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Science and Discovery

Going deep for science

Deep underground, far from the reach of cosmic rays, scientists are working on experiments that may answer fundamental questions about how the universe was formed.
Scientists at work underground

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Cosmic rays from space

Cosmic Shower

High energy cosmic radiation is constantly bombarding the surface of the earth. If you hold out your hand in this shower, one or two cosmic rays will pass through it every second. This radiation is harmless to you and me but scientists looking for rare and specific interactions need a place free of this cosmic noise to build sensitive detectors.

Cosmic Rays hit the earth at Sanford Lab

Blocking cosmic rays

The overburden of rock acts as a shield against all the unwanted cosmic radiation that showers the surface of the Earth. Going nearly a mile underground reduces the cosmic noise for sensitive physics experiments by a factor of 10 million. 

Lead bricks protect experiment from radiation

Even more shielding

But trace amounts of radiation exist everywhere. Small amounts of uranium and thorium exist within the rock. Even our own bodies are fantastically radioactive. Scientists surround their experiments with water, lead and other materials to protect them these trace amounts of radioactive materials.

Feet below the surface

Most of the experiments at Sanford lab are at the 4850-foot level. 
Not all underground labs are created equal. Depth and rock density play an important role in how well cosmic rays are blocked out. We need a consistent way to measure cosmic ray attenuation in underground labs.

Meters of water equivalent

In physics we measure the amount shielding an underground lab provides in meters of water equivalent (m.w.e.). In other words—how deep would water have to be to provide the same amount of shielding from muons. The Sanford Lab is rated at 4,300 m.w.e., for comparison the average depth of the ocean is 3,682 meters.
Scientist working underground

It's quiet down here

Remember, at the surface one or two cosmic rays go through your hand every second. But on the 4850 Level you could wait more than 3 months before a single cosmic ray event occurs. With all this cosmic noise virtually eliminated, scientists can build super sensitive detectors that look for rare events. The goal is to catch rare interactions of neutrinos and dark matter.

These experiments are designed to see what the universe is made of, to understand how it was made and to find out why matter—stuff like stars, planets and even us—exist.