The swept charge device, a novel CCD-based EDX detector: first results

Lowe, B. G.; Holland, Andrew D.; Hutchinson, Ian; Burt, David; Pool, P.

doi:10.1016/s0168-9002(00)00918-9

Cited by 23 publications

(10 citation statements)

References 11 publications

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“…SCD is a new type of charge coupled device (CCD). The dark current of the SCD is much lower by being operated in the inverted mode operation (IMO) [3]. The SCD gains the faster readout speed by abandoning the position information, and the readout time of the whole frame can be less than 1ms [3].…”

Section: Introductionmentioning

confidence: 99%

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Proton irradiation effect on SCDs

et al. 2014

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The Low Energy X-ray Telescope is a main payload on the Hard X-ray Modulation Telescope satellite. The swept charge device is selected for the Low Energy X-ray Telescope. As swept charge devices are sensitive to proton irradiation, irradiation test was carried out on the HI-13 accelerator at the China Institute of Atomic Energy. The beam energy was measured to be 10 MeV at the SCD. The proton fluence delivered to the SCD was 3 × 10 8 protons/cm 2 over two hours. It is concluded that the proton irradiation affects both the dark current and the charge transfer inefficiency of the SCD through comparing the performance both before and after the irradiation. The energy resolution of the proton-irradiated SCD is 212 eV@5.9 keV at −60 • C, while it before irradiated is 134 eV. Moreover, better performance can be reached by lowering the operating temperature of the SCD on orbit.

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Section: Introductionmentioning

confidence: 99%

“…The dark current of the SCD is much lower by being operated in the inverted mode operation (IMO) [3]. The SCD gains the faster readout speed by abandoning the position information, and the readout time of the whole frame can be less than 1ms [3]. The SCD (CCD236) is especially designed to meet the scientific objectives of LE.…”

Section: Introductionmentioning

confidence: 99%

Proton irradiation effect on SCDs

et al. 2014

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“…SCDs are modified versions of conventional X-ray CCDs specially designed for non-imaging, spectroscopic studies. The C1XS experiment used an array of 24 SCDs (Lowe et al 2001) to record X-ray emission in the energy range of 0.8 to 20 keV. It offers good spectral resolution at benign operating temperatures, allowing the C1XS detectors to be operated between -10 • C to +5 • C using a passively cooled system.…”

Section: Swept Charge Devices Used In C1xsmentioning

confidence: 99%

Simulating charge transport to understand the spectral response of Swept Charge Devices

Athiray

Sreekumar

Narendranath

et al. 2015

A&A

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Context. Swept Charge Devices (SCD) are novel X-ray detectors optimized for improved spectral performance without any demand for active cooling. The Chandrayaan-1 X-ray Spectrometer (C1XS) experiment onboard the Chandrayaan-1 spacecraft used an array of SCDs to map the global surface elemental abundances on the Moon using the X-ray fluorescence (XRF) technique. The successful demonstration of SCDs in C1XS spurred an enhanced version of the spectrometer on Chandrayaan-2 using the next-generation SCD sensors. Aims. The objective of this paper is to demonstrate validation of a physical model developed to simulate X-ray photon interaction and charge transportation in a SCD. The model helps to understand and identify the origin of individual components that collectively contribute to the energy-dependent spectral response of the SCD. Furthermore, the model provides completeness to various calibration tasks, such as generating spectral matrices (RMFs -redistribution matrix files), estimating efficiency, optimizing event selection logic, and maximizing event recovery to improve photon-collection efficiency in SCDs. Methods. Charge generation and transportation in the SCD at different layers related to channel stops, field zones, and field-free zones due to photon interaction were computed using standard drift and diffusion equations. Charge collected in the buried channel due to photon interaction in different volumes of the detector was computed by assuming a Gaussian radial profile of the charge cloud. The collected charge was processed further to simulate both diagonal clocking read-out, which is a novel design exclusive for SCDs, and event selection logic to construct the energy spectrum. Results. We compare simulation results of the SCD CCD54 with measurements obtained during the ground calibration of C1XS and clearly demonstrate that our model reproduces all the major spectral features seen in calibration data. We also describe our understanding of interactions at different layers of SCD that contribute to the observed spectrum. Using simulation results, we identify the origin of different spectral features and quantify their contributions.

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“…The extended solar minimum that prevailed during the Chandrayaan-1 mission time-frame (Nov'08 -Aug'09), left C1XS with only a handful of solar flares (a few C, B and A class flares) during which quantitative analysis could be carried out. C1XS used an array of 24 Swept Charge Devices (SCDs) (Lowe et al, 2001), with each of area 1 cm 2 , to record the X-ray emission with energies of 0.8 to 10 keV. Spatial resolution for a single spectral observation varies from <50 km to >1000 km depending on spacecraft altitude and integration time.…”

Section: Overview Of C1xsmentioning

confidence: 99%

C1XS results—First measurement of enhanced sodium on the lunar surface

Athiray

Narendranath

Sreekumar

et al. 2014

Planetary and Space Science

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We describe the first unambiguous evidence of enhanced Sodium on the lunar surface revealed by the Chandrayaan-1 X-ray Spectrometer (C1XS). The C1XS onboard the Chandrayaan-1 spacecraft was designed to map the surface elemental chemistry of the Moon using the X-ray fluorescence (XRF) technique. During the nine months of remote sensing observations (Nov'2008-Aug'2009), C1XS measured XRF emission from the Moon under several solar flare conditions. A summary of entire C1XS observations and data selection methods are presented. Surface elemental abundances of major rock-forming elements viz., Mg, Al, Si and Ca as well as Na derived from C1XS data corresponding to certain nearside regions of the Moon are reported here. We also present a detailed description of the analysis techniques including derivation of XRF line fluxes and conversion to elemental abundances. The derived abundances of Na (2-3 wt%) are significantly higher than what has been known from earlier studies. We compare the surface chemistry of C1XS observed regions with the highly silicic compositions (intermediate plagioclase) measured by the Diviner Radiometer instrument onboard Lunar Reconnaissance Orbiter(LRO) in those regions.

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The swept charge device, a novel CCD-based EDX detector: first results

Cited by 23 publications

References 11 publications

Proton irradiation effect on SCDs

Proton irradiation effect on SCDs

Simulating charge transport to understand the spectral response of Swept Charge Devices

C1XS results—First measurement of enhanced sodium on the lunar surface

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