Positron

A positron or antielectron is the antimatter counterpart to an electron. A positron has the equal or same mass as an electron and a spin of 1/2, but it has an electrical charge of +1. When a positron collides with electron annihilation, it results in the production of two or more gamma-ray photons.

Positron is also known as the positive electron, it is a positively charged subatomic particle having the same or equal mass and magnitude of charge as the electron and creates the antiparticle of a negative electron.

One of the two particles is called a positron or positron-electron; the other is called an electron antineutrino or antielectron. Each particle has the same rest mass as the electron, although the combined mass of a positron and an electron is much greater because the masses of the electron and the positron are one half of the mass of an electron. The positron has the same magnetic moment as an electron, but the positron is a much heavier, slower particle. They are opposites of each other (charge is the same, but the particles have opposite electric charges), and have opposite electric and magnetic moments. Since they have the same charge but opposite electric and magnetic moments, they are also mutually antipodal.

What is an Electron?

The electron is an elementary particle that plays a vital role in the branches of science and everyday life. The electron was first discovered by the English physicist Joseph John Thomson in 1897. An electron is a negatively charged subatomic particle. It can either be free or bound to the nucleus of an atom.

Electrons in atoms exist in spherical balls or various radii, representing the energy levels. The larger the spherical shell, the higher will be the energy contained in the electron.

Electron

Electrons are charged elementary particles. Each particle is composed of three parts: a particle with a negative charge, called the electron, called a negatively charged fermion, and an electromagnetic field with a magnetic field and an electric field called the electromagnetic field. The proton is composed of three quarks and gluons.

A proton's mass is four hundred times greater than an electron's mass; the proton weighs about while the electron weighs. The proton has an electric charge of a one-half unit of the charge of the electron.

Electron neutrinos are produced in nuclear interactions, mainly beta decay, and also as a byproduct of solar flares and other natural nuclear reactions. When an electron interacts with an antineutrino via a weak force, a new type of neutrino is produced.

Neutron

Neutrons are stable neutral particles. As with the proton, a neutron's mass is approximately four hundred times greater than an electron's mass. The neutron has an electric charge of zero. Unlike protons, neutrons have no strong interactions, except through gravity. Thus, neutrons are much less affected by gravity than protons, and hence, can be contained in small containers such as those made of graphite, beryllium, or lead.

Nucleon

The nucleon, nucleus, or proton-neutron nucleus is a fermionic bound state composed of a neutron and a proton (or a proton and a neutron). The nucleon contains the proton, and the neutron has a very similar structure. A nucleon contains three valence quarks and gluons. The proton and neutron form a nucleus, which has more mass than either nucleon alone.

For a given nucleus, the mass of a nucleon is usually much smaller than the mass of a nucleus. This is not true for all nuclei, however, as the mass of the nucleus is determined by the number of protons and neutrons within it.

All of the elementary particles that make up the nucleon have a charge. As each of these charges is compensated for by the other, there are no net electric charges within a nucleon. In addition to the three valence quarks that characterize the nucleon, it also has three sea quarks (i.e., a gluon) and three valence gluons. The nucleon can also be said to have a weak charge (with the proton's weak charge being approximately 2.3 times greater than the neutron's).

The proton-neutron nucleus has a half-integer spin.

Protons

Protons are a fermionic bound state of a down quark and an up quark (along with a gluon).

The proton has a negative electric charge, but no net charge. Protons are negatively charged because their quarks are charged negatively. Protons have a mass of approximately 1.7 million times that of a neutron. The proton has a strong force and a weak force that are the same as those that act on quarks, but the weak force acts on the electron and positron, and therefore the weak force on a proton differs in magnitude from the weak force on a quark. This is manifested in proton decay, as decay only involves the quarks and gluon. Also, although protons can be created, they cannot be destroyed: there is no weak interaction between a proton and an electron or a positron, so they do not mix. This is similar to the difference between electrical charge and mass.

Proton has a spin-off (half a unit). This is known as a superposition of two states:  in which the spin is aligned along the direction of the momentum (in the same direction as the electric charge) and in which it is antiparallel. The difference between the spin states (the spin projection) of the proton is known as the magnetic moment and is in the same direction as the electric dipole moment.

Protons that decay, such as those that decay to the positron and the neutrino, violate CP-symmetry. This is true of the decay p → e+ π+ν (branching ratio 0.7%), but it is also true of p → γ + π+ν, where the pion is a charged particle.

Proton decay is a form of radioactive decay. Unlike other radioactive decay, it is not accompanied by the emission of a high energy neutrino or the emission of a neutron.

Protons are fermions and have equal numbers of left-handed and right-handed components, and are therefore chirally symmetric.

Production

Protons are formed mainly in the Big Bang when electrons and positrons (electron-positron annihilation) are converted to photons (cosmic background radiation) via the collision of a proton and an electron or positron. However, in certain other stellar processes (such as p-processes in stellar nucleosynthesis), they can also be produced by the capture of two neutrons to form. 

Difference between Electron and Positron:

Both the electrons and positrons are beta β particles. A positron is the antimatter counterpart or doppelganger of an electron β-. A positron is a positive electron beta plus β+.

Positron emission gives a new nucleus with the same mass number but an atomic number that is less than the old one. 

Electron emission grants an atomic number that is one greater.

Beta emission is a process in which a nucleus emits a β particle may be a positron or an electron. This allows the atom to get the optimal ratio of protons and neutrons.

There are two types of β emission:

The emission of an electron is β- decay and the emission of the positron is β+ decay.

What is Positron Made Up of?

The positron or positive electron is the antiparticle of the antimatter counterpart of the electron. The positron has an electric charge of +1, a spin of ½ and has the same mass as an electron.

Positron and Electron Collide:

During the beta plus decay, a proton is converted into a neutron and a positive beta particle or beta plus. This is called a positron and it is positively charged and has the same mass. When the electron and positron collide and annihilate, an event occurs, and gamma rays are produced.

Beta Plus Decay:

Beta plus decay is caused because a nucleus has too low a neutron: proton ratio to be stable.

Beta plus decay is a process in which a nucleus emits a positron. A positron is the antimatter counterpart or doppelganger of an electron.

Most nuclei are unstable if the neutron-proton ratio is less than 1:1 for small nuclei or 1.5:1 for larger nuclei. That is, there are too many protons.

One way for the nucleus to become more stable is by beta plus decay. This increases the number of neutrons and decreases the number of protons.

Symbol of Positron:

Positron emission or beta plus decay or β+ decay is a subtype or alternate of radioactive decay called beta decay, in which a proton inside a radionuclide nucleus is converted into a neutron while releasing a positron and an electron neutrino. Positron emission is mediated by a weak force.

In other words, the positron emission occurs when a proton in a radioactive nucleus changes into a neutron and releases a positron and electron neutrino.

Explanation:

A positron is a type of beta particle β+. Most nuclei are unsteady or unstable if the neutron-proton ratio is less than 1:1 that is if there are too many protons. They will decay to correct the imbalance.

Positron emission increases the number of neutrons and decreases the number of protons, making the nucleus more stable or balanced. In positron emission, the atomic number Z decreases or lessens by one while the mass number A remains the same.

Magnesium-23 has 12 protons and 11 neutrons. The neutron: proton ratio is 11:12 or 0.92:1. It undergoes positron emission to form sodium-23.

How does Positron Emission Mammography Work?

Positron emission mammography works on the basis that cancer cells show increased usage of glucose. A positron emission scanner is a miniature X-ray machine and a PET scanner.

Isotopes like F-18 are positron emitters. Substances consist of these isotopes collected in disease sites in the body.

The patient receives a solution of F-18 fluorodeoxyglucose, which accumulates the cancer cells.

When an F-18 decays, it emits a positron and a neutrino. 

The positron soon meets an electron in the tissue. They annihilate each other, producing two antiparallel 511 keV y-rays.

The PEM uses a pair of detectors placed above and below the breast and mild breast compression to detect the y-rays. The signals are amplified or strengthened, and a computer uses these to generate images of thin slices through the breast. The images are then overlaid with an ordinary X-rays image.

What Elements Undergo Positron Decay?

Positron emission or beta plus decay are an appropriate type of radioactive decay, in which a proton inside a radionuclide nucleus is transformed into a neutron while releasing a positron and an electron neutrino. The positron is a type of beta particle β+, the other beta particle being the electron β- emitted from the β negative decay of a nucleus.

Isotopes that undergo this decay and thereby emit positrons are:

Carbon -11, potassium-40, oxygen-15, aluminum-26, nitrogen- 13, sodium-22, fluorine-18, and iodine-121

Positron decay is an exponential process. During radioactive decay, an unstable or changeable nucleus loses energy by emitting ionizing radiation. This radiation includes energetic alpha particles, beta particles, and gamma particles.

In any radioactive decay, it is impossible to conclude when a particular atom will decay. The chance that a given atom will decay is consistent over time.

Positron emission, therefore, follows the augmented rule for radioactive decay:

N=N0eβ^-kt.

Natural Production of Positron:

The positrons are naturally produced in β+ decays of occurring naturally radioactive isotopes and in interactions of the gamma with the matter. The discovery of the positive electron or positron by Anderson was the first evidence of these particles being symmetrical or the particles of our everyday life. They belong to what is called antimatter.

To demonstrate the existence of the antiproton, the scientist had to wait for the development of large particle accelerators. In 1955, the group of members’ segno, Owen, using a bevatron, proved the existence of the antiproton and then shortly the antineutron.

The position does not exist in the environment. It is possible to produce positrons with an energy greater than 511 Kev, the mass of the electron or positron. One should simultaneously create one antiparticle, either a neutrino or an electron. The total electric charge will be conserved during the process.

Some of the positrons are generated by a rare type of radioactive decay, beta-plus decays. The positron is produced together with an invisible electron-neutrino that escapes detection. Energy is appropriated from the energy released in the decay.

A second process is the production of an electron and a positron during the interaction of an energetic gamma with a nucleus. As an electron is also produced 511 Kev should be added to the 511 Kev that is needed to create the position: the gamma energy should be larger than 1022 Kev.

Few of the gammas in radioactive decay have such energies. Pair production plays a marginal role in the environment.

Every kilogram of matter in the world contains billions of billions of billions of electrons. If it does not travel or move in a vacuum, a positron quickly encounters one of these electrons. When the positron and electron meet, which are antiparticles of each other, they destroy themselves mutually and annihilate. 

Two annihilation of gamma with equal energy is also emitted back to back. They carry each 511 Kev that is the mass-energy of the two particles electron and positron which is thus restored. Moving amid its countless electron enemies, positrons are virtually absent from the environment. These happen to be antiprotons. 

β Beta Decay Weak Forces:

The first theory of beta decay was formed in 1934 by the great Italian physicist Enrico Fermi

The forces which allow a nucleus to emit or transmit beta electrons:

Beta-decay (β) changes the composition of the protons and neutrons in a nucleus. The electric charge of the nucleus will be increasing or decreasing by one. The variation of charge is compensated by the emission of a charged particle- a positron or an electron or rarely the capture of an electron. 

The main forces at work in the nucleus, those attractive that maintain their coherence and those repulsive between electric charges of the same sign are unable to transform neutrons into protons and produce electrons, positrons, antineutrinos, and neutrinos. The third type of cooperation or interaction is used by nature to allow and proceed with beta decay or electron capture.

The third interaction is considered weak as beta decays that are the most visible manifestation are very slow transformations that happen rarely. The lifetimes of unstable nuclei are extremely variable that is quarter of an hour for a free neutron, one week for iodine-131, thirty years for caesium-137, a billion years for potassium-40, but all these periods including the quarter of an hour of the neutron are very long for the nuclear block.