The neutron as a particle - my thoughts

It may be difficult to separate "theory" from "application," but let''s see if this helps facilitate the discussion.
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The neutron as a particle - my thoughts

Post by Richard Hull » Tue Feb 25, 2003 9:49 pm

It is insightful to read Chadwick's Nobel presentation regarding the neutron. Thanks to Jon Rosenstiel, the PDF of this epic paper is now in the books and refs forum for all to view and read. I have had it in a number of texts here.

This represents the last of the great major matter particles to be discovered. (1935) That it existed, was no surprise.
Rutherford, with his keen insight into what might be needed to make the nucleus work, posited the idea in 1920. His one-time student, Chadwick, ultimately found the particle.

Rutherford realized that some unusual marriage of the proton and electron would solve the riddle of what might hold a nucleus together and account for the missing mass (discrepency between atomic number and atomic weight.) He surmised that this marriage would be mysterious and perhaps unfathomable.

Rutherford felt that this neutral particle might be neutral on the grand scheme of our major measurement down to the nuclear level. However, the particle would still hold out electrostatic irregularites at ultra short range (intranuclear). This being due to that unfathomable closeness of the proton-electron marriage. I still hold with Rutherford on this, of course.

The neutron could bind a nucleus electrostatically by sharing its electron with neighboring protons at ranges virtually unmeasurable and far below the range of Heisenberg uncertainty where the electrostatic forces would indeed equal the proposed but never proven or utilized strong force.

This would be just conjecture had it not been observed that free neutrons were unstable outside the nucleus and indeed did decay into a proton and electron. Something happens when a neutron is released form a parent nucleus. It starts to go unstable without the forever surrounding, linked protons which have been there since its birth in a star. The forces it contains are too strong for what is, in effect, a lilliputian hydrogen atom roaming free.

The ultimate exothermic reaction found in a single piece of bulk matter per unit mass is released inside of 10 minutes as the neutron blows apart giving up its long stored energy.

I view the neutron as the first piece of fused matter in the universe and the first item to fuse in any proton-electron stellar furnace. With this building block, a nearly instant fusion with the nearest proton next makes deuterium. A single neutron can never fuse with more than 2 protons, likewise, under no circumstances can the neutron number in any piece of matter ever equal three times that of the protons.


There is a critcal point in the periodic table. This is at calcium where all stable atoms can be made up of equal numbers of protons and neutrons. Beyond this point, casual fusion gets more difficult to near impossible outside of supernova.

Paramount to my concept and Rutherford's as well as common sense based on observation, is that P-P fusion is an absurdity. Yet this is the very stuff of the currently accepted stellar theory thanks to the imagined and yet never shown strong force. Ocams razor would favor electrostatic binding of a nucleus over an imagined new force. Those who might say we have measured the strong force and it is accepted would be wrong. The strong force is still merely a theoretical dalliance. What we HAVE measured is the force necessary to bind nuclei together. Common electrostatic forces at ASSUMED ranges appear to be insufficient to explain nuclear binding. Most of this argument is due to the strong net positive nature of the nucleus to the tune of its protons. However an old concept is resurfacing regarding a nuclear shell structure where neutrons, or what we call neutrons, layer the shared protons outward allowing the positive charges of the protons to manifest themselves in bulk fashion. All this using well understood and simple electrostatic laws. Ocams razor, again.

I truly believe that the neutron, if it is a true intra-nuclear particle, will not resemble, at all, the free neutron we observe. The free neutron should be much larger in size when out in the open.

One reason the cross section may swell with slow and thermal neutrons is that they are really physically expanding as they get older, losing energy and recoiling around in matter. They actually seek to be recaptured by this swelling. Alas, uncaptured, they swell to a bursting point.

To my knowledge,decay of fast neutrons has never been observed. (How would you do it?...How would you prove it.?) The normal method is to obtain, contain and reflect ultra cold neutrons in physically large systems and the protons of decay and rising hydrogen spectra are seen to herald the decay of these old, sluggardly neutrons. (Remember you have to actually make them and hold onto them in quantity to observe decay, quantitatively.)

For a number of years after the neutron was discovered, it remained the nuclear glue in the minds of most physicists.

With the plethora of muon, pions, etc that showed up in ever more cataclysmic accelerators just before, and especially after WW-II, the apparent need to fit all of these into some cohesive model bred the current quarkiferous sub-sub particle zoo and the strong force was dreamed up and quickly AFFIRMED without ever being CONFIRMED when simple comprehensible forces failed to seemingly answer questions about super energetic events spewing out "non-matter" and ultimately dreamed up particles beyond those seen in normal universal events. All of this led to the "standard model". It gave a lot of folks work and expanded our our present, codified, lack of understanding to super heights.

Oh well, I always needed to design things around goings on five orders of magnitude below heisenberg.

The simple neutron is indeed a unique and interesting bit of matter. Not found anywhere in the universe all to itself, but only contained in bulk matter. For me, the fusor is a way to get at these unique real world particles.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
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Re: The neutron as a particle - my thoughts

Post by DaveC » Wed Feb 26, 2003 6:33 am

Richard -

Thanks for sharing your thoughts ..some good things to chew on.
A stray thought occured while reading... that if the free neutron spontaneously disintegrates into a proton and electron, it would seem that colliding electrons and protons at sufficient energy, should make neutrons.

At first glance one might expect just simple neutralization. The proton thus becoming a hydrogen atom again. But with a binding energy of about 13.6 eV, the neutraliztion process would have to be rather gentle. More likely, the electron just sails on by. But a direct hit on the proton, would bring the electron-proton mass centers close enough for the coulombic attraction to oover power the relatively weak energy well out at the normal electron shell radius.

Doubt if the probability of direct hits occuring is very large. But even microamps of beam current present lots of opportunities for neutron generation to occur... if it can be done this way.

Dave Cooper

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Re: The neutron as a particle - my thoughts

Post by ChrisSmolinski » Wed Feb 26, 2003 3:07 pm

An *extremely* interesting article, Richard.

I remember several introductory nuclear texts, stressing that a neutron "isn't just a proton and an electron". But what if it is, as you say?

And what about other decay modes? When a nucleus has "too many" neutrons, it undergoes beta decay, converting a neutron into a proton and electron. Likewise there is the reverse process - electron capture.

Certainly many things to ponder.

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Re: The neutron as a particle - my thoughts

Post by Richard Hull » Wed Feb 26, 2003 3:53 pm

Chris is correct. The general view against all reason and logic that is held openly by the standard model is that the neutron.... IS NOT.... repeat.... NOT... a proton-electron pair. They say this boldly and with a great degree of certainty and, what's more, no shame at all.

Yet the lone neutron decays into a proton and a neutron. FACT
Beta decay demands that a neutron convert to a proton. FACT
Electron capture drops the nucleus one atomic number as a proton becomes a neutron. FACT


Ocams razor is becoming more and more rusty as it sits in the dank lab supply closet as no scientists today bother to use or strop it anymore. It is like the theorists are telling us that just because we observe a boy and girl step out of a box, this does not imply that there was ever a boy or a girl in that box. DUH!

Interestingly, on NOVA last night there was a great program on dirty bombs. They had to explain the atom, of course, in order to introduce radiation. I was stunned when the commentator said that the presence of neutrons in the nucleus help balance out the positive charge of the protons and assits in holding the nucleus together!!!!!! I was in mid gulp on a Pepsi and it almost got spit out all over my wife.

Wow! Nova usually researches stuff fairly tightly, especially in explaining basic concepts. They just got exhiled to the paw-paw patch on this one or either are talking to nuclear experts who are part of a new wave of realists.

It maybe that many in physics are tiring of giving a thumbs up, carte blanche, OK to ever more whacko extensions of an ever more tenuous and physically disconnected "standard model" that appears hopelessly mired in statistics based on predicted but unseen, secondary and tertiary events two layers deep in bubble chambers.

I long ago gave up on following much of anything in nuclear physics which can't be readily measured and shown at the laboratory level as a direct, linked physical cause and effect event. For as good scientists this is where we must uncouple from conjecture and never allow it to extend a single theoretical layer deeper than this last best guess. A long held, last best guess can never be used as a basis for another new theory, extension of an existing one or making another best guess.

Nonetheless, last best guesses made in the 40's and 50's which were never experimentally refuted, but seemed highly likely have repeatedly been used as bed rock for new theory and extensions of concepts. The generation that would have poo-poo'ed this travesty has retired and those they taught the last best guess to now move on it as gospel.

Real, comprehensible, cause and effect events based on common sense, logic and reason are the only really great tools we have in divining the natural processes. The point at which these concepts break down either in the ultra smallness of things or the super macroscopic demands that we see this as a barrier and go no further. At some point, we must accept the unknowable as physical reality breaks down.

Crafting a cleaver, self consistant theory two orders of magnitude below heisenberg is just a mental exercise designed to keep us from moving into protracted, pleasurable, self abuse.

Finally on to Dave's thoughts. I have been told that neutrons have been made in super accelerators by a couple of different phyicists friends. I would love to have references to give, but have none. I have thought as Dave has thought. Hydrogen is a product of very gentle proton-neutron interaction, indeed. Whole gang o' energy is locked up in the neutron and was put there by gravity (core cause of fusion) in the begining.

Richard Hull
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Fusion is the energy of the future....and it always will be
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Re: The neutron as a particle - my thoughts

Post by grrr6 » Wed Feb 26, 2003 6:44 pm

Where do you think the extra mass is comingfrom in the neutron? A proton has mass 938.3 MeV electron .5 MeV neutron 939.6 MeV, so there is an extra .8 MeV in there somewhere. If you ware colliding electrons and protons, this means that if "fusion" occurs, it wont start happening until around 1 MeV and might peak somewhere past this.

Similar to the 2D -> 2n + 2p stripping reaction, since its endothermic, more energy usually means better cross section. So if you can get electrons and protons up to the multi MeV range, this might be a neat experiment to try out.

I still wonder where that extra mass in the neutron is from. It seems as though a neutron is a proton and an electron, maybe with some particle holding them together? Could that be possible? Some particle holds them together somehow? And ive never understood this, a free neutron has a half life of 10 minutes, but a neutron in a nucleus, has essentially no decay. What does the presence of a single proton in deuterium do to stabilize the neturon? Richard said earlier that the stability ofthe neutron might have something to do with its energy, as you cool it, it might become bigger till it pops, that might have something to do with it.

Also, how does a neutron hold the protons in a nucleus together? Unless you invoke the strong nuclear force, its a really difficult question to answer.

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Re: The neutron as a particle - my thoughts

Post by Richard Hull » Wed Feb 26, 2003 7:20 pm

Greg,

Perhaps I did state my case as plainly as I should have. The neutron binds to the proton in a simple electrostatic manner by sharing the tightly held electron within the neutron. Thus, the neutron is in reality some form of hydrogen atom that has been crushed in some fashion where potential energy is locked into a stable intra-nuclear particle. This particle will only remain stable if it shares its electron with another proton in, again, some electrostatic manner. This makes the neutron stable only in a nucleus while sharing its electron with other nuclear protons. No strong force required, no gluonic dream particle demanded either, just good old electrostatics.

There is probably something that we do not yet understand about ultra-close range electrostatic forces that would allow, with a close enough approach, and in an energetic enough environment, proton-electron binding or ultra collapsed orbitals.

While neutron building is totally endothermic, neutron decay is, obviously, exothermic and returns that original energy.

One thing seems rather obvious and that is that the neutron is at the very heart of atom building and is certainly the first fusion done. After protium, and after the first fusion on the first stellar ignition, nature never looked back and never allowed any fusion process or atom to exist without neutrons. Neutrons are the nuclear glue.

If forced into a corner, I would say fusion goes in the stepped order of p + e = n, n + p = d, d + n = t, t+p= He and so on. (Notice the absence of p+p a rather senseless , illogical and never observed fusion reaction) The affore mentioned processes are most likely the ones that most stars actually build and burn on most of their active lives.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
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Re: The neutron as a particle - my thoughts

Post by ChrisSmolinski » Wed Feb 26, 2003 7:46 pm

Greg Rogers wrote:
> Where do you think the extra mass is coming from in the neutron? A proton has mass 938.3 MeV electron .5 MeV neutron 939.6 MeV, so there is an extra .8 MeV in there somewhere. If you ware colliding electrons and protons, this means that if "fusion" occurs, it wont start happening until around 1 MeV and might peak somewhere past this.

Well, when a lone neutron decays, the resulting electron has a maximum energy of, guess what, 0.8 MeV.

Richard mentioned some accelerator experiments where electrons and protons were collided, resulting in neutrons. I'd have to imagine the cross section of such a reaction would be rather small, otherwise, one could put a piece of plastic in front of a suitable beta source (say Sr90/Y90) and produce neutrons.

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Re: The neutron as a particle - my thoughts

Post by Brett » Wed Feb 26, 2003 8:00 pm

It's been about 20 years since * took college level physics, but let me have a crack at this, ok?

First, we know that making a neutron out of a proton and electron *requires* energy. Breaking up a neutron into a proton and electron *supplies* energy. But electrons and protons ATTRACT each other. If there were nothing but electromagnetism involved, it would be the other way around, right? Making a neutron would be highly exothermic, (The ultra-violet catastrophe, I think this is called.) beta decay would be endothermic. But they're not! This means that at some point, you have to be *fighting* a repulsive force when you're driving the two particles together, one that builds up faster than inverse square, or else it would be attraction all the way down.

And neutrons are (more) stable in nuclei, unstable by themselves. But how is a "condensed hydrogen atom" neutron going to tie two protons together, as in He3? Obviously it would have to be by some kind of super Van der Wals effect, right? But there's no arrangement of three equal positive charges, and one negative charge of the same size, where the net force isn't apart. And even if there were, the neutron's constituent parts would be under tension, if it were holding two other particles together. So it ought to be *less* stable in He3 than by itself, not more.

There's simply no way to construct a stable nucleus without adding another force besides electromagnetism, one that doesn't obey an inverse square law. So you're stuck with the strong nuclear force. Generations of physicists haven't accepted the existance of this force without good reason, after all.

At least, that's my take on this.

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Re: The neutron as a particle - my thoughts

Post by Richard Hull » Wed Feb 26, 2003 8:36 pm

Glad to here someone come in in favor of the strong force. Your arguments are well laid out and logical. I give a whole gang o' plus points for the argument concerning the electrostatic force stopping at a point due to some repulsive force in the creation of a neutron. SO...The posited strong force would need to be a repulsive force only and not an attractive force by this argument. This is worth considering, for most look at the strong force as a binding force within nuclei.

The strong force, whether repulsive or attractive, is undemonstrated as of yet other than through conjecture based on a feeling that it must be there. Fortunately for its proponents, and much like the neutrino argument, its proponents do not have to show a physical reality or interaction, use or versatility for same beyond the conjecture that such things must exist. This remains at the first step I mentioned about the "last useful best guess" we might make. That is why I am open, receptive, and pensive to arguments on the strong force. It is right at the heisenberg limit of things we might muse over. Finer structures than this or any further adavancement where the strong force is used as a positive argument to go lower is an absurdity. The strong force is just another one of those things that is theorized, un-proven, never seen, but so obvious an assumption, that over time it is melded into such an accepted edifice that new stuff based on it is accepted with open arms. I hope a lot of you can see this.

I am worried that nuclear physics feels it is on solid ground when ,as the camera zooms back to a full view, parts of currently accepted nuclear physics is actually seen as a tiny dot in the middle of a giant iceberg, hopelessly adrift.

How many theories on top of theories supporting bold new ideas based on assumptions that just sort of became accepted are we allowed before we see the emporer has no clothes.

Some of the latest stuff is so arcane that only a few people in the world could dare question it. That worries me mightily.

People poo-poo the seemingly logical but unseen aether yet speak openly and with straight faces of virtual photons and messenger particles. I feel the aether was just dreamed up too soon; in an era of empiricism where hard nosed physicists tried to find it and found it apparently did not exist and that was good enough. Apparently the aether might fair better today if it were a new concept. Where will it all end.

Richard Hull
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Fusion is the energy of the future....and it always will be
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Re: The neutron as a particle - my thoughts

Post by grrr6 » Wed Feb 26, 2003 9:12 pm

my point was that, if the neutron were just a proton and a neutron, its mass would be .8 MeV lower than it is measured to be. There has to be something else in there, unless of course we have measured its mass wrong. It could be possible.

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