Pen dosimeter

FIG. 7.8. Pen dosimeter with direct readout of the dose. (From Lapp and Andrews, 1948.)... 

Photographic emulsions are sensitized by ionizing radiation resulting in darkening upon development. This is used in the film dosimeter for measurement of 0-, y-, or n-doses. In order to differentiate between various types of radiation, the film is siUTOunded by filters or transfer screens. Although any type of film may be used, special nuclear emulsions have been designed. The dose received is directly proportional to the optical daisity of the exposed film. Film dosimeters are useful in the same range as the pen dosimeter, and both are used for personnel measurements. While the pen dosimeter can be read directly, the film dosimeter requires development. 

A direct reading condenser chamber (pen dosimeter) is charged from a battery pack so that full scale (1(X)) is obtained at 20 V. When conqtletely discharged, the accumulated dose is 5.00 mGy. The gas volume is 4 cm air (STP). What is the capacitance of the condenser chamber ... 

The protection follows three stages prevoition, supervision, and after-control. Preventive measures include use of fume hoods, or-boxes, radiation shielding, tongs, etc., as discussed above. The supervision stage involves the use of radiation instrum ts to monitor the radiation level (see Ch. 8). Small TLD, film or pocket pen dosimeters are used for individual monitoring ( 7.9). For spills and contamination of hands, shoes, etc., special contamination instruments (counters) are used which are more sraisitive than the monitoring dose instrumrats. 

Recent Uses of Solid-Surface Luminescence Analysis in Environmental Analysis. Vo-Dinh and coworkers have shown very effectively how solid-surface luminescence techniques can be used for environmentally important samples (17-22). RTF has been used for the screening of ambient air particulate samples (17,18). In addition, RTF has been employed in conjunction with a ranking index to characterize polynuclear aromatic pollutants in environmental samples (19). A unique application of RTF reported recently is a personal dosimeter badge based on molecular diffusion and direct detection by RTF of polynuclear aromatic pollutants (20). The dosimeter is a pen-size device that does not require sample extraction prior to analysis. 

Ionization Dosimeters Both of the two previous types of dosimeters require processing in orderto be read. The two most common types of ionization dosimeters can be read immediately, although the indirect type requires an auxiliary reading device to do so. Ionization dosimeters to be used as personnel dosimeters are typically about the size of a pen and are usually called pocket dosimeters. 

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