BasicRadiationPhysics (1).pdf

BASIC RADIATION PHYSICS BET-NDT-4A ABOGADO, NICOLE JOHN R.  Contents 01 02 03 04 Introduction to Types of Examples, Conclusion and Basic Radiation Radiation, How Nuclear...

BASIC RADIATION PHYSICS BET-NDT-4A ABOGADO, NICOLE JOHN R.  Contents 01 02 03 04 Introduction to Types of Examples, Conclusion and Basic Radiation Radiation, How Nuclear Recommendations Physics, does it interact Reaction and Definition, with Matter, Radioactivity, Fundamental Photons Half-life activity Units, etc. connection with Matter and Radiography Objectives To refresh some of the basic 1. knowledge about radiation. Have wider perspective about 2. the application of Radiographic Testing To understand the 3. complexities of Radiography Introduction: what is radiation? Radiation is the emission of energy as electromagnetic waves or particles. It plays a vital role in fields such as medicine, energy, and communication. Understanding radiation types, interactions with matter, and safety precautions is crucial in both practical and theoretical applications. Types of radiation Radiation can be classified broadly into two main categories: non-ionizing and ionizing radiation. The distinction between these two lies in their energy and ability to ionize atoms (i.e., to knock out electrons from atoms, turning them into ions). Types of radiation There are two main informational types of radiation: Ionizing radiation Non-ionizing radiation Ionizing radiation is more energetic Non-ionizing radiation refers to types of radiation that do not have enough energy to and has enough power to ionize ionize atoms. They primarily cause excitation, atoms by removing electrons. This where electrons jump to higher energy states type of radiation is of primary but remain bound to the atom. Examples include: concern in medical fields like Radio waves (used in communication) Microwaves (used in cooking and wireless radiology and radiotherapy, as it can technology) damage living tissue. It is subdivided Visible light (part of the electromagnetic into directly ionizing and indirectly spectrum that humans can see) ionizing radiation. Infrared radiation (felt as heat) Ionizing radiation There are two types of ionizing radiation: Direct radiation In-direct radiation Involves charged particles such Involves neutral particles such as as electrons (beta particles), photons (X-rays and gamma protons, and alpha particles. rays) and neutrons. These These particles directly particles don't ionize atoms interact with matter, directly but can produce transferring energy to atoms charged particles (like electrons) in matter, which in turn causes and causing ionization. ionization. Examples X-rays Gamma rays Alpha - P Used in diagnostic High-energy Heavy and charged imaging but in high radiation emitted by particles emitted by doses can damage radioactive atoms, certain radioactive used in cancer materials, used in cells. treatment but also specific types of a source of danger cancer therapy. due to their deep penetration ability. Photon interactions with matter Photons, which include gamma rays and X-rays, interact with matter in several ways. These interactions are important for understanding how radiation is absorbed or transmitted through different materials. Photoelectric effect In the photoelectric effect, a photon transfers all its energy to an electron in an atom, ejecting the electron from the atom. This process occurs predominantly with low- energy photons. The ejected electron, called a 'photoelectron', carries kinetic energy equal to the photon’s original energy minus the binding energy of the electron. Compton effect The Compton effect involves a photon colliding with a loosely bound or free electron, transferring part of its energy to the electron. The photon continues on a different path with reduced energy. This is the dominant interaction for photons in the diagnostic radiology energy range (0.1 to 10 MeV). Pair production Pair production occurs when a photon with energy greater than 1.02 MeV passes near the nucleus of an atom and creates an electron-positron pair. This interaction is essential in high-energy physics but only occurs when photons have energies above 1.02 MeV. It also has implications in radiation therapy, where high-energy photons are used. Nuclear Reactions and Radioactivity Nuclear reactions involve changes to the nucleus of an atom, often resulting in the emission of ionizing radiation. The primary types of radioactive decay include: Alpha Decay: An alpha particle (two protons and two neutrons) is emitted from the nucleus. Alpha particles cannot penetrate deeply but can be dangerous if ingested or inhaled. Beta Decay: A neutron in the nucleus converts into a proton and an electron, with the electron (beta particle) being ejected. Gamma Decay: The nucleus releases energy in the form of a gamma photon, often after an alpha or beta decay. style, tone and formality The 'half-life' of a radioactive substance is critical in understanding its decay rate. The activity (A) of a radioactive substance is a measure of how many decays occur per second. It is defined by the equation: \[ A(t) = \lambda N(t) \] Where: - \( A(t) \) = Activity at time \( t \) - \( \lambda \) = Decay constant - \( N(t) \) = Number of radioactive atoms present at time \( t \) Stopping and Scattering power When researching for your informative text, you'll likely use a combination of both primary and secondary sources. Stopping power Scattering power Stopping power refers to the energy Scattering power describes how much a loss per unit distance traveled by a charged particle, like an electron, is charged particle in a material. It’s deflected as it passes through a material. essential for determining the energy This is particularly important for understanding the behavior of electron deposition in tissues, especially in beams used in radiotherapy. radiation therapy. Continuation... The mass stopping power \( S/ρ \) is divided into: Collisional stopping power: Due to interactions with orbital electrons, leading to excitation and ionization. Radiative stopping power: Due to interactions with nuclei, producing bremsstrahlung (braking radiation). Photon Beam Attenuation When photons pass through matter, they lose energy through scattering and absorption, which is described by photon attenuation. The linear attenuation coefficient \( \mu \) describes the fraction of photons removed per unit thickness of material. The formula is: Conclusion In summary, radiation physics provides the foundation for understanding how radiation interacts with matter. These principles are not only crucial for the safe application of radiation in medicine but also in industries like nuclear energy. Radiation safety requires knowledge of how different types of radiation behave, and protective measures like shielding and dose management should always be enforced to minimize risks. Target objectives 1. Increased Awareness: Educational programs should emphasize the dangers of ionizing radiation, even in medical settings where it is commonly used. 2. Research: More studies are needed to explore better materials for radiation shielding, especially for high-energy photons. 3. Safety Measures: Ensure regular monitoring of radiation exposure, especially for professionals working in radiology and radiotherapy. Thanks for listening