| 摘要 |
A thermoluminescent dosimeter for ionizing radiation comprises first and second parts of an active thermoluminescent substance arranged side-by-side on the surface of a support, said support being provided within a container transparent to said radiation and with a heater for raising the temperature of the first part at a rate different from that of the second part. This different rate of heating may be achieved in various ways:-Fig. 1 shows the support 1 as a tube containing a helically wound heater filament 3 with an axis coincident with that of the support, the pitches of those parts of the helix adjacent said first and second parts being different; alternatively as shown in Fig. 2, the pitch of the helix may be the same throughout the length of the support 1 being arranged to supply substantially identical quantities of heat to the two parts in identical periods of time but the wall thickness of the tube 1 is different at the two parts 7 and 8; in Figs. 3 and 4 on the other hand, the heat supplied is again the same but in the first the layers 7 and 8 have different thicknesses and in the second a sleeve of heat resistant insulation material 11 is provided between the support 1 and one of the layers. In a preferred embodiment, Fig. 5, the support 1 is constituted by two sections 13, 14, joined by spot weld 12. Section 13 has a linearly increasing thickness from the free end towards the junction with 14, and is coated with a layer 8 of thermoluminescent material which also increases in thickness as it approaches section 14. Section 14 is a tube of constant and thinner thickness than 13 and supports luminescent layer 7. The advantage of the above arrangement is that the thicker section of the section 13 allows for the heat conducted from section 14 and thus layer 8 exhibits an even temperature over its whole length, furthermore, a delay of luminescence between sections 7 and 8 may be obtained. The luminescence may be recorded photographically or with an oscilloscope to determine the radiation dose received by the dosimeter. The two different sections of the dosimeter may be used to record different doses, e.g. current and cumulative radiation dose. The container of the dosimeter may be evacuated, or a very low gas pressure may prevail therein. |
