Dosimeter materials

Pre-exposure proeessing and preparation of the inner and outer whole-body dosimeters for use in the field should be eonsidered. The analytieal laboratory should determine if the fabric of the dosimeter of choice contains any analytical interference, which may be a problem in subsequent analysis of the fabric. If such analytical interferences are present in the fabric of the dosimeter, they may be reduced by pre-washing the dosimeter material prior to use in the field. The dosimeter is usually pre-washed (sometimes more than once) and rinsed several times prior to thorough drying. The washing detergent of choice should be as free as possible from additive brighteners and other chemicals, which may cause analytical interferences. 

Inner dosimeter sections should be covered with outer dosimeter material to simulate the environment of the inner dosimeter on the volunteer, which would normally be covered by the outer dosimeter. This procedure can be accomplished by pinning the outer dosimeter material over the inner dosimeter section using straight pins. Outer dosimeter sections, patches, or other exposed matrices should not be covered. 

With respect to worker safety and re-entry studies, reference substances are necessary to assay the test substance (and, if applicable, any control substance) and determine its stability and for the analyses of specimens collected in the study. Specimens may include plant material (dislodgeable residues), adsorbent media (inhalation), or clothing/dosimeter materials collected during a worker safety study to assess exposure. If biomonitoring is involved, blood and/or urine specimens may be analyzed against reference substances of known purity. 

Development of Dosimeter Materials. - 4.2.1 Quantitative ESR and Intensity Standards of Mn1+ and CuS04.5H20. An ESR spectrometer consists of vacuum tube amplifier and a Klystron oscillator with thermal noise and frequency drift. Hence, an inherent standard of Mn2+ was used in ESR dating of carbonate stalactites,8 and patented as a standard in ESR radiation dosimetry in 1980.102 The standard sample of MgO with Mn2+ is frequently used for calibration of -factor and the magnetic field as well as for radiation dosimetry.103... 

A large number of organic and inorganic materials which exhibit photochromism have been known for many years. Such materials have been applied in many areas of technology to use them as dosimeter materials, light control filters, recording films in photography and decorative paints. 

Line-width The amplitude of an ESR 1st derivative line is inversely proportional to the line-width squared at a fixed concentration of free radicals. A narrow line-width is therefore desirable. The anisotropy of the g-factor and/or the hyperfine coupling causes line broadenings in several of the commonly used dosimeter materials, e.g. alanine and Li-formate. The line-width also tends to increase at microwave saturation, which is an additional reason for not increasing the power excessively. In practice the signal of an ESR-dosimeter may be distributed over several hyperfine lines, causing loss of sensitivity. For alanine five lines are present (Fig. 9.3). 

The free radical yields of the potential ESR-dosimeter materials in Table 9.2 are in several cases not known. In other cases G-value data obtained in independent studies of a specific substance disagree, indicating that the techniques of quantitative ESR spectrometry were not generally established at the time the measurements were done [4],... 

The sensitivity S of potential ESR dosimeter materials can be estimated by an equation showing the dependence on the microwave power (P), the line-width (w) and the radiation yield (G) [20] ... 

Pig. 9.15 Experimental (+) and theoretical (-) saturation curves for radicals trapped in an X-irradiated crystalline dosimeter material... 

High sensitivity to radiation, exceeding that of all other dosimeter materials the ratio of the TL response per unit detector mass and radiation dose constitutes 54 27 7 1 for AIN, LiF Mg,Cu,P, AI2O3 C, and LiF Mg,Ti, respectively. TL curves of these dosimetric materials after the same dose of beta radiation are shown in Figure 9.17. From this figure it is seen that AlN ceramics obtains a wide and structureless TL peak in the 100 - 500 thermal range. 

It was found that AIN ceramics is very sensitive to UV light. To estimate its applicability for needs of UV dosimetry it was studied in comparison with AI2O3 - a widely used dosimeter material suitable for measurements of UV dose [30]. 

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