Characterization of Alpha Particle Track Lengths in LR-115 Detectors

We investigate the dependence of the maximum etched track length (Lmax) on alpha-particle energy and incidence angle in LR-115 Type II detectors by combining Geant4 Monte Carlo simulations with controlled chemical etching experiments. The track and bulk etch rates were measured under standardized conditions, yielding VB=2.46±0.05 µm/h and VT=4.36±0.06 µm/h, which imply a critical detection angle of about 56.5o. Simulations covering initial energies between 1 and 5 MeV and incidence angles up to 70o confirm that the maximum etched track length depends quadratically on both energy and angle. We provide empirical parameterizations for Lmax(E,θ), establish energy thresholds for complete track registration within the 12 µm sensitive layer, and validate the angular acceptance predicted by the VT/VB ratio. These findings improve the quantitative calibration of LR-115 detectors and support their application in environmental radon monitoring, radiation dosimetry, and alpha spectrometry. Our results also demonstrate the utility of Geant4-based modeling for refining SSNTD response functions and guiding the design of optimized detector protocols for nuclear and environmental physics research.