Prompt Gamma-ray Analysis Research Articles

Applicability of prompt gamma-ray analysis to the initial analysis of the extraterrestrial materials for chemical composition

When extraterrestrial materials are returned to the earth by future space missions, these materials are to be subjected to the initial examination. For such purposes, measurements are desired to be done non-destructively. In this study, we investigated the applicability of non-destructive prompt gamma-ray analysis (PGA) for determining chemical composition of the returned materials, focusing on levels of induced radioactivities and the effect on isotopic composition by PGA. Under current conditions applied for the PGA facility at the Japan Atomic Energy Research Institute, essentially no residual radioactivities remain after appropriate cooling, making the same specimen analyzed by PGA usable for further research without any restriction. The effect on isotopic composition by PGA was examined both for neutron-induced reactions and for neutron-induced nuclear fission of 235U. No significant effect can be brought by neutron-induced reactions even for some noble gas nuclides such as 80Kr and 128I, which can be augmented by (n, γ) reactions on neighboring halogens. Neutron-induced nuclear fission reactions of 235U yield essentially no effect on isotopic composition. In addition, PGA has several advantages over other nondestructive analytical methods such as instrumental neutron activation analysis (INAA) and synchrotron radiation x-ray fluorescence (SR-XRF); INAA leaves a significant level of induced-radioactivities and SR-XRF yields less reliable and less accurate values for elemental composition. Judging from these features and characteristics, it is concluded that PGA can be one of the most suitable analytical methods potentially applicable for initial analysis of returned samples from space.

Investigations on neutron-induced prompt gamma ray analysis of bulk samples

A systematic investigation was carried out for the improvement of the prompt gamma interrogation method used for contraband detection by the pulsed fast/thermal neutron analysis (PFTNA) technique. Optimizations of source–detector shielding and geometry, role of the type and dimension of the gamma detector, attenuation of neutrons and gamma rays in bulky samples were also studied. Results obtained for both the shielding materials and elemental content of cocaine simulants have been compared with the values calculated by the MCNP-4A code.

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.

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%.

A noninvasive dose estimation system for clinical BNCT based on PG-SPECT--conceptual study and fundamental experiments using HPGe and CdTe semiconductor detectors.

A noninvasive method for measuring the absorbed dose distribution during the administration of clinical boron neutron capture therapy (BNCT) using an online three-dimensional (3D) imaging system is presented. This system is designed to provide more accurate information for treatment planning and dosimetry. The single-photon emission computed tomography (SPECT) technique is combined with prompt gamma-ray analysis (PGA) to provide an ideal dose estimation system for BNCT. This system is termed PG-SPECT. The fundamental feasibility of the PG-SPECT system for BNCT is confirmed under the following conditions: (1) a voxel size of 1 x 1 x 1 cm3, comparable to the spatial resolution of our standard dosimetric technique using gold wire activation, where data are available for every 5-10 mm of wire length; (2) a reaction rate of 10B(n,alpha)7Li within the measurement volume is greater than 1.1 x l0(6) interactions/cm3/s, corresponding to a thermal neutron flux of 5 x 10(8) n/cm2/s and a 10B concentration of greater than 10 ppm for the deepest part of the tumor volume under typical BNCT clinical conditions; (3) statistical uncertainty of the count rate for 10B(n,alpha)7Li prompt gamma rays is 10% or less. The desirable characteristics of a detector for the PG-SPECT system were determined by basic experiments using both HPGe and CdTe semiconductor detectors. The CdTe semiconductor detector has the greatest potential for this system because of its compactness and simplicity of maintenance.

Determination of Boron in Animal Materials by Reactor Neutron Induced Prompt Gamma-Ray Analysis

Boron concentration of plasma, feces, urine and body tissues from sheep fed with borated water (100 mg B/l) and tap water were determined by neutron-induced prompt gamma-ray analysis to elucidate boron metabolism. The B level in plasma and urine increased rapidly and the B content of feces increased greatly. The B concentrations in body tissues (liver, kidney, spleen, thyroid and muscle) of B dosed sheep were ten times higher than those of tap water administered sheep.

K0 Standardization Approach in Neutron-Induced Prompt Gamma-Ray Analysis at JAERI

The k0 standardization method has been studied and applied at JAERI for the accurate determination of multielements by neutron-induced prompt gamma-ray analysis (PGA). The k0 factors for 26 elements using Cl as a comparator were measured by the cold and thermal neutron guided beams of JRR-3M with an uncertainty less than 3% except for a few elements. The k0 factors for most elements obtained with both cold and thermal neutrons agreed within 3%, and agreed also with those measured at other cold and thermal neutron guided beams within 10%, except for a few elements. Multielement determinations in reference materials were performed using the k0 factors obtained to evaluate the accuracy and precision of this work.

Usefulness of Prompt Gamma-Ray Analysis with Guided Neutron Beams Compared to NAA

A neutron-induced prompt γ-ray analysis (PGA) has become widely utilized due to the improved analytical sensitivities and detection limits especially by using low energy guided neutron beams. Current studies on the low energy neutron guided beam PGA are reviewed. Historical backgrounds, current analysis systems, advantages when compared with conventional NAA, standardization for elemental determination and analytical applications in JAERI of the guided beam PGA are described.

Prompt gamma-ray analysis using cold and thermal guided neutron beams at JAERI.

A highly sensitive neutron-induced prompt gamma-ray analysis (PGA) system, usable at both cold and thermal neutron beam guides of JRR-3M, has been constructed. The system was designed to achieve the lowest gamma-ray background by using lithium fluoride tiles as neutron shielding, by placing the samples in a He atmosphere and by using a Ge-bismuth germanate detector system for Compton suppression. The gamma-ray spectrometer can acquire three modes of spectra simultaneously: single, Compton suppression, and pair modes. Because of the low-energy guided neutron beams and the low-background system, analytical sensitivities and detection limits better than those in usual PGA systems have been achieved. Boron and multielemental determination by a comparative standardization have been investigated, and accuracy, precision, and detection limits for the elements in various materials were evaluated. The system has been applied to the determination of B and multielements in samples of various fields such as medical, environmental, and geological sciences.

Prompt gamma-ray analysis (PGA) of meteorite samples, with emphasis on the determination of Si

Neutron-induced prompt gamma-ray analysis (PGA) was applied to seven meteorite samples (Allende, Zagami, Acfer 209, ALH77005, ALH84001, EET79001 and Neagari). Samples were irradiated in both the thermal neutron and the cold neutron guided beams of JRR-3M at JAERI. Multiple samples of an Allende standard powder were analyzed for Si using two different methods: (1) the comparison method, using a Si standard, and (2) the mono-standard method, using Fe as an internal reference element. The Si concentrations determined by these two methods are in good agreement with literature values. The analytical sensitivity for Si using the cold neutron guided beam is∼14.3× higher than that for the thermal neutron guided beam. Other elements determined (B, Ca, Ti and S) also showed higher sensitivities using the cold neutron beam. The other meteorites studied showed some anomalous B and S values likely due to the effects of terrestrial weathering/contamination.

Vertical distribution of elements in non-polluted estuarine sediments determined by neutron induced prompt gamma-ray and instrumental neutron activation analyses

Neutron induced prompt gamma-ray analysis (PGA) and instrumental neutron activation analysis (INAA) have been applied to the sediments collected from the Yasaka River estuary in Oita Prefecture, Japan. The vertical distribution of 33 elements in the sediments has been determined and compared with that in more polluted estuarine sediments. While the S content increased with increasing depth because of a sulphide accumulation under reducing condition, the increase in sulphide-forming elements such as Ag, Cd, Co and Zn was not observed in the deeper section of the Yasaka River estuarine sediments.

アルミニウム陽極酸化皮膜中の水素の濃度と分布

Electrolyte anions and water are incorporated in anodic alumina films during aluminum anodization. Component distribution is related to their physical and chemical properties and is related to the mechanism for forming anodic alumina films.Hydrogen in anodic alumina films separated from Al substrates was determined by a neutron-induced prompt gamma-ray analysis (PGA) system installed at an atomic reactor. Trace hydrogen was determined by liquid scintillation counting method for tritium in barrier films formed in an electrolyte containing tritium water. The hydrogen depth profile was measured after steps were etched into barrier films.Anodic alumina films consist of inner and outer parts, with electrolyte anions distributed to a depth half way from the outer electrolyte/oxide surface but not detected near the inner oxide/metal surface. Otherwise, 0.0035wt% hydrogen was distibuted throughout in the entire depth. We concluded that OH acts as a carrier, migrating to the oxide/metal surface and reacting with Al3+ near the oxide/metal interface.

Development of a Neutron-Capture Prompt Gamma-Ray Analysis System and Basic Studies of Element Analysis Using This System/Analysis of Steel and Copper by Cathodic Stripping Voltammetry

Development of a Neutron-Capture Prompt Gamma-Ray Analysis System and Basic Studies of Element Analysis Using This System/Analysis of Steel and Copper by Cathodic Stripping Voltammetry

Bone mass and soft tissue composition in adolescents with anorexia nervosa.

The relationship between bone mass and compartments of soft tissue was studied in 22 adolescent women with anorexia nervosa (mean, 17 years). Results were compared to data on age- and gender-matched controls. Bone mass of the lumbar vertebrae and femoral neck, fat and lean tissue was measured by dual energy X-ray absorptiometry (DXA). Bone mass in the central third of the skeleton, by neutron activation analysis (NAA), and body protein, by prompt gamma ray analysis (PGA), was measured on patients, but not controls. The patients had significantly lower values than controls in total weight (26%), lean tissue (16%), fat (60%), bone mass of lumbar spine (14%), and femoral neck (15%). The mean calcium bone index (CaBI), the central skeletal calcium normalized for body size based on height, was significantly lower than the value for external controls, (0.86 +/- 0.10 vs. 0.97 +/- 0.10). The nitrogen index (NI), body protein normalized for height, showed a similar reduction from external controls (0.84 +/- 0.10 vs. 1.0 +/- 0.10). Bone mass (both DXA and NAA data) was strongly correlated to lean tissue and to protein; the correlations to fat were weaker. Follow-up studies after 7-26 months in 12 patients showed a modest increase in weight (mean, 4.9 kg) which was due, primarily, to an increase in fat with only insignificant increase in lean tissue and in protein. In bone mass, there was either no change or further loss. Only four restored body weight to normal (BMI > 20) and they achieved normal menstruation, but even these four responders showed no increase in bone mass. Our studies confirm that adolescent females with anorexia nervosa suffer losses not only in all compartments of body composition, but also demonstrate that the restoration of bone mass lags behind improvement in soft tissue compartments. These results were independent of methods used for the measurements.

Multi-Element Determination by a Cold Neutron-Induced Prompt Gamma-Ray Analysis

A non-destructive multi-element determination using a cold neutron-induced prompt y-ray analysis (PGA) has been investigated. The elements H, C, N, Na, Mg, Al, Si, P, S, CI, K, Ca, Ti, Mn, Fe, Co, Cd, Sm, Gd and Hg were determined by a comparative standardization using the cold neutron guided beams of JRR-3M (upgraded Japan Research Reactor No. 3). To accurately determine the amounts of elements, possible interferences by other elements and background counts were examined and evaluated. Many elements in several reference materials, such as geological, environmental, and biological samples, coal and fuel oil, were determined, and the accuracy and precision of a multi-element determination were estimated. Toxic elements, such as Cd and Hg, at ug/g levels were accurately determined in environmental samples. The detection limits in various matrices were from 25 to 820 ng/g for Cd, Sm and Gd, 1.1 to 820 μg/g for H, Na, S, CI, K, Ti, Mn, Co and Hg, and 0.031 to 10% for C, N, Mg, Al, Si, P, Ca and Fe.

Quantitative Analysis of Boron in Plant and Soil Materials by Prompt Gamma Ray Analysis Using Reactor Guided Neutron Beams

Quantitative Analysis of Boron in Plant and Soil Materials by Prompt Gamma Ray Analysis Using Reactor Guided Neutron Beams

バリアー型アルミニウム陽極酸化皮膜中のホウ素の濃度と分布

In anodization of alminum, electrolyte anions are incorporated into the oxide film from the liquid electrolyte. The anion distribution is related to physical and chemical properties and the mode of film formation. Prompt Gamma-ray Analysis (PGA) has higt sensitivity (2000cps·mg-1) and a low detection limit (0.002μg) for boron, so it is applicable to the determination of boron in aluminum oxide films.It was found that the average boron content was 0.25wt% with electrolysis at 25°C in a 0.5mol·dm-3 H3BO3-0.05mol·dm-3 Na2B4O7 solution. Differences of the electrolytes and in formation voltages, i.e. in the thickness of the barrier films, had little effect on this value, but it varied in proportion to the boron concentration in the electrolyte and decreased at higher temperatures.Boron was distributed to a distance of half the depth from the surface, and was not detected near the oxide/metal interface. This result can be explained on the basis of the transport number (0.45-0.6) of Al(III) ion and by the absorption of borate ions into hydrous aluminum oxides.

ホウ酸硫酸混合電解液を用いるアルミニウムの陽極酸化とホウ素含有量

The boric/sulfuric acid anodizing process has been developed in the U. S. as a replacement for chromic acid anodizing to meet stricter environmental regulations. A comparative study has been conducted on the microstructures of boric/sulfuric acid films and sulfuric acid films. The sulfur and boron contents of the oxide films were determined by prompt gamma ray analysis. The type of V-t and I-t curves, and the morphology of pores were not appreciably influenced by the presence of boric acid in the anodizing bath, but the rate of formation of the boric/sulfuric acid films increased slightly and the rate of their disolution in phosphoric acid solution decreased slightly. The concentration of boric acid did not influence the amount of surfur incorporated into the oxide films. After the pores were sealed, surfur content decreased significantly due to the dissolution of sulfur compounds to the sealing solution.The boron content of porous type films was negligible, in the order of ppm. This is in remarkable contrast to the barrier type films formed in borate solutions, where boron contents of the order of several per cent have been reported. The boron content increased with increasing concentration of boric acid in the electrolytes.

Examination of errors caused by random summing in in vivo prompt gamma ray analysis

A technique is described for examining the mode of operation of radiation detectors and estimating the losses and gains caused by random summing effects in spectra acquired at high counting rates. The technique is applied to estimating the errors caused by random summing when measuring the amounts of carbon and nitrogen in the human body by the prompt gamma ray neutron activation analysis system installed in Leeds, UK. The authors' examination shows that the counting rate would have to increase to more than twice the value used at the method's calibration, before an error of greater than 10% is caused in the estimation of carbon by random summing effects, whilst for nitrogen a change of only 18% in the counting rate will cause a 10% error in its estimation.

The spectral shape and the components of the background in in vivo neutron capture prompt gamma ray analysis

The shape of the background spectrum and the different contributions to the background in in vivo neutron capture prompt gamma ray analysis have been studied using a 252Cf neutron source. Since the source of background and its contribution varies for different energy regions, the detector shielding and the facility construction materials may be different for each analyzed element. Limits of detection for in vivo measurement of Hg, Ca and N were determined.