I was just wondering, is the radius of a proton and neutron EXACTLY equal? I know that the neutron is very slightly heavier than the proton, but are they exactly of equal radius?

8X10^-16 Meters is what www.physlink.com says the radius of both protons and neutrons are but i get the feeling that it is a rounded off figure.

most scientific read outs that are acurate look more something like 1.6726231*10^-27 kg

The above mentioned value is the mass of a proton

1.6749286X10^-27 kg is the mass value of the heavier neutron.

Can anyone tell me if the radius of neutrons and protons are in fact exactly identical?


David

A neutron is basically a proton with an electron in close orbit.

They're not actually shaped like a ball in the classical sense. Both are made up of quarks that move around each other. So essentially, the radius is the orbit of the quarks.

This electron in close orbit with the neutron, is it a meson? If so which nuclear force does it belong to? Weak or strong?

I was under the impression that mesons ocilate between protons, making each one a neutron at each pass.


David

This electron in close orbit with the neutron, is it a meson?

They are all fermions. Neutrons and protons are hadrons. The electron is a lepton.

If so which nuclear force does it belong to? Weak or strong?

Electrons are held in orbit by the electrical Coulomb force between charged particles. Neutrons are bound by the weak force.

Particle........Radius(m).....Mass(kg)

Electron.......0.00..............9.1094E-31
Proton.........8.00E-16.......1.6726E-27
Neutron.......8.00E-16.......1.6749E-27

Proton mass + electron mass = 1.6735E-27 kg only !!
Actual Neutron mass...............= 1.6749E-27 kg

If a neutron truely is a proton with an electron in close orbit...

How come it has more mass than a proton and an electron combined?


Regards, David

(Q):

In this instance I'm afraid you're on the wrong track.

<i>A neutron is basically a proton with an electron in close orbit.</i>

No it isn't. Both neutrons and protons are made up of quarks.

It is very hard to pin down the radius of a neutron or proton, since the concept is ill-defined at the quantum level. A neutron, for example, is in a sense a smeared-out fuzzy ball of probability. It is not a solid, billiard-ball-like object.

The strong nuclear force which holds protons and neutrons together operates at distances less than about 10^-15 m. The radius values quoted are a kind of average which is a bit less than that.

Incidentally, electrons are currently thought to have zero radius - literally no size.

I'm not sure I can see electrons having no radius (little joke there).

............LENGTH......MASS

.............m................kg

Plank....1.62E-35.....2.1767E-08

But protons and neutrons are heavier and bigger than plank length and mass. Surely that allows them to have a specific radius?

But getting back to the question... do protons and neutrons share identical radius? Or is the Neutron slightly larger?


I remembered reading somewhere that mesons ocilate between protons and to make each proton a neutron during each pass... so a heliem neucleus is made up of protons that constantly swap states with other protons... taking turns to become a neutron each time a negative charge messon takes turns on the diferent protons.

I was under the impression that mesons are electrons that exist within the nucleus.


David

How could an electron have no radius/size if it has mass?

Electrons are smaller than plank's length so it plays by the rules of quantum theory and not newton's rules.

A black hole is the same thing... it has no radius... dont confuse this with the schwartschild radius. The singularity it self has no radius but there is a specific mass and gravitational level.


Electrons are points like black holes are but electrons unlike blackholes exist in several points in space simultaneusly. This is called quantum weirdness.

Electrons ocupy several points in space and these points are suficiently spread out to be wider than the schartschild radius of the electron so it doesnt colapse into a black hole.

Hope this helps! And if you dont understand half of the terms i used... i suggest you do your own research at http://www.physlink.com

Anyways! Having said all that... can some one please tell me if neutrons do infact have equal radius to protons? And please explain why or why not.

I can see there are already several diferences in opinions about this please continue to discuss this as i will monitor your replies between each other.

Also please read all the replies here before you post so that you can take into account of everything i have already said. Such as the numbers and arguements i have already pointed out.


Regards, David

James R

(Q):

In this instance I'm afraid you're on the wrong track.

A neutron is basically a proton with an electron in close orbit.

No it isn't. Both neutrons and protons are made up of quarks.

I said they were made up of quarks and so did you. How is that the wrong track?

Q said:

Neutrons are bound by the weak force.

Whoops! I see now. You're right James. My mistake. Neutrons are bound by the 'strong force' which occurs via exchange of mesons which are the basic one quark/one antiquark zero spin bosons.

Sorry about that DarkDave.

James said:

It is very hard to pin down the radius of a neutron or proton, since the concept is ill-defined at the quantum level.

Not really. The radius of a neutron can be derived from the potential energy using the orbital conception that a neutron is made of a core and a shell. This approach provides a very simple way to get the neutrons classical radius, whose value is in agreement with experimental data.

If a neutron truely is a proton with an electron in close orbit...

How come it has more mass than a proton and an electron combined?

When a neutron decays into a proton, an electron is 'fired' out moving at a high speed thus creating a lot of kinetic energy. The kinetic energy of the fast moving electron and the energy of the neutrino appear as "binding energy." All three particles (proton, electron, antineutrino) can share this energy in many ways and in doing so take on a range of values while still obeying energy and momentum conservation. Some energy is also carried away during the decay hence there will be a difference in the masses.

Nuetrons are essentailly protons with a close orbiting electron in the orbital conception. And as James R has pointed out, the electron basically has no radius and at the quantum level is in a sense a smeared-out fuzzy ball of probability. That is why their radii are almost the same.

Hi Dave, In physics singularities and points are not the same.

(Q):

Let me repeat - your idea that a neutron is somehow made of an electron and a proton is completely incorrect.

Protons and neutrons are both made of up and down quarks. A proton consists of two up quarks and one down quark (uud), whereas a neutron consists of two down quarks and one up quark (udd). <b>A neutron has no electrons inside it.</b>

For others:

I thought I'd already answered the radius question. Since a neutron is not a solid ball, but actually a group of three particles, the radius is difficult to define. The values quoted are always an average value. I <i>think</i>, for what it's worth, that the radii of a proton and a neutron in these terms are approximately equal, but it's something you'll almost never hear a physicist talking about because the concept is ill-defined at the quantum level.

But the radius of an electron, which has mass?

The radius of an electron is beyond our ability to probe. There's a theoretical construct called the <i>classical electron radius</i> which is useful in some instances, but isn't a real measure. I can't remember its exact value.

More bloody unanswered questions! Physics needs to get itself sorted out PDQ! :p

When this question came up about radii sizes I said, "Well let me look and see what I can find". I found gobs of info but nowhere did I find it flat out stated that the neutron or proton is of such and such size. It became appearent after a while that it is danced around because it is a vague value. This tends to support James R's explainations in my mind. If there was a flat out "value" it would say so. That it doesn't speaks volumes for what James R has put forth...

Electrons and Blackhole Singularities are not the same thing. I never implied that.

However... Electrons and Blackhole singularities ARE points but of a diferent kind of points.

The Electron's virtual radius (area of space ocupied by fuzzy probabilities) cover an area of space larger than it's own Schartschild radius... this is why it does not colapse into a black hole singularity.

The black hole singularity on the other hand has too much mass to exist in a quantum state of ocupying multiple points in space simultaneusly in a fuzzy probability nature. It's mass exeeds plank's mass.

The black hole exists at a single point in space with a 100% probability of being there. The Electron exists as multiple points in space with varying probabilities at various points. Both however... have one thing in common... they are both points and therefore have no actual radius although they both have mass.


David

Also regarding the gentlemen's comment that the thread not having any values of radiuses... kindly scroll up... i have as a matter of fact stated several times the radiuses that are officialy stated in

http://www.physlink.com

click on the REFERENCE SECTION and click on REFERENCES
also the section there called CONSTANTS are also useful.

All my values were picked from there. For some reason... the proton and neutron radiuses listed there are identical, but they are only up to 4 decimal places.

Im getting the impression now that a Neutron contains a proton , electron and an anti-neutrino??? is this what youre all implying?


Regards, David

Im getting the impression now that a Neutron contains a proton , electron and an anti-neutrino??? is this what youre all implying?

That is true, metaphorically. The neutron is made up of quarks, however the neutron decays into a proton, creating and releasing the antineutrino and electron. The proton remains and consists of quarks.

If a neutron is made out of three quarks, and a proton is made out of three quarks, then why does a neutron decay into a proton, electron, and antineutrino???

Does that mean that an electron is made of quarks, as well?? If the electron is made of fragments of quarks, then do quarks, as independent particles, really exist???

Or is the quark theory another failed attempt to explain the structure of nucleons???

All feedback is appreciated.


Tom

If a neutron is made out of three quarks, and a proton is made out of three quarks, then why does a neutron decay into a proton, electron, and antineutrino???

Essentially, a down quark is transformed into an up quark. But the Standard Model however, does not answer the question, why.

Q i think youre missing the point of the question, i understand what his getting at...

The neutron according to the experts here are made out of 3 QUARKS right??? Is that all? Just 3 Quarks? Is there not an electron or neutrino orbiting with the 3 Quarks too? or inside of the quarks.

Where did the electron and neutrino come from? You said they are made up of 3 quarks... and nothing more.

If i say i have 3 marbles in a bag and pull out a rabbit plus the 3 marbles... where did the rabit come from?

Good question, i like to know the answer my self... i suspect youre going to tell us that they are converted into matter from energy of the Quarks orbit or something??

See, ... I thought that a neutron was just another proton with an electron near it... but now u tell us that it's made up of diferent kinds of quarks than the protons! So does that mean that the electron in close orbit (meson) flips the switch on the quark and turn it into a down or up quark??


Sincerely, David

Please read This description of the Standard Model (http://particleadventure.org).

A neutron is made of 3 quarks and 3 gluons. The gluons carry the strong nuclear or colour force. As darkDAVE correctly intuits the mass of the glouns is (crudely) converted to energy and thence to an electron, proton and anti-neutrino. It is more correct to think in terms of quantum properties changing and being conserved.

No doubt some one, Adam probably, will ask the reasonable question, why? No one currently can explain why the Standard model behaves as it does. It is purely a description of what happens and not an explanation. That is in the realms of supersymmetry and grand unification, as yet unknown.

As James R points out, the neutron is made of particles obeying rules of QM and has no definite radius. Same as the electron.

The gluons carry the strong nuclear or colour force. As darkDAVE correctly intuits the mass of the glouns is (crudely) converted to energy and thence to an electron, proton and anti-neutrino.

Don't you mean the gluon energy force is converted into matter in the form of an electron and an anti-neutrino?

The proton was always there was it not? I thought the Proton + the Gluon = Neutron?

1) btw, why anti-neutrino? why not Neutrino?

2) Whats the diference between the two?

3) How can there be an anti-particle for a neutrino that has no charge?

Also...

4) How much mass does a neutrino have?

5) How big is it's radius? (im assuming it's smaller than plank's length?)


Im under the impression that the mass of this particle is undiscovered?

6) Does a Neutrino exist in a cloud of probabilities like an electron?

7) Exactly how fast in terms of c does a neutrino particle travel?

Thanks for the link u gave us... it's always nice to add another useful reference to my favorites folder...

I'll try and search thru it but atm, a lot of the analogies are beyond me.


David

The process by which a neutron decays into a proton, an electron and an antineutrino is called <i>beta decay</i>. It is due to the weak nuclear force.

In the interaction, a down quark is converted into an up quark. In order to conserve energy, momentum and various other quantum numbers an electron and antineutrino are produced in the process. It is an antineutrino rather than a neutrino because a quantity called the lepton number is conserved in the interaction.

All particles have antiparticles, though some particles are their own antiparticles. Antiparticles of charged particles always have the opposite charge.

Nobody knows how much mass a neutrino has, although there are upper limits on how much mass they can have, established by experiment. Originally, they were thought to have zero mass, but the neutrino oscillation experiments seem to indicate otherwise.

Hi Dave, Sorry but by your post I am still getting the impression that your idea of a singularity and a point are too close together.

A point is a point an epsilon if you wish.

A singularity is an edge it has no points.





The neutrino has been "weighed"


THE lightest known particle in the Universe has been weighed for the first time.

Scientists from Cambridge University have calculated that the neutrino, the tiniest and most elusive of the sub-atomic particles that make up matter, weighs less than a billionth of the mass of a hydrogen atom, the smallest and simplest of all the elements. That puts the maximum mass of the neutrino at 1.8 x 10-36kg, or 0.0000000000000000000000000000000000018kg.

<A HREF="http://www.thetimes.co.uk/article/0,,2-262297,00.html" target=new><FONT COLOR=ff0098 size=+1> from the times</FONT></A>

Originally posted by John Devers

Scientists from Cambridge University have calculated that the neutrino, the tiniest and most elusive of the sub-atomic particles that make up matter, weighs less than a billionth of the mass of a hydrogen atom, the smallest and simplest of all the elements. That puts the maximum mass of the neutrino at 1.8 x 10-36kg, or 0.0000000000000000000000000000000000018kg.


Dumb-arse. I could have told them that. All they had to do is ask. Would have saved them heaps of money and effort. :p

Thanks for that! MR John Devers. WOW!! Those figures are sooo beatiful :)

I'll have to enter it into my research spreadsheet :)

John, doesnt the fact that singularities have only one dimension qualify it as a point?

And also... James said that the neutron decays into a proton and releases a single electron and anti-neutrino... but wouldnt this process have to be re-curing within the neucleus of a single stable atom?

I thought that protons and neutrons CONTINUALY swap into each other's role?

eg...

1) Messon leaves neutron and goes to proton and proton turns to neutron

2) Neutron is now mesonless... and becomes a proton.

3) Go back to step 1.

Wouldnt the atom continualy loose neutrinos this way? Or are they neutrinos part of mesons?

Im getting the impression here that

Mesons consist of:

1) An Electron
2) An anti-neutrino

Is this correct?

What makes an anti-neutrino diferent from a neutrino? Do anti-neutrinos have negative mass or something? :)

Or do they spin diferently to ordinary neutrinos?


David