摘要:

Stopping powers of aluminium and tin in the energy range 3–10 MeV for4He ions, in the range 3–17 MeV for7Li, 8–20 MeV for11B, 10–23 MeV for12C, 9–22 MeV for14N, and 11–25 MeV for16O ions have been determined by using the transmission technique. The experimental stopping powers are compared with the predictions of semiempirical models. The available literature data is surveyed and compared with the present data.

ISSN:1042-0150    

DOI:10.1080/10420159108220624

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A method to evaluate fission yields in experiments of induced and spontaneous fission which use fissionable target materials in the configuration of contact with dielectric track detectors has been developed. The effect of energy absorption of the fission fragments by the target sample, and the optical resolution power for observation of etched fission tracks are taken into account in deducing the total efficiency factors resulting from the use of targets of different thicknesses. With this method, the conditions to give the maximum observable density of etched tracks can be obtained, which is important to experiments of low fission yields. A number of useful formulae applicable to mica and plastic track detectors for evaluation of fission yields are reported. The method has been successfully applied to recent photo-fission experiments of low fission yields, and it can also be useful in the study of other fission cases as well as in applications to fission-related problems.

ISSN:1042-0150    

DOI:10.1080/10420159108220625

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The chemical defects produced by electron irradiation of P(VDF-TrFe) have been studied using XPS and UV spectroscopy. As a result of irradiation it was found that the fluorine content was decreased, mainly through HF desorption. Correlatively, double bonds and conjugated double bonds were produced. As a consequence, the concentration of dipole moments and the dipolar energy were reduced in consistency with the depression of the Curie temperature after irradiation.

ISSN:1042-0150    

DOI:10.1080/10420159108220626

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Zone-leveled and hot-pressedn-andp-type Si80Ge20alloys were irradiated with neutrons to a fluence of 4 × 1018n/cm2and to a fluence of 5.4 × 1019n/cm2at a temperature of approximately 200–300°C. The main purpose of this work was to determine the effect of neutron irradiation on the thermoelectric properties of these alloys. The carrier concentration and mobility (and hence the resistivity) were measured at room temperature while the thermal diffusivity was measured at 177–192°C both before and after the irradiation and after each subsequent 2 hour heat-treatment at 350°C, 600°C and 1000°C. The irradiation increased the resistivity significantly but the thermal conductivity decreased only by about 10–15%. This would tend to indicate that radiation produced only small defects (single pairs and small vacancy chains). The samples all returned to almost exactly their pre-irradiation state after the 1000°C anneal.

ISSN:1042-0150    

DOI:10.1080/10420159108220627

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The depth distribution of phosphorus in silicon after high energy implantation in the range of 8 to 30 MeV was investigated using spreading resistance profiling. The values for the projected ranges taken from experimentally determined charge carrier profiles agree well with theoretical predictions (TRIM). However, the shape of the measured phosphorus depth distributions is at variance with the calculation. Inclusion or exclusion of electronic straggling in the calculations does not significantly change the theoretical phosphorus depth profiles.

ISSN:1042-0150    

DOI:10.1080/10420159108220628

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Data are reported for stored energy release from Bi4Ge3O12after He+ion implantation and/or gamma ray irradiation. Approximately 0.2% of the ion beam energy is stored and subsequently thermally released during defect annealing. The data imply that the complex defects formed by ion implantation lead to very significant quantities of energy storage at each defect site.

ISSN:1042-0150    

DOI:10.1080/10420159108220629

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The Ll2Ni3Al compound is known to be disordered by ion or electron irradiation, while preserving its crystalline structure. In this work, embedded-atom potentials are used to investigate the change of internal energy of the crystal and of the lattice parameter as a function of the degree of long range order. Various vacancy-interstitial configurations are investigated in order to explore the possibility of a substantial point defect buildup. It is found that spontaneous recombination is a function of the nature of the interstitial, the vacancy-interstitial distance and the characteristics of the atom environment of the pair. The vacancyinterstitial interaction is also found to be, in some cases, dependent on the local atomic environment. Local disorder, moreover, can produce in some cases interstitial trapping. The implications of the effects obtained in the present simulations on the possibility of an irradiation-induced amorphous transition are discussed.

ISSN:1042-0150    

DOI:10.1080/10420159108220630

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The parameters of the depth profiles of Sb atoms implanted into titanium were measured using standard RBS technique. The measured profile moments are compared with theoretical values calculated by means of TRIM program. The experimental projected ranges are lower by 15–25% than the theoretical ones but these differences may partly be explained by target sputtering. The measured range stragglings agree with those calculated within few percent. Extremely high values of profile skewness and kurtosis are found for shallow profiles.

ISSN:1042-0150    

DOI:10.1080/10420159108220631

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Bleaching of F centers in gamma irradiated NaCl crystals at room temperature and elevated temperatures using laser pulses from pulsed laser systems is studied in this paper. The rate of decay of F centers is monitored and the decay constants are evaluated. A comparison on the decay kinetics is made for CW and pulsed bleaching with a He-Cd laser. F center to C center conversions using a thermo-optic scheme are carried out with nanosecond dye laser pulses in gamma irradiated NaCl crystals.

ISSN:1042-0150    

DOI:10.1080/10420159108220632

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The question of structural instability during charging under electron irradiation in small particles and amorphous phases is semi-quantitatively explained. Experimental observations in electron microscopes during irradiation have reported that when the particle radius is less than ∼ 10 Å complete random diffusion of atoms is seen over the whole particle volume, whereas for larger sizes, only local areas fluctuate. In amorphous structures similar local fluctuations are seen during high flux electron irradiation. Using thermodynamic arguments an empirical criterion is used to define the critical size scale for instability when the coulombic stresses set up inside a particle enhance the point defect concentration such that the flux of atoms inside the particle reaches some critical value. Agreement is seen between the predicted size ranges and experimental results. Enhanced diffusion due to charging may also account for anisotropic growth in materials when irradiation is localized or formation of heterogeneous interfaces creates anisotropy.

ISSN:1042-0150    

DOI:10.1080/10420159108220633

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor