摘要:

The continuum Fokker-Planck formalism is applied to describe the compositional changes in composite solids during simultaneous ion bombardment and atomic flux deposition. The general defining equations are derived. As a demonstration of the limitations and the extent of applicability of this approach the case of ion irradiation of composite solids has been studied comprehensively in the limit of ballistically equivalent species and in the absence of cascade mixing and diffusion. In the second part of this communication some general relations between the steady state partial sputtering yields of the different constituents for some specific systems are also derived. In particular, the net erosion and the net deposition regimes are studied as well as the transition between them. It is shown that the latter could be discontinuous with increasing deposition fluxes for particular systems.

ISSN:1042-0150    

DOI:10.1080/10420159408229031

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The effects of neutron, gamma and alpha radiations on the alpha and fission fragment tracks registration and revelation properties of CR-39 detectors (CR-39 and CR-39(DOP) were studied. It was found that the ratio of the bulk etch rate of irradiated to unirradiated (VG(irr.)/VG(unirr.) detectors is linearly dependent on dose. An exponential decrease in fission track densities with increase in neutron fluence was observed. The ratio of VG(irr.)/VG(unirr.) was found to be high in CR-39 than that in CR-39(DOP) exposed to the same reactor neutron fluence. The decrease in fission track densities with increase in neutron fluence was observed to be faster in CR-39 than in CR-39(DOP). This indicates that doping with dioctyl phthalate improves the radiation resistance of CR-39 detectors. It was observed that in detectors exposed to an alpha flux of the order of 9.36 × 106/ cm2, the fission track density was reduced by 11% and thereafter it remained constant. The results also indicate that thermal neutron fluence up to 7.01 ×1011neutrons/cm2does not affect the alpha and fission track densities. I.R. spectra were also studied to find out the nature of chemical changes produced by these radiations on CR-39.

ISSN:1042-0150    

DOI:10.1080/10420159408229032

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The optical absorption spectra of polyvinyle chloride, PVC, doped with Cd and Pb is presented. The effect of γ radiation doses in range of 2–200 Mrad on the fundamental absorption edge Λgwas determined. On the basis of quantitative analysis of obtained data, the calculated absorption coefficient, α, the absorption index, K, and the optical energy gap Eopt, were found to be radiation and dopant dependent. The results are discussed on the basis of the radiation induced degradiation of PVC.

ISSN:1042-0150    

DOI:10.1080/10420159408229033

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Thermoluminescence (TL) glow curves of lithium cesium sulphate ferroelastic crystals LiCsSO4doped with 0.5% of Os, Tb, Eu and Tl have been studied in the temperature range from room temperature to 300°C. Three peaks are observed at about 75, 125 and 225°C. The study includes also analysis of peak position and peak height of the glow curves with various dopant ions at different gamma radiation doses. The results are interpreted on the basis of point defects introduced interstitially or substitutionally admixtured into the host lattice. In spite of the host material being the same (LiCsSO4), the glow curve structure changes due to variation of dopant materials (Os, Tb, Eu, and Tl). The obtained results are discussed in detail. The applicability of such materials for accident dosimetry depends on the lower limit of dectection.

ISSN:1042-0150    

DOI:10.1080/10420159408229034

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor