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: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:N. Oshima, E. Hamada, T. Suzuki, K. Kondo, I. Kanazawa, and Y. Ito
Pulsed slow positrons were produced using a time-varying moderator bias with an interval of 82 ns; 97% of the positrons were
compressed within 2 ns width at the target position. Both the positron annihilation lifetime and Doppler broadening of the
positron annihilation radiation (DBPR) of polytetrafluoroethylene (PTFE) were measured as a function of the incident energy
of slow positrons. It was shown that the lifetime and intensity of the long-lived component of positron annihilation are independent
of the positron incident energy above 1.2 keV. However, the width of the Doppler-broadened annihilation γ-ray increased in
the energy region below 1.2 keV.
Authors:Y. Hatsukawa, Y. Toh, M. Oshima, T. Hayakawa, N. Shinohara, K. Kushita, T. Ueno, and K. Toyoda
Multiparameter coincidence g-ray spectrometry based on g-g coincidence is widely used in the field of nuclear structure studies, and has produced many succesful results. In this paper, feasibility of the method for neutron activation analysis of trace elements was studied. Particularly, a long-lived radioisotope 129I (T1/2 = 1.57.107 y) in algae samples and iridium in geological samples has been determined.
Authors:T. Suzuki, Y. Oki, M. Numajiri, T. Miura, K. Kondo, N. Oshima, T. Hayashi, H. Nakamura, and Y. Ito
The polymerization process of bisphenol-A dicyanate (BADCy) has been studied using a positron-annihilation lifetime technique (PAL). The polymerization was conducted at 150°C, and the process was followed by PAL. Seven kinds of samples with different curing times were also formed at 150°C, and the relation between the period of the curing time and the degree of polymerization was studied. It has been shown that theo-Ps lifetime increases in samples with a higher polymerization than 85%, which is consistent with measurements of the specific volume of BADCy.