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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

Conference:

Abstract

The measurement of single differential neutron scattering cross-sections (d{sigma}/d {Omega}) for the common moderators is being carried out by time-of-flight techniques. The procedure utilizes an intense pulsed source of thermal neutrons produced by the General Atomic linear accelerator, and a 12-m flight path at the end of which is located i thin sample of the moderator under investigation. In addition there is a short final flight path for the scattered neutrons from the sample to several totally absorbing neutron detectors. The scattering angular distribution for over 50 incident neutron energies can be measured simultaneously using the above procedure. Intensities are high, background is low and well defined, and measurements may be made rapidly at all scattering angles from 10 Degree-Sign to 155 Degree-Sign . Measurements of the differential scattering cross-section for vanadium, H{sub 2}O, D{sub 2}O and ZrH are presented. Vanadium has been studied as a check of the experimental apparatus. H{sub 2}O measurements for several sample thicknesses and orientations have been made for comparison with calculations based on various bound hydrogen scattering models and for comparison with the work of Springer and Reinsch. The experimental measurements have all been corrected for the serious effects of multiple scattering in the  More>>
Authors:
Beyster, J. R.; Young, J. C.; Neill, J. M.; Mowry, W. R. [1] 
  1. General Atomic Division of General Dynamics Corporation, John Jay Hopkins Laboratory for Pure and Applied Science, San Diego, CA (United States)
Publication Date:
Aug 15, 1965
Product Type:
Conference
Report Number:
IAEA-SM-62/64
Resource Relation:
Conference: Symposium on Pulsed Neutron Research, Karlsruhe (Germany), 10-14 May 1965; Other Information: 20 refs., 9 figs.; Related Information: In: Pulsed Neutron Research. Vol. I. Proceedings of the Symposium on Pulsed Neutron Research| 713 p.
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANGULAR DISTRIBUTION; CROSS SECTIONS; EV RANGE; EXPERIMENTAL DATA; HEAVY WATER; HYDROGEN; KERNELS; MODERATORS; MOLECULAR MODELS; MULTIPLE SCATTERING; NEUTRON DETECTORS; NEUTRON DIFFRACTION; NEUTRON SOURCES; NEUTRON TRANSPORT; PULSED NEUTRON TECHNIQUES; THERMAL NEUTRONS; TIME-OF-FLIGHT METHOD; VANADIUM; WATER; ZIRCONIUM HYDRIDES
OSTI ID:
22122984
Research Organizations:
International Atomic Energy Agency, Vienna (Austria)
Country of Origin:
IAEA
Language:
English
Contract Number:
Contract AT(04-3)-167
Other Identifying Numbers:
Other: ISSN 0074-1884; TRN: XA13M2587078786
Submitting Site:
INIS
Size:
page(s) 407-421
Announcement Date:
Aug 30, 2013

Conference:

Citation Formats

Beyster, J. R., Young, J. C., Neill, J. M., and Mowry, W. R. 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. IAEA: N. p., 1965. Web.
Beyster, J. R., Young, J. C., Neill, J. M., & Mowry, W. R. 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. IAEA.
Beyster, J. R., Young, J. C., Neill, J. M., and Mowry, W. R. 1965. "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." IAEA.
@misc{etde_22122984,
title = {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}
author = {Beyster, J. R., Young, J. C., Neill, J. M., and Mowry, W. R.}
abstractNote = {The measurement of single differential neutron scattering cross-sections (d{sigma}/d {Omega}) for the common moderators is being carried out by time-of-flight techniques. The procedure utilizes an intense pulsed source of thermal neutrons produced by the General Atomic linear accelerator, and a 12-m flight path at the end of which is located i thin sample of the moderator under investigation. In addition there is a short final flight path for the scattered neutrons from the sample to several totally absorbing neutron detectors. The scattering angular distribution for over 50 incident neutron energies can be measured simultaneously using the above procedure. Intensities are high, background is low and well defined, and measurements may be made rapidly at all scattering angles from 10 Degree-Sign to 155 Degree-Sign . Measurements of the differential scattering cross-section for vanadium, H{sub 2}O, D{sub 2}O and ZrH are presented. Vanadium has been studied as a check of the experimental apparatus. H{sub 2}O measurements for several sample thicknesses and orientations have been made for comparison with calculations based on various bound hydrogen scattering models and for comparison with the work of Springer and Reinsch. The experimental measurements have all been corrected for the serious effects of multiple scattering in the samples. At present the pronounced variation predicted at about 0.06 eV neutron energy by the Nelkin scattering model is not observed experimentally due to the fact that the assumed single hindered rotator at 0.06 eV is not physically realistic. In addition large angle scattering is not predicted correctly by this simple model. The experimental data serve several useful purposes. First the angular distributions are quite sensitive to the physical properties of the scattering model and serve to verify their adequacy. Secondly the experimental results are sensitive to higher orders of the P{sub n} scattering, in contrast to many integral experiments, which are sensitive mainly to P{sub 0} scattering. In particular one may test the P{sub 1} scattering kernel appropriate to a given molecular model. Third, the transport cross-section may be calculated directly from the experiments for use in multigroup reactor analysis. (author) [French] On mesure par les methodes du temps de vol les sections efficaces differentielles de diffusion simple (d{sigma}/d {Omega}) pour les ralentisseurs usuels. On utilise des neutrons thermiques produits par une source puisee intense (accelerateur lineaire de la General Atomic) avec un parcours de vol de 12 m a l'extremite duquel est place un echantillon mince du ralentisseur a l*etude. En outre, on a egalement prevu un petit parcours de vol terminal pour les neutrons diffuses, entre l'echantillon et plusieurs detecteurs de neutrons entierement absorbants. Cette methode permet de mesurer simultanement la distribution angulaire de diffusion pour plus de 50 energies des neutrons incidents. Les intensites sont-elevees, le bruit de fond est faible et bien defini et on peut proceder a des mesures rapides pour tous les angles de diffusion compris entre 10 et 155 degres. Les auteurs presentent des mesures de la section efficace differentielle de diffusion pour le vanadium, H{sub 2}O, D{sub 2}O et ZrH. On a etudie le vanadium pour controler le dispositif experimental. On a fait des mesures avec H{sub 2}O pour diverses epaisseurs et orientations des echantillons en vue de les comparer aux calculs fondes sur divers modeles de diffusion par l'hydrogene lie et aux resultats obtenus par Springer et Reinsch. Toutes les mesures experimentales ont ete corrigees pour tenir compte des effets importants de la diffusion multiple dans les echantillons. Pour l'instant, on n'a pas observe experimentalement la variation accusee que fait prevoir le modele de diffusion de Nelkin lorsque l'energie des neutrons est d'environ 0,06 eV; ceci est du au fait que l'hypothese du rotateur unique inhibe a 0,06 eV n'a pas 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 H{sub 2}O, con muestras de espesor y orientacion diferentes para cotejar los resultados con los calculos basados en varios modelos de dispersion con enlaces hidrogeno, y para compararlos tambien con los trabajos de Springer y Reinsch. Las mediciones experimentales se han corregido para compensar los acusados efectos de la dispersion multiple en las muestras. En la actualidad, la pronunciada variacion prevista para una energia neutronica de 0,06 eV, aproximadamente, por el modelo de dispersion de Nelkin no se observa experimentalmente debido a que el rotor monorrestringido que se considera a 0,06 eV, no es realista desde el punto de vista fisico. Ademas, este modelo simple no describe satisfactoriamente la dispersion a grandes angulos. Los datos experimentales sirven para varios fines. En primer lugar, las distribuciones angulares son muy sensibles a las propiedades fisicas del modelo de dispersion y permiten verificar su validez. En segundo lugar, los resultados experimentales son sensibles a la dispersion P{sub n} de orden superior, a diferencia de muchos experimentos integrales, que son sensibles sobre todo a la dispersion P{sub 0}: en particular es posible comprobar el nucleo de dispersion P{sub 1} apropiado para un modelo molecular determinado. Por ultimo, la seccion eficaz de transporte puede calcularse directamente a partir de los datos experimentales y utilizarse para el analisis de reactores por el metodo de varios grupos. (author) [Russian] Izmerenija sechenij (d{sigma}/d {Omega})odnokratnogo differencial'nogo rassejanija nejtronov dlja zamedlitelej obychnyh vidov provoditsja po metodu izmerenija vremeni proleta. Metod predusmatrivaet ispol'zovanie intensivnogo pul'sirujushhego istochnika teplovyh nejtronov, proizvodimyh linejnym uskoritelem obshhestva ''Dzheneral atomik'' s dlinoj proleta v 12m, v konce kotorogo raspolagaetsja tonkij obrazec issleduemogo zamedlitelja. V dopolnenie k jetomu imeetsja eshhe konechnyj put' proleta dlja rassejannyh obrazcov nejtronov po napravleniju k neskol'kim polnost'ju pogloshhajushhim nejtrony detektoram. Metod pozvoljaet izmerjat' odnovremenno uglovoe raspredelenie bolee chem dlja 50 energij bombardirujushhih nejtronov. Intensivnosti vysoki, fonovye shumy maly i horosho opredeleny, tak chto izmerenija mogut proizvodit'sja bystro pri vseh uglah rassejanija ot 10 do 155m. Soobshhajutsja rezul'taty izmerenij sechenij differencial'nogo rassejanija dlja vanadija, N{sub 2}O, D{sub 2}O i ZrH. Vanadij izuchen dlja proverki jeksperimental'nogo oborudovanija. Izmerenija s N{sub 2}O dlja obrazcov raznoj tolshhiny v razlichnyh napravlenijah provedeny dlja sopostavlenija s raschetami, osnovannymi na razlichnyh modeljah rassejanija so svjazannym vodorodom, i dlja sravnenija s rabotami Shpringera i Rejnsha. Vo vse jeksperimental'nye izmerenija byli vneseny popravki na nabljudaemoe v obrazcah sil'noe vozdejstvie mnogokratnogo rassejanija. V nastojashhee vremja predskazyvaemoe model'ju rassejanija Nelkina sil'noe izmenenie pri energii nejtronov priblizitel'no v 0,06 jev jeksperimental'no ne nabljudaetsja iz-za togo, chto predpolozhitel'nyj edinyj rotator s tormozheniem pri moshhnosti v 0,06 jev ne predstavljaetsja fizicheski real'nym. Krome togo, jeta prostaja model' ne predugadyvaet pravil'no rassejanie pri bol'shih uglah. Jeksperimental'nye dannye sluzhat dlja celogo rjada poleznyh nadobnostej. Prezhde vsego uglovoe raspredelenie chrezvychajno chuvstvitel'no po otnosheniju k fizicheskim svojstvam modeli rassejanija i pojetomu sluzhit dlja proverki udovletvoritel'nosti jetoj modeli. Vo-vtoryh, jeksperimental'nye rezul'taty chuvstvitel'ny k bolee vysokim porjadkam rassejanija P{sub n} v protivopolozhnost' mnogochislennym integral'nym jeksperimentam, kotorye chuvstvitel'ny glavnym obrazom k rassejaniju P{sub 0}. V chastnosti predstavljaetsja vozmozhnym proverjat' jadro rassejanija P{sub 1} tak, chtoby ono podhodilo dlja dannoj molekuljarnoj modeli. V- tret'ih, na osnovanii jeksperimentov predstavljaetsja vozmozhnym podschityvat' neposredstvenno sechenija perenosa dlja ispol'zovanija ih v analize reaktorov mnogih grupp. (author)}
place = {IAEA}
year = {1965}
month = {Aug}
}