An improved imaging technique to analyze the tail of the pion emission source

Abstract: Previous imaging techniques have shown that pion-emitting sources produced at RHIC exhibit a prominent non-Gaussian tail,which may be attributed to the analysis being performed in the center-of-mass frame of the pion pair (CMFP) rather than the source frame (CMFS).To eliminate this frame-dependent effect, we propose an improved imaging technique that operates directly in the CMFS. Unlike conventional methods that rely on selecting pion pairs based on energy differences in CMFP, our technique performs the analysis in a single CMFS frame, eliminating the need to reconstruct source parameters from multiple CMFP frames.This approach reduces kinematic correlations and provides a more physically consistent imaging result. We validate our method by comparing the imaging results with real source functions extracted from models, demonstrating a significant reduction in the non-Gaussian tail and a closer match to the model's source morphology.