| 1. |
- Uher, J., et al.
(författare)
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Characterization of 3D thermal neutron semiconductor detectors
- 2007
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 576:1, s. 32-37
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Tidskriftsartikel (refereegranskat)abstract
- Neutron semiconductor detectors for neutron counting and neutron radiography have an increasing importance. Simple silicon neutron detectors are combination of a planar diode with a layer of an appropriate neutron converter such as (LiF)-Li-6. These devices have limited detection efficiency of not more than 5%. The detection efficiency can be increased by creating a 3D microstructure of dips, trenches or pores in the detector and filling it with a neutron converter. The first results related to the development of such devices are presented. Silicon detectors were fabricated with pyramidal dips on the surface covered with (LiF)-Li-6 and then irradiated by thermal neutrons. Pulse height spectra of the energy deposited in the sensitive volume were compared with simulations. The detection efficiency of these devices was about 6.3%. Samples with different column sizes were fabricated to study the electrical properties of 3D structures. Charge collection efficiencies in silicon columns from 10 to 800 mu m wide and 80-200 mu m high were measured with alpha particles.The neutron detection efficiency of a full 3D structure was simulated. The results indicate an increase in detection efficiency by a factor of 6 in comparison with a standard planar neutron detector.
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| 2. |
- Uher, J, et al.
(författare)
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Directional Radiation Detector
- 2007
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Ingår i: IEEE Nuclear Science Symposium Conference Record. - : IEEE conference proceedings. ; , s. 1162-1165
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Konferensbidrag (refereegranskat)abstract
- Many applications likehomeland security, radiation protection, control of fissile material proliferation and other require not only detection of radioactive materials, but also their localization. We are presenting a directional detector based on an array of semiconductor detectors capable to determine direction where the radioactive source is placed. Semiconductor single pad detectors are arranged into rows and separated by a shielding material. Selection of the detectors and shielding material depends on the type and energy of the radiation desired to monitor (i.e. X-rays, gammas or neutrons). Level of the signal, i.e. count rate, in each detector depends on the angle of the incoming radiation. Analysis of the count rate in each detector allows calculating angular position of the source. A series of simulations and evaluating measurements of the directional radiation detection principle is presented.
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| 3. |
- Uher, J, et al.
(författare)
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Highly sensitive silicon detectors of thermal neutrons
- 2007
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Ingår i: Nuclear Science Symposium Conference Record, 2006. IEEE. Vol 3.. - : IEEE conference proceedings. - 1424405602 - 9781424405619 ; , s. 1346-1348
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Konferensbidrag (refereegranskat)abstract
- Planar semiconductor diodes supplemented with a layer of an appropriate neutron converter such as 6LiF can be used for thermal neutron counting or imaging. Neutrons interacting in the converter generate alphas and tritons which enter the semiconductor and are detected there. However, simple planar devices suffer from limited detection efficiency which cannot reach more than about 5%. The limit in detection efficiency can be overcome by etching a 3D microstructure of trenches, pores or columns in the detector and filling it with the neutron converter. The overall neutron detection efficiency of such structure with pores was simulated. The results indicate an increase in the detection efficiency by factor of 6 in comparison with a standard planar neutron detector. Samples with different silicon column sizes were fabricated to study the electrical properties of 3D structures. The charge collection efficiency in silicon columns from 10 μm to 800 μm wide and 80 μm high was measured. Single pad detectors with pores were also fabricated and tested for thermal neutron detection. The samples have square pores of 20 μm wide, ~60 μm deep. The pore pitch is 70 μm. 6LiF was used as the neutron converter in all cases. Pulse height spectra of the filled samples irradiated by thermal neutrons were measured. The measurement proved functionality of such detectors and its usability for thermal neutron detection.
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| 4. |
- Uher, J, et al.
(författare)
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Silicon detectors for neutron imaging
- 2007
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Ingår i: NUCLEAR PHYSICS METHODS AND ACCELERATORS IN BIOLOGY AND MEDICINE: Fourth International Summer School on Nuclear Physics Methods and Accelerators in Biology and Medicine.. - : American Institute of Physics (AIP). - 9780735404724 ; , s. 101-104
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Konferensbidrag (refereegranskat)abstract
- Semiconductor silicon detectors are used in many applications for detection and imaging of ionizing radiation. Detection of neutrons is also possible with these devices. However, the silicon detectors must be adapted for the thermal neutron detection and imaging. The devices must be supplemented with a material which ``converts'' neutrons into a radiation detectable directly in the semiconductor detector. The principle of the thermal neutron detection with semiconductor silicon detectors is explained. Advantages of such detectors are shown as well as their limitations. The way of the detector improvement using 3D detector technologies is described. The 3D detector properties were simulated; real 3D structures were fabricated and successfully tested with a beam of thermal neutrons, finally. The functionality of these devices was proved.
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