Beta particle

Tiny bits fly from some things.

These bits move very fast. They can travel through the air. A thin metal sheet can stop them.

Some bits can even make water glow blue. This happens when they move through water. Doctors use these bits to help sick people. They can treat some types of cancer. They also help check how thick paper is. It is amazing how these tiny bits work!

Tiny parts fly out of some atoms. These are called beta particles.

They are very fast and have high energy. They can be electrons or positrons. A positron is a type of beta particle too.

Beta particles come from beta decay. This is a way an atom changes. In one way, a neutron turns into a proton. This lets out an electron. In another way, a proton turns into a neutron. This lets out a positron.

These particles are ionizing. This means they can knock electrons off other things. They are more ionizing than gamma rays. But they are less ionizing than alpha particles.

Beta particles can travel through the air. A particle with 0.5 MeV of energy can travel one metre. They cannot pass through clothing or thin metal. A thin sheet of aluminium can stop them.

People use beta particles for many jobs. Doctors use them to treat some cancers. They also use them as tracers. Machines use them to check the thickness of paper. If the paper is too thick, the particles are stopped. This helps machines fix the paper right away.

Beta particles are tiny pieces of energy that fly out of certain atoms. Scientists call this process beta decay. These particles are either electrons or positrons, which are like the opposites of electrons.

Beta particles are a type of ionizing radiation. This means they can knock electrons off other things they hit. They are more ionizing than gamma rays, but they are not as strong as alpha particles.

Because they are ionizing, they can cause changes in living tissue.

There are two main ways beta decay happens. In one way, called beta-minus decay, an unstable nucleus has too many neutrons. A neutron turns into a proton and sends out an electron and an antineutrino.

In the other way, called beta-plus decay, a nucleus has too many protons. A proton turns into a neutron and sends out a positron and a neutrino. This happens when the new nucleus has lower energy than the old one. These tiny changes are how atoms find a more stable way to exist.

People discovered these particles a long time ago. Henri Becquerel first found unknown radiation while working with uranium. Later, Ernest Rutherford studied this radiation more closely. In 1899, he found that beta particles were 100 times more penetrating than alpha particles.

In 1900, Becquerel measured the charge of these particles. He found they were the same as electrons. This helped scientists realize that beta particles are actually electrons.

Beta particles have different strengths and behaviors. A particle with 0.5 MeV of energy can travel about one metre in the air. They cannot pass through clothing or thin metal sheets. However, a thin plate of aluminium can stop them.

In water, some beta particles move very fast. They can move faster than light moves through water. This creates a beautiful blue glow called Cherenkov radiation. This glow can be seen in the water of swimming pool reactors.

We use beta particles for many helpful things every day. Doctors use them to treat bone and eye cancer. They also use them as tracers to see how things move.

In factories, machines use them to check if paper is the right thickness. If the paper is too thick, it stops more particles. We also use tritium to make betalights. These lights do not need any power to work. They stay lit as long as the tritium exists.

A beta particle, also known as a beta ray or beta radiation (symbol β), is a high-energy, high-speed particle emitted during radioactive decay. This process occurs when an unstable atomic nucleus undergoes beta decay to reach a more stable state. Beta particles can be either electrons or positrons. Electrons carry a negative charge, while positrons are their antimatter counterparts. These particles are a form of ionizing radiation. This means they have enough energy to knock electrons off the shells of other atoms.

The mechanism of beta decay depends on the balance of particles within the nucleus. In beta-minus (β−) decay, a nucleus has an excess of neutrons. A neutron transforms into a proton, an electron, and an electron antineutrino. This change is mediated by the weak interaction through a virtual W− boson. At the subatomic level, this boson turns a down quark into an up quark. This shift changes the neutron into a proton.

Conversely, beta-plus (β+) decay occurs in nuclei with too many protons. A proton converts into a neutron, a positron, and an electron neutrino. This specific type of decay only happens if the resulting daughter nucleus is in a lower-energy state than the parent nucleus.

Scientists categorize beta decay into these two distinct modes. Beta-minus decay is common in neutron-rich fission byproducts found in nuclear reactors. It also occurs during the decay of free neutrons. Beta-plus decay, or positron emission, is the source of positrons used in medical technology. A notable example is Phosphorus-32. This isotope is a beta emitter used widely in medicine. It has a short half-life of 14.29 days. When it decays into sulfur-32, it releases 1.709 MeV of energy. Most of this energy is carried by the electron, while the rest goes to the antineutrino.

The history of these particles involves several key scientific discoveries. Henri Becquerel first discovered unknown radiation while experimenting with uranium and photographic plates. Later, Ernest Rutherford conducted experiments to identify different types of radiation. In 1899, Rutherford published results showing that beta particles were 100 times more penetrating than alpha particles. In 1900, Becquerel measured the mass-to-charge ratio of these particles. He found the ratio was identical to that of the electron identified by J. J. Thomson. This led to the conclusion that beta particles are indeed electrons.

Beta particles have specific physical properties regarding energy and penetration. A beta particle with 0.5 MeV of energy can travel about one metre in the air. They cannot pass through clothing or thin metal sheets. However, a thin aluminium plate can stop most beta particles.

In water, some beta particles move faster than the speed of light in that medium. The speed of light in water is about 75% of its speed in a vacuum. When this happens, it generates a blue glow called Cherenkov radiation. This effect is visible in the water of swimming pool reactors.

These particles have significant practical applications in various fields. In medicine, beta particles are used in radiation therapy to treat bone and eye cancer. Positrons from beta-plus decay are essential for positron emission tomography, known as PET scans. In industry, beta radiation is used for quality control. Machines use it to monitor the thickness of products like paper. If the paper is too thick or too thin, the amount of radiation absorbed changes. This allows computers to adjust the rollers automatically. We also use tritium in betalights. As tritium decays, it emits beta particles that strike a phosphor to create light without external power.

Understanding beta radiation is vital for safety and science. Because they are charged particles, beta rays are more ionizing than gamma rays. However, they are less ionizing than alpha particles. This ionizing effect can cause spontaneous mutations in DNA within living tissue. For radiation protection, the absorbed dose is measured in grays (Gy). The biological effect on human tissue is measured in sieverts (Sv). For beta radiation, the conversion factor between these two units is 1. This is different from alpha particles, which have a weighting factor of 20 due to their higher ionizing power.