Prompt Gamma-ray Activation Analysis Research Articles

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.

Determination of boron concentration in blood and tissue samples from patients with liver metastases of colorectal carcinoma using Prompt Gamma Ray Activation Analysis (PGAA)

As part of the studies on Boron Neutron Capture Therapy at the University of Mainz, Germany, a clinical trial has been started in which, four patients suffering from liver metastases of colorectal carcinoma have been enrolled. Specimens of blood and healthy tissue samples taken from the patients were measured at the PGAA facilities at the HFR in Petten, The Netherlands, and at the FRM II in Munich, Germany. From the measured boron concentrations, pharmacokinetic curves and blood-to-tissue concentration ratios were produced.

Characterisation and optimisation of the new Prompt Gamma-ray Activation Analysis (PGAA) facility at FRM II

At the research reactor Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II) a new Prompt Gamma-ray Activation Analysis (PGAA) facility was installed. The instrument was originally built and operating at the spallation source at the Paul Scherrer Institute in Switzerland. After a careful re-design in 2004–2006, the new PGAA instrument was ready for operation at FRM II.In this paper the main characteristics and the current operation conditions of the facility are described. The neutron flux at the sample position can reach up 6.07×1010[cm−2s−1], thus the optimisation of some parameters, e.g. the beam background, was necessary in order to achieve a satisfactory analytical sensitivity for routine measurements.Once the optimal conditions were reached, detection limits and sensitivities for some elements, like for example H, B, C, Si, or Pb, were calculated and compared with other PGAA facilities. A standard reference material was also measured in order to show the reliability of the analysis under different conditions at this instrument.

Improving the performance of 241Am-Be for PGNAA applications using a proper shielding for neutron source and the NaI detector

The gamma ray spectrum resolution from a 241Am-Be source-based prompt gamma ray activation analysis set-up has been observed to increase in the energy region of interest with enclosing the NaI detector in a proper neutron and gamma ray shield. We have investigated the tact that the peak resolution of prompt gamma rays in the region of interest from the set-up depends on the source activity to the great extent, size and kind of the detector and the geometry of the detector shield. In order to see the role of a detector shield, five kinds of the detector shield were used and finally the proper kind was introduced. Since the detector shield has an important contribution in the reduction of the undesirable and high rate gamma rays coming to the gamma ray detector, a good design of a proper shield enables the elimination of the unwanted events, such as a pulse pile-up. By improving the shielding design, discrete and distinguishable photoelectric peaks in the energy region of interest have been observed in the spectrum of prompt gamma rays.

Determination of elements in SRM soil 2709a by neutron activation analysis

A combination of instrumental neutron activation analysis (INAA) and prompt gamma-ray activation analysis (PGAA) was used to value assign 35 elements in SRM soil 2709a (San Joaquin Soil). INAA with counting of short-lived radioisotopes was used for determination of Al, Au, Ca, Dy, K, Mg, Mn, Na, Ti, and V. Elements determined by INAA with counting of intermediate and long-lived radioisotopes included As, Ba, Ce, Co, Cr, Cs, Eu, Fe, Hf, La, Lu, Nd, Rb, Sb, Sc, Sm, Sr, Ta, Tb, Yb, Zn, and Zr. Thermal neutron PGAA was used for the determination of H, B, Si, K, Ti, Mn, Fe, Cd and Gd. Expanded uncertainties were determined for all values reported.

Performance characteristics of a prompt gamma-ray activation analysis (PGAA) system equipped with a new compact D–D neutron generator

A new prompt gamma-ray activation analysis (PGAA) system equipped with a compact deuterium–deuterium (D–D) neutron generator has been developed for fast detection of explosives and chemical warfare agents. The PGAA system was built based on a fully high-voltage-shielded, axial D–D neutron generator with a radio frequency (RF)-driven ion source. The ionic current of the compact neutron generator was determined as a function of the acceleration voltage at various RF powers. Monoenergetic neutrons (2.45MeV) with a neutron yield of >1×107n/s were obtained at a deuterium pressure of 8.0mTorr, an acceleration voltage of 80kV, and an RF power of 1.1kW. The performance of the PGAA system was examined by studying the dependence of a prompt gamma-ray count rate on crucial operating parameters.

Determination of boron and other elements in volcanic rocks by prompt gamma-ray analysis: An application to magma genesis in Kyushu island, SW-Japan

Neutron induced prompt gamma-ray activation analysis (PGAA) is applied for determining boron contents in volcanic rocks, which is an important element in the discussion of material circulation in volcanic arc systems. To evaluate the recycling of oceanic crust in Kyushu, we analyzed boron and other trace element contents in basaltic rocks from the area. The basalts from volcanic front have high B/Nb (2.9–3.7), B/Zr (0.1–0.2) and B/Sm (2.8–6.0) ratios, whereas those ratios in the basalts from backarc are extremely low (<0.5; <0.1; 0.5–1.7), respectively. This indicates that the recycling of subducted oceanic crust to the arc crust is limited in the volcanic front.

Characterization of Materials for a Hydrogen-Based Economy by Cold Neutron Prompt Gamma-Ray Activation Analysis

AbstractAn instrument for cold neutron prompt gamma-ray activation analysis (PGAA) at the NIST Center for Neutron Research (NCNR) has proven useful for the chemical characterization of hydrogen storage materials and other materials of importance to a hydrogen-based economy. The detection limit for hydrogen is less than 10 mg/kg for most materials. Potential hydrogen storage materials that have been characterized by PGAA include single-wall carbon nanotubes with and without boron doping, porous carbons, lithium magnesium imides, and ternary hydrides of various elements. The capability to allow in situ hydrogenation and characterization of materials is currently under development. PGAA has also been used to characterize materials used in hydrogen fuel cells, including solid proton conductors, polymer membrane, and proton exchange membranes. Future upgrades to the instrument will improve detection limits and functionality of the instrument.

Efficiency calibration of an HPGe detector in the 0.1–2.5 MeV energy range for Am-Be neutron source-based PGAA applications

A 740 GBq 241Am-Be neutron source based prompt gamma-ray activation analysis (PGAA) setup in combination with a typical coaxial n-type HPGe detector (REGe) system was used to analyze light elements like H, B, C, N, etc. The absolute full energy peak (FEP) efficiencies of the shielded REGe detector for irradiation and counting geometries and for sources with different sizes (point, ampoule and cylindrical) were measured in the 0.1–2.5 MeV energy range by utilizing calibrated sources (point, liquid and solid). 4th order polynomials were fitted to the experimental data. Efficiencies in far irradiation and counting geometries are compared.

Validation of an alkali reaction, borate fusion, X-ray fluorescence method for silicon metal

The value assignment of candidate Standard Reference Material (SRM®) 57b Silicon Metal provided an opportunity to develop an alkali reaction procedure as a precursor to borate fusion for the preparation of test specimens from the metal powder for X-ray fluorescence spectrometry (XRF). Suggested for this purpose by Blanchette in a 2002 Advances in X-ray Analysis article [45, 415–420 (2002)], the alkali reaction uses LiOH∙H2O to convert Si to Li2SiO3. Lithium silicate is fused with lithium borate flux without damage to platinum ware. Once specimens are fused and cast as beads, calibration standards are prepared to closely match the compositions of the specimens, allowing a linear calibration for each analyte. The XRF method yields results that are directly traceable to the mole through NIST SRM spectrometric solutions. The method was validated in two ways. First, the reaction was used on older SRMs for Si metal: SRM 57 and SRM 57a. Second, XRF results for candidate SRM 57b were compared to results obtained using prompt gamma-ray activation analysis (PGAA) and inductively coupled plasma optical emission spectrometry (ICPOES). Bias tests show the XRF results are accurate for the elements Al, S, Ca, Ti, Cr, Mn, Ni, Cu, and Zr. Levels of S, Ca, Cr, and Cu in candidate SRM 57b are near the limits of quantification of the borate fusion method. Iron results may be subject to a low bias. Phosphorus is not quantitatively retained during the alkali reaction and borate fusion. These elements, plus B, which cannot be determined after borate fusion, are listed in manufacturing specifications for Si metal.

Non-destructive evaluation of concrete samples using PGNAA technique

Non-destructive evaluation of concrete is an important task of quality control in building construction industry. The quality evaluation of concrete samples was carried out using prompt gamma ray activation analysis (PGNAA) technique. In this study calcium and silicon contents of six concrete samples were determined through yield of 1.94 MeV gamma-rays from calcium and 3.54 MeV gamma-rays from silicon. The concrete samples were prepared by mixing cement, coarse and fine aggregates in different proportions. A linear correlation has been observed between the experimental yield of the prompt gamma rays and the actual calcium and silicon concentration in the concrete samples. Results of this study have demonstrated successful use of an accelerator-based PGNAA setup in non-destructive analysis of the concrete samples.

New source–moderator geometry to improve performance of 252Cf and 241Am–Be source-based PGNAA setups

The gamma ray yield from a 252Cf and a 241Am–Be source-based Prompt Gamma Ray Activation Analysis (PGNAA) setup has been observed to increase with enclosing their neutrons sources in a high-density polyethylene moderator. The prompt gamma rays yield from both setups depends upon the moderator length and the source position in it. For both setups, the optimum moderator length is found to be 7 cm. The optimum position of the neutron source inside moderator of the 252Cf and the 241Am–Be source-based PGNAA setups was found to be at a distance of 0.5 and 0.75 cm from the moderator-end facing the sample, respectively. Due to enclosure of the source in the moderator, about three-fold increase has been observed in the yield of prompt gamma rays from a Portland cement sample of a 252Cf and a 241Am–Be source-based PGNAA setups.

Proton Insertion into Oxide Cathodes during Chemical Delithiation

A quantitative determination of proton contents in various chemically delithiated oxide cathodes has been carried out with prompt gamma-ray activation analysis (PGAA), and the results are complemented by mass spectrometric and thermogravimetric analysis data. While the delithiated layered Li 1-x CoO 2 , Li 1-x Ni 1/3 Mn 1/3 Co 1/3 O 2 , and Li 1-x Ni 1/2 Mn 1/2 O 2 show a significant amount of proton in the lattice at deep lithium extraction, orthorhombic Li 1-x MnO 2 , spinel Li 1-x Mn 2 O 4 , and olivine Li 1-x FePO 4 do not encounter such proton insertion. Interestingly, spinel Li 1-x Co 2 O 4 shows both proton insertion and oxygen loss at deep lithium extraction. The differences are attributed to the differences in the chemical instability of the various cathodes.

Cold Neutron Prompt Gamma-Ray Activation Analysis for Characterization of Hydrogen Storage and Related Materials

ABSTRACTPrompt gamma-ray activation analysis (PGAA) is an important technique for analyzing materials that may impact the hydrogen economy. An instrument for cold neutron PGAA, located at the NIST Center for Neutron Research (NCNR), has proven useful for the measurement of hydrogen and other elements in a variety of such materials. The detection limit for hydrogen is less than 10 mg/kg for most materials. PGAA has been used to characterize materials with potential for hydrogen storage (e.g. single wall carbon nanohorns, lithium magnesium imides, and zirconium beryllium hydrides), to measure hydrogen uptake by solid proton conductors, and to characterize stoichiometries of Nafion films used as membranes in fuel cells. Future upgrades to the instrument will improve detection limits, applicability, and user interface.

On the construction of a new instrument for cold-neutron prompt gamma-ray activation analysis at the FRM-II

A new flexible prompt gamma-ray activation analysis (PGAA) station will be installed and operated at the FRM-II reactor in Garching at the beginning of the year 2006. The PGAA station has been moved from the Paul Scherrer Institute (PSI), Villigen, Switzerland and is now being re-designed for three different experimental applications: PGAA instrument, cold neutron tomography setup and a compact Ge-array. Simulations of the beam guide have been carried out in order to yield the best conditions for each of the instruments, and are discussed here. A number of the PGAA applications are listed here. A new project dealing with a systematic measurement of bulky composition of small amount of meteorites (~100 mg) is proposed. Results of a test measurement of the Dhurmasala meteorite composition at the PGAA station at the Budapest Research Reactor are presented. Expected parameters of the PGAA facility at FRM-II are compared both with those at PSI and with the Budapest facility.

Sources of uncertainties in prompt gamma activation analysis

Two prompt gamma-ray activation analysis (PGAA) facilities at the NIST Center for Neutron Research have been used routinely to perform elemental analyses of a variety of materials. Results from these analyses are usually expressed as mass fraction values with expanded uncertainties. The expanded uncertainty consists of the combined uncertainty multiplied by the appropriate coverage factor (k) required to achieve a 95% confidence interval. The combined uncertainty includes the uncertainties associated with preparation, irradiation, and γ-ray spectrometry of samples and standards, and corrections for γ-rays from the background or blanks where necessary. To determine the combined uncertainty, each component of uncertainty associated with each variable and constant in the basic measurement equation is evaluated. In this paper we present the PGAA measurement equation, a description of the potential sources of uncertainty for each component of the equation, and three examples of uncertainty evaluation. The examples are for determination of H in standard reference material (SRM) 2454, hydrogen in titanium alloy using the cold neutron PGAA facility, Cd in SRM 2702 Inorganics in Marine Sediment using the original thermal neutron PGAA facility, and N in SRM 3244 Ephedra-Containing Protein Powder using the recently designed thermal neutron PGAA facility.

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

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 LiNi0.5Mn0.5O2 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 Li1-xCo1-yMyO2 (M = Cr, Mn, Fe, Ni, Cu, Mg, and Al) cathodes.

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

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.

Study on prompt gamma-ray spectrometer using Compton suppression system

The performance of the prompt gamma-ray activation analysis (PGAA) facility was improved by a series of modifications to the making composition of a Compton suppression system at HANARO, the 24MW research reactor in the Korea Atomic Energy Research Institute. An adjustment of the crystal was made by various efforts to obtain most suitable condition for the diffracted beam, the neutron flux was increased by 20% at the sample position to 8.4×107ncm−2s−1, and the Compton suppression ratio was 4.3–5 times below the Compton continuum region that appeared near the sample of interest such as boron. The PGAA facility at the HANARO research reactor serves as a major analytical tool for quantifying light elements in biological, geological and food samples. The sensitivity of boron is 1468cps/mg which is obtained from the slope of the boron peak count rate versus the boron mass. For the low background conditions, a supplement to the shielding materials on the detection assembly was made and the path of the beam line reduced the background count rate, which was evaluated from the boron data using the Compton- and single-mode. From this Compton suppressed gamma-ray spectrometer, we obtained high quality spectroscopic data from thermal neutron capture.

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).