Feasibility of Shielding Correction for Radiation Detectors in LEO
A Geant4 Analysis of Shielding Effects on the Timepix3 Detector aboard OneWeb’s JoeySat
O.K. Van de Sype (TU Delft - Aerospace Engineering)
Alessandra Menicucci – Mentor (TU Delft - Space Systems Egineering)
Carlos Granja – Mentor
Kevin Cowan – Graduation committee member (TU Delft - Astrodynamics & Space Missions)
İklim Gencturk Akay – Graduation committee member (TU Delft - Space Systems Egineering)
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Abstract
Measurements of the space radiation environment in Low Earth Orbit (LEO) are critical for satellite
safety and operations. However, the inherent shielding of a spacecraft alters the incident radiation
field, complicating efforts to reconstruct the true external environment from measurements taken by internal detectors. This thesis investigates the feasibility of developing shielding correction factors for proton radiation measured by a Timepix3 (TPX3) detector.
The research was conducted using the Geant4 Monte Carlo toolkit to model the transport of protons
through a 5 mm aluminium shield. This simulation framework was first validated against data from
ground-based proton accelerator experiments. Empirical models for correcting kinetic energy reduction and particle transmission were then successfully derived from the simulation data.
The validation process confirmed the simulation’s accuracy for high-energy protons (>70 MeV) but
revealed a systematic overestimation of energy loss at lower energies (<40 MeV). The investigation
into applying the correction factors uncovered a more basic limitation: an inherent ambiguity exists
in the relationship between a proton’s deposited energy (𝐸𝑑𝑒𝑝 ) and its kinetic energy (𝐸𝑘𝑖𝑛 ), which prevents a reliable, direct conversion from the detector’s measurements.
It is therefore concluded that while theoretical correction models can be formulated, their practical
application to shielded detector data is impractical due to the main challenge of reconstructing the
incident energy of detected particles.