B Input Energy of Radioactive Decays

  • Thread starter A M
  • Start date

A M

83
13
Summary
We know that nuclear fusion doesn't occur under normal conditions (e.g. in a helium balloon).
Because for the fusion of even the lightest elements (like hydrogen isotopes), fairly high energy is needed to 'break' the electrostatic repulsion barrier; although the released energy might be much higher.
But how about some radioactive decays? (α, SF, CD, ...)
Don't we need energy to to separate some nucleons of a radioactive nucleus?
 

Orodruin

Staff Emeritus
Science Advisor
Homework Helper
Insights Author
Gold Member
2018 Award
15,955
5,921
Yes, decays also need to overcome an energy barrier. This is done through quantum mechanical tunneling through the energy barrier. The difference in relation to fusion is that you only have a single radioactive particle and even a small probability per time of decaying will eventually lead to a decay. For fusion, the particles also need to meet up and when they do they have a single chance of tunneling through the energy barrier with very low proability.
 

A M

83
13
Yes, decays also need to overcome an energy barrier.
Would you please explain a little more?
 
1,366
135
For example of tunnelling where it is electrons that tunnel: we can observe both field emission and photoelectric effect. There is a definite energy barrier (as demonstrated by photoelectric effect) and yet electrons do have a small chance of getting through without any additional energy (as shown by field emission).
 

A M

83
13
Yes, decays also need to overcome an energy barrier. This is done through quantum mechanical tunneling through the energy barrier. The difference in relation to fusion is that you only have a single radioactive particle and even a small probability per time of decaying will eventually lead to a decay.
What does this probability come from? The higher energy they need to overcome that barrier or sth more complicated?
 
33,396
9,113
Yes. We had this discussion and even a graph for alpha decays in the previous thread. The energy released is not directly the same as the energy barrier but the two are closely linked.
 

A M

83
13
Thank you for the reply, but I haven't quite understood.
What if the nuclei were in a situation without that amount of energy available? The decay wouldn't occur?
 

Orodruin

Staff Emeritus
Science Advisor
Homework Helper
Insights Author
Gold Member
2018 Award
15,955
5,921
Thank you for the reply, but I haven't quite understood.
What if the nuclei were in a situation without that amount of energy available? The decay wouldn't occur?
Yes it would. It is quantum tunnelling. In quantum mechanics a particle can pass an energy barrier that it classically would not be able to.
 

Want to reply to this thread?

"Input Energy of Radioactive Decays" You must log in or register to reply here.

Related Threads for: Input Energy of Radioactive Decays

Replies
6
Views
951
  • Posted
Replies
2
Views
2K
  • Posted
Replies
1
Views
2K
  • Posted
Replies
15
Views
3K
Replies
2
Views
649
Replies
2
Views
3K
Replies
4
Views
949
  • Posted
Replies
4
Views
8K

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving
Top