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Submitted on 1 Jan 1980
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Radiation induced M-centre production in NaCl at and above 15 °C
E. Hodgson, A. Delgado, J. Alvarez Rivas
To cite this version:
E. Hodgson, A. Delgado, J. Alvarez Rivas. Radiation induced M-centre production in NaCl at and above 15 °C. Journal de Physique Colloques, 1980, 41 (C6), pp.C6-351-C6-351.
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JOURNAL DE PHYSIQUE
Colloyue C6, supplkment au no 7 , Tome 41, Juillet 1980, page C6-35 1
Radiation induced M-centre production in NaCl at and above 15 "C
E. R. Hodgson, A. Delgado and J. L. Alvarez Rivas
Division de Fisica, Junta de Energia Nuclear, Madrid, SpalnAbstract. - From a series of experiments studying F and M-centre production a t low gamma dose rates ( - l o 4 R h - I ) and a t temperatures in the range 15-95 OC, it was found that M c e n t r e production could be des- cribed by two distinct processes, one purely statistical, and another due to F-centre thermal diffusion [ I , 21.
Experiments are now being carried out irradiating samples with 1.2 MeV electrons (I
-
10 nA cm-', equivalent to-
l o 5 R h - I ) , with the aim to bridging the gap between the low dose rate work (- lo4 R h - ' , F-centre density-
l o L 6 ~ m - ~ ) and the high dose rate data( 2
l o 6 R h - I , F-centre density2
1017 cm-9). In this way, one should be able t o separate the individual processes involved in F-aggregation and determine the dominant process a t any given dose rate. At the medium dose rates a non-thermal diffusion process is observed, which is directly pro- portional to the dose rate. The M-centre production rate may be written,The first term represents the statistical M c e n t r e production, the second thermal diffusion, the third radiation induced diffusion and the last term all possible M-centre annihilation processes [2]. This last term is necessary a t and above about 75 O C where R-centre production is observed to be important. Whereas the thermal diffusion process is important even a t low F-centre densities ( < 1016 ~ m - ~ ) , the radiation induced diffusion appears to be short range, only being observed for F-centre densities above about 1017 ~ m - ~ .
As in the case o f the thermal diffusion process, the radiation induced diffusion process also does not lead to an M = K, F2 relation. The fact that this relationship is observed to hold a t very high dose rates could be due to the importance of the term f ( M ) giving rise to an equilibrium situation, or to the term dF/dt which increases rapidly in third stage coloration.
DISCUSSION
Question.
-S. STERN. Reply.
-E. R. HODGSON.
Do you get a value for the activation energy for Yes, 0.88 eV. The thermal and statistical production the thermal diffusion term
?has been reported (J. Phys. C . 12 1239).
References
[I] HODGSON, E. R., DELGADO, A , ALVAREZ RIVAS, J. L., Phys. [2] HOWSON, E. R., DELGADO, A. and AI.VAREZ RIVAS, J. L., Rev. B 18 (1978) 2911. J Phys. C. 12 (1979) to be published.
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1980689
