SYDNEY J. FREEDBERG JR.
SPACE & MISSILE DEFENSE SYMPOSIUM, HUNTSVILLE, ALA.: Imagine a engineering that could discover roadside bombs together with landmines buried underground, pick out a nuclear warhead from a cloud of decoys miles away, or fifty-fifty fry enemy electronics, potentially disarming those warheads from a distance. Well, physicist William Dent has invented that engineering together with briefed its potential to the Army together with manufacture here. It’s called a neutron beam generator. Dent’s consider is a potential breakthrough for bomb squads together with missile defenses, enthused conference organizer David Mann, a three-star Army general who ran Space & Missile Defense Command hither (SMDC) until his retirement inwards 2016. Despite the Star Trek-esque name, Isle of Mann told me after Dent’s presentation, this is a viable real-world technology, a affair of “when, non if.” An MRAP (Mine-Resistant Ambush-Protected) truck torn apart past times an IED (Improvised Explosive Device)
Dent is already working amongst the Army to explore the low-hanging fruit: detecting buried explosives at a distance. Now, the military machine already uses neutron generators for this, because neutrons easily penetrate most materials (they receive got no electrical accuse to interact amongst together with a lot of volume to arrive at them momentum) but volition halt together with generate a distinctive flare-up of gamma rays when they hitting high-density materials similar explosives. The work amongst electrical flow systems is their arrive at is really short, anywhere from one meter to 20-plus depending on the size of the explosive together with the depth to which it’s buried. Why? Traditional neutron generators shoot off neutrons indiscriminately inwards all directions, the same way a lite bulb emits light. That agency the neutrons spread out rapidly, inwards fact exponentially (specifically, dissever strength at the root past times the foursquare of the distance). Very soon, in that place are every bit good few of them hitting whatsoever detail target to trigger plenty gamma radiations to detect.
Dent’s electron beam generator, however, shoots out all its electrons along the same path, similar a Light Amplification by Stimulated Emission of Radiation beam. (It’s worth noting that getting neutrons to business upward obediently similar this is an extraordinary achievement inwards physics; to a greater extent than on that below). As a result, the let on of neutrons hitting the target stays high fifty-fifty at a distance. Just how far depends on the ability you lot position inwards together with the character of your aiming system.
How long a arrive at is Dent talking about? “Many, many kilometers,” he told me together with some other reporter after his presentation. The private neutrons cross that distance at a respectable xiv per centum of the speed of light, nigh 94 1 grand m miles per hour. And that’s amongst a organisation of manageable size: neutron beam generator, aiming system, together with ability furnish should add together upward to no to a greater extent than than “a few hundred pounds,” he said.
Safeguard missile defence strength site inwards Nekoma, North Dakota
Those numbers brand the neutron beam generator practical for a broad arrive at of military machine applications. While detecting roadside bombs is the most near-term possibility, a high-power version of the same engineering could live mounted on aircraft or fifty-fifty satellites, something he’s discussing amongst Army Space & Missile Defense Command here. Like high explosives, nuclear warheads are extremely dense, made of plutonium or uranium. So, similar conventional explosives, nuclear explosives are dense plenty to halt neutrons that would larn through most ordinary materials, together with in 1 lawsuit the neutrons hit, they generate a distinctive flare-up of gamma rays. By zapping incoming radar contacts amongst neutron beams, missile defenders could tell which were decoys together with which were existent warheads, allowing them to target the existent threat.
At fifty-fifty higher ability levels, the neutron beam generator could also disable electronics. High-energy neutrons, it turns out, create nasty things to materials similar the silicon used inwards estimator chips or the gallium used inwards radars. It’s rather similar a neutron bomb, except you lot tin aim it at 1 target instead of blasting everything indiscriminately. (There are other aimable electronics-killing technologies out in that place every bit well, similar high-powered microwaves, but the arrive at is much shorter).
So, I asked, could a sufficiently high-powered neutron beam non but discover a nuclear warhead from a distance, but genuinely disable it? Dent, who worked on the Safeguard missile defence strength organisation every bit a immature Army officeholder together with after on Reagan’s Star Wars first for SAIC, pondered a moment.
Then he said: “Could it fry the electronics ? Yes, it could.”
And is that but a theory, I asked afterwards, or something you’re actively working on? The answer: He’s working on it.
Electrons, protons, together with neutrons inwards an atom (highly simplified together with abstracted).
The Physics: Rats together with Rhinos
Neutrons are non user-friendly particles, so getting them to business upward politely together with all larn into 1 management is a remarkable feat of physics. If electrons are the rats of the subatomic Blue Planet — small, fast, highly reactive to stimuli, together with able to sneak inwards almost anywhere — together with so neutrons are rhinoceroses: big, unresponsive to most stimuli, tedious to larn going, but in 1 lawsuit inwards motility almost impossible to stop. (Why? Electrons receive got a large electrical accuse but really picayune mass, making them piece of cake to “grab into” electromagnetically, spell neutrons receive got a large volume but no charge, making them the subatomic equivalent of a bowling ball amongst no finger holes).
Our culture runs on electricity because electrons are tractable: Magnetic fields together with copper wires are basically the Pied Piper for electrons, able to brand the rats scurry wherever nosotros desire them to go. But neutrons are intractable: What Dent has done is invent the Pied Piper for rhinoceroses.
How Dent directs the neutrons is an practise inwards arcane quantum mechanics. Since a neutron has no electrical charge, you lot can’t straight it amongst electromagnetic fields the way you lot tin straight a charged particle, such every bit electron or a proton. But neutrons split off from atoms (in this case, from the atomic nucleus formed when deuterium together with tritium undergo fusion inwards a particle accelerator). And you lot tin arrive at an atom a accuse (by adding or subtracting electrons). So instead of manipulating the neutrons themselves, you lot manipulate the raise atoms to brand certain the neutrons they emit larn into the correct direction.
Specifically, an atomic particle spins on its axis, similar a top. If that particle undergoes a nuclear reaction together with splits off another, smaller particle, the spin of the raise determines the spin of the child. (In mathematical terms, spin is a conserved quantity). Normal neutron generators shoot neutrons inwards all directions because the atoms generating the neutrons are all spinning inwards dissimilar directions. But if you lot tin business upward atoms so they’re all spinning inwards the same direction, you lot tin predict the management of whatsoever novel particles they spin off. That is how Dent aims neutrons.
Relative volume together with accuse of protons, neutrons, together with electrons.
Readers amongst a background inwards either scientific discipline or scientific discipline fiction powerfulness realize what we’re taking nigh is a course of study of particle beam. But experimental particle beams inwards the existent Blue Planet by together with large shoot charged particles, which are easier to aim than neutrons but which are also to a greater extent than massive also interact much to a greater extent than amongst the atmosphere, slowing them down. Those resistances require a lot of ability to overcome. Since the neutron beam generator shoots neutrons, which receive got no accuse together with don’t interact amongst anything less dense than high explosives, it takes much less unloose energy to propel them a long distance. Finally, why larn to all this problem to generate neutrons to discover conventional together with nuclear explosives? Readers powerfulness wonder why nosotros can’t discover nuclear weaponsfrom long arrive at already. But reverse to myth, nuclear warheads aren’t specially radioactive compared to, say, granite or bananas. So you lot can’t discover nukes from a distance amongst a Geiger counter — at to the lowest degree non until they detonate, which is rather every bit good late.
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