SCINTILLATION DETECTOR

Abstract

A scintillator unit is described for use in a radiation detector assembly comprising: a scintillator comprising a scintillating material; a wrapping layer at least partly covering an external surface of the scintillating material; wherein the wrapping layer comprises a composite layer including a first layer of diffusively reflective material and a second layer of specularly reflective material. A radiation detector assembly including a scintillator unit is also described. Methods of fabrication of the same are also described.

Claims

1. A scintillator unit for use in a radiation detector assembly comprising: a scintillator comprising a scintillating material; a wrapping layer at least partly covering an external surface of the scintillating material; wherein the wrapping layer comprises a composite layer including a first layer of diffusively reflective material and a second layer of specularly reflective material.

2. A scintillator unit in accordance with claim 1 wherein the layer of diffusively reflective material comprises a diffusively reflective flexible film.

3. A scintillator unit in accordance with claim 2 wherein the layer of diffusively reflective material comprises a layer of flexible polymeric material sheet.

4. A scintillator unit in accordance with claim 3 wherein the layer of diffusively reflective material comprises a layer of PTFE sheet.

5. A scintillator unit in accordance with claim 1 wherein the layer of specularly reflective material comprises a specularly reflective flexible film.

6. A scintillator unit in accordance with claim 5 wherein the layer of specularly reflective material comprises a layer of metallic material and for example comprises a layer of reflective metal foil or a layer of metallised polymer sheet.

7. A scintillator unit in accordance with claim 1 wherein the layer of diffusively reflective material has a thickness of less than 2 mm and for example of between 0.1 mm and 1 mm.

8. A scintillator unit in accordance with claim 1 wherein the layer of specularly reflective material has a thickness of less than 200 microns and for example of between 10 μm and 100 μm.

9. A scintillator unit in accordance with claim 1 wherein the layer of diffusively reflective material is located closer to the scintillator than the layer of specularly reflective material.

10. A scintillator unit in accordance with claim 1 wherein the wrapping layer comprises the layer of diffusively reflective material directly overlaid by the layer of specularly reflective material.

11. A scintillator unit in accordance with claim 1 wherein the layer of specularly reflective material comprises the outermost layer of the wrapping layer.

12. A scintillator unit in accordance with claim 1 wherein the scintillating material is an inorganic crystalline scintillating material.

13. A scintillator unit in accordance with claim 12 wherein the inorganic scintillating material is selected from one or more of: doped alkali halides, such as NaI(TI), CsI(TI), CsI(Na), LiI(Eu); other slow inorganics such as BGO, CdWO.sub.4, ZnS(Ag); Ce.sup.3+-activated fast inorganics such as lanthanum chloride (LaCl.sub.3(Ce)), lanthanum bromide (LaBr.sub.3(Ce)), CLLB (Cs.sub.2LiLaBr.sub.6(Ce)), GSO (Gd.sub.2SiO.sub.5(Ce)), YAP, YAG, LSO, LuAP, and the like.

14. A radiation detector assembly comprising: a scintillator unit comprising: a scintillating material; a wrapping layer at least partly covering an external surface of the scintillating material, wherein the wrapping layer comprises a composite layer including a first layer of diffusively reflective material and a second layer of specularly reflective material; a photodetector optically coupled to the scintillator.

15. A radiation detector assembly in accordance with claim 14 wherein the assembly is adapted to be portable in that it comprises a housing adapted to associate components of the radiation detector together compactly in a portable manner, and for example adapted to be hand-held in use.

16. A method of fabrication of a scintillator unit comprising: providing a scintillator comprising a scintillating material; at least partly covering an external surface of the scintillating material with a wrapping layer; wherein the wrapping layer comprises a composite layer including a first layer of diffusively reflective material and a second layer of specularly reflective material.

17. The method of claim 16 further comprising optically coupling a photodetector with the scintillator.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0063] The invention will now be described by way of example only with reference to FIG. 1 of the accompanying drawings, which shows a scintillator assembly including a scintillator unit in accordance with an embodiment of the first aspect of the invention in exploded view.

DETAILED DESCRIPTION

[0064] FIG. 1 shows a scintillator assembly illustrative of various aspects of the invention in exploded view.

[0065] The assembly includes, from the top, a housing lid (1), a photodetector PCB and flex (3), an inorganic crystalline scintillator which in the embodiment is CLLB (5), a PTFE wrapping layer (7) and reflective foil wrapping layer sitting outside the PTFE layer in use (9), a PTFE base layer (11), a neoprene support layer (13), and a housing body (15).

[0066] When suitably assembled, the outer cylindrical surface of the scintillator is consequently covered first by the PTFE layer and then by the reflective foil layer. The combined effect of this composite covering is to produce in combination: the high diffusing behaviour of conventional expanded PTFE wrapping without the disadvantage of the conventionally required thickness; and the high reflectivity of the foil layer while mitigating the disadvantages usually associated with the specular nature of the reflectivity of such foils. In consequence, a layer thickness of around 200-300 μm is achievable, and the whole assembly is particularly adapted to compact construction which can readily be incorporated into portable and for example hand-held detectors.

[0067] Other combinations of a layer of flexible polymeric material and layer of reflective foil, and optional further layers, will readily suggest themselves. The layers are preferably juxtaposed such that the flexible polymeric material is disposed closer to an external surface of the inorganic crystalline scintillating material and the layer reflective foil is disposed more distantly from the inorganic crystalline scintillating material and for example constitutes an outer surface of the wrapping.

[0068] The composite film of the embodiment of the invention thus uses a thin layer specularly reflective foil and a thin layer of diffusing material to provide both high diffusing behaviour and high reflectivity in a wrapping that requires much less thickness.

[0069] For example, the composite wrapping film of the invention has a thickness of less than 2.1 mm and for example of between 110 microns and 1100 microns.

[0070] The active components of the assembly are shown in a suitable housing which provides an enclosure volume in which the components are mechanically and environmentally protected. The enclosure volume comprises a housing body and a housing lid. The housing body defines an enclosure volume into which the components are received, and on to which the lid is then sealed. The housing may provide a hermetically enclosure to protect delicate and for example hygroscopic scintillator crystals from the external environment.

[0071] The illustrated housing may then be incorporated into a suitable portable and for example hand-held detector with other associated processing and control electronics, power source and the like.