A multi-level clocking scheme has been developed to improve the parallel CTE of four-phase CCDs by suppressing the effects of traps located in the transport channel under barrier phases by inverting one of these phases throughout the transfer sequence.In parallel it was apparent that persistence following optical overload in Euclid VIS detectors would lead to undesirable signal released in subsequent rows and frames and that a suitable scheme for flushing this signal would be required. With care, the negatively biased electrodes during the multi-level transfer sequence can be made to pin the entire surface, row-by-row, and annihilate the problematic charges.This process can also be extended for use during integration to significantly reduce the unusable area of the detector, as per the clocked anti-blooming techniques developed many years ago; however, with the four-phase electrodes architecture of modern CCDs, we can take precautionary measures to avoid the problem of charge pumping and clock induced charge within the science frames.Clock induced charge is not all bad! We also propose the use of on-orbit trap-pumping for Euclid VIS to provide calibration input to ground based correction algorithms and as such a uniform, low noise background is require. Clock induced charge can be manipulated to provide a very suitable, low signal and noise background to the imaging array.Here we describe and present results of multi-level parallel clocking schemes for use in four-phase CCDs that could improve performance of high precision astronomy applications such as Euclid VIS.

A front-illuminated development Euclid charge-coupled device (CCD) is tested to observe the CCD point-spread function (PSF) relative to signal size using a single-pixel photon transfer curve (SP-PTC) technique. In the process of generating a SP-PTC charge redistribution effects were observed. In attempting to show that charge redistribution can be caused by exposing a charge-populated well in the CCD array to further illumination, excess charge became apparent in recorded data. Excess charge is suggested to be proportionally generated in the CCD array if existing charge is subjected to further illumination before transfer and readout. The construction of an optical test bench and CCD operating variables are discussed alongside systematic error concerns and mitigation techniques.

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 10 10 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 CIS115, the imager selected for the JANUS camera on ESA's JUICE mission to Jupiter, is a Four Transistor CMOS Image Sensor (CIS) fabricated in a 0.18 µm process. 4T CIS (like the CIS115) transfer photo generated charge collected in the pinned photodiode to the sense node through the Transfer Gate. These regions are held at different potentials and charge is transferred from the potential well under the pinned photodiode to the potential well under the sense node through a voltage pulse applied to the transfer gate. Incomplete transfer of this charge can result in image lag, where signal in previous frames can manifest itself in subsequent frames, often appearing as ghosted images in successive readouts, seriously affecting image quality in scientific instruments, which must be minimised. This is important in the JANUS camera, where image quality is essential to help JUICE meet its scientific objectives. Image lag investigation in this paper compare results pre and post Total Ionizing Dose and documents a decrease in image lag following Total Ionizing dose below device full well capacity, scaled with dose. This paper also presents two techniques to minimise image lag within the CIS115. An analysis of the optimal voltage for the transfer gate voltage is detailed where optimisation of this TG "ON" voltage has shown to minimise image lag in both an engineering model, gamma and proton irradiated devices. Secondly, a new readout method of the CIS115 is described, where following standard image integration, the PPD is biased to the reset voltage level (VRESET) through the transfer gate to empty charge on the PPD and has shown to reduce image lag in the CIS115

The CIS115 is one of the latest CMOS Imaging Sensors designed by e2v technologies, with 1504x2000 pixels on a 7 µm pitch. Each pixel in the array is a pinned photodiode with a 4T architecture, achieving an average dark current of 22 electrons pixel -1 s -1 at 21°C measured in a front-faced device. The sensor aims for high optical sensitivity by utilising e2v's back-thinning and processing capabilities, providing a sensitive silicon thickness approximately 9 µm to 12 µm thick with a tuned anti-reflective coating.The sensor operates in a rolling shutter mode incorporating reset level subtraction resulting in a mean pixel readout noise of 4.25 electrons rms. The full well has been measured to be 34000 electrons in a previous study, resulting in a dynamic range of up to 8000. These performance characteristics have led to the CIS115 being chosen for JANUS, the highresolution and wide-angle optical camera on the JUpiter ICy moon Explorer (JUICE).The three year science phase of JUICE is in the harsh radiation environment of the Jovian magnetosphere, primarily studying Jupiter and its icy moons. Analysis of the expected radiation environment and shielding levels from the spacecraft and instrument design predict the End Of Life (EOL) displacement and ionising damage for the CIS115 to be equivalent to 10 10 10 MeV protons cm -2 and 100 krad(Si) respectively. Dark current and image lag characterisation results following initial proton irradiations are presented, detailing the initial phase of space qualification of the CIS115. Results are compared to the pre-irradiation performance and the instrument specifications and further qualification plans are outlined.