LYRA SWENET intro

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LYRA the Lyman-alpha Radiometer onboard PROBA-2
LYRA Tests and Selections
SCSL Meeting Bern 29 Nov - 01 Dec 2006
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Contents

• I. From Model to Configuration
• II. BESSY Campaigns
• a. Flux Linearity
• b. Stability, Drift
• c. LEDs, Dark Current
• d. Spectral Responsivity
• e. Homogeneity, Flatfield
• III. Summary

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I. From Model to Configuration

• Choice of filters Zirconium (150 nm, 300 nm),
  Aluminium, Lyman-alpha (N, XN, VN, and
  combinations thereof), Herzberg,
• Choice of detectors MSMxx (diamond), PINxx
  (diamond), AXUVxx (silicon),
• Tested separately to find transmittance and
  responsivity
• Simulated with TIMED-SEE solar spectra to find
  expected response values and purities
• cf. http//lyra.oma.be/radiometric_model/radiometr
  ic_model.php
• Example high flux Herzberg filter PIN
  detector

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Selected configurations

• filter detector nominal FWHM measured
• 1-1 Ly XN MSM12 121.5 /- nm 116-126 nm
• 1-2 Herzberg PIN10 200-220 nm 197-218 nm
• 1-3 Aluminium MSM11 17-80 nm (1)-2.4, 17-35
  nm
• 1-4 Zr (300nm) AXUV20D 1-20 nm (1)-1.3, 6-15
  nm
• 2-1 Ly XN MSM21 121.5 /- nm 116-126 nm
• 2-2 Herzberg PIN11 200-220 nm 199-219 nm
• 2-3 Aluminium MSM15 17-80 nm (1)-1.4, 17-27
  nm
• 2-4 Zr (150nm) MSM19 1-20 nm (1)-1.3, 6-12
  nm
• 3-1 Ly NXN AXUV20A 121.5 /- nm 116-126 nm
• 3-2 Herzberg PIN12 200-220 nm 198-219 nm
• 3-3 Aluminium AXUV20B 17-80 nm (1)-2.4, 17-35
  nm
• 3-4 Zr (300nm) AXUV20C 1-20 nm (1)-1.3, 6-15
  nm

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Consequence

• All channels individual
• No simple redundancy
• Combined responsivities
• New estimates for response and purity (cf. II d.)

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II. BESSY Campaigns

• NI beamline (40 240 nm, 60 C) July 2005
• Doc. RP-ROB-LYR-0132-NI-July2005
• GI beamline (1 30 nm, 60 C) July 2005
• Doc. RP-ROB-LYR-0132-GI-July2005
• (Final) NI beamline (40 240 nm, 37 C) March
  2006
• Doc. RP-ROB-LYR-0132-NI-March2006
• (Final) GI beamline (1 30 nm, 37 C) March 2006
• Doc. RP-ROB-LYR-0132-GI-March2006

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a. Flux Linearity

• Using different aperture stops, or
• Varying exit slit of monochromator
• Relation fitted (2006) with a function
  IcaPb
• Results almost linear, slightly sub/superlinear,
  sub/superlinear (qualitatively)
• or b1, c0 (quantitatively)

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Results in detail

• NI 2006 GI 2005 NI 2006 GI 2006
• (121.6 nm, 200 nm) (20 nm, 10 nm)
  (121.6 nm, 210 nm, 50 nm) (18 nm,
  10 nm)
• 1-1 MSM slightly sublin. 0.99572
• 1-2 PIN slightly superlin. 1.00656
• 1-3 MSM 0.98565 1.1719, but cgt0
• 1-4 AXUV 1.00155
• 2-1 MSM slightly sublin. 1.03661
• 2-2 PIN slightly superlin. 0.99483
• 2-3 MSM superlinear 1.02234 0.97894
• 2-4 MSM slightly superlin. 1.04009
• 3-1 AXUV almost linear 1.02434
• 3-2 PIN almost linear 0.99529
• 3-3 AXUV sublinear 0.00230 0.99253
• 3-4 AXUV almost linear 1.00064

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b. Stability, Drift

• Shutter was opened and closed every 60 s, then
  every 600 s
• Some additional longer tests were executed
• BESSY 2005 campaigns (60 C) still to be analyzed
  in detail
• LED values, dark current values and 44 C, 50 C
  temperature effects see below
• Example
• Channel 2-1 (Ly XN MSM21) at BESSY NI 2006

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Results (2006) in detail

• start drift stop
• (slow min, almost
  immediate s)
  (tail min, almost immediate s)
• 1-1 MSM slow upward tail
• 1-2 PIN almost immediate (almost) no almost
  immediate
• 1-3 MSM almost immediate, slow upward tail,
  almost immediate
• 1-4 AXUV immediate no immediate
• 2-1 MSM slow upward tail
• 2-2 PIN almost immediate (almost)
  no immediate
• 2-3 MSM slow upward almost immediate
• 2-4 MSM slow upward almost immediate
• 3-1 AXUV (almost) immediate (almost) no almost
  immediate
• 3-2 PIN almost immediate no immediate
• 3-3 AXUV (almost) immediate (almost)
  no (almost) immediate
• 3-4 AXUV immediate no almost immediate

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c. LEDs, Dark Current

• visLED uvLED offset _at_37 C 44 C 50
  C
• 1-1 MSM (0.005) (0.024) 0.001 0.010
• 1-2 PIN 0.004 0.014 0.000 -0.002
• 1-3 MSM (0.100) 0.000, -0.007 0.003 0.010
• 1-4 AXUV -0.004
• 2-1 MSM (0.012) (0.023) 0.001 0.009
• 2-2 PIN 0.015 -0.001 -0.002 -0.005
• 2-3 MSM ((0.016-0.136)) 0.000, -0.008
  0.002 0.007
• 2-4 MSM -0.001
• 3-1 AXUV 0.000? 0.000 0.002 0.008
• 3-2 PIN 0.006 -0.003 -0.005
• 3-3 AXUV (1.059) -0.001, -0.011
  -0.003 -0.005
• 3-4 AXUV -0.014
• All values in nA
• (x) varying around x, ((x-y)) unstable from y
  to x, negative current values due to conversion

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d. Spectral Responsivity

• Filters and detectors measured together
  (channels as configurated)
• Relevant spectral range is tested, with special
  attention to range borders
• V changed to A using appropriate gain resistor
• Corrections for ring current applied
• Example high solar flux simulated with
  measurements of channel 1-1 (Ly XN MSM12) at
  BESSY NI 2006
• How to estimate correction factors?
• Consequences for data levels?

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Expected Signal and Purity

• theorectical min high measured
  min high
• 1-1 MSM 0.139 nA (37) 0.161 nA (44)
  0.240 nA (24) 0.267 nA (30)
• 1-2 PIN 12.75 nA (86) 12.77nA (86)
  12.57 nA (83) 12.59 nA (83)
• 1-3 MSM 0.120 nA (61) 5.264 nA ( 3)
  0.086 nA (58) 4.945 nA ( 3)
• 1-4 AXUV 0.530 nA (99) 15.37 nA (88) 0.699
  nA (100) 19.09 nA (100)
• 2-1 MSM 0.115 nA (39) 0.135 nA (46)
  0.104 nA (21) 0.114 nA (26)
• 2-2 PIN 13.80 nA (83) 13.82 nA (83)
  13.75 nA (84) 13.76 nA (84)
• 2-3 MSM 0.127 nA (73) 3.821 nA ( 6)
  0.074 nA (59) 3.837 nA ( 3)
• 2-4 MSM 0.111 nA (99) 2.878 nA (100)
  0.094 nA (100) 2.772 nA (100)
• 3-1 AXUV 0.132 nA (46) 0.156 nA (54) 0.113
  nA (81) 0.148 nA (84)
• 3-2 PIN 10.20 nA (85) 10.22 nA (85)
  10.15 nA (83) 10.16 nA (83)
• 3-3 AXUV 1.072 nA (75) 34.95 nA ( 6) 1.090
  nA (72) 36.83 nA ( 5)
• 3-4 AXUV 0.530 nA (99) 15.37 nA (88) 0.710
  nA (100) 19.31 nA (100)

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Calibration Factor, Data Levels

• How to estimate the solar signal from the LYRA
  signal?
• LYRA signal purity / area / responsivity
  solar signal
• A m2 A W-1
  W m-2
• \___________________/
• calibration factor
• Example max, high, min flux Channels
  1-1, 1-2, 1-3, 1-4
• Use constant factor, linear dependency on signal,
  knowledge about solar flux?
• Change public data each time when calibration
  factor gets more realistic? Use different data
  levels?

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e. Homogeneity, Flatfield

• Example Channel 2-3 (detector diameter 4.2 mm)
• What consequences will an off-pointing have?

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III. Summary

• Linearity Stability LEDs
  Signal, Purity
• 1-1 MSM -- -
• 1-2 PIN
• 1-3 MSM --- - ? --
• 1-4 AXUV ??
• 2-1 MSM - -
• 2-2 PIN
• 2-3 MSM -- - -? --
• 2-4 MSM - ??
• 3-1 AXUV -
• 3-2 PIN ?
• 3-3 AXUV - ? --
• 3-4 AXUV ??

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Recommendation

• Head 2 should be nominal
• Head 1 should be used once a week
• Head 3 should be used once a month
• depending on the behaviour of LYRA (deterioration
  etc.)