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New Accelerator Technique Doubles Particle Energy
ZonkerWilliam writes "Plasma wake particle accelerators are making surprisingly quick advances. It was a just a little while ago we had GeV acceleration in 3cm. Now they are capable of doubling the energy of electrons. 'Imagine a car that accelerates from zero to sixty in 250 feet, and then rockets to 120 miles per hour in just one more inch. That's essentially what a collaboration of accelerator physicists has accomplished, using electrons for their race cars and plasma for the afterburners. Because electrons already travel at near light's speed in an accelerator, the physicists actually doubled the energy of the electrons, not their speed.'"
One of these days those crazy scientists are going to do something and we will all just disappear into a mass of energy.
in 5, 4, 3, 2, 1...
The kinetic energy is proportional to speed^2 (E=1/2 m v^2), so a car at 120mph has 4 times the energy of a car at 60mph. Thus, doubling in energy is not like doubling in speed.
Unfortunately, these concepts will not be applied to the next generation of high energy accelerators. The International Linear Collider will supplant the Large Hadron Collider some time after 2015, but relies on superconducting static-gap technology and will be 30-40 kilometers long. Perhaps the next generation of experiemnts will employ plasma accelerators?
You might not believe it but there are some bona-fida scientists skulking about slashdot.
That's essentially what a collaboration of accelerator physicists has accomplished, using electrons for their race cars and plasma for the afterburners.
Those sound like really small physicists.
Wizard Needs Food, Badly
In terms of solving the relevent math covered in the study of Quantum Mechanics and Molecular Spectroscopy (senior Inorganic Chem II at my alma mater), pumping energy into an electron is computationally similar to accelerating an object of 1000 kg mass to 60 mph over the span of time required to travel 250 feet and then nearly instantaneously pumping enough energy to double the velocity in the span of time represented by the distance travelled in one more inch.
the NPG electrode was replaced with carbon blac
E=mv^2/2 only for small values of v.
The other formula for E, you might have heard of, is E=mc^2. m = \gamma m_0, where m_0 is the rest mass, \gamma = 1 / sqrt(1 - \beta^2), and beta = v/c. I.e.,
E=m_0 c^2/sqrt(1 - v^2/c^2)
For very small values of v (relative to c), 1/sqrt(1-v^2/c^2) \approx = (1/2)v^2/c^2, which leads back to your formula - but the approximation is only valid for v
Ben Hocking
Need a professional organizer?
I assume you are referencing Dimopoulos and Landsberg's paper http://prola.aps.org/abstract/PRL/v87/i16/e161602 . There is nothing to worry about. These physicists proposed that if certain theories were true (M theory, quantum loop gravity, super symmetry) then the energy densities seen in the RHIC or LHC experiments could produce something "mathematically analogous" to a black hole. There is no possibility under any current theory that an event horizon could form and attract matter.
I jammed a butter knife into a 220v circuit when I was a toddler and became a diembodied electromagnetic life-force with super powers.
Other than a morbid fear of lightning rods and antistatic wrist-straps, it pretty much rocks.
1/2 mv^2 is the non-relativistic kinetic energy. The mass correction will change the energy rapidly as v approaches c. The mass correction with the Lorentz factor in that expression are needed to get the correct relativistic energy.
The lorentz factor is 1/sqrt(1-(v/c)^2); at 0.99c it will multiply the mass (and energy) by a factor of 7; at 0.999c it will multiply everything by a factor of 22.3.
They increased the mass of the electrons by 1.65064935 × 10-27 hundredweight in 0.00032808399 football fields. Sorry, I don't know how much that is in SUVs.
Seriously, though, this is a neat trick. (Yes, IAAP)
Cue the crackpots who deny the science.
A simile depends on having a kind of mapping between one domain and another. These allow you to use reasoning from one domain to reason in another. That's why they're so useful - by using such a mapping, people inexperienced in one domain can still reason in it by leveraging their experience in another. For example, when Shakespeare says "Shall I compare thee to a summer's day" he points out that some of our reasoning about summer's days can be applied to people too. For example, just as many people are disappointed when we know there will be no more summer's days as autumn approaches, we know that Shakespeare would be disappointed if separated from the subject of his sonnet for an extended period of time. We know this even though he doesn't say it explicitly because he has set up a mapping that allows us to reason about his subject.
Sometimes the mapping is a direct translation. For example if someone says that detecting a pulsar with a new radio telescope is like seeing a candle on the moon we can guess that maybe the power being received from the pulsar is the same as the power received from a candle on the moon. Sometimes it's a scaling. For example if someone says that a flea's jump is like a human jumping over the Empire State building we guess that if we were to scale a human down to the size of a flea, then applying the same scaling to the said building would reduce it to the height of a flea's jump.
So now I can say what my complaint about this simile is. It gives no idea what the mapping is. Actually, it's worse, I can partly see what the mapping is, but the concepts I use to do this aren't in the grasp of the very people it is designed to help. But even in this case it's only a partial understanding. I don't know if the energy of the car is meant to be literally the same energy as that of the particle. I don't know if the 250ft is meant to be taken literally. And the stupid thing is that ordinary people have no intuition about the energy stored in a non-relativistic moving object, let alone a relativistic one. So most people are probably inclined to try to set up an interpretation of the mapping in terms of the car's velocity - and that's the wrong mapping.
Doesn't it make you feel good to know that our freedoms are protected by politicans, lawyers and journalists.
Unless you're irrational, that is.
im in ur
'Imagine a car that accelerates from zero to sixty in 250 feet, and then rockets to 120 miles per hour in just one more inch. First of all at non relativisitc speeds, doubling the speed results in a four fold increase in kinetic energy and not a doubling. Why give a bad classical mechanics analogy and then tell us that the speed didn't actually double because of relativistic effects.
I actually do some work on this with the PWFA group at USC (i'm an undergrad research assistant). It really is amazing! We can reach acceleration gradients of around 60 GeV/m, compared to something like 40 MeV/m for a normal accelerator. It works like this: .or at least something close to that!
1. The electrons travel down the main linac in carefully spaced "bunches", and get accelerated to around 43 GeV over a course of ~3KM (this is at the main beam at SLAC).
2. A (in the last experiment) 1.2m long Lithium plasma "oven" is at the end of the beam, which the electrons are directed into.
3. The first, or "driving," bunch goes through the plasma, and repels all of the electrons it gets near, leaving an "empty" wake behind it, where only the positively charged ions are.
4. The positive charge behind the driving beam pulls it backwards, causing it to lose energy. At the same time, a "witness" bunch placed strategically within the wakefield gets pulled forward by the positively charged ions. The witness gains energy while the driver loses energy.
5. Voila! One bunch now has twice the energy, and one bunch now has none . .
The main caveat is that you're upward-limited by your entering energy, so you still need a huge Linac to accelerate the bunches to begin with. This will likely get tacked on in the form of a "plasma afterburner" to a normal linac, such as in the setup at SLAC.
I'm perfect in every way, except for my humility.
As I understand it, luminosity is one major reason why this technology is not yet ready for prime time (i.e. not in time for the proposed ILC). You can't just accelerate a few particles to high energies and say you are done. You're looking for rare processes, so you need to create many consistent particle collisions per second in a tiny area. This means you need to have a tight, "bright" beam. The Tevatron has a luminosity of ~2e+32 interactions/cm^2/s now, the LHC may eventually reach 1e+34, and the goal for the ILC is more like 2e+34. Plasma wakefield systems are now demonstrating large increases in energy over short distances, but it's very difficult to daisy-chain them together to reach high total energies with any significant luminosity.
This division in our ranks is merely imaginary; don't let it keep us from finding the root of the problem.
It's nothing but crumpled porno and Ayn Rand.
Any black hole created in a lab on earth is going to have negligable sucking power, since the mass in them will be tiny. The vision of a black hole forming and swallowing the earth is great sci-fi, but (happily) poor science. At worst, it will hang around, swallowing the odd electron at very rare intervals.
Wikileaks, no DNS
Cue people who pretend they understand the science...
As mentioned, there are some of us around here who are actual scientists. However, there are no details in the article, thus no science to understand. All I found were crappy analogies with afterburners and some hand-wavey crap about plasma. I'm pretty sure that if it were as easy as running some crap through a plasma to accelerate it, it would have been done some time ago. And there are a number of pertinent questions:
Why do they have to use a 2-mile accelerator if the plasma can do in a foot what it takes the 2 miles to do?
Why can't it be longer?
How is the plasma chamber set up? I'm guessing it's probably an coupled with an RF field, which can accelerate a plasma, but details, come on!