The Jupiter Icy Moon Explorer (JUICE) has been officially adopted as the next Large class mission by the European Space Agency, with a launch date of 2022. The science payload includes an optical camera, JANUS, which will perform imaging and mapping observations of Jupiter, its moons and icy rings. A 13 slot filter wheel will be used to provide spectral information in order for the JANUS experiment to study the geology and physical properties of Ganymede, Europa and Io, and to investigate processes and structures in the atmosphere of Jupiter. The sensor selected for JANUS is the back-thinned CIS115, a 3 MPixel CMOS Image Sensor from e2v technologies. The CIS115 has a 4-Transistor pixel design with a pinned photodiode to improve signal to noise performance by reducing dark current and allowing for reset level subtraction. The JUICE mission will consist of an 8 year cruise phase followed by a 3 year science phase in the Jovian system. Models of the radiation environment throughout the JUICE mission predict that the End of Life (EOL) non-ionising damage will be equivalent to 1010 protons cm-2 (10 MeV) and the EOL ionising dose will be 100 krad(Si), once the shielding from the spacecraft and instrument design is taken into account. An extensive radiation campaign is therefore being carried out to qualify and characterise the CIS115 for JANUS, as well as other space and terrestrial applications. Radiation testing to take the CIS115 to twice the ionising dose and displacement damage levels was completed in 2015 and the change in sensor performance has been characterised. Good sensor performance has been observed following irradiation and a summary of the key results from the campaign using gamma irradiation (ionising dose) will be presented here, including its soft X-ray detection capabilities, flat-band voltage shift and readout noise. In 2016, further radiation campaigns on flight-representative CIS115s will be undertaken and their results will be disseminated in future publications.
The Chandrayaan-1 X-ray Spectrometer (C1XS) was launched onboard the Indian Space Research Organisation (ISRO)
Chandrayaan-1 lunar mission in October 2008. The instrument consisted of 24 swept-charge device silicon X-ray
detectors providing a total collecting area of ~24 cm2, corresponding to a 14° field of view (FWHM), with the ability to
measure X-rays from 0.8 – 10 keV. During the 10 months the spacecraft was located in orbit around the Moon a number
of solar flare X-ray events were detected, along with calibration data from X-ray sources housed inside the movable door
of the instrument. This paper presents a further study of the degradation in spectral resolution of the measured X-ray
calibration lines, adding a final calibration point towards the end of mission lifetime to the known results from the
midpoint of the mission, giving a more detailed analysis of the extent of the radiation damage. The radiation environment
the detectors were subjected to is discussed in light of the actual radiation damage effects on the spectral resolution
observed in flight.
This paper describes the use of a swept-charge device (SCD) silicon X-ray detector in a laboratory based X-ray
fluorescence (XRF) facility for calculating elemental abundance ratios from planetary analogue powder samples. The
facility was developed to support the Chandrayaan-1 X-ray Spectrometer (C1XS) detector development and calibration
activities prior to the flight of the instrument onboard the Indian Space Research Organisation (ISRO) Chandrayaan-1
mission to the Moon in 2008. The test facility has subsequently been used to carry out XRF analysis of homogenous
samples made from mixtures of MgO, Al2O3 and SiO2 powders, all of grain size <44 μm, across a range of mixture ratios
and at a high level of X-ray flux data in order to develop an algorithm which will allow the calculation of elemental
abundance ratios. This paper also presents an analysis of XRF data collected from lunar regolith simulant JSC-1A and an
Etna Basalt powder sample to enable calibration of various model parameters. The operation of the SCD, the XRF test
facility, the sample preparation methodology and the process of obtaining elemental abundance ratios from planetary
analogue samples using the test facility are discussed in this paper.
The Chandrayaan-1 X-ray Spectrometer (C1XS) was launched onboard the Indian Space Research Organisation (ISRO)
Chandrayaan-1 lunar mission in October 2008. The instrument consisted of 24 swept-charge device silicon X-ray
detectors providing a total collecting area of ~24 cm2, corresponding to a 14° field of view (FWHM), with the ability to
measure X-rays from 0.8 - 10 keV. During the 10 months the spacecraft was located in orbit around the Moon a number
of solar flare X-ray events were detected, along with calibration data from X-ray sources housed inside the movable door
of the instrument. This paper presents a study of the degradation in spectral resolution of the measured X-ray calibration
lines, comparing those recorded mid way through the mission lifetime with ground based calibration data collected prior
to the launch of the instrument. The radiation environment the detectors were subjected to is discussed in light of the
actual radiation damage effects on the spectral resolution observed in flight.
The CCD97 is a low light level (L3) device from e2v technologies range of electron multiplying CCDs (EMCCDs). The
device uses e2v's patented extended gain register and through the use of appropriately designed electrodes can be used to
maximise the signal whilst keeping the impact of the noise to a minimum. The nature of this device makes it ideal for
use with a scintillator in order to see individual flashes of light from single X-ray photons. Through the examination of
individual X-ray events, it is possible to analyse each interaction in the scintillator to determine the sub-pixel position of
the interaction. Using the modelling capabilities of the Geant4 toolkit it is possible to simulate X-ray events and thus
examine interactions with known energy and point of interaction. Through bringing together the experimental and
simulated results, the spectral capabilities of such a device are discussed.
The Chandrayaan-1 X-ray Spectrometer (C1XS) will be launched as part of the Indian Space Research Organisation
(ISRO) Chandrayaan-1 payload in September 2008, arriving at the Moon within 7 days to begin a two year mission in
lunar orbit conducting mineralogical surface mapping over the range of 1 - 10 keV. The detector plane of the instrument
consists of twenty four e2v technologies CCD54 swept-charge devices (SCDs). Such devices were first flown in the
Demonstration of a Compact Imaging X-ray Spectrometer (D-CIXS) instrument onboard SMART-1 [4, 5]. The detector
plane in each case provides a total X-ray collection area of 26.4 cm2. The SCD is capable of providing near Fano-limited
spectroscopy at -10°C, and at -20°C, near the Chandrayaan-1 mission average temperature, it achieves a total system
noise of 6.2 electrons r.m.s. and a FWHM of 134 eV at Mn-Kα. This paper presents a brief overview of the C1XS
mission and a detailed study of the effects of proton irradiation on SCD operational performance.
The Indian Space Research Organisation (ISRO) Chandrayaan-1 mission is India's first lunar spacecraft, containing a
suite of instruments to carry out high-resolution remote sensing of the Moon at visible, near infrared and X-ray
wavelengths. Due for launch in early 2008, the spacecraft will carry out its two year mission in a polar orbit around the
Moon at an altitude of 100 km. One of the eleven instruments in the spacecraft payload is the Chandrayaan-1 X-ray
Spectrometer (C1XS), a descendant of the successful D-CIXS instrument that flew on the European Space Agency
SMART-1 lunar mission launched in 2003. C1XS consists of 24 swept-charge device (SCD) silicon X-ray detectors
arranged in 6 modules that will carry out high quality X-ray spectroscopic mapping of the Moon using the technique of
X-ray fluorescence. This paper presents an overview of the Chandrayaan-1 mission and specifically the C1XS
instrument and describes the development of an SCD test facility, proton irradiation characterisation and screening of
candidate SCD devices for the mission.
This paper describes a qualification programme for Electron-Multiplication Charge Coupled Devices (EMCCDs) for use in space applications. While the presented results are generally applicable, the programme was carried out in the context of CCD development for the Radial Velocity Spectrometer (RVS) instrument on the European Space Agency's cornerstone Gaia mission. We discuss the issues of device radiation tolerance, charge transfer efficiency at low signal levels and life time effects on the electron-multiplication gain. The development of EMCCD technology to allow operation at longer wavelengths using high resistivity silicon, and the cryogenic characterisation of EMCCDs are also described.
KEYWORDS: Charge-coupled devices, Electrons, Monte Carlo methods, Point spread functions, Calibration, Radiation effects, Data modeling, Telescopes, Modulation transfer functions, Motion models
ESA's Gaia astrometry mission is due for launch in 2011. The astrometric instrument focal plane will have an area of up to 0.5m2 and will contain more than 100 CCDs. These will be operated in Time Delay and Integration mode in order to track and observe sources whilst the telescopes continuously scan the sky. Gaia's target for astrometric precision of a few millionths of an arc second, places extreme demands on focal plane thermo--mechanical stability and electronics performance. The CCDs themselves are large area, back illuminated, full--frame, four phase devices. They require maximum efficiency for observing the majority of (faint) objects, yet must simultaneously be able to handle very bright objects that will regularly cross the field of view. Achieving the final astrometric precision will also require excellent noise performance and MTF. In addition to demanding excellent performance from each CCD, they will need to be produced in large numbers which raises production and yield issues. When analyzing Gaia data it will be essential to understand and calibrate CCD behaviour correctly, including the expected performance degradation due to radiation damage. This is being addressed through comprehensive testing and the development of CCD models.
Electron multiplying CCD (EMCCD) technology has found important initial applications in low light surveillance and photon starved scientific instrumentation. This paper discusses the attributes of the EMCCD which make it useful for certain space instruments, particularly those which are photon starved, and explores likely risks from the radiation expected in such instruments.
In recent years the XEUS mission concept has evolved and has been the subject of several industrial studies. The mission concept has now matured to the point that it could be proposed for a Phase A study and subsequent flight programme. The key feature of XEUS will be its X-ray optic with collecting area ~30-100x that of XMM. The mission is envisaged at an orbit around the L2 point in space, and is formed from two spacecraft; one for the mirrors, and the other for the focal plane detectors. With a focal length of 50m, the plate scale of the optic is 6.5x that of XMM, which using existing focal plane technology will reduce the effective field of view to a few arc minutes. Cryogenic instrumentation, with detector sizes of a few mm can only be used for narrow field studies of target objects, and a wide field instrument is under consideration using a DEPFET pixel array to image out to a diameter of 5 arcminutes, requiring an array of dimension 70mm. It is envisaged to extend this field of view possibly out to 15 arcminutes through the use of an outer detection ring comprised of MOS CCDs
The inclusion of a charge injection structure on a charge coupled device (CCD) allows for the mitigation of charge transfer loss which can be caused by radiation induced charge trapping defects. Any traps present in the pixels of the CCD are filled by the injected charge as it is swept through the device and consequently, the charge transfer efficiency is improved in subsequently acquired images. To date, a number of different types of CCD have been manufactured featuring a variety of charge injection techniques. The e2v Technologies CCD22, used in the EPIC MOS focal plane instruments of XMM-Newton, is one such device and is the subject of this paper. A detailed understanding of charge injection operation and the use of charge injection to mitigate charge transfer losses resulting from radiation damage to CCDs will benefit a number of space projects planned for the future, including the ESA GAIA and X-ray Evolving Universe Spectrometry (XEUS) missions.
The charge injection structure and mode of operation of the CCD22 are presented, followed by a detailed analysis of the uniformity and repeatability of the charge injection amplitude across the columns of the device. The effects of proton irradiation on the charge injection characteristics are also presented, in particular the effect of radiation induced bright pixels on the injected charge level.
The ESA cornerstone mission GAIA will perform astrometric, photometric and spectroscopic measurements and is due for launch in 2010 into L2 orbit. The astrometric telescope system will catalogue the position of over 109 objects down to 20th magnitude and perform broadband photometry. The spectroscopic telescope will provide narrow-band photometry and feed a Radial Velocity Spectrometer which will accurately determine the radial velocities of objects down to 17-18 magnitude. This paper discusses the characteristics of the detectors envisaged for the focal plane of the RVS instrument.
The ESA cornerstone mission GAIA will perform astrometric and photometric measurements on one billion objects, and is due for launch in 2010 into L2 orbit. The key astrometric focal plane will comprise over 180 large area CCDs with a focal surface of about 0.5m2. The 45x60mm2 CCDs for the focal plane will include technical features new to CCDs. This paper will discuss the characteristics of these devices, including the measures to improve the radiation hardness of the technology.
The effect of different proton fluences on the performance of two E2V Technologies CCD47-20 devices was investigated with particular emphasis given to the analysis of 'random telegraph signal' (RTS) generation, bright pixel generation and induced changes in base dark current level. The results show that bright pixel frequency increases as the mean energy of the proton beam is increased, and that the base dark current level after irradiation scales with the level of ionization damage. For the RTS study, 500 pixels on one device were monitored over a twelve hour period. This data set revealed a number of distinct types of pixel change level fluctuation and a system of classification has been devised. Previously published RTS data is discussed and reviewed in light of the new data.
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