An ion detector ( 1 ) comprising a semi-conductor avalanche photodiode ( 4 ) and a scintillation layer ( 2 ), the scintillation layer having a thickness in the range 0.1 mm to 00 mm, the scintillation layer arranged to generate photons towards the photodiode resulting from ions impinging on the scintillation layer.
1. An ion detector, comprising:
a plurality of avalanche photodiodes configured in a spatial distribution to provide a pixelated array of photodiodes, each said avalanche photodiode in said pixelated array further comprising a semi-conductor avalanche photodiode, and the detector comprising a scintillation layer, the scintillation layer having a thickness in the range 0.1 μm to 100 μm, the scintillation layer arranged to generate photons towards the photodiode resulting from ions impinging on the scintillation layer, wherein said detector is capable of detecting ions of 10 keV.
2. A detector as claimed in claim 1 in which each said avalanche photodiode has sensitivity to detect a single photon.
3. A detector as claimed in claim 1 in which each said avalanche photodiode comprises a reversely biased photosensitive p-n junction.
4. A detector as claimed in claim 1 in which the semi-conductor avalanche photodiode is a silicon-based photodiode.
5. A detector as claimed in claim 1 in which the scintillation layer has been formed in situ on the semi-conductor avalanche photodiode by a deposition process.
6. A detector as claimed in claim 1 in which the scintillation layer is a pre-formed component attached to the semi-conductor avalanche photodiode.
7. A detector as claimed in claim 1 wherein said avalanche photodiode is capable of detecting ions having energies within a range of from 0-20 keV.
8. A detector as claimed in claim 1 consisting of an integrated device.
9. A detector as claimed in claim 1 further comprising an optical lens located between the scintillator layer and the semi-conductor avalanche photodiode.
10. A detector as claimed in claim 1 in which the thickness of the scintillator layer is less than a distance between photosensitive regions of neighbouring photodiodes of said spatially distributed array of avalanche photodiodes.
11. A detector as claimed in claim 10 in which the width of the photosensitive region is in the range 10 μm to 100 μm.
12. A detector as claimed in claim 1 in which a thickness of the scintillator layer is in the range of 0.1 to tens of μm's.
13. A method of ion detection comprising use of the detector of claim 1 .