Neutron Source
I've mentioned numerous times neutron sources, so here I bring what I had promised.
First of all, what are the neutrons? Neutrons are particles that form the nucleus of atoms. They consist of an electron and a proton (quarks up-down-down). What to serve? To get the atomic nucleus together by the strong interaction .
Generally, small nuclei have the same number of neutrons and protons, and as the atomic mass increases, it requires a much larger number of neutrons and protons to maintain the cohesion atomic nucleus.
And what happens if we add one more neutron to an atom stable? Many will know that a core is unstable when there is a big difference between the number of neutrons and protons. If we add a neutron to an atom, this will become unstable, and as the neutron will have an abundance, as a rule decay emitting an electron, transforming the neutron into proton (beta decay -).
Thus, the atomic mass is conserved (N), but the atomic number will rise to 1 (Z = +1). Indeed, 've created a new item!
For example, if bombarded with neutrons to U-238:
U-238 + n -> U-239 (b-) -> Np-239 (b-) -> Pu-239
We have obtained Fissile plutonium! But let's leave this for later (and lapsed, where decaying, half-life). Now take what we want ...
Neutron sources
There are basically two neutron sources: 1-The
using the interaction of alpha partÃculoa on a light element or
2-Those with an isotope with a very high rate of SF .
Let's see first. There are elements that decay by emitting an alpha particle. These are heavy elements: radium, radon, uranium, polonium, americium, curium ...
Well, is that they emit an alpha particle usually very energetic, about 5-6 MeV.
These helium nuclei without electrons (which are alpha particles), are so strong they can coalesce with another nucleus. This core must be of a light element, since otherwise the electrostatic repulsion forces are so large that it will break.
And that's what happens in this merger? An example of the fusion alpha with a core of Beryllium:
to + Be -> C-12 + n
As we can see, the alpha particle fuses with beryllium to form carbon (fully stable isotope) and releasing a neutron .
Beryllium is not the only element with this property are also oxygen, silicon or aluminum, to name a few. But yes, beryllium is the most efficient: for every million alpha particles generated 30 neutrons (remember that this merger is not always, a matter of probabilities.
Now go to the second method. Turns out there are so heavy atom, to be broken, because fission itself randomly. This is called SF (spontaneous fission, which is English).
This occurs even in the U, Pu, in many ... But it is very unlikely to happen in sufficient quantities for these fissions produce a very high number of neutrons. However, the Curio-248 and californium-252 especially are SF very elecvado index. The californium-252 (Cf-252) has a rate of 3,092% FS! This makes one microgram (1 mg) of Cf-252 emits a stream of
17 billion neutrons per second! That is an outrage, and makes it widely used as neutron source. The curium-248 (Cm-248) has a rate of 8% SF! While yes, this is not used as the Cf-252. The Curio is often used more as a source of alpha particles.
Our own neutron source
If you want to have your own source of neutrons, it is best obteis by the first method. Get Cf-252 or Cm-248 is usually very difficult. We can try to get from Nucliber , since they are official distributors of Isotrak. If you offer it without a license, you will draw a paste that you shit. Or you can try from this website Russian. Should the cops stop you, me I have not said anything XD
So we started. First, find a source of alpha particles.
What can be?
-Am-241 of a smoke detector (recommended). Radio
-phosphorescent handles an old clock.
-Po-210, highly recommended, but if you may have. Uranium and Thorium-
not recommended because of its low emission of alpha particles due to the long half-life of the two.
Am-241 can be extracted from the detector smoke as recently started here.
If you have an old clock radio with handles (that glow in the dark because they are radioactive) so you can use. How to know if they have radio or is it normal fluorescent PINTRO? Very simple: hide for 24 hours or more the clock. If you still glowing in the dark after having removed (try it to remove low light) is that it Radio. If not shine bright but before (years ago), it could have corrupted the phosphorescent material is excited by the Radio. For this you will not be forced to use a Geiger counter or a piece of blank paper radiography. If time being exposed is black, is Radio.
Or more simple, because sometimes there are places where they sell a lot of paint clockwise Radio. If you have the opportunity.
Polonium-210 only what you can find in photography, in some brushes that are used to remove static electricity. Or you can buy 0.1 mCi of polonium-210 in Spectrum Techniques. Although it seems little is enough.
Well, once the source you need Beryl. You could also use aluminum (paper "silver" cooking) or Silicon (Silica Gel, used in some bags, etc., to prevent moisture, and come in paper bags). Buy
Beryllium in Smart-Elements , UnitedNuclear , Emovendo , ElementSales , or just looking for San Google. Do not need much.
warn: The Beryllium is very toxic, especially in powder form. Keep you off the dust and I evitaréis problems.
Then, just will have to couple the source with beryllium (the more contact area the better) and you'll have your source of neutrons! Calculating
neutrons generated ...
For this you have to know your source alpha activity.
For example if you use 0.1 mCi of Po-210, how is it calculated? If 1 mCi are 1 / 1000000 Ci, and Ci (Curie) are 3.7e10 decays / sec, and only Po-210 decays by alpha particles, then the Po-210 emits 3.7e10 / 10000000 (we added a 0 over to be 0.1 mCi) = 3700 alpha particles per second. Beryllium 30 neutrons emitted per million alpha particles. Then
1000000 / 3700 = ~ 270 sec. to reach a million. We know then that in 270 sec 30 neutrons emitted, how many in a minute? A simple rule of thumb that gives us 6 to 7 neutrons / min! Not much, but for a start. We recommend using Americium, and all that podais (the more you find broken smoke detectors, the better).
"Now I can start?
yet, first you need a moderator of neutrons. I'll explain this in the next chapter.
Salu2!
0 comments:
Post a Comment