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GeV Acceleration In 3 Centimeters
ZonkerWilliam writes, "Here is a very interesting article, for the scientific community at least, on an advancement in laser wakefield particle accelerators. Being able to accelerate electrons to 1 Gev in the space of 3.3 cm calls up visions of portable devices that can be used anywhere: think of portable cancer therapies, if they can do the same for positrons, portable PET scans, possible use in compact fusion devices, capturing the dearly departed, etc. The uses are mind boggling." From the article: "By comparison, SLAC, the Stanford Linear Accelerator Center, boosts electrons to 50 GeV over a distance of two miles... The Berkeley Lab group and their Oxford collaborators... achieve a 50th of SLAC's beam energy in just one-100,000th of SLAC's length." I doubt that this tech will fit on a table top anytime soon. The article quotes the Berkeley researcher: "We believe we can [get to 10 GB] with an accelerator less than a meter long — although we'll probably need 30 meters' worth of laser path."
How many eV would it take to make Han Solo's blaster? :)
I believe Han Solo's only notable piece of equipment is a small bouquet of daisies, one of which he gives to Guido in the super-hyper-ultra-master-remix of Star Wars Episode -12.
Why on earth would Han want to "blast" anything, as is? He's a perfectly legitimate businessman, brought into hard times by a pair of misfits who attack people with Mag Lites... or at least that's the latest Lucas version.
At last, a portable zap gun! About freakin" time!
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Mad science! Robots! Underwear! Cute girls! Full comic online! http://www.girlgeniusonline.com/
But if you only need 30 meters of laser path, wouldn't it be possible to just use different mirrors to reflect within the chamber to obtain the length needed, and can't you do it thanks to the light wavelength in nano (or pico??) meters?
I'm not that educated in lasers, it wasn't as big of a study as mass-power mini railguns (no joking) to me. Someone PLEASE inform me and nobody bother modding me, I just want answers for my education.
Still waiting on Serviscope_minor to wake up to fucking reality and realize that Jessica Price isn't going to fuck him.
capturing the dearly departed, etc.
Holy Jesus, we can capture ghosts now with our 1 inch laser PET scans!!!
I don't bother scanning for 'em, at this point if I so much as suspect I have a PET I just call in the exterminator. I've really gotta start bein' more careful about shutting my back door.
The racoons and possums I was able to deal with myself in fairly short order, but it took 18 years to get rid of that damned cat.
KFG
Seeing as how the LHC produces two beams in opposite directions with energy 7 Tev each (total collision energy is 14 Tev) this accelerator has 3 or 4 orders of magnitude to scale before it can even begin to compete with the LHC.
History will be kind to me, for I intend to write it - Sir Winston Churchill
GeV = giga electron Volts
Also, TFA links to an illustrated version of the story.
We're talking about electron volts. You see, electricity is not the electrons themselves, but rather a wave of energy passing from one electron to the next as they collide with each other. (A bit simplified, but hey.)
You know those desk decorations that have about 5 metal ball suspended from wires? If you lift one and let go, gravity imparts energy on one of those balls. When it hits the next ball, it transfers energy to the other ball, which in turn hits the next ball, transfers its energy, so on and so forth. When the last ball has nothing more to hit, it swings out from the kinetic energy imparted on it. This is pretty much how electricity works.
An electron Volt is a method of measuring the kinetic energy for individual particles. It translates directly to the voltage/joules calculations we all know and love, except that it only involves one particle instead of a wire full of them. Most commonly, this term is used in particle physics where the energy of a single particle matters.
What has been built here is a micro particle-accelerator capable of imparting massive velocities on individual electrons. This is useful for things like advanced medical scanners which bombard a target with a small number of high energy particles in order to get 3D image of the object. With a small enough particle accelerator, we could begin building devices like the medical tricorders you see in Star Trek. That's never been possible before.
Javascript + Nintendo DSi = DSiCade
When using a portable particle accelerator, always remember this important safety tip:
[End of Line]
For anyone who's interested, the actual velocity of the electrons is about 0.999999869 times the speed of light -- which is why talking about GeV is more instructive than talking about how fast the particle goes. The math follows, if you're interested.
... or you can type sqrt(1-1/(1GeV / electron mass / c^2)^2) into Google Calculator.
1GeV = energy = gamma * m * c^2 (gamma = 1/sqrt(1-v^2/c^2))
1 GeV / c^2 / m = gamma
1957 = gamma = 1/sqrt(1-v^2/c^2)
v/c = 0.999999869
Interesting fact: we usually hear about E = mc^2. That's the direct matter->energy conversion when the matter is at rest: if the matter is moving, we add on a factor of "gamma" -- which, at small velocities, is about 1 + 1/2 * v^2/c^2 (giving E = mc^2 + 1/2 mv^2, or rest mass + classical kinetic energy!)
Yeah, I have lost count of how many times i have heard those starving Africans saying "Man, I wish i could accelerate electrons to 1 Gev over 3cm".
God Be Gone
Yeah the LHC produces proton collisions but protons are not fundamental particles, they are composite particles (3 quarks each + gluons)! They make "dirty" collisions with all sorts of particles flying everywhere. Electron positron collisions are much much "cleaner", the energy per individual fundamental particle is what matters. The international linear collider (a planned e- e+ collider) is hoped to achieve center of mass collisions of just 1 TeV and this will be sufficient to explore in depth the physics hinted at in the LHC at CERN. That means you only need two 500 GeV beams to do this. It looks to me like we're a mere ~2 orders of magnitude away from that point. All that has to be done now is a little succesive staging engineering and work to get the luminosity up.
- "Hear that?! The percolations are imminent! Cease your ingress!"
And just to elaborate on what you've hinted at for others, the reason this will never make the LHC redundant is to do with that the LHC does not have a fixed centre of mass energy in collisions as as you said, they are composite particles so while the protons collide at centre of mass energy of 14TeV, the individual quarks and gluons collide with a variable centre of mass energy (depends how much of the momentum is carried by that quark/gluon) upto a maximum of 14TeV. Anything produced by this development would have a fixed centre of mass energy. Hence to discover any new particle you have to scan through the centre-of-mass energies manually so to speak which means you could well miss something interesting. At the LHC, the scanning of the centre of mass energies is automatic so to speak making it very difficult to miss the new physics resonance. Hence you build messy hadron machines to find something and then precision lepton colliders to study it in detail as lepton colliders need to know the energy of the particle they're studing in advance.
This device uses a relative modest 9TW. The submitter suggests some portable applications.
I'll get one of these, throw away the whole electron/laser surf part, and just use the portable 9TW generator in my Toyota Prius.
That should get me from 0 to escape velocity in 1 microsecond.
don't cut it off www.mgmbill.org
You see, electricity is not the electrons themselves, but rather a wave of energy passing from one electron to the next as they collide with each other.
Well, this depends on what context you're talking about. In a metal conductor, you're absolutely right - an individual electron crosses a potential difference at a speed much much less (generally a fraction of a millimeter per second) than that of the effect of electricity (which is close to c). In a vacuum, when energy is imparted by a particle accelerator (such as the particle accelerator you are staring into right at this very moment), the electrons move much faster than they do in a conductor, and there are few particle collisions within the beam.
Of course, the energy imparted to the electrons that are flying at your face when you're looking at your monitor is in the keV range, many orders of magnitude less than the GeV we're talking about here. Still, they move fast enough when they strike the phosphor screen that relativistic effects are just beginning to creep up.
Reading the responses, there is frequently a lack of understanding of just how big this stuff is, just what it takes to produce things like wakefield accelerators and the difference between instantaneous power in watts and available energy.
Which reminds me of a true story. One company I worked for, the MD (aka CEO) decided we had to have a carbon dioxide laser to replace the ruby laser in one of our products. He talked to an academic researcher and asked how big the laser would need to be. The researcher said 10cm long and was promptly hired.
Six months later he had a prototype. The laser was a ceramic tube with fittings on a stand, genuinely about 150mm long with the fittings. Behind it was a room full of high voltage equipment, giant capacitors, carbon dioxide cylinders, extractor fans and, in fact, a water cooling system connected to a pressure main.
It took the MD a litle time to realise that this stuff was all part of making the laser go. He then asked when it would all be reduced in size to fit into a hand held box. The researcher's response? "You never told me you wanted the electrics to go in a box. You just said you wanted a four inch long laser."
Pining for the fjords
It is not for electron beams that this would be a boon. It is rather for other particles (protons, heavy ions). The footprint of such facilities is pretty large. In the US there are currently a number of proton treatment centers. Protons allow you to generate more conformal treatments (e.g. treating tumor not healthy tissue) with very low levels of doses elsewhere in the body. The latter is important for patients expected to have long survival times (these are becoming more prevalent as we are able to cure more and more tumors with less side effects). This is particularly important in treatment of childhood cancers.
Heavy Ions is another ball game. Now you need a synchrotron to get these up to the desired energies. This means building another building only to hold the accelerator (no talk about treatment rooms, rotatable gantries or anything). Heavy ions are very good at destroying cells as they generate a high density of ionizations along their path. They also have the same interesting conformal properties as protons. There are only about 4 or 5 heavy ion facilities in the world, most of them in Japan or Europe. There currently is no economic gain to be made building heavy ion facilities, protons are now reimbursed and facilities are starting to be generated although they are very costly ($100 10^6)
A "portable" accelerator would reduce footprint and building costs immensely making it economically feasible. Unfortunately, the accelerators presented here do not have a high enough flux yet to be used for clinically relevant doses.
In short: interesting, but don't hold your breath. Implementation, even in a research setting is at least 10-15 years down the line. Of course I could be completely wrong and have one on my doorstep tomorrow, with a note by a physician, "please calibrate, a patient starts tomorrow"PET scans don't use accelerated positrons. A radioisotope is injected into the patient, which emits a positron when it decays. The positron immediately annihilates with an electron and emits two gamma rays. The gamma rays are detected and used to build the scan. To make the radioisotope you need a proton accelerator, but these are already very compact at 2-3m diameter, and anyway don't need to be near the patient.
Fusion, of course, has nothing to do with accelerating electrons.
I thought geeks knew this stuff, or do they only need to pretend these days?
They do but it would be a lot cheaper to move the patient to a hospital near a power grid than try to put one of these at every clinic.
Cancer patients getting radiation treatment need a lot of care. I am not sure that they would have much of a chance of surviving at a local solar powered clinic with an MD and maybe a nurse running the show.
Local clinics need to provide general care. Ideally any seriously ill patent would be transported to a larger care hospital for specialized care.
The money that it would take to provide that level of cancer care locally would be much better spent general care and transportation of special needs patients.
And before any idiot says anything about racism. The exact same thing would apply for a small town in the US or Canada.
I will give you points for a caring but it wouldn't be practical or provide the best benefit for the money.
Now maybe if the could mount it on a bus and use it as a mobile system it could have some value at small hospitals but those would tend to have a at least some kind of power grid.
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.