Gamma-Ray Measurement of <sup>152</sup>Eu Produced by Neutrons from the Hiroshima Atomic Bomb and Evaluation of Neutron Fluence

Kato, Kazúo; Habara, Minoru; Aoyama, Tetsuhisa; Sakata, H.; Yoshizawa, Yasukazu

doi:10.1143/jjap.29.1546

Cited by 9 publications

(11 citation statements)

References 4 publications

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“…This was similar to the fact that the 7,8) . The filled squares ( ) show the activities estimated from the calculated ones based on the DS02 10,11) .…”

Section: The 36supporting

confidence: 74%

“…Filled triangles indicate the ratios measured by Nakanishi et al 6) . Open circles and crosses show the ratios measured by Kato, et al 7,8) .…”

Section: Samplesmentioning

confidence: 93%

“…Because of the long life (13.537 y) 1) , the 152 Eu activities are still measurable. Many investigations have been performed for measuring the 152 Eu/Eu ratios in the rock samples exposed to the Hiroshima atomic bomb [2][3][4][5][6][7][8] . The data on the .…”

Section: Introductionmentioning

confidence: 99%

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Measurements of 152Eu/Eu ratios in surfaces of rock samples near the hypocenter of the Hiroshima atomic bomb

Kato

Honjyo

2011

Radiat. Safety. Manag.

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The152 Eu/Eu ratios were measured at various surface positions of two granite samples (gravestones) in the vicinities of the hypocenter of the Hiroshima atomic bomb. The sample pieces were dissolved and the europium elements were chemically isolated. The radioisotopes of Actinium series in the rock samples were excluded from the europium samples. The measured 152 Eu/Eu ratio was not constant in each surface, and was low at the surface positions close to neighbor gravestone. The 152 Eu/Eu ratios were high at the positions that were largely open for the scattered neutrons from the soil ground. This suggests that the rock materials between sample and soil ground reduced thermal neutron fluence to the sample.

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“…This was similar to the fact that the 7,8) . The filled squares ( ) show the activities estimated from the calculated ones based on the DS02 10,11) .…”

Section: The 36supporting

confidence: 74%

“…Filled triangles indicate the ratios measured by Nakanishi et al 6) . Open circles and crosses show the ratios measured by Kato, et al 7,8) .…”

Section: Samplesmentioning

confidence: 93%

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Measurements of 152Eu/Eu ratios in surfaces of rock samples near the hypocenter of the Hiroshima atomic bomb

Kato

Honjyo

2011

Radiat. Safety. Manag.

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“…Various radionuclides produced by neutron activation were detected. 60 Co, 152 Eu, and 154 Eu were measured by gamma-spectroscopy [60,69,70]. In this gravestone, two further radioisotopes, 36 Cl and 41 Ca with half-lives of 3 · 10 5 years and 10 5 years, respectively, could be determined for the first time [65,[71][72][73].…”

Section: Developments After the Release Of Ds86mentioning

confidence: 95%

The dosimetry system DS86 and the neutron discrepancy in Hiroshima - historical review, present status, and future options

Rühm¹,

Kellerer²,

Korschinek

et al. 1998

Radiation and Environmental Biophysics

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The historical development of the dosimetry systems for Hiroshima and Nagasaki is outlined from the time immediately after the A-bomb explosions to the publication of the dosimetry system DS86 in 1987, and the present status of the so-called Hiroshima neutron discrepancy is summarized. Several long-lived radionuclides are discussed with regard to their production by neutrons from the A-bomb explosions. With the exception of 63Ni, these radionuclides have not, up to now, been measured in samples from Hiroshima and Nagasaki. Two of them, 63Ni in copper samples and 39Ar in granite samples, were predominantly produced by fast neutrons. 63Ni can be determined by accelerator mass spectrometry with a gas-filled analyzing magnet. It should be measurable, in the near future, in copper samples up to 1500 m from the hypocenter in Hiroshima. 39Ar can be measured in terms of low-level beta-counting. This should be feasible up to a distance of about 1000 m from the hypocenter. Three radionuclides, 10Be, 14C, and 59Ni, were produced predominantly by thermal neutrons with smaller fractions due to the epithermal and fast neutrons, which contribute increasingly more at larger distances from the hypocenter. State-of-the-art accelerator mass spectrometry is likely to permit the determination of 10Be close to the hypocenter and of 14C up to a distance of about 1000 m. 59Ni should be detectable up to a distance of about 1000 m in terms of accelerator mass spectrometry with a gas-filled magnet. The measurements of 10Be, 14C, 39Ar, 59Ni -- and potentially of 131Xe -- can be performed in the same granitic sample that was already analyzed for 36Cl, 41Ca, 6Co, 152Eu, and 154Eu. This will provide extensive information on the neutron spectrum at the specified location, and similarly complete analyses can conceivably be performed on granite samples at other locations.

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“…The measured ratio was approximately twice that calculated in free air by the DS02 11,12,13) . Kato et al 14) measured the 152 Eu/Eu ratios in a gravestone (the Niitani family's gravestone) in the vicinity of the hypocenter. As shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Exclusion of natural radioisotopes for measurements of 152Eu in granites exposed to the Hiroshima atomic bomb

Kato

Kikkawa²,

Iwamoto

2009

Radiat. Safety. Manag.

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Precise 152 Eu gamma-ray measurements in the granite samples exposed to the Hiroshima atomic bomb require concentrating the europium (Eu) and excluding natural radioisotopes. In this study, an ion exchange method was applied for isolating Eu ions from granite samples at 56 m, 502 m and 818 m distances from the hypocenter. Although the Eu samples included 232 Th atoms, the 152 Eu 344 keV gamma-ray full energy peaks were scarcely affected by the gamma rays from the radioisotopes of the thorium series. Almost all of the radioisotopes in the uranium and actinium series were removed. The Eu contents were determined by atomic absorption spectrometry. The 152 Eu specific radioactivities in the samples at 56 m and 502 m were higher than those inferred from the DS02 calculations. In the sample at 818 m, the measured value was in agreement with the calculated value based on the DS02. Estimations of the atomic bomb radiation doses are necessary for many investigations which attempt to decide the acceptable levels of radiation risk to the public and workers. The results in the present study will be useful for studying the uncertainties of the estimated atomic bomb radiation doses.

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Gamma-Ray Measurement of ¹⁵²Eu Produced by Neutrons from the Hiroshima Atomic Bomb and Evaluation of Neutron Fluence

Cited by 9 publications

References 4 publications

Measurements of 152Eu/Eu ratios in surfaces of rock samples near the hypocenter of the Hiroshima atomic bomb

Measurements of 152Eu/Eu ratios in surfaces of rock samples near the hypocenter of the Hiroshima atomic bomb

The dosimetry system DS86 and the neutron discrepancy in Hiroshima - historical review, present status, and future options

Exclusion of natural radioisotopes for measurements of 152Eu in granites exposed to the Hiroshima atomic bomb

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Gamma-Ray Measurement of 152Eu Produced by Neutrons from the Hiroshima Atomic Bomb and Evaluation of Neutron Fluence

Cited by 9 publications

References 4 publications

Measurements of 152Eu/Eu ratios in surfaces of rock samples near the hypocenter of the Hiroshima atomic bomb

Measurements of 152Eu/Eu ratios in surfaces of rock samples near the hypocenter of the Hiroshima atomic bomb

The dosimetry system DS86 and the neutron discrepancy in Hiroshima - historical review, present status, and future options

Exclusion of natural radioisotopes for measurements of 152Eu in granites exposed to the Hiroshima atomic bomb

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Gamma-Ray Measurement of ¹⁵²Eu Produced by Neutrons from the Hiroshima Atomic Bomb and Evaluation of Neutron Fluence