Fast neutrons measured in copper from the Hiroshima atomic bomb dome.

The first measurements of (63)Ni produced by A-bomb fast neutrons (above approximately 1 MeV) in copper samples from Hiroshima encompassed distances from approximately 380 to 5062 m from the hypocenter (the point on the ground directly under the bomb). They included the region of interest to survivor studies (approximately 900 to 1500 m) and provided the first direct validation of fast neutrons in that range. However, a significant measurement gap remained between the hypocenter and 380 m.

The plutonium isotopic composition of marine biota on Enewetak Atoll: a preliminary assessment.

We have determined the level and distribution of gamma-emitting radionuclides, plutonium activity concentrations, and 240Pu/239Pu atom ratios in tissue samples of giant clam (Tridacna gigas and Hippopus hippopus), a top snail (Trochus nilaticas) and sea cucumber (Holothuria atra) collected from different locations around Enewetak Atoll. The plutonium isotopic measurements were performed using ultra-high sensitivity accelerator mass spectrometry (AMS). Elevated levels of plutonium were observed in the stomachs (includes the stomach lining) of Tridacna clam (0.

Neutron-induced 63Ni in copper samples from Hiroshima and Nagasaki: a comprehensive presentation of results obtained at the Munich Maier-Leibnitz Laboratory.

Those inhabitants of Hiroshima and Nagasaki who were affected by the A-bomb explosions, were exposed to a mixed neutron and gamma radiation field. Few years later about 120,000 survivors of both cities were selected, and since then radiation-induced late effects such as leukemia and solid tumors are being investigated in this cohort. When the present study was initiated, the fast neutron fluences that caused the neutron doses of these survivors had never been determined experimentally.

Measurement of beryllium in biological samples by accelerator mass spectrometry: applications for studying chronic beryllium disease.

A method using accelerator mass spectrometry (AMS) has been developed for quantifying attomoles of beryllium (Be) in biological samples. This method provides the sensitivity to trace Be in biological samples at very low doses with the purpose of identifying the molecular targets involved in chronic beryllium disease. Proof of the method was tested by administering 0.

Measuring fast neutrons in Hiroshima at distances relevant to atomic-bomb survivors.

Data from the survivors of the atomic bombs serve as the major basis for risk calculations of radiation-induced cancer in humans. A controversy has existed for almost two decades, however, concerning the possibility that neutron doses in Hiroshima may have been much larger than estimated. This controversy was based on measurements of radioisotopes activated by thermal neutrons that suggested much higher fluences at larger distances than expected.

Accelerator mass spectrometry of 63Ni at the Munich Tandem Laboratory for estimating fast neutron fluences from the Hiroshima atomic bomb.

After the release of the present dosimetry system DS86 in 1987, measurements have shown that DS86 may substantially underestimate thermal neutron fluences at large distances (>1,000 m) from the hypocenter in Hiroshima. This discrepancy casts doubts on the DS86 neutron source term and, consequently, the survivors' estimated neutron doses. However, the doses were caused mainly by fast neutrons.