A Measurement Scheme of Anisotropy from quasi-2D to True 2D with EAS array

Current observations of the two-dimensional (2D) anisotropy of cosmic rays in the GeV-PeV energy remain inadequate. In the TeV-PeV energy, ground-based experiments can only precisely measure the anisotropy along the right ascension (RA) direction within individual declination(DEC) bands; the precision across different DEC bands is insufficient for precise measurements. In the GeV-TeV energy, space-based experiments provide only upper limits. For ground-based array, Earth's rotation causes the detectors to sweep uniformly across DEC bands, ensuring consistent detection efficiency across RA directions. This enables high-precision measurement of the relative intensity variation in RA directions. However, no analogous natural scanning mechanism exists for the DEC direction. To address this limitation, this paper proposes a novel rotating ground-based array scheme. By rotating the detector array, the RA scanning principle is extended to cover the full two-dimensional RA-Dec plane, enabling true-2D anisotropy measurement. This approach simultaneously allows for precise determination of the array's detection efficiency for cosmic rays arriving from different directions. Notably, space-based experiments inherently function as rotating platforms. Therefore, the analysis methods developed in this study are expected to be directly applicable to satellite data.