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R B Barreiro - One of the best experts on this subject based on the ideXlab platform.
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Planck 2013 results. IX. HFI Spectral Response
Astronomy and Astrophysics, 2014Co-Authors: Nabila Aghanim, C. Armitage-caplan, Monique Arnaud, F. Atrio-barandela, M Ashdown, J Aumont, Carlo Baccigalupi, A J Banday, R B BarreiroAbstract:The Planck High Frequency Instrument (HFI) Spectral Response was determined through a series of ground based tests conducted with the HFI focal plane in a cryogenic environment prior to launch. The main goal of the Spectral transmission tests was to measure the relative Spectral Response (includingthe level of out-of-band signal rejection) of all HFI detectors to a known source of electromagnetic radiation individually. This was determined by measuring the interferometric output of a continuously scanned Fourier transform spectrometer with all HFI detectors. As there is no on-board spectrometer within HFI, the ground-based Spectral Response experiments provide the definitive data set for the relative Spectral calibration of the HFI. Knowledge of the relative variations in the Spectral Response between HFI detectors allows for a more thorough analysis of the HFI data. The Spectral Response of the HFI is used in Planck data analysis and component separation, this includes extraction of CO emission observed within Planck bands, dust emission, Sunyaev-Zeldovich sources, and intensity to polarization leakage. The HFI Spectral Response data have also been used to provide unit conversion and colour correction analysis tools. While previous papers describe the pre-flight experiments conducted on the Planck HFI, this paper focusses on the analysis of the pre-flight Spectral Response measurements and the derivation of data products, e.g. band-average spectra, unit conversion coefficients, and colour correction coefficients, all with related uncertainties. Verifications of the HFI Spectral Response data are provided through comparisons with photometric HFI flight data. This validation includes use of HFI zodiacal emission observations to demonstrate out-of-band Spectral signal rejection better than 108. The accuracy of the HFI relative Spectral Response data is verified through comparison with complementary flight-data based unit conversion coefficients and colour correction coefficients. These coefficients include those based upon HFI observations of CO, dust, and Sunyaev-Zeldovich emission. General agreement is observed between the ground-based Spectral characterization of HFI and corresponding in-flight observations, within the quoted uncertainty of each; explanations are provided for any discrepancies.
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Planck 2013 results. IX. HFI Spectral Response
Astronomy & Astrophysics, 2014Co-Authors: Peter A. R. Ade, C. Armitage-caplan, Monique Arnaud, F. Atrio-barandela, M Ashdown, Nabila Aghanim, J Aumont, Carlo Baccigalupi, A J Banday, R B BarreiroAbstract:The Planck High Frequency Instrument (HFI) Spectral Response was determined through a series of ground based tests conducted with the HFI focal plane in a cryogenic environment prior to launch. The main goal of the Spectral transmission tests was to measure the relative Spectral Response (including out-of-band signal rejection) of all HFI detectors. This was determined by measuring the output of a continuously scanned Fourier transform spectrometer coupled with all HFI detectors. As there is no on-board spectrometer within HFI, the ground-based Spectral Response experiments provide the definitive data set for the relative Spectral calibration of the HFI. The Spectral Response of the HFI is used in Planck data analysis and component separation, this includes extraction of CO emission observed within Planck bands, dust emission, Sunyaev-Zeldovich sources, and intensity to polarization leakage. The HFI Spectral Response data have also been used to provide unit conversion and colour correction analysis tools. Verifications of the HFI Spectral Response data are provided through comparisons with photometric HFI flight data. This validation includes use of HFI zodiacal emission observations to demonstrate out-of-band Spectral signal rejection better than 10^8. The accuracy of the HFI relative Spectral Response data is verified through comparison with complementary flight-data based unit conversion coefficients and colour correction coefficients. These coefficients include those based upon HFI observations of CO, dust, and Sunyaev-Zeldovich emission. General agreement is observed between the ground-based Spectral characterization of HFI and corresponding in-flight observations, within the quoted uncertainty of each; explanations are provided for any discrepancies.
Benkang Chang - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of chemical cleaning for Ga1−xAlxAs photocathode by Spectral Response
Optics Communications, 2013Co-Authors: Xinlong Chen, Benkang Chang, Jing Zhao, Guanghui Hao, Muchun JinAbstract:Abstract The Spectral Response has been used to evaluate the chemical cleaning for Ga1−xAlxAs photocathode by an on-line Spectral Response measurement system. The Spectral Response curves of Ga1−xAlxAs photocathodes treated by different chemical cleaning methods are measured and analyzed in detail. We use the quantum efficiency formulas to fit the experimental curves transforming from the Spectral Response curves, and obtain the related performance parameters such as the surface electron escape probability, the back-interface recombination velocity, the electron diffusion length, and the thickness of the etching GaAs layer. The results show that the GaAs photocathode cleaned by the HF solution could obtain a good photoemission effect, while the Ga0.37Al0.63As photocathode could be well cleaned by the solution of sulfuric acid and hydrogen peroxide.
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variation of Spectral Response for exponential doped transmission mode gaas photocathodes in the preparation process
Applied Optics, 2010Co-Authors: Yijun Zhang, Jijun Zou, Benkang Chang, Jun Niu, Yajuan XiongAbstract:To confirm the actual effect of an exponential-doped structure on cathode performance, an exponential-doped structure was applied to the preparation of a transmission-mode GaAs photocathode, and Spectral Response curves after high-temperature activation, low-temperature activation, and the indium sealing process were separately measured by use of the on-line Spectral Response measurement system. The results show that, compared to the previously uniform-doped photocathode, the exponential-doped photocathode can obtain higher cathode performance and photoemission capability because of the built-in electric field. Nevertheless, cesium desorption and impurity of gas during the sealing process can cause the degeneration of Spectral Response in the entire Response waveband, especially in the long-wavelength region, with the decrease in surface electron escape probability related to the adverse evolution of the surface potential barrier profile.
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Variation of Spectral Response from cesium-covered GaAs and band features contained within the Spectral Response
Applied Optics, 2010Co-Authors: Jijun Zou, Benkang Chang, Yijun Zhang, Zhi YangAbstract:The Spectral Response and band features of cesium-covered GaAs have been investigated by using a Spectral-Response measuring instrument at room temperature. We find that the shape of the Spectral-Response curves is almost identical if the vacuum level is greater than the energy level of the conduction band minimum; otherwise, the shape changes with time. The preservation or change in the shape is attributed to the evolution of a surface barrier. By calculation of the derivatives of the Spectral Response, the band features of GaAs can be determined. We find six peaks in the Spectral-Response derivatives. These peaks are in excellent agreement with the photon energy positions determined by the transitions from different valence band peaks to different conduction band valleys.
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Variation of Spectral Response curves of GaAs photocathodes in activation chamber
Optoelectronic Materials and Devices, 2006Co-Authors: Jijun Zou, Benkang Chang, Zhi Yang, Hui Wang, Pin GaoAbstract:The Spectral Response curves of reflection-mode GaAs (100) photocathodes are measured in activation chamber by multi-information measurement system at RT, and by applying quantum efficiency formula, the variation of Spectral Response curves have been studied. Reflection-mode GaAs photocathodes materials are grown over GaAs wafer (100) by MBE with p-type beryllium doping, doping concentration is 1×1019 cm-3 and the active layer thickness is 1.6μm. During the high-temperature activation process, the Spectral Response curves varied with activation time are measured. After the low-temperature activation, the photocathode is illuminated by a white light source, and the Spectral Response curves varied with illumination time are measured every other hour. Experimental results of both high-temperature and low-temperature activations show that the Spectral Response curve shape of photocathodes is a function of time. We use traditional quantum efficiency formulas of photocathodes, in which only the Γ photoemission is considered, to fit experimental Spectral Response curves, and find the theoretical curves are not in agreement with the experimental curves, the reason is other valley and hot-electron yields are necessary to be included in yields of reflection-mode photocathodes. Based on the two-minima diffusion model and the fit of escape probability, we modified the quantum efficiency formula of reflection-mode photocathodes, the modified formula can be used to explain the variation of yield curves of reflection-mode photocathodes very well.
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Spectral Response variation of a negative-electron-affinity photocathode in the preparation process
Applied optics, 2006Co-Authors: Lei Liu, Benkang Chang, Qian Yun-shengAbstract:In order to research the Spectral Response variation of a negative electron affinity (NEA) photocathode in the preparation process, we have done two experiments on a transmission-type GaAs photocathode. First, an automatic Spectral Response recording system is described, which is used to take Spectral Response curves during the activation procedure of the photocathode. By this system, the Spectral Response curves of a GaAs:Cs-O photocathode measured in situ are presented. Then, after the cathode is sealed with a microchannel plate and a fluorescence screen into the image tube, we measure the Spectral Response of the tube by another measurement instrument. By way of comparing and analyzing these curves, we can find the typical variation in Spectral-Responses. The reasons for the variation are discussed. Based on these curves, Spectral matching factors of a GaAs cathode for green vegetation and rough concrete are calculated. The visual ranges of night-vision goggles under specific circumstances are estimated. The results show that the Spectral Response of the NEA photocathode degraded in the sealing process, especially at long wavelengths. The variation has also influenced the whole performance of the intensifier tube.
Nabila Aghanim - One of the best experts on this subject based on the ideXlab platform.
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Planck 2013 results. IX. HFI Spectral Response
Astronomy and Astrophysics, 2014Co-Authors: Nabila Aghanim, C. Armitage-caplan, Monique Arnaud, F. Atrio-barandela, M Ashdown, J Aumont, Carlo Baccigalupi, A J Banday, R B BarreiroAbstract:The Planck High Frequency Instrument (HFI) Spectral Response was determined through a series of ground based tests conducted with the HFI focal plane in a cryogenic environment prior to launch. The main goal of the Spectral transmission tests was to measure the relative Spectral Response (includingthe level of out-of-band signal rejection) of all HFI detectors to a known source of electromagnetic radiation individually. This was determined by measuring the interferometric output of a continuously scanned Fourier transform spectrometer with all HFI detectors. As there is no on-board spectrometer within HFI, the ground-based Spectral Response experiments provide the definitive data set for the relative Spectral calibration of the HFI. Knowledge of the relative variations in the Spectral Response between HFI detectors allows for a more thorough analysis of the HFI data. The Spectral Response of the HFI is used in Planck data analysis and component separation, this includes extraction of CO emission observed within Planck bands, dust emission, Sunyaev-Zeldovich sources, and intensity to polarization leakage. The HFI Spectral Response data have also been used to provide unit conversion and colour correction analysis tools. While previous papers describe the pre-flight experiments conducted on the Planck HFI, this paper focusses on the analysis of the pre-flight Spectral Response measurements and the derivation of data products, e.g. band-average spectra, unit conversion coefficients, and colour correction coefficients, all with related uncertainties. Verifications of the HFI Spectral Response data are provided through comparisons with photometric HFI flight data. This validation includes use of HFI zodiacal emission observations to demonstrate out-of-band Spectral signal rejection better than 108. The accuracy of the HFI relative Spectral Response data is verified through comparison with complementary flight-data based unit conversion coefficients and colour correction coefficients. These coefficients include those based upon HFI observations of CO, dust, and Sunyaev-Zeldovich emission. General agreement is observed between the ground-based Spectral characterization of HFI and corresponding in-flight observations, within the quoted uncertainty of each; explanations are provided for any discrepancies.
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Planck 2013 results. IX. HFI Spectral Response
Astronomy & Astrophysics, 2014Co-Authors: Peter A. R. Ade, C. Armitage-caplan, Monique Arnaud, F. Atrio-barandela, M Ashdown, Nabila Aghanim, J Aumont, Carlo Baccigalupi, A J Banday, R B BarreiroAbstract:The Planck High Frequency Instrument (HFI) Spectral Response was determined through a series of ground based tests conducted with the HFI focal plane in a cryogenic environment prior to launch. The main goal of the Spectral transmission tests was to measure the relative Spectral Response (including out-of-band signal rejection) of all HFI detectors. This was determined by measuring the output of a continuously scanned Fourier transform spectrometer coupled with all HFI detectors. As there is no on-board spectrometer within HFI, the ground-based Spectral Response experiments provide the definitive data set for the relative Spectral calibration of the HFI. The Spectral Response of the HFI is used in Planck data analysis and component separation, this includes extraction of CO emission observed within Planck bands, dust emission, Sunyaev-Zeldovich sources, and intensity to polarization leakage. The HFI Spectral Response data have also been used to provide unit conversion and colour correction analysis tools. Verifications of the HFI Spectral Response data are provided through comparisons with photometric HFI flight data. This validation includes use of HFI zodiacal emission observations to demonstrate out-of-band Spectral signal rejection better than 10^8. The accuracy of the HFI relative Spectral Response data is verified through comparison with complementary flight-data based unit conversion coefficients and colour correction coefficients. These coefficients include those based upon HFI observations of CO, dust, and Sunyaev-Zeldovich emission. General agreement is observed between the ground-based Spectral characterization of HFI and corresponding in-flight observations, within the quoted uncertainty of each; explanations are provided for any discrepancies.
Andres Cuevas - One of the best experts on this subject based on the ideXlab platform.
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Generalized models of the Spectral Response of the voltage for the extraction of recombination parameters in silicon devices
Journal of Applied Physics, 2005Co-Authors: Helmut Mackel, Andres CuevasAbstract:Analytical models of the Spectral Response of the voltage of silicon devices have been generalized using the concept of the internal quantum efficiency of the semiconductor. This allows the extension of models used in the analysis of the internal quantum efficiency to the Spectral Response of the voltage. Existing models for the Spectral Response of the voltage that are largely employed in the surface photovoltage technique are shown to be special cases that approximate the internal quantum efficiency. A more sophisticated model of the internal quantum efficiency, the model of Isenberg, and a model that allows the analysis of the internal quantum efficiency of rear-illuminated devices have been adapted to the Spectral Response of the voltage. This paves the way to analyze solar cells, Schottky devices, or chemically treated silicon wafers independently of the light intensity and using front or rear illumination. The models have been validated by comparing the analysis of the Spectral Response of the short...
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The Spectral Response of the open-circuit voltage: a new characterization tool for solar cells
Solar Energy Materials and Solar Cells, 2004Co-Authors: Helmut Mackel, Andres CuevasAbstract:This paper explores the possibility of measuring the open-circuit voltage of a solar cell as a function of wavelength as a tool for device characterization. Theoretical calculations and computer simulations show that the Spectral Response of the open-circuit voltage exhibits a similar dependence to the Spectral Response of the short-circuit current. Experimental studies on silicon solar cells confirmed the strong Spectral dependence of the open-circuit voltage. The Spectral measurements have been performed using a quasi-steady-state open-circuit voltage method, which also allows to determine the Spectral Response of the maximum power voltage. The advantages of this new technique over conventional Spectral Response measurements include its applicability directly after junction formation and the simplicity of the experimental apparatus.
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Spectral Response of the photoconductance: a new technique for solar cell characterization
2001Co-Authors: Helmut Mackel, Andres CuevasAbstract:Abstract A new technique, the Spectral Response of the steady-state photoconductance, is proposed for solar cell characterization in research and development. The method is experimentally demonstrated with solar cell precursors having emitters with markedly different levels of surface and bulk recombination losses. A high-efficiency solar cell has been investigated, comparing the new Spectral Response method to the conventional Spectral Response. The Spectral Response of the photoconductance has been measured with a contactless quasi-steady state photoconductance method (QSSPC) using light of different wavelengths. The measured Spectral Response of the photoconductance has been compared to PC1D simulations. A good agreement between theory and experiment, and between the two Spectral Response techniques has been found. The main advantages of the Spectral photoconductance technique are that it is fast, contactless, and can be used immediately after junction formation before metallization. These properties make it very appropriate for routine monitoring of the emitter region, including in-line process control.
C. Armitage-caplan - One of the best experts on this subject based on the ideXlab platform.
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Planck 2013 results. IX. HFI Spectral Response
Astronomy and Astrophysics, 2014Co-Authors: Nabila Aghanim, C. Armitage-caplan, Monique Arnaud, F. Atrio-barandela, M Ashdown, J Aumont, Carlo Baccigalupi, A J Banday, R B BarreiroAbstract:The Planck High Frequency Instrument (HFI) Spectral Response was determined through a series of ground based tests conducted with the HFI focal plane in a cryogenic environment prior to launch. The main goal of the Spectral transmission tests was to measure the relative Spectral Response (includingthe level of out-of-band signal rejection) of all HFI detectors to a known source of electromagnetic radiation individually. This was determined by measuring the interferometric output of a continuously scanned Fourier transform spectrometer with all HFI detectors. As there is no on-board spectrometer within HFI, the ground-based Spectral Response experiments provide the definitive data set for the relative Spectral calibration of the HFI. Knowledge of the relative variations in the Spectral Response between HFI detectors allows for a more thorough analysis of the HFI data. The Spectral Response of the HFI is used in Planck data analysis and component separation, this includes extraction of CO emission observed within Planck bands, dust emission, Sunyaev-Zeldovich sources, and intensity to polarization leakage. The HFI Spectral Response data have also been used to provide unit conversion and colour correction analysis tools. While previous papers describe the pre-flight experiments conducted on the Planck HFI, this paper focusses on the analysis of the pre-flight Spectral Response measurements and the derivation of data products, e.g. band-average spectra, unit conversion coefficients, and colour correction coefficients, all with related uncertainties. Verifications of the HFI Spectral Response data are provided through comparisons with photometric HFI flight data. This validation includes use of HFI zodiacal emission observations to demonstrate out-of-band Spectral signal rejection better than 108. The accuracy of the HFI relative Spectral Response data is verified through comparison with complementary flight-data based unit conversion coefficients and colour correction coefficients. These coefficients include those based upon HFI observations of CO, dust, and Sunyaev-Zeldovich emission. General agreement is observed between the ground-based Spectral characterization of HFI and corresponding in-flight observations, within the quoted uncertainty of each; explanations are provided for any discrepancies.
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Planck 2013 results. IX. HFI Spectral Response
Astronomy & Astrophysics, 2014Co-Authors: Peter A. R. Ade, C. Armitage-caplan, Monique Arnaud, F. Atrio-barandela, M Ashdown, Nabila Aghanim, J Aumont, Carlo Baccigalupi, A J Banday, R B BarreiroAbstract:The Planck High Frequency Instrument (HFI) Spectral Response was determined through a series of ground based tests conducted with the HFI focal plane in a cryogenic environment prior to launch. The main goal of the Spectral transmission tests was to measure the relative Spectral Response (including out-of-band signal rejection) of all HFI detectors. This was determined by measuring the output of a continuously scanned Fourier transform spectrometer coupled with all HFI detectors. As there is no on-board spectrometer within HFI, the ground-based Spectral Response experiments provide the definitive data set for the relative Spectral calibration of the HFI. The Spectral Response of the HFI is used in Planck data analysis and component separation, this includes extraction of CO emission observed within Planck bands, dust emission, Sunyaev-Zeldovich sources, and intensity to polarization leakage. The HFI Spectral Response data have also been used to provide unit conversion and colour correction analysis tools. Verifications of the HFI Spectral Response data are provided through comparisons with photometric HFI flight data. This validation includes use of HFI zodiacal emission observations to demonstrate out-of-band Spectral signal rejection better than 10^8. The accuracy of the HFI relative Spectral Response data is verified through comparison with complementary flight-data based unit conversion coefficients and colour correction coefficients. These coefficients include those based upon HFI observations of CO, dust, and Sunyaev-Zeldovich emission. General agreement is observed between the ground-based Spectral characterization of HFI and corresponding in-flight observations, within the quoted uncertainty of each; explanations are provided for any discrepancies.
