JPH0341401Y2 - - Google Patents

Description

[Detailed description of the invention] A proportional counter is usually a cylindrical container with an anode core wire stretched over the axis, and an entrance window for radiation is provided at the center or end of the container, and an ionized gas is provided inside the container. distributed or enclosed. Among these, an end window type proportional counter having a window formed at the end of the container has high sensitivity, but has the disadvantage of low energy resolution. The present invention aims to eliminate this drawback and further improve the counting efficiency for low-energy radiation. In other words, in a conventional end window type proportional counter tube, an anode core wire is arranged on the axis of a cylindrical airtight container in which ionized gas is sealed or circulated, and both ends of the anode core wire are stretched over struts penetrating the container wall. The structure was such that a radiation entrance window was formed in the portion where the radiation passes through the end face of the container, and radiation was incident in the direction of the axis. In such a counter, radiation passes through the area where the electric field is disturbed between the window and the pillar, but in this area, ion recombination is likely to occur in the generated primary and secondary electrons, and the gas amplification is also lower than the core line. The value is lower than that near the center. Therefore, the third
As shown in the figure, an incomplete peak B appears in addition to the photoelectron peak A in the relationship curve between the wave height and the intensity of the output pulse, which has the disadvantage that the usable range is narrowed. Moreover, since the counting efficiency decreases due to the radiation absorption in the incomplete region mentioned above, the fourth
As shown by the broken line C, the counting efficiency decreases particularly for low-energy radiation.

The end window type proportional counter tube of the present invention is similar to conventional counter tubes in that a core wire is stretched along the axis of a cylindrical airtight container, but radiation is emitted at a position offset from the axis on the end surface of the container. An entrance window is formed. In such a counter, radiation can be made to enter parallel to the core line through the window, but by making the window inclined with respect to the axis and making the radiation enter obliquely so as to intersect with the core line,
The window can be made relatively large and the attenuation caused by the window material can be reduced, thereby improving counting efficiency. However, in any case, since the radiation does not pass through the part of the pillar where the core wire is stretched, the electron flow that is absorbed by the pillar with a small gas amplification degree is removed, which improves the counting efficiency and limits the range of use. Such defects are also eliminated. That is, as shown in FIG. 3, the incomplete peak B is removed and the usable range is expanded. In addition, low-energy radiation is absorbed by the gas near the window, and the ionization electrode is absorbed by the thick pillar without being sufficiently multiplied. For this reason, it was not possible to obtain sufficient counting efficiency as shown by the broken line c in FIG. High counting efficiency can be obtained for Therefore, by using the counter of the present invention in, for example, fluorescence X-ray analysis, it is possible to improve the energy resolution and detect long wavelength characteristic X-rays with high sensitivity.

Fig. 1 is a longitudinal sectional view of an embodiment of the present invention, and Fig. 2 is a front view thereof. Supports 3, 3 made of strong metal wire are passed through. The anode core wire 4 stretched between the tips of the supports 3, 3 is arranged on the axis of the cylindrical container 1, and one end wall surface 5 of the container 1 is located at a position offset from the axis.
is inclined with respect to the axis, and a radiation entrance window 6 is formed in this wall surface 5. Note that the container 1 may be sealed and filled with an appropriate ionized gas.
Further, for example, an inlet/outlet for ionized gas may be formed at both ends to allow the gas to flow during use. Further, the radiation to be detected can be made to enter through the window 6 parallel to the core wire 4, but it can also be made to enter obliquely as shown by the dotted line with an arrow in the figure. As described above, in the end window type proportional counter tube of the present invention, since the window is formed at a position offset from the axis, the incident radiation reaches the core wire portion without passing near the pillar 3. Therefore, the above-mentioned effects can be obtained.
Note that by tilting the end face of the container as in the above embodiment and allowing the radiation to enter obliquely,
The window can be made relatively large and the attenuation caused by the window material can be reduced.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view of an embodiment of the present invention, Fig. 2 is a front view of the proportional counter shown in Fig. 1, and Figs. 3 and 4 are characteristic curves of the inventive and conventional end window type proportional counters. It is. In the figure, 1 is a container, 2 is a mantle, 3 is a support, 4 is a core wire, 5 is an end wall surface, and 6 is a radiation entrance window.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) An anode core wire is stretched along the axis of a cylindrical airtight container filled with ionized gas, and a radiation entrance window is provided at a position offset from the axis at the end of the airtight container. (2) A proportional counter according to claim (1) of the utility model registration claim, in which the radiation entrance window is formed to be inclined with respect to the axis.