Mesure de la luminescence induite par le rayonnement α du 210Po dans l'air et dans l'eau

Abstract

This paper refers to the study of the luminescence induced in air and water by the α-particles from 210Po. A description of the experimental device is given, the main piece of it being a photomultiplier 51 UVP with a quartz window. A method is suggested to determine the number of photons produced, individually, by each α particle in the scintillating substance. The shape of the pulse spectrum connected with the emission of light is explained. The geometry efficiency of light collection is calculated by means of different hypotheses as to the distribution of the photons along the track of the α particles. The sensitivity of this mode of detection is brought to evidence by the fact that one is able to observe such a small scintillation as that of water, which has been estimated to 2-3 photons per α-particle of 2.5 MeV, in the range of wavelengths from 2 200 to 5 200 Å. In air, the radiochemical yield has been evaluated as 6.10—4 photon per ions pair, in the same range of wavelengths, and a rough experiment shows evidence that nitrogen is responsible for the luminescence.Une méthode est indiquée pour atteindre, par la technique des impulsions, en utilisant un photomultiplicateur à fenêtre de quartz (51 UVP), le nombre de photons produits le long d'une trajectoire α dans la substance luminescente. La grande sensibilité de cette méthode a permis de mettre en évidence une très petite scintillation de l'eau: 2 à 3 photons par particule α de 2,5 MeV dans la bande 2 200 Å < λ < 5 200 Å. Pour l'air le rendement radiochimique a été évalué à 6.10—4 photons par paire d'ions