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.     

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 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).     

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).     

Analyses of oxyanion materials by prompt gamma activation analysis

Prompt gamma activation analysis (PGAA) has been used to analyze metal ion oxyanion materials that have multiple applications, including medicine, materials, catalysts, and electronics. The significance for the need for accurate, highly sensitive analyses for the materials is discussed in the context of quality control of end products containing the parent element in each material. Applications of the analytical data for input to models and theoretical calculations related to the electronic and other properties of the materials are discussed.     

Determination of boron in ceramic reference materials by prompt gamma activation analysis using focused neutron guided beam of JRR-3M

Prompt gamma activation analysis using a focused thermal neutron guided beam at JAEA JRR-3M was applied to the determination of B in ceramic certified reference materials (BAM CRM S-003 Silicon Carbide Powder and NMIJ CRM 8004-a Silicon Nitride Powder). Cl and Si were used as internal standards to obtain linear calibration curves of B. The analytical result of B in BAM CRM S-003 was in good agreement with the certified value. The relative expanded measurement uncertainties (k = 2) were 4.8% for BAM CRM S-003 and 4.9% for NMIJ CRM 8004-a.     

Determination of the hydrogen concentration in coal and titanium alloy by prompt gamma neutron activation analysis

The determination of the hydrogen concentrations in coal and metal samples were investigated by using the PGAA system at the HANARO Research Reactor, KAERI. The calibration curve of the hydrogen concentration was obtained from a standard sample and the effects of the interference peaks near the gamma-energy region of hydrogen were investigated. The background in the hydrogen peak of a prompt gamma-ray spectrum was measured for the sample chamber and shielding materials of an atmospheric state. The combined uncertainties estimated for the analysis procedure were in the range of 4–5%. Two kinds of certified reference materials, NIST SRM 1632c (Coal), NIST SRM 173c (Titaniumbase Alloy) and NIST SRM 2453 (Titanium Alloy) were used to verify the accuracy and precision of the measurement. The relative error was in the range of 3–6% and the relative standard deviation were less than 4%.     

Xenon diffusion studies with prompt gamma activation analysis

Developing a better understanding of xenon transport through porous systems is critical to predicting how this gas will enter the atmosphere after a below ground nuclear weapons test. Radioxenon monitoring is a vital part of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) International Monitoring System. This work details the development of prompt gamma activation analysis for measuring the diffusion rates of xenon and argon gases through a porous medium. The University of Texas at Austin maintains a prompt gamma activation analysis facility with a peak neutron flux of ~1.5 × 10⁷ cm⁻² s⁻¹ and a beam diameter of 1 cm. Due to the relatively large prompt gamma cross sections of many stable xenon isotopes at thermal and sub-thermal neutron energies, prompt gamma activation analysis is a suitable technique for in situ non-destructive analysis of natural xenon. A test chamber has been designed and constructed to utilize prompt gamma activation analysis to measure xenon and argon diffusion through geological materials (e.g., sand, soil, etc.). Initial experiments have been conducted to determine the detection limits for stable gas measurements. The results from these experiments will be utilized to benchmark parts of a xenon transport model that is being used to determine diffusion coefficients for xenon and argon.     

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.     

Progress of prompt gamma activation analysis in Korea

Summary The new PGAA facility using diffracted neutron beam was developed in Korea. The basic characteristics of the facility were studied in detail. A general formalism of the k₀ factor as extended to non-1/v absorber and arbitrary neutron spectrum was discussed and the actual data for Cd, Sm, Eu, Gd have been measured and determined successfully owing to the simple nature of the diffracted neutron spectrum. The k₀ factors for B, N, Si, P, S and Cl were also determined and showed consistent results with previously reported ones. At an early stage, feasibility of boron concentration analysis and measurement of thermal neutron capture cross sections has been studied. The PGAA facility is now open to users. A considerable amount of beam time is already dedicated to studies on the elemental analysis.     

Combining prompt gamma activation analysis and off-line counting

The off-line γ-counting of in-beam activated radionuclides has been explored to extend the detection capabilities of prompt gamma activation analysis (PGAA). Such combination of the prompt measurement with a subsequent decay-counting is feasible if radionuclides with half-lives of minutes or hours are produced in the sample during neutron irradiation. Thanks to the simpler spectrum and the higher counting efficiency of decay counting, both selectivity and sensitivity can be improved. The pros and cons of the proposed method have been demonstrated on a series of industry-related measurements.     

Investigation of hydrogen content in chemically delithiated lithium-ion battery cathodes using prompt gamma activation analysis

Summary Lithium-ion batteries are widely used as a power source for portable electronic devices. Currently, only 50-70% of the theoretical capacity of the layered oxide cathode (positive electrode) materials could be reversibly used. The reason for this limitation is not fully understood in the literature. Recent structural and chemical characterizations of chemically delithiated (charged) cathodes suggest that loss of oxygen from the lattice may play a role in this regard. However, during the chemical delithiation process any proton inserted from the solvent could adversely affect the oxygen content analysis data. The challenge in addressing this issue is to detect and determine precisely the proton content in the chemically delithiated samples. The prompt gamma-ray activation analysis (PGAA) facility at the Nuclear Engineering Teaching Laboratory (NETL) is used to determine the proton content in the layered oxide cathode LiNi_0.5Mn_0.5O₂ before and after chemical delithiation. The data are compared with those obtained with Fourier transform infrared (FTIR) spectroscopy, which can provide mainly qualitative analysis. The technique has proved to be promising for these compounds and will be applied to characterize several other chemically delithiated Li_1-xCo_1-yM_yO₂ (M = Cr, Mn, Fe, Ni, Cu, Mg, and Al) cathodes.     

Recent developments of prompt gamma activation analysis at Budapest

The PGAA facility at the Budapest Research Reactor has been continually upgraded and developed since its start-up in 1996, as a result of which its performance has improved considerably. The installation of the cold neutron source, the partial change to supermirror neutron guides and their realignment increased the flux by almost two orders of magnitude. The data acquisition has been modernized as well; digital spectrometers were tested and implemented in novel forms of gamma-ray spectrum collection. This year a higher-efficiency HPGe detector and a new data acquisition module were put into operation. Most recently all the neutron guides were changed to supermirror-coated ones to further increase the neutron flux. The improved evaluation software makes possible a more reliable elemental analysis of the samples. In this progress report these developments are critically reviewed. The characteristics of the latest system are also described. It is the first time that a set of new partial gamma-ray production cross sections are presented, which are based on the new intensity values of ¹⁴N(n,γ)¹⁵N calibration standard.     

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.     

Determination of nuclear graphite impurities by prompt gamma activation analysis to support decommissioning operations

Journal of Radioanalytical and Nuclear Chemistry - Elemental composition of non-irradiated nuclear grade graphite was determined by Prompt Gamma Activation Analysis (PGAA) to quantitively assess...     

Upgrade of the prompt gamma activation analysis and the neutron-induced prompt gamma spectroscopy facilities at the Budapest research reactor

The Budapest Research Reactor’s Prompt Gamma Activation Analysis (PGAA) and Neutron-Induced Prompt gamma Spectroscopy (NIPS) facilities were significantly upgraded during the last few years. The higher neutron flux, achieved by the partial replacement and realignment of the neutron guides, made feasible the automation and specialization of the two experimental stations. A new neutron flux monitor, computer-controlled beam shutters and a low-level counting chamber have been put into operation to assist with in-beam activation experiments. An automatic sample changer has been installed at the PGAA station, while the NIPS station was redesigned and upgraded with a Compton suppressor to use for the non-destructive analysis of bulky samples. In the near future the latter setup will be completed with a neutron tomograph and a moving table, to turn it into a Neutron Radiography/Tomography-driven PGAA equipment.     

Neutron self-shielding correction for prompt gamma neutron activation analysis of large samples

Summary Facilities and methods for INAA of large samples (up to 30 kg) have been developed and successfully tested at IRI, Delft. The methods encompass corrections for neutron self shielding in an isotropic neutron field and gamma self-absorption. The sample’s neutron absorption and scattering characteristics are determined by monitoring the neutron fluence rate around the sample and comparing the neutron densities measured with unperturbed fluence rates. We report on the possibility of developing similar methods for PGNAA. Relative self-shielding factors were measured as well as obtained from Monte Carlo computations. The agreement is good except for the most extreme case, with respect to absorption, attempted (CCl₄).     

Determination of carbon, nitrogen, and phosphorus in cattail using thermal neutron prompt gamma activation analysis

A previous study on the determination of carbon, nitrogen, and phosphorus in cattail using cold neutron prompt gamma activation analysis (CNPGAA) demonstrates that the results of numerous cattail samples showed favorable comparison to results from an elemental analyzer (EA) for C and N. However, the results for P overestimated the results from a UV-VIS spectrophotometer because of the interference of chlorine existing in cattail collected from an estuarine environment. To compare to CNPGAA, a method for the determination of C, N, and P in cattail using thermal neutron prompt gamma activation analysis (TNPGAA) has been developed in the TNPGAA facility at the National Institute of Standards and Technology (NIST) and evaluated through the analysis of standard reference materials (SRMs).