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Analysis of Astrium Radiation 2nd Campaign RVS Data

Study on the effects of radiation exposure on Astrium's CCD, analyzing signal levels, CTI effects, and quantitative results at different temperatures. Damage assessment and implications on RV bias and EW reduction revealed.

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Analysis of Astrium Radiation 2nd Campaign RVS Data

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  1. Analysis of the Astrium radiation 2nd campaign RVS data C. Allende Prieto MSSL, Univ. College London

  2. The setup • Red enhanced TDI-operated e2v CCD: calibration runs with un-irradiated CCD, rest with partly irradiated (2e9 p+/cm2) CCD • Mask and optics mounted on a movable train displaced in sync with TDI charge shift • CCD read for 8000 TDI periods, runs separated by 27s • Runs with different illumination levels and detector temperatures

  3. The mask pattern

  4. What we get • Samples: signal over 9 pixels in AC • Sample 1: pre-scan • Samples 2-3-4: reference square • Samples 5-13: non-irradiated area • Samples 14-32: irradiated area • Data for V6.10, V6.00, V5.76, V5.52, V5.28, V5.21 • Data for T=161, 175, 185, 195 K

  5. A reconstructed image

  6. .. closer

  7. … and closer

  8. Calibration • Background • flatfielding

  9. Signal levels • V6.00= 300 e- (Grvs~ 7.7) 4 runs • V5.76= 30 e- (10.2) 5 • V5.52= 3 e- (12.8) 10 • V5.28= 0.5 e- (15.7) 50 • V5.21= 0.3 e- (16.9) 100 WARNING: Spectra look much better than they will do for a single transit

  10. Signal levels

  11. V6.10 -- Calibration runs

  12. V6.0 (Grvs ~ 7.7)

  13. V5.76 (Grvs~ 10.2)

  14. V5.52 (Grvs ~ 12.8)

  15. V5.28 (Grvs ~ 15.7)

  16. V5.21 (Grvs ~ 16.9)

  17. CTI effects • Distorted continuum shape, especially at the beginning • Net loss of charge, trailing charges • Filling-in of the absorption lines, hence reduced equivalent widths • Distorted line shapes, systematic shifts of the line centers • Reduced line-to-continuum contrast, hence larger random errors in RV

  18. Quantitative analysis (185 K) Grvs net loss RV bias EW change _______________________________ 7.7 4% -0.3 pix - 5% 10.2 16% -0.9 pix -30% 12.8 28% -1.3 pix -60% 15.7 44% -1.4 pix -70% 16.9 44% -1.5 pix -80%

  19. Damages • Modest effects regarding RV bias: less than 2 pixels or 20 km/s at the lowest illumination levels • Modest charge loss: < 50% at worse • But dramatic EW reduction: 80% at 185 K, 100% at 195 K for Grvs~ 16.9 • The lines are washed down, causing a huge impact on the random errors on the derived RVs: x20 at Grvs~ 15.7 mag (400 km/s), x7 at Grvs~ 12.8 mag (35 km/s) • Losing 4 magnitudes?

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