# Simple question regarding annihilaion

• humsafar
In summary, when particles, such as a proton and antiproton, are annihilated, they release energy in the form of x gigaelectronvolts (GeV). If the particles are annihilated at 4 GeV instead of 2 GeV, the energy released will be double. However, this calculation is simplified in the center of mass system, which takes into account the energy and momentum of the particles. If the particles are at rest, the resulting energy will simply be twice their rest mass energy. However, in experiments, the particles are not at rest and their momentum contributes to the total energy released.
humsafar
if annihilation of particles(let's say proton-antiproton) releases x energy at 2 giga electron volts, then if we annihilate it at let's say 4 GeV, would we be getting double the energy?

also, i have seen the wikipedia page of annihilation of proton and antiproton which mentions the energy levels at 2 GeV but does not mention released energy at rest "clearly"...please help

The calculation is simplified in the c.m. system; proton and anti-proton have energy-momentum (E, p) and (E, -p). The sum ist (2E, 0), so 2E is the c.o.m energy. Of course E and p are related via E² - p² = m² where m is the rst mass m=938 MeV.

humsafar said:
if annihilation of particles(let's say proton-antiproton) releases x energy at 2 giga electron volts, then if we annihilate it at let's say 4 GeV, would we be getting double the energy?

also, i have seen the wikipedia page of annihilation of proton and antiproton which mentions the energy levels at 2 GeV but does not mention released energy at rest "clearly"...please help

If one could cause an annihilation with both particles at rest, the result is simply twice the rest mass energy (2*938 MeV ~2 GeV). However experimentally you send two streams of particles at some velocity toward each other, so the momentum at annihilation is not zero (rest momentum) and contributes to the total energy.

Thanks for the answers...but please try to explain in layman terms...I'm not a physicist by profession here...just doing my b.s in Computer science...I don't get the c.m system...

## 1. What is annihilation?

Annihilation is a process in which a particle and its antiparticle collide and are converted into energy in the form of photons.

## 2. What are antiparticles?

Antiparticles are the mirror image of particles, with the same mass but opposite charge. They are produced in high-energy collisions and can annihilate with particles of the same type.

## 3. How does annihilation occur?

Annihilation occurs when a particle and its antiparticle collide and their respective energies are converted into photons. This process follows the law of conservation of energy.

## 4. What is the significance of annihilation in physics?

Annihilation plays a crucial role in understanding the behavior of matter and energy in the universe. It is used in particle accelerators to study the properties of particles and their interactions.

## 5. Can annihilation be reversed?

No, annihilation is an irreversible process. Once a particle and its antiparticle annihilate, they are converted into energy and cannot be brought back into their original form.

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