Annealing behaviour of heavy ion radiation damage in muscovite is studied at different temperatures. The activation energies Ea for annealing of heavy ion tracks of different energies, viz. 93Nb(18.0 MeVn −1), 208Pb(17.0MeVn −1), 238U(10.0MeVn −1) and 252Cf(fission fragments), are found to be the same (∼0.97 eV). The concept of a single activation energy as an intrinsic property of the detector seems to be fully justified.
A new theory of ion reflection from a smooth amorphous solid surface is developed. A continuous potential is introduced for describing the ion reflection from amorphous surfaces at low glancing angles. It is shown that the difference, between a true surface potential and a continuous one could be taken into account in terms of a correction factor, thus yielding a Fokker-Planck-type equation for a particle distribution in angle and transverse coordinate. Diffusion coefficients included in this equation are calculated with allowance for atom discrete positions and ion-electron collision effect. On the basis of the derived kinetic equation the angular and energy ion distributions in a reflected beam are analyzed. The presented theory, somewhat modified, can be used for describing ion reflection from a crystal surface as well.
A comparison study of the photoluminescent (PL) spectra in pure and ultra-pure irradiated and annealed germanium has been performed. Some radiative recombination centres including impurities have been found. The spectra of samples bombarded by neutrons were found to include, along with the lines from intrinsic defects (Z, Y, X, W, V), the centres due to hydrogen and oxygen impurities (the lines T1, T2, U). A considerable number of the lines (A1-A3, B1, B2, C, D1, D2) in the PL spectra of crystals exposed to gamma-quanta and electrons were identified with the centres including carbon atoms. Such a great set of lines, presumably, results from the transformation of the above mentioned complexes in the course of annealing. The observed differences in the PL spectra within 0.72 to 0.74 eV range probably indicate a contribution of several types of intrinsic defects and other impurities, along with carbon, to complexing.
The changes occurring upon pulsed laser irradiation on maraging steel of 69Fe-18Ni-8Co-5Mo composition have been studied using Conversion Electron Mossbauer Spectroscopy (CEMS), Scanning Electron Microscopy (SEM), Internal Friction (IF) and aqueous corrosion. It is observed that an austenitic phase in the upper layer is retained without much change in chemical composition for the pulsed laser treated sample. Mechanical bulk properties are not affected by this treatment, however betterment in corrosion resistance is achieved.
The annealing behaviour of heavy ion radiation damage trails in Lexan Polycarbonate is studied on the basis of two different models proposed by Modgil and Virk11 and Price et al. 15 The shortcomings of these two approaches are brought into focus and a new formulation proposed to remove some inherent drawbacks.
We have used ion implantation of 30 keV48Ti+ ions into a-Si films at nominal doses of 1020-1021 ions/m2 to fabricate coherent silicide layers. Characterization of these layers and study of their annealing behaviour were carried out using XRD and RBS techniques. We find that the layers are a mixture of Ti5Si4, TiSi, TiSi2 and Si. On annealing at relatively lower temperatures (up to ∼ 300° C), predominant silicide phases present in the layer are Ti-rich, such as Ti5Si4 and TiSi. At higher temperatures, the Ti-rich layer has a tendency to consume unreacted Si from the film and to form a predominantly Si-rich silicide layer. A structure of silicon different from the diamond cubic structure is noticed in these implanted layers.
Direct numerical solution of the Boltzman transport equation for incident ions and knocked-off atoms of the target is applied for range and damage calculations. The influence of physical parameters in a model of ion stopping in matter on the obtained range and damage distribution is investigated in the range of ion energies from 1 KeV to 1 MeV. All the examined interatomic potentials give close values of mean depths and higher moments of range and damage distributions. The influence of differences in electronic stopping is also studied. The obtained results are compared with experimental data and the results of other calculations.
By a careful analysis of the electron loss spectra of some alkali halide crystals after ion irradiation we have demonstrated that defect generation depends on ion energy nonmonotonously. This effect is connected with inelastic interaction between ion and surface atoms.
Radiation defect accumulation in 60Co γ-ray-irradiated n-type Si single crystals (ρ=150ωcm) with various densities of dislocations (ND = 1 × 104 to 1 × 107 cm −2) introduced at plastic deformation was studied. The temperature dependences of the Hall coefficient were measured. The probabilities of interaction of vacancies with oxygen, phosphorus atoms, and dislocation line elements were determined. It has been established that with the increase of ND they can increase at the expense of complication of dislocation structure, decrease during formation of impurity atmosphere near dislocations and compensation of deformation fields, and they do not change if complex formation of vacancies with impurities occurs far from dislocations. Kinetics of A- and E-centre accumulation in the crystals containing dislocations with different impurity atmosphere was described.
When silica is irradiated by 80-keV D+ ions or RF plasma of D2 gas, deuterium is trapped in the silica forming Si-OD bonds. The deuterium, trapped as OD bonds, is desorbed from the silica upon heating to form some release products. The thermal detrapping process corresponds to decrease of OD bonds and was studied by measurement of infrared Fourier transform spectroscopy (FTIR). The release products HDO, D2O, HD, and D2 were measured by quadrupole mass spectroscopy (QMS). The detrapping and release processes of trapped deuterium were studied by simultaneous measurement of FTIR and QMS. Since the release spectra of HDO, D2O, HD, and/or D2 correspond to the decrease spectra of OD bonds, these release products are formed by thermal decomposition of OD bonds. The formation of water (HDO, D2O) and hydrogen (HD, D2) depends upon concentration of pre-existing OH bonds and deuterium injection methods (80-keV D+ implantation or RF D2 plasma irradiation).
The analysis of the deflection efficiency of high-energy proton beam with a bent crystal has been made and the optimum length of the bent crystal estimated. A bent Si crystal was used in the experiments at Serpukhov circular accelerator with 70 GeV proton beam. The results of the formation of a narrow proton beam and measurements of the beam phase volume are discussed.
Electrical properties of oxygen-related donors formed in Cz-Si at 600°C are investigated. The formation of these donors was found to be very sensitive to the oxygen concentration. Electrical measurements on heat-treated and irradiated samples made it possible to outline the distribution of single and double donors over their ionization energies. A similarity in electrical properties of oxygen-related donors formed in Cz-Si at 450° and 600°C is discussed.
Makrofol polycarbonate—one of the widely used materials for making nuclear track filters, has been studied for its transparency to light (Λ = 350 nm to 950 nm). Also the optical transmission and IR-spectroscopy results on the Makrofol foils, forming nuclear track filters by irradiating with 14 MeV/n 238U ions, with and without post-irradiation UV and γ-exposures, are presented. Studies have been extended to these filters to investigate the variation of percentage transmission with etch-time, pore diameter, at different values of Λ.
This paper reports the first experimental results on shattering solids by irradiating supercurrent proton beams. The obtained results have been compared with the data by irradiating pulse supercurrent electron beams and have been discussed. A calculation of the solid dielectric doses by irradiating 14 MeV neutrons has been carried out. By applying the present experiment and calculation the threshold intensities of the pulse thermonuclear fusion neutron fluxes, whereby the investigated crystals may be shattered, have been estimated.
The results of ESR investigation of atomic hydrogen centres in γ-irradiated polycrystalline Me(OH)2, where Me = Mg, Ca, Sr, Ba, are reported. Several types of H0-centres having different hyperfine constants AisO were obtained in hydroxides depending on pre-treatment temperature. It has been established that the spin density on hydrogen nucleus decreases with increasing atomic number of cations. The analysis of the obtained data was performed in semiempirical Mulliken-Volsberg-Helmholtz's a molecular orbital method terms in supposition that H-atoms occupied interstitials with four OH-ions or three OH-ions and one cation in the nearest surrounding. Satisfactory agreement between experimental and calculated values of Aiso was achieved.
A method is presented for damage energy distribution calculations for incident energies above the electronic stopping power maximum. The method is based on the approximate solution of the transport equation for stationary angular flux developed in a previous paper. In order to compare the results with experimental data and other theoretical rates, calculations were made at incident energies under the electronic stopping power maximum (for Al ions at 4.6, 5 and 5.4 MeV incident energies in Al target and for 46.7 MeV Ni in Au target). Combining the large energy transfer approximation and the path length approximation, we obtain a simple approximation for the calculation of the “tail” of the damage rates at high incident energies.
In thermoluminescence dating, in which the TL of naturally occurring minerals is used to obtain past radiation doses, the responses of these minerals to both alpha and beta irradiations must be measured. In this paper a new parameter, the-b-value, is introduced to relate these two responses in the low-dose linear response regions. It is then shown that in simple models for the high-dose non-linear responses, the b-value concept can still be applied and that it can be determined in a straightforward manner using equivalent beta dose and equivalent alpha track length measurements. The b-value equivalent dose so determined may be used in the standard age equation for archaeological and geological materials without errors due to non-linearity. An example supporting the model is given.
Ceramic powders can be prepared in a radiation damaged condition by bombardment with 1 to 4 MeV ions of Ne, Ar, Kr or Xe. The powder particle sizes are chosen to correspond to the ion beam penetration but are found to be considerably greater than the calculated ion ranges for powders becoming metamict. A monolayer of powder particles of sizes up to about 5 μm is sedimented onto long strips of metal foil with an area density of about 1 mg-cm-2. The ion beam is rastered to irradiate an area as the foil rotates on a drum through the beam. Alternately, monolayers of powder particles can be prepared by the use of a very-thin layer of rubber cement. By these techniques, plates can be prepared for irradiation in the ion beam and also for direct insertion into an X-ray diffractometer. Gram amounts of irradiated material can be collected in a few hours for studies such as powder X-ray diffraction, SEM, Differential Scanning Calorimetry and density measurements. Thus, zircon ZrSiO4 becomes non-crystalline or metamict under ion bombardment with a damage cross-section DM = 0.33 nm-2 for Ar (3 MeV) ions; one gram can be rendered 50% non-crystalline after two hours of irradiation by a 6 μA ion beam.
Reconstruction processes proceeding during annealing of radiation defects in60Co γ-ray-irradiated (T in≲50°C) n-type silicon (ρ=20 to 250 Ω cm) grown by the vacuum float-zone technique were investigated. The temperature dependences (80 to 400 K) of charge carrier concentration and life time were measured at various stages of annealing (Tann= 100 to 600°C). It has been established that during annealing theE-centres interact with carbon-containing complexes of interstitial type or are transformated into more complicated complexes of phosphorus-divacancy. Phosphorus electrical activity is completely restored after annealing of phosphorus-divacancy complexes atT ann = 400 to 500°C. The energy level of phosphorus-divacancy complexes was found to be in lower half of forbidden gap (ΔEr = 0.34 eV). The cross-section [sgrave] p of hole capture by these complexes was determined to be equal to 4 × 10−15 cm2. It was concluded that the phosphorus-divacancy complexes are singly charged acceptors.
