摘要:

The trapping of3He and4He ions with energies between 10 eV and 40 keV in polycrystalline Al and Pt and in BeO and anodic Al2O3films has been studied. The measured collecting efficiencies vary from a few times at 10−4at eV to ∼ 1 at energies above 10 keV. Except for very low implantation energies (less than ∼ 1 keV), where initially trapped particles are probably released by diffusion, we derive reflection coefficients and compare with current theoretical calculations. Our reflection coefficients obtained for implantation energies larger than 1 keV in Al and Pt are in excellent agreement with calculated values. We have also measured the dependence of the trapping probability on the angle of incidence for 3 keV He ions in Al and Pt.

ISSN:0033-7579    

DOI:10.1080/00337578008209145

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The determination of void volumes from transmission electron micrographs is an essential part of evaluating the void swelling in irradiated materials. Three commonly-used methods of determining the void volume are investigated.

ISSN:0033-7579    

DOI:10.1080/00337578008209146

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Analytical calculations of power-law damage and ionization distributions, done earlier for equal projectile and target-atom masses, are extended to the unequal-mass case, in which the integral equations are inhomogeneous. (The unequal-mass range distribution is given by a homogeneous equation, and so was treated in the earlier work.) More terms are necessary in the asymptotic expansion of the Mellin transform of the distribution than for the homogeneous case; these expansions are given explicitly. The large-depth asymptotic behaviour of the distributions is determined by the projectile range or by the range of the highest-energy recoils, whichever is the greater. Some calculated distributions are shown.

ISSN:0033-7579    

DOI:10.1080/00337578008209147

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Statistical distributions of rhomboidally shaped nuclear track holes in mica have been analyzed using computer image analysis. Experimental results are compared with a theory based on quadratic holes with uniform shapes. The single-hole areal dispersion is evaluated for hole areas between 6 and 320 (μm)2. It is found to range between 5 and 13% FWHM. The accessible parameter range for nuclear track filters concerning nominal porosity, hole size, and areal density is delineated. Upper limits for transmission losses in particle filtration processes are given.

ISSN:0033-7579    

DOI:10.1080/00337578008209148

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Si implanted at 200°C is known not to form an amorphous layer and to anneal less well than Si implanted at room temperature. Reasons for this difference and the implications of gradual wafer heating during implantation were studied.

ISSN:0033-7579    

DOI:10.1080/00337578008209149

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The theory of K-electron ionization probabilities by heavy relativistic particles (protons, mesons, ions) as a function of an impact parameter is treated in the virtual photon approximation. This approximation can be used to calculate the K-X-ray yield excited by channeled negative and positive particles. For negative particles there is an enhancement of the yield under channeling conditions as compared with the random yield. The present theory predicts a considerable decrease of the depth of the K-X-ray yield dip when a positive particle velocityv→c. A comparison of the theoretical results with the experiments on total ionization cross sections has been performed and the agreement is good.

ISSN:0033-7579    

DOI:10.1080/00337578008209150

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Thin copper foils were irradiated with 650 keV electrons at 10 K in a high-voltage electron microscope (HVEM) to doses φ in the range 2 × 1023electrons/m2≲ φ ≲ 2 × 1025electrons/m2and then annealed in situ up to room temperature and outside the HVEM between room temperature and 470 K. During irradiation visible defect clusters were formed only at φ ≳ 2.5 × 1024electrons/m2. At smaller doses defect clusters became visible after annealing at 50 K. Between 50 K and 120 K further clusters, mainly dislocation loops on {111} planes, appeared. Above 120 K, particularly between 160 K and 300 K, some of the dislocation loops became glissile. They glided out of the specimens or agglomerated to larger clusters of frequently complex shapes. As a consequence, between 160 K and 300 K the cluster density decreased strongly, whereas the mean cluster size increased monotonously through the entire range of annealing temperatures covered. Contrast analyses between 180 K and 400 K revealed that the great majority of the dislocation loops were of interstitial type. At 470 K a new type of small clusters emerged, presumably of vacancy type. These observations are compared with other studies on electron-irradiated copper and with the current models of radiation damage in metals.

ISSN:0033-7579    

DOI:10.1080/00337578008209151

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

A semiclassical model for the calculation of the heavy ion electronic stopping cross section in a wide energy range is proposed. Two mechanisms of energy loss are considered: (i) energy loss to excitation or ionization of the target electrons by the partly screened field of moving ion nucleus is calculated in the binary encounter approximation (BEA) and (ii) energy to electron exchange is calculated on the basis of the modified Firsov theory taking into account electron-electron scattering. For the determination of the average momentum transferred in a collision of two electrons the BEA is also used. The simple universal projectile velocity dependence of the average effective ion charge is applied in calculations.

ISSN:0033-7579    

DOI:10.1080/00337578008209152

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The surface disorder created by 1 MeV He+bombardment of Si has been studied for random and aligned ⟨111⟩ bombardment at 40 K and 300 K. For the aligned beam it is found that the surface disorder is much larger than can be predicted by bulk damage production and that the disorder production rate is only weakly dependent on temperature and alignment. The observations suggest a component of beam induced annealing present at 40 K. The energy dependence of the surface disorder production is reasonably well explained by a surface atom recoil model in which the initial surface oxide atoms can be recoiled to create damage. When the damage production caused by low dose heavy ion bombardments is increased using MeV He+beams, the surface damage caused by the analysing beam may form a large part of the total damage, unless care is taken to minimise the analysing beam dose.

ISSN:0033-7579    

DOI:10.1080/00337578008209153

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The creation and annealing of defects introduced at 78 and 280 K by 2 MeV electron irradiation ofp-type silicon doped either by boron or by aluminium have been studied by using Hall effect, conductively and minority carrier diffusion length measurements.

ISSN:0033-7579    

DOI:10.1080/00337578008209154

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor