Progress of Underground Nuclear Astrophysics Experiment JUNA in China.

JUNA measured the SP 19 sp F(p, ) SP 16 sp O channel down to the lowest energy of E SB c.m. sb 72 keV, and the JUNA rate deviates significantly from the previous expectations by a factor of 0.2-1.3 [[21]]. Thanks to the advantages provided by CJPL, the Jinping Underground Nuclear Astrophysics (JUNA) experiment collaboration has proposed to exploit the extremely low background and try to reach the Gamow region in CJPL-II A1 Hall (see Figure 1) [[9]]. Previously, this reaction was thought to be weak compared to the SP 19 sp F(p, ) SP 16 sp O reaction, so most of the SP 19 sp F produced by the CNO cycle would be recycled back into SP 16 sp O, with no substantial chemical abundance changes. The background mainly consists of the neutron-induced background from SP 13 sp C( ,n) SP 16 sp O reaction and the gamma background from other ( , ) reactions, making the analysis complicated. [Extracted from the article]