JPS593714B2 - Thermal fluorescence dosimeter element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a thermal fluorescence dosimeter element, and provides a method for manufacturing a thermal fluorescence dosimeter element that is advantageous in improving measurement accuracy and increasing manufacturing yield.

Thermal fluorescence dosimeter elements used in thermal fluorescence dosimeters store part of the energy in the form of excited electrons when exposed to radiation (C By heating the element, the excited state electrons are released and emit light.

Radiation is measured by measuring this light with a photomultiplier tube, but from a practical standpoint, one of the most important aspects of performance is the reproducibility of the measurement. The advantage is that a constant amount of light emission can be measured at all times.

Conventionally, thermal fluorescence dosimeter elements have been made of crystalline materials (Ca
SO4, LiF, CaF2, etc.) or sintered body (BeO
0Mg2Si04) was crushed into a fine powder and then sealed in a glass ampoule or directly embedded in glass or heat-resistant resin.

However, if there is variation in the particle size of this powder, reproducibility deteriorates.

For example, in a device sealed in a glass tube, fine powder and large particles are mixed inside unevenly (if they are mixed, directional dependence will occur, causing variation).

In addition, when the crystals are crushed in production to prevent this, if the crushed powder has a large particle size and is adjusted to a constant particle size, there is a problem that the classification yield becomes poor.

The present invention provides a method for manufacturing a thermal fluorescence dosimeter element that can solve the above-mentioned problems in measurement accuracy and classification yield, and the present invention will be described in detail below.

FIG. 1 shows the shape of thermal phosphor particles produced by the production method of the present invention, with a diameter of about 0.2 mm and a length of about 0.2 mm.
It has a cylindrical shape of 3 mm.

The aggregate of such particles is a free-flowing powder that is easy to handle.

Here, the shape of each particle does not necessarily have to be a proper cylinder; for example, it may have missing corners or be rounded, or it may have a shape such as a prism instead of a cylinder. The effects described below remain the same.

Also, as long as the dimensions of the particles are uniform, the diameter is O,
1mm~11n71Ls Length 0.2 mrn-1m
It may be arbitrarily selected within the range of vt.

Next, a method for manufacturing the thermal fluorescence dosimeter element of the present invention will be described.

If the thermal phosphor is a ceramic body and is manufactured using a ceramic manufacturing method, the thermal phosphor raw material powder is mixed with the binder and lubricant necessary for press molding, and then formed into a thin wire using an extrusion jig. extrude

When this is cut into short pieces with a cutting machine and fired at high temperatures, it becomes ceramic and becomes columnar ceramic grains.Finally, it is passed through a sieve to classify it into a certain particle size range, and a thermal fluorescence dosimeter element with a uniform particle size is produced. get.

Furthermore, to make this into an element, it is sealed in an ampoule such as a glass tube, or embedded in a heat-resistant resin.

Examples will be described below. [Example 1] Ceramic grains having the shape of the present invention were produced using beryl oxide powder as a raw material.

Beryllium oxide is activated by alkali ions, but beryllium oxide powder 100f is used as a raw material for thermal phosphors? and sodium compound 1mol1% (relative to BeO), methyl cellulose as an additive necessary for pressing 21. Mix glycerin: lof and distilled water = 100cc in a beaker,
After drying to a state where it can be pressed, it is extruded into a thin wire shape of 0.5tttxφ using an extrusion jig.

Cut the wire into pieces of about 0.5 to 1 mm using this thin wire cutting machine.

The compressed and cut raw material is fired in an electric furnace at 1600° C. for 2 hours to form columnar thermal phosphor particles.

Furthermore, the sintered particles are passed through a sieve machine to obtain a 0.1 to 0
．． Beryllium oxide thermal phosphor particles were obtained by classification into a particle size range of 3 yarns.

Further, using this, devices as shown in FIGS. 2 and 3 were experimentally manufactured.

FIG. 2 shows an example of a thermal fluorescence dosimeter element made by sealing powder 1' produced by the production method of the present invention in a glass ampoule 2, which has an outer diameter of 1.2 mm and a length of 8 mm.

Figure 3 shows an example of a thermal fluorescence dosimeter element made by embedding powder 1' in heat-resistant resin 3, with a diameter of 8 mm and a thickness of 0.5 mm.
It's relevant.

The manufacturing method of the present invention has the above-mentioned configuration and can obtain uniform columnar particles. Therefore, radiation (X-rays, α-rays) can be emitted using a thermal fluorescence dosimeter element in which the columnar particles are assembled. When measuring, the repeated measurements using the same element in the ampoule element shown in FIG. 2 were approximately ±3%, which was a great improvement compared to the accuracy of the conventional element with non-uniform particle size, which was ±10%.

Since the particles are small particles that can be said to be granular, not only the oxygen that tends to be insufficient during firing is supplied to the molecules from the outside, but also the light is efficiently extracted to the outside when emitting light as a phosphor. Therefore, the radiation sensitivity is higher than an element composed of a large element body such as a pellet.

In addition, the classification yield of thermal phosphor particles according to the production method of the present invention is 70 to 75%, and compared to the classification yield of about 35 to 40% after crushing in the conventional production method, the production cost is reduced. In addition, the fact that there is almost no need for a grinding step that generates dust during the manufacturing process is also advantageous from the standpoint of work hygiene.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of phosphor particles manufactured by a manufacturing method according to an embodiment of the present invention, and FIG. 2 is a partially cutaway front view of a thermal fluorescent dosimeter element using the same thermal phosphor particles. FIG. 3 is a perspective view of another embodiment. 1...Particles, 2...Glass ampoules,
3...Heat-resistant resin.

Claims (1)

[Claims] 1 Add and mix a binder and a lubricant to the thermal phosphor raw material powder, extrude this mixture into a thin wire using an extrusion jig, cut the thin wire, and further bake at a high temperature to form a columnar thermal phosphor. 1. A method for manufacturing a thermal fluorescence dosimeter element, characterized by forming body particles.