Hybrid X/β-ray transmission for two-component areal-density reconstruction: a graphite/Si-C electrode study

Two-component areal-density reconstruction from integrated transmission measurements can become ill-conditioned when the constituent materials exhibit strongly correlated radiation responses, particularly for low-Z material pairs. A hybrid X/β-ray transmission method was developed to increase response diversity by combining photon attenuation and β-particle transport within a unified response-matrix framework. Graphite/Si-C electrodes were used as a representative low-Z two-component system. Under the same normalized statistical assumptions, an idealized comparison showed more favorable response separability and conditioning for the hybrid configuration than for the idealized dual-energy X-ray benchmark. Polychromatic Monte Carlo simulations further identified calibration-state transfer and Cu-thickness variation as important practical constraints and indicated 9-10 kV as a suitable operating region for the present system, with 9 kV selected for experimental evaluation. Measurements on a roll-to-roll-compatible platform, using a 0.1 s integration time per channel acquisition, yielded repeated-measurement standard deviations below 0.1 g/m² and reconstruction root-mean-square error (RMSE) values of approximately 1 g/m² for both components. Comparable accuracy was retained after excluding calibration points coincident with the test densities. These results demonstrate the feasibility of hybrid X/β-ray transmission for two-component areal-density reconstruction and provide a basis for further evaluation in other material systems through system-specific calibration and validation.