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XMM EPIC MOS Steve Sembay Mallorca 01/04/09 A Phenomenological approach to the MOS detector response. Steve Sembay Phenomenological.

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Presentation on theme: "XMM EPIC MOS Steve Sembay Mallorca 01/04/09 A Phenomenological approach to the MOS detector response. Steve Sembay Phenomenological."— Presentation transcript:

1 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 A Phenomenological approach to the MOS detector response. Steve Sembay Phenomenological Theory. A theory which expresses mathematically the results of observed phenomena without paying detailed attention to their fundamental significance. i.e. If you don't understand it....describe it !

2 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 Motivation: Develop a descriptive model of the RMF that is computationally quick to generate and provides a “reasonably” accurate description of the spatial and temporal variations observed in the MOS RMF (i.e. the patch) A “quick” RMF makes deriving RMF parameters via optimisation procedures practical and allows one to provide a description for changes to the RMF much more quickly than “manual tweaking” Such a model could be used to inform a more physically realistic model.

3 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 tnmin optimisation program in IDL IACHEC model for 1E0102 Automated RMF fitting

4 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 x (μm) f(x) f(x) = α + (β E 0 ) E(x) = f(x) E 0 I(e) = ∑I(x)exp(E(x),e,σ) dx α = α(E 0 ), β = β(E 0 ) Current Empirical Surface Loss Model

5 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 Nov FM1 = Flight Spare“Calibrate Orsay” Apr 1998 – FM2 = MOS26 CCDs (1 faulty) Camera rebuild in June 1998 July 1998 – FM3 = MOS17 CCDs Nov 1998 – FM1 = Flight Spare7 CCDs Orsay MOS Calibration Campaign Data on 20 EPIC-MOS CCDs MOS1- All 7 CCDs in orbit have Orsay ground cal data MOS2- Due to rebuild, 4 CCDs in orbit have Orsay ground cal data

6 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 FM1MOS1MOS2FM1MOS1MOS2FM1MOS1MOS2 Orsay Data 20 CCDs E input = 350 eV

7 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 FM1MOS1MOS2FM1MOS1MOS2FM1MOS1MOS2 Orsay Data 20 CCDs E input = 350 eV

8 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 Orsay Data 20 CCDs E input = 350 eV Re-order by strength of loss peak. “Good” “Bad” What if the way the shape changes from “good” to bad” from CCD to CCD (at a given energy) is similar to the way the shape of the loss peak in the patch changes with time on the central CCD (at that energy).

9 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 Position and Size of Loss Component have relatively simple functional forms versus energy 0.73 MOS1 CCD1

10 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 Position of loss peak / position of main peak Fraction of counts in loss peak These two quantities are correlated!

11 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 Position of loss peak / position of main peak Fraction of counts in loss peak These two quantities are correlated!

12 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 The position of the loss peak relative to the main peak (The Epeak parameter) is constant with energy (at least above ~300 eV) The strength of loss peak follows a simple exponential relation with energy. The normalisation of this relation is correlated with Epeak. In this simple descriptive model, a single parameter, Epeak defines the position and strength of the loss peak as a function of energy.

13 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 Descriptive Model: The VRMF Model Main Peak Blue Wing: Gaussian Red Wing: Voigt Function = Gaussian convolved with a Lorentian. Dampening factor = 0 (Gaussian) > 0 (Lorentz-like)

14 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 Descriptive Model: The VRMF Model Loss Peak Blue Wing: Triangular Red Wing: Gaussian Time to generate 2400 x 2400 SAS p0 rmf ~ 60 seconds Time to generate 2400 x 2400 VRMF p0 rmf ~2 seconds

15 XMM EPIC MOS Steve Sembay Mallorca 01/04/ Comparing the Model to 1E0102 (MOS1)

16 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 IACHEC model for 1E0102 Automated RMF fitting Epeak σ = a + b*sqrt(E) Global Norm 4 Free Parameters

17 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 χ 2 (SAS)χ 2 (VRMF)Epeak Rev Rev Rev

18 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 χ 2 (SAS)χ 2 (VRMF)Epeak Rev Rev Rev

19 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 χ 2 (SAS)χ 2 (VRMF)Epeak Rev Rev Rev c.f. Orsay Epeak = 0.73

20 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 Lines ~ keV too strong ?

21 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 Conclusions: 1) It is possible to mathematically describe the energy dependent shape of the loss component of the RMF, as observed in our ground cal, with a model which has one dependent parameter = Epeak. (True > eV) 2) Deriving Epeak assuming the IACHEC 1E0102 model gives values consistent with that measured at Orsay for off-axis and consistent with our “picture” of the patch for on-axis. 3) What about low energies? Below ~ eV

22 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 The Curious Case of Konrad's Comet Obs: 3.29 cts/s Model: 3.33 cts/s χ 2 = Bad!

23 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 The Curious Case of Konrad's Comet Obs: 3.25 cts/s Model: 3.37 cts/s

24 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 The Curious Case of Konrad's Comet

25 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 The Curious Case of Konrad's Comet

26 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 The Curious Case of Konrad's Comet

27 XMM EPIC MOS Steve Sembay Mallorca 01/04/09 Orsay Data 20 CCDs E input = 350 eV Re-order by strength of loss peak. “Good” “Bad”


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