID-based measurements with DynaCan demonstrate a cancellation of 99%. Dynamical cancellation has the great advantage that, for a given system, the cancellation accuracy can be optimized in software. This technique can be applied to both metal and high-permeability alloy shielded rooms, and even to transients other than eddy currents

Nuclear shielding of openings in ITER Tokamak building

Energy Technology Data Exchange (ETDEWEB)

Dammann, A., E-mail: alexis.dammann@iter.org [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Arumugam, A.P.; Beaudoin, V.; Beltran, D.; Benchikhoune, M.; Berruyer, F.; Cortes, P.; Gandini, F. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Ghirelli, N. [ASSYSTEM E.O.S, ZAC Saint Martin, 23, rue Benjamin Franklin, 84120 Pertuis (France); Gray, A.; Hurzlmeier, H.; Le Page, M. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Lemée, A. [SOGETI High Tech, 180 Rue René Descartes, 13851 Aix en Provence (France); Lentini, G.; Loughlin, M.; Mita, Y.; Patisson, L.; Rigoni, G.; Rathi, D.; Song, I. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France)

2013-10-15

Highlights: ► Establishment of a methodology to design shielded opening in external wall of the Tokamak building. ► Analysis of the shielding requirement, case by case, depending on the localization and the context. ► Implementation of an integrated solution for shielded opening. -- Abstract: The external walls of the Tokamak building, made of thick concrete, provide the nuclear shielding for operators working in adjacent buildings and for the environment. There are a series of openings to these external walls, devoted to ducts or pipes for ventilation, waveguides and transmission lines for heating systems and diagnostics, cooling pipes, cable trays or busbars. The shielding properties of the wall shall be preserved by adequate design of the openings in order not to affect the radiological zoning in adjacent areas. For some of them, shielding properties of the wall are not affected because the size of the network is quite small or the source is far from the opening. But for most of the openings, specific features shall be considered. Even if the approach is the same and the ways to shield can be standardized, specific analysis is requested in any case because the constraints are different.

ICRF Faraday shield plasma sheath models: Low and high conductivity limits

International Nuclear Information System (INIS)

Whealton, J.H.; Ryan, P.M.; Raridon, R.J.

1989-01-01

Using a 2-D nonlinear formulation which explicitly considers the plasma edge near a Faraday shield in a self consistent manner, progress is indicated in the modeling of the ion motion for a Faraday shield concept and model suggested by Perkins. Several models are considered which may provide significant insight into the impurities generation for ICRH antennas. 6 refs., 8 figs

BUGLE-93 (ENDF/B-VI) cross-section library data testing using shielding benchmarks

International Nuclear Information System (INIS)

Hunter, H.T.; Slater, C.O.; White, J.E.

1994-01-01

Several integral shielding benchmarks were selected to perform data testing for new multigroup cross-section libraries compiled from the ENDF/B-VI data for light water reactor (LWR) shielding and dosimetry. The new multigroup libraries, BUGLE-93 and VITAMIN-B6, were studied to establish their reliability and response to the benchmark measurements by use of radiation transport codes, ANISN and DORT. Also, direct comparisons of BUGLE-93 and VITAMIN-B6 to BUGLE-80 (ENDF/B-IV) and VITAMIN-E (ENDF/B-V) were performed. Some benchmarks involved the nuclides used in LWR shielding and dosimetry applications, and some were sensitive specific nuclear data, i.e. iron due to its dominant use in nuclear reactor systems and complex set of cross-section resonances. Five shielding benchmarks (four experimental and one calculational) are described and results are presented

Development of special radiation shielding concretes using natural local materials and evaluation of their shielding characteristics

International Nuclear Information System (INIS)

Kharita, M. H.; Takeyeddin, M.; Al-Nassri, M.; Yousef, S.

2008-01-01

Concrete is one of the most important materials used for radiation shielding in facilities containing radioactive sources and radiation generating machines. The concrete shielding properties may vary depending on the composite of the concrete. Aggregates is the largest constituent (about 70-80% of the total weight of normal concrete). The aim of this work is to develop special concrete with good shielding properties for gamma and neutrons, using natural local materials. For this reason two types of typical concrete widely used in Syria (in Damascus and Aleppo) and four other types of concrete, using aggregates from different regions, have been prepared. The shielding properties of these six types were studied for gamma ray (from Cs-137 and Co-60 sources)and for neutrons (from am-Be source). A reduction of about 10% in the HVL was obtained for the concrete from Damascus in comparison with that from Aleppo, for both neutrons and gammas. One of the other four types of concrete (from Rajo site, mostly Hematite), was found to further reduce the HVL by about 10% for both neutrons and gamma rays.(author)

Self-consistent treatment of nuclear collective motion with an application to the giant-dipole resonance

International Nuclear Information System (INIS)

Liran, S.; Technion-Israel Inst. of Tech., Haifa. Dept. of Physics)

1977-01-01

This paper extends the recent theory of Liran, Scheefer, Scheid and Greiner on non-adiabatic cranking and nuclear collective motion. In the present work we show the self-consistency conditions for the collective motion, which are indicated by appropriate time-dependent Lagrange multipliers, can be treated explicitly. The energy conservation and the self-consistency condition in the case of one collective degree of freedom are expressed in differential form. This leads to a set of coupled differential equations in time for the many-body wave function, for the collective variable and for the Lagrange multiplier. An iteration procedure similar to that of the previous work is also presented. As an illustrative example, we investigate Brink's single-particle description of the giant-dipole resonance. In this case, the important role played by non-adiabaticity and self-consistency in determining the collective motion is demonstrated and discussed. We also consider the fact that in this example of a fast collective motion, the adiabatic cranking model of Inglis gives the correct mass parameter. (orig.) [de

Light shielding apparatus

Science.gov (United States)

Miller, Richard Dean; Thom, Robert Anthony

2017-10-10

A light shielding apparatus for blocking light from reaching an electronic device, the light shielding apparatus including left and right support assemblies, a cross member, and an opaque shroud. The support assemblies each include primary support structure, a mounting element for removably connecting the apparatus to the electronic device, and a support member depending from the primary support structure for retaining the apparatus in an upright orientation. The cross member couples the left and right support assemblies together and spaces them apart according to the size and shape of the electronic device. The shroud may be removably and adjustably connectable to the left and right support assemblies and configured to take a cylindrical dome shape so as to form a central space covered from above. The opaque shroud prevents light from entering the central space and contacting sensitive elements of the electronic device.

Measurements and applications of neutron multiple scattering in resonance region

International Nuclear Information System (INIS)

Ohkubo, Makio

1977-02-01

Capture yield of neutrons impinging on a thick material is complicated due to self-shielding and multiple scattering, especially in the resonance region. When the incident neutron energy is equal to a resonance energy of the material, capture probability of the neutron increases with sample thickness and reaches a saturation value P sub(CO). There is a simple relation between P sub(CO) and GAMMA sub(n)/GAMMA and the recoil energy by the Monte-Carlo calculation. To examine validity of the relation, P sub(CO) was measured for 19 resonances in 12 nuclides with thick samples, using a JAERI linac time-of-flight spectrometer with Moxon-Rae type gamma ray detector and transmission type neutron flux monitor. Results of the measurements confirmed the validity. With this relation, the GAMMA sub(n)/GAMMA or GAMMA sub(γ)/GAMMA value can be obtained from the measured P sub(CO), and also the level spins be determined by combining the transmission data. Because of the definition of P sub(CO), determination of the resonance parameters is not sensitive to the sample thickness as far as it is sufficiently thick. (auth.)

An assessment of the lifetime of Faraday shield elements

International Nuclear Information System (INIS)

Caughman, J.B.O. II; Ruzic, D.N.; Hoffman, D.J.; Langley, R.A.; Lewis, M.B.; Ryan, P.M.

1990-01-01

The interaction of plasma with rf fields from an ion cyclotron range of frequencies (ICRF) antenna has been studied to estimate the amount of Faraday shield erosion expected in normal ICRF heating operation. Plasma parameters and ion energies have been measured in the near field of an antenna and used in a model to estimate the erosion rate of the Faraday shield surface. Experiments were conducted on the RF Test Facility, a magnetic mirror device at Oak Ridge National Laboratory, using a single-strap resonant loop antenna with a two-tier Faraday shield. The outer tier, facing the plasma, was layered with graphite tiles. The antenna was operated at currents and voltages within 50% of those expected in tokamaks. The time-varying floating potential was measured with a capacitively coupled probe, and the time-averaged floating potential, electron temperature, and electron density were measured with a Langmuir probe. Ion energies were measured with a gridded energy analyser located below the antenna, and samples of silicon were placed on the Faraday shield surface to estimate the incident ion energy. The capacitive probe measurements show that the rf floating potential follows the magnetic field pattern of the antenna, indicating that the electromagnetic fields are responsible for the potential formation. Plasma parameters and ion energies have been correlated with the antenna current and used in a computational model of the plasma sheath to predict the amount of erosion expected from the Faraday shield elements exposed to plasma. Predictions of light ion sputtering of candidate Faraday shield materials are presented

Redefinition of the self-bias voltage in a dielectrically shielded thin sheath RF discharge

Science.gov (United States)

Ho, Teck Seng; Charles, Christine; Boswell, Rod

2018-05-01

In a geometrically asymmetric capacitively coupled discharge where the powered electrode is shielded from the plasma by a layer of dielectric material, the self-bias manifests as a nonuniform negative charging in the dielectric rather than on the blocking capacitor. In the thin sheath regime where the ion transit time across the powered sheath is on the order of or less than the Radiofrequency (RF) period, the plasma potential is observed to respond asymmetrically to extraneous impedances in the RF circuit. Consequently, the RF waveform on the plasma-facing surface of the dielectric is unknown, and the behaviour of the powered sheath is not easily predictable. Sheath circuit models become inadequate for describing this class of discharges, and a comprehensive fluid, electrical, and plasma numerical model is employed to accurately quantify this behaviour. The traditional definition of the self-bias voltage as the mean of the RF waveform is shown to be erroneous in this regime. Instead, using the maxima of the RF waveform provides a more rigorous definition given its correlation with the ion dynamics in the powered sheath. This is supported by a RF circuit model derived from the computational fluid dynamics and plasma simulations.

Representation of the neutron cross sections of several fertile and fissile nuclei in the resonance regions

International Nuclear Information System (INIS)

de Saussure, G.; Perez, R.B.

1981-01-01

Several aspects of the measurement, analysis and evaluation of the cross sections of the fertile and fissile nuclides in the resonance regions are discussed. In the resolved range, for the fertile nuclides it is thought that the principal requirement for improved evaluations is for a practical methodology to deal with systematic errors and their correlations. For the fissile nuclides 235 U and 239 Pu, the ENDF/B-V evaluations are not consistent with ENDF/B procedures recommendations and fall short of the goals of resonance analysis. New evaluations of these two isotopes should be performed. In the unresolved resonance region it is shown that the ENDF/B representation is ambiguous and is not theoretically justified. A better representation may be desirable, and a validation of the representation with experimental self-shielding and transmission measurements is certainly required. 105 references

Angle-dependent spin-wave resonance spectroscopy of (Ga,Mn)As films

Science.gov (United States)

Dreher, L.; Bihler, C.; Peiner, E.; Waag, A.; Schoch, W.; Limmer, W.; Goennenwein, S. T. B.; Brandt, M. S.

2013-06-01

A modeling approach for standing spin-wave resonances based on a finite-difference formulation of the Landau-Lifshitz-Gilbert equation is presented. In contrast to a previous study [C. Bihler , Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.79.045205 79, 045205 (2009)], this formalism accounts for elliptical magnetization precession and magnetic properties arbitrarily varying across the layer thickness, including the magnetic anisotropy parameters, the exchange stiffness, the Gilbert damping, and the saturation magnetization. To demonstrate the usefulness of our modeling approach, we experimentally study a set of (Ga,Mn)As samples grown by low-temperature molecular-beam epitaxy by means of angle-dependent standing spin-wave resonance spectroscopy and electrochemical capacitance-voltage measurements. By applying our modeling approach, the angle dependence of the spin-wave resonance data can be reproduced in a simulation with one set of simulation parameters for all external field orientations. We find that the approximately linear gradient in the out-of-plane magnetic anisotropy is related to a linear gradient in the hole concentrations of the samples.

Mechanical design of the TIBER breeding shield

Energy Technology Data Exchange (ETDEWEB)

Rathke, J.; Deutsch, L. (Grumman Corp., Bethpage, NY (USA). Space Systems Div.)

1989-04-01

TIBER features a segmented shield assembly that provides the nuclear shielding for the superconducting toroidal field coils. In addition to its primary function, the shield also provides tritium breeding through the use of water coolant that contains 16 wt% dissolved lithium nitrate. Because the TIBER reactor need not provide electrical power, the coolant is maintained at low pressure (0.2 MPa) and low temperature (75/sup 0/C). The shield is made in several segments to facilitate assembly and allow for replacement of high heat flux components (divertor blades). The segments are designated as inboard, outboard, upper, lower, and divertor modules. In total, there are 96 separate modules in the machine, consisting of six different types. The design features of the different modules vary primarily depending on the thickness of the shield in a given location. The very thick outboard shield has a breeding zone in the inboard portion of the module, with a shielding zone behind it. The breeding zone consists of a stainless steel casing filled with beryllium spheres. The shielding zone consists of the same casing filled with steel spheres. Both of these zones have lithiated water circulated throughout to provide cooling and breeding. In zones with minimal thickness, tungsten alloys are used to achieve the required shielding. These alloys are incoprorated in subassemblies utilizing stainless steel casings surrounding blocks of tungsten heavy metal alloy. These are infiltrated with lead on final assembly to form a thermally continuous panel. Several of these panels are then assembled into an outer stainless steel case to form an inboard module. These modules also use the lithiated coolant. The details of the design are presented and discussed. (orig.).

Self-cognitions in antisocial alcohol dependence and recovery.

Science.gov (United States)

Corte, Colleen; Stein, Karen Farchaus

2007-02-01

Cross-sectional relationships between content and structural properties of the self-concept and alcohol use in young adults with antisocial alcohol dependence (AAD) (n = 24), those in recovery from AAD (n = 18), and controls (n = 23) were examined using the schema model of the self-concept. Persons with AAD had a trend toward fewer positive self-schemas than did controls, and had more negative self-schemas and a trend toward higher interrelatedness than did those in recovery and controls. They also showed evidence of a drinking-related self-schema, whereas those in recovery showed evidence of a recovery-related self-schema. Finally, evidence to support a model using properties of the self-concept to predict high levels of alcohol use was found. These findings provide a beginning empirical foundation for the development of nursing interventions aimed at altering self-structure to prevent the development of and promote recovery from antisocial alcohol dependence.

A support shield for a powered support

Energy Technology Data Exchange (ETDEWEB)

Korczynski, P; Rojicek, P

1982-08-31

The subject of this invention is a support shield for a powered support. This shield resists creep of the coal from the longwall face, including an inclined longwall. It involves an arrangement wherein the distributor hinge is separated into upper and lower sections. The lower section holds a second hinge and the end of the rod of the pressure cylinder, one end of which is connected to the roof support. An advantage of the support is that compared to existing supports, it is self-advancing and holds stopes with coal which slopes in its formation or has inrushes. To a certain degree it prevents the stope space from ejecting fine pieces of rock from the longwall roof using an inter-timber support between the powered support and the stope. The support shield is moved by a simple system of levers which makes it possible, using a pressurized cylinder, to transmit a significant force to the coal stope. In this case, when the coal inrushes exceed the designed capabilities of the shield, a wooden extension piece is placed between the support and the face, through which the support pressure is applied.

AP1000 shield building: a constructability challenge

International Nuclear Information System (INIS)

Di Giuseppe, Giovanni; Bonanno, Domenico

2010-01-01

The AP1000 Shield Building, an enhanced structure which surrounds the containment vessel, consists of standard Reinforced Concrete (RC) and composite Steel and Concrete (SC) construction. In the SC module the surface steel plates, (with attached shear studs and angles) filled with concrete, act as the steel reinforcement in concrete. This is a relatively new design technology that required the appropriate use of structural codes, supplemented with information from applicable tests on similar composite steel and concrete construction. Being a newer design concept, existing codes do not provide explicit guidance on SC construction so a review of literature and test data on composite structures similar to AP1000 shield building was done in order to confirm the technical basis for the design. The SC walls, air inlet structure and roof of the Shield Building will be constructed using modular construction practices and then transported to site and lifted into place. These modules, working also as permanent form-work, will be filled with high strength Self- Consolidating Concrete. (SCC) This paper provides a focused and integrated presentation of the enhanced shield building design methodology, testing, constructability and inspection. (authors)

Core-dependent and ligand-dependent relativistic corrections to the nuclear magnetic shieldings in MH4-n Y n (n = 0-4; M = Si, Ge, Sn, and Y = H, F, Cl, Br, I) model compounds.

Science.gov (United States)

Maldonado, Alejandro F; Aucar, Gustavo A; Melo, Juan I

2014-09-01

The nuclear magnetic shieldings of Si, Ge, and Sn in MH(4-n) Y(n) (M = Si, Ge, Sn; Y = F, Cl, Br, I and n = 1-4) molecular systems are highly influenced by the substitution of one or more hydrogens by heavy-halogen atoms. We applied the linear response elimination of small components (LRESC) formalism to calculate those shieldings and learn whether including only a few of the leading relativistic correction terms is sufficient to be able to quantitatively reproduce the full relativistic value. It was observed that the nuclear magnetic shieldings change as the number of heavy halogen substituents and their weights vary, and the pattern of σ(M) generally does not exhibit the normal halogen dependence (NHD) behavior that can be seen in similar molecular systems containing carbon atoms. We also analyzed each relativistic correction afforded by the LRESC method and split them in two: core-dependent and ligand-dependent contributions; we then looked for the electronic mechanisms involved in the different relativistic effects and in the total relativistic value. Based on this analysis, we were able to study the electronic mechanism involved in a recently proposed relativistic effect, the "heavy atom effect on vicinal heavy atom" (HAVHA), in more detail. We found that the main electronic mechanism is the spin-orbit or σ p (T(3)) correction, although other corrections such as σ p (S(1)) and σ p (S(3)) are also important. Finally, we analyzed proton magnetic shieldings and found that, for molecules containing Sn as the central atom, σ(H) decreases as the number of heavy halogen substituents (of the same type: either F, Cl, or Br) increases, albeit at different rates for different halogens. σ(H) only increase as the number of halogen substituents increases if the halogen is iodine.

Self-body recognition depends on implicit and explicit self-esteem.

Science.gov (United States)

Richetin, Juliette; Xaiz, Annalisa; Maravita, Angelo; Perugini, Marco

2012-03-01

The present contribution bridges research on body image, self-esteem, and body recognition. Recent work in neuroscience indicates a superiority in the processing of self relative to others' body parts. The present contribution shows that this ability is not universal but it is qualified by individual differences in implicit and explicit self-esteem. In fact, two studies (n₁ = 41 and n₂ = 35) using two different paradigms in body recognition and direct and indirect measures of self-esteem reveal that this advantage in recognizing one's own body parts is associated with one's level of self-esteem. Moreover, it appears that measures of implicit and explicit self-esteem provide different contributions to self-body recognition abilities and that these contributions depend on how self-body recognition is assessed. Implications of these results are discussed notably in the perspective of research on body image. Copyright © 2011 Elsevier Ltd. All rights reserved.

Observation of self-pulsing in singly resonant optical second-harmonic generation with competing nonlinearities

DEFF Research Database (Denmark)

Bache, Morten; Lodahl, Peter; Mamaev, Alexander V.

2002-01-01

We predict and experimentally observe temporal self-pulsing in singly resonant intracavity second-harmonic generation under conditions of simultaneous parametric oscillation. The threshold for self-pulsing as a function of cavity tuning and phase mismatch are found from analysis of a three...

Evaluation of syringe shield effectiveness in handling radiopharmaceuticals

Directory of Open Access Journals (Sweden)

Cho Yong-In

2015-01-01

Full Text Available The purpose of this study was to evaluate the effectiveness of the radiation shield of radionuclide syringes and the personal dose equivalent by performing a simulation of radionuclides used in nuclear medicine diagnosis. In order to evaluate the dose depending on the distance between the radiation source and the ICRU sphere against the thickness of the shielding device, the distance at which a nuclear medicine worker may inadvertently come into contact with radiation from the radiation source was set at 0 cm to 30 cm according to the thickness of the shield, thus fixing the ICRU sphere. For a dose evaluation, Hp(10, Hp(3, and Hp(0.07 measurable in specific depth of the ICRU were evaluated. It was found that a dose measured on skin surface of nuclear medicine workers was relatively higher, that the dose varied in relation to the thickness of the radiation shield, and that the shielding effect decreased for some radiation sources such as 67Ga and 111In. It proved necessary to increase thickness of shielding device to the radiation sources such as 67Ga and 111In. It is also considered that a study of proper shielding thickness will be needed in future.

Acoustic metacages for sound shielding with steady air flow

Science.gov (United States)

Shen, Chen; Xie, Yangbo; Li, Junfei; Cummer, Steven A.; Jing, Yun

2018-03-01

Conventional sound shielding structures typically prevent fluid transport between the exterior and interior. A design of a two-dimensional acoustic metacage with subwavelength thickness which can shield acoustic waves from all directions while allowing steady fluid flow is presented in this paper. The structure is designed based on acoustic gradient-index metasurfaces composed of open channels and shunted Helmholtz resonators. In-plane sound at an arbitrary angle of incidence is reflected due to the strong parallel momentum on the metacage surface, which leads to low sound transmission through the metacage. The performance of the proposed metacage is verified by numerical simulations and measurements on a three-dimensional printed prototype. The acoustic metacage has potential applications in sound insulation where steady fluid flow is necessary or advantageous.

Self-Resonant Electrically Small Loop Antennas for Hearing-Aids Application

DEFF Research Database (Denmark)

Zhang, Jiaying; Breinbjerg, Olav

2010-01-01

Two novel self-resonant electrically small antennas are proposed in this paper, which are designed for hearing aids applications. They are miniaturized by using the capacitive and inductive coupling mechanism between two loops, and the antenna impedance can be matched to a specific value without...... using any additional matching network and lumped components. The dimension of the proposed antenna is 0.10λ0×0.03λ0, and it is designed to be resonant at 900 MHz. Both the analytical model and numerical simulations are discussed and explained. The antenna is also fabricated and measured in an anechoic...... chamber. The measurement methods for electrically small antennas are reported....

Penetrating power of resonant electromagnetic induction imaging

Directory of Open Access Journals (Sweden)

Roberta Guilizzoni

2016-09-01

Full Text Available The possibility of revealing the presence and identifying the nature of conductive targets is of central interest in many fields, including security, medicine, industry, archaeology and geophysics. In many applications, these targets are shielded by external materials and thus cannot be directly accessed. Hence, interrogation techniques are required that allow penetration through the shielding materials, in order for the target to be identified. Electromagnetic interrogation techniques represent a powerful solution to this challenge, as they enable penetration through conductive shields. In this work, we demonstrate the power of resonant electromagnetic induction imaging to penetrate through metallic shields (1.5-mm-thick and image targets (having conductivities σ ranging from 0.54 to 59.77 MSm−1 concealed behind them.

1 1/2 years of experience with a 10 MeV self-shielded on-line e-beam sterilization system

International Nuclear Information System (INIS)

Lambert, Byron; Tang, Fuh-Wei; Riggs, Brian; Allen, Thomas; Williams, C.B.

2000-01-01

The Vascular Intervening Group of the Guidant Corporation (Guidant IV) has been operating a self-shielded, 10 MeV 4 kW, electron beam sterilization system since July of 1988. The system was designed, built and installed in a 70 square meter area in an existing Guidant manufacturing facility by Titan Scan Corporation and performance of the system was validated in conformance with 1S0-11137 standards. The goal of this on-site e-beam system was 'just in time' JIT, sterilization, i.e. the ability to manufacture, sterilize and ship, high intrinsic value medical devices in less than 24 hours. The benefits of moving from a long gas sterilization cycle of greater than one week to a JIT process were envisioned to be a) speed to market with innovated new products b) rapid response to customer requirements c) reduced inventory carrying costs and finally manufacturing and quality system efficiency. The ability of Guidant to realize these benefits depended upon the ability of the Guidant VI business units to adapt to the new sterilization modality and functionality and on the overall system reliability. This paper reviews the operating experience to date and the overall system reliability. (author)

Capsule shields the function of short bacterial adhesins

DEFF Research Database (Denmark)

Schembri, Mark; Dalsgaard, D.; Klemm, Per

2004-01-01

Bacterial surface structures such as capsules and adhesins are generally regarded as important virulence factors. Here we demonstrate that capsules block the function of the self-recognizing protein antigen 43 through physical shielding. The phenomenon is not restricted to Escherichia coli but can...

Group cross sections in the resolved resonance region calculated for a CANDU-PHW reactor operating on closed thorium-uranium and thorium-plutonium-uranium fuel cycles

International Nuclear Information System (INIS)

Hamel, D.; Wilkin, G.B.

1979-09-01

Group cross sections in the resolved resonance region are commonly computed for each nuclide independently of other resonance nuclides present in the fuel mixture. While this technique is usually entirely adequate for uranium fuel cycles, it is necessary to establish its legitimacy for closed thorium fuel cycles topped with fissile uranium or plutonium by analysis of a number of representative cases. At the same time cross sections originating from WIMS (Winfrith Improved Multigroup Scheme) calculations are compared with values computed in this study. In this context, particular attention is paid to the adequacy of the lower boundary for the WIMS resonance treatment. All calculations are based on heavy nuclide cross sections from the ENDF/B-IV data compilaton (Evaluated Nuclear Data File). Appreciable interaction effects have been determined for all nuclides except for 232 Th. In most cases, these are due to the strong 232 Th resonance doublet at 21.8 eV and 23.5 eV but some effects also result from resonances of 234 U (5.19 eV, 48.75 eV), 236 U (5.45 eV), 242 Pu (2.67 eV) and others. The influence of mutual interaction on the infinite lattice multiplicaton factor is very small in comparison to the effects of self-shielding. WIMS cross sections do not always compare well with the values computed in the study, but discrepancies are in most cases related to the different sources of data. Interaction effects are not explicitly taken into account in WIMS. Several nuclides ( 233 Pa, 233 U, 240 Pu, 242 Pu) show appreciable self-shielding below the WIMS resonance region and are therefore not treated adequately. The impact of these discrepancies on the multiplication factor is relatively small, however, because of error cancellation. (author)

Electromagnetic shielding

International Nuclear Information System (INIS)

Tzeng, Wen-Shian V.

1991-01-01

Electromagnetic interference (EMI) shielding materials are well known in the art in forms such as gaskets, caulking compounds, adhesives, coatings and the like for a variety of EMI shielding purposes. In the past, where high shielding performance is necessary, EMI shielding has tended to use silver particles or silver coated copper particles dispersed in a resin binder. More recently, aluminum core silver coated particles have been used to reduce costs while maintaining good electrical and physical properties. (author). 8 figs

Segmentation of head magnetic resonance image using self-mapping characteristic

International Nuclear Information System (INIS)

Madokoro, Hirokazu; Sato, Kazuhito; Ishii, Masaki; Kadowaki, Sakura

2004-01-01

In this paper, we proposed a segmentation method, for head magnetic resonance (MR) images. Our method used self mapping characteristic of a self-organization map (SOM), and it does not need the setting of the representative point by the operator. We considered the continuity and boundary in the brain tissues by the definition of the local block. In the evaluation experiment, we obtained the segmentation result of matching anatomical structure information. In addition, our method applied the clinical MR images, it was possible to obtain the effective and objective result for supporting the diagnosis of the brain atrophy by the doctor. (author)

About the Scythian Shields

Directory of Open Access Journals (Sweden)

About the Scythian Shields

2017-10-01

Full Text Available Shields played major role in the armament system of the Scythians. Made from organic materials, they are poorly traced on the materials of archaeological excavations. Besides, scaly surface of shields was often perceived in practice as the remnants of the scaly armor. E. V. Chernenko was able to discern the difference between shields’ scaly plates and armor scales. The top edge of the scales was bent inwards, and shield plates had a wire fixation. These observations let significantly increase the number of shields, found in the burial complexes of the Scythians. The comparison of archaeological materials and the images of Scythian warriors allow distinguishing the main forms of Scythian shields. All shields are divided into fencing shields and cover shields. The fencing shields include round wooden shields, reinforced with bronze sheet, and round moon-shaped shields with a notch at the top, with a metal scaly surface. They came to the Scythians under the Greek influence and are known in the monuments of the 4th century BC. Oval shields with scaly surface (back cover shields were used by the Scythian cavalry. They protected the rider in case of frontal attack, and moved back in case of maneuver or closein fighting. Scythian battle tactics were based on rapid approaching the enemy and throwing spears and further rapid withdrawal. Spears stuck in the shields of enemies, forcing them to drop the shields, uncover, and in this stage of the battle the archers attacked the disorganized ranks of the enemy. That was followed by the stage of close fight. Oval form of a wooden shield with leather covering was used by the Scythian infantry and spearmen. Rectangular shields, including wooden shields and the shields pleached from rods, represented a special category. The top of such shield was made of wood, and a pleached pad on leather basis was attached to it. This shield could be a reliable protection from arrows, but it could not protect against javelins

Survivor shielding. Part C. Improvements in terrain shielding

International Nuclear Information System (INIS)

Egbert, Stephen D.; Kaul, Dean C.; Roberts, James A.; Kerr, George D.

2005-01-01

A number of atomic-bomb survivors were affected by shielding provided by terrain features. These terrain features can be a small hill, affecting one or two houses, or a high mountain that shields large neighborhoods. In the survivor dosimetry system, terrain shielding can be described by a transmission factor (TF), which is the ratio between the dose with and without the terrain present. The terrain TF typically ranges between 0.1 and 1.0. After DS86 was implemented at RERF, the terrain shielding categories were examined and found to either have a bias or an excessive uncertainty that could readily be removed. In 1989, an improvement in the terrain model was implemented at RERF in the revised DS86 code, but the documentation was not published. It is now presented in this section. The solution to the terrain shielding in front of a house is described in this section. The problem of terrain shielding of survivors behind Hijiyama mountain at Hiroshima and Konpirasan mountain at Nagasaki has also been recognized, and a solution to this problem has been included in DS02. (author)

Shielding modefication and safety review on Mutsu

International Nuclear Information System (INIS)

Osanai, Masao

1978-01-01

The Japan Atomic Energy Commission requests strongly to repair the shielding and make general safety inspection on Mutsu after an accident of radiation leakage from the reactor. The content and procedure of this repair of shielding and general safety inspection are outlined. The neutron leakage location in the reactor proper, technical shielding investigation, conceptual design of relating shielding repair, the mock up test of the shielding on the neutron streaming, the final conceptual design of repair, the relating research and development experiment and the detailed basic design of repair are explained, comparing the original design and the modified one. The modified design depends on the experimental results of neutron streaming test between the reactor vessel and the primary shield. As for the general safety inspection, the functional test of control rod driving mechanism and other main components, the flaw detection for heat transfer tubes of the steam generator and primary cooling pipings are carried out in hardwares, and the integrity analysis of fuel assemblies, stress corrosion cracking of fuel claddings and primary cooling pipings, the natural circulation analysis of primary cooling system, and integrity check of the heat transfer tubes of steam generator are carried out in softwares. The burst test and the strength test after high temperature oxidation for fuel claddings made of stainless steel were carried out. (Nakai, Y.)

The temperature dependence of quantum spin pumping generated using electron spin resonance with three-magnon splittings

International Nuclear Information System (INIS)

Nakata, Kouki

2013-01-01

On the basis of the Schwinger–Keldysh formalism, we have closely investigated the temperature dependence of quantum spin pumping generated using electron spin resonance. We have clarified that three-magnon splittings excite non-zero modes of magnons and characterize the temperature dependence of quantum spin pumping generated using electron spin resonance. (paper)

Shielding Design and Radiation Shielding Evaluation for LSDS System Facility

International Nuclear Information System (INIS)

Kim, Younggook; Kim, Jeongdong; Lee, Yongdeok

2015-01-01

As the system characteristics, the target in the spectrometer emits approximately 1012 neutrons/s. To efficiently shield the neutron, the shielding door designs are proposed for the LSDS system through a comparison of the direct shield and maze designs. Hence, to guarantee the radiation safety for the facility, the door design is a compulsory course of the development of the LSDS system. To improve the shielding rates, 250x250 covering structure was added as a subsidiary around the spectrometer. In this study, the evaluations of the suggested shielding designs were conducted using MCNP code. The suggested door design and covering structures can shield the neutron efficiently, thus all evaluations of all conditions are satisfied within the public dose limits. From the Monte Carlo code simulation, Resin(Indoor type) and Tungsten(Outdoor type) were selected as the shielding door materials. From a comparative evaluation of the door thickness, In and Out door thickness was selected 50 cm

The angular gamma flux in an iron slab shield

International Nuclear Information System (INIS)

Penkuhn, H.

1975-08-01

The angular distribution of the photon energy and dose rate flux in a plane iron shield is investigated assuming an isotropic volume source. Near the shield axis (cos phi approximately 1, with phi=angle between shield axis and gamma direction) the angular spectrum is strongly space-dependent. For large phi, space-independent fits are given. Source energies from 0.662 to 6 MeV and penetrations from 6 to 60 cm are treated and the results are compared with a similar investigation on normal concrete. The differences iron-concrete are appreciable only for the lowest source energy

Multi-Layered Effects of Fe on EMI Shielding of Sn-Al Hotel Architectural Powder

Directory of Open Access Journals (Sweden)

Hung Fei-Shuo

2016-01-01

Full Text Available No evident effect in shielding efficiency is observed when the electromagnetic wave-absorbing coating materials were applied in single layers because of the dispersing nature of the powder. When increased to two-layer coating, shielding effects were evident at both high and low frequencies, with greater shielding efficiency at low frequencies over high frequencies. It is worth noting that when increased to three-layer coating, as the weight percentage of powdered Fe increased from 5% to 8% , the shielding efficiency of the powdered-Fe composite material was raised to −35 dB This shows that, as the weight percentage gets higher, the powder shows the resonance phenomenon of permeability spectrum, and at high frequencies, the electromagnetic wave shielding efficiency of the composite materials were greatly increased. As the weight percentage of the powered Fe were increased to 8% , we were unable to spread the powder evenly in the epoxy because of the dispersing characteristic in the electromagnetic properties of Fe and the anisotropic and heterogeneous nature of a powered composite material. During production, the powder aggregates often resulted in greater heterogeneity in the materials and consequently, lowered shielding efficiency at 3GHz.

Injection-controlled laser resonator

Science.gov (United States)

Chang, J.J.

1995-07-18

A new injection-controlled laser resonator incorporates self-filtering and self-imaging characteristics with an efficient injection scheme. A low-divergence laser signal is injected into the resonator, which enables the injection signal to be converted to the desired resonator modes before the main laser pulse starts. This injection technique and resonator design enable the laser cavity to improve the quality of the injection signal through self-filtering before the main laser pulse starts. The self-imaging property of the present resonator reduces the cavity induced diffraction effects and, in turn, improves the laser beam quality. 5 figs.

VHF Series-Input Parallel-Output Interleaved Self-Oscillating Resonant SEPIC Converter

DEFF Research Database (Denmark)

Kovacevic, Milovan; Knott, Arnold; Andersen, Michael A. E.

2013-01-01

If the switches of two resonant SEPIC converters are capacitively coupled, it is possible to obtain a self-oscillating converter in which the two power stages operate in interleaved mode. This paper describes a topology where the inputs of two SEPIC converters are connected in series, thereby sha...

Analysis of a shielded TE011 mode composite dielectric resonator ...

Indian Academy of Sciences (India)

Abstract. Analysis of a TE011 mode composite sapphire–rutile dielectric resonator has been car- ried out to study the temperature variation of resonance frequency, close to the Cs atomic clock hyperfine frequency of 9.192 GHz. The complementary behavior of dielectric permittivity with tem- perature of the composite has ...

Operant ethanol self-administration in ethanol dependent mice.

Science.gov (United States)

Lopez, Marcelo F; Becker, Howard C

2014-05-01

While rats have been predominantly used to study operant ethanol self-administration behavior in the context of dependence, several studies have employed operant conditioning procedures to examine changes in ethanol self-administration behavior as a function of chronic ethanol exposure and withdrawal experience in mice. This review highlights some of the advantages of using operant conditioning procedures for examining the motivational effects of ethanol in animals with a history of dependence. As reported in rats, studies using various operant conditioning procedures in mice have demonstrated significant escalation of ethanol self-administration behavior in mice rendered dependent via forced chronic ethanol exposure in comparison to nondependent mice. This paper also presents a summary of these findings, as well as suggestions for future studies. Copyright © 2014 Elsevier Inc. All rights reserved.

The manufacturing of depleted uranium biological shield components

International Nuclear Information System (INIS)

Metelkin, J.A.

1998-01-01

The unique combination of the physical and mechanical properties of uranium made it possible to manufacture biological shield components of transport package container (TPC) for transportation nuclear power plant irradiated fuel and radionuclides of radiation diagnostic instruments. Protective properties are substantially dependent on the nature radionuclide composition of uranium, that why I recommended depleted uranium after radiation chemical processing. Depleted uranium biological shield (DUBS) has improved specific mass-size characteristics compared to a shield made of lead, steel or tungsten. Technological achievements in uranium casting and machining made it possible to manufacture DUBS components of TPC up to 3 tons of mass and up to 2 metres of the maximum size. (authors)

Shielding benchmark problems

International Nuclear Information System (INIS)

Tanaka, Shun-ichi; Sasamoto, Nobuo; Oka, Yoshiaki; Kawai, Masayoshi; Nakazawa, Masaharu.

1978-09-01

Shielding benchmark problems were prepared by the Working Group of Assessment of Shielding Experiments in the Research Comittee on Shielding Design of the Atomic Energy Society of Japan, and compiled by the Shielding Laboratory of Japan Atomic Energy Research Institute. Twenty-one kinds of shielding benchmark problems are presented for evaluating the calculational algorithm and the accuracy of computer codes based on the discrete ordinates method and the Monte Carlo method and for evaluating the nuclear data used in the codes. (author)

Using the shield for thermal energy storage in pulsar

International Nuclear Information System (INIS)

Sager, G.T.; Sze, D.K.; Wong, C.P.C.; Bathke, C.G.; Blanchard, J.P.; Brimer, C.; Cheng, E.T.; El-Guebaly, L.A.; Hasan, M.Z.; Najmabadi, F.; Sharafat, S.; Sviatoslavski, I.N.; Waganer, L.

1995-01-01

The PULSAR pulsed tokamak power plant design utilizes the outboard shield for thermal energy storage to maintain full 1000MW(e) output during the dwell period of 200s. Thermal energy resulting from direct nuclear heating is accumulated in the shield during the 7200s fusion power production phase. The maximum shield temperature may be much higher than that for the blanket because radiation damage is significantly reduced. During the dwell period, thermal power discharged from the shield and coolant temperature are simultaneously regulated by controlling the coolant mass flow rate at the shield inlet. This is facilitated by throttled coolant bypass. Design concepts using helium and lithium coolant have been developed. Two-dimensional time-dependent thermal hydraulic calculations were performed to confirm performance capabilities required of the design concepts. The results indicate that the system design and performance can accommodate uncertainties in material limits or the length of the dwell period. (orig.)

Next generation self-shielded flux cored electrode with improved toughness for off shore oil well platform structures

Energy Technology Data Exchange (ETDEWEB)

Singh, Daya; Soltis, Patrick; Narayanan, Badri; Quintana, Marie; Fox, Jeff [The Lincoln Electric Company (United States)

2005-07-01

Self-shielded flux cored arc welding electrodes (FCAW-S) are ideal for outdoor applications, particularly open fabrication yards where high winds are a possibility. Development work was carried out on a FCAW-S electrode for welding 70 and 80 ksi yield strength base materials with a required minimum average Charpy V-Notch (CVN) absorbed energy value of 35 ft-lb at -40 deg F in the weld metal. The effect of Al, Mg, Ti, and Zr on CVN toughness was evaluated by running a Design of Experiments approach to systematically vary the levels of these components in the electrode fill and, in turn, the weld metal. These electrodes were used to weld simulated pipe joints. Over the range of compositions tested, 0.05% Ti in the weld metal was found to be optimum for CVN toughness. Ti also had a beneficial effect on the usable voltage range. Simulated offshore joints were welded to evaluate the effect of base metal dilution, heat input, and welding procedure on the toughness of weld metal. CVN toughness was again measured at -40 deg F on samples taken from the root and the cap pass regions. The root pass impact toughness showed strong dependence on the base metal dilution and the heat input used to weld the root and fill passes. (author)

Resonant ultrasound spectrometer

Science.gov (United States)

Migliori, Albert; Visscher, William M.; Fisk, Zachary

1990-01-01

An ultrasound resonant spectrometer determines the resonant frequency spectrum of a rectangular parallelepiped sample of a high dissipation material over an expected resonant response frequency range. A sample holder structure grips corners of the sample between piezoelectric drive and receive transducers. Each transducer is mounted on a membrane for only weakly coupling the transducer to the holder structure and operatively contacts a material effective to remove system resonant responses at the transducer from the expected response range. i.e., either a material such as diamond to move the response frequencies above the range or a damping powder to preclude response within the range. A square-law detector amplifier receives the response signal and retransmits the signal on an isolated shield of connecting cabling to remove cabling capacitive effects. The amplifier also provides a substantially frequency independently voltage divider with the receive transducer. The spectrometer is extremely sensitive to enable low amplitude resonance to be detected for use in calculating the elastic constants of the high dissipation sample.

Poor Utility of Gonadal Shielding for Pediatric Pelvic Radiographs.

Science.gov (United States)

Lee, Mark C; Lloyd, Jessica; Solomito, Matthew J

2017-07-01

Plain pelvic radiographs are commonly used for a variety of pediatric orthopedic disorders. Lead shielding is typically placed over the gonads to minimize radiation exposure to these sensitive tissues. However, misplaced shielding can sabotage efforts to protect patients from excessive radiation exposure either by not covering radiosensitive tissues or by obscuring anatomic areas of interest, prompting repeat radiographic examinations. The goal of this study was to determine the incidence of misplaced shielding for pelvic radiographs obtained for pediatric orthopedic evaluation. Children 8 to 16 years old who had an anteroposterior or frog lateral pelvic radiograph between 2008 and 2014 were included. A total of 3400 patients met the inclusion criteria, and 84 boys and 84 girls were randomly selected for review. For both boys and girls, the percentage of incorrectly positioned or missing shields was calculated. Chi-square testing was used to compare the frequency of missing or incorrectly placed shields between sexes and age groups. Pelvic shields were misplaced in 49% of anteroposterior and 63% of frog lateral radiographs. Shielding was misplaced more frequently for girls than for boys on frog lateral radiographs (76% vs 51%; P<.05). Pelvic bony landmarks were often obscured by pelvic shielding, with a frequency of 7% to 43%, depending on the specific landmark. The femoral head and acetabulum were obscured by shielding in up to 2% of all images. The findings suggest that accepted pelvic shielding protocols are ineffective. Consideration should be given to alternative protocols or abandonment of this practice. [Orthopedics. 2017; 40(4):e623-e627.]. Copyright 2017, SLACK Incorporated.

Validity of Hansen-Roach cross sections in low-enriched uranium systems

International Nuclear Information System (INIS)

Busch, R.D.; O'Dell, R.D.

1991-01-01

Within the nuclear criticality safety community, the Hansen-Roach 16 group cross section set has been the ''standard'' for use in k eff calculations over the past 30 years. Yet even with its widespread acceptance, there are still questions about its validity and adequacy, about the proper procedure for calculating the potential scattering cross section, σ p , for uranium and plutonium, and about the concept of resonance self shielding and its impact on cross sections. This paper attempts to address these questions. It provides a brief background on the Hansen-Roach cross sections. Next is presented a review of resonances in cross sections, self shielding of these resonances, and the use of σ p to characterize resonance self shielding. Three prescriptions for calculating σ p are given. Finally, results of several calculations of k eff on low-enriched uranium systems are provided to confirm the validity of the Hansen-Roach cross sections when applied to such systems

Validity of Hansen-Roach cross sections in low-enriched uranium systems

International Nuclear Information System (INIS)

Busch, R.D.; O'Dell, R.D.

1991-01-01

Within the nuclear criticality safety community, the Hansen-Roach 16 group cross section set has been the standard for use in k eff calculations over the past 30 years. Yet even with its widespread acceptance, there are still questions about its validity and adequacy, about the proper procedure for calculating the potential scattering cross section, σ p , for uranium and plutonium, and about the concept of resonance self shielding and its impact on cross sections. This paper attempts to address these questions. It provides a brief background on the Hansen-Roach cross sections. Next is presented a review of resonances in cross sections, self shielding of these resonances, and the use of σ p to characterize resonance self shielding. Three prescriptions for calculating σ p are given. Finally, results of several calculations of k eff on low-enriched uranium systems are provided to confirm the validity of the Hansen-Roach cross sections when applied to such systems. (Author)

The construction of radiation shielding for baby ebm

International Nuclear Information System (INIS)

Mohd Rizal Md Chulan; Leo Kwee Wah; Lee Chee Huei; Muhamad Zahidee Taat; Fadzlie Nordin; Abu Bakar Mhd Ghazali; Mohd Yusof Ali; Mohd Rizal Mamat Ibrahim; Syed Nasaruddin Syed Idris; Mahmud Hamid; Mohd Khairi Mohd Said

2005-01-01

The construction of radiation shielding for electron beam machine, Baby EBM is necessary for prevention from x-ray (Bremstrahlung) that produced when electron bombarded the target material. The strength of produced x-ray is depending on electron energy and the atomic number of target material. In the construction process of radiation shielding, a few aspects need to be considered such as shielding material and its thickness to be used, mainframe for radiation shielding and the way fabrication to be done. In this project, the thickness of radiation shielding is calculated manually following the NCRP 51 guidelines whereas for frame design, shielding walls and fabrication is considered that the accelerator devices (accelerating tube, focusing device and neck) is vertically and the whole weight of Baby EBM. From the calculations, the thickness and the material for radiation shielding is to be used are 6mm lead. This radiation shielding has been tested (using the parameters that have been considered) to know the leak of radiation (at all surfaces) and direct radiation below 5 cm from the window. The value of high voltage that applied at accelerating tube is 80 kV and the voltage, current supply at electron gun is 3.0 V, 7.1 A respectively. The result of the testing found that dose rate under the window foil is more than 2000 mSv/hr and at all shielding surfaces are less than 0.5 mSv/hr, which is background reading and this is acceptable as compared to the theoretical calculation. The measurement was done using a survey meter typed Ludlum-model 3. (Author)

Determination of effective resonance energies for the (n,γ) reactions of 152Sm and 165Ho by using dual monitors

International Nuclear Information System (INIS)

Budak, M.G.; Karadag, M.; Yuecel, H.

2010-01-01

The effective resonance energies E - bar r for the (n,γ) reactions of 152 Sm and 165 Ho isotopes were determined by using dual monitors ( 55 Mn- 98 Mo) due to their favourable resonance properties. The samples were irradiated in an isotropic neutron field obtained from 241 Am-Be neutron sources. The induced activities were measured with a high efficient, p-type Ge detector. The necessary correction factors for thermal neutron self-shielding (G th ), resonance neutron self-shielding (G epi ), self absorption (F s ) and true coincidence summing (F coi ) effects for the measured γ-rays were taken into account. Thus, the experimental E - bar r -values for above (n,γ) reactions are found to be 8.65 ± 1.80 eV for 152 Sm and 12.90 ± 2.69 eV for 165 Ho isotopes, respectively. The E - bar r -values for both 152 Sm and 165 Ho isotopes were also theoretically calculated from the newest resonance data in the literature. Theoretically calculated E - bar r -values are estimated to be 8.34 eV and 8.53 eV for 152 Sm by two different approaches, which are generally, much smaller than that the present experimental value by 1.4-3.6% for 152 Sm. In case of 165 Ho isotope, the theoretically calculated E - bar r -value of 8.63 eV from the first approach deviates substantially from the measured value by about 33%, whereas the theoretical E - bar r -value of 12.95 eV from the second approach agrees very well with our experimentally determined E - bar r -value. The results show that the present experimental E - bar r -values for 152 Sm and 165 Ho isotopes agree with the calculated ones from the second approach within limits of the estimated uncertainty if the recently evaluated resonance data are used. However, it is worth noting that the results for E - bar r -value calculated from the first approach are not satisfactorily accurate because of neglecting the neutron widths in that approach. Therefore, this study implies that it be regarded to the experimentally determined E - bar r

Self-esteem and alcohol dependence as predictors of contemplation ...

African Journals Online (AJOL)

PROMOTING ACCESS TO AFRICAN RESEARCH ... Self-esteem was measured by Rosenberg's self-esteem scale, and alcohol dependence was ... Binary logistic regression analysis revealed that an increase in self-esteem decreased the ...

Thyroid shields and neck exposures in cephalometric radiography

International Nuclear Information System (INIS)

Hujoel, Philippe; Hollender, Lars; Bollen, Anne-Marie; Young, John D; Cunha-Cruz, Joana; McGee, Molly; Grosso, Alex

2006-01-01

The thyroid is among the more radiosensitive organs in the body. The goal of this study was twofold: (1) to evaluate age-related changes in what is exposed to ionizing radiation in the neck area, and (2) to assess thyroid shield presence in cephalometric radiographs Cephalometric radiographs at one academic setting were sampled and neck exposure was related to calendar year and patient's gender and age. In the absence of shields, children have more vertebrae exposed than adults (p < 0.0001) and females have more neck tissue exposed inferior to the hyoid bone than males (p < 0.0001). The hyoid bone-porion distance increased with age (p <0.01). Thyroid shields were visible in 19% of the radiographs and depended strongly on the calendar year during which patient was seen (p-value <0.0001). Compared to adults, children were less likely to wear thyroid shields, particularly between 1973 and 1990 (1.8% versus 7.3% – p-value < 0.05) and between 2001 and 2003 (7.1% versus 42.9% – p-value < 0.05). In the absence of a thyroid shield, children have more neck structure exposed to radiation than adults. In agreement with other reports, thyroid shield utilization in this study was low, particularly in children

Shielding calculations using FLUKA

International Nuclear Information System (INIS)

Yamaguchi, Chiri; Tesch, K.; Dinter, H.

1988-06-01

The dose equivalent on the surface of concrete shielding has been calculated using the Monte Carlo code FLUKA86 for incident proton energies from 10 to 800 GeV. The results have been compared with some simple equations. The value of the angular dependent parameter in Moyer's equation has been calculated from the locations where the values of the maximum dose equivalent occur. (author)

Electromagnetic shielding formulae

International Nuclear Information System (INIS)

Dahlberg, E.

1979-02-01

This addendum to an earlier collection of electromagnetic shielding formulae (TRITA-EPP-75-27) contains simple transfer matrices suitable for calculating the quasistatic shielding efficiency for multiple transverse-field and axial-field cylindrical and spherical shields, as well as for estimating leakage fields from long coaxial cables and the normal-incidence transmission of a plane wave through a multiple plane shield. The differences and similarities between these cases are illustrated by means of equivalent circuits and transmission line analogies. The addendum also includes a discussion of a possible heuristic improvement of some shielding formulae. (author)

An assessment of the lifetime of Faraday shield elements

International Nuclear Information System (INIS)

Caughman, J.B.O. II; Ruzic, D.N.; Hoffman, D.J.; Langley, R.A.; Lewis, M.B.; Ryan, P.M.

1989-01-01

The interaction of plasma with rf fields from an ion cyclotron range of frequencies (ICRF) antenna has been studied to estimate the amount of Faraday shield erosion expected in normal ICRF heating (ICRH) operation. Plasma parameters and ion energies have been measured in the near field of an antenna and used in a model to estimate the erosion rate of the Faraday shield surface. Experiments were conducted on the RF Test Facility (RFTF), a magnetic mirror device at Oak Ridge National Laboratory (ORNL), using a single-strap resonant loop antenna with a two-tier Faraday shield. The outer tier, facing the plasma, was layered with graphite tiles. The antenna was operated at currents and voltages (∼500 A, ∼20 kV at 25 kW) within 50% of those expected in tokamaks. The time varying floating potential was measured with a capacitively coupled probe, and the time-averaged floating potential, electron temperature, and electron density were measured with a Langmuir probe. Both probes were scanned in front of the antenna. Ion energies were measured with a gridded energy analyzer located below the antenna, and samples of silicon were placed on the Faraday shield surface to estimate the incident ion energy. The capacitive probe measurements show that the rf floating potential follows the magnetic field pattern of the antenna, indicating that the electromagnetic fields are responsible for the potential formation. Plasma parameters and ion energies have been correlated with the antenna current and used in s computational model of the plasma sheath to predict the amount of erosion expected from the Faraday shield elements exposed to plasma. Predictions of light ion sputtering of candidate Faraday shield materials are presented. 19 refs., 6 figs., 1 tab

Verification of the accuracy of Doppler broadened, self-shielded multigroup cross sections for fast power reactor applications

International Nuclear Information System (INIS)

Ganesan, S.; Gopalakrishnan, V.; Ramanadhan, M.M.; Cullen, D.E.

1988-01-01

Verification results for Doppler broadening and self-shielding are presented. One of the important results presented is that the original SIGMA1 method of numerical Doppler broadening has now been demonstrated to be inaccurate and not capable of producing results to within required accuracies. Fortunately, due to this study, the SIGMA1 method has been significantly improved and the new SIGMA1 is now capable of producing results to within required accuracies. Although this paper presents results based upon using only one code system, it is important to realize that the original SIGMA1 method is presently used in many cross-section processing code systems; the results of this paper indicate that unless these other code systems are updated to include the new SIGMA1 method, the results produced by these code systems could be very inaccurate. The objectives of the IAEA nuclear data processing code verification project are reviewed as well as the requirements for the accuracy of calculation of Doppler coefficients and the present status of these calculations. The initial results of Doppler broadening and self-shielding calculations are presented and the inconsistency of the results which led to the discovery of errors in the original SIGMA1 method of Doppler broadening are pointed out. Analysis of the errors found and improvements in the SIGMA1 method are presented. Improved results are presented in order to demonstrate that the new SIGMA1 method can produce results within required accuracies. Guidelines are presented to limit the uncertainty introduced due to cross-section processing in order to balance available computer resources to accuracy requirements. Finally cross-section processing code users are invited to participate in the IAEA processing code verification project in order to verify the accuracy of their calculated results. (author)

SWANS: A Prototypic SCALE Criticality Sequence for Automated Optimization Using the SWAN Methodology

International Nuclear Information System (INIS)

Greenspan, E.

2001-01-01

SWANS is a new prototypic analysis sequence that provides an intelligent, semi-automatic search for the maximum k eff of a given amount of specified fissile material, or of the minimum critical mass. It combines the optimization strategy of the SWAN code with the composition-dependent resonance self-shielded cross sections of the SCALE package. For a given system composition arrived at during the iterative optimization process, the value of k eff is as accurate and reliable as obtained using the CSAS1X Sequence of SCALE-4.4. This report describes how SWAN is integrated within the SCALE system to form the new prototypic optimization sequence, describes the optimization procedure, provides a user guide for SWANS, and illustrates its application to five different types of problems. In addition, the report illustrates that resonance self-shielding might have a significant effect on the maximum k eff value a given fissile material mass can have

SWANS: A Prototypic SCALE Criticality Sequence for Automated Optimization Using the SWAN Methodology

Energy Technology Data Exchange (ETDEWEB)

Greenspan, E.

2001-01-11

SWANS is a new prototypic analysis sequence that provides an intelligent, semi-automatic search for the maximum k{sub eff} of a given amount of specified fissile material, or of the minimum critical mass. It combines the optimization strategy of the SWAN code with the composition-dependent resonance self-shielded cross sections of the SCALE package. For a given system composition arrived at during the iterative optimization process, the value of k{sub eff} is as accurate and reliable as obtained using the CSAS1X Sequence of SCALE-4.4. This report describes how SWAN is integrated within the SCALE system to form the new prototypic optimization sequence, describes the optimization procedure, provides a user guide for SWANS, and illustrates its application to five different types of problems. In addition, the report illustrates that resonance self-shielding might have a significant effect on the maximum k{sub eff} value a given fissile material mass can have.

Micro-machined resonator oscillator

Science.gov (United States)

Koehler, Dale R.; Sniegowski, Jeffry J.; Bivens, Hugh M.; Wessendorf, Kurt O.

1994-01-01

A micro-miniature resonator-oscillator is disclosed. Due to the miniaturization of the resonator-oscillator, oscillation frequencies of one MHz and higher are utilized. A thickness-mode quartz resonator housed in a micro-machined silicon package and operated as a "telemetered sensor beacon" that is, a digital, self-powered, remote, parameter measuring-transmitter in the FM-band. The resonator design uses trapped energy principles and temperature dependence methodology through crystal orientation control, with operation in the 20-100 MHz range. High volume batch-processing manufacturing is utilized, with package and resonator assembly at the wafer level. Unique design features include squeeze-film damping for robust vibration and shock performance, capacitive coupling through micro-machined diaphragms allowing resonator excitation at the package exterior, circuit integration and extremely small (0.1 in. square) dimensioning. A family of micro-miniature sensor beacons is also disclosed with widespread applications as bio-medical sensors, vehicle status monitors and high-volume animal identification and health sensors. The sensor family allows measurement of temperatures, chemicals, acceleration and pressure. A microphone and clock realization is also available.

Magnetic resonance described in the excitation dependent rotating frame of reference.

Science.gov (United States)

Tahayori, Bahman; Johnston, Leigh A; Mareels, Iven M Y; Farrell, Peter M

2008-01-01

An excitation dependent rotating frame of reference to observe the magnetic resonance phenomenon is introduced in this paper that, to the best of our knowledge, has not been used previously in the nuclear magnetic resonance context. The mathematical framework for this new rotating frame of reference is presented based on time scaling the Bloch equation after transformation to the classical rotating frame of reference whose transverse plane is rotating at the Larmor frequency. To this end, the Bloch equation is rewritten in terms of a magnetisation vector observed from the excitation dependent rotating frame of reference. The resultant Bloch equation is referred to as the time scaled Bloch equation. In the excitation dependent rotating frame of reference whose coordinates are rotating at the instantaneous Rabi frequency the observed magnetisation vector is a much slower signal than the true magnetisation in the rotating frame of reference. As a result the ordinary differential equation solvers have the ability to solve the time scaled version of the Bloch equation with a larger step size resulting in a smaller number of samples for solving the equation to a desired level of accuracy. The simulation results for different types of excitation are presented in this paper. This method may be used in true Bloch simulators in order to reduce the simulation time or increase the accuracy of the numerical solution. Moreover, the time scaled Bloch equation may be employed to determine the optimal excitation pattern in magnetic resonance imaging as well as designing pulses with better slice selectivity which is an active area of research in this field.

Shielding member for thermonuclear device

Energy Technology Data Exchange (ETDEWEB)

Onozuka, Masanori

1997-06-30

In a thermonuclear device for shielding fast neutrons by shielding members disposed in a shielding vessel (vacuum vessel and structures such as a blanket disposed in the vacuum vessel), the shielding member comprises a large number of shielding wires formed fine and short so as to have elasticity. The shielding wires are sealed in a shielding vessel together with water, and when the width of the shielding vessel is changed, the shielding wires follow after the change of the width while elastically deforming in the shielding vessel, so that great stress and deformation are not formed thereby enabling to improve reliability. In addition, the length, the diameter and the shape of each of the shielding wires can be selected in accordance with the shielding space of the shielding vessel. Even if the shape of the shielding vessel is complicated, the shielding wires can be inserted easily. Accordingly, the filling rate of the shielding members can be changed easily. It can be produced more easily compared with a conventional spherical pebbles. It can be produced more easily than existent spherical shielding pebbles thereby enabling to reduce the production cost. (N.H.)

Control of recoil losses in nanomechanical SiN membrane resonators

Science.gov (United States)

Borrielli, A.; Marconi, L.; Marin, F.; Marino, F.; Morana, B.; Pandraud, G.; Pontin, A.; Prodi, G. A.; Sarro, P. M.; Serra, E.; Bonaldi, M.

2016-09-01

In the context of a recoil damping analysis, we have designed and produced a membrane resonator equipped with a specific on-chip structure working as a "loss shield" for a circular membrane. In this device the vibrations of the membrane, with a quality factor of 107, reach the limit set by the intrinsic dissipation in silicon nitride, for all the modes and regardless of the modal shape, also at low frequency. Guided by our theoretical model of the loss shield, we describe the design rationale of the device, which can be used as effective replacement of commercial membrane resonators in advanced optomechanical setups, also at cryogenic temperatures.

Hollow Microtube Resonators via Silicon Self-Assembly toward Subattogram Mass Sensing Applications.

Science.gov (United States)

Kim, Joohyun; Song, Jungki; Kim, Kwangseok; Kim, Seokbeom; Song, Jihwan; Kim, Namsu; Khan, M Faheem; Zhang, Linan; Sader, John E; Park, Keunhan; Kim, Dongchoul; Thundat, Thomas; Lee, Jungchul

2016-03-09

Fluidic resonators with integrated microchannels (hollow resonators) are attractive for mass, density, and volume measurements of single micro/nanoparticles and cells, yet their widespread use is limited by the complexity of their fabrication. Here we report a simple and cost-effective approach for fabricating hollow microtube resonators. A prestructured silicon wafer is annealed at high temperature under a controlled atmosphere to form self-assembled buried cavities. The interiors of these cavities are oxidized to produce thin oxide tubes, following which the surrounding silicon material is selectively etched away to suspend the oxide tubes. This simple three-step process easily produces hollow microtube resonators. We report another innovation in the capping glass wafer where we integrate fluidic access channels and getter materials along with residual gas suction channels. Combined together, only five photolithographic steps and one bonding step are required to fabricate vacuum-packaged hollow microtube resonators that exhibit quality factors as high as ∼ 13,000. We take one step further to explore additionally attractive features including the ability to tune the device responsivity, changing the resonator material, and scaling down the resonator size. The resonator wall thickness of ∼ 120 nm and the channel hydraulic diameter of ∼ 60 nm are demonstrated solely by conventional microfabrication approaches. The unique characteristics of this new fabrication process facilitate the widespread use of hollow microtube resonators, their translation between diverse research fields, and the production of commercially viable devices.

The Effect of Consolidation on TBM Shield Loading in Water-Bearing Squeezing Ground

Science.gov (United States)

Ramoni, M.; Anagnostou, G.

2011-01-01

Jamming or overstressing of the shield due to ground pressure are potential problems for tunnel boring machine (TBM) tunnelling in squeezing ground. The risk of shield jamming depends essentially on the deformation rate of the ground in the vicinity of the working face. The time-dependency of the ground response to the excavation is associated with its rheological properties as well as with the transient consolidation process that takes place around the opening in the case of a low-permeability saturated ground. The present paper focuses on the second mechanism and investigates the interaction between the advancing shield, tunnel lining and consolidating ground by means of transient numerical analyses. For a given set of geotechnical conditions and a given TBM configuration, the load exerted by the ground upon the shield during TBM operation decreases with increasing gross advance rate. During a long break in operations, the ground pressure may increase significantly, thereby necessitating a higher thrust force to overcome shield skin friction and restart the TBM. It is interesting to note that a high advance rate reduces the risk of shield jamming not only during TBM advance, but is also favourable with respect to any subsequent long standstills.

Competitive resonance interference models in direct whole core transport code nTRACER

Energy Technology Data Exchange (ETDEWEB)

Bacha, Meer; Joo, Han Gyu [Seoul National Univ., Seoul (Korea, Republic of)

2015-05-15

The capability of nTRACER was enhanced with WIMS IAEA library using the equivalence theory and Dancoff correction method based on the resonance integral data. The background XSs, for the heterogeneous system, incorporating the shadowing effects, are evaluated by the enhanced neutron current method. The effective XSs are generated using the Resonance Integral (RI) data by interpolating for background XSs and temperatures. The conventional method, which augments the background XS with average absorption XSs of all other resonant isotopes in the mixture, is used for treating the resonance interference in mixed resonant absorbers. A lot of methods are being developed for the resonance self-shielding in mixed absorbers, but still there exists some inadequacy in the XSs evaluation. The most accurate method is solving the UFG slowing down equation, but at the cost of huge computational burden. On the other hand, the conventional method is the simplest and easy to implement, but it has drawback, that it can't correctly estimate the cross sections in mixed absorbers because it adds the absorption XS. The resonance interference treatment methods are studied and implemented in nTRACER and checked the capacity to improve the overlap effects for multiple resonant isotopes. In XST method, the XSs are improved a lot as compared to conventional method, but still there exists discrepancy in the lower energy range. This method is very fast having no burden during execution.

Resonant vibrations of self-interstitials in fcc metals with application to specific heat and neutron scattering

International Nuclear Information System (INIS)

Ram, P.N.; Dederichs, P.H.

1981-07-01

Some aspects of resonant vibrations of self-interstitials in the 100-dumbbell configuration in fcc-metals are discussed by extending previous calculations of Zeller et al. and Schober et al. Employing a simple defect model with nearest-neighbour interaction the local frequency spectrum of the defect is calculated showing several localized modes and low-frequency resonant modes. The change in the total density of states due to the defects is expressed as the derivative of a generalized phase shift which is used to calculate the change in the lattic specific heat due to single interstitials. Inelastic neutron scattering away from the one-phonon lines is proposed as a method to observe the resonant modes induced by self-interstitials. The model calculation in Cu shows that the well defined resonant modes due to dumbbell vibrations have appreciable intensity and could presumably be detected in neutron scattering measurements. The effect of di-interstitials on the phonon dispersion in Al is also discussed. (orig./GSCH)

Self-Biased 215MHz Magnetoelectric NEMS Resonator for Ultra-Sensitive DC Magnetic Field Detection

Science.gov (United States)

Nan, Tianxiang; Hui, Yu; Rinaldi, Matteo; Sun, Nian X.

2013-06-01

High sensitivity magnetoelectric sensors with their electromechanical resonance frequencies electromechanical systems (NEMS) resonator with an electromechanical resonance frequency of 215 MHz based on an AlN/(FeGaB/Al2O3) × 10 magnetoelectric heterostructure for detecting DC magnetic fields. This magnetoelectric NEMS resonator showed a high quality factor of 735, and strong magnetoelectric coupling with a large voltage tunable sensitivity. The admittance of the magnetoelectric NEMS resonator was very sensitive to DC magnetic fields at its electromechanical resonance, which led to a new detection mechanism for ultra-sensitive self-biased RF NEMS magnetoelectric sensor with a low limit of detection of DC magnetic fields of ~300 picoTelsa. The magnetic/piezoelectric heterostructure based RF NEMS magnetoelectric sensor is compact, power efficient and readily integrated with CMOS technology, which represents a new class of ultra-sensitive magnetometers for DC and low frequency AC magnetic fields.

Functional dependence of resonant harmonics on nanomechanical parameters in dynamic mode atomic force microscopy.

Science.gov (United States)

Gramazio, Federico; Lorenzoni, Matteo; Pérez-Murano, Francesc; Rull Trinidad, Enrique; Staufer, Urs; Fraxedas, Jordi

2017-01-01

We present a combined theoretical and experimental study of the dependence of resonant higher harmonics of rectangular cantilevers of an atomic force microscope (AFM) as a function of relevant parameters such as the cantilever force constant, tip radius and free oscillation amplitude as well as the stiffness of the sample's surface. The simulations reveal a universal functional dependence of the amplitude of the 6th harmonic (in resonance with the 2nd flexural mode) on these parameters, which can be expressed in terms of a gun-shaped function. This analytical expression can be regarded as a practical tool for extracting qualitative information from AFM measurements and it can be extended to any resonant harmonics. The experiments confirm the predicted dependence in the explored 3-45 N/m force constant range and 2-345 GPa sample's stiffness range. For force constants around 25 N/m, the amplitude of the 6th harmonic exhibits the largest sensitivity for ultrasharp tips (tip radius below 10 nm) and polymers (Young's modulus below 20 GPa).

Weld metal microstructures of hardfacing deposits produced by self-shielded flux-cored arc welding

International Nuclear Information System (INIS)

Dumovic, M.; Monaghan, B.J.; Li, H.; Norrish, J.; Dunne, D.P.

2015-01-01

The molten pool weld produced during self-shielded flux-cored arc welding (SSFCAW) is protected from gas porosity arising from oxygen and nitrogen by reaction ('killing') of these gases by aluminium. However, residual Al can result in mixed micro-structures of δ-ferrite, martensite and bainite in hardfacing weld metals produced by SSFCAW and therefore, microstructural control can be an issue for hardfacing weld repair. The effect of the residual Al content on weld metal micro-structure has been examined using thermodynamic modeling and dilatometric analysis. It is concluded that the typical Al content of about 1 wt% promotes δ-ferrite formation at the expense of austenite and its martensitic/bainitic product phase(s), thereby compromising the wear resistance of the hardfacing deposit. This paper also demonstrates how the development of a Schaeffler-type diagram for predicting the weld metal micro-structure can provide guidance on weld filler metal design to produce the optimum microstructure for industrial hardfacing applications.

LOW-FREQUENCY MAGNETIC FIELD SHIELDING BY A CIRCULAR PASSIVE LOOP AND CLOSED SHELLS

Directory of Open Access Journals (Sweden)

V.S. Grinchenko

2016-05-01

Full Text Available Purpose. To analyze the shielding factors for a circular passive loop and conductive closed shells placed in a homogeneous low-frequency magnetic field. Methodology. We have obtained simplified expressions for the shielding factors for a circular passive loop and a thin spherical shell. In addition, we have developed the numerical model of a thin cubical shell in a magnetic field, which allows exploring its shielding characteristics. Results. We have obtained dependences of the shielding factors for passive loops and shells on the frequency of the external field. Analytically determined frequency of the external magnetic field, below which field shielding of a passive loop is expedient to use, above which it is advisable to use a shielding shell.

Why do mothers use nipple shields and how does this influence duration of exclusive breastfeeding?

DEFF Research Database (Denmark)

Kronborg, Hanne; Foverskov, Else; Nilsson, Ingrid

2017-01-01

with introducing nipple shields were lower- gestational age and birthweight. The use of nipple shields was furthermore found to be associated with a threefold increased risk of earlier cessation of exclusive breastfeeding: among primiparae odds ratio = 3.80 (confidence interval 2.61–5.53); among multiparae odds......The present study addressed the contentious discussions about the benefits and risks of nipple shield use. The objective was to explore self-reported reasons for using a nipple shield and examine associations pertaining to the mother, the infant and duration of breastfeeding. Data were collected...... breastfeeding period. Primiparae used nipple shields more often than multiparae, and early breastfeeding problems as well as background factors like lower age, education and higher body mass index were associated with a higher likelihood of using nipple shields. Characteristics of infants associated...

COMBINE7.1 - A Portable ENDF/B-VII.0 Based Neutron Spectrum and Cross-Section Generation Program

Energy Technology Data Exchange (ETDEWEB)

Woo Y. Yoon; David W. Nigg

2009-08-01

COMBINE7.1 is a FORTRAN 90 computer code that generates multigroup neutron constants for use in the deterministic diffusion and transport theory neutronics analysis. The cross-section database used by COMBINE7.1 is derived from the Evaluated Nuclear Data Files (ENDF/B-VII.0). The neutron energy range covered is from 20 MeV to 1.0E-5 eV. The Los Alamos National Laboratory NJOY code is used as the processing code to generate a 167 fine-group cross-section library in MATXS format for Bondarenko self-shielding treatment. Resolved resonance parameters are extracted from ENDF/B-VII.0 File 2 for a separate library to be used in an alternate Nordheim self-shielding treatment in the resolved resonance energy range. The equations solved for energy dependent neutron spectrum in the 167 fine-group structure are the B-3 or B-1 approximations to the transport equation. The fine group cross sections needed for the spectrum calculation are first prepared by Bondarenko self-shielding interpolation in terms of background cross section and temperature. The geometric lump effect, when present, is accounted for by augmenting the background cross section. Nordheim self-shielded fine group cross sections for a material having resolved resonance parameters overwrite correspondingly the existing self-shielded fine group cross sections when this option is used. The fine group cross sections in the thermal energy range are replaced by those self-shielded with the Amouyal/Benoist/Horowitz method in the three region geometry when this option is requested. COMBINE7.1 coalesces fine group cross sections into broad group macroscopic and microscopic constants. The coalescing is performed by utilizing fine-group fluxes and/or currents obtained by spectrum calculation as the weighting functions. The multigroup constant may be output in any of several standard formats including ANISN 14** free format, CCCC ISOTXS format, and AMPX working library format. ANISN-PC, a one-dimensional, discrete

COMBINE7.1 - A Portable ENDF/B-VII.0 Based Neutron Spectrum and Cross-Section Generation Program

International Nuclear Information System (INIS)

Yoon, Woo Y.; Nigg, David W.

2009-01-01

COMBINE7.1 is a FORTRAN 90 computer code that generates multigroup neutron constants for use in the deterministic diffusion and transport theory neutronics analysis. The cross-section database used by COMBINE7.1 is derived from the Evaluated Nuclear Data Files (ENDF/B-VII.0). The neutron energy range covered is from 20 MeV to 1.0E-5 eV. The Los Alamos National Laboratory NJOY code is used as the processing code to generate a 167 fine-group cross-section library in MATXS format for Bondarenko self-shielding treatment. Resolved resonance parameters are extracted from ENDF/B-VII.0 File 2 for a separate library to be used in an alternate Nordheim self-shielding treatment in the resolved resonance energy range. The equations solved for energy dependent neutron spectrum in the 167 fine-group structure are the B-3 or B-1 approximations to the transport equation. The fine group cross sections needed for the spectrum calculation are first prepared by Bondarenko self-shielding interpolation in terms of background cross section and temperature. The geometric lump effect, when present, is accounted for by augmenting the background cross section. Nordheim self-shielded fine group cross sections for a material having resolved resonance parameters overwrite correspondingly the existing self-shielded fine group cross sections when this option is used. The fine group cross sections in the thermal energy range are replaced by those self-shielded with the Amouyal/Benoist/Horowitz method in the three region geometry when this option is requested. COMBINE7.1 coalesces fine group cross sections into broad group macroscopic and microscopic constants. The coalescing is performed by utilizing fine-group fluxes and/or currents obtained by spectrum calculation as the weighting functions. The multigroup constant may be output in any of several standard formats including ANISN 14** free format, CCCC ISOTXS format, and AMPX working library format. ANISN-PC, a one-dimensional, discrete

A contribution to shielding effectiveness analysis of shielded tents

Directory of Open Access Journals (Sweden)

Vranić Zoran M.

2004-01-01

Full Text Available An analysis of shielding effectiveness (SE of the shielded tents made of the metallised fabrics is given. First, two electromagnetic characteristic fundamental for coupling through electrically thin shield, the skin depth break frequency and the surface resistance or transfer impedance, is defined and analyzed. Then, the transfer function and the SE are analyzed regarding to the frequency range of interest to the Electromagnetic Compatibility (EMC Community.

Neutronics benchmarks of mixed-oxide fuels using the SCALE/CENTRM sequence

International Nuclear Information System (INIS)

Hollenbach, D.F.; Fox, P.B.

2000-01-01

The purpose of this study is to determine and document the reactor physics parameters (multiplication factors, spatially dependent flux ratios, and spacially dependent reaction rates ) for several distinct sets of problems using two distinct resonance cross-section processing techniques. In SCALE, by default, resonances are processed using NITAWL, which utilizes the Nordheim Integral Treatment. The results produced using this sequence are considered to be the base results. A second set of results are produced by replacing NITAWL with CENTRM/PMC. CENTRM produces point-wise fluxes for a given geometry configuration and set of isotopes. Using these fluxes, PMC produces problem-dependent self-shielding cross sections. Both sequences use ENDF/B-V cross-section data

Transparent fast neutron shielding material and shielding method

International Nuclear Information System (INIS)

Nashimoto, Tetsuji; Katase, Haruhisa.

1993-01-01

Polyisobutylene having a viscosity average molecular weight of 20,000 to 80,000 and a hydrogen atom density of greater than 7.0 x 10 22 /cm 3 is used as a fast neutron shielding material. The shielding material is excellent in the shielding performance against fast neutrons, and there is no worry of leakage even when holes should be formed to a vessel. Further, it is excellent in fabricability, relatively safe even upon occurrence of fire and, in addition, it is transparent to enable to observe contents easily. (T.M.)

Field angle dependence of voltage-induced ferromagnetic resonance under DC bias voltage

International Nuclear Information System (INIS)

Shiota, Yoichi; Miwa, Shinji; Tamaru, Shingo; Nozaki, Takayuki; Kubota, Hitoshi; Fukushima, Akio; Suzuki, Yoshishige; Yuasa, Shinji

2016-01-01

We studied the rectification function of microwaves in CoFeB/MgO-based magnetic tunnel junctions using voltage-induced ferromagnetic resonance (FMR). Our findings reveal that the shape of the structure of the spectrum depends on the rotation angle of the external magnetic field, providing clear evidence that FMR dynamics are excited by voltage-induced magnetic anisotropy changes. Further, enhancement of the rectified voltage was demonstrated under a DC bias voltage. In our experiments, the highest microwave detection sensitivity obtained was 350 mV/mW, at an RF frequency of 1.0 GHz and field angle of θ_H=80°, ϕ_H=0°. The experimental results correlated with those obtained via simulation, and the calculated results revealed the magnetization dynamics at the resonance state. - Highlights: • Examined voltage-induced ferromagnetic resonance (FMR) under various field angles. • FMR dynamics are excited by voltage-induced magnetic anisotropy changes. • Microwave detection sensitivity depends on input RF and elevation angle. • Microwave detection sensitivity=350 mV/mW at RF=1.0 GHz, θ_H=80°, ϕ_H=0°.

Electromagnetically shielded building

Energy Technology Data Exchange (ETDEWEB)

Takahashi, T; Nakamura, M; Yabana, Y; Ishikawa, T; Nagata, K

1992-04-21

This invention relates to a building having an electromagnetic shield structure well-suited for application to an information network system utilizing electromagnetic waves, and more particularly to an electromagnetically shielded building for enhancing the electromagnetic shielding performance of an external wall. 6 figs.

Electromagnetically shielded building

International Nuclear Information System (INIS)

Takahashi, T.; Nakamura, M.; Yabana, Y.; Ishikawa, T.; Nagata, K.

1992-01-01

This invention relates to a building having an electromagnetic shield structure well-suited for application to an information network system utilizing electromagnetic waves, and more particularly to an electromagnetically shielded building for enhancing the electromagnetic shielding performance of an external wall. 6 figs

Achieving Optimal Self-Adaptivity for Dynamic Tuning of Organic Semiconductors through Resonance Engineering.

Science.gov (United States)

Tao, Ye; Xu, Lijia; Zhang, Zhen; Chen, Runfeng; Li, Huanhuan; Xu, Hui; Zheng, Chao; Huang, Wei

2016-08-03

Current static-state explorations of organic semiconductors for optimal material properties and device performance are hindered by limited insights into the dynamically changed molecular states and charge transport and energy transfer processes upon device operation. Here, we propose a simple yet successful strategy, resonance variation-based dynamic adaptation (RVDA), to realize optimized self-adaptive properties in donor-resonance-acceptor molecules by engineering the resonance variation for dynamic tuning of organic semiconductors. Organic light-emitting diodes hosted by these RVDA materials exhibit remarkably high performance, with external quantum efficiencies up to 21.7% and favorable device stability. Our approach, which supports simultaneous realization of dynamically adapted and selectively enhanced properties via resonance engineering, illustrates a feasible design map for the preparation of smart organic semiconductors capable of dynamic structure and property modulations, promoting the studies of organic electronics from static to dynamic.

An assessment of the lifetime of Faraday shield elements

International Nuclear Information System (INIS)

Caughman, J.B.O. II; Ruzic, D.N.; Hoffman, D.J.; Langley, R.A.; Lewis, M.B.; Ryan, P.M.

1989-01-01

The interaction of plasma with rf fields from an ion cyclotron range of frequencies (ICRF) antenna has been studied to estimate the amount of Faraday shield erosion expected in normal ICRF heating operation. Plasma parameters and ion energies have been measured in the near field of an antenna and used in a model to estimate the erosion rate of the Faraday shield surface. Experiments were conducted on the RF Test Facility, a magnetic mirror device at Oak Ridge National Laboratory, using a single-strap resonant loop antenna with a two-tier Faraday shield. The outer tier, facing the plasma, was layered with graphite tiles. The antenna was operated at currents and voltages within 50% of those expected in tokamaks. The time-varying floating potential was measured with a capacitively coupled probe, and the time-averaged floating potential, electron temperature, and electron density were measured with Langmuir probe. Both probes were scanned in front of the antenna. Ion energies were measured with a gridded energy analyzer located below the antenna, and samples of silicon were placed on the Faraday shield surface to estimate the incident ion energy. The capacitive probe measurement show that the rf floating potential follows the magnetic field pattern of the antenna, indicating that the electromagnetic fields are responsible for the potential formation. Electron temperatures increase with rf power and can reach values ≥60 eV for an rf power of ∼25 kW. Incident ion energies ≥300 eV have been measured for the same power level. Predictions of light ion sputtering of candidate Faraday shield materials are presented. 19 refs., 6 figs., 1 tab

Radiation shielding concrete

International Nuclear Information System (INIS)

Kunishima, Shigeru.

1990-01-01

The radiation shielding concretes comprise water, cement, fine aggregates consisting of serpentines and blown mist slags, coarse aggregates consisting of serpentines and kneading materials. Since serpentines containing a relatively great amount of water of crystallization in rocks as coarse aggregates and fine aggregates, the hydrogen content in the radiation shielding concretes is increased and the neutron shielding effect is improved. In addition, since serpentines are added as the fine aggregates and blown mists slags of a great specific gravity are used, the specific gravity of the shielding concretes is increased to improve the γ-ray shielding effect. Further, by the use of the kneading material having a water reducing effect and fluidizing effect, and by the bearing effect of the spherical blown mist slags used as the fine aggregates, concrete fluidity can be increased. Accordingly, workability of the radiation shielding concretes can be improved. (T.M.)

Comparison of calculational methods for liquid metal reactor shields

International Nuclear Information System (INIS)

Carter, L.L.; Moore, F.S.; Morford, R.J.; Mann, F.M.

1985-09-01

A one-dimensional comparison is made between Monte Carlo (MCNP), discrete ordinances (ANISN), and diffusion theory (MlDX) calculations of neutron flux and radiation damage from the core of the Fast Flux Test Facility (FFTF) out to the reactor vessel. Diffusion theory was found to be reasonably accurate for the calculation of both total flux and radiation damage. However, for large distances from the core, the calculated flux at very high energies is low by an order of magnitude or more when the diffusion theory is used. Particular emphasis was placed in this study on the generation of multitable cross sections for use in discrete ordinates codes that are self-shielded, consistent with the self-shielding employed in the generation of cross sections for use with diffusion theory. The Monte Carlo calculation, with a pointwise representation of the cross sections, was used as the benchmark for determining the limitations of the other two calculational methods. 12 refs., 33 figs

Shielding augmentation of roll-on shield from NAPS to Kaiga-2

International Nuclear Information System (INIS)

Pradhan, A.S.; Kumar, A.N.

2000-01-01

Extensive radiation field surveys were conducted in NAPS and KAPS reactor buildings as a part of commissioning checks on radiation shielding. During such surveys, dose rate higher than the expected values were noticed in fuelling machine service areas. A movable shield, separating high field area fuelling machine vault and low field area fuelling machine service area, known as roll-on shield was identified as one of the causes of high field in fuelling machine service area along with weaker end-shield. This paper discusses systematic approach adopted in bringing down the dose rates in fuelling machine service area by augmentation of roll-on shield. (author)

γ-ray shielding behaviors of some nuclear engineering materials

International Nuclear Information System (INIS)

Mann, Kulwinder Singh

2017-01-01

The essential requirement of a material to be used for engineering purposes at nuclear establishments is its ability to attenuate the most penetrating ionizing radiations, gamma (γ)-rays. Mostly, high-Z materials such as heavy concrete, lead, mercury, and their mixtures or alloys have been used in the construction of nuclear establishments and thus termed as nuclear engineering materials (NEM). The NEM are classified into two categories, namely opaque and transparent, depending on their behavior towards the visible spectrum of EM waves. The majority of NEM are opaque. By contrast, various types of glass, which are transparent to visible light, are necessary at certain places in the nuclear establishments. In the present study, γ-ray shielding behaviors (GSB) of six glass samples (transparent NEM) were evaluated and compared with some opaque NEM in a wide range of energy (15 keV–15 MeV) and optical thickness (OT). The study was performed by computing various γ-ray shielding parameters (GSP) such as the mass attenuation coefficient, equivalent atomic number, and buildup factor. A self-designed and validated computer-program, the buildup factor-tool, was used for various computations. It has been established that some glass samples show good GSB, thus can safely be used in the construction of nuclear establishments in conjunction with the opaque NEM as well

γ-ray shielding behaviors of some nuclear engineering materials

Energy Technology Data Exchange (ETDEWEB)

Mann, Kulwinder Singh [Dept. of Physics, D.A.V. College, Punjab (India)

2017-06-15

The essential requirement of a material to be used for engineering purposes at nuclear establishments is its ability to attenuate the most penetrating ionizing radiations, gamma (γ)-rays. Mostly, high-Z materials such as heavy concrete, lead, mercury, and their mixtures or alloys have been used in the construction of nuclear establishments and thus termed as nuclear engineering materials (NEM). The NEM are classified into two categories, namely opaque and transparent, depending on their behavior towards the visible spectrum of EM waves. The majority of NEM are opaque. By contrast, various types of glass, which are transparent to visible light, are necessary at certain places in the nuclear establishments. In the present study, γ-ray shielding behaviors (GSB) of six glass samples (transparent NEM) were evaluated and compared with some opaque NEM in a wide range of energy (15 keV–15 MeV) and optical thickness (OT). The study was performed by computing various γ-ray shielding parameters (GSP) such as the mass attenuation coefficient, equivalent atomic number, and buildup factor. A self-designed and validated computer-program, the buildup factor-tool, was used for various computations. It has been established that some glass samples show good GSB, thus can safely be used in the construction of nuclear establishments in conjunction with the opaque NEM as well.

γ-Ray Shielding Behaviors of Some Nuclear Engineering Materials

Directory of Open Access Journals (Sweden)

Kulwinder Singh Mann

2017-06-01

Full Text Available The essential requirement of a material to be used for engineering purposes at nuclear establishments is its ability to attenuate the most penetrating ionizing radiations, gamma (γ-rays. Mostly, high-Z materials such as heavy concrete, lead, mercury, and their mixtures or alloys have been used in the construction of nuclear establishments and thus termed as nuclear engineering materials (NEM. The NEM are classified into two categories, namely opaque and transparent, depending on their behavior towards the visible spectrum of EM waves. The majority of NEM are opaque. By contrast, various types of glass, which are transparent to visible light, are necessary at certain places in the nuclear establishments. In the present study, γ-ray shielding behaviors (GSB of six glass samples (transparent NEM were evaluated and compared with some opaque NEM in a wide range of energy (15 keV–15 MeV and optical thickness (OT. The study was performed by computing various γ-ray shielding parameters (GSP such as the mass attenuation coefficient, equivalent atomic number, and buildup factor. A self-designed and validated computer-program, the buildup factor-tool, was used for various computations. It has been established that some glass samples show good GSB, thus can safely be used in the construction of nuclear establishments in conjunction with the opaque NEM as well.

Calculation of resonance integral for fuel cluster

International Nuclear Information System (INIS)

Remsak, S.

1969-01-01

The procedure for calculating the shielding correction, formulated in the previous paper [6], was broadened and applied for a cluster of cylindrical rods. The sam analytical method as in the previous paper was applied. A combination of Gauss method with the method of Almgren and Porn used for solving the same type of integral was used to calculate the geometry functions. CLUSTER code was written for ZUSE-Z-23 computer to calculate the shielding corrections for pairs of fuel rods in the cluster. Computing time for one pair of fuel rods depends on the number of closely placed rod, and for two closely placed rods it is about 3 hours. Calculations were done for clusters containing 7 and 19 UO 2 rods. results show that calculated values of resonance integrals are somewhat higher than the values obtained by Helstrand empirical formula. Taking into account the results for two rods from the previous paper it can be noted that the calculated and empirical values for clusters with 2 and 7 rods are in agreement since the deviations do not exceed the limits of experimental error (±2%). In case of larger cluster with 19 rods deviations are higher than the experimental error. Most probably the calculated values exceed the experimental ones result from the fact that in this paper the shielding correction is calculated only in the region up to 1 keV [sr

Temperature dependence of spreading width of giant dipole resonance

International Nuclear Information System (INIS)

Storozhenko, A.N.; Vdovin, A.I.; Ventura, A.; Blokhin, A.I.

2002-01-01

The Quasiparticle-Phonon Nuclear Model extended to finite temperature within the framework of Thermo Field Dynamics is applied to calculate a temperature dependence of the spreading width Γ ↓ of a giant dipole resonance. Numerical calculations are made for 120 Sn and 208 Pb nuclei. It is found that Γ ↓ increases with T. The reason of this effect is discussed as well as a relation of the present approach to other ones, existing in the literature

Gradient-induced longitudinal relaxation of hyperpolarized noble gases in the fringe fields of superconducting magnets used for magnetic resonance.

Science.gov (United States)

Zheng, Wangzhi; Cleveland, Zackary I; Möller, Harald E; Driehuys, Bastiaan

2011-02-01

When hyperpolarized noble gases are brought into the bore of a superconducting magnet for magnetic resonance imaging (MRI) or spectroscopy studies, the gases must pass through substantial field gradients, which can cause rapid longitudinal relaxation. In this communication, we present a means of calculating this spatially dependent relaxation rate in the fringe field of typical magnets. We then compare these predictions to experimental measurements of (3)He relaxation at various positions near a medium-bore 2-T small animal MRI system. The calculated and measured relaxation rates on the central axis of the magnet agree well and show a maximum (3)He relaxation rate of 3.83×10(-3) s(-1) (T(1)=4.4 min) at a distance of 47 cm from the magnet isocenter. We also show that if this magnet were self-shielded, its minimum T(1) would drop to 1.2 min. In contrast, a typical self-shielded 1.5-T clinical MRI scanner will induce a minimum on-axis T(1) of 12 min. Additionally, we show that the cylindrically symmetric fields of these magnets enable gradient-induced relaxation to be calculated using only knowledge of the on-axis longitudinal field, which can either be measured directly or calculated from a simple field model. Thus, while most MRI magnets employ complex and proprietary current configurations, we show that their fringe fields and the resulting gradient-induced relaxation are well approximated by simple solenoid models. Finally, our modeling also demonstrates that relaxation rates can increase by nearly an order of magnitude at radial distances equivalent to the solenoid radius. Copyright © 2010 Elsevier Inc. All rights reserved.

Energy-pointwise discrete ordinates transport methods

International Nuclear Information System (INIS)

Williams, M.L.; Asgari, M.; Tashakorri, R.

1997-01-01

A very brief description is given of a one-dimensional code, CENTRM, which computes a detailed, space-dependent flux spectrum in a pointwise-energy representation within the resolved resonance range. The code will become a component in the SCALE system to improve computation of self-shielded cross sections, thereby enhancing the accuracy of codes such as KENO. CENTRM uses discrete-ordinates transport theory with an arbitrary angular quadrature order and a Legendre expansion of scattering anisotropy for moderator materials and heavy nuclides. The CENTRM program provides capability to deterministically compute full energy range, space-dependent angular flux spectra, rigorously accounting for resonance fine-structure and scattering anisotropy effects

Influence of the Radiation Shield on the Temperature of Rails Rolled in the Reversing Mill

Directory of Open Access Journals (Sweden)

Gołdasz A.

2015-04-01

Full Text Available The paper presents a mathematical model of heat transfer during cooling of hot-rolled rails in the reversing mill. The influence of the radiation shield on the temperature of rolled rails has been analyzed. The heat transfer model for cooling a strip covered by the thermal shield has been presented. The two types of shields build of steel and aluminum sheets separated with insulating layer have been studded. Calculations have been performed with self developed software which utilizes the finite element method.

Exact invariants in the form of momentum resonances for particle motion in one-dimensional, time-dependent potentials

International Nuclear Information System (INIS)

Goedert, J.; Lewis, H.R.

1984-01-01

A momentum-resonance ansatz of Lewis and Leach was used to study exact invariants for time-dependent, one-dimensional potentials. This ansatz provides a framework for finding invariants admitted by a larger class of time-dependent potentials that was known previously. For a potential that admits an exact invariant in this resonance form, we have shown how to construct the invariant as a functional of the potential in terms of the solution of a definite linear algebraic system of equations. We have found a necessary and sufficient condition on the potential for the existence of an invariant with a given number of resonances. There exist more potentials that admit invariants with two resonances than were previously known and we have found an example in parametric form of such a potential. We have also found examples of potentials that admit invariants with three resonances

CSI-EPT in Presence of RF-Shield for MR-Coils.

Science.gov (United States)

Arduino, Alessandro; Zilberti, Luca; Chiampi, Mario; Bottauscio, Oriano

2017-07-01

Contrast source inversion electric properties tomography (CSI-EPT) is a recently developed technique for the electric properties tomography that recovers the electric properties distribution starting from measurements performed by magnetic resonance imaging scanners. This method is an optimal control approach based on the contrast source inversion technique, which distinguishes itself from other electric properties tomography techniques for its capability to recover also the local specific absorption rate distribution, essential for online dosimetry. Up to now, CSI-EPT has only been described in terms of integral equations, limiting its applicability to homogeneous unbounded background. In order to extend the method to the presence of a shield in the domain-as in the recurring case of shielded radio frequency coils-a more general formulation of CSI-EPT, based on a functional viewpoint, is introduced here. Two different implementations of CSI-EPT are proposed for a 2-D transverse magnetic model problem, one dealing with an unbounded domain and one considering the presence of a perfectly conductive shield. The two implementations are applied on the same virtual measurements obtained by numerically simulating a shielded radio frequency coil. The results are compared in terms of both electric properties recovery and local specific absorption rate estimate, in order to investigate the requirement of an accurate modeling of the underlying physical problem.

Towards Self-adaptation for Dependable Service-Oriented Systems

Science.gov (United States)

Cardellini, Valeria; Casalicchio, Emiliano; Grassi, Vincenzo; Lo Presti, Francesco; Mirandola, Raffaela

Increasingly complex information systems operating in dynamic environments ask for management policies able to deal intelligently and autonomously with problems and tasks. An attempt to deal with these aspects can be found in the Service-Oriented Architecture (SOA) paradigm that foresees the creation of business applications from independently developed services, where services and applications build up complex dependencies. Therefore the dependability of SOA systems strongly depends on their ability to self-manage and adapt themselves to cope with changes in the operating conditions and to meet the required dependability with a minimum of resources. In this paper we propose a model-based approach to the realization of self-adaptable SOA systems, aimed at the fulfillment of dependability requirements. Specifically, we provide a methodology driving the system adaptation and we discuss the architectural issues related to its implementation. To bring this approach to fruition, we developed a prototype tool and we show the results that can be achieved with a simple example.

Self consistent and covariant propagation of pions, nucleon and isobar resonances in cold nuclear matter

International Nuclear Information System (INIS)

Korpa, C.L.; Lutz, M.F.M.; Technische Univ. Darmstadt

2003-06-01

We evaluate the in-medium spectral functions for pions, nucleon and isobar resonances in a self consistent and covariant manner. The calculations are based on a recently developed formulation which leads to predictions in terms of the pion-nucleon scattering phase shifts and a set of Migdal parameters describing important short range correlation effects. We do not observe any significant softening of pion modes if we insist on reasonable isobar resonance properties but predict a considerable broadening of the N(1440) and N(1520) resonances in nuclear matter. (orig.)

Effects of Mo-doping on microstructure and near-infrared shielding performance of hydrothermally prepared tungsten bronzes

Energy Technology Data Exchange (ETDEWEB)

Wang, Qingjuan; Li, Can; Xu, Wenai; Zhao, Xiaolin; Zhu, Jingxin [Laboratory of Green Energy Materials and Storage Systems, College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Jiang, Haiwei, E-mail: tyjmx@163.com [Laboratory of Green Energy Materials and Storage Systems, College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Kang, Litao, E-mail: kangltxy@163.com [Laboratory of Green Energy Materials and Storage Systems, College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences (China); Zhao, Zhe [School of Materials Science & Engineering, Shanghai Institute of Technology, Shanghai 201418 (China)

2017-03-31

Highlights: • Mo-doped tungsten bronzes were hydrothermally synthesized at 80 °C. • Samples transformed from hexagonal to monoclinic structure with Mo-content increase. • 1.5% Mo-doped samples show the best near-infrared shielding performance. • High Mo-doping weakens localized surface plasmon resonance (LSPR) absorption and thus NIR shielding performance. • Small polaron absorption seems to be less affected by Mo-doping. - Abstract: Both Mo and W belong to VIB-sub-group, and possess similar ionic radii, electronegativity and oxide lattice configuration. Herein, Mo-doped (0–80 at.%) tungsten bronzes, M{sub x}WO{sub 3}, were hydrothermally prepared to systematically explore the influence of Mo-doping on their micro-structure and optical performance. The products adopted a hexagonal structure within 6 at.% Mo-doping, and transformed into a monoclinic phase with higher Mo-doping content. Further tests suggested that 1.5 at.% Mo-doping is beneficial for the formation of pure hexagonal phase and uniform nano-rod morphology. Optical measures showed that all samples exhibited high and comparable visible transmittance (70–80%), but a very different near infrared (NIR) shielding ability. The sample doped with 1.5 at.% Mo demonstrated the best NIR shielding ability with a transmittance minimum of 20% at 1300 nm. Further increase of Mo-doping dosage remarkably deteriorated NIR shielding ability by depressing the absorption of localized surface plasmon resonance (LSPR). However, the optical absorption from small-polaron was less influenced by the introduction of Mo. As a result, Mo-doping caused an evident blue shift of the infrared absorption peaks from 1350 to 750 nm.

Neutron and gamma-ray spectra measurement on the model of the KS-150 reactor radial shielding

International Nuclear Information System (INIS)

Holman, M.; Hogel, J.; Marik, J.; Kovarik, K.; Franc, L.; Vespalec, R.

1977-01-01

A shortened model of the peripheral region of the KS-150 reactor core consisting of two rows of fuel elements and a reflector was constructed from the peripheral fuel elements of the KS-150 reactor core in an experiment on the TR-0 reactor. The mockup of the thermal shield (10 cm of steel), the pressure vessel (15 cm of steel) and the inner wall of the water biological shielding (2 cm of steel) of the KS-150 reactor were erected outside the TR-0 vessel. Fast neutron and gamma spectra were measured with a stilbene crystal scintillation spectrometer. The resonance neutron spectra were measured with 197 Au, 63 Cu and 23 Na resonance activation detectors. Fast neutron spectra inside the reactor were measured with a 10 mm diameter by 10 mm thick stilbene crystal spectrometer, outside the reactor with a 10 mm diameter by 10 mm thick and a 20 mm diameter by 20 mm thick stilbene crystal spectrometer. Neutron spectra in the energy regions of 1 eV to 3 keV and 0.6 MeV to 0.8 MeV were obtained on the core periphery, on the reflector half-thickness and in front of and behind the reactor thermal shield. Gamma spectra were obtained in front of and behind the thermal shield. It was found that the attenuation of neutron fluxes by the reflector and the thermal shield increased with increasing energy while gamma radiation attenuation decreased with increasing energy. It was not possible to obtain the neutron spectrum in the 10 to 600 keV energy range because suitable detection instrumentation was not available. (J.P.)

Non-blinking quantum dot with a plasmonic nanoshell resonator

Science.gov (United States)

Ji, Botao; Giovanelli, Emerson; Habert, Benjamin; Spinicelli, Piernicola; Nasilowski, Michel; Xu, Xiangzhen; Lequeux, Nicolas; Hugonin, Jean-Paul; Marquier, Francois; Greffet, Jean-Jacques; Dubertret, Benoit

2015-02-01

Colloidal semiconductor quantum dots are fluorescent nanocrystals exhibiting exceptional optical properties, but their emission intensity strongly depends on their charging state and local environment. This leads to blinking at the single-particle level or even complete fluorescence quenching, and limits the applications of quantum dots as fluorescent particles. Here, we show that a single quantum dot encapsulated in a silica shell coated with a continuous gold nanoshell provides a system with a stable and Poissonian emission at room temperature that is preserved regardless of drastic changes in the local environment. This novel hybrid quantum dot/silica/gold structure behaves as a plasmonic resonator with a strong Purcell factor, in very good agreement with simulations. The gold nanoshell also acts as a shield that protects the quantum dot fluorescence and enhances its resistance to high-power photoexcitation or high-energy electron beams. This plasmonic fluorescent resonator opens the way to a new family of plasmonic nanoemitters with robust optical properties.

The shielding calculation for the CN guide shielding assembly in HANARO

International Nuclear Information System (INIS)

Kim, H. S.; Lee, B. C.; Lee, K. H.; Kim, H.

2006-01-01

The cold neutron research facility in HANARO is under construction. The area including neutron guides and rotary shutter in the reactor hall should be shielded by the guide shielding assembly which is constructed of heavy concrete blocks and structure. The guide shielding assembly is divided into 2 parts, A and B. Part A is about 6.4 meters apart from the reactor biological shield and it is constructed of heavy concrete blocks whose density is above 4.0g/cm 3 . And part B is a fixed heavy concrete structure whose density is above 3.5g/cm 3 . The rotary shutter is also made with heavy concrete whose density is above 4.0g/cm 3 and includes 5 neutron guides inside. It can block the neutron beam by rotating when CNS is not operating. The dose criterion outside the guide shielding assembly is established as 12.5 μSv/hr which is also applied to reactor shielding in HANARO

Shielding synchrotron light sources: Advantages of circular shield walls tunnels

Energy Technology Data Exchange (ETDEWEB)

Kramer, S.L. [Design and Accelerator Operations Consulting, 568 Wintergreen Ct Ridge, NY 11961 (United States); Ghosh, V.J.; Breitfeller, M. [NSLS-II, Brookhaven National Laboratory, Upton, NY 11973 (United States)

2016-08-11

Third generation high brightness light sources are designed to have low emittance and high current beams, which contribute to higher beam loss rates that will be compensated by Top-Off injection. Shielding for these higher loss rates will be critical to protect the projected higher occupancy factors for the users. Top-Off injection requires a full energy injector, which will demand greater consideration of the potential abnormal beam miss-steering and localized losses that could occur. The high energy electron injection beam produce significantly higher neutron component dose to the experimental floor than lower energy injection and ramped operations. High energy neutrons produced in the forward direction from thin target beam losses are a major component of the dose rate outside the shield walls of the tunnel. The convention has been to provide thicker 90° ratchet walls to reduce this dose to the beam line users. We present an alternate circular shield wall design, which naturally and cost effectively increases the path length for this forward radiation in the shield wall and thereby substantially decreasing the dose rate for these beam losses. This shield wall design will greatly reduce the dose rate to the users working near the front end optical components but will challenge the beam line designers to effectively utilize the longer length of beam line penetration in the shield wall. Additional advantages of the circular shield wall tunnel are that it's simpler to construct, allows greater access to the insertion devices and the upstream in tunnel beam line components, as well as reducing the volume of concrete and therefore the cost of the shield wall.

Application of wavelet scaling function expansion continuous-energy resonance calculation method to MOX fuel problem

International Nuclear Information System (INIS)

Yang, W.; Wu, H.; Cao, L.

2012-01-01

More and more MOX fuels are used in all over the world in the past several decades. Compared with UO 2 fuel, it contains some new features. For example, the neutron spectrum is harder and more resonance interference effects within the resonance energy range are introduced because of more resonant nuclides contained in the MOX fuel. In this paper, the wavelets scaling function expansion method is applied to study the resonance behavior of plutonium isotopes within MOX fuel. Wavelets scaling function expansion continuous-energy self-shielding method is developed recently. It has been validated and verified by comparison to Monte Carlo calculations. In this method, the continuous-energy cross-sections are utilized within resonance energy, which means that it's capable to solve problems with serious resonance interference effects without iteration calculations. Therefore, this method adapts to treat the MOX fuel resonance calculation problem natively. Furthermore, plutonium isotopes have fierce oscillations of total cross-section within thermal energy range, especially for 240 Pu and 242 Pu. To take thermal resonance effect of plutonium isotopes into consideration the wavelet scaling function expansion continuous-energy resonance calculation code WAVERESON is enhanced by applying the free gas scattering kernel to obtain the continuous-energy scattering source within thermal energy range (2.1 eV to 4.0 eV) contrasting against the resonance energy range in which the elastic scattering kernel is utilized. Finally, all of the calculation results of WAVERESON are compared with MCNP calculation. (authors)

Nuclear magnetic shielding tensors of 207Pb2+ in Pb(NO3)2

International Nuclear Information System (INIS)

Lutz, O.; Nolle, A.

1980-01-01

The NMR signals of 207 Pb were observed in a single crystal of Pb(NO 3 ) 2 and could be assigned to the four different Pb 2+ sites by the dependence of the linewidths on the orientation. Four different nuclear magnetic shielding tensors with equal principal values but with different characteristic vectors could be determined. The symmetry of the shielding tensors is in agreement with the symmetry at the Pb 2+ sites. It is shown, that intermolecular contributions can not account for the anisotropy of the nuclear magnetic shielding, which is 3 0 / 00 of the isotropic absolute magnetic shielding. (orig.)

RF MEMS Fractal Capacitors With High Self-Resonant Frequencies

KAUST Repository

Elshurafa, Amro M.

2012-07-23

This letter demonstrates RF microelectromechanical systems (MEMS) fractal capacitors possessing the highest reported self-resonant frequencies (SRFs) in PolyMUMPS to date. Explicitly, measurement results show SRFs beyond 20 GHz. Furthermore, quality factors higher than 4 throughout a band of 1-15 GHz and reaching as high as 28 were achieved. Additional benefits that are readily attainable from implementing fractal capacitors in MEMS are discussed, including suppressing residual stress warping, eliminating the need for etching holes, and reducing parasitics. The latter benefits were acquired without any fabrication intervention. © 2011 IEEE.

Brain magnetic resonance imaging with contrast dependent on blood oxygenation

International Nuclear Information System (INIS)

Ogawa, S.; Lee, T.M.; Kay, A.R.; Tank, D.W.

1990-01-01

Paramagnetic deoxyhemoglobin in venous blood is a naturally occurring contrast agent for magnetic resonance imaging (MRI). By accentuating the effects of this agent through the use of gradient-echo techniques in high yields, the authors demonstrate in vivo images of brain microvasculature with image contrast reflecting the blood oxygen level. This blood oxygenation level-dependent (BOLD) contrast follows blood oxygen changes induced by anesthetics, by insulin-induced hypoglycemia, and by inhaled gas mixtures that alter metabolic demand or blood flow. The results suggest that BOLD contrast can be used to provide in vivo real-time maps of blood oxygenation in the brain under normal physiological conditions. BOLD contrast adds an additional feature to magnetic resonance imaging and complement other techniques that are attempting to provide position emission tomography-like measurements related to regional neural activity

INTOR radiation shielding for personnel access

International Nuclear Information System (INIS)

Gohar, Y.; Abdou, M.

1981-01-01

The INTOR reactor shield system consists of the blanket, bulk shield, penetration shield, component shield, and biological shield. The bulk shield consists of two parts: (a) the inboard shield; and (b) the outboard shield. The distinction between the different components of the shield system is essential to satisfy the different design constraints and achieve various objectives

Hysteresis loops of spin-dependent electronic current in a paramagnetic resonant tunnelling diode

International Nuclear Information System (INIS)

Wójcik, P; Spisak, B J; Wołoszyn, M; Adamowski, J

2012-01-01

Nonlinear properties of the spin-dependent electronic transport through a semiconductor resonant tunnelling diode with a paramagnetic quantum well are considered. The spin-dependent Wigner–Poisson model of the electronic transport and the two-current Mott’s formula for the independent spin channels are applied to determine the current–voltage curves of the nanodevice. Two types of the electronic current hysteresis loops are found in the current–voltage characteristics for both the spin components of the electronic current. The physical interpretation of these two types of the electronic current hysteresis loops is given based on the analysis of the spin-dependent electron densities and the potential energy profiles. The differences between the current–voltage characteristics for both the spin components of the electronic current allow us to explore the changes of the spin polarization of the current for different electric fields and determine the influence of the electronic current hysteresis on the spin polarization of the current flowing through the paramagnetic resonant tunnelling diode. (paper)

Dependence of excitation frequency of resonant circuit on RF irradiation position of MRI equipment

International Nuclear Information System (INIS)

Shimizu, Masato; Yamada, Tsutomu; Takemura, Yasushi; Niwa, Touru; Inoue, Tomio

2010-01-01

Hyperthermia using implants is a cancer treatment in which cancer tissue is heated to over 42.5 deg C to selectively kill the cancer cells. In this study, a resonant circuit was used as an implant, and a weak magnetic field of radiofrequency (RF) pulses from a magnetic resonance imaging (MRI) device was used as an excitation source. We report here how the temperature of the resonant circuit was controlled by changing the excitation frequency of the MRI. As a result, the temperature rise of the resonant circuit was successfully found to depend on its position in the MRI device. This significant result indicates that the temperature of the resonant circuit can be controlled only by adjusting the excitation position. Accurate temperature control is therefore expected to be possible by combining this control technique with the temperature measurement function of MRI equipment. (author)

Design and Characterization of a Gradient-Transparent RF Copper Shield for PET Detector Modules in Hybrid MR-PET Imaging

Science.gov (United States)

Berneking, Arne; Trinchero, Riccardo; Ha, YongHyun; Finster, Felix; Cerello, Piergiorgio; Lerche, Christoph; Shah, Nadim Jon

2017-05-01

This paper focuses on the design and the characterization of a frequency-selective shield for positron emission tomography (PET) detector modules of hybrid magnetic resonance-PET scanners, where the shielding of the PET cassettes is located close to the observed object. The proposed shielding configuration is designed and optimized to guarantee a high shielding effectiveness (SE) of up to 60 dB for B1-fields at the Larmor frequency of 64 MHz, thus preventing interactions between the radio-frequency (RF) coil and PET electronics. On the other hand, the shield is transparent to the gradient fields with the consequence that eddy-current artifacts in the acquired EPI images are significantly reduced with respect to the standard solid-shield configuration. The frequency-selective behavior of the shield is characterized and validated via simulation studies with CST MICROWAVE STUDIO in the megahertz and kilohertz range. Bench measurements with an RF coil built in-house demonstrated the high SE at the Larmor frequency. Moreover, measurements on a 4-T human scanner confirmed the abolishment of eddy current artifact and also provided an understanding of where the eddy currents occur with respect to the sequence parameters. Simulations and measurements for the proposed shielding concept were compared with a solid copper shielding configuration.

Monitoring the hydration of DNA self-assembled monolayers using an extensional nanomechanical resonator

DEFF Research Database (Denmark)

Cagliani, Alberto; Kosaka, Priscila; Tamayo, Javier

2012-01-01

We have fabricated an ultrasensitive nanomechanical resonator based on the extensional vibration mode to weigh the adsorbed water on self-assembled monolayers of DNA as a function of the relative humidity. The water adsorption isotherms provide the number of adsorbed water molecules per nucleotid...

Evaluation of shielding parameters for heavy metal fluoride based tellurite-rich glasses for gamma ray shielding applications

International Nuclear Information System (INIS)

Sayyed, M.I.; Lakshminarayana, G.; Kityk, I.V.; Mahdi, M.A.

2017-01-01

In this work, we have evaluated the γ-ray shielding parameters such as mass attenuation coefficient (μ/ρ), effective atomic number (Z eff ), half value layer (HVL), mean free path (MFP) and exposure buildup factors (EBF) for heavy metal fluoride (PbF 2 ) based tellurite-rich glasses. In addition, neutron total macroscopic cross sections (∑ R ) for these glasses were also calculated. The maximum value for µ/ρ, Z eff and ∑ R was found for heavy metal (Bi 2 O 3 ) oxide introduced glass. The results of the selected glasses have been compared, in terms of MFP with different glass systems. The shielding effectiveness of the selected glasses is found comparable or better than of common ones, which indicates that these glasses with suitable oxides could be developed for gamma ray shielding applications. - Highlights: • μ/ρ, Z eff , HVL and MFP for PbF 2 based tellurite-rich glasses have been calculated. • µ/ρ and Z eff depend on the photon energy and chemical composition of the glasses. • EBF values of these glasses have been calculated using G-P fitting method. • The maximum value for µ/ρ and Z eff was found for Bi 2 O 3 oxide introduced glass. • New types of non-traditional radiation shielding glasses are demonstrated.

Computational methodology for the Oak Ridge Research Reactor (ORR) and Bulk Shielding Reactor (BSR): cross-section and validation. Volume 1

International Nuclear Information System (INIS)

Miller, L.F.; Williams, M.L.

1986-03-01

A neutronics library suitable for low-enrichment uranium (LEU) and high-enrichment uranium (HEU) fueled cores for both the Oak Ridge Research Reactor (ORR) and the Bulk Shielding Reactor (BSR) is documented herein. The library is obtained from version V of the Evaluated Nuclear Data File (ENDF/B-V) and contains 223 nuclides weighted over a variety of region-dependent neutron spectra. Self-shielding and zone-weighting effects are incorporated with 227-group calculations for several reactor-core configurations. Libraries are archived for both transport and diffusion theory seven-group calculations. Complete listings of processing details are included so that libraries with different specifications can be easily obtained. Results from validation calculations indicate that the neutronics libraries obtained from this effort are suitable for neutronics computations for the ORR and BSR. 12 refs., 5 figs., 15 tabs

Radiation shielding plate

International Nuclear Information System (INIS)

Kobayashi, Torakichi; Sugawara, Takeo.

1983-01-01

Purpose: To reduce the weight and stabilize the configuration of a radiation shielding plate which is used in close contact with an object to be irradiated with radiation rays. Constitution: The radiation shielding plate comprises a substrate made of lead glass and a metallic lead coating on the surface of the substrate by means of plating, vapor deposition or the like. Apertures for permeating radiation rays are formed to the radiation shielding plate. Since the shielding plate is based on a lead glass plate, a sufficient mechanical strength can be obtained with a thinner structure as compared with the conventional plate made of metallic lead. Accordingly, if the shielding plate is disposed on a soft object to be irradiated with radiation rays, the object and the plate itself less deform to obtain a radiation irradiation pattern with distinct edges. (Moriyama, K.)

A study of the electromagnetic shielding mechanisms in the GHz frequency range of graphene based composite layers

Energy Technology Data Exchange (ETDEWEB)

Drakakis, E. [Electrical Engineering Department, School of Engineering, Technological Educational Institute of Crete, Heraklion (Greece); Kymakis, E. [Electrical Engineering Department, School of Engineering, Technological Educational Institute of Crete, Heraklion (Greece); Center of Materials Technology and Photonics, School of Engineering, Technological Educational Institute of Crete, Heraklion (Greece); Tzagkarakis, G.; Louloudakis, D.; Katharakis, M. [Center of Materials Technology and Photonics, School of Engineering, Technological Educational Institute of Crete, Heraklion (Greece); Kenanakis, G. [Institute of Electronic Structure & Laser (IESL), Foundation for Research and Technology (FORTH) Hellas, Heraklion (Greece); Suchea, M.; Tudose, V. [Center of Materials Technology and Photonics, School of Engineering, Technological Educational Institute of Crete, Heraklion (Greece); Chemistry Faculty, “Al.I.Cuza” University of Iasi, Iasi (Romania); Koudoumas, E., E-mail: koudoumas@staff.teicrete.gr [Electrical Engineering Department, School of Engineering, Technological Educational Institute of Crete, Heraklion (Greece); Center of Materials Technology and Photonics, School of Engineering, Technological Educational Institute of Crete, Heraklion (Greece)

2017-03-15

Highlights: • Optimum paint contents should be chosen so that homogeneous and uniform nanocomposite layers exist exhibiting effective electromagnetic shielding. • The electromagnetic shielding in the frequency range studied comes mainly from absorption and increases with frequency. • Reflection reduces with increasing frequency, the decrease rate being smaller than that of the increase in absorption. • The shielding efficiency depends on both conductivity and thickness, the first dependence being more pronounced. - Abstract: We report on the mechanisms of the electromagnetic interference shielding effect of graphene based paint like composite layers. In particular, we studied the absorption and reflection of electromagnetic radiation in the 4–20 GHz frequency of various dispersions employing different amounts of graphene nanoplatelets, polyaniline, and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), special attention given on the relative contribution of each process in the shielding effect. Moreover, the influence of the composition, the thickness and the conductivity of the composite layers on the electromagnetic shielding was also examined.

A study of the electromagnetic shielding mechanisms in the GHz frequency range of graphene based composite layers

International Nuclear Information System (INIS)

Drakakis, E.; Kymakis, E.; Tzagkarakis, G.; Louloudakis, D.; Katharakis, M.; Kenanakis, G.; Suchea, M.; Tudose, V.; Koudoumas, E.

2017-01-01

Highlights: • Optimum paint contents should be chosen so that homogeneous and uniform nanocomposite layers exist exhibiting effective electromagnetic shielding. • The electromagnetic shielding in the frequency range studied comes mainly from absorption and increases with frequency. • Reflection reduces with increasing frequency, the decrease rate being smaller than that of the increase in absorption. • The shielding efficiency depends on both conductivity and thickness, the first dependence being more pronounced. - Abstract: We report on the mechanisms of the electromagnetic interference shielding effect of graphene based paint like composite layers. In particular, we studied the absorption and reflection of electromagnetic radiation in the 4–20 GHz frequency of various dispersions employing different amounts of graphene nanoplatelets, polyaniline, and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), special attention given on the relative contribution of each process in the shielding effect. Moreover, the influence of the composition, the thickness and the conductivity of the composite layers on the electromagnetic shielding was also examined.

Electromagnetic shield

International Nuclear Information System (INIS)

Miller, J.S.

1987-01-01

An electromagnetic shield is described comprising: closed, electrically-conductive rings, each having an open center; and binder means for arranging the rings in a predetermined, fixed relationship relative to each other, the so-arranged rings and binder means defining an outer surface; wherein electromagnetic energy received by the shield from a source adjacent its outer surface induces an electrical current to flow in a predetermined direction adjacent and parallel to the outer surface, through the rings; and wherein each ring is configured to cause source-induced alternating current flowing through the portion of the ring closest to the outer surface to electromagnetically induce an oppositely-directed current in the portion of the ring furthest from the surface, such oppositely-directed current bucking any source-induced current in the latter ring portion and thus reducing the magnitude of current flowing through it, whereby the electromagnetic shielding effected by the shield is enhanced

Status of multigroup cross-section data for shielding applications

International Nuclear Information System (INIS)

Roussin, R.W.; Maskewitz, B.F.; Trubey, D.K.

1983-01-01

Multigroup cross-section libraries for shielding applications in formats for direct use in discrete ordinates or Monte Carlo codes have long been a part of the Data Library Collection (DLC) of the Radiation Shielding Information Center (RSIC). In recent years libraries in more flexible and comprehensive formats, which allow the user to derive his own problem-dependent sets, have been added to the collection. The current status of both types is described, as well as projections for adding data libraries based on ENDF/B-V

News from the Library: Facilitating access to a program for radiation shielding - the Library can help

CERN Multimedia

CERN Library

2013-01-01

MicroShield® is a comprehensive photon/gamma ray shielding and dose assessment programme. It is widely used for designing shields, estimating source strength from radiation measurements, minimising exposure to people, and teaching shielding principles.   Integrated tools allow the graphing of results, material and source file creation, source inference with decay (dose-to-Bq calculations accounting for decay and daughter buildup), the projection of exposure rate versus time as a result of decay, access to material and nuclide data, and decay heat calculations. The latest version is able to export results using Microsoft Office (formatted and colour-coded for readability). Sixteen geometries accommodate offset dose points and as many as ten standard shields plus source self-shielding and cylinder cladding are available. The library data (radionuclides, attenuation, build-up and dose conversion) reflect standard data from ICRP 38 and 107* as well as ANSI/ANS standards and RSICC publicat...

Self-Employment Dynamics, State Dependence and Cross-Mobility Patterns

OpenAIRE

Caliendo, Marco; Uhlendorff, Arne

2008-01-01

This paper analyzes the mobility between self-employment, wage employment and non-employment. Using data for men in West Germany, we find strong true state dependence in all three states. Moreover, compared to wage employment, non-employment increases the probability of self-employment significantly, and self-employment goes along with a higher risk of future non-employment.

Examination of total cross section resonance structure of niobium and silicon in neutron transmission experiments

Science.gov (United States)

Andrianova, Olga; Lomakov, Gleb; Manturov, Gennady

2017-09-01

The neutron transmission experiments are one of the main sources of information about the neutron cross section resonance structure and effect in the self-shielding. Such kind of data for niobium and silicon nuclides in energy range 7 keV to 3 MeV can be obtained from low-resolution transmission measurements performed earlier in Russia (with samples of 0.027 to 0.871 atom/barn for niobium and 0.076 to 1.803 atom/barn for silicon). A significant calculation-to-experiment discrepancy in energy range 100 to 600 keV and 300 to 800 keV for niobium and silicon, respectively, obtained using the evaluated nuclear data library ROSFOND, were found. The EVPAR code was used for estimation the average resonance parameters in energy range 7 to 600 keV for niobium. For silicon a stochastic optimization method was used to modify the resolved resonance parameters in energy range 300 to 800 keV. The improved ROSFOND evaluated nuclear data files were tested in calculation of ICSBEP integral benchmark experiments.

Some observations of the pressure distribution in a tube bank for conditions of self generated acoustic resonance

International Nuclear Information System (INIS)

Fitzpatrick, J.A.; Donaldson, I.S.; McKnight, W.

1979-01-01

The results for mean and fluctuating pressure distributions around tubes in an in-line tube bank are presented for both non-resonant and self-excited acoustic standing wave resonant flow regimes. It is readily deduced that the nature of the flow in the bank is dramatically altered with the onset of acoustic resonance. The velocity gradients which appear across the bank with the onset of resonance would suggest regions of flow recirculation in the bank although no evidence of this was found. The spectra of fluctuating pressure on the duct roof in the bank and on tubes deep in the bank exhibited coherent peaks only during resonance. (author)

Single-mode Brillouin fiber laser passively stabilized at resonance frequency with self-injection locked pump laser

International Nuclear Information System (INIS)

Spirin, V V; Lopez-Mercado, C A; Megret, P; Fotiadi, A A

2012-01-01

We demonstrate a single-mode Brillouin fiber ring laser, which is passively stabilized at pump resonance frequency by using self-injection locking of semiconductor pump laser. Resonance condition for Stokes radiation is achieved by length fitting of Brillouin laser cavity. The laser generate single-frequency Stokes wave with linewidth less than 0.5 kHz using approximately 17-m length cavity

Shielding Calculations for PUSPATI TRIGA Reactor (RTP) Fuel Transfer Cask with Micro shield

International Nuclear Information System (INIS)

Nurhayati Ramli; Ahmad Nabil Abdul Rahim; Ariff Shah Ismail

2011-01-01

The shielding calculations for RTP fuel transfer cask was performed by using computer code Micro shield 7.02. Micro shield is a computer code designed to provide a model to be used for shielding calculations. The results of the calculations can be obtained fast but the code is not suitable for complex geometries with a shielding composed of more than one material. Nevertheless, the program is sufficient for As Low As Reasonable Achievable (ALARA) optimization calculations. In this calculation, a geometry based on the conceptual design of RTP fuel transfer cask was modeled. Shielding material used in the calculations were lead (Pb) and stainless steel 304 (SS304). The results obtained from these calculations are discussed in this paper. (author)

The Active Muon Shield

CERN Document Server

Bezshyiko, Iaroslava

2016-01-01

In the SHiP beam-dump of the order of 1011 muons will be produced per second. An active muon-shield is used to magnetically deflect these muons out of the acceptance of the spectrom- eter. This note describes how this shield is modelled and optimized. The SHiP spectrometer is being re-optimized using a conical decay-vessel, and utilizing the possibility to magnetize part of the beam-dump shielding iron. A shield adapted to these new conditions is presented which is significantly shorter and lighter than the shield used in the Technical Proposal (TP), while showing a similar performance.

Ferromagnetic resonance in low interacting permalloy nanowire arrays

Energy Technology Data Exchange (ETDEWEB)

Raposo, V.; Zazo, M.; Flores, A. G.; Iñiguez, J. [Departamento de Física Aplicada, University of Salamanca, E-37071 Salamanca (Spain); Garcia, J.; Vega, V.; Prida, V. M. [Departamento de Física, Universidad de Oviedo, E-33007 Oviedo (Spain)

2016-04-14

Dipolar interactions on magnetic nanowire arrays have been investigated by various techniques. One of the most powerful techniques is the ferromagnetic resonance spectroscopy, because the resonance field depends directly on the anisotropy field strength and its frequency dependence. In order to evaluate the influence of magnetostatic dipolar interactions among ferromagnetic nanowire arrays, several densely packed hexagonal arrays of NiFe nanowires have been prepared by electrochemical deposition filling self-ordered nanopores of alumina membranes with different pore sizes but keeping the same interpore distance. Nanowires’ diameter was changed from 90 to 160 nm, while the lattice parameter was fixed to 300 nm, which was achieved by carefully reducing the pore diameter by means of Atomic Layer Deposition of conformal Al{sub 2}O{sub 3} layers on the nanoporous alumina templates. Field and frequency dependence of ferromagnetic resonance have been studied in order to obtain the dispersion diagram which gives information about anisotropy, damping factor, and gyromagnetic ratio. The relationship between resonance frequency and magnetic field can be explained by the roles played by the shape anisotropy and dipolar interactions among the ferromagnetic nanowires.

Quantum Devices Bonded Beneath a Superconducting Shield: Part 2

Science.gov (United States)

McRae, Corey Rae; Abdallah, Adel; Bejanin, Jeremy; Earnest, Carolyn; McConkey, Thomas; Pagel, Zachary; Mariantoni, Matteo

The next-generation quantum computer will rely on physical quantum bits (qubits) organized into arrays to form error-robust logical qubits. In the superconducting quantum circuit implementation, this architecture will require the use of larger and larger chip sizes. In order for on-chip superconducting quantum computers to be scalable, various issues found in large chips must be addressed, including the suppression of box modes (due to the sample holder) and the suppression of slot modes (due to fractured ground planes). By bonding a metallized shield layer over a superconducting circuit using thin-film indium as a bonding agent, we have demonstrated proof of concept of an extensible circuit architecture that holds the key to the suppression of spurious modes. Microwave characterization of shielded transmission lines and measurement of superconducting resonators were compared to identical unshielded devices. The elimination of box modes was investigated, as well as bond characteristics including bond homogeneity and the presence of a superconducting connection.

Design and Performance of a Metal-Shielded Piezoelectric Sensor.

Science.gov (United States)

Sáenz de Inestrillas, Álvaro; Camarena, Francisco; Bou Cabo, Manuel; Barreiro, Julián M; Reig, Antonio

2017-06-04

In certain circumstances when acoustic measurements are required in the presence of explosive atmospheres the sensor must be placed inside a Faraday Cage. Piezoelectric active materials are suitable for this purpose as they do not need an electrical power supply, although the metal shielding can considerably reduce sensor sensitivity, which is already low at the acoustic frequency range (<20 kHz). This paper describes a metal-shielded piezoelectric sensor designed to work in the range of frequencies between 1 and 2 kHz and in these environmental conditions. The main idea was to add a thin material layer to the front face of the piezoelectric ceramic in order to force the system to vibrate in flexure mode at low frequencies. The resonant frequency and sensitivity of the system was studied as a function of the radius, thickness, and material of the thin layer. The study includes a comparison of theoretical model, FEM simulation, and real data measured using three aluminum and three steel prototypes of different sizes.

REACTOR SHIELD

Science.gov (United States)

Wigner, E.P.; Ohlinger, L.E.; Young, G.J.; Weinberg, A.M.

1959-02-17

Radiation shield construction is described for a nuclear reactor. The shield is comprised of a plurality of steel plates arranged in parallel spaced relationship within a peripheral shell. Reactor coolant inlet tubes extend at right angles through the plates and baffles are arranged between the plates at right angles thereto and extend between the tubes to create a series of zigzag channels between the plates for the circulation of coolant fluid through the shield. The shield may be divided into two main sections; an inner section adjacent the reactor container and an outer section spaced therefrom. Coolant through the first section may be circulated at a faster rate than coolant circulated through the outer section since the area closest to the reactor container is at a higher temperature and is more radioactive. The two sections may have separate cooling systems to prevent the coolant in the outer section from mixing with the more contaminated coolant in the inner section.

TIME-DEPENDENT COROTATION RESONANCE IN BARRED GALAXIES

Energy Technology Data Exchange (ETDEWEB)

Wu, Yu-Ting; Taam, Ronald E. [Institute of Astronomy and Astrophysics, Academia Sinica, Taipei 10617, Taiwan (China); Pfenniger, Daniel, E-mail: ytwu@asiaa.sinica.edu.tw, E-mail: daniel.pfenniger@unige.ch, E-mail: taam@asiaa.sinica.edu.tw [Geneva Observatory, University of Geneva, CH-1290 Sauverny (Switzerland)

2016-10-20

The effective potential neighboring the corotation resonance region in barred galaxies is shown to be strongly time-dependent in any rotating frame, due to the competition of nearby perturbations of similar strengths with differing rotation speeds. Contrary to the generally adopted assumption that in the bar rotating frame the corotation region should possess four stationary equilibrium points (Lagrange points), with high quality N -body simulations, we localize the instantaneous equilibrium points (EPs) and find that they circulate or oscillate broadly in azimuth with respect to the pattern speeds of the inner or outer perturbations. This implies that at the particle level the Jacobi integral is not well conserved around the corotation radius. That is, angular momentum exchanges decouple from energy exchanges, enhancing the chaotic diffusion of stars through the corotation region.

Evaluation of radiation-shielding properties of the composite material

International Nuclear Information System (INIS)

Pavlenko, V.I.; Chekashina, N.I.; Yastrebinskij, R.N.; Sokolenko, I.V.; Noskov, A.V.

2016-01-01

The paper presents the evaluation of radiation-shielding properties of composite materials with respect to gamma-radiation. As a binder for the synthesis of radiation-shielding composites we used lead boronsilicate glass matrix. As filler we used nanotubular chrysotile filled with lead tungstate PbWO4. It is shown that all the developed composites have good physical-mechanical characteristics, such as compressive strength, thermal stability and can be used as structural materials. On the basis of theoretical calculation we described the graphs of the gamma-quanta linear attenuation coefficient depending on the emitted energy for all investigated composites. We founded high radiation-shielding properties of all the composites on the basis of theoretical and experimental data compared to materials conventionally used in the nuclear industry - iron, concrete, etc

SHIELD 1.0: development of a shielding calculator program in diagnostic radiology

International Nuclear Information System (INIS)

Santos, Romulo R.; Real, Jessica V.; Luz, Renata M. da; Friedrich, Barbara Q.; Silva, Ana Maria Marques da

2013-01-01

In shielding calculation of radiological facilities, several parameters are required, such as occupancy, use factor, number of patients, source-barrier distance, area type (controlled and uncontrolled), radiation (primary or secondary) and material used in the barrier. The shielding design optimization requires a review of several options about the physical facility design and, mainly, the achievement of the best cost-benefit relationship for the shielding material. To facilitate the development of this kind of design, a program to calculate the shielding in diagnostic radiology was implemented, based on data and limits established by National Council on Radiation Protection and Measurements (NCRP) 147 and SVS-MS 453/98. The program was developed in C⌗ language, and presents a graphical interface for user data input and reporting capabilities. The module initially implemented, called SHIELD 1.0, refers to calculating barriers for conventional X-ray rooms. The program validation was performed by the comparison with the results of examples of shielding calculations presented in NCRP 147.

Design of emergency shield

International Nuclear Information System (INIS)

Soliman, S.E.

1993-01-01

Manufacturing of an emergency movable shield in the hot laboratories center is urgently needed for the safety of personnel in case of accidents or spilling of radioactive materials. In this report, a full design for an emergency shield is presented and the corresponding dose rates behind the shield for different activities (from 1 mCi to 5 Ci) was calculated by using micro shield computer code. 4 figs., 1 tab

A self-adaptive metamaterial beam with digitally controlled resonators for subwavelength broadband flexural wave attenuation

Science.gov (United States)

Li, Xiaopeng; Chen, Yangyang; Hu, Gengkai; Huang, Guoliang

2018-04-01

Designing lightweight materials and/or structures for broadband low-frequency noise/vibration mitigation is an issue of fundamental importance both practically and theoretically. In this paper, by leveraging the concept of frequency-dependent effective stiffness control, we numerically and experimentally demonstrate, for the first time, a self-adaptive metamaterial beam with digital circuit controlled mechanical resonators for strong and broadband flexural wave attenuation at subwavelength scales. The digital controllers that are capable of feedback control of piezoelectric shunts are integrated into mechanical resonators in the metamaterial, and the transfer function is semi-analytically determined to realize an effective bending stiffness in a quadratic function of the wave frequency for adaptive band gaps. The digital as well as analog control circuits as the backbone of the system are experimentally realized with the guarantee stability of the whole electromechanical system in whole frequency regions, which is the most challenging problem so far. Our experimental results are in good agreement with numerical predictions and demonstrate the strong wave attenuation in almost a three times larger frequency region over the bandwidth of a passive metamaterial. The proposed metamaterial could be applied in a range of applications in the design of elastic wave control devices.

RadShield: semiautomated shielding design using a floor plan driven graphical user interface.

Science.gov (United States)

DeLorenzo, Matthew C; Wu, Dee H; Yang, Kai; Rutel, Isaac B

2016-09-08

The purpose of this study was to introduce and describe the development of RadShield, a Java-based graphical user interface (GUI), which provides a base design that uniquely performs thorough, spatially distributed calculations at many points and reports the maximum air-kerma rate and barrier thickness for each barrier pursuant to NCRP Report 147 methodology. Semiautomated shielding design calculations are validated by two approaches: a geometry-based approach and a manual approach. A series of geometry-based equations were derived giv-ing the maximum air-kerma rate magnitude and location through a first derivative root finding approach. The second approach consisted of comparing RadShield results with those found by manual shielding design by an American Board of Radiology (ABR)-certified medical physicist for two clinical room situations: two adjacent catheterization labs, and a radiographic and fluoroscopic (R&F) exam room. RadShield's efficacy in finding the maximum air-kerma rate was compared against the geometry-based approach and the overall shielding recommendations by RadShield were compared against the medical physicist's shielding results. Percentage errors between the geometry-based approach and RadShield's approach in finding the magnitude and location of the maximum air-kerma rate was within 0.00124% and 14 mm. RadShield's barrier thickness calculations were found to be within 0.156 mm lead (Pb) and 0.150 mm lead (Pb) for the adjacent catheteriza-tion labs and R&F room examples, respectively. However, within the R&F room example, differences in locating the most sensitive calculation point on the floor plan for one of the barriers was not considered in the medical physicist's calculation and was revealed by the RadShield calculations. RadShield is shown to accurately find the maximum values of air-kerma rate and barrier thickness using NCRP Report 147 methodology. Visual inspection alone of the 2D X-ray exam distribution by a medical physicist may not

A Sensitivity Study on the Radiation Shield of KSPR Space Reactor

Energy Technology Data Exchange (ETDEWEB)

Cerba, S.; Lee, Hyun Chul; Lim, Hong Sik; Noh, Jae Man [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-05-15

The idea of a space reactor was realised some decades ago and since that time several research activities have been performed into this field. The US National Aeronautics and Space Administration (NASA) has been developing a small fast reactor called as fission power system (FPS) for deep space mission, where highly enriched uranium (HEU) is used as fuel. On the other hand, other researchers have also surveyed a thermal reactor concept with low enriched uranium (LEU) for space applications. One of the main concerns in terms of a space reactor is the total size and the mass of the system including the reactor itself as well as the radiation shield. Since the reactor core is a source of neutrons and gamma photons of various energies, which may cause severe damage on the electronics of the space stations, the questions related to the development of a radiation shield should be address appropriately. The proposal of a radiation shield for a small space reactor is discussed in this paper. The requirements for the radiation shield have been addressed in terms of maximal absorbed doses and neutron flounces during 10 years of operation. In this study a radiation shield design for a small space reactor was investigated. All the presented calculations were performed using the multi-purpose stochastic MCNP code with temperature dependent continuous energy ENDF/B VII.0 neutron and photon cross section libraries. The aim of this study was to design a neutron and gamma shield that can meet the requirements of 250 Gy absorbed during 10 years of reactor operation. The comparison with a fast reactor design showed that high content of {sup 238}U strongly influences the shielding mass. This phenomenon is due to the higher photon production in case of the KSPR design and therefore the use of high {sup 235}U enrichments and the operation in fast neutron spectrum may be more desirable. In case if the KSPR space reactor the best shielding performance was achieved while utilizing a multi

Neutron shielding material

International Nuclear Information System (INIS)

Nodaka, M.; Iida, T.; Taniuchi, H.; Yosimura, K.; Nagahama, H.

1993-01-01

From among the neutron shielding materials of the 'kobesh' series developed by Kobe Steel, Ltd. for transport and storage packagings, silicon rubber base type material has been tested for several items with a view to practical application and official authorization, and in order to determine its adaptability to actual vessels. Silicon rubber base type 'kobesh SR-T01' is a material in which, from among the silicone rubber based neutron shielding materials, the hydrogen content is highest and the boron content is most optimized. Its neutron shielding capability has been already described in the previous report (Taniuchi, 1986). The following tests were carried out to determine suitability for practical application; 1) Long-term thermal stability test 2) Pouring test on an actual-scale model 3) Fire test The experimental results showed that the silicone rubber based neutron shielding material has good neutron shielding capability and high long-term fire resistance, and that it can be applied to the advanced transport packaging. (author)

Shielding benchmark problems, (2)

International Nuclear Information System (INIS)

Tanaka, Shun-ichi; Sasamoto, Nobuo; Oka, Yoshiaki; Shin, Kazuo; Tada, Keiko.

1980-02-01

Shielding benchmark problems prepared by Working Group of Assessment of Shielding Experiments in the Research Committee on Shielding Design in the Atomic Energy Society of Japan were compiled by Shielding Laboratory in Japan Atomic Energy Research Institute. Fourteen shielding benchmark problems are presented newly in addition to twenty-one problems proposed already, for evaluating the calculational algorithm and accuracy of computer codes based on discrete ordinates method and Monte Carlo method and for evaluating the nuclear data used in codes. The present benchmark problems are principally for investigating the backscattering and the streaming of neutrons and gamma rays in two- and three-dimensional configurations. (author)

Primary shield displacement and bowing

International Nuclear Information System (INIS)

Scott, K.V.

1978-01-01

The reactor primary shield is constructed of high density concrete and surrounds the reactor core. The inlet, outlet and side primary shields were constructed in-place using 2.54 cm (1 in) thick steel plates as the forms. The plates remained as an integral part of the shields. The elongation of the pressure tubes due to thermal expansion and pressurization is not moving through the inlet nozzle hardware as designed but is accommodated by outward displacement and bowing of the inlet and outlet shields. Excessive distortion of the shields may result in gas seal failures, intolerable helium gas leaks, increased argon-41 emissions, and shield cooling tube failures. The shield surveillance and testing results are presented

Evaluation of the shielding integrity of end-shields in PHWR type NPPs

International Nuclear Information System (INIS)

Sah, B.M.L.; Ramamirtham, B.; Kutty, B.S.

1996-01-01

In the new plants (Narora Atomic Power Plants (NAPP) onwards) relatively higher radiation fields exist on the north and south fuelling machine (FM) vault walls of the E1 100m accessible area passages. These fields were first noticed at NAPS-1 and subsequently at NAPS-2 and KAPS-1. Such surveys done at RAPS have indicated that the fields on these walls would come out to be quite low (only 1-2 mR/h) from sources other than that arising from 41 Ar contamination. RAPS/MAPS experience pointed to adequacy of shielding of the FM vault walls and sufficient overall shielding thickness of the end-shields. Further, radiometry tests of end-shields carried out at Kaiga and RAPP 3 and 4 indicated fairly satisfactory and uniform filling of balls. Hence, incomplete filling of water column of the end-shields due to any venting problem was suspected to be one possible reason for the observed high fields in NAPS and Kakrapar Atomic Power Station (KAPS). Since the presence of high radiation fields, both neutron and gamma, is of long-term concern, a special study/measurement of radiation levels on reactor face during high power operation was undertaken. In order to compare the shielding integrity of the older (RAPS/MAPS solid plate type shielding) and newer (NAPS/KAPS steel ball-filled type) end shields, these experiments were done at MAPS-2 and NAPS-2. (author). 2 refs., 2 tabs

Isoscalar and isovector giant resonances in a self-consistent phonon coupling approach

Energy Technology Data Exchange (ETDEWEB)

Lyutorovich, N.; Tselyaev, V. [Physical Faculty, St. Petersburg State University, RU-198504 St. Petersburg (Russian Federation); Speth, J., E-mail: J.Speth@fz-juelich.de [Institut für Kernphysik, Forschungszentrum Jülich, D-52425 Jülich (Germany); Krewald, S.; Grümmer, F. [Institut für Kernphysik, Forschungszentrum Jülich, D-52425 Jülich (Germany); Reinhard, P.-G. [Institut für Theoretische Physik II, Universität Erlangen-Nürnberg, D-91058 Erlangen (Germany)

2015-10-07

We present fully self-consistent calculations of isoscalar giant monopole and quadrupole as well as isovector giant dipole resonances in heavy and light nuclei. The description is based on Skyrme energy-density functionals determining the static Hartree–Fock ground state and the excitation spectra within random-phase approximation (RPA) and RPA extended by including the quasiparticle-phonon coupling at the level of the time-blocking approximation (TBA). All matrix elements were derived consistently from the given energy-density functional and calculated without any approximation. As a new feature in these calculations, the single-particle continuum was included thus avoiding the artificial discretization usually implied in RPA and TBA. The step to include phonon coupling in TBA leads to small, but systematic, down shifts of the centroid energies of the giant resonances. These shifts are similar in size for all Skyrme parametrizations investigated here. After all, we demonstrate that one can find Skyrme parametrizations which deliver a good simultaneous reproduction of all three giant resonances within TBA.

Resonant spin-flavor conversion of supernova neutrinos: Dependence on electron mole fraction

International Nuclear Information System (INIS)

Yoshida, Takashi; Takamura, Akira; Kimura, Keiichi; Yokomakura, Hidekazu; Kawagoe, Shio; Kajino, Toshitaka

2009-01-01

Detailed dependence of resonant spin-flavor (RSF) conversion of supernova neutrinos on electron mole fraction Y e is investigated. Supernova explosion forms a hot-bubble and neutrino-driven wind region of which electron mole fraction exceeds 0.5 in several seconds after the core collapse. When a higher resonance of the RSF conversion is located in the innermost region, flavor change of the neutrinos strongly depends on the sign of 1-2Y e . At an adiabatic high RSF resonance the flavor conversion of ν e ↔ν μ,τ occurs in Y e e >0.5 and inverted mass hierarchy. In other cases of Y e values and mass hierarchies, the conversion of ν e ↔ν μ,τ occurs. The final ν e spectrum is evaluated in the cases of Y e e >0.5 taking account of the RSF conversion. Based on the obtained result, time variation of the event number ratios of low ν e energy to high ν e energy is discussed. In normal mass hierarchy, an enhancement of the event ratio should be seen in the period when the electron fraction in the innermost region exceeds 0.5. In inverted mass hierarchy, on the other hand, a dip of the event ratio should be observed. Therefore, the time variation of the event number ratio is useful to investigate the effect of the RSF conversion.

Electron heating via self-excited plasma series resonance in geometrically symmetric multi-frequency capacitive plasmas

International Nuclear Information System (INIS)

Schüngel, E; Brandt, S; Schulze, J; Donkó, Z; Korolov, I; Derzsi, A

2015-01-01

The self-excitation of plasma series resonance (PSR) oscillations plays an important role in the electron heating dynamics in capacitively coupled radio-frequency (CCRF) plasmas. In a combined approach of PIC/MCC simulations and a theoretical model based on an equivalent circuit, we investigate the self-excitation of PSR oscillations and their effect on the electron heating in geometrically symmetric CCRF plasmas driven by multiple consecutive harmonics. The discharge symmetry is controlled via the electrical asymmetry effect (EAE), i.e. by varying the total number of harmonics and tuning the phase shifts between them. It is demonstrated that PSR oscillations will be self-excited under both symmetric and asymmetric conditions, if (i) the charge–voltage relation of the plasma sheaths deviates from a simple quadratic behavior and (ii) the inductance of the plasma bulk exhibits a temporal modulation. These two effects have been neglected up to now, but we show that they must be included in the model in order to properly describe the nonlinear series resonance circuit and reproduce the self-excitation of PSR oscillations, which are observed in the electron current density resulting from simulations of geometrically symmetric CCRF plasmas. Furthermore, the effect of PSR self-excitation on the discharge current and the plasma properties, such as the potential profile, is illustrated by applying Fourier analysis. High-frequency oscillations in the entire spectrum between the applied frequencies and the local electron plasma frequency are observed. As a consequence, the electron heating is strongly enhanced by the presence of PSR oscillations. A complex electron heating dynamics is found during the expansion phase of the sheath, which is fully collapsed, when the PSR is initially self-excited. The nonlinear electron resonance heating (NERH) associated with the PSR oscillations causes a spatial asymmetry in the electron heating. By discussing the resulting ionization

Rotational dependence of Fermi-type resonance interactions in molecules

Science.gov (United States)

Mikhailov, Vladimir M.; Smirnov, M. A.

1997-03-01

In Pasadena, (Milliken Lab., USA, 1930) F. Rossetti has observed in Raman spectrum of carbon-dioxide molecule the full symmetric vibration of carbon dioxide appeared as the group of four near lying lines instead of the waited single line. The true interpretation of this enigmatic effect (in that time) was given by E. Fermi -- accidental degeneration of the first excited state of the full symmetric vibration in carbon dioxide. It was the first example of the event observed later in various organic molecules. This event was named as resonance Fermi. The rotational dependence of Fermi type resonance interactions in quasirigid molecules in dominant approximation can be selected in an expansion of the effective vibration-rotation Hamiltonian Hvib- roteff by the operator H(g)(Fermi) equals H30 plus (Sigma) nH3n(g). Let us consider in detail the problem of the construction of the effective vibration-rotational Hamiltonian HVR yields Heff from the point of view of various ordering schemes (grouping) of the vibrational-rotational interactions with sequential analysis of the choice of the convenient grouping adequate to the spectroscopic problem.

Impedance self-matching ultra-narrow linewidth fiber resonator by use of a tunable π-phase-shifted FBG.

Science.gov (United States)

Jing, Mingyong; Yu, Bo; Hu, Jianyong; Hou, Huifang; Zhang, Guofeng; Xiao, Liantuan; Jia, Suotang

2017-05-15

In this paper, we present a novel ultra-narrow linewidth fiber resonator formed by a tunable polarization maintaining (PM) π-phase-shifted fiber Bragg grating and a PM uniform fiber Bragg grating with a certain length of PM single mode fiber patch cable between them. Theoretical prediction shows that this resonator has ultra-narrow linewidth resonant peaks and is easy to realize impedance matching. We experimentally obtain 3 MHz narrow linewidth impedance matched resonant peak in a 7.3 m ultra-long passive fiber cavity. The impedance self-matching characteristic of this resonator also makes itself particularly suitable for use in ultra-sensitive sensors, ultra-narrow band rejection optical filters and fiber lasers applications.

Electron correlation effects on geometries and 19F shieldings of fluorobenzenes

International Nuclear Information System (INIS)

Webb, G.A.; Karadakov, P.B.; England, J.A.

2000-01-01

In order to include the effects of electron correlation in ab initio molecular orbital calculations it is necessary to go beyond the single determinant Hartree-Fock (HF) level of theory. In the present investigation the influences of both dynamic and non-dynamic correlation effects on the optimised geometries and 19 F nuclear shielding calculations of the twelve fluorobenzenes are reported.The non-dynamic electron correlation effects are represented by complete-active space self-consistent field (CASSCF) calculations. Second- and fourth-order Moller-Plesset (MP2 and MP4) calculations are used to describe the dynamic electron correlation effects. Some density-functional (DFT) results are also reported which do not distinguish between dynamic and non-dynamic electron correlation. Following the correlated geometry optimisations 19 F nuclear shielding calculations were performed using the gauge-included atomic orbitals (GIAO) procedure, these were undertaken with wave functions which include various levels of electron correlation including HF, CASSCF and MP2. For the calculations of the optimised geometries, and some of the nuclear shieldings the 6-13G** basis set s used whereas the locally-dense [6-13G** on C and H and 6-311++G(2d,2p) on F] set is used for some of the shielding calculations. A comparison of the results of HF shielding calculations using other basis sets is included. Comparison of the calculated geometry and shielding results with relevant, reported, experimental data is made. (author)

Shielding container for radioactive isotopes

International Nuclear Information System (INIS)

Sumi, Tetsuo; Tosa, Masayoshi; Hatogai, Tatsuaki.

1975-01-01

Object: To effect opening and closing bidirectional radiation used particularly for a gamma densimeter or the like by one operation. Structure: This device comprises a rotatable shielding body for receiving radioactive isotope in the central portion thereof and having at least two radiation openings through which radiation is taken out of the isotope, and a shielding container having openings corresponding to the first mentioned radiation openings, respectively. The radioactive isotope is secured to a rotational shaft of the shielding body, and the shielding body is rotated to register the openings of the shielding container with the openings of the shielding body or to shield the openings, thereby effecting radiation and cut off of gamma ray in the bidirection by one operation. (Kamimura, M.)

REX1-87, Multigroup Neutron Cross-Sections from ENDF/B

International Nuclear Information System (INIS)

Gopalakrishnan, V.; Ganesan, S.

1988-01-01

1 - Description of program or function: The program calculates self- shielding factors for reactor applications from a pre-processed (linearized) evaluated nuclear data file in the ENDF/B format. 2 - Method of solution: Bondarenko definition of multigroup self- shielding factors invoking narrow resonance treatment is used. 3 - Restrictions on the complexity of the problem: a) Maximum no. of energy group is 620. b) Only the built-in forms of the weighting functions can be chosen. c) The program is strictly limited to resolved resonance region from physical considerations

Shielding in experimental areas

International Nuclear Information System (INIS)

Stevens, A.; Tarnopolsky, G.; Thorndike, A.; White, S.

1979-01-01

The amount of shielding necessary to protect experimental detectors from various sources of background radiation is discussed. As illustrated an experiment has line of sight to sources extending approx. 90 m upstream from the intersection point. Packing a significant fraction of this space with shielding blocks would in general be unacceptable because primary access to the ring tunnel is from the experimental halls. (1) From basic machine design considerations and the inherent necessity to protect superconducting magnets it is expected that experimental areas in general will be cleaner than at any existing accelerator. (2) Even so, it will likely be necessary to have some shielding blocks available to protect experimental apparatus, and it may well be necessary to have a large amount of shielding available in the WAH. (3) Scraping will likely have some influence on all halls, and retractable apparatus may sometimes be necessary. (4) If access to any tunnel is needed to replace a magnet, one has 96 h (4 days) available to move shielding away to permit access without additional downtime. This (the amount of shielding one can shuffle about in 96 h) is a reasonable upper limit to shielding necessary in a hall

Quantum tunneling resonant electron transfer process in Lorentzian plasmas

International Nuclear Information System (INIS)

Hong, Woo-Pyo; Jung, Young-Dae

2014-01-01

The quantum tunneling resonant electron transfer process between a positive ion and a neutral atom collision is investigated in nonthermal generalized Lorentzian plasmas. The result shows that the nonthermal effect enhances the resonant electron transfer cross section in Lorentzian plasmas. It is found that the nonthermal effect on the classical resonant electron transfer cross section is more significant than that on the quantum tunneling resonant charge transfer cross section. It is shown that the nonthermal effect on the resonant electron transfer cross section decreases with an increase of the Debye length. In addition, the nonthermal effect on the quantum tunneling resonant electron transfer cross section decreases with increasing collision energy. The variation of nonthermal and plasma shielding effects on the quantum tunneling resonant electron transfer process is also discussed