摘要:

Formation of some enigmatic haloes (such as giant, super-giant, intermediate types, dwarf, polonium haloes etc.) has been explained, in an unified approach, on the basis of α-recoil and α-particle damage density distribution from the decay series of radon and thoron diffusing out of the highly radiation damaged inclusion and the surrounding host matrix. It is shown that the origin of these haloes can be explained without invoking the presence of any hitherto undiscovered radioelement or superheavy element in the halo inclusion. An order of magnitude estimate of the diffusion coefficient has been made. The data available in literature on different haloes have been shown to fit in well with the diffusion mechanism.

ISSN:0033-7579    

DOI:10.1080/00337578008207089

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The characteristic times and lengths involved in the problem of heat flow through a semiinfinite Al sample irradiated with nanosecond laser pulses are discussed with reference both to the underlying physics and to the numerical solution of heat diffusion equation. Laser pulse energies allow sample melting, but no vaporization. The numerical solution proceeds via subdividing the sample into layers of thickness Δx. After describing the mechanism of heat flow through these layers, the Δx-dependence of some significant quantities is discussed and found negligible. The temperature time behaviour at different sample depths is given, showing latent heat effects; results for the solid-liquid interface motion, cooling rates, energy deposition in the front layer are presented and their dependence on the laser pulse parameters discussed qualitatively. Finally the connection of the present calculations with some recent experiments is discussed and the conditions under which neglecting of undercooling effects is a consistent procedure are ascertained.

ISSN:0033-7579    

DOI:10.1080/00337578008207090

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Many features of the results obtained by numerically solving a heat diffusion equation, which allows for melting and resolidification of an Al sample under irradiation by a laser pulse, may be reproduced analytically by means of the combined use of an intuitive heat balance principle, evolving in time, and a simple formula for the position in time of the melting-resolidification front. Analytical expressions have been obtained for several quantities, as average velocities for the liquid-solid interface motion, maximum melted depth, maximum surface temperature, duration of the surface melted phase, heating and cooling rates. These expressions have been tested against the actual numerical results, showing a good overall agreement. They also permit a deeper understanding of the dynamics of the whole heat flow and its dependence on the laser pulse parameters.

ISSN:0033-7579    

DOI:10.1080/00337578008207091

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Thermoluminescence spectra of CaS:Bi dosimeter have been recorded for the two glow peaks occuring at 60°C and 200°C. Due to the presence of two groups of traps, retrapping mechanism has been investigated in order to get the best performance out of this dosimeter. The effect of annealing, storage and pre-heating on the spectral characteristics has also been studied. The shift of the band maximum to longer wave length at higher temperature has been briefly discussed on the basis of one kind of luminescence centres.

ISSN:0033-7579    

DOI:10.1080/00337578008207092

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

An apparent charge of local vibration due to the vacancy-oxygen complex (absorption bands 835 and 884 cm−1) was determined on the basis of joint measurements of IR-absorption, EPR and the temperature dependencies of the Hall effect on 1 and 3.5 MeV electrons irradiatedn-type silicon samples. The value obtained enables us to apply the IR-absorption method to determine the absolute values of the concentration of vacancy-oxygen complexes in silicon at superhigh irradiation doses (∼ 1018- 1020cm−2) under the conditions when their concentration was near to the limiting one. The IR measurements showed that within the above dose range the complex concentration varies slightly and is ∼4.1017cm−3, with the concentration of the interstitial oxygen uncombined in complexes remaining rather high (∼4.1017cm−3) even at the dose of ∼1, 16.1020cm−2. An analysis causing saturation of the A-centres concentrations with the dose in the presence of a large amount of free interstitial oxygen has been done in the work. The question of the limiting change of the semiconductor crystal parameters resulting from electron irradiation is discussed.

ISSN:0033-7579    

DOI:10.1080/00337578008207093

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Infrared absorption measurements have been made on GaAs, GaP and InP following multiple energy bombardments by either protons or deuterons. Localized mode frequencies have been determined for both H and D in GaAs and Gap. Estimates of the relative damage have been made from the induced electronic absorption below the band gap energy. Preliminary results of annealing studies are presented. This work relates to recent publications which show that the carrier removal rate in deuteron irradiated GaAs is twenty times greater than that obtained with proton irradiations.

ISSN:0033-7579    

DOI:10.1080/00337578008207094

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Zinc telluride samples of differing degrees of purity have been implanted with 100 keV Ar+ions and subjected to post-implantation isochronal annealing treatments at various temperatures in the range 50–500°C. After each anneal the cathodoluminescence emission spectra were recorded with the samples at liquid helium temperature. Annealing of the less pure argon-implanted zinc telluride in the range 300–450°C produced a new emission band at 537.8 nm (2.305 eV) which was shown by time-resolved spectroscopy and temperature dependence of emission measurements to result from donor-acceptor pair recombination involving a previously-unobserved acceptor centre which has a hole binding energy of 96 meV and which is tentatively believed to involve lithium impurity.

ISSN:0033-7579    

DOI:10.1080/00337578008207095

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Nous présentons dans cet article les résultats d'une étude expérimentale par microscopie électronique, des défauts d'irradiation électronique dans des lames minces monocristallines d'antimoine (structure rhomboédrique A7) d'orientation proche de (111). Nous avons tout d'abord étudié l'influence d'une composante coin sur la montée des dislocations au cours de l'irradiation dans un microscope a haute tension, en irradiant des dislocations mixtes dont nous avions préalablement détermine le vecteur de Burgers. Contrairement à la forme hélicoïdale prise par les dislocations vis dans d'autres matériaux, les dislocations mixtes adoptent dans l'antimoine une configuration presque plane (proche du plan (b, u)). par formation de dipôdes dont l'allongement permet l'accommodation de nouveaux défauts ponctuels. Nous avons également détermine, par les techniques habituelles de contraste, la nature des amas de défauts ponctuels qui se forment essentiellement au voisinage des dislocations; il s'agit de trois familles équivalentes de boucles lacunaires parfaites, de vecteur de Burgers ½[011], ½[101] et ½[110].

ISSN:0033-7579    

DOI:10.1080/00337578008207096

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Changes in thermoluminescence (TL) sensitivity and thermally stimulated conductivity (TSC) of natural quartz crystals induced by X-ray irradiation have been studied by utilizing a bleaching procedure. The magnitude of the temperature shift between the TL and TSC peaks at about 330 K depends on the thermal treatment of the sample. The experimental results can be explained by a phenomenological concept based upon a simple kinetic model. This model predicts that the density of free recombination centres in a preirradiated sample will be increased by thermal activation. This prediction is in good agreement with the predose model proposed earlier.15

ISSN:0033-7579    

DOI:10.1080/00337578008207097

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

It is shown that after implantation of a dose of impurity into a solid, the diffusion coefficient of impurity atoms in the selvedge of the solid can be determined by measuring the desorption flux as a function of time. The diffusion coefficientD=D0exp(-Q/kT) of potassium atoms in tungsten is found to be independent of the distance to the surface over 25 lattice layers. AroundT= 1900 K we obtainD0= 2.9 × 10−8m2/sandQ= (3.80 × 0.25) eV.

ISSN:0033-7579    

DOI:10.1080/00337578008207098

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor