Photon photon collider

[37818]

http://www.forbes.com/sites/paulrodg.../#20c652fd5c14

One problem with the idea - not mentioned. In order to detect such matter from pure energy requires matter to be present. Which would skew such an experiment having matter present which allows a single high energy photon to become an electron positron pair.

It remains to be seen and understood how that experiment can be conducted,

[Kbertsche]

http://www.forbes.com/sites/paulrodg.../#20c652fd5c14

One problem with the idea - not mentioned. In order to detect such matter from pure energy requires matter to be present. Which would skew such an experiment having matter present which allows a single high energy photon to become an electron positron pair.

It remains to be seen and understood how that experiment can be conducted,

Interesting idea. I don't see how "having matter present" would "skew" the experiment, though it may be difficult to discriminate electrons and positrons from a photon-photon collision with those from other processes.

But other than showing that it is possible, I don't see the point of a photon-photon collider. The collision efficiency and luminosity would be ridiculously low. Converting energy from electrons to photons is extremely inefficient, no matter how it is done (bremsstrahlung, diffraction grating for THz, or FEL). Colliding two photon beam is extremely inefficient. (Colliding photons with electrons as in "reverse Compton scattering" is extremely inefficient; colliding photons is worse.). An electron-electron or electron-positron collider wold have much higher luminosity and would probably be much more useful as a physics tool.

[37818]

The experiment is to prove matter can come from pure energy without other matter present. That is how I understood this.

[shunyadragon]

The experiment is to prove matter can come from pure energy without other matter present. That is how I understood this.

Correct

[robrecht]

Since the Link in the May 2014 Forbes piece now seems to be broken, here is the original letter in the May 18, 2014 issue of nature photonics:

http://www.nature.com/nphoton/journa...n.2014.95.html

Old news, but very cool old news.

[37818]

Since the Link in the May 2014 Forbes piece now seems to be broken, here is the original letter in the May 18, 2014 issue of nature photonics:

http://www.nature.com/nphoton/journa...n.2014.95.html

Old news, but very cool old news.

Thank you.

It is not broken - but on the upper right of the page one must select contiune on to site. After that the link will just take you there. And that is only temporary until the next day.

[robrecht]

Thank you.

It is not broken - but on the upper right of the page one must select contiune on to site. After that the link will just take you there. And that is only temporary until the next day.

No, I don't mean your link to the Forbes article, but the link in the Forbes article to the letter that appeared in nature photonics--that's the link that is broken, at least on my computer.

[rwatts]

It remains to be seen and understood how that experiment can be conducted,

Throw two torches at each other?

[Kbertsche]

Since the Link in the May 2014 Forbes piece now seems to be broken, here is the original letter in the May 18, 2014 issue of nature photonics:

http://www.nature.com/nphoton/journa...n.2014.95.html

Old news, but very cool old news.

FYI, Here's another article about the idea; this one has a few technical details:
http://www.photonics.com/Article.aspx?AID=56211

They suggest using a 2 GeV electron beam to strike a 5 mm gold target to produce Bremsstrahlung radiation. After using magnets to remove the electrons which pass through the target, they suggest letting the photons interact with 400 eV blackbody radiation from a heated hohlraum.

A 2 GeV electron beam is around the energy used in some synchrotron light sources and electron colliders; possibly the experiment could be done at one of these existing facilities.

[37818]

My question is how will the experimenter know any resulting matter resulting from the high energy photons did not result from any high energy photons interacting with surrounding materials or from particle scatter?