The Lunar Lander Neutron & Dosimetry (LND) Experiment on Chang’E4.

Chang'E4, the Chinese mission to the Moon, launched on December 8, 2018 and landed on the far side of the Moon in the von Karman crater on January 3, 2019. The mission consists of a lander, a rover, and a communication relay. In this presentation we will describe first data from the Lunar Lander Neutron & Dosimetry experiment (LND) which is placed on the lander. LND consists of a stack of 10 segmented Si solid-state detectors (SSDs) which forms a particle telescope to measure charged particles (electrons fom 0.5 MeV to several MeV, protons 8-35 MeV, and heavier nuclei 17-75 MeV/nuc). A special geometrical arrangement allows observations of fast neutrons (and - rays) which are also important for dosimetry and cosmic-ray exposure of lunar soils. Thermal neutrons are measured using a very thin Gd conversion foil which is sandwiched between two SSDs. Thermal neutrons are sensitive to subsurface water and important to understand lunar surface mixing processes. [...