Positron confusion

[Silvestru]

Hello group,

 

I was reading about positrons and in the wikipedia article there is this section:

Physicists at the Lawrence Livermore National Laboratory in California have used a short, ultra-intense laser to irradiate a millimeter-thick gold target and produce more than 100 billion positrons.Presently significant lab production of 5 MeV positron-electron beams allows investigation of multiple characteristics such as how different elements react to 5 MeV positron interactions or impacts, how energy is transferred to particles, and the shock effect of GRBs.

 

 

I started reading more about it and it is explained that:

 

As they move close to the gold nucleus, the electrons each break apart into a lower-energy electron and its anti-matter opposite, a positron. The high-energy electrons would naturally break down into matter and anti-matter pairs; the gold simply speeds up the transformation.

 

 

I thought that a fermion cannot create another fermion + it's oposite anti-fermion equivalent. It's the equivalent of disappearing.(at least at my current level of understanding).

 

Can anyone help?

 

Links used:

 

https://en.wikipedia.org/wiki/Positron

 

http://www.nbcnews.com/id/27998860/

[Sensei]

When you have high kinetic energy particle (accelerated to significant part of speed of light), upon collision there can be created pair of particle and its antiparticle, to conserve quantum numbers.

 

In this article you have examples of calculations of energy needed to create such pair:

http://galileo.phys.virginia.edu/classes/252/particle_creation.html

On the bottom there is pair of proton-antiproton antimatter.

 

After creation from really fast moving particles, newly created pair is also accelerated to significant velocity, thus they don't annihilate immediately, and can be captured by electromagnetic traps.

f.e. https://en.wikipedia.org/wiki/Ion_trap

Edited June 9, 2017 by Sensei

[Silvestru]

And can a high energy anti-particle split into a particle and another anti-particle too?

[Sensei]

And can a high energy anti-particle split into a particle and another anti-particle too?

 

Yes, of course, if they are unstable they will decay after a while.

 

In particle accelerators like LHC/CERN inside chamber there are external electric and magnetic fields, which bend paths of newly created particles,

so positive charged particles are flying in opposite direction from negative charged particles, and they're starting making "circles".

 

 

In Bubble chamber (now ancient) particle detector, there is liquid Hydrogen, and x-rays are used to make photos many thousands times per second.

Paths of accelerated particles are visible on photo, and can be analyzed.

Edited June 9, 2017 by Sensei

[swansont]

The NBC summary is giving you some combination of omitting details, using imprecise teminology and being flat-out wrong.

 

This shows more detail and explains that the production is of an additional e-e+ pair

https://str.llnl.gov/JulAug09/pdfs/07.09.3.pdf

[Silvestru]

The NBC summary is giving you some combination of omitting details, using imprecise teminology and being flat-out wrong.

 

This shows more detail and explains that the production is of an additional e-e+ pair

https://str.llnl.gov/JulAug09/pdfs/07.09.3.pdf

 

Haha I wasnt expectng anything less from NBC but I thought I would add the link anyway.