IDEE, The Electron Spectrometer of the Taranis Mission

J.-A. Sauvaud1, A. Fedorov1, P. Devoto1, C. Jacquey1,

L. Prech2, Z. Nemecek2, F. Lefeuvre3

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

Charged particle

W= 3.5 eV/e--hole pair

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

PARTICLE ENVIRONMENT AT 700 KM ALTITUDEPARTICLE ENVIRONMENT AT 700 KM ALTITUDE(200 keV)(200 keV)

DEMETER DATA

IDEE conceptionIDEE conception

3 objectives:3 objectives:

-Pitch-angle Distribution of Radiation Belt Electrons

-Relativistic Runaway Electrons (RRE)

-Lightning-induced Electron Precipitation (LEP)

Can IDP (DEMETER) do that?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

Two spectrometers, 735 cmTwo spectrometers, 735 cm33 each eachOne looking upward, the other downwardOne looking upward, the other downward

IDEE TARANISIDEE TARANIS

Silicon matrix Energy range : 70 keV – 350 keV

CdTe matrix Energy range : 350 keV – 4 MeV

Objectif - Runaway Relativistic Objectif - Runaway Relativistic ElectronsElectrons

Possible RRE spectrum (Red)

Where we can distinguish a RRE spectrum from the bkg electrons.

(After DEMETER data)

Runaway Relativistic ElectronsRunaway Relativistic Electrons

Possible RRE spectrum (Red)Detection of RRE8 horizontal bands, 8 CdTe cells in eachthickness 6mm to stop electrons up to 4 Mev

Runaway Relativistic ElectronsRunaway Relativistic Electrons

Possible RRE spectrum (Red)An Al foil (0.65mm width) protects thesensor from low energy particles

Runaway Relativistic ElectronsRunaway Relativistic Electrons

CdTe detector Geometrical FactorGEANT-4 simulation with real design

An Al foil (0.65mm) protects the sensor From low energy particles

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

DEMETERDEMETER

Lightning-induced Electron PrecipitationLightning-induced Electron Precipitation

Example of LEP measurements E = 30 - 200keV

A Si detector is located ahead of the CdTeto measure moderate fluxes and (weak) energies of precipitated electrons. Expected flux: 8 104 s-1 in 200 ms bursts

Radiation belt detector: Si central cellRadiation belt detector: Si central cell

For strong fluxes of radiation belt electrons, the only central part of the silicium is used.

The resulting IDEE sensor for TARANISThe resulting IDEE sensor for TARANIS

Can we provide measurements at high latitudes?Can we provide measurements at high latitudes?

Demeter electron flux

Geant-4 simulations

Can we provide measurements in high latitude regions?Can we provide measurements in high latitude regions?

Yes, we can

Spectrometersimulation

Spectra providedby the Si centralcell and by thecentral cell in Coincidence withCdTe are not saturated

Response to RRE eventResponse to RRE event

Geant-4 simulation20 counts/event

Measurable signalfor CdTe only

Expected response to RRE eventExpected response to RRE event

Geant-4 simulation20 counts/event

Time profile ofmodeled fluxduring an event ,Noise below 1 count/5ms ( < 200)

CdTe

Response to associated Gamma raysResponse to associated Gamma rays

Geant-4 simulation

when gamma onlyare received, the measured signal isvery weak.

Gammas will notdisturbed electronmeasurements.

STATUS OF THE EXPERIMENTSTATUS 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