| 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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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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| 3. |
- Fraz, Hamza, et al.
(författare)
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Prediction of Harmonic Distortion in ADCs using dynamic Integral Non-Linearity model
- 2009
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Ingår i: Behavioral Modeling and Simulation Workshop, 2009. BMAS 2009. IEEE. - 9781424453580 ; , s. 102-107
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Konferensbidrag (refereegranskat)abstract
- This paper investigates the application of dynamic, Integral Non-Linearity (INL) model of Analog-to-Digital Converters (ADC) to predict the harmonic distortion in pipelined ADCs. The device used to validate the model is Texas Instruments' ADS6129; a 12-bit, 250 MSPS1 pipelined ADC. The performance of the model is measured using single tones in the first Nyquist zone, with an amplitude ranging between −1 dBFS2 and −46 dBFS. Total Harmonic Distortion (THD) and Spurious Free Dynamic Range (SFDR) are used as metrics to compare the performance of the model to the actual ADC. The results indicate that a model for High Code Frequency (HCF) INL is essential for correct prediction of distortion for input signals with small amplitudes. The results also suggest that dynamic INL models offer an effective method to model the distortion in ADCs until Nyquist frequency only. Beyond Nyquist frequency, the non-linear effects of Track and Hold (T/H) start manifesting and the INL model can no longer account for all the distortion seen at the output of ADCs.
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