SOLID STATE DOSIMETERS FOR RADIATION MEASUREMENT

Technical Report · Fri Oct 31 04:00:00 EST 1958

OSTI ID:4307708

Schulman, J H

Exposure to ionizing radiation can produce changes in a number of the physical properties of insulating solids. Changes in optical properties-- specifically in absorption and luminescenee--are especially striking with some materials, and these effects have been extensively investigated for application to dosimetry. Resulting from these investigations are dosimetric devices characterized by great convenienoe in handling, long and perhaps unlimited shelf life, small volume, and ruggedness. The dose range that can be measured by solid state detectors is literally enormous, extending from the order of milliroentgens to beyond 10/sup 8/ roentgens, depending upon the phenomenon employed. All solid state dosimeters are secondary instruments and must be calibrated against some standard, such as an ion chamber. Because of the definition of the roentgen solid state dosimeters exhibit an energy-dependent response, particularly at low energies. This is especially serious with inorganic solids because of the comparetively high atomic numbers of their constitueats. Selective shielding of these devices has been successfully employed in order to achieve a reasonable energy independence. The general theory underlying inorganic solid detectors may be summarized as follows. When an electron is freed from an atom by irradiation of a solid, it may wander through the material until it is trapped by some constituent, such as a chemical impurity, or by some region of the solid containing a flawy or defect in the structure. The entity or center formed by combination of the electron with the trapping site has different optical properties from the normal solid, i.e., it may absorb light in a spectral region where the normal solid is transparent (coioration), it may emit fluorescent light under conditions where the normal solid would not do so (radiophotoluminescence, thermoluminescence, or stimulable luminescence), or it may fail to flnoresce under conditions where the normal solid would emit light (degradation or quenching of lumincscence). These radiationinduced changes are detected by optical techniques and constitute a measure of the dose. The centers are responsible for coloration, radiophoto- luminescenoe, or the degradation of luminescence are generally quite stable, permitting repeated measurement of the dose if desired. The centers giving rise to thermoluminescence or stimulated luminescence are necessarily destroyed by the measurement procedure, so that the dose reading cannot generally be repeated. Dosimeters based upon all the above mentioned effects are described, their operational advantages and limitations are delineated, and their applications are discussed in personal monitoring, internal dosimetry, and in the radiationpreservation of foods. (auth)

• Research Organization: Naval Research Lab., Washington, D.C.
• NSA Number: NSA-12-014929
• OSTI ID: 4307708
• Report Number(s): A/CONF.15/P/1859
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ABSORPTION-- ATOMS-- CHARGED PARTICLES-- DOSEMETERS-- ELECTRIC CHARGES-- ELECTRIC CONDUCTIVITY-- ENERGY-- FOOD-- LUMINESCENCE-- MONITORING-- PERSONNEL-- RADIATION DOSES-- SHIELDING-- SOLIDS-- STABILITY-- STANDARDS-- USES
ABSORPTION-- COMPOUNDS-- DOSEMETERS-- ELECTRONS-- FLUORESCENCE-- IMPURITIES-- LATTICES-- LIGHT-- SOLIDS-- THERMODYNAMICS
PHYSICS