Title: A Research Agenda for Nuclear Astrophysics Measurements Underground


Precise data on nuclear reaction cross sections is needed to advance understanding in several areas of physics. Current problems in solar neutrino studies, Big Bang Nucleosynthesis, solar physics (refining the Standard Solar Model), galactic chemical evolution, stellar evolution and nucleosynthesis would all benefit greatly from more precise measurements of key reaction cross sections. We will discuss the motivation for measuring several reactions. It is preferable to perform these measurements at stellar energies, meaning very low reaction rates in some cases. An underground research facility allows measurements with much lower background rates, yielding data which would be unobtainable with surface facilities. DIANA (Dakota Ion Accelerators for Nuclear Astrophysics) is a collaboration between the Notre Dame, U. of North Carolina, Western Michigan U., and LBNL to build a nuclear astrophysics accelerator facility 1.4 km below ground. DIANA is part of the proposed research at DUSEL to establish a cross-disciplinary underground laboratory in the former gold mine of Homestake in South Dakota. DIANA will consist of two high-current accelerators, a 30 to 400 kV high voltage platform, and a second dynamitron accelerator with a voltage range of 350 kV to 3 MV. As a unique feature, both accelerators are planned to be equipped with either high-current microwave ion sources or multi-charged ECR ion sources producing ions from protons to oxygen. Compared to current astrophysics facilities DIANA could increase the available beam densities on target by at least an order of magnitude: tens of mA on the low energy accelerator and several mA on the high energy accelerator. An integral part of the DIANA project is the development of a high-density super-sonic gas-jet target which can handle these anticipated beam powers. We will describe the DIANA proposal in context with other nuclear astrophysics accelerator efforts worldwide.