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Fission ionisation chamber for the measurement of low fluxes of slow neutrons; Chambre d'ionisation a fission pour la mesure des faibles flux de neutrons lents

Abstract

The ionisation chamber described is designed for the measurement of slow neutron fluxes of average or low intensity, in the presence, eventually, of very high gamma fluxes. The capture of a slow neutron by a fissile material, in this case {sup 235}U, gives rise to fission fragments, high-energy particles which ionise the gas contained in the chamber. The neutrons are detected by virtue of the potential pulses, on the collecting electrode of the chamber, deriving from the collection of the ions produced by the fission fragments. The pulses are counted by means of a measuring system consisting of a preamplifier, a 2 Mc amplifier, a discriminator and an electronic scale with numerator or integrator. The general characteristics are as follows: sensitivity to neutrons: 0.07 kicks/n/cm{sup 2}.s, sensitivity to {gamma} rays: zero up to 3.10{sup 4} R/H, a background noise at the normal discrimination voltage: 0.01 kicks/s, working H.T.: -500 V, capacity: 40 {mu}{mu}F, average height of pulse: 8 mV, limits of use: from several neutrons to 10{sup 6} n/cm{sup 2}.s. This chamber may be used in all cases where low fluxes of slow neutrons must be measured, especially in the presence of high gamma fluxes, for example in the checking  More>>
Authors:
Weill, J; Duchene, J P [1] 
  1. Commissariat a l'Energie Atomique, Saclay (France). Centre d'Etudes Nucleaires
Publication Date:
Jul 01, 1958
Product Type:
Technical Report
Report Number:
CEA-R-870
Resource Relation:
Other Information: 6 refs
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ALPHA PARTICLES; ARGON; ATMOSPHERIC PRESSURE; BACKGROUND RADIATION; COUNTING RATES; CROSS SECTIONS; DESIGN; ELECTRODEPOSITION; ENRICHED URANIUM; FISSILE MATERIALS; FISSION CHAMBERS; FISSION FRAGMENT DETECTION; GAMMA RADIATION; MEV RANGE; NATURAL RADIOACTIVITY; NEUTRON FLUX; PARTICLE DISCRIMINATION; RADIOSENSITIVITY; SLOW NEUTRONS
OSTI ID:
20889997
Research Organizations:
CEA Saclay, 91 - Gif-sur-Yvette (France)
Country of Origin:
France
Language:
French
Other Identifying Numbers:
TRN: FR07R0870054616
Availability:
Available from INIS in electronic form
Submitting Site:
FRN
Size:
16 pages
Announcement Date:
Aug 10, 2007

Citation Formats

Weill, J, and Duchene, J P. Fission ionisation chamber for the measurement of low fluxes of slow neutrons; Chambre d'ionisation a fission pour la mesure des faibles flux de neutrons lents. France: N. p., 1958. Web.
Weill, J, & Duchene, J P. Fission ionisation chamber for the measurement of low fluxes of slow neutrons; Chambre d'ionisation a fission pour la mesure des faibles flux de neutrons lents. France.
Weill, J, and Duchene, J P. 1958. "Fission ionisation chamber for the measurement of low fluxes of slow neutrons; Chambre d'ionisation a fission pour la mesure des faibles flux de neutrons lents." France.
@misc{etde_20889997,
title = {Fission ionisation chamber for the measurement of low fluxes of slow neutrons; Chambre d'ionisation a fission pour la mesure des faibles flux de neutrons lents}
author = {Weill, J, and Duchene, J P}
abstractNote = {The ionisation chamber described is designed for the measurement of slow neutron fluxes of average or low intensity, in the presence, eventually, of very high gamma fluxes. The capture of a slow neutron by a fissile material, in this case {sup 235}U, gives rise to fission fragments, high-energy particles which ionise the gas contained in the chamber. The neutrons are detected by virtue of the potential pulses, on the collecting electrode of the chamber, deriving from the collection of the ions produced by the fission fragments. The pulses are counted by means of a measuring system consisting of a preamplifier, a 2 Mc amplifier, a discriminator and an electronic scale with numerator or integrator. The general characteristics are as follows: sensitivity to neutrons: 0.07 kicks/n/cm{sup 2}.s, sensitivity to {gamma} rays: zero up to 3.10{sup 4} R/H, a background noise at the normal discrimination voltage: 0.01 kicks/s, working H.T.: -500 V, capacity: 40 {mu}{mu}F, average height of pulse: 8 mV, limits of use: from several neutrons to 10{sup 6} n/cm{sup 2}.s. This chamber may be used in all cases where low fluxes of slow neutrons must be measured, especially in the presence of high gamma fluxes, for example in the checking of Pu concentrations in an extraction plant or for the starting up of reactors. (author) [French] La chambre d'ionisation decrite est destinee a la mesure des flux de neutrons lents d'intensite moyenne ou faible, en presence eventuelle de flux gamma tres importants. La capture d'un neutron lent par un materiau fissile, en l'occurrence {sup 235}U, donne naissance a des fragments de fission, particules de grande energie qui ionisent le gaz contenu dans la chambre. Les neutrons sont detectes grace aux impulsions de potentiel, sur l'electrode collectrice de la chambre, provenant de la collection des ions produits par les fragments de fission. Une chaine de mesure comprenant un preamplificateur, un amplificateur 2 Mc, un discriminateur, une echelle electronique avec numerateur ou integrateur permet le comptage des impulsions. Les caracteristiques generales sont: sensibilite aux neutrons: 0,07 choc /n/cm{sup 2}.s, sensibilite aux rayons {gamma}: nulle jusqu'a 3.10{sup 4} R/H, bruit de fond {alpha} a la tension normale de discrimination: 0,01 choc/s, H.T. de fonctionnement: -500 V, capacite: 40 {mu}{mu}F, hauteur moyenne d'impulsion: 8 mV, limites d'emploi: de quelques neutrons a 10{sup 6} n/cm{sup 2}.s. Cette chambre peut etre utilisee dans tous les cas ou l'on doit mesurer de faibles flux de neutrons lents, surtout en presence de flux gamma intenses, par exemple pour le controle des concentrations de Pu dans une usine d'extraction, ou pour le demarrage des reacteurs. (auteur)}
place = {France}
year = {1958}
month = {Jul}
}