Ionizing Radiation (Radioactivity) Flashcards
What is radioactivity?
It is the spontaneous disintegration of nuclei with simultaneous emission of alpha, beta and gamma rays.
What are alpha rays?
Alpha particles, (alpha rays/alpha radiation), consists of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus.
4/2He
What is the equation used for alpha rays?
A/Z X –> (A-4)/(Z-2) Y + 4/2 He
What is the charge of alpha rays?
Alpha rays are POSITIVELY charged.
What are beta rays?
A beta particle, (beta ray/beta radiation) (symbol β), is a high-energy, high-speed electron or positron emitted by the radioactive decay of an atomic nucleus during the process of beta decay.
What is the equation used for beta rays? for electons? for positrons?
A/Z X –> (A)/(Z+1) Y + e^- + v
A/Z X –> (A)/(Z-1) Y + e^+ + v
What are the two possible forms of beta decay?
β− decay (produce electrons)
β+ decay (produce positrons)
What are gamma rays?
- very short electromagnetic waves
- formed due to an energy change within the atomic nucleus
What do gamma emissions change? atomic number, or atomic mass?
neither!
What is the equation used for gamma rays?
80/m Br –> 80/m Br + y
What is ionising radiation?
the radiation that carries enough energy to ionise the atoms or molecules.
What is a half-life?
a measure of the tendency of the nucleus to “decay” and the time required for a quantity to reduce to half of its initial value.
What is the equation used to calculate a species half life?
T = ln2/ℷ
ℷ- radioactive decay constant = average life time
What is “activity” in physics?
the rate of decay per second
What is the equation for calculating the Activity (A) of an isotope?
A = ln2 * N / T
What is the SI unit of isotopic activity?
Bq - Becquerel
What is 1 Bq (Becquerel) equal to?
1 decay / second
What is the law of radioactive decay?
The number of radioactive nuclei decreases exponentially over time (ln).
What are the three principles of radiation protection?
1) time
2) distancing
3) shielding
What is the half-value layer?
the thickness of material at which the intensity of radiation has been reduced by half.
What is the linear attenuation coefficient (lu (micro))?
a size that is inversely proportional to thickness of a layer required to reduce the intensity of radiation to magnitude of e.
What are the main ionising radiation types?
alpha
beta
gamma
X-rays
rays
What are the products of radioactivity?
alpha, beta and gamma
What is “penetration power”?
The power (length) of an electron beam transmitted for a substance.
What is an alpha particle?
a nuclear of helium
What does a neutron divide into?
Neutron –> positron + electron + antineutrino
n0–> p+ + e- + ve
What is the helium particle?
an alpha particle
What are the different X-ray sources?
What kind of spectrum does the x-ray tube have?
continuous
What is the daily maximal radiation exposure to not have problems?
25 rems
What is the daily radiation exposure that leads to death in less than 2 months?
> 600 rems
What does exposure to radiation lead to?
DNA damage
What are the two ways radiation can damage DNA?
1) Indirect (through a free radical of water)
2) Direct
What type of scan can be created using radiation? What does it screen for?
Computed tomography, (CT scans), are medical imaging tests that use ionizing radiation to create cross-sectional (slices) pictures inside selected areas of the body from different angles.
- The images can show internal organs, blood vessels, soft tissues, and bones.
