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Outline Description of GSEM HEP Range Telescope Radiation in Space GEANT4 Simulation

GSEM project SPENVIS/GEANT4 Workshop, Leuven, Belgium, 3 - 7 October 2005 Daniel Haas, DPNC Gen è ve. Outline Description of GSEM HEP Range Telescope Radiation in Space GEANT4 Simulation Outlook & Conclusions. The GSEM project….

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Outline Description of GSEM HEP Range Telescope Radiation in Space GEANT4 Simulation

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  1. GSEM projectSPENVIS/GEANT4 Workshop, Leuven, Belgium, 3 - 7 October 2005Daniel Haas, DPNC Genève Outline Description of GSEM HEP Range Telescope Radiation in Space GEANT4 Simulation Outlook & Conclusions

  2. The GSEM project… • General Space Environment Monitor:Multi-Purpose Detector to monitor critical environmental data, like: • Radiation (High Energy Particle Sensor) • Vibration • Debris • Plasma/Discharge SPENVIS & GEANT4 Workshop, Leuven, October 2005, Page 2

  3. …The GSEM project… • ESA/ESTEC contract 10619/04 • Collaborators: • Contraves Space, Zürich (SREM) • Vibrometer, Fribourg • DPNC, Université de Genève • Prof. Martin Pohl, Prof. Divic Rapin, Dr. Daniel Haas, Denis Rosset • Phase A finished • Phase B ongoing SPENVIS & GEANT4 Workshop, Leuven, October 2005, Page 3

  4. …The GSEM project • Key Issues: • Very light: Central Unit and HEP sensor ~ 1 kg • Low Power:Central Unit and HEP sensor ~ 1 Watt • Modular:Easy integration of other sensor systems SPENVIS & GEANT4 Workshop, Leuven, October 2005, Page 4

  5. The HEP Sensor System……what was existing • Jan 2005: ESA Workshop on Ionizing Particle Measurements in Space: • Future Technology Priorities: • High fidelity energetic particle telescopes (EPT…) • Sub-kg general particle spectral monitors (GSEM)incl. miniaturized dose rate monitors • Problems of existing Monitors: • Poor separation of electrons, protons and ions • Measurement of deposited energy only  Difficulties in data interpretations SPENVIS & GEANT4 Workshop, Leuven, October 2005, Page 5

  6. The HEP Sensor System……what do we need • HEP sensor system of GSEM should provide: • e/p separation of 1 in 10-3 • Measure incoming particle energy with good fidelity and multiple bins • Data needs to be corrected for dead time, channel and particle cross-feed  Simplified data interpretation SPENVIS & GEANT4 Workshop, Leuven, October 2005, Page 6

  7. The HEP Sensor System……Revised Design Requirements by ESA • Distinguish electron/proton/ion • Measure incoming particle energy Measure E and dE/dx • Energy ranges: • Electrons: 120 keV - 7 MeV • Protons: 3 MeV - 300 MeV • Ions: 1 - 70 MeV/cm2/mg • Viewing angle at least  20o • Sampling rate: 500 kEvents/s with dead time correction SPENVIS & GEANT4 Workshop, Leuven, October 2005, Page 7

  8. The HEP Sensor System……Design Approach • Range Telescope with: • Measured quantities: • Range • dE/dx in all layers • Stack of silicon PIN diodesand absorber layers • Size determined by rateabout 2 cm diameter • Full digital readout • Active veto outside • Passive shield around Veto Shielding Veto SPENVIS & GEANT4 Workshop, Leuven, October 2005, Page 8

  9. The HEP Sensor System……Geometry • 6 layers of sensors: • 1st layer 2 sensors of 50 m and 300 mwith coincidence • Other layers 300 m • Increasing absorber-thickness: • 10 m (pinhole), 200 m (ring) • 0.8 mm, 1.6 mm, 3.2 mm, 6.4 mm, 12.8 mm • Protons will straggle to stop • Electrons often have large angle scatters SPENVIS & GEANT4 Workshop, Leuven, October 2005, Page 9

  10. The HEP Sensor System……Geometry Detector Sideview • 10 electronsgoing throughthe detector • Multiple scattering • Photonsproduced e-  SPENVIS & GEANT4 Workshop, Leuven, October 2005, Page 10

  11. Radiation in Space……expected maximum fluxes PROTONS ELECTRONS SPENVIS & GEANT4 Workshop, Leuven, October 2005, Page 11

  12. Radiation in Space……expected LET rates for 1 cm2sr, 1mm Al • Helium:5 Hz - 15/day • Iron:0.07 Hz - 2/month • Iron shoulder 2•105 MeV/g/cm20.014 Hz - 4/year • Higher rates need much bigger surfaces Covered range p He p He Fe Fe SPENVIS & GEANT4 Workshop, Leuven, October 2005, Page 12

  13. GEANT4 Simulation……Geometry • Full geometry implemented • 6 mm Al-shield around active veto for low E particles • Height of detector adjustable 2 cm SPENVIS & GEANT4 Workshop, Leuven, October 2005, Page 13

  14. GEANT4 Simulation……Setup • 2 versions of simulation: • ‘Old’ Simplified geometry,  20o input,200 kEvents, flat spectrum, ROOT-histograms • Full geometry, full angle, 1 MEvents, ROOT-trees(available since mid september) • Most plots still with ‘old’ simulation • Detailed analysis with ‘new’ simulation currently ongoing (angular acc., veto-counters, power-law spectrum) SPENVIS & GEANT4 Workshop, Leuven, October 2005, Page 14

  15. GEANT4 Simulation……Particle separation • Total E shown • Protons very clean Protons Electrons SPENVIS & GEANT4 Workshop, Leuven, October 2005, Page 15

  16. GEANT4 Simulation……Proton binning < 80 MeV • 5 bins by range in 1st 5 layers (3-80 MeV) • Excellent separation for range bins • Basically no cross-feed between energies SPENVIS & GEANT4 Workshop, Leuven, October 2005, Page 16

  17. GEANT4 Simulation……Proton binning > 80 MeV • High E bins by total dE/dx • 4 bins from 80 to 300 MeV • Good separation, easy unfolding of the small cross-feed • Last bin above 300 MeV as veto SPENVIS & GEANT4 Workshop, Leuven, October 2005, Page 17

  18. GEANT4 Simulation……Electron binning • 6 electron bins: • 5 bins by range in 1st 5 layers, as for protons • Reasonable separation in E, unfolding needed • Last bin as veto for E > 14 MeV SPENVIS & GEANT4 Workshop, Leuven, October 2005, Page 18

  19. GEANT4 Simulation……Electron/Proton separation • Good separation between electrons and protons/ions • Misidentification p  e: < 6•10-5 at highest energy • Misidentification e  p: 10-3 (low E) 10-2 (high E) Color = Energy bins High E Low E Electrons SPENVIS & GEANT4 Workshop, Leuven, October 2005, Page 19

  20. GEANT4 Simulation……New Plots (ongoing) • Expected Angular Acceptance  20o • Crosscheck with simplified geometry show same behaviour dE/dx unchanged Preliminary Full angle In sensor 1 No veto SPENVIS & GEANT4 Workshop, Leuven, October 2005, Page 20

  21. Outlook & Conclusions • Range telescope shows convincing performance from simulation • Good e/p separation • Spectra with reasonable binning • Easy interpretation of proton spectra • Simple unfolding for electrons needed • Phase A finished, Phase B close to completion • Fine tuning of simulation • Building of prototype detector will start 2006 • Sensor samples already in our hands, will be tested soon on probe station SPENVIS & GEANT4 Workshop, Leuven, October 2005, Page 21

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