Post on 01-Apr-2015
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XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
A Phenomenological approach to the MOSdetector 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 !
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
Motivation:
Develop a descriptive model of the RMF that is computationally quick to generate and provides a “reasonably” accuratedescription of the spatial and temporal variations observed in the MOS RMF (i.e. the patch)
A “quick” RMF makes deriving RMF parameters viaoptimisation procedures practical and allows one to providea description for changes to the RMF much more quickly than“manual tweaking”
Such a model could be used to inform a more physically realisticmodel.
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
tnmin optimisationprogram in IDL
IACHEC modelfor 1E0102
Automated RMF fitting
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
x (μm)1.0
0.0
f(x)
f(x) = α + (β E0)
E(x) = f(x) E0
I(e) = ∑I(x)exp(E(x),e,σ) dx
α = α(E0), β = β(E
0)
Current Empirical Surface Loss Model
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
Nov 1997 - FM1 = Flight Spare “Calibrate Orsay”
Apr 1998 – FM2 = MOS2 6 CCDs (1 faulty)Camera rebuild in June 1998
July 1998 – FM3 = MOS1 7 CCDs
Nov 1998 – FM1 = Flight Spare 7 CCDs
Orsay MOS Calibration Campaign
Data on 20 EPIC-MOS CCDsMOS1 - All 7 CCDs in orbit have Orsay ground cal dataMOS2 - Due to rebuild, 4 CCDs in orbit have Orsay ground cal data
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
FM1 MOS1 MOS2FM1 MOS1 MOS2FM1 MOS1 MOS2
Orsay Data
20 CCDs
Einput
= 350 eV
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
FM1 MOS1 MOS2FM1 MOS1 MOS2FM1 MOS1 MOS2
Orsay Data
20 CCDs
Einput
= 350 eV
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
Orsay Data
20 CCDs
Einput
= 350 eV
Re-order bystrength of losspeak.
“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).
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
Position and Size of Loss Component have relatively simplefunctional forms versus energy
0.73
MOS1CCD1
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
Position of loss peak / position of main peak
Fraction ofcounts in losspeak
These two quantities are correlated!
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
Position of loss peak / position of main peak
Fraction ofcounts in losspeak
These two quantities are correlated!
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
The position of the loss peak relative to the main peak(The Epeak parameter) is constant with energy (at leastabove ~300 eV)
The strength of loss peak follows a simple exponentialrelation with energy.
The normalisation of this relation is correlated with Epeak.
In this simple descriptive model, a single parameter, Epeakdefines the position and strength of the loss peak as a functionof energy.
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)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)
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)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
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
0065 1082 1165
Comparing the Model to 1E0102 (MOS1)
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
IACHEC modelfor 1E0102
Automated RMF fitting
Epeak
σ = a + b*sqrt(E)
Global Norm
4 Free Parameters
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
χ2 (SAS) χ2 (VRMF) EpeakRev 0065 2.45 2.40 0.78Rev 1082 4.06 2.01 0.70Rev 1165 5.02 1.78 0.46
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
χ2 (SAS) χ2 (VRMF) EpeakRev 0065 2.45 2.40 0.78Rev 1082 4.06 2.01 0.70Rev 1165 5.02 1.78 0.46
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
χ2 (SAS) χ2 (VRMF) EpeakRev 0065 2.45 2.40 0.78Rev 1082 4.06 2.01 0.70Rev 1165 5.02 1.78 0.46
c.f. Orsay Epeak = 0.73
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
Lines ~0.8-0.85 keV too strong ?
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
Conclusions:
1) It is possible to mathematically describe the energy dependentshape of the loss component of the RMF, as observed in our ground cal, with a model which has one dependent parameter = Epeak. (True > 300-350 eV)
2) Deriving Epeak assuming the IACHEC 1E0102 model givesvalues consistent with that measured at Orsay for off-axis andconsistent with our “picture” of the patch for on-axis.
3) What about low energies? Below ~300-350 eV
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
The Curious Case of Konrad's Comet
Obs:3.29 cts/s
Model:3.33 cts/s
χ2 = Bad!
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
The Curious Case of Konrad's Comet
Obs:3.25 cts/s
Model:3.37 cts/s
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
The Curious Case of Konrad's Comet
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
The Curious Case of Konrad's Comet
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
The Curious Case of Konrad's Comet
XMMEPICMOS
Steve Sembay (sfs5@star.le.ac.uk)Mallorca 01/04/09
Orsay Data
20 CCDs
Einput
= 350 eV
Re-order bystrength of losspeak.
“Good”
“Bad”