ALPHA RADIATION DETECTOR HAVING AN OPTICAL SENSOR FOR MEASURING THE RADON CONCENTRATION IN THE AMBIENT AIR

Abstract

The invention relates to an alpha radiation detector (1) for measuring the radon concentration in the ambient air, comprising a housing (10) having a base (5) on which a hood (2) is arranged, which hood has a chamber (9) which is located therein, wherein the opaque housing (10) is designed in such a way that ambient air can penetrate into the chamber (9) from the outside, the alpha radiation detector further comprising an optical sensor (4). According to the invention, the hood (2) has an inner wall which is provided at least in part with a scintillation material (3) which generates light pulses (8) upon impingement of alpha particles (7), which light pulses are sensed by the optical sensor (4).

Claims

1-15. (canceled)

16. An alpha radiation detector for measuring radon concentration in ambient air, the alpha radiation detector comprising: a housing having a base on which there is arranged a hood having a chamber which is located therein, the housing being configured in such a way that ambient air can penetrate into the chamber from outside, and an optical sensor; the hood having an inner wall, which is provided with a scintillation material which generates light pulses upon impingement of alpha particles, which light pulses are sensed by the optical sensor, wherein the hood has an annular portion which is made of a material that is impermeable to light but permeable to gas, so that radon gas can penetrate into the chamber from outside.

17. The alpha radiation detector according to claim 16, wherein the hood is made as a single piece and has a first portion that is impermeable to light as well as a second portion that is impermeable to light, but permeable to gas.

18. The alpha radiation detector according to claim 16, wherein the gas-permeable material comprises felt, silicone, cloth, plastic, foam, a ceramic material, or a membrane.

19. The alpha radiation detector according to claim 16, wherein the scintillation material comprises doped zinc sulfide, bismuth germanate, lead tungstate, lutetium oxyorthosilicate, sodium iodide, zinc sulfide, or cesium iodide.

20. The alpha radiation detector according to claim 16, wherein the optical sensor is arranged within the chamber, on the base.

21. The alpha radiation detector according to claim 16, wherein the optical sensor is a silicon photomultiplier.

22. The alpha radiation detector according to claim 16, wherein the sensor is arranged in the chamber.

23. The alpha radiation detector according to claim 16, wherein the base is plate-shaped.

24. The alpha radiation detector according to claim 16, wherein the base is made of a printed circuit board material and is equipped with an evaluation electronics.

25. The alpha radiation detector according to claim 16, wherein a first and a second mounting element are provided, which are configured such that the first and second mounting elements press the hood against the base when the first and second mounting elements are joined together.

26. The alpha radiation detector according to claim 25, wherein the first mounting element has an opening which is dimensioned such that only a part of the hood fits through, the second mounting element is plate-shaped, and both mounting elements comprise corresponding elements of a detent connection, by means of which they are connected.

27. An alpha radiation detector for measuring radon concentration in ambient air, the alpha radiation detector comprising: a housing having a base on which there is arranged a hood having a chamber which is located therein, the housing being configured in such a way that ambient air can penetrate into the chamber from outside, and an optical sensor; wherein: the base is made of a printed circuit board material and is equipped with an evaluation electronics; the optical sensor is arranged within the chamber, on the base; the optical sensor is a silicon photomultiplier; and the base has at least one aperture, which is closed by a material that is impermeable to light but permeable to gas, so that radon gas can pass into the chamber from outside, through the aperture.

28. The alpha radiation detector according to claim 27, wherein the gas-permeable material is arranged on an underside of the base, and a first mounting element and a second mounting element are provided, which are configured such that the gas-permeable material is pressed against the underside of the base when the first and second mounting elements are joined together.

29. The alpha radiation detector according to claim 28, wherein the hood is formed as the first mounting element, the second mounting element is plate-shaped, and both mounting elements comprise corresponding elements of a detent connection, by means of which they are connected to one another.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The invention will be explained by way of example in greater detail hereinafter with reference to the appended drawing, in which:

[0029] FIG. 1 shows an exploded view of an alpha radiation detector according to a first embodiment;

[0030] FIG. 2 shows a side view of the alpha radiation detector of FIG. 1;

[0031] FIG. 3 shows an exploded view of an alpha radiation detector according to a second embodiment; and

[0032] FIG. 4 shows a side view of the alpha radiation detector from FIG. 3.

[0033] FIGS. 1 and 2 show a first embodiment of an alpha radiation or radon detector 1 with a base 5, on which there is arranged a hemispherical hood 2. A chamber 9 is located within the hood 2 and represents a measuring cell in which the radon concentration is measured. An optical sensor 4, such as a SiPM, is arranged on the base 5 and detected the light pulses generated during alpha decay.

[0034] The base 5 together with the hood 2 located thereon form a housing 10 which completely surrounds the chamber 9, so that no light can penetrate into the chamber 9 from outside. In the embodiment shown in FIGS. 1 and 2, the hood 2 is formed in a number of parts and comprises a first portion 14, which is impermeable to light and is provided on its inner wall with a scintillation material 3, which, upon impingement of alpha particles, generates light pulses which are sensed by the optical sensor 4. The hood 2 further comprises a second, annular portion 15, which is produced from a material 6 that is impermeable to light, but permeable to air or gas, such as a (open-pore) foam. The two portions 14, 15, when assembled together, lie one above the other and are pressed together with the base 5 by first and second mounting elements 11, 12.

[0035] The first portion 14 of the hood 2 can be produced for example from metal, ceramic or a plastic.

[0036] The first portion 14 of the hood 2, in the embodiment shown here, has an edge 19 which protrudes outwardly beyond the contour of the portion 14 and which is engaged by the first mounting element 11. The second mounting element 12 is arranged on the other side of the base 5 and forms a bottom of the arrangement. Both mounting elements 11, 12 comprise corresponding elements of a detent connection 17, which make it possible to assembly the radon detector 1 quickly and easily and, as the mounting elements 11, 12 are joined together, to press the first portion 14 of the hood 2 simultaneously against the annular or peripheral portion 15 and the base 5. A plurality of protrusions 18 are also provided on the second mounting element 12 and press against the base 5 from below.

[0037] The gas-permeable material 6 can comprise, for example, felt, silicone, foam, a plastic, or a membrane. The wall thickness and the structure/the tightness of the material 6 is selected in such a way that it is impermeable to light present at the site of use, however, a sufficient exchange of ambient air into and out from the chamber 9 may occur.

[0038] As mentioned at the outset, radon decays under radiation of alpha particles into further decay products. The decay products, such as polonium, also then decay again with alpha radiation. An alpha particle 7 is shown by way of example in FIG. 2. The alpha particle 7 moves in the direction of the dashed arrow and impinges at a point P against the scintillation material 3 located on the inner wall of the hood 2. The scintillation material in turn emits an optical light pulse 8, which is then detected by the optical sensor 4. The scintillation material 3 is preferably a layer of zinc sulfide (ZnS:Cu, ZnS:AG). Alternatively, other materials known from the prior art could also be used.

[0039] The base 5 preferably comprises a printed circuit board, on or below which an evaluation electronics 21 can also be arranged. In the shown exemplary embodiment, the evaluation electronics 21 is located beneath the printed circuit board. As can be seen, the evaluation electronics 21 is not located directly beneath the sensor 4, but is arranged at the greatest possible distance from the sensor 4 in order to keep the influence of electromagnetic radiation on the sensor 4 low and to avoid interference.

[0040] The optical sensor 4 is preferably a silicon photomultiplier. In the shown exemplary embodiment the optical sensor 4 sits on the bottom of the chamber 9 on the base 5. The photomultiplier is preferably arranged on an axis of symmetry of the hood on the base 5.

[0041] An optical unit for bundling the light pulses 8 may be provided, but does not have to be.

[0042] FIGS. 3 and 4 show a second embodiment of an alpha radiation or radon detector 1 having a base 5 on which a hood 2 is arranged. A chamber 9 is in turn located within the hood 2 and represents a measuring cell, in which the radon concentration is measured.

[0043] The hood 2 is provided on its inner wall with a scintillation material 3, which, upon impingement of alpha particles, generates light pulses which are sensed by an optical sensor 4. In contrast to the first embodiment, the base 5 is formed in such a way that ambient air can pass from outside through the base 5 and into the chamber 9. The base 5 for this purpose has at least one aperture 16, which is closed by the material 6 that is impermeable to light but permeable to gas.

[0044] The gas-permeable material 6 is plate-shaped here and is located beneath the base 5. The hood 2 is located on the upper side of the base 5 and preferably consists of a material that is impermeable to light, such as plastic or metal.

[0045] In the radon detector 1 as per the second embodiment, the hood 2 and a second mounting element 12 are designed to press the gas-permeable material 6 against the base 5 when the hood 2 is connected to the second mounting element 12. The second mounting element 12 is located on the underside of the base 5 and forms a bottom of the arrangement. The above-mentioned gas-permeable material 16 is located between the second mounting element 12 and the base 5. Both parts 2, 12 are equipped with corresponding elements of a detent connection 17.

[0046] The hood 2 comprises an inwardly protruding stop 20, which engages a surface of the base 5. When the hood 2 and the second mounting element 12 are joined together, the base 5 and the gas-permeable material 6 are clamped between the two parts 2, 12.

[0047] The second mounting element 12 comprises at least one further opening 13, through which ambient air can penetrate into the radon detector 1 from outside. The ambient air then passes through the gas-permeable material 6 and the aperture 16 into the chamber 9.

[0048] The signals generated by the sensor 4 are processed by the evaluation electronics 21 and provides corresponding electrical analogue or digital signals, which can be tapped via an interface 22. The radon detector 1 can also comprise one or more interfaces 22 for peripheral devices, such as display units or computers.