Exposure Rate Constants

The "Specific Exposure Rate Constant", sometimes known as the "Gamma Factor", is the exposure rate at a specific distance from a given amount of a photon-emitting radionuclide. These constants are used frequently for radiation protection purposes. The following is a listing of Specific Exposure Rate Constants for a variety of radionuclides, in units of Roentgens per hour (R/hr) at a distance of one (1) meter from a one (1) curie point source of that radionuclide.

Actinium

Aluminum

Americium

Antimony

Argon

Arsenic

Astatine

Barium

Berkelium

Beryllium

Bismuth

Bromine

Cadmium

Calcium

Californium

Carbon

Cerium

Cesium

Chlorine

Chromium

Cobalt

Copper

Curium

Dysprosium

Einsteinium

Erbium

Europium

Fermium

Fluorine

Francium

Gadolinium

Gallium

Germanium

Gold

Hafnium

Holmium

Indium

Iodine

Iridium

Iron

Krypton

Lanthanum

Lead

Lutetium

Magnesium

Manganese

Mercury

Molybdenum

Neodynium

Neptunium

Nickel

Niobium

Nitrogen

Osmium

Oxygen

Platinum

Plutonium

Polonium

Potassium

Praseodynium

Promethium

Protactinium

Radium

Radon

Rhenium

Rhodium

Rubidium

Ruthenium

Samarium

Scandium

Selenium

Silicon

Silver

Sodium

Strontium

Tantalum

Technetium

Tellurium

Terbium

Thorium

Thullium

Tin

Titanium

Tungsten

Uranium

Vanadium

Xenon

Ytterbium

Yttrium

Zinc

Zirconium

**Listing partially extracted from ORNL/RSIC-45, "Specific Gamma-Ray Dose Constants for Nuclides Important to Dosimetry and Radiological Assessment", 1981.

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