Determination of chromium on metal surfaces by prompt proton spectrometry

Surface concentrations of chromium were determined non-destructively on copper and nickel substrates by prompt proton spectrometry during irradiation with 3.5 MeV deuterons. Ground state protons from⁵²Cr were used as a measure of the chromium content. The analysis required 5 to 30 min. The relative precision obtained was ±1.8% on copper and ±2.4% on nickel substrates, respectively.     

The determination of minor elements in steel by proton-induced prompt gamma-ray spectrometry

Pure elemental targets of Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo and W were irradiated with protons from 3.5 to 6.0 MeV, interference-free sensitivities were calculated for analysis by prompt gamma-ray spectrometry and sensitivity curves were plotted to show the variation of sensitivity with bombarding energy. Appropriate bombarding energies were selected for analysis and the extent of possible inter-element interferences and background effects were determined. Standard reference steels were used to evaluate this method for the determination of the minor elements Si, V, Cr, Mn and Co.     

The elimination of matrix effects in the determination of fluorine by proton induced prompt gamma-spectrometry

By measuring the yield of prompt gamma-rays, induced by energetic protons, the ratio of the ranges in sample and standard was used in the average cross-section method to determine fluorine. By spiking the sample with known amounts of a lithium compound, a nonanalyte element (absent from the sample), the appropriate ranges in the samples were determined by measuring the prompt gamma-rays induced in the non-analyte spike. Fluorine was determined in ores and ivory and the method was tested by analyzing the standard reference materials SRM 91, SRM 120c and SRM 694.     

The determination of boron in biological materials by neutron irradiation and prompt gamma-ray spectrometry

A prompt-gamma neutron activation technique has been developed using the (n, ) apparatus situated at the O degree through-tube of the Imperial College CONSORT II Reactor with a thermal neutron flux at the target position of approximately 2×10⁶ n cm^–2 sec^–1, and a Compton-suppression system involving a lithium-drifted germanium (Ge(Li)) detector and a sodium iodide anti-Compton shield. Boron levels of 1–5 g g^–1 (detection limit 0.05 g B for 10,000 sec period of measurement) can be attained using the Compton-suppression system with graphical inter-polation correction for the 472 keV sodium-ray peak contribution to the Doppler-broadened 478 keV boron gamma-ray peak resulting from the¹⁰B(n, )⁷Li reaction. Very good agreement is reached for boron levels compared using this system for various Standard Reference Materials and other published values. Measurement of the boron content of bone and tooth samples from rheumatoid arthritis individuals shows lower levels, (p<0.05); 16.13±7.53 g g^–1, when compared with a control population; 19.79±4.18 g g^–1. A positive correlation existed between the boron content of bone and tooth material for each study group. Results indicate that boron availability may be associated with rheumatoid arthritis.     

The determination of molybdenum and tungsten by high resolution spectrometry of alpha-induced prompt photon emission

A simple, rapid and non-destructive method is described for determining molybdenum and tungsten in steels over the concentration range 0.07 to about 20% by mass. The method uses high resolution spectrometry of the low energy gamma-rays induced by 5 MeV alpha-particle beams. The precision for molybdenum is 2.7% and for tungsten is 0.55% using respectively the 204 and 100.1 keV gamma-rays. Results obtained by Ge(Li) and intrinsic germanium detectors are compared. The extent of interference from other elements is discussed.     

The determination of boron in sedimentary rocks by neutron irradiation and prompt γ-ray spectrometry

Prompt γ-rays following the (n_th, α) reaction on¹⁰B have been measured to determine the boron content of sedimentary rocks. Employing an external reactor neutron beam with only modest flux, it is possible to assay boron at concentrations typically encountered in this material (>5 μg/g). The technique relies on the use of chemical standards and the values obtained for 9 North American shales are compared with measurements performed by emission spectrography. Detection limits and statistical errors as a function of beam time are also discussed. Department of Geology, Mcmaster University, Hamilton, Ontario (Canada)     

Determination of fluorine by the spectrometry of prompt gamma-rays

The use, for analysis, of prompt gamma-rays excited by 5 MeV alpha-particles from the reactions¹⁹F(α,α′γ)¹⁹F,¹⁹F(α, nγ)²²Na and¹⁹F(α, pγ)²²NE, was studied. The precision of the analyses depended on the gamma-ray energy used for the measurement. Relative standard deviations were ±1.8, ±0.9 and ±1.3% using the 110-, 197- or 1275 keV gamma-rays. The method was tested with N. I. M. standard materials of calcium fluoride and fluorspar, and was used as a rapid method for the determination of fluorine in cements.     

Determination of nitrogen in steels by alpha-induced prompt gamma-ray spectrometry

The prompt gamma-ray of 871 keV emitted during the bombardment of steels by 5 MeV alpha particles were used to determine nitrogen by means of the reaction¹⁴N(α, pγ)¹⁷O. The method is non-destructive, rapid and experimentally simple. It has a sensitivity of about 7 μg·g⁻¹. In the nitrogen concentration range of 10¹–10² μg·g⁻¹ the relative precision of the method is about 3%. The accuracy of the method compares with that of other nuclear methods. Presented at the 5th Symposium on Recent Developments in Activation Analysis, Oxford, 17–21 July, 1978.     

基于中子活化瞬发伽马能谱确定地层元素含量的方法

中子技术能够利用中子与物质的相互作用确定其组成等性质,广泛应用于医学、环境科学、核反应堆建设、金属矿产勘查及石油工业中。在石油天然气领域,中子探测技术主要被用于确定井孔中的孔隙度、密度和流体饱和度等参数。随着测井技术的不断发展,基于瞬发伽马射线的中子活化分析技术也已应用于井下确定地层元素含量,并成为复杂岩性和非常规油气储层获得矿物含量的唯一手段。本文阐述了地层元素伽马能谱测井的方法,利用蒙特卡罗方法模拟了不同地层条件下的伽马能谱,构建了地层元素的标准谱库,研究了奇异值分解和极大似然估计能谱数据处理方法,并利用得到的元素产额及氧闭合模型实现地层元素含量的确定。利用蒙特卡罗方法构建已知地层的伽马能谱,采用上述数据处理方法得到元素含量与地层真实元素含量误差均在4%之内,Si元素误差最大为2.8%,Ca元素最大误差为3.3%,研究结果为井下确定地层元素成分及含量提供了有效的技术支持。     

Prompt proton spectrometry from highQ-value (d,p) reactions and its use for determining10B

The analysis of boron in ore and glass samples was attempted by prompt proton spectrometry. A deuteron bombarding energy of 2.7 MeV was chosen to coincide with a region where the excitation function of the¹⁰B(d, p)¹¹B reaction did not vary appreciably with the energy. The intensity of the ground-state protons, emerging at an angle of 30°, was used as a measure of the boron content. Targets were prepared by a technique whereby approximately 300 μg/cm² deposits of powdered samples were centrifuged from a methanol suspension onto tantalum discs. Concentrations down to 0.2% were determined. Possible interference by other elements, particularly nitrogen, magnesium and titanium, was investigated but found to be of little consequence mainly because of the highQ-value of the¹⁰B(d, p)¹¹B reaction.     

The determination of gallium by atomic absorption spectrometry

The use of a nitrous oxide-acetylene flame for the determination of gallium by atomic absorption spectrometry was compared with the use of air-acetylene flames. The nitrous oxide method provided higher sensitivity and was much less sensitive to acid and base composition and to diverse added salts. Significant matrix and background effects, which occurred when gallium was determined in ore solutions with the air-acetylene flame, were eliminated with the nitrous oxideacetylene flame.     

Simultaneous determination of nitrogen, carbon, and hydrogen by thermal neutron prompt γ-ray spectrometry

Thermal neutron prompt γ-ray spectrometry is applied to the determination of nitrogen, carbon, and hydrogen in environmental materials. Useful, simultaneous, nondestructive analyses with 1-g samples can be achieved at concentrations greater than 500 ppm, 10% and 5 ppm, respectively.     

Improvements in food analysis by thermal neutron capture prompt gamma-ray spectrometry

Summary The thermal neutron prompt gamma-ray activation analysis (PGAA) facility, operated by the US Food and Drug Administration and National Institute of Standards and Technology Center for Neutron Research, has been redesigned to lower background radiation levels and improved analytical capabilities. Analysis of 22 element standards and food and botanical certified reference materials revealed significant sensitivity increases and lower limits of detection for H, B, C, N, Na, Al, P, S, Cl, K, Ca, Fe, and Cd. Mass fractions for these elements, as well as Mg, Al, Si, Ti, Mn, Fe, Cu, I, Zn, Sm, and Gd, were determined for 6 dietary supplements.     

Measurement of proton-induced prompt low energy photons by high resolution spectrometry: The analysis of lanthanides

Photons below 200 keV excited by protons from 1.8 to 5.4 MeV were measured from the lanthanides. The K X-rays were sufficiently resolved for analysis, and the sensitivity attainable was or the order of 100 g.g^–1. Apart from La and Ce, all the rare earths also yielded low energy gamma-rays suitable for qualitative analysis and for the determination of minor components at concentrations above mg.g^–1. Some excitation functions are reported and results are given for test analyses of geological materials.     

Simultaneous determination of boron-10 and boron-11 under proton bombardment

Simultaneous determination of the two stable boron isotopes was carried out through the measurement of proton induced 2124 keV gamma-ray from¹¹B and 428 keV or 718 keV gamma-rays from¹⁰B. Excitation functions were constructed and mean energies for thick target range corrections were calculated. Analysis requires no target preparation. Bombardments last up to 30 min. The sensitivity limit for total boron is 150 μg·g⁻¹ and for isotopic determinations, 0.50 atom%. The relative precision is about 3%.     

The determination of selenium by atom-trapping atomic absorption spectrometry

The application of atom-trapping atomic absorption spectrometry to the determination of selenium has been studied in detail. The optimum experimental parameters were established and the interference of major elements on the determination of selenium was studied using collection on a cold silica tube. The atom-trapping atomic absorption technique gives a detection limit of 0.03 ppm after 2-min collection on silica in an air—acetylene flame. This compares with ca. 1 ppm by the conventional absorption technique at the same 196.1-nm line. Methods to minimize interferences were examined, including the use of a double tube arrangement, an aluminium oxide-coated silica tube and ion-exchange separation. A combination of combustion in an oxygen flask and collection from an air—acetylene flame on the aluminium oxide-coated silica tube yielded satisfactory results in the analysis of four plant tissue samples.     

The determination of tungsten by electron paramagnetic resonance spectrometry

Electron paramagnetic resonance is used to determine tungsten in the range 5–400 μg ml^-1. Tungstate is reduced to tungsten(V) in the presence of thiocyanate in acidic medium and detected as the tungsten(V)—thiocyanate complex in amyl acetate after extraction. Molybdenum does not interfere; vanadium (5 mg) interferes. The relative standard deviation for mid-range concentrations is about 3%.     

Analysis of glass by simultaneous spectrometry of scattered alpha particles and prompt protons

The energy spectrum of alpha particles scattered from a beam of 4 MeV was used to determine heavy elements and oxygen and silicon in glass. Simultaneously, but with a separate detector, the energy spectrum of prompt protons from (α, p) reactions were used to determine boron, sodium and aluminium. Both detectors were placed at 135° to the direction of the beam, but the proton detector was covered with an absorber to stop backscattered alpha particles, Glass samples analysed by other methods and standard glass powders from the U. S. Bureau of Standards were used as references.     

Measurement of proton-induced prompt low energy photons by high resolution spectrometry: The analysis of noble metals

Using HPGe detectors, the K X-rays and prompt gamma-rays below 200 keV from Ru, Rh, Pd, Ag, Re, Os, Ir, Pt and Au were measured under bombardment with protons from 1.8 to 5.4 MeV. Excitation functions for analytically important gamma-rays were determined. Interference-free sensitivities were calculated and the method was tested by the analysis of standard dental alloys.     

Recent developments in the analytical application of prompt spectrometry

A survey of the possibilities of analysis by alpha-induced prompt gamma-ray spectrometry is reported for 57 elements at a bombarding energy of 5 MeV. Additional data obtained at 11 and 16 MeV are given. Interference-free sensitivities are presented. The use of the position sensitive detector is introduced to overcome problems such as occur in prompt alpha spectrometry from (p, α) reactions. The technique is illustrated by studies on the reaction¹⁹F(p, α)¹⁶O and severely tested for boron analysis using the reaction¹¹B(p, α)⁸Be and measuring the α₀ and α₁ groups.