Time taken to absorb neutrons,photons

  • Thread starter kurious
  • Start date
  • Tags
    Time
In summary, the conversation discusses the difference in momentum change and absorption time between particles and photons when they interact with a surface. It is mentioned that photons do not bounce but are absorbed and then re-emitted. The topic of neutrons and their ability to be at rest in reality is also brought up. Finally, the conversation briefly touches on the timescale for a photon and an electron to reflect off a surface.
  • #1
kurious
641
0
How long do particles take to change their mometum when they "bounce"
off a surface and when they are absorbed by a surface?
Do photons have a noticeably different "bounce" and absorption time to particles with rest mass?
Can a neutron have a rest mass and be at rest in reality rather than just in theory?
 
Physics news on Phys.org
  • #2
Photons cannot ever change their speed, so they do not bounce. They are absorbed by an atom, then the atom emits a new photon in another direction.

Neutrons have zero residual (external) electronic charge, but their component quarks can interact either via the electromagnetic or strong forces with other particles. Depending upon the angles involved in the collision, I'd expect a neutron to be either be scattered by a nucleus ("bouncing"), or captured by a nucleus.

Neutrons can certainly be at rest in reality.

- Warren
 
  • #3
I meant to ask: can a neutrino be at rest in reality and not just in theory?
 
  • #4
kurious said:
I meant to ask: can a neutrino be at rest in reality and not just in theory?

If the neutrinos have even a small mass, the answer is yes. Nobody has trapped one, but someday it may be done.
 
  • #5
Over what sort of timescale does a photon reflect off a mirror back along the direction it came from, and the same for an electron "reflected" by a solid surface.
 
  • #6
As has been said, the photon doesn't reflect. It's absorbed, then a new photon is emitted. I suppose the time scale is comparable to the lifetime of an excited atomic state, something on the order of nanoseconds or less I believe. As for an electron, this can be treated clasically, and I think it depends on the properties of the reflecting medium.
 

1. How does the time taken to absorb neutrons affect nuclear reactions?

The time taken to absorb neutrons can significantly impact nuclear reactions. Neutrons must be absorbed within a certain time frame for a chain reaction to occur. If the absorption time is too short, the reaction will not be sustained and if it is too long, the reaction can become uncontrollable.

2. What factors influence the time taken to absorb photons?

The time taken to absorb photons is influenced by several factors such as the type of material the photons are passing through, the energy level of the photons, and the density of the material. Higher energy photons are typically absorbed more quickly than lower energy photons, and denser materials will absorb photons faster than less dense materials.

3. Does the time taken to absorb neutrons and photons differ for different materials?

Yes, the time taken to absorb neutrons and photons can vary greatly depending on the material. Different materials have different atomic structures and properties that can affect how quickly they absorb neutrons and photons. For example, materials with a higher atomic number will usually absorb neutrons more quickly than materials with a lower atomic number.

4. How is the time taken to absorb neutrons and photons measured?

The time taken to absorb neutrons and photons can be measured using various techniques such as time-of-flight measurements and pulse shape analysis. These methods involve measuring the time it takes for particles to travel a specific distance or analyzing the shape of the radiation pulses to determine the absorption time.

5. Can the time taken to absorb neutrons and photons be controlled?

Yes, the time taken to absorb neutrons and photons can be controlled through various means such as using different materials, adjusting the energy level of the particles, and changing the density of the material. This can be useful in controlling nuclear reactions or in applications such as medical imaging where precise timing is crucial.

Similar threads

  • High Energy, Nuclear, Particle Physics
Replies
20
Views
2K
  • High Energy, Nuclear, Particle Physics
Replies
17
Views
2K
  • High Energy, Nuclear, Particle Physics
Replies
6
Views
1K
  • High Energy, Nuclear, Particle Physics
Replies
6
Views
662
  • High Energy, Nuclear, Particle Physics
Replies
7
Views
2K
  • High Energy, Nuclear, Particle Physics
Replies
4
Views
2K
  • High Energy, Nuclear, Particle Physics
Replies
2
Views
1K
  • High Energy, Nuclear, Particle Physics
Replies
8
Views
2K
  • High Energy, Nuclear, Particle Physics
Replies
15
Views
2K
  • High Energy, Nuclear, Particle Physics
Replies
3
Views
4K
Back
Top