Journal of Radiation Research

Electron Penetration through Aluminium

Takenobu HIGASHIMURA

1961 Volume 2 Issue 1 Pages 1-19
Published: June 01, 1961
Released on J-STAGE: August 29, 2006

DOIhttps://doi.org/10.1269/jrr.2.1

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The problem of electron penetration is treated analytically in an infinite homogeneous medium employing a segment model on the track of the electron. The intensity of the electron flux is obtained as a function of the energy, the direction of motion and the spatial variables. The numerical application is done for 2MeV perpendicular source in aluminium. Comparisons are made with Spencer's theory on energy dissipation and it is found that the moment coefficients of the electron flux obtained from both theories are generally consistent of with each other. Penetration probability calculated is compared with the experimental results and a fair agreement is found except in a shallow and a very deep layer. Energy distribution of the penetrating electron is also calculated, taking into consideration the straggling of the energy loss and the experimental plots well agree the theoretical distribution curve for moderate and deep penetration.

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Local Changes in ⁹⁰Sr Deposition in the Soil as Observed in Hokkaido Island, Japan

Sanshi ABE, Yutaka UENO, Tadashi YAMAGUCHI

1961 Volume 2 Issue 1 Pages 20-24
Published: June 01, 1961
Released on J-STAGE: August 29, 2006

DOIhttps://doi.org/10.1269/jrr.2.20

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We observed cumulative amount of ⁹⁰Sr in soils on different parts of Hokkaido Island in 1958-1959.
The results show that the amount of ^9OSr deposition ranges from 3mc/km² (at Obihiro) to 32mc/km² (at Imagane).
There is a high correlation (r=+0.75) between the mean annual precipitations at sampling stations and the accumulations of ⁹⁰Sr.
It is necessary to investigate with regard to the change of accumulations of ⁹⁰Sr in soils and correlation between accumlations of ⁹⁰Sr and meteorological conditions.

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Cesium 137 and Strontium 90 in Sea Water

Yasuo MIYAKE, Katsuko SARUHASHI, Yukio KATSURAGI, Teruko KANAZAWA

1961 Volume 2 Issue 1 Pages 25-28
Published: June 01, 1961
Released on J-STAGE: August 29, 2006

DOIhttps://doi.org/10.1269/jrr.2.25

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Concentration of Cs-137 and Sr-90 in the western North Pacific was determined. The content of Cs-137 ranged from 0.8 to 4.8 μμc/l while Sr-90 of 0.6 to 3.1 μμc/l was observed. These values are much higher than those obtained in the Atlantic and the eastern part of the North Pacific. The cause of higher contamination is due to the direct flowout of the fission product from the proving grounds in the tropical region of the Pacific. The reason for the lower ratio of Cs-137/Sr-90 in sea water is also discussed.

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Strontium 90 and Cesium 137 in Fallout Deposits and Implications of Their Ratio

Masami IZAWA, Hiroyuki TSUBOTA, Takashi NAGAI

1961 Volume 2 Issue 1 Pages 29-41
Published: June 01, 1961
Released on J-STAGE: August 29, 2006

DOIhttps://doi.org/10.1269/jrr.2.29

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Radioactivity in monthly fallout, which had been collected by the “pot” method, were measured for Sr-90 since October 1956 and Cs-137 since August 1957. Total accumulated amount up to July 1960 were 15 me/km² for Sr-90 and 31mc/km² for Cs-137. Distinct spring maxima of fallout rate were observed on May 1959 and 1960. Ratio of the total activities of Cs-137 and Sr-90 since August 1957 were 2.8, which is higher than the assumed ratio from nuclear fission processes, and ratio Cs-137/Sr-90 vary considerably from month to month (1.8-8.2).
The high observed ratio can be explained mainly from the differences in the half-lives of the ancestor radionuclides of Sr-90 and Cs-137, i.e., Kr-90 (33 sec) and Xe-137 (3.9 min), respectively, while monthly variation of the ratios can be explained from meteorological conditions in the rain-bearing layer of troposphere.

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Biophysical Interpretation on the Biological Actions of Radiations (I) (Correspondence between the Relay-contact System and the Gene-enzyme System and Some Discussions on the Target Theory)

Yasushi NISHIWAKI

1961 Volume 2 Issue 1 Pages 42-60
Published: June 01, 1961
Released on J-STAGE: August 29, 2006

DOIhttps://doi.org/10.1269/jrr.2.42

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From the analogy between the complex gene-enzyme system governing the metabolic current in the cell and the complex electric switching circuit system governing the electric current, the induction of mutation may be compared to the blocking or alteration of different parts of the switching system at random by the mutagenic agents or by the action of radiations. Based upon the results of analysis of such a complex system with the symbolic logic or Boolean algebra, more general types of the multi-target hit functions are introduced and some special cases which may be useful in the analysis of the dose-survival and the dose-effect curves are discussed. Under the condition where the effective action field of radiation is large in comparison with the mean separation of the unit target switches, a major part of the complex switching system in the cell may be blocked or altered simultaneously by a single hit of radiation and it may appear as if there exists only a single target in the cell. With the reduction of the effective action field of radiation the dose-survival curve may have a tendency to become a sigmoid type and may be approximated by a more complex type of hit functions corresponding to the apparent internal structure of the cell explicit tinder the condition of the experiment.

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