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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

Conference:

Abstract

By a mass spectrometer fission fragments from thermal fission of U{sup 235} are exactly separated with respect to mass and kinetic energy within a time of 10{sup -6} s after fission. The separated fragments are caught in a {beta}-sensitive Ilford G 5 emulsion that is located in the focal plane of the spectrometer. Development of the irradiated emulsions is carried out, if possible, after a time long compared with the longest half-life of the regarded decay chain. Half-lives of days or longer are not taken into account, but corrections can be easily made for them. After development of the emulsions all beta tracks emerging from the end of every fission-fragment track can be seen under the microscope. The possibility of correlating every single {beta}-track with a particular fission-fragment track allows the evaluation of the number n(x) of fission fragments possessing x {beta}-tracks, thus giving not only the mean chain length but also the {beta}-particle distribution. As the stable end product of each decay chain is known, this {beta}-distribution is an exact image of the primary nuclear charge distribution. In the measurements done up to now only {beta}-particles emitted into the half solid angle formed by the emulsion plate were registered,  More>>
Authors:
Konecny, E.; Opower, H.; Guenther, H.; Goebel, H. [1] 
  1. Physik-Department der Technischen Hochschule Muenchen, Munich and II. Physikalisches Institut der Justus Liebig-Universitaet Giessen, Federal Republic of Germany (Germany)
Publication Date:
Jul 15, 1965
Product Type:
Conference
Report Number:
IAEA-SM-60/33
Resource Relation:
Conference: Symposium on Physics and Chemistry of Fission, Salzburg (Austria), 22-26 Mar 1965; Other Information: 20 refs., 8 figs., 1 tab.; Related Information: In: Physics and Chemistry of Fission. Vol. I. Proceedings of the Symposium on Physics and Chemistry of Fission| 654 p.
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ATOMIC NUMBER; COMPARATIVE EVALUATIONS; DELAYED NEUTRONS; DISTRIBUTION; ELECTRONS; EMULSIONS; FISSION FRAGMENTS; HALF-LIFE; KINETIC ENERGY; MASS; MASS SPECTROMETERS; PARTICLE TRACKS; THERMAL FISSION; URANIUM 235
OSTI ID:
22184512
Research Organizations:
International Atomic Energy Agency, Vienna (Austria)
Country of Origin:
IAEA
Language:
English
Other Identifying Numbers:
Other: ISSN 0074-1884; TRN: XA13M3163008495
Submitting Site:
INIS
Size:
page(s) 401-413
Announcement Date:
Jan 30, 2014

Conference:

Citation Formats

Konecny, E., Opower, H., Guenther, H., and Goebel, H. 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. IAEA: N. p., 1965. Web.
Konecny, E., Opower, H., Guenther, H., & Goebel, H. 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. IAEA.
Konecny, E., Opower, H., Guenther, H., and Goebel, H. 1965. "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." IAEA.
@misc{etde_22184512,
title = {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}
author = {Konecny, E., Opower, H., Guenther, H., and Goebel, H.}
abstractNote = {By a mass spectrometer fission fragments from thermal fission of U{sup 235} are exactly separated with respect to mass and kinetic energy within a time of 10{sup -6} s after fission. The separated fragments are caught in a {beta}-sensitive Ilford G 5 emulsion that is located in the focal plane of the spectrometer. Development of the irradiated emulsions is carried out, if possible, after a time long compared with the longest half-life of the regarded decay chain. Half-lives of days or longer are not taken into account, but corrections can be easily made for them. After development of the emulsions all beta tracks emerging from the end of every fission-fragment track can be seen under the microscope. The possibility of correlating every single {beta}-track with a particular fission-fragment track allows the evaluation of the number n(x) of fission fragments possessing x {beta}-tracks, thus giving not only the mean chain length but also the {beta}-particle distribution. As the stable end product of each decay chain is known, this {beta}-distribution is an exact image of the primary nuclear charge distribution. In the measurements done up to now only {beta}-particles emitted into the half solid angle formed by the emulsion plate were registered, buta simple statistical calculation enables the desired 4{pi}-distribution to be evaluated. By this method {beta}-distributions at fixed kinetic energies near the mean kinetic energy of each fragment mass are given for the masses 132, 134, 136 and 137. For the lower masses 132 and 134 the neutron shell N = 82 is responsible for the most probable primary charges near 50 and 52 respectively. For M = 136 and 137 the primary charge is about 53 and 53.2. Additional approximative corrections in respect of conversion electrons (by omitting very short {beta}-tracks corresponding to very low {beta}-energies) and to delayed neutrons (for mass 137) were not very large. Similar measurements carried out directly in 4{pi}-geometry to avoid the statistical error arising from the transformation from 2{pi}- to 4{pi}-distribution, and for various kinetic energies as parameters, are in preparation. (author) [French] A l'aide d'un spectrometre de masse, on separe avec precision les fragments de la fission thermique de {sup 235}U d'apres leur masse et leur energie cinetique dans la microseconde qui suit la fission. Les fragments separes sont retenus dans une emulsion Ilford G 5 sensible aux particules {beta}, qui est placee dans le plan focal du spectrometre. Les emulsions irradiees sont developpees, dans la mesure du possible, apres un delai relativement long par rapport a la periode la plus longue de la serie radioactive consideree. Les periodes de l'ordre de plusieurs jours ou plus longues encoxe ne sont pas prises en consideration, mais il est facile d'appliquer un facteur de correction approprie. Apres avoir developpe les emulsions, on peut observer au microscope toutes les traces {beta} qui prolongent chacune des traces de fragments de fission. La possibilite d'etablir une correlation entre une trace {beta} et une trace de fragment de fission permet d'evaluer le nombre n(x) de fragments de fission possedant un nombre x de traces {beta}, ce qui indique non seulement la longueur moyenne de la serie mais aussi la distribution des particules {beta}. Le nucleide stable de chaque serie etant connu, la distribution des particules {beta} constitue une image exacte de la repartition primaire des charges nucleaires. Au cours des mesures effectuees jusqu'a present, on n'a en-' registre que les particules {beta} emises dans le demi-angle solide forme par la plaque d'emulsion, mais un calcul statistique simple permet d'evaluer la distribution. 4{pi} voulue. Grace a cette methode, on obtient la distribution des particules 0 a des energies cinetiques determinees proches de l'energie cinetique moyenne de chaque fragment pour les masses 132, 134, 136 et 137. Pour les masses 132 et 134, c'est a la couche de neutrons N = 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 estable de cada cadena es conocido, esta distribucion de las particulas beta refleja fielmente la distribucion primaria de las cargas nucleares. En las mediciones realizadas hasta ahora, solo se han registrado las particulas beta recogidas en el semiangulo solido formado por la placa portadora de la emulsion, pero un simple calculo estadistico permite determinar la distribucion 4{pi} apetecida. En la memoria se indican las distribuciones de particulas beta obtenidas por este metodo, a energias cineticas fijas, proximas a la energia cinetica media de cada fragmento, para las masas 132, 134, 136 y 137. En lo que respecta a las masas 132 y 134, la capa neutronica N = 82 determina las cargas primarias mas probables en las proximidades de 50 y 52, respectivamente. Para M= 136 y 137, la carga primaria es de 53 y 53,2. No resultan muy considerables las correcciones aproximadas, de caracter complementario para tener en cuenta los electrones.de conversion (omitiendo las trazas muy cortas de particulas beta correspondientes a energias muy bajas) y los neutrones retardados (en el caso de la masa 137). Se estan preparando mediciones analogas que se efectuaran directamente en geometria 4{pi} para evitar el error estadistico debido a la transformacion de la distribucion 2{pi} en 4{pi}, con varias energias cineticas como parametros. (author) [Russian] Pri pomoshhi mass-spektrometra oskolki, obrazujushhiesja pri delenii urana-235 pod dejstviem teplovyh nejtronov, tochno otdeljajutsja po masse i kineticheskoj jenergii za promezhutok vremeni v 10{sup -6} sek posle delenija. Izvlechennye oskolki zahvatyvajutsja na jemul'siju Il'forda G5, chuvstvitel'nuju k beta-chasticam i raspolozhennuju v ploskosti fokusa spektrometra. Obluchennye jemul'sii projavljajutsja po mere vozmozhnosti spustja dostatochno dolgoe vremja posle delenija po sravneniju s naibolee dolgim poluperiodom zhizni rassmatrivaemoj cepochki raspada. Poluperiody zhizni porjadka neskol'kih dnej ili bolee ne prinimajutsja vo vnimanie, no v otnoshenii ih legko vnesti sootvetstvujushhie popravki. Posle projavlenija jemul'sij vse beta-sledy, idushhie ot konca kazhdogo sleda oskolkov delenija, jasno vidny pod mikroskopom. Vozmozhnost' korreljacii kazhdogo otdel'nogo beta-sleda s opredelennym sledom oskolka delenija delaet vozmozhnym ustanovit' chislo p(h) oskolkov delenija, imejushhih ''h'' beta-sledy, chto daet ne tol'ko srednjuju dlinu cepochki, no takzhe raspredelenie beta-chastic. Tak kak ustojchivyj konechnyj produkt kazhdogo raspada v cepochke izvesten, to jeto raspredelenie beta-chastic javljaetsja tochnym izobrazheniem raspredelenija pervichnogo jadernogo zarjada. Pri izmerenijah, provodivshihsja do nastojashhego vremeni, registrirovalis' tol'ko beta-chasticy, izluchennye v polovine prostranstvennogo ugla, o'razovannogo jemul'sionnoj plastinkoj; odnako prostoj statisticheskij podschet daet vozmozhnost' ustanovit' zhelaemoe raspredelenie v geometrii 4{pi}. Na osnovanii jetogo metoda raspredelenija beta-chastic pri opredelennyh kineticheskih jenergijah, blizkih k srednej kineticheskoj jenergii kazhdoj massy oskolkov, dajutsja dlja mass 132, 134, 136 i 137. Dlja bolee nizkih iz jetih mass, , a imenno 132 i 134, nejtronnaja obolochka N = 82 opredeljaet naibolee verojatnye pervichnye zarjady sootvetstvenno okolo 50 i 52. Dlja M =136 i 137 pervichnyj zarjad sostavljaet okolo 53 i 53,2. Dopolnitel'nye priblizitel'nye popravki na jelektrony konversii (ne schitaja ochen' korotkih beta-sledov, sootvetstvujushhih ochen'malym beta-jenergijam) i na zapazdyvajushhie nejtrony (dlja massy 137) okazyvajutsja ne ochen' znachitel'nymi. V nastojashhee vremja podgotavlivajutsja analogichnye izmerenija neposredstvenno v geometrii 4{pi} vo izbezhanie statisticheskih pogreshnostej, voznikajushhih ot preobrazovanija raspredelenija 2{pi} v raspredelenie 4{pi} a takzhe dlja razlichnyh kineticheskih jenergij, prinimaemyh v kachestve parametrov. (author)}
place = {IAEA}
year = {1965}
month = {Jul}
}