共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
《Journal of Nuclear Science and Technology》2013,50(5):488-492
Atomic fractions of each isotope in 36Ar-38Ar-40Ar gas mixture near natural abundance were measured by using a general-purpose double-focused mass spectrometer HITACHI M-80. Because an amount of gas in a sample bulb and consequently a height of output peak decreases while taking measurements. 30 sets of peak height and time elapsed for each isotope were measured for calculation of atomic fractions through a least squares method under the assumptions (1) the reduction in heights follows an exponential function of time and (2) the rates of reduction are the same among argon isotopes. Application of this method to argon gas samples extracted from the top and bottom of a thermal diffusion column for isotope separation have proved that the method gives data with small dispersion even for 38Ar, and is satisfactory for studying separative performances of thermal diffusion column. 相似文献
3.
4.
A possible variant of a safe reactor operating on fast neutrons and cooled by the alloy Na−K−Cs is examined. The results of
optimization investigations of the layout of a fast reactor with constraints on the functionals characterizing the internal
self-shielding from ATWS-type accidents are presented. 2 tables, 5 references.
Moscow Engineering-Physics Institute. Translated from Atomnaya énergiya. Vol. 88, No. 3, pp. 169–176, March, 2000. 相似文献
5.
6.
7.
8.
《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》1987,28(1):131-134
Several experimental runs on the investigation of H− production in various types of pulsed power diodes (reflex and magnetically insulated) at a power level of 10 GW and electron cathode surface current density in the (0.5-) KA/cm range with different prepulse conditions in the anode-cathode (A-C) gap were carried out. The scheme with intermediate ion charge exchange (H− → H+) and two stage acceleration was used to identify the H− (or D−) ions and estimate their relative concentration in the plasma formed at the cathode surface. The measured activation yield of 13N in the 12C(p, γ)13N reaction gave values of H− current densities equal to (0.25 ± 0.15) A/cm2, which corresponded to (0.5–2)% of H− percentage in the cathode plasma in our experimental conditions. 相似文献
9.
10.
《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2004,217(1):33-38
Molecular dynamics study of the Si1−xGex epitaxial growth on Si(1 0 0) substrate utilizing the Stillinger–Weber two- and three-body interaction potentials was carried out. The Stranski–Krastanov growth mechanism of the Si1−xGex strain layers on Si(1 0 0) was studied and compared with experiment results. The influence of different x on the epitaxial growth layers morphology was investigated. The structure properties of the Si1−xGex layers were evaluated. 相似文献
11.
12.
Hiroaki Muta Yukihiro Murakami Masayoshi Uno Ken Kurosaki Shinsuke Yamanaka 《Journal of Nuclear Science and Technology》2013,50(2):181-187
Th1?x U x O2 solid solutions were synthesized by solid-state reaction and pelletized using the spark plasma sintering (SPS) technique. Pellets with >90% theoretical density were easily obtained within 40 min of sintering without any additive. The thermal conductivity, Young's modulus, Debye temperature, Vickers hardness, and heat capacity were systematically investigated, and the values for ThO2 agree with the literature data. The thermal conductivity of Th1?x U x O2 decreased with increasing U content up to x =~0.5. This tendency corresponds to phonon-point defect scattering theory. The Young's modulus and Debye temperature linearly decreased with increasing U content. The Debye temperature and standard molar entropy derived from the low-temperature heat capacity agree with the reported values. 相似文献
13.
《Annals of Nuclear Energy》1986,13(8):467-469
The delayed-neutron emission probabilities (Pn-values) of 94Rb and 95Rb have been measured as 9.73 ± 0.62 and 8.60 ± 0.57%, respectively, by a β−γ spectroscopic method utilizing the on-line isotope separator KUR-ISOL. This method can be usefully applied if a pure isotopic and mass-separated ion beam is available and the absolute emission probabilities per decay of main γ-rays emitted from relevant nuclides are well-established. 相似文献
14.
15.
The sound speeds of longitudinal and transverse waves in the uranium–plutonium mixed oxide pellets were measured as functions of porosity, oxygen-to-metal ratio, and plutonium content. The effect of each parameter was well fitted by a linear function and the equations were obtained to calculate the sound speeds. Mechanical properties were evaluated with the sound speeds and the result of Young's modulus showed that porosity was the most important factor to decrease Young's modulus. Temperature dependence on Young's modulus was also evaluated with previously reported thermal expansion. Decrease of Young's modulus with increasing temperature was in good agreement with available literature. 相似文献
16.
《Journal of Nuclear Science and Technology》2013,50(7):631-641
By using the two-dimensional rigorous numerical solution of flow and convection-diffusion equations, the H2-HT separative performances of thermal diffusion column with 15 mm-radius and 288.15K cold-wall was analyzed up to ?0.3 MPa for higher hot-wire temperature (up to ?1,700K). Flow analysis has revealed: (1) The magnitude of the free convection is almost proportional to the pressure, and laminar solution of free convection could not be obtained at the pressure more than ?0.32 MPa. (2) The magnitude of the free convection increases gradually with ΔT (the temperature difference between hot and cold surfaces), when ΔT<–800 K. In the range of larger ΔT, the magnitude is almost constant or rather decreases gradually with ΔT. As a result, the laminar solution could always be obtained at the pressure less than ?0.32 MPa, no matter how large ΔT may be. Separative analysis for H2-HT isotope separation has made clear that the thermal diffusion column with 288.15 K cold-wall should be operated at (1) 0.15–0.2 MPa, (2) ΔT that is as large as technically possible, and (3) the feed rate F of 50–100 cm3 (288.15 K, 0.1 MPa)/min. 相似文献
17.
《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》1987,28(1):108-112
We have developed a compact ΔE−E gas telescope that can easily be incorporated into a standard ultrahigh vacuum ion scattering chamber. If energetic, heavy ions are available as a primary beam, the gas telescope can be used to detect light elastic recoils scattered from the surface region of a sample. The detector consists of a gas ionization chamber in front of a surface-barrier detector. The energy loss signal in the gas (ΔE) is taken in coincidence with the energy signal in the surface-barrier detector (E) to identify both the atomic number and the total energy of the elastic recoil. The design parameters of the detector have been chosen to allow detection of elements from H to O with good depth resolution ( < 100 Å) and submonolayer sensitivity. The mass resolution is adequate to easily separate all elements from H to O. 相似文献
18.
《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》1998,134(1):107-112
The location of Ag in Ag-doped YBa2Cu3O7−δ (YBCO) films and other high-Tc materials (such as Ag-doped BiSrCaCuO films and Ag-sheathed textured BiSrCaCuO wires) is a very important issue for improving high-Tc materials. In this work, laser ablated and DC magnetron sputtered YBCO films on (1 0 0) LaAlO3 and (1 0 0) SrTiO3 were prepared from sintered Ag-YBCO composite targets (nominally containing 5 wt% Ag) and studied by Rutherford Backscattering Spectrometry (RBS) and ion channeling techniques using 2.0 MeV4He+ and 7Li+ beams. We have found that the Ag-YBCO targets contain about 3 wt% Ag and most of the retained Ag atoms form some small size Ag precipitates with a typical size smaller than a few microns. We have demonstrated that in very good single crystalline YBCO films, the percentage of retained Ag in substitutional sites can be estimated by ion channeling technique. For example, we have found that about 1.2 wt% Ag atoms remain in the laser ablated Ag-doped films prepared from the Ag-YBCO target and about two-thirds of the retained Ag atoms occupy substitutional sites. The sputtered films contain less retained Ag atoms since the deposition temperature is higher and deposition time is longer than those for laser ablated films. 相似文献
19.
20.
Effects of pre-irradiation annealing and deposition of a thin film of Lix–Co(1−x)–O on soda lime glass substrate are studied using the thermoluminescence technique, at low gamma radiation doses. Simple but similar glow curves were obtained with a single glow peak in all cases. Glow peaks occurred within the temperature range of 266 and 288 °C depending on sample treatment and gamma dosage. Within the studied gamma radiation dose range of 0.86–4.29 mGy, the heated soda lime glass consistently showed the highest TL response, while that from the film deposited sample was the least. At a dose of 0.86 mGy, a 41.8% enhancement and a 56.7% loss in signal over those from ordinary soda lime glass were recorded for annealed and film deposited samples respectively. Peak shift to higher temperatures were also observed in the two treated samples, relative to blank. These we have attributed to the increased diffusion of alkali ions in the annealed glass and exchange of impurity ions between the Lix–Co(1−x)–O thin film and the soda lime glass substrate, at high temperatures, resulting in increased formation of points and complex defects that could be either killer or radiative traps. 相似文献