Slashdot Mirror
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? :)
If I want a PET scan , I'll go to the vet.
- Aetheral Research -
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.
In what distance can they generate 1.21 GigaWatts? 88 Miles for 1 hour? Capacity for Flux Generators?
Well, with this we might have to worry about raidation-shielding on armored vehicles. What's the point in armor at all if they can shine enough of these at your armored SUV?
Job? I don't have time to get a job! Who will sit around and bitch about being broke and unemployed then?
At last, a portable zap gun! About freakin" time!
--
Mad science! Robots! Underwear! Cute girls! Full comic online! http://www.girlgeniusonline.com/
One of the major issues with the deployment of such portable technology is the power requirements. If they could get it to run off solar power, that would be a major boon to the less wartorn parts of Africa.
"In no instance have the churches been guardians of the liberties of the people." James Madison
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!!!
capturing the dearly departed
So, are you saying that we can now capture ghosts with a particle thrower (Proton Pack). Damn, SciFi really DOES pave the way toward the future...
Excuse me now while I hide from the Stay-Puft Marshmallow Man!
Life is not for the lazy.
one needs a beam of sufficient luminosity / small emmitance to be useful on its own wthough I suppose this could start off as an injector to a more traditional accelerator.
Imagine a Beowulf cluster of these!
No seriously. If you can get 1GeV in 3cm and 10GeV in a few meters, the LHC is redundant before it got completed.
It would kick ass if a group of undergrads somewhere complete an accelerator with the energy of the LHC and start testing the weak theory days before the LHC becomes operational. What was the cost of it again?
"Give orange me give eat orange me eat orange give me eat orange give me you." -Nim Chimpsky
GeV = giga electron Volts
Also, TFA links to an illustrated version of the story.
This advancement could create portable Free Electron Laser (FEL), coolest laser around. The most interesting thing of FEl is that it can have variable wavelength.
It can be tuned to just above the highest energy absorption line (the "K edge") of the chemical element, and that element can be used for total reflection mirror at grazing angles. Thus Lead can be used to create optic for FEL X-ray laser tuned to Lead K-edge. Effective X-ray laser becoming possible without any nuclear blast. And even portable X-ray laser.
X-ray laser may have range measured in light secondd, light minutes and even light hours, making possible to build high resolution X-ray LIDAR with ability to scan Pluton surface. And Laser Cannon with the same range too.
The source of the positrons in PET scans is a radio-isotope consumed by the patient - no messy acceleration to GeV energy required.
A PET scanner doesn't work by bombardment with positrons. Positrons are generated internally by the decay of a radiolabeled metabolite or dye that's given to the subject. The positron (aka anti-electron) generated by the decay immediately finds an electron in the surrounding matter and the particle-antiparticle pair annihilate each other and emit two gamma-ray photons 180 degrees apart. These photon pairs are what is being detected and used to build the image.
And I thought just zapping unsuspecting friends with a 50kv taser was fun. This thing is going to be a blast!
-b
If I wanted a sig I would have filled in that stupid box.
That's great, I guess, but my Seagate gets to 160 GB, and it is much less than a meter long. So: hard drives are better than accelerators when it comes to storing data? And I'd wager that HD's require a LOT less power to operate, though I admit to not having RTFA yet.
This is a hacked account, for which the owner can not be held responsible.
This seems like we're on the way to tricorders. Handheld PET scanners, SWEET.
The Doormat
If you're not outraged, then you're not paying attention.
When using a portable particle accelerator, always remember this important safety tip:
[End of Line]
I visited the Standford Linear Accelerator, I highly reccomend that you go see it if your in the area. The tour was very informative, pretty neat to see a building 2 miles long, perfectly straight. The laser path is actually like 30 feet below ground, though. Also, they are building an addition to make it even longer, for a new project financed by the DOE.
Where are you going to find a 40 TW laser that is considered portable? They don't mention how big the laser was. I would be willing to guess that a 40 TW laser takes up a fair amount of real estate.
"To those who are overly cautious, everything is impossible. "
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!)
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
I don't see how this is immediately very useful for electron-beam cancer therapy. This system seems infinitely complex compared to the current methods for generating electron beams--the one I can come up with off the top of my head is thermionic emission from a tungsten wire plus acceleration through a potential in vacuum. This process generates the keV-MeV range electrons that are necessary for therapy (I think) or for producing X-rays.
Now, I'm a medical physics _student,_ so if anyone has some better insights into this please feel free to correct me. I'm honestly not even sure if that method I outlined above is commonly used for generating electron beams for therapy--I know it is for x-ray generation. I suppose it's probably more common to use a linac to generate particle beams. I'm also not 100% certain that high electron energies _aren't_ desirable for cancer therapy (most of what I've done so far has been x-ray imaging). Once again, anyone feel free to correct me, but it seems that therapy aims for the keV-MeV range.
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
Am I missing something here? Is he talking about making F-18 portably? Didn't the article say the unit would be room-sized...like say a cyclotron, already used to make F-18? Also, you don't make F-18 using positrons. F-18 gives off positrons.
I'm not much of a physicist but a while back in the mid 90s someone came up with a way to get
:-)
MeV electrons by hitting a very thin metal foil with a laser.
"High-energy electron beam production by femtosecond laser interactions
with exploding-foil plasmas"
http://xray.ipcf.cnr.it/archivio/PRE_RC_01.pdf
They were already back then ten years ago jawing about cheap radiation equipment for example for
radiation therapy etc. Nothing came of it, I wonder why Siemens or Varian or all the rest of the equipment
manufacturers aren't delighted that there now is a cheap alternative?
Btw, you don't need to wear that lead apron while burning DVDs
The production of positron emitting radioisotopes in a cyclotron, eg. F-18, requires the acceleration of a beam of protons - very different from electrons.
And even if you can produce the isotope in a pocket-sized apparatus, the scanner itself - the array of scintillators, lightguides, photomultipliers, electronics and computers that the patient lays inside, is not exactly portable by any stretch of the imagination.
"So its a ray?"
"Yes."
"That causes instant death?"
"Yes."
"Then why don't you just CALL it a DEATH RAY?"
~Eureka
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?
Railgun, Railgun, Railgun...
USB-powered tabletop LHC. It can produce nice experiments with black holes on your desk when running as screensaver.
Holy moley - how much energy does 10Gb of data have?! That'd just punch right through a firewall, and set fire to the editors sitting the other side!
biopowered.co.uk - catalytically cracking triglycerides for home automotive use since 2008. Just say no to big oil!
In fact the laser power supply system together with laser itself occupies almost as much space as a conventional accelerator does. Also laser acceleration have a long way to go to achieve the repetition rate, efficiency and reliability of a conventional radio frequency accelerators.
More importantly, considering that Earth is tech level ~9, does that mean that PGMP's really are more like tech level 10, not 12?
-Styopa
Just use one billion volts.
To me a 1 GeV particle accelerator that can fit in a semi-truck or room or heck even two rooms, is "portable" compared to lugging around a 2 mile long linear accelerator!
When I said cancer therapy I was thinking more along other known therapies such as Pion therapy, more novel but effective in treating tumor cells just as well. See here for Pion therapy: http://www.triumf.ca/welcome/pion_trtmt.html See here how to create Pion's using electron bombardment: http://prola.aps.org/abstract/PR/v102/i5/p1392_1
As the other posters said, the purpose of the laser is to accelerate electrons. The way it works is that Hydrogen is ionized, breaking apart into protons and electrons, and heated to form a plasma. A laser is shot through this plasma, and the electrons are "pushed" down the chamber. Assuming I understanding this correctly, if the photons were reflected back through the chamber, the electrons would be pushed the opposite direction, undoing the work of the first traversal.
Now it's my turn to ask a question to the physicists:) The article stated that the reason that this worked well was because the plasma acted simular to cladding on a fiber, keeping the light focused in the center of the chamber. Does this mean that it might be possible to create curved chambers? It also mentioned that their next goal was to increase the length of the device by chaining one after another. If successfull, might it be possible to create a wavefield ring, where the particle could be accelerated for as long as they like before being spewed out?
30 meters of laser path? Why would that stop you from fitting it on a table? You just bend it around with mirrors, like any other optics experiment.
One of the earlier Wake-Field experiments was done by UCLA at SLAC.
The problem with using a wake-field to accelerate particles, such as electrons, is that you lose a huge amount of current density.
You're basically using the energy of many electrons to sort of sling-shot and accelerate a few electrons. So that way the majority of electrons are "left behind" while the few are energized to however many GeV that they're talking about.
The significance of only having a few electrons? Well, if you're trying to observe particles colliding with other particles, you'd want to throw as many particles at it as possible to get as much data as possible. Using the wake-field method, you'll get the seldom particle-particle collission, but they'll be of an extremely high energy. So it depends on what kind of data you want to get.
-Kazem
You forgot to down-mod Kbox's last post. Geez, you asshat mods are really starting to slack...
Using Google: 5.4e20 G's. Whoa.
Um, what the heck does your little anecdote have to do with there being a "real crisis in physics education"? That was an example of a crisis in communication: it makes me think that the researcher has Asperger Syndrome or something. Because who in the hell would expect a CEO to have a clue about lasers and physics??
"Literal interpretation is another common, but not universal hallmark of [Asperger Syndrome]. Attwood gives the example of a girl with AS who answered the telephone one day and was asked, "Is Paul there?" Although the Paul in question was in the house, he was not in the room with her, so after looking around to ascertain this, she simply said "no" and hung up. The person on the other end had to call back and explain to her that he meant for her to find him and get him to pick up the telephone." (Wikipedia)
Now I can take care of that slowpoke in front of me once and for all.
..........FULL STOP.