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Since 2014 I can find 34 citations, none of which are an actual experimental realization of their scheme [1]. Anyhow, TL;DR: They theoretically propose the fol

Since 2014 I can find 34 citations, none of which are an actual experimental realization of their scheme [1]. Anyhow, TL;DR: They theoretically propose the following experiment: First, accelerate electrons to just below the speed of light and fire them into a slab of gold. This creates the beam of nessesary high-energy photons. Second, fire a high-energy laser at the inner surface of a tiny hohlraum (German for ‘empty room’) gold can, to create a thermal radiation field which generates light similar to that emitted by stars. Finally, direct the photon beam from (1) through the centre of the can, causing the photons from the two sources to collide and form electrons and positrons. It would then be possible to detect the formation of the electrons and positrons when they exited the can. === [1] https://www.researchgate.net/publication/270858006_A_photon-photon_collider_in_a_vacuum_hohlraum https://www.researchgate.net/publication/270858006_A_photon-...

ChuckMcM 9y ago
That struck me as odd as well. 57 citations none of them where they actually ran the experiment and created electron / positron pairs. This was fun though (from 2013) "A table-top laser-based source of femtosecond, collimated, ultra-relativistic positron beams" -- https://arxiv.org/pdf/1304.5379.pdf https://arxiv.org/pdf/1304.5379.pdf
hdhzy 9y ago
Comments such as this one make me always check comments before reading the submission. Thanks!
archgoon 9y ago
I know it's from the article, but the expression "Accelerate Electrons just below the speed of light" tells you pretty much nothing. An electron travelling at .9 the speed of light has 1.1 MeV of energy. Nature seems to be down, so I can't access the abstract, but the google tagline has the following. 'Photons emitted above 100 MeV as a function of target width, for 1 × 109 incident electrons of energy 500 MeV (blue), 1 GeV (black) and 2 GeV (red).' A table for comparison .9 1.1 MeV .99 3.6 MeV .999 11 MeV .9999 36 MeV .99999 114 MeV .999999 361 MeV .9999999 1.14 GeV So it's somewhere in the .999999c-.999999999c. Assuming that snippet was accurate. The LHC gets particles up to the TeV range, but, as the name suggests, they are much larger particles. An actual particle physicist can probably tell you more about whether it is significantly harder to get the much lighter Electron (and associated radiation losses) up to those energies. SLAC (https://en.wikipedia.org/wiki/SLAC_National_Accelerator_Laboratory https://en.wikipedia.org/wiki/SLAC_National_Accelerator_Labo...) apparently can get electrons up to 50 GeV, so if those energies from the snippet are the target ones, that part should be achievable.
- PoachedSausage 9y ago
  I'm not a particle physicist but a particle accelerator engineer. GeV energies for electrons are achievable with a reasonably sized synchrotron like Diamond Light Source[0]. The magnets required to keep electrons in line are quite a bit smaller than those required for protons due to the mass difference. Small refrigerator sized verses small car sized. [0] https://en.wikipedia.org/wiki/Diamond_Light_Source https://en.wikipedia.org/wiki/Diamond_Light_Source
raverbashing 9y ago
To be fair very few labs in the world have the ability to do that. Possibly only the NIF has powerful enough lasers

ChuckMcM 9y ago

That struck me as odd as well. 57 citations none of them where they actually ran the experiment and created electron / positron pairs. This was fun though (from 2013) "A table-top laser-based source of femtosecond, collimated, ultra-relativistic positron beams" -- https://arxiv.org/pdf/1304.5379.pdf https://arxiv.org/pdf/1304.5379.pdf

hdhzy 9y ago

Comments such as this one make me always check comments before reading the submission. Thanks!

archgoon 9y ago

I know it's from the article, but the expression "Accelerate Electrons just below the speed of light" tells you pretty much nothing. An electron travelling at .9 the speed of light has 1.1 MeV of energy. Nature seems to be down, so I can't access the abstract, but the google tagline has the following. 'Photons emitted above 100 MeV as a function of target width, for 1 × 109 incident electrons of energy 500 MeV (blue), 1 GeV (black) and 2 GeV (red).' A table for comparison .9 1.1 MeV .99 3.6 MeV .999 11 MeV .9999 36 MeV .99999 114 MeV .999999 361 MeV .9999999 1.14 GeV So it's somewhere in the .999999c-.999999999c. Assuming that snippet was accurate. The LHC gets particles up to the TeV range, but, as the name suggests, they are much larger particles. An actual particle physicist can probably tell you more about whether it is significantly harder to get the much lighter Electron (and associated radiation losses) up to those energies. SLAC (https://en.wikipedia.org/wiki/SLAC_National_Accelerator_Laboratory https://en.wikipedia.org/wiki/SLAC_National_Accelerator_Labo...) apparently can get electrons up to 50 GeV, so if those energies from the snippet are the target ones, that part should be achievable.

PoachedSausage 9y ago
I'm not a particle physicist but a particle accelerator engineer. GeV energies for electrons are achievable with a reasonably sized synchrotron like Diamond Light Source[0]. The magnets required to keep electrons in line are quite a bit smaller than those required for protons due to the mass difference. Small refrigerator sized verses small car sized. [0] https://en.wikipedia.org/wiki/Diamond_Light_Source https://en.wikipedia.org/wiki/Diamond_Light_Source

raverbashing 9y ago

To be fair very few labs in the world have the ability to do that. Possibly only the NIF has powerful enough lasers