Isotopic ratio of 129I/127I in seaweed measured by neutron activation analysis with gamma-gamma coincidence.

129I is a long-lived (1.6 x 10(7) y) radionuclide that is produced in nature as the result of spontaneous fission of heavy elements and reaction of xenon with cosmic rays. Recently, however, artificial sources from nuclear power plants and nuclear test explosions have become a significant component of environmental radioactive iodine.

Electron energy-loss spectroscopy study of amorphization process of graphite bombarded with hydrogen ions and energetic electrons at low temperatures.

Structural change of graphite bombarded with hydrogen ions as well as energetic electrons is investigated mainly by the EELS (electron energy-loss spectroscopy) technique, with a focus on the formation of diamond-like amorphous (DLA) phase at low temperatures. The chemical effects of hydrogen ions on the amorphization process are examined by comparing the results obtained by hydrogen-ion bombardment with those obtained by electron bombardment. The critical temperatures for the formation of DLA phase during hydrogen-ion and electron bombardments are determined.

Preparation of tritium standard gas by the use of tritiated methane.

Tritium standard gas for calibrating radioactivity detectors was prepared by the use of tritiated methane synthesized by the reaction of tritiated water with aluminum carbide at ca. 470 degrees C. A long-path proportional counter was used to standardize the radioactivity of the prepared gas.