Basics of Radiation Science: Types of Radiation Part 1

In my day job I'm a health physicist who oversees the radiation safety program of research labs at a large university. I'm also liberal leaning and have noticed a trend of anti-nuclear sentiment on those who lean left. I think some of that stems from a lack of understanding of ionizing radiation. Which given that Homer Simpson is the most famous nuclear safety officer in existence, I wouldn't blame them. However radiation science is a field that has existed since at least 1896 with the discovery of x-rays by Wilhelm Roentgen. With safety measures for radiation work first being proposed by the German Roentgen society in 1913. To assist with this lack of basic radiation science being readily available on the internet, I have decided to start a learning series here on Steemit. With today covering X-ray and Gamma Ray radiation.

Before we get further I want to reiterate that this is a basic description. I won't be going in depth into the mechanics today just giving a generalization of the types of radiation. I will also only be talking about Gamma/x-ray today. There is also Alpha, Beta/ Positrons and Neutron radiation, and we will discuss those in the next few iteration of this learning series. so without further ado let us begin by talking about the first type of radiation discovered which is x-ray/gamma ray.

X-ray/Gamma Ray: X-ray and Gamma rays were the first types of radiation that were discovered. X-rays were discovered by Wilhelm Roentgen in 1896 . He was conducting experiments with cathode ray tubes and and in that same room had an unopened box of photographic film. When we opened the box he noticed that the film was already exposed. He theorized that the cathode ray tubes were emitting an unknown ray, which he dubbed "X-ray". The X being used as it would in a math equation for an unknown variable. The name has just stuck at this point, though there was a movement to name the x-ray the Roentgen ray which has not caught on everywhere.

So x-rays and gamma rays are grouped together because outside of how they are generated they function pretty much the same. How they are generated is similar though from different parts of the atom. For X-rays, they are typically generated when an electron jumps from a higher energy shell to a lower energy shell. The difference in energy doesn't disappear but forms a photon and this photon is called an x-ray . It can also be formed when an electron is abruptly stopped or has it's trajectory abruptly moved. In that situation the electron might have changed direction but the momentum of the electron keeps going forward. This is known as bremsstrahlung radiation. Gamma radiation is formed similar to how the first method of x-ray radiation is formed but, it all occurs in the nucleus of the atom. The nucleus also is composed of shells, and in those shells live protons and neutrons. When a proton jump from a higher energy to a lower energy state the difference in energy forms a photon and that photon is known as a gamma ray.

So gamma rays and x-rays are both really small in size. Being a photon they exist in the particle-wave duality. Meaning that they function as both a wave would and also as a particle does once it interacts with matter. So the range of a x-ray or gamma ray is functionally infinite. When they interact with matter they tend to deposit a small amount of energy and keep going. They are small particle. To properly shield for them the shielding material needs to be made of dense material made of elements with densely packed nucleus to increase the chance that the photon interact with the shielding material. This typically means that lead is the shielding material is made out of lead.

Given all that information what is the risk of being around this type of radiation. The risk itself is rather low. What I mean by that is that unlike the subsequent types of radiation we will be talking about, the effective dose rate of x-ray/gamma ray is a one to one ratio with the dose rate. The difference between the effective dose rate and dose rate will be a topic in of itself, but for now understand that all radiation deposits its energy when interacting with matter differently. In the case of x-ray and gamma ray it's a little bit of radiation and keep going. Since they behave that way the amount of radiation dose a person receives from an x-ray source is directly proportional to the energy of the source. In practical terms if you need to be near a high energy x-ray or gamma ray sources, and you are not a medical patient, place a little bit of lead between you and the source to lower your dose.

I hope you found this helpful. They should hopefully all not be this long. In our next lesson we will be discussing Alpha radiation. If you have any questions or topics you would liked discussed in this series, please leave it in the comments.