THORWART AND FECHTER COMMENT: The French army arrived in Haigerloch on Sunday, 22 April 1945, but took no notice of the underground nuclear lab. The war in Germany officially ended on 8 May 1945.
American–British ALSOS forces arrived on Monday, 23 April 1945, with the lab as their target, and soon dismantled it. According to our archive, the photograph in Physics Today showing the dismantling was taken by Samuel Goudsmith, the scientific head of ALSOS, on 24 April 1945. So, this was very near—but before—the official end of the war.
German scientists had removed the uranium cubes and the heavy water from the lab and hidden them before ALSOS arrived. They left only the inner and outer vessels and the graphite block that separated them.
Colonel Boris Pash of ALSOS initially planned to destroy the entire cave. However, local priest Monsignore Marquard Gulde convinced him that the beautiful baroque church on top of the cave would also be destroyed. After ALSOS forces had found and confiscated the heavy water, the uranium, and the inner vessel, Pash agreed to spare the church, possibly because he realized that the lab was too small for any future German nuclear experiments. He ordered a very limited explosion that destroyed the remaining outer vessel within the cave.
The Atomkeller Museum is underground and the original structure is completely preserved—even the hole for the reactor vessel, which now contains a model of the original reactor, as shown in figure 1. Aside from the damaged outer vessel, shown in figure 2 as it appears today in the museum, no evidence of the explosion exists. The museum is open to the public. See http://www.haigerloch.de/keller/EKELLER.htm.