Classification of Elastic and Inelastic scattering

In summary, the conversation discusses the confusion surrounding the terminology of elastic and inelastic in the context of interactions such as Rayleigh, photoelectric, compton scattering and pair production. The main questions raised are whether elastic is equal to coherent and inelastic is equal to incoherent, whether kinetic energy is conserved in elastic collisions involving photons, and whether inelastic processes require a threshold energy. The conclusion is that elastic scattering preserves kinetic energy while inelastic scattering does not, and that this applies to interactions such as Rayleigh and Thomson scattering as being elastic, and photoelectric, compton and pair production as being inelastic.
  • #1
abotiz
72
0
Hi,

I am slightly confused regarding the termenology elastic and inelastic. My focus is on the interactions, Rayleigh, photoelectric, comptonscattering and pair production. I have read around the internet and have some question I did not fully got answered.

1) Is Elastic = Coherent and Ineleastic = Inchoherent?

2) Elastic is a process where the kinetic energy is conserved? This confuses me when one is dealing with photons because they have no mass so a kinetic energy is non existant?

3) Inelastic, neither the momentum nor the kinetic energy is preserved?

4) Inelastic is usually a process that needs a threshold energy?

So if the above is true, then;
Rayleigh and Thomson scattering is the only coherent/elastic scattering, and photoelectric + compton + pairproduction are incoherent/inelastic scattering?

Thank you!
 
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  • #2
Yes, the terminology can be confusing since these terms are defined in slightly different way depending on context. The simplest definition is that an elastic collision is one that preserves total kinetic energy. Note that all of a photon's energy is considered kinetic energy since none of it is due to it's mass. Kinetic energy = Total energy - mass energy - potential energy (if any).
 
  • #3
Comparing this with classical terminology can be a bit confusing.

Elastic scattering is when the initial and final states are identical. This means the kinetic energy is conserved. (Photons have kinetic energy. In fact, they have only kinetic energy. Take this question to the SR/GR forum if you're still confused.)

Inelastic scattering is when initial and final states are different. In these processes kinetic energy is not conserved.

So eg. e+e- -> 2 photons is inelastic, and e + photon -> e + photon is elastic.

So yea, basically, you are right.
 

1. What is the difference between elastic and inelastic scattering?

Elastic scattering refers to a type of scattering where the incident particle (such as a photon or an electron) is scattered off an object without losing any energy. In other words, the kinetic energy of the incident particle before and after the scattering remains the same. In contrast, inelastic scattering involves the transfer of energy between the incident particle and the object, resulting in a change in the kinetic energy of the incident particle.

2. How is elastic scattering used in scientific research?

Elastic scattering is widely used in scientific research to study the properties and structure of materials. By analyzing the scattering pattern of incident particles, scientists can gather information about the size, shape, and composition of the object being studied. This technique is commonly used in fields such as material science, biology, and physics.

3. What factors affect the scattering behavior of particles?

The scattering behavior of particles is affected by factors such as the type of incident particle, the energy of the incident particle, the size and composition of the object being scattered, and the angle at which the scattering occurs. These factors can influence whether the scattering is elastic or inelastic, as well as the intensity and direction of the scattered particles.

4. Can inelastic scattering be used to identify unknown materials?

Yes, inelastic scattering can be used to identify unknown materials. Inelastic scattering techniques, such as Raman spectroscopy, use the energy transfer between the incident particle and the object to identify the chemical composition of the material. By analyzing the scattered spectrum, scientists can determine the molecular structure and composition of the unknown material.

5. What are some real-world applications of elastic and inelastic scattering?

Elastic and inelastic scattering have many practical applications in various fields. In material science, they are used to study the properties and structure of materials, as well as for quality control purposes. In biology, scattering techniques are used to study the structure of biological molecules and proteins. In the medical field, inelastic scattering is used in techniques such as X-ray imaging and MRI to diagnose and study diseases. Additionally, elastic and inelastic scattering are used in environmental monitoring and in the development of new technologies such as solar panels and semiconductors.

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