The Naked Scientists

The Naked Scientists Forum

Author Topic: What's the point of a Neutron?  (Read 11235 times)

Offline dairving76

  • First timers
  • *
  • Posts: 1
    • View Profile
What's the point of a Neutron?
« on: 15/04/2015 02:01:29 »
Other than mass what does a Neutron provide to the Universe?
« Last Edit: 15/04/2015 12:37:03 by evan_au »


 

Offline evan_au

  • Neilep Level Member
  • ******
  • Posts: 4106
  • Thanked: 245 times
    • View Profile
Re: What's the point of a Nuetron
« Reply #1 on: 15/04/2015 12:32:13 »
Stable atoms larger than Hydrogen.
- Without the neutrons to hold the nucleus together, Helium or higher elements would blow themselves apart by electrostatic repulsion.
- We would not exist

The Sun that provides light, heat and energy on Earth.
- Without Hydrogen fusing to Helium, the Sun would not glow.
- We would not exist

Nuclear Power The neutron is able to sneak past the strong electrostatic field surrounding the uranium nucleus, and trigger a chain reaction.

Pulsars: these are Neutron stars
- They have proved useful in testing various aspects of Einsteins theory of relativity
- Some researchers are trying to use them to detect gravitational waves in deep space
- Pulsars were used to define the location of Earth on the Voyager spacecraft (just in case some alien discovered it, someday)

One more critter in the Subatomic Zoo
« Last Edit: 16/04/2015 22:23:30 by evan_au »
 

Offline alancalverd

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 4701
  • Thanked: 153 times
  • life is too short to drink instant coffee
    • View Profile
Re: What's the point of a Neutron?
« Reply #2 on: 16/04/2015 00:15:23 »
Neutron diffraction and radiography.

Isotopes.

Radionuclides.

Activation analysis and neutron capture radiotherapy.
 

Offline PmbPhy

  • Neilep Level Member
  • ******
  • Posts: 2760
  • Thanked: 38 times
    • View Profile
Re: What's the point of a Neutron?
« Reply #3 on: 16/04/2015 16:50:25 »
Quote from: dairving76
Other than mass what does a Neutron provide to the Universe?
Welcome to the forum.

As evan_au indicates, the neutron plays a formidable role in the universe. The strong force between nuclei (the neutron is a nuclei as is the proton) holds the nucleus together. Otherwise they would decay quite quickly.

You should keep in mind that any particular particle need not provide anything to the universe. They're just there, doing their thing! :)
 

Offline chiralSPO

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 1872
  • Thanked: 143 times
    • View Profile
Re: What's the point of a Neutron?
« Reply #4 on: 16/04/2015 16:53:00 »
A little typo I want to correct to avoid confusion:


As evan_au indicates, the neutron plays a formidable role in the universe. The strong force between nucleons (the neutron is a nucleon as is the proton) holds the nucleus together. Otherwise they would decay quite quickly.

You should keep in mind that any particular particle need not provide anything to the universe. They're just there, doing their thing! :)
 

Offline Cosmo

  • First timers
  • *
  • Posts: 1
    • View Profile
Re: What's the point of a Neutron?
« Reply #5 on: 25/04/2015 17:39:05 »
  The Neutron is absolutely critical to Nuclear binding - two protons repel without a neutron.  Except in the case of hydrogen and Helium  there needs to be at least as many Neutrons as protons to form a stable nucleus.  A plot of Z (# of Protons) vs N (number of neutrons) for stable elements diverges from the straight line N = Z  The heavier the nucleus, the greater the divergence.  For the light elements, the most stable configurations tend to have equal numbers of protons and neutrons
 

Offline PmbPhy

  • Neilep Level Member
  • ******
  • Posts: 2760
  • Thanked: 38 times
    • View Profile
Re: What's the point of a Neutron?
« Reply #6 on: 26/04/2015 02:58:09 »
Welcome to the forum, Cosmo!  :)
Quote from: Cosmo
  The Neutron is absolutely critical to Nuclear binding - two protons repel without a neutron.
This was covered in my last post. Did you read that one? I.e. in post #3 I wrote
Quote
The strong force between nuclei (the neutron is a nuclei as is the proton) holds the nucleus together. Otherwise they would decay quite quickly.
 

Offline syhprum

  • Neilep Level Member
  • ******
  • Posts: 3817
  • Thanked: 19 times
    • View Profile
Re: What's the point of a Neutron?
« Reply #7 on: 26/04/2015 07:05:15 »
Did our universe begin with only protons, anti protons, electrons an anti electrons ?.
I have the very na´ve view that the neutron is a proton that somehow has an electron forced into it that only survives when it has proton companions otherwise ejects the electron after 15 minutes or so. 

PS if it all began as a soup of quarks where did the electrons come from that are apparently not built from quarks but a different type of particle ?
 
« Last Edit: 26/04/2015 07:37:30 by syhprum »
 

Offline jccc

  • Hero Member
  • *****
  • Posts: 990
    • View Profile
Re: What's the point of a Neutron?
« Reply #8 on: 26/04/2015 07:18:52 »
  The Neutron is absolutely critical to Nuclear binding - two protons repel without a neutron.  Except in the case of hydrogen and Helium  there needs to be at least as many Neutrons as protons to form a stable nucleus.  A plot of Z (# of Protons) vs N (number of neutrons) for stable elements diverges from the straight line N = Z  The heavier the nucleus, the greater the divergence.  For the light elements, the most stable configurations tend to have equal numbers of protons and neutrons

isn't proton contains 2 u quake and 1 d quake? how the 3 make up the proton? what's strong force up to? how neutron stables nucleus?

Welcome and thanks!
 

Offline evan_au

  • Neilep Level Member
  • ******
  • Posts: 4106
  • Thanked: 245 times
    • View Profile
Re: What's the point of a Neutron?
« Reply #9 on: 26/04/2015 21:56:22 »
Quote from: jccc
what's the strong force up to? How does a neutron stabilize the nucleus?
Both the proton & neutron feel the strong nuclear force of attraction. So a proton and a neutron together (Hydrogen 2 = deuterium) is stable.

However, protons also have a positive charge. Two protons repel each other strongly. So a proton and another proton together (Helium 2) is extremely unstable, ie the energy tied up in the electrostatic repulsion is so great that it overcomes the energy involved in the strong nuclear attraction.

If you have two protons and a neutron, the neutron adds some attraction from the strong nuclear force, without adding to the electrostatic repulsion, so Helium 3 is stable.

In general, it takes slightly more neutrons than protons to make a stable nucleus (this effect is more obvious for nuclei the size of Carbon and larger, where carbon 12 & 13 are stable; carbon 14 is moderately stable, with a half-life in the thousands of years).
 
 

Offline jccc

  • Hero Member
  • *****
  • Posts: 990
    • View Profile
Re: What's the point of a Neutron?
« Reply #10 on: 27/04/2015 04:50:16 »
Quote from: jccc
what's the strong force up to? How does a neutron stabilize the nucleus?
Both the proton & neutron feel the strong nuclear force of attraction. So a proton and a neutron together (Hydrogen 2 = deuterium) is stable.

However, protons also have a positive charge. Two protons repel each other strongly. So a proton and another proton together (Helium 2) is extremely unstable, ie the energy tied up in the electrostatic repulsion is so great that it overcomes the energy involved in the strong nuclear attraction.

If you have two protons and a neutron, the neutron adds some attraction from the strong nuclear force, without adding to the electrostatic repulsion, so Helium 3 is stable.

In general, it takes slightly more neutrons than protons to make a stable nucleus (this effect is more obvious for nuclei the size of Carbon and larger, where carbon 12 & 13 are stable; carbon 14 is moderately stable, with a half-life in the thousands of years).

Evan, thanks!

if there is a strong force holding protons together, why need neutrons for?

proton carries +1, neutron carries 0, how they attract each other? gravity?

if protons and neutrons can form a group, why need a strong force to make stable nucleus?

what's the mechanism/source of strong force? why is it has such a short range? isn't em force is long range force? if strong force is not em force, how can it act on charged protons?
 

Offline PmbPhy

  • Neilep Level Member
  • ******
  • Posts: 2760
  • Thanked: 38 times
    • View Profile
Re: What's the point of a Neutron?
« Reply #11 on: 27/04/2015 11:01:22 »
Quote from: jccc
if there is a strong force holding protons together, why need neutrons for?
Because the strong force isn't sufficient to hold protons together. The strong force is short range only acting on the nearest nucleon. The electrical repulsion of the protons would rip larger nuclei apart if it wasn't for neutrons there acting like a nuclear "glue."

Quote from: jccc
proton carries +1, neutron carries 0, how they attract each other? gravity?
neutrons attract each other by the strong force.

Quote from: jccc
what's the mechanism/source of strong force?
Your fortunate this time in that we know what the mechanism that does this is. If the strong force is acting between two hadrons then its mediated by the exchange of massive mesons. If the strong force is acting between two quarks then its mediated by two massless quarks.
« Last Edit: 27/04/2015 11:15:39 by PmbPhy »
 

Offline jccc

  • Hero Member
  • *****
  • Posts: 990
    • View Profile
Re: What's the point of a Neutron?
« Reply #12 on: 27/04/2015 14:36:33 »
Pete, thank you.

i know all those, everyone can wiki knows all those.

your answers are not clear enough, what's the source of strong force?

what's the nature and mechanism?

what's the prove?

why strong force only exist within nucleus? is it em force?

thank you again!
 

Offline chiralSPO

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 1872
  • Thanked: 143 times
    • View Profile
Re: What's the point of a Neutron?
« Reply #13 on: 27/04/2015 15:03:08 »
Pete, thank you.

i know all those, everyone can wiki knows all those.

your answers are not clear enough, what's the source of strong force?

what's the nature and mechanism?

what's the prove?

why strong force only exist within nucleus? is it em force?

thank you again!

as you say, anyone with access to wikipedia has access to the answers to these questions.

http://en.wikipedia.org/wiki/Strong_interaction
 

Offline PmbPhy

  • Neilep Level Member
  • ******
  • Posts: 2760
  • Thanked: 38 times
    • View Profile
Re: What's the point of a Neutron?
« Reply #14 on: 27/04/2015 15:45:00 »
Quote from: jccc
Pete, thank you.

i know all those, everyone can wiki knows all those.
Then shut up and stop asking.

Quote from: jccc
your answers are not clear enough, ..
Actually the fact is that you don't have the skills to grasp it.

Quote from: jccc
what's the source of strong force?
I already told you. The source if the strong force in particle physics is said to be the fact that the force is mediated by mesons (for hadrons) or gluons (for quarks). THAT is the mechanism. Don't blame me if you're unable to grasp that as being the mechanism. Blame your lack of education on that.

Another thing you've never been able to grasp due to your refusal to read a physics text is that in the field of science nothing is ever "proved" to be right. All that can be done is to make predictions and verify that the predictions agree with experiments. If they don't then the theory is wrong. If they do then scientists have more confidence in the theory. Since ever time we see you ask for proof in this forum, and you've asked countless times, and we've told you this, also countless times, it's clear that this is yet another thing you'll refuse to remember/learn

Quote from: jccc
why strong force only exist within nucleus? is it em force?
Because mesons are massless particles the force is short range. The strong force has a range of only about the diameter of a nucleon.

If you think that I'm going to give a derivation or every question you pose or correct every nonsensical statement you make then you're deluded. That you keep asking is merely a result of the fact that you don't want to do the work required to learn the subject. You want everyone else to do the work for you and spoon feed you everything you have a question on. Forget it. Someone would have to be an idiot to do that. We've done the work to learn physics. Do the same.

This forum was not created so you could come here and ask every single question you could think of to understand physics. This is a Discussion Forum created for people who wish to discuss what they have learned through hard work. We're not about to feed your lazy tendencies and make you even more lazy.
« Last Edit: 27/04/2015 15:49:39 by PmbPhy »
 

Offline jccc

  • Hero Member
  • *****
  • Posts: 990
    • View Profile
Re: What's the point of a Neutron?
« Reply #15 on: 27/04/2015 16:45:26 »
Pete,

if i am that lazy, who debunked big bang theory?

do you still think big bang theory is correct?

no matter how you think about me, i still deeply appreciate your every post, and this awesome forum!

if i can find answers from wiki, i will not need any help! please agree with me on this.





 

Offline PmbPhy

  • Neilep Level Member
  • ******
  • Posts: 2760
  • Thanked: 38 times
    • View Profile
Re: What's the point of a Neutron?
« Reply #16 on: 28/04/2015 00:51:14 »
Quote from: jccc
if i am that lazy, who debunked big bang theory?
What on Earth do these questions have about you being too lazy to pick up a text on math and physics and start learning physics like I did?

Nobody debunked the Big Bang theory . Where would you get such an idea from?

Quote from: jccc
do you still think big bang theory is correct?
Physics is not about beliefs like what we think is true or think is false. It's about experiment, observation and confidence. I have confidence that the Big Bang theory is accurate description of nature.

Quote from: jccc
if i can find answers from wiki, i will not need any help! please agree with me on this.
The term "need" is defined as follows. From: http://www.merriam-webster.com/dictionary/need
Quote
: a situation in which someone or something must do or have something

: something that a person must have : something that is needed in order to live or succeed or be happy

: a strong feeling that you must have or do something
which one applies to your question?
 

Offline UltimateTheory

  • Sr. Member
  • ****
  • Posts: 107
  • Thanked: 1 times
    • View Profile
    • Ultimate Theory of the Universe
Re: What's the point of a Neutron?
« Reply #17 on: 28/04/2015 18:01:26 »
I have the very na´ve view that the neutron is a proton that somehow has an electron forced into it that only survives when it has proton companions otherwise ejects the electron after 15 minutes or so. 

Then look at Beta Decay Plus, in which proton turns to neutron, by emission of positron and neutrino..

http://en.wikipedia.org/wiki/Positron_emission

If neutron is proton+electron, then how can proton change to neutron, in proton-rich isotopes.. ? Basically reverse situation.
Going your above path of thought, proton would be neutron with positron..
But that's not the case.

PS if it all began as a soup of quarks where did the electrons come from that are apparently not built from quarks but a different type of particle ?

Electrons can be created in pair production from photons with energy exceeding 1.022 MeV.
 

Offline evan_au

  • Neilep Level Member
  • ******
  • Posts: 4106
  • Thanked: 245 times
    • View Profile
Re: What's the point of a Neutron?
« Reply #18 on: 28/04/2015 22:27:37 »
Hi...  I saw this in a post above:
Quote from: PmbPhy
Because mesons are massless particles the [strong nuclear] force is short range

Please explain - I thought "Because photons are massless the electromagnetic force is long range"?

Wikipedia says meson mass is ≥ 139 MeV/c2.

So it must be a typo: "because mesons are massive particles the [strong nuclear] force is short range"?
 

Offline PmbPhy

  • Neilep Level Member
  • ******
  • Posts: 2760
  • Thanked: 38 times
    • View Profile
Re: What's the point of a Neutron?
« Reply #19 on: 29/04/2015 08:00:07 »
Hi...  I saw this in a post above:
Quote from: PmbPhy
Because mesons are massless particles the [strong nuclear] force is short range

Please explain - I thought "Because photons are massless the electromagnetic force is long range"?

Wikipedia says meson mass is ≥ 139 MeV/c2.

So it must be a typo: "because mesons are massive particles the [strong nuclear] force is short range"?
Thanks. Yes. It was a typo. I had in mind to say "massive" but instead said "massless".
 

The Naked Scientists Forum

Re: What's the point of a Neutron?
« Reply #19 on: 29/04/2015 08:00:07 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums