Types of Radiation Flashcards
What is nuclear radiation? (Name the types)
Refers to particles/rays that is emitted by an unstable nuclei during decay.
-Alpha (a)
-Beta(-/+) (B or e)
-Gamma (Y)
Alpha Radiation (How fast, ionisation, penetration, and limitation and application)
-Travels at less than 10% the speed of light.
-Since alpha particles have high charge and mass, they are capable of dislodging other electrons at ease. Hence they have a high ionisation energy
-Due to high charge, it can interact with other particles more frequently, which slows it down. Therefore, low penetration ability.
-Stopped by paper or outer layer of skin
-Used in Smoke Detectors
Beta Negative Radiation (How fast, ionisation, penetration, and limitation)
-Travel at 90% the speed of light.
-Moderate ionising ability, because of reduced mass/charge relative to alpha.
-Moderate Penetrating ability, because it moves fast and it has less charge than an alpha particle, so it has fewer interactions with surrounding particles.
-Stopped by 1mm of aluminium.
Beta Positive Radiation (How fast, ionisation, penetration)
-Fast moving positrons.
-Since it annihalates any electron immediately, it has very high ionisation and very low penetration ability.
What is annihlation?
Refers to the process in - which a positron (antimatter of electron) comes into contact with an electron which in-turn causes them to transform into pure energy in the form of 2 gamma rays in being emitted on opposite sides.
Gamma Radiation
-Travels at the speed of light (3x10^8)^2 m s^-1)
-Low -no Ionisation energy because it has no mass nor charge
-Very High penetration ability because it has no charge, and is very fast.
-stopped by 40cm of lead sheet or 2m of concrete.
Effect of electric field on radiation
Charged particles get deflected by the field, so only alpha and beta are affected.
Effect of magnetic field on radiation.
Charged particle will experience force acting on it a a right angle to the direction of travel. Only alpha and beta are affected. Beta will be deflected in opposite direction. Alpha will be deflected in a certain direction depending on magnetic field direction, and gamma wont be affected
What is absorbed dose?
Absorbed dose refers to radiation absorbed by a specific tissue/organ/matter per kg. (Gy Grays)
Absorbed Dose Formula:
D = E/m (Energy in joules/Mass in kg)
What is Dose Equivelant?
Refers to the absorbed dose that accounts for the type of radiation that is absorbed. (Sv Sieverts)
Dose Equivalent Formula:
DE = D x Qf (Dose absorbed x Quality Factor)
