Electret ionization chamber: a new method for detection and dosimetry of thermal neutrons; Camara de ionizacao de eletretos: um novo metodo para deteccao e dosimetria de neutrons termicos

Energy Technology Data Exchange (ETDEWEB)

Ghilardi, A J.P.

1988-12-31

An electret ionization chamber with boron coated walls is presented as a new method for detecting thermal neutrons. The efficiency of electret ionization chambers with different wall materials for the external electrode was inferred from the results. Detection of slow neutrons with discrimination against the detection of {gamma}-rays and energetic neutrons was shown to depend on the selection of these materials. The charge stability over a long period of time and the charge decay owing to natural radiation were also studied. Numerical analysis was developed by the use of a micro-computer PC-XT. Both the experimental and numerical results show that the sensitivity of the electret ionization chamber for detection of thermal neutrons is comparable with that of the BF{sub 3} ionization chamber and that new technologies for deposition of the boron layer will produce higher efficiency detectors. (author). 102 refs, 32 fig, 10 tabs.

Measurement of the para-hydrogen concentration in the ISIS moderators using neutron transmission and thermal conductivity

Science.gov (United States)

Romanelli, Giovanni; Rudić, Svemir; Zanetti, Matteo; Andreani, Carla; Fernandez-Alonso, Felix; Gorini, Giuseppe; Krzystyniak, Maciej; Škoro, Goran

2018-04-01

We present an experimental study to determine the para-hydrogen concentration in the hydrogen moderators at the ISIS pulsed neutron and muon source. The experimental characterisation is based on neutron transmission experiments performed on the VESUVIO spectrometer, and thermal conductivity measurements using the TOSCA para-hydrogen rig. A reliable estimation of the level of para-hydrogen concentration in the hydrogen moderators is of crucial importance in the framework of a current project to completely refurbish the first target station at ISIS. Moreover, we report a new measurement of the total neutron cross section for normal hydrogen at 15 K on the broad energy range 3 meV -10 eV suggesting a revision of the most recent nuclear libraries for incident neutron energies lower than 10 meV. Finally, we characterise systematic errors affecting the para-hydrogen level estimation due to conversion from para to ortho hydrogen, as a function of the time a batch of gas spends in every component of our gas panel and apparatus.

Digital pulse shape discrimination between fast neutrons and gamma rays with para-terphenyl scintillator

Science.gov (United States)

Chepurnov, A. S.; Kirsanov, M. A.; Klenin, A. A.; Klimanov, S. G.; Kubankin, A. S.

2017-12-01

In the presented work, we investigated several digital methods of a discrimination signals from fast neutrons and gamma quanta. The experimental setup consists of a Pu-Be neutron source, a scintillation detector with an organic para-terphenyl monocrystal, and a digitizer (CAEN DT5730, 500 MS/s). Mixed waveform sequences were stored and then separated by pulse shape. Four methods were used for signals separation. Comparison of the traditional and the new methods of Figure of Merit (FOM) calculation is given. FOM = 1.5 was obtained in our setup for the minimum threshold value. A scintillation detector with a para-terphenyl crystal was used to measure neutron yield in the neutron generator with carbon nanotubes.

The determination of sulphur in materials of high neutron absorption cross-section by fast-neutron activation analysis; Determination du soufre dans les matieres de forte section efficace d'absorption neutronique, au moyen d'une analyse par activation avec des neutrons rapides; Opredelenie sery v materialakh s bol'shim secheniem pogloshcheniya nejtronov metodom aktivatsionnogo analiza bystrykh nejtronov; Determinacion del azufre en sustancias de elevada seccion eficaz de absorcion neutronica mediante analisis por activacion con neutrones rapidos

Energy Technology Data Exchange (ETDEWEB)

Gibbons, D; Simpson, H [Wantage Research Laboratory (A.E.R.E.), Wantage, Berks. (United Kingdom)

1962-01-15

The production of radiophosphorus by the fast neutron (n, p) reaction on sulphur is used for the determination of sulphur by activation analysis. Using this technique it is possible to determine sulphur in materials of high thermal-neutron absorption cross-section because the absorption cross-sections for fast neutrons are, in general, much lower than those for slow neutrons, so that self-shielding errors are considerably reduced. Interference due to the slow neutron (n, {gamma}) reaction on neutral phosphorus is eliminated by a double irradiation technique involving irradiation in regions of differing slow/fast flux-ratios. The method has been applied to the determination of sulphur in chromium and arsenic. (author) [French] La production de radiophosphore par reaction (n, p) de neutrons rapides sur le soufre est utilisee pour la determination du soufre au moyen d'une analyse par activation. Cette methode permet la determination du soufre dans les matieres de forte section efficace d'absorption des neutrons thermiques; en effet, les sections efficaces d'absorption des neutrons rapides sont, d'une maniere generale, beaucoup plus faibles que pour les neutrons lents, de sorte que les erreurs d'autoprotection se trouvent considerablement reduites. L'interference due a la reaction (n, {gamma}) des neutrons lents sur le phosphore naturel est eliminee par une double irradiation, qui implique une irradiation dans les regions ou le rapport du flux de neutrons lents au flux de neutrons rapides a des valeurs differentes. La methode a ete appliquee a la determination du soufre dans le chrome et l'arsenic. (author) [Spanish] La formacion de fosforo radiactivo por la accion de los neutrones rapidos sobre el azufre, reaccion (n, p), puede servir para determinar este elemento mediante analisis por activacion. El empleo de esta tecnica permite efectuar determinaciones de azufre en materiales de elevada seccion eficaz de absorcion de neutrones termicos porque, en general, las

Photo and cathode luminescence emission in oxide silicium films implanted with silicium; Emision de foto y catodoluminiscencia en peliculas de oxido de silicio termico implantadas con silicio

Energy Technology Data Exchange (ETDEWEB)

Flores, F; Aceves, M. [Instituto Nacional de Astrofisica Optica y Electronica, Mexico, D.F. (Mexico); Carrillo, J. [Benemrita Universidad Autonoma de Puebla, Puebla (Mexico); Dominguez, C. [Universida Autonoma de Barcelona, Barcelona (Spain); Falcony, C. [Instituto Politecnico Nacional, Mexico, D.F. (Mexico)

2001-10-01

We studied the photo and cathodoluminescence of Silicon Rich Oxides (SRO) obtained by ion implant of Si in thermal oxides. Doses of 10{sup 1}6 cm{sup -}2 (low dose) and 10{sup 1}7 cm{sup -}2 (high dose) and implant energy of 150 keV were used. The films were annealed for 30, 60 and 180 minutes in nitrogen at 1100 Celsius degrees. The spectra show photo and cathodoluminescence emission in the visible range, the bands in the spectra change with the conditions of ion implant and annealing. The films without thermal treatment in both dose present photoluminescence bands around 1.9 eV (band B) and 2.4 eV (band C). With the thermal treatments, the band B disappears. In the case of the films with low dose, the band C shows a blue shift and a decrease in intensity. The high dose films have a band centered in 1.7 eV (band A) that increases its intensity with annealings. The cathodoluminescence bands in all the cases are in 2.7 eV (band D) and they present changes with the thermal treatments that it seems they depend on the variation in the implant parameters. [Spanish] Se estudian las propiedades de foto y la catodoluminiscencia de peliculas de oxidos de silicio ricos en Si (Silicon Rich Oxide SRO) obtenidas por implantacion ionica de Si en oxidos termicos. Se usaron dosis de 10{sup 1}6 cm{sup -}2 (dosis baja) y 10{sup 1}7 cm{sup -}2 (dosis alta) y energia de implantacion de 150 keV. Las peliculas se sometieron a tratamientos termicos por 30, 60 y 180 minutos en nitrogeno de 1100 grados centigrados. Se encontro emision foto y catodoluminiscente en el rango visible, las bandas en los espectros cambian con las condiciones de implantacion ionica y con los tratamientos termicos. Las peliculas sin tratamiento termico en ambas dosis presentan bandas de fotoluminiscencia alrededor de 1.9 eV (banda B) y 2.4 eV (banda C). Con los tratamientos termicos, la banda B desaparece. En el caso de las peliculas con dosis baja, la banda C muestra un corrimiento hacia el azul junto con una

The effective lifetime and temperature coefficient in a coupled fast-thermal reactor; Temps de vie effectif et coefficient de temperature dans un reacteur a couplage neutrons rapides-neutrons thermiques; Ehffektivnyj srok zhizni i temperaturnyj koehffitsient nejtronov v dvoyakom reaktore na bystrykh i teplovykh nejtronakh; Vida efectiva y coeficiente de temperatura en un reactor con acoplamiento rapido-termico

Energy Technology Data Exchange (ETDEWEB)

Haefele, W. [Kernforschungszentrum, Karlsruhe (Germany)

1962-03-15

thermique. Le probleme est etudie avec un groupe de neutrons retardes (au sens habituel). Un formalisme exprime le temps de vie effectif et le coefficient de temperature aux differents stades de la saute de puissance. L'auteur indique les sautes de puissance pour differentes valeurs de {alpha}{sub 0} jusqu'a ce que soit atteinte la limite de la cinetique du reacteur a neutrons rapides. (author) [Spanish] La teoria de los sistemas acoplados fue ampliamente desarrollada por Avery y sus colaboradores en el Argonne National Laboratory. Una de las caracteristicas mas interesantes de los sistemas acoplados es la prolongacion de la vida efectiva de los neutrones. La componente termica actua como una especie de retardador neutronico. Como en la teoria de los neutrones retardados, el efecto retardador desaparece cuando la reactividad adquiere un valor suficientemente elevado para que la componente rapida alcance la criticidad independientemente . El autor examina un reactor con acoplamiento en el que la componente rapida sufre un salto instantaneo de reactividad {alpha}{sub 0}. La temperatura aumenta como consecuencia del incremento del nivel de potencia y comienzan a actuar dos coeficiente termicos: el que corresponde a la componente rapida y el coeficiente de temperatura de la componente termica. El problema se estudia en relacion con un grupo de neutrones retardados (en el sentido corriente del termino). El autor presenta una serie de formulas que expresan la vida efectiva de los neutrones y el coeficiente de temperatura en las diferentes etapas del salto de reactividad. El autor indica esos saltos para distintos valores de {alpha}{sub 0}, basta alcanzar el limite correspondiente a la cinetica de los reactores de neutrones rapidos. (author) [Russian] Teoriya dvoyakikh sistem byla podrobno razrabotana R. Ehjveri i sotrudnikami v Argonskoj natsional'noj laboratorii. Odnim iz osnovnykh interesnykh momentov v sparennoj sisteme yavlyaetsya bol'shij ehffektivnyj srok zhizni nejtronov

Measurements of thermal neutron fluence in the bunker of a cyclotron for PET isotope production; Medidas de fluencia de neutrones termicos en el bunker de un ciclotron de produccion de isotopos para PET

Energy Technology Data Exchange (ETDEWEB)

Mendez Villafane, R.; Sansoloni florit, F.; Lagares gonzalez, J. L.; Llop Roig, J.; Guerrero Araque, J. E.; Muniz Gutierrez, J. L.; Perez Morales, J. M.

2011-07-01

To measure the neutron spectrum has been used spectrometry system based on Bonner spheres with Au flakes as thermal neutron detector at its center while the results are still pending and will be analyzing another job.

Energy saving by means of air conditioning equipment replacement and the household application of thermal insulation; Ahorro de energia electrica por reemplazo de equipos de aire acondicionado y aplicacion de aislamiento termico en viviendas

Energy Technology Data Exchange (ETDEWEB)

Peralta Solorio, Jose Luis [Fideicomiso para el Ahorro de la Energia (Mexico)

2005-07-15

An extension study of the Financing Program for Energy Saving looked for the evaluation of the electric energy saving potential obtained by the replacement of air conditioning equipment and the application of thermal insulation in 30 houses of two Mexican cities with warmth climate. In a joint effort with Comision Federal de Electricidad the consumption files of the users were analyzed and field measurements of electric demand and of refrigeration were made. As a following step the change of the refrigeration necessities derived from the application of thermal insulation were evaluated as well as the energy efficiency improvement obtained by the substitution of the air conditioning equipment and the favorable results obtained by the implementation of both measures - thermal insulation and change of air conditioning equipment in a joint form. This way, as a conclusion, the optimum sequence of application of these measures is revealed. [Spanish] Un estudio extension del Programa de Financiamiento para el Ahorro de Energia Electrica busco evaluar el potencial de ahorro de energia electrica alcanzado por el reemplazo de equipos de aire acondicionado y la aplicacion de aislamiento termico en 30 viviendas de dos ciudades mexicanas con clima calido. En un esfuerzo conjunto con la Comision Federal de Electricidad se analizaron los historiales de consumo de los usuarios y se efectuaron las mediciones de campo de demanda electrica y de refrigeracion. Como paso siguiente se valoro el cambio en las necesidades de refrigeracion derivado de la aplicacion de aislamiento termico al igual que la mejora en eficiencia energetica obtenida por la sustitucion de aire acondicionado y se identificaron los resultados favorecedores arrojados por la implementacion de ambas medidas -aislamiento termico y cambio de equipo de aire acondicionado- en forma conjunta. De esta manera, como conclusion, se devela la mas optima secuencia de aplicacion de estas medidas.

The impact of the use of thermal insulating materials in the global climatic change; El impacto del uso de los aislamientos termicos en el cambio de los climas globales

Energy Technology Data Exchange (ETDEWEB)

Ordonez C, Luis Felipe [Aislantes Minerales, S.A. de C.V. (Mexico)

1996-12-31

One of the technologies for energy saving easier to understand and one of the fastest and economical to install in the dwelling, commercial and industrial, construction is represented by the use of thermal insulation for the thermal energy losses control. As a result of the application of this technology in direct form for the smaller consumption of energy fuels, will have the effect of a lesser emission of pollution gases that produce the green house effect of the earth atmosphere. The thermal insulating materials, made from a variety of raw materials, many of which utilize large amounts of recycled products in the benefit of the smaller use of natural resources, offer annually and permanently reductions in the energy consumption much higher than the energy resources utilized just once in its manufacture. Therefore, they are also an economical way in contributing in the reduction of atmospheric pollutants of the so-called greenhouse gases. [Espanol] Una de las tecnologias para el ahorro de energia mas faciles de comprender y de las mas rapidas y economicas de instalar en la edificacion de vivienda, comercial e industrial, es la que representa el uso de aislamientos termicos para el control de las perdidas de energia termica. Como resultado de la aplicacion de esta tecnologia, en forma directa por el menor consumo de energeticos combustibles, tendra como efecto la menor emision de gases contaminantes que producen el efecto de invernadero en la atmosfera terrestre. Los aislamientos termicos, fabricados de una gran variedad de materiales, muchos de los cuales utilizan grandes cantidades de productos reciclados en beneficio del menor uso de los recursos naturales, ofrecen anualmente y permanentemente reducciones de consumo de energia muy superiores a los recursos energeticos utilizados una sola vez en su manufactura. Por ende, tambien son una forma economica a coadyuvar en la reduccion de contaminantes atmosfericos de los llamados gases de invernadero.

The impact of the use of thermal insulating materials in the global climatic change; El impacto del uso de los aislamientos termicos en el cambio de los climas globales

Energy Technology Data Exchange (ETDEWEB)

Ordonez C, Luis Felipe [Aislantes Minerales, S.A. de C.V. (Mexico)

1997-12-31

One of the technologies for energy saving easier to understand and one of the fastest and economical to install in the dwelling, commercial and industrial, construction is represented by the use of thermal insulation for the thermal energy losses control. As a result of the application of this technology in direct form for the smaller consumption of energy fuels, will have the effect of a lesser emission of pollution gases that produce the green house effect of the earth atmosphere. The thermal insulating materials, made from a variety of raw materials, many of which utilize large amounts of recycled products in the benefit of the smaller use of natural resources, offer annually and permanently reductions in the energy consumption much higher than the energy resources utilized just once in its manufacture. Therefore, they are also an economical way in contributing in the reduction of atmospheric pollutants of the so-called greenhouse gases. [Espanol] Una de las tecnologias para el ahorro de energia mas faciles de comprender y de las mas rapidas y economicas de instalar en la edificacion de vivienda, comercial e industrial, es la que representa el uso de aislamientos termicos para el control de las perdidas de energia termica. Como resultado de la aplicacion de esta tecnologia, en forma directa por el menor consumo de energeticos combustibles, tendra como efecto la menor emision de gases contaminantes que producen el efecto de invernadero en la atmosfera terrestre. Los aislamientos termicos, fabricados de una gran variedad de materiales, muchos de los cuales utilizan grandes cantidades de productos reciclados en beneficio del menor uso de los recursos naturales, ofrecen anualmente y permanentemente reducciones de consumo de energia muy superiores a los recursos energeticos utilizados una sola vez en su manufactura. Por ende, tambien son una forma economica a coadyuvar en la reduccion de contaminantes atmosfericos de los llamados gases de invernadero.

Matriz para ingenieria de tejido oseo: modificacion superficial con zinc Estudio preliminar

OpenAIRE

Martinez, Cristian; Olmedo, Daniel; Ozols, Andres

2013-01-01

El objetivo del presente trabajo es desarrollar un metodo de sintesis de matrices para ingenieria de tejidos, capaces de acelerar los procesos reparativos y disminuir el riesgo de infeccion, destinadas a cirugias reconstructivas que involucren el tejido oseo. A este fin se emplea la fase mineral de hueso bovino, la hidroxiapatita, conservando su estructura tridimensional. Esta se obtiene a partir de un proceso de lavado quimico, seguido de un proceso termico que elimina todos los componentes ...

Determination of thermal neutrons diffusion length in graphite; Determinacion de la Longitud de Difusion de los Neutrones Termicos en Grafito

Energy Technology Data Exchange (ETDEWEB)

Garcia Fite, J

1959-07-01

The diffusion length of thermal neutrons in graphite using the less possible quantity of material has been determined. The proceeding used was the measurement in a graphite pile which has a punctual source of rapid neutrons inside surrounded by a reflector medium (paraffin or water). The measurement was done in the following conditions: a) introducing an aluminium plate between both materials. b) Introducing a cadmium plate between both materials. (Author) 91 refs.

Synthesis and characterization of alanine boron hydrate for its use in thermal neutron dosimetry.; Sintesis y caracterizacion del borohidrato de alanina para su uso en dosimetria de neutrones termicos.

Energy Technology Data Exchange (ETDEWEB)

Yanez S, J C

1994-07-01

Alanine boron hydrate was synthesized for its possible use as intercomparison dosimeter for thermal neutron irradiation. The irradiations were performed in the Nuclear Reactor of the Nuclear Center of Mexico. The salt was prepared by reacting alanine and boric acid in a (1:1) stoichiometric ratio in neutral pH 7.5 aqueous solution and also in a basic pH 13 solution. The latter reaction was prepared with the addition of ammonia hydroxide (25%). Solutions were stirred and afterwards were let to evaporate. The obtained product in each reaction is a white solid. Dosimeters were prepared with the obtained reaction products and irradiated under thermal neutron flux of 5 x 10{sup 7} n/cm{sup 2} s. For 30 hours. The analysis of irradiated samples was made in a Variant E-15 Electron Paramagnetic Resonance spectrometer. The observed response of the samples prepared with the reaction product at the basic pH is approximately 50% higher than the neutral pH samples. In order to investigate the optimum signal enhancement samples were prepared in a basic pH medium in the following stoichiometric ratios: (1:0.5); (1:0.75); (1:1.25); (1:1.5) and (1:1.75). It was observed that the samples of the reaction (1:0.75) produced the higher response. The response was 2728% higher than the alanine only dosimeters. The reaction product was chemically characterized by X-ray diffraction, Nuclear Magnetic Resonance, Chromatography, Refractometry and Solubility tests. Results indicate that alanine boron hydrate is formed in basic media and in a stoichiometric ratio (1:0.75). The dosimetric characterization of alanine boron hydrate was performed, results are reported. It is concluded that alanine boron hydrate may be a good intercomparison dosimeter for thermal neutron irradiation. (Author).

The structure of para-toluidine by X-ray and neutron diffraction

International Nuclear Information System (INIS)

Bertinotti, A.L.

1965-12-01

The crystal and molecular structure of para-toluidine has been solved by X-ray and neutron diffraction counter techniques. The molecules are arranged in the form of infinite chains in the crystal, each molecule being linked to two neighbours by hydrogen bonds. The presence of the H bonds makes clear the difference in the melting points between para-toluidine and benzene hydrocarbons of related symmetry and molecular weight. Their direction accounts for the (001) cleavage and the growth anisotropy of crystals from supersaturated vapour phase. A structure-seeking method by computer has been elaborated, using lattice energy calculations applied to molecules treated as rigid bodies and making use of a simplex method for function minimization without calculation of derivatives. The way the available information is handled allows to increase the range of convergence, as shown in the case of para-toluidine. (author) [fr

The structure of para-toluidine by X-ray and neutron diffraction; Etude de la structure de la para-toluidine par la diffraction des rayons X et des neutrons

Energy Technology Data Exchange (ETDEWEB)

Bertinotti, A.L. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1965-12-01

The crystal and molecular structure of para-toluidine has been solved by X-ray and neutron diffraction counter techniques. The molecules are arranged in the form of infinite chains in the crystal, each molecule being linked to two neighbours by hydrogen bonds. The presence of the H bonds makes clear the difference in the melting points between para-toluidine and benzene hydrocarbons of related symmetry and molecular weight. Their direction accounts for the (001) cleavage and the growth anisotropy of crystals from supersaturated vapour phase. A structure-seeking method by computer has been elaborated, using lattice energy calculations applied to molecules treated as rigid bodies and making use of a simplex method for function minimization without calculation of derivatives. The way the available information is handled allows to increase the range of convergence, as shown in the case of para-toluidine. (author) [French] La structure cristalline et moleculaire de la para-toluidine a ete resolue a l'aide de la diffraction des rayons X et des neutrons. L'analyse a revele que la structure presentait un encha ement particulier des molecules, liees entre elles par des ponts hydrogene. La presence des liaisons rend compte de l'elevation du point de fusion de la para-toluidine par rapport a celui des carbures benzeniques de symetrie et de poids moleculaires voisins. La direction des liaisons explique le clivage facile (001) des cristaux obtenus par fusion et l'anisotropie de croissance des cristaux en phase vapeur. Une methode de recherche de structures par ordinateur a ete elaboree, faisant usage du concept d'energie reticulaire applique aux molecules considerees comme rigides et faisant appel a une methode de simplexe pour la minimisation des fonctions sans calcul de derivees. La maniere dont est exploitee l'information disponible permet d'accro re, comme cela est montre dans le cas de la para-toluidine, l'etendue du domaine de

The structure of para-toluidine by X-ray and neutron diffraction; Etude de la structure de la para-toluidine par la diffraction des rayons X et des neutrons

Energy Technology Data Exchange (ETDEWEB)

Bertinotti, A L [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1965-12-01

The crystal and molecular structure of para-toluidine has been solved by X-ray and neutron diffraction counter techniques. The molecules are arranged in the form of infinite chains in the crystal, each molecule being linked to two neighbours by hydrogen bonds. The presence of the H bonds makes clear the difference in the melting points between para-toluidine and benzene hydrocarbons of related symmetry and molecular weight. Their direction accounts for the (001) cleavage and the growth anisotropy of crystals from supersaturated vapour phase. A structure-seeking method by computer has been elaborated, using lattice energy calculations applied to molecules treated as rigid bodies and making use of a simplex method for function minimization without calculation of derivatives. The way the available information is handled allows to increase the range of convergence, as shown in the case of para-toluidine. (author) [French] La structure cristalline et moleculaire de la para-toluidine a ete resolue a l'aide de la diffraction des rayons X et des neutrons. L'analyse a revele que la structure presentait un encha ement particulier des molecules, liees entre elles par des ponts hydrogene. La presence des liaisons rend compte de l'elevation du point de fusion de la para-toluidine par rapport a celui des carbures benzeniques de symetrie et de poids moleculaires voisins. La direction des liaisons explique le clivage facile (001) des cristaux obtenus par fusion et l'anisotropie de croissance des cristaux en phase vapeur. Une methode de recherche de structures par ordinateur a ete elaboree, faisant usage du concept d'energie reticulaire applique aux molecules considerees comme rigides et faisant appel a une methode de simplexe pour la minimisation des fonctions sans calcul de derivees. La maniere dont est exploitee l'information disponible permet d'accro re, comme cela est montre dans le cas de la para-toluidine, l'etendue du domaine de convergence. (auteur)

An extension of diffusion theory for thermal neutrons near boundaries; Extension del campo de validez de la teoria de difusion para neutrones termico en las proximidades de bordes

Energy Technology Data Exchange (ETDEWEB)

Alvarez Rivas, J L

1963-07-01

The distribution of thermal neutron flux has been measured inside and outside copper rods of several diameters, immersed in water. It has been found that these distributions can be calculated by means of elemental diffusion theory if the value of the coefficient of diffusion is changed. this parameter is truly a diffusion coefficient, which now also depends on the diameter of the rod. Through a model an expression of this coefficient is introduced which takes account of the measurements of the author and of those reported in PUGC P/928 (1995), ANL-5872 (1959), DEGR 319 (D) (1961). This model could be extended also to plane geometry. (Author) 19 refs.

Computed tomography with thermal neutrons and gaseous position sensitive detector; Tomografia computadorizada com neutrons termicos e detetor a gas sensivel a posicao

Energy Technology Data Exchange (ETDEWEB)

Souza, Maria Ines Silvani

2001-12-01

A third generation tomographic system using a parallel thermal neutron beam and gaseous position sensitive detector has been developed along three discrete phases. At the first one, X-ray tomographic images of several objects, using a position sensitive detector designed and constructed for this purpose have been obtained. The second phase involved the conversion of that detector for thermal neutron detection, by using materials capable to convert neutrons into detectable charged particles, testing afterwards its performance in a tomographic system by evaluation the quality of the image arising from several test-objects containing materials applicable in the engineering field. High enriched {sup 3} He, replacing the argon-methane otherwise used as filling gas for the X-ray detection, as well as, a gadolinium foil, have been utilized as converters. Besides the pure enriched {sup 3} He, its mixture with argon-methane and later on with propane, have been also tested, in order to evaluate the detector efficiency and resolution. After each gas change, the overall performance of the tomographic system using the modified detector, has been analyzed through measurements of the related parameters. This was done by analyzing the images produced by test-objects containing several materials having well known attenuation coefficients for both thermal neutrons and X-rays. In order to compare the performance of the position sensitive detector as modified to detect thermal neutrons, with that of a conventional BF{sub 3} detector, additional tomographs have been conducted using the last one. The results have been compared in terms of advantages, handicaps and complementary aspects for different kinds of radiation and materials. (author)

A Cold Neutron Monochromator and Scattering Apparatus; Monochromateur et appareillage pour la diffusion de neutrons lents; Monokhromator dlya ''kholodnykh'' nejtronov i pribor dlya rasseyaniya; Monocromador y aparato de dispersion para neutrones frios

Energy Technology Data Exchange (ETDEWEB)

Harris, D; Cocking, S J; Egelstaff, P A; Webb, F J [Nuclear Physics Division, Aere, Harwell, Didcot, Berks (United Kingdom)

1963-01-15

de tiempo (8 {mu}s), por el rotor. Las rafagas de neutrales monocromaticos provenientes del rotor son dispersadas por una muestra y detectadas en uno de dos dispositivos de recuento. Cuando se estudian muestras liquidas o policristalinas, se utiliza un dispositivo de seis contadores (de BF{sub 3} de superficie unitaria) de 2 pulgadas por 24 pulgadas para angulos, de dispersion comprendidos entre 20{sup o} y 90{sup o}. Este dispositivo se coloca debajo del haz neutronico. Por encima del eje del haz, se instala otro dispositivo integrado por tres centelleadores de 2 pulgadas de diametro, que se utiliza para estudiar muestras monocristalinas. Las senales emitidas por cada contador se transmiten a un grabador de cinta que dispone de 500 canales de tiempo para cada contador. El aparato se ha utilizado para estudiar la dispersion de neutrones por varias muestras gaseosas, liquidas y cristalinas. Las mediciones masrecientesse exponen en otras memorias presentadas al Simposio. (author)

Calculation of the Inelastic Scattering of Neutrons from Polyethylene and Water; Calcul de la diffusion inelastique des neutrons par le polyethylene et l'eau; Raschet neuprugogo rasseyaniya nejtronov poliehtilenom i vodoj; Calculo de la dispersion inelastica de neutrones por polietileno y agua

Energy Technology Data Exchange (ETDEWEB)

Goldman, D T; Federighi, F D [Knolls Atomic Power Laboratory, General Electric Company, Schenectady, NY (United States)

1963-01-15

quelques precautions lorsque l'on fait l'integration numerique par rapport aux angles et aux energies. Le modele de diffusion a ete etendu aux calculs de la diffusion des neutrons par le polyethylene C{sub n}H{sub 2n}. On note des niveaux analogues a 0,089 eV, 0,182 eV, 0,354 eV et 0,533 eV. Les auteurs ont calcule les sections efficaces diffe- rentielle et totale pour la diffusion et ils ont constate que la seconde est en bon accord avec l'experience a la temperature du laboratoire. Ils ont calcule des noyaux de diffusion pour un certain nombre de temperatures et, chaque fois qu'il etait possible de le faire, ils ont compare les resultats aux experiences. De plus, ils ont calcule les spectres de flux de neutrons et les longueuts de diffusion en se fondant sur les equations de la physique des reacteurs. En comparant ces resultats et les donnees experimentales, on constate que ces mesures integrales donnent au moins des indications generales sur les caracteristiques du systeme de diffusion et qu'il conviendrait de les analyser en tenant compte des resultats detailles relatifs aux sections efficaces different tielles. (author) [Spanish] Nelkin propuso un modelo para calcular la dispersion de neutrones termicos por sistemas quimicos. Con arreglo a este modelo, la dinamica real del sistema dispersante se consideraba compuesta por una serie de movimientos oscilatorios cada uno de los cuales podia describirse por un hamiltoniano que conmuta con los hamiltonianos de los otros movimientos oscilatorios. Ello permitiria; expresar la seccion eficaz diferencial de dispersion en forma cerrada. Los autores han utilizado este modelo para calcular la dispersion de neutrones por el agua. Debe procederse con cierto cuidado al efectuar la integracion numerica respecto del angulo y de la energia. El modelo sella utilizado tambien para calcular la dispersion de neutrones por polietileno (C{sub n}H{sub 2n}). A 0,089 eV, 0,182 eV, 0.354 eV y 0,533 eV, se observan niveles analogos en el

Computer program for the calculation of stresses in rotary equipment discs; Programas de computo para el calculo de esfuerzos en discos de equipo rotatorio

Energy Technology Data Exchange (ETDEWEB)

Gutierrez Delgado, Wilson; Kubiak, Janusz; Serrano Romero, Luis Enrique [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

1991-12-31

In the preliminary design and diagnosis of rotary machines is very common to utilize simple calculation methods for the mechanical and thermal stresses, dynamic and thermodynamic analysis and flow of fluids in this machines (Gutierrez et al., 1989). The analysis with these methods provides the necessary results for the project initial stage of the machine. Later on, more complex tools are employed to refine the design of some machine components. In the Gutierrez report et al., (1989) 34 programs were developed for the preliminary design and diagnosis of rotating equipment; in this article, one of them is presented in which a method for the analysis of mechanical and thermal stresses is applied in discs of uniform or variable thickness that are normally found in turbomachines and rotary equipment. [Espanol] En el diseno preliminar y diagnostico de maquinas rotatorias es muy comun emplear metodos de calculo sencillos para el analisis de esfuerzos mecanicos y termicos, analisis dinamico y termodinamico y de flujo de fluidos en estas maquinas (Gutierrez et al., 1989). El analisis con estos metodos proporcionan los resultados necesarios para la etapa del proyecto inicial de la maquina. Posteriormente, para refinar el diseno de algunos componentes de la maquina, se aplican las herramientas mas complejas. En el informe de Gutierrez et al., (1989) se desarrollan 34 programas para el diseno preliminar y diagnostico de equipo rotatorio; en este articulo, se presenta uno de ellos, en el que se emplea un metodo para el analisis de esfuerzos mecanicos y termicos en discos de espesor constante o variable que se encuentran comunmente en turbomaquinas y en equipos rotatorios.

Computer program for the calculation of stresses in rotary equipment discs; Programas de computo para el calculo de esfuerzos en discos de equipo rotatorio

Energy Technology Data Exchange (ETDEWEB)

Gutierrez Delgado, Wilson; Kubiak, Janusz; Serrano Romero, Luis Enrique [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

1990-12-31

In the preliminary design and diagnosis of rotary machines is very common to utilize simple calculation methods for the mechanical and thermal stresses, dynamic and thermodynamic analysis and flow of fluids in this machines (Gutierrez et al., 1989). The analysis with these methods provides the necessary results for the project initial stage of the machine. Later on, more complex tools are employed to refine the design of some machine components. In the Gutierrez report et al., (1989) 34 programs were developed for the preliminary design and diagnosis of rotating equipment; in this article, one of them is presented in which a method for the analysis of mechanical and thermal stresses is applied in discs of uniform or variable thickness that are normally found in turbomachines and rotary equipment. [Espanol] En el diseno preliminar y diagnostico de maquinas rotatorias es muy comun emplear metodos de calculo sencillos para el analisis de esfuerzos mecanicos y termicos, analisis dinamico y termodinamico y de flujo de fluidos en estas maquinas (Gutierrez et al., 1989). El analisis con estos metodos proporcionan los resultados necesarios para la etapa del proyecto inicial de la maquina. Posteriormente, para refinar el diseno de algunos componentes de la maquina, se aplican las herramientas mas complejas. En el informe de Gutierrez et al., (1989) se desarrollan 34 programas para el diseno preliminar y diagnostico de equipo rotatorio; en este articulo, se presenta uno de ellos, en el que se emplea un metodo para el analisis de esfuerzos mecanicos y termicos en discos de espesor constante o variable que se encuentran comunmente en turbomaquinas y en equipos rotatorios.

Study of the Li{sub 2}CO{sub 3} as thermal neutrons detector; Estudio del Li{sub 2}CO{sub 3} como detector de neutrones termicos

Energy Technology Data Exchange (ETDEWEB)

Herrera A, E.; Urena N, F.; Delfin L, A. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)] e-mail: eha@nuclear.inin.mx

2003-07-01

The use every day but it frequents of the thermal neutrons in the treatment of tumours, using the neutron capture therapy technique in boron, there is generated the necessity to develop a dosimetric system that allows to evaluate in a reliable way the fluence and consequently the dose of neutrons that it is given in the tumours of the patients. One of the techniques but employees to determine the neutron fluence sub cadmic and epi cadmic in an indirect way, it is the activation of thin sheets of gold undress and covered with cadmium respectively that when being exposed to a neutron beam to the nuclear reaction {sup 197}Au (n, {gamma} ) {sup 198} Au, emitting gamma radiation with an energy of 0.4118 MeV, being this, a disadvantage to be used as dosemeter. On the other hand, when exposing the lithium carbonate to a thermal neutron beam, free radicals of CO{sub 3} that are quantified by the electron paramagnetic resonance technique are generated. This work analyzes those basic parameters that determine if those made up of Li{sub 2}CO{sub 3} complete with the requirements to be used as detectors and/or dosemeters of thermal neutrons. (Author)

Neutronics of pulsed spallation neutron sources

CERN Document Server

Watanabe, N

2003-01-01

Various topics and issues on the neutronics of pulsed spallation neutron sources, mainly for neutron scattering experiments, are reviewed to give a wide circle of readers a better understanding of these sources in order to achieve a high neutronic performance. Starting from what neutrons are needed, what the spallation reaction is and how to produce slow-neutrons more efficiently, the outline of the target and moderator neutronics are explained. Various efforts with some new concepts or ideas have already been devoted to obtaining the highest possible slow-neutron intensity with desired pulse characteristics. This paper also reviews the recent progress of such efforts, mainly focused on moderator neutronics, since moderators are the final devices of a neutron source, which determine the source performance. Various governing parameters for neutron-pulse characteristics such as material issues, geometrical parameters (shape and dimensions), the target-moderator coupling scheme, the ortho-para-hydrogen ratio, po...

Nonlinear analysis of thermal stresses of a of first stage nozzle of a gas turbine at full load from the results of an analysis of conjugated heat transference; Analisis no lineal de esfuerzos termicos de una tobera de primera etapa de turbina de gas a plena carga a partir de resultados de un analisis de transferencia de calor conjugado

Energy Technology Data Exchange (ETDEWEB)

Perez Hernandez, Efrain [Centro Nacional de Investigacion y Desarrollo Tecnologico (Cenidet), Cuernavaca, Morelos (Mexico); Mazur C, Zdzislaw; Garcia Illescas, R; Hernandez Rossette, Alejandro [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)

2007-11-15

The gas turbines operate at extremely high temperatures, at high thermal and mechanical stresses, causing that the useful life of the involved components be reduced. In the present article the results realized by previous investigations of temperatures obtained from analysis of heat transfer and flow of fluids of the nozzle by means of the Star-CD program based on finite volumes is presented. Later, the NISA program of finite elements was used to realize the analysis of thermal stresses considering the material plasticity. The methodology employed to determine the material properties variable with the temperature of the super-alloy FSX-414 and the plasticity model used in the structural analysis in the finite element program. The result will be later used in the fatigue analysis for the useful life assessment. [Spanish] Las turbinas de gas operan a temperatura extremadamente altas, a elevados esfuerzos termicos y mecanicos, ocasionando que la vida de los componentes involucrados se reduzca. En el presente articulo se presentan los resultados realizados por previas investigaciones de temperaturas obtenidas a partir de analisis de transferencia de calor y flujo de fluidos de la tobera mediante el programa Star-CD basado en volumenes finitos. Posteriormente, se utilizo el programa NISA de elementos finitos para realizar el analisis de esfuerzos termicos considerando plasticidad del material. Se muestra la metodologia empleada para determinar las propiedades del material variables con la temperatura de la superaleacion FSX-414 y el modelo de plasticidad utilizado en el analisis estructural en el programa de elemento finito. Los resultados seran empleados posteriormente en el analisis de fatiga para la estimacion de vida util.

Neutronics of pulsed spallation neutron sources

International Nuclear Information System (INIS)

Watanabe, Noboru

2003-01-01

Various topics and issues on the neutronics of pulsed spallation neutron sources, mainly for neutron scattering experiments, are reviewed to give a wide circle of readers a better understanding of these sources in order to achieve a high neutronic performance. Starting from what neutrons are needed, what the spallation reaction is and how to produce slow-neutrons more efficiently, the outline of the target and moderator neutronics are explained. Various efforts with some new concepts or ideas have already been devoted to obtaining the highest possible slow-neutron intensity with desired pulse characteristics. This paper also reviews the recent progress of such efforts, mainly focused on moderator neutronics, since moderators are the final devices of a neutron source, which determine the source performance. Various governing parameters for neutron-pulse characteristics such as material issues, geometrical parameters (shape and dimensions), the target-moderator coupling scheme, the ortho-para-hydrogen ratio, poisoning, etc are discussed, aiming at a high performance pulsed spallation source

Energy saving in the auxiliaries consumption for circulation water pumps optimizing the thermal regime; Ahorro en el consumo de auxiliares por bombas de agua de circulacion optimando el regimen termico

Energy Technology Data Exchange (ETDEWEB)

Orozco Martinez, Roni [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

1999-12-31

A methodology is proposed that should be followed in any thermal electric power plant to determine the load value at which a unit requires a second circulation water pump without affecting the thermal regime and avoiding an excessive auxiliaries consumption in partial loads. In applying this method the power plant would have an energy saving equivalent to the auxiliaries consumption during an hour, when the unit as operating at full load. [Espanol] Se propone una metodologia que debe seguirse en cualquier central termoelectrica para determinar el valor de la carga en la cual una unidad requiere de la segunda bomba de agua de circulacion sin afectar el regimen termico y evitadose un excesivo consumo de auxiliares en cargas parciales. Al aplicar este metodo la central tendria un ahorro de energia equivalente al consumo de auxiliares durante una hora cuando la unidad esta generando su maxima carga.

Energy saving in the auxiliaries consumption for circulation water pumps optimizing the thermal regime; Ahorro en el consumo de auxiliares por bombas de agua de circulacion optimando el regimen termico

Energy Technology Data Exchange (ETDEWEB)

Orozco Martinez, Roni [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

1998-12-31

A methodology is proposed that should be followed in any thermal electric power plant to determine the load value at which a unit requires a second circulation water pump without affecting the thermal regime and avoiding an excessive auxiliaries consumption in partial loads. In applying this method the power plant would have an energy saving equivalent to the auxiliaries consumption during an hour, when the unit as operating at full load. [Espanol] Se propone una metodologia que debe seguirse en cualquier central termoelectrica para determinar el valor de la carga en la cual una unidad requiere de la segunda bomba de agua de circulacion sin afectar el regimen termico y evitadose un excesivo consumo de auxiliares en cargas parciales. Al aplicar este metodo la central tendria un ahorro de energia equivalente al consumo de auxiliares durante una hora cuando la unidad esta generando su maxima carga.

Thermal fracturing of the well H-40, Los Humeros, Pue., geothermal field; Fracturamiento termico del pozo H-40 del campo geotermico de Los Humeros, Pue.

Energy Technology Data Exchange (ETDEWEB)

Flores Armenta, Magaly; Tovar Aguado, Rigoberto [Comision Federal de Electricidad (Mexico)]. E-mail: magaly.flores@cfe.gob.mx

2007-01-15

Well H-40 was drilled for production in 1997, but the well was not able to sustain flow. After it was monitored to assess its injection capacity, the well was changed to an injection well, but the well did not accept more than 5 tons of fluid per hour (t/h). The well was stimulated by thermal fracturing in three tests made in October 2005. As a result, the well can accept up to 110t/h and can be used as an injection well. [Spanish] El pozo H-40 se perforo con objetivos de produccion en 1997. Sin embargo, el pozo resulto incapaz de mantenerse fluyendo. Despues de un periodo de monitoreo se evaluo su capacidad de aceptacion para tratar de utilizarlo como pozo inyector, observandose que no aceptaba mas de 5 toneladas por hora (t/h) de fluido. Por lo tanto, se decidio estimularlo mediante fracturamiento termico con tres pruebas que se realizaron en octubre de 2005, lograndose que el pozo llegara a aceptar hasta 110 t/h, lo que permitira que el pozo pueda ser usado como inyector.

Computerized system for energy diagnosis in domestic users; Sistema computarizado para diagnostico energetico en usuarios domesticos

Energy Technology Data Exchange (ETDEWEB)

Ramos N, Gaudencio; Heard, Cristopher; Fiscal E, Raul; Maqueda Z, Martin [Instituto de Investigaciones Electricas, Temixco, Morelos (Mexico)

1999-07-01

The scope of a computerized system is presented to make an energy diagnosis to homes and a simulation of scenarios of cost/benefit, due to the implementation of energy saving measures and the efficient use of electrical energy. The FIPATERM (trust for the heat insulation of the house in Mexicali), provides economic and technical support so that the domestic users diminish their expense for the electrical energy, implementing programs of Demand Side Management (DSM). The current effective programs are: thermal insulation, substitution of the existent air conditioning units for efficient ones, reduction of infiltration, leveled plan of payments, interruption of the air conditioning equipment. In order to participate in one or several of the programs of energy efficiency, an energy diagnosis is made to the user. It is from a survey of the equipment and characteristics of the house, as well as a description on the part of the user of his habits of use of the equipment, that scenarios are simulated, which allow the user to identify the most profitable measures. [Spanish] Se presenta el alcance de un sistema computarizado para realizar diagnostico energetico a casas habitacion y simulacion de escenarios de beneficio/costo, debido a la implantacion de medidas de ahorro y uso eficiente de energia electrica. El FIPATERM (fideicomiso para el aislamiento termico de la vivienda en Mexicali), proporciona apoyo economico y tecnico para que los usuarios domesticos minimicen su gasto de energia electrica, implementando programas de Administracion por el Lado de la Demanda (ALD). Los programas actualmente vigentes son: aislamiento termico, sustitucion del aire acondicionado actual por uno eficiente, reduccion de infiltracion, plan nivelado de pagos, interrupcion del equipo de aire acondicionado. Para participar en uno o varios de los programas de eficiencia energetica, al usuario se le realiza un diagnostico energetico. Es a partir de una encuesta del equipamiento y caracteristicas

Optimization of air conditioning systems utilizing low temperature thermal storage; Optimizacion de sistemas de acondicionamiento de aire utilizando sistemas de almacenamiento termico de baja temperatura

Energy Technology Data Exchange (ETDEWEB)

Contreras Ramirez, J.; Dorantes Rodriguez, R. [Departamento de Energia, Universidad Autonoma Metropolitana - Unidad Azcapotzalco, Mexico, D. F. (Mexico)

1997-12-31

sistemas esta relacionado con la variabilidad de la carga termica y las posibilidades de regulacion de la o las maquinas termicas, de tal manera de lograr, a lo largo del dia, un adecuado uso y optimizacion de la carga total instalada, con los mejores beneficios economicos posibles. Entre las estrategias que permiten optimizar la capacidad de la instalacion y la variacion de la carga termica esta el almacenamiento termico de baja temperatura, por ejemplo, el almacenamiento de hielo, el cual se produce y se almacena durante las horas en que normalmente las maquinas de refrigeracion estan paradas, y con el fin de usar esta energia almacenada durante el horario pico y durante las horas de operacion normal del equipo, pero disminuyendo en forma importante la demanda electrica de la instalacion al satisfacer la carga termica con una combinacion almacen termico-maquina de refrigeracion. En este trabajo se presentan algunos antecedentes y tipos de almacenes termicos utilizados comunmente, se discute una metodologia que permite dimensionar un almacen termico, tanto tecnica como economicamente, y se plantean algunos de los problemas en el control y operacion de estos sistemas termicos.

Optimization of air conditioning systems utilizing low temperature thermal storage; Optimizacion de sistemas de acondicionamiento de aire utilizando sistemas de almacenamiento termico de baja temperatura

Energy Technology Data Exchange (ETDEWEB)

Contreras Ramirez, J; Dorantes Rodriguez, R [Departamento de Energia, Universidad Autonoma Metropolitana - Unidad Azcapotzalco, Mexico, D. F. (Mexico)

1998-12-31

sistemas esta relacionado con la variabilidad de la carga termica y las posibilidades de regulacion de la o las maquinas termicas, de tal manera de lograr, a lo largo del dia, un adecuado uso y optimizacion de la carga total instalada, con los mejores beneficios economicos posibles. Entre las estrategias que permiten optimizar la capacidad de la instalacion y la variacion de la carga termica esta el almacenamiento termico de baja temperatura, por ejemplo, el almacenamiento de hielo, el cual se produce y se almacena durante las horas en que normalmente las maquinas de refrigeracion estan paradas, y con el fin de usar esta energia almacenada durante el horario pico y durante las horas de operacion normal del equipo, pero disminuyendo en forma importante la demanda electrica de la instalacion al satisfacer la carga termica con una combinacion almacen termico-maquina de refrigeracion. En este trabajo se presentan algunos antecedentes y tipos de almacenes termicos utilizados comunmente, se discute una metodologia que permite dimensionar un almacen termico, tanto tecnica como economicamente, y se plantean algunos de los problemas en el control y operacion de estos sistemas termicos.

Production of a {sup 44} Ti target and its cross section of thermal neutron capture; Producao de um alvo de {sup 44} Ti e sua secao de choque para captura de neutrons termicos

Energy Technology Data Exchange (ETDEWEB)

Ejnisman, R

1994-12-31

A study of the production of a {sup 44} Ti target was carried out aiming the determination of its thermal neutron capture cross-section. With this purpose, the cross-section of the reaction {sup 45} Sc(p,2 n) {sup 44} Ti was determined in the energies 16-, 18-, 20-22- and 45 MeV. The cross-section of the reactions (p,n) {sup 45} Ti, (p,pn) {sup 44m} Sc, (p,pn) {sup 44g} Sc and (p,p2n){sup 43} Sc were also measured. The results in the low energy region are in good agreement with a previous work by McGee et al. On the other hand, the cross-section at 45 MeV is different from McGee`s result and indicates the existence of an abnormal behavior of the excitation function at higher energies. Furthermore, a radiochemical separation method was developed in order to eliminate Sc from the {sup 44} Ti target which was irradiated with neutrons. It was possible to determine an upper limit for the cross-section of the reaction {sup 44} Ti (n, {gamma}) of 4 x 10{sup 3} b. At last, it is presented a discussion of the results obtained and their possible astrophysical implications. (author) 94 refs.

Neutronic study of spherical cold-neutron sources composed of liquid hydrogen and liquid deuterium

CERN Document Server

Matsuo, Y; Nagaya, Y

2003-01-01

Using the cross-section model for neutron scattering in liquid H sub 2 and D sub 2 , a neutron transport analysis is performed for spherical cold-neutron sources composed of either para H sub 2 , normal H sub 2 or normal D sub 2. A special effort is made to generate a set of energy-averaged cross-sections (80 group constants between 0.1 mu eV and 10 eV) for liquid H sub 2 and D sub 2 at melting and boiling points. A number of conclusions on the spherical cold-neutron source configurations are drawn. It is especially shown that the highest cold-neutron flux is obtainable from the normal D sub 2 source with a radius of about 50 cm, while the normal- and para-H sub 2 sources with radii around 3-4 cm produce maximum cold-neutron fluxes at the center.

The epithermal critical experiments; Experiences critiques avec des neutrons epitliermiques; Nadteplovye kriticheskie ehksperimenty; Experimentos criticos con neutrones epitermicos

Energy Technology Data Exchange (ETDEWEB)

Morewitz, H A; Carpenter, S O [Atomics International, Canoga Park, CA (United States)

1962-03-15

rapport entre les quantites de graphite et de combustible. Une experience a l'aide d'un oscillateur a ondes carrees definit les valeurs de la reactivite centrale de quarante petits echantillons de differents materiaux, jusqu'a 10{sup -8} {Delta}k pour chaque ensemble. De plus, on fait osciller des sources artificielles de neutrons, etalonnees entre elles, pour determiner les differentes fonctions neutroniques importantes au centre du montage. On obtient les spectres en procedant a des mesures a l'aide de compteurs a fission comportant des feuilles etalonnees de seuils differents et d'un spectrometre a compteur au {sup 6}Li. Une methode de traitement numerique permettra de grouper toutes les mesures en un fichier autonome de sections efficaces moyennes par spectre. (author) [Spanish] La fase actual del programa del reactor epitermico de tipo avanzado, alimentado con torio, comprende una serie de experimentos integrales sobre fisica de los reactores, cuyo objeto es reunir datos sobre las secciones eficaces neutronicas en el intervalo 1 keV a 10 MeV. Se esta estudiando una serie de nueve conjuntos criticos de varias regiones, con acoplamiento termico-rapido, de forma pseudoesferica, del tipo alveolar de cuerpo dividido. Hasta ahora se han puesto en servicio tres conjuntos de esa indole. La region externa de conexion-desconexio n acciona una region de ensayo interna de forma esferica alimentada con {sup 233}U-Th, cuyo espectro neutronico se degrada progresivament e aumentando la razon grafito-combustible . Un experimento efectuado con un oscilador de onda cuadrada define los valores de la reactividad central de cuarenta pequenas muestras de diferentes materiales, hasta 10{sup -8} {Delta}k; para cada conjunto. Ademas, se hacen oscilar fuentes artificiales de neutrones intercalibradas para determinar las diferentes funciones neutronicas que revisten importancia en el centro del conjunto. Los espectros se obtienen procediendo a mediciones con contadores de fision

Low dimensional neutron moderators for enhanced source brightness

DEFF Research Database (Denmark)

Mezei, Ferenc; Zanini, Luca; Takibayev, Alan

2014-01-01

In a recent numerical optimization study we have found that liquid para-hydrogen coupled cold neutron moderators deliver 3–5 times higher cold neutron brightness at a spallation neutron source if they take the form of a flat, quasi 2-dimensional disc, in contrast to the conventional more voluminous...... for cold neutrons. This model leads to the conclusions that the optimal shape for high brightness para-hydrogen neutron moderators is the quasi 1-dimensional tube and these low dimensional moderators can also deliver much enhanced cold neutron brightness in fission reactor neutron sources, compared...... to the much more voluminous liquid D2 or H2 moderators currently used. Neutronic simulation calculations confirm both of these theoretical conclusions....

Neutron spectrum for neutron capture therapy in boron; Espectro de neutrones para terapia por captura de neutrones en boro

Energy Technology Data Exchange (ETDEWEB)

Medina C, D.; Soto B, T. G. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Programa de Doctorado en Ciencias Basicas, 98068 Zacatecas, Zac. (Mexico); Baltazar R, A. [Universidad Autonoma de Zacatecas, Unidad Academica de Ingenieria Electrica, Programa de Doctorado en Ingenieria y Tecnologia Aplicada, 98068 Zacatecas, Zac. (Mexico); Vega C, H. R., E-mail: dmedina_c@hotmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas, Zac. (Mexico)

2016-10-15

Glioblastoma multiforme is the most common and aggressive of brain tumors and is difficult to treat by surgery, chemotherapy or conventional radiation therapy. One treatment alternative is the Neutron Capture Therapy in Boron, which requires a beam modulated in neutron energy and a drug with {sup 10}B able to be fixed in the tumor. When the patients head is exposed to the neutron beam, they are captured by the {sup 10}B and produce a nucleus of {sup 7}Li and an alpha particle whose energy is deposited in the cancer cells causing it to be destroyed without damaging the normal tissue. One of the problems associated with this therapy is to have an epithermal neutrons flux of the order of 10{sup 9} n/cm{sup 2}-sec, whereby irradiation channels of a nuclear research reactor are used. In this work using Monte Carlo methods, the neutron spectra obtained in the radial irradiation channel of the TRIGA Mark III reactor are calculated when inserting filters whose position and thickness have been modified. From the arrangements studied, we found that the Fe-Cd-Al-Cd polyethylene filter yielded a ratio between thermal and epithermal neutron fluxes of 0.006 that exceeded the recommended value (<0.05), and the dose due to the capture gamma rays is lower than the dose obtained with the other arrangements studied. (Author)

Portable system for periodical verification of area monitors for neutrons; Sistema portatil para verificacao periodica de monitores de area para neutrons

Energy Technology Data Exchange (ETDEWEB)

Souza, Luciane de R.; Leite, Sandro Passos; Lopes, Ricardo Tadeu, E-mail: rluciane@ird.gov.b [Coordenacao dos Programas de Pos-Graduacao de Engenharia (PEN/COPPE/UFRJ), RJ (Brazil). Programa de Energia Nuclear; Patrao, Karla C. de Souza; Fonseca, Evaldo S. da; Pereira, Walsan W., E-mail: karla@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Lab. Nacional de Metrologia das Radiacoes Ionizantes (LNMRI). Lab. de Neutrons

2009-07-01

The Neutrons Laboratory develops a project viewing the construction of a portable test system for verification of functioning conditions of neutron area monitors. This device will allow to the users the verification of the calibration maintenance of his instruments at the use installations, avoiding the use of an inadequate equipment related to his answer to the neutron beam response

TAR-1 A programme for the determination of time behaviour of neutron density on a thermal reactor; TAR-1. Programa para la determinacion del comportamiento temporal de la densidad neutronica en reactor termico

Energy Technology Data Exchange (ETDEWEB)

Torres Vida, J

1963-07-01

This programme, written for the UNIVAC-UCT of J.E.N., obtain the time behaviour of neutron density as a function of both positive and negative step change in reactivity. These results are obtained from solutions of the space-independent kinetic equations of a bare thermal reactor based on the Fermi continuous slowing down model and using six groups of delayed neutrons. (Author) 3 refs.

Differential Neutron Scattering from Hydrogenous Moderators; Diffusion Differentielle des Neutrons par des Ralentisseurs Hydrogenes; Differentsial'noe rasseyanie nejtronov iz vodorodosoderzhashchikh zamedlitelej; Dispersion Diferencial de Neutrones en Moderadores Hidrogenados

Energy Technology Data Exchange (ETDEWEB)

Beyster, J. R.; Young, J. C.; Neill, J. M.; Mowry, W. R. [General Atomic Division of General Dynamics Corporation, John Jay Hopkins Laboratory for Pure and Applied Science, San Diego, CA (United States)

1965-08-15

de realite physique. En outre, ce modele simple ne permet pas de prevoir avec exactitude la diffusion selon de grands angles. Les donnees experimentales sont utilisees a diverses fins pratiques. Tout d'abord, les distributions angulaires sont tres sensibles aux proprietes physiques du modele de diffusion et elles servent a les verifier. Deuxiemement, les resultats experimentaux sont sensibles aux ordres superieurs de la diffusion Pn, par opposition a plusieurs experiences integrales qui sont surtout sensibles a la diffusion P{sub 0}. En particulier, on peut verifier le noyau de diffusion P{sub 1} approprie a un modele moleculaire donne. Troisiemement, on peut calculer la section efficace de transport directement a partir des experiences en vue de l'utiliser dans l'analyse des reacteurs en theorie multigroupe. (author) [Spanish] Los autores estan midiendo, por el metodo del tiempo de vuelo, las secciones eficaces diferenciales de dispersion neutronica (d{sigma}/d {Omega}) de los moderadores de uso corriente. Para ello emplean una intensa fuente pulsada de neutrones termicos producidos por el acelerador lineal de la General Atomic, y una trayectoria de vuelo de 12 m, al final de la cual se encuentra una muestra delgada del moderador. Ademas, hay una breve trayectoria final de vuelo para los neutrones dispersados que va desde la muestra hasta varios detectores de neutrones totalmente absorbentes. Con este procedimiento puede medirse simultaneamente la distribucion angular de dispersion correspondiente a mas de 50 energias de incidencia de los neutrones. Las intensidades son elevadas, la actividad de fondo es baja y bien definida, y las mediciones pueden efectuarse rapidamente en todos los angulos de dispersion comprendidos entre 10 Degree-Sign y 155 Degree-Sign . Se presentan mediciones de las secciones eficaces de dispersion diferencial del vanadio, H{sub 2}O, D{sub 2}O y ZrH. El V se ha investigado para comprobar el aparato experimental. Se han efectuado mediciones en

Somatic mutation and recombination induced with reactor thermal neutrons in Drosophila melanogaster; Mutacion y recombinacion somaticas inducidas con neutrones termicos de reactor en Drosophila melanogaster

Energy Technology Data Exchange (ETDEWEB)

Zambrano A, F.; Guzman R, J.; Paredes G, L.; Delfin L, A. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

1997-07-01

The SMART test of Drosophila melanogaster was used to quantify the effect over the somatic mutation and recombination induced by thermal and fast neutrons at the TRIGA Mark III reactor of the ININ at the power of 300 k W for times of 30, 60 and 120 minutes with total equivalent doses respectively of 20.8, 41.6 and 83.2 Sv. A linear relation between the radiation equivalent dose and the frequency of the genetic effects such as mutation and recombination was observed. The obtained results allow to conclude that SMART is a sensitive system to the induced damage by neutrons, so this can be used for studying its biological effects. (Author)

Thermal and fast neutron distribution determination in the IPR-R1 reactor core; Levantamento das distribuicoes dos fluxos de neutrons termicos e rapidos no nucleo do reator IPR-R1

Energy Technology Data Exchange (ETDEWEB)

Guimaraes, R R.R.

1985-06-01

The work is aimed at obtaining a physical method for neutron flux distribution determination within the reactor core, in order to analyze the project of power increase in the TRIGA IPR-R1 reactor at the Nuclebras Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), located in Belo Horizonte, Minas Gerais, Brazil. The experimental process utilizes the neutron activation technique in impurities of stainless steel welding rods 700 mm long, set in acrylic supports. These rods provide simultaneous information on the thermal and fast neutron fluxes through capture and threshold reactions. The process of detection and counting of activation products utilizes a high resolution Ge (Li) detector and a mechanical scanning device, designed and manufactured at CDTN for burn-up measurements of irradiated fuel elements. Besides its simplicity, the method presents the advantage of substituting high purity imported materials by one easily obtained that also furnishes simultaneous information on the thermal and fast neutron fluxes. Furthermore, values for the absolute thermal neutron flux a long the whole core height are obtained. The procedure consists of the assessment of the thermal neutron flux in a fixed point by means of a conventional detector, and then establishing the correspondence of this measurement with the response of the stainless steel rods. (author). 30 refs, 39 figs, 9 tabs.

The Pulsed Neutron Technique Applied to Fast Non-Multiplying Assemblies; Application de la Methode des Neutrons Pulses aux Assemblages Non Multiplicateurs a Neutrons Rapides; Primenenie metoda impul'snykh nejtronov pri izuchenii povedeniya bystrykh nejtronov v nerazmnozhayushchikh sborkakh; Aplicacion de la Tecnica de los Neutrones Pulsados a Conjuntos Rapidos de Materiales No Multiplicadores

Energy Technology Data Exchange (ETDEWEB)

Beghian, L. E.; Wilensky, S. [Massachusetts Institute of Technology, Cambridge, MA (United States)

1965-10-15

Boltzmann qui est fonction du temps (c'est-a-dire une dimension, une vitesse). Les constantes de decroissance ont ete mesurees pour des plaques de plomb de 70 cm x 80 cm et de 5, 10, 15 et 20 cm d'epaisseur. Apres correction pour tenir compte de la degradation en energie et des dimensions finies de l'assemblage, les resultats sont compares aux solutions approchees de l'equation de transport de Boltzmann. (author) [Spanish] Los autores han empleado un acelerador Van de Graafi, que emitia rafagas de neutrones pulsados del orden del nanosegundo, para estudiar el comportamiento de los neutrones rapidos en conjuntos de metales no multiplicadores. Emplearon esta tecnica de la fuente de neutrones pulsados a fin de medir las secciones eficaces de dispersion inelastica de los neutrones rapidos en el Fe. El metodo empleado es analogo al utilizado para medir las secciones eficaces de absorcion en conjuntos termicos, salvo el hecho de que los tiempos de decrecimiento de los neutrones rapidos son del orden del nanosegundo mas bien que del microsegundo. En estos experimentos, se inyectaron rafagas de neutrones monoenergeticos, del orden del nanosegundo, en conjuntos de Fe de diversas dimensiones. Se observo que, en esos conjuntos, el flujo neutronico decrece exponencialmente con una constante caracteristica. Esta constante de decrecimiento esta constituida por una suma de terminos que representan la perdida de neutrones debidos al escape y a la degradacion energetica. Esta ultima representa una perdida de neutrones toda vez que se emplea un detector neutronico polarizado. El termino de eliminacion correspondiente a la dispersion elastica e inelastica puede determinarse midiendo la constante de decrecimiento en funcion de las dimensiones del conjunto de que se trate. Los autores exponen un procedimiento teorico que permite calcular la medida en que la dispersion elastica contribuye al termino de eliminacion, con lo que puede calcularse subsiguientemente la seccion eficaz de dispersion

Sistema de adquisición y transmisión de datos, por fibra óptica, para un generador de neutrones.

Directory of Open Access Journals (Sweden)

Sergio Vergara Limon

2010-11-01

Full Text Available Normal 0 21 false false false MicrosoftInternetExplorer4 st1:*{behavior:url(#ieooui } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabla normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} Se presenta el desarrollo construcción   y aplicación de un sistema virtual de adquisición de datos basado en el uso de microcontroladores, fibra óptica y PC; que restablece la comunicación entre los módulos básicos que componen un Generador de Neutrones. Se muestra como queda modernizada la interfaz original del generador, al automatizarse la adquisición de datos sobre sus parámetros de explotación.  Se introduce el uso de la PC en el Generador de Neutrones y se establece el antecedente para extender la automatización a otros subsistemas de la instalación.  

Approximation for the adjoint neutron spectrum; Aproximacao para o espectro adjunto de neutrons

Energy Technology Data Exchange (ETDEWEB)

Suster, Luis Carlos; Martinez, Aquilino Senra; Silva, Fernando Carvalho da [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Programa de Engenharia Nuclear

2002-07-01

The proposal of this work is the determination of an analytical approximation which is capable to reproduce the adjoint neutron flux for the energy range of the narrow resonances (NR). In a previous work we developed a method for the calculation of the adjoint spectrum which was calculated from the adjoint neutron balance equations, that were obtained by the collision probabilities method, this method involved a considerable quantity of numerical calculation. In the analytical method some approximations were done, like the multiplication of the escape probability in the fuel by the adjoint flux in the moderator, and after these approximations, taking into account the case of the narrow resonances, were substituted in the adjoint neutron balance equation for the fuel, resulting in an analytical approximation for the adjoint flux. The results obtained in this work were compared to the results generated with the reference method, which demonstrated a good and precise results for the adjoint neutron flux for the narrow resonances. (author)

Modulation of the neutron spectrum for NCTB; Modulacion del espectro de neutrones para TCNB

Energy Technology Data Exchange (ETDEWEB)

Medina C, D.; Letechipia de L, C.; Vega C, H. R., E-mail: dmedina_c@hotmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No.10, Fracc. La Penuela, 98068 Zacatecas, Zac. (Mexico)

2016-09-15

Cancer is characterized by the uncontrolled growth of differentiated cells in a part of the organism. Currently in the world there are millions of people living with cancer. Glioblastoma multiform e is the most common and most aggressive of brain tumors and is very difficult to treat by conventional surgery, chemotherapy or radiation. The only viable alternative is its treatment through Neutron Capture Therapy in Boron (NCTB), since is a selective therapy that requires a drug with {sup 10}B (a non-radioactive isotope of boron) and a modulated neutron beam. Thermal neutrons are captured by {sup 10}B, because has a large effective section of thermal neutron absorption, in an exothermic reaction forming the nucleus composed of {sup 11}B in an excited state that induces its cleavage in two nuclei: {sup 7}Li and alpha particle ({sup 4}He). This process causes the destruction of cancer cells by direct DNA damage, without damaging normal tissue. One of the problems associated with this therapy is to have a neutron beam with adequate flow and spectrum. The neutron spectrum must be moderated and filtered from the characteristics of the source. To this end, the main sources of neutrons are nuclear research reactors and particle accelerators. The intensity of the flow should be 2 x 10 E{sup 9} n/cm{sup 2}.s, in order to treat the patient in a reasonable time; thus, is interesting to design filters for a radial beam of a TRIGA reactor, where materials such as Cd, Al, Fe and polyethylene are being implemented in the interest of having a spectrum with which the therapy can be implemented. For this design is being played with the position of the materials, to be able to see the behavior of the spectrum and thus choose some arrangement as indicated, of course taking into account the doses of both neutrons and gammas. (Author)

A Double Slow Neutron Spectrometer; Spectrometre double pour neutrons lents; Dvojnoj spektrometr medlennykh nejtronov; Espectrometro doble para neutrones lentos

Energy Technology Data Exchange (ETDEWEB)

Bondarenko, I I; Liforov, V G; Nikolaev, M N; Orlov, V V; Parfenov, V A; Semenov, V A; Smirnov, V I; Turchin, V F [Fehi, Moscow, SSSR (Russian Federation)

1963-01-15

The neutron spectrometer described in the paper is intended for measurements of the angular and energy distribution of monochromatic slow neutrons, inelasticaily scattered by liquid and solid bodies. Experiments of this type permit detailed information to be obtained concerning the dynamics of the atoms in various aggregate states of a substance. The spectromeeter is based on the time-of-flight method. The pulse source of neutrons is the IBR (1) reactor. A mechanical interrupter, rotating synchronously with the disc of the IBR and having a prescribed phase shift, serves as the monochromator. A special phasing system ensures a phasee stability better than 0.5{sup o}. The neutrons scattered by the sample are recorded by a scintillation detector set at a given angle to the neutron beam. The resolving power of the spectrometer is - 15 {mu}s/m. The paper gives a detailed description of the construction of the spectroscope and its characteristics. (author) [French] Le spectrometre neutronique decrit dans le memoire est destine a mesurer la distribution en energie, la distribution angulaire et la diffusion inelastique des neutrons lents monochromatiques dans des liquides et des solides. Les experiences de ce genre permettent d'obtenir des renseignements detailles sur la dynamique des atomes dans de divers etats de la matiere. Le spectrometre est fonde sur la mesure du temps de vol. Comme source puisee de neutrons on a utilise le reacteur IBR-1. Le systeme monochromateur etait constitue par un interrupteur mecanique en rotation synchronisee avec celle du disque du reacteur IBR, avec un dephasage determine. Un dispositif special de dephasage assure la stabilite de la phase a 0,5{sup o} pres. La diffusion des neutrons par l'echantillon est enregistree a l'aide d'un detecteur a scintillations dispose sous un angle determine par rapport au faisceau de neutrons. Le pouvoir de resolution du spectrometre est d'environ 15 {mu}s/m. Les auteurs decrivent en detail la construction du

Study of thermal behavior of the adobe with the simulator DOE 2.1E; Estudio de comportamiento termico del adobe con el simulador DOE 2.1E

Energy Technology Data Exchange (ETDEWEB)

Luna, Anibal; Gallegos, Ricardo; Bojorquez, Gonzalo [Universidad Autonoma de Baja California, Mexicali, Baja California (Mexico)

2000-07-01

A thermal analysis of the envelope of one of the most used housing models for low income groups, as those offered by the Mexican Government is presented in this report. The building's thermal gain in walls was determined, using: concrete block, brick and adobe; and considering concrete of roofing, concrete floors, windows and doors equal in all the cases. The objective of this study is to know the contribution to the building's thermal load of each one of the materials applied. The calculation was conducted using the Doe 2.1E thermal simulator software, using meteorological data for the city of El Centro, California, USA. This was so, because there is no reliable weather data for the city of Mexicali, B.C., where the housing units are. Because of geographical proximity between of these cities the same data was used. The properties for each one of the three building materials were taken from specialized bibliography. It was determined that the housing built with adobe walls has thermal advantages over the units built with concrete block and brick. The adobe unit has a lower thermal load of 13% over the concrete block, and of 3.44% over the clay brick unit. [Spanish] Se presenta el analisis termico de la envolvente de uno de los modelos de casas mas utilizados en la construccion de viviendas de interes social en Mexico. Se determino la ganancia, termica del edificio por muros, aplicando: bloque de concreto, ladrillo de barro y adobe. Se considero techo, piso, ventanas y puertas iguales en todos los casos. El objetivo del estudio es conocer la distribucion de la carga termica segun los materiales aplicados. El calculo se realizo con el simulador termico DOE 2.1E con datos meteorologicos de la ciudad de El Centro, California, E. U., por no contar con datos de Mexicali, B. C.: debido a la proximidad y similitud topografica entre ambas ciudades se uso la misma informacion. Las propiedades aplicadas para cada uno de los tres materiales fueron tomadas de

Patterns of Lethality and Absorbed Dose Distributions in Mice for Monoenergetic Neutrons; Letalite et Distribution de la Dose Absorbee chez la Souris pour des Neutrons Monoenergetiques; Letal'nost' i raspredelenie pogloshchennoj dozy pri obluchenii myshej monoehnergeticheskimi neitronami; Letalidad y Distribucion de las Dosis Absorbidas por el Raton para Neutrones Monoenergeticos

Energy Technology Data Exchange (ETDEWEB)

Frigerio, N. A.; Jordan, D. L. [Argonne National Laboratory, Argonne, IL (United States)

1964-03-15

V {+-} 50 keV pour couvrir la region des resonances de N et de O. On a constate que la courbe de letalite est une fonction marquee de Tenergie des neutrons et une fonction egalement marquee mais independante de la distribution de la dose. Toutefois, quelles que soient la dose, l'energie et la distribution, tous les animaux qui ont survecu 5 j ont ensuite survecu au moins 144 j, puis sont morts sous les effets a long terme habituels. Cela donne a penser que les neutrons rapides monoenergetiques n ayant pas subi de contamination gamma ou epithermique produisent presque exclusivement la 'mort intestinale ' precoce. (author) [Spanish] La presencia de intensas resonancias para el C, el N y el O, en el intervalo de 100 a 1500keV, ha permitido estudiar las interacciones especificas neutron-nuclido, que se manifiestan por variaciones de la letalidad, maximos de la EBR, etc. Mediante protones resueltos de 62 {mu}A, procedentes de un acelerador de van de Graaf, de 1882 keV a 2738 keV, se obtuvieron neutrones monoenergeticos por intermedio de la reaccion {sup 7}Li(p, n){sup 7}Be. Los autores expusieron al efecto de los neutrones monoenergeticos a hembras de raton virgenes, CF-1, en capsulas de celuloide, a distancias de 3,1 a 11,3 cm de la fuente, bajo angulos de 0 a 1 radian. Durante la exposicion bilateral, los animales giraban simultaneamente en orbitas circulares o elipticas normales al eje del haz. De esta manera se podia regular la distribucion de la dosis en el cuerpo del animal. Los autores midieron el flujo absoluto con contadores de fision de {sup 235}U y por receuento absoluto mediante alambres y laminas de oro activados, revestidos de Gd. Determinaron las dosis absorbidas con microcamaras de ionizacion y con un dosimetro de FeSO{sub 4}-NH{sub 4}SCN de alta sensibilidad, preparado especialmente para este fin. Para la medicion de las dosis relativas, usaron contadores gaseosos de Hurst para protones de retroceso y centelleadores de {sup 10}B, {sup 6}Li y de protones de

In Vivo and Air Dosimetry of Fission-Spectrum Neutrons; Dosimetrie In Vivo et dans l'Air du Spectre des Neutrons de Fission; Dozimetriya v vozdukhe i dozimetriya In Vivo nejtronov spektra deleniya; Dosimetria In Vivo y en el Aire de Neutrones de un Espectro de Fision

Energy Technology Data Exchange (ETDEWEB)

Mobley, T. S.; Engel, R. E.; Godden, W. R. [Kirtland Airforce Base, New Mexico (United States); Penikas, V. T. [AFIT, Wright-Patterson Air Force Base, Ohio, with Duty Station at University of Rochester, School of Medicine and Dentistry, Rochester, NY (United States)

1964-03-15

laterales a une distance mediane de 200 cm ou de 175 cm du centre de l ' assemblage critique. La dose de neutrons mesuree dans l ' air etait de 161 {+-} 5 ,5 rad a 200 cm et de 242 {+-} 16.6 rad a 175 cm. A ces distances, la dose gamma etait respectivement de 33 {+-} 2,4 et 42 {+-} 2,5 r. Les doses d'entree et de sortie ainsi que la dose a l ' insertion variaient selon l'elevation de temperature due aux bouffees de neutrons, la distance du reacteur, l 'orientation des feuilles par rapport au reacteur et l'epaisseur et la composition de tissus attenuants. (author) [Spanish] Con el proposito de evaluar la configuracion de la dosis profunda durante la exposicion a neutrones de un espectro de fisionalos autores han ideado un metodo de dosimetria neutronica in vivo que aplicaron a ovejas. Utilizaron para estos estudios un reactor pulsante analogo al GODIVA II del Laboratorio Cientifico de Los Alamos. Dicho conjunto funciona de forma de producir impulsos de 50 {mu}s de amplitud, medida a la mitad de la altura maxima, y un ascenso de temperatura del combustible de unos 100 Degree-Sign C. Ademas, prepararon 'apositos ' subcutaneos que contienen una lamina de oro recubierta de cadmio, una lamina de oro sin recubrir y tres dosimetros de varilla de vidrio, termoluminiscentes, en un recipiente de plomo al litio revestido de vidrio. Estos apositos se introdujeron en el tejido subcutaneo, a ambos lados del cuerpo, y sirvieron para medir el flujo integrado de neutrones termicos y la dosis gamma, a medida que la irradiacion neutronica se aplica 'lateralmente'. Los apositos abdominales se prepararon en forma semejante a los subcutaneos; constan de una esfera de boro que contiene laminas de umbral de fision (Pu, Np, U) recubiertas de cadmio, una pastilla de azufre y los mismos tres tipos de dosimetros que forman parte del aposito subcutaneo. El aposito dosimetrico se sujeto al pilar anterior del rumen del animal 18 h antes de someterlo a la exposicion. En la memoria se describe la tecnica de

Potential of para-boronophenylalaninol as a boron carrier in boron neutron capture therapy, referring to that of its enantiomers

International Nuclear Information System (INIS)

Masunaga, S.; Sakurai, Y.; Ono, K.; Suziki, M.; Nagata, K.; Takagaki, M.; Nagasawa, H.

2003-01-01

We evaluated the potential of a newly developed 10 B-containing alpha-amino alcohol of para-boronophenylalanine- 10 B (BPA), para-boronophenylalaninol (BPAol), as a boron carrier in boron neutron capture therapy. C57BL mice bearing EL4 tumors and C3H/He mice bearing SCC VII tumors received 5-bromo-2'-deoxyuridine (BrdU) continuously via implanted mini-osmotic pumps to label all proliferating (P) cells. After oral administration of L-BPA or D-BPA, or intraperitoneal injection of L-BPAol or D-BPAol, the tumors were irradiated with reactor thermal neutron beams. For the combination with mild temperature hyperthermia (MTH) and/or tirapazamine (TPZ), the tumors were heated at 40 degrees centigrade for 30 minutes right before neutron exposure, and/or TPZ was intraperitoneally injected 30 minutes before irradiation. The tumors were then excised, minced and trypsinized. The tumor cell suspensions thus obtained were incubated with cytochalasin-B (a cytokinesis blocker), and the micronucleus (MN) frequency in cells without BrdU labeling ( = quiescent (Q) cells) was determined using immunofluorescence staining for BrdU. Meanwhile, 6 hours after irradiation, tumor cell suspensions obtained in the same manner were used for determining the apoptosis frequency in Q cells. The apoptosis and MN frequency in total (P + Q) tumor cells were determined from the tumors that were not pretreated with BrdU. Without TPZ or MTH, L- and D-BPAol increased both frequencies markedly, especially for total cells. Although not significantly, L-BPA and D-BPAol increased both frequencies slightly more remarkably than D-BPA and L-BPAol, respectively. On combined treatment with both MTH and TPZ, the sensitivity difference between total and Q cells was markedly reduced. MTH increased the 10 B uptake of all 10 B-carriers into both tumor cells to some degree. Both L- and D-BPAol have potential as 10 B-carriers in neutron capture therapy, especially when combined with both MTH and TPZ

Transmutation doping and recoil effects in semiconductors exposed to thermal neutrons; Transmutations provoquees et effets de recul dans les semi-conducteurs exposes aux neutrons thermiques; Prisadka i sdacha v rezul'tate prevrashcheniya poluprovodnikov pod dejstviem teplovykh nejtronov; Impurificacion por transmutacion y efectos de retroceso en los semiconductores expuestos a neutrones termicos

Energy Technology Data Exchange (ETDEWEB)

Crawford, Jr, J H; Cleland, J W [Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN (United States)

1962-01-15

) (gallium-71) pour chaque (arsenic-75 et selenium-77) ; en choisissant la dose d'exposition, on peut ramener la concentration electronique d'un germanium de type n a de tres faibles valeurs ou meme le transformer en un germanium de type p. La periode du gallium-71 est assez longue pour qu'il soit possible de suivre les details du par le coefficient de Hall et sa conductivite. Les experiences montrent aussi qu'environ un electron par neutron capture est elimine par des defauts de reseau crees par des noyaux de recul dont le deplacement resulte de l'emission de rayons gamma de capture. On peut rendre a ces atomes deplaces leur place normale dans le reseau en procedant a un recuit a environ 450 Degree-Sign C. D'autre part, les auteurs ont observe des effets de recul dans le silicium, deux porteurs de charge environ etant elimines a chaque capture. Ils examinent les consequences de ces resultats et des effets sur le germanium en ce qui concerne le spectre de rayons gamma de capture. Dans l'antimoniure d'indium, les rayons gamma emanant de l'indium-115 sont insuffisants pour deplacer un grand nombre de noyaux et l'effet principal est la production d'atomes d'etain-116, qui sont des lorsqu'ils remplacent des atomes d'indium. Les transmutations nucleaires provoquees ouvrent une voie nouvelle aux recherches sur de nombreux semi-conducteurs composes dans lesquels il est difficile d'introduire des impuretes par des moyens chimiques. (author) [Spanish] Los autores han estudiado muy extensamente la exposicion del germanio a neutrones termicos. Tres de los cinco isotopos de ese elemente se transmutan en impurezas quimicas; los rendimientos en atomos por 100 capturas neutronicas, y los periodos de semidesintegracion respectivos, son los siguientes: {sup 71}Ga - 30,4 - 11,4 dias; {sup 75}As - 9,8 - 82 minutos; {sup 77}Se - 1,2 - 39 horas. Por lo tanto, por cada donor ({sup 75}As y {sup 77}Se) se introducen aproximadamente tres aceptores

Thermal behavior of building materials based in woody fibers; Comportamiento termico de materiales constructivos a base de fibras lenosas

Energy Technology Data Exchange (ETDEWEB)

Flores Murrieta, Fernando E; Bojorquez Baez, Inocente; Llovera Esteban, Arturo; Hernandez Rodriguez, Jose [Universidad de Quintana Roo, Chetumal, Quintana Roo (Mexico); Perez Sanchez, Maria M [Universidad Autonoma de Yucatan, Merida (Mexico)

2000-07-01

A Test development to obtain the thermal conductivity and the study of thermal performance of building materials by a device of the Guarded Hot Plate (25 x 24.8 cm) according to standards ASTM C 518-91 and C 717-97, in a range of low temperatures (23-50 Celsius degrees) are presented in this work. The device consist of a structure whit: heat source system; heat dissipator system; plates and specimens fastener, and assembly of thermocouples and insulated plates. Subsequently in the experiments, will be necessary to reach a steady state to different temperatures for monitoring the thermal gradient. Another side, considering the electric power of the overall system and the modified Fouriers equation for two specimens, we can obtain the thermal conductivity, for instance: Plaster; woods and new materials based on woody fibers. [Spanish] En este trabajo se presenta el estudio del comportamiento termico y desarrollo de prueba de conductividad termica tanto en materiales de construccion como aquellos basado en fibras lenosas en un rango de bajas temperaturas (23-50 grados Celsius). De acuerdo con las normas ASTM C-518-91 y C-177-97, se utiliza un dispositivo de placa caliente guardada de 25 x 24.8 cm. que requiere de dos muestras identicas de especimenes diferentes colocadas entre una fuente de calor y una fuente fria aisladas termicamente. Se presenta el desarrollo experimental para determinar la conductividad termica en estado estacionario a varias temperaturas de operacion en materiales constructivos tales como: yeso, madera de pino y a base de fibra lenosa. Los dos primeros materiales se han utilizado como referencia en la comparacion de las propiedades termofisicas que aparecen en la bibliografia tecnica. Lo cual nos permite tener un buen grado de confiabilidad en el dispositivo utilizado en la determinacion de dichas propiedades.

Coupled hydrogen moderator optimization with ortho/para hydrogen ratio

International Nuclear Information System (INIS)

Kai, Tetsuya; Harada, Masahide; Teshigawara, Makoto; Watanabe, Noboru; Ikeda, Yujiro

2004-01-01

Neutronic performance of a coupled hydrogen moderator was studied as a function of para hydrogen concentration, moderator thickness and height, premoderator thickness, etc. for the J-PARC spallation neutron source. It was found that a thick (140 mm) moderator with 100% para-hydrogen was optimal to provide a high time- and energy-integrated neutron intensity below 15 meV and high pulse-peak intensities at lower energies. Distribution of the cold neutrons on a moderator viewed surface was studied and found to exhibit an intensity-enhanced region at the fringe part near the premoderator. This rather peculiar distribution suggested that the moderator and the viewed surface must be designed so as to take the full advantage of the brighter region near the premoderator

Comportamento termico de gorduras tecnicas produzidas no Brasil

OpenAIRE

Block, Jane Mara

1992-01-01

Dissertação (mestrado) - Universidade Federal de Santa Catarina. Centro de Ciencias Agrarias O mercado brasileiro de gorduras vegetais é constituído de ampla variedade de produtos hidrogenados para uso específico, principalmente a nível industrial. No presente trabalho, foram estudadas 6 amostras de bases hidrogenadas, 4 gorduras de uso geral, 2 gorduras para panificação, 2 gorduras para fritura, 1 gordura para sorvete, 2 gorduras para bombons, recheios e coberturas, 2 emulsões de uso ...

Adjoint P1 equations solution for neutron slowing down; Solucao das equacoes P1 adjuntas para moderacao de neutrons

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Cardoso, Carlos Eduardo Santos; Martinez, Aquilino Senra; Silva, Fernando Carvalho da [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Programa de Engenharia Nuclear

2002-07-01

In some applications of perturbation theory, it is necessary know the adjoint neutron flux, which is obtained by the solution of adjoint neutron diffusion equation. However, the multigroup constants used for this are weighted in only the direct neutron flux, from the solution of direct P1 equations. In this work, the adjoint P1 equations are derived by the neutron transport equation, the reversion operators rules and analogies between direct and adjoint parameters. The direct and adjoint neutron fluxes resulting from the solution of P{sub 1} equations were used to three different weighting processes, to obtain the macrogroup macroscopic cross sections. It was found out noticeable differences among them. (author)

Derivation of a volume-averaged neutron diffusion equation; Atomos para el desarrollo de Mexico

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Vazquez R, R.; Espinosa P, G. [UAM-Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, Mexico D.F. 09340 (Mexico); Morales S, Jaime B. [UNAM, Laboratorio de Analisis en Ingenieria de Reactores Nucleares, Paseo Cuauhnahuac 8532, Jiutepec, Morelos 62550 (Mexico)]. e-mail: rvr@xanum.uam.mx

2008-07-01

This paper presents a general theoretical analysis of the problem of neutron motion in a nuclear reactor, where large variations on neutron cross sections normally preclude the use of the classical neutron diffusion equation. A volume-averaged neutron diffusion equation is derived which includes correction terms to diffusion and nuclear reaction effects. A method is presented to determine closure-relationships for the volume-averaged neutron diffusion equation (e.g., effective neutron diffusivity). In order to describe the distribution of neutrons in a highly heterogeneous configuration, it was necessary to extend the classical neutron diffusion equation. Thus, the volume averaged diffusion equation include two corrections factor: the first correction is related with the absorption process of the neutron and the second correction is a contribution to the neutron diffusion, both parameters are related to neutron effects on the interface of a heterogeneous configuration. (Author)

Survey of Pulsed Neutron Source Methods for Multiplying Media; Methodes des Neutrons Pulses Pour l'Etude des Milieux Multiplicateurs; Obzor metodov s ispol'zovaniem istochnikov impul'snykh nejtronov dlya razmnozhayushchej sredy; Estudio Panoramico de los Metodos de Empleo de Fuentes de Neutrons Pulsados en Medios Multiplicadores

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Garelis, E. [General Electric Company, Vallecitos Atomic Laboratory, Pleasanton, CA (United States)

1965-10-15

-Small-L ). Il discute en outre l'emploi des methodes qui sont fondees sur la reponse a des impulsions pseudoaleatoires et utilisent une correlation entre l'entree et la sortie, pour la determination de la fonction de Green d'un milieu multiplicateur. H montre que les renseignements obtenus par ces methodes sont identiques a ceux fournis par les methodes de la source puisee a repetition, ce qui permet d'appliquer aux premieres les procedes qui ont ete mis au point pour les secondes. (author) [Spanish] En los ultimos afios ha habido dos tendencias principales acerca de la manera mas eficaz de medir la reactividad de parada, empleando fuentes de neutrones pulsados: la primera preconizaba el empleo de metodos tradicionales de medicion con fuentes neutronicas reiteradamente pulsadas, y la segunda propugnaba la aplicacion de metodos basados en una tecnica seudoaleatoria de respuesta a los impulsos, utilizando una correlacion entre los datos de entrada y los de salida. La informacion obtenida con una y otra tecnica es la misma; en teoria, ambos metodos sirven para determinar la funcion de respuesta. Se resefia el desarrollo de las tecnicas de empleo de fuentes de neutrones pulsados aplicadas a sistemas termicos con miras a medir la reactividad, desde los primeros intentos de Sjoestrand hasta el reciente metodo (k{beta}/ Script-Small-L ). Con el metodo usual de empleo de estas fuentes, la propiedad que se procuia determinar es la funcion de Green del conjunto subercritico empleado, es decir, la respuesta del reactor a una fuente de neutrones de funcion delta. El decrecimiento exponencial (e{sup {alpha}t}) de la funcion de Green proporciona una constante de decrecimiento de los neutrones instantaneos que es independiente del espacio. El autor examina los metodos para obtener el valor de la reactividad partiendo de la medida de a, como por ejemplo el metodo de la medicion de la criticidad por neutrones retardados a y el reciente metodo (k{beta}/ Script-Small-L ). Seguidamente examina el

Design of a system for neutrons dosimetry; Diseno de un sistema para dosimetria de neutrones

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Ceron, P.; Rivera, T. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Legaria No. 694, Col. Irrigacion, 11500 Mexico D. F. (Mexico); Paredes G, L. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Azorin, J. [Universidad Autonoma Metropolitana, Unidad Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, 09340 Mexico D. F. (Mexico); Sanchez, A. [IPN, Escuela Superior de Fisica y Matematicas, Av. Instituto Politecnico Nacional s/n, Col. San Pedro Zacatenco, 07738 Mexico D. F. (Mexico); Vega C, H. R., E-mail: victceronr@hotmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

2014-08-15

At the present time diverse systems of detection of neutrons exist, as proportional counters based on BF{sub 3}, He{sub 3} and spectrometers of Bonner spheres. However, the cost and the complexity of the implementation of these systems put them far from the reach for dosimetric purposes. For these reasons a system of neutrons detection composed by a medium paraffin moderator that forms a 4π (spheres) arrangement and of several couples of thermoluminescent dosimeters TLD 600/TLD 700. The response of the system presents a minor repeatability to 5% in several assays when being irradiated with a {sup 239}PuBe source and a deviation of 13.8% in the Tl readings of four different spheres. The calibration factor of the system with regard to the neutrons source which was of 56.2 p Sv/nc also was calculated. These detectors will be used as passive monitors of photoneutrons in a radiotherapy room with lineal accelerator of high energy. (Author)

Monitoring and assessment of thermical comfort in hygrothermically moderate offices and laboratories; Monitoraggio e valutazione del comfort termico negli ambienti di lavoro termoigrometricamente moderati

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Speranza, A. [ENEA, Centro Ricerche `Ezio Clementel`, Bologna (Italy). Dip. Ambiente

1998-12-31

This study reports the results of the micro climatic measurements carried out in some ENEA work environments. The work conditions in the surveyed areas, have been evaluated following welfare indexes or thermical comfort: PMV= Predicted Mean Vote (ISO recommendation 7730); PPD= Predicted Percentage of Dissatisfied (ISO recommendation 7730). [Italiano] In questo studio sono riportati i risultati delle misure microclimatiche eseguite in alcuni ambienti di lavoro dei centri ENEA di Bologna. Le condizioni di lavoro (delle zone che sono state sottoposte ad indagine) sono state valutate mediante i seguenti indici di benessere o `comfort` termico: Voto Medio Previsto (PMV= Predicted Mean Vote) - raccomandazione ISO 7730; Percentuale Prevista di Insoddisfatti (PPD= Predicted Percentage of Dissatisfied) - raccomandazione ISO 7730.

Monitoring and assessment of thermical comfort in hygrothermically moderate offices and laboratories; Monitoraggio e valutazione del comfort termico negli ambienti di lavoro termoigrometricamente moderati

Energy Technology Data Exchange (ETDEWEB)

Speranza, A [ENEA, Centro Ricerche ` Ezio Clementel` , Bologna (Italy). Dip. Ambiente

1999-12-31

This study reports the results of the micro climatic measurements carried out in some ENEA work environments. The work conditions in the surveyed areas, have been evaluated following welfare indexes or thermical comfort: PMV= Predicted Mean Vote (ISO recommendation 7730); PPD= Predicted Percentage of Dissatisfied (ISO recommendation 7730). [Italiano] In questo studio sono riportati i risultati delle misure microclimatiche eseguite in alcuni ambienti di lavoro dei centri ENEA di Bologna. Le condizioni di lavoro (delle zone che sono state sottoposte ad indagine) sono state valutate mediante i seguenti indici di benessere o `comfort` termico: Voto Medio Previsto (PMV= Predicted Mean Vote) - raccomandazione ISO 7730; Percentuale Prevista di Insoddisfatti (PPD= Predicted Percentage of Dissatisfied) - raccomandazione ISO 7730.

Mesh sensitivity in the thermal analysis of a gas turbine a blade with internal cooling; Sensibilidad de malla en el analisis termico de un alabe de turbina de gas con enfriamiento interno

Energy Technology Data Exchange (ETDEWEB)

Alfaro Ayala, Jorge Arturo; Gallegos Munoz, Armando [Facultad de Ingenieria Mecanica, Electrica y Electronica (FIMEE), Universidad de Guanajuato (Mexico); Campos Amezcua, Alfonso [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)

2007-11-15

This article presents the methodology to generate the mesh model of the computer model of a blade by means of commands in the software of CFD Fluent, mainly in the fluid zone, since a mesh sensitivity analysis becomes too expensive in terms of human and computer resources. When geometry is too irregular, modifications are required in the mesh to avoid problems such as the divergence, instability in the solution and the dependency on the results of temperature, pressure, velocity, etc. Such is the case of a blade with internal cooling of the first stage of a gas turbine. The results are included of the generated mesh as well as of the thermal analysis of the blade. Additionally the results of temperature, pressure and velocity of the combustion gases and of the cooling air are shown. [Spanish] Este articulo presenta la metodologia para generar el mallado del modelo computacional de un alabe por medio de comandos en el software de CFD Fluent, principalmente en la zona del fluido, ya que un analisis de sensibilidad de malla se vuelve demasiado costoso en terminos de recursos humanos y computacionales. Cuando la geometria es demasiado irregular, se requiere de modificaciones en la malla para evitar problemas como son la divergencia, inestabilidad en la solucion y la dependencia de los resultados de temperatura, presion, velocidad, etc. Tal es el caso de un alabe con enfriamiento interno de la primera etapa de una turbina de gas. Se incluyen los resultados tanto de la malla generada como del analisis termico del alabe. Adicionalmente se muestran los resultados de temperatura, presion y velocidad de los gases de la combustion y del aire de enfriamiento.

Scintillation Counters for Neutron Scattering Experiments; Compteurs a scintillations pour les experiences de diffusion neutronique; Stsintillyatsionnye schetchiki dlya ehksperimentov s rasseyaniem nejtronov; Contadores de centelleo para experimentos de dispersion neutronica.

Energy Technology Data Exchange (ETDEWEB)

Harris, D; Duffil, C [Atomic Energy of Canada Ltd., Chalk River, Ontario (Canada); Wraight, L A [Aere, Harwell, Didcot, Berks (United Kingdom)

1963-01-15

Scintillation counters discussed in this paper are of two types : (i) UP or B{sub 2}O{sub 3} fixed with zinc sulphide in varving composition, (ii) Li containing glasses of varying composition. The ideal composition of each rype for neutron scattering experiments and their relative sensitivity tae neutrons and {gamma}-rays are considered. The ZnS type can be used with a {gamma}-ray pulse shape discriminator and practical experience of its use in a multi-counter time-of-flight experiment is described. The Li glass has higher {gamma}-background but also higher neutron efficiency. Performance figures of a scintillator containing 25% by wt. Li{sub 2}O and 1 mm thick will be given. (author) [French] Les compteurs a scintillations etudies sont de deux types : i) LiF ou B{sub 2}O{sub 3} fixe par du sulfure de zinc en composition variable, ii) verres contenant du lithium en composition variable. Les auteurs examinent la composition ideale de chaque type de compteur pour les experiences de diffusion de neutrons, ainsi que leur sinsibilite rrelative aux neutrons et aux rayons gamma. On peut utiliser le compteur a ZnS avec un discriminates de forme pour rayons gamma; les auteurs decrivent l'experience qu'ils ont de son emploi dans une experience de temps de vol a plusieurs compteurs. Le compteur verre-Li a un mouvement propre plus eleve pour les rayons gamma mais une meilleure efficacite vis-a-vis des neutrons. Les auteurs donnent quelques chiffres concernant le fonctionnement d'un scintillateur contenant 25% en poids de Li{sub 2}O et ayant une epaisseur de un millimetre. (author) [Spanish] Los contadores de centelleo examinados en esta memoria son de dos tipos : a) de LiF o B{sub 2}O{sub 3} mezclado con sulfuro de cinc en proporciones variables; b) de vidrios litiados de diversas composiciones. Los autores estudian la composicion ideal de cada tipo para experimentos de dispersion neutronica, asi como su sensibilidad relativa a los neutrones y a los rayos gamma. El tio de Zn

Thermal responses and its relation with the building outdoor conditions; Respuestas termicas y su relacion con la envolvente del edificio

Energy Technology Data Exchange (ETDEWEB)

Marincic, Irene [Universidad de Sonora, Hermosillo, Sonora (Mexico); Isalgue, Antoni [Universidad Politecnica de Cataluna, Barcelona (Spain)

2000-07-01

In order to understand and to control the indoor thermal behavior in buildings, it is necessary to know the origin of the energies coming into and outside the building, identifying the geometric factors and physical properties, that can modify the thermal balance of the system. In this work, we analyze the thermal behavior of a building experimentally, related with its exterior conditions. Specifically, we analyze the thermal response indoors at different distances from the building envelope, which implies different thermal insulation situations. Supported on temperature measurements in a residential building, which is representative of local construction styles (adjacent other buildings), we analyze the thermal response effects depending on the distances between the considered points and the envelope and on the insulation between both. Applying a methodology based on experimental transfer functions of buildings, the thermal behavior in the temporary and frequency domains is evaluated. With this methodology, it is possible to visualize certain phenomena and to obtain thermal parameters that characterize the dynamic aspects of the thermal response. The main scope is to extract information from the building analysis, in order to extrapolate the behavior conclusions to a proper thermal design of similar constructions. From the thermal responses analysis at different spatial localization, we conclude that the distance from the building envelope (and also its properties) has a great influence on thermal inertia effects, which can modify importantly the thermal response. This phenomena has a parallelism with the skin effect of the magnetic fields penetration in conductors. The spatial localization implies a certain thermal mass involved in each case, which controls the penetration of exterior thermal oscillation. [Spanish] Para poder entender y controlar los comportamientos termicos en el interior de los edificios, es necesario conocer el origen de las energias que

Simply architecture or bioclimatic architecture?; Arquitectura bioclimatica o simplemente Arquitectura?

Energy Technology Data Exchange (ETDEWEB)

Rodriguez Torres, Juan Manuel [Universidad de Guanajuato (Mexico)

2006-10-15

The bioclimatic architecture is the one which profits from its position in the environment and its architectonic elements for the climate benefit. With the aim of reach the internal thermal comfort without using mechanical systems. This article states the story about this singular kind of architecture during centuries. And also emphasizes the sunlight utilization, in order to achieve the desired thermal well-being in edifications. [Spanish] El tipo de arquitectura que toma ventaja de su disposicion en el entorno y sus elementos arquitectonicos para el aprovechamiento del clima, con el fin de conseguir el confort termico interior sin utilizar sistemas mecanicos, se denomina bioclimatica. En este articulo se habla de la historia de este tipo tan singular de arquitectura con el paso de los siglos, y tambien se hace hincapie acerca de la luz solar, como un medio muy eficiente a traves del cual las edificaciones pueden ser disenadas para lograr el bienestar termico deseado.

System of adjoint P1 equations for neutron moderation; Sistema de equacoes P1 adjuntas para a moderacao de neutrons

Energy Technology Data Exchange (ETDEWEB)

Martinez, Aquilino Senra; Silva, Fernando Carvalho da; Cardoso, Carlos Eduardo Santos [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Programa de Engenharia Nuclear

2000-07-01

In some applications of perturbation theory, it is necessary know the adjoint neutron flux, which is obtained by the solution of adjoint neutron diffusion equation. However, the multigroup constants used for this are weighted in only the direct neutron flux, from the solution of direct P1 equations. In this work, this procedure is questioned and the adjoint P1 equations are derived by the neutron transport equation, the reversion operators rules and analogies between direct and adjoint parameters. (author)

A New Apparatus for Inelastic, Quasi-Elastic and Elastic Cold Neutron Measurements; Un nouveau appareil pour les mesures de diffusion inelastique , quasi-elastique et elastique des neutrons lents; Novyj pribor dlya izmereniya neuprugogo, kvaziuprugogo i uprugogo rasseyaniya kholodnykh nejtrohov; Nuevo aparato para mediciones inelastic as, cuasi elasticas y elasticas de neutrones frios

Energy Technology Data Exchange (ETDEWEB)

Otnes, K; Palevsky, H [Brookhaven National Laboratory, Upton, NY (United States)

1963-01-15

despersion de la longueur d'onde (largeur totale a mi-hauteur) seront respectivement de 16 {mu}s et 0,16 A pour des neutrons incidents ayant une longueur d'onde de 4 A; l'intensite de la bouffee sur l'echantillon (4 x 1,6 cm) sera de 2 x 10{sup 6} n/s pouf mesures de diffusion quasi-elastique et elastique, la configuration a trois rotors conviendra parfaitement. La duree de la bouffee et la dispersion de longueur d'onde correspondante peuvent atteindre des valeurs aussi faibles que 8 {mu}s et 0, 04 A, ce qui donne une intensite de 10{sup 4} n/s sur un echantillon de 4 x 0, 8 cm. La longueur d'onde et la resolution en temps peuvent etre ajustees entre les; deux limites susmentionnees, de maniere a obtenir l'intensite de flux maximum pour une experience determinee. (author) [Spanish] Se esta construyendo un nuevo selector mecanico destinado al reactor de flujo intenso de Brookhaven. El aparato es del tipo de tres elementos rotores en fase. Los rotores, de 80 cm de diametro, giran a una velo- cidad maxima de 15000 rev/min y se han disenado de modo que emitan tres rafagas de neutrones monocromaticos por revolucion. Dos de los rotores giran alrededor de un eje horizontal, mientras que el tercero lo hace verticalmente. El sistma puede funcionar con uno, dos or tres elementos selectores, segun el tipo de medicion que se quiera efectuar. Para las mediciones inelasticas en que los neutrones ganan energia, lo mas indicado es utilizar un sistema de dos rotores. En este sistema, la duracion de las rafagas sera de 16 {mu}s y el ensanchamiento de longitudes de onda (amplitud plena a la mitad del valor maximo) de 0,16 A para neutrones incidentes de 4 A; la intensidd en la muestra (4 x 1,6 cm) sera de 2 x 10{sup 6} n/s. para las mediciones cuasi elasticas y elasticas resultara mas apropiado el sistema de tres rotores. La duracion de las rafagas y el ensanchamiento de longitudes de onda pueden llegar a un minimo de 8 {mu}s y 0,04 A, respectivamente, lo que representa una intensidad de 10{sup

Metal temperature monitoring in corrosive gases at high temperature and high thermal flows; Monitoreo de temperaturas de metal en gases corrosivos a alta temperatura y altos flujos termicos

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Huerta Espino, Mario; Martinez Flores, Marco Antonio; Martinez Villafane, Alberto; Porcayo Calderon, Jesus; Gomez Guzman, Roberto; Reyes Cervantes, Fernando [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

1991-12-31

The direct measurement of metal temperatures during operation in superheater, reheater, and water wall tubes in zones exposed to high thermal flows is of great interest for the operation and analysis of the correct functioning of a steam generator. The operation temperature measurement of these zones differs very much of the monitored temperature in headers in the dead chamber, since the temperature measured in this zone is the steam temperature that does not reflect the one detected in the gas zone. For this reason, the thermocouples implant in gas zones will detect the real metal temperature and the incidence that some operation variables might have on it (Martinez et al., (1990). [Espanol] La medicion directa de temperaturas de metal durante operacion en tubos de sobrecalentador, recalentador y pared de agua en zonas expuestas a altos flujos termicos es de gran interes para la operacion y analisis del buen funcionamiento de un generador de vapor. La medicion de la temperatura de operacion de estas zonas, difiere mucho de la temperatura monitoreada en cabezales en zona de camara muerta, ya que la temperatura registrada en esta zona es la de vapor que no es un reflejo de la detectada en zona de gases. Por esta razon, la implantacion de termopares en zona de gases detectara la temperatura de metal real y la incidencia que algunas variables de operacion tengan sobre esta (Martinez et al., 1990).

Metal temperature monitoring in corrosive gases at high temperature and high thermal flows; Monitoreo de temperaturas de metal en gases corrosivos a alta temperatura y altos flujos termicos

Energy Technology Data Exchange (ETDEWEB)

Huerta Espino, Mario; Martinez Flores, Marco Antonio; Martinez Villafane, Alberto; Porcayo Calderon, Jesus; Gomez Guzman, Roberto; Reyes Cervantes, Fernando [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

1990-12-31

The direct measurement of metal temperatures during operation in superheater, reheater, and water wall tubes in zones exposed to high thermal flows is of great interest for the operation and analysis of the correct functioning of a steam generator. The operation temperature measurement of these zones differs very much of the monitored temperature in headers in the dead chamber, since the temperature measured in this zone is the steam temperature that does not reflect the one detected in the gas zone. For this reason, the thermocouples implant in gas zones will detect the real metal temperature and the incidence that some operation variables might have on it (Martinez et al., (1990). [Espanol] La medicion directa de temperaturas de metal durante operacion en tubos de sobrecalentador, recalentador y pared de agua en zonas expuestas a altos flujos termicos es de gran interes para la operacion y analisis del buen funcionamiento de un generador de vapor. La medicion de la temperatura de operacion de estas zonas, difiere mucho de la temperatura monitoreada en cabezales en zona de camara muerta, ya que la temperatura registrada en esta zona es la de vapor que no es un reflejo de la detectada en zona de gases. Por esta razon, la implantacion de termopares en zona de gases detectara la temperatura de metal real y la incidencia que algunas variables de operacion tengan sobre esta (Martinez et al., 1990).

Practical in-situ determination of ortho-para hydrogen ratios via fiber-optic based Raman spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Sutherland, Liese-Marie; Knudson, James N.; Mocko, Michal; Renneke, Richard M.

2016-02-21

An experiment was designed and developed to prototype a fiber-optic-based laser system, which measures the ratio of ortho-hydrogen to para-hydrogen in an operating neutron moderator system at the Los Alamos Neutron Science Center (LANSCE) spallation neutron source. Preliminary measurements resulted in an ortho to para ratio of 3.06:1, which is within acceptable agreement with the previously published ratio. The successful demonstration of Raman Spectroscopy for this measurement is expected to lead to a practical method that can be applied for similar in-situ measurements at operating neutron spallation sources.

Improved Techniques for Low-Flux Measurement of Prompt Neutron Lifetime, Conversion Ratio and Fast Spectra; Methodes Perfectionnees de Mesure de la Duree de Vie des Neutrons Instantanes, du Rapport de Conversion et des Spectres de Neutrons Rapides, dans un Reacteur a Bas Flux; Usovershenstvovannye metody izmereniya vremeni zhizni mgnovennykh nejtronov, koehffitsienta konversii i spektra bystrykh nejtronov pri slabykh potokakh nejtronov; Tecnicas Perfeccionadas para la Determinacion del Periodo de los Neutrones Inmediatos, la Razon de Conversion y los Espectros de Neutrones Rapidos, con Flujos Reducidos

Energy Technology Data Exchange (ETDEWEB)

Armani, R. J.; Bennett, E. F.; Brenner, M. W.; Bretscher, M. M.; Cohn, C. E.; Huber, R. J.; Kaufmann, S. G.; Redman, W. C. [Argonne National Laboratory, Argonne, IL (United States)

1964-02-15

medir este valor en un reactor de flujo reducido, pero se estan estudiando algunos que pueden servir a ese fin. Los autores resefian tres de las tecnicas que ofrecen mejores perspectivas. Los estudios realizados con el proposito de construit un espectrometro pequeflo para neutrones rapidos con buenas caracteristicas de estabilidad, poder de resolucion y sensibilidad, destinado a la medicion de espectros neutronicos dentro del reactor, en el intervalo energetico de las decenas o centenares de kilovoltios, se han concentrado en el empleo del analisis de la forma de los impulsos (con el fin de rechazar los sucesos iniciados por los rayos gamma en los contadores proporcionales de retroceso de hidtogeno) y el empleo de la colimacion en los detectores tipo sandwich, a base de {sup 6}LiF en un material solido, a fin de aumentar el poder de resolucion. Se ha construido cierto ndmero de instrumentes de este tipo y se esta estudiando la forma en que se comportan frente a los neutrones monocineticos y los neutrones de un reactor. Recurriendo a la tecnica de rechazo de los rayos gamma, se ha podido reducir varios cientos de veces la sensibilidad del contador de retroceso frente a dichos rayos y de esta manera, el limite inferior de aplicacion del instrumente se ha extendido por lo menos hasta los 30 keV. En cuanto a los instrumentes de semiconductors a base de {sup 6}Li, se han observado poderes de resolucion de hasta 70 keV de amplitud total en correspondencia con la mitad del maximo (1,5%) para la suma de los impulsos, en la irradiaeion con neutrones termicos. (author) [Russian] Pri osushhestvlenii programmy issledovanija reak- tora nulevoj moshhnosti (ZPR) primenjalis' razlichnye statisticheskie metody izmerenija ot- noshenija vremeni zhizni mgnovennyh nejtronov k doze zapazdyvajushhih nejtronov. Odin metod, a imenno analiz ''shuma'' reaktora s pomoshh'ju polosovogo fil'tra byl razrabotan v laboratorii, a drugie, naprimer izmerenie chastoty zapazdyvajushhih sovpadenij impul

Problems Associated with the Monochromatisation of Slow Neutrons; Quelques aspects de la monochromatisation des neutrons thermiques; Nekotorye voprosy monokhromatizatsii medlennykh nejtronov; Algunos problemas de la monocromatizacion de neutrones lentos

Energy Technology Data Exchange (ETDEWEB)

Vertebnyj, V P; Kolotyj, V V; Majstrenko, A N

1963-01-15

The paper sets out the result of calculations to determine the shape of the spectral line of twin-rotor, pulsing, slow-neutron monochromators, as a function of the shifts in the phases between the rotors. Consideration is also given to die possibility of using certain light elements as slow-neutron filters. (author) [French] Les auteurs exposent les resultats de leurs calculs relatifs a la forme du spectre des monochromateurs a impulsions et a deux rotors pour neutrons thermiques en fonction de la distance et du dephasage entre les rotors. Ils examinent egalement la possibilite d*utiliser certains elements legers comme filtres a neutrons lents. (author) [Spanish] Los autores exponen ios resultadas de sus calculos relativos a la forma de la linea espectral de los monocromadores pulsantes de dos rotores para neutrones lentos en funcion de la distancia y del desias amiento de los rotores. Examinan asimismo la posibilidad de utilizar algunos elementos ligeros como filtros de neutrones lentos. (author)

Neutronic studies on decoupled hydrogen moderator for a short-pulse spallation source

International Nuclear Information System (INIS)

Harada, Masahide; Watanabe, Noboru; Teshigawara, Makoto; Kai, Tetsuya; Ikeda, Yujiro

2005-01-01

Neutronic studies of decoupled hydrogen moderators were performed by calculations taking into account para hydrogen content, decoupling energy, moderator dimensions/shapes and reflector material. Low-energy parts of calculated spectral intensities with different para hydrogen contents were analyzed by a modified Maxwell function to characterize neutron spectra. The result shows that a 100% para hydrogen moderator gives the highest pulse peak intensity together with the narrowest pulse width and the shortest decay times. Pulse broadening with a reflector was explained by time distributions of source neutrons entering into the moderator through a decoupler. Material dependence of time distribution was studied. A decoupling energy higher than 1 eV does not bring about a large improvement in pulse widths and decay times, even at a large penalty in the peak intensity. The optimal moderator thickness was also discussed for a rectangular parallelepipe-shaped and a canteen-shaped moderator

Calculation of the temperature distribution and thermal stresses in a gas turbine nozzle cooled by air film; Calculo de la distribucion de temperaturas y esfuerzos termicos en una tobera de turbina de gas enfriada por pelicula de aire

Energy Technology Data Exchange (ETDEWEB)

Hernandez R, Alejandro; Garcia I, Rafael; Mazur C, Zdislaw [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)

2004-07-01

temperaturas. Con las temperaturas correctamente importadas, se realizaron las simulaciones para el calculo de los esfuerzos termicos en la tobera.

Qualification of the monitor Pug-7N like dosimeter for neutrons; Habilitacion del monitor PUG-7N como dosimetro para neutrones

Energy Technology Data Exchange (ETDEWEB)

Benites R, J. L. [Centro Estatal de Cancerologia de Nayarit, Av. Enfermeria, Fracc. Fray Junipero Serra, 63000 Tepic, Nayarit (Mexico); Vega C, H. R.; Murillo O, R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Velazquez F, J. B., E-mail: jlbenitesr@prodigy.net.mx [Universidad Autonoma de Nayarit, Postgrado CBAP, Carretera Tepic Compostela Km. 9, Xalisco, Nayarit (Mexico)

2011-10-15

By means of an inter-comparison method, the monitor for neutrons Pug-7N was enabled like dosimeter for neutrons of two magnitudes: the environmental equivalent dose, H*(10), and the H equivalent dose. The monitor Pug-7N has a plastic detector of scintillation Pns-20 that can be used inside or outside of its polyethylene cylindrical moderator. This designed to detect the neutrons presence that is shown in ana logical form by means of a fast count. Although the instrument is useful to detect the neutrons presence its design it does not allow to estimate the dose. With the purpose of enabling it as dosimeter for neutrons, their response was compared with the response of the area monitor for neutrons Bert hold Lb 6411 and Eberline NRD model Asp-1. Under the same irradiation conditions the 3 instruments were exposed to a source of {sup 241}AmBe of 3.7E(9) Bq (100 mCi) of activity whose spectrum and dosimetric magnitudes were determined with a spectrometric system of Bonner spheres with scintillator of {sup 6}Lil(Eu) and the NSDUAZ code. Conversion factors of H*(10)/cpm and H/cpm were obtained for the two options of the monitor detector Pug-7N, with this procedure the monitor Pug-7N besides determining the presence of neutrons, it has been enabled for their use as dosimeter for neutrons. (Author)

Evaluation of criteria of environmental fitness for popular houses of the low income sector to arid regions in Mexicali, Baja California; Evaluacion de criterios de adecuacion ambiental para la vivienda popular de sectores de bajos ingresos al clima calido extremo de Mexicali, B.C.

Energy Technology Data Exchange (ETDEWEB)

Corral Martinez, Maria [Universidad Autonoma de Baja California, Mexicali, Baja California (Mexico)

2000-07-01

The main purpose of this work is to present the impact on minimizing thermal loads, the traditional bioclimatic criteria commonly utilized on low income housing types in Mexicali, B.C., Mexico by showing the results of dynamic thermal evaluation based in the DOE 2.1e software as well as its technical description, with the purpose of providing recommendations for low income popular houses on arid regions, due to the high reduction percentages that can be obtained during summertime. Therefore, having the data obtained from the field as a starting point, the thermal problematic in popular housing is detected. A properties is chosen from a representative range of government supported housing types named progressive housing which are offered an financially available to the large low income popular sector in order to determine the thermal environmental function using the DOE 2.1e software and a gnomon analysis. To conclude evaluations showed that by integrating and applying traditional thermal and environmental strategies that are commonly used in this region, it is possible to reduce as much 50% of the annual cooling internal load, enhancing thermal comfort conditions in natural bioclimatic way. [Spanish] El objetivo de este trabajo es mostrar el impacto en la reduccion de la carga interna de enfriamiento, de los criterios de adecuacion ambiental que tradicionalmente se aplican en la vivienda de Mexicali, B.C., Mexico presentando los resultados de una evaluacion termica en estado dinamico con el programa DOE 2.1e y la descripcion tecnica de las mismas, con el proposito de hacer recomendaciones para la vivienda popular de bajos ingresos en zonas aridas. Para ello a partir de informacion de campo se detecta la existencia de problema termico en la vivienda popular. Se revisa un prototipo representativo de los programas oficiales de vivienda ofrecido a los sectores populares denominado vivienda progresiva, a fin de establecer el grado de adecuacion termico ambiental con el

Retention in Solid KIO{sub 3} Activated with Fast and Slow Neutrons; Retention dans KIO{sub 3} Solide Active par des Neutrons Rapides et des Neutrons Lents; 0423 0414 0415 0420 0416 0410 041d 0418 0415 0412 0422 0412 0415 0420 0414 041e 041c KIO{sub 3}, 0410 041a 0422 0418 0412 0418 0420 041e 0412 0410 041d 041d 041e 041c 0411 042b 0421 0422 0420 042b 041c 0418 0418 041c 0415 0414 041b 0415 041d 041d 042b 041c 0418 041d 0415 0418 0422 0420 041e 041d 0410 041c 0418 ; Retencion en KIO{sub 3} Solido Activado con Neutrones Rapidos y Lentos

Energy Technology Data Exchange (ETDEWEB)

Aten, A.H.W. Jr.; Lindner-Groen, M.; Lindner, L. [Instituut voor Kernphysisch Onderzoek, Amsterdam (Netherlands)

1965-04-15

cristal, y presentar caracteristicas identicas para los diferentes isotopos. Para comprobar estas hipotesis se ha realizado una serie de experimentos en los que se activo KIO{sub 3} solido con neutrones rapidos y termicos. En el caso de los neutrones rapidos, la retencion de {sup 128}I fue sensiblemente mayor que la de {sup 126}I, pero la retencion de {sup 128}I alcanzada con los neutrones termicos fue aun mas elevada que la obtenida con los neutrones rapidos. Este hecho indica que, aparte del esquema de desintegracion, la energia de retroceso tambien puede constituir un factor determinante de la retencion. Tambien difieren los efectos del recocido en el {sup 128}I y en el {sup 126}I (obtenidos ambos con neutrones rapidos). Por tratamiento postirradiatorio a temperaturas de hasta 100 Degree-Sign C, la retencion de ambos isotopos referida a la actividad total aumento en la misma proporcion, esto es, la diferencia de retencion permanecio constante. Por tanto, la parte de la fraccion de {sup 126}I reducida por el proceso de retroceso que excede de la fraccion de {sup 128}I reducida, resulta mucho menos afectada por el calentamiento que la fraccion reducida de ambos isotopos. Es evidente que solo un modelo bastante detallado permite explicar ese comportamiento quimico tan complicado del atomo radiactivo de retroceso. (author) [Russian] Prostaja model' vzaimodejstvij jader otdachi v tverdom tele predpolagaet, chto osnovnoe (neotozhzhennoe) uderzhanie dolzhno pokazat' izotopnye jeffekty (kotorye, verojatno, byli by svjazany so sposobom poteri jadrom produkta svoej izbytochnoj jadernoj jenergii) i chto jeto kolichestvo dolzhno byt' nechuvstvitel'nym k usloviju kristallicheskoj reshetki. S drugoj storony, otzhig v jetoj prostoj modeli dolzhen zaviset' ot uslovija (i predvaritel'noj obrabotki) kristalla, no pokazyvat' to zhe samoe povedenie dlja razlichnyh izotopov . Proverka jetih argumentov daetsja posredstvom provedenija serii opytov, v kotoryh tverdyj KJO{sub 3} aktivirovalsja

Diffusion Parameters of BeO by the Pulsed Neutron Method; Calcul des Parametres de Diffusion de BeO par la Methode des Neutrons Pulses; Opredelenie diffuzionnykh parametrov BeO s pomoshch'yu metoda impul'snykh nejtronov; Determinacion de los Parametros de Difusion en el BeO por el Metodo de los Neutrones Pulsados

Energy Technology Data Exchange (ETDEWEB)

Joshi, B. V.; Nargundkar, V. R.; Subbarao, K. [Atomic Energy Establishment Trombay, Bombay (India)

1965-08-15

la constante de decrecimiento, fue posible tener en cuenta toda actividad de fondo constante. Para evitar armonicos temporales se prescindio de los laplacianos de valor muy elevado. Se elimino el efecto de todo contenido armonico remanente mediante el empleo de un retardo adecuado. Se determino, para varios laplacianos, la constante de decrecimiento del modo fundamental de la poblacion de neutrones termicos. Los autores examinan las condiciones que han de satisfacerse para determinar con precision la constante C de enfriamiento por difusion. Los valores obtenidos para el BeO fueron los siguientes: {lambda}{sub 0} = constante de absorcion = 156, 02 {+-} 4,37 s{sup -1}, D = coeficiente de difusion = (1,3334 {+-} 0,0128) * 10{sup 5} cm{sup 2}/s, C = constante de enfriamiento por difusion = (-4,8758 {+-} 0,5846) * 10{sup 5} cm{sup 4}/s. Los autores calcularon el efecto de despreciar la influencia del termino B{sup 6} sobre la determinacion de los parametros de difusion, demostrando que es considerable. Atribuyen a ese efecto la persistente discrepancia entre los valores de C obtenido para el mismo moderador por distintos investigadores. (author) [Russian] Opisyvaetsja primenenie metoda impul'snyh nejtronov dlja toch- nogo opredelenija diffuzionnyh parametrov zamedlitelej. S pomoshh'ju jetogo metoda byli polucheny diffuzionnye parametry VeO. Impul'sy nejtronov poluchalis' s pomoshh'ju kas- kadnogo uskoritelja v rezul'tate pul'sirovanija istochnika ionov i ispol'zovanija reakcii Be (d, n). Detektorom sluzhil proporcional'nyj schetchik iz obogashhennogo grehftoristogo bora. Pokazano, chto pri pravil'nom vybore polozhenija i dliny schetchika, a takzhe polozhenija istochnika, mozhno ustranit' bol'shuju chast' prostranstvennyh garmonik. Ljuboj postojannyj fon mozhet byt' uchten pri raschete postojannoj raspada. Chtoby izbezhat' vremennyh garmo- nik, ochen' bol'shie laplasiany ne ispol'zovalis'. Vse ostavshiesja garmoniki byli svedeny na net blagodarja ispol'zovaniju pravil

Unperturbed moderator brightness in pulsed neutron sources

International Nuclear Information System (INIS)

Batkov, K.; Takibayev, A.; Zanini, L.; Mezei, F.

2013-01-01

The unperturbed neutron brightness of a moderator can be defined from the number of neutrons leaving the surface of a moderator completely surrounded by a reflector. Without openings for beam extraction, it is the maximum brightness that can be theoretically achieved in a moderator. The unperturbed brightness of a cylindrical cold moderator filled with pure para-H 2 was calculated using MCNPX; the moderator dimensions were optimised, for a fixed target and reflector geometry corresponding to the present concept for the ESS spallation source. This quantity does not depend on openings for beam extraction and therefore can be used for a first-round optimisation of a moderator, before effects due to beam openings are considered. We find that such an optimisation yields to a factor of 2 increase with respect to a conventional volume moderator, large enough to accommodate a viewed surface of 12×12 cm 2 : the unperturbed neutron brightness is maximum for a disc-shaped moderator of 15 cm diameter, 1.4 cm height. The reasons for this increase can be related to the properties of the scattering cross-section of para-H 2 , to the added reflector around the exit surface in the case of a compact moderator, and to a directionality effect. This large optimisation gain in the unperturbed brightness hints towards similar potentials for the perturbed neutron brightness, in particular in conjunction with advancing the optical quality of neutron delivery from the moderator to the sample, where by Liouville theorem the brightness is conserved over the beam trajectory, except for absorption and similar type losses

Non-Fick ian law for the neutron density current; Atomos para el desarrollo de Mexico

Energy Technology Data Exchange (ETDEWEB)

Espinosa P, G.; Vazquez R, R. [UAM-Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, Mexico D.F. 09340 (Mexico); Morales S, J. [UNAM, Laboratorio de Analisis en Ingenieria de Reactores Nucleares, Paseo Cuauhnahuac 8532, Jiutepec, Morelos 62550 (Mexico)]. e-mail: gepe@xanum.uam.mx

2008-07-01

In this paper, a fractional wave equation for the average neutron motion in a nuclear reactor is considered. This representation covers the full spectrum of the average neutron transport behavior, i.e., Fick ian and non-Fick ian effects. The fractional diffusion model retains the main dynamic characteristics of the neutron motion. The relaxation time associated with a rapid variation in the neutron flux contains an adjustable parameter, which can be manipulated to obtain the best representation of the neutron transport phenomena. (Author)

Measure of thermal neutron flux in the IPEN/MB-01 reactor using {sup 197} Au wire activation detectors; Medida do fluxo de neutrons termicos do reator IPEN/MB-01 com detectores de ativacao de fios de {sup 197} Au

Energy Technology Data Exchange (ETDEWEB)

Marques, Andre Luis Ferreira

1995-12-31

This dissertation has aimed at developing a neutron flux measurement technique by means of detectors activation analysis. The main task of this work was the implementation of this thermal neutron flux measurement technique, using gold wires as activation detectors in the IPEN/MB-01 reactor core. The neutron thermal flux spatial distribution was obtained by gold wire activation technique, with wire diameters of 0.125 mm and 0.250 mm in seven selected reactor experimental channels. The values of thermal flux were about 10{sup 9} neutrons/cm{sup 2}.s. This experiment has been the first one conducted with gold wires in the IPEN/MB-01 reactor, being this technique implemented for use by experiments in flux mapping of the core 73 refs., 60 figs., 31 tabs.

Measure of thermal neutron flux in the IPEN/MB-01 reactor using {sup 197} Au wire activation detectors; Medida do fluxo de neutrons termicos do reator IPEN/MB-01 com detectores de ativacao de fios de {sup 197} Au

Energy Technology Data Exchange (ETDEWEB)

Marques, Andre Luis Ferreira

1996-12-31

This dissertation has aimed at developing a neutron flux measurement technique by means of detectors activation analysis. The main task of this work was the implementation of this thermal neutron flux measurement technique, using gold wires as activation detectors in the IPEN/MB-01 reactor core. The neutron thermal flux spatial distribution was obtained by gold wire activation technique, with wire diameters of 0.125 mm and 0.250 mm in seven selected reactor experimental channels. The values of thermal flux were about 10{sup 9} neutrons/cm{sup 2}.s. This experiment has been the first one conducted with gold wires in the IPEN/MB-01 reactor, being this technique implemented for use by experiments in flux mapping of the core 73 refs., 60 figs., 31 tabs.

Accelerator-based neutron source and its future

International Nuclear Information System (INIS)

Kiyanagi, Yoshiaki

2008-01-01

Neutrons are useful tool for the material science and also for the industrial applications. Now, high intensity neutron sources based on MW class big accelerators are under commissioning in Japan, Japan Spallation Neutron Source (JSNS) at J-PARC and in the US, SNS. Such high power neutron sources required the moderators that can be used under high radiation field and also give high neutronic performance. We have been performing experimental and Monte Carlo simulation studies to develop the cold neutron moderator systems for the high power sources since it is becoming important for materials and life science. Hydrogen is the unique candidate at the present stage due to its high resistibility to the radiation. It was indicated the para hydrogen moderator gave a good neutronic performance by experimental results. On the other hand, in the future, low power neutron sources are recognized to be useful to perform sprouting experiments and to promote the neutron science. The moderator systems need a concept different from the high power source. Therefore, we studied neutronic performances of the mesitylene and the methane moderators to get high intensity in a definite area on the moderator surface. Single groove moderators were studied and optimal geometry and the intensity gain were obtained. The mesitylene moderator gave a rather good performance compared to the methane moderator. (author)

Energy consumption and the use of thermal insulating materials. A comparative analysis on the tendencies over the time; Consumo de energia y uso de aislamientos termicos - un analisis comparativo de tendencias en el tiempo

Energy Technology Data Exchange (ETDEWEB)

Ordonez C, Luis Felipe [Aislantes Minerales, S. A. de C. V. Mexico, D. F. (Mexico)

1994-12-31

positivas y son semejantes a las tendencias en el consumo de aislamientos termicos y a cifras semejantes de otros paises. El analisis de estas cifras nos permiten detectar si se pueden correlacionar los esfuerzos de ahorro de energia con el consumo de aislamientos termicos y con el nivel de vida de un pais (determinado por su ingreso per capita), y establecer un indice futuro de efectividad de conservacion de energia por el uso adecuado de materiales de espesor economico. El indice propuesto en esta ponencia sirve este proposito y nos arroja resultados interesantes. A lo largo de los anos recientes y como resultado del cambio en el nivel de industrializacion y de vida en Mexico, el consumo de energeticos ha aumentado en proporcion mayor al crecimiento de poblacion, tomando como base las cifras de 1980. En ese mismo periodo, el producto interno bruto per capita ha aumentado en proporcion tambien ligeramente menor al crecimiento poblacional. Esto significa que la cifra de Intensidad Energetica, definida como la proporcion de consumo de energeticos sobre el producto interno bruto, ha aumentado ligeramente en el mismo periodo en consideracion, significando que el pais se ha vuelto mas ineficiente en anos recientes. Al mismo tiempo, la capacidad de produccion de materiales aislantes termicos ha permanecido constante desde 1980 hasta principios de 1994. Esto compara desfavorablemente con todos los paises desarrollados, en los cuales la intensidad energetica ha disminuido considerablemente en los ultimos anos, al tiempo que la produccion de materiales aislantes termicos ha crecido a un ritmo de proporciones semejantes.

Cogeneration in a plywood factory; Sistema de cogeneracion en una planta maderera

Energy Technology Data Exchange (ETDEWEB)

Castelazo Hernandez, Arturo; Mendoza Arcaraz, Alfonso [Ultra Energia, S. A. de C. V. Naucalpan (Mexico)

1996-12-31

-calentar el aceite termico en un intercambiador de calor gases de escape-aceite termico. Debido a que los gases de escape del motor no contienen la suficiente energia para calentar el aceite termico a la temperatura deseada se utilizara una caldera de fluido termico que quema desperdicios de madera y corteza de arbol como combustible. 2. Generacion de energia electrica con una turbina de vapor a contrapresion. La salida del vapor a contrapresion se utilizara para calentar el aceite termico a traves de un intercambiador de calor vapor-aceite termico.

Cogeneration in a plywood factory; Sistema de cogeneracion en una planta maderera

Energy Technology Data Exchange (ETDEWEB)

Castelazo Hernandez, Arturo; Mendoza Arcaraz, Alfonso [Ultra Energia, S. A. de C. V. Naucalpan (Mexico)

1997-12-31

-calentar el aceite termico en un intercambiador de calor gases de escape-aceite termico. Debido a que los gases de escape del motor no contienen la suficiente energia para calentar el aceite termico a la temperatura deseada se utilizara una caldera de fluido termico que quema desperdicios de madera y corteza de arbol como combustible. 2. Generacion de energia electrica con una turbina de vapor a contrapresion. La salida del vapor a contrapresion se utilizara para calentar el aceite termico a traves de un intercambiador de calor vapor-aceite termico.

Anti mutagenesis of chemical modulators against damage induced by reactor thermal neutrons; Antimutagenesis de moduladores quimicos contra el dano inducido por neutrones termicos de reactor

Energy Technology Data Exchange (ETDEWEB)

Zambrano A, F.; Guzman R, J.; Garcia B, A.; Paredes G, L.; Delfin L, A. [Instituto Nacional de Investigaciones Nucleares, Departamentos de Materiales Radiactivos, de Biologia, del Reactor y Gerencia de Aplicaciones Nucleares en la Salud, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

1999-07-01

The mutations are changes in the genetic information whether for spontaneous form or induced by the exposure of the genetic material to certain agents, called mutagens: chemical or physical (diverse types of radiations). As well as exist a great variety of mutagens and pro mutagens (these last are agents which transform themselves in mutagens after the metabolic activation). Also several chemical compounds exist which are called antimutagens because they reduce the mutagens effect. The C vitamin or ascorbic acid (A A) presents antimutagenic and anti carcinogenic properties. On the other hand a sodium/copper salt derived from chlorophyll belonging to the porphyrin group (C L) contains a chelated metal ion in the center of molecule. It is also an antioxidant, antimutagenic and anti carcinogenic compound, it is called chlorophyllin. The objective of this work is to establish if the A A or the C L will reduce the damages induced by thermal and fast reactor neutrons. (Author)

Criteria to determine the depth of the production interval in wells of the Cerro Prieto geothermal field, Mexico; Criterios para determinar la profundidad del intervalo productor en pozos del campo geotermico de Cerro Prieto, Mexico

Energy Technology Data Exchange (ETDEWEB)

Leon Vivar, Jesus Saul de [Comision Federal de Electricidad, Residencia General de Cerro Prieto, Mexicali, B.C. (Mexico)]. E-mail: jesus.deleon@cfe.gob.mx

2006-07-15

Ways to select the depth of the production interval or to complete wells in the Cerro Prieto geothermal field have changed during the development of the field. From 1961 when drilling began to the middle of 2005, a total of 325 wells were drilled. The paper compares the approaches used in the past with those of the last ten years. The Cerro Prieto system has been classified as being of liquid-dominated and high-temperature. Today, after 33 years of commercial exploitation, it has experienced a series of thermal and geochemical fluid changes making it necessary to modify the ways to select the depth of the well production intervals, according to the observed behavior of the reservoir. The new criteria include the thermal approach, the geological approach, the geochemical approach and a comparative approach with neighboring wells. If most of these criteria are interpreted correctly, the success of a well is ensured. [Spanish] Los criterios para seleccionar la profundidad del intervalo productor o la terminacion de los pozos en el campo geotermico de Cerro Prieto han cambiado durante el desarrollo del mismo. De 1961, cuando se perforaron los primeros pozos, hasta mediados del 2005 se han perforado un total de 325 pozos. En el presente articulo se hara una breve revision de cuales han sido los criterios usados en el pasado y los que se han venido empleando en los ultimos diez anos. El yacimiento de Cerro Prieto ha sido clasificado como de liquido dominante, de alta temperatura, pero actualmente, despues de 33 anos de explotacion comercial, ha sufrido una serie de cambios termicos y geoquimicos en sus fluidos, por lo que ha sido necesario modificar los criterios para seleccionar la profundidad del intervalo productor de los pozos de acuerdo al comportamiento observado en el yacimiento. Los criterios actuales se dividen en cuatro: 1. Criterio termico, 2. Criterio geologico, 3. Criterio geoquimico y 4. Criterio comparativo de los pozos vecinos. Cuando la mayoria de estos

Dosimetric evaluation of spectrophotometric response of alanine gel solution for gamma, photons, electrons and thermal neutrons radiations; Avaliacao dosimetrica da resposta espectrofotometrica da solucao gel de alanina para radiacao gama, de fotons, de eletrons e de neutrons termicos

Energy Technology Data Exchange (ETDEWEB)

Silva, Cleber Feijo

2009-07-01

Alanine Gel Dosimeter is a new gel material developed at IPEN that presents significant improvement on Alanine system developed by Costa. The DL-Alanine (C{sub 3}H{sub 7}NO{sub 2}) is an amino acid tissue equivalent that improves the production of ferric ions in the solution. This work aims to analyse the main dosimetric characteristics this new gel material for future application to measure dose distribution. The performance of Alanine gel solution was evaluated to gamma, photons, electrons and thermal neutrons radiations using the spectrophotometry technique. According to the obtained results for the different studied radiation types, the reproducibility intra-batches and inter-batches is better than 4% and 5%, respectively. The dose response presents a linear behavior in the studied dose range. The response dependence as a function of dose rate and incident energy is better 2% and 3%, respectively. The lower detectable dose is 0.1 Gy. The obtained results indicate that the Alanine gel dosimeter presents good performance and can be useful as an alternative dosimeter in the radiotherapy area, using MRI technique for tridimensional dose distribution evaluation. (author)

Second law characterization of stratified thermal storage tanks

Energy Technology Data Exchange (ETDEWEB)

Fraidenraich, N [Departamento de Energia Nuclear-UFPE (Brazil)

2000-07-01

de la primera ley de la termodinamica no existe diferencia entre los tanques de almacenamiento con la misma masa y temperatura promedio aun si tienen diferentes estructuras termicas estratificadas. No obstante la energia termica util que puede obtenerse de ellos puede diferir significativamente. En este trabajo derivamos una expresion capaz de caracterizar la configuracion estratificada del fluido termico. Usando los resultados obtenidos mediante la termodinamica de procesos irreversibles, este procedimiento adoptado consiste en calcular el maximo trabajo que se puede obtener de la capa termica que el tanque es capaz de desarrollar. Llegamos entonces a una expresion adimensional, el parametro de estratificacion (SP) que depende de la fraccion de masa y de la temperatura absoluta de cada termica asi como tambien la temperatura promedio del fluido termico. Se dan ejemplos numericos para diferentes tipos de estratificacion en el tanque y se verifica que la expresion obtenida es sensible a pequenas diferencias en la configuracion del almacenamiento termico. Por ejemplo un almacenamiento con temperaturas iguales a 74, 64 y 54 grados Celsius con su masa igualmente distribuida a lo largo del tanque rinde para el parametro SP una cifra igual a 0.000294. Por otra parte un tanque de almacenamiento con la misma temperatura promedio pero con diferentes temperaturas de las capas 76, 64, y 52 grados Celsius, tambien con distribucion uniforme de masa, rinde para SP un valor igual a la evaluacion cuantitativa de la estructura de estratificacion de almacenamientos termicos.

Cold neutron source conceptual designing for Tehran Research Reactor

International Nuclear Information System (INIS)

Khajvand, N.; Mirvakili, S.M.; Faghihi, F.

2016-01-01

Highlights: • Cold neutron source conceptual designing for Tehran research reactor is carried out. • Type and geometry of moderator and dimensions of cold neutron source are analyzed. • Liquid hydrogen with more ortho-concentration can be better option as moderator. - Abstract: A cold neutron source (CNS) conceptual designing for the Tehran Research Reactor (TRR) were carried out using MCNPX code. In this study, a horizontal beam tube of the core which has appropriate the highest thermal flux is selected and parametric analysis to choose the type and geometry of the moderator, and the required CNS dimensions for maximizing the cold neutron production was performed. In this design the moderator cell has a spherical annulus structure, and the cold neutron flux and its brightness are calculated together with the nuclear heat load of the CNS for a variety of materials including liquid hydrogen, liquid deuterium, and solid methane. Based on our study, liquid hydrogen with more ortho-concentration than para and solid methane are the best options.

Integrating techniques for neutron dosimetry in Linac 18 MV; Integrando tecnicas para dosimetria de neutrones en un Linac de 18 MV

Energy Technology Data Exchange (ETDEWEB)

Ceron R, P. V.; Diaz G, J. A. I.; Rivera M, T. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria 694, 11500 Mexico D. F. (Mexico); Paredes G, L. C. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas, Zac. (Mexico)

2015-10-15

In this paper thermoluminescent dosimetry, analytical techniques and Monte Carlo calculations were used to estimate the neutron dose equivalent in a radiotherapy room with a linear electron accelerator of 18 MV. The equivalent dose was measured at isocenter to 1.42 m of target and at the entrance of the labyrinth of the room of a Novalis Tx. The neutron detectors were constructed with pairs of thermoluminescent dosimeters TLD 600 ({sup 6}LiF: Mg, Ti) and TLD 700 ({sup 7}LiF: Mg, Ti) which are placed inside a paraffin sphere of 20 cm in diameter. These measurements enabled the calculation of equivalent dose in the gate and the source term, using the relationships contained in the NCRP-151. Through the models carried out with the code MCNPX the absorbed dose distribution with regard to depth in a paraffin phantom are included and the neutron spectrum produced by the head, taking into account the geometry and component materials. The results are in the order of neutron milli sievert by gray of X-rays (mSv/Gy x) which are in the same order as those found in other reports for different accelerators. (Author)

RBE of Monoenergetic Fast Neutrons: Cytogenetic Effects in Maize; EBR des Neutrons Rapides Monoenergeniques: Effets Cytogenetiques sur le Mais; Obeh monoehnergeticheskikh bystrykh nejtronov: tsitogeneticheskie izmeneniya u kukuruzy; EBR de los Neutrones Rapidos Monoenergeticos: Efectos Citogeneticos en el Maiz

Energy Technology Data Exchange (ETDEWEB)

Smith, H. H.; Bateman, J. L.; Quastler, H.; Rossi, H. H. [Biology and Medical Departments, Brookhaven National Laboratory, Upton, NY (United States)

1964-05-15

secteurs mutants g{sub 2}. (author) [Spanish] La variedad de maiz utilizada en los experimentos descritos presenta la ventaja, desde el punto de vista del estudio de la EBR, de proporcionar una curva dosis-respuesta que es basicamente de primer grado, tanto para las radiaciones de TLE elevada como para las de TLE baja. Los autores emplearon un aparato de exposicion que produce intensidades de dosis esencialmente iguales en cinco anillos de semillas colocadas de modo que intercepten a los neutrones de 0,43, 0,65, 1,00 1,50 y 1,80 MeV. Se supone que los sectores mutantes producidos en las hojas se deben en su mayor parte a una simple ruptura y eliminacion de cromosomas. Se realizaron experimentos con dosis adecuadas para obtener respuestas lineales, inferiores al valor de saturacion, y tales que los intervalos correspondientes a los neutrones rapidos monoenergeticos y a los rayos X de 250 kVp se superpongan parcialmente. Los valores de la EBR calculados a base de las pendientes comparadas de las curvas de regresion de primer grado para los neutrones y los rayos X respectivamente, varian entre 42 y 135, con una media global del orden'de 70. De todos los neutrones rapidos utilizados en los experimentos, los mas eficaces para producir sectores mutantes g{sub 2} fueron los de 0,43 MeV. (author) [Russian] Kukuruza, ispol'zovannaja v jetih jeksperimentah, obladaet preimushhestvom dlja izuchenija OBJe pri poluchenii krivoj pervogo porjadka zavisimosti reakcii ot dozy dlja izuchenij s nizkim i vysokim LPJe. Primenjalas' ustanovka dlja obluchenija, kotoraja obespechivala po sushhestvu ravnye moshhnosti doz dlja raspolozhennyh v kol'cevom porjadke pjati rjadov semjan pri obluchenii nejtronami s jenergiej 0,43, 0,65, 1,00, 1,50 i 1,80 Mjev. Sektory mutantov, poluchaemye v list'jah, kak polagajut, dolzhny, glavnym obrazom, uproshhat' razryv i uterju hromosom. Byli provedeny jeksperimenty pri urovnjah doz, kotorye vyzyvali otvetnye reakcii s linejnoj zavisimost'ju nizhe urovnja

A FORTRAN program for the use of digital terrain elevation models of the Instituto Nacional de Estadistica, Geografia e Informatica of Mexico (INEGI); Programa en FORTRAN para el manejo de modelos digitales de elevacion del terreno del Instituto Nacional de Estadistica, Geografia e Informatica de Mexico (INEGI)

Energy Technology Data Exchange (ETDEWEB)

Garcia Estrada, Gerardo [Gerencia de Proyectos Geotermoelectricos de la Comision Federal de Electricidad, Morelia (Mexico)

1996-09-01

producir un mapa en coordenadas planas rectangulares en metros. Durante la delimitacion de la ventana se hace un filtrado simple para disminuir los errores numericos que existen en el archivo y si se desea puede elegirse un submuestreo de los datos para preparar mapas menos detallados pero de gran cobertura. El programa ha sido desarrollado y probado extensamente en la Gerencia de Proyectos Geotermoelectricos de la Comision Federal de Electricidad (CFE) de Mexico, en donde se utiliza en estudios regionales para la elaboracion de mapas base, el trazo automatico de perfiles topograficos y el calculo de condiciones de frontera para modelos termicos. Otros usos directos son el calculo de las correcciones por rugosidad o la estimacion de efectos isostaticos en estudios gravimetricos, la estimacion de cotas topograficas para puntos de coordenadas horizontales conocidas, el modelado termico de efectos climaticos en funcion de la topografia, el calculo automatico de volumenes de material y muchos otros.

Procedure to measure the neutrons spectrum around a lineal accelerator for radiotherapy; Procedimiento para medir el espectro de los neutrones en torno a un acelerador lineal para radioterapia

Energy Technology Data Exchange (ETDEWEB)

Vega C, H. R.; Hernandez D, V. M.; Letechipia de L, C. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98060 Zacatecas (Mexico); Benites R, J. L. [Servicios de Salud de Nayarit, Centro Estatal de Cancerologia, Calzada de la Cruz 116 Sur, 63000 Tepic, Nayarit (Mexico); Salas L, M. A., E-mail: fermineutron@yahoo.com [Universidad Autonoma de Zacatecas, Unidad Academica de Agronomia, Apdo. Postal 336, 98000 Zacatecas (Mexico)

2013-10-15

An experimental procedure was developed, by means of Bonner spheres, to measure the neutrons spectrum around Linacs of medical use that only requires of a single shot of the accelerator; to this procedure we denominate Planetary or Isocentric method. One of the problems associated to the neutrons spectrum measurement in a radiotherapy room with lineal accelerator is because inside the room a mixed, intense and pulsed radiation field takes place affecting the detection systems based on active detector; this situation is solved using a passive detector. In the case of the Bonner spheres spectrometer the active detector has been substituted by activation detectors, trace detectors or thermoluminescent dosimeters. This spectrometer uses several spheres that are situated one at a time in the measurement point, this way to have the complete measurements group the accelerator should be operated, under the same conditions, so many times like spheres have the spectrometer, this activity can consume a long time and in occasions due to the work load of Linac to complicate the measurement process too. The procedure developed in this work consisted on to situate all the spectrometer spheres at the same time and to make the reading by means of a single shot, to be able to apply this procedure, is necessary that before the measurements two characteristics are evaluated: the cross-talking of the spheres and the symmetry conditions of the neutron field. This method has been applied to determine the photo-neutrons spectrum produced by a lineal accelerator of medical use Varian ix of 15 MV to 100 cm of the isocenter located to 5 cm of depth of a solid water mannequin of 30 x 30 x 15 cm. The spectrum was used to determine the total flow and the environmental dose equivalent. (Author)

Evolutionary neural networks: a new alternative for neutron spectrometry; Redes neuronales evolutivas: una nueva alternativa para la espectrometria de neutrones

Energy Technology Data Exchange (ETDEWEB)

Ortiz R, J. M. [Departamento de Electrotecnia y Electronica, Escuela Politecnica Superior, Av. Menendez Pidal s/n, 14004 Cordoba (Spain); Martinez B, M. R.; Vega C, H. R. [Unidad Academica de Estudios Nucleares, Universidad Autonoma de Zacatecas, Cipres 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Galleo, E. [Departamento de Ingenieria Nuclear, Universidad Politecnica de Madrid, Jose Gutierrez Abascal 2, 28006 Madrid (Spain)], e-mail: morvymm@yahoo.com.mx

2009-10-15

A device used to perform neutron spectroscopy is the system known as a system of Bonner spheres spectrometer, this system has some disadvantages, one of these is the need for reconstruction using a code that is based on an iterative reconstruction algorithm, whose greater inconvenience is the need for a initial spectrum, as close as possible to the spectrum that is desired to avoid this inconvenience has been reported several procedures in reconstruction, combined with various types of experimental methods, based on artificial intelligence technology how genetic algorithms, artificial neural networks and hybrid systems evolved artificial neural networks using genetic algorithms. This paper analyzes the intersection of neural networks and evolutionary algorithms applied in the neutron spectroscopy and dosimetry. Due to this is an emerging technology, there are not tools for doing analysis of the obtained results, by what this paper presents a computing tool to analyze the neutron spectra and the equivalent doses obtained through the hybrid technology of neural networks and genetic algorithms. The toolmaker offers a user graphical environment, friendly and easy to operate. (author)

Methods of Particle Detection in Free Neutron Decay; Methode de detection des particules dans une desintegration de neutrons libres; Metod obnaruzheniya chastits pri raspade svobodnogo nejtrona; Metodo para la deteccion de particulas en la desintegracion de neutrones libres

Energy Technology Data Exchange (ETDEWEB)

Novey, T B [Argonne National Laboratory, Lemont, IL (United States)

1960-06-15

aboutir a un multiplicateur ordinaire a 10 etages et ses chicanes d'entree pour resolution angulaire. 4. Le systeme electronique qui isole dans les detecteurs les impulsions venant des detecteurs et ayant les caracteristiques voulues de frequence, de retard relatif et d'amplitude et permet ainsi d'identifier la des- integration d'un neutron. (author) [Spanish] En el Laboratorio de Argonne se ha llevado a cabo recientemente una serie de estudios experimentales sobre la desintegracion de neutrones polarizados, con el fin de elucidar las modalidades de la interaccion nuclear a bajas energias. Estos estudios han consistido en mediciones de la distribucion angular de electrones y protones con respecto al sentido del spin de los neutrones libres que sufren la desintegracion. Los componentes fundamentales del aparato que el autor describe en la memoria son: 1. Un espejo de hierro y cobalto, de un metro, que selecciona un haz de neutrones altamente polarizados y permite determinar el grado de polarizacion aplicando distintos procedimientos . 2. El detector de electrones, consistente en un mosaico de cristales de antraceno de 10 cm de diametro y 6 mm de espesor, y en un dispositivo de canalizacion luminosa. 3. El detector de protones, formado por un sistema multiplicador de electrones de 14 etapas, la primera de las cuales con una abertura de 15x15 cm, que va disminuyendo en cuatro pasos hasta una estructura multiplicadora usual de 10 etapas, y sus deflectores de entrada para lograr la resolucion angular. 4. El sistema electronico que selecciona los impulsos que, al ser adecuados los intervalos con que se suceden, su defasaje en tiempo y su amplitud, hacen posible la identificacion de una desintegracion neutronica. (author) [Russian] Nedavno Argonnskoj gruppoj byl zavershen ryad ehksperimental'nykh issledovanij po raspadu polyarizovannykh nejtronov s tem, chtoby prolit'svet na strukturu slabogo yadernogo vzaimodejstviya. EHti issledovaniya nosili formu izmereniya uglovykh

Calculations of neutron spectra after neutron-neutron scattering

Energy Technology Data Exchange (ETDEWEB)

Crawford, B E [Gettysburg College, Box 405, Gettysburg, PA 17325 (United States); Stephenson, S L [Gettysburg College, Box 405, Gettysburg, PA 17325 (United States); Howell, C R [Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Mitchell, G E [North Carolina State University, Raleigh, NC 27695-8202 (United States); Tornow, W [Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Furman, W I [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Lychagin, E V [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Muzichka, A Yu [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Nekhaev, G V [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Strelkov, A V [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Sharapov, E I [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Shvetsov, V N [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation)

2004-09-01

A direct neutron-neutron scattering length, a{sub nn}, measurement with the goal of 3% accuracy (0.5 fm) is under preparation at the aperiodic pulsed reactor YAGUAR. A direct measurement of a{sub nn} will not only help resolve conflicting results of a{sub nn} by indirect means, but also in comparison to the proton-proton scattering length, a{sub pp}, shed light on the charge-symmetry of the nuclear force. We discuss in detail the analysis of the nn-scattering data in terms of a simple analytical expression. We also discuss calibration measurements using the time-of-flight spectra of neutrons scattered on He and Ar gases and the neutron activation technique. In particular, we calculate the neutron velocity and time-of-flight spectra after scattering neutrons on neutrons and after scattering neutrons on He and Ar atoms for the proposed experimental geometry, using a realistic neutron flux spectrum-Maxwellian plus epithermal tail. The shape of the neutron spectrum after scattering is appreciably different from the initial spectrum, due to collisions between thermal-thermal and thermal-epithermal neutrons. At the same time, the integral over the Maxwellian part of the realistic scattering spectrum differs by only about 6 per cent from that of a pure Maxwellian nn-scattering spectrum.

The Control of Fast Reactors: Current Methods and Future Prospects; Controle des Reacteurs a Neutrons Rapides. Methodes Actuelles et Perspectives d'Avenir; Upravlenie reaktorami na bystrykh nejtronakh. sushchestvuyushchie metody i dal'nejshie perspektivy; Control de Reactores Rapidos: Metodos Actuales y Perspectivas

Energy Technology Data Exchange (ETDEWEB)

Loewenstein, W. B. [Argonne National Laboratory, IL (United States)

1964-06-15

pour determiner leurs effets sur la quantite de reactivite qu'il faut donner aux barres de controle. Les methodes utilisees pour la prevision de l'efficacite des mecanismes de controle ont evolue: au debut, il s'agissait d'evaluations approximatives; on fait maintenant des calculs tout a fait surs que peuvent confirmer les donnees experimentales obtenues grace aux assemblages critiques. L'auteur indique dans ce memoire certains resultats experimentaux et expose les methodes analytiques sflres que l'on emploie couramment. Les experiences critiques portant sur la generation actuelle de reacteurs a neutrons rapides ont comporte de nombreuses recherches concernant l'efficacite de leur mecanisme de commande, ainsi que des experiences a la peripherie du coeur pour l'etude de reacteurs perfectionnes ayant un coeur d'un plus grand volume. L'auteur mentionne des etudes analytiques preliminaires qui montrent qu'il ne faudra peut-etre pas proceder dans l'avenir a des recherches experimentales detaillees sur maquette. (author) [Spanish] El autor examina los aspectos practicos del problema consistente en obtener una reactividad suficiente para el control de los reactores de neutrones rapidos, control que es muy diferente del utilizado en los sistemas de neutrones termicos. Las diferencias se deben en primer lugar a los valores relativamente pequenos de las secciones eficaces para los neutrones rapidos. En un sistema de neutrones rapidos no hay venenos fuertes. Como consecuencia, los fuertes venenos de fision (por ejemplo, el Xe y el Sm) en los reactores termicos exigen un exceso de reactividad mucho menor que la perdida de reactividad causada por la destruccion del material fisionable por fision y captura. Como las secciones eficaces del espectro de neutrones rapidos son relativamente pequenas comparadas con las correspondientes a los neutrones termicos, la densidad atomica del material desempena un papel importante al elegir los materiales de las barras de control. El autor

Characterization of film-converter screens systems for neutron radiography; Caracterizacao de sistemas filme-conversor para radiografia com neutrons

Energy Technology Data Exchange (ETDEWEB)

Andrade, Marcos Leandro Garcia

2002-07-01

In general a good quality radiography is that one able to furnish high contrast and sharp edge images. Technically 'high contrast' means high capability to discern material thickness and 'sharp edges', high resolution power. In the present work the optimal conditions to obtain neutron radiography images by using the following film-converter screen systems, Kodak-AA/Gd vaporated; Kodak-AA/Gd metallic; Kodak-AA/LiF; Min-R/GdS{sub 2}O{sub 4}, have been determined. The irradiations were performed in a radiographic facility which was designed and constructed by the neutron radiography working group and is installed at the beamhole 08 of the IEA-R1 nuclear research reactor of the IPEN-CNEN/SP. In order to determine such conditions, the start point was to evaluate the neutron exposure interval for which the optical contrast is maximal and so quantify the sensitivity or capability to discern material thickness, as well as the spatial resolution achieved in the radiographic image, for these systems. The best results have been obtained for the Kodak-AA/Gd vaporated system which is able to discern, for example, 0,024 cm of lucite, with a maximal resolution of 22{mu}m. The radiography images presently obtained in IPEN-CNEN/SP have similar quality when compared to the ones from several other research centers, around the world, whose making use of the same film-converter screens systems. (author)

Scattering of Neutrons by Liquid Bromine; Diffusion des neutrons par le brome liquide; R; Dispersion de neutrones por bromo liquido

Energy Technology Data Exchange (ETDEWEB)

Coote, G E; Haywood, B C [Atomic Energy of Canada Ltd., Chalk River, Ontario (Canada)

1963-01-15

energetica de los neutrones dispersos fue medida para angulos comprendidos entre 10{sup o} y 160{sup o}, mediante el metodo del tiempo de vuelo. La distribucion angular cbnfirma los resultados obtenidos en un estudio anterior por Caglioti. Los espectros fueron expresados en la forma correspondiente a la ''ley de dispersion'' S({alpha},{beta}) de Egelstaff y analizados para derivar la distribucion generalizada de frecuencias p({beta}) de los movimientos atomicos en el liquido. La funcion p({beta}) tiene un pico poco pronunciado, cuyo maximo corresponde a {beta}{approx}0,3 y no parece presentar saltos en el intervalo 0 < {beta} < 0,8 medido; la forma general de la curva confirma la descripcion del liquido como ''cuasi-cristalino''. Los autores examinan las dificultades que presenta la normalizacion absoluta de la funcion p({beta}). (author)

RAMA Methodology for the Calculation of Neutron Fluence; Metodologia RAMA para el Calculo de la Fluencia Neutronica

Energy Technology Data Exchange (ETDEWEB)

Villescas, G.; Corchon, F.

2013-07-01

he neutron fluence plays an important role in the study of the structural integrity of the reactor vessel after a certain time of neutron irradiation. The NRC defined in the Regulatory Guide 1.190, the way must be estimated neutron fluence, including uncertainty analysis of the validation process (creep uncertainty is ? 20%). TRANSWARE Enterprises Inc. developed a methodology for calculating the neutron flux, 1,190 based guide, known as RAMA. Uncertainty values obtained with this methodology, for about 18 vessels, are less than 10%.

Neutron fluence in a 18 MeV Electron Accelerator for Therapy; Fluencia de neutrones en un Acelerador de Electrones de 18 MeV para terapia

Energy Technology Data Exchange (ETDEWEB)

Paredes G, L C [Instituto Nacional de Investigaciones Nucleares, Direccion de Innovacion Tecnologica, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

2001-07-01

An investigation was made on the theoretical fundamentals for the determination of the neutron fluence in a linear electron accelerator for radiotherapy applications and the limit values of leakage neutron radiation established by guidelines and standards in radiation protection for these type of accelerators. This investigation includes the following parts: a) Exhaustive bibliographical review on the topics mentioned above, in order to combine and to update the necessary basic information to facilitate the understanding of this subject; b) Analysis of the accelerator operation and identification of its main components, specially in the accelerator head; c) Study of different types of targets and its materials for the Bremsstrahlung production which is based on the electron initial energy, the thickness of the target, and its angular distribution and energy, which influences in the neutron generation by means of the photonuclear and electro disintegration reactions; d) Analysis of the neutron yield based on the target type and its thickness, the energy of electrons and photons; e) Analysis of the neutron energy spectra generated in the accelerator head, inside and outside the treatment room; f) Study of the dosimetry fundamentals for neutron and photon mixed fields, the dosimeter selection criteria and standards applied for these applications, specially the Panasonic U D-809 thermoluminescent dosemeter and C R-39 nuclear track dosimeter; g) Theoretical calculation of the neutron yield using a simplified geometric model for the accelerator head with spherical cell, which considers the target, primary collimator, flattener filter, movable collimators and the head shielding as the main components for radiation production. The cases with W and Pb shielding for closed movable collimators and an irradiation field of 20 x 20 cm{sup 2} were analyzed and, h) Experimental evaluation of the leakage neutron radiation from the patient and head planes, observing that the

Activación del topacio natural irradiado por neutrones en el núcleo del reactor RP-10

OpenAIRE

Gómez, J.; Parreño, Fernando; Lázaro, Gerardo; Vela, Mariano

2003-01-01

Se obtuvieron cristales de topacio activados al ser irradiados con neutrones dentro del núcleo del reactor RP-10. La activación depende del flujo de neutrones, por ello se desarrolló portamuestras (canes de irradiación) para absorber que son los causantes de la activación

Thermal evaluation by means of simulation of two houses with different materials in the city of La Paz, B.C.S.; Evaluacion termica mediante simulacion de dos casas con materiales diferentes en la ciudad de la Paz, B.C.S.

Energy Technology Data Exchange (ETDEWEB)

Resendiz Pacheco, Oscar; Morillon Galvez, David; Chavez M, Elizabeth; Poujol G, Federico; Flores I, Alfredo [Universidad Autonoma de Baja California Sur (Mexico)

2009-01-15

In this article the evaluation of two houses of social interest in the city of La Paz is presented, in terms of the thermal comfort that could be offered to their users with a minimum cost of energy by means of a simulation of their thermal behavior with the program TRNSYS. One of the houses is constructed in a large extent with adobe, for the walls and brick for the ceilings and the other is a typical construction of social interest built with conventional materials. The obtained results are presented, with which some recommendations that can be made tending to improve comfort and energy saving in houses of social interest. These recommendations consider the type of material as much as the geometry of the houses. [Spanish] En este articulo se presenta la evaluacion de dos casas de interes social para la ciudad de La Paz, en terminos del confort termico que pudieran ofrecer a sus usuarios con un gasto minimo de energia mediante una simulacion de su comportamiento termico con el programa TRNSYS. Una de las casas esta construida en su mayor parte con adobe, para las paredes y ladrillo para los techos y la otra es una construccion tipica de interes social construida de materiales convencionales. Se presentan los resultados obtenidos, con los que se pueden hacer algunas recomendaciones tendientes a mejorar confort y ahorro de energia en casas de interes social. Estas recomendaciones consideran tanto el tipo de material como la geometria de las casas.

Experimental determination about thermal comfort conditions in buildings; Determinacion experimental de las condiciones de confort termico en edificaciones

Energy Technology Data Exchange (ETDEWEB)

Ambriz Garcia, Juan Jose; Garcia Chavez, Jose Roberto; Paredes Rubio, Hernando Romero [Universidad Autonoma Metropolitana (Mexico)]. E-mail: agj@xanum.uam.mx; jgc@correo.azc.uam.mx; hrp@xanum.uam.mx

2006-04-15

This paper analyzes the thermal comfort importance in a building. And the influence it exerts on quality of life as well as the efficiency of people work activities. There are comments about some models which better help to estimate the recommended temperature levels. The experimental evaluation results from a Mexico City population sampler are presented. This work was done in a Controlled Environment Laboratory; the obtained outcomes proved the preferences occupants exceed the comfort zone greatest limit accepted in the reference international standards. The meaning of this conclusion is thermal comfort can be reached with higher temperatures and consequently an energy consumption and an environment impact decrease. [Spanish] En este trabajo se analiza la importancia que tiene el confort termico en la calidad de vida de las personas que ocupan una edificacion y en la eficiencia de sus actividades. Se comentan algunos modelos con los cuales se estiman los niveles de temperatura recomendados y se presentan los resultados de una evaluacion experimental realizada en un Laboratorio de Ambiente Controlado con una muestra de la poblacion del Distrito Federal. Los resultados que se obtuvieron demuestran que los ocupantes tienen preferencias que rebasan el limite superior de la zona de confort comunmente aceptada en los estandares internacionales de referencia. Esto quiere decir que el confort puede lograrse con mayores temperaturas, lo que se traduce en menor consumo de energia y menor impacto en el ambiente.

Neutron--neutron logging

International Nuclear Information System (INIS)

Allen, L.S.

1977-01-01

A borehole logging tool includes a steady-state source of fast neutrons, two epithermal neutron detectors, and two thermal neutron detectors. A count rate meter is connected to each neutron detector. A first ratio detector provides an indication of the porosity of the formation surrounding the borehole by determining the ratio of the outputs of the two count rate meters connected to the two epithermal neutron detectors. A second ratio detector provides an indication of both porosity and macroscopic absorption cross section of the formation surrounding the borehole by determining the ratio of the outputs of the two count rate meters connected to the two thermal neutron detectors. By comparing the signals of the two ratio detectors, oil bearing zones and salt water bearing zones within the formation being logged can be distinguished and the amount of oil saturation can be determined. 6 claims, 2 figures

Irreversibility analysis of non isothermal flat plate solar collectors for air heating with a dimensionless model; Analisis de las irreversibilidades en colectores solares de placas planas no isotermicos para calentamiento de aire utilizando un modelo adimensional

Energy Technology Data Exchange (ETDEWEB)

Bracamonte-Baran, Johane Hans; Baritto-Loreto, Miguel Leonardo [Universidad Central de Venezuela (Venezuela)]. E-mails: johanehb@gmail.com; johane.bracamonte@ucv.ve; miguel.baritto@ucv.ve

2013-04-15

The dimensionless model developed and validated by Baritto and Bracamonte (2012) for the thermal behavior of flat plate solar collector without glass cover is improved by adding the entropy balance equation in a dimensionless form. The model is solved for a wide range of aspect ratios and mass flow numbers. A parametric study is developed and the distribution of internal irreversibilities along the collector is analyzed. The influence of the design parameters on the entropy generation by fluid friction and heat transfer is analyzed and it is found that for certain combinations of these parameters optimal thermodynamic operation can be achieved. [Spanish] En el presente trabajo, el modelo adimensional desarrollado y validado por Baritto y Bracamonte (2012) para describir el comportamiento termico de colectores solares de placas planas sin cubierta transparente, se complementa con la ecuacion adimensional de balance de entropia para un elemento diferencial de colector solar. El modelo se resuelve para un amplio rango de valores de relaciones de aspecto y numero de flujo de masa. A partir de los resultados del modelo se desarrolla un analisis detallado de la influencia de estos parametros sobre la distribucion de irreversibilidades internas a lo largo del colector. Adicionalmente se estudia la influencia de estos parametros sobre los numeros de generacion de entropia por friccion viscosa, por transferencia de calor y total. Se encuentra que existen combinaciones de los parametros antes mencionados, para los cuales, la operacion del colector es termodinamicamente optima para numeros de flujo de masa elevados.

Experimental characterization of the Advanced Liquid Hydrogen Cold Neutron Source spectrum of the NBSR reactor at the NIST Center for Neutron Research

Science.gov (United States)

Cook, J. C.; Barker, J. G.; Rowe, J. M.; Williams, R. E.; Gagnon, C.; Lindstrom, R. M.; Ibberson, R. M.; Neumann, D. A.

2015-08-01

The recent expansion of the National Institute of Standards and Technology (NIST) Center for Neutron Research facility has offered a rare opportunity to perform an accurate measurement of the cold neutron spectrum at the exit of a newly-installed neutron guide. Using a combination of a neutron time-of-flight measurement, a gold foil activation measurement, and Monte Carlo simulation of the neutron guide transmission, we obtain the most reliable experimental characterization of the Advanced Liquid Hydrogen Cold Neutron Source brightness to date. Time-of-flight measurements were performed at three distinct fuel burnup intervals, including one immediately following reactor startup. Prior to the latter measurement, the hydrogen was maintained in a liquefied state for an extended period in an attempt to observe an initial radiation-induced increase of the ortho (o)-hydrogen fraction. Since para (p)-hydrogen has a small scattering cross-section for neutron energies below 15 meV (neutron wavelengths greater than about 2.3 Å), changes in the o- p hydrogen ratio and in the void distribution in the boiling hydrogen influence the spectral distribution. The nature of such changes is simulated with a continuous-energy, Monte Carlo radiation-transport code using 20 K o and p hydrogen scattering kernels and an estimated hydrogen density distribution derived from an analysis of localized heat loads. A comparison of the transport calculations with the mean brightness function resulting from the three measurements suggests an overall o- p ratio of about 17.5(±1) % o- 82.5% p for neutron energies<15 meV, a significantly lower ortho concentration than previously assumed.

Experimental characterization of the Advanced Liquid Hydrogen Cold Neutron Source spectrum of the NBSR reactor at the NIST Center for Neutron Research

Energy Technology Data Exchange (ETDEWEB)

Cook, J.C.; Barker, J.G.; Rowe, J.M.; Williams, R.E. [NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Mail Stop 6100, Gaithersburg, MD 20899-6100 (United States); Gagnon, C. [Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742 (United States); Lindstrom, R.M. [Scientist Emeritus, Chemical Sciences Division, National Institute of Standards and Technology, 100 Bureau Drive, Mail Stop 8395, Gaithersburg, MD 20899-8395 (United States); Ibberson, R.M.; Neumann, D.A. [NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Mail Stop 6100, Gaithersburg, MD 20899-6100 (United States)

2015-08-21

The recent expansion of the National Institute of Standards and Technology (NIST) Center for Neutron Research facility has offered a rare opportunity to perform an accurate measurement of the cold neutron spectrum at the exit of a newly-installed neutron guide. Using a combination of a neutron time-of-flight measurement, a gold foil activation measurement, and Monte Carlo simulation of the neutron guide transmission, we obtain the most reliable experimental characterization of the Advanced Liquid Hydrogen Cold Neutron Source brightness to date. Time-of-flight measurements were performed at three distinct fuel burnup intervals, including one immediately following reactor startup. Prior to the latter measurement, the hydrogen was maintained in a liquefied state for an extended period in an attempt to observe an initial radiation-induced increase of the ortho (o)-hydrogen fraction. Since para (p)-hydrogen has a small scattering cross-section for neutron energies below 15 meV (neutron wavelengths greater than about 2.3 Å), changes in the o- p hydrogen ratio and in the void distribution in the boiling hydrogen influence the spectral distribution. The nature of such changes is simulated with a continuous-energy, Monte Carlo radiation-transport code using 20 K o and p hydrogen scattering kernels and an estimated hydrogen density distribution derived from an analysis of localized heat loads. A comparison of the transport calculations with the mean brightness function resulting from the three measurements suggests an overall o- p ratio of about 17.5(±1) % o- 82.5% p for neutron energies<15 meV, a significantly lower ortho concentration than previously assumed.

Determination of nitrogen in wheat flour through Activation analysis using Fast neutron flux of a Thermal nuclear reactor; Determinacion de nitrogeno en harina de trigo mediante analisis por activacion empleando el flujo de neutrones rapidos de un reactor nuclear termico

Energy Technology Data Exchange (ETDEWEB)

Ramirez G, T

1976-07-01

In this work is done a technical study for determining Nitrogen (protein) and other elements in wheat flour Activation analysis, with Fast neutrons from a Thermal nuclear reactor. Initially it is given an introduction about the basic principles of the methods of analysis. Equipment used in Activation analysis and a brief description of the neutron source (Thermal nuclear reactor). The realized experiments for determining the flux form in the irradiation site, the half life of N-13 and the interferences due to the sample composition are included too. Finally, the obtained results by Activation and the Kjeldahl method are tabulated. (Author)

Calculation of neutron fluence to dose equivalent conversion coefficients using GEANT4; Calculo de coeficientes de fluencia de neutrons para equivalente de dose individual utilizando o GEANT4

Energy Technology Data Exchange (ETDEWEB)

Ribeiro, Rosane M.; Santos, Denison de S.; Queiroz Filho, Pedro P. de; Mauricio, CLaudia L.P.; Silva, Livia K. da; Pessanha, Paula R., E-mail: rosanemribeiro@oi.com.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

2014-07-01

Fluence to dose equivalent conversion coefficients provide the basis for the calculation of area and personal monitors. Recently, the ICRP has started a revision of these coefficients, including new Monte Carlo codes for benchmarking. So far, little information is available about neutron transport below 10 MeV in tissue-equivalent (TE) material performed with Monte Carlo GEANT4 code. The objective of this work is to calculate neutron fluence to personal dose equivalent conversion coefficients, H{sub p} (10)/Φ, with GEANT4 code. The incidence of monoenergetic neutrons was simulated as an expanded and aligned field, with energies ranging between thermal neutrons to 10 MeV on the ICRU slab of dimension 30 x 30 x 15 cm{sup 3}, composed of 76.2% of oxygen, 10.1% of hydrogen, 11.1% of carbon and 2.6% of nitrogen. For all incident energy, a cylindrical sensitive volume is placed at a depth of 10 mm, in the largest surface of the slab (30 x 30 cm{sup 2}). Physic process are included for neutrons, photons and charged particles, and calculations are made for neutrons and secondary particles which reach the sensitive volume. Results obtained are thus compared with values published in ICRP 74. Neutron fluence in the sensitive volume was calculated for benchmarking. The Monte Carlo GEANT4 code was found to be appropriate to calculate neutron doses at energies below 10 MeV correctly. (author)

Scenarios simulation for the conservation and efficient use of energy, using passive control measures; Simulacion de escenarios de ahorro y uso eficiente de energia, utilizando medidas de control pasivo

Energy Technology Data Exchange (ETDEWEB)

Ramos, G.; Heard, Ch.; Sanchez Viveros, A. [Instituto de Investigaciones Electricas,Cuernavaca (Mexico)

1997-12-31

Every one involved with the conservation and efficient use of electric energy, has listened in reiterative occasions to the causes that changed the conventional mentality at the beginning of the seventies. Nevertheless, there are many persons that still ignore that by using the energy rationally, their costs are significantly reduced, their comfort is enhanced and the environmental problems are minimized. Specifically, in the domestic sector, from the figures reported by the Comision Federal de Electricidad (CFE) in 1996, the electric energy sold was 28,410 Gwh, that is, 23.4% of the total consumption (121,579 Gwh). Table 1 presents the average by tariff in the national domestic sector, which shows that 20% of the electricity consumed was required for environmental conditioning (air conditioning, evaporative coolers and electric fans). The above figures quantitatively show that there is a strong impact in the consumption of electric energy due to weather conditions. For this reason, currently the Comision Nacional de Ahorro de Energia (CONAE) and the Fideicomiso para el Ahorro de Energia (FIDE) are promoting standards and projects to propitiate the rationalization in the use of energy, besides of achieving the improvement of thermal comfort conditions. One more case would be the Fideicomiso para el Aislamiento Termico de la Vivienda en Mexicali (FIPATERM), which promotes the financing of saving measures and efficient energy use in cities with extreme climate. This paper describes the strategy that was followed by the Instituto de Investigaciones Electricas (IIE), for the development of the human and material infrastructure, that has allowed the sustainment of several projects in the saving and efficient use of energy in CFE, CONAE, FIDE, FIPATERM and the Lawrence Berkeley National Laboratory (LBNL), concretely in relationship with the thermal analysis of dwellings. [Espanol] Todos aquellos relacionados con el ahorro y el uso eficiente de la energia electrica, han

Scenarios simulation for the conservation and efficient use of energy, using passive control measures; Simulacion de escenarios de ahorro y uso eficiente de energia, utilizando medidas de control pasivo

Energy Technology Data Exchange (ETDEWEB)

Ramos, G; Heard, Ch; Sanchez Viveros, A [Instituto de Investigaciones Electricas,Cuernavaca (Mexico)

1998-12-31

Every one involved with the conservation and efficient use of electric energy, has listened in reiterative occasions to the causes that changed the conventional mentality at the beginning of the seventies. Nevertheless, there are many persons that still ignore that by using the energy rationally, their costs are significantly reduced, their comfort is enhanced and the environmental problems are minimized. Specifically, in the domestic sector, from the figures reported by the Comision Federal de Electricidad (CFE) in 1996, the electric energy sold was 28,410 Gwh, that is, 23.4% of the total consumption (121,579 Gwh). Table 1 presents the average by tariff in the national domestic sector, which shows that 20% of the electricity consumed was required for environmental conditioning (air conditioning, evaporative coolers and electric fans). The above figures quantitatively show that there is a strong impact in the consumption of electric energy due to weather conditions. For this reason, currently the Comision Nacional de Ahorro de Energia (CONAE) and the Fideicomiso para el Ahorro de Energia (FIDE) are promoting standards and projects to propitiate the rationalization in the use of energy, besides of achieving the improvement of thermal comfort conditions. One more case would be the Fideicomiso para el Aislamiento Termico de la Vivienda en Mexicali (FIPATERM), which promotes the financing of saving measures and efficient energy use in cities with extreme climate. This paper describes the strategy that was followed by the Instituto de Investigaciones Electricas (IIE), for the development of the human and material infrastructure, that has allowed the sustainment of several projects in the saving and efficient use of energy in CFE, CONAE, FIDE, FIPATERM and the Lawrence Berkeley National Laboratory (LBNL), concretely in relationship with the thermal analysis of dwellings. [Espanol] Todos aquellos relacionados con el ahorro y el uso eficiente de la energia electrica, han

Interpretation of the quasi-elastic neutron scattering on PAA by rotational diffusion models

International Nuclear Information System (INIS)

Bata, L.; Vizi, J.; Kugler, S.

1974-10-01

First the most important data determined by other methods for para azoxy anisolon (PAA) are collected. This molecule makes a rotational oscillational motion around the mean molecular direction. The details of this motion can be determined by inelastic neutron scattering. Quasielastic neutron scattering measurements were carried out without orienting magnetic field on a time-of-flight facility with neutron beam of 4.26 meV. For the interpretation of the results two models, the spherical rotation diffusion model and the circular random walk model are investigated. The comparison shows that the circular random walk model (with N=8 sites, d=4A diameter and K=10 10 s -1 rate constant) fits very well with the quasi-elastic neutron scattering, while the spherical rotational diffusion model seems to be incorrect. (Sz.N.Z.)

Neutron radiography with ultracold neutrons

International Nuclear Information System (INIS)

Bates, J.C.

1981-01-01

The neutron transmission factor of very thin films may be low if the neutron energy is comparable to the pseudo-potential of the film material. Surprisingly, perhaps, it is relatively easy to obtain neutrons with such low energies in sufficient numbers to produce neutron radiographs. (orig.)

The Biological Effect of Fast Neutrons and High-Energy Protons; Effets Biologiques des Neutrons Rapides et des Protons de Haute Energie; Biologicheskoe dejstvie bystrykh nejtronov i protonov vysokikh ehnergii; Efectos Biologicos de los Neutrones Rapidos y de los Protones de Elevada Energia

Energy Technology Data Exchange (ETDEWEB)

Moskalev, Ju. I.; Petrovich, I. K.; Strel' cova, V. N.

1964-03-15

frecuencia y rapidez de formacion de tumores en la rata, en funcion de la dosis aplicada y del tiempo transcurrido a partir de' la irradiacion. En el experimento con neutrones utilizaron 573 ratas blancas y en el experimento con protones, 490. Expusieron los animales a dosis neutronicas de 8,5 a 510 rad, y dosis protonicas comprendidas entre 28 y 1008 rad. Tanto para los neutrones rapidos como para los protones, establecieron el valor de la dosis efectiva aguda, subaguda y cronica. La DL{sup 30}{sub 50} para los neutrones asciende a 408 rad y a 600 rad para los protones; las respectivas dosis DL{sup 120}{sub 50} son 380 rad y 600 rad. Los autores estudiaron las leyes que rigen la mortalidad de los sujetos en experimentos breves y prolongados. Demuestran que la sobrevivencia de los mismos, cuando se ios irradia con neutrones rapidos, es independiente del sexo. La forma de la curva dosis/efecto para los diversos Indices de la sangre periferica no solo depende de la radiosensibilidad de las celulas sanguineas correspondientes, sino tambien del perfodo de observacion. Puede sufrir modificaciones sensibles en funcion del tiempo para un mismo indice. Algun tiempo despues de la irradiacion, tanto con neutrones rapidos como con protones, se observan en las ratas tumores de caracter benigno o maligno en diversos tejidos, entre ellos en los de los arganos hematopoyeticos, las glandulas mamarias, la hipofisis, el utero, los ovarios, la prostata, los testiculos, la tiroides, el timo y el pancreas, las glandulas suprarrenales, el higado, los rinones, los pulmones, el tracto gastrointestinal, el tejido hipodermico, los ganglios linfaticos, la vejiga, etc. La frecuencia total de los tumores y el numero de casos de formacion multicentrica de neoplasias es de 2 a 3 veces mayor en las hembras que en los machos. La dosis tumorigena minima en las glandulas mamarias, en la irradiacion neutronica, parece ser algo inferior a 42,5 rad. La frecuencia maxima de los tumores de la hipofisis se observa

Neutron Skins and Neutron Stars

OpenAIRE

Piekarewicz, J.

2013-01-01

The neutron-skin thickness of heavy nuclei provides a fundamental link to the equation of state of neutron-rich matter, and hence to the properties of neutron stars. The Lead Radius Experiment ("PREX") at Jefferson Laboratory has recently provided the first model-independence evidence on the existence of a neutron-rich skin in 208Pb. In this contribution we examine how the increased accuracy in the determination of neutron skins expected from the commissioning of intense polarized electron be...

A new computation tool for neutron spectrometry and dosimetry; Una nueva herramiento de computo para la espectrometria y dosimetria de neutrones

Energy Technology Data Exchange (ETDEWEB)

Martinez B, M. R.; Ortiz R, J. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Av. Ramon Lopez Velarde No. 801, Col. Centro, Zacatecas (Mexico)], e-mail: mrosariomb@yahoo.com.mx

2009-10-15

By using the integrated accounts of spectrometric system of Bonner spheres is possible to reconstruct the neutron spectrum using various methods such as: Monte Carlo, the parameterization and iterative methods. The response matrix, counting rates and neutron spectrum are intimately related through the integral-differential of Fredholm of first type. however, the weight of Bonner spheres system, the procedure of spectra reconstruction, the need of a expert user, the high time consumption, the need to use a reconstruction code (BUNKI, SAND, among others) and the spectrum resolution, are some of problems that this system presents. The above difficulties have motivated the development of complementary procedures such as maximum entropy, genetic algorithms and artificial neural networks. In recent years, using neural network technology has become an alternative procedure in the nuclear science research area, considering a replacement for classical techniques used for years. In previous works, was used a new method called robust design methodology of artificial neural networks, to construct various network topologies capable of solving the problems of neutron spectrometry and dosimetry, however noted that not exist tools for end-user that allow test and validate the designed networks. This paper presents the development of a software for neutronic spectrometry and dosimetry, based on information extracted from an artificial neural network designed in previous work, through the robust design methodology of artificial neural networks with the following characteristics: was designed in a user graphical interface easy to use, speed on the application execution, unlike other deconvolution codes, not is necessary to select and initial spectrum for spectrum reconstruction, as an additional element to this tool, besides spectrum, the calculation is performed simultaneous of 13 equivalent dose from just counting rates from a spectrometric system of Bonner spheres. (Author)

Structural and energetical studies of the adsorption of para and meta-isomers of xylene on pre-hydrated zeolite BaX. Characterization by neutron diffraction and temperature programmed desorption; Etude structurale et energetique de l'adsorption des isomeres para- et meta- du xylene dans la zeolithe BaX prehydratee. Caracterisation par diffraction des neutrons et thermodesorption programmee

Energy Technology Data Exchange (ETDEWEB)

Pichon, Ch.

1999-10-19

The separation of p-xylene from C{sub 8} aromatics is performed industrially by selective adsorption on zeolitic materials. FAU-type zeolites are currently used for this separation and especially the partially hydrated BaX. The aim of this work is to characterize from a structural (by low temperature neutron powder diffraction) and an energetical (by temperature programmed desorption) point of view, the adsorption of para- and meta- isomers of xylene, for different fillings, as pure substances as well as mixtures, on pre-hydrated zeolite BaX. The influence of the water pre-adsorption on xylene adsorption selectivity is carefully discussed. The crystalline structure of the zeolite BaX (framework and compensation of charge cations) and of the adsorbed phase (water, p- and m-xylene molecules) are completely characterized by neutron diffraction. The location and the distribution of water and xylene molecules on their adsorption sites is especially followed as a function of the filling of the zeolite and of the composition of the adsorbed phase. Microscopic measurements were correlated to the energetical analysis (at a macroscopic level) in order to obtain a consistent description of adsorption phenomenon and to propose a possible origin for adsorption selectivity.

Neutron-neutron probe for uranium exploration

International Nuclear Information System (INIS)

Smith, R.C.

1979-01-01

A neutron activation probe for assaying the amount of fissionable isotopes in an ore body is described which comprises a casing which is movable through a borehole in the ore body, a neutron source and a number of delayed neutron detectors arranged colinearly in the casing below the neutron source for detecting delayed neutrons

Medición del tiempo de generación de Neutrones Prontos por los Métodos de Feynman y Bennett

OpenAIRE

Fiestas Urbina, Carlos Job; Fiestas Urbina, Carlos Job

1982-01-01

El propósito principal del presente trabajo es determinar el tiempo de generación de neutrones prontos reducidos, la constante de decaimiento de los neutrones, correspondientes a una reactividad, la eficiencia del detector de neutrones de la segunda cadena de arranque, para el reactor de potencia cero con la configuración nuclear #52; haciendo un análisis estadístico del contaje de neutrones mediante los modelos de Feyman y Bennett. La diferencia de estos métodos radica en que el primero no ...

Quantitative neutron radiography using neutron absorbing honeycomb

International Nuclear Information System (INIS)

Tamaki, Masayoshi; Oda, Masahiro; Takahashi, Kenji; Ohkubo, Kohei; Tasaka, Kanji; Tsuruno, Akira; Matsubayashi, Masahito.

1993-01-01

This investigation concerns quantitative neutron radiography and computed tomography by using a neutron absorbing honeycomb collimator. By setting the neutron absorbing honeycomb collimator between object and imaging system, neutrons scattered in the object were absorbed by the honeycomb material and eliminated before coming to the imaging system, but the neutrons which were transmitted the object without interaction could reach the imaging system. The image by purely transmitted neutrons gives the quantitative information. Two honeycombs were prepared with coating of boron nitride and gadolinium oxide and evaluated for the quantitative application. The relation between the neutron total cross section and the attenuation coefficient confirmed that they were in a fairly good agreement. Application to quantitative computed tomography was also successfully conducted. The new neutron radiography method using the neutron-absorbing honeycomb collimator for the elimination of the scattered neutrons improved remarkably the quantitativeness of the neutron radiography and computed tomography. (author)

Neutron dosimetry; Dosimetria de neutrons

Energy Technology Data Exchange (ETDEWEB)

Fratin, Luciano

1993-12-31

A neutron irradiation facility was designed and built in order to establish a procedure for calibrating neutron monitors and dosemeters. A 185 GBq {sup 241} Am Be source of known is used as a reference source. The irradiation facility using this source in the air provides neutron dose rates between 9 nSv s{sup -1} and 0,5 {sup {mu}}Sv s{sup -1}. A calibrated 50 nSv s{sup -1} thermal neutron field is obtained by using a specially designed paraffin block in conjunction with the {sup 241} Am Be source. A Bonner multisphere spectrometer was calibrated, using a procedure based on three methods proposed by international standards. The unfold {sup 241} Am Be neutron spectrum was determined from the Bonner spheres data and resulted in a good agreement with expected values for fluence rate, dose rate and mean energy. A dosimetric system based on the electrochemical etching of CR-39 was developed for personal dosimetry. The dosemeter badge using a (n,{alpha}) converter, the etching chamber and high frequency power supply were designed and built specially for this project. The electrochemical etching (ECE) parameters used were: a 6N KOH solution, 59 deg C, 20 kV{sub pp} cm{sup -1}, 2,0 kHz, 3 hours of ECE for thermal and intermediate neutrons and 6 hours for fast neutrons. The calibration factors for thermal, intermediate and fast neutrons were determined for this personal dosemeter. The sensitivities determined for the developed dosimetric system were (1,46{+-} 0,09) 10{sup 4} tracks cm{sup -2} mSv{sup -1} for thermal neutrons, (9{+-}3) 10{sup 2} tracks cm{sup -2} mSV{sup -1} for intermediate neutrons and (26{+-}4) tracks cm{sup -2} mSv{sup -1} for fast neutrons. The lower and upper limits of detection were respectively 0,002 mSv and 0,6 mSv for thermal neutrons, 0,04 mSv and 8 mSv for intermediate neutrons and 1 mSv and 12 mSv for fast neutrons. In view of the 1990`s ICRP recommendations, it is possible to conclude that the personal dosemeter described in this work is

Neutron dosimetry; Dosimetria de neutrons

Energy Technology Data Exchange (ETDEWEB)

Fratin, Luciano

1994-12-31

A neutron irradiation facility was designed and built in order to establish a procedure for calibrating neutron monitors and dosemeters. A 185 GBq {sup 241} Am Be source of known is used as a reference source. The irradiation facility using this source in the air provides neutron dose rates between 9 nSv s{sup -1} and 0,5 {sup {mu}}Sv s{sup -1}. A calibrated 50 nSv s{sup -1} thermal neutron field is obtained by using a specially designed paraffin block in conjunction with the {sup 241} Am Be source. A Bonner multisphere spectrometer was calibrated, using a procedure based on three methods proposed by international standards. The unfold {sup 241} Am Be neutron spectrum was determined from the Bonner spheres data and resulted in a good agreement with expected values for fluence rate, dose rate and mean energy. A dosimetric system based on the electrochemical etching of CR-39 was developed for personal dosimetry. The dosemeter badge using a (n,{alpha}) converter, the etching chamber and high frequency power supply were designed and built specially for this project. The electrochemical etching (ECE) parameters used were: a 6N KOH solution, 59 deg C, 20 kV{sub pp} cm{sup -1}, 2,0 kHz, 3 hours of ECE for thermal and intermediate neutrons and 6 hours for fast neutrons. The calibration factors for thermal, intermediate and fast neutrons were determined for this personal dosemeter. The sensitivities determined for the developed dosimetric system were (1,46{+-} 0,09) 10{sup 4} tracks cm{sup -2} mSv{sup -1} for thermal neutrons, (9{+-}3) 10{sup 2} tracks cm{sup -2} mSV{sup -1} for intermediate neutrons and (26{+-}4) tracks cm{sup -2} mSv{sup -1} for fast neutrons. The lower and upper limits of detection were respectively 0,002 mSv and 0,6 mSv for thermal neutrons, 0,04 mSv and 8 mSv for intermediate neutrons and 1 mSv and 12 mSv for fast neutrons. In view of the 1990`s ICRP recommendations, it is possible to conclude that the personal dosemeter described in this work is

Neutron detection efficiency determinations for the TUNL neutron-neutron and neutron-proton scattering-length measurements

International Nuclear Information System (INIS)

Trotter, D.E. Gonzalez; Meneses, F. Salinas; Tornow, W.; Crowell, A.S.; Howell, C.R.; Schmidt, D.; Walter, R.L.

2009-01-01

The methods employed and the results obtained from measurements and calculations of the detection efficiency for the neutron detectors used at Triangle Universities Nuclear Laboratory (TUNL) in the simultaneous determination of the 1 S 0 neutron-neutron and neutron-proton scattering lengths a nn and a np , respectively, are described. Typical values for the detector efficiency were 0.3. Very good agreement between the different experimental methods and between data and calculation has been obtained in the neutron energy range below E n =13MeV.

Neutron detection efficiency determinations for the TUNL neutron-neutron and neutron-proton scattering-length measurements

Energy Technology Data Exchange (ETDEWEB)

Trotter, D.E. Gonzalez [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)], E-mail: crowell@tunl.duke.edu; Meneses, F. Salinas [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Tornow, W. [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)], E-mail: tornow@tunl.duke.edu; Crowell, A.S.; Howell, C.R. [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Schmidt, D. [Physikalisch-Technische Bundesanstalt, D-38116, Braunschweig (Germany); Walter, R.L. [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)

2009-02-11

The methods employed and the results obtained from measurements and calculations of the detection efficiency for the neutron detectors used at Triangle Universities Nuclear Laboratory (TUNL) in the simultaneous determination of the {sup 1}S{sub 0} neutron-neutron and neutron-proton scattering lengths a{sub nn} and a{sub np}, respectively, are described. Typical values for the detector efficiency were 0.3. Very good agreement between the different experimental methods and between data and calculation has been obtained in the neutron energy range below E{sub n}=13MeV.

Neutron stars

International Nuclear Information System (INIS)

Irvine, J.M.

1978-01-01

The subject is covered in chapters entitled: introduction (resume of stellar evolution, gross characteristics of neutron stars); pulsars (pulsar characteristics, pulsars as neutron stars); neutron star temperatures (neutron star cooling, superfluidity and superconductivity in neutron stars); the exterior of neutron stars (the magnetosphere, the neutron star 'atmosphere', pulses); neutron star structure; neutron star equations of state. (U.K.)

Neutron field characterization in the installation for BNCT study in the IEA-R1 reactor; Caracterizacao do campo de neutrons na instalacao para estudo em BNCT no reator IEA-R1

Energy Technology Data Exchange (ETDEWEB)

Carneiro Junior, Valdeci

2008-07-01

This work aims to characterize the mixed neutron and gamma field, in the sample irradiation position, in a research installation for Boron Neutron Capture Therapy (BNCT), in the IPEN IEA-R1 reactor. The BNCT technique has been studied as a safe and selective option in the treatment of resistant cancerigenous tumors or considered non-curable by the conventional techniques, for example, the Glioblastoma Multiform - a brain cancerigenous tumor. Neutron flux measurements were carried out: thermal, resonance and fast, as well as neutron and gamma rays doses, in the sample position, using activation foils detectors and thermoluminescent dosimeters. For the determination of the neutron spectrum and intensity, a set of different threshold activation foils and gold foils covered and uncovered with cadmium irradiated in the installation was used, analyzed by a high Pure Germanium semiconductor detector, coupled to an electronic system suitable for gamma spectrometry. The results were processed with the SAND-BP code. The doses due to gamma and neutron rays were determined using thermoluminescent dosimeters TLD 400 and TLD 700 sensitive to gamma and TLD 600, sensitive to neutrons. The TLDs were selected and used for obtaining the calibration curves - dosimeter answer versus dose - from each of the TLD three types, which were necessary to calculate the doses due to neutron and gamma, in the sample position. The radiation field, in the sample irradiation position, was characterized flux for thermal neutrons of 1.39.10{sup 8} {+-} 0,12.10{sup 8} n/cm{sup 2}s the doses due to thermal neutrons are three times higher than those due to gamma radiation and confirm the reproducibility and consistency of the experimental findings obtained. Considering these results, the neutron field and gamma radiation showed to be appropriated for research in BNCT. (author)

On the yield of cold and ultracold neutrons for liquid hydrogen at low temperatures near the melting point

CERN Document Server

Morishima, N

1999-01-01

The neutron scattering cross sections for liquid hydrogen in the temperature range from the melting point to the boiling point are calculated. It is shown that lowering the temperature results in a significant increase in the yield of cold neutrons: for instance, a 44% increase for an incident neutron energy of 19.4 meV. The major cause of this increment is the para-to-ortho transition of a hydrogen molecule though accompanied by an appreciable increase in the density. The results of the cold- and ultracold-neutron yields are discussed in connection with the experimental results of Altarev et al. at the WWR-M reactor.

Neutron moderators for the European Spallation Source

DEFF Research Database (Denmark)

Klinkby, Esben Bryndt; Zanini, L.; Batkov, K.

The design of the neutron moderators for the European Spallation Source, intended to be installed at the start of operations of the facility in 2019 has now been finalized and the moderators are being fabricated. Among the driving principles in the design have been flexibility for instruments...... to have access to cold and thermal neutrons with highest possible source brightness. Different design and configuration options were evaluated. The final configuration accepted for construction foresees two moderators with identical para-hydrogen (so-called "butterfly") shape, but different heights......, placed above and below the spallation target. Both moderators are able to serve the full 2 x 120° beam extraction sectors of instrument suite. The top, 3-cm tall moderator, has both high thermal and high cold brightness, more than by a factor of 2.5 compared to the previous design of the Technical Design...

Study of liquid hydrogen and liquid deuterium cold neutron sources; Etude de sources de neutrons froids a hydrogene et deuterium liquides

Energy Technology Data Exchange (ETDEWEB)

Harig, H D [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1967-12-01

In view of the plant of the cold neutron source for a high flux reactor (maximal thermal flux of about 10{sup 15} n/cm{sup 2}s) an experimental study of several cold sources of liquid hydrogen and liquid deuterium has been made in a low power reactor (100 kW, about 10{sup 12} n/cm{sup 2}s). We have investigated: -cold neutron sources of liquid hydrogen shaped as annular layers of different thickness. Normal liquid hydrogen was used as well as hydrogen with a high para-percentage. -Cold neutron sources of liquid deuterium in cylinders of 18 and 38 cm diameter. In this case the sources could be placed into different positions to the reactor core within the heavy water reflector. This report gives a general description of the experimental device and deals more detailed with the design of the cryogenic systems. Then, the measured results are communicated, interpreted and finally compared with those of a theoretical study about the same cold moderators which have been the matter of the experimental investigation. (authors) [French] En vue de l'installation d'une source a neutrons froids dans un reacteur a haut flux (flux thermique maximal environ 10{sup 15} n/cm{sup 2}s), nous avons fait une etude neutronique experimentale de differentes sources froides a hydrogene et a deuterium liquides aupres d'un reacteur a faible puissance (100 kW environ 10{sup 12} n/cm{sup 2}s). Nous avons etudie: des couches annulaires de differentes epaisseurs d'hydrogene liquide normal et d'hydrogene a grand pourcentage para, des cellules cylindriques de 18 et 38 cm de diametre, remplies de deuterium liquide et placees a differentes positions dans le reflecteur D{sub 2}O. Ce travail traite l'implantation de l'installation cryogenique et donne une description generale de l'experience. L'interpretation des resultats fait etat entre autres d'une comparaison entre l'experience et une etude theorique portant sur les memes moderateurs. (auteurs)

The Determination of Uranium in Urine by Delayed Neutron Counting; Dosage de l'Uranium dans l'Urine par Comptage des Neutrons Differes; Opredelenie soderzhaniya urana v moche putem scheta zapazdyvayushchikh nejtronov; Determinacion del Uranio Contenido en la Orina por Recuento de Neutrones Retardados

Energy Technology Data Exchange (ETDEWEB)

Brookes, I. R. [Atomic Weapons Research Establishment, Aldermaston, Berks. (United Kingdom)

1965-10-15

polyethylene d'une capacite de 2,85 cl, qui est scelle a chaud. Le flacon contenant l'echantillon est enferme dans un tube et envoye par un systeme pneumatique dans le coeur du reacteur HERALD ou il est irradie par un fieux de neutrons thermiques de 3,94 * 10{sup 12}n/cm{sup 2}s. Apres une irradiation de 1 min, l'echantillon retourne automatiquement au laboratoire ou le flacon contenant l'echantillon est place dans un compteur a neutrons. Ce compteur est mis en marche 25 s apres que l'echantillon a quitte le reacteur et compte l'echantillon pendant 1 min. Les echantillons temoins se composent d'urine provenant de personnes qui ne sont pas professionnellement exposees a l'uranium; l'etalon est une quantite connue de {sup 235}U (sous forme d'uranium naturel). La limite de detection est de 0,020 pCi d'uranium enrichi a 93% ou de 0,026 {mu}g d'uranium naturel (0,007 de la charge corporelle maximale admissible) et de 0,036 {mu}g d'uranium naturel pour 100 ml d'urine. Elle depend du nombre de coups correspondant aux temoins. La composante principale du temoin est la reponse du compteur aux rayons gamma emis par les produits d'activation que l'urine irradiee contient. Il faut 3,5 min environ pour irradier et compter un echantillon et l'on peut, au cours d'une journee de travail, faire evaporer et traiter 50 echantillons pour les mettre en flacons. Pour les analyses d'urine, l'influence de {sup 239}Pu peut etre consideree comme negligeable. (author) [Spanish] Con arreglo al metodo del autor, el uranio-235 se determina por recuento de los neutrones retardados emitidos a raiz de la fision por neutrones termicos del {sup 235}U contenido en la muestra. Los tres grupos de neutrones que se consideran tienen periodos de 55, 72, 22, 72 y 6, 22 s, respectivamente. En un bano Maria se evaporan a sequedad 100 mi de orina. El residuo se pasa con unos 4 a 5 mi de agua a un frasco de polietileno de 1 onza, que se cierra seguidamente por soldadura termica. El frasco con la muestra se coloca en un

Geochemistry of single diamond crystals by instrumental neutron activation analysis

International Nuclear Information System (INIS)

Damarupurshad, A.

1995-02-01

Neutron activation analysis is probably the most powerful technique, available to date, for the analysis of the trace elements in diamond. In this study the technique of neutron activation analysis has been modified and optimized for the analysis of single, small (0.01-0.5 carat), inclusion-bearing and inclusion-free diamonds. Instrumental neutron activation analysis was used to analyze for up to 40 different elements at the ppb and ppt levels in diamonds from Brazil, South Africa, Colorado and China. The data obtained was used to detect and understand the differences between diamonds from the eclogitic and peridotitic para geneses and between diamonds from the different localities. In this regard, two inter element ratios, i.e. Cr/Sc and Au/Ir ratios were found to be useful. It seems that diamonds from a particular locality or mine have a unique range of Cr/Sc ratios. Furthermore, the identity of the dominant silicate inclusion(s) can be deduced from the Cr/Sc ratio of the diamond, since each type of silicate inclusion has a different range of Cr/Sc ratios. Not only is the Cr/Sc ratio distinctive for silicate inclusions in diamonds, it is also distinctive for minerals co genetic with diamond, such as orange garnet, red garnet, chrome diopside and ortho pyroxene (macrocrysts) which were separated from kimberlites. Sulphide inclusions may also contain detectable quantities of Au and Ir and the ratios of these two elements can also be used to differentiate between diamonds of the two para geneses. Carbon isotope ratios of these eclogitic and peridotitic diamonds were also measured. The comparison of this with the Cr/Sc ratios revealed that the carbon isotope ratios of both para geneses overlap in a narrow range and do not show the clear separations seen with Cr/Sc and Au/Ir ratios. It can be suggested, therefore, on the basis of the suite of 61 diamonds analyzed in this study, that the Cr/Sc and Au/Ir ratios are much more useful tools to distinguish between diamonds

Application of scale test modules for model the electrothermal performance in buildings for the efficient use of energy; Aplicacion de modulos de prueba a escala para modelar el funcionamiento electrotermico de edificios para el uso eficiente de la energia

Energy Technology Data Exchange (ETDEWEB)

Acoltzi Acoltzi, Higinio

2000-10-01

and small vault pottery with glass sun reflector (34% in the experimental model and 37% in the theoretical model). [Spanish] La investigacion para acondicionamiento de espacios por enfriamiento en edificios de tamano real tiene un costo elevado por la cantidad de materiales y la variedad de parametros que intervienen. Por lo anterior, en este trabajo se utilizan modulos de prueba a escala acoplados a sistemas de aire acondicionado para obtener su respuesta electrotermica; es decir, cuantificar la cantidad de energia electrica que consumira un modulo en funcion de los materiales de prueba. Se analiza un modelo termico teorico transitorio y las pruebas experimentales del comportamiento termico de modulos de prueba a escala por la variacion de los materiales de los techos y ventanas, desarrollado con el objeto de establecer criterios de aplicacion de dichos materiales en las industrias de la edificacion. Adicionalmente se presenta el desarrollo de un modelo electrotermico teorico en estado permanente, que define el comportamiento del consumo de energia electrica, para mantener las condiciones de confort al interior de los modulos de prueba respecto a la variacion de los materiales mencionados. Se presenta tambien el diseno y el desarrollo de las pruebas experimentales utilizando los modulos de prueba a escala para validar el modelo electrotermico. La experimentacion se desarrolla exponiendo los modulos de prueba a escala, acoplados a los equipos de aire acondicionado, a la radiacion solar directa, registrando el consumo de energia electrica de los equipos de aire acondicionado, la radiacion solar sobre techo y ventanas de prueba, la temperatura interior de los modulos, la temperatura interior y exterior en la superficie de los techos de prueba, la temperatura ambiente, y la velocidad del viento. Los resultados obtenidos comparando las mediciones en campo y el modelo electrotermico teorico desarrollado, presentan diferencias promedio de 16%. Los ahorros de energia

Thermal spectra of the TRIGA Mark III reactor; El espectro termico del reactor TRIGA Mark III

Energy Technology Data Exchange (ETDEWEB)

Macias B, L.R.; Palacios G, J. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

1998-07-01

The diffraction phenomenon is gave in observance of the well known Bragg law in crystalline materials and this can be performance by mean of X-rays, electrons and neutrons among others, which allows to do inside the field of each one of these techniques the obtaining of measurements focussed at each one of them. For the present work, it will be mentioned only the referring to X-ray and neutron techniques. The X-ray diffraction due to its properties just it does measurements which are known in general as superficial measurements of the sample material but for the properties of the neutrons, this diffraction it explores in volumetric form the sample material. Since the neutron diffraction process depends lots of its intensity, then it is important to know the neutron source spectra that in this case is supplied by the TRIGA Mark III reactor. Within of diffraction techniques a great number of them can be found, however some of the traditional will be mentioned such as the identification of crystalline samples, phases identification and the textures measurement. At present this last technique is founded on the dot of a minimum error and the technique of phases identification performs but not compete with that which is obtained by mean of X-rays due to this last one has a major resolution. (Author)

Pulsed neutron sources for epithermal neutrons

International Nuclear Information System (INIS)

Windsor, C.G.

1978-01-01

It is shown how accelerator based neutron sources, giving a fast neutron pulse of short duration compared to the neutron moderation time, promise to open up a new field of epithermal neutron scattering. The three principal methods of fast neutron production: electrons, protons and fission boosters will be compared. Pulsed reactors are less suitable for epithermal neutrons and will only be briefly mentioned. The design principle of the target producing fast neutrons, the moderator and reflector to slow them down to epithermal energies, and the cell with its beam tubes and shielding will all be described with examples taken from the new Harwell electron linac to be commissioned in 1978. A general comparison of pulsed neutron performance with reactors is fraught with difficulties but has been attempted. Calculation of the new pulsed source fluxes and pulse widths is now being performed but we have taken the practical course of basing all comparisons on extrapolations from measurements on the old 1958 Harwell electron linac. Comparisons for time-of-flight and crystal monochromator experiments show reactors to be at their best at long wavelengths, at coarse resolution, and for experiments needing a specific incident wavelength. Even existing pulsed sources are shown to compete with the high flux reactors in experiments where the hot neutron flux and the time-of-flight methods can be best exploited. The sources under construction can open a new field of inelastic neutron scattering based on energy transfer up to an electron volt and beyond

Neutron radiography using neutron imaging plate

International Nuclear Information System (INIS)

Chankow, Nares; Wonglee, Sarinrat

2008-01-01

Full text: The aims of this research are to study properties of neutron imaging plate, to obtain a suitable condition for neutron radiography and to use the neutron imaging plate for testing of materials nondestructively. The experiments were carried out by using a neutron beam from the Thai Research Reactor TRR-1/M1 at a power of 1.2 MW. A BAS-ND 2040 FUJI neutron imaging plate and a MX125 Kodak X-ray film/Gadolinium neutron converter screen combination were tested for comparison. It was found that the photostimulated light (PSL) read out of the imaging plate was directly proportional to the exposure time. It was also found that radiography with neutron using the imaging plate was approximately 40 times faster than the conventional neutron radiography using x-ray film/Gd converter screen combination. The sensitivity of the imaging plate to gamma-rays was investigated by using gamma-rays from an 192 Ir and a 60 Co radiographic sources. The imaging plate was found to be 5-6 times less sensitive to gamma-rays than a FUJI BAS-MS 2040 gamma-ray imaging plate. Finally, some specimens were selected to be radiographed with neutrons using the imaging plate and the x-ray film/Gd converter screen combination in comparison to x-rays. Parts containing light elements could be clearly observed by the two neutron radiographic techniques. It could be concluded that the image quality from the neutron imaging plate was comparable to the conventional x-ray film/Gd converter screen combination but the exposure time could be approximately reduced by a factor of 40

Ultracold neutrons

International Nuclear Information System (INIS)

Steenstrup, S.

Briefly surveys recent developments in research work with ultracold neutrons (neutrons of very low velocity, up to 10 m/s at up to 10 -7 eV and 10 -3 K). Slow neutrons can be detected in an ionisation chamber filled with B 10 F 3 . Very slow neutrons can be used for investigations into the dipole moment of neutrons. Neutrons of large wave length have properties similar to those of light. The limit angle for total reflection is governed by the wave length and by the material. Total reflection can be used to filter ultracold neutrons out of the moderator material of a reactor. Total reflection can also be used to store ultracold neutrons but certain problems with storage have not yet been clarified. Slow neutrons can be made to lose speed in a neutron turbine, and come out as ultracold neutrons. A beam of ultracold neutrons could be used in a neutron microscope. (J.S.)

Basic research of neutron radiography using cold neutron beam

International Nuclear Information System (INIS)

Oda, Masahiro; Tamaki, Masayoshi; Tasaka, Kanji

1995-01-01

As the result of demanding high quality images, now the nuclear reactors which can supply stably intense neutron beam have become the most general neutron source for radiography. For the purpose, mostly thermal neutrons have been used, but it is indispensable to use other neutrons than thermal neutrons for advancing neutron radiography technology and expanding the application fields. The radiography using cold neutrons is most behind in the development because the suitable neutron source was not available in Japan. The neutron sources for exclusively obtaining intense cold neutron beam were installed in the Kyoto University reactor in 1986 and in the JRR-3M of Japan Atomic Energy Research Institute in 1991. Basically as neutron energy lowers, the cross section of substances increases. In certain crystalline substances, the Bragg cutoff arises. The removal of scattered neutrons, the measurement of parallelism of beam and the relation of the thickness of objects with the transmissivity of cold neutrons are described. The imaging by TV method and the cold neutron CT in the CNRF and the simplified neutron CT by film method are reported. (K.I.)

Technological evolution of the fluorescent lamps for the domestic sector; Evolucion tecnologica de lamparas fluorescentes para el sector domestico

Energy Technology Data Exchange (ETDEWEB)

Valera Negrete, A. [Programa de Ahorro de Energia para el Sector Electrico, Mexico, D. F. (Mexico)

1995-12-31

This paper shows the efficiency, the harmonic distortion and the power factor of compact and circular fluorescent lamps that replace the incandescent bulbs of 60, 75 and 100 Watts in the domestic sector offered by manufacturers to increase the efficient use of the electric energy in networks of the national electric system. Also are presented, the quality parameters such as color temperature, performance index, useful life and maintenance of the lighting source; the aesthetics as length and weight and additionally the safety measures (thermal protector) that make competitive and functional the use of fluorescent lamps in relation to the installation of incandescent bulbs. [Espanol] En este trabajo se muestran las eficacias, distorsion de armonica y factor de potencia de lamparas fluorescentes compactas y circulares, que sustituyen a focos incandescentes de 60, 75 y 100 W en el sector domestico, ofrecidas por los fabricantes para aumentar el uso eficiente de la energia electrica en las redes del sistema electrico nacional. Ademas, se presentan los parametros de calidad, como temperatura de color, indice de rendimiento de color, vida y mantenimiento de la fuente luminosa; de estetica como longitud y peso; y adicionalmente la medida de seguridad (protector termico); que hace competitivo y funcional el uso de lamparas fluorescentes respecto a la instalacion de focos incandescentes.

Technological evolution of the fluorescent lamps for the domestic sector; Evolucion tecnologica de lamparas fluorescentes para el sector domestico

Energy Technology Data Exchange (ETDEWEB)

Valera Negrete, A [Programa de Ahorro de Energia para el Sector Electrico, Mexico, D. F. (Mexico)

1996-12-31

This paper shows the efficiency, the harmonic distortion and the power factor of compact and circular fluorescent lamps that replace the incandescent bulbs of 60, 75 and 100 Watts in the domestic sector offered by manufacturers to increase the efficient use of the electric energy in networks of the national electric system. Also are presented, the quality parameters such as color temperature, performance index, useful life and maintenance of the lighting source; the aesthetics as length and weight and additionally the safety measures (thermal protector) that make competitive and functional the use of fluorescent lamps in relation to the installation of incandescent bulbs. [Espanol] En este trabajo se muestran las eficacias, distorsion de armonica y factor de potencia de lamparas fluorescentes compactas y circulares, que sustituyen a focos incandescentes de 60, 75 y 100 W en el sector domestico, ofrecidas por los fabricantes para aumentar el uso eficiente de la energia electrica en las redes del sistema electrico nacional. Ademas, se presentan los parametros de calidad, como temperatura de color, indice de rendimiento de color, vida y mantenimiento de la fuente luminosa; de estetica como longitud y peso; y adicionalmente la medida de seguridad (protector termico); que hace competitivo y funcional el uso de lamparas fluorescentes respecto a la instalacion de focos incandescentes.

Neutron stars as cosmic neutron matter laboratories

International Nuclear Information System (INIS)

Pines, D.

1986-01-01

Recent developments which have radically changed our understanding of the dynamics of neutron star superfluids and the free precession of neutron stars are summarized, and the extent to which neutron stars are cosmic neutron matter laboratories is discussed. 17 refs., 1 tab

Design of a versatile detector for the detection of charged particles, neutrons and gamma rays. Neutron interaction with the matter; Diseno de un detector versatil para la deteccion de particulas cargadas, neutrones y rayos gamma. Interaccion neutronica con la materia

Energy Technology Data Exchange (ETDEWEB)

Perez P, J J [Comision Nacional de Seguridad Nuclear y Salvaguardias, Mexico, D.F. (Mexico)

1991-07-01

The Fostron detector detects charged particles, neutrons and gamma rays with a reasonable discrimination power. Because the typical detectors for neutrons present a great uncertainty in the detection, this work was focused mainly to the neutron detection in presence of gamma radiation. Also there are mentioned the advantages and disadvantages of the Fostron detector.

Polarized neutrons

International Nuclear Information System (INIS)

Williams, W.G.

1988-01-01

The book on 'polarized neutrons' is intended to inform researchers in condensed matter physics and chemistry of the diversity of scientific problems that can be investigated using polarized neutron beams. The contents include chapters on:- neutron polarizers and instrumentation, polarized neutron scattering, neutron polarization analysis experiments and precessing neutron polarization. (U.K.)

Neutron spectra produced by moderating an isotopic neutron source

International Nuclear Information System (INIS)

Carrillo Nunnez, Aureliano; Vega Carrillo, Hector Rene

2001-01-01

A Monte Carlo study has been carried out to determine the neutron spectra produced by an isotopic neutron source inserted in moderating media. Most devices used for radiation protection have a response strongly dependent on neutron energy. ISO recommends several neutron sources and monoenergetic neutron radiations, but actual working situations have broad spectral neutron distributions extending from thermal to MeV energies, for instance, near nuclear power plants, medical applications accelerators and cosmic neutrons. To improve the evaluation of the dosimetric quantities, is recommended to calibrate the radiation protection devices in neutron spectra which are nearly like those met in practice. In order to complete the range of neutron calibrating sources, it seems useful to develop several wide spectral distributions representative of typical spectra down to thermal energies. The aim of this investigation was to use an isotopic neutron source in different moderating media to reproduce some of the neutron fields found in practice. MCNP code has been used during calculations, in these a 239PuBe neutron source was inserted in H2O, D2O and polyethylene moderators. Moderators were modeled as spheres and cylinders of different sizes. In the case of cylindrical geometry the anisotropy of resulting neutron spectra was calculated from 0 to 2 . From neutron spectra dosimetric features were calculated. MCNP calculations were validated by measuring the neutron spectra of a 239PuBe neutron source inserted in a H2O cylindrical moderator. The measurements were carried out with a multisphere neutron spectrometer with a 6LiI(Eu) scintillator. From the measurements the neutron spectrum was unfolded using the BUNKIUT code and the UTA4 response matrix. Some of the moderators with the source produce a neutron spectrum close to spectra found in actual applications, then can be used during the calibration of radiation protection devices

Neutron beam design for low intensity neutron and gamma-ray radioscopy using small neutron sources

CERN Document Server

Matsumoto, T

2003-01-01

Two small neutron sources of sup 2 sup 5 sup 2 Cf and sup 2 sup 4 sup 1 Am-Be radioisotopes were used for design of neutron beams applicable to low intensity neutron and gamma ray radioscopy (LINGR). In the design, Monte Carlo code (MCNP) was employed to generate neutron and gamma ray beams suited to LINGR. With a view to variable neutron spectrum and neutron intensity, various arrangements were first examined, and neutron-filter, gamma-ray shield and beam collimator were verified. Monte Carlo calculations indicated that with a suitable filter-shield-collimator arrangement, thermal neutron beam of 3,900 ncm sup - sup 2 s sup - sup 1 with neutron/gamma ratio of 7x10 sup 7 , and 25 ncm sup - sup 2 s sup - sup 1 with very large neutron/gamma ratio, respectively, could be produced by using sup 2 sup 5 sup 2 Cf(122 mu g) and a sup 2 sup 4 sup 1 Am-Be(37GBq)radioisotopes at the irradiation port of 35 cm from the neutron sources.

Neutron cooling and cold-neutron sources (1962); Refroidissement des neutrons et sources de neutrons froids (1962)

Energy Technology Data Exchange (ETDEWEB)

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

1962-07-01

Intense cold-neutron sources are useful in studying solids by the inelastic scattering of neutrons. The paper presents a general survey covering the following aspects: a) theoretical considerations put forward by various authors regarding thermalization processes at very low temperatures; b) the experiments that have been carried out in numerous laboratories with a view to comparing the different moderators that can be used; c) the cold neutron sources that have actually been produced in reactors up to the present time, and the results obtained with them. (author) [French] Des sources intenses de neutrons froids sont utiles pour l'etude des solides par diffusion inelastique des neutrons. On presente une revue d'ensemble: a) des considerations theoriques faites par divers auteurs sur les processus de thermalisation a tres basse temperature; b) des experiences faites dans de nombreux laboratoires pour comparer les divers moderateurs possibles; c) des sources de neutrons froids effectivement realisees dans des piles a ce jour, et des resultats obtenus avec ces sources. (auteur)

Development of an area monitor for neutrons using solid state nuclear track detector; Desenvolvimento de um monitor de area para neutrons utilizando detector solido de tracos nucleares

Energy Technology Data Exchange (ETDEWEB)

Zahn, G.S.

1994-12-31

An area monitor for neutrons composed of the solid state nuclear track detector (SSNTD) Makrofol DE, together with a (n,{alpha}) converter, in the center of a 25 cm diameter polyethylene sphere, is developed. The optimal electrochemical etching conditions for the detection of thermal neutrons by the Makrofol DE using the BN converter are studied, leading to the choice of 55 min, at 30{sup 0} C, under a 44,2 kV.cm{sup -1} electric field with oscillation frequency of 2,0 khz. The response of this system to thermal neutrons, in the optimal conditions, is of 2,76(10)x 10{sup -3} tr/n. Changing from the BN converter to a 2,73(3)g compressed boric acid tablet this value lowers to 3,88(17)x 10{sup -4} tr/n. The performance of the whole monitor in the detection of fast neutrons is examined using the BN converter and neutrons from a {sup 241} Am Be source, with a response of 4,4(2)x 10{sup 3} tr.mSv{sup -1}.cm{sup -2} and operational limits between 7(3){mu}Sv and 5,6(2)mSv. The result of the monitoring of the control room of the IPEN Cyclotron accelerator are also presented as a final test for the viability of the practical use of the monitor. (author). 34 refs, 15 figs, 6 tabs, 1 app.

Experimental verification of a new neutron spectrometer for environmental dosimetry and area; Verficiacion experimental de un nuevo espectrometro de neutrones para dosimetria ambiental y de area

Energy Technology Data Exchange (ETDEWEB)

Gomez-Ros, J. M.; Romero, A.; Begogini, R.; Esposito, A.; Moraleda, M.; Lagares, J. I.; Sansaloni, F.; Arce, P.; Llop, J.

2011-07-01

In this communication, we present experimental results with a new neutron spectrometer, developed jointly by the Radiation Dosimetry Unit of CIEMAT Unita di Fisica and INFN-LNF Sanitary (Italy), consisting of a polyethylene moderating sphere detectors thermal neutrons (paired thermoluminescent dosimeters and activation foils) located in different positions. The device configuration and distribution of dosimeters are designed to elicit a response in a nearly isotropic up to 20 MeV energy range. (Author)

Neutron radiography

International Nuclear Information System (INIS)

Hrdlicka, Z.

1977-01-01

Neutron radiography is a radiographic method using a neutron beam of a defined geometry. The neutron source usually consists of a research reactor, a specialized neutron radiography reactor or the 252 Cf radioisotope source. There are two types of the neutron radiography display system, viz., a system producing neutron radiography images by a photographic process or a system allowing a visual display, eg., using a television monitor. The method can be used wherever X-ray radiography is used except applications in the radiography of humans. The neutron radiography unit at UJV uses the WWR-S reactor as the neutron source and both types of the above mentioned display system. (J.P.)

Neutron matter, neutron pairing, and neutron drops based on chiral effective field theory interactions

Energy Technology Data Exchange (ETDEWEB)

Krueger, Thomas

2016-10-19

The physics of neutron-rich systems is of great interest in nuclear and astrophysics. Precise knowledge of the properties of neutron-rich nuclei is crucial for understanding the synthesis of heavy elements. Infinite neutron matter determines properties of neutron stars, a final stage of heavy stars after a core-collapse supernova. It also provides a unique theoretical laboratory for nuclear forces. Strong interactions are determined by quantum chromodynamics (QCD). However, QCD is non-perturbative at low energies and one presently cannot directly calculate nuclear forces from it. Chiral effective field theory circumvents these problems and connects the symmetries of QCD to nuclear interactions. It naturally and systematically includes many-nucleon forces and gives access to uncertainty estimates. We use chiral interactions throughout all calculation in this thesis. Neutron stars are very extreme objects. The densities in their interior greatly exceed those in nuclei. The exact composition and properties of neutron stars is still unclear but they consist mainly of neutrons. One can explore neutron stars theoretically with calculations of neutron matter. In the inner core of neutron stars exist very high densities and thus maybe exotic phases of matter. To investigate whether there exists a phase transition to such phases even at moderate densities we study the chiral condensate in neutron matter, the order parameter of chiral symmetry breaking, and find no evidence for a phase transition at nuclear densities. We also calculate the more extreme system of spin-polarised neutron matter. With this we address the question whether there exists such a polarised phase in neutron stars and also provide a benchmark system for lattice QCD. We find spin-polarised neutron matter to be an almost non-interacting Fermi gas. To understand the cooling of neutron stars neutron pairing is of great importance. Due to the high densities especially triplet pairing is of interest. We

The Los Alamos Neutron Science Center Spallation Neutron Sources

International Nuclear Information System (INIS)

Nowicki, Suzanne F.; Wender, Stephen A.; Mocko, Michael

2017-01-01

The Los Alamos Neutron Science Center (LANSCE) provides the scientific community with intense sources of neutrons, which can be used to perform experiments supporting civilian and national security research. These measurements include nuclear physics experiments for the defense program, basic science, and the radiation effect programs. This paper focuses on the radiation effects program, which involves mostly accelerated testing of semiconductor parts. When cosmic rays strike the earth's atmosphere, they cause nuclear reactions with elements in the air and produce a wide range of energetic particles. Because neutrons are uncharged, they can reach aircraft altitudes and sea level. These neutrons are thought to be the most important threat to semiconductor devices and integrated circuits. The best way to determine the failure rate due to these neutrons is to measure the failure rate in a neutron source that has the same spectrum as those produced by cosmic rays. Los Alamos has a high-energy and a low-energy neutron source for semiconductor testing. Both are driven by the 800-MeV proton beam from the LANSCE accelerator. The high-energy neutron source at the Weapons Neutron Research (WNR) facility uses a bare target that is designed to produce fast neutrons with energies from 100 keV to almost 800 MeV. The measured neutron energy distribution from WNR is very similar to that of the cosmic-ray-induced neutrons in the atmosphere. However, the flux provided at the WNR facility is typically 5×107 times more intense than the flux of the cosmic-ray-induced neutrons. This intense neutron flux allows testing at greatly accelerated rates. An irradiation test of less than an hour is equivalent to many years of neutron exposure due to cosmic-ray neutrons. The low-energy neutron source is located at the Lujan Neutron Scattering Center. It is based on a moderated source that provides useful neutrons from subthermal energies to ~100 keV. The characteristics of these sources

The Los Alamos Neutron Science Center Spallation Neutron Sources

Science.gov (United States)

Nowicki, Suzanne F.; Wender, Stephen A.; Mocko, Michael

The Los Alamos Neutron Science Center (LANSCE) provides the scientific community with intense sources of neutrons, which can be used to perform experiments supporting civilian and national security research. These measurements include nuclear physics experiments for the defense program, basic science, and the radiation effect programs. This paper focuses on the radiation effects program, which involves mostly accelerated testing of semiconductor parts. When cosmic rays strike the earth's atmosphere, they cause nuclear reactions with elements in the air and produce a wide range of energetic particles. Because neutrons are uncharged, they can reach aircraft altitudes and sea level. These neutrons are thought to be the most important threat to semiconductor devices and integrated circuits. The best way to determine the failure rate due to these neutrons is to measure the failure rate in a neutron source that has the same spectrum as those produced by cosmic rays. Los Alamos has a high-energy and a low-energy neutron source for semiconductor testing. Both are driven by the 800-MeV proton beam from the LANSCE accelerator. The high-energy neutron source at the Weapons Neutron Research (WNR) facility uses a bare target that is designed to produce fast neutrons with energies from 100 keV to almost 800 MeV. The measured neutron energy distribution from WNR is very similar to that of the cosmic-ray-induced neutrons in the atmosphere. However, the flux provided at the WNR facility is typically 5×107 times more intense than the flux of the cosmic-ray-induced neutrons. This intense neutron flux allows testing at greatly accelerated rates. An irradiation test of less than an hour is equivalent to many years of neutron exposure due to cosmic-ray neutrons. The low-energy neutron source is located at the Lujan Neutron Scattering Center. It is based on a moderated source that provides useful neutrons from subthermal energies to ∼100 keV. The characteristics of these sources, and

Sequia inminente de neutrones en Europa Cuatro regiones aspiran a la nueva fuente europea de espalacion, pendiente de una decision politica

CERN Multimedia

Elvira, M

2002-01-01

"Faltan neutrones. Dicho asi, puede parecer extrano, pero es cierto. Los cientificos e ingenieros no tienen suficientes neutrones para observar la materia a nivel microscopico como les gustaria. Se asoman a posibilidades que les seducen pero no pueden ir mas alla por falta de una cantidad suficiente de estas particulas, que deben ser generadas en reactores o aceleradores " (2 pages).

Workshop on polarized neutron filters and polarized pulsed neutron experiments

International Nuclear Information System (INIS)

Itoh, Shinichi

2004-07-01

The workshop was held in KEK by thirty-three participants on April 26, 2004. The polarized neutron filter method was only discussed. It consists of three parts; the first part was discussed on the polarized neutron methods, the second part on the polarized neutron experiments and the third on the pulse neutron spectrometer and polarized neutron experiments. The six papers were presented such as the polarized 3 He neutron spin filter, neutron polarization by proton polarized filter, soft master and neutron scattering, polarized neutron in solid physics, polarization experiments by chopper spectroscope and neutron polarization system in superHRPD. (S.Y.)

Neutron matter, symmetry energy and neutron stars

Energy Technology Data Exchange (ETDEWEB)

Stefano, Gandolfi [Los Alamos National Laboratory (LANL); Steiner, Andrew W [ORNL

2016-01-01

Recent progress in quantum Monte Carlo with modern nucleon-nucleon interactions have enabled the successful description of properties of light nuclei and neutron-rich matter. Of particular interest is the nuclear symmetry energy, the energy cost of creating an isospin asymmetry, and its connection to the structure of neutron stars. Combining these advances with recent observations of neutron star masses and radii gives insight into the equation of state of neutron-rich matter near and above the saturation density. In particular, neutron star radius measurements constrain the derivative of the symmetry energy.

Fail-safe neutron shutter used for thermal neutron radiography

International Nuclear Information System (INIS)

Sachs, R.D.; Morris, R.A.

1976-11-01

A fail-safe, reliable, easy-to-use neutron shutter was designed, built, and put into operation at the Omega West Reactor, Los Alamos Scientific Laboratory. The neutron shutter will be used primarily to perform thermal neutron radiography, but is also available for a highly collimated source of thermal neutrons [neutron flux = 3.876 x 10 6 (neutrons)/(cm 2 .s)]. Neutron collimator sizes of either 10.16 by 10.16 cm or 10.16 by 30.48 cm are available

Test and validation of the iterative code for the neutrons spectrometry and dosimetry: NSDUAZ; Prueba y validacion del codigo iterativo para la espectrometria y dosimetria de neutrones: NSDUAZ

Energy Technology Data Exchange (ETDEWEB)

Reyes H, A.; Ortiz R, J. M.; Reyes A, A.; Castaneda M, R.; Solis S, L. O.; Vega C, H. R., E-mail: alfredo_reyesh@hotmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Ingenieria Electrica, Av. Lopez Velarde 801, Col. Centro, 98000 Zacatecas (Mexico)

2014-08-15

In this work was realized the test and validation of an iterative code for neutronic spectrometry known as Neutron Spectrometry and Dosimetry of the Universidad Autonoma de Zacatecas (NSDUAZ). This code was designed in a user graph interface, friendly and intuitive in the environment programming of LabVIEW using the iterative algorithm known as SPUNIT. The main characteristics of the program are: the automatic selection of the initial spectrum starting from the neutrons spectra catalog compiled by the International Atomic Energy Agency, the possibility to generate a report in HTML format that shows in graph and numeric way the neutrons flowing and calculates the ambient dose equivalent with base to this. To prove the designed code, the count rates of a spectrometer system of Bonner spheres were used with a detector of {sup 6}LiI(Eu) with 7 polyethylene spheres with diameter of 0, 2, 3, 5, 8, 10 and 12. The count rates measured with two neutron sources: {sup 252}Cf and {sup 239}PuBe were used to validate the code, the obtained results were compared against those obtained using the BUNKIUT code. We find that the reconstructed spectra present an error that is inside the limit reported in the literature that oscillates around 15%. Therefore, it was concluded that the designed code presents similar results to those techniques used at the present time. (Author)

A Time of flight spectrometer for measurements of double differential neutron scattering cross sections; Montaje de un espectrometro por tiempo de vuelo para la medicion de secciones doble diferenciales de dispersion de neutrones

Energy Technology Data Exchange (ETDEWEB)

Padron, I; Dominguez, O; Sarria, P. Sandin, C. [Centro de Estudios Aplicados al Desarrollo Nuclear (CEADEN), La Habana (Cuba)

1996-05-01

The time -of-Flight neutron spectrometry technique by associated particle method was improved using a D-T neutron generator at Laboratory of Nuclear Analysis. This technique was implemented for double differential cross section measurements and supported by the IAEA Project CUB/01/005. An stilbene scintillation detector (dia=100 mm, length=50 mm) was used as principal neutron detector detector and was situated outside a hole in the concrete wall. This way the fligth path was extended and the scattered neutron cone accurate collimated throught the 2 m concrete wall. For the associated particle {alpha} detection a thin plastic NE-102 scint illator was used, as well as, two scintilation detectors and a long counter for the neutron flux monitoring. In this TOF neutron spectrometer (3.40 m flight path) a 1.7 nseg. temporal resolution was obtained.

Extraction of the neutron-neutron scattering length ann from kinematically complete neutron-deuteron breakup experiments

International Nuclear Information System (INIS)

Witala, H.; Hueber, D.; Gloeckle, W.; Tornow, W.; Gonzalez Trotter, D.E.

1996-01-01

Data for the neutron-neutron final-state-interaction cross section obtained recently in a kinematically complete neutron-deuteron breakup experiment have been reanalyzed using rigorous solutions of the three-nucleon Faddeev equations with realistic nucleon-nucleon interactions. A discrepancy was found with respect to a recent analysis based on the W-matrix approximation to the Paris potential. We also estimate theoretical uncertainties in extracting the neutron-neutron scattering length resulting from the use of different nucleon-nucleon interactions and the possible action of the two pion-exchange three-nucleon force. We find that there exists a certain production angle for the interacting neutron-neutron pair where the uncertainties become minimal. (author)

Neutron Absorbing Ability Variation in Neutron Absorbing Material Caused by the Neutron Irradiation in Spent Fuel Storage Facility

Energy Technology Data Exchange (ETDEWEB)

Sohn, Hee Dong; Han, Seul Gi; Lee, Sang Dong; Kim, Ki Hong; Ryu, Eag Hyang; Park, Hwa Gyu [Doosan Heavy Industries and Construction, Changwon (Korea, Republic of)

2014-10-15

In spent fuel storage facility like high density spent fuel storage racks and dry storage casks, spent fuels are stored with neutron absorbing materials installed as a part of those facilities, and they are used for absorbing neutrons emitted from spent fuels. Usually structural material with neutron absorbing material of racks and casks are located around spent fuels, so it is irradiated by neutrons for long time. Neutron absorbing ability could be changed by the variation of nuclide composition in neutron absorbing material caused by the irradiation of neutrons. So, neutron absorbing materials are continuously faced with spent fuels with boric acid solution or inert gas environment. Major nuclides in neutron absorbing material are Al{sup 27}, C{sup 12}, B{sup 11}, B{sup 10} and they are changed to numerous other ones as radioactive decay or neutron absorption reaction. The B{sup 10} content in neutron absorbing material dominates the neutron absorbing ability, so, the variation of nuclide composition including the decrease of B{sup 10} content is the critical factor on neutron absorbing ability. In this study, neutron flux in spent fuel, the activation of neutron absorbing material and the variation of nuclide composition are calculated. And, the minimum neutron flux causing the decrease of B{sup 10} content is calculated in spent fuel storage facility. Finally, the variation of neutron multiplication factor is identified according to the one of B{sup 10} content in neutron absorbing material. The minimum neutron flux to impact the neutron absorbing ability is 10{sup 10} order, however, usual neutron flux from spent fuel is 10{sup 8} order. Therefore, even though neutron absorbing material is irradiated for over 40 years, B{sup 10} content is little decreased, so, initial neutron absorbing ability could be kept continuously.

Neutron optics using transverse field neutron spin echo method

International Nuclear Information System (INIS)

Achiwa, Norio; Hino, Masahiro; Yamauchi, Yoshihiro; Takakura, Hiroyuki; Tasaki, Seiji; Akiyoshi, Tsunekazu; Ebisawa, Toru.

1993-01-01

A neutron spin echo (NSE) spectrometer with perpendicular magnetic field to the neutron scattering plane, using an iron yoke type electro-magnet has been developed. A combination of cold neutron guider, supermirror neutron polarizer of double reflection type and supermirror neutron analyser was adopted for the spectrometer. The first application of the NSE spectrometer to neutron optics by passing Larmor precessing neutrons through gas, solid and liquid materials of several different lengths which are inserted in one of the precession field have been examined. Preliminary NSE spectra of this sample geometry are discussed. (author)

Critical heat flux, post dry-out and their augmentation

Energy Technology Data Exchange (ETDEWEB)

Celata, G.P.; Mariani, A. [ENEA, Centro Ricerche Casaccia, S. Maria di Galeria, RM (Italy). Dipt. Energia

1999-07-01

The report shows the state of art review on the critical heat flux and the post-dryout heat transfer. The work, which is a merge of original researches carried out at the Institute of Thermal Fluid Dynamic of ENEA (National Agency for New Technology, Energy and the Environment) and a thorough review of the recent literature, is divided in four chapters: critical heat flux in subcooled flow boiling; critical heat flux in saturated flow boiling; post-dryout heat transfer; enhancement of critical heat flux and post-dryout heat transfer. [Italian] Si passa in rassegna lo stato dell'arte sulla crisi termica e sullo scambio termico post-crisi, che compendia studi tradizionali condotti dall'ENEA. Il rapporto e' suddiviso in quattro parti: crisi termica in ebollizione sottoraffreddata; crisi termica in ebollizione satura; scambio termico dopo la crisi termica; incremento del flusso termico critico e dello scambio termico post-crisi.

Critical heat flux, post dry-out and their augmentation

Energy Technology Data Exchange (ETDEWEB)

Celata, G P; Mariani, A [ENEA, Centro Ricerche Casaccia, S. Maria di Galeria, RM (Italy). Dipt. Energia

1999-07-01

The report shows the state of art review on the critical heat flux and the post-dryout heat transfer. The work, which is a merge of original researches carried out at the Institute of Thermal Fluid Dynamic of ENEA (National Agency for New Technology, Energy and the Environment) and a thorough review of the recent literature, is divided in four chapters: critical heat flux in subcooled flow boiling; critical heat flux in saturated flow boiling; post-dryout heat transfer; enhancement of critical heat flux and post-dryout heat transfer. [Italian] Si passa in rassegna lo stato dell'arte sulla crisi termica e sullo scambio termico post-crisi, che compendia studi tradizionali condotti dall'ENEA. Il rapporto e' suddiviso in quattro parti: crisi termica in ebollizione sottoraffreddata; crisi termica in ebollizione satura; scambio termico dopo la crisi termica; incremento del flusso termico critico e dello scambio termico post-crisi.

Phonons in Solid Hydrogen and Deuterium Studied by Inelastic Coherent Neutron Scattering

DEFF Research Database (Denmark)

Nielsen, Mourits

1973-01-01

Phonon dispersion relations have been measured by coherent neutron scattering in solid para-hydrogen and ortho-deuterium. The phonon energies are found to be nearly equal in the two solids, the highest energy in each case lying close to 10 meV. The pressure and temperature dependence of the phonon...... energies have been measured in ortho-deuterium and the lattice change determined by neutron diffraction. When a pressure of 275 bar is applied, the phonon energies are increased by about 10%, and heating the crystal to near the melting point decreases them by about 7%. The densities of states, the specific...... heats, and the Debye temperatures have been deduced and found to be in agreement with the published experimental results. The Debye temperatures are 118 K for hydrogen and 114 K for deuterium. For hydrogen the Debye-Waller factor has been measured by incoherent neutron scattering and it corresponds...

Neutron radiography

International Nuclear Information System (INIS)

Hiraoka, Eiichi

1988-01-01

The thermal neutron absorption coefficient is essentially different from the X-ray absorption coefficient. Each substance has a characteristic absorption coefficient regardless of its density. Neutron deams have the following features: (1) neutrons are not transmitted efficiently by low molecular weight substances, (2) they are transmitted efficiently by heavy metals, and (3) the transmittance differs among isotopes. Thus, neutron beams are suitable for cheking for foreign matters in heavy metals and testing of composites consisting of both heavy and light materials. A neutron source generates fast neutrons, which should be converted into thermal neutrons by reducing their energy. Major neutron souces include nuclear reactors, radioisotopes and particle accelerators. Photographic films and television systems are mainly used to observe neutron transmission images. Computers are employed for image processing, computerized tomography and three-dimensional analysis. The major applications of neutron radiography include inspection of neclear fuel; evaluation of material for airplane; observation of fuel in the engine and oil in the hydraulic systems in airplanes; testing of composite materials; etc. (Nogami, K.)

Neutron Dosimetry

International Nuclear Information System (INIS)

Vanhavere, F.

2001-01-01

The objective of SCK-CEN's R and D programme on neutron dosimetry is to improve the determination of neutron doses by studying neutron spectra, neutron dosemeters and shielding adaptations. In 2000, R and D focused on the contiued investigation of the bubble detectors type BD-PND and BDT, in particular their sensitivity and temperature dependence; the updating of SCK-CEN's criticality dosemeter, the investigation of the characteristics of new thermoluminescent materials and their use in neutron dosemetry; and the investigation of neutron shielding

Neutron Dosimetry

Energy Technology Data Exchange (ETDEWEB)

Vanhavere, F

2001-04-01

The objective of SCK-CEN's R and D programme on neutron dosimetry is to improve the determination of neutron doses by studying neutron spectra, neutron dosemeters and shielding adaptations. In 2000, R and D focused on the contiued investigation of the bubble detectors type BD-PND and BDT, in particular their sensitivity and temperature dependence; the updating of SCK-CEN's criticality dosemeter, the investigation of the characteristics of new thermoluminescent materials and their use in neutron dosemetry; and the investigation of neutron shielding.

Study of liquid hydrogen and liquid deuterium cold neutron sources

International Nuclear Information System (INIS)

Harig, H.D.

1969-01-01

In view of the plant of the cold neutron source for a high flux reactor (maximal thermal flux of about 10 15 n/cm 2 s) an experimental study of several cold sources of liquid hydrogen and liquid deuterium has been made in a low power reactor (100 kW, about 10 12 n/cm 2 s). We have investigated: -cold neutron sources of liquid hydrogen shaped as annular layers of different thickness. Normal liquid hydrogen was used as well as hydrogen with a high para-percentage. -Cold neutron sources of liquid deuterium in cylinders of 18 and 38 cm diameter. In this case the sources could be placed into different positions to the reactor core within the heavy water reflector. This report gives a general description of the experimental device and deals more detailed with the design of the cryogenic systems. Then, the measured results are communicated, interpreted and finally compared with those of a theoretical study about the same cold moderators which have been the matter of the experimental investigation. (authors) [fr

Neutronic analysis of JET external neutron monitor response

Energy Technology Data Exchange (ETDEWEB)

Snoj, Luka, E-mail: luka.snoj@ijs.si [Reactor Physics Division, Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Lengar, Igor; Čufar, Aljaž [Reactor Physics Division, Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Syme, Brian; Popovichev, Sergey [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon, OX14 3DB, United Kingdom (United Kingdom); Batistoni, Paola [ENEA C. R. Frascati, via E. Fermi 45, 00044 Frascati, Roma (Italy); Conroy, Sean [VR Association, Uppsala University, Department of Physics and Astronomy, PO Box 516, SE-75120 Uppsala (Sweden)

2016-11-01

Highlights: • We model JET tokamak containing JET remote handling system. • We investigate effect of remote handling system on external neutron monitor response. • Remote handling system correction factors are calculated. • Integral correction factors are relatively small, i.e up to 8%. - Abstract: The power output of fusion devices is measured in terms of the neutron yield which relates directly to the fusion yield. JET made a transition from Carbon wall to ITER-Like Wall (Beryllium/Tungsten/Carbon) during 2010–11. Absolutely calibrated measurement of the neutron yield by JET neutron monitors was ensured by direct measurements using a calibrated {sup 252}Cf neutron source (NS) deployed by the in-vessel remote handling system (RHS) inside the JET vacuum vessel. Neutronic calculations were required in order to understand the neutron transport from the source in the vacuum vessel to the fission chamber detectors mounted outside the vessel on the transformer limbs of the tokamak. We developed a simplified computational model of JET and the JET RHS in Monte Carlo neutron transport code MCNP and analyzed the paths and structures through which neutrons reach the detectors and the effect of the JET RHS on the neutron monitor response. In addition we performed several sensitivity studies of the effect of substantial massive structures blocking the ports on the external neutron monitor response. As the simplified model provided a qualitative picture of the process only, some calculations were repeated using a more detailed full 3D model of the JET tokamak.

Investigation of Response of Several Neutron Surveymeters by a DT Neutron Generator

International Nuclear Information System (INIS)

Kim, Sang In; Jang, In Su; Kim, Jang Lyul; Lee, Jung IL; Kim, Bong Hwan

2012-01-01

Several neutron measuring devices were tested under the neutron fields characterized with two distinct kinds of thermal and fast neutron spectrum. These neutron fields were constructed by the mixing of both thermal neutron fields and fast neutron fields. The thermal neutron field was constructed using by a graphite pile with eight AmBe neutron sources. The fast neutron field of 14 MeV was made by a DT neutron generator. In order to change the fraction of fast neutron fluence rate in each neutron fields, a neutron generator was placed in the thermal neutron field at 50 cm and 150 cm from the reference position. The polyethylene neutron collimator was used to make moderated 14 MeV neutron field. These neutron spectra were measured by using a Bonner sphere system with an LiI scintillator, and dosimetric quantities delivered to neutron surveymeters were determined from these measurement results.

Neutron Imaging at Compact Accelerator-Driven Neutron Sources in Japan

Directory of Open Access Journals (Sweden)

Yoshiaki Kiyanagi

2018-03-01

Full Text Available Neutron imaging has been recognized to be very useful to investigate inside of materials and products that cannot be seen by X-ray. New imaging methods using the pulsed structure of neutron sources based on accelerators has been developed also at compact accelerator-driven neutron sources and opened new application fields in neutron imaging. The world’s first dedicated imaging instrument at pulsed neutron sources was constructed at J-PARC in Japan owing to the development of such new methods. Then, usefulness of the compact accelerator-driven neutron sources in neutron science was recognized and such facilities were newly constructed in Japan. Now, existing and new sources have been used for neutron imaging. Traditional imaging and newly developed pulsed neutron imaging such as Bragg edge transmission have been applied to various fields by using compact and large neutron facilities. Here, compact accelerator-driven neutron sources used for imaging in Japan are introduced and some of their activities are presented.

Accelerator based neutron source for neutron capture therapy

International Nuclear Information System (INIS)

Salimov, R.; Bayanov, B.; Belchenko, Yu.; Belov, V.; Davydenko, V.; Donin, A.; Dranichnikov, A.; Ivanov, A.; Kandaurov, I; Kraynov, G.; Krivenko, A.; Kudryavtsev, A.; Kursanov, N.; Savkin, V.; Shirokov, V.; Sorokin, I.; Taskaev, S.; Tiunov, M.

2004-01-01

Full text: The Budker Institute of Nuclear Physics (Novosibirsk) and the Institute of Physics and Power Engineering (Obninsk) have proposed an accelerator based neutron source for neutron capture and fast neutron therapy for hospital. Innovative approach is based upon vacuum insulation tandem accelerator (VITA) and near threshold 7 Li(p,n) 7 Be neutron generation. Pilot accelerator based neutron source for neutron capture therapy is under construction now at the Budker Institute of Nuclear Physics, Novosibirsk, Russia. In the present report, the pilot facility design is presented and discussed. Design features of facility components are discussed. Results of experiments and simulations are presented. Complete experimental tests are planned by the end of the year 2005

Design of hyper-thermal neutron irradiation fields for neutron capture therapy in KUR-heavy water neutron irradiation facility. Mounting of hyper-thermal neutron converter in therapeutic collimator

International Nuclear Information System (INIS)

Sakurai, Y.; Kobayashi, T.

2001-01-01

Neutron capture therapy (NCP) using thermal neutron needs to improve of depth dose distribution in a living body. Epi-thermal neutron following moderation of fast neutron is usually used for improving of the depth dose distribution. The moderation method of fast neutron, however, gets mixed some of high energy neutron which give some of serious effects to a living body, and involves the difficulty for collimation of thermal neutron to the diseased part. Hyper-thermal neutrons, which are in an energy range of 0.1-3 eV at high temperature side of thermal neutron, are under consideration for application to the NCP. The hyper-thermal neutrons can be produced by up-scattering of thermal neutron in a high temperature material. Fast neutron components in collimator for the NCP reduce on application of the up-scattering method. Graphite at high temperature (>1000k) is used as a hyper-thermal neutron converter. The hyper-thermal neutron converter is planted to mount on therapeutic collimator which is located at the nearest side of patient for the NCP. Total neutron flux, ratio of hyper-thermal neutron to total neutron, and ratio of gamma-ray dose to neutron flux are calculated as a function of thickness of the graphite converter using monte carlo code MCNP-V4B. (M. Suetake)

The secondary neutron sources for generation of particular neutron fluxes

International Nuclear Information System (INIS)

Tracz, G.

2007-07-01

The foregoing paper presents the doctor's thesis entitled '' The secondary neutron sources for generation of particular neutron fluxes ''. Two secondary neutron sources have been designed, which exploit already existing primary sources emitting neutrons of energies different from the desired ones. The first source is devoted to boron-neutron capture therapy (BNCT). The research reactor MARIA at the Institute of Atomic Energy in Swierk (Poland) is the primary source of the reactor thermal neutrons, while the secondary source should supply epithermal neutrons. The other secondary source is the pulsed source of thermal neutrons that uses fast 14 MeV neutrons from a pulsed generator at the Institute of Nuclear Physics PAN in Krakow (Poland). The physical problems to be solved in the two mentioned cases are different. Namely, in order to devise the BNCT source the initial energy of particles ought to be increased, whilst in the other case the fast neutrons have to be moderated. Slowing down of neutrons is relatively easy since these particles lose energy when they scatter in media; the most effective moderators are the materials which contain light elements (mostly hydrogen). In order to increase the energy of neutrons from thermal to epithermal (the BNCT case) the so-called neutron converter should be exploited. It contains a fissile material, 235 U. The thermal neutrons from the reactor cause fission of uranium and fast neutrons are emitted from the converter. Then fissile neutrons of energy of a few MeV are slowed down to the required epithermal energy range. The design of both secondary sources have been conducted by means of Monte Carlo simulations, which have been carried out using the MCNP code. In the case of the secondary pulsed thermal neutron source, some of the calculated results have been verified experimentally. (author)

Bioclimatic conditioning places for propagation the plants; Acondicionamiento Bioclimatico de locales para programacion de plantas

Energy Technology Data Exchange (ETDEWEB)

Iriarte, Adolfo [Catamarca, (Argentina); Lesino, Gabriela [Buenos Aires, (Argentina); Matias, Cesar [Catamarca, (Argentina)

2000-07-01

y masa, distribucion de temperatura en la estructura, aire, camas de enraizamiento y humedades relativas internas y externas, asi como resultados termicos y agronomicos logrados durante condiciones de verano e invierno, destacandose que la eficiencia de produccion en verano estuvo entre el 43 y en 75 % y en invierno entre el 30 y 60 % para estacas de olivo.

Calculations to support JET neutron yield calibration: Modelling of neutron emission from a compact DT neutron generator

Science.gov (United States)

Čufar, Aljaž; Batistoni, Paola; Conroy, Sean; Ghani, Zamir; Lengar, Igor; Milocco, Alberto; Packer, Lee; Pillon, Mario; Popovichev, Sergey; Snoj, Luka; JET Contributors

2017-03-01

At the Joint European Torus (JET) the ex-vessel fission chambers and in-vessel activation detectors are used as the neutron production rate and neutron yield monitors respectively. In order to ensure that these detectors produce accurate measurements they need to be experimentally calibrated. A new calibration of neutron detectors to 14 MeV neutrons, resulting from deuterium-tritium (DT) plasmas, is planned at JET using a compact accelerator based neutron generator (NG) in which a D/T beam impinges on a solid target containing T/D, producing neutrons by DT fusion reactions. This paper presents the analysis that was performed to model the neutron source characteristics in terms of energy spectrum, angle-energy distribution and the effect of the neutron generator geometry. Different codes capable of simulating the accelerator based DT neutron sources are compared and sensitivities to uncertainties in the generator's internal structure analysed. The analysis was performed to support preparation to the experimental measurements performed to characterize the NG as a calibration source. Further extensive neutronics analyses, performed with this model of the NG, will be needed to support the neutron calibration experiments and take into account various differences between the calibration experiment and experiments using the plasma as a source of neutrons.

Calculations to support JET neutron yield calibration: Modelling of neutron emission from a compact DT neutron generator

Energy Technology Data Exchange (ETDEWEB)

Čufar, Aljaž, E-mail: aljaz.cufar@ijs.si [Reactor Physics Department, Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Batistoni, Paola [ENEA, Department of Fusion and Nuclear Safety Technology, I-00044 Frascati, Rome (Italy); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Conroy, Sean [Uppsala University, Department of Physics and Astronomy, PO Box 516, SE-75120 Uppsala (Sweden); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Ghani, Zamir [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Lengar, Igor [Reactor Physics Department, Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Milocco, Alberto; Packer, Lee [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Pillon, Mario [ENEA, Department of Fusion and Nuclear Safety Technology, I-00044 Frascati, Rome (Italy); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Popovichev, Sergey [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Snoj, Luka [Reactor Physics Department, Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); EUROfusion Consortium, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)

2017-03-01

At the Joint European Torus (JET) the ex-vessel fission chambers and in-vessel activation detectors are used as the neutron production rate and neutron yield monitors respectively. In order to ensure that these detectors produce accurate measurements they need to be experimentally calibrated. A new calibration of neutron detectors to 14 MeV neutrons, resulting from deuterium–tritium (DT) plasmas, is planned at JET using a compact accelerator based neutron generator (NG) in which a D/T beam impinges on a solid target containing T/D, producing neutrons by DT fusion reactions. This paper presents the analysis that was performed to model the neutron source characteristics in terms of energy spectrum, angle–energy distribution and the effect of the neutron generator geometry. Different codes capable of simulating the accelerator based DT neutron sources are compared and sensitivities to uncertainties in the generator's internal structure analysed. The analysis was performed to support preparation to the experimental measurements performed to characterize the NG as a calibration source. Further extensive neutronics analyses, performed with this model of the NG, will be needed to support the neutron calibration experiments and take into account various differences between the calibration experiment and experiments using the plasma as a source of neutrons.

Study of neutron fields around an intense neutron generator.

Science.gov (United States)

Kicka, L; Machrafi, R; Miller, A

2017-12-01

Neutron fields in the vicinity of the newly built neutron facility, at the University of Ontario Institute of Technology (UOIT), have been investigated in a series of Monte Carlo simulations and measurements. The facility hosts a P-385 neutron generator based on a deuterium-deuterium fusion reaction. The neutron fluence at different locations around the neutron generator facility has been simulated using MCNPX 2.7E Monte Carlo particle transport program. To characterize neutron fields, three neutron sources were modeled with distributions corresponding to different incident deuteron energies of 90kV, 110kV, and 130kV. Measurements have been carried out to determine the dose rate at locations adjacent to the generator using bubble detectors (BDs). The neutron intensity was evaluated and the total dose rates corresponding to different applied acceleration potentials were estimated at various locations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Miscellaneous neutron techniques

International Nuclear Information System (INIS)

Iddings, F.A.

1976-01-01

Attention is brought to the less often uses of neutrons in the areas of neutron radiography, well logging, and neutron gaging. Emphasis on neutron radiography points toward the isotopic sensitivity of the method versus the classical bulk applications. Also recognized is the ability of neutron radiography to produce image changes that correspond to thickness and density changes obtained in photon radiography. Similarly, neutron gaging applications center on the measurement of radiography. Similarly, neutron gaging applications center on the measurement of water, oil, or plastics in industrial samples. Well logging extends the neutron gaging to encompass many neutron properties and reactions besides thermalization and capture. Neutron gaging also gives information on organic structure and concentrations of a variety of elements or specific compounds in selected matrices

Discovery of the neutron (to the fiftieth anniversary of neutron discovery)

International Nuclear Information System (INIS)

Pasechnik, M.V.

1984-01-01

Development of neutron physics in the USSR for the recent 50 years from the moment of neutron discovery is considered. History of neutron discovery is presented in brief. Neutron properties and fundamental problems of physics: electric dipole neutron moment, neutron β-decay, neutron interaction with nuclei and potential of nucleon interaction not conserving spatial parity are discussed. Main aspects of neutron physics application in power engineering, nuclear technology and other branches of science and technique are set forth

Neutron rich matter, neutron stars, and their crusts

International Nuclear Information System (INIS)

Horowitz, C J

2011-01-01

Neutron rich matter is at the heart of many fundamental questions in Nuclear Physics and Astrophysics. What are the high density phases of QCD? Where did the chemical elements come from? What is the structure of many compact and energetic objects in the heavens, and what determines their electromagnetic, neutrino, and gravitational-wave radiations? Moreover, neutron rich matter is being studied with an extraordinary variety of new tools such as Facility for Rare Isotope Beams (FRIB) and the Laser Interferometer Gravitational Wave Observatory (LIGO). We describe the Lead Radius Experiment (PREX) that is using parity violation to measure the neutron radius in 208Pb. This has important implications for neutron stars and their crusts. Using large scale molecular dynamics, we model the formation of solids in both white dwarfs and neutron stars. We find neutron star crust to be the strongest material known, some 10 billion times stronger than steel. It can support mountains on rotating neutron stars large enough to generate detectable gravitational waves. Finally, we describe a new equation of state for supernova and neutron star merger simulations based on the Virial expansion at low densities, and large scale relativistic mean field calculations.

Measurement of scattering cross sections of liquid and solid hydrogen, deuterium and deuterium hydride for thermal neutrons

International Nuclear Information System (INIS)

Seiffert, W.D.

1984-01-01

The scattering cross sections for liquid and solid normal hydrogen, para-hydrogen, deuterium and deuterium hydride were measured for thermal neutrons at various temperatures. Solid samples of para-hydrogen exhibit distinct Bragg scattering. Liquid samples of deuterium and para-hydrogen also exhibit distinct coherence phenomena, which is indicative of strong local ordering of the molecules. In para-hydrogen and deuterium hydride, the threshold for scattering with excitation of rotations is distinctly visible. The positions of the thresholds show that the molecules in liquid hydrogen are not unhindered in their movement. After the beginning of the rotational excitation the scattering cross sections of liquid and solid para-hydrogen have different shapes which is to be explained by the differences in the dynamics of the liquid and the solid specimen. 22 references

Neutron Beam Filters

International Nuclear Information System (INIS)

Adib, M.

2011-01-01

The purpose of filters is to transmit neutrons with selected energy, while remove unwanted ones from the incident neutron beam. This reduces the background, and the number of spurious. The types of commonly used now-a-day neutron filters and their properties are discussed in the present work. There are three major types of neutron filters. The first type is filter of selective thermal neutron. It transmits the main reflected neutrons from a crystal monochromate, while reject the higher order contaminations accompanying the main one. Beams coming from the moderator always contain unwanted radiation like fast neutrons and gamma-rays which contribute to experimental background and to the biological hazard potential. Such filter type is called filter of whole thermal neutron spectrum. The third filter type is it transmits neutrons with energies in the resonance energy range (En . 1 KeV). The main idea of such neutron filter technique is the use of large quantities of a certain material which have the deep interference minima in its total neutron cross-section. By transmitting reactor neutrons through bulk layer of such material, one can obtain the quasimonochromatic neutron lines instead of white reactor spectrum.

Characterization of the neutron field of the {sup 241}AmBe in a calibration room; Caracterizacion del campo de neutrones del {sup 241} AmBe en una sala para calibracion

Energy Technology Data Exchange (ETDEWEB)

Vega C, H.R. [UAZ, A.P. 336, 98000 Zacatecas (Mexico); Gallego, E.; Lorente, A. [Universidad Politecnica de Madrid, C. Jose Gutierrez Abascal 2, 28006 Madrid (Spain)] e-mail: rvega@cantera.reduaz.mx

2003-07-01

The field of neutrons produced by an isotopic source of neutrons of {sup 241} Am Be had been characterized. The characterization was carried out modeling those relevant details of the calibration room and simulating the neutron transport at different distances of the source. The calculated spectra were used to determine the equivalent environmental dose rate. A series of experiments were carried out with the Bonner sphere spectrometric system to measure the spectra in the same points where the calculations were carried out and with these spectra the rates of environmental dose were calculated. By means of a one sphere dosemeter type Berthold the rates of environmental dose were measured. To the one to compare the calculated spectra and measured its were found small differences in the group of the thermal neutrons due to the elementary composition used during the simulation. When comparing the derived rates starting from the calculated spectra with those measured it was found a maxim difference smaller to 13%. (Author)

Neutron stochastic transport theory with delayed neutrons

International Nuclear Information System (INIS)

Munoz-Cobo, J.L.; Verdu, G.

1987-01-01

From the stochastic transport theory with delayed neutrons, the Boltzmann transport equation with delayed neutrons for the average flux emerges in a natural way without recourse to any approximation. From this theory a general expression is obtained for the Feynman Y-function when delayed neutrons are included. The single mode approximation for the particular case of a subcritical assembly is developed, and it is shown that Y-function reduces to the familiar expression quoted in many books, when delayed neutrons are not considered, and spatial and source effects are not included. (author)

Fundamental of neutron radiography and the present of neutron radiography in Japan

International Nuclear Information System (INIS)

Sekita, Junichiro

1988-01-01

Neutron radiography refers to the application of transmitted neutrons to analysis. In general, thermal neutron is used for neutron radiography. Thermal neutron is easily absorbed by light atoms, including hydrogen, boron and lithium, while it is not easily absorbed by such heavy atoms as tungsten, lead and uranium, permitting detection of impurities in heavy metals. Other neutrons than thermal neutron can also be applied. Cold neutron is produced from fast neutron using a moderator to reduce its energy down to below that of thermal neutron. Cold neutron is usefull for analysis of thick material. Epithermal neutron can induce resonance characteristic of each substance. With a relatively small reaction area, fast neutron permits observation of thick samples. Being electrically neutral, neutrons are difficult to detect by direct means. Thus a substance that releases charged particles is put in the path of neutrons for indirect measurement. X-ray film combined with converter screen for conversion of neutrons to charge particles is placed behind the sample. Photographing is carried out by a procedure similar to X-ray photography. Major institues and laboratories in Japan provided with neutron radiography facilities are listed. (Nogami, K.)

Monitoring system for thermal plasma; Sistema de monitoreo para plasma termico

Energy Technology Data Exchange (ETDEWEB)

Romero G, M.; Vilchis P, A.E. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

1999-07-01

In the Thermal plasma applications laboratory it has been the degradation project of oils for isolation in transformers. These are a very hazardous residues and at this time in the country they are stored in metal barrels. It has been the intention to undergo the oils to plasma for degradate them to non-hazardous residues. The system behavior must be monitored to establish the thermal plasma behavior. (Author)

Review of Non-Neutron and Neutron Nuclear Data, 2004

International Nuclear Information System (INIS)

Holden, Norman E.

2005-01-01

Review articles are in preparation for the 2004 edition of the CRC Handbook of Chemistry and Physics dealing with the evaluation of both non-neutron and neutron nuclear data. Data on the discovery of element 110, Darmstadtium, and element 111 have been officially accepted, while data on element 118 have been withdrawn. Data to be presented include revised values for very short-lived nuclides, long-lived nuclides, and beta-beta decay measurements. There has been a reassessment of the spontaneous fission (sf) half-lives, which distinguishes between sf decay half-lives and cluster decay half-lives, and with cluster-fission decay. New measurements of isotopic abundance values for many elements will be discussed with an emphasis on the minor isotopes of interest for use in neutron activation analysis measurements. Neutron resonance integrals will be discussed emphasizing the differences between the calculated values obtained from the analytical integration over neutron resonances and the measured values in a neutron reactor-spectrum, which does not quite conform to the assumed 1/E neutron energy spectrum. The method used to determine the neutron resonance integral from measurement, using neutron activation analysis, will be discussed

Procedure for measurement of anisotropy factor for neutron sources; Procedimentos para medição do fator de anisotropia de fontes de nêutrons

Energy Technology Data Exchange (ETDEWEB)

Creazolla, Prycylla Gomes

2017-07-01

Radioisotope neutron sources allow the production of reference fields for calibration of neutron detectors for radiation protection and analysis purposes. When the emission rate of these sources is isotropic, no correction is necessary. However, variations in source encapsulation and in the radioactive material concentration produce differences in its neutron emission rate, relative to the source axis, this effect is called anisotropy. In this study, is describe a procedure for measuring the anisotropy factor of neutron sources performed in the Laboratório de Metrologia de Neutrons (LN) using a Precision Long Counter (PLC) detector. A measurement procedure that takes into account the anisotropy factor of neutron sources contributes to solve some issues, particularly with respect to the high uncertainties associated with neutron dosimetry. Thus, a bibliographical review was carried out based on international standards and technical regulations specific to the area of neutron fields, and were later reproduced in practice by means of the procedure for measuring the anisotropy factor in neutron sources of the LN. The anisotropy factor is determined as a function of the angle of 90° in relation to the cylindrical axis of the source. This angle is more important due to its high use in measurements and also of its higher neutron emission rate if compared with other angles. (author)

Observation of Neutron Skyshine from an Accelerator Based Neutron Source

Energy Technology Data Exchange (ETDEWEB)

Franklyn, C. B. [Radiation Science Department, Necsa, PO Box 582, Pretoria 0001 (South Africa)

2011-12-13

A key feature of neutron based interrogation systems is the need for adequate provision of shielding around the facility. Accelerator facilities adapted for fast neutron generation are not necessarily suitably equipped to ensure complete containment of the vast quantity of neutrons generated, typically >10{sup 11} n{center_dot}s{sup -1}. Simulating the neutron leakage from a facility is not a simple exercise since the energy and directional distribution can only be approximated. Although adequate horizontal, planar shielding provision is made for a neutron generator facility, it is sometimes the case that vertical shielding is minimized, due to structural and economic constraints. It is further justified by assuming the atmosphere above a facility functions as an adequate radiation shield. It has become apparent that multiple neutron scattering within the atmosphere can result in a measurable dose of neutrons reaching ground level some distance from a facility, an effect commonly known as skyshine. This paper describes a neutron detection system developed to monitor neutrons detected several hundred metres from a neutron source due to the effect of skyshine.

Comparison of the thermal neutron scattering treatment in MCNP6 and GEANT4 codes

Science.gov (United States)

Tran, H. N.; Marchix, A.; Letourneau, A.; Darpentigny, J.; Menelle, A.; Ott, F.; Schwindling, J.; Chauvin, N.

2018-06-01

To ensure the reliability of simulation tools, verification and comparison should be made regularly. This paper describes the work performed in order to compare the neutron transport treatment in MCNP6.1 and GEANT4-10.3 in the thermal energy range. This work focuses on the thermal neutron scattering processes for several potential materials which would be involved in the neutron source designs of Compact Accelerator-based Neutrons Sources (CANS), such as beryllium metal, beryllium oxide, polyethylene, graphite, para-hydrogen, light water, heavy water, aluminium and iron. Both thermal scattering law and free gas model, coming from the evaluated data library ENDF/B-VII, were considered. It was observed that the GEANT4.10.03-patch2 version was not able to account properly the coherent elastic process occurring in crystal lattice. This bug is treated in this work and it should be included in the next release of the code. Cross section sampling and integral tests have been performed for both simulation codes showing a fair agreement between the two codes for most of the materials except for iron and aluminium.

Pulsed neutron uranium borehole logging with prompt fission neutrons

International Nuclear Information System (INIS)

Bivens, H.M.; Smith, G.W.; Jensen, D.H.

1976-01-01

The gross count natural gamma log normally used for uranium borehole logging is seriously affected by disequilibrium. Methods for the direct measurement of uranium, such as neutron logging, which are not affected by disequilibrium have been the object of considerable effort in recent years. This paper describes a logging system for uranium which uses a small accelerator to generate pulses of 14 MeV neutrons to detect and assay uranium by the measurement of prompt fission neutrons in the epithermal energy range. After an initial feasibility study, a prototype logging probe was built for field evaluation which began in January 1976. Physical and operational characteristics of the prototype probe, the neutron tube-transformer assembly, and the neutron tube are described. In logging operations, only the epithermal prompt fission neutrons detected between 250 microseconds to 2500 microseconds following the excitation neutron pulse are counted. Comparison of corrected neutron logs with the conventional gross count natural gamma logs and the chemical assays of cores from boreholes are shown. The results obtained with this neutron probe clearly demonstrate its advantages over the gross count natural gamma log, although at this time the accuracy of the neutron log assay is not satisfactory under some conditions. The necessary correction factors for various borehole and formation parameters are being determined and, when applied, should improve the assay accuracy

Neutron reflectometry

International Nuclear Information System (INIS)

Van Well, A.A.

1999-01-01

Neutron research where reflection, refraction, and interference play an essential role is generally referred to as 'neutron optics'. The neutron wavelength, the scattering length density and the magnetic properties of the material determine the critical angle for total reflection. The theoretical background of neutron reflection, experimental methods and the interpretation of reflection data are presented. (K.A.)

Pulsed neutron generator for use with pulsed neutron activation techniques

International Nuclear Information System (INIS)

Rochau, G.E.

1980-01-01

A high-output, transportable, pulsed neutron generator has been developed by Sandia National Laboratories for use with Pulsed Neutron Activation (PNA) techniques. The PNA neutron generator generates > 10 10 14 MeV D-T neutrons in a 1.2 millisecond pulse. Each operation of the unit will produce a nominal total neutron output of 1.2 x 10 10 neutrons. The generator has been designed to be easily repaired and modified. The unit requires no additional equipment for operation or measurement of output

Calibration of a NE213 detector for neutron spectroscopy; Calibracion de un detector de NE213 para espectroscopia de neutrones

Energy Technology Data Exchange (ETDEWEB)

Blazquez Martinez, J; Butragueno Casado, J L

1974-07-01

This work describes the experimental way followed for getting the calibration of a NE213 detector with a beam of neutrons from the J.E.N. 2 MeV Van de Graaff and using at once pulse shape discrimination. Detector has been used for measuring the spectrum of the fast reactor CORAL-1. There is also included an experimental method in order to get with precision where the Compton edge is placed on the electron spectrum. (Author) 9 refs.

Neutron nuclear physics under the neutron science project

Energy Technology Data Exchange (ETDEWEB)

Chiba, Satoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1997-11-01

The concept of fast neutron physics facility in the Neutron Science Research project is described. This facility makes use of an ultra-short proton pulse (width < 1 ns) for fast neutron time-of-flight works. The current design is based on an assumption of the maximum proton current of 100 {mu}A. Available neutron fluence and energy resolution are explained. Some of the research subjects to be performed at this facility are discussed. (author)

Development of highly effective neutron shields and neutron absorbing materials

International Nuclear Information System (INIS)

Tsuda, K.; Matsuda, F.; Taniuchi, H.; Yuhara, T.; Iida, T.

1993-01-01

A wide range of materials, including polymers and hydrogen-occluded alloys that might be usable as the neutron shielding material were examined. And a wide range of materials, including aluminum alloys that might be usable as the neutron-absorbing material were examined. After screening, the candidate material was determined on the basis of evaluation regarding its adaptabilities as a high-performance neutron-shielding and neutron-absorbing material. This candidate material was manufactured for trial, after which material properties tests, neutron-shielding tests and neutron-absorbing tests were carried out on it. The specifications of this material were thus determined. This research has resulted in materials of good performance; a neutron-shielding material based on ethylene propylene rubber and titanium hydride, and a neutron-absorbing material based on aluminum and titanium hydride. (author)

Methods for absorbing neutrons

Science.gov (United States)

Guillen, Donna P [Idaho Falls, ID; Longhurst, Glen R [Idaho Falls, ID; Porter, Douglas L [Idaho Falls, ID; Parry, James R [Idaho Falls, ID

2012-07-24

A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.

Neutron scattering. Lectures

International Nuclear Information System (INIS)

Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner

2013-01-01

The following topics are dealt with: Neutron sources, symmetry of crystals, nanostructures investigated by small-angle neutron scattering, structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic neutron scattering, strongly correlated electrons, polymer dynamics, applications of neutron scattering. (HSI)

Development of Cold Neutron Activation Station at HANARO Cold Neutron Source

International Nuclear Information System (INIS)

Sun, G. M.; Hoang, S. M. T.; Moon, J. H.; Chung, Y. S.; Cho, S. J.; Lee, K. H.; Park, B. G.; Choi, H. D.

2012-01-01

A new cold neutron source at the HANARO Research Reactor had been constructed in the framework of a five-year project, and ended in 2009. It has seven neutron guides, among which five guides were already allocated for a number of neutron scattering instruments. A new two-year project to develop a Cold Neutron Activation Station (CONAS) was carried out at the two neutron guides since May 2010, which was supported by the program of the Ministry of Education, Science and Technology, Korea. Fig. 1 shows the location of CONAS. CONAS is a complex facility including several radioanalytical instruments utilizing neutron capture reaction to analyze elements in a sample. It was designed to include three instruments like a CN-PGAA (Cold Neutron - Prompt Gamma Activation Analysis), a CN-NIPS (Cold Neutron - Neutron Induced Pair Spectrometer), and a CN-NDP (Cold Neutron - Neutron-induced prompt charged particle Depth Profiling). Fig. 2 shows the conceptual configuration of the CONAS concrete bioshield and the instruments. CN-PGAA and CN-NIPS measure the gamma-rays promptly emitted from the sample after neutron capture, whereas CN-NDP is a probe to measure the charged particles emitted from the sample surface after neutron capture. For this, we constructed two cold neutron guides called CG1 and CG2B guides from the CNS

The magnetic diffusion of neutrons; La diffusion magnetique des neutrons

Energy Technology Data Exchange (ETDEWEB)

Koehler, W C [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1959-07-01

The purpose of this report is to examine briefly the diffusion of neutrons by substances, particularly by crystals containing permanent atomic or ionic magnetic moments. In other words we shall deal with ferromagnetic, antiferromagnetic, ferrimagnetic or paramagnetic crystals, but first it is necessary to touch on nuclear diffusion of neutrons. We shall start with the interaction of the neutron with a single diffusion centre; the results will then be applied to the magnetic interactions of the neutron with the satellite electrons of the atom; finally we shall discuss the diffusion of neutrons by crystals. (author) [French] Le but de ce rapport est d'examiner, brievement, la diffusion des neutrons par les substances, et surtout, par des cristaux qui contiennent des moments magnetiques atomiques ou ioniques permanents. C'est-a-dire que nous nous interesserons aux cristaux ferromagnetiques, antiferromagnetiques, ferrimagnetiques ou paramagnetiques; il nous faut cependant rappeler d'abord la diffusion nucleaire des neutrons. Nous commencerons par l'interaction du neutron avec un seul centre diffuseur; puis les resultats seront appliques aux interactions magnetiques du neutron avec les electrons satellites de l'atome; enfin nous discuterons la diffusion des neutrons par les cristaux. (auteur)

Neutron scattering. Lectures

Energy Technology Data Exchange (ETDEWEB)

Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

2010-07-01

The following topics are dealt with: Neutron sources, neutron properties and elastic scattering, correlation functions measured by scattering experiments, symmetry of crystals, applications of neutron scattering, polarized-neutron scattering and polarization analysis, structural analysis, magnetic and lattice excitation studied by inelastic neutron scattering, macromolecules and self-assembly, dynamics of macromolecules, correlated electrons in complex transition-metal oxides, surfaces, interfaces, and thin films investigated by neutron reflectometry, nanomagnetism. (HSI)

Neutron scattering. Lectures

International Nuclear Information System (INIS)

Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner

2010-01-01

The following topics are dealt with: Neutron sources, neutron properties and elastic scattering, correlation functions measured by scattering experiments, symmetry of crystals, applications of neutron scattering, polarized-neutron scattering and polarization analysis, structural analysis, magnetic and lattice excitation studied by inelastic neutron scattering, macromolecules and self-assembly, dynamics of macromolecules, correlated electrons in complex transition-metal oxides, surfaces, interfaces, and thin films investigated by neutron reflectometry, nanomagnetism. (HSI)

Neutron polarization

International Nuclear Information System (INIS)

Firk, F.W.K.

1976-01-01

Some recent experiments involving polarized neutrons are discussed; they demonstrate how polarization studies provide information on fundamental aspects of nuclear structure that cannot be obtained from more traditional neutron studies. Until recently, neutron polarization studies tended to be limited either to very low energies or to restricted regions at higher energies, determined by the kinematics of favorable (p, vector n) and (d, vector n) reactions. With the advent of high intensity pulsed electron and proton accelerators and of beams of vector polarized deuterons, this is no longer the case. One has entered an era in which neutron polarization experiments are now being carried out, in a routine way, throughout the entire range from thermal energies to tens-of-MeV. The significance of neutron polarization studies is illustrated in discussions of a wide variety of experiments that include the measurement of T-invariance in the β-decay of polarized neutrons, a search for the effects of meson exchange currents in the photo-disintegration of the deuteron, the determination of quantum numbers of states in the fission of aligned 235 U and 237 Np induced by polarized neutrons, and the double- and triple-scattering of fast neutrons by light nuclei

Resources of thermal control in vernacular houses of North of Mexico and Peru. A comparative analysis; Recursos de control termico en viviendas vernaculas del Norte de Mexico y Peru. Un analisis comparativo

Energy Technology Data Exchange (ETDEWEB)

Guerrero, Luis F. [Universidad Autonoma Metropolitana Azcapotzalco, Mexico, D.F.(Mexico)

2000-07-01

ponencia se presentan los resultados de un analisis comparativo realizado entre viviendas prehispanicas y vernaculas de los alrededores de la ciudad de Trujillo, Peru y de Casas Grandes en Chihuahua, Mexico, con la finalidad de identificar las caracteristicas formales, funcionales y materiales que permitieron su adaptacion termica a medios geograficos con climas hostiles, resultado de su localizacion en zonas deserticas. Sin que haya existido contacto alguno entre las culturas historicas y vernaculas que se desarrollaron desde hace casi dos mil anos en el Valle de Moche y el Valle de Casas Grandes, se han generado una serie de respuestas arquitectonicas con notables coincidencias en su eficacia para integrarse a las extremosas condiciones climaticas imperantes. Entre estas respuestas es posible destacar la utilizacion de la tierra como material de construccion, la masividad de las estructuras, orientacion geografica, pendientes de techos, dimensiones de sus locales, formas de agrupacion, tipos de ventanas, espacios abiertos, parasoles, pergolas y celosias, entre otros recursos de diseno. Sin embargo, con el paso del tiempo una parte importante de los conocimientos que fundamentaban estas formas de adaptacion al medio fueron perdiendose y se transformo la arquitectura para dar pie a una tradicion vernacula cuyas caracteristicas han resultado ser cada vez menos eficientes. Lo mas grave de esta tendencia es que en anos recientes, a consecuencia de la incorporacion de sistemas constructivos ajenos, la arquitectura local ha ido degenerando hasta perder casi totalmente los rasgos que apoyaban su integracion al medio circundante, transformandose en espacios con un confort termico nulo. El analisis no solo permite valorar los elementos arquitectonicos identificados para promover su conservacion como testimonio historico, sino fundamentalmente como fuente para el diseno de soluciones habitacionales que en el presente y el futuro recuperen la sabiduria ancestral.

MINARET: Towards a time-dependent neutron transport parallel solver

International Nuclear Information System (INIS)

Baudron, A.M.; Lautard, J.J.; Maday, Y.; Mula, O.

2013-01-01

We present the newly developed time-dependent 3D multigroup discrete ordinates neutron transport solver that has recently been implemented in the MINARET code. The solver is the support for a study about computing acceleration techniques that involve parallel architectures. In this work, we will focus on the parallelization of two of the variables involved in our equation: the angular directions and the time. This last variable has been parallelized by a (time) domain decomposition method called the para-real in time algorithm. (authors)

Differences between cross-section libraries for neutron dosimetry; Diferencas entre bibliotecas de secoes de choque para dosimetria de neutrons

Energy Technology Data Exchange (ETDEWEB)

Tardelli, T.C.; Stecher, L.C.; Coelho, T.S.; Castro, V.A. De; Cavalieri, T.A.; Menzel, F.; Giarola, R.S.; Domingos, D.B.; Yoriyaz, H., E-mail: tiago.tardelli@gmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Engenharia Nuclear

2013-08-15

Absorbed dose calculations depend on a consistent set of nuclear data used in simulations in computer codes. Nuclear data are stored in libraries, however, the information available about the differences in dose caused by different libraries are rare. The libraries are processed by a computer system to be able to be used by a radiation transport code. One of the systems capable of processing nuclear data is the NJOY system. The objective of this study is to evaluate the nuclear data libraries for neutrons available in the literature, and to quantify the differences in absorbed dose obtained using the libraries JENDL 4.0, JEFF 3.3.1 and ENDF/B.VII. The absorbed dose calculation was performed on a simple geometric model, as spheres, and in anthropomorphic model of the human body based on the ICRP-110 for neutron transport simulation using the MCNP5 code. The results were compared with literature data. The results obtained with cross sections from the libraries JEFF and ENDF/B.VII have shown to be identical in most cases, except for one case where the difference has exceeded 10%. The results obtained with JENDL library has shown to be considerably different in most cases comparing to other two libraries. Some differences were over 200%. The dose calculations showed differences between the libraries, which is justified by differences in the cross sections. It has been observed that the cross sections values of certain nuclides assume quite different values in different libraries. These differences in turn cause considerable differences in dose calculations. (author)

Neutron imaging integrated circuit and method for detecting neutrons

Science.gov (United States)

Nagarkar, Vivek V.; More, Mitali J.

2017-12-05

The present disclosure provides a neutron imaging detector and a method for detecting neutrons. In one example, a method includes providing a neutron imaging detector including plurality of memory cells and a conversion layer on the memory cells, setting one or more of the memory cells to a first charge state, positioning the neutron imaging detector in a neutron environment for a predetermined time period, and reading a state change at one of the memory cells, and measuring a charge state change at one of the plurality of memory cells from the first charge state to a second charge state less than the first charge state, where the charge state change indicates detection of neutrons at said one of the memory cells.

Neutron reflector design with Californium 252 neutron for Boron neutron chapter therapy facility using MCNP5 simulation method

International Nuclear Information System (INIS)

Muhammad Fakhrurreza; Kusminanto; Y Sardjono

2014-01-01

In this research has made a reflector design to provide beams of Neutron for BNCT with Californium-252 radioactive source. This collimator is useful to obtain optimum epithermal neutron flux with the smallest impurity radiation (thermal neutron, fast neutron, and gamma). The design process is done using Monte Carlo N-Particle simulation version 5 (MCNP5) code to calculate the neutron flux tally form. The chosen reflector design is the reflectors which use material such as BeO ceramic with 13 cm thick. Moderator use sulfur material with the slope angle of the cone is 30°. From the calculation result, it is obtained that Reflector with 1 gram Californium-252 source can produce a neutron output thermal which has thermal neutron specification 2.23189 x 10 9 n/s.cm 2 , epithermal neutron 3.51548 x 10 9 n/s.cm 2 , and fast neutron 4.82241 x 10 9 n/s.cm 2 From the result, it needs additional collimator because the BNCT requirement. (author)

Neutron spectometers

International Nuclear Information System (INIS)

Poortmans, F.

1977-01-01

Experimental work in the field of low-energy neutron physics can be subdivided into two classes: 1)Study of the decay process of the compound-nucleus state as for example the study of the capture gamma rays and of the neutron induced fission process; 2)Study of the reaction mechanism, mainly by measuring the reaction cross-sections and resonance parameters. These neutron cross-sections and resonance parameters are also important data required for many technological applications especially for reactor development programmes. In general, the second class of experiments impose other requirements on the neutron spectrometer than the first class. In most cases, a better neutron energy resolution and a broader neutron energy range are required for the study of the reaction mechanism than for the study of various aspects of the decay process. (author)

Neutron scattering. Lectures

International Nuclear Information System (INIS)

Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner

2012-01-01

The following topics are dealt with: Neutron scattering in contemporary research, neutron sources, symmetry of crystals, diffraction, nanostructures investigated by small-angle neutron scattering, the structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic scattering, strongly correlated electrons, dynamics of macromolecules, applications of neutron scattering. (HSI)

Aerial Neutron Detection: Neutron Signatures for Nonproliferation and Emergency Response Applications

Energy Technology Data Exchange (ETDEWEB)

Maurer, Richard J.; Stampahar, Thomas G.; Smith, Ethan X.; Mukhopadhyay, Sanjoy; Wolff, Ronald S.; Rourke, Timothy J.; LeDonne, Jeffrey P.; Avaro, Emanuele; Butler, D. Andre; Borders, Kevin L.; Stampahar, Jezabel; Schuck, William H.; Selfridge, Thomas L.; McKissack, Thomas M.; Duncan, William W.; Hendricks, Thane J.

2012-10-17

From 2007 to the present, the Remote Sensing Laboratory has been conducting a series of studies designed to expand our fundamental understanding of aerial neutron detection with the goal of designing an enhanced sensitivity detection system for long range neutron detection. Over 35 hours of aerial measurements in a helicopter were conducted for a variety of neutron emitters such as neutron point sources, a commercial nuclear power reactor, nuclear reactor spent fuel in dry cask storage, depleted uranium hexafluoride and depleted uranium metal. The goals of the project were to increase the detection sensitivity of our instruments such that a 5.4 × 104 neutron/second source could be detected at 100 feet above ground level at a speed of 70 knots and to enhance the long-range detection sensitivity for larger neutron sources, i.e., detection ranges above 1000 feet. In order to increase the sensitivity of aerial neutron detection instruments, it is important to understand the dynamics of the neutron background as a function of altitude. For aerial neutron detection, studies have shown that the neutron background primarily originates from above the aircraft, being produced in the upper atmosphere by galactic cosmic-ray interactions with air molecules. These interactions produce energetic neutrons and charged particles that cascade to the earth’s surface, producing additional neutrons in secondary collisions. Hence, the neutron background increases as a function of altitude which is an impediment to long-range neutron detection. In order to increase the sensitivity for long range detection, it is necessary to maintain a low neutron background as a function of altitude. Initial investigations show the variation in the neutron background can be decreased with the application of a cosmic-ray shield. The results of the studies along with a representative data set are presented.

Synovectomy by Neutron capture; Sinovectomia por captura de neutrones

Energy Technology Data Exchange (ETDEWEB)

Vega C, H.R.; Torres M, C. [Centro Regional de Estudios Nucleares, Universidad Autonoma de Zacatecas, C. Cipres 10, Fracc. La Penuela, 98000 Zacatecas (Mexico)

1998-12-31

The Synovectomy by Neutron capture has as purpose the treatment of the rheumatoid arthritis, illness which at present does not have a definitive curing. This therapy requires a neutron source for irradiating the articulation affected. The energy spectra and the intensity of these neutrons are fundamental since these neutrons induce nuclear reactions of capture with Boron-10 inside the articulation and the freely energy of these reactions is transferred at the productive tissue of synovial liquid, annihilating it. In this work it is presented the neutron spectra results obtained with moderator packings of spherical geometry which contains in its center a Pu{sup 239} Be source. The calculations were realized through Monte Carlo method. The moderators assayed were light water, heavy water base and the both combination of them. The spectra obtained, the average energy, the neutron total number by neutron emitted by source, the thermal neutron percentage and the dose equivalent allow us to suggest that the moderator packing more adequate is what has a light water thickness 0.5 cm (radius 2 cm) and 24.5 cm heavy water (radius 26.5 cm). (Author)

Assessing neutron generator output using neutron activation of silicon

International Nuclear Information System (INIS)

Kehayias, Pauli M.; Kehayias, Joseph J.

2007-01-01

D-T neutron generators are used for elemental composition analysis and medical applications. Often composition is determined by examining elemental ratios in which the knowledge of the neutron flux is unnecessary. However, the absolute value of the neutron flux is required when the generator is used for neutron activation analysis, to study radiation damage to materials, to monitor the operation of the generator, and to measure radiation exposure. We describe a method for absolute neutron output and flux measurements of low output D-T neutron generators using delayed activation of silicon. We irradiated a series of silicon oxide samples with 14.1 MeV neutrons and counted the resulting gamma rays of the 28 Al nucleus with an efficiency-calibrated detector. To minimize the photon self-absorption effects within the samples, we used a zero-thickness extrapolation technique by repeating the measurement with samples of different thicknesses. The neutron flux measured 26 cm away from the tritium target of a Thermo Electron A-325 D-T generator (Thermo Electron Corporation, Colorado Springs, CO) was 6.2 x 10 3 n/s/cm 2 ± 5%, which is consistent with the manufacturer's specifications

Assessing neutron generator output using neutron activation of silicon

Energy Technology Data Exchange (ETDEWEB)

Kehayias, Pauli M. [Body Composition Laboratory, Jean Mayer United States Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111 (United States); Kehayias, Joseph J. [Body Composition Laboratory, Jean Mayer United States Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111 (United States)]. E-mail: joseph.kehayias@tufts.edu

2007-08-15

D-T neutron generators are used for elemental composition analysis and medical applications. Often composition is determined by examining elemental ratios in which the knowledge of the neutron flux is unnecessary. However, the absolute value of the neutron flux is required when the generator is used for neutron activation analysis, to study radiation damage to materials, to monitor the operation of the generator, and to measure radiation exposure. We describe a method for absolute neutron output and flux measurements of low output D-T neutron generators using delayed activation of silicon. We irradiated a series of silicon oxide samples with 14.1 MeV neutrons and counted the resulting gamma rays of the {sup 28}Al nucleus with an efficiency-calibrated detector. To minimize the photon self-absorption effects within the samples, we used a zero-thickness extrapolation technique by repeating the measurement with samples of different thicknesses. The neutron flux measured 26 cm away from the tritium target of a Thermo Electron A-325 D-T generator (Thermo Electron Corporation, Colorado Springs, CO) was 6.2 x 10{sup 3} n/s/cm{sup 2} {+-} 5%, which is consistent with the manufacturer's specifications.

Hyper-thermal neutron irradiation field for neutron capture therapy

International Nuclear Information System (INIS)

Sakurai, Yoshinori; Kobayashi, Tooru; Kanda, Keiji

1994-01-01

The utilization of hyper-thermal neutrons, which have an energy spectrum of a Maxwell distribution higher than the room temperature of 300 K, has been studied in order to improve the thermal neutron flux distribution in a living body for a deep-seated tumor in neutron capture therapy (NCT). Simulation calculations using MCNP-V3 were carried out in order to investigate the characteristics of the hyper-thermal neutron irradiation field. From the results of simulation calculations, the following were confirmed: (i) The irradiation field of the hyper-thermal neutrons is feasible by using some scattering materials with high temperature, such as Be, BeO, C, SiC and ZrH 1.7 . Especially, ZrH 1.7 is thought to be the best material because of good characteristics of up-scattering for thermal neutrons. (ii) The ZrH 1.7 of 1200 K yields the hyper-thermal neutrons of a Maxwell-like distribution at about 2000 K and the treatable depth is about 1.5 cm larger comparing with the irradiation of the thermal neutrons of 300 K. (iii) The contamination by the secondary gamma-rays from the scattering materials can be sufficiently eliminated to the tolerance level for NCT through the bismuth layer, without the larger change of the energy spectrum of hyper-thermal neutrons. ((orig.))

Effects of neutron spectrum and external neutron source on neutron multiplication parameters in accelerator-driven system

International Nuclear Information System (INIS)

Shahbunder, Hesham; Pyeon, Cheol Ho; Misawa, Tsuyoshi; Lim, Jae-Yong; Shiroya, Seiji

2010-01-01

The neutron multiplication parameters: neutron multiplication M, subcritical multiplication factor k s , external source efficiency φ*, play an important role for numerical assessment and reactor power evaluation of an accelerator-driven system (ADS). Those parameters can be evaluated by using the measured reaction rate distribution in the subcritical system. In this study, the experimental verification of this methodology is performed in various ADS cores; with high-energy (100 MeV) proton-tungsten source in hard and soft neutron spectra cores and 14 MeV D-T neutron source in soft spectrum core. The comparison between measured and calculated multiplication parameters reveals a maximum relative difference in the range of 6.6-13.7% that is attributed to the calculation nuclear libraries uncertainty and accuracy for energies higher than 20 MeV and also dependent on the reaction rate distribution position and count rates. The effects of different core neutron spectra and external neutron sources on the neutron multiplication parameters are discussed.

Neutron dosimetry at SLAC: Neutron sources and instrumentation

International Nuclear Information System (INIS)

Liu, J.C.; Jenkins, T.M.; McCall, R.C.; Ipe, N.E.

1991-10-01

This report summarizes in detail the dosimetric characteristics of the five radioisotopic type neutron sources ( 238 PuBe, 252 Cf, 238 PuB, 238 PuF 4 , and 238 PuLi) and the neutron instrumentation (moderated BF 3 detector, Anderson-Braun (AB) detector, AB remmeter, Victoreen 488 Neutron Survey Meter, Beam Shut-Off Ionization Chamber, 12 C plastic scintillator detector, moderated indium foil detector, and moderated and bare TLDs) that are commonly used for neutron dosimetry at the Stanford Linear Accelerator Center (SLAC). 36 refs,. 19 figs

Production of 14 MeV neutrons from D-D neutron generators

International Nuclear Information System (INIS)

Cecil, F.E.; Nieschmidt, E.B.

1986-01-01

The production of 14 MeV neutrons from a D-D neutron generator resulting from tritium buildup from the d(d,p)t reaction in the target is discussed. The effect of the 14 MeV neutrons on fast neutron activation analysis with D-D neutron generators is evaluated. (orig.)

Pulsed neutron generator

International Nuclear Information System (INIS)

Bespalov, D.F.; Bykovskii, Yu.A.; Vergun, I.I.; Kozlovskii, K.I.; Kozyrev, Yu.P.; Leonov, R.K.; Simagin, B.I.; Tsybin, A.S.; Shikanov, A.Ie.

1986-03-01

The paper describes a new device for generating pulsed neutron fields, utilized in nuclear geophysics for carrying out pulsed neutron logging and activation analysis under field conditions. The invention employs a sealed-off neutron tube with a laser ion source which increases neutron yield to the level of 10 neutrons per second or higher. 2 refs., 1 fig

Neutron PSDs for the next generation of spallation neutron sources

CERN Document Server

Eijk, C W

2002-01-01

A review of R and D for neutron PSDs to be used at anticipated new spallation neutron sources: the Time-of-Flight system facility, European Spallation Source, Spallation Neutron Source and Neutron Arena, is presented. The gas-filled detectors, scintillation detectors and hybrid systems are emphasized.

New neutron imaging using pulsed sources. Characteristics of a pulsed neutron source and principle of pulsed neutron imaging

International Nuclear Information System (INIS)

Kiyanagi, Yoshiaki

2012-01-01

Neutron beam is one of important tools to obtain the transmission image of an object. Until now, steady state neutron sources such as reactors are mainly used for this imaging purpose. Recently, it has been demonstrated that pulsed neutron imaging based on accelerator neutron sources can provide a real-space distribution of physical information of materials such as crystallographic structure, element, temperature, hydrogen bound state, magnetic field and so on, by analyzing wavelength dependent transmission spectrum, which information cannot be observed or difficult to obtain with a traditional imaging method using steady state neutrons. Here, characteristics of the pulsed neutron source and principle of the pulsed neutron imaging are explained as a basic concept of the new method. (author)

Neutron guides and scientific neutron equipment at CILAS/GMI

International Nuclear Information System (INIS)

Gautier-Picard, P.

2003-01-01

CILAS company is the world's leading supplier of complete neutron guides systems. The neutron optics with multilayer coatings produced by CILAS have become an international standard for neutron beam transportation in the modern research institutes. During the last 30 years, CILAS designed, produced and installed more than 5000 meters of guides in many European, American and Asian countries. To reinforce its leadership and presence in neutron research, CILAS acquired the company Grenoble Modular Instruments (GMI), a leading company in high precision mechanics, engineering and manufacturing of spectrometers and scientific equipment for neutron and synchrotron research. (author)

Neutron detector

Science.gov (United States)

Stephan, Andrew C [Knoxville, TN; Jardret,; Vincent, D [Powell, TN

2011-04-05

A neutron detector has a volume of neutron moderating material and a plurality of individual neutron sensing elements dispersed at selected locations throughout the moderator, and particularly arranged so that some of the detecting elements are closer to the surface of the moderator assembly and others are more deeply embedded. The arrangement captures some thermalized neutrons that might otherwise be scattered away from a single, centrally located detector element. Different geometrical arrangements may be used while preserving its fundamental characteristics. Different types of neutron sensing elements may be used, which may operate on any of a number of physical principles to perform the function of sensing a neutron, either by a capture or a scattering reaction, and converting that reaction to a detectable signal. High detection efficiency, an ability to acquire spectral information, and directional sensitivity may be obtained.

Development of fast neutron radiography system based on portable neutron generator

Energy Technology Data Exchange (ETDEWEB)

Yi, Chia Jia, E-mail: gei-i-kani@hotmail.com; Nilsuwankosit, Sunchai, E-mail: sunchai.n@chula.ac.th [Department of Nuclear Engineering, Faculty of Engineering, Chulalongkorn University, Phayathai Rd., Patumwan, Bangkok, THAILAND 10330 (Thailand)

2016-01-22

Due to the high installation cost, the safety concern and the immobility of the research reactors, the neutron radiography system based on portable neutron generator is proposed. Since the neutrons generated from a portable neutron generator are mostly the fast neutrons, the system is emphasized on using the fast neutrons for the purpose of conducting the radiography. In order to suppress the influence of X-ray produced by the neutron generator, a combination of a shielding material sandwiched between two identical imaging plates is used. A binary XOR operation is then applied for combining the information from the imaging plates. The raw images obtained confirm that the X-ray really has a large effect and that XOR operation can help enhance the effect of the neutrons.

Calibration of area monitors for neutrons used in clinical linear accelerators; Calibracao de monitores de area para neutrons usados em aceleradores lineares clinicos

Energy Technology Data Exchange (ETDEWEB)

Salgado, Ana Paula; Pereira, Walsan Wagner; Patrao, Karla C. de Souza; Fonseca, Evaldo S. da, E-mail: asalgado@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Batista, Delano V.S. [Instituto Nacional do Cancer (INCa), Rio de Janeiro, RJ (Brazil)

2009-07-01

This work demonstrates the complexity and the necessary cares for the realization of measurements of neutron fields in rooms for radiotherapy treatment containing clinical accelerators. The acquaintance of the technical characteristics of the monitors and the periodic calibration are actions and fundamental procedures to guarantee traceability and the reliability of measurements

Neutron dosimetry at SLAC: Neutron sources and instrumentation

Energy Technology Data Exchange (ETDEWEB)

Liu, J.C.; Jenkins, T.M.; McCall, R.C.; Ipe, N.E.

1991-10-01

This report summarizes in detail the dosimetric characteristics of the five radioisotopic type neutron sources ({sup 238}PuBe, {sup 252}Cf, {sup 238}PuB, {sup 238}PuF{sub 4}, and {sup 238}PuLi) and the neutron instrumentation (moderated BF{sub 3} detector, Anderson-Braun (AB) detector, AB remmeter, Victoreen 488 Neutron Survey Meter, Beam Shut-Off Ionization Chamber, {sup 12}C plastic scintillator detector, moderated indium foil detector, and moderated and bare TLDs) that are commonly used for neutron dosimetry at the Stanford Linear Accelerator Center (SLAC). 36 refs,. 19 figs.

Directional epithermal neutron detector

International Nuclear Information System (INIS)

Givens, W.W.; Mills, W.R. Jr.

1986-01-01

A borehole tool for epithermal neutron die-away logging of subterranean formations surrounding a borehole is described which consists of: (a) a pulsed source of fast neutrons for irradiating the formations surrounding a borehole, (b) at least one neutron counter for counting epithermal neutrons returning to the borehole from the irradiated formations, (c) a neutron moderating material, (d) an outer thermal neutron shield providing a housing for the counter and the moderating material, (e) an inner thermal neutron shield dividing the housing so as to provide a first compartment bounded by the inner thermal neutron shield and a first portion of the outer thermal neutron shield and a second compartment bounded by the inner thermal neutron shield and a second portion of the outer thermal neutron shield, the counter being positioned within the first compartment and the moderating material being positioned within the second compartment, and (f) means for positioning the borehole tool against one side of the borehole wall and azimuthally orienting the borehole tool such that the first chamber is in juxtaposition with the borehole wall, the formation epithermal neutrons penetrating into the first chamber through the first portion of the outer thermal neutron shield are detected by the neutron counter for die-away measurement, thereby maximizing the directional sensitivty of the neutron counter to formation epithermal neutrons, the borehole fluid epithermal neutrons penetrating into the second chamber through the second chamber through the second portion of the outer thermal neutron shield are largely slowed down and lowered in energy by the moderating material and absorbed by the inner thermal neutron shield before penetrating into the first chamber, thereby minimizing the directional sensitivity of the neutron counter to borehole fluid epithermal neutrons

Neutron Optics: Towards Applications for Hot Neutrons

International Nuclear Information System (INIS)

Schanzer, C; Schneider, M; Böni, P

2016-01-01

Supermirrors with large critical angles of reflection, i.e. large index m are an essential ingredient to transport, focus and polarise neutrons over a wide range of energy. Here we summarise the recent developments of supermirror with very large critical angles of reflection and high reflectivity that were conducted at SwissNeutronics as well as their implementation in devices. Approaching critical angles m = 8 times the critical angle of natural nickel makes new applications possible and extends the use of reflection optics towards the regime of hot and epithermal neutrons. Based on comparisons of simulations with experiment we demonstrate future possibilities of applications of large-m supermirrors towards devices for neutrons with short wavelength. (paper)

Neutron transportation simulator

International Nuclear Information System (INIS)

Uenohara, Yuzo.

1995-01-01

In the present invention, problems in an existent parallelized monte carlo method is solved, and behaviors of neutrons in a large scaled system are accurately simulated at a high speed. Namely, a neutron transportation simulator according to the monte carlo method simulates movement of each of neutrons by using a parallel computer. In this case, the system to be processed is divided based on a space region and an energy region to which neutrons belong. Simulation of neutrons in the divided regions is allotted to each of performing devices of the parallel computer. Tarry data and nuclear data of the neutrons in each of the regions are memorized dispersedly to memories of each of the performing devices. A transmission means for simulating the behaviors of the neutrons in the region by each of the performing devices, as well as transmitting the information of the neutrons, when the neutrons are moved to other region, to the performing device in a transported portion are disposed to each of the performing devices. With such procedures, simulation for the neutrons in the allotted region can be conducted with small capacity of memories. (I.S.)

Neutronics of the IFMIF neutron source: development and analysis

International Nuclear Information System (INIS)

Wilson, P.P.H.

1999-01-01

The accurate analysis of this system required the development of a code system and methodology capable of modelling the various physical processes. A generic code system for the neutronics analysis of neutron sources has been created by loosely integrating existing components with new developments: the data processing code NJOY, the Monte Carlo neutron transport code MCNP, and the activation code ALARA were supplemented by a damage data processing program, damChar, and integrated with a number of flexible and extensible modules for the Perl scripting language. Specific advances were required to apply this code system to IFMIF. Based on the ENDF-6 data format requirements of this system, new data evaluations have been implemented for neutron transport and activation. Extensive analysis of the Li(d, xn) reaction has led to a new MCNP source function module, M c DeLi, based on physical reaction models and capable of accurate and flexible modelling of the IFMIF neutron source term. In depth analyses of the neutron flux spectra and spatial distribution throughout the high flux test region permitted a basic validation of the tools and data. The understanding of the features of the neutron flux provided a foundation for the analyses of the other neutron responses. (orig./DGE) [de

Neutron spectra and dosimetric features of isotopic neutron sources: a review

International Nuclear Information System (INIS)

Vega C, H. R.; Martinez O, S. A.

2015-10-01

A convenient way to produce neutrons is the isotopic neutron source, where the production is through (α, n), (γ, n), and spontaneous fission reactions. Isotopic neutron sources are small, easy to handle, and have a relative low cost. On the other hand the neutron yield is small and mostly of them produces neutrons with a wide energy distribution. In this work, a review is carried out about the the main features of 24 NaBe, 24 NaD 2 O, 116 InBe, 140 LaBe, 238 PuLi, 239 PuBe, 241 AmB, 241 AmBe, 241 AmF, 241 AmLi, 242 CmBe, 210 PoBe, 226 RaBe, 252 Cf and 252 Cf/D 2 O isotopic neutron source. Also, using Monte Carlo methods, the neutron spectra in 31 energy groups, the neutron mean energy; the Ambient dose equivalent, the Personal dose equivalent and the Effective dose were calculated for these isotopic neutron sources. (Author)

A neutron detector for measurement of total neutron production cross sections

International Nuclear Information System (INIS)

Sekharan, K.K.; Laumer, H.; Kern, B.D.; Gabbard, F.

1976-01-01

A neutron detector has been constructed and calibrated for the accurate measurement of total neutron production cross sections. The detector consists of a polyethylene sphere of 60 cm diameter in which eight 10 BF 3 counters have been installed radially. The relative efficiency of this detector has been determined for average neutron energies from 30 keV to 1.5 MeV by counting neutrons from 7 Li(p, n) 7 Be. By adjusting the radial positions of the BF 3 counters in the polyethylene sphere the efficiency for neutron detection was made nearly constant for this energy range. Measurement of absolute efficiency for the same neutron energy range has been done by counting the neutrons from 51 V(p, n) 51 Cr and 57 Fe(p, n) 57 Co reactions and determining the absolute number of residual nuclei produced during the measurement of neutron yield. Details of absolute efficiency measurements and the use of the detector for determination of neutron production cross sections are given. (Auth.)

Fusion neutronics

CERN Document Server

Wu, Yican

2017-01-01

This book provides a systematic and comprehensive introduction to fusion neutronics, covering all key topics from the fundamental theories and methodologies, as well as a wide range of fusion system designs and experiments. It is the first-ever book focusing on the subject of fusion neutronics research. Compared with other nuclear devices such as fission reactors and accelerators, fusion systems are normally characterized by their complex geometry and nuclear physics, which entail new challenges for neutronics such as complicated modeling, deep penetration, low simulation efficiency, multi-physics coupling, etc. The book focuses on the neutronics characteristics of fusion systems and introduces a series of theories and methodologies that were developed to address the challenges of fusion neutronics, and which have since been widely applied all over the world. Further, it introduces readers to neutronics design’s unique principles and procedures, experimental methodologies and technologies for fusion systems...

Neutron-induced peaks in Ge detectors from evaporation neutrons

International Nuclear Information System (INIS)

Gete, E.; Measday, D.F.; Moftah, B.A.; Saliba, M.A.; Stocki, T.J.

1997-01-01

We have studied the peak shapes at 596 and 691 keV resulting from fast neutron interactions inside germanium detectors. We have used neutrons from a 252 Cf source, as well as from the 28 Si(μ - , nν), and 209 Bi(π - , xn) reactions to compare the peaks and to check for a dependence of peak shape on the incoming neutron energy. In our investigation, no difference between these three measurements has been observed. In a comparison of these peak shapes with other studies, we found similar results to ours except for those measurements using monoenergetic neutrons in which a significant variation with neutron energy has been observed. (orig.)

Development of high flux thermal neutron generator for neutron activation analysis

Energy Technology Data Exchange (ETDEWEB)

Vainionpaa, Jaakko H., E-mail: hannes@adelphitech.com [Adelphi Technology, 2003 E Bayshore Rd, Redwood City, CA 94063 (United States); Chen, Allan X.; Piestrup, Melvin A.; Gary, Charles K. [Adelphi Technology, 2003 E Bayshore Rd, Redwood City, CA 94063 (United States); Jones, Glenn [G& J Jones Enterprice, 7486 Brighton Ct, Dublin, CA 94568 (United States); Pantell, Richard H. [Department of Electrical Engineering, Stanford University, Stanford, CA (United States)

2015-05-01

The new model DD110MB neutron generator from Adelphi Technology produces thermal (<0.5 eV) neutron flux that is normally achieved in a nuclear reactor or larger accelerator based systems. Thermal neutron fluxes of 3–5 · 10{sup 7} n/cm{sup 2}/s are measured. This flux is achieved using four ion beams arranged concentrically around a target chamber containing a compact moderator with a central sample cylinder. Fast neutron yield of ∼2 · 10{sup 10} n/s is created at the titanium surface of the target chamber. The thickness and material of the moderator is selected to maximize the thermal neutron flux at the center. The 2.5 MeV neutrons are quickly thermalized to energies below 0.5 eV and concentrated at the sample cylinder. The maximum flux of thermal neutrons at the target is achieved when approximately half of the neutrons at the sample area are thermalized. In this paper we present simulation results used to characterize performance of the neutron generator. The neutron flux can be used for neutron activation analysis (NAA) prompt gamma neutron activation analysis (PGNAA) for determining the concentrations of elements in many materials. Another envisioned use of the generator is production of radioactive isotopes. DD110MB is small enough for modest-sized laboratories and universities. Compared to nuclear reactors the DD110MB produces comparable thermal flux but provides reduced administrative and safety requirements and it can be run in pulsed mode, which is beneficial in many neutron activation techniques.

Fast neutron activation analysis by means of low voltage neutron generator

Directory of Open Access Journals (Sweden)

M.E. Medhat

Full Text Available A description of D-T neutron generator (NG is presented. This machine can be used for fast neutron activation analysis applied to determine some selected elements, especially light elements, in different materials. Procedure of neutron flux determination and efficiency calculation is described. Examples of testing some Egyptian natural cosmetics are given. Keywords: Neutron generator, Fast neutron activation analysis, Elemental analysis

Research of accelerator-based neutron source for boron neutron capture therapy

International Nuclear Information System (INIS)

Li Changkai; Ma Yingjie; Tang Xiaobin; Xie Qin; Geng Changran; Chen Da

2013-01-01

Background: 7 Li (p, n) reaction of high neutron yield and low threshold energy has become one of the most important neutron generating reactions for Accelerator-based Boron Neutron Capture Therapy (BNCT). Purpose Focuses on neutron yield and spectrum characteristics of this kind of neutron generating reaction which serves as an accelerator-based neutron source and moderates the high energy neutron beams to meet BNCT requirements. Methods: The yield and energy spectrum of neutrons generated by accelerator-based 7 Li(p, n) reaction with incident proton energy from 1.9 MeV to 3.0 MeV are researched using the Monte Carlo code-MCNPX2.5.0. And the energy and angular distribution of differential neutron yield by 2.5-MeV incident proton are also given in this part. In the following part, the character of epithermal neutron beam generated by 2.5-MeV incident protons is moderated by a new-designed moderator. Results: Energy spectra of neutrons generated by accelerator-based 7 Li(p, n) reaction with incident proton energy from 1.9 MeV to 3.0 MeV are got through the simulation and calculation. The best moderator thickness is got through comparison. Conclusions: Neutron beam produced by accelerator-based 7 Li(p, n) reaction, with the bombarding beam of 10 mA and the energy of 2.5 MeV, can meet the requirement of BNCT well after being moderated. (authors)

A polarizing neutron periscope for neutron imaging

International Nuclear Information System (INIS)

Schulz, Michael; Boeni, Peter; Calzada, Elbio; Muehlbauer, Martin; Neubauer, Andreas; Schillinger, Burkhard

2009-01-01

Optical neutron polarizers like guides or benders destroy the collimation of a neutron beam due to multiple reflections or scattering. This makes them unsuitable for their use in polarized neutron radiography, because the beam collimation is essential to obtain high spatial resolution. We have developed a neutron polarizer based on the principle of an optical periscope with a zigzag double reflection on two parallel high-m supermirror polarizers. If the supermirrors are perfectly parallel and flat, the beam collimation is left unchanged by such a device. A first proof of concept version of this type of polarizer was built and tested. We expect to achieve a beam polarization of up to 99% with an improved version yet to be built.

Neutron detector

International Nuclear Information System (INIS)

Endo, Hiroshi.

1993-01-01

The device of the present invention detects neutrons in a reactor container under a high temperature and reduces the noise level in an FBR type reactor. That is, the detection section comprises a high heat resistant vessel containing a scintillator therein for detecting neutrons. Neutron signals sent from the detection section are inputted to a neutron measuring section by way of a signal transmission section. The detection section is disposed at the inside of the reactor container. Further, the signal transmission section is connected optically to the detection section. With such a constitution, since the detection section comprising the high temperature resistant vessel is disposed at the inside of the reactor container, neutron fluxes can be detected and measured at high sensitivity even under a high temperature circumstance. Since the signal transmission section is optically connected to the detection section, influence of radiation rays upon transmission of the neutron detection signals can be reduced. Accordingly, the noise level can be kept low. (I.S.)

Very slow neutrons

International Nuclear Information System (INIS)

Frank, A.

1983-01-01

The history is briefly presented of the research so far of very slow neutrons and their basic properties are explained. The methods are described of obtaining very slow neutrons and the problems of their preservation are discussed. The existence of very slow neutrons makes it possible to perform experiments which may deepen the knowledge of the fundamental properties of neutrons. Their wavelength approximates that of visible radiation. The possibilities and use are discussed of neutron optical systems (neutron microscope) which could be an effective instrument for the study of the detailed arrangement, especially of organic substances. (B.S.)

Neutron in biology

International Nuclear Information System (INIS)

Niimura, Nobuo

1997-01-01

Neutron in biology can provide an experimental method of directly locating relationship of proteins and DNA. However, there are relatively few experimental study of such objects since it takes a lot of time to collect a sufficient number of Bragg reflections and inelastic spectra due to the low flux of neutron illuminating the sample. Since a next generation neutron source of JAERI will be 5MW spallation neutron source and its effective neutron flux will be 10 2 to 10 3 times higher than the one of JRR-3M, neutron in biology will open a completely new world for structural biology. (author)

Experiment of Neutron Generation by Using Prototype D-D Neutron Generator

International Nuclear Information System (INIS)

Kim, In Jung; Kim, Suk Kwon; Park, Chang Su; Jung, Nam Suk; Jung, Hwa Dong; Park, Ji Young; Hwang, Yong Seok; Choi, H.D.

2005-01-01

Experiment of neutron generation was performed by using a prototype D-D neutron generator. The characteristics of D-D neutron generation in drive-in target was studied. The increment of neutron yield by increasing ion beam energy was investigated, too

Analysis of the neutron generation from a D-Li neutron source

International Nuclear Information System (INIS)

Gomes, I.

1994-02-01

The study of the neutron generation from the D-Li reaction is an important issue to define the optimum combination of the intervening parameters during the design phase of a D-Li neutron source irradiation facility. The major players in defining the neutron yield from the D-Li reaction are the deuteron incident energy and the beam current, provided that the lithium target is thick enough to stop all incident deuterons. The incident deuteron energy also plays a role on the angular distribution of the generated neutrons, on the energy distribution of the generated neutrons, and on the maximum possible energy of the neutrons. The D-Li reaction produces neutrons with energies ranging from eV's to several MeV's. The angular distribution of these neutrons is dependent on the energy of both, incident deuterons and generated neutrons. The deuterons lose energy interacting with the lithium target material in such a way that the energy of the deuterons inside the lithium target varies from the incident deuteron energy to essentially zero. The first part of this study focuses in analyzing the neutron generation rate from the D-Li reaction as a function of the intervening parameters, in defining the source term, in terms of the energy and angular distributions of the generated neutrons, and finally in providing some insights of the impact of varying input parameters on the generation rate and correlated distributions. In the second part an analytical description of the Monte Carlo sampling procedure of the neutron from the D-Li reaction is provided with the aim at further Monte Carlo transport of the D-Li neutrons

Angular distributions of fast neutrons scattered by Al, Si, P, S and Zn; Distributions angulaires des neutrons rapides diffuses par Al, Si, P, S et Zn; Usloviya raspredeleniya bystrykh nejtronov, rasseyannykh alyuminiem, kremniem, fosforom i tsinkom; Distribuciones angulares de neutrones rapidos dispersados por Al, Si, P, S y Zn

Energy Technology Data Exchange (ETDEWEB)

Tstjkaija, K; Tanaka, S; Maeuyama, M; Tomita, Y [Japan Atomic Energy Research Institute, Tokai-Mtjea (Japan)

1962-03-15

Differential scattering cross-sections of Al, Si, P, S and Zn for fast neutrons have been measured in an energy range of 3.4 to 4.6 MeV by using the time-of-flight method. Angular distributions of the inelastically scattered neutrons are nearly isotropic in all cases. These results are discussed on the basis of the Hauser-Feshbach theory. (author) [French] Les sections efficaces differentielles de diffusion de Al, Si, P, S et Zn pour des neutrons rapides ont ete mesurees dans la gamme d'energies de 3,4 a 4,6 MeV, en employant la methode du temps de vol. Les distributions angulaires des neutrons diffuses inelastiquement sont presque isotropes dans tous les cas. Les auteurs analysent ces resultats en se fondant sur la theorie de Hauser-Feshbach. (author) [Spanish] Los autores han medido por el metodo del tiempo de vuelo las secciones eficaces diferenciales de dispersion del Al, Si, P, S y Zn para neutrones rapidos de energia comprendida entre 3,4 y 4,6 MeV. Las distribuciones angulares de los neutrones dispersados inelasticamente son casi isotropicas en todos los casos. Los autores analizan los resultados obtenidos basandose en la teoria de Hauser-Feshbach . (author) [Russian] Differentsial'no e sechenie rasseyaniya alyuminiya, kremniya, fosfora, sery i tsinka dlya bystrykh nejtronov izmereno v diapazone ehnergii ot 3,4 do 4,6 Megaehlektronvol't ispol'zovanie m metoda vremeni proleta. Uglovye raspredeleniya neuprugo rasseyannykh nejtronov yavlyayutsya pochti vo vsekh sluchayakh izotropnymi. Jeti rezul'taty obsuzhdayutsya na osnove teorii Hauzera-Feshbakha. (author)

Regularities in the Changes of Absorber Material Properties as a Function of Absorber Concentration; Regularite des Variations des Proprietes des Substances Absorbantes en Fonction de la Concentration de l'Absorbant; Zakonomernosti izmeneniya svojstv poglashchayushchikh materialov v zavisimosti ot kontsentratsii poglotitelya; Leyes de Variacion de las Propiedades de los Materiales Absorbentes en Funcion de la Concentracion del Absorbente

Energy Technology Data Exchange (ETDEWEB)

Portnoj, K. I.

1964-06-15

pouvoir absorbant, en tant que fonction de la concentration de l'absorbant, varie d'apres une courbe caracteristique d'un phenomene de saturation et depend du spectre de neutrons. L'auteur formule une hypothese sur l'obtention du pouvoir absorbant maximum grace a la combinaison de plusieurs absorbants. Cette hypothese a ete largement confirmee par des experiences effectuees, dans des reacteurs a neutrons thermiques et intermediaires, sur de nombreuses combinaisons d'absorbants metalliques ou non. (author) [Spanish] En esta memoria se exponen las leyes que rigen las variaciones de las propiedades mecanicas y termofisicas y del poder de absorcion, en funcion de la concentracion del absorbente, en aleaciones destinadas a los reactores de neutrones termicos e intermedios. La conductividad y el coeficiente de dilatacion termica de las aleaciones absorbentes a base de boro y oxidos de las tierras raras se reducen al aumentar dicha concentracion. En el caso de las aleaciones con oxidos de las tierras raras, la variacion del coeficiente de dilatacion es lineal, mientras que para las alea,- ciones de boro esa caracteristica aditiva se altera. Ello se debe a que a temperaturas elevadas se forman fases de boruro con distintas redes cristalinas. En cuanto al poder absorbente, varia segun una curva de saturacion y depende tambien del espectro neutronico. El autor propone una hipotesis para explicar la aparicion de un maximo en la curva del poder absorbente, que atribuye a un fenomeno de interaleacion de los absorbentes. Esta hipotesis ha sido confirmada ampliamente por los resultados de experimentos efectuados con muchos sistemas absorbentes metalicos y no metalicos, de variada composicion, en reactores de neutrones termicos e intermedios. (author) [Russian] Doklad stavit cel'ju izlozhit' poluchennye zakonomernosti izmenenija mehanicheskih i teplofizicheskih svojstv, a takzhe pogloshhajushhej sposobnosti v zavisimosti ot koncentracii poglotitelej v sp lav a h , prednaznachennyh dlja

Neutron techniques

International Nuclear Information System (INIS)

Charlton, J.S.

1986-01-01

The way in which neutrons interact with matter such as slowing-down, diffusion, neutron absorption and moderation are described. The use of neutron techniques in industry, in moisture gages, level and interface measurements, the detection of blockages, boron analysis in ore feedstock and industrial radiography are discussed. (author)

Neutron scattering. Lectures

Energy Technology Data Exchange (ETDEWEB)

Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner [eds.

2010-07-01

The following topics are dealt with: Neutron sources, symmetry of crystals, diffraction, nanostructures investigated by small-angle neutron scattering, the structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic scattering, strongly correlated electrons, dynamics of macromolecules, applications of neutron scattering. (HSI)

Neutron scattering. Lectures

International Nuclear Information System (INIS)

Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner

2010-01-01

The following topics are dealt with: Neutron sources, symmetry of crystals, diffraction, nanostructures investigated by small-angle neutron scattering, the structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic scattering, strongly correlated electrons, dynamics of macromolecules, applications of neutron scattering. (HSI)

Neutron spectra and dosimetric features of isotopic neutron sources: a review

Energy Technology Data Exchange (ETDEWEB)

Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98060 Zacatecas, Zac. (Mexico); Martinez O, S. A., E-mail: fermineutron@yahoo.com [Universidad Pedagogica y Tecnologica de Colombia, Grupo de Fisica Nuclear Aplicada y Simulacion, Av. Central del Norte 39-115, 150003 Tunja, Boyaca (Colombia)

2015-10-15

A convenient way to produce neutrons is the isotopic neutron source, where the production is through (α, n), (γ, n), and spontaneous fission reactions. Isotopic neutron sources are small, easy to handle, and have a relative low cost. On the other hand the neutron yield is small and mostly of them produces neutrons with a wide energy distribution. In this work, a review is carried out about the the main features of {sup 24}NaBe, {sup 24}NaD{sub 2}O, {sup 116}InBe, {sup 140}LaBe, {sup 238}PuLi, {sup 239}PuBe, {sup 241}AmB, {sup 241}AmBe, {sup 241}AmF, {sup 241}AmLi, {sup 242}CmBe, {sup 210}PoBe, {sup 226}RaBe, {sup 252}Cf and {sup 252}Cf/D{sub 2}O isotopic neutron source. Also, using Monte Carlo methods, the neutron spectra in 31 energy groups, the neutron mean energy; the Ambient dose equivalent, the Personal dose equivalent and the Effective dose were calculated for these isotopic neutron sources. (Author)

A neutron detector for measurement of total neutron production cross sections

Energy Technology Data Exchange (ETDEWEB)

Sekharan, K K; Laumer, H; Kern, B D; Gabbard, F [Kentucky Univ., Lexington (USA). Dept. of Physics and Astronomy

1976-03-01

A neutron detector has been constructed and calibrated for the accurate measurement of total neutron production cross sections. The detector consists of a polyethylene sphere of 60 cm diameter in which eight /sup 10/BF/sub 3/ counters have been installed radially. The relative efficiency of this detector has been determined for average neutron energies from 30 keV to 1.5 MeV by counting neutrons from /sup 7/Li(p, n)/sup 7/Be. By adjusting the radial positions of the BF/sub 3/ counters in the polyethylene sphere the efficiency for neutron detection was made nearly constant for this energy range. Measurement of absolute efficiency for the same neutron energy range has been done by counting the neutrons from /sup 51/V(p, n)/sup 51/Cr and /sup 57/Fe(p, n)/sup 57/Co reactions and determining the absolute number of residual nuclei produced during the measurement of neutron yield. Details of absolute efficiency measurements and the use of the detector for determination of neutron production cross sections are given.

Neutron radiography

International Nuclear Information System (INIS)

Alaa eldin, M.T.

2011-01-01

The digital processing of the neutron radiography images gives the possibility for data quantification. In this case an exact relation between the measured neutron attenuation and the real macroscopic attenuation coefficient for every point of the sample is required. The assumption that the attenuation of the neutron beam through the sample is exponential is valid only in an ideal case where a monochromatic beam, non scattering sample and non background contribution are assumed. In the real case these conditions are not fulfilled and in dependence on the sample material we have more or less deviation from the exponential attenuation law. Because of the high scattering cross-sections of hydrogen (σs=80.26 barn) for thermal neutrons, the problem with the scattered neutrons at quantitative radiography investigations of hydrogenous materials (as PE, Oil, H 2 O, etc) is not trivial. For these strong scattering materials the neutron beam attenuation is no longer exponential and a dependence of the macroscopic attenuation coefficient on the material thickness and on the distance between the sample and the detector appears. When quantitative radiography (2 D) or tomography investigations (3 D) are performed, some image correction procedures for a description of the scattering effect are required. This thesis presents a method that can be used to enhance the neutron radiography image for objects with high scattering materials like hydrogen, carbon and other light materials. This method uses the Monte Carlo code, MCNP5, to simulate the neutron radiography process and get the flux distribution for each pixel of the image and determine the scattered neutrons distribution that causes the image blur and then subtract it from the initial image to improve its quality.

A search for solar neutron response in neutron monitor data

International Nuclear Information System (INIS)

Kudela, K.

1990-01-01

The search for an impulsive increase corresponding to a solar neutron response on high-mountain neutron monitors requires control of the stability of the measurement and elimination of other sources of short-time increases of different kinds which are involved in fluctuations of cosmic-ray intensity. For the solar flare of June 3, 1982 the excess of counting rate on the Lomnicky stit neutron monitor is, within a factor or 1.8, equal to that expected from solar neutrons. Superposed epoch analysis of 17 flares with gamma-ray or hard X-ray production gives a slight tendency of an occurring signal in cases of high heliocentric angles, indicating anisotropic production of neutrons on the sun. The low statistical significance of the result indicates that higher temporal resolution, better evaluation of multiplicity, better knowledge of the power spectra of short-term intensity fluctuations on neutron monitors, as well as coordinated measurements of solar gamma-rays and neutrons on satellites, are required. 21 refs

Delayed neutron yield from fast neutron induced fission of 238U

International Nuclear Information System (INIS)

Piksaikin, V.M.; Kazakov, L.E.; Isaev, S.G.; Roshchenko, V.A.; Goverdovski, A.A.; Tertytchnyi, R.G.

2002-01-01

The measurements of the total delayed neutron yield from fast neutron induced fission of 238 U were made. The experimental method based on the periodic irradiation of the fissionable sample by neutrons from a suitable nuclear reaction had been employed. The preliminary results on the energy dependence of the total delayed neutron yield from fission of 238 U are obtained. According to the comparison of experimental data with our prediction based on correlation properties of delayed neutron characteristics, it is concluded that the value of the total delayed neutron yield near the threshold of (n,f) reaction is not a constant. (author)

Neutron flux stabilization in the NG-150 neutron generators

International Nuclear Information System (INIS)

Kuz'min, L.E.; Makarov, S.A.; Pronman, I.M.

1986-01-01

Problem of metal tritium target lifetime increase and neutron flux stabilization in the NG-150 neutron generators is studied. Possibility on neutron flux stabilization using the mass analyzer for low-angle (4 deg and 41 deg) mass separation of a beam in thre components, which fall on a target simultaneously, is confirmed experimentally. Basic generator parameters are: accelerating voltage of 150 kV, total beam current on a target of 1.5 mA, beam current density of 0.3-1.6 mA/cm 2 , beam diameter of 8 mm. The initial neutron flux on the targets of 0.73 mg/cm 2 thick constituted 1.1x10 11 ssup(-1). The neutron flux monitoring was accomplished from recoil proton recording by a plastic scintillator. Flux decrease by more than 5% served as a signel for measuring mass analyzer magnetic field providing beam displacement on a target and restoration of the given flux. The NG-150 generator neutron flux stabilization was attained during 2h

Neutron detection technique

International Nuclear Information System (INIS)

Oblath, N.S.; Poon, A.W.P.

2000-01-01

The Sudbury Neutrino Observatory (SNO) has the ability to measure the total flux of all active flavors of neutrinos using the neutral current reaction, whose signature is a neutron. By comparing the rates of the neutral current reaction to the charged current reaction, which only detects electron neutrinos, one can test the neutrino oscillation hypothesis independent of solar models. It is necessary to understand the neutron detection efficiency of the detector to make use of the neutral current reaction. This report demonstrates a coincidence technique to identify neutrons emitted from the 252 Cf neutron calibration source. The source releases on average four neutrons when a 252 Cf nucleus spontaneously fissions. Each neutron is detected as a separate event when the neutron is captured by a deuteron, releasing a gamma ray of approximately 6.25 MeV. This gamma ray is in turn detected by the photomultiplier tube (PMT) array. By investigating the time and spatial separation between neutron-like events, it is possible to obtain a pure sample of neutrons for calibration study. Preliminary results of the technique applied to two calibration runs are presented

Neutron in biology

Energy Technology Data Exchange (ETDEWEB)

Niimura, Nobuo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1997-11-01

Neutron in biology can provide an experimental method of directly locating relationship of proteins and DNA. However, there are relatively few experimental study of such objects since it takes a lot of time to collect a sufficient number of Bragg reflections and inelastic spectra due to the low flux of neutron illuminating the sample. Since a next generation neutron source of JAERI will be 5MW spallation neutron source and its effective neutron flux will be 10{sup 2} to 10{sup 3} times higher than the one of JRR-3M, neutron in biology will open a completely new world for structural biology. (author)

Reactor neutron dosimetry

International Nuclear Information System (INIS)

Najzer, M.; Pauko, M.; Glumac, B.; Acquah, I.N.; Moskon, F.

1977-01-01

An analysis of requirements and possibilities for experimental neutron spectrum determination during the reactor pressure vessel surveil lance programme is given. Fast neutron spectrum and neutron dose rate were measured in the Fast neutron irradiation facility of our TRIGA reactor. It was shown that the facility can be used for calibration of neutron dosimeters and for irradiation of samples sensitive to neutron radiation. The investigation of the unfolding algorithm ITER was continued. Based on this investigations are two specialized unfolding program packages ITERAD and ITERGS written this year. They are able to unfold data from activation detectors and NaI(T1) gamma spectrometer respectively

New thermal neutron scattering files for ENDF/B-VI release 2

International Nuclear Information System (INIS)

MacFarlane, R.E.

1994-03-01

At thermal neutron energies, the binding of the scattering nucleus in a solid, liquid, or gas affects the cross section and the distribution of secondary neutrons. These effects are described in the thermal sub-library of Version VI of the Evaluated Nuclear Data Files (ENDF/B-VI) using the File 7 format. In the original release of the ENDF/B-VI library, the data in File 7 were obtained by converting the thermal scattering evaluations of ENDF/B-III to the ENDF-6 format. These original evaluations were prepared at General Atomics (GA) in the late sixties, and they suffer from accuracy limitations imposed by the computers of the day. This report describes new evaluations for six of the thermal moderator materials and six new cold moderator materials. The calculations were made with the LEAPR module of NJOY, which uses methods based on the British code LEAP, together with the original GA physics models, to obtain new ENDF files that are accurate over a wider range of energy and momentum transfer than the existing files. The new materials are H in H 2 O, Be metal, Be in BeO, C in graphite, H in ZrH, Zr in ZrH, liquid ortho-hydrogen, liquid para-hydrogen, liquid ortho-deuterium, liquid para-deuterium liquid methane, and solid methane

Characteristics of Fabricated SiC Neutron Detectors for Neutron Flux Monitoring

Energy Technology Data Exchange (ETDEWEB)

Kim, Han Soo; Ha, Jang Ho; Park, Se Hwan; Lee, Kyu Hong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lee, Cheol Ho [Hanyang University, Seoul (Korea, Republic of)

2011-05-15

An SPND (Self-powered Neutron Detector) is commonly used for neutron detection in NPP (Nuclear Power Plant) by virtue of un-reactivity for gamma-rays. But it has a drawback, which is that it cannot detect neutrons in real time due to beta emissions (about > 48 s) after reactions between neutrons and {sup 103}Rh in an SPND. And Generation IV reactors such as MSR (Molten-salt reactor), SFR (Sodium-cooled fast reactor), and GFR (Gas-cooled fast reactor) are designed to compact size and integration type. For GEN IV reactor, neutron monitor also must be compact-sized to apply such reactor easily and much more reliable. The wide band-gap semiconductors such as SiC, AlN, and diamond make them an attractive alternative in applications in harsh environments by virtue of the lower operating voltage, faster charge-collection times compared with gas-filled detectors, and compact size.1) In this study, two PIN-type SiC semiconductor neutron detectors, which are for fast neutron detection by elastic and inelastic scattering SiC atoms and for thermal neutron detection by charged particle emissions of 6LiF reaction, were designed and fabricated for NPP-related applications. Preliminary tests such as I-V and alpha response were performed and neutron responses at ENF in HANARO research reactor were also addressed. The application feasibility of the fabricated SiC neutron detector as an in-core neutron monitor was discussed

Measuring neutron spectra in radiotherapy using the nested neutron spectrometer

Energy Technology Data Exchange (ETDEWEB)

Maglieri, Robert, E-mail: robert.maglieri@mail.mcgill.ca; Evans, Michael; Seuntjens, Jan; Kildea, John [Medical Physics Unit, McGill University, Montreal, Quebec H4A 3J1 (Canada); Licea, Angel [Canadian Nuclear Safety Commission, Ottawa, Ontario K1P 5S9 (Canada)

2015-11-15

Purpose: Out-of-field neutron doses resulting from photonuclear interactions in the head of a linear accelerator pose an iatrogenic risk to patients and an occupational risk to personnel during radiotherapy. To quantify neutron production, in-room measurements have traditionally been carried out using Bonner sphere systems (BSS) with activation foils and TLDs. In this work, a recently developed active detector, the nested neutron spectrometer (NNS), was tested in radiotherapy bunkers. Methods: The NNS is designed for easy handling and is more practical than the traditional BSS. Operated in current-mode, the problem of pulse pileup due to high dose-rates is overcome by measuring current, similar to an ionization chamber. In a bunker housing a Varian Clinac 21EX, the performance of the NNS was evaluated in terms of reproducibility, linearity, and dose-rate effects. Using a custom maximum-likelihood expectation–maximization algorithm, measured neutron spectra at various locations inside the bunker were then compared to Monte Carlo simulations of an identical setup. In terms of dose, neutron ambient dose equivalents were calculated from the measured spectra and compared to bubble detector neutron dose equivalent measurements. Results: The NNS-measured spectra for neutrons at various locations in a treatment room were found to be consistent with expectations for both relative shape and absolute magnitude. Neutron fluence-rate decreased with distance from the source and the shape of the spectrum changed from a dominant fast neutron peak near the Linac head to a dominant thermal neutron peak in the moderating conditions of the maze. Monte Carlo data and NNS-measured spectra agreed within 30% at all locations except in the maze where the deviation was a maximum of 40%. Neutron ambient dose equivalents calculated from the authors’ measured spectra were consistent (one standard deviation) with bubble detector measurements in the treatment room. Conclusions: The NNS may

Neutron recognition in the LAND detector for large neutron multiplicity

Energy Technology Data Exchange (ETDEWEB)

Pawlowski, P., E-mail: piotr.pawlowski@ifj.edu.pl [Institute of Nuclear Physics, PAN, Radzikowskiego 152, 31-342 Krakow (Poland); Brzychczyk, J. [Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow (Poland); Leifels, Y.; Trautmann, W. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Adrich, P. [National Centre for Nuclear Research, PL-00681 Warsaw (Poland); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Aumann, T. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Bacri, C.O. [Institut de Physique Nucleaire, IN2P3-CNRS et Universite, F-91406 Orsay (France); Barczyk, T. [Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow (Poland); Bassini, R. [Istituto di Scienze Fisiche, Universita degli Studi and INFN, I-20133 Milano (Italy); Bianchin, S. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Boiano, C. [Istituto di Scienze Fisiche, Universita degli Studi and INFN, I-20133 Milano (Italy); Boretzky, K. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Boudard, A. [IRFU/SPhN, CEA/Saclay, F-91191 Gif-sur-Yvette (France); Chbihi, A. [GANIL, CEA et IN2P3-CNRS, F-14076 Caen (France); Cibor, J.; Czech, B. [Institute of Nuclear Physics, PAN, Radzikowskiego 152, 31-342 Krakow (Poland); De Napoli, M. [Dipartimento di Fisica e Astronomia-Universita and INFN-CT and LNS, I-95123 Catania (Italy); and others

2012-12-01

The performance of the LAND neutron detector is studied. Using an event-mixing technique based on one-neutron data obtained in the S107 experiment at the GSI laboratory, we test the efficiency of various analytic tools used to determine the multiplicity and kinematic properties of detected neutrons. A new algorithm developed recently for recognizing neutron showers from spectator decays in the ALADIN experiment S254 is described in detail. Its performance is assessed in comparison with other methods. The properties of the observed neutron events are used to estimate the detection efficiency of LAND in this experiment.

Nanosecond neutron generator

International Nuclear Information System (INIS)

Lobov, S.I.; Pavlovskaya, N.G.; Pukhov, S.P.

1991-01-01

High-voltage nanosecond neutron generator for obtaining neutrons in D-T reaction is described. Yield of 6x10 6 neutron/pulse was generated in a sealed gas-filled diode with a target on the cathode by accelerating pulse voltage of approximately 0.5 MV and length at half-height of 0.5 ns and deuterium pressure of 6x10 -2 Torr. Ways of increasing neutron yield and possibilities of creating generators of nanosecond neutron pulses with great service life are considered

Neutron transport

International Nuclear Information System (INIS)

Berthoud, Georges; Ducros, Gerard; Feron, Damien; Guerin, Yannick; Latge, Christian; Limoge, Yves; Santarini, Gerard; Seiler, Jean-Marie; Vernaz, Etienne; Coste-Delclaux, Mireille; M'Backe Diop, Cheikh; Nicolas, Anne; Andrieux, Catherine; Archier, Pascal; Baudron, Anne-Marie; Bernard, David; Biaise, Patrick; Blanc-Tranchant, Patrick; Bonin, Bernard; Bouland, Olivier; Bourganel, Stephane; Calvin, Christophe; Chiron, Maurice; Damian, Frederic; Dumonteil, Eric; Fausser, Clement; Fougeras, Philippe; Gabriel, Franck; Gagnier, Emmanuel; Gallo, Daniele; Hudelot, Jean-Pascal; Hugot, Francois-Xavier; Dat Huynh, Tan; Jouanne, Cedric; Lautard, Jean-Jacques; Laye, Frederic; Lee, Yi-Kang; Lenain, Richard; Leray, Sylvie; Litaize, Olivier; Magnaud, Christine; Malvagi, Fausto; Mijuin, Dominique; Mounier, Claude; Naury, Sylvie; Nicolas, Anne; Noguere, Gilles; Palau, Jean-Marc; Le Pallec, Jean-Charles; Peneliau, Yannick; Petit, Odile; Poinot-Salanon, Christine; Raepsaet, Xavier; Reuss, Paul; Richebois, Edwige; Roque, Benedicte; Royer, Eric; Saint-Jean, Cyrille de; Santamarina, Alain; Serot, Olivier; Soldevila, Michel; Tommasi, Jean; Trama, Jean-Christophe; Tsilanizara, Aime; Behar, Christophe; Provitina, Olivier; Lecomte, Michael; Forestier, Alain; Bender, Alexandra; Parisot, Jean-Francois; Finot, Pierre

2013-10-01

This bibliographical note presents a reference book which addresses the study of neutron transport in matter, the study of conditions for a chain reaction and the study of modifications of matter composition due to nuclear reactions. This book presents the main nuclear data, their measurement, assessment and processing, and the spallation. It proposes an overview of methods applied for the study of neutron transport: basic equations and their derived forms, deterministic methods and Monte Carlo method of resolution of the Boltzmann equation, methods of resolution of generalized Bateman equations, methods of time resolution of space kinetics coupled equations. It presents the main calculation codes, discusses the qualification and experimental aspects, and gives an overview of neutron transport applications: neutron transport calculation of reactors, neutron transport coupled with other disciplines, physics of fuel cycle, criticality

Dynamically Polarized Sample for Neutron Scattering At the Spallation Neutron Source

International Nuclear Information System (INIS)

Pierce, Josh; Zhao, J. K.; Crabb, Don

2009-01-01

The recently constructed Spallation Neutron Source at the Oak Ridge National Laboratory is quickly becoming the world's leader in neutron scattering sciences. In addition to the world's most intense pulsed neutron source, we are continuously constructing state of the art neutron scattering instruments as well as sample environments to address today and tomorrow's challenges in materials research. The Dynamically Polarized Sample project at the SNS is aimed at taking maximum advantage of polarized neutron scattering from polarized samples, especially biological samples that are abundant in hydrogen. Polarized neutron scattering will allow us drastically increase the signal to noise ratio in experiments such as neutron protein crystallography. The DPS project is near completion and all key components have been tested. Here we report the current status of the project.

Neutron response study

International Nuclear Information System (INIS)

Endres, G.W.R.; Fix, J.J.; Thorson, M.R.; Nichols, L.L.

1981-01-01

Neutron response of the albedo type dosimeter is strongly dependent on the energy of the incident neutrons as well as the moderating material on the backside of the dosimeter. This study characterizes the response of the Hanford dosimeter for a variety of neutron energies for both a water and Rando phantom (a simulated human body consisting of an actual human skeleton with plastic for body muscles and certain organs). The Hanford dosimeter response to neutrons of different energies is typical of albedo type dosimeters. An approximate two orders of magnitude difference in response is observed between neutron energies of 100 keV and 10 MeV. Methods were described to compensate for the difference in dosimeter response between a laboratory neutron spectrum and the different spectra encountered at various facilities in the field. Generally, substantial field support is necessary for accurate neutron dosimetry

Basic of Neutron NDA

Energy Technology Data Exchange (ETDEWEB)

Trahan, Alexis Chanel [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-09-15

The objectives of this presentation are to introduce the basic physics of neutron production, interactions and detection; identify the processes that generate neutrons; explain the most common neutron mechanism, spontaneous and induced fission and (a,n) reactions; describe the properties of neutron from different sources; recognize advantages of neutron measurements techniques; recognize common neutrons interactions; explain neutron cross section measurements; describe the fundamental of ³He detector function and designs; and differentiate between passive and active assay techniques.

A study on the utilization of hyper-thermal neutrons for neutron capture therapy

International Nuclear Information System (INIS)

Sakurai, Yoshinori; Kobayashi, Tooru; Kanda, Keiji

1993-01-01

The utilization of hyper-thermal neutrons, which have an energy spectrum of a Maxwellian distribution of a higher temperature than the room temperature of 300 K, was studied in order to improve the thermal neutron flux distribution at the deeper part in a living body for neutron capture therapy. Simulation calculations were carried out using MCNP-V3 in order to confirm the characteristics of hyper-thermal neutrons, i.e., (1) depth dependence of neutron energy spectrum, and (2) depth distribution of the reaction rate in a water phantom for materials with 1/v neutron absorption. It is confirmed that the hyper-thermal neutron irradiation can improve the thermal neutron flux distribution in the deeper and wider area in a living body compared with the thermal neutron irradiation. Practically, by the incidence of the hyper-thermal neutrons with a 3000 K Maxwellian distribution, the thermal neutron flux at 5 cm depth can be given about four times larger than by the incidence of the thermal neutrons of 300 K. (author)

On-line monitoring for the detection and prevention of faults in the power transformers; Monitoreo en linea para la deteccion y prevencion de fallas en transformadores de potencia

Energy Technology Data Exchange (ETDEWEB)

Lopez Tagle, Alfredo; Equihua Tapia, Hugo [Comision Federal de Electricidad (Mexico); Linan Garcia, Roberto; Pascacio de los Santos, Alberth; Nunez Dominguez, Arturo [Instituto de Investigaciones Electricas, Temixco, Morelos (Mexico)

2000-07-01

Power transformers are held to thermal, electrical and mechanical efforts, which degrade the isolation system oil/paper. So that to detect incipient degradations in transformers with more than 25 years of service installed in the transmission network of Commission Federal de Electricidad (CFE). The Instituto de Investigaciones Electricas (IIE), developed and installed six on-line Monitoring Systems for Power Transformers (SMLTP). The systems are installed at the substations Puebla II, banks AT-1 and AT-2, Malpaso II, bank, AT-1 and phase B of bank AT-1 of the electrical substation Villa de Garcia. [Spanish] Los transformadores de potencia estan sujetos a esfuerzos termicos, electricos y mecanicos, los cuales degradan el sistema de aislamiento aceite/papel. De modo que con el proposito de detectar degradaciones incipientes en transformadores con mas de 25 anos de servicio instalado en la red de transmision de la Comision Federal de Electricidad (CFE). El Instituto de Investigaciones Electricas (IIE), desarrollo e instalo seis Sistemas de Monitoreo en Linea para Transformadores de Potencia (SMLTP). Los sistemas se encuentran en las subestaciones Puebla II, bancos AT-1 y AT-2, Malpaso II, banco, AT-1 y fase B del banco AT-1 de la subestacion electrica Villa de Garcia.

Method to allow the estimation of heat transfer coefficients in solar stills; Metodo para determinar coeficientes locales de transferencia de calor en destiladores solares

Energy Technology Data Exchange (ETDEWEB)

Rubio Cerda, Eduardo; Porta Gandara, Miguel A [CIBNOR, Mexico D.F (Mexico); Fernandez Zayas, Jose Luis [UNAM Mexico, D.F. (Mexico)

2000-07-01

This work reports an experimental method that allows to estimate the heat transfer coefficients in the neighborhood of walls or flat plates subject to convective transport phenomena. This method can be applied to a great variety of thermal systems since it is based on the knowledge of the border condition for the temperature at the surface of the plate, and the temperature profile that characterize the dimensionless coefficient of heat transfer in the fluid, according to its definition given by the Nusselt number. The approach of this work are the foundations of the method and the system that has been developed to apply it, that incorporates automatic acquisition equipment for continuos monitoring of the information and elements to control the parameters of interest. In addition, the experimental cavities on which the method will be evaluated are discussed, considering two different scales, as well as experiments in cavities filled with air, and with a mixture of air and steam water, as is the case for solar distillation. [Spanish] En este trabajo se presenta un metodo que permite determinar de manera experimental coeficientes de transferencia de calor por conveccion. Este metodo puede ser aplicado a una gran variedad de sistemas termicos ya que se fundamenta en el conocimiento de la condicion de frontera para la temperatura en la superficie de la placa, y del perfil de temperaturas que caracteriza el coeficiente adimensional de transferencia de calor en el fluido, de acuerdo a la definicion de este, dada por el numero de Nusselt. El trabajo que aqui se reporta esta enfocado a la fundamentacion del metodo y al equipamiento que se ha desarrollado para instrumentarlo, que incorpora equipos automaticos de adquisicion continua de informacion y elementos de control para los parametros de interes. Se presentan ademas, las cavidades experimentales sobre las que sera evaluado el metodo, que considera dos escalas diferentes, asi como experimentos en cavidades llenas de aire

Steel research using neutron beam techniques. In-situ neutron diffraction, small-angle neutron scattering and residual stress analysis

International Nuclear Information System (INIS)

Sueyoshi, Hitoshi; Ishikawa, Nobuyuki; Yamada, Katsumi; Sato, Kaoru; Nakagaito, Tatsuya; Matsuda, Hiroshi; Arakaki, Yu; Tomota, Yo

2014-01-01

Recently, the neutron beam techniques have been applied for steel researches and industrial applications. In particular, the neutron diffraction is a powerful non-destructive method that can analyze phase transformation and residual stress inside the steel. The small-angle neutron scattering is also an effective method for the quantitative evaluation of microstructures inside the steel. In this study, in-situ neutron diffraction measurements during tensile test and heat treatment were conducted in order to investigate the deformation and transformation behaviors of TRIP steels. The small-angle neutron scattering measurements of TRIP steels were also conducted. Then, the neutron diffraction analysis was conducted on the high strength steel weld joint in order to investigate the effect of the residual stress distribution on the weld cracking. (author)

First results of micro-neutron tomography by use of a focussing neutron lens

CERN Document Server

Masschaele, B; Cauwels, P; Dierick, M; Jolie, J; Mondelaers, W

2001-01-01

Since the appearance of high flux neutron beams, scientists experimented with neutron radiography. This high beam flux combined with modern neutron to visible light converters leads to the possibility of performing fast neutron micro-tomography. The first results of cold neutron tomography with a neutron lens are presented in this article. Samples are rotated in the beam and the projections are recorded with a neutron camera. The 3D reconstruction is performed with cone beam reconstruction software.

Gamma/neutron competition above the neutron separation energy in delayed neutron emitters

Directory of Open Access Journals (Sweden)

Valencia E.

2014-03-01

Full Text Available To study the β-decay properties of some well known delayed neutron emitters an experiment was performed in 2009 at the IGISOL facility (University of Jyväskylä in Finland using Total Absorption γ-ray Spectroscopy (TAGS technique. The aim of these measurements is to obtain the full β-strength distribution below the neutron separation energy (Sn and the γ/neutron competition above. This information is a key parameter in nuclear technology applications as well as in nuclear astrophysics and nuclear structure. Preliminary results of the analysis show a significant γ-branching ratio above Sn.

Nuclear reactor neutron shielding

Science.gov (United States)

Speaker, Daniel P; Neeley, Gary W; Inman, James B

2017-09-12

A nuclear reactor includes a reactor pressure vessel and a nuclear reactor core comprising fissile material disposed in a lower portion of the reactor pressure vessel. The lower portion of the reactor pressure vessel is disposed in a reactor cavity. An annular neutron stop is located at an elevation above the uppermost elevation of the nuclear reactor core. The annular neutron stop comprises neutron absorbing material filling an annular gap between the reactor pressure vessel and the wall of the reactor cavity. The annular neutron stop may comprise an outer neutron stop ring attached to the wall of the reactor cavity, and an inner neutron stop ring attached to the reactor pressure vessel. An excore instrument guide tube penetrates through the annular neutron stop, and a neutron plug comprising neutron absorbing material is disposed in the tube at the penetration through the neutron stop.

Development of neutron detectors for neutron scattering experiments

Energy Technology Data Exchange (ETDEWEB)

Moon, Myungkook; Kim, Jongyul; Kim, Jeong ho; Lee, Suhyun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lee, Changhwy [Korea Research Institute of Ships and Ocean Engineering, Daejeon (Korea, Republic of)

2015-10-15

Various kinds of detectors are used in accordance with the experimental purpose, such as zero dimensional detector, 1-D or 2-D position-sensitive detectors. Most of neutron detectors use He-3 gas because of its high neutron sensitivity. Since the He-3 supply shortage took place in early 2010, various He-3 alternative detectors have been developed even for the other neutron application. We have developed a new type alternative detector on the basis of He-3 detector technology. Although B- 10 has less neutron detection efficiency compared with He-3, it can be covered by the use of multiple B-10 layers. In this presentation, we would like to introduce the neutron detectors under development and developed detectors. Various types of detector were successfully developed and result of the technical test performance is promising. Even though the detection efficiency of the B-10 detector lower than He-3 one, the continuous research and development is needed for currently not available He-3.

Fundamental neutron physics at a 1 MW long pulse spallation neutron source

International Nuclear Information System (INIS)

Greene, G.L.

1995-01-01

Modern neutron sources and modern neutron science share a common origin in mid twentieth century scientific investigations concerned with the study of the fundamental interactions between elementary particles. Since the time of that common origin, neutron science and the study of elementary particles have evolved into quite disparate disciplines. The neutron became recognized as a powerful tool for the study of condensed matter with modern neutron sources being primarily used (and primarily justified) as tools for condensed matter research. The study of elementary particles has, of course, led to the development of rather different tools and is now dominated by activities carried out at extremely high energies. Notwithstanding this trend, the study of fundamental interactions using neutrons has continued and remains a vigorous activity at many contemporary neutron sources. This research, like neutron scattering research, has benefited enormously by the development of modern high flux neutron facilities. Future sources, particularly high power spallation sources, offer exciting possibilities for the continuation of this program of research

Powder neutron diffractometers

International Nuclear Information System (INIS)

Adib, M.

2002-01-01

Basic properties and applications of powder neutron Diffractometers are described for optimum use of the continuous neutron beams. These instruments are equipped with position sensitive detectors, neutron guide tubes, and both high intensity and high resolution modes of operation are possible .The principles of both direct and Fourier reverse time-of-flight neutron Diffractometers are also given

Polycapillary neutron lenses

International Nuclear Information System (INIS)

Mildner, D.F.R.

1997-01-01

The principle of multiple mirror reflection from smooth surfaces at small grazing angles enables the transport and guiding of high intensity slow neutron beams to locations of low background for neutron scattering and absorption experiments and to provide facilities for multiple instruments. Curved guides have been widely used at cold neutron facilities to remove the unwanted radiation (fast neutrons and gamma rays) from the beam without the use of filters. A typical guide has transverse dimensions of 50 mm and, with a radius of curvature of 1 km, transmits wavelengths longer than 5 A. Much tighter curves requires narrower transverse dimensions, otherwise there is little transmission. Typical neutron benders have a number of slots with transverse dimensions of ∼5 mm. Based on the same principle but using a different technology, recent developments in glass polycapillary fibers have produced miniature versions of neutron guides. Fibers with many thousands of channels having sizes of ∼ 10 μm enable beams of long wavelength neutrons (λ > 4 A) to be transmitted efficiently in a radius of curvature as small as a fraction of 1 m. A large collection of these miniature versions of neutron guides can be used to bend the neutron trajectories such that the incident beam can be focused. (author)

Neutron structural biology

Energy Technology Data Exchange (ETDEWEB)

Niimura, Nobuo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1998-03-01

Neutron diffraction provides an experimental method of directly locating hydrogen atoms in protein which play important roles in physiological functions. However, there are relatively few examples of neutron crystallography in biology since it takes a lot of time to collect a sufficient number of Bragg reflections due to the low flux of neutrons illuminating the sample. In order to overcome the flux problem, we have successfully developed the neutron IP, where the neutron converter, {sup 6}Li or Gd, was mixed with a photostimulated luminescence material on flexible plastic support. Neutron Laue diffraction 2A data from tetragonal lysozyme were collected for 10 days with neutron imaging plates, and 960 hydrogen atoms in the molecule and 157 bound water molecules were identified. These results explain the proposed hydrolysis mechanism of the sugar by the lysozyme molecule and that lysozyme is less active at pH7.0. (author)

Neutron exposure

International Nuclear Information System (INIS)

Prillinger, G.; Konynenburg, R.A. van

1998-01-01

As a result of the popularity of the Agencies report 'Neutron Irradiation Embrittlement of Reactor Pressure Vessel Steels' of 1975, it was decided that another report on this broad subject would be of use. In this report, background and contemporary views on specially identified areas of the subject are considered as self-contained chapters, written by experts. In chapter 6, LWR-PV neutron transport calculations and dosimetry methods and how they are combined to evaluate the neutron exposure of the steel of pressure vessels are discussed. An effort to correlate neutron exposure parameters with damage is made

Atmospheric neutrons

International Nuclear Information System (INIS)

Preszler, A.M.; Moon, S.; White, R.S.

1976-01-01

Additional calibrations of the University of California double-scatter neutron and additional analysis corrections lead to the slightly changed neutron fluxes reported here. The theoretical angular distributions of Merker (1975) are in general agreement with our experimental fluxes but do not give the peaks for vertical upward and downward moving neutrons. The theoretical neutron escape current J 2 /sub pi/ (Merker, 1972; Armstrong et al., 1973) is in agreement with the experimental values from 10 to 100 MeV. Our experimental fluxes agree with those of the Kanbach et al. (1974) in the overlap region from 70 to 100 MeV

Study on neutron irradiation behavior of beryllium as neutron multiplier

Energy Technology Data Exchange (ETDEWEB)

Ishitsuka, Etsuo [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment

1998-03-01

More than 300 tons beryllium is expected to be used as a neutron multiplier in ITER, and study on the neutron irradiation behavior of beryllium as the neutron multiplier with Japan Materials Testing Reactor (JMTR) were performed to get the engineering data for fusion blanket design. This study started as the study on the tritium behavior in beryllium neutron reflector in order to make clear the generation mechanism on tritium of JMTR primary coolant since 1985. These experiences were handed over to beryllium studies for fusion study, and overall studies such as production technology of beryllium pebbles, irradiation behavior evaluation and reprocessing technology have been started since 1990. In this presentation, study on the neutron irradiation behavior of beryllium as the neutron multiplier with JMTR was reviewed from the point of tritium release, thermal properties, mechanical properties and reprocessing technology. (author)

Neutron source

International Nuclear Information System (INIS)

Cason, J.L. Jr.; Shaw, C.B.

1975-01-01

A neutron source which is particularly useful for neutron radiography consists of a vessel containing a moderating media of relatively low moderating ratio, a flux trap including a moderating media of relatively high moderating ratio at the center of the vessel, a shell of depleted uranium dioxide surrounding the moderating media of relatively high moderating ratio, a plurality of guide tubes each containing a movable source of neutrons surrounding the flux trap, a neutron shield surrounding one part of each guide tube, and at least one collimator extending from the flux trap to the exterior of the neutron source. The shell of depleted uranium dioxide has a window provided with depleted uranium dioxide shutters for each collimator. Reflectors are provided above and below the flux trap and on the guide tubes away from the flux trap

Neutron cooling and cold-neutron sources (1962)

International Nuclear Information System (INIS)

Jacrot, B.

1962-01-01

Intense cold-neutron sources are useful in studying solids by the inelastic scattering of neutrons. The paper presents a general survey covering the following aspects: a) theoretical considerations put forward by various authors regarding thermalization processes at very low temperatures; b) the experiments that have been carried out in numerous laboratories with a view to comparing the different moderators that can be used; c) the cold neutron sources that have actually been produced in reactors up to the present time, and the results obtained with them. (author) [fr

High energy neutron radiography

International Nuclear Information System (INIS)

Gavron, A.; Morley, K.; Morris, C.; Seestrom, S.; Ullmann, J.; Yates, G.; Zumbro, J.

1996-01-01

High-energy spallation neutron sources are now being considered in the US and elsewhere as a replacement for neutron beams produced by reactors. High-energy and high intensity neutron beams, produced by unmoderated spallation sources, open potential new vistas of neutron radiography. The authors discuss the basic advantages and disadvantages of high-energy neutron radiography, and consider some experimental results obtained at the Weapons Neutron Research (WNR) facility at Los Alamos

Intense fusion neutron sources

International Nuclear Information System (INIS)

Kuteev, B. V.; Goncharov, P. R.; Sergeev, V. Yu.; Khripunov, V. I.

2010-01-01

The review describes physical principles underlying efficient production of free neutrons, up-to-date possibilities and prospects of creating fission and fusion neutron sources with intensities of 10 15 -10 21 neutrons/s, and schemes of production and application of neutrons in fusion-fission hybrid systems. The physical processes and parameters of high-temperature plasmas are considered at which optimal conditions for producing the largest number of fusion neutrons in systems with magnetic and inertial plasma confinement are achieved. The proposed plasma methods for neutron production are compared with other methods based on fusion reactions in nonplasma media, fission reactions, spallation, and muon catalysis. At present, intense neutron fluxes are mainly used in nanotechnology, biotechnology, material science, and military and fundamental research. In the near future (10-20 years), it will be possible to apply high-power neutron sources in fusion-fission hybrid systems for producing hydrogen, electric power, and technological heat, as well as for manufacturing synthetic nuclear fuel and closing the nuclear fuel cycle. Neutron sources with intensities approaching 10 20 neutrons/s may radically change the structure of power industry and considerably influence the fundamental and applied science and innovation technologies. Along with utilizing the energy produced in fusion reactions, the achievement of such high neutron intensities may stimulate wide application of subcritical fast nuclear reactors controlled by neutron sources. Superpower neutron sources will allow one to solve many problems of neutron diagnostics, monitor nano-and biological objects, and carry out radiation testing and modification of volumetric properties of materials at the industrial level. Such sources will considerably (up to 100 times) improve the accuracy of neutron physics experiments and will provide a better understanding of the structure of matter, including that of the neutron itself.

Intense fusion neutron sources

Science.gov (United States)

Kuteev, B. V.; Goncharov, P. R.; Sergeev, V. Yu.; Khripunov, V. I.

2010-04-01

The review describes physical principles underlying efficient production of free neutrons, up-to-date possibilities and prospects of creating fission and fusion neutron sources with intensities of 1015-1021 neutrons/s, and schemes of production and application of neutrons in fusion-fission hybrid systems. The physical processes and parameters of high-temperature plasmas are considered at which optimal conditions for producing the largest number of fusion neutrons in systems with magnetic and inertial plasma confinement are achieved. The proposed plasma methods for neutron production are compared with other methods based on fusion reactions in nonplasma media, fission reactions, spallation, and muon catalysis. At present, intense neutron fluxes are mainly used in nanotechnology, biotechnology, material science, and military and fundamental research. In the near future (10-20 years), it will be possible to apply high-power neutron sources in fusion-fission hybrid systems for producing hydrogen, electric power, and technological heat, as well as for manufacturing synthetic nuclear fuel and closing the nuclear fuel cycle. Neutron sources with intensities approaching 1020 neutrons/s may radically change the structure of power industry and considerably influence the fundamental and applied science and innovation technologies. Along with utilizing the energy produced in fusion reactions, the achievement of such high neutron intensities may stimulate wide application of subcritical fast nuclear reactors controlled by neutron sources. Superpower neutron sources will allow one to solve many problems of neutron diagnostics, monitor nano-and biological objects, and carry out radiation testing and modification of volumetric properties of materials at the industrial level. Such sources will considerably (up to 100 times) improve the accuracy of neutron physics experiments and will provide a better understanding of the structure of matter, including that of the neutron itself.

Thermal neutron flux measurements using neutron-electron converters; Mesure de flux de neutrons thermiques avec des convertisseurs neutrons electrons

Energy Technology Data Exchange (ETDEWEB)

Le Meur, R; Lecomte, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1968-07-01

The operation of neutron-electron converters designed for measuring thermal neutron fluxes is examined. The principle is to produce short lived isotopes emitting beta particles, by activation, and to measure their activity not by extracting them from the reactor, but directly in the reactor using the emitted electrons to deflect the needle of a galvanometer placed outside the flux. After a theoretical study, the results of the measurements are presented; particular attention is paid to a new type of converter characterized by a layer structure. The converters are very useful for obtaining flux distributions with more than 10{sup 7} neutrons cm{sup -2}*sec{sup -1}. They work satisfactorily in pressurized carbon dioxide at 400 Celsius degrees. Some points still have to be cleared up however concerning interfering currents in the detectors and the behaviour of the dielectrics under irradiation. (authors) [French] On examine le fonctionnement de convertisseurs neutrons electrons destines a des mesures de flux de neutrons thermiques. Le principe est de former par activation des isotopes a periodes courtes et a emission beta et de mesurer leur activite non pas en les sortant du reacteur, mais directement en pile, utilisant les electrons emis pour faire devier l'aiguille d'un galvanometre place hors flux. Apres une etude theorique, on indique des resultats de mesures obtenus, en insistant particulierement sur un nouveau type de convertisseur, caracterise par sa structure stratifiee. Les convertisseurs sont tres interessants pour tracer, des cartes de flux a partir de 10{sup 7} neutrons cm{sup -2}*s{sup -1}. Ils sont utilisables pour des flux de 10{sup 14} neutrons cm{sup -2}*s{sup -1}. Ils fonctionnent correctement dans du gaz carbonique sous pression a 400 C. Des points restent cependant a eclaircir concernant les courants parasites dans les detecteurs et le comportement des dielectriques pendant leur irradiation. (auteur)

Application of MSS-neutron spin echo spectrometer to pulsed neutron sources

International Nuclear Information System (INIS)

Tasaki, S.; Ebisawa, T.; Hino, M.; Kawai, T.

2001-01-01

A multilayer spin splitter (MSS) is a neutron device that gives phase difference between field-parallel and -antiparallel spin component of a superposing state. Since the phase difference is equivalent to the Larmor precession angle, MSS enables us to construct a new type of neutron spin echo (NSE) spectrometer. The new NSE spectrometer has its properties that 1. since the phase shift is neutron flight path length, the spectrometer can be drastically small, 2. the neutron spin echo time is proportional to the neutron wavelength. (author)

A simple and rapid method for measurement of 10B-para-boronophenylalanine in the blood for boron neutron capture therapy using fluorescence spectrophotometry

International Nuclear Information System (INIS)

Kashino, Genro; Fukutani, Satoshi; Suzuki, Minoru

2009-01-01

10 B deriving from 10 B-para-boronophenylalanine (BPA) and 10 B-borocaptate sodium (BSH) have been detected in blood samples of patients undergoing boron neutron capture therapy (BNCT) using prompt gamma ray spectrometer or Inductively Coupled Plasma (ICP) method, respectively. However, the concentration of each compound cannot be ascertained because boron atoms in both molecules are the target in these assays. Here, we propose a simple and rapid method to measure only BPA by detecting fluorescence based on the characteristics of phenylalanine. 10 B concentrations of blood samples from human or mice were estimated by the fluorescence intensities at 275 nm of a BPA excited by light of wavelength 257 nm using a fluorescence spectrophotometer. The relationship between fluorescence to increased BPA concentration showed a positive linear correlation. Moreover, we established an adequate condition for BPA measurement in blood samples containing BPA, and the estimated 10 B concentrations of blood samples derived from BPA treated mice were similar between the values obtained by our method and those by ICP method. This new assay will be useful to estimate BPA concentration in blood samples obtained from patients undergoing BNCT especially in a combination use of BSH and BPA. (author)

Neutron Research in HANARO

International Nuclear Information System (INIS)

Kim, Hark Rho

2005-01-01

HANARO (High-flux Advanced Neutron Application Reactor), which was designed and constructed by indigenous technology, is a world-class multi-purpose research reactor with a design thermal power of 30 MW, providing high neutron flux for various applications in Korea. HANARO has been operated since its first criticality in February 1995, and is now successfully utilized in such areas as neutron beam research, fuel and materials tests, radioisotopes and radiopharmaceuticals production, neutron activation analysis, and neutron transmutation doping, etc. A number of experimental facilities have been developed and installed since the beginning of reactor operation, and R and D activities for installing more facilities are actively under progress. Three flux traps in the core (CT, IR1, IR2), providing a high fast neutron flux, can be used for materials and fuel irradiation tests. They are also proper for production of high specific activity radioisotopes. Four vertical holes in the outer core region, abundant in epithermal neutrons, are used for fuel or material tests and radioisotope production. In the heavy water reflector region, 25 vertical holes with high quality thermal neutrons are located for radioisotope production, neutron activation analysis, neutron transmutation doping and cold neutron source installation. The two largest holes named NTD1 and NTD2 are for neutron transmutation doping, CNS for the cold neutron source installation, and LH for the irradiation of large targets. The high resolution powder diffractometer (HRPD) became operational in 1998, followed by the four circle diffractometer (FCD) in 1999, the residual stress instrument (RSI) in 2000, and the small angle neutron spectrometer (SANS) in 2001, respectively. HRPD and SANS became the most popular instruments these days, attracting wide range of users from academia, institutes and industries. We have made a lot of efforts during the last 10 years to develop some key components such as

Deteriorating mechanisms of electric generators; Mecanismos de deterioro de generadores electricos

Energy Technology Data Exchange (ETDEWEB)

Garcia Tevillo, Arturo; Reyes Martinez, Oscar Alfonso; Robles Pimentel, Edgar Guillermo; Esparza Saucedo, Marcos; Lopez Azamar, Jose Ernesto; Medina Flores, Alfredo; Uribe Martinez, Manuel O [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

1999-12-31

It is of the greatest importance to know the deteriorating mechanisms that an electric generator undergoes, in order to take corrective measures to stop the process in order to avoid catastrophic damages that imply non scheduled interruptions for maintenance, or inclusively, to carry on the overhaul. In this paper are discussed the deteriorating mechanisms that have been found in the stator (winding and core) and the rotor of thermoelectric and hydroelectric power stations by the natural aging process and abnormal operation. [Espanol] Es de suma importancia conocer los mecanismos de deterioro que sufre un generador, para tomar medidas correctivas que detengan el proceso, con el fin de evitar danos catastroficos que impliquen salidas no programadas para dar mantenimiento, o incluso, para efectuar la rehabilitacion. En este articulo se discuten los mecanismos de deterioro que se han encontrado en el estator (devanado y nucleo) y el rotor de generadores termicos e hidroelectricos por el proceso natural de envejecimiento y por operacion anormal.

Deteriorating mechanisms of electric generators; Mecanismos de deterioro de generadores electricos

Energy Technology Data Exchange (ETDEWEB)

Garcia Tevillo, Arturo; Reyes Martinez, Oscar Alfonso; Robles Pimentel, Edgar Guillermo; Esparza Saucedo, Marcos; Lopez Azamar, Jose Ernesto; Medina Flores, Alfredo; Uribe Martinez, Manuel O. [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

1998-12-31

It is of the greatest importance to know the deteriorating mechanisms that an electric generator undergoes, in order to take corrective measures to stop the process in order to avoid catastrophic damages that imply non scheduled interruptions for maintenance, or inclusively, to carry on the overhaul. In this paper are discussed the deteriorating mechanisms that have been found in the stator (winding and core) and the rotor of thermoelectric and hydroelectric power stations by the natural aging process and abnormal operation. [Espanol] Es de suma importancia conocer los mecanismos de deterioro que sufre un generador, para tomar medidas correctivas que detengan el proceso, con el fin de evitar danos catastroficos que impliquen salidas no programadas para dar mantenimiento, o incluso, para efectuar la rehabilitacion. En este articulo se discuten los mecanismos de deterioro que se han encontrado en el estator (devanado y nucleo) y el rotor de generadores termicos e hidroelectricos por el proceso natural de envejecimiento y por operacion anormal.

Photoneutron cross sections measurements in {sup 9}Be, {sup 13}C e {sup 17}O with thermal neutron capture gamma-rays; Medidas das secoes de choque de fotoneutrons do {sup 9}Be, {sup 13}C e {sup 17}O com radiacao gama de captura de neutrons termicos

Energy Technology Data Exchange (ETDEWEB)

Semmler, Renato

2006-07-01

Photoneutron cross sections measurements of {sup 9}Be, {sup 13}C and {sup 17}O have been obtained in the energy interval between 1,6 and 10,8 MeV, using neutron capture gamma-rays with high resolution in energy (3 a 21 eV), produced by 21 target materials, placed inside a tangential beam port, near the core of the IPEN/CNEN-SP IEA-R1 (5 MW) research reactor. The samples have been irradiated inside a 4{pi} geometry neutron detector system 'Long Counter', 520,5 cm away from the capture target. The capture gamma-ray flux was determined by means of the analysis of the gamma spectrum obtained by using a Ge(Li) solid-state detector (EG and G ORTEC, 25 cm{sup 3}, 5%), previously calibrated with capture gamma-rays from a standard target of Nitrogen (Melamine). The neutron photoproduction cross section has been measured for each target capture gamma-ray spectrum (compound cross section). A inversion matrix methodology to solve inversion problems for unfolding the set of experimental compound cross sections, was used in order to obtain the cross sections at specific excitation energy values (principal gamma line energies of the capture targets). The cross sections obtained at the energy values of the principal gamma lines were compared with experimental data reported by other authors, with have employed different gamma-ray sources. A good agreement was observed among the experimental data in this work with reported in the literature. (author)

Neutron capture therapy with thermal neutrons at IRT MIFI

International Nuclear Information System (INIS)

Zajtsev, K.N.; Portnov, A.A.; Savkin, V.A.; Kulakov, V.N.; Khokhlov, V.F.; Shejno, I.N.; Vajnson, A.A.; Kozlovskaya, N.G.; Meshcherikova, V.V.; Mitin, V.N.; Yarmonenko, S.P.

2001-01-01

Combined preclinical investigations into neutron capture therapy are conducted. Malignant melanoma was adopted as the line of investigation; boron-containing and gadolinium-containing preparations were used during the neutron capture therapy working off. Preparations produce secondary varying radiations when used in tumor. Dogs with spontaneous melanoma were used for the experiments. Procedures for the irradiation of dogs by neutron beam as the stage before use for the treatment of oncology patients were finished off; efficiency of neutron beam influence on normal tissues during the irradiation of dogs with melanoma (and without it) in antitumor and side effect sense was estimated [ru

Primary Distributions of Nuclear Charge for Fission-Fragment Masses 132, 134, 136 and 137 from Thermal Fission of U{sup 235}; Repartition Primaire de la Charge Nucleaire pour les Fragments de Masse 132, 134, 136 et 137, Provenant de la Fission de {sup 235}U par Neutrons Thermiques; 041f 0415 0420 0414 ; Distribuciones Primarias de las Cargas Nucleares de los Fragmentos de Masa 132, 134, 136 y 137, Resultantes de la Fision del {sup 235}U por Neutrones Termicos

Energy Technology Data Exchange (ETDEWEB)

Konecny, E.; Opower, H.; Guenther, H.; Goebel, H. [Physik-Department der Technischen Hochschule Muenchen, Munich and II. Physikalisches Institut der Justus Liebig-Universitaet Giessen, Federal Republic of Germany (Germany)

1965-07-15

= 82 que sont dues les charges primaires les plus probables voisines de 50 et 52 respectivement. Lorsque M = 136 ou 137, la charge primaire est d'environ 53 et 53,2. Il s'est revele que les corrections approximatives supplementaires pour tenir compte des electrons de conversion (en negligeant les traces {beta} tres courtes correspondant a des energies {beta} tres faibles) et des neutrons retardes (pour la masse 137) ne sont pas tres importantes. On prepare actuellement des mesures analogues qui seront effectuees directement dans une geometrie 4{pi}, de maniere a eviter l'erreur statistique qu'entraine la transformation de la distribution 2{pi} en distribution 4{pi}, et qui porteront sur differentes energies cinetiques prises comme parametres. (author) [Spanish] Los fragmentos resultantes de la fision del {sup 235}U por neutrones termicos se separan exactamente segun su masa y energia cinetica con ayuda de un espectrometro de masas en el microsegundo que sigue a la fision. Los fragmentos separados se recogen en una emulsion Ilford G-5 sensible a las particulas beta, colocada en el plano focal del espectrometro. El revelado de las emulsiones irradiadas se efectua, en lo posible, despues de haber transcurrido un tiempo suficientemente largo en relacion con el periodo mas prolongado que aparece en la cadena de desintegracion considerada. Los periodos del orden de dias o mas largos no se tienen en cuenta, pero pueden introducirse facilmente las correcciones adecuadas. Despues del revelado de la emulsion, pueden verse al microscopio todas las trazas de particulas beta que surgen del extremo de la traza de cada fragmento de fision. La posibilidad de correlacionar cada traza de particula beta con la traza de un fragmento de fision determinado permite calcular el numero n(x) de fragmentos de fision a los que corresponden x trazas de particulas beta, lo que indica no solo la longitud media de la cadena, sino tambien la distribucion de las particulas beta. Como el producto final

Compact neutron generator

Science.gov (United States)

Leung, Ka-Ngo; Lou, Tak Pui

2005-03-22

A compact neutron generator has at its outer circumference a toroidal shaped plasma chamber in which a tritium (or other) plasma is generated. A RF antenna is wrapped around the plasma chamber. A plurality of tritium ion beamlets are extracted through spaced extraction apertures of a plasma electrode on the inner surface of the toroidal plasma chamber and directed inwardly toward the center of neutron generator. The beamlets pass through spaced acceleration and focusing electrodes to a neutron generating target at the center of neutron generator. The target is typically made of titanium tubing. Water is flowed through the tubing for cooling. The beam can be pulsed rapidly to achieve ultrashort neutron bursts. The target may be moved rapidly up and down so that the average power deposited on the surface of the target may be kept at a reasonable level. The neutron generator can produce fast neutrons from a T-T reaction which can be used for luggage and cargo interrogation applications. A luggage or cargo inspection system has a pulsed T-T neutron generator or source at the center, surrounded by associated gamma detectors and other components for identifying explosives or other contraband.

Thermal neutron moderating device

International Nuclear Information System (INIS)

Takigami, Hiroyuki.

1995-01-01

In a thermal neutron moderating device, superconductive coils for generating magnetic fields capable of applying magnetic fields vertical to the longitudinal direction of a thermal neutron passing tube, and superconductive coils for magnetic field gradient for causing magnetic field gradient in the longitudinal direction of the thermal neutron passing tube are disposed being stacked at the outside of the thermal neutron passing tube. When magnetic field gradient is present vertically to the direction of a magnetic moment, thermal neutrons undergo forces in the direction of the magnetic field gradient in proportion to the magnetic moment. Then, the magnetic moment of the thermal neutrons is aligned with the direction vertical to the passing direction of the thermal neutrons, to cause the magnetic field gradient in the passing direction of the thermal neutrons. The speed of the thermal neutrons can be optionally selected and the wavelength can freely be changed by applying forces to the thermal neutrons and changing the extent and direction of the magnetic field gradient. Superconductive coils are used as the coils for generating magnetic fields and the magnetic field gradient in order to change extremely high energy of the thermal neutrons. (N.H.)

Reactor Neutron Sources

International Nuclear Information System (INIS)

Aksenov, V.L.

1994-01-01

The present status and the prospects for development of reactor neutron sources for neutron scattering research in the world are considered. The fields of application of neutron scattering relative to synchrotron radiation, the creation stages of reactors (steady state and pulsed) and their position in comparison with spallation neutron sources at present and in the foreseen future are discussed. (author). 15 refs.; 8 figs.; 3 tabs

Evaluation of the environmental equivalent dose rate using area monitors for neutrons in clinical linear accelerators; Avaliacao da taxa de equivalente de dose ambiente utilizando monitores de area para neutrons em aceleradores lineares clinicos

Energy Technology Data Exchange (ETDEWEB)

Salgado, Ana Paula; Pereira, Walsan Wagner; Patrao, Karla C. de Souza; Fonseca, Evaldo S. da, E-mail: asalgado@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Batista, Delano V.S. [Instituto Nacional do Cancer (INCa), Rio de Janeiro, RJ (Brazil)

2009-07-01

The Neutron Laboratory of the Radioprotection and Dosimetry Institute - IRD/CNEN, Rio de Janeiro, Brazil, initiated studies on the process of calibration of neutron area monitors and the results of the measurements performed at radiotherapy treatment rooms, containing clinical accelerators

Neutron Albedo

CERN Document Server

Ignatovich, V K

2005-01-01

A new, algebraic, method is applied to calculation of neutron albedo from substance to check the claim that use of ultradispersive fuel and moderator of an active core can help to gain in size and mass of the reactor. In a model of isotropic distribution of incident and reflected neutrons it is shown that coherent scattering on separate grains in the case of thermal neutrons increases transport cross section negligibly, however it decreases albedo from a wall of finite thickness because of decrease of substance density. A visible increase of albedo takes place only for neutrons with wave length of the order of the size of a single grain.

Progress report: determinations of the neutron-neutron scattering length ann from kinematically incomplete neutron-deuteron breakup data revisited

International Nuclear Information System (INIS)

Tornow, W.; Braun, R.T.; Witala, H.

1996-01-01

We review published analyses of the final-state-interaction enhancement observed in proton energy distributions obtained from kinematically incomplete neutron-deuteron breakup experiments. We compare the results derived from these analyses for the neutron-neutron scattering length, a nn with our results based on a rigorous treatment of the three-nucleon Faddeev equations in conjunction with the use of realistic nucleon-nucleon potentials. Our values for a nn deviate outside the quoted uncertainties from the ones obtained in the previous analyses where simplified nucleon-nucleon interaction models were employed. In contrast to the previous determinations, the present results for a nn are in clear disagreement with the values for a nn based on π - -deuteron capture experiments. Unless inconsistencies in the experimental neutron-deuteron breakup data at low energies can be resolved and the influence of possible three-nucleon-force effects can be reliably determined, we recommend that one not resort to the kinematically incomplete neutron-deuteron breakup reaction as a tool for determining a quantity as important for nuclear and particle physics as is the neutron-neutron scattering length a nn . (author)

Neutron Flux Distribution on Neutron Radiography Facility After Fixing the Collimator

International Nuclear Information System (INIS)

Supandi; Parikin; Mohtar; Sunardi; Roestam, S

1996-01-01

The Radiography Neutron Facility consists of an inner collimator, outer collimator, main shutter, second shutter and the sample chamber with 300 mm in diameter. Neutron beam quality depends on the neutron flux intensities distribution, L/D ratio Cd ratio, neutron/gamma ratio. The results show that the neutron flux intensity was 2.83 x 107 n cm-2.s-1, with deviation of + 7.8 % and it was distributed homogeneously at the sample position of 200 mm diameter. The beam characteristics were L/D ratio 98 and Rod 8, and neutron gamma ratio 3.08 x 105n.cm-2.mR-1 and Reactor Power was 20 MW. This technique can be used to examine sample with diameter of < 200 mm

Refractive neutron lens

International Nuclear Information System (INIS)

Petrov, P.V.; Kolchevsky, N.N.

2013-01-01

Model of the refractive neutron lens is proposed. System of N lenses acts as one thin lens with a complex refraction index n*. The maximum number N max of individual lenses for 'thick' neutron lens is calculated. Refractive neutron lens properties (resolution, focal depth) as function of resolution factor F 0 =ρbc/μ and depth of field factor dF 0 =λF 0 =λρbc/μ are calculated. It is shown that micro resolution of the refractive neutron optics is far from the wavelength in size and its open possibilities for progress in refractive neutron optics. (authors)

The neutron

International Nuclear Information System (INIS)

Kredov, B.M.

1979-01-01

The history of the neutron is displayed on the basis of contributions by scientists who produced outstanding results in neutron research (part 1), of summarizing discoveries and theories which led to the discovery of the neutron and the resulting development of nuclear physics (part 2), and of fundamental papers written by Rutherford, Chadwick, Iwanenko, and others (appendix). Of interest to physicists, historians, and students

Prototype Neutron Energy Spectrometer

International Nuclear Information System (INIS)

Mitchell, Stephen; Mukhopadhyay, Sanjoy; Maurer, Richard; Wolff, Ronald

2010-01-01

The project goals are: (1) Use three to five pressurized helium tubes with varying polyethylene moderators to build a neutron energy spectrometer that is most sensitive to the incident neutron energy of interest. Neutron energies that are of particular interest are those from the fission neutrons (typically around 1-2 MeV); (2) Neutron Source Identification - Use the neutron energy 'selectivity' property as a tool to discriminate against other competing processes by which neutrons are generated (viz. Cosmic ray induced neutron production (ship effect), (a, n) reactions); (3) Determine the efficiency as a function of neutron energy (response function) of each of the detectors, and thereby obtain the composite neutron energy spectrum from the detector count rates; and (4) Far-field data characterization and effectively discerning shielded fission source. Summary of the presentation is: (1) A light weight simple form factor compact neutron energy spectrometer ready to be used in maritime missions has been built; (2) Under laboratory conditions, individual Single Neutron Source Identification is possible within 30 minutes. (3) Sources belonging to the same type of origin viz., (a, n), fission, cosmic cluster in the same place in the 2-D plot shown; and (4) Isotopes belonging to the same source origin like Cm-Be, Am-Be (a, n) or Pu-239, U-235 (fission) do have some overlap in the 2-D plot.

Prototype Neutron Energy Spectrometer

Energy Technology Data Exchange (ETDEWEB)

Stephen Mitchell, Sanjoy Mukhopadhyay, Richard Maurer, Ronald Wolff

2010-06-16

The project goals are: (1) Use three to five pressurized helium tubes with varying polyethylene moderators to build a neutron energy spectrometer that is most sensitive to the incident neutron energy of interest. Neutron energies that are of particular interest are those from the fission neutrons (typically around 1-2 MeV); (2) Neutron Source Identification - Use the neutron energy 'selectivity' property as a tool to discriminate against other competing processes by which neutrons are generated (viz. Cosmic ray induced neutron production [ship effect], [a, n] reactions); (3) Determine the efficiency as a function of neutron energy (response function) of each of the detectors, and thereby obtain the composite neutron energy spectrum from the detector count rates; and (4) Far-field data characterization and effectively discerning shielded fission source. Summary of the presentation is: (1) A light weight simple form factor compact neutron energy spectrometer ready to be used in maritime missions has been built; (2) Under laboratory conditions, individual Single Neutron Source Identification is possible within 30 minutes. (3) Sources belonging to the same type of origin viz., (a, n), fission, cosmic cluster in the same place in the 2-D plot shown; and (4) Isotopes belonging to the same source origin like Cm-Be, Am-Be (a, n) or Pu-239, U-235 (fission) do have some overlap in the 2-D plot.

Conceptual moderator studies for the Spallation Neutron Source short-pulse second target station

Energy Technology Data Exchange (ETDEWEB)

Gallmeier, F. X., E-mail: gallmeierfz@ornl.gov; Lu, W.; Riemer, B. W.; Zhao, J. K.; Herwig, K. W.; Robertson, J. L. [Instrument and Source Division, Oak Ridge National Laboratory, P.O. Box 2008, MS6466, Oak Ridge, Tennessee 37831 (United States)

2016-06-15

Candidate moderator configurations for a short-pulse second target station (STS) at the Oak Ridge National Laboratory Spallation Neutron Source (SNS) have been identified using a global optimizer framework built around the MCNPX particle transport code. Neutron brightness metrics were selected as the figure-of-merit. We assumed that STS would use one out of six proton pulses produced by an SNS accelerator upgraded to operate at 1.3 GeV proton energy, 2.8 MW power and 60 Hz repetition rate. The simulations indicate that the peak brightness can be increased by a factor of 5 and 2.5 on a per proton pulse basis compared to the SNS first target station for both coupled and decoupled para-hydrogen moderators, respectively. Additional increases by factors of 3 and 2 were demonstrated for coupled and decoupled moderators, respectively, by reducing the area of neutron emission from 100 × 100 mm{sup 2} to 20 × 20 mm{sup 2}. This increase in brightness has the potential to translate to an increase of beam intensity at the instruments’ sample positions even though the total neutron emission of the smaller moderator is less than that of the larger. This is especially true for instruments with small samples (beam dimensions). The increased fluxes in the STS moderators come at accelerated poison and de-coupler burnout and higher radiation-induced material damage rates per unit power, which overall translate into lower moderator lifetimes. A first effort was undertaken to group decoupled moderators into a cluster collectively positioning them at the peak neutron production zone in the target and having a three-port neutron emission scheme that complements that of a cylindrical coupled moderator.

Ramsauer effect in triplet neutron-neutron scattering

International Nuclear Information System (INIS)

Pupyshev, V.V.; Solovtsova, O.P.

1995-01-01

As we show, due to interplay of pure nuclear and magnetic moment interactions, the total cross section of triplet neutron-neutron scattering should possess a non-zero limit at E cm = 0 and a local minimum at ∼ 20 keV. 17 refs., 1 fig

Spectral correction factors for conventional neutron dosemeters used in high-energy neutron environments

International Nuclear Information System (INIS)

Lee, K.W.; Sheu, R.J.

2015-01-01

High-energy neutrons (>10 MeV) contribute substantially to the dose fraction but result in only a small or negligible response in most conventional moderated-type neutron detectors. Neutron dosemeters used for radiation protection purpose are commonly calibrated with 252 Cf neutron sources and are used in various workplace. A workplace-specific correction factor is suggested. In this study, the effect of the neutron spectrum on the accuracy of dose measurements was investigated. A set of neutron spectra representing various neutron environments was selected to study the dose responses of a series of Bonner spheres, including standard and extended-range spheres. By comparing 252 Cf-calibrated dose responses with reference values based on fluence-to-dose conversion coefficients, this paper presents recommendations for neutron field characterisation and appropriate correction factors for responses of conventional neutron dosemeters used in environments with high-energy neutrons. The correction depends on the estimated percentage of high-energy neutrons in the spectrum or the ratio between the measured responses of two Bonner spheres (the 4P6-8 extended-range sphere versus the 6'' standard sphere). (authors)

Neutron activation analysis at the Californium User Facility for Neutron Science

International Nuclear Information System (INIS)

Martin, R.C.; Smith, E.H.; Glasgow, D.C.; Jerde, E.A.; Marsh, D.L.; Zhao, L.

1997-12-01

The Californium User Facility (CUF) for Neutron Science has been established to provide 252 Cf-based neutron irradiation services and research capabilities including neutron activation analysis (NAA). A major advantage of the CUF is its accessibility and controlled experimental conditions compared with those of a reactor environment The CUF maintains the world's largest inventory of compact 252 Cf neutron sources. Neutron source intensities of ≤ 10 11 neutrons/s are available for irradiations within a contamination-free hot cell, capable of providing thermal and fast neutron fluxes exceeding 10 8 cm -2 s -1 at the sample. Total flux of ≥10 9 cm -2 s -1 is feasible for large-volume irradiation rabbits within the 252 Cf storage pool. Neutron and gamma transport calculations have been performed using the Monte Carlo transport code MCNP to estimate irradiation fluxes available for sample activation within the hot cell and storage pool and to design and optimize a prompt gamma NAA (PGNAA) configuration for large sample volumes. Confirmatory NAA irradiations have been performed within the pool. Gamma spectroscopy capabilities including PGNAA are being established within the CUF for sample analysis

A proposed experiment for studying the direct neutron-neutron interaction

International Nuclear Information System (INIS)

Hassan Fikry, A.R.; Maayouf, R.M.A.

1979-01-01

An experiment for studying the direct neutron-neutron interaction is suggested. The experiment is based on the combined use of an accelerator, e.g., an electron linear accelerator, together with a mobile pulsed reactor; or using a pulsed beam reactor together with a mobile neutron generator

Neutron spectrum for neutron capture therapy in boron

International Nuclear Information System (INIS)

Medina C, D.; Soto B, T. G.; Baltazar R, A.; Vega C, H. R.

2016-10-01

Glioblastoma multiforme is the most common and aggressive of brain tumors and is difficult to treat by surgery, chemotherapy or conventional radiation therapy. One treatment alternative is the Neutron Capture Therapy in Boron, which requires a beam modulated in neutron energy and a drug with 10 B able to be fixed in the tumor. When the patients head is exposed to the neutron beam, they are captured by the 10 B and produce a nucleus of 7 Li and an alpha particle whose energy is deposited in the cancer cells causing it to be destroyed without damaging the normal tissue. One of the problems associated with this therapy is to have an epithermal neutrons flux of the order of 10 9 n/cm 2 -sec, whereby irradiation channels of a nuclear research reactor are used. In this work using Monte Carlo methods, the neutron spectra obtained in the radial irradiation channel of the TRIGA Mark III reactor are calculated when inserting filters whose position and thickness have been modified. From the arrangements studied, we found that the Fe-Cd-Al-Cd polyethylene filter yielded a ratio between thermal and epithermal neutron fluxes of 0.006 that exceeded the recommended value (<0.05), and the dose due to the capture gamma rays is lower than the dose obtained with the other arrangements studied. (Author)

Polarized neutron spectrometer

International Nuclear Information System (INIS)

Abov, Yu.G.; Novitskij, V.V.; Alfimenkov, V.P.; Galinskij, E.M.; Mareev, Yu.D.; Pikel'ner, L.B.; Chernikov, A.N.; Lason', L.; Tsulaya, V.M.; Tsulaya, M.I.

2000-01-01

The polarized neutron spectrometer, intended for studying the interaction of polarized neutrons with nuclei and condensed media in the area of energies from thermal up to several electron-volt, is developed at the IBR-2 reactor (JINR, Dubna). Diffraction on the Co(92%)-Fe(8%) magnetized monocrystals is used for the neutron polarization and polarization analysis. The neutron polarization within the whole energy range equals ∼ 95% [ru

Evaluation of room-scattered neutrons at the JNC Tokai neutron reference field

Energy Technology Data Exchange (ETDEWEB)

Yoshida, Tadayoshi; Tsujimura, Norio [Japan Nuclear Cycle Development Inst., Tokai, Ibaraki (Japan). Tokai Works; Oyanagi, Katsumi [Japan Radiation Engineering Co., Ltd., Hitachi, Ibaraki (Japan)

2002-09-01

Neutron reference fields for calibrating neutron-measuring devices in JNC Tokai Works are produced by using radionuclide neutron sources, {sup 241}Am-Be and {sup 252}Cf sources. The reference field for calibration includes scattered neutrons from the material surrounding sources, wall, floor and ceiling of the irradiation room. It is, therefore, necessary to evaluate the scattered neutrons contribution and their energy spectra at reference points. Spectral measurements were performed with a set of Bonner multi-sphere spectrometers and the reference fields were characterized in terms of spectral composition and the fractions of room-scattered neutrons. In addition, two techniques stated in ISO 10647, the shadow-cone method and the polynomial fit method, for correcting the contributions from the room-scattered neutrons to the readings of neutron survey instruments were compared. It was found that the two methods gave an equivalent result within a deviation of 3.3% at a source-to-detector distance from 50cm to 500cm. (author)

Evaluation of room-scattered neutrons at the JNC Tokai neutron reference field

International Nuclear Information System (INIS)

Yoshida, Tadayoshi; Tsujimura, Norio

2002-01-01

Neutron reference fields for calibrating neutron-measuring devices in JNC Tokai Works are produced by using radionuclide neutron sources, 241 Am-Be and 252 Cf sources. The reference field for calibration includes scattered neutrons from the material surrounding sources, wall, floor and ceiling of the irradiation room. It is, therefore, necessary to evaluate the scattered neutrons contribution and their energy spectra at reference points. Spectral measurements were performed with a set of Bonner multi-sphere spectrometers and the reference fields were characterized in terms of spectral composition and the fractions of room-scattered neutrons. In addition, two techniques stated in ISO 10647, the shadow-cone method and the polynomial fit method, for correcting the contributions from the room-scattered neutrons to the readings of neutron survey instruments were compared. It was found that the two methods gave an equivalent result within a deviation of 3.3% at a source-to-detector distance from 50cm to 500cm. (author)

Utilization of low voltage D-T neutron generators in neutron physics studies

International Nuclear Information System (INIS)

Singkarat, S.

1995-01-01

In a small nuclear laboratory of a developing country a low voltage D-T neutron generator can be a very useful scientific apparatus. Such machines have been used successfully for more than 40 years in teaching and scientific research. The original continuous mode 150-kV D-T neutron generator has been modified to have also a capability of producing 2-ns pulsed neutrons. Together with a carefully designed 10 m long flight path collimator and shielding of a 25 cm diameter · 10 cm thick BC-501 neutron detector, the pulsing system was successfully used for measuring the double differential cross-section (DDX) of natural iron for 14.1-MeV neutron from the angle of 30 deg to 150 deg in 10 deg steps. In order to extend the utility of the generator, two methods for converting the almost monoenergetic 14-MeV neutrons to monoenergetic neutrons of lower energy were proposed and tested. Both designs used the neutron-proton interaction at a circular surface-of-revolution made of hydrocarbon materials. The first design is for a pulsed neutron generator and the second design is for an ordinary continuous mode generator. The latter method was successfully used to measure the scintillation light output of a 1.4 cm diameter spherical NE-213 scintillation detector. The neutron generator has also been used in the continuous search for improved neutron detection techniques. There is a proposal, based on Monte Carlo calculations, of using a scintillation fiber for a fast neutron spectrometer. Due to the slender shape of the fiber, the pattern of produced light gives a peak in the pulse height spectrum instead of the well-known rectangular-like distribution, when the fiber is bombarded end-on by a beam of 14-MeV neutrons. Experimental investigations were undertaken. Detailed investigations on the light transportation property of a short fiber were performed. The predicted peak has not yet been found but the fiber detector may be developed as a directional discrimination fast neutron

Pulsed neutron porosity logging system

International Nuclear Information System (INIS)

Smith, H.D. Jr.; Smith, M.P.; Schultz, W.E.

1978-01-01

An improved pulsed neutron porosity logging system is provided in the present invention. A logging tool provided with a 14 MeV pulsed neutron source, an epithermal neutron detector, and a fast neutron detector is moved through a borehole. Repetitive bursts of neutrons irradiate the earth formations and, during the bursts, the fast neutron population is sampled. During the interval between bursts the epithermal neutron population is sampled along with background gamma radiation due to lingering thermal neutrons. The fast and epithermal neutron population measurements are combined to provide a measurement of formation porosity

Application of imaging plate neutron detector to neutron radiography

CERN Document Server

Fujine, S; Kamata, M; Etoh, M

1999-01-01

As an imaging plate neutron detector (IP-ND) has been available for thermal neutron radiography (TNR) which has high resolution, high sensitivity and wide range, some basic characteristics of the IP-ND system were measured at the E-2 facility of the KUR. After basic performances of the IP were studied, images with high quality were obtained at a neutron fluence of 2 to 7x10 sup 8 n cm sup - sup 2. It was found that the IP-ND system with Gd sub 2 O sub 3 as a neutron converter material has a higher sensitivity to gamma-ray than that of a conventional film method. As a successful example, clear radiographs of the flat view for the fuel side plates with boron burnable poison were obtained. An application of the IP-ND system to neutron radiography (NR) is presented in this paper.

METHODS OF ASSESSMENT OF THE RELATIVE BIOLOGICAL EFFECTIVENESS OF NEUTRONS IN NEUTRON THERAPY

Directory of Open Access Journals (Sweden)

V. A. Lisin

2017-01-01

Full Text Available The relative biological effectiveness (RBE of fast neutrons is an important factor influencing the quality of neutron therapy therefore, the assessment of RBE is of great importance. Experimental and clinical studies as well as different mathematical and radiobiological models are used for assessing RBE. Research is conducted for neutron sources differing in the method of producing particles, energy and energy spectrum. Purpose: to find and analyze the dose-dependence of fast neutron RBE in neutron therapy using the U-120 cyclotron and NG-12I generator. Material and methods: The optimal method for assessing the relative biological effectiveness of neutrons for neutron therapy was described. To analyze the dependence of the RBE on neutron dose, the multi-target model of cell survival was applied. Results: The dependence of the RBE of neutrons produced from the U-120 cyclotron and NG-120 generator on the dose level was found for a single irradiation of biological objects. It was shown that the function of neutron dose was consistent with similar dependencies found by other authors in the experimental and clinical studies.

The “neutron channel design”—A method for gaining the desired neutrons

Directory of Open Access Journals (Sweden)

G. Hu

2016-12-01

Full Text Available The neutrons with desired parameters can be obtained after initial neutrons penetrating various structure and component of the material. A novel method, the “neutron channel design”, is proposed in this investigation for gaining the desired neutrons. It is established by employing genetic algorithm (GA combining with Monte Carlo software. This method is verified by obtaining 0.01eV to 1.0eV neutrons from the Compact Accelerator-driven Neutron Source (CANS. One layer polyethylene (PE moderator was designed and installed behind the beryllium target in CANS. The simulations and the experiment for detection the neutrons were carried out. The neutron spectrum at 500cm from the PE moderator was simulated by MCNP and PHITS software. The counts of 0.01eV to 1.0eV neutrons were simulated by MCNP and detected by the thermal neutron detector in the experiment. These data were compared and analyzed. Then this method is researched on designing the complex structure of PE and the composite material consisting of PE, lead and zirconium dioxide.

Applications of image plates in neutron radiography and neutron diffraction at BARC, Trombay

International Nuclear Information System (INIS)

Shaikh, A.M.

2013-01-01

Neutron radiography techniques based on Gd, Dy and In metallic foils and X-ray film have been used at this centre since early seventies for various NDT and R and D work in nuclear, defence and aerospace industries. In recent years use of photostimulated luminescence based phosphor imaging plate has been introduced in our work. This has enabled to achieve higher sensitivities and dynamic ranges of recording radiographs with acceptable spatial resolution. It also provides digital image information which is more convenient for quantitative evaluations. Neutron image plates have been used in variety of radiography techniques such as conventional neutron radiography (NR), neutron induced beta radiography (NIBR), hydrogen sensitive epithermal neutron radiography (HYSEN) and for neutron powder diffractometry using Apsara, CIRUS and Dhruva reactors as neutron sources. Recently the image plates have also been used for characterization of thermalized neutron beam from a plasma focus neutron source and recording neutron radiographs. Prior to the utilization image plates have been characterised for their performance. Details of the measurements and applications will be presented. (author)

Neutrons in biology

International Nuclear Information System (INIS)

Funahashi, Satoru; Niimura, Nobuo.

1993-01-01

The start of JRR-3M in 1990 was a great epoch to the neutron scattering research in Japan. Abundant neutron beam generated by the JRR-3M made it possible to widen the research field of neutron scattering in Japan. In the early days of neutron scattering, biological materials were too difficult object to be studied by neutrons not only because of their complexity but also because of the strong incoherent scattering by hydrogen. However, the remarkable development of the recent neutron scattering and its related sciences, as well as the availability of higher flux, has made the biological materials one of the most attractive subjects to be studied by neutrons. In early September 1992, an intensive workshop titled 'Neutrons in Biology' was held in Hitachi City by making use of the opportunity of the 4th International Conference on Biophysics and Synchrotron Radiation (BSR92) held in Tsukuba. The workshop was organized by volunteers who are eager to develop the researches in this field in Japan. Numbers of outstanding neutron scattering biologists from U.S., Europe and Asian countries met together and enthusiastic discussions were held all day long. The editors believe that the presentations at the workshop were so invaluable that it is absolutely adequate to put them on record as an issue of JAERI-M and to make them available for scientists to refer to in order to further promote the research in the future. (author)

Study on neutron beam probe. Study on the focused neutron beam

Energy Technology Data Exchange (ETDEWEB)

Kotajima, Kyuya; Suzuki, K.; Fujisawa, M.; Takahashi, T.; Sakamoto, I. [Tohoku Univ., Sendai (Japan). Faculty of Engineering; Wakabayashi, T.

1998-03-01

A monoenergetic focused neutron beam has been produced by utilizing the endoenergetic heavy ion reactions on hydrogen. To realize this, the projectile heavy ion energy should be taken slightly above the threshold energy, so that the excess energy converted to the neutron energy should be very small. In order to improve the capability of the focused neutron beam, some hydrogen stored metal targets have also been tested. Separating the secondary heavy ions (associated particles) from the primary ions (accelerated particles) by using a dipole magnet, a rf separator, and a particle identification system, we could directly count the produced neutrons. This will leads us to the possibility of realizing the standard neutron field which had been the empty dream of many neutron-related researchers in the world. (author)

Neutron flux monitor

International Nuclear Information System (INIS)

Oda, Naotaka.

1993-01-01

The device of the present invention greatly saves an analog processing section such as an analog filter and an analog processing circuit. That is, the device of the present invention comprises (1) a neutron flux detection means for detecting neutron fluxed in the reactor, (2) a digital filter means for dividing signals corresponding to the detected neutron fluxes into predetermined frequency band regions, (3) a calculation processing means for applying a calculation processing corresponding to the frequency band regions to the neutron flux detection signals divided by the digital filter means. With such a constitution, since the neutron detection signals are processed by the digital filter means, the accuracy is improved and the change for the property of the filter is facilitated. Further, when a neutron flux level is obtained, a calculation processing corresponding to the frequency band region can be conducted without the analog processing circuit. Accordingly, maintenance and accuracy are improved by greatly decreasing the number of parts. Further, since problems inherent to the analog circuit are solved, neutron fluxes are monitored at high reliability. (I.S.)

A long neutron optical horn for the ILL neutron-antineutron oscillation experiment

International Nuclear Information System (INIS)

Bitter, T.; Eisert, F.; El-Muzeini, P.; Kessler, M.; Klemt, E.; Lippert, W.; Meienburg, W.; Dubbers, D.

1992-01-01

In the neutron-antineutron oscillation experiment at ILL the divergence of the free flying cold neutron beam was strongly reduced without loss of intensity by the use of a 34 m long neutron-optical horn system. The divergence reduction was accurately studied in order to maintain the total width of the neutron beam below 1.1 m after a neutron free flight distance of about 80 m. The fabrication and performance of this system are described. (orig.)

Activation neutron detector

International Nuclear Information System (INIS)

Ambardanishvili, T.S.; Kolomiitsev, M.A.; Zakharina, T.Y.; Dundua, V.J.; Chikhladze, N.V.

1976-01-01

An activation neutron detector made as a moulded and cured composition of a material capable of being neutron-activated is described. The material is selected from a group consisting of at least two chemical elements, a compound of at least two chemical elements and their mixture, each of the chemical elements and their mixture, each of the chemical elements being capable of interacting with neutrons to form radioactive isotopes having different radiation energies when disintegrating. The material capable of being neutron-activated is distributed throughout the volume of a polycondensation resin inert with respect to neutrons and capable of curing. 17 Claims, No Drawings

Neutron fluence measurement in nuclear facilities.; Medicion de flujos de neutrones en instalaciones nucleares.

Energy Technology Data Exchange (ETDEWEB)

Camacho L, M E

1997-12-01

The objective of present work is to determine the fluence of neutrons in nuclear facilities using two neutron detectors designed and built at Instituto Nacional de Investigaciones Nucleares (ININ), Mexico. The two neutron detectors are of the passive type, based on solid state nuclear tracks detectors (SSNTD). One of the two neutron detectors was used to determine the fluence distribution of the ports at the nuclear research reactor TRIGA Mark III, which belongs to ININ. In these facilities is important to know the neutron fluence distribution characteristic to carried out diverse kind of research activities. The second neutron detector was employed in order to carry out environmental neutron surveillance. The detector has the property to separate the thermal, intermediate and fast components of the neutron fluence. This detector was used to measure the neutron fluence at hundred points around the primary container of the first Mexican Nuclear Power plant `Laguna Verde`. This last detector was also used to determine the neutron fluence in some points of interest, around and inside a low scattering neutron room at the `Centro de Metrologia de Radiaciones Ionizantes` of the ININ, to know the background neutron field produced by the neutron sources used there. The design of the two neutron detector and the results obtained for each of the surveying facilities, are described in this work. (Author).

Methods of neutron spectrometry

International Nuclear Information System (INIS)

Doerschel, B.

1981-01-01

The different methods of neutron spectrometry are based on the direct measurement of neutron velocity or on the use of suitable energy-dependent interaction processes. In the latter case the measuring effect of a detector is connected with the searched neutron spectrum by an integral equation. The solution needs suitable unfolding procedures. The most important methods of neutron spectrometry are the time-of-flight method, the crystal spectrometry, the neutron spectrometry by use of elastic collisions with hydrogen nuclei, and neutron spectrometry with the aid of nuclear reactions, especially of the neutron-induced activation. The advantages and disadvantages of these methods are contrasted considering the resolution, the measurable energy range, the sensitivity, and the experimental and computational efforts. (author)

Extraction of neutron-neutron scattering length from nn coincidence-geometry nd breakup data

Directory of Open Access Journals (Sweden)

E. S. Konobeevski

2011-03-01

Full Text Available We report preliminary results of a kinematically complete experiment on measurement of nd breakup reaction yield at neutron beam RADEX of Institute for Nuclear Research (Moscow, Russia. In the experiment two secondary neutrons are detected in geometry of neutron-neutron final-state interaction. Data are obtained at energy of incident neutrons En = 40 - 60 MeV for various divergence angles of two neutrons ΔΘ = 4, 6, 8º. 1S0 neutron-neutron scattering length ann were determined by comparison of the experimental dependence of reaction yield on the relative energy of two secondary neutrons with results of simulation depending on ann. For En = 40 MeV and ΔΘ = 6º (the highest statistics in the experiment the value ann = -17.9 ± 1.0 fm is obtained. The further improving of accuracy of the experiment and more rigorous theoretical analysis will allow one to remove the existing difference in ann values obtained in different experiments.

Subcritical Neutron Multiplication Measurements of HEU Using Delayed Neutrons as the Driving Source

International Nuclear Information System (INIS)

Hollas, C.L.; Goulding, C.A.; Myers, W.L.

1999-01-01

A new method for the determination of the multiplication of highly enriched uranium systems is presented. The method uses delayed neutrons to drive the HEU system. These delayed neutrons are from fission events induced by a pulsed 14-MeV neutron source. Between pulses, neutrons are detected within a medium efficiency neutron detector using 3 He ionization tubes within polyethylene enclosures. The neutron detection times are recorded relative to the initiation of the 14-MeV neutron pulse, and subsequently analyzed with the Feynman reduced variance method to extract singles, doubles and triples neutron counting rates. Measurements have been made on a set of nested hollow spheres of 93% enriched uranium, with mass values from 3.86 kg to 21.48 kg. The singles, doubles and triples counting rates for each uranium system are compared to calculations from point kinetics models of neutron multiplicity to assign multiplication values. These multiplication values are compared to those from MC NP K-Code calculations

A neutron activation detector

International Nuclear Information System (INIS)

Ambardanishvili, T.S.; Kolomiitsev, M.A.; Zakharina, T.Y.; Dundua, V.J.; Chikhladze, N.V.

1973-01-01

The present invention concerns a neutron activation detector made from a moulded and hardened composition. According to the invention, that composition contains an activable substance constituted by at least two chemical elements and/or compounds of at least two chemical elements. Each of these chemical elements is capable of reacting with the neutrons forming radio-active isotopes with vatious levels of energy during desintegration. This neutron detector is mainly suitable for measuring integral thermal neutron and fast neutron fluxes during irradiation of the sample, and also for measuring the intensities of neutron fields [fr

Layered semiconductor neutron detectors

Science.gov (United States)

Mao, Samuel S; Perry, Dale L

2013-12-10

Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

Neutron Scattering Software

Science.gov (United States)

Home Page | Facilities | Reference | Software | Conferences | Announcements | Mailing Lists Neutron Scattering Banner Neutron Scattering Software A new portal for neutron scattering has just been established sets KUPLOT: data plotting and fitting software ILL/TAS: Matlab probrams for analyzing triple axis data

A Wide Spectrum Neutron Polarizer for a Pulsed Neutron Source

International Nuclear Information System (INIS)

Nikitenko, Yu.V.

1994-01-01

A wide spectrum neutron polarizer for a pulsed neutron source is considered. The polarizer is made in a form of a set of magnetized mirrors placed on a drum. Homogeneous rotation of the polarizer is synchronized with the power pulses of the neutron source. The polarizer may be utilized in a collimated neutron beam with cross section of the order of magnitude of 100 cm 2 within a wavelength from 2 up to 20 A on sources with a pulse repetition frequency up to 50 Hz. (author). 5 refs.; 3 figs

Evaluation of area monitor response for neutrons in radiation field generated by a 15 MV clinic accelerator; Avaliacao da resposta dos monitores de area para neutrons em campo de radiacao gerado por um acelerador clinico de 15 MV

Energy Technology Data Exchange (ETDEWEB)

Salgado, Ana Paula

2011-07-01

The clinical importance and usage of linear accelerators in cancer treatment increased significantly in the last years. Coupled with this growth came the concern about the use of accelerators with energies over to 10 MeV which produce therapeutic beam contaminated with neutrons generated when high-energy photons interact with high-atomic-number materials such as tungsten and lead present in the accelerator itself. At these facilities, measurements of the ambient dose equivalent for neutrons present difficulties owing to the existence of a mixed radiation field and possible electromagnetic interference near the accelerator. The Neutron Laboratory of the IRD - Brazilian Institute for Radioprotection and Dosimetry, aiming to evaluate the survey meters performance at these facilities, initiated studies of instrumentation response in the presence of different neutron spectra. Neutrons sources with average energies ranging from 0.55 to 4.2 MeV, four different survey meters and one ionization chamber to obtain the ratio between the dose due to neutrons and gamma radiation were used in this work. The evaluation of these measurements, performed in a 15 MV linear accelerator room is presented. This work presents results that demonstrate the complexity and care needed to make neutrons measurements in radiotherapy treatment rooms containing high energy clinical accelerators. (author)

Neutron activation system for spectral measurements of pulsed ion diode neutron production

International Nuclear Information System (INIS)

Hanson, D.L.; Kruse, L.W.

1980-02-01

A neutron energy spectrometer has been developed to study intense ion beam-target interactions in the harsh radiation environment of a relativistic electron beam source. The main component is a neutron threshold activation system employing two multiplexed high efficiency Ge(Li) detectors, an annihilation gamma coincidence system, and a pneumatic sample transport. Additional constraints on the neutron spectrum are provided by total neutron yield and time-of-flight measurements. A practical lower limit on the total neutron yield into 4π required for a spectral measurement with this system is approx. 10 10 n where the neutron yield is predominantly below 4 MeV and approx. 10 8 n when a significant fraction of the yield is above 4 MeV. Applications of this system to pulsed ion diode neutron production experiments on Hermes II are described

Neutron spectra characteristics for the intense neutron source, INS

International Nuclear Information System (INIS)

Battat, M.; Dierckx, R.; Emigh, C.R.

1977-01-01

The Intense Neutron Source, INS, facility is presently under construction at the Los Alamos Scientific Laboratory. Its purpose is to provide a broad base for research work related to the radiation effects produced by 14-MeV neutrons from a D-T burn of a fusion reactor. The INS facility produces a D-T burn-like reaction from the collision of an intense tritium-ion beam with a supersonic jet target of deuterium gas. The reaction produces a typical D-T 14-MeV neutron spectrum. By adding a fission blanket surrounding the D-T ''burn,'' the neutron spectral shape may be tailored to match almost perfectly the anticipated first-wall spectra from presently proposed fusion reactors. With a blanket in place, the total production of neutrons can be as large as 3 x 10 16 n/s and experimental volumes of the order of 1000 cm 3 can be available at flux levels greater than 0.6 x 10 14 n/cm 2 s

Basics of Neutrons for First Responders

Energy Technology Data Exchange (ETDEWEB)

Rees, Brian G. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2018-02-05

These are slides from a presentation on the basics of neutrons. A few topics covered are: common origins of terrestrial neutron radiation, neutron sources, neutron energy, interactions, detecting neutrons, gammas from neutron interactions, neutron signatures in gamma-ray spectra, neutrons and NaI, neutron fluence to dose (msV), instruments' response to neutrons.

Real time neutron flux monitoring using Rh self powered neutron detector

Energy Technology Data Exchange (ETDEWEB)

Juna, Byung Jin; Lee, Byung Chul; Park, Sang Jun; Jung, Hoan Sung [KAERI, Daejeon (Korea, Republic of)

2012-10-15

Rhodium (Rh) self powered neutron detectors (SPNDs) are widely used for on line monitoring of local neutron flux. Its signal is slower than the actual variation of neutron flux owing to a delayed {beta} decay of the Rh activation product, but real time monitoring is possible by solving equations between the neutron reaction rate in the detector and its signal. While the measuring system is highly reliable, the accuracy depends on the method solving the equations and accuracy of the parameters in the equations. The uncertain parameters are the contribution of gamma rays to the signal, and the branching ratios of Rh 104 and Rh 104m after the neutron absorption of Rh 103. Real time neutron flux monitoring using Rh SPNDs has been quite successful for neutron transmutation doping (NTD) at HANARO. We revisited the initial data used for the verification of a real time monitoring system, to refine algorithm for a better solution and to check the parameters for correctness. As a result, we suggest an effective way to determine the prompt parameter.

Real time neutron flux monitoring using Rh self powered neutron detector

International Nuclear Information System (INIS)

Juna, Byung Jin; Lee, Byung Chul; Park, Sang Jun; Jung, Hoan Sung

2012-01-01

Rhodium (Rh) self powered neutron detectors (SPNDs) are widely used for on line monitoring of local neutron flux. Its signal is slower than the actual variation of neutron flux owing to a delayed β decay of the Rh activation product, but real time monitoring is possible by solving equations between the neutron reaction rate in the detector and its signal. While the measuring system is highly reliable, the accuracy depends on the method solving the equations and accuracy of the parameters in the equations. The uncertain parameters are the contribution of gamma rays to the signal, and the branching ratios of Rh 104 and Rh 104m after the neutron absorption of Rh 103. Real time neutron flux monitoring using Rh SPNDs has been quite successful for neutron transmutation doping (NTD) at HANARO. We revisited the initial data used for the verification of a real time monitoring system, to refine algorithm for a better solution and to check the parameters for correctness. As a result, we suggest an effective way to determine the prompt parameter

Evaluation of saving measurements and energetic efficiency in air-conditioning systems; Evaluacion de medidas de ahorro y eficiencia energetica en sistemas de climatizacion

Energy Technology Data Exchange (ETDEWEB)

Perez Lombard, L [Asociacion de Investigacion y Cooperacion de Andalucia (Spain); Ortiz, J [Building Research Establishment (United Kingdom); Riviere, P [Armines-ecole des mines de Paris (France)

2006-04-15

Buildings require an adequate air conditioning to offer workers a labor environment where there is thermal comfort. A study was performed in three different European places which count on several climates. The conclusion was the following: in order to analyze the energy efficiency in edifications it is fundamental the simulation tools use with the purpose of calculating the consumption and evaluating the saving measurements. [Spanish] Los edificios requieren de una climatizacion adecuada para que los que ahi operan puedan hacerlo dentro de un ambiente laboral donde exista el confort termico. Se llevo a cabo un estudio en tres lugares de Europa poseedores de diferentes climas y se concluyo que para poder analizar la eficiencia energetica de climatizacion en las edificaciones es imprescindible el uso de herramientas de simulacion con el proposito de calcular el consumo y evaluar las medidas de ahorro.

Neutron therapy

International Nuclear Information System (INIS)

Riesler, Rudi

1995-01-01

Standard radiotherapy uses Xrays or electrons which have low LET (linear energy transfer); in contrast, particles such as neutrons with high LET have different radiobiological responses. In the late 1960s, clinical trials by Mary Catterall at the Hammersmith Hospital in London indicated that fast neutron radiation had clinical advantages for certain malignant tumours. Following these early clinical trials, several cyclotron facilities were built in the 1980s for fast neutron therapy, for example at the University of Washington, Seattle, and at UCLA. Most of these newer machines use extracted cyclotron proton beams in the range 42 to 66 MeV with beam intensities of 15 to 60 microamps. The proton beams are transported to dedicated therapy rooms, where neutrons are produced from beryllium targets. Second-generation clinical trials showed that accurate neutron beam delivery to the tumour site is more critical than for photon therapy. In order to achieve precise beam geometries, the extracted proton beams have to be transported through a gantry which can rotate around the patient and deliver beams from any angle; also the neutron beam outline (''field shape'') must be adjusted to extremely irregular shapes using a flexible collimation system. A therapy procedure has to be appropriately organized, with physicians, radiotherapists, nurses, medical physicists and other staff in attendance; other specialized equipment, such as CT or MRI scanners and radiation simulators must be made available. Neutron therapy is usually performed only in radiation oncology departments of major medical centres

Polarimetric neutron scattering

International Nuclear Information System (INIS)

Tasset, F.

2001-01-01

Polarimetric Neutron Scattering in introduced, both by, explaining methodological issues and the corresponding instrumental developments. After a short overview of neutron spin polarization and the neutron polarization 3d-vector a pictorial approach of the microscopic theory is used to show how a polarized beam interacts with lattice and magnetic Fourier components in a crystal. Examples are given of using Spherical Neutron Polarimetry (SNP) and the corresponding Cryopad polarimeter for the investigation of non-collinear magnetic structures. (R.P.)

Neutron kinetics in moderators and SNM detection through epithermal-neutron-induced fissions

Energy Technology Data Exchange (ETDEWEB)

Gozani, Tsahi, E-mail: tgmaven@gmail.com [1050 Harriet St., Palo Alto, CA 94301 (United States); King, Michael J. [Rapiscan Laboratories Inc., 520 Almanor Ave., Sunnyvale, CA 94085 (United States)

2016-01-01

Extension of the well-established Differential Die Away Analysis (DDAA) into a faster time domain, where more penetrating epithermal neutrons induce fissions, is proposed and demonstrated via simulations and experiments. In the proposed method the fissions stimulated by thermal, epithermal and even higher-energy neutrons are measured after injection of a narrow pulse of high-energy 14 MeV (d,T) or 2.5 MeV (d,D) source neutrons, appropriately moderated. The ability to measure these fissions stems from the inherent correlation of neutron energy and time (“E–T” correlation) during the process of slowing down of high-energy source neutrons in common moderating materials such as hydrogenous compounds (e.g., polyethylene), heavy water, beryllium and graphite. The kinetic behavior following injection of a delta-function-shaped pulse (in time) of 14 MeV neutrons into such moderators is studied employing MCNPX simulations and, when applicable, some simple “one-group” models. These calculations served as a guide for the design of a source moderator which was used in experiments. Qualitative relationships between slowing-down time after the pulse and the prevailing neutron energy are discussed. A laboratory system consisting of a 14 MeV neutron generator, a polyethylene-reflected Be moderator, a liquid scintillator with pulse-shape discrimination (PSD) and a two-parameter E–T data acquisition system was set up to measure prompt neutron and delayed gamma-ray fission signatures in a 19.5% enriched LEU sample. The measured time behavior of thermal and epithermal neutron fission signals agreed well with the detailed simulations. The laboratory system can readily be redesigned and deployed as a mobile inspection system for SNM in, e.g., cars and vans. A strong pulsed neutron generator with narrow pulse (<75 ns) at a reasonably high pulse frequency could make the high-energy neutron induced fission modality a realizable SNM detection technique.

Generation of neutron standing waves at total reflection of polarized neutrons

International Nuclear Information System (INIS)

Aksenov, V.L.; Nikitenko, Yu.V.; Kozhevnikov, S.V.; Radu, F.; Kruijs, R.; Rekveldt, M.Th.

1999-01-01

The regime of neutron standing waves at reflection of polarized thermal neutrons from the structure glass/Cu (1000 A Angstrom)/Ti (2000 A Angstrom)/Co (60 A Angstrom)/Ti (300 A Angstrom) in a magnetic field directed at an angle to the sample plane is realized. The intensity of neutrons with a particular spin projection on the external magnetic field direction appears to be a periodic function of the neutron wavelength and the glancing angle of the reflected beam. It is shown that the neutron standing wave regime can be a very sensitive method for the determination of changes in the spatial position of magnetic noncollinear layers. (author)

A neutron calibration technique for detectors with low neutron/high photon sensitivity

International Nuclear Information System (INIS)

Jahr, R.; Guldbakke, S.; Cosack, M.; Dietze, G.; Klein, H.

1978-03-01

The neutron response of a detector with low neutron-/high photon sensitivity is given by the difference of two terms: the response to the mixed neutron-photon field, measured directly, and the response to the photons, deduced from additional measurements with a photon spectrometer. The technique is particularly suited for use in connection with targets which consist of a thick backing and thin layer of neutron producing material such as T, D, Li nuclei. Then the photon component of the mixed field is very nearly the same as the pure photon field from a 'phantom target', being identical with the neutron producing target except for the missing neutron producing material. Using this technique in connection with a T target (Ti-T-layer on silver backing) and the corresponding phantom target (Ti-layer on silver backing), a GM counter was calibrated at a neutron energy of 2.5 MeV. Possibilities are discussed to subsequently calibrate the GM counter at other neutron energies without the use of the photon spectrometer. (orig./HP) [de

Neutron protection material and neutron protection devices made of such material

International Nuclear Information System (INIS)

Ries, W.

1984-01-01

This is concerned with a neutron protection material made of thermoplastic or thermosetting plastic from high molecule hydrocarbon compounds with particularly high hydrogen and carbon contents as braking or shielding material (moderator) for fast neutrons. The plastic can contain boron for absorbing low energy neutrons. The material is used to manufacture foil, plates, pipes, shielding walls, components, bodies for radiation protection equipment, devices and plant and for neutron protection clothes. (orig./HP) [de

Neutron radiography of thick hydrogenous materials with use of an imaging plate neutron detector

International Nuclear Information System (INIS)

Kato, K.; Matsumoto, G.; Karasawa, Y.; Niimura, N.; Matsubayashi, M.; Tsuruno, A.

1996-01-01

The value of the neutron mass attenuation coefficient of hydrogen being very high, it is extremely difficult to image normal size, living animals with neutron radiography. However, the authors suggest the possibility of applying neutron radiography for biomedical specimens. The organs in the breast, bones and cartilages in the extremities, and the tail of mice and rats were clearly imaged by neutron radiography with Gd foils as neutron converters and X-ray films. However, no contours of the organs in the mouse abdomen were visible with neutron radiography with an exposure time of 200 s. By adding Gd or Li compounds as neutron converters to imaging X-ray plates, imaging plates have been developed for neutron detectors. A trial using these imaging plates for neutron radiography of water-filled containers and the abdomen of mice was completed. The roundness of a 100 ml-beaker was imaged with a neutron exposure of 180 s. Obscure contours of the liver and kidneys of the mouse were imaged with a neutron exposure of 100 s. (orig.)

Pulsed thermal neutron source at the fast neutron generator.

Science.gov (United States)

Tracz, Grzegorz; Drozdowicz, Krzysztof; Gabańska, Barbara; Krynicka, Ewa

2009-06-01

A small pulsed thermal neutron source has been designed based on results of the MCNP simulations of the thermalization of 14 MeV neutrons in a cluster-moderator which consists of small moderating cells decoupled by an absorber. Optimum dimensions of the single cell and of the whole cluster have been selected, considering the thermal neutron intensity and the short decay time of the thermal neutron flux. The source has been built and the test experiments have been performed. To ensure the response is not due to the choice of target for the experiments, calculations have been done to demonstrate the response is valid regardless of the thermalization properties of the target.

Design progress of cryogenic hydrogen system for China Spallation Neutron Source

Energy Technology Data Exchange (ETDEWEB)

Wang, G. P.; Zhang, Y.; Xiao, J.; He, C. C.; Ding, M. Y.; Wang, Y. Q.; Li, N.; He, K. [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, P.R. (China)

2014-01-29

China Spallation Neutron Source (CSNS) is a large proton accelerator research facility with 100 kW beam power. Construction started in October 2011 and is expected to last 6.5 years. The cryogenic hydrogen circulation is cooled by a helium refrigerator with cooling capacity of 2200 W at 20 K and provides supercritical hydrogen to neutron moderating system. Important progresses of CSNS cryogenic system were concluded as follows. Firstly, process design of cryogenic system has been completed including helium refrigerator, hydrogen loop, gas distribution, and safety interlock. Secondly, an accumulator prototype was designed to mitigate pressure fluctuation caused by dynamic heat load from neutron moderation. Performance test of the accumulator has been carried out at room and liquid nitrogen temperature. Results show the accumulator with welding bellows regulates hydrogen pressure well. Parameters of key equipment have been identified. The contract for the helium refrigerator has been signed. Mechanical design of the hydrogen cold box has been completed, and the hydrogen pump, ortho-para hydrogen convertor, helium-hydrogen heat exchanger, hydrogen heater, and cryogenic valves are in procurement. Finally, Hydrogen safety interlock has been finished as well, including the logic of gas distribution, vacuum, hydrogen leakage and ventilation. Generally, design and construction of CSNS cryogenic system is conducted as expected.

Utilization of low voltage D-T neutron generators in neutron physics studies

Energy Technology Data Exchange (ETDEWEB)

Singkarat, S.

1995-08-01

In a small nuclear laboratory of a developing country a low voltage D-T neutron generator can be a very useful scientific apparatus. Such machines have been used successfully for more than 40 years in teaching and scientific research. The original continuous mode 150-kV D-T neutron generator has been modified to have also a capability of producing 2-ns pulsed neutrons. Together with a carefully designed 10 m long flight path collimator and shielding of a 25 cm diameter {center_dot} 10 cm thick BC-501 neutron detector, the pulsing system was successfully used for measuring the double differential cross-section (DDX) of natural iron for 14.1-MeV neutron from the angle of 30 deg to 150 deg in 10 deg steps. In order to extend the utility of the generator, two methods for converting the almost monoenergetic 14-MeV neutrons to monoenergetic neutrons of lower energy were proposed and tested. The first method uses a pulsed neutron generator and the second method uses an ordinary continuous mode generator. The latter method was successfully used to measure the scintillation light output of a 1.4 cm diameter spherical NE-213 scintillation detector. The neutron generator has also been used in the continuous search for improved neutron detection techniques. There is a proposal, based on Monte Carlo calculations, of using a scintillation fiber for a fast neutron spectrometer. Due to the slender shape of the fiber, the pattern of produced light gives a peak in the pulse height spectrum instead of the well-known rectangular-like distribution, when the fiber is bombarded end-on by a beam of 14-MeV neutrons. Experimental investigations were undertaken. Detailed investigations on the light transportation property of a short fiber were performed. The predicted peak has not yet been found but the fiber detector may be developed as a directional discrimination fast neutron detector. 18 refs.

Fusion neutron detector calibration using a table-top laser generated plasma neutron source

International Nuclear Information System (INIS)

Hartke, R.; Symes, D.R.; Buersgens, F.; Ruggles, L.E.; Porter, J.L.; Ditmire, T.

2005-01-01

Using a high intensity, femtosecond laser driven neutron source, a high-sensitivity neutron detector was calibrated. This detector is designed for observing fusion neutrons at the Z accelerator in Sandia National Laboratories. Nuclear fusion from laser driven deuterium cluster explosions was used to generate a clean source of nearly monoenergetic 2.45 MeV neutrons at a well-defined time. This source can run at 10 Hz and was used to build up a clean pulse-height spectrum on scintillating neutron detectors giving a very accurate calibration for neutron yields at 2.45 MeV

Neutron image intensifier tubes

International Nuclear Information System (INIS)

Verat, M.; Rougeot, H.; Driard, B.

1983-01-01

The most frequently used techniques in neutron radiography employ a neutron converter consisting of either a scintillator or a thin metal sheet. The radiation created by the neutrons exposes a photographic film that is in contact with the converter: in the direct method, the film is exposed during the time that the object is irradiated with neutrons; in the transfer method, the film is exposed after the irradiation of the object with neutrons. In industrial non-destructive testing, when many identical objects have to be checked, these techniques have several disadvantages. Non-destructive testing systems without these disadvantages can be constructed around neutron-image intensifier tubes. A description and the operating characteristics of neutron-image intensifier tubes are given. (Auth.)

Neutron multiplicity measurements with ³He alternative: Straw neutron detectors

Energy Technology Data Exchange (ETDEWEB)

Mukhopadhyay, Sanjoy [Arnold Avenue Andrews AFB, Joint Base Andrews, MD (United States); Wolff, Ronald [Arnold Avenue Andrews AFB, Joint Base Andrews, MD (United States); Detwiler, Ryan [Arnold Avenue Andrews AFB, Joint Base Andrews, MD (United States); Maurer, Richard [Arnold Avenue Andrews AFB, Joint Base Andrews, MD (United States); Mitchell, Stephen [National Security Technologies, LLC, Las Vegas, NV (United States); Guss, Paul [Remote Sensing Lab. - Nellis, Las Vegas, NV (United States); Lacy, Jeffrey L. [Proportional Technologies, Inc., Houston, TX (United States); Sun, Liang [Proportional Technologies, Inc., Houston, TX (United States); Athanasiades, Athanasios [Proportional Technologies, Inc., Houston, TX (United States)

2015-01-27

Counting neutrons emitted by special nuclear material (SNM) and differentiating them from the background neutrons of various origins is the most effective passive means of detecting SNM. Unfortunately, neutron detection, counting, and partitioning in a maritime environment are complex due to the presence of high-multiplicity spallation neutrons (commonly known as ‘‘ship effect ’’) and to the complicated nature of the neutron scattering in that environment. A prototype neutron detector was built using ¹⁰B as the converter in a special form factor called ‘‘straws’’ that would address the above problems by looking into the details of multiplicity distributions of neutrons originating from a fissioning source. This paper describes the straw neutron multiplicity counter (NMC) and assesses the performance with those of a commercially available fission meter. The prototype straw neutron detector provides a large-area, efficient, lightweight, more granular (than fission meter) neutron-responsive detection surface (to facilitate imaging) to enhance the ease of application of fission meters. Presented here are the results of preliminary investigations, modeling, and engineering considerations leading to the construction of this prototype. This design is capable of multiplicity and Feynman variance measurements. This prototype may lead to a near-term solution to the crisis that has arisen from the global scarcity of ³He by offering a viable alternative to fission meters. This paper describes the work performed during a 2-year site-directed research and development (SDRD) project that incorporated straw detectors for neutron multiplicity counting. The NMC is a two-panel detector system. We used ¹⁰B (in the form of enriched boron carbide: ¹⁰B₄C) for neutron detection instead of ³He. In the first year, the project worked with a panel of straw neutron detectors, investigated its characteristics, and

Neutron dosimeters and survey meters in accelerators, reactors and other neutron environments

International Nuclear Information System (INIS)

1989-03-01

Neutron fields in occupationally accessible areas around nuclear reactors, radioisotope sources and medical and high energy accelerators have been characterized using currently available information. Neutron, rem meters, such as the Leake detector, are the most suitable instruments available for conducting neutron dose rate surveys in the vicinity of radioisotope neutron sources, nuclear reactors and medical accelerators. However, these instruments have been shown to be deficient in that they overrespond by a factor of four to neutrons in the 0.1 to 1 MeV range and are insensitive to neutrons from about 1 eV up to about 10 keV. Also, they are insensitive to neutrons above 20 MeV and their use must be restricted near high energy accelerators where significant numbers of neutrons above 20 MeV are known to be present. The most suitable instrument of measure dose from neutrons above 20 MeV is the 12 C(n,2n) 11 C scintillation chamber. Commercially available rem meters frequently use BF 3 counters in the pulse mode to detect thermal neutrons. Therefore, measurements around pulsed accelerators must be made with caution to ensure that the detector is not saturated during each pulse and that the accelerator pulse period is greater than the response time of the detector. The personal neutron dosimeters currently available either are known to be insensitive to neutrons above 20 MeV or have not been tested. Also, all except the albedo dosimeter are insensitive to or have not been tested for neutron energies in the range 1 eV to 10 keV. Several dosimeter types respond reasonably well to neutrons in the energy range 0.1 to 15 MeV, for example, CR-39, bubble and superheated drop detectors. However, the first gas a lower limit of sensitivity of about 0.3 mSv. The bubble detector can be designed to measure doses as small as 1μSv and offers the additional benefit of direct-reading capability. The superheated drop detector is not suitable for use around pulsed accelerators because

Neutron resonance spectroscopy

International Nuclear Information System (INIS)

Gunsing, F.

2005-06-01

The present document has been written in order to obtain the diploma 'Habilitation a Diriger des Recherches'. Since this diploma is indispensable to supervise thesis students, I had the intention to write a document that can be useful for someone starting in the field of neutron resonance spectroscopy. Although the here described topics are already described elsewhere, and often in more detail, it seemed useful to have most of the relevant information in a single document. A general introduction places the topic of neutron-nucleus interaction in a nuclear physics context. The large variations of several orders of magnitude in neutron-induced reaction cross sections are explained in terms of nuclear level excitations. The random character of the resonances make nuclear model calculation predictions impossible. Then several fields in physics where neutron-induced reactions are important and to which I have contributed in some way or another, are mentioned in a first synthetic chapter. They concern topics like parity nonconservation in certain neutron resonances, stellar nucleosynthesis by neutron capture, and data for nuclear energy applications. The latter item is especially important for the transmutation of nuclear waste and for alternative fuel cycles. Nuclear data libraries are also briefly mentioned. A second chapter details the R-matrix theory. This formalism is the foundation of the description of the neutron-nucleus interaction and is present in all fields of neutron resonance spectroscopy. (author)

Neutron dosimetry - A review

Energy Technology Data Exchange (ETDEWEB)

Baum, J W

1955-03-29

This review summarizes information on the following subjects: (1) physical processes of importance in neutron dosimetry; (2) biological effects of neutrons; (3) neutron sources; and (4) instruments and methods used in neutron dosimetry. Also, possible improvements in dosimetry instrumentation are outlined and discussed. (author)

Response of six neutron survey meters in mixed fields of fast and thermal neutrons.

Science.gov (United States)

Kim, S I; Kim, B H; Chang, I; Lee, J I; Kim, J L; Pradhan, A S

2013-10-01

Calibration neutron fields have been developed at KAERI (Korea Atomic Energy Research Institute) to study the responses of commonly used neutron survey meters in the presence of fast neutrons of energy around 10 MeV. The neutron fields were produced by using neutrons from the (241)Am-Be sources held in a graphite pile and a DT neutron generator. The spectral details and the ambient dose equivalent rates of the calibration fields were established, and the responses of six neutron survey meters were evaluated. Four single-moderator-based survey meters exhibited an under-responses ranging from ∼9 to 55 %. DINEUTRUN, commonly used in fields around nuclear reactors, exhibited an over-response by a factor of three in the thermal neutron field and an under-response of ∼85 % in the mixed fields. REM-500 (tissue-equivalent proportional counter) exhibited a response close to 1.0 in the fast neutron fields and an under-response of ∼50 % in the thermal neutron field.

Instrumentation with polarized neutrons

International Nuclear Information System (INIS)

Boeni, P.; Muenzer, W.; Ostermann, A.

2009-01-01

Neutron scattering with polarization analysis is an indispensable tool for the investigation of novel materials exhibiting electronic, magnetic, and orbital degrees of freedom. In addition, polarized neutrons are necessary for neutron spin precession techniques that path the way to obtain extremely high resolution in space and time. Last but not least, polarized neutrons are being used for fundamental studies as well as very recently for neutron imaging. Many years ago, neutron beam lines were simply adapted for polarized beam applications by adding polarizing elements leading usually to unacceptable losses in neutron intensity. Recently, an increasing number of beam lines are designed such that an optimum use of polarized neutrons is facilitated. In addition, marked progress has been obtained in the technology of 3 He polarizers and the reflectivity of large-m supermirrors. Therefore, if properly designed, only factors of approximately 2-3 in neutron intensity are lost. It is shown that S-benders provide neutron beams with an almost wavelength independent polarization. Using twin cavities, polarized beams with a homogeneous phase space and P>0.99 can be produced without significantly sacrificing intensity. It is argued that elliptic guides, which are coated with large m polarizing supermirrors, provide the highest flux.

Neutron producing reactions in PuBe neutron sources

Energy Technology Data Exchange (ETDEWEB)

Bagi, János [European Commission, Joint Research Centre (JRC), Institute for Transuranium Elements (ITU) (Germany); Lakosi, László; Nguyen, Cong Tam [Centre for Energy Research, Hungarian Academy of Sciences, Budapest (Hungary)

2016-01-01

There are a plenty of out-of-use plutonium–beryllium neutron sources in Eastern Europe presenting both nuclear safeguards and security issues. Typically, their actual Pu content is not known. In the last couple of years different non-destructive methods were developed for their characterization. For such methods detailed knowledge of the nuclear reactions taking place within the source is necessary. In this paper we investigate the role of the neutron producing reactions, their contribution to the neutron yield and their dependence on the properties of the source.

Neutrons at COSY

International Nuclear Information System (INIS)

Filges, D.; Freiesleben, H.

1988-05-01

For many years neutrons were considered important both as a useful probe in nuclear physics research and as an initiator and catalyst for fission, fusion and other applications. As a result knowledge about neutrons, especially below 20 MeV, received organized world-wide attention. Research with neutrons at medium energies, say 50 MeV to several GeV, has not consistently received attention and no systematic evaluations exist. But there is a large and considerable interest today because medium energy neutrons are very important in basic science and technology. The aim of this workshop was to provide an overview of the present status and the research which should be carried out in this field in future and which kind of experiments should be performed at the COSY facility: State-of-the-art about medium energy neutron experiments and existing facilities; planned experiments; needs for experiments doing research with neutrons at COSY (detectors, accelerator requirements, time structure etc.); what will be a first experiment to measure neutrons at COSY. The interest in this workshop is documented by a large number of participants. Copies of the viewgraphs of the talks are provided. (orig./HP)

Neutronic performance issues for the Spallation Neutron Source moderators

International Nuclear Information System (INIS)

Iverson, E.B.; Murphy, B.D.

2001-01-01

We continue to develop the neutronic models of the Spallation Neutron Source target station and moderators in order to better predict the neutronic performance of the system as a whole and in order to better optimize that performance. While we are not able to say that every model change leads to more intense neutron beams being predicted, we do feel that such changes are advantageous in either performance or in the accuracy of the prediction of performance. We have computationally and experimentally studied the neutronics of hydrogen-water composite moderators such as are proposed for the SNS Project. In performing these studies, we find that the composite moderator, at least in the configuration we have examined, does not provide performance characteristics desirable for the instruments proposed and being designed for this neutron scattering facility. The pulse width as a function of energy is significantly broader than for other moderators, limiting attainable resolution-bandwidth combinations. Furthermore, there is reason to expect that higher-energy (0.1-1 eV) applications will be significantly impacted by bimodal pulse shapes requiring enormous effort to parameterize. As a result of these studies, we have changed the SNS design, and will not use a composite moderator at this time. We have analyzed the depletion of a gadolinium poison plate in a hydrogen moderator at the Spallation Neutron Source, and found that conventional poison thicknesses will be completely unable to last the desired component lifetime of three operational years. A poison plate 300-600 μm thick will survive for the required length of time, but will somewhat degrade the intensity (by as much as 15% depending on neutron energy) and the consistency of the neutron source performance. Our results should scale fairly easily to other moderators on this or any other spallation source. While depletion will be important for all highly-absorbing materials in high-flux regions, we feel it likely that

Determination of radiation levels by neutrons in an accelerator for radiotherapy; Determinacion de niveles de radiacion por neutrones en un acelerador para radioterapia

Energy Technology Data Exchange (ETDEWEB)

Paredes G, L.; Salazar B, M.A. [Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, 11801 Mexico D.F. (Mexico); Genis S, R. [Fundacion Clinica Medica Sur, Puente de Piedra 150, Col. Torriello Guerra, Tlalpan 14050, Mexico D.F. (Mexico)

1998-12-31

It was determined the radiation levels by neutrons due to photonuclear reactions ({gamma}, n) which occur in the target, levelling filter, collimators and the small pillow blinding of a medical accelerator Varian Clinac 2100C of 18 MeV, using thermoluminescent dosemeters UD-802AS and US-809AS. The experimental values were presented for the patient level, inside and outside of the radiation field, as well as for the small pillow. (Author)

Isotopic neutron sources for neutron activation analysis

International Nuclear Information System (INIS)

Hoste, J.

1988-06-01

This User's Manual is an attempt to provide for teaching and training purposes, a series of well thought out demonstrative experiments in neutron activation analysis based on the utilization of an isotopic neutron source. In some cases, these ideas can be applied to solve practical analytical problems. 19 refs, figs and tabs

New opportunities in neutron capture research using advanced pulsed neutron sources

International Nuclear Information System (INIS)

Bowman, C.D.

1987-08-01

The extraordinary neutron intensities available from the new spallation pulsed neutron sources open up exciting opportunities for basic and applied research in neutron nuclear physics. Prospective experiments are reviewed with particular attention to those with a strong connection to capture gamma-ray spectroscopy

Use of a neutron guide in industrial neutron radiography

International Nuclear Information System (INIS)

Zaccheo, M.; Berthon, J.; Uzureau, G.; Laporte, A.

1983-01-01

This paper describes the neutron radiography facility associated with the Orphee high flux reactor at the Saclay Nuclear Research Centre. Following a brief background review, the paper deals with: the presentation of the facility, with emphasis on all the mechanical systems involved; description of the control and monitoring console; a non-exhaustive list of the facility's potentialities; the advantages and drawbacks of the use of a neutron guide to carry out industrial neutron radiography. (Auth.)

Neutron Detector Signal Processing to Calculate the Effective Neutron Multiplication Factor of Subcritical Assemblies

International Nuclear Information System (INIS)

Talamo, Alberto; Gohar, Yousry

2016-01-01

This report describes different methodologies to calculate the effective neutron multiplication factor of subcritical assemblies by processing the neutron detector signals using MATLAB scripts. The subcritical assembly can be driven either by a spontaneous fission neutron source (e.g. californium) or by a neutron source generated from the interactions of accelerated particles with target materials. In the latter case, when the particle accelerator operates in a pulsed mode, the signals are typically stored into two files. One file contains the time when neutron reactions occur and the other contains the times when the neutron pulses start. In both files, the time is given by an integer representing the number of time bins since the start of the counting. These signal files are used to construct the neutron count distribution from a single neutron pulse. The built-in functions of MATLAB are used to calculate the effective neutron multiplication factor through the application of the prompt decay fitting or the area method to the neutron count distribution. If the subcritical assembly is driven by a spontaneous fission neutron source, then the effective multiplication factor can be evaluated either using the prompt neutron decay constant obtained from Rossi or Feynman distributions or the Modified Source Multiplication (MSM) method.

Neutron Detector Signal Processing to Calculate the Effective Neutron Multiplication Factor of Subcritical Assemblies

Energy Technology Data Exchange (ETDEWEB)

Talamo, Alberto [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Gohar, Yousry [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division

2016-06-01

This report describes different methodologies to calculate the effective neutron multiplication factor of subcritical assemblies by processing the neutron detector signals using MATLAB scripts. The subcritical assembly can be driven either by a spontaneous fission neutron source (e.g. californium) or by a neutron source generated from the interactions of accelerated particles with target materials. In the latter case, when the particle accelerator operates in a pulsed mode, the signals are typically stored into two files. One file contains the time when neutron reactions occur and the other contains the times when the neutron pulses start. In both files, the time is given by an integer representing the number of time bins since the start of the counting. These signal files are used to construct the neutron count distribution from a single neutron pulse. The built-in functions of MATLAB are used to calculate the effective neutron multiplication factor through the application of the prompt decay fitting or the area method to the neutron count distribution. If the subcritical assembly is driven by a spontaneous fission neutron source, then the effective multiplication factor can be evaluated either using the prompt neutron decay constant obtained from Rossi or Feynman distributions or the Modified Source Multiplication (MSM) method.

New generation non-stationary portable neutron generators for biophysical applications of Neutron Activation Analysis.

Science.gov (United States)

Marchese, N; Cannuli, A; Caccamo, M T; Pace, C

2017-01-01

Neutron sources are increasingly employed in a wide range of research fields. For some specific purposes an alternative to existing large-scale neutron scattering facilities, can be offered by the new generation of portable neutron devices. This review reports an overview for such recently available neutron generators mainly addressed to biophysics applications with specific reference to portable non-stationary neutron generators applied in Neutron Activation Analysis (NAA). The review reports a description of a typical portable neutron generator set-up addressed to biophysics applications. New generation portable neutron devices, for some specific applications, can constitute an alternative to existing large-scale neutron scattering facilities. Deuterium-Deuterium pulsed neutron sources able to generate 2.5MeV neutrons, with a neutron yield of 1.0×10 6 n/s, a pulse rate of 250Hz to 20kHz and a duty factor varying from 5% to 100%, when combined with solid-state photon detectors, show that this kind of compact devices allow rapid and user-friendly elemental analysis. "This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo". Copyright © 2016 Elsevier B.V. All rights reserved.

LANSA: A large neutron scintillator array for neutron spectroscopy at Nova

International Nuclear Information System (INIS)

Nelson, M.B.; Cable, M.D.; Bennett, C.K.; Mant, G.

1992-01-01

A very sensitive neutron time-of-flight spectrometer is now in use at Nova. LANSA consists of 960 channels of a neutron sensitive liquid scintillator (10 x lO x lO cm) coupled to a photomultiplier tube followed by a discriminator, TDC and ADC to allow the measurement of neutron arrival time as well as pulse size. LANSA is capable of measuring yields as low as 2.3 x 10 5 DT neutrons (100 detected hits) with resolution of 2.3 ns (170 key for 14 MeV neutrons with 20 m flight path). Shielding and collimation provide background levels low enough to allow measurement of secondary and tertiary reaction neutrons. Details of design, testing, calibration and experimental results will be presented. This work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under contract No. W-7405-ENG-48

Neutron guides and scientific neutron equipment at CILAS/GMI

International Nuclear Information System (INIS)

Gautier-Picard, P.

2001-01-01

The French company CILAS is the world's leading supplier of complete neutron guide systems. The neutron optics with multilayer coatings produced by CILAS has become an international standard for neutron beam transportation at modern research institutes. During the last 30 years, CILAS designed, produced and installed more than 5000 meters of guides in many European, American and Asian countries. By these projects the company has acquired a very strong experience with: conception, design, manufacturing, setting up of Neutron Guides. In most cases, CILAS was in charge of the design, as well as the manufacturing of the whole system, comprising optical and mechanical components, vacuum system, shutter and shielding definition. By our long experience we have also acquired good knowledge of the materials used in this specific nuclear environment and their behavior under radiation such as glass, borated or not, coatings, glue or metal. To reinforce its leadership and presence in neutron research, CILAS acquired the company Grenoble Modular Instruments (GMI) a leading company in high precision mechanics, engineering and manufacturing of spectrometers and scientific equipment for neutron and synchrotron research. This merger allows us to design and to supply a complete range of high precision optical and mechanical eqipment for neutron research. CILAS and GMI have designed, manufactured and installed a High Resolution Powder Diffractometer for the 30MW Korean Hanaro Reactor. This project included the calculation, design and supply of the complete biological shielding of the instrument as well as for the primary beam shutter on the thermal beamport. (author)

Neutron-neutron quasifree scattering in nd breakup at 10 MeV

Science.gov (United States)

Malone, R. C.; Crowe, B.; Crowell, A. S.; Cumberbatch, L. C.; Esterline, J. H.; Fallin, B. A.; Friesen, F. Q. L.; Han, Z.; Howell, C. R.; Markoff, D.; Ticehurst, D.; Tornow, W.; Witała, H.

2016-03-01

The neutron-deuteron (nd) breakup reaction provides a rich environment for testing theoretical models of the neutron-neutron (nn) interaction. Current theoretical predictions based on rigorous ab-initio calculations agree well with most experimental data for this system, but there remain a few notable discrepancies. The cross section for nn quasifree (QFS) scattering is one such anomaly. Two recent experiments reported cross sections for this particular nd breakup configuration that exceed theoretical calculations by almost 20% at incident neutron energies of 26 and 25 MeV [1, 2]. The theoretical values can be brought into agreement with these results by increasing the strength of the 1S0 nn potential matrix element by roughly 10%. However, this modification of the nn effective range parameter and/or the 1S0 scattering length causes substantial charge-symmetry breaking in the nucleon-nucleon force and suggests the possibility of a weakly bound di-neutron state [3]. We are conducting new measurements of the cross section for nn QFS in nd breakup. The measurements are performed at incident neutron beam energies below 20 MeV. The neutron beam is produced via the 2H(d, n)3He reaction. The target is a deuterated plastic cylinder. Our measurements utilize time-of-flight techniques with a pulsed neutron beam and detection of the two emitted neutrons in coincidence. A description of our initial measurements at 10 MeV for a single scattering angle will be presented along with preliminary results. Also, plans for measurements at other energies with broad angular coverage will be discussed.

MAGNETIC NEUTRON SCATTERING

Energy Technology Data Exchange (ETDEWEB)

ZALIZNYAK,I.A.; LEE,S.H.

2004-07-30

Much of our understanding of the atomic-scale magnetic structure and the dynamical properties of solids and liquids was gained from neutron-scattering studies. Elastic and inelastic neutron spectroscopy provided physicists with an unprecedented, detailed access to spin structures, magnetic-excitation spectra, soft-modes and critical dynamics at magnetic-phase transitions, which is unrivaled by other experimental techniques. Because the neutron has no electric charge, it is an ideal weakly interacting and highly penetrating probe of matter's inner structure and dynamics. Unlike techniques using photon electric fields or charged particles (e.g., electrons, muons) that significantly modify the local electronic environment, neutron spectroscopy allows determination of a material's intrinsic, unperturbed physical properties. The method is not sensitive to extraneous charges, electric fields, and the imperfection of surface layers. Because the neutron is a highly penetrating and non-destructive probe, neutron spectroscopy can probe the microscopic properties of bulk materials (not just their surface layers) and study samples embedded in complex environments, such as cryostats, magnets, and pressure cells, which are essential for understanding the physical origins of magnetic phenomena. Neutron scattering is arguably the most powerful and versatile experimental tool for studying the microscopic properties of the magnetic materials. The magnitude of the cross-section of the neutron magnetic scattering is similar to the cross-section of nuclear scattering by short-range nuclear forces, and is large enough to provide measurable scattering by the ordered magnetic structures and electron spin fluctuations. In the half-a-century or so that has passed since neutron beams with sufficient intensity for scattering applications became available with the advent of the nuclear reactors, they have became indispensable tools for studying a variety of important areas of modern

Hydrogen absorption in Mg1.95Ti0.05Ni0.95Cu0.05 alloy prepared with mechanical alloying and thermal treatment; Absorcion de hidrogeno en la aleacion Mg1.95Ti0.05Ni0.95Cu0.05 preparada por aleado mecanico y tratamiento termico

Energy Technology Data Exchange (ETDEWEB)

Martinez, Juan Bonifacio; Urena Nunez, Fernando [Instituto Nacional de Investigaciones Nucleares, Ocoyoacac, Estado de Mexico (Mexico)]. E-mail: juan.bonifacio@inin.gob.mx

2009-09-15

This work presents hydrogen absorption in quaternary alloy Mg1.95Ti0.05Ni0.95Cu0.05 obtained by the mechanical alloying method, followed by thermal treatment in ultra-high pure argon atmosphere. The composition of the phases, microstructure and morphology of ground powders and with thermal treatment were characterized by DRX, SEM/EDS and TEM. After 20 hours of mechanical grinding and recooked at 300 degrees Celsius/1h in argon atmosphere, the quaternary alloy has a Mg{sub 2}Ni crystalline hexagonal structure with a crystallite size under 10 nm. The absorption measurements were performed under a pressure of 0.2 to 1.2 MPa at a temperature of 200 degrees Celsius in a micro-reactor. The quantification of absorption-desorption of hydrogen in the intermetallic was conducted in a TGA-DSC simultaneous calorimeter. Metallic hydride-dehydride powder was characterized with SEM and XRD. [Spanish] En este trabajo se presenta la absorcion de hidrogeno en la aleacion cuaternaria Mg1.95Ti0.05Ni0.95Cu0.05 obtenida por el metodo de aleado mecanico, seguida de tratamiento termico en atmosfera de argon de ultra alta pureza. La composicion de las fases, microestructura y morfologia de los polvos molidos y con tratamiento termico fue caracterizada por DRX, SEM/EDS y TEM. Despues de 20 h de molienda mecanica con recocido a 300 grados Celsios/1h en atmosfera de argon, la aleacion cuaternaria tiene una estructura cristalina hexagonal Mg{sub 2}Ni con tamano de cristalito menor a 10 nm. Las mediciones de absorcion fueron realizadas bajo una presion de 0.2 a 1.2 MPa a una temperatura de 200 grados Celsios en un micro-reactor. La cuantificacion de absorcion-desorcion de hidrogeno en el intermetalico se realizo en un calorimetro simultaneo TGA-DSC. Se determino que la cantidad maxima absorbida de hidrogeno en la aleacion cuaternaria fue de 3.24% en peso cuando la presion fue de 0.8 MPa a dicha temperatura. Polvos metalicos hidrurados-deshidrurados se caracterizaron por SEM y XRD.

Neutron Scattering

International Nuclear Information System (INIS)

Fayer, Michael J.; Gee, Glendon W.

2005-01-01

The neutron probe is a standard tool for measuring soil water content. This article provides an overview of the underlying theory, describes the methodology for its calibration and use, discusses example applications, and identifies the safety issues. Soil water makes land-based life possible by satisfying plant water requirements, serving as a medium for nutrient movement to plant roots and nutrient cycling, and controlling the fate and transport of contaminants in the soil environment. Therefore, a successful understanding of the dynamics of plant growth, nutrient cycling, and contaminant behavior in the soil requires knowledge of the soil water content as well as its spatial and temporal variability. After more than 50 years, neutron probes remain the most reliable tool available for field monitoring of soil water content. Neutron probes provide integrated measurements over relatively large volumes of soil and, with proper access, allow for repeated sampling of the subsurface at the same locations. The limitations of neutron probes include costly and time-consuming manual operation, lack of data automation, and costly regulatory requirements. As more non-radioactive systems for soil water monitoring are developed to provide automated profiling capabilities, neutron-probe usage will likely decrease. Until then, neutron probes will continue to be a standard for reliable measurements of field water contents in soils around the globe

A neutron beam polarizer for study of parity violation in neutron-nucleus interactions

International Nuclear Information System (INIS)

Penttilae, S.I.; Bowman, J.D.; Frankle, C.M.; Seestrom, S.J.; Yen, Yi-Fen; Delheij, P.P.J.; Haase, D.G.; Postma, H.

1994-01-01

A dynamically-polarized proton target operating at 5 Tesla and 1 K has been built to, neutron beam for studies of parity violation in compound-nuclear resonances. Nearly 0.9 proton polarization was obtained in an electron-beam irradiated ammonia target. This was used to produce a neutron beam polarization of 0.7 at epithermal energies. The combination of the polarized proton target and the LANSCE spallation neutron source produces the most intense pulsed polarized epithermal neutron beam in the world. The neutron-beam polarizer is described and methods to determine neutron beam polarization are presented

Online monitoring of fast neutron (DT/DD) at Purnima neutron generator

International Nuclear Information System (INIS)

Bishnoi, S.; Patel, T.; Shukla, M.; Adhikari, P.S.; Sinha, A.

2012-01-01

A neutron generator (NG) at Purnima Labs, BARC has been developed for DT accelerator driven zero power subcritical (ADSS) system. Subcritical core of ADSS will be coupled to the NG for benchmarking experiments. Kinetic parameters of ADSS such as K-source, flux, power etc depends on this external neutron source strength injected to the core. However the neutron emission rate of NG does not remain stable throughout its operation. In view of this a reliable, precise and online monitoring of NG's neutron emission rate is required. An online neutron monitoring system based on associated particle method has been designed, developed and installed at NG. The monitoring unit consists of an ion implanted planar silicon detector, placed inside the drift tube of NG at an angle with respect to D + beam direction. A series of experiments were carried out with increasing neutron yield to optimize the position of detector such that it has sufficient counting statistics and minimum pileup. A complementary calibration procedure for validating these results based on activation technique was also carried out with standard Cu foil. The reaction rate monitored with online monitor and foil activation technique were compared, their variations with the predicted (theoretical) results were within 16%. This paper deals with the development and performance of online neutron monitoring system for DT and DD neutrons

Neutrons and Nuclear Engineering

International Nuclear Information System (INIS)

Ekkebus, Allen E.

2007-01-01

Oak Ridge National Laboratory hosted two workshops in April 2007 relevant to nuclear engineering education. In the Neutron Stress, Texture, and Phase Transformation for Industry workshop (http://neutrons.ornl.gov/workshops/nst2/), several invited speakers gave examples of neutron stress mapping for nuclear engineering applications. These included John Root of National Research Council of Canada, Mike Fitzpatrick of the UK's Open University, and Yan Gao of GE Global Research on their experiences with industrial and academic uses of neutron diffraction. Xun-Li Wang and Camden Hubbard described the new instruments at ORNL that can be used for such studies. This was preceded by the Neutrons for Materials Science and Engineering educational symposium (http://neutrons.ornl.gov/workshops/edsym2007). It was directed to the broad materials science and engineering community based in universities, industry and laboratories who wish to learn what the neutron sources in the US can provide for enhancing the understanding of materials behavior, processing and joining. Of particular interest was the presentation of Donald Brown of Los Alamos about using 'Neutron diffraction measurements of strain and texture to study mechanical behavior of structural materials.' At both workshops, the ORNL neutron scattering instruments relevant to nuclear engineering studies were described. The Neutron Residual Stress Mapping Facility (NRSF2) is currently in operation at the High Flux Isotope Reactor; the VULCAN Engineering Materials Diffractometer will begin commissioning in 2008 at the Spallation Neutron Source. For characteristics of these instruments, as well as details of other workshops, meetings, capabilities, and research proposal submissions, please visit http://neutrons.ornl.gov. To submit user proposals for time on NRSF2 contact Hubbard at hubbardcratornl.gov

Introduction to neutron stars

Energy Technology Data Exchange (ETDEWEB)

Lattimer, James M. [Dept. of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States)

2015-02-24

Neutron stars contain the densest form of matter in the present universe. General relativity and causality set important constraints to their compactness. In addition, analytic GR solutions are useful in understanding the relationships that exist among the maximum mass, radii, moments of inertia, and tidal Love numbers of neutron stars, all of which are accessible to observation. Some of these relations are independent of the underlying dense matter equation of state, while others are very sensitive to the equation of state. Recent observations of neutron stars from pulsar timing, quiescent X-ray emission from binaries, and Type I X-ray bursts can set important constraints on the structure of neutron stars and the underlying equation of state. In addition, measurements of thermal radiation from neutron stars has uncovered the possible existence of neutron and proton superfluidity/superconductivity in the core of a neutron star, as well as offering powerful evidence that typical neutron stars have significant crusts. These observations impose constraints on the existence of strange quark matter stars, and limit the possibility that abundant deconfined quark matter or hyperons exist in the cores of neutron stars.

Evaluation of avoided carbon dioxide emissions in cogeneration projects; Evaluacion de las emisiones evitadas de bioxido de carbono en proyectos de cogeneracion

Energy Technology Data Exchange (ETDEWEB)

Flores Zamudio, Jesus Antonio; Fernandez Montiel, Manuel Francisco; Alcaraz Calderon, Agustin Moises [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)]. E-mail: jesus.flores@iie.org.mx; mffm@iie.org.mx; malcaraz@iie.org.mx

2010-11-15

In this paper, presents a methodology of how to calculate the emissions of CO{sub 2} (Carbon Dioxide) in cogeneration of plants for evaluate future cases with the type of fuel and fuel flow used in the plant. The methodology was in spreadsheets developed a series of stoichiometric balances. The methodology was done for three types of fossil fuels: solid, liquid and gas. The analysis is made only to the percentages of the items contained in the fuel flow automatically used and results in the combustion products in tons per hour. This method was compared with the results obtained in the software Thermoflow Inc. (Used in Gerencia de Procesos Termicos of Instituto de Investigaciones Electricas for evaluate various process systems that produce energy power) using different cogeneration systems, that is to say about the technology used emissions compared according to the amount of excess air for each type of technology and at one point before the gas cleaning systems. The results can be evaluated for emissions avoided through the fuel type used and developing a cogeneration plant compared to a conventional plant. [Spanish] En este articulo, se presenta una metodologia de como calcular las emisiones de CO{sub 2} (Bioxido de carbono) en plantas de cogeneracion, para evaluar casos a futuro por medio del tipo de combustible y flujo de combustible a utilizar en la planta. La metodologia se realizo en hojas de calculo, donde se desarrollaron una serie de balances estequiometricos. La metodologia se hizo para tres tipos de combustibles fosiles: solido, liquido y gas. El analisis se realiza con solo dar los porcentajes de los elementos que contiene el combustible y el flujo a utilizarse y automaticamente da como resultado los productos de la combustion en toneladas por hora. Esta metodologia se comparo con los resultados obtenidos en el software Thermoflow Inc. (Empleado en la Gerencia de Procesos Termicos del Instituto de Investigaciones Electricas para evaluar diversos

Study of neutron focusing at the Texas Cold Neutron Source. Final report

International Nuclear Information System (INIS)

Wehring, B.W.; Uenlue, K.

1995-01-01

Funds were received for the first year of a three year DOE Nuclear Engineering Research Grant, ''Study of Neutron Focusing at the Texas Cold Neutron Source'' (FGO2-92ER75711). The purpose of this three year study was to develop a neutron focusing system to be used with the Texas Cold Neutron Source (TCNS) to produce an intense beam of neutrons. A prompt gamma activation analysis (PGAA) facility was also to be designed, setup, and tested under the three year project. During the first year of the DOE grant, a new procedure was developed and used to design a focusing converging guide consisting of truncated rectangular cone sections. Detailed calculations were performed using a 3-D Monte Carlo code which we wrote to trace neutrons through the curved guide of the TCNS into the proposed converging guide. Using realistic reflectivities for Ni-Ti supermirrors, we obtained gains of 3 to 5 for the neutron flux averaged over an area of 1 x 1 cm

Microdosimetry of intermediate energy neutrons in fast neutron fields

International Nuclear Information System (INIS)

Saion, E.B.; Watt, D.E.

1988-01-01

A coaxial double cylindrical proportional counter has been constructed for microdosimetry of intermediate energy neutrons in mixed fields. Details are given of the measured gas gain and resolution characteristics of the counter for a wide range of anode voltages. Event spectra due to intermediate neutrons in any desired energy band is achieved by an appropriate choice of thickness of the common dividing wall in the counter and by appropriate use of the coincidence, anticoincidence pulse counting arrangements. Calculated estimates indicate that the dose contribution by fast neutrons to the energy deposition events in the intermediate neutron range may be as large as 25%. Empirical procedures being investigated aim to determine the necessary corrections to be applied to the microdose distributions, with a precision of 10%. (author)

Neutron capture studies of {sup 206}Pb at a cold neutron beam

Energy Technology Data Exchange (ETDEWEB)

Schillebeeckx, P.; Kopecky, S.; Quetel, C.R.; Tresl, I.; Wynants, R. [Institute for Reference Materials and Measurements, European Commission, Joint Research Centre, Geel (Belgium); Belgya, T.; Szentmiklosi, L. [Institute for Energy Security and Environmental Safety, Centre for Energy Research, Budapest (Hungary); Borella, A. [Institute for Reference Materials and Measurements, European Commission, Joint Research Centre, Geel (Belgium); SCK CEN, Mol (Belgium); Mengoni, A. [Nuclear Data Section, International Atomic Energy Agency (IAEA), Wagramerstrasse 5, PO Box 100, Vienna (Austria); Agenzia Nazionale per le Nuove Tecnologie, l' Energia e lo Sviluppo Economico Sostenibile (ENEA), Bologna (Italy)

2013-11-15

Gamma-ray transitions following neutron capture in {sup 206}Pb have been studied at the cold neutron beam facility of the Budapest Neutron Centre using a metallic sample enriched in {sup 206}Pb and a natural lead nitrate powder pellet. The measurements were performed using a coaxial HPGe detector with Compton suppression. The observed {gamma} -rays have been incorporated into a decay scheme for neutron capture in {sup 206}Pb. Partial capture cross sections for {sup 206}Pb(n, {gamma}) at thermal energy have been derived relative to the cross section for the 1884 keV transition after neutron capture in {sup 14}N. From the average crossing sum a total thermal neutron capture cross section of 29{sup +2}{sub -1} mb was derived for the {sup 206}Pb(n, {gamma}) reaction. The thermal neutron capture cross section for {sup 206}Pb has been compared with contributions due to both direct capture and distant unbound s-wave resonances. From the same measurements a thermal neutron-induced capture cross section of (649 {+-} 14) mb was determined for the {sup 207}Pb(n, {gamma}) reaction. (orig.)

Neutron filters for producing monoenergetic neutron beams

International Nuclear Information System (INIS)

Harvey, J.A.; Hill, N.W.; Harvey, J.R.

1982-01-01

Neutron transmission measurements have been made on high-purity, highly-enriched samples of 58 Ni (99.9%), 60 Ni (99.7%), 64 Zn (97.9%) and 184 W (94.5%) to measure their neutron windows and to assess their potential usefulness for producing monoenergetic beams of intermediate energies from a reactor. Transmission measurements on the Los Alamos Sc filter (44.26 cm Sc and 1.0 cm Ti) have been made to determine the characteristics of the transmitted neutron beam and to measure the total cross section of Sc at the 2.0 keV minimum. When corrected for the Ti and impurities, a value of 0.35 +- 0.03 b was obtained for this minimum

Latest developments of neutron scattering instrumentation at the Juelich Centre for Neutron Science

International Nuclear Information System (INIS)

Ioffe, Alexander

2013-01-01

Jülich Centre for Neutron Science (JCNS) is operating a number of world-class neutron scattering instruments situated at the most powerful and advanced neutron sources (FRM II, ILL and SNS) and is continuously undertaking significant efforts in the development and upgrades to keep this instrumentation in line with the continuously changing scientific request. These developments are mostly based upon the latest progress in neutron optics and polarized neutron techniques. For example, the low-Q limit of the suite of small angle-scattering instruments has been extended to 4·10 -5 Å -1 by the successful use of focusing optics. A new generation of correction elements for the neutron spin-echo spectrometer has allowed for the use of the full field integral available, thus pushing further the instrument resolution. A significant progress has been achieved in the developments of 3 He neutron spin filters for purposes of the wide-angle polarization analysis for off-specular reflectometry and (grazing incidence) small-angle neutron scattering, e.g. the on-beam polarization of 3 He in large cells is allowing to achieve a high neutron beam polarization without any degradation in time. The wide Q-range polarization analysis using 3 He neutron spin filters has been implemented for small-angle neutron scattering that lead to the reduction up to 100 times of the intrinsic incoherent background from non-deuterated biological molecules. Also the work on wide-angle XYZ magnetic cavities (Magic PASTIS) will be presented. (author)

Effect of neutrons scattered from boundary of neutron field on shielding experiment

International Nuclear Information System (INIS)

Ogawa, Tatsuhiko; Abe, Takuya; Kosako, Toshiso; Iimoto, Takeshi

2009-01-01

Neutron shielding experiment with 49 cm-thick ordinary concrete was carried out at the reactor 'Yayoi' The University of Tokyo. System of this experiment is enclosed by heavy concrete where neutrons backscattered from heavy concrete likely affected neutron flux on the back surface of shielding concrete. Reaction rate of 197 Au(n, γ), cadmium covered 197 Au(n, γ) and 115 In(n, n') in the shielding concrete was measured using foil activation method. Neutron transport calculation was carried out in order to simulate reaction rate by calculating neutron spectra and convoluting with neutron capture cross-section in neutron shielding concrete. Comparison was made between calculated reaction rate and experimental one, and almost satisfactory agreement was found except for the back surface of shielding. To compose adequate simulation model, description of heavy concrete behind the shielding was thought to be of importance. For example, disregarding neutrons backscattered from heavy concrete, calculation underestimated reaction rate by the factor of 10. In another example, assuming that chemical composition of heavy concrete is equal to the composition adopted from a literature, the reaction rate was overestimated by factor of 5. By making the composition of heavy concrete equal to that based on facility design, overestimation was found to be the factor of 2. Therefore, adequate description of chemical composition of heavy concrete is found to be of importance in order to simulate neutron induced reaction rate on the back surface of neutron shielding concrete in shielding experiment performed in a system enclosed by heavy concrete. (author)