Forest detectors

The forest as a neutrino detector: "We explore in this article the feasibility of using the forest as a detector. Trees have been shown to be efficient broadband antennas, and may, without damage to the tree, be instrumented with a minimum of apparatus. A large scale array of such trees may be the key to achieving the requisite target volumes for UHE neutrino astronomy."

Your first impression might be to wonder what the author's dreams are like.

However, the idea isn't completely crazy. Presumably because of fluid in the living trees, they conduct electricity at some level. Therefore they can act as antennas for radio waves, and in fact this was studied by the military at one point. They tried driving nails into the tree and hooking receivers to wires attached, and also tried winding coils of wire around the trunk. Both actually worked, though the latter worked better.

OK, now the next question is why one would care. Answer: At high enough energies neutrinos do not zip through everything almost without interacting--they actually do interact, generally creating a lepton in the process, which does interact, generally with showers of other particles. Lots of them. Enough that their current, in the Earth's magnetic field, produces radio waves. You can detect those radio waves, and with an array of antennas figure to detect their timing, you can figure out the track of the shower--and therefore the initial cosmic ray.

Getting an idea of where this is going?

There are some technicalities--you want to detect showers that seem to be coming up out of the Earth, or out of a mountain, to try to filter out things other than neutrinos interacting very near the surface. But the general idea is that the patterns of radio waves corresponding to such particle showers can be pieced out of the general radio background. This is already being done successfully in several different experiments.

The bulk of the hardware cost of such an experiment is in the radio antennas, the electronics to read them out, and the labor to do it. If the antennas are already standing around, there's some savings already. Plus, trees are tall, so they'd help pick up lower frequency radio waves.

Another advantage to using trees is that you don't need to find a bare spot to put up your antennas, so you've got more choices for locations. And you don't have to lug a lot of heavy gear around to places that may not always be easy to get to.

Downsides... The electronics costs the same, and is a substantial part of the total. One guy said it cost more than the antennas--he was probably thinking about short antennas, though, not tree-sized. Also you can predict the sensitivity of a steel antenna--how do you calibrate the radio wave sensitivity of jackpine number 88-K?

And, we wonders, aye we wonders, what the wildlife will think of tasty wires strung here and there in the woods. In the planning for the SSC designers realized that fire ants would colonize their electrical distribution boxes, and nibble.