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Results from the GIOVE-A CEDEX Space Radiation Monitor

Results from the GIOVE-A CEDEX Space Radiation Monitor. B Taylor 1 , C Underwood 1 , H Evans 2 , E Daly 2 , G Mandorlo 2 , R Prieto 2 , M Falcone 2 Surrey Space Centre, University of Surrey, UK ESA/ESTEC/TEC-EDD, NL 3 rd European Space Weather Week Brussels, Belgium, 13-17 November 2006.

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Results from the GIOVE-A CEDEX Space Radiation Monitor

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  1. Results from the GIOVE-A CEDEX Space Radiation Monitor B Taylor1, C Underwood1, H Evans2, E Daly2, G Mandorlo2, R Prieto2, M Falcone2 Surrey Space Centre, University of Surrey, UK ESA/ESTEC/TEC-EDD, NL 3rd European Space Weather Week Brussels, Belgium, 13-17 November 2006

  2. Outline • The CEDEX instrument • Results and model comparisons • Heavy Ion LET spectrum • Proton Flux • Ionising Dose rate • Conclusions 3rd European Space Weather Week

  3. CEDEX • Resources: <2.2 kg (including radiation shielding), <4.5W • Heritage: Surrey’s CRE Payloads • KITSAT-1, PoSAT-1, AMSAT-OSCAR-40 • Measure Proton flux (45-50 MeV) and ion LET spectra • Combined proton and ion telescope employing large-area (3cm x 3cm) PIN diodes • Ion LET values binned into 512 linearly spaced channels • 32 to >10,000 MeV cm2 g-1. • Measure ionising dose-rate induced photocurrents • Dose-rate-induced photocurrents measured in dome shielded PIN photodiodes (provides electron data) • Four shielding depths: 2mm Al, 4mm Al, 2mm Cu, 4mm Cu • Calibrated at QinetiQ’s REEF facility 3rd European Space Weather Week

  4. CEDEX 3rd European Space Weather Week

  5. Heavy Ion LET Spectrum • Flux is assumed to be over 4p with 1cm uniform shielding. ±5mm deviation produces a maximum error of 20% at high LET for the model predictions. • The background flux as measured by CEDEX matches the shape of the CREME86 model spectrum, with the interplanetary weather index set to take into account Galactic cosmic rays and the fully ionised component (i.e.: CREME86 M=2) and the 90% worst case cosmic ray level (i.e.: CREME86 M=3). • The majority of the spectrum lies between the M=2 and M=3 CREME86 models. • Further investigation is required to establish true flux through the telescope. 3rd European Space Weather Week

  6. Heavy Ion LET Spectrum CEDEX measured Heavy Ion LET Spectrum for January to September 2006 compared to CREME86 3rd European Space Weather Week

  7. Proton Flux • Awaiting full analysis • Contamination from a particles and other heavy Ions • Proton Events • Single event associated with M2 solar flare 3rd European Space Weather Week

  8. GRAS modelling • GEANT-4 Radiation Analysis for Space- GRAS • Instruments can be easily modelled using gdml files • Range of analysis packages • Range of energetic particles 3rd European Space Weather Week

  9. Dose Rate Photodiodes –Short Term • Belt transits • Sensitive to Electrons • Clearly visible in Aluminium shielded domes • Detected in Copper shielded domes at high activity • Shape due to peak differing in L shell 3rd European Space Weather Week

  10. Dose Rate Photodiodes –Short Term • AE-8 Predicted Dose rates • >1 MeV Electrons modelled • Assumes spectrum is constant • Worst day 2mm Al diode saturates • Observed dose rates more confined than model predictions 3rd European Space Weather Week

  11. Dose Rate Photodiodes –Long Term • Long Term Dose Rate • Highly variable • Clear 27 day periodicity in early 2006 • Fair match to model predictions • 2mm Al Shielded diode saturates during large event in April 3rd European Space Weather Week

  12. Dose Rate Photodiodes –Long Term • Average Dose Rate • Flight data is a fair match to GRAS modelling • 2mm Al diode has lower dose rate than expected • Due to saturation and sub-threshold data • Derived dose rate from linear relationship between 2mm & 4mm Al diodes 3rd European Space Weather Week

  13. Dose Rate Photodiodes –Long Term • Geomagnetic activity and Dose rate • Large dose rates observed after Geomagnetic Storms • Geomagnetic Storms triggered by interaction with Coronal Holes 3rd European Space Weather Week

  14. Conclusions • The GIOVE-A CEDEX instrument is working well. • The heavy ion LET environment is in reasonable agreement with the LET spectrum produced by CREME86. • The Proton environment is quiet with a single small event occurring • The MEO dose environment is observed to be highly variable, especially due to Geomagnetic storms associated with coronal holes • Initial GRAS modelling using the AE-8MIN model indicates a fair match to flight data in the longer term 3rd European Space Weather Week

  15. Thank You Questions? 3rd European Space Weather Week

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