Understanding the evolution of radiation damage on the Gaia CCDs after 72 months at L2

Ahmed, Saad; Hall, D.; Crowley, C.; Skottfelt, J.; Dryer, Ben; Seabroke, G. M.; Hernández, J. M.; Holland, Andrew D.

doi:10.1117/1.jatis.8.1.016003

Cited by 3 publications

(4 citation statements)

References 18 publications

(44 reference statements)

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“…If the Sun is less active during this period, a GCR flux increase might be experienced. Consequently, the spacecraft may observe a higher than predicted instrument radiation background, changes in radiation damage of CCDs or similar effects as the Gaia mission experienced (Crowley et al, 2016;Ahmed et al, 2022).…”

Section: Radiation Environment and Instrument Backgroundmentioning

confidence: 97%

The CCD instrument background of the SMILE SXI

W. J. Hubbard,

Hetherington,

J. Hall

et al. 2024

Earth and Planetary Physics

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Section: Radiation Environment and Instrument Backgroundmentioning

confidence: 97%

The CCD instrument background of the SMILE SXI

W. J. Hubbard,

Hetherington,

J. Hall

et al. 2024

Earth and Planetary Physics

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“…11,12 After more than six years in orbit, the increase of CTI has not differed significantly from the previously measured trend although that is likely to change given the onset of a new solar cycle in recent years. 13 Figure 1 illustrates the trailing charge CTI as measured by irradiated on-ground devices as the in-flight CTI from multiple CCDs at two different points in the mission, albeit at different periods between in-flight and on-ground. The details of these in-flight results are outlined in another study.…”

Section: Previous Studiesmentioning

confidence: 99%

“…The details of these in-flight results are outlined in another study. 13 The on-ground CCD was irradiated at room-temperature at Gaia's predicted in-flight fluence levels with a safety margin added.…”

Section: Previous Studiesmentioning

confidence: 99%

“…In the case of Gaia, a number of different hypotheses have been proposed to explain the difference in CTI between the in-flight and on-ground CCDs such as the in-flight straylight levels, the lower solar activity, and the irradiation environment. 12,13 Analysing the CTI results directly can quantitatively tell us how much the CTI differs between in-flight and on-ground, as illustrated in Figure 1. To understand the CTI as accurately as possible however, it becomes important to try and model the charge data in order to understand the trap defect landscapes responsible for the CTI.…”

Section: Previous Studiesmentioning

confidence: 99%

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Modelling charge transfer inefficiency in Gaia CCDs with in-flight and on-ground data

Ahmed¹,

Hall

Skottfelt³

et al. 2022

X-Ray, Optical, and Infrared Detectors for Astronomy X

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The European Space Agency's Gaia spacecraft was launched in 2013 with the aim of making the largest and most precise map of the Milky Way by taking measurements of almost one billion astronomical objects. It has a focal plane that consists of 106 Charge-Coupled Devices (CCDs), custom designed by Teledyne e2v to help fulfil its objectives. These detectors make measurements of positions, velocities, parallaxes, and other physical properties of any objects, with a sufficiently bright enough magnitude, that pass through their field of view. Operating in space means that the Gaia CCDs have been subjected to radiation damage, both ionizing and non-ionizing in nature, in orbit from predominantly solar radiation. This radiation-induced damage leads to the formation of trap defects in the CCD silicon lattice which can trap electrons during readout leading to the increase of charge transfer inefficiency (CTI) and a reduction in the quality of the returned science data. From previous analysis of in-flight data, the degradation of the CCDs, measured from an increase in CTI, has been calculated to be less that that predicted from pre-flight models and on-ground tests. In this study, in-flight and on-ground data is modelled so that the trap landscapes can be further investigated. This was achieved using a charge transfer model, the Charge Distortion Model (CDM), integrated in the Pyxel detector simulation toolkit. Other simulations, namely C3TM, are used in conjunction with the results from Pyxel to obtain a more thorough understanding of the trap landscape causing the observed CTI effects.

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Radiation tolerance of a single-photon counting complementary metal-oxide semiconductor image sensor

Gallagher,

Buntic,

Deng

et al. 2024

J. Astron. Telesc. Instrum. Syst.

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We present the results of a radiation test program for a 1-megapixel single-photoncounting and photon-number-resolving CMOS image sensor. The results include pre-and post-radiation values for dark current, voltage shift at the pixels' output, read noise, quantum efficiency (QE), conversion gain, and photon counting ability. The Center for Detectors at the Rochester Institute of Technology exposed the sensor to a 50-krad(Si) dose of 60-MeV protons, equivalent to the dose absorbed over 10 11-year space missions at L2 with 1-cm aluminum shielding. The median dark current of the sensor increased from 0.00085 to 0.0085 e − ∕s∕pix at 258 K and from 0.0075 to 0.075 e − ∕s∕pix at 282 K. This is an increase of 2.0 fA∕cm 2 ∕kradðSiÞ and 17.8 fA∕cm 2 ∕kradðSiÞ, respectively. Performance in other metrics remained constant: 0.34 e − median read noise, 85% peak QE at 490 nm, and photon number resolution. We report mostly total ionizing dose and displacement damage dose effects and compare the radiation tolerance of the device to the performance of state-of-the-art charge coupled devices and CMOS devices. The detector exhibits a comparable radiation tolerance to the expected tolerance of modern CMOS devices.

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Understanding the evolution of radiation damage on the Gaia CCDs after 72 months at L2

Cited by 3 publications

References 18 publications

The CCD instrument background of the SMILE SXI

The CCD instrument background of the SMILE SXI

Modelling charge transfer inefficiency in Gaia CCDs with in-flight and on-ground data

Radiation tolerance of a single-photon counting complementary metal-oxide semiconductor image sensor

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