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Health and cleanliness of the XMM- Newton science payload since launch

Health and cleanliness of the XMM- Newton science payload since launch.

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Health and cleanliness of the XMM- Newton science payload since launch

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  1. Health and cleanliness of the XMM-Newton science payload since launch M.G.F. KirschaA. Abbey c, B.Altieri a, D. Baskill c, K. Dennerl b, J.van Dooren e, J. Fauste a, M.J. Freyberg b, C. Gabriel a, F. Haberl b, H. Hartmann d, G. Hartner b, N. Meidinger b, L. Metcalfe a, B. Olabarri a, A.M.T. Pollock a, A.M. Read c, S. Rives a, S. Sembay c, M.J.S. Smith a, M. Stuhlinger a, A. Talavera a aEuropean Space Agency (ESA), European Space Astronomy Centre (ESAC), Villafranca, Apartado 50727, 28080 Madrid, Spain, bMax-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany, cDept. of Physics and Astronomy, Leicester University, Leicester LE1 7RH, U.K., dEADS Astrium GmbH

  2. menu • What does healthy and clean mean? • XMM-Newton operations- 5 years in orbit • Instrument performance monitoring • Contamination monitoring • The need for X-ray standards • Conclusions

  3. Healthy and clean • Instrument performance is unchanged or change is understood and can be modeled • Health risks: • Soft protons funneled by mirrors • Hard particles Reduction of Charge Transfer Efficiency and energy resolution • Instruments show no contamination • Particulate contamination • Molecular contamination • Contamination risk • Outgassing material Reduction of effective area and creation of edges in spectra

  4. Cleanliness requirements Before launch • In order to fulfil the requirements of an absolute effective area accuracy of 10 % at any energy included between 0.1-10 keV and a relative accuracy better than 3 %till the end of the XMM-NEWTON life time a maximum of 200 ppm for particulate contamination and 210-7 g cm-2 for molecular contamination should not be exceeded. • preliminary error budget indicated a contamination increase of 140 ppm for particulate and 1.510-7 g cm-2 molecular contamination between the end of the ground calibration tests at the PANTER test facility and the start of the in-orbit operation.

  5. XMM-Newton • 3 mirror modules with 58 shells each • EPIC: • 2 MOS CCD cameras • 1 pn CCD camera • 2 Reflecting Grating Spectrometers • 1 Optical Monitor

  6. EPIC-pn-CCD camera shows correlation between the gain and the temperature of quadrant boxes temperature decrease of 1 C corresponds to an energy shift of ~0.4 adu (~ 2 eV) at the Mn-Kenergy of 5.9 keV clear trend for all modes, a temperature decrease of about 3.2 mK per revolution (~ 0.59 C per year). similar trend for the EPIC-MOS electronics boxes and for the total satellite temperature. orbital change and consequently reduced reflected emission from Earth may have decreased the temperature Upto now no significant drift in line energies of Al-K, Mn-K, and Cu-K in EPIC-pn could be identified (e.g., expected -6 eV at Mn-K from a pure temperature-gain relation after 1000 evolutions). small (< 10-5) systematic long-term variation of the EPIC-pn oscillator frequency has been found which could be related to the temperature variation presented here (Freyberg et al. 2005). housekeeping monitoring we show the temperature of all focal plane CCDs As a consequence of the cooling of the EPIC-MOS and RGS instruments these temperatures are dropping at the end of 2002. excursions of the temperature due to eclipse seasonal effect is seen that causes a kind of wave structure in temperature at the end and the beginning of the revolution due to the influence of the albedo of the earth scientific data is not affected by those temperature excursions since scientific observations are only started when the nominal CCD temperatures are reached. Thermal history

  7. Radiation • High fluctuations and variability on very short time scales of the particle background • Especially soft-protons funnelled by the telescope, damaging for CCDs. • Soft-proton flaring can occur at any altitude but probability increases towards radiation belt • Asymmetry of radiation profile across the revolution, with seasonal variations  a radiation model was developed and now used for operations.

  8. Micrometeoroids • 4 impacts so far in the mission • Last one in rev 961 (March 05) caused the loss of MOS1 CCD6 and a new hot column passing very close to the MOS1 boresight. • After a sudden optical flash, bright hot pixels appear • Interpreted as a dust micrometeoroid scattered off the mirror surface under grazing incidence and reaching the focal plane detector. • Typical size ~< 1 micron • Interplanetary (or interstellar) dust but not linked to meteor shower (higher sizes/masses)

  9. EPIC-MOS patch Rev 247 MOS1 Rev 247 MOS2 • small patch on each detector has been discovered using all archived 1ES0102 observation and performing in addition a raster scan to identify position and time variability. • patch has degraded over time. • broadens the redistribution function at energies around 0.5 keV • coincident with the nominal position of sources when placed at EPIC-pn and RGS boresights, i.e :the peak in received photon dose of the detectors • causes a significant change in the low energy redistribution characteristics of the EPIC-MOS cameras, which is spatially and temporarily dependent • the situation seems to have stabilised and we see • no evidence for contaminant • Epoch dependent canned Response Matrices (RMF) are currently under testing. The task rmfgen of analysis software XMM-Newton SAS-6.5 will be able to produce spatially and epoch dependent RMFs for all epochs and off axis angles. Rev 447 MOS2 Rev 447 MOS1 smoothed images 1ES01020.1-0.35 keV

  10. MOS patch effect calibrated SAS 6.1 (public) SAS 6.5 (August 2005) EPIC-pn MOS1 MOS2RGS1RGS2

  11. EPIC MOS CTI since launch

  12. EPIC-Charge Transfer Efficiency • EPIC-pn CTE degradation is slight and in agreement with pre-launch predictions • no clear correlation between the EPIC-pn CTE degradation and proton flares • Solar flares created a series of jumps in the EPIC-MOS cameras CTE • EPIC-pn CTI is degrading independently of the solar flares with a nearly constant rate of 4 % per year EPIC-MOS Mn EPIC-MOS Al EPIC-pn Mn EPIC-pn Al

  13. EPIC-Energy resolution • EPIC-MOS energy resolution at low energies is much better than the EPIC-pn • at high energies EPIC-MOS energy resolution was degrading up to the cooling of the EPIC-MOS cameras up to the same level as the EPIC-pn • after cooling the EPIC-MOS cameras have again a better energy resolution also for high energies. EPIC-pn Al EPIC-MOS Al EPIC-pn Mn EPIC-MOS Mn

  14. Bad Pixel • As "bad/hot pixel" we consider pixels within a CCD exhibiting abnormal behaviour which make them useless for scientific evaluation due to its tendency to mimic a signal (hot) or giving no signal (bad). • For the EPIC-MOS cameras the number of hot pixels increased over the mission time due to meteoroid events and aging due to hard particles. • after the cooling in rev 533 most of the hot pixels have disappeared and the onboard bad pixel table could have been relaxed to a few pixels per CCD. • For the EPIC-pn camera a small number of hot pixels, i.e. pixels with high dark current generation, were present in the CCDs at launch • Damage resulting from a suspected micrometeoroid impact in revolution 156 caused the sudden appearance of 35 additional hot pixels

  15. Contamination monitoring-EPIC • isolated neutron star RXJ1856-3754 is used as a target to monitor contamination on the EPIC cameras • very soft spectrum  well suited to measure possible contamination, which would affect the low energy regime most strongly • observations can be used to derive upper limits for an additional contamination between Revolutions 427 und 968 for carbon and oxygen • SNRs N132D and 1ES0102 are used to measure contamination and stability of the energy calibration of the EPIC cameras. • This analysis showed that the EPIC-MOS cameras have changed in their redistribution characteristics but not in a way consistent with contamination.

  16. EPIC-pn versus RGS • EPIC-pn camera is the most stable instrument on XMM-Newton • EPIC-pn is not contaminated • also variable objects can be used to compare relative fluxes with regard to EPIC-pn • PKS2155-304 and 3C273 have been used to perform a long time comparison of the EPIC-pn camera with the RGS1 and RGS2 • clear trend of decreasing flux in both RGSs by ~20 %

  17. Contamination monitoring-RGS • no contamination at oxygen • increasing flux deficit at carbon connection with evolution of CCD charge-transfer properties rather than contamination

  18. Contamination monitoring-OM • Laboratory measurements of all Optical Monitor components allowed to predict the throughput of the OM system • after launch in-flight throughput measured by observing standard stars was found to be lower than expected (in particular in the UV filters) • deficit observed in the in-flight throughput, as low as 16 % at 212 nm, is independent from the time sensitivity degradation of the OM detector, which is much smaller. • Molecular contamination occurred prior to or during launch could be the reason for this deficit • If we consider the number of surfaces where the contaminating material can be deposited (9 for OM), then a density of 3010-7 g cm-2 can account for the deficit in transmission.

  19. Conclusion • current status of contamination measures for XMM-Newton clearly shows that the precaution for contamination of the instruments in the design, testing and integration of the satellite has clearly paid off and should provide very low contamination behaviour until the end of the mission. • higher soft proton flux firstly discovered by Chandra was clearly a surprise for both satellites and needs especially taken into account for future missions that will operate front illuminated CCDs systematic internal calibration source measurements are mandatory for any future mission in order to guarantee a complete sampling of the CTI behaviour over time • The micrometeoroid impacts suffered by XMM-Newton could be a significant issue for future missions. • strong need for a set of standard calibration sources for the X-ray regime  luxury situation of having 6 satellites (XMM-Newton, Chandra, RXTE, Swift, Integral, Astro-E2) in orbit that are having X-ray instruments as their payload for the coming years we recommend to found an international calibration group that may steer the cross calibration efforts Splinter meeting for interested calibration peopleTuesday 2 August lunch break

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