Determination of hydrogen in rock samples by neutron-induced prompt gamma-ray analysis

Prompt gamma-ray analysis was applied to determine hydrogen in geological samples. In order to obtain accurate values, blank values were estimated and subtracted. Samples were dried to constant weight in an oven. Helium gas was introduced into the sample box to purge the air containing moisture during the measurement. Hydrogen contents in some geochemical standard samples were determined and highly reproducible values were obtained.     

Elemental concentrations in geochemical reference samples by neutron capture prompt gamma-ray spectroscopy

A facility for neutron capture prompt gamma-ray activation analysis, installed on a curved thermal neutron guide at the ILL High Flux Reactor, is described. Elemental sensitivities for B, Sm and Gd have been measured. The performance of the facility has been assessed by the measurement of these trace elements in eleven USGS geochemical reference samples and comparison of the results with existing values. Preliminary concentrations of B, Sm and Gd are also reported for twelve French GRS.     

Determination of boron in marine carbonates by prompt gamma-ray analysis

Boron in carbonate reference samples was measured by neutron-induced prompt gamma-ray analysis (PGA) using cold and thermal neutron guide beams of the JRR-3M reactor. In order to determine B contents in marine carbonates, the Doppler-broadened -ray peak of 478 keV was used together with the correction of interference from Na-peak of 472 keV. We determined B in coral samples within 3% of analytical precision. The data obtained by the present method are mostly consistent with reported values. Here, we report PGA of B in marine carbonates.     

Analysis of marine samples by neutron-induced prompt gamma-ray technique and ICP-MS

Multi-element and isotopic analyses of oils and marine environmental samples were carried out to estimate a contamination source using a "finger printing" method. Elemental analyses were carried out using neutron-induced prompt gamma-ray analysis (PGA), instrumental neutron activation analysis (INAA) at the Japan Atomic Energy Research Institute, Tokai-mura, Japan (JAERI) and ICP-MS in the IAEA Marine Environment Laboratory, Monaco (MEL). Fifteen elements including light elements, H, B, N, Si and Ca, which cannot be determined by INAA and ICP-MS, were determined by PGA. A total of 47 elements were determined in the present study. The potential of PGA for the determination of isotopic ratios was tested by measuring ³⁴S/³²S ratios in oils. The evaluation of historical records of marine environmental conditions using annual bands in coral samples was also investigated.     

Determination of boron in materials by cold neutron prompt gamma-ray activation analysis

An instrument for cold neutron prompt gamma-ray activation analysis (PGAA), located at the NIST Center for Neutron Research (NCNR), has proven useful for the measurement of boron in a variety of materials. Neutrons, moderated by passage through liquid hydrogen at 20 K, pass through a (58)Ni coated guide to the PGAA station in the cold neutron guide hall of the NCNR. The thermal equivalent neutron fluence rate at the sample position is 9 x 10(8) cm(-2) s(-1). Prompt gamma rays are measured by a cadmium- and lead-shielded high-purity germanium detector. The instrument has been used to measure boron mass fractions in minerals, in NIST SRM 2175 (Refractory Alloy MP-35-N) for certification of boron, and most recently in semiconductor-grade silicon. The limit of detection for boron in many materials is <10 ng g(-1).     

Multielement determination of typical diet reference materials by neutron-induced prompt gamma-ray analysis using k 0 standardization

Multielement determination in reference materials of diet and its relatedsamples has been studied by a k 0 based neutron-induced prompt gamma-ray analysis(PGA) by using cold and thermal guided neutron beams of JRR-3M at JAERI. Hydrogen,B, C, N, Na, S, Cl, K and Ca were determined in the reference materials ofNIES and NIST typical diet and milk powder samples. Analytical results ofthe NIST Standard Reference Materials agreed with the certified values towithin 7%.     

Determination of boron in borosilicate glasses by neutron capture prompt gamma-ray activation analysis

Major levels of boron in borosilicate glasses have been determined nondestructively by neutron activation analysis. In contrast to chemical methods for determining boron as a major component, the described nuclear method has few interferences and does not require chemical separation of boron prior to its quantitation. The effects of neutron self-shielding by boron (1 to 8% by weight) are examined, minimized by dilution of powdered samples with high purity graphite, and circumvented by comparative analyses. Results of the analysis of a series of glasses with increasing boron composition are 1.150±.005% and 7.766±.035% for the low and high members of the series. Accuracy of these results depends upon comparative analyses with the certified Standard Reference Material, SRM 93a (3.89±0.02% B). Once analyzed, the glasses are useful as secondary standards for alpha track counting, and also ion and electron microprobe analyses of glasses.     

The recommended k0-factors for neutron-induced prompt gamma-ray analysis and the prompt gamma-ray emission probabilities

Recommended k ₀-factors for gamma-lines of 24 elements useful for neutron-induced prompt gamma-ray analysis (PGA) and which are not influenced by neutron spectrum differences were obtained from the k ₀-factors measured with the cold and thermal neutron guided beams of JRR-3M, by statistical calculation. The prompt gamma-ray emission probabilities were derived from the recommended k ₀-factors using atomic weight, isotopic abundance and thermal neutron capture cross section all related to the k ₀-factors, for which one can obtain accurate data. The derived gamma-ray emission probabilities for the light elements (H to Ca) agreed well within ±10% with those of the ENSDF values, which reflect recent data while the agreement for heavy elements (Ti to Pb) was ±40% with those of the ENSDF, which are still composed of old data. This revised version was published online in July 2006 with corrections to the Cover Date.     

Measurement of30Si as a tracer by neutron-induced prompt gamma-ray analysis

The application of stable isotope analysis using neutron-induced prompt -ray analysis (PGA) with cold/thermal neutron beams for the tracer study of geological materials are discussed. Silicon has three natural isotopes differing in abundance:²⁸Si (92.23%),²⁹Si (4.67%) and³⁰Si (3.10%). For the purpose of the assessment of Si migration in engineered barrier material, enriched³⁰Si can be used as a tracer due to its nuclear and chemical properties. Isotope analysis of³⁰Si was performed by PGA during the tracer study. Neutron intensity at the sample position was 1.4·10⁸ n¢cm^–2·s^–1, 2.4·10⁷ n·cm^–2·s^–1 for cold and themal neutron guided beams of JRR-3M, respectively. Calibration curves and analytical sensitivity of³⁰Si were determined based on measurement of standard samples. BG and detection limits for³⁰Si analysis were also measured in Japanese bentonite (Kunigel V1 and Kunipia F) and their pore water. Fiffteen elements were determined simultaneously using PGA.     

Determination of boron in water samples by chemical prompt gamma neutron activation analysis

Boron concentration has been determined in groundwater samples, collected from Khuchch, Gujarat, India, by prompt gamma neutron activation analysis (PGNAA) after selective separation and pre-concentration by solvent extraction with 10% 2-ethyl hexane 1,3-diol in CHCl₃. Solvent extraction separation helped to eliminate the interfering elements in PGNAA determination of boron. The sensitivity of PGNAA is found to be 18.83 cps/mg B based on the slope of a calibration plot obtained by carrying out measurements on synthetic boric acid samples containing boron in the range of 30–150 μg. Detection limit of the method is 0.2 μg/g counted for 35,000 seconds at a sample size of 15 gram. The precision (relative standard deviation at 1σ level) and accuracy of the method is 5%. The analytical results of the present method agreed well with well-established spectrophotometric determination of boron as boron-curcumin complex and inductively coupled plasma atomic emission spectroscopy (ICP-AES).     

Application of multiple prompt gamma-ray analysis (MPGA) to geochemical and cosmochemical samples

A prompt gamma-ray analysis system using multiple detection method (MPGA system) was constructed at the neutron guide hall of the JRR-3M reactor of the Japan Atomic Energy Agency. We applied MPGA method to geochemical and cosmochemical samples to evaluate its analytical performance on signal to noise (S/N) ratio, sensitivity, and detection limit. The S/N ratio measured by MPGA system was larger than that by normal prompt gamma ray activation analysis (PGAA) at JRR-3M. For some elements, the S/N ratio was improved more than ten times. Several elements that are not detected by PGAA were detected by MPGA. At the present time, concentrations of major elements and trace elements with high neutron capture cross section in geochemical and cosmochemical samples were determined accurately by the MPGA system installed at JRR-3M. It is expected that it will determine a lot of trace elements after appropriate adjustments and modifications.     

Neutron spectrum correction of k0-factors for k0-based neutron-induced prompt gamma-ray analysis

Neutron spectrum correction has been attempted for the k₀-factors of the non-1/v elements which are affected neutron spectrum difference. Effective g-factors and Westcott g-factors, which are neutron spectrum correction factors obtained from an actual neutron spectrum and the Maxwellian distribution, respectively, for the non-1/v elements were calculated using their neutron cross section data of JENDEL-3.2. The neutron spectrum correction was made for the measured k₀-factors of the non-1/v elements such as Cd, Sm and Gd with the cold and thermal guided neutron beams of JRR-3M using the g-factors. The corrected k₀-factors between the cold and thermal neutron beams using both g-factors for both neutron beams agreed well for Cd. However, 9 to 44% deviations have been found for Sm and Gd, respectively.     

Accurate and efficient determination of boron content in volcanic rocks by neutron induced prompt gamma-ray analysis

An accurate and efficient analytical method using neutron-induced prompt γ-ray was developed for the determination of boron contents in volcanic rocks. We corrected the effect of sample geometry and flux fluctuation by using silicon as an internal standard. However, we found that the slopes of the calibration line vary among volcanic samples with different matrix. Because the increase of boron activity correlates positively with γ-ray count rate of hydrogen (water), we call this as the hydrogen effect. The hydrogen effect was confirmed by our experiment in which the boron activities showed systematic increase with the amount of added hydrogen (water). Most volcanic rocks, however, contain little water (<2 wt.%) to show this effect. We determined boron contents in various volcanic rocks in order to confirm the validity of the procedure that we established. The analyzed boron contents agreed well with the previous reported values. For efficient PGA of boron in volcanic rocks, we recommend JB-2 (GSJ standard rock) as a single geochemical standard, because of its high boron content (31.2 ppm).     

Determination of boron in a black mouse by prompt gamma activation analysis

In the boron neutron capture therapy, an accurate determination of the boron content in a biological sample is very important. The boron content was investigated with a standard solution of boron which was administered intraperitoneally with a dose of 750 mg/kg body weight into mice induced cancer cells and tumors. The boron content for two types of a sample was compared to the boronophenylalanine for the tumor and the ethylamine derivatives for the induced cancer cell, which were also investigated for their accumulation rate in each organ such as blood, spleen, liver, kidney and brain. An analytical quality control was carried out by using certified reference materials such as Peach Leaves, Apple Leaves and Spinach Leaves. The relative error of the measured values was in good agreement within 2% to the certified values.     

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.     

Biological application of Doppler broadening of neutron-induced prompt gamma-ray from energetic 7*Li

Summary By probing Doppler broadened line-shapes of prompt γ -ray at 478 keV emitted from moving ⁷*Li produced via the ¹⁰B(n, γ)⁷*Li reaction, matrix materials containing and/or surrounding boron species were non-destructively characterized for several growing stages of soybean. It was elucidated that boron is in the form close to each other for both the dry seeds for planting and the dry seeds harvested, while it was revealed that boron exists in an aqueous solution for the two stages of growing, swelling seeds with a bourgeon and a greenish sprout. This work is the first biological application of Doppler broadening of neutron induced prompt γ -rays.     

Analysis of boron in biological reference materials using prompt gamma activation analysis

Summary A prompt gamma activation analysis facility has been constructed on the ST1 horizontal beam port at the HANARO research reactor, KAERI in 2003. The detector system consists of a high-purity Ge detector surrounded by BGO/NaI(Tl) scintillators as an annulus type to reject the Compton scattered photons. Detection sensitivity for boron was obtained from the prompt gamma-ray spectra of boric acid, B(OH)₃, containing 0.1-65 μg boron. The net peak for the calculation of the boron concentration was obtained by eliminating the sodium 472 keV peak, involved in the boron 478 keV peak. The biological samples used are NIST SRMs such as Peach Leaves, Apple Leaves, Tomato Leaves, Spinach Leaves, Total Diet, Typical Diet, Oyster Tissue and Corn Bran, etc. The measured values for high boron concentration showed up to a 3% of the relative, but in a low concentration below 5 ppm, present values were higher than the certified ones.     

Multi-element analysis of environmental samples by cold and thermal guided neutron induced prompt gamma-ray measurement

Non-destructive multi-element determination in environmental samples by neutron-induced prompt -ray analysis (PGA) has been investigated. Comparative standardization for the elements including H, B, C, N, Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, Mn, Fe, Co, Cd, Sm, Gd, Hg by PGA has been carried out using the cold and thermal guided neutron beams of JRR-3M reactor and then several environmental reference materials have been analyzed. Accuracy and precision of better than 20% were found for these elemental analyses except for H, C, N and Cl in biological samples. Detection limits in various environmental matrices were 25 to 820 ng/g for B, Cd, Sm and Gd, 1.1 to 820 g/g for H, Na, S, Cl, K, Ti, Mn, Co and Hg, and 0.031 to 10% for C, N, Mg, Al, Si, P, Ca and Fe. The present method is being applied to environmental studies of post war Persian Gulf together with INAA and ICP-MS.     

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.     

Development of multiple prompt gamma-ray analysis

From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium M⁺(aq)+NaL⁺(nb)⇔ML⁺(nb)+Na⁺(aq) taking place in the two-phase water-nitrobenzene system [M⁺=Li⁺, K⁺, Rb⁺, Cs⁺; L = p-tert-butylcalix[4]arene-tetrakis (N, N-dimethylthioacetamide); aq = aqueous phase, nb = nitrobenzene phase] were evaluated. Furthermore, the stability constants of the ML⁺ complexes in water saturated nitrobenzene were calculated; they were found to increase in the cation order Cs⁺<Rb⁺<K⁺<Li⁺<Na⁺.