In October 2024, I was on a review committee for the Sanford Underground Research Facility (SURF) and they gave us a tour of the future home of the DUNE experiment. This post shows how one accesses the mine and what it looks like 4850 ft below the Black Hills.

You can learn more about SURF and DUNE here:

https://sanfordlab.org

https://www.dunescience.org

View from the hotel at dawn. The Black Hills are gorgeous!
Walking to the administration building at SURF. SURF is located in the Homestake Gold Mine (now inactive) and has inherited the mine’s historic buildings.
The Ross hoist. We’re going to take this down into the mine. https://sanfordlab.org/news/how-it-works-yates-hoistroom has a description of how it works.
You have to put on a coverall and hard hat with a light. (Rolf Heuer)
Inside the cage for our descent. Around 15 people are in the cage. Our group and some geologists from PNNL.
After about 5 minutes we reach the 4850 ft level. The rails are for a tiny train that moves between the Ross Campus (where we are) and the Davis Campus (where the LZ experiment is).
This is what the cage looks like once you get out. People only travel in one of the 3 segments. The others are for material (in this case trash).
We head over to the DUNE area. First enormous cavern on your right.
Here is one of the 2 large halls for the DUNE far detectors. It is hard to grasp the scale without people. That equipment down there is BIG!.
It’s easier to get an idea of the scale from the utility hall that lies between the 2 detector halls. It is the same area but not as deep.
Another view of the Utility Hall
The little brass disk in the floor is where the center of the beam from Fermilab is supposed to be.

Now we get in the train to go to the Davis Campus and see the LZ experiment.
On the train
Its a bit dark in spots.
Even darker. Those LED lights are a huge improvement over the bad old days when you just had your lantern on your hard hat.
We have to clean our boots and then change our of our dusty coveralls to go into the Davis Campus as it needs to be kept clean.
Entrance to the Majorana demonstrator clean room.
The LZ experiment is inside this large tank.
More LZ.
The espresso machine.
Back near the DUNE halls we get to see a new excavation.
More of the new excavation. This is a bypass so that new construction won’t affect DUNE.
And we head back up.
Special bonus. Chocolate!
In case they are closed, you can buy chocolate from a vending machine.