1. N. Stoffle University of Houston
Simulation of Van Allen Belt and Galactic Cosmic Ray Ionized Particle Tracks in a Si Timepix Detector
N. Stoffle
University of Houston

2. Collaborators Lawrence Pinsky - University of Houston
Anton Empl - University of Arkansas at Little Rock
Son Hoang - University of Houston
Stanislav Pospisil - IEAP
Jan Jakubek - IEAP
Daniel Turecek - IEAP
Zdenek Vykydal - IEAP

3. Timepix Detector Hybrid Pixel Detector Track Imaging
256 x 256 pixel grid
14mm square
300 µm Si
Track Imaging
Charge sharing impacts
Calibration: ToT to Energy

4. LEO Radiation Environment
Trapped Radiation
Galactic Cosmic Rays
Geomagnetic shielding and cusp regions

5. Simulation Method Overview
Produce Input data for Monte Carlo routines
Generate LEO Orbital track data
Gather Particle and Energy data from models for each point in the orbital track
Simulate interaction and energy deposition physics in the Timepix detector
Model charge movement within Silicon layer
Process data and produce track images

6. Orbital Track Generation
SPENVIS Orbit Generator
One minute data
Latitude
Longitude
Altitude B L
Image generated using SPENVIS

7. Trapped Radiation Data
AE8/AP8 data on a one-minute cadence
Each point has spectral data associated
Both electron and protons
Energy Bin Data
Integral Flux
Differential Flux
Image generated using SPENVIS

8. Galactic Cosmic Ray Data
SPENVIS limited to 1/10th orbit for GCR spectra
Average spectra used for high/low shielded regions
Images generated using SPENVIS

9. Data Sampling Generate source data for use in Monte Carlo code
ROOT data structures and tools used
Assume random isotropic field
Impose total flux limits from data sets
Generate a list of particle hits
Orbit location, Species, Energy, Time, Position, and Angle

10. Monte Carlo Simulation
Simplified Detector Geometry
Source data propagated through material
Energy deposition and location (depth/pixel)
Secondaries included
Raw data output requires further processing
Charge collection
Post Processing

11. Charge Movement
Drift and diffusion processes within the Silicon layer impact measurements
Bouchami et al (2011) proposed model for Medipix2 technology
Apply this model to produce modified track pixel mapping

12. Post Processing
Combine tracks within the same acquisition time window into a single frame
Produce results that can mimic hardware acquisition settings
Output files in preferred structure for direct use within Pixelman

13. Current Results Trapped Proton frames
Electrons below 10MeV assumed screened by vehicle shielding
Track structures and frame data sets visible in Pixelman
1 second time window
60 second frame separation

14. Forward Work
Incorporate and Verify charge collection model using heavy ion accelerator measurements
Implement methods for direct estimation of GCR spectra instead of averaged data
Utilize rigidity at given orbital point

15. Summary Robust and flexible track simulation method has been developed
Source input data can be modified as needed
Highly applicable to space radiation dosimetry

16. Thank you