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Neutrino tomography of Earth

nature.com

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Re: Neutrino tomography of Earth

#11

Post by njarboe »

not2b wrote: post #6
gpuhacker wrote: post #5

Earlier quoted context omitted.

An in space detector is (at least to my understanding) not that easy, as you need the surface of the Earth to interact with the neutrinos. These interactions result in muons, which allow to detect that there was a neutrino in the first place. Also, there is a pretty big source for neutrinos pretty close to Earth, but Earth is in its orbit, as opposed to the other way around.

The IceCube neutrino detector consists of about a cubic kilometer of ice. You're not going to put one of those in orbit.

But it would make a cool joint project for NASA and the NSF to fund. Capture a comet big enough that you could mine enough water to make a cubic kilometer sized detector in Earth orbit.

Re: Neutrino tomography of Earth

#12

Post by logfromblammo »

gpuhacker wrote: post #8
not2b wrote: post #6

Earlier quoted context omitted.

The IceCube neutrino detector consists of about a cubic kilometer of ice. You're not going to put one of those in orbit.

Exactly

You might be able to tow it in from elsewhere using a light sail, however. Beyond our current technology, but might be doable by 2100, or sooner with a fortuitous comet trajectory.

Re: Neutrino tomography of Earth

#13

Post by Balgair »

Supplementary Figure 6 is pretty cool! There seems to be a lot of strange things happening at the mantle-crust boundary that will take some further study to understand.

All said, this is a MAJOR advance in our understanding of the Earth and the science thereof. This technique should allow for some pretty amazing things in the future.

Re: Neutrino tomography of Earth

#16

Post by lootsauce »

InclinedPlane wrote: post #10
phkahler wrote: post #3

Would it be feasible to put a source and detector in orbit so we could get high resolution CT images of the interior of the earth? IIRC the detector used here is very large, but there are smaller ones and a directed source would go a long way towards making the detection simpler.

Neutrino detection generally requires large volumes and large masses (for very large values of "large"), neither of which are as yet feasible for space based systems. The IceCube neutrino observatory, for example, makes use of a volume of ice that is on the order of a cubic kilometer (over 900 million tonnes). Suffice it to say, building cubic kilometer solid structures in space that weigh hundreds of millions of ton…

Could we not just land a detector on the far side of the moon. Thats pretty large no?

Re: Neutrino tomography of Earth

#17

Post by phinnaeus »

lootsauce wrote: post #16
InclinedPlane wrote: post #10

Earlier quoted context omitted.

Neutrino detection generally requires large volumes and large masses (for very large values of "large"), neither of which are as yet feasible for space based systems. The IceCube neutrino observatory, for example, makes use of a volume of ice that is on the order of a cubic kilometer (over 900 million tonnes). Suffice it to say, building cubic kilometer solid structures in space that weigh hundreds of millions of ton…

Could we not just land a detector on the far side of the moon. Thats pretty large no?

Each detector has a limited range. And only works well in certain mediums, generally water or water ice. Even if the Moon was solid ice, we would need to surround it with detectors, as well as drill a huge number of holes all the way through it and place detectors (probably hundreds of thousands or millions) in each hole.

Re: Neutrino tomography of Earth

#18

Post by pvg »

lootsauce wrote: post #16
InclinedPlane wrote: post #10

Earlier quoted context omitted.

Neutrino detection generally requires large volumes and large masses (for very large values of "large"), neither of which are as yet feasible for space based systems. The IceCube neutrino observatory, for example, makes use of a volume of ice that is on the order of a cubic kilometer (over 900 million tonnes). Suffice it to say, building cubic kilometer solid structures in space that weigh hundreds of millions of ton…

Could we not just land a detector on the far side of the moon. Thats pretty large no?

It is but you need both a big hunk of mass and a way to detect the neutrino interactions inside it. Ice Cube is shot through with detectors. One of the OG detectors measured the particular isotope created during interactions.

https://en.wikipedia.org/wiki/Homestake_experiment#Methodolo...

The Super-Kamiokande has photomultipliers staring at a bunch of water looking for Cherenkov radiation resulting from neutrino interactions

https://en.wikipedia.org/wiki/Super-Kamiokande

None of these are much of a practical option with the moon.

Re: Neutrino tomography of Earth

#19

Post by bacon_waffle »

jboggan wrote: post #2

This is really brilliant, literally jaw-dropping. I was really blown away by the idea and construction of the detector itself and this application is astounding. https://en.wikipedia.org/wiki/IceCube_Neutrino_Observatory

My favourite story about the construction of IceCube relates to the drilling of the holes to deploy the detector. They used two types of drill, which melt the firn (compacted snow) on top and ice lower down. One is a sort of conical heat exchanger, the other circulates water through a Big water heater on the surface.

In the early days of South Pole Station (late 1950s), supplies were airdropped in - the cargo planes of that era couldn't land on the snow and going overland was very difficult. Many of the parachutes wouldn't open properly, and so lots of supplies (including a bulldozer) and parachutes wound up buried in the snow. South Pole slowly accumulates snow, so that debris has gotten deeper and deeper below the surface over time.

Of course, the holes required to build IceCube had to go deeper than those supplies, but the drill can't go through things that don't melt, so in some cases the holes had to be moved off the nominal grid. According to the story I heard, one of the holes ran in to a bunch of meat, which floated to the top of the bore...

Re: Neutrino tomography of Earth

#20

Post by InclinedPlane »

lootsauce wrote: post #16
InclinedPlane wrote: post #10

Earlier quoted context omitted.

Neutrino detection generally requires large volumes and large masses (for very large values of "large"), neither of which are as yet feasible for space based systems. The IceCube neutrino observatory, for example, makes use of a volume of ice that is on the order of a cubic kilometer (over 900 million tonnes). Suffice it to say, building cubic kilometer solid structures in space that weigh hundreds of millions of ton…

Could we not just land a detector on the far side of the moon. Thats pretty large no?

You need to have the reaction mass to make use of. Most neutrino detectors use special chemicals in custom tanks, IceCube uses antarctic ice. You would need not just mass but ice or water for a neutrino detector, ideally highly compressed optically clear ice. The only possible candidate in the Solar System that fits that bill at present is Europa. Though it's possible that similar conditions might also exist on Mars (we know there are sub-surface glaciers, but we don't know how deep they go or how pure the ice is. And potentially some of the large sub-surface oceans (on Ganymede, Enceladus, etc.) might work too but we know even less about their properties.
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