1. Cross-Calibration Meeting ESTEC, February 2006
CIS Calibration Adjustments and Inter-Calibrations Iannis Dandouras (1), Claire Vallat (2), Lynn M. Kistler (3), and the CIS Team 1Centre d’Etude Spatiale des Rayonnements, Toulouse, France 2ESA/ESTEC RSSD, Noordwijk, the Netherlands 3University of New Hampshire, NH, USA
Cross-Calibration Meeting ESTEC, February 2006

2. Ion Composition and Distribution Function Analyser
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
Includes also an RPA: ~ eV/e (wrt spacecraft potential)
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. CIS Modes Data Compression Modes Solar Wind Modes RPA Mode
Magnetospheric Modes

5. CODIF Solar Wind Modes
Reduced Energy-Sweep when High-Sensitivity side facing the Solar Wind
( 45° in azimuth over 360° )
Either side is selectable by command, the two sides are mutually exclusive
 check from which side of the instrument the data are coming from

6. CIS Instrument Status Rumba Salsa Samba Tango
* 1
* 2
* 1 : Not operational since 25 Oct. 2004
* 2 : to be switched ON

7. All CIS Calibration files for years 2001 and 2002 delivered to CAA
ASCII files, self-documented (including comments) : machine-readable and human-readable
Include also calibration files catalogue: pointer to which calibration files to use for each time period (detection efficiency evolution)
Files updated regularly
All CIS Calibration files for years 2001 and 2002 delivered to CAA

8. HIA (CIS-2) : Pre-flight Calibrations
Relative efficiency and solid angle for each anode
Energy-dependent efficiency coefficients
Analyser K, Da, DE/E
Attenuation grid, MCP area, MCP dead times
MCP grid potential
G - factors (for the High Sensitivity Side and the Low Sensitivity Side)

9. HIA (CIS-2) : Density Calculation
Geometric factor
Efficiency
Counting Rate

10. HIA (CIS-2) : Velocity Calculation

11. HIA (CIS-2) Calibration Files Updating
Updating the calibration files for the detection efficiency evolution, with respect to the pre-launch calibrations, is a multi-step process. The HIA density values are compared and cross-calibrated with the density values supplied by the Whisper sounder experiment:
in the Magnetosheath (High Sensitivity Side)
in the Solar Wind (Low Sensitivity Side)
Outside these regions in some cases the HIA and Whisper supplied densities may not agree, due to factors such as the presence of plasma outside the HIA energy range, or operation of the instrument in an inappropriate mode (e.g. High Sensitivity Side operation in the Solar Wind).

12. HIA Calibration Files Updating (cont.)
HIA - Whisper cross-calibrations: adjustment of the effective Geometric factor only (  G)
Cross-anode calibrations:
Checking the isotropy of the response
Checking the velocity direction in the Solar Wind (Low Sensitivity Side) and in the Magnetosheath (High Sensitivity Side)
Until now not any adjustment of the cross-anode calibrations: pre-launch relative anode efficiencies still valid.

13. HIA (CIS-2) Status : MCP High Voltage Evolution

14. HIA (CIS-2) : Calibration Status
MCPs in good shape.
MCP efficiencies stabilised: very slow evolution since 2003.
Calibration files updated several times: step function introduced.
HIA calibration updates performed by Claire Vallat (initially at CESR, now at ESTEC).
HIA calibrations have been independently analysed by Jim McFadden (SSL, Berkeley): confirmed values.
Most recent calibration update : September 2005 [C. Vallat]
Calibration updates implement in the calibration files: valid until November 2003.

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

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

17. CODIF (CIS-1) : Pre-flight Calibrations
Energy-dependent relative efficiency for each anode and for each of the main ion species (H+, He++, He+, O+)
Analyser K, Da, DE/E
Post-acceleration potential
G - factors (for the High Sensitivity Side and the Low Sensitivity Side)
RPA potentials and G - factor
For each ion species detected (H+, He++, He+, O+), the detection efficiency is given by :
Eff(PF, E, m) = (M0 + M1*E + M2*E2 + M3*E3 ) * Abs_Eff
M0 .. M3 : efficiency calibration coefficients, depending on the ion mass m (4 sets), and on the detection anode PF
E : total ion energy (ion energy + post-acceleration energy)
Abs_Eff : absolute efficiency (one value for the HS side and one value for the LS side)

18. CODIF (CIS-1) Calibration Files Updating
The CODIF calibrations updating is a more complex process. It involves (Abs_Eff for each ion species):
the determination of the start-MCP efficiency
the stop-MCP efficiency
the fraction of coincidences between the “start” and the “stop” signal that also have a single position signal, allowing thus to calculate the total efficiency [Lynn Kistler]

19. CODIF Calibration Files Updating (cont.)
In addition, the efficiencies of the individual anodes (M0 to M3 coefficients for each 22.5° sector) have to be cross-calibrated, and this is performed by using time periods when the ion distributions are expected to be gyrotropic.
CODIF calibrations involve also separate efficiencies determination for H+ and O+ ions.
The CODIF H+ measurements are finally cross-checked with the HIA measurements, for periods when the plasma is composed mainly from H+ ions, and neither instrument saturates or has low counting statistics.

20. CODIF (CIS-1) Status : Efficiencies
sc1 and sc4 : Slow, graceful efficiencies degradation on these spacecraft.
CODIF - sc4
MCP HV raise
Single Event Rate (SFR + 1 position) / Start-Stop Coincidence Rate

21. CODIF (CIS-1) Status : Efficiencies
sc 4
sc 1

22. CODIF (CIS-1) Status : Efficiencies
sc 3

23. CODIF (CIS-1) Status : Efficiencies
sc3: One MCP quadrant (southward looking directions on the High-Sensitivity side) suffers from substantially decreased detection efficiency.  Reduced accuracy of CODIF data on sc3. Boundary identification however possible.
sc3
sc4
Calibrations meaningless for these « almost dead » anodes of sc3

24. CODIF (CIS-1) Status : MCP High Voltage Evolution

25. CODIF (CIS-1) : Calibration Status
Calibration files updated several times: step function introduced.
Most recent calibration update : July (valid until Oct. 2004): Lynn Kistler.
Efficiency evolution much more complex than for HIA.