Dr. Priscilla Cushman

Well, the lab coat, no.

You'll have to think more about a large miner's coverall and a utility belt and a backpack filled with not only my own stuff I need, but also a self-rescuer that weighs about 20 pounds, marching about a kilometer to get to the lab, actually, at two kilometers below the surface.

Well, basically, we have very, very sensitive detectors, right?

And so they're sensitive to everything.

And that includes the cosmic rays, which are intersecting us and the Earth at all times.

And they get blocked by the Earth between the surface and where the lab is.

But the dark matter particles do not.

because they are so weakly interacting.

Basically, they pass through the earth.

You would count as many of them at night as at day because they can just come through the other side of the earth any way they want.

But it is moving quite fast because not so much that it is moving fast, but that we are moving fast through it as we move around the sun and as our solar system moves around our galaxy.

Yeah, it's more to think of it that way, because the relative motion is all that counts, because we're having detectors that measure the kinetic energy of the particles.

And so from our point of view, it's like this dark matter wind that's moving through our detectors.

But only one in a trillion actually gets close enough to one of our target atoms to move the nucleus a tiny bit.

And that's why we have a hard time seeing it, although there's so much of it.

So what we're looking for is an interaction between a dark matter particle and a nucleus.

Our target material, for example, are crystals of germanium or silicon.

The target material

exist to be interacted with, if you like.

So we have all of this collection of nuclei and the dark matter particles are moving through and they have to be very close to the nucleus to make an interaction.