Identical Pion Interferometry from Au + Au Collisions at $$\sqrt {{{s}_{{NN}}}} $$ = 3, 3.2, 3.5, and 3.9 GeV in the STAR Experiment at RHIC

Two-pion interferometry provides access to the spatial and temporal size, shape, and evolution of the sources created in heavy ion collisions, offering strong constraints for theoretical models. In these proceedings, we will report the measurement of correlation strength ( $$\lambda $$ ) and femtoscopic radii ( $${{R}_{{{\text{out}}}}}$$ , $${{R}_{{{\text{side}}}}}$$ , $${{R}_{{{\text{long}}}}}$$ , $$R_{{{\text{out}} - {\text{long}}}}^{2}$$ ) extracted from the two-pion correlation function in Au + Au collisions at $$\sqrt {{{s}_{{NN}}}} $$ = 3, 3.2, 3.5, and 3.9 GeV. The dependences of these parameters on pair transverse momentum, pair rapidity, collision centrality, and collision energy will be presented, and their physics implications will be discussed.