A Compton camera prototype has been developed using a pixelated CZT detector with 4-by-4 pixels.Signals of the detector are read out by a VASTAT ASIC that is controlled by a self-developed DAQ board. The DAQ software ...A Compton camera prototype has been developed using a pixelated CZT detector with 4-by-4 pixels.Signals of the detector are read out by a VASTAT ASIC that is controlled by a self-developed DAQ board. The DAQ software is developed using LabVIEW, and the offline Compton imaging codes are written in C++. The prototype has been successfully calibrated, and its capabilities for source detection, spectroscopy, and Compton imaging have been demonstrated using a Cs-137 source.The angular resolution of the 662 keV line is 36° FWHM for the simple back-projection method and 9.6° FWHM for the MLEM reconstruction method. The system is ready to be extended to 11-by-11 pixels in the future, and a better imaging quality can be expected due to the better relative position resolution.展开更多
An on-chip reference voltage has been designed in capacitor-resister hybrid SAR ADC for CZT detec- tor with the TSMC 0.35 μm 2P4M CMOS process. The voltage reference has a dynamic load since using variable capacitors...An on-chip reference voltage has been designed in capacitor-resister hybrid SAR ADC for CZT detec- tor with the TSMC 0.35 μm 2P4M CMOS process. The voltage reference has a dynamic load since using variable capacitors and resistances, which need a large driving ability to deal with the current related to the time and sampling rate. Most of the previous articles about the reference for ADC present only the bandgap part for a low temperature coefficient and high PSRR. However, it is not enough and overall, it needs to consider the output driving ability. The proposed voltage reference is realized by the band-gap reference, voltage generator and output buffer. Apart from a low temperature coefficient and high PSRR, it has the features of a large driving ability and low power con- sumption. What is more, for CZT detectors application in space, a radiation-hardened design has been considered. The measurement results show that the output reference voltage of the buffer is 4.096 V. When the temperature varied from 0 to 80 ℃, the temperature coefficient is 12.2 ppm/℃. The PSRR was -70 dB @ 100 kHz. The drive current of the reference can reach up to 10 mA. The area of the voltage reference in the SAR ADC chip is only 449 × 614μm2. The total power consumption is only 1.092 mW.展开更多
In this paper, we report on the design, simulation and testing of a novel CZT detector with an electrode named the Strengthened Electric Field Line Anode（SEFLA）. The Strengthened Electric Field（SEF） technique and ...In this paper, we report on the design, simulation and testing of a novel CZT detector with an electrode named the Strengthened Electric Field Line Anode（SEFLA）. The Strengthened Electric Field（SEF） technique and Single Polarity Charge Sensing（SPCS） technique are implemented. It could achieve the same performance as Coplanar Grid, Pixel Array CZT detectors but requires only a simple readout system. Geant4, Ansoft Maxwell and a self-developed Induced Current Calculator（ICC） package are used to develop an understanding of how the energy spectrum is formed, and the parameters of the detector are optimized. A prototype is fabricated. Experimental results demonstrate the effectiveness of this design. The test shows that the SEFLA detector achieves a FWHM of6.0% @59.5 ke V and 1.6% @662 ke V, which matches well with the simulations.展开更多
We are currently investigating the spatial resolution of highly pixelated Cadmium Zinc Telluride （CZT） detector for imaging application. A 20 mm × 20 mm× 5 mm CZT substrate was fabricated with 600 μm pitc...We are currently investigating the spatial resolution of highly pixelated Cadmium Zinc Telluride （CZT） detector for imaging application. A 20 mm × 20 mm× 5 mm CZT substrate was fabricated with 600 μm pitch pixels （500μm anode pixels with 100 μm gap） and coplanar cathode. Charge sharing between two pixels was studied using collimated a 122 keV gamma ray source. Experiments show a resolution of 125 μm FWHM for double-pixel charge sharing events when the 600 μm pixelated and 5 mm thick CZT detector biased at -1000 V. In addition, we analyzed the energy response of the 600 μm pitch pixelated CZT detector.展开更多
Cadmium zinc telluride(CZT)is a preferred material for X-ray and gamma-ray detector.Thanks to the relatively high atomic number,high density and wide band-gap,CZT detector possesses sharp energy resolution and high de...Cadmium zinc telluride(CZT)is a preferred material for X-ray and gamma-ray detector.Thanks to the relatively high atomic number,high density and wide band-gap,CZT detector possesses sharp energy resolution and high detection efficiency without cryogenic cooling.We have developed a CdZnTe detector with an energy resolution of 3.45%(FWHM)at 59.54 keV at room temperature,and it is used for X-ray fluorescence analysis.In this paper, leakage current,energy resolution and long term stability of the CZT detector are discussed.展开更多
文摘A Compton camera prototype has been developed using a pixelated CZT detector with 4-by-4 pixels.Signals of the detector are read out by a VASTAT ASIC that is controlled by a self-developed DAQ board. The DAQ software is developed using LabVIEW, and the offline Compton imaging codes are written in C++. The prototype has been successfully calibrated, and its capabilities for source detection, spectroscopy, and Compton imaging have been demonstrated using a Cs-137 source.The angular resolution of the 662 keV line is 36° FWHM for the simple back-projection method and 9.6° FWHM for the MLEM reconstruction method. The system is ready to be extended to 11-by-11 pixels in the future, and a better imaging quality can be expected due to the better relative position resolution.
基金supported by the National Key Scientific Instrument and Equipment Development Project(No.2011YQ040082)the National Natural Science Foundation of China(No.61376034)the Shaanxi Province Science and Technology Innovation Project(No.2015KTZDGY03-03)
文摘An on-chip reference voltage has been designed in capacitor-resister hybrid SAR ADC for CZT detec- tor with the TSMC 0.35 μm 2P4M CMOS process. The voltage reference has a dynamic load since using variable capacitors and resistances, which need a large driving ability to deal with the current related to the time and sampling rate. Most of the previous articles about the reference for ADC present only the bandgap part for a low temperature coefficient and high PSRR. However, it is not enough and overall, it needs to consider the output driving ability. The proposed voltage reference is realized by the band-gap reference, voltage generator and output buffer. Apart from a low temperature coefficient and high PSRR, it has the features of a large driving ability and low power con- sumption. What is more, for CZT detectors application in space, a radiation-hardened design has been considered. The measurement results show that the output reference voltage of the buffer is 4.096 V. When the temperature varied from 0 to 80 ℃, the temperature coefficient is 12.2 ppm/℃. The PSRR was -70 dB @ 100 kHz. The drive current of the reference can reach up to 10 mA. The area of the voltage reference in the SAR ADC chip is only 449 × 614μm2. The total power consumption is only 1.092 mW.
基金Supported by Ministry of Science and Technology of People’s Republic of China(2011YQ040082)
文摘In this paper, we report on the design, simulation and testing of a novel CZT detector with an electrode named the Strengthened Electric Field Line Anode（SEFLA）. The Strengthened Electric Field（SEF） technique and Single Polarity Charge Sensing（SPCS） technique are implemented. It could achieve the same performance as Coplanar Grid, Pixel Array CZT detectors but requires only a simple readout system. Geant4, Ansoft Maxwell and a self-developed Induced Current Calculator（ICC） package are used to develop an understanding of how the energy spectrum is formed, and the parameters of the detector are optimized. A prototype is fabricated. Experimental results demonstrate the effectiveness of this design. The test shows that the SEFLA detector achieves a FWHM of6.0% @59.5 ke V and 1.6% @662 ke V, which matches well with the simulations.
基金Supported by NSFC(11305083)Fundamental Research Funds for the Central Universities(lzujbky-2013-5)
文摘We are currently investigating the spatial resolution of highly pixelated Cadmium Zinc Telluride （CZT） detector for imaging application. A 20 mm × 20 mm× 5 mm CZT substrate was fabricated with 600 μm pitch pixels （500μm anode pixels with 100 μm gap） and coplanar cathode. Charge sharing between two pixels was studied using collimated a 122 keV gamma ray source. Experiments show a resolution of 125 μm FWHM for double-pixel charge sharing events when the 600 μm pixelated and 5 mm thick CZT detector biased at -1000 V. In addition, we analyzed the energy response of the 600 μm pitch pixelated CZT detector.
文摘Cadmium zinc telluride(CZT)is a preferred material for X-ray and gamma-ray detector.Thanks to the relatively high atomic number,high density and wide band-gap,CZT detector possesses sharp energy resolution and high detection efficiency without cryogenic cooling.We have developed a CdZnTe detector with an energy resolution of 3.45%(FWHM)at 59.54 keV at room temperature,and it is used for X-ray fluorescence analysis.In this paper, leakage current,energy resolution and long term stability of the CZT detector are discussed.
