What are Alpha particles, Beta particles, and Gamma particles?

Question

And can someone help me differentiate them? Thanks in advance.

Answer 1

Alpha particles are nucleus of Helium. It means that they are He atoms (better to say ions) without electrons. They made up of two protons and two neutrons, hence have positive charge. α-particles very energetic and quickly  ionize many atoms (about 10 000 ionizations per mm in air for each α-particle). Because they lose so fast their energy, they have weak penetration ability. We can protect ourselves from alfa radiation using the piece of paper.

The health effect from exposure to alpha radiation depends greatly on how a person is exposed. They lack the energy to penetrate even the outer layer skin, so it is not a major concern, if we are talking about the exposure outside of the body. However, inside the body they can be very harmful. If α-emitters are inhaled or swallowed, or get into the body through a cut, the α-particles can damage sensitive living tissue. The ionization they cause are very close together – they can release all their energy in a few cells. This can cause a mutation. If the DNA in the nucleus of a cell is damaged, the cell may become cancerous (usually lung cancer). In this case the cell divides rapidly and causes serious health problems.

Beta particles are fast moving electrons ( or positrons – antiparticles for electrons), hence have negative (or positive) charge. Their mass is much smaller than of α-particles, charge is half of their charge. The high speed of β-particles and small size (8 000 times smaller than α-particle) make them more dangerous, they still can knock electrons of atom. Each of β-particle will ionize about 100 atoms per mm in air, losing energy at each interaction. Lower number of interactions means that beta radiation causes  much less damage to body tissue (1/20 of the damage done by the same dose of α-particles). External exposure can cause burns and tissue damage, along with other symptoms of radiation sickness. They have more penetrating power than α-particles. When they penetrate through your skin, β-particles affect cells inside you. This damage is less than in case of α-particles, because the ionizations β-particles produce are more widely spread.  Beta radiation can be stopped by a layer of clothing or by thin layer of aluminum (3 -4 mm). As with α-emitters, β-emitters are most hazardous when they are inhaled or swallowed.

 Gamma particles are very short electromagnetic waves with the wavelength less than of X-rays. Very often we call them γ-photons. They are similar to visible light, but have much higher energy. Gamma rays are a radiation hazard for the entire body. They can easily penetrate barriers that can stop alpha and beta particles, like your skin or clothing.  γ-rays  have so much penetrating power that 10 – 20 cm of a dense material such as lead or around 1 m of concrete may be required to stop them. Gamma rays can pass completely through the human body; as they pass through, they can cause ionizations that damage tissue and DNA. The reason – their energy, not lack of charge. You need to understand that gamma particles are the most dangerous form of ionizing radiation. These extremely high energy photons are massless, so can travel through most forms of matter. If you are exposed to γ-rays, they pass through your entire body, affecting all of your tissues from your skin to the marrow of your bones. This causes widespread, systematic damage.

Finally, there is no the lowest level of radiation that is unharmful. The reality is that we still unaware of all aspects of exposure to radioactive particles. Some people could develop severe health issues being expose to very low level of radiation, some of them could be exposed with lethal dose and survive…

Answer 2

Each of these particles are different outputs of a nuclear reaction:

Alpha Particles:

They're just two protons and two neutrons, technically a Helium-4 nucleus

They're created by "Alpha decay" which is when a heavy atom like Uranium splits into a smaller atom, like Thorium, and the alpha particle. Uranium = Alpha Particle + Thorium. Alpha particles aredangerous depending on the situation, they can't pass through human skin, but if they get inside you, they can damage your organs from inside.

Beta Particles:

They're technically an electron, or positron (same mass but opposite charge as an electron)

They're created by "Beta Decay" but it works a little differently from Alpha Decay. When a Beta Decay happens, a Neutron in the nucleus of an atom splits into a positively charged particle and a negatively charged particle -- a proton and an electron most of the time -- There are many possible examples, but the important part is that it releases a lot of energy. Beta particles can also be dangerous, but they can be blocked by heavy clothing, they can't hurt you too much unless you touch them with your skin.

Gamma Particles:

A Gamma Particle or Gamma Ray is an electromagnetic wave, like radio waves or light. However, it is extremely high frequency (above 30 * 10^18 Hertz). They are made during both Alpha and Beta decay. They are so small and high energy that they can pass through anything with ease, but they also won't do much damage.

Ernest Rutherford named them according to how easily / how many materials they penetrate, which is an easy way to remember them. Alpha particles penetrate the least, Beta particles are in the middle, and Gamma rays penetrate the most. Remember that Alpha, Beta, and Gamma are the first three letters of the Greek alphabet

Another way to remember is a gruesome joke a physics professor shared with me:

An evil physicist gives you three cookies. Each of them contains one type of emitter creating each respective particle. You need to hold one in your hand, put one in your pocket, and eat one.

If you want to survive: Alpha emitter in your hand, since it can't get through your skin. Beta emitter in your pocket, since it can't get through your clothing. Eat the Gamma emitter, because there is nothing you can do to stop Gamma particles anyways, and the other two types are way more dangerous if they get inside your stomach.

For legal purposes, I'm obligated to tell you not to replicate this in real life. Please do not play with radioactive emitters.