1. Final Presentation By Matthew Lewis 17 th March 2006 “To Determine the Accuracy that GOES True Numbers can Reproduce the Full X-ray Spectrum of the Sun”

2. 17 th March 2006Final Presentation 2 Contents - The Project Questions Recap - GOES XRS - XSM Calibration for Instrument Response Correlations between Measurements Interpretation of Results Conclusions

3. 17 th March 2006Final Presentation 3 The Project An investigation to determine the accuracy to which the two broad band X-ray measurements from the NASA geostationary operational environmental satellite (GOES) can reproduce the full X-ray spectrum of the Sun

4. 17 th March 2006Final Presentation 4 GOES Geostationary Operational Environment Satellite Solar Monitor:Energetic Particle Sensor (EPS) High Energy Proton and Alpha Detector (HEPAD) Magnetometers X-ray Sensor (XRS)

5. 17 th March 2006Final Presentation 5 GOES XRS Gas ionisation detector Solar Flux e ion + Q - Q + _ Two noble gases:Xenon (0.5 – 3 Å) Argon (1 – 8 Å) Beryllium window

6. 17 th March 2006Final Presentation 6 GOES XRS Detects X-ray flux in two broad spectral ranges:0.5 – 3 Å (XS) 1 – 8 Å (XL) 2 x 10 -7 Wm -2 5 x 10 -9 Wm -2 Data below sensitivity threshold removed Removal of ‘Bad’ data points (flux levels of 3.27 x 10 4 W/m -2 )

7. 17 th March 2006Final Presentation 7 Solar Flares From GOES

8. 17 th March 2006Final Presentation 8 X-ray Solar Monitor (XSM) Calibration instrument for D-CIXS 104 degree field of view Energy range 1-20 keV Energy resolution of 250 eV at 6 keV 512 channels, 40eV/channel HPSi (High Purity Silicon) detector X Y Z SMART-1 + Y + X 45

9. 17 th March 2006Final Presentation 9 XSM Detector Energy- Resolving Semiconductor Detector Photons p-type n-type Intrinsic / insulator layer Metal contact (-) Metal contact (+) HPSi p-i-n diode Beryllium window electron hole

10. 17 th March 2006Final Presentation 10 XSM Solar Spectrum Background Combination of ‘sky’ and ‘particle’ backgrounds Sky – Due to temperature of Universe & is constant Particle – Due to cosmic rays and solar proton flux Solar proton flux not constant, variability highly dependant on solar activity Red line - solar spectrum with background subtracted Purple line is spectrum detected by XSM Black line - background

11. 17 th March 2006Final Presentation 11 XSM

12. 17 th March 2006Final Presentation 12 Instrument Calibration SUN XSM GOES XRS GOES Calibration XSM Calibration Solar Flux (Photons) Counts Counts (GOES) Counts (XSM)

13. 17 th March 2006Final Presentation 13 XSM Response XSM Efficiency Energy (keV) 0510152025 0.000 0.005 0.010 0.015 Effective Area (cm 2 ) K absorption edge (1.84 keV) Response at lower energies due to Beryllium widow thickness Response at higher energies due to Silicon detector

14. 17 th March 2006Final Presentation 14 GOES XRS Response K absorption edge (3.2 keV) L(Ш) absorption edge (4.7 keV) Response at lower energies due to Beryllium widow thickness Response at higher energies due to fill gas in ion chamber Xenon fill gas Argon fill gas

15. 17 th March 2006Final Presentation 15 Totalling XSM Flux XSM XL XSM XS GOES XS GOES XL

16. 17 th March 2006Final Presentation 16 XSM to GOES Ratio (XL) Ratio of GOES calibrated XSM to GOES measurements in XL spectral region Ratio is dependant upon solar activity No dots occur due to XSM being turned off High solar activity produces a high ratio

17. 17 th March 2006Final Presentation 17 XSM to GOES Ratio (XS) Ratio of GOES calibrated XSM to GOES measurements in XS spectral region Ratio is always greater than 1 as XSM flux is always greater than GOES Much bigger difference in the flux level for XS spectral region

18. 17 th March 2006Final Presentation 18 XSM Field of View

19. 17 th March 2006Final Presentation 19 Left side of XSM FOV Sun detected at 52 degrees field of view

20. 17 th March 2006Final Presentation 20 Right side of XSM FOV Number of Counts XSM FOV Sun detected at 42 degrees field of view Therefore total XSM field of view is 94 degree, not 105 degrees

21. 17 th March 2006Final Presentation 21 XSM FOV Calibration Right SideLeft Side Only the x-axis needs to be considered due to the limited rotation of SMART-1 Calibration is different depending upon which side of the origin the Sun is positioned

22. 17 th March 2006Final Presentation 22 Correlation GOES XL Flux Level (Wm -2 )Flare Classification 1x10 -6 ≤ F < 5x10 -6 C1 – C4 5x10 -7 ≤ F < 1x10 -6 B5 – B9 1x10 -7 ≤ F < 5x10 -7 B1 – B4 F < 1x10 -7 A

23. 17 th March 2006Final Presentation 23 Interpretation

24. 17 th March 2006Final Presentation 24 Linear Pearson Correlation Data SetXL Correlation Coefficient, R XS Correlation Coefficient, R GOES Flare Classification 00.9850.184B1 – B4 00.9620.886B5 – B9 00.9570.897C1 – C5 Linear Pearsons Correlation, R R = Covariance between X and Y (Standard Deviation of X)(Standard Deviation of Y)

25. 17 th March 2006Final Presentation 25 Conclusions Method to Compare XSM to the GOES XRS measurements is valid Solar spectrum changes during a solar flare:More energetic photons detected Spectrum become broader Good correlation between the two instruments - But correlation is a lot better for the XL spectral region than XS - & Correlation depends upon solar activity Solution, problems with the GOES XRS XS response curve Possibility that the XSM response curve is inaccurate for harder X-rays

26. 17 th March 2006Final Presentation 26 Discussion of Conclusions Many scientific experiments based upon temperature derived from GOES flux levels The ratio of the GOES true numbers can be used to determine the effective colour temperature If one or both of these flux levels are wrong than so will the temperature An example is the NEAR mission which used GOES temperature to analyse spectra from the asteroid Eros

27. 17 th March 2006Final Presentation 27 Suggestions for Further Work Questions? Increased number of Observations Measurements taken during solar maximum Use different correlation techniques Try to reproduce full X-ray spectrum of the Sun from GOES true numbers