Progress of the Jinping Underground Nuclear Astrophysics ( JUNA) Experimental Platform

This article reviews the development and achievements of the Jinping Underground Nuclear Astrophysics ( JUNA) experimental platform and focuses on the direct measurement of reaction rates inside or near the Gamow window in deep-underground astrophysical experiments. It discusses the advantages of conducting experiments in the deep-underground environment of the China Jinping Underground Laboratory (CJPL), which provides significant shielding from cosmic rays along with milliampere-level intensity from the JUNA accelerator. This shielding and high intensity are crucial for accurately measuring very-low-cross-section nuclear reactions essential to understanding astrophysical processes, such as the synthesis of heavy elements in stars from neutron sources and CNO cycle leakage. The manuscript also covers technological achievements, including advancements in ion sources, accelerators, detectors, and targets used in the JUNA experiment. The physics results from these experiments provide valuable data for key reactions, such as neutron source reactions and radiative capture reactions, as well as for the production of heavy elements in early stars. Future plans for the JUNA experiment are also outlined.