# Making atoms out of their building blocks (p,n,e-)

1. Oct 17, 2013

### taylaron

Greetings Pfers
I am curious what breakthroughs need to be made for the completion of a device capable of forming an atom out of the basic subatomic particles (protons, neutrons and electrons). Technology is advanced enough to where we have machines capable of generating these subatomic particles at will, and at very precise quantities.

http://en.wikipedia.org/wiki/Electron_gun
http://en.wikipedia.org/wiki/Neutron_source
Ionized hydrogen for a proton source
All of these can be generated using various exposures to ionizing radiation

Basically, we have the building blocks of an atom. So, what is keeping us from generating materials like Aluminum, Plutonium, or any other element?

While the energy required at the moment to generate the protons, neutrons and electrons most likely far outweighs the cost of traditional mining and refinement, please focus on the topic at hand.

Regards,
-Tay

2. Oct 17, 2013

### UltrafastPED

You need very high energy densities. For example, an ultrafast petawatt laser can (and has) transmuted elements.

This also occurs in the sun. But the energy density of the core of the earth is insufficient.

3. Oct 17, 2013

### mathman

Processes to create atomic nuclei are very expensive and produce extremely small quantities, suitable for lab. studies, but not for any commercial purpose.

4. Oct 17, 2013

### Staff: Mentor

It's not clear why one would bother constructing atoms of elements from nucleons when they are available naturally and are mined economically. Economics is certainly a deciding factor in collecting an element. Neutron sources require pre-existing elements, regardless of the reaction involved.

5. Oct 17, 2013

### SteamKing

Staff Emeritus
The problem is that you just can't take a batch of protons and neutrons and stick them together as if they were Legos. (Electrons are easy to add once you get the nucleus put together). The problem gets harder once the nuclei have more than a couple of protons, because adding any more protons requires that the incoming proton overcome the repulsion from the nucleus due to coulomb forces. It takes a lot of energy to do this, which is why transmutation requires the use of a particle accelerator or a nuclear reactor to induce radioactive transmutation by bombarding a target with neutrons (which are electrically neutral and not affected by coulomb forces from protons).

6. Oct 18, 2013

### taylaron

Thanks for your feedback. While it's apparently already been done, there is a lot of advancements that need to be made for it to become in any way practical. I hadn't considered the challenges associated with coulomb forces.

Regards.

7. Oct 19, 2013

### Staff: Mentor

As SteamKing indicated, the coulomb forces make it difficult for protons (or other nuclei) to approach a target nuclei, and as Z increases, the probability of 'absorption' decreases, while the probability of scatter increases. Much of the energy involved in the process would be lost to ionization of existing atoms and scattering (of the projectile protons or nuclei) and recoils of the target nuclei.

Coulomb forces $\propto$ Z2 for same species, or ZtZp, where Zt is the Z of the nuclear target and Zp is Z of the nuclear projectile.

There are no advancements that would make building nuclei from constituent nucleons 'practical'. One is stuck with the physics at hand, e.g., spallation reactions with existing elements. Stars on the other hand are practical with regard to nucleosynthesis, but they are 'out of reach', as is the sun. One can collect solar particles, but even that is expensive.

The earth's atmosphere does collect solar particles (solar wind) and cosmic radiation, and there are often spallation reactions that result in lighter nuclei, as well as the occasional formation of anti-protons.