Authors:Y. Toh, M. Oshima, M. Koizumi, A. Kimura, and Y. Hatsukawa
In order to improve the limits of quantification for trace elements, we applied the multiple gamma-ray detection method in
the prompt gamma-ray analysis (PGA). The Clover Ge detector system was constructed for multiple prompt gamma-ray analysis
(MPGA) at the neutron guide hall of the JRR-3M reactor of the Japan Atomic Energy Agency (JAEA). The MPGA system consists
of three Clover detectors and a BGO Compton suppressor. The instrumentation of the MPGA beam line and the detector system
were developed. The estimated limit of quantification of cadmium in the plastic sample is approximately 0.1 ppm. The capability
of the MPGA system could be improved by modification of the detector system, shield arrangement, software algorithm, etc.
Authors:Y. Hatsukawa, M. Oshima, T. Hayakawa, Y. Toh, and N. Shinohara
Feasibility of the method of multidimensional -ray spectrometer for neutron activation analysis was examined. Reference igneous rock (JP-1, JB-1a and JB-1) samples issued by the Geological Survey of Japan (GSJ) and the Allende meteorite reference sample were irradiated in a research reactor, and multiple -rays from the produced radioisotopes via neutron capture reactions were measured using an array of twelve germanium detectors with BGO Compton suppressors called GEMINI. Simultaneously thirty elements were observed with no chemical separation. The observed smallest component was Eu contained in JP-1 with abundance of 4 ppb.
Authors:Y. Toh, M. Oshima, Y. Hatsukawa, T. Hayakawa, and N. Shinohara
A comparison method, utilizing neutron activation analysis followed by multidimensional spectrum analysis was proven to provide accurate quantification of the multi-element samples. In this study, 23 elements were detected simultaneously in a sample containing standard elements for neutron activation analysis. The method presented here can be applied for about 50 elements.
Authors:A. Kimura, Y. Toh, M. Oshima, Y. Hatsukawa, and J. Goto
Recycled steel products demands a new technique for determining tramp elements in steel. In this paper, As and Sb in iron
certified reference materials were determined by neutron activation analysis with the multiple gamma-ray detection method.
The determined values are in good agreement with certified and reference values. The lower determination limits (LDL) for
As and Sb in high purity iron are 0.012 and 0.0025 ppm, respectively. As the demanded LDL for As and Sb is 0.1 ppm, the method
described in this work is suitable for determining As and Sb in recycled steel.
Authors:H. Honda, A. Oshima, H. Hinode, and M. Wakihara
Enthalpy increment HT-H289K measurements have been made on iron Chevrel phase sulphide Fe2Mo6S7.8, in the temperature range 300 to 500 K by the drop method using a hightemperature Calvet-type twin calorimeter. The first-order phase transition of this sulphide from a triclinic (low-temperature phase) to a rhombohedral (high-temperature phase) occurred at 375 K, and the enthalpy was evaluated to be 6.0 kJ/mol. The heat capacities of iron Chevrel phase sulphide Fe2Mo6S7.8 were also calculated before and after the phase transition.
Authors:A. Kimura, Y. Toh, M. Oshima, and Y. Hatsukawa
Recycling steel products demands a new technique for determining tramp elements in steel. Tramp elements, As and Sb, in some
iron certified reference materials were determined by neutron activation analysis with multiple gamma-ray detection method
and reported in MTAA11. In MTAA12, the authors reported the lower limit of determination values (LDL) and the dispersion of
this method. The values of the LDLs for As and Sb in high purity iron were 0.002 and 0.0009 μg·g−1. The dispersion is small enough to satisfy the demand from materials science.
Authors:M. Oshima, Y. Toh, A. Kimura, M. Ebihara, Y. Oura, Y. Itoh, H. Sawahata, and M. Matsuo
By combining neutron activation analysis with multiple gamma-ray detection (gamma-gamma coincidence), we have proved better
sensitivity and resolution for the trace element analysis than the ordinary single gamma-ray detection method. We now try
to apply the multiple gamma-ray detection method to the prompt gamma ray analysis (PGA). We have established a new cold neutron
beam line for PGA in Japan Research Reactor, JRR-3M, at Tokai establishment of Japan Atomic Energy Research Institute (JAERI).
It consists of a beam shutter, a beam attenuator, a gamma-ray detector array, a sample changer, and a beam stopper. We construct
a high-efficiency gamma-ray detector array specially designed for this purpose. Its performance has been evaluated with the
Monte Carlo simulation code, GEANT 4.5.0.
Authors:M. Oshima, Y. Toh, Y. Hatsukawa, M. Koizumi, A. Kimura, A. Haraga, M. Ebihara, and K. Sushida
A new radionuclide quantification method is proposed on the basis of multiple gamma-ray detection, which is two or higher
fold gamma-ray coincidence method. The coincidence method has so far been used for nuclear structure study. We apply this
method for quantification of radioactive nuclei. The advantage of this method consists of high energy resolution and high
sensitivity. It is successfully applied to nuclear waste analysis, neutron activation analysis and prompt gamma-ray analysis.
The principle of the multiple gamma-ray detection method and future perspectives for an innovative pulsed neutron source and
a new detector system will be presented.
Authors:Y. Hatsukawa, Y. Toh, M. Oshima, A. Kimura, and M. Hosein Mahmudy Gharaie
In this study, sensitive trace element analyses were carried out without chemical separation by the combination of neutron
activation analysis and multi-parameter coincidence spectroscopy. A long-lived radioisotope 129I in algae samples and iridium in geological samples were analyzed.
Authors:Y. Hatsukawa, Y. Miyamoto, Y. Toh, M. Oshima, M. Hosein Mahmudy Gharaie, K. Goto, and K. Toyoda
In this study, using neutron activation analysis with multi-parameter coincidence method which was developed at Japan Atomic
Energy Agency (JAEA), a non-destructive, ultra-high sensitive multi-elemental determination has been realized. The multi-parameter
coincidence method is carried out with an array of 19 germanium detectors, GEMINI-II. Using this system, very weak γ-rays
emitted from trace amounts of elements can be detected. The iridium concentration has been determined by means of neutron
activation analysis with multi-parameter coincidence method for Cuban sediment samples across the K/T boundary strata.