1. IDEE, The Electron Spectrometer of the Taranis Mission J.-A. Sauvaud 1, A. Fedorov 1, P. Devoto 1, C. Jacquey 1, L. Prech 2, Z. Nemecek 2, F. Lefeuvre 3 1 CESR-U. Of Toulouse-CNRS 2 Charles University, Prague 3 LPCE, CNRS, Orléans Workshop on Coupling of Thunderstorms and Lightning Discharges to Near-Earth Space 23-27 June 2008, Corte, France

2. Charged particle W= 3.5 eV/e - -hole pair The spectrometer uses semi-conductors as particle detectors (an electron crossing a semi-conductor generate pairs of e-holes. A pair is produced for each 3.5 eV lost. The energy lost is measured)

3. PARTICLE ENVIRONMENT AT 700 KM ALTITUDE (200 keV) DEMETER DATA

4. IDEE conception 3 objectives: - Pitch-angle Distribution of Radiation Belt Electrons -Relativistic Runaway Electrons (RRE) -Lightning-induced Electron Precipitation (LEP)‏

5. Can IDP (DEMETER) do that? Relativistic Runaway Electrons (RRE) Not enough Geometrical Factor Lightning-induced Electron Precipitation (LEP)‏ Energy range and time resolution not adequate Pitch-angle Distribution of Radiation Belt Electrons No angular channels

6. Two spectrometers, 735 cm 3 each One looking upward, the other downward IDEE TARANIS Silicon matrix Energy range : 70 keV – 350 keV CdTe matrix Energy range : 350 keV – 4 MeV

7. Objectif - Runaway Relativistic Electrons Possible RRE spectrum (Red)‏ Where we can distinguish a RRE spectrum from the bkg electrons. (After DEMETER data)‏

8. Runaway Relativistic Electrons Possible RRE spectrum (Red)‏ Detection of RRE 8 horizontal bands, 8 CdTe cells in each thickness 6mm to stop electrons up to 4 Mev

9. Runaway Relativistic Electrons Possible RRE spectrum (Red)‏ An Al foil (0.65mm width) protects the sensor from low energy particles

10. Runaway Relativistic Electrons CdTe detector Geometrical Factor GEANT-4 simulation with real design An Al foil (0.65mm) protects the sensor From low energy particles

11. Objectif - Lightning induced electron precipitation (DEMETER - above Europe: weak energy, critical time resolution of electron data ) DEMETER

12. Lightning-induced Electron Precipitation Example of LEP measurements E = 30 - 200keV A Si detector is located ahead of the CdTe to measure moderate fluxes and (weak) energies of precipitated electrons. Expected flux: 8 10 4 s -1 in 200 ms bursts

13. Radiation belt detector: Si central cell For strong fluxes of radiation belt electrons, the only central part of the silicium is used.

14. The resulting IDEE sensor for TARANIS

15. Can we provide measurements at high latitudes? Demeter electron flux

16. Geant-4 simulations Can we provide measurements in high latitude regions? Yes, we can Spectrometer simulation Spectra provided by the Si central cell and by the central cell in Coincidence with CdTe are not saturated

17. Response to RRE event Geant-4 simulation 20 counts/event Measurable signal for CdTe only

18. Expected response to RRE event Geant-4 simulation20 counts/event Time profile of modeled flux during an event, Noise below 1 count/5ms ( < 200) CdTe

19. Response to associated Gamma rays Geant-4 simulation when gamma only are received, the measured signal is very weak. Gammas will not disturbed electron measurements.

20. STATUS OF THE EXPERIMENT Sensor head design: performed Electronic design: performed. ASIC under development DPU design: performed (Charles university) Modes: defined Burst trigger: ready Thermal study: under way