Radiation and Atom PDF

RADIATION AND ATOM  Fundamental Particles Relative Mass Approximate Energy particle Symbol charge (amu) Equivalent (MeV) Neutron n0 0 1.008982 940 Pro...

RADIATION AND ATOM  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 Atomic Structure  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  Non-Ionizing Radiation Non-ionizing radiation is the radiation that has enough energy to move atoms in a molecule around or cause them to vibrate, but not enough to remove electrons. That mean it does not possess enough energy to produce ions. Alpha, Beta, and Neutron Ionizing Radiation Ionizing radiation is a special type of radiation (in the form of either particles or waves) that has enough energy to remove tightly bound electrons out of their orbits around atoms, thus creating ions. Gamma-ray, X-ray, and UV 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.