JP6350945B2 - Radioactivity measurement container installation jig, radiation detector efficiency calibration method, and radioactivity measurement apparatus - Google Patents

Description

  The present invention relates to a radioactivity measurement container installation jig, a radiation detector efficiency calibration method, and a radioactivity measurement apparatus.

  2. Description of the Related Art Conventionally, for example, a sample holder for fixing a measurement container in which various radioactivity measurement samples are housed on an end cap of a radiation detector is known (see, for example, Non-Patent Document 1).

"Radioactivity measurement method series 7 Gamma-ray spectrometry using germanium semiconductor detector", Ministry of Education, Culture, Sports, Science and Technology, 1992, p.110-111

  By the way, when fixing the measurement container on the end cap of the radiation detector using the sample holder according to the above prior art, if a part of the sample holder is interposed between the sample and the detector sensitive part, The problem arises that the radiation from is absorbed. To fix such a problem, when the measurement container is fixed on the end cap of the radiation detector using the sample holder, there is a radiation absorber by the sample holder between the sample and the sensitive part of the detector. It is desirable to prevent this.

  The present invention has been made in view of the above circumstances, and a radioactivity measurement container capable of appropriately positioning and fixing a measurement container with respect to an end cap of a radiation detector while suppressing absorption of radiation from a sample. An object of the present invention is to provide an installation jig, an efficiency calibration method for a radiation detector, and a radioactivity measurement apparatus.

In order to solve the above problems and achieve the object, the present invention employs the following aspects.
(1) A radioactivity measurement container installation jig according to an aspect of the present invention is an radioactivity measurement container installation in which a measurement container containing a radioactivity measurement sample is positioned and fixed with respect to an end cap of a radiation detector. A jig, which is positioned by a first portion for positioning the outer peripheral surface of the distal end portion of the measurement container, a second portion for positioning the distal end surface of the distal end portion of the measurement container, and the outer peripheral surface of the end cap A third portion to be provided.

(2) In the radioactivity measurement container installation jig according to (1), the second part includes an opening that exposes a part of the distal end surface of the measurement container.

(3) The radioactivity measurement container installation jig according to the above (1) or (2) includes a pressing member that pushes the measurement container toward the tip of the end cap through the second part.

(4) In the radioactivity measurement container installation jig according to the above (1) or (2), elasticity that generates a pressing force that pushes the measurement container toward the tip of the end cap through the second part. An attachment portion to which the member is attached is provided.

(5) In the radioactivity measurement container installation jig according to any one of (1) to (4), the first part, the second part, and the third part are connected to the end cap. The measuring container and the end cap can be detached while maintaining the positioning of the measuring container.

(6) A method for calibrating the efficiency of a radiation detector according to an aspect of the present invention uses the radioactivity measurement container installation jig described in any one of (1) to (5) above, and the standard line The measurement container containing the source is positioned and fixed with respect to the end cap of the radiation detector, and the efficiency of the radiation detector is calibrated using the standard radiation source.

(7) In the radiation detector efficiency calibration method according to (6) above, the shape of the standard radiation source is the same as the shape of the radioactivity measurement sample.

(8) A radioactivity measurement apparatus according to an aspect of the present invention includes a radiation detector that performs efficiency calibration by the efficiency calibration method for a radiation detector according to (6) or (7) above, and the radiation detector Is accommodated in the measuring container positioned and fixed with respect to the end cap of the radiation detector by the radioactive measuring container installing jig described in any one of (1) to (5) above. Radiation emitted from the radioactivity measurement sample is detected.

  According to the radioactivity measurement container installation jig according to the aspect described in (1) above, the radiation is measured between the radioactivity measurement sample or the standard radiation source accommodated in the measurement container and the end cap. It can prevent that the site | part used as an absorber is provided. Thereby, it is possible to position and fix the measurement container with respect to the end cap while suppressing the radiation from the radioactivity measurement sample or the standard radiation source from being absorbed.

  According to the radioactivity measurement container installation jig according to the aspect described in (2) above, after the measurement container is positioned and fixed with respect to the end cap, the end cap is pressed while pressing the tip of the measurement container from the opening. The positioning of the measurement container relative to can be maintained. Thereby, the radioactivity measurement container installation jig can be removed from the measurement container while maintaining the positioning of the measurement container with respect to the end cap. Remove the radiation measurement container installation jig to prevent radiation from being scattered by the radioactivity measurement container installation jig when measuring radiation from a sample for radioactivity measurement or a standard radiation source with a radiation detector. Can do.

  According to the radioactivity measurement container installation jig according to the aspect described in the above (3) or (4), for example, when the measurement container is packaged for contamination prevention, It can prevent separating from the front-end | tip of an end cap.

  According to the radioactivity measurement container installation jig according to the aspect described in (5) above, it is possible to prevent radiation from being scattered by the radioactivity measurement container installation jig while maintaining the positioning of the measurement container relative to the end cap. Can do.

  According to the efficiency calibration method of the radiation detector according to the aspect described in the above (6) or (7), the efficiency calibration can be performed under the same conditions as the measurement of the radioactivity measurement sample.

  According to the radioactivity measuring apparatus according to the aspect described in (8) above, the radioactivity measurement accuracy of the radioactivity measurement sample can be improved.

Sectional drawing of the container installation jig for radioactivity measurement which concerns on embodiment of this invention. Sectional drawing of the container installation jig for radioactivity measurement which concerns on embodiment of this invention. The perspective view of the container installation jig for a radioactivity measurement which concerns on embodiment of this invention. The figure which shows the process of removing the container installation jig for a radioactivity measurement which concerns on embodiment of this invention. Sectional drawing of the container installation jig for a radioactivity measurement which concerns on the 1st modification of embodiment of this invention. Sectional drawing of the container installation jig for a radioactivity measurement which concerns on the 2nd modification of embodiment of this invention.

  Hereinafter, a radioactivity measurement container installation jig, a radiation detector efficiency calibration method, and a radioactivity measurement apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings.

The radioactivity measurement container installation jig 10 according to the embodiment includes a jig main body 11 and a weight member 12 as shown in FIGS. 1 to 3. The radioactivity measurement container installation jig 10 positions and fixes the measurement container 13 containing the radioactivity measurement sample or the standard radiation source with respect to the end cap housing 15 of the radiation detector 14.
The radiation detector 14 detects radiation emitted from the radioactivity measurement sample or the standard radiation source of the measurement container 13 after the measurement container 13 is positioned with respect to the end cap housing 15.

The measurement container 13 includes a bottomed cylindrical container body 31 and a lid body 32 that covers the open end of the container body 31. The container main body 31 accommodates a radioactivity measurement sample or a standard radiation source therein. The lid 32 is, for example, a screw cap or a twist cap. The lid body 32 is attached to the container main body 31 by being wound around a screw thread provided on the outer peripheral surface on the distal end side of the container main body 31.
The measurement container 13 is packaged by, for example, a bag 33 for preventing contamination.

The radiation detector 14 is a semiconductor detector such as a germanium semiconductor detector or a silicon semiconductor detector. The radiation detector 14 is a vertical cryostat (not shown) in a vacuum region inside the end cap housing 15 having a radiation entrance window (not shown). The semiconductor crystal (not shown) is held. The inside of the cryostat is cooled by thermal contact with a cooling rod (not shown) made of copper immersed in liquid nitrogen stored in a dewar (not shown). A crystal electrode (not shown) formed on the semiconductor crystal is connected to a charge preamplifier (not shown) housed in the end cap housing 15. The charge preamplifier outputs an output signal pulse having a peak value corresponding to the energy of radiation incident on the semiconductor crystal from an output terminal (not shown) exposed to the outside.
The radiation detector 14 includes a bottomed cylindrical protective cover 41 that accommodates the distal end portion of the end cap housing 15. The protective cover 41 includes an inner surface 41A that contacts the distal end surface 15A and the outer peripheral surface 15B of the end cap housing 15.

The radioactive measuring container installation jig 10 positions and fixes the measuring container 13 with respect to the end cap housing 15 so as to press the bottom surface 13A of the measuring container 13 against the distal end surface 41B of the protective cover 41.
The jig body 11 is formed in a bottomed cylindrical shape. The jig body 11 includes a cylindrical first part 21, a disk-like second part 22, an opening 23 provided in the second part 22, and a cylindrical third part larger than the first part 21. 24.

The first portion 21 includes an inner peripheral surface 21A that is slightly larger than the outer peripheral surface 32A of the lid 32 that forms the tip of the measurement container 13. The first portion 21 positions the outer peripheral surface 32 </ b> A by holding the outer peripheral surface 32 </ b> A of the lid body 32 via the bag 33.
The second portion 22 has a surface 22A that is slightly larger than the tip surface 32B of the lid 32 that forms the tip of the measurement container 13. The second portion 22 positions the distal end surface 32 </ b> B by pushing the distal end surface 32 </ b> B of the lid body 32 toward the distal end surface 15 </ b> A of the end cap housing 15 through the bag 33. The second portion 22 includes an opening 23 that exposes a part of the front end surface 32 </ b> B of the lid body 32. The opening 23 includes an inner peripheral surface 23A having an inner diameter smaller than the outer diameter of the distal end surface 32B. The opening 23 accommodates a knot of the bag 33, for example.
The third portion 24 is provided coaxially with the first portion 21, and includes an inner peripheral surface 24 </ b> A that is slightly larger than the outer peripheral surface 41 </ b> C of the protective cover 41. The third portion 24 is positioned by the outer peripheral surface 15B of the end cap housing 15 via the protective cover 41 by holding the outer peripheral surface 41C of the protective cover 41.

  The outer shape of the weight member 12 is formed in a disc shape. The weight member 12 is placed on the distal end surface 11 </ b> A of the jig main body 11, thereby pushing the measurement container 13 toward the distal end surface 15 </ b> A of the end cap housing 15 through the second portion 22. The weight member 12 includes an opening 12 a that faces and is connected to the opening 23 of the second portion 22.

  Hereinafter, a method of positioning the measurement container 13 with respect to the end cap housing 15 using the radioactivity measurement container installation jig 10 of the embodiment will be described.

First, as shown in FIG. 3, the measurement container 13 packaged in the bag 33 is placed on the front end surface 41 </ b> B of the protective cover 41 of the end cap housing 15. Then, the jig body 11 of the radioactivity measurement container installation jig 10 is attached to the protective cover 41 from the distal end side of the measurement container 13. At this time, as shown in FIG. 2, the outer peripheral surface 32 </ b> A of the lid body 32 is held by the first portion 21 of the jig body 11. Further, the front end surface 32B of the lid body 32 is pushed toward the front end surface 15A of the end cap housing 15 by the second portion 22. Further, the outer peripheral surface 41 </ b> C of the protective cover 41 is held by the third portion 24. Further, a knot or the like of the bag 33 is disposed in the opening 23.
Next, the weight member 12 may be placed on the distal end surface 11A of the jig body 11 as necessary. For example, the weight member 12 is used when the measurement container 13 is packaged by the bag 33 and the measurement container 13 is lifted from the front end surface 41B of the protective cover 41 due to the deflection of the bag 33 or the like. At this time, a knot or the like of the bag 33 is disposed in the opening 12a. Therefore, for example, when the measurement container 13 is not packaged by the bag 33, the weight member 12 need not be used.

Further, prior to detecting the radiation emitted from the sample for measuring radioactivity in the measurement container 13 or the standard radiation source by the radiation detector 14, the radioactivity measurement container installation jig 10 is measured as necessary. Remove from container 13.
In this case, first, if the weight member 12 is placed on the front end surface 11 </ b> A of the jig main body 11, the weight member 12 is removed from the front end surface 11 </ b> A of the jig main body 11.
Next, as shown in FIG. 4, the jig main body 11 is moved outward from the distal end side of the measurement container 13 while pressing the lid 32 from the opening 23 with an operator's fingers. Corresponding to this operation, for example, in the axial direction of the jig body 11, the length at which the third portion 24 and the protective cover 41 overlap compared to the length L1 at which the first portion 21 and the measurement container 13 overlap. L2 may be formed longer. In this case, first, the holding of the lid 32 by the first part 21 is canceled, and then the holding of the protective cover 41 by the third part 24 is canceled.

Hereinafter, the radioactivity measurement apparatus 50 that measures the radioactivity of the radioactivity measurement sample using the radioactivity measurement container installation jig 10 of the embodiment will be described.
As shown in FIG. 1, the radioactivity measurement apparatus 50 according to the embodiment includes a measurement container 13 positioned by a radioactivity measurement container installation jig 10 and a radiation detector 14.
The radioactivity measurement apparatus 50 performs efficiency calibration of the radiation detector 14 using a standard radiation source accommodated in the measurement container 13. The shape of the standard radiation source is, for example, the same as the shape of the radioactivity measurement sample. The radiation detector 14 detects radiation from a standard radiation source accommodated in a measurement container 13 that is positioned and fixed with respect to the end cap housing 15 by the radioactivity measurement container installation jig 10. The radioactivity measurement apparatus 50 is accommodated in the measurement container 13 that is positioned and fixed with respect to the end cap housing 15 by the radioactivity measurement container installation jig 10, as in the case of performing efficiency calibration using a standard radiation source. The radiation from the radioactivity measurement sample is detected by the radiation detector 14. The radioactivity measurement apparatus 50 measures the radioactivity of the radioactivity measurement sample by measuring the radiation from the radioactivity measurement sample by the radiation detector 14 whose efficiency is calibrated by a standard radiation source.

As described above, according to the radioactivity measurement container installation jig 10 according to the present embodiment, the radioactivity measurement sample or the standard radiation source accommodated in the measurement container 13, the distal end surface 15 A of the end cap housing 15, and It can prevent that the site | part used as a radiation absorber is provided in between. Thereby, the measurement container 13 can be positioned and fixed to the end cap housing 15 while suppressing the radiation from the radioactivity measurement sample or the standard radiation source from being absorbed.
Further, after positioning and fixing the measurement container 13 with respect to the end cap housing 15, the measurement container 13 is positioned with respect to the end cap housing 15 while pressing the tip of the measurement container 13 from the opening 23 of the jig body 11. Can be maintained. Thereby, the jig body 11 can be detached from the measurement container 13 while maintaining the positioning of the measurement container 13 with respect to the end cap housing 15. Scattering of radiation by the radioactivity measurement container installation jig 10 when the radiation detector 14 measures the radiation from the radioactivity measurement sample or the standard radiation source by removing the radioactivity measurement container installation jig 10. Can be prevented.
Furthermore, when the measurement container 13 is packaged to prevent contamination, the measurement container 13 can be prevented from being separated from the distal end surface 15A of the end cap housing 15 due to floating or the like.

Further, according to the efficiency calibration method for the radiation detector 14 according to the present embodiment, the efficiency calibration can be performed under the same conditions as those for measuring the radioactivity measurement sample.
Moreover, according to the radioactivity measurement apparatus 50 according to the present embodiment, the radioactivity measurement accuracy of the radioactivity measurement sample can be improved.

Below, the 1st modification of embodiment mentioned above is demonstrated.
As shown in FIG. 5, the radioactivity measurement container installation jig 10 of the first modification includes an attachment portion 25 at the tip of the jig body 11 instead of the weight member 12 of the above-described embodiment. Yes.
The outer shape of the attachment portion 25 is formed in a bowl shape, for example. The attachment portion 25 supports the first end portion 50 a of the elastic member 50 that generates a pressing force that pushes the measurement container 13 toward the distal end surface 15 </ b> A of the end cap housing 15 via the second portion 22. The elastic member 50 is, for example, a spring. The second end 50b of the elastic member 50 is fixed to the lower surface 60A inside the box-type radiation shield 60 that shields the radiation detector 14 from background radiation. The radiation shield 60 includes a through hole 60a into which the end cap housing 15 is inserted in the lower portion in the vertical direction.

Below, the 2nd modification of embodiment mentioned above is demonstrated.
As shown in FIG. 6, the radioactivity measurement container installation jig 10 of the second modification includes an attachment member 27 having an attachment part 26 instead of the attachment part 25 of the first modification described above. Yes.
The outer shape of the mounting portion 26 is formed in a bowl shape, for example. The attachment portion 26 supports the first end portion 50 a of the elastic member 50 that generates a pressing force that pushes the measurement container 13 toward the distal end surface 15 </ b> A of the end cap housing 15 via the second portion 22.
The outer shape of the mounting member 27 is formed in an annular plate shape, for example. The mounting member 27 includes a surface 27A in contact with the distal end surface 11A and the outer peripheral surface 11B at the distal end portion of the jig body 11. The mounting member 27 holds the front end surface 11 </ b> A and the outer peripheral surface 11 </ b> B in a state where the mounting member 27 is mounted on the front end portion of the jig main body 11.

Below, the other modification of embodiment mentioned above is demonstrated.
In the embodiment described above, the first modified example, and the second modified example, the bag 33 may be omitted.
In the embodiment described above, the first modified example, and the second modified example, the weight member 12, the mounting portion 25, and the mounting member 27 may be omitted.

  The embodiments of the present invention are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10 ... Radioactivity measurement container installation jig, 11 ... Jig body, 12 ... Weight member, 13 ... Measurement container, 14 ... Radiation detector, 15 ... End cap housing, 21 ... First part, 22 ... Second Part, 23 ... opening, 24 ... third part, 25 ... attachment part, 26 ... attachment part, 27 ... attachment member, 31 ... container body, 32 ... lid, 33 ... bag, 41 ... protective cover, 50 ... elasticity Element

Claims (8)

A radioactivity measurement container installation jig for positioning and fixing a measurement container containing a radioactivity measurement sample or a standard radiation source with respect to an end cap of a radiation detector,
A first portion for positioning the outer peripheral surface of the distal end portion of the measurement container;
A second portion for positioning the distal end surface of the distal end portion of the measurement container;
A third portion positioned by the outer peripheral surface of the end cap;
Comprising
A container installation jig for measuring radioactivity. The second part is
An opening that exposes a portion of the tip surface of the measurement container;
The radioactivity measurement container installation jig according to claim 1. A pressing member that pushes the measurement container toward the tip of the end cap through the second portion;
The radioactivity measurement container installation jig according to claim 1, wherein the radioactivity measurement container installation jig is provided. An attachment portion to which an elastic member for generating a pressing force for pushing the measurement container toward the tip of the end cap is attached via the second portion;
The radioactivity measurement container installation jig according to claim 1, wherein the radioactivity measurement container installation jig is provided. The first part, the second part, and the third part are:
Detachable from the measurement container and the end cap while maintaining the positioning of the measurement container relative to the end cap;
The radioactivity measurement container installation jig according to any one of claims 1 to 4, wherein: Using the radioactivity measurement container installation jig according to any one of claims 1 to 5, the measurement container in which the standard radiation source is accommodated with respect to an end cap of the radiation detector. Positioning and fixing,
Performing an efficiency calibration of the radiation detector using the standard source;
An efficiency calibration method for a radiation detector. The shape of the standard radiation source is the same as the shape of the radioactivity measurement sample,
The method of calibrating the efficiency of the radiation detector according to claim 6. A radiation detector for which efficiency calibration is performed by the efficiency calibration method for a radiation detector according to claim 6 or 7,
The radiation detector is
The said radioactivity accommodated in the said measurement container positioned and fixed with respect to the end cap of the said radiation detector with the radioactivity measurement container installation jig as described in any one of Claims 1-5. Detect the radiation emitted from the measurement sample,
A radioactivity measuring apparatus characterized by that.

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