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HIA: Instrument and Calibrations Iannis Dandouras

HIA: Instrument and Calibrations Iannis Dandouras. HIA-WHISPER Cross-Calibration Meeting ISS, Bucharest, January 2009. Introduction : The CIS Experiment. CODIF (CIS-1) Ion Composition and Distribution Function Analyser

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HIA: Instrument and Calibrations Iannis Dandouras

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  1. HIA: Instrument and Calibrations Iannis Dandouras HIA-WHISPER Cross-Calibration Meeting ISS,Bucharest, January 2009

  2. Introduction : The CIS Experiment • CODIF (CIS-1) • Ion Composition and Distribution Function Analyser • 3D ion distributions with mass-per-charge composition determination • ~0 – 40 keV/e Energy Range • HIA (CIS-2) • Hot Ion Analyser • 3D ion distributions with high angular resolution • 5 eV/e – 32 keV/e Energy Range

  3. CIS Dynamic Range Solar wind Magnetosheath Lobe

  4. ZA CIS-2 (HIA) ZA 

  5. Detector Plane Spin Plane HIA Solar Wind Modes • Both sensitivity sides can supply data simultaneously • Solar Wind Energy-sweep Tables (1 out of 9 possible) when low-sensitivity side facing the Solar Wind (45° in azimuth over 360°) • Full Energy-sweep when looking away of the Solar Wind (2  135° in azimuth over 360°) • Reduced Energy-Sweep when High-Sensitivity side facing the Solar Wind (45° in azimuth) • Moments come from the 45°  45° centred in the Solar Wind direction, low-sensitivity side  Under-sampled distributions in the Magnetosheath when in a Solar Wind Mode

  6. HIA (CIS-2) Detection Efficiency • For HIA the detection efficiency is given by : • Eff ( PF, E)-1 = Norm_Q * Eff (E) * Cheff(Q) *[ 1 / T(E) ] • E : ion energy • Norm_Q: Anode normalisation coefficients (one value for the HS and one for the LS side) • Eff (E) : Energy-dependent efficiency term, given by Eff (E) = A * E + B(A, B : linear coefficients, one for the HS and one for the LS side) • Cheff(Q) : Anode - dependent efficiency coefficients • T(E) : MCP energy-dependent efficiency, given by T(E) = T0 + T1*(E+Eg) + T2*(E+Eg)2(Eg : MCP grid acceleration energy) • Total: 2 + 4 + 32 +3 = 41 efficiency calibration coefficients per validity period per spacecraft • In addition: gE : energy-independent geometric factor (one for the HS sideand one for the LS side)

  7. HIA Efficiency Coefficients at the start of the mission

  8. HIA Efficiency Coefficients at the start of the mission

  9. HIA (CIS-2) Onboard Calibration Principle (approx. once per year) MCP HV needs to be increased MCP HV is adequate

  10. HIA (CIS-2) Onboard Calibration Operations:February - March 2008

  11. HIA (CIS-2) Onboard Calibration Operations:February - March 2008

  12. 2007 data, sc1 & sc3 - HIA, plasma sheet:anode response, corresponding to elevation of arriving particles Homogeneous anode response in an isotropic plasma

  13. CODIF sc4 H+ Anode Efficiencies Before efficiencies adjustment After efficiencies adjustment Dayside Plasma Sheet

  14. HIA (CIS-2) Status :MCP High Voltage Evolution Latest MCP HV increase: Feb. 2007

  15. HIA Status :Discriminators Level Evolution

  16. HIA Status :Effective Geometric Factor Evolution (wrt. Start of the mission) Most recent calibrations file update performed in September 2005, by Claire Vallat

  17. HIA – WHISPER Cross-Calibrations • Since 2005 the HIA efficiency values are to be divided by: • sc1 HS:    0.94 • sc1 LS:    1.21 • sc3 HS:    0.98 • sc3 LS:    1.15 • These values are preliminary. • Current efficiencies are reduced to about 77% of the initial HIA detection efficiencies on sc1, and are almost the same as the initial ones for HIA on sc3. (Physical degradation of the MCPs is in reality higher, but it is in some extent compensated by applying increased high voltages on the MCP plates). HIA densities before correction by 0.94 HIA densities before correction by 0.94

  18. HIA Calibration: LS side (Solar Wind)Comparison with the density derived from Whisper C. Vallat HIA density slightly below whisper density 2001 JAN 15 HIA density slightly above whisper density 2001 FEB 23

  19. HIA Calibration: HS side (Magnetosheath) Comparison with the density derived from Whisper S/C1 S/C3 C. Vallat 2001 JAN 14 HIA density slightly below WH. density 2001 FEB 23 HIA density slightly above WH.density HIA saturation (SW)

  20. Masson et al., 2008

  21. HIA (CIS-2) : Calibration Status • MCPs in good shape. • MCP efficiencies stabilised: very slow evolution since 2003. • Latest slight rise of the MCP HV on sc1 and sc3 in Feb. 2007. • Calibration files updated several times: step function introduced. • Most recent calibration update : September 2005 [C. Vallat]. • Since then efficiency values to be corrected by 2 % (sc3, HS) to 21 % (sc1, LS): new calibration files to be prepared. • Actual efficiencies are reduced to about 77% of the initial HIA detection efficiencies on sc1, and are almost the same as the initial ones for HIA on sc3. (Physical degradation of the MCPs is in reality higher, but it is in some extent compensated by applying increased high voltages on the MCP plates ).

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