Measurements of External Environmental Radiation in the United States

The development of field-based measurement methods for radioactive fallout assessment

An overview is provided on the development of field equipment, instrument systems, and methods of analyses that were used to assess the impact of radioactive fallout from atmospheric weapons tests. Included in this review are developments in fallout collection, aerosols measurements in surface air, and high-altitude sampling with aircraft and balloons. In addition, developments in radiation measurements are covered in such areas as survey and monitoring instruments, in situ gamma-ray spectrometry, and aerial measurement systems. The history of these developments and the interplay with the general advances in the field of radiation and radioactivity metrology are highlighted. An emphasis is given as to how the modifications and improvements in the instruments and methods over time led to their adaptation to present-day applications to radiation and radioactivity measurements.

Apatite: Origin of Blue Color

The optical absorption and emission spectra of natural blue apatite are similar enough to spectra of synthetic compounds containing MnO(4)(-3) to conclude that the blue color of natural apatite results from the presence of this ion.