Talk:Neutron/Archive 1

Talk:Free neutron

(from merge of Free neutron into Neutron)

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Zero binding energy

zero binding energy? It is tens of times heavier than its quarks put together...

Binding energy has many meanings. On the isotope infobox binding energy "is derived from the strong nuclear force and is the energy required to disassemble a nucleus into neutrons and protons". — oo64eva (Alex) ^{(U | T | C)} @ 19:40, May 29, 2005 (UTC)

Proposed merge of fast neutron and thermal neutron into free neutron

The exact same particle, just at two different energies. For both the novice and the professor of physics, it would be useful to have the content for all three particles on the same page - Jack (talk) 15:39, 26 July 2006 (UTC)

I like having thermal neutron as its own page. In radiation physics we talk of thermal neutrons, and I have not heard the term free neutron. Perhaps a link between pages is a good compromise?

What is the disadvantage of having thermal neutron as a section in the free neutron article? Thermal neutron can only really be understood when compaired to a fast neutron. I think they should both be in a page where they can be discussed in prose - Jack (talk) 21:51, 26 July 2006 (UTC)

The idea of an encyclopedia is to expand your knowledge, I think knowing that fast, thermal, intermediate, cold, and other neutrons are all free is very useful. I agree with the merge proposal but suggest it no go on until this article isn't awful. Pdbailey 06:00, 27 July 2006 (UTC)

Which article is awful, and why? The idea of a merge is that is quickly increases the size of an article, and then we can begin cleanup. If two (or more) articles need merging, they should be merged, unconditionally. - Jack (talk) 15:31, 27 July 2006 (UTC)

I agree with your idea that having them all in one place will help. This artile isn't so bad now, but it still has huge holes.Pdbailey 00:47, 17 August 2006 (UTC)

Free neutron half-life

Can anyone get a definative source for a neutron's half-life? I've found a few, but they all seem to disagree. I've heard 10.3mins (680s) / 15mins (900s) / 16.83mins (1010s) - Jack (talk) 15:31, 27 July 2006 (UTC)

Yes. I will update it on the page itself. Note that the lifetime is log_e(1/2) times longer than the half-life. --Strait 21:27, 10 August 2006 (UTC)

Pick of very small nit: You mean $\lg \ e$ times longer, I'm sure. $\ln \ 0.5$ is negative, about -0.693. BrianTung 20:59, 29 August 2006 (UTC)

The infobox contradicts the article lead on this now. Also, there should be a section on decay; the intro shouldn't have information not in the article itself. Since the PDG has 885.7 ± 0.8 s, I'll change the infobox to match. Reading the commment directly above would have been good. :) --Starwed 23:50, 23 May 2007 (UTC)

Early on around 1960 the neutron half-life was reported to be 3.2 seconds. It could be it does not have a specific relationship to the time domain. Could be political pressure. My 1986 CRC says it's around 3 minutes. Seems like neutrons appear spontaneously in space and decay into hydrogen; that's where stars come from. 67.136.128.168 (talk) 12:35, 16 December 2007 (UTC)

Neutron Waste

How do free neutron constitute 'huge amounts of radioactive waste'? (In the context of fusion.) Neutrons decay quite fast, or bind to existing atoms. And it's not particularly difficult to select materials that either don't become radioactive after neutron absorbtion, or if they do, then to find materials that decay quickly after absorbtion. Either senario will not generate 'huge amounts of radioactive waste'. 71.199.123.24 22:39, 16 August 2006 (UTC)

free neutrons with high energy can do a lot more than add them selves on to an existing atom. They can also spallate the atom which can make mostly okay stuff but some nasties. Also, it is difficult to find materials that can contain the stuff that is making the neutrons (i.e. something extreemly hot) and has the nice properties listed above. You sure are right that if water made great walls, this would not be a problem... but. --Pdbailey 00:56, 17 August 2006 (UTC)

I didn't think of spalling, but still, you make a normal metal wall, then a large amount of water shielding around it (and the resulting heavy water could maybe become some of fuel, and act as cooling). I'm not saying there will be no waste, I just don't see how it could possibly be huge amounts. 71.199.123.24 02:34, 17 August 2006 (UTC)

The problem is much simpler from the outside than from the inside. As an example, after defuling a nuclear power plant in the US, the shielding is still hotter than a pistol and is generally entombed in place. This is a huge part of our existing reactor decomissiong problems.

As for fusion reactions, I just added a link to a BBC page that claims that at the new fission reactor in Frace: (a) there will be raidioactie waste at the new fussion reactor site in Frace, and (b) that there will be long lived radioactive waste. They calim that it will be 10 cubic meters, but you can bet when the time comes it will be a lot more because you can't always find the border or cut just so to get just the bad parts (especially because people can't hang out there forever because it's radioactive). Industrial chemistry labs that can deal with this cost an absolute mint to build, opperate, and close and then gerarate huge amounts of waste from their cleanup.

To get specific about your complaint, metals can activate, esp when the neutron has 14 MeV. Then the activated metal can get hit again, and this is where the nastiest guys can come from because the designer could only find a metal with a good first reaction product, not a good second reaction product. Also, these reactions don't happen at room temperature, you need a material that can hold up the walls (and all the material above the walls) while under high heat and perhaps pressure, and do this even after a sizable fraction of the material has been activated to something else which always reduces the structural integrity of the material. Pdbailey 12:53, 18 August 2006 (UTC)

QUESTION TO THE AUTHOR

WHERE DID U GET YOUR FIGURES FROM? I.E. WHERE ARE YOUR REFERENCES? SPECIFICALLY ON THE VELOCITIES OF THE NEUTRONS (BOTH THERMAL AND FAST) AND ALSO ON WHERE U SAID THE NUMBER OF COLLISONS REQUIRED FOR A FAST NEUTRON TO BE THERMALISED IS TYPICALLY BETWEEN 10-20; SURELY THAT DEPENDS ON THE MODERATING SUBSTANCE? AND IN THE CASE OF GRAPHITE, DO U KNOW HOW THIS FIGURE CHANGES?

ANY HELP ON THIS ISSUE WOULD BE APPRECIATED AND ANY GOOD REFERENCES FOR ME TO LOOK AT WOULD ALSO BE HELPFUL

THANKS!

Alextheo250 10:52, 14 May 2007 (UTC)

free neutron?

Why is there an article on free neutrons and not free proton or free electron (well, the free electron model doesn't count because they are still associated with an atom). Pdbailey 04:21, 17 May 2007 (UTC)

Isn't free proton covered under fully ionized protium? (ie, part of the hydrogen article) And free electron as part of electricity? 132.205.93.63 02:43, 18 July 2007 (UTC)

A free neutron is "free" as compared to being bound up in a nucleus, i.e. transmuted into an chemical element. A free electron or proton are altered only by chemical processes, such as the ionization of hydrogen. From the perspective of human society transmutation is seen as a powerful barrier that distinguishes fundamentally different entities, and so it is a convenient place to draw the line between articles. Wnt (talk) 20:16, 18 May 2008 (UTC)

Mean life

Is it 15 minutes or 10 minutes?--Dojarca (talk) 11:10, 14 December 2007 (UTC)

Neutron-electron interaction?

I don't currently have access, but apparently there is some electromagnetic interaction between electrons and neutrons.[1] I understand of course that this would be very weak and requires more than a point-(no)-charge approximation. Could someone elaborate what is known about this for the article - for instance, does it give any insight into the quark structure of the neutron, or can you create some sort of diffuse "orbital" with some kind of "chemistry"? Wnt (talk) 20:33, 18 May 2008 (UTC)

Assessment comment

The comment(s) below were originally left at Talk:Neutron/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

Part of a "set" with electron, proton.

Last edited at 03:23, 23 June 2006 (UTC). Substituted at 21:46, 3 May 2016 (UTC)

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