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3mm Inexpensive Chip Revolutionizes Electron Accelerators
AaronW writes "Scientists and engineers at the US DOE SLAC National Accelerator Laboratory and Stanford University have developed an advanced accelerator technology smaller than a grain of rice. It is currently accelerating electrons at 300 million volts per meter with a goal of achieving 1 billion EV per meter. It could do in 100 feet what the SLAC linear accelerator does in two miles and could achieve a million more electron pulses per second. This could lead to more compact accelerators and X-ray devices."
"300 Mev photons are high-power gamma rays, not x-rays."
No, an accelerator of 300 MeV per meter over 3 mm gives you 1 MeV, or less if the actual field is over less than the chip size. Tuning down from there will easily get you into the x ray domain.
Avantslash: low-bandwidth mobile slashdot.
This is a reference to a movie called "Back to the Future"..
1) You'll probably get some photons out of the deal but they won't all be 300MeV. There are lots of places to put energy (this is what makes particle physics hard) and photons are only one of those places. See the light-matter interaction box on the "Photoelectric_effect" wiki page. At 1MeV, even pair production becomes viable.
2) Photons don't transmute atoms (search for "photonuclear reactions" for the exceptions). Neither do electrons (look up "Electron_capture" for the exception, but it generally only happens with electrons already bound to the nucleus rather than ones flying around). Neutrons transmute elements because they can ignore the Coulomb barrier. Irradiating, say, rubber tubing with gamma radiation won't make it radioactive (it'll probably make some radicals and mess with the chemistry, but nothing nuclear). Neutron radiation is a totally different story.
The modern classification of x-ray vs. gamma-ray is based on the source of the emission (electron vs. nucleus), not the wavelength. http://wiki.answers.com/Q/What_is_the_difference_between_gamma_rays_and_X-rays
If you read the article, you'll realize that there is a separate laser accelerator necessary BEFORE this chip, and then a second high-power IR laser necessary to drive the chip.
More-or-less, they've increased the efficiency of laser-based electron acceleration. Good on them, but the solution isn't, as the summary suggests by omission, just a small chip alone and nothing else.
More importantly for the parent (I know, I know, don't feed the trolls), the presented accelerator only accelerates electrons, and is intended as a gamma and x-ray source. That's very different from accelerating electrons and positrons to nearly the speed of light, or protons, or atomic nuclei, etc. To do high-energy physics, you need big, big accelerators. The device to accelerate a single subatomic particle to levels where it carries as much energy as a brick dropped on your foot, isn't going to be a crystal a few millimeters on a side.
Put my fist through my alarm clock with its ding-dong death inside my ear. - The Blackjacks.