Proton induced gamma ray emission analysis of nitrogen

The proton-capture reactions 14N(p,γ)15O and 15N(p,αγ)^12C have been studied to determine their applicabilities to the analysis of materials for 15N enrichment,It is true that precision of the measurement concerned in these techniques cannot compete with mass spectrometry,but their ease of application is of great advantage to the fast handling of very large batches of samples from stable nuclide tracer experiments.     

Absolute thick-target γ-ray yields for elemental analysis by 7 and 9 MeV protons

A systematic study of absolute thick-target γ-ray yields, produced in the bombardment of elements with Z = 3–9, 11–17, 19, 20, 22–30, 32, 39–42, 44, 46–51, 53, 62, 64, 70, 72–74, 78, 79, and 82 by 7 and 9 MeV protons, has been carried out. The most suit γ-ray energies and absolute yields for elemental analysis are listed. Relative neutron yields are also given.     

Proton elastic scattering and proton induced γ-ray emission cross-sections on Na from 2 to 5 MeV

Differential cross-sections for proton elastic scattering on sodium and for γ-ray emission from the reactions ²³Na(p,p′γ)²³Na (E_γ = 440 keV and E_γ = 1636 keV) and ²³Na(p,α′γ)²⁰Ne (E_γ = 1634 keV) were measured for proton energies from 2.2 to 5.2 MeV using a 63 μg/cm² NaBr target evaporated on a self-supporting thin C film.The γ-rays were detected by a 38% relative efficiency Ge detector placed at an angle of 135° with respect to the beam direction, while the backscattered protons were collected by a Si surface barrier detector placed at a scattering angle of 150°. Absolute differential cross-sections were obtained with an overall uncertainty estimated to be better than ±6.0% for elastic scattering and ±12% for γ-ray emission, at all the beam energies.To provide a convincing test of the overall validity of the measured elastic scattering cross-section, thick target benchmark experiments at several proton energies are presented.     

Metrological system forγ-ray spectrometry measurement of the specific activity and mass fraction of natural radioactive elements in soil and rock samples

All-Russian Scientific-Research Institute of Exploratory Geophysics, VIRG-Rudgeofizika. Scientific and Industrial Association "VNIIM im. D. I. Mendeleeva," Center for Metrological Standards for Ecological Safety. Institute of Radiation Hygiene. Translated from Atomnaya Énergiya, Vol. 75, No. 5, pp. 350-354, November, 1993.     

Beam charge integration in external beam PIXE–PIGE analysis utilizing proton backscattering with an extraction window

In this study,we present a new method for the indirect integration of beam charges in external beam proton-induced X-ray emission and proton-induced c-ray emission(PIXE–PIGE) analysis.We recorded proton spectra backscattered by a Kapton film extraction window in different sample situations and under different beam currents.We also simulated backscattering spectra using the simulation of backscattering spectra program(SIMNRA).We determined that in a specific geometrical arrangement,different sample situations did not significantly affect factor C_Q(the ratio between integral backscattering proton counts and integral beam charges).We also studied the reproducibility and beam current dependence of factor C_Q.The statistic factor of C_Q was28.95 ± 0.6 kilo counts/l C,with a relative standard deviation of 2.0 %.Significantly,in external beam PIXE–PIGE analysis,we were able to calculate beam charge integration from the integral backscattering proton counts in an energy region.     

Improved method for measuring the γ-ray absorbed dose rate in models of iron shielding of a thermonuclear reactor

An improved method of measuring the absorbed γ-ray dose rate usingCaSO ₄ andSrSO ₄ type thermoluminescent detectors in models of iron shielding of a thermonuclear reactor is described. The reactionT(d, n)⁴ He served as a neutron source. The method obtained makes it possible to determine the absorbed γ-ray dose rate in shielding without using computed information and relying only on experimental data on the rates of nuclear reactions in threshold detectors. 7 figures, 1 table, 9 references. Moscow Engineering-Physics Institute. Translated from Atomnaya énergiya, Vol. 86, No. 3, pp. 219–225, March, 1999.     

A UHV-compatible ΔE−E gas telescope for depth profiling and surface analysis of light elements

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.     

Activity level of gross α and gross β in airborne aerosol samples around the Qinshan NPP

The monitoring results of gross α and gross β activity from 2001 to 2005 for environmental airborne aerosol samples around the Qinshan NPP base are presented in this paper. A total of 170 aerosol samples were collected from monitoring sites of Caichenmen village, Qinlian village, Xiajiawan village and Yangliucun village around the Qinshan NPP base. The measured specific activity of gross α and gross β are in the range of 0.02 - 0.38 mBq/m^3 and 0.10 - 1.81 mBq/m^3, respectively, with an average of 0.11 mBq/m^3 and 0.45mBq/m^3, respectively. They are lower than the average of 0.15 mBq/m^3 and 0.52mBq/m^3, of reference site at Hangzhou City. It is indicated that the specific activity of gross α and gross β for environmental aerosol samples around the Qinshan NPP base had not been increased in normal operating conditions of the NPP.     

Activity level of gross α and gross β in airborne aerosol samples around the Qinshan NPP

The monitoring results of gross α and gross β activity from 2001 to 2005 for environmental airborne aerosol samples around the Qinshan NPP base are presented in this paper. A total of 170 aerosol samples were collected from monitoring sites of Caichenmen village, Qinlian village, Xiajiawan village and Yangliucun village around the Qinshan NPP base. The measured specific activity of gross α and gross β are in the range of 0.02 ～ 0.38 mBq/m3 and 0.10 ～ 1.81 mBq/m3, respectively, with an average of 0.11 mBq/m3 and 0.45mBq/m3, respectively. They are lower than the average of 0.15 mBq/m3 and 0.52mBq/m3, of reference site at Hangzhou City. It is indicated that the specific activity of gross α and gross β for environmental aerosol samples around the Qinshan NPP base had not been increased in normal operating conditions of the NPP.     

Proton induced L-shell X-ray production cross-sections for Pb in the energy range 225–400 KeV

The L-shell X-ray production cross-sections in lead (Pb) by proton impact over the energy range 225–400 keV, with an interval of 25 keV, have been measured. The thick target X-ray yields have been obtained using a HPGe detector. The experimental results for σ_L1, σ_Lα, σ_Lβ and σ_Lγ have been compared with perturbed stationary state theory with relativistic (R), energy loss (E) and Coulomb (C) corrections (ECPSSR theory). The comparison of L_α, L_β and L_γ, X-ray production cross-sections shows a fairly good agreement, except at the lowest energy. The L₁ X-ray production cross-sections are higher by ≈ 20–30% than their theoretical estimates.     

Tests in an MR reactor of experimental fuel elements of the VVÉR-1000 reactor

Conclusions In an MR reactor performance tests of 16 fuel assemblies, with elements having essentially the same structure as standard VVÉR-100 fuel elements, were carried out. Tests of five more fuel assemblies are continuing. Of the 16 assemblies, 13 were studied in a hot laboratory.The tests in the MR, carried out at high loads and with a large number of transition processes, as well as the postreactor studies, indicated that fuel elements of the specified design (with initial helium pressures of 1.96–2.45 MPa) have a high reliability. None of the elements of the fuel assemblies studied malfunctioned due to design defects or faults in their fabrication. During the tests the jackets were subject to a little oxidation and hydrogenation (zirconium-oxide film<3 m thick, hydrogen content less than 0.008% by mass), and their plasticity remained high (the relative elongation at the working temperature remained at the 20% level).Translated from Atomnaya Énergiya, Vol. 62, No. 5, pp. 312–317, May, 1987.     

Novel methodology for the quantitative assay of fissile materials using temporal and spectral β-delayed γ-ray signatures

An analytical model for the generation of β-delayed γ-ray spectra following thermal-neutron-induced fission of mixed samples of ²³⁵U and ²³⁹Pu is presented. Using an energy-dependent figure-of-merit to designate the spectral regions employed in the assay, the unique temporal β-delayed γ-ray signatures are utilized to determine the fraction of ²³⁹Pu in a mixed U-Pu sample. By evaluating the β-delayed γ-ray temporal signatures of both ²³⁵U and ²³⁹Pu within a 3 keV energy bin, traditional sources of systematic uncertainty in quantitative assay using β-delayed γ-ray signals, such as self-attenuation of the sample and energy-dependent γ-ray detection efficiency, are significantly reduced. The effects of the time-dependent Compton-continuum and growth of longer-lived nuclides on the quantitative assessment are explored. This methodology represents a promising extension of the conventional means of analysis for quantitative assay of fissile materials using β-delayed γ-ray signatures.     

Identification tables for use in the analysis of α and β activities

In order to facilitate the identification of activities being subjected to analysis, tables are compiled according to data published prior to 1958 containing the distribution of all known - and -radioactive isotopes as a function of their T_1/2, end-point energies of their -spectra, and -particle energies. The tables make it possible to establish a group of isotopes with a previously established T_1/2 and energies of radioactive emission. In a number of cases, the use of a scheme involving the radioactive decay chain may also prove expedient in the identification of activities.We consider it our duty to express our gratitude to Yu. A. Zysin for a discussion and his advice.     

Possibility of Activation γ-Spectrometric Measurements for Determining the Masses of Nuclear Materials in Samples

Measurements of -ray spectra performed on uranium and plutonium samples irradiated with ²⁵²Cf source neutrons are described. Peaks due to ¹³⁸Cs and other short-lived fission products are observed in the spectra. The intensity of the peaks characterizes the content of fissioning isotopes in the samples.     

Determination of the Attentuation Multiple of an Air Layer for γ-Rays Emitted from a Radioactively Contaminated Site

Accidents with rupture of a reactor core can contaminate large regions. One way to reduce the time required to determine the scenario can be to perform a preliminary survey using nonspecialized dose rate meters placed on aircraft. For methodological support for this approach, an analytical relation is obtained which permits determining indirectly, on the basis of data on the flight altitude, the coefficients which are needed to convert the -ray dose rate measured from the aircraft to the value at the ground.     

CFD analysis of the loss coefficient for a 90° bend in rolling motion

The local loss coefficient for a 90° bend in rolling motion is investigated with CFD code FLUENT. The calculation results are validated with experimental and theoretical results in steady state. The effect of spanwise and transverse additional forces on the bend loss is significant. The effects of additional forces on the bend loss are mainly embodied in the downstream section. The oscillation of bend loss caused by the spanwise and transverse additional forces is very regular while that caused by velocity oscillation is very irregular. The effect of velocity oscillation on the bend loss is significant in rolling motion with low Reynolds number. But the variation of bend loss coefficient with velocity oscillating period is very limited.     

Monte Carlo simulation of the response of Si(Li) X-ray detectors to proton induced K X-rays of light elements (12 ≦ Z ≦ 32) applied to efficiency determination

Measurements of proton induced K X-ray spectra of elements in the range 12 ≦ Z ≦ 32 have been performed, using two different Si(Li) detectors. A new detector model is deduced from the measured ratios of low energy background counts to photopeak counts. This detector model assumes both the existence of a surface layer with reduced charge carrier collection efficiency and the existence of a low concentration of small regions of detector defects, which have enhanced charge carrier recombination probability, within the volume of the Si(Li) detector, to explain the observed low energy background. Monte Carlo simulations of the response of two different Si(Li) detectors to K X-rays have been performed in order to quantify possible contributions of detector front contact and dead layer, respectively, to the measured X-ray spectra. Upper limits of those contributions and upper limits of dead layer thickness are given. The consequence of these results to detector efficiency calibration measurements are discussed.