Monte Carlo simulation of the radiolysis of the ceric sulfate dosimeter by low linear energy transfer radiation

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From: Canadian Journal of Chemistry(Vol. 90, Issue 9)
Publisher: NRC Research Press
Document Type: Report
Length: 4,150 words
Lexile Measure: 1580L

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Abstract :

The ceric sulfate dosimeter is based on the radio-induced reduction of [Ce.sup.4+] in acidic medium. For low linear energy transfer (LET) radiation, the yield of [Ce.sup.3+] is 2.4 molecules/100 eV, regardless of the presence of oxygen. To investigate the reaction mechanisms of the ceric sulfate dosimeter, we simulated the chemical reaction kinetics curves and the evolution of G([Ce.sup.3+]), G([O.sub.2]), and G([H.sub.2]) in the ceric sulfate solution with and without oxygen. Studies of G([Ce.sup.3+]) as function of the initial concentration of [Ce.sup.3+] and of the LET were also done. One important finding of this study is that [sup.*]OH radicals are scavenged by the reaction [sup.*]OH + HS[O.sub.4]- [right arrow] S[O.sub.4]*- + [H.sub.2]O, rather than by the reaction [sup.*]OH + [Ce.sup.3+] [right arrow] [Ce.sup.4+] + O[H.sup.-]. Key words: ceric sulfate dosimeter, radiolysis, free-radical and molecular yields, linear energy transfer (LET), Monte Carlo simulations. Le dosimetre cerique est base sur la reduction radio-induite de [Ce.sup.4+] en milieu acide. Pour les radiations de faible transfert d'energie lineaire (TEL), le rendement de [Ce.sup.3+] est 2,4 molecules/100 eV, independamment de la presence d'oxygene. Pour etudier les mecanismes du dosimetre cerique, nous avons simule l'evolution temporelle de G([Ce.sup.3+]), G([O.sub.2])et G ([H.sub.2]) dans une solution de sulfate cerique avec et sans oxygene. Des etudes des rendements en fonction de la concentration initiale de [Ce.sup.3+] et du TEL ont egalement ete realisees. Une decouverte importante de cette etude est que les radicaux [sup.*]OH sont captes par la reaction [sup.*]OH + HS[O.sub.4]- [right arrow] S[O.sub.4]*- + [H.sub.2]O, plutot que par la reaction [sup.*]OH + [Ce.sup.3+] [right arrow] [Ce.sup.4+] + OH-. Mots-cles: dosimetre cerique, radiolyse, rendements radicalaires et moleculaires, transfert d'energie lineaire (TEL), simulations Monte Carlo.

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Gale Document Number: GALE|A305994522