RHESSI Studies of Solar Flare Hard X-Ray Polarization Mark L. McConnell 1, David M. Smith 2, A....
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Transcript of RHESSI Studies of Solar Flare Hard X-Ray Polarization Mark L. McConnell 1, David M. Smith 2, A....
RHESSI Studies of Solar Flare RHESSI Studies of Solar Flare Hard X-Ray PolarizationHard X-Ray Polarization
Mark L. McConnell1, David M. Smith2, A. Gordon Emslie4, Martin Fivian3, Gordon J. Hurford3,
Robert P. Lin3, and James M. Ryan1
1Space Science Center, University of New Hampshire, Durham, NH2Dept. Of Physics, U.C. Santa Cruz, Santa Cruz, CA
3Space Sciences Laboratory, U.C. Berkeley, Berkeley, CA4Physics Department, University of Alabama, Huntsville, AL
Polarization in Solar FlaresPolarization in Solar Flares
The hard X-ray continuum is dominated by electron bremsstrahlung emission.
Measurements of hard X-ray polarization can shed light on the geometry of the acceleration process.
Models predict polarization levels as high as 20 or 30%.
Model parameters include :
1) pitch angle distribution
2) B-field geometry
3) viewing angle
4) atm density profile
The Polarization SignatureThe Polarization Signature
For a fixed Compton scatter angle (), the azimuthal distribution of scattered photons contains the polarization signature.
The amplitude of the modulation defines the level of polarization.
The scattering angle corresponding to the minimum of the distribution defines the plane of polarization.
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Azimuthal Scatter Angle (degs)
C-max
C-min
polarization angle
€
C η( ) = A cos2(η−ϕ)+B
1
10
100
Asymmetry Ratio
1201008060Scattering Angle (degrees)
50 keV
100 keV
250 keV
500 keV
1 MeV
Asymmetry Ratio
RHESSI as a Polarimeter (20 – 100 keV)RHESSI as a Polarimeter (20 – 100 keV)
A small (3 cm diam by 3.5 cm high) cylinder of Be serves as a Compton scattering element.
The Ge detectors measure the distribution of the scattered radiation.
The rotation of the spacecraft rotation provides an effective method for fine sampling of the scatter distribution.
RHESSI as a Polarimeter (20 – 100 keV)RHESSI as a Polarimeter (20 – 100 keV)
Complications :
Varying background as a function of spacecraft spin angle.
Scattering of solar flux from parts of the spacecraft other than the Be block.
Scattering of solar flux off atmosphere (spin-dependent).
The Polarization Signal - Simulated ResultsThe Polarization Signal - Simulated Results
40 keV
40 keV
80 keV
80 keV
Top row shows results for narrow incident beam (no
spacecraft scattering).
Bottom row shows results for wide
incident beam (with spacecraft scattering).
Note the significant degradation of signal
at 80 keV.
Polarimeter Mode – Effective AreaPolarimeter Mode – Effective Area
The effective area is defined for both a narrow beam and a broad beam.
The broad beam simulation incorporates the effects of scattering of solar flux into
the rear Ge segments, which leads to an increase in effective area at higher
energies .0.01
0.1
1
10
10 100
Energy (keV)
RHESSI Polarimeter ModeEffective Area
Narrow Beam
Broad Beam
Polarimeter Mode – Modulation FactorPolarimeter Mode – Modulation Factor
The modulation factor is a measure of the quality of the polarization signal.
Scattering of incident solar flux reduces the quality of the polarization signal. (The scattered flux is not
modulated.)
1.0
0.8
0.6
0.4
0.2
0.010 100
Energy (keV)
RHESSI Polarimeter ModeModulation Factor
Narrow Beam
Broad Beam
Polarimeter Mode – Figure of MeritPolarimeter Mode – Figure of Merit
The figure-of-merit is a measure of the intrinsic capability to measure
polarization.
Here, it is defined as the product of (effective area)1/2 and the modulation factor.
As defined here, it does not incorporate the effects of
detector background.
0.6
0.5
0.4
0.3
0.2
0.1
0.010 100
Energy (keV)
RHESSI Polarimeter ModeFigure of Merit
Narrow Beam
Broad Beam
Nature of the RHESSI DataNature of the RHESSI Data
Rear Segment Data(20 – 40 keV)
X4.8 Flare - 23 July 2002
00:27 – 00:43 UT
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BGD Counts
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Detector Roll Angle
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FLR Counts
FLR interval BGD interval
Ge112000
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BGD Counts
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Detector Roll Angle
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FLR Counts
FLR interval BGD interval
Ge3
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BGD Counts
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Detector Roll Angle
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FLR Counts
FLR interval BGD interval
Ge412000
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BGD Counts
360°300°240°180°120°60°0°
Detector Roll Angle
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FLR Counts
FLR interval BGD interval
Ge5
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BGD Counts
360°300°240°180°120°60°0°
Detector Roll Angle
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FLR Counts
FLR interval BGD interval
Ge6
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BGD Counts
360°300°240°180°120°60°0°
Detector Roll Angle
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FLR Counts
FLR interval BGD interval
Ge7
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BGD Counts
360°300°240°180°120°60°0°
Detector Roll Angle
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FLR Counts
FLR interval BGD interval
Ge812000
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FLR Counts
360°300°240°180°120°60°0°
Detector Roll Angle
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BGD Counts
FLR interval BGD interval
Ge9
An Initial Approach to RHESSI AnalysisAn Initial Approach to RHESSI Analysis
Three pairs of detectors with similar background : detectors 8/9, detectors 3/5 and detectors 4/6.
The data from detectors 3-6 can be used as background estimate for the polarimeter mode detectors 8/9.
Limitations :
• Does not use detector #1
• Assumes symmetric geometry
• No modeling of Earth albedo
Nature of the RHESSI DataNature of the RHESSI Data
Rear Segment Data(20 – 40 keV)
X4.8 Flare - 23 July 2002
00:27 – 00:43 UT
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BGD Counts
360°300°240°180°120°60°0°
Detector Roll Angle
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FLR Counts
FLR interval BGD interval
Ge112000
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BGD Counts
360°300°240°180°120°60°0°
Detector Roll Angle
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FLR Counts
FLR interval BGD interval
Ge3
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BGD Counts
360°300°240°180°120°60°0°
Detector Roll Angle
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FLR Counts
FLR interval BGD interval
Ge412000
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BGD Counts
360°300°240°180°120°60°0°
Detector Roll Angle
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FLR Counts
FLR interval BGD interval
Ge5
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BGD Counts
360°300°240°180°120°60°0°
Detector Roll Angle
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FLR Counts
FLR interval BGD interval
Ge6
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BGD Counts
360°300°240°180°120°60°0°
Detector Roll Angle
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FLR Counts
FLR interval BGD interval
Ge7
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BGD Counts
360°300°240°180°120°60°0°
Detector Roll Angle
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FLR Counts
FLR interval BGD interval
Ge812000
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FLR Counts
360°300°240°180°120°60°0°
Detector Roll Angle
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BGD Counts
FLR interval BGD interval
Ge9
X4.8 Flare of 23-July-2002X4.8 Flare of 23-July-200225000
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Counts per 5 sec Time Bin
00:20 00:30 00:40 00:50
Time (UT)
FLR207230120 - 40 keV
FLR BGD1 (24 hrs before) BGD2 (24 hrs after)
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15000
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Counts per 5 sec Time Bin
00:20 00:30 00:40 00:50
Time (UT)
FLR207230140 - 60 keV
FLR BGD1 (24 hrs before) BGD2 (24 hrs after)
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15000
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Counts per 5 sec Time Bin
00:20 00:30 00:40 00:50
Time (UT)
FLR207230160 - 80 keV
FLR BGD1 (24 hrs before) BGD2 (24 hrs after)
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Counts per 5 sec Time Bin
00:20 00:30 00:40 00:50
Time (UT)
FLR207230180 - 100 keV
FLR BGD1 (24 hrs before) BGD2 (24 hrs after)
Analysis Interval : 00:27 – 00:43 UT
X4.8 Flare of 23-July-2002X4.8 Flare of 23-July-2002
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-5000
Counts per 15°
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
20 – 40 keV
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-5000
Counts per 15°
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Azimuthal Scatter Angle
20 – 40 keV
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-5000
Counts per 15°
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
40 - 60 keV
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-5000
Counts per 15°
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
40 - 60 keV
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0
-5000
Counts per 15°
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
60 - 80 keV
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-5000
Counts per 15°
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
60 - 80 keV
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0
-5000
Counts per 15°
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
80 - 100 keV
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-5000
Counts per 15°
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
80 - 100 keV
“Background”-subtracted data
An Initial Approach to RHESSI AnalysisAn Initial Approach to RHESSI Analysis
Two Component Analysis
1. Systematic Component:• Single sinusoid component.
2. Polarization Signal• Double sinusoid component.
€
f (η ) = A + B sin2(η −ϕ ) + C sinα (η −ψ )
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Counts per 15°
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
20 – 40 keV
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-5000
Counts per 15°
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
20 – 40 keV
Background SystematicsBackground Systematics
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FLR Counts
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Detector Roll Angle
Ge4/6 - Ge5/3
X4.8 Flare of 23-July-2002X4.8 Flare of 23-July-2002
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-5000
Counts per 15°
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
20 – 40 keV
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-5000
Counts per 15°
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
20 – 40 keV
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-5000
Counts per 15°
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
40 - 60 keV
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-5000
Counts per 15°
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
40 - 60 keV
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-5000
Counts per 15°
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
60 - 80 keV
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Counts per 15°
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
60 - 80 keV
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-5000
Counts per 15°
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
80 - 100 keV
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-5000
Counts per 15°
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
80 - 100 keV
“Background”-subtracted data
X4.8 Flare of 23-July-2002X4.8 Flare of 23-July-2002
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Counts
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Azimuthal Scatter Angle
FLR2072301 : 20 - 40 keV
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Counts
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Azimuthal Scatter Angle
FLR2072301 : 20 - 40 keV
-2000
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Counts
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Azimuthal Scatter Angle
FLR2072301 : 60 - 80 keV
-2000
-1000
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Counts
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Azimuthal Scatter Angle
FLR2072301 : 60 - 80 keV
-2000
-1000
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Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2072301 : 40 - 60 keV
-2000
-1000
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Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2072301 : 40 - 60 keV
-2000
-1000
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Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2072301 : 80 - 100 keV
-2000
-1000
0
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Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2072301 : 80 - 100 keV
Residual Polarization Signal
X4.8 Flare of 23-July-2002X4.8 Flare of 23-July-2002
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Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2072301 : 20 - 40 keV
χν2 ( ) = 3.32polar
χν2 ( ) = 9.46line
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Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2072301 : 20 - 40 keV
χν2 ( ) = 3.32polar
χν2 ( ) = 9.46line
-2000
-1000
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Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2072301 : 40 - 60 keV
χν2 ( ) = 3.90polar
χν2 ( ) = 3.88line
-2000
-1000
0
1000
2000
Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2072301 : 40 - 60 keV
χν2 ( ) = 3.90polar
χν2 ( ) = 3.88line
-2000
-1000
0
1000
2000
Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2072301 : 60 - 80 keV
χν2 ( ) = 1.72polar
χν2 ( ) = 1.67line
-2000
-1000
0
1000
2000
Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2072301 : 60 - 80 keV
χν2 ( ) = 1.72polar
χν2 ( ) = 1.67line
-2000
-1000
0
1000
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Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2072301 : 80 - 100 keV
χν2 ( ) = 0.62polar
χν2 ( ) = 0.92line
-2000
-1000
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Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2072301 : 80 - 100 keV
χν2 ( ) = 0.62polar
χν2 ( ) = 0.92line
Residual Polarization Signal
X1.5 Flare of 21-April-2002X1.5 Flare of 21-April-2002
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Counts per 5 sec Time Bin
01:05 01:10 01:15 01:20 01:25
Time (UT)
FLR204210120 - 40 keV
FLR BGD1 (24 hrs before) BGD2 (24 hrs after)
3000
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Counts per 5 sec Time Bin
01:05 01:10 01:15 01:20 01:25
Time (UT)
FLR204210140 - 60 keV
FLR BGD1 (24 hrs before) BGD2 (24 hrs after)
3000
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Counts per 5 sec Time Bin
01:05 01:10 01:15 01:20 01:25
Time (UT)
FLR BGD1 (24 hrs before) BGD2 (24 hrs after)
FLR204210160 - 80 keV
3000
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Counts per 5 sec Time Bin
01:05 01:10 01:15 01:20 01:25
Time (UT)
FLR204210180 - 100 keV
FLR BGD1 (24 hrs before) BGD2 (24 hrs after)
Analysis Interval : 1:12 – 1:18 UT
X1.5 Flare of 21-April-2002X1.5 Flare of 21-April-2002
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-100
-200
Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2042101 : 20 - 40 keV
400
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0
-100
-200
Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2042101 : 40 - 60 keV
400
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0
-100
-200
Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2042101 : 60 - 80 keV
400
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0
-100
-200
Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2042101 : 80 - 100 keV
Residual Polarization Signal
X1.5 Flare of 21-April-2002X1.5 Flare of 21-April-2002
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-100
-200
Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2042101 : 20 - 40 keV
χν2 ( ) = 0.42polar
χν2 ( ) = 0.37const
400
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200
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0
-100
-200
Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2042101 : 20 - 40 keV
χν2 ( ) = 0.42polar
χν2 ( ) = 0.37const
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-100
-200
Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2042101 : 40 - 60 keV
χν2 ( ) = 0.77polar
χν2 ( ) = 0.60const
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0
-100
-200
Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2042101 : 40 - 60 keV
χν2 ( ) = 0.77polar
χν2 ( ) = 0.60const
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Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2042101 : 60 - 80 keV
χν2 ( ) = 0.99polar
χν2 ( ) = 1.05const
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0
-100
-200
Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2042101 : 60 - 80 keV
χν2 ( ) = 0.99polar
χν2 ( ) = 1.05const
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0
-100
-200
Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2042101 : 80 - 100 keV
χν2 ( ) = 2.09polar
χν2 ( ) = 1.58const
400
300
200
100
0
-100
-200
Counts
360°300°240°180°120°60°0°
Azimuthal Scatter Angle
FLR2042101 : 80 - 100 keV
χν2 ( ) = 2.09polar
χν2 ( ) = 1.58const
Residual Polarization Signal
X3.9 Flare of 03-November-2003X3.9 Flare of 03-November-200335000
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25000
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15000
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0
Counts per Time Bin
09:45 09:50 09:55 10:00
Time (UT)
FLR311031620 - 40 keV
FLR BGD1 (24 hrs before) BGD2 (24 hrs after)
35000
30000
25000
20000
15000
10000
5000
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Counts per Time Bin
09:45 09:50 09:55 10:00
Time (UT)
FLR311031640 - 60 keV
FLR BGD1 (24 hrs before) BGD2 (24 hrs after)
35000
30000
25000
20000
15000
10000
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0
Counts per Time Bin
09:45 09:50 09:55 10:00
Time (UT)
FLR311031660 - 80 keV
FLR BGD1 (24 hrs before) BGD2 (24 hrs after)
35000
30000
25000
20000
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10000
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Counts per Time Bin
09:45 09:50 09:55 10:00
Time (UT)
FLR311031680 - 100 keV
FLR BGD1 (24 hrs before) BGD2 (24 hrs after)
Analysis Interval : 9:48 – 9:53 UT
X3.9 Flare of 03-November-2003X3.9 Flare of 03-November-2003
6000
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Counts
360300240180120600
Azimuthal Scatter Angle
FLR3110316 : 20 - 40 keV
6000
4000
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0
Counts
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Azimuthal Scatter Angle
FLR3110316 : 20 - 40 keV
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1000
500
0
-500
-1000
Counts
360300240180120600
Azimuthal Scatter Angle
FLR3110316 : 40 - 60 keV1500
1000
500
0
-500
-1000
Counts
360300240180120600
Azimuthal Scatter Angle
FLR3110316 : 40 - 60 keV
1500
1000
500
0
-500
-1000
Counts
360300240180120600
Azimuthal Scatter Angle
FLR3110316 : 60 -80 keV1500
1000
500
0
-500
-1000
Counts
360300240180120600
Azimuthal Scatter Angle
FLR3110316 : 60 -80 keV
1500
1000
500
0
-500
-1000
Counts
360300240180120600
Azimuthal Scatter Angle
FLR3110316 : 80 - 100 keV1500
1000
500
0
-500
-1000
Counts
360300240180120600
Azimuthal Scatter Angle
FLR3110316 : 80 - 100 keV
Residual Polarization Signal
X3.9 Flare of 03-November-2003X3.9 Flare of 03-November-2003
6000
4000
2000
0
Counts
360300240180120600
Azimuthal Scatter Angle
FLR3110316 : 20 - 40 keV
χν2 ( ) = 3.55polar
χν2 ( ) = 3.82const
6000
4000
2000
0
Counts
360300240180120600
Azimuthal Scatter Angle
FLR3110316 : 20 - 40 keV
χν2 ( ) = 3.55polar
χν2 ( ) = 3.82const
1500
1000
500
0
-500
-1000
Counts
360300240180120600
Azimuthal Scatter Angle
FLR3110316 : 40 - 60 keV
χν2 ( ) = 1.73polar
χν2 ( ) = 2.12const
1500
1000
500
0
-500
-1000
Counts
360300240180120600
Azimuthal Scatter Angle
FLR3110316 : 40 - 60 keV
χν2 ( ) = 1.73polar
χν2 ( ) = 2.12const
1500
1000
500
0
-500
-1000
Counts
360300240180120600
Azimuthal Scatter Angle
FLR3110316 : 60 -80 keV
χν2 ( ) = 0.82polar
χν2 ( ) = 1.21const
1500
1000
500
0
-500
-1000
Counts
360300240180120600
Azimuthal Scatter Angle
FLR3110316 : 60 -80 keV
χν2 ( ) = 0.82polar
χν2 ( ) = 1.21const
1500
1000
500
0
-500
-1000
Counts
360300240180120600
Azimuthal Scatter Angle
FLR3110316 : 80 - 100 keV
χν2 ( ) = 0.97polar
χν2 ( ) = 1.58const
1500
1000
500
0
-500
-1000
Counts
360300240180120600
Azimuthal Scatter Angle
FLR3110316 : 80 - 100 keV
χν2 ( ) = 0.97polar
χν2 ( ) = 1.58const
Residual Polarization Signal
X2.5 Flare of 10-November-2004X2.5 Flare of 10-November-2004
25000
20000
15000
10000
5000
0
Counts per 5 Sec Time Bin
02:00 02:05 02:10 02:15 02:20 02:25 02:30
Time (UT)
FLR411100220 -40 keV
FLR BGD2 (24 hrs after)
25000
20000
15000
10000
5000
0
Counts per 5 Sec Time Bin
02:00 02:05 02:10 02:15 02:20 02:25 02:30
Time (UT)
FLR411100240 - 60 keV
FLR BGD2 (24hrs after)
25000
20000
15000
10000
5000
0
Counts per 5 Sec Time Bin
02:00 02:05 02:10 02:15 02:20 02:25 02:30
Time (UT)
FLR411100260 - 80 keV
FLR BGD2 (24 hrs after)
25000
20000
15000
10000
5000
0
Counts per 5 Sec Time Bin
02:00 02:05 02:10 02:15 02:20 02:25 02:30
Time (UT)
FLR411100280 - 100 keV
FLR BGD2 (24 hrs after)
Analysis Interval : 2:06 – 2:15 UT
X2.5 Flare of 10-November-2004X2.5 Flare of 10-November-2004
800
400
0
-400
Counts
360300240180120600
Azimuthal Scatter Angle
FLR4111002 : 20 - 40 keV
800
400
0
-400
Counts
360300240180120600
Azimuthal Scatter Angle
FLR4111002 : 40 - 60 keV
800
400
0
-400
Counts
360300240180120600
Azimuthal Scatter Angle
FLR4111002 : 60 -80 keV
800
400
0
-400
Counts
360300240180120600
Azimuthal Scatter Angle
FLR4111002 : 80 - 100 keV
Residual Polarization Signal
X2.5 Flare of 10-November-2004X2.5 Flare of 10-November-2004
800
400
0
-400
Counts
360300240180120600
Azimuthal Scatter Angle
FLR4111002 : 20 - 40 keV
χν2 ( ) = 1.52polar
χν2 ( ) = 1.89const
800
400
0
-400
Counts
360300240180120600
Azimuthal Scatter Angle
FLR4111002 : 20 - 40 keV
χν2 ( ) = 1.52polar
χν2 ( ) = 1.89const
800
400
0
-400
Counts
360300240180120600
Azimuthal Scatter Angle
FLR4111002 : 40 - 60 keV
χν2 ( ) = 1.37polar
χν2 ( ) = 1.36const
800
400
0
-400
Counts
360300240180120600
Azimuthal Scatter Angle
FLR4111002 : 40 - 60 keV
χν2 ( ) = 1.37polar
χν2 ( ) = 1.36const
800
400
0
-400
Counts
360300240180120600
Azimuthal Scatter Angle
FLR4111002 : 60 -80 keV
χν2 ( ) = 1.54polar
χν2 ( ) = 1.98const
800
400
0
-400
Counts
360300240180120600
Azimuthal Scatter Angle
FLR4111002 : 60 -80 keV
χν2 ( ) = 1.54polar
χν2 ( ) = 1.98const
800
400
0
-400
Counts
360300240180120600
Azimuthal Scatter Angle
FLR4111002 : 80 - 100 keV
χν2 ( ) = 1.03polar
χν2 ( ) = 1.18const
800
400
0
-400
Counts
360300240180120600
Azimuthal Scatter Angle
FLR4111002 : 80 - 100 keV
χν2 ( ) = 1.03polar
χν2 ( ) = 1.18const
Residual Polarization Signal
Selected FlaresSelected Flares
11-Nov-2004N8W62
23-Jul-2002 S13E72
03-Nov-2003 N08W77
21-Apr-2002S14W84
X4.8 Flare of 23-July-2002X4.8 Flare of 23-July-2002
20 - 40 keV Polarization
Flare location : S13E72
8000
6000
4000
2000
Counts
360°300°240°180°120°60°0°
Scatter Angle (η)
2072301FLR20-40 keV
µp = 0.10 ± 0.04
Π ≈ 18%Φ = 79° ± 3°
X4.8 Flare of 23-July-2002X4.8 Flare of 23-July-2002
8000
6000
4000
2000
Counts
360°300°240°180°120°60°0°
Scatter Angle (η)
2072301FLR20-40 keV
µp = 0.10 ± 0.04
Π ≈ 18%Φ = 79° ± 3°
8000
6000
4000
2000
0
Counts
360°300°240°180°120°60°0°
Scatter Angle (η)
µp = 0.15 ± 0.06
Π ≈ 27%Φ = 86° ± 2°
FLR207230120-40 keV
(Ge8-Ge3)+(Ge9-Ge5)
8000
6000
4000
2000
0
Counts
360°300°240°180°120°60°0°
Scatter Angle (η)
µp = 0.07 ± 0.05
Π ≈ 13%Φ = 66° ± 4°
FLR207230120-40 keV
(Ge8-Ge6)+(Ge9-Ge4)
X4.8 Flare of 23-July-2002X4.8 Flare of 23-July-2002
8000
6000
4000
2000
Counts
360300240180120600
Scatter Angle (η)
2072301FLR20-30 keV
µp = 0.07 ± 0.04
Π ≈ 12%Φ = 74° ± 3°
8000
6000
4000
2000
Counts
360°300°240°180°120°60°0°
Scatter Angle (η)
2072301FLR20-40 keV
µp = 0.10 ± 0.04
Π ≈ 18%Φ = 79° ± 3°
1400
1200
1000
800
600
400
200
Counts
360300240180120600
Scatter Angle (η)
2072301FLR30-40 keV
µp = 0.33 ± 0.16
Π ≈ 60%Φ = 92° ± 4°
SummarySummary
Addition of a Be scattering block provides HESSI with significant polarimetric capability.
Polarization sensitivity predicted to be less than a few percent for some X-class flares.
First analysis includes four events :
1) 23-July-2002
2) 21-April-2002
3) 03-November-2003
4) 10-November-2004
Only the July 23rd event shows evidence of polarization (at the ~18% level in the 20-40 keV energy range).
In ProgressIn Progress
Draft paper should be ready soon :Draft paper should be ready soon :
description of methoddescription of method
positive results for 23-July-2002positive results for 23-July-2002
null results for 21-Apr-2002, 3-Nov-2003, 10-Nov-2004 null results for 21-Apr-2002, 3-Nov-2003, 10-Nov-2004
Simulations with proper input spectra.Simulations with proper input spectra.
Quantify resultsQuantify results
Time-dependence of July 23rd event.Time-dependence of July 23rd event.
Polarization Measurements with Coronas-FPolarization Measurements with Coronas-F
Uses similar concept for polarization measurements (Be scattering into CsI).
Looked at data from three events:
1) 28-Oct-2003
2) 29-Oct-2003
3) 04-Nov-2003
Polarization detected only for 29-Oct-2003
40-60 keV polarization >75%