The Figure caption "Dismantling the Last German Atomic Pile" (Physics Today, July 2000, page 35), contains two incorrect statements.
The dismantling of the pile occurred not after the war, but in April 1945, a few weeks before the war ended in Europe.
The cave was not blown up by the American soldiers. The laboratory was dismantled and the utilities disconnected, but the cave as such was not destroyed. According to the recollections of older residents in Haigerloch, the destruction was avoided by a local priest, who persuaded the Americans to refrain from the destruction because an explosion would have also destroyed a medieval church and castle on the cliff above the cave. Incidentally, Heisenberg occasionally played Bach on the organ of that church.
Today, there is a small museum in the cave, with original and reconstructed artifacts. Visitors are most impressed by how unbelievably small and primitive the historic laboratory was, compared to the gigantic and elaborate technology of the Manhattan Project. It looks more like a TinkertoyTM arrangement than something on the forefront of technology at the time; however, if completed, the Haigerloch laboratory would have led to huge sources of energy and the power for enormous devastation!
Otto G. Folberth
Böblingen, Germany
[Editor's note: We contacted Michael Thorwart of the Atomkeller Museum at Haigerloch. He and Egidius Fechter, director of the museum, provided the following detailed information on the dismantling of the German nuclear lab and the fate of the cave that housed it.]
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.
Figure 1. Reconstructed
model reactor in the original
hole, Atomkeller Museum,
Haigerloch, Germany.
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.
Figure 2. Damaged outer
reactor vessel, on display
at the museum.
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.
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