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Description
The Stereo ECal consists of elongated scintillator strips arranged at alternating stereo angles in adjacent layers. This configuration provides three-dimensional spatial information while limiting the number of readout channels, making it a candidate design for a highly granular calorimeter at the CEPC. In this study, the spatial and angular reconstruction performance of a six-layer Stereo ECal prototype was evaluated using cosmic-ray data and an external tracking system. A parallax-free reconstruction method based on measurements perpendicular to the scintillator strips was developed for the multilayer stereo geometry, enabling the reconstruction of three-dimensional particle trajectories. Comparisons with external reference tracks yield spatial resolutions of approximately $3.50\mathrm{mm}$ and $10.86\mathrm{mm}$ in the two transverse directions at the center of the prototype, together with an azimuthal angular resolution of approximately $3.14^\circ$. These measurements include contributions from the external tracking system and residual alignment uncertainties. The results demonstrate the capability of the stereo-strip geometry to reconstruct both particle positions and directions, providing an experimental basis for further optimization and development of the Stereo ECal for the CEPC.
