摘要:

Charged particle energy loss has been calculated as a function of an impact parameter in a crystal. The quantum dielectric formalism is used when calculating the energy loss in the outer valence shell. Calculations have been carried out particularly for silicon including the zonal energy structure. Energy loss on inner electrons has been calculated in the semi-classical approximation and in the classical dipole approximation. The scope of applicability of the two approximations has been determined.

ISSN:0033-7579    

DOI:10.1080/00337577408232138

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

An analysis is made of the effect of dislocation vibration on the efficiency of a dislocation line as a sink for point defects. It is concluded that a dislocation will act as a better sink whenever the amplitude of vibration A is larger than the characteristic diffusion distance d = (D/4v)1/2wherevis the frequency of vibration andDis the diffusion coefficient of the point defect. BecauseDis so large for interstitial atoms it is not expected that this effect ever is important for interstitial atoms. The effect can be important for lattice vacancies and can counteract the effect of the stress field of a dislocation that makes a dislocation line a more efficient sink for interstitial atoms than for vacancies. The present theories of void growth in irradiated metals depend on the assumption that dislocation lines are better sinks for interstitials than for vacancies. If these theories are correct, then one can expect that void growth can be prevented by vibrating dislocations over a great enough amplitude at a high enough frequency.

ISSN:0033-7579    

DOI:10.1080/00337577408232139

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Specimens of Cu, Ag and Pt were irradiated in a fast neutron (f.n.) flux to a dose of about 2.5 × 1015n/cm2, yielding defect densities of about 4 × 10−7, and stored at 4.4 K. Specimens with the same prehistory were irradiated in a thermal neutron flux until the resistivity changes were the same as those recorded for the fast neutron irradiation. All samples were simultaneously annealed according to an isochronal programme.

ISSN:0033-7579    

DOI:10.1080/00337577408232140

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

A method for determining energy losses o f channeled particles from the backscattering spectra is described. The depth dependence of relative energy losses has been obtained for the (111), <100>, <110> and {110} channels in a tungsten crystal. It has been shown that the depth dependence of the fraction of channeled particles obtained with allowance for energy losses is well described by the exponential law at all depths.

ISSN:0033-7579    

DOI:10.1080/00337577408232141

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

In this paper, a study is made of radiation damage in silicon p n diodes produced by low dose neutron irradiation, and a comparison is made with the results of earlier work on carbon irradiated diodes. Particular emphasis is placed on the effects of damage on theI/Vcharacteristics of the diodes. The physical properties of the damage are studied by means of thermally stimulated current measurements, and further information is obtained from the temperature dependence of the reverse leakage.

ISSN:0033-7579    

DOI:10.1080/00337577408232142

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The stopping power of Ti, Mo, Ag, Ta and W for4He ions at energies of 500, 750, 1000, 1 250, 1500 and 1750 keV has been measured using the backscattering technique. The intensities of the backscattering yields have been employed in the calculation of stopping powers relative to those of Al and Au, which were used as reference materials. The experimental accuracy of the results is about ±3%, which does not contain the possible errors in the reference stopping powers. The results obtained are compared with the stopping power values found in the literature for these elements.

ISSN:0033-7579    

DOI:10.1080/00337577408232143

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Carbon fibres heat treated to temperatures in the range 1000-2600°C have been irradiated in the spent fuel pond to gamma doses between 1-1000 Megarads (MI). The mechanical properties of the irradiated fibres have been determined by single filament tests.

ISSN:0033-7579    

DOI:10.1080/00337577408232144

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Gamma radiolysis of cysteine in aerated and oxygen saturated acidic solutions leads to a chain decomposition of the solute with a corresponding formation of cystine and cysteine sulphinic acid. A reaction mechanism to explain the experimental yields is proposed and a rate expression forG(-CySH) evaluated. It is found that the calculated and experimentalG(-CySH) are in excellent agreement. It is also found thatG(CyS-SCy) and G(H202) increase with decreasing dose rate (I).G(Cys-SCy) andG(H2O2) plotted against I/✓Iare straight lines suggesting a radical-radical chain termination step.

ISSN:0033-7579    

DOI:10.1080/00337577408232145

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Single crystals of semi-insulating cadmium telluride have been implanted with 50 keV argon ions and 100 keV indium, tellurium and bismuth ions in an attempt to reduce the resistivity of the implanted layer by the injection of free carriers. Carrier concentrations were determined from sheet resistivity and Hall measurements. The highest percentage (∽ 30%) of electrically active ions to the total number implanted was measured for a dose of 1014indium ions/cm2implanted into a substrate held at 200°C. Although some activity was generated by bismuth ions, tellurium and argon ions produced no measurable electrical changes. The backscattering and channelling of hetium ions was used to study the damage produced by the different ions under different implant and annealing conditions. The technique was also used to measure the bismuth atom concentration retained by samples after various annealing stages. Some of the increases in electrical activity could be correlated with reductions in radiation damage. Above annealing temperatures of 400°C however, the increases in lattice disorder and sample resistivities were probably due to thermally generated active defects and loss of the implanted ion species.

ISSN:0033-7579    

DOI:10.1080/00337577408232146

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Specific helium-tungsten defect configurations suggested by Kornelsen to result from ion implantation following irradiation have been calculated. The calculations are atomistic in nature; those interatomic potentials involving the rare gases were determined from fist principles. The divacancy is found to be most stable in the second-neighbor configuration in the pure W lattice, but energetically prefers first-neighbors if it contains a Kr atom. We obtain good agreement with the experimental activation energies although we find certain configurations to differ slightly from those suggested by Kornelsen.

ISSN:0033-7579    

DOI:10.1080/00337577408232147

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor