A new determination method for222Rn and220Rn in water sample was developed by extracting radon with toluene and applying the integral counting method with a liquid
scintillation counter. The essential characteristics of the methods are, (1) extraction of radon with toluene from water,
(2) finding absolute counts and making corrections for the quenching effect by the adoption of the integral counting method,
(3) the determination of222Rn and220Rn was performed by counting the activity of220Rn with its descendants and of ThB (212Pb) with its descendants in a radioactive equilibrium, respectively, (4) realizing high sensitivity by simultaneous counting
of α, β− particles emitted from the decay products formed in toluene. The lowest detection limit obtained by the present method was
5.0·10−13 Ci/l for222Rn and 6.8·10−8 Ci/l for220Rn in water.
A new method is described for the determination of Rn in soil gas. Open vials containing a liquid scintillator solution, suspended
in a hole of the ground surface, absorb a fixed proportion of Rn present in soil gas. This allows the total Rn concentration
to be determined. The method described is rapid, simple and reproducible. It should have many kinds of field application.
Authors:H. Nakahara, K. Masago, Y. Nakamura, K. Horiuchi, and Y. Murakami
Neutron activation analyses were performed for the newly issued reference rocks, GSJ JA-1 and JB-2, and also for the widely
distributed GSJ JG-1 and JB-1. The contents of fourteen elements could be newly determined for the former two rocks and those
of eleven elements were re-determined for the latter rocks.
Authors:H. Nakahara, M. Tsukada, A. Moriizumi, K. Horiuchi, and Y. Murakami
The improvement obtained by epithermal neutron activation analysis was studied in terms of the detection sensitivity and precision
in the γ-ray spectrometry for geological and biological reference samples. For geological samples, small improvement was observed
only for the elements As, Ba, Sb, Se and U. For biological samples, however, large improvement was observed for As, Br, Sb
and U. The ratio of the resonance integral to the effective thermal-neutron capture cross section was observed for 19 nuclides.
The effect of the (n, p) reaction to the determination of Al and Mg by the ordinary reaktor-neutron activation analysis was
Authors:H. Muramatsu, S. Yoshizawa, T. Abe, T. Ishii, M. Wada, Y. Horiuchi, and R. Kanekatsu
The concentration of 7Be in surface air at Nagano City has been measured during the period from August 2000 to March 2005. The average monthly concentrations
of 7Be in surface air were in the range of 3.3–14 mBq/m3 with pronounced two peaks in spring and autumn. It took 30–40 hours to recover the 7Be concentrations observed before, once 7Be was washed out by wet precipitations. For a pronounced increase in the concentrations of 7Be found in winter, a low-pressure trough coming close to the Japanese Islands with high concentrations of 7Be is responsible under the characteristic distribution of atmospheric pressure around the Japanese Islands.