Particle accelerator fits on the head of a pin | Hacker News Reader

Particle accelerator fits on the head of a pin

techcrunch.com

87 pointsrbanffy40 comments

From the standpoint of particle physics, these aren’t that exciting. Though you would never know it from the article, the electric fields in these things are about the same as the fields in existing accelerators, because they’re both limited by the fact that strong fields start ripping the thing apart. So they wouldn’t actually “shrink” particle accelerators at all. They’re 1,000 times smaller than the existing cells, but you would need 1,000 times more of them to get the same effect.

The intended application isn't particle physics: "These won’t be rivaling macro-size accelerators like SLAC’s or the Large Hadron Collider, but they could be much more useful for research and clinical applications where planet-destroying power levels aren’t required. For instance, a chip-sized electron accelerator might be able to direct radiation into a tumor surgically rather than through the skin."

So that's a step towards particle weapons, right? :).

I'm only half-joking here. In my copious spare time, I sometimes wonder how one could approach building something resembling a phaser. The most recent question I've added to my "to investigate" list is, is there a way of sending energy (either as photons or via larger particles) that would avoid scattering off targets? Scattering is a problem with lasers - if you take one that's powerful enough to be interesting and use it in enclosed space, you'll get everyone in the room not wearing eye protection blind before the target starts to heat up.

A particle canon that can accelerate a gas with good directional control (that can be aimed and focused) with sufficient energy to cause damage to an object 5m away will probably be better applied as deep space propulsion than as a weapon.

It's a bit like a space invasion - if you plan on invading another planet, just accelerate for the first part of the trip, point the engine to the destination and fire it for the rest of the trip. When you arrive, there will probably be no armies, of lifeforms, to resist you.

OTOH, you may need to wait a couple million years before the planet is cool, or inhabitable again.

Seems like it would take an obscene amount of fuel to heat a planet, and taking a detour through kinetic energy shouldn't change that fact.

Yes. It also takes an obscene amount of energy to get something as heavy as an invasion force as far as another planet in a reasonable timeframe. There’s also the energy you gain (or have to dissipate) from the final descent.

Call me nuts, but I’m more interested in propulsion than weapons.

A torchship?

http://www.projectrho.com/public_html/rocket/torchships.php

Might be simpler just to accelerate a small un-crewed ship to approach the speed of light, and strike the planet with it as a kinetic weapon (causing an extinction event but not enough to actually disintegrate the planet). Closely following behind can be a slower ship containing the colonizing party. Then there won't be a need to heat up the target planet.

1. Throw out the garbage before hitting the brakes.

2. Garbage hits planet at relativistic speed.

3. Profit.

Why slow down at all?

https://military.wikia.org/wiki/Relativistic_kill_vehicle

"I'm only half-joking here. In my copious spare time, I sometimes wonder how one could approach building something resembling a phaser."

Well, we're getting there. We do have laser rifles, though they're a little pathetic compared to an AR-15.

Dunno man you can buy some really wack lasers off of ebay:

https://www.youtube.com/watch?v=-BeTq99LqUo

They were talking about this kind of particle accelerator in the 90s back when I used to hang out with accelerator physicists. Though back then it was going to be terahertz waves rather than lasers. Still got to power it with something.

IMO best mad scientist weapon is something like this: https://en.m.wikipedia.org/wiki/MARAUDER

Holy moly, those are $60 new on ebay.

Wow! They were successfully testing plasma rail guns that delivered an equivalent of 5 tons of TNT per hit in 1993 before it went classified!

5 pounds, not 5 tons.

Wow. The MARAUDER sounds like the kind of weapon you would only find in a modern installment of Command & Conquer in an alternate timeline of history.

Command & Conquer had several Marauders

Not the same tech, unfortunately.

It hit with the energy of 5lbs of tnt. There are thousands of weapons out there with thousands of times that power.

The in-game incarnation doesn't have to be as weak as the real-life one. It could be based on the same technology, but with a fantastically higher fire power. Because fiction.

What about masers? The atmosphere should be fairly transparent in that frequency range so no need to worry about scattering, and the wavelength is short enough so you don't have to worry too much about near field effects.

I'm less worried about scattering off air, than I'm worried about scattering off the thing it hits. I'd like the energy to be deposited only to the material at the focus of the device (and whatever it then convects to).

Beyond obvious military application, imagine this as an alternative to laser engravers and cutters that would need no light-absorbing enclosure and light-absorbing glasses.

I see two possibilities, depending on what you want.

1) Dust — anything in the range 1mm to 1nm, depending on what properties you want it to have. Give it a small electric charge and accelerate it conventionally, perhaps in a vacuum with a plasma window at one end.

2) A relativistic beam of something that quickly decays in a way that doesn’t emit much EM radiation. (Would muons fit this description? I don’t know, I’m relying on what Wikipedia says).

I see. Well with high enough laser intensities the back reflection portion plateaus due to plasma formation [0], while the specular reflection portion could probably be minimised with a suitable prepulse[1,2] to pattern the surface. That said, the reflected intensity is probably still going to be pretty high, so I guess laser weapons are probably best reserved for long range combat.

[0] https://pureadmin.qub.ac.uk/ws/portalfiles/portal/124726142/... [1] https://www.ncbi.nlm.nih.gov/pubmed/21935245 [2] https://www.sciencedirect.com/science/article/pii/S016943321...

Don't give a switchblade to a monkey!

You might enjoy these speculative articles about proton beams:

"Particle Beams and Saucer Dreams" https://www.otherhand.org/home-page/area-51-and-other-strang...

"So ya don’t believe it was a proton beam, eh?" https://www.otherhand.org/home-page/area-51-and-other-strang...

In Artemis Fowl, the Neutrino weapons used by the faeries are not actually neutrino ray guns, but a substance called HCSP (High Conductivity Soft Polymer) which conducts electricity. It is charged with varying levels of electricity while leaving the gun, and dissolves upon impact at high enough velocity while imparting its electrical charge into the target.

Wouldn't work well against dry kevlar, but I suppose you just bring the right tools for the job. I think it's worth exploring polymers, though a dissolvable polymer sounds like microplastic hell.

> Sapra et al. developed an integrated particle accelerator using photonic inverse design methods to optimize the interaction between the light and the electrons. They show that an additional kick of around 0.9 kilo–electron volts (keV) can be given to a bunch of 80-keV electrons along just 30 micrometers of a specially designed channel.

A lot less exiting than techcrunch says, but I wouldn't know why I expected better.

The exciting part of this is the gradient. The addition of 1keV in 30um is huge!

For reference, in a typical electron microscope, accelerating fields might reach a 1 MeV/m gradient. In these cases, it's usually an anode (-200kV) and cathode (0V) closely separated. High vacuum is required, it's large, power supplies are enormous, etc.

Scaling the results of this paper, especially after a working prototype, will be more interesting to the general population. But the key discoveries are already here. Scaling becomes an engineering concern.

So what’s stopping us from being able to convert energy to mass with a particle accelerator? Shouldn’t it be possible to get a particle of equivalent mass-energy to the energy concentrated by an accelerator? So like amp up an electron to 106 MeV and get a muon-on-demand?

Well, muons are made by getting electrons or other particles up to high speeds and then crashing them into stationary targets or counterrotating beams. But you have to create muon-antimuon pairs, so that requires at least 212 MeV in theory and much more in practice because of energy lost to heat, etc. https://www.fnal.gov/pub/today/SpecialROW032808MERIT.html

Per google, you have to have a collision because of the law of conservation of momentum otherwise won’t allow for pair production. It’s an open question how we get a universe of matter out of seemingly only producing mass energy in matter/anti-matter symmetry. Sounds like a sure Nobel prize for that one, too.

Is there any reason they couldn't chain a whole bunch together to kick up to higher energy levels? Say you need 50um per segment for the support framework and whatnot, you could pack 200 of them in a cm long instrument and kick up the power by 200keV?

Oh yes, that's what I would anticipate.

The design shown in this paper is specific to an initial electron energy of 83keV. That means that chaining identical parts wouldn't work, but you could have an array of similar parts with slightly different properties at each "stage".

900V/30μm is likely to be very useful indeed. At that gradient, the threshold for positron-electron pair production is about 34mm, which is small enough I can — for example — imagine it being built into a surgical instrument specifically intended to be pushed into a tumour.

As I am not a biologist, I have no idea if that is actually a useful way to deal with tumours, but regardless of the specifics I definitely expect it to enable things that are not currently practical.

two questions immediately coming to mind:

1. can one build a viable rocket engine out of an array of these? if it runs on IR, can one reuse the heat it generates to improve its own efficiency?

2. can one build a handheld/mounted particle beam weapon with these?

This was done for molecular beams too, at MPI Göttingen and FHI some years ago.

Original paper: https://sci-hub.se/https://doi.org/10.1126/science.aay5734

Anyone have a non-Verizon source? I refuse to use a site with obfuscation and anti-patterns in their privacy options.

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