Effects of the radiative recombination on the intensity and polarization of the Ly-α emission of hydrogen-like ions

The intensity ratio of the to photon emission is analyzed for hydrogen-like Fe²⁵⁺ ions if their excitation arises in a plasma not only from the electron impact but also due to the radiative recombination (RR) of initially bare Fe²⁶⁺ ions. Under such conditions, the intensity ratio and the (degree of) linear polarization of the Ly-α₁ line are explored for collisions with an electron beam over a wide range of kinetic energies up to 50 keV. Apart from the direct population of the 2p_1/2,3/2 levels via the RR of bare ions, the contributions from radiative cascades and higher multipoles are taken into account by applying a fully relativistic theory for the motion of the electrons and the electron-photon coupling. Our calculations show an overall small effect of the RR upon the degree of the Ly-α₁ polarization as well as the intensity ratio under usual plasma conditions. However, the effects from the RR of initially bare ions may become significant at electron beam energies , for plasma conditions far away from ionization equilibrium with a relatively large proportion of bare Fe ions, as it may be realized in electron-beam ion trap experiments.     

Relativistic configuration interaction calculations for the Kα and Kβ X-ray satellites of iron

Multi-configuration Dirac-Fock and relativistic configuration interaction calculations with the Breit interaction, quantum electrodynamics, and finite nuclear mass corrections were carried out in the extended optimal level scheme for the transition wavelengths, electric dipole transition rates, and oscillator strengths of the Kα and Kβ X-rays from Fe XVII through Fe XXV. The calculated values were compared with the available data on He-like, Li-like, Be-like, and F-like iron, and were in very good agreement. These data provide reference values for level lifetime, charge state distribution, and average charge of iron plasmas.     

Fine-structure effects on the polarization of Kα1 radiation from heavy, highly-charged ions

Radiative decay of heavy, few-electron ions following electron capture is studied within the framework of the density matrix theory combined with the multiconfiguration Dirac-Fock approach. Special attention is paid to the linear polarization of the decay X-ray photons. Detailed calculations have been carried out, in particular, for the Kα₁ (1s2p_3/2^1,3P_1,2 →  1s²¹S₀) transition in helium-like uranium U⁹⁰⁺ ions. For this line, the characteristic radiation is almost unpolarized as a result of the superposition of its fine-structure ¹P₁ → ¹S₀ and ³P₂ → ¹S₀ components which are strongly linearly polarized in perpendicular directions.     

Influence of chemical binding on the neutron width Γn

In the studies of the broadening of neutron resonance reactions, it has always been assumed that one can neglect the dependence of the neutron width Γ_n on the initial and intermediate state of the lattice when the capturing atom is bound in a crystal. In this paper, we calculate the mean value of the resolvent of the Schrodinger equation to derive a formal expression of Γ_n that shows that the neutron width depends on the initial and intermediate state of the lattice after formation of the compound nucleus. An application is made to harmonic oscillators targets.     

Point by Point model calculation of the prompt neutron multiplicity distribution P(ν) for spontaneous and neutron induced fission of actinides

The prompt neutron multiplicity distribution P(ν) is a very sensitive quantity which depends on the model calculation of the multi-parametric matrix ν(A,TKE) and on the fission fragment distributions.     

Study on the angular dependence of personal exposure dosimeter – Focus on thermoluminescent dosimeter and photoluminescent dosimeter

Radiation management departments place more emphasis on the accuracy of measurements than on the increase in the average dose and personal exposure dose from the use of radiation equipment and radioactive isotopes. Although current measurements are taken using devices, such as film badge dosimeters, pocket dosimeters and thermoluminescent dosimeters (TLDs), this study compared the angular dependence between the widely used TLDs and photoluminescent dosimeter (PLDs) in order to present primary data and evaluate the utility of PLD as a new dosimeter device. For X-ray fluoroscopy, a whole body phantom was placed on a table with a setting for the G-I technical factors fixed at a range of approximately 40 cm with a range of ±90° at an interval scale of 15° from the center location of an average radiological worker for PLDs (GD-450) and TLDs (Carot). This process was repeated 10 times, and at each time, the cumulative dosage was interpreted from 130 dosimeters using TLDs (UD-710R, Panasonic) and PLDs (FGD-650). The TLD and PLD showed a 52% and 23% decrease in the depth dosage from 0° to ?90°, respectively. Therefore, PLDs have a lower angular dependence than TLDs.     

Isotope distribution of iridium in the interaction of 47MeV／nucleon^12C with^197Au

Thick gold targets were bombarded with 47 MeV/nucleon ^12C ions and the radioactive isotopes of iridium and platinum were produced through the multi-nucleon transfer reactions. The production cross-sections of iridium isotopes in the reactions have been determined by a combination of radiochemical separation and off-line γ-ray spectroscopy technique. The obtained Ir isotope distribution was compared with those obtained in other experiment as well as calculated by the statistical model.     

Effects of γ-ray irradiation on the C-V and G/ω-V characteristics of Al/SiO2/p-Si (MIS) structures

The effect of the ⁶⁰C_o (γ-ray) exposure on the electrical characteristics of Al/SiO₂/p-Si (MIS) structures has been investigated using capacitance-voltage (C-V) and conductance-voltage (G/ω-V) measurements. The MIS structures were stressed with a bias of 0 V during ⁶⁰C_oγ-sources irradiation with the total dose range from 0 to 25 kGy. The C-V and G/ω-V characteristics were measured at 500 kHz and room temperature before and after ⁶⁰C_oγ-ray irradiation. The results indicated that γ-irradiation caused an increase in the barrier height Φ_B, interface states N_ss and depletion layer width W_D obtained from reverse bias C-V measurements. The series resistance R_s profile for various radiation doses was obtained from forward and reverse bias C-V and G/ω-V measurements. Both C-V and G/ω-V characteristics indicate that the total dose radiation hardness of MIS structures may be limited by the decisive properties of the SiO₂/Si interface to radiation-induced damage. After γ-irradiation, the decrease in capacitance of MIS structure results in the increase in the semiconductor depletion width.     

Measurement of cross sections for (n, 2n), (n, p) and (n, α) reactions on germanium isotopes induced by 14 MeV neutrons

Activation cross sections at the neutron energy about 14 MeV on germanium isotopes have been measured, employing the activation technique and γ-ray spectrometry. The data of the cross section are reported for the (n, 2n), (n, p) and (n, α) reactions. The neutron flux was determined using the monitor reactions ²⁷Al (n, α) ²⁴Na and the neutron energies were measured by the method of cross section ratios for ⁹⁰Zr (n, 2n) ⁸⁹Zr to ⁹³Nb (n, 2n) ^92mNb reactions. The measured results were compared with the other measurements.     

Measurement and analysis of the energy–angular distribution of secondary neutrons for Be at 5.9 and 6.4 MeV incident neutrons

The energy-angle double-differential neutron emission cross-sections of beryllium have been measured using the time of flight technique for 5.9 and 6.4 MeV incident neutrons, respectively, at 10 laboratory angles between 25° and 150°. The measured results are compared with model calculations based on the LUNF code and those of other authors and the ENDF/B-VII data. The estimation of the inelastic scattering neutron cross-sections leaving ⁹Be^∗ at the low-lying level states are also theoretically analyzed by the LUNF code. The experimental and calculated results indicated that the lowest (1.68 MeV) level still contributes to the (n, 2n) reaction with cross-sections of several 10 mb. The angular distributions and the angle-integrated elastic scattering cross-sections are also presented in comparison with other ones, these being in good agreement with the ENDF/B-VII data.     

γ-Irradiation effects on the optical properties of amorphous Ge10As30Se60 thin films

Amorphous Ge₁₀As₃₀Se₆₀ thin films on glass substrates were prepared by thermal evaporation method. The effect of γ-irradiation on the optical properties of the amorphous Ge₁₀As₃₀Se₆₀ thin films was studied in the spectral range from 200 nm to 1100 nm. γ-Radiation-induced bleaching was observed after irradiation of the samples for doses up to 50 kGy. An increase in transmission and a shift in the (transmission) absorption edge towards higher energies were observed with the irradiation dose. An increase in the optical energy gap with irradiation dose was also observed in the studied range. Photo-bleaching due to γ-irradiation was discussed in light of the structural aspects and configurational-coordinate model for Ge-As-Se.     

Effects of water chemistry and potential distribution on electrochemical corrosion potential measurements in 553 K pure water

The effects of water chemistry distribution on the potential of a reference electrode and of the potential distribution on the measured potential should be known qualitatively to obtain accurate electrochemical corrosion potential (ECP) data in BWRs. First, the effects of oxygen on a platinum reference electrode were studied in 553 K pure water containing dissolved hydrogen (DH) concentration of 26–105 μg kg^?1 (ppb). The platinum electrode worked in the same way as the theoretical hydrogen electrode under the condition that the molar ratio of DH to dissolved oxygen (DO) was more than 10 and that DO was less than 100 ppb. Second, the effects of potential distribution on the measured potential were studied by using the ECP measurement part without platinum deposition on the surfaces connected to another ECP measurement part with platinum deposition on the surfaces in 553 K pure water containing 100–130 ppb of DH or 100–130 ppb of DH plus 400 ppb of hydrogen peroxide. Measured potentials for each ECP measurement part were in good agreement with literature data for each surface condition. The lead wire connecting point did not affect the measured potential. Potential should be measured at the nearest point from the reference electrode in which case it will be not affected by either the potential distribution or the connection point of the lead wire in pure water.     

H_α/ D_α Measurements Based on Photo Diode Array in the HT-7 Tokamak

1. IntroductionThe measurement of H./D. emission, which canafford much information of the plasma, is one of the-,primary diagnostics in tokamak experiments. If theintensity Of H./D. emission along different chords ina poloidal plane are measured, with the ABEL inver-sion, one can get the H./D. emissivity, thus the spatial distribution of neutral H/D and its penetrationor ionization length. With the absolute brightness ofH./D. emission and assuming some symmetries inspatial distribution, …     

Amorphization of the interaction products in U–Mo/Al dispersion fuel during irradiation

The microstructures of the product resulting from interaction between U–Mo fuel particles and the Al matrix in U–Mo/Al dispersion fuel are discussed. We analyzed the available characterization results for the Al matrix dispersion fuels from both the out-of-pile and in-pile tests and examined the difference between these results. The morphology of pores that form in the interaction products during irradiation is similar to the porosity previously observed in irradiation-induced amorphized uranium compounds. The available diffraction studies for the interaction products formed in both the out-of-pile and in-pile tests are analyzed. We have concluded that the interaction products in the U–Mo/Al dispersion fuel are formed as an amorphous state or become amorphous during irradiation, depending on the irradiation conditions.     

Effect of metal ions in a heated nitric acid solution on the corrosion behavior of a titanium–5% tantalum alloy in the hot nitric acid condensate

For evaluating the application of titanium and its alloys as components of equipment for storing nitric acid condensate in spent nuclear fuel reprocessing plants, the corrosion behavior of titanium–5% tantalum alloy (Ti–5Ta) in a continuously renewed hot nitric acid condensate, and particularly the effect of metal ions in the heated nitric acid solution, was investigated. Corrosion experiments in an apparatus designed to renew the condensate at regular intervals showed that the corrosion rate of Ti–5Ta in the condensate increased linearly with the nitric acid concentration. The surface morphology of Ti–5Ta coupons after the corrosion experiments indicated uniform corrosion under any condition. The oxide film on the coupons had nearly constant thickness, and it was composed of mainly lower Ti oxides, such as TiO and Ti₂O₃, regardless of the nitric acid concentration in the condensate. The experimental results also showed that the addition of metal ions into the heated nitric acid solution increased the nitric acid concentration in the condensate, which resulted in a higher corrosion rate of Ti–5Ta. The corrosion rate increased noticeably as the valence of the metal ion increased and its ionic radius decreased. This effect of metal ions in the heated nitric acid solution on the corrosion rate of Ti–5Ta in the condensate was evaluated quantitatively based on the Gibbs free energy of hydration of the metal ions, and the calculated corrosion rates of Ti–5Ta in the condensate were found to be in good agreement with the experimental values.     

Kinetic studies of the α-β phase transition in the Zr1%Nb cladding for nuclear reactors

The α-β phase transition of a zirconium alloy doped with 1 mol% of niobium (E110 alloy) is investigated using differential scanning calorimetry. The onset and endpoints of the transition are identified from the measured heat flow signal and from the integration of the observed peak the extent of the α-β phase change is calculated as a function of temperature. The experiment has been performed at different heating rates and a shift of the onset temperature with increasing heating rate was observed. From the dataset the equilibrium transition curve has been extrapolated and compared with other types of zirconium-based cladding materials.