Electronic Stopping Power Range Research Articles

X-ray diffraction study of the damage induced in yttria-stabilized zirconia by swift heavy ion irradiations

The lattice damage was investigated by x-ray diffraction techniques in yttria-stabilized zirconia single crystals with the (100) or (110) orientation upon irradiation with swift heavy ions (from 100-MeV C to 2.6-GeV U) in a broad electronic stopping power range (from about 0.3 to 48 keV nm−1). The θ-2θ scans show that no amorphization or change to a new crystalline phase occurs regardless of the ion and crystal features. However, the rocking curves (ω scans) and reciprocal space mappings show evidence of the mosaicity of the crystals, which is produced above a threshold electronic stopping power between 18 and 27 keV nm−1. This threshold is in agreement with our previous Rutherford backscattering spectroscopy/channeling spectroscopy data. Two kinds of damage phenomena are found: (i) nuclear-collision induced clusters of point defects which generate Bragg peak shifts and broadening in the 2θ-ω and θ-2θ scans, and (ii) electronic-excitation induced lattice damage yielding broad peaks in the ω scans above the stopping power threshold at high fluences.

The damage process induced by swift heavy ion in polycarbonate

To describe the damage process of polymer in the energetic heavy ion tracks by thermal spike model, polycarbonate (PC, Makrofol KG) foil stacks were irradiated with various swift heavy ions (1.158 GeV Fe 56, 1.755 GeV Xe 136 and 2.636 GeV U 238) in a very wide electronic stopping power range (from 1.9 to 17.1 keV/nm) and fluence range from 1 × 10 10 to 3 × 10 12 ions/cm 2. The amorphous processes and chemical degradation in the irradiated PC were studied by X-ray diffraction and Fourier transform infrared spectroscopy measurements. By applying the saturated track model, the mean damage radii of tracks of the amorphous and alkyne formation process were obtained for Fe, Xe and U ion irradiation, respectively. The results were validated by the thermal spike model. The analysis of the irradiated PC films shows that the predictions of the thermal spike model of Szenes are basically in quantitative agreement with the experimental results.

Swift heavy ion induced amorphisation and chemical modification in polycarbonate

Polycarbonate (Makrofol kg) film stacks were irradiated by 15.14 MeV/amu Xe 136 and 11.4 MeV/amu U 238 in the electronic stopping power range (7.6–17.1 keV/nm) and the fluence range from 9×10 9 to 1×10 12 ions/cm 2. The chemical degradation of the function group was investigated by Fourier-transform infrared (FTIR) spectroscopy and the crystallinity was analyzed by X-ray diffraction (XRD) measurement. FTIR results reveal that the material suffers serious degradation after irradiation. The alkyne group was found after irradiation and their formation cross-sections were evaluated. XRD measurements show the decrease of the main XRD peak intensity, confirming that the material to be amorphised under irradiation. The ion induced amorphisation cross-section was extracted from the fitting of the experimental data for different electronic energy loss irradiations. The degradation cross-section, the formation cross-section and the amorphisation cross-section versus electronic energy loss were discussed.

Damage morphology of Kr ion tracks in apatite: Dependence on thermal annealing

In this study, we have characterized the isothermal annealing (300°C) of 86Kr 32+ ion tracks in Durango fluoroapatite by means of channeling Rutherford backscattering spectrometry (CRBS) and chemical etching. The CRBS results were obtained for four 86Kr 32+ irradiation energies chosen in the electronic stopping power range: 1.83, 0.73, 0.22 and 0.10 MeV u −1. It was shown that the nuclear track effective radius ( R e) decreases with the annealing time. In that way, the crystalline reorganization phenomenon of previously amorphized bulk near the ion path is quantified for several ion energies. Chemical etching experiments associated with CRBS allowed us to qualitatively interpret the damage morphology evolution of nuclear tracks versus thermal treatment. It appears that crystal reorganization produces a defect fragmentation phenomenon, which is highlighted by chemical etching. This phenomenon is similar to the one previously detected during the slowing down of incident ions. In both cases, each type of track morphology can be defined by appropriate R e values. The experimental results were then applied to determine the evolution of the 238U fission-track structure under thermal annealing.

Swift heavy ion irradiation effects in α poly(vinylidene fluoride): spatial distribution of defects within the latent track

Poly(vinylidene fluoride) (PVDF) films are irradiated with different swift heavy ions (Sn, Kr, Ar, O) in the electronic stopping power range (4.3 to 11.8 MeV/amu). SHI irradiations induce a huge density of excitations and ionisations along the ion path. Fourier Transform Infrared (FTIR) transmission analysis allows us to study the decrease of crystallinity and the formation of unsaturations: alkynes and double-bonds either isolated or conjugated. The influence of irradiation parameters (absorbed dose, ion) is presented. The spatial distribution of the various defects within the latent track is studied.

Swift heavy ions effects in fluoropolymers: radicals and crosslinking

Fluoropolymers are irradiated with different swift heavy ions (O, Kr, Sn) in the electronic stopping power range (2.9 to 7.8 MeV/amu). The stable radicals left after irradiation are analysed by Electronic Spin Resonance (ESR). The nature of the radicals depends mainly on the chemical structure. After recombination of the radicals, a stable radical remains which is not a polyenyl radical and is best seen when ions of high Z and high fluences are used. It is characterized by ESR and consists of an isotropic singlet of lorentzian lineshape. In addition, it does not depend on the chemical composition nor on the nature of the crystalline phase. This new radical is believed to be located in the crosslinked structure where no hyperfine interactions are possible. Solubility measurements are performed and analysed by the Charlesby-Pinner equation. The results are in agreement with this hypothesis.

Effects of electronic energy loss in crystalline and amorphous Ni3B irradiated with high-energy heavy ions

Abstract Crystalline Ni-B (c-Ni-B) and amorphous Ni-B (a-Ni-B) ribbons have been irradiated at 80 K with 3 GeV Xe ions in order to study the influence of the alloy structure on the disordering process induced by heavy-ion electronic energy loss. The relative electrical resistance variation of the samples measured in situ during irradiation reveals that the effect is much larger in the amorphous than in the crystalline system. The behaviour of a-Ni75B25 is basically that of a-Fe85B15: an increase in the alloy resistivity at the beginning of the irradiation, certainly due to disorder production, followed by a large growth of the sample dimensions. Both effects are attributed to electronic energy loss. On the contrary, c-Ni3B does not present any measurable growth; high-resolution electron microscopy experiments on single crystals indicate that, in the electronic stopping power range studied, the resistivity increase is essentially due to elastic collision events. A model has been derived to account for the ...

Damage induced by high electronic stopping power in SiO 2 quartz

Heavy ion irradiations of α-quartz have been performed using 1 MeV 4He, 30 MeV 16O, 110 and 168 MeV 58Ni, 188 MeV 127I and 3.5 GeV 238U. The induced damage has been determined using channeling Rutherford backscattering with a 4He beam of 3 MeV. In the electronic stopping power range investigated (1.5–104 MeV cm 2 mg −1), the electronic stopping power damage efficiency increases by at least four orders of magnitude. Moreover, irradiations have also been performed in channeled and random conditions. The influence on the track creation mechanism of inner-shell excitations was checked by comparison between channeling and random irradiations. It is not necessary to invoke inner-shell excitations followed by an Auger decay in order to account for the damage efficiency.