When they meet, the positron and the electron, which are Antiparticles of each other, destroy themselves mutually, they annihilate. Two annihilation gamma with equal energy are also emitted back to back. They carry each 511 keV, that is the mass energy of the two particles which is thus restored.

For pair production to occur, the electromagnetic energy, in a discrete quantity called a photon, must be at least equivalent to the mass of two electrons. The positron that is formed quickly disappears by reconversion into photons in the process of annihilation with another electron in matter.

Annihilation, in physics, reaction in which a particle and its antiparticle collide and disappear, releasing energy. The most common annihilation on Earth occurs between an electron and its antiparticle, a positron.

Quarks and antiquarks of the same type do indeed annihilate. If they’re of different types, then the interaction is a bit more nuanced. Regardless, none of the mesons are stable; they all decay in a fraction of a second after they form (although some decay much faster than others).

A photon comes from the left of the diagram and decays into an electron and an anti-electron. At the same time, another photon comes from the right and turns into an electron and an anti-electron. Each anti-electron collides with an electron, they mutually annihilate and turn back into a new photon.

If two photons head towards each other and they both turn into electron/anti-electron pairs at about the same time, then these particles can interact. Each anti-electron collides with an electron, they mutually annihilate and turn back into a new photon.

The answer is yes, photons may collide and produce other particles. One familiar reaction is the low-energy annihilation of an electron and an anti-electron (known as a positron)– the result is usually a pair of photons (sometimes you get more than two). The energies of the photons has to be really high, however.

In particle physics, every type of particle is associated with an antiparticle with the same mass but with opposite physical charges (such as electric charge). Some particles, such as the photon, are their own antiparticle.

positron

Some fermions are elementary particles, such as the electrons, and some are composite particles, such as the protons. According to the spin-statistics theorem in relativistic quantum field theory, particles with integer spin are bosons, while particles with half-integer spin are fermions.

Neutrinos have half-integer spin ( 12ħ); therefore they are fermions. Neutrinos are leptons. They have only been observed to interact through the weak force, although it is assumed that they also interact gravitationally.

Fermions are particles which have half-integer spin and therefore are constrained by the Pauli exclusion principle. Particles with integer spin are called bosons. Fermions include electrons, protons, neutrons.

The Higgs boson is the fundamental particle associated with the Higgs field, a field that gives mass to other fundamental particles such as electrons and quarks. A particle’s mass determines how much it resists changing its speed or position when it encounters a force.

There’s a limit to how big we can make a dark matter detector, based solely on engineering and cost constraints. But thankfully, according to a new paper recently appearing on the online preprint site arXiv, there’s a gigantic dark matter detector that’s been collecting data for millions of years.

Even when something is dark, when hit by light, baryonic matter will become luminous. Dark matter is therefore non-baryonic, travelling faster than light and has a mass half that of a photon.

The answer is yes, photons may collide and produce other particles. One familiar reaction is the low-energy annihilation of an electron and an anti-electron (known as a positron)– the result is usually a pair of photons (sometimes you get more than two). This happens all the time in particle physics experiments.

When antimatter and regular matter touch together, they destroy each other and release lots of energy in the form of radiation (usually gamma rays). If it’s a large amount, the gamma radiation would be enough to kill you or cause serious harm. Note, however, that antimatter only destroys matter in equal amounts.

Antimatter may exist in relatively large amounts in far-away galaxies due to cosmic inflation in the primordial time of the universe.

Given that there is about 700 times as much normal matter as there are black holes, this can’t be where the antimatter is hiding; antimatter didn’t form black holes. But we had another way of knowing that: the laws of physics have symmetries between the way matter and antimatter are allowed to behave.

The Big Bang should have created equal amounts of matter and antimatter in the early universe. But today, everything we see from the smallest life forms on Earth to the largest stellar objects is made almost entirely of matter. Comparatively, there is not much antimatter to be found.

Primary evidence for dark matter comes from calculations showing that many galaxies would fly apart, or that they would not have formed or would not move as they do, if they did not contain a large amount of unseen matter.

What if anti-atoms gravitationally repelled each other? In that case, an antimatter universe would never form stars or galaxies. Our antimatter universe would simply be filled with traces of anti-hydrogen and anti-helium, and nothing would ever look up at the cosmic sky.

These positrons—antimatter particles with the same mass as an electron, but with a positive charge—have since puzzled scientists with the cosmic mystery of their origins. Researchers have proposed several possible sources of the positrons.

If dark matter is made of regular WIMPS, when two WIMPs meet at the center of a star they would destroy one another, because they are their own antimatter counterparts. If two of these like particles met, they would not annihilate, so dark matter would simply build up over time inside the star.

This positron signature could have a variety of causes, but a prime candidate is dark matter, the intangible stuff thought to make up about 98 percent of all matter in the universe. When two dark matter particles collide they can sometimes destroy each other and release a burst of energy that includes positrons.