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System for Comparing Gamma Sources Varying by Ratios of up to 1:1000; Dispositivo Gamma que para Comparar Fuentes Difieren Hasta uno En Mil

Conference:

Abstract

Two nonelectronic devices have been constructed permitting continuous and reasonably accurate amplification by a factor of up to 100 of the counting capacity of a scintillation system. This system is designed for use in comparing the activities of radiation sources, mainly of the gamma type, and also the activities of one and the same radioisotope, when they differ by a ratio of the order 1:1000. The immediate use of the system is in the preparation of gamma standards for the calibration of ionization chambers requiring radioisotope (e. g. {sup 60}Co and {sup 131}I) activities in millicuries, on the basis of corresponding standards with activities of the order of microcuries. The basic principle involved is to limit the passage of light through the scintillation crystal to the photomultiplier tube. In the first device, half the face of the Nal(Tl) scintillation crystal and half the face of the photomultiplier are screened in such a way that rotation of the crystal causes the screens to be superimposed and the amount of light is cut down by from 50% to nil. With this device, it has been possible in practice to compare activities varying by 1:20. The second device is fitted with five diaphragms  More>>
Authors:
Tejera Rivera, A.; Navarro Cuevas, D. [1] 
  1. Universidad Nacional Autonoma de Mexico, Mexico D.F. (Mexico)
Publication Date:
Mar 15, 1967
Product Type:
Conference
Report Number:
IAEA-SM-79/57
Resource Relation:
Conference: Symposium on Standardization of Radionuclides, Vienna (Austria), 10-14 Oct 1966; Other Information: 1 ref., 2 figs.; Related Information: In: Standardization of Radionuclides. Proceedings of a Symposium on Standardization of Radionuclides| 763 p.
Subject:
07 ISOTOPES AND RADIATION SOURCES; 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; COBALT 60; COMPARATIVE EVALUATIONS; DEAD TIME; GAMMA SOURCES; IODINE 131; SCINTILLATIONS
OSTI ID:
22116266
Research Organizations:
International Atomic Energy Agency, Vienna (Austria)
Country of Origin:
IAEA
Language:
Spanish
Other Identifying Numbers:
Other: ISSN 0074-1884; TRN: XA13M1553072921
Submitting Site:
INIS
Size:
page(s) 419-422
Announcement Date:
Jul 26, 2013

Conference:

Citation Formats

Tejera Rivera, A., and Navarro Cuevas, D. System for Comparing Gamma Sources Varying by Ratios of up to 1:1000; Dispositivo Gamma que para Comparar Fuentes Difieren Hasta uno En Mil. IAEA: N. p., 1967. Web.
Tejera Rivera, A., & Navarro Cuevas, D. System for Comparing Gamma Sources Varying by Ratios of up to 1:1000; Dispositivo Gamma que para Comparar Fuentes Difieren Hasta uno En Mil. IAEA.
Tejera Rivera, A., and Navarro Cuevas, D. 1967. "System for Comparing Gamma Sources Varying by Ratios of up to 1:1000; Dispositivo Gamma que para Comparar Fuentes Difieren Hasta uno En Mil." IAEA.
@misc{etde_22116266,
title = {System for Comparing Gamma Sources Varying by Ratios of up to 1:1000; Dispositivo Gamma que para Comparar Fuentes Difieren Hasta uno En Mil}
author = {Tejera Rivera, A., and Navarro Cuevas, D.}
abstractNote = {Two nonelectronic devices have been constructed permitting continuous and reasonably accurate amplification by a factor of up to 100 of the counting capacity of a scintillation system. This system is designed for use in comparing the activities of radiation sources, mainly of the gamma type, and also the activities of one and the same radioisotope, when they differ by a ratio of the order 1:1000. The immediate use of the system is in the preparation of gamma standards for the calibration of ionization chambers requiring radioisotope (e. g. {sup 60}Co and {sup 131}I) activities in millicuries, on the basis of corresponding standards with activities of the order of microcuries. The basic principle involved is to limit the passage of light through the scintillation crystal to the photomultiplier tube. In the first device, half the face of the Nal(Tl) scintillation crystal and half the face of the photomultiplier are screened in such a way that rotation of the crystal causes the screens to be superimposed and the amount of light is cut down by from 50% to nil. With this device, it has been possible in practice to compare activities varying by 1:20. The second device is fitted with five diaphragms on a rotating disk which permit the passage of light to be regulated from 100% to nil. Using this device, it is possible to compare sources varying in activity by ratios of up to 1:1000, keeping the scaler reading within the limits of 100 000 counts/min. The main advantage to this procedure is that error due to differences in counter dead time for counts on sources varying widely in activity is reduced; further, samples of this kind can be compared using small-size shielding. (author) [Spanish] Se han construido dos dispositivos no electronicos que permiten ampliar hasta 100 veces, de manera continua y con buena exactitud, la capacidad de recuento de un equipo de centelleo. La finalidad de este dispositivo es la comparacion de las actividades de fuentes de radiacion, principalmente gamma y de un mismo radioisotopo, cuando difieren en una relacion del orden de uno a miL La utilidad inmediata de este dispositivo es la elaboracion de patrones gamma para la calibracion de camaras de ionizacion que requieren actividades del orden de milicuries de radioisotopos, como el {sup 60}Co o el {sup 131}I, a partir de patrones respectivos con actividades del orden del microcurie. El principio en que se basan los dispositivos construidos es restringir el paso de la luz emitida por el cristal de centelleo al tubo fotomultiplicador. En el primer dispositivo se enmascaro la mitad de la cara del cristal de centelleo, Nal (TI), y la mitad de la cara del foto-multiplicador de tal forma que haciendo girar el cristal se sobreponen las mascaras y se restringe la luz desde 50% hasta 0%. Con este dispositivo se ha conseguido en la practica comparar actividades de uno a veinte. En el segundo dispositivo se han dispuesto cinco diafragmas en un disco rotatorio que permiten el paso desde 100% de luz hasta 1%. Usando este dispositivo es posible comparar fuentes que difieren hasta mil veces en actividad, manteniendo dentro de 100 000 cuentas/min la lectura del escalador. Este procedimiento resulta ventajoso principalmente porque disminuye el error debido a diferencias del tiempo muerto instrumental para los recuentos realizados con fuentes de muy diferente actividad y permite, ademas, comparar estas muestras usando un blindaje de dimensiones reducidas. (author)}
place = {IAEA}
year = {1967}
month = {Mar}
}