A 3D-printed miniature (~1/4 scale) of the so-called “demon core”, the third pit (core) created from Hanford plutonium during the latter stages of WWII. After the Trinity test and the Nagasaki bomb, the third, 6.2-kg Pu pit was used for weapons research at the Los Alamos Laboratory. The diameter of the largest circle on the model is 10 cm. Atomic weapons require a critical size before they will detonate. Experiments were done to confirm calculations of the critical size. In these experiments a screwdriver was used as a wedge to separate the upper segment from the lower. As it was withdrawn, the two pieces came closer together and, from observing the neutron count, the critical size could be determined. On two occasions accidents occurred where the two segments came closer than intended and in each case the experimenters received fatal doses of radiation and died within weeks.
