Radiation Physics And Instruments (1) Lec 1 PDF

Radiation Physics and Instruments (1) First Semester-2025 Course code: RIRP202 Prof.Dr. Yasser Rammah  Lecturer 1 01.10.2024 RADIATION AND ATOM Prof.Dr. Yasser Rammah  Energy in motion What is Radiation? ▪...

Radiation Physics and Instruments (1) First Semester-2025 Course code: RIRP202 Prof.Dr. Yasser Rammah  Lecturer 1 01.10.2024 RADIATION AND ATOM Prof.Dr. Yasser Rammah  Energy in motion What is Radiation? ▪ Radiation: Radiation is energy travelling through space. ▪ Sunshine is one of the most familiar forms of radiation. ▪ It delivers energy, light, heat and suntans. ▪ While enjoying and depending on it, we control our exposure to it. ▪ Beyond ultraviolet radiation from the sun, there are higher-energy kinds of radiation which are used in medicine and which we all get in low doses from space, from the air, and from the earth and rocks. ▪ Collectively we can refer to these kinds of radiation as Ionizing Radiation. ▪ It can cause damage to matter, particularly living tissue. ▪ At high levels it is therefore dangerous, so it is necessary to control our exposure.  The Atom The nucle us All matter is made up of atoms. Atoms are the smallest component of an electr element, comprised of three particles: ons orbital Protons. s Neutrons. Electrons. Particle Symbol Mass Energy Charge (kg) The atom is mostly empty space and Neutral (MeV) protons and neutrons in the nucleus. ------------------------------------------- the number of electrons is equal to the number --------------- of protons. Proton p 1.672*10-27 electrons in space around the nucleus. 938.2 + -27 extremely small. One teaspoon of water has 3 Neutron n 1.675*10 times as many atoms as the Atlantic Ocean has 939.2 0 teaspoons of water. Electron e 0.911*10 -30 0.511 -  Standard nuclear notation A mass number A=Z+N chemical symbol (N = # of neutrons) atomic number Z X # of protons or Let’s practice mass number A=Z+N chemical (N = # of symbol neutrons) A X atomic number # of protons Z  The Nucleus Nucleons – particles found in the nucleus of an atom neutrons protons Atomic Number (Z) – number of protons in the nucleus Mass Number (A) – sum of the number of protons and neutrons Atomic Isotopes – atoms with identical atomic number, Z numbers but different mass numbers 1 Nuclide – each unique atom. A Elemental 3 symbol l Atomic 26.9 mass (u) 81  The Nnucleus It is the central part of an atom. It composed of Protons and Neutrons join together. It contains most of the mass of atom. Proton and Neutron have almost the same mass. The number of Protons in the nucleus is called Atomic Number (Z). The total number of Protons and Neutrons in the nucleus is called Mass Number (A). Protons Proton is positively charged particle. The atomic number (Z) is the “ID Card” of the element Neutrons Neutron carry NO electrical charge “neutral particle” Electrons negative electrical charge.  AMU Atomic masses may be given either in grams or in relative numbers called unified atomic mass units (u). Since one mole of any substance contains 6.02×1023 molecules (Avogadro’s number) and the mass in grams of one mole is equal numerically to its molecular weight, the mass of a single atom can easily be computed. In the case of 12C, which is a monoatomic molecule, for example, 1 mol is 12g (by definition). One atom, therefore, Particle Charge(C) Mass (g) Mass (amu) Proton 1.602 x 10-19 1.67x10-24 1.0073 Since 12C was assigned an atomic mass of 12 Neutron 0 1.68x10-24 1.0087 (exactly), one atomic mass unit, u (also called a dalton, symbolized by Electron -1.602 x 10-19 9.11x10-28 0.0006 Da), is : Atomic Structure  Fundamental Particles Relative Mass Approximate Energy particle Symbol charge (amu) Equivalent (MeV) Neutron n0 0 1.008982 940 Proton P, 1H+ +1 1.007593 938 Electron (beta minus) e−, β− −1 0.000548 0.511 Positron (beta plus) e+, β+ +1 0.000548 0.511 Alpha α, 4H2+ +2 4.0028 3727  Binding Energy 1- Binding energy, amount of energy required to separate a particle from a system of particles or to disperse all the particles of the system. 2- The binding energy depends on the shell , and on the element, increasing as the atomic number increases Electromagnetic wave. Wavelength (λ) or Period (T) Amplitude (A) Propagation Velocity Mahmood & Haider Electromagnetic spectrum Electromagnetic Wavelength Frequency Energy Radio waves 30-6 m 10-50 MHz 40-200 neV Infrared 10-0.7 µrn 30-430 THz 0. 2-1.8 eV Visible light 700-400 nm 430-750 THz l.8-3eV Ultraviolet 400-100 nm 750-3000 THz 3-12 eV X- and gamma 60-2.5 pm 5× I06– 120× 106THz 20-500 keV Radiation Ionizing vs. Non-Ionizing Radiations Ionizing Non-Ionizing Ionizing Radiation Alpha Radiation Beta A radiation that has Gamma A radiation that is sufficient energy to X-Rays not as energetic as remove electrons from Neutrons ionizing radiation and atoms or molecules as it cannot remove passes through matter. electrons from atoms Non- or molecules. Examples: x-rays, Ionizing gamma rays, beta Examples: light, particles, and alpha Radio waves lasers, heat, particles. Microwaves microwaves, and radar. Infrared Visible Light Ultraviolet (UV) Why is it called ionizing? Because it creates ions… atoms with a charge. Energy Education, University of Calgary Penetration abilities of different types of radiation Inverse Square Law for Radiation , Intensity = Power /Area  * Properties Considered When Ionizing Radiation Measured Ionizing radiation is measured in terms of: 1- The strength or radioactivity of the radiation source, 2- The energy of the radiation, 3- The level of radiation in the environment, and 4- The radiation dose or the amount of radiation energy absorbed by the human body.  Units of radiation Radiologic units includes Roentgen, Rad, Rem, Curie, and Electron volt  Roentgen (R) The Rontgen (R or r) is the unit of dose of electromagnetic radiation exposure or intensity. It is equal to the radiation intensity that will create 2.08×109 ion pairs in a cubic centimeter of air that is: 1R = 2.08 ⨉ 109 ion pairs/cm3 The official definition, however, is in terms of electric charge per unit mass of air: 1R=2.58 ⨉ 10-4 C/kg The charge refers to the electrons liberated by ionization.  Rad The Rad (radiation absorbed dose) is used to measure the amount of radiation absorbed by an object or person which reflects the amount of energy that radioactive sources deposit in materials through which they pass. An absorbed dose of 1 rad means that 1 gram of material absorbed 100 ergs of energy. 1Rad=100 ergs/g (10-2 Gy) Where the erg (joule) is a unit of energy, and the gram (kilogram) is a unit of mass. The related international system unit is the gray (Gy), where 1 Gy is equivalent to 100 rad.  Rem The rem (Roentgen equivalent man) is the traditional unit of dose equivalent (DE) or occupational exposure. It is used to express the quantity of radiation received by radiation workers.  Curie Curie (Ci) the original unit used to express the decay rate of a sample of radioactive material. One Curie is that quantity of material in which 3.7x1010 atoms disintegrate every second (3.7x10 Becquerel, Bq).  Electron Volt Electron Volt (eV) is the amount of energy by the charge of a single electron moved across an electric potential difference of one volt. one electron volt is equal to J  Practical Units Absorbed Dose When ionizing radiation penetrates the human body or an object, it deposits energy. The fundamental units do not take into account the amount of damage done to matter (especially living tissue) by ionizing radiation. This is more closely related to the amount of energy deposited rather than the charge. The energy absorbed from exposure to radiation is called an absorbed dose. The absorbed dose is measured in a unit called the gray (Gy). The gray (Gy), with units J/kg, is the SI unit of absorbed dose, which represents the amount of radiation required to deposit 1 joule of energy in 1 kilogram of any kind of matter. The rad (radiation absorbed dose), is the corresponding traditional unit, which is 0.01 J deposited per kg. 100 rad = 1 Gy.  Equivalent Dose The equivalent dose is expressed in a measure called the sievert (Sv). The weighted absorbed dose is called equivalent dose. 1 sievert = 100 rem. Because the rem is a relatively large unit, typical equivalent dose is measured in millirem (mrem), 10−3 rem, or in microsievert (μSv), 10−6 Sv. 1 mrem = 10 μSv.  Effective Dose Where WT is tissue weighting factor, HT is equivalent dose to tissue T For example, if someone’s lungs and thyroid are exposed separately to radiation, and the equivalent doses to the organs are 2 mSv (they have a weighting factor of 0.12) and 1 mSv (it has a weighting factor of 0.06) respectively. The effective dose is: (2 mSv × 0.12) + (1 × 0.06) = 0.3 mSv.