The neutron and photon beam dump
The beam dump of the nELBE setup consists of a cylindrical block of borated polyethylene surrounded by a 0.5 mm thick layer of Cd and a 7.5 to 10 cm thick Pb shielding. The layout is shown in the picture below (all dimensions are given in units of cm).
The Pb shielding is taken from the former "Big NaJ" spectrometer of the Ruhr-Universität Bochum . The borated polyethylene was fitted into the passive shielding of this spectrometer. The back side is made from conventional Pb bricks. A hole of 10 cm diameter was drilled into the polyethylene to move the point of first interaction to an optimal position.
 L. Ricken, "Der Strahlungseinfang schwerer Ionen - Intermediäre Strukturen und der Zerfall von Riesenresonanzen", Dissertation, Bochum 1988