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)
A. Menicucci – Mentor (Space Systems Egineering)
Carlos Granja – Mentor
K.J. Cowan – Graduation committee member (Astrodynamics & Space Missions)
I. Akay – Graduation committee member (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.