Challenges in the Replacement of Current Gamma Ray Detectors with Readily Available Solid State for the use of Personal Dosimetry

Abstract

The accurate monitoring of ionising radiation exposure is critical for occupational safety in environments where radioactive sources are present. Current personal dosimetry solutions predominantly rely on thermoluminescent dosimeters (TLDs) and electronic personal dosimeters (EPDs). While TLDs provide reliable cumulative dose measurements, they lack real-time feedback. Conversely, EPDs offer real-time readings but are almost universally based on Geiger–Müller (GM) tubes—fragile, high-voltage components developed nearly a century ago and prone to supply chain disruptions.
This research investigates the feasibility of replacing the GM tube with low-cost, mass-produced, and readily available solid-state components for use in personal dosimetry. Four potential detector types were selected for study: PIN photodiodes, light dependent resistors (LDRs), photovoltaic (PV) cells, and supercapacitors. Each device was characterised through simulation using the Monte Carlo N-Particle (MCNP) transport code and verified experimentally under controlled gamma radiation conditions. Performance was evaluated across sensitivity, energy response (both compensated and uncompensated), isotropic response, and temperature stability.
The results demonstrate that certain commercially available PIN photodiodes exhibit a linear response to gamma radiation with energy and angular dependencies comparable to compensated GM tubes, indicating strong potential as viable replacements in low-cost EPDs. LDRs and PV cells showed measurable but less linear responses, suggesting possible use in specialised or hybrid detection configurations. Supercapacitors did not exhibit signs of detectible radiation-induced leakage effects.
This study concludes that readily available solid-state components—particularly PIN photodiodes—can provide a robust, scalable, and cost-effective alternative to traditional GM tube–based dosimeters, paving the way for new designs of affordable, real-time personal radiation monitors.

Date of Award	18 Dec 2025
Original language	English
Awarding Institution	Northumbria University
Supervisor	Rick Binns (Supervisor) & Wai Pang Ng (Supervisor)