Direct nn-scattering at the YAGUAR reactor

The Direct Investigation of ann Association (DIANNA) is finalizing the design of a direct measurement of the nn-scattering length to be performed at the YAGUAR reactor in Snezhinsk, Russia. Extensive modeling of the neutron field, nn-scattering kinematics, and sources of detector background have verified the plan for a 3% measurement of ann. Measurements of the neutron flux support the neutron field modeling. Initial test measurements of the neutron field inside the underground channel have confirmed calculations of the thermal neutron background.