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21.7: Key Terms

Last updated

Aug 26, 2023
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- 21.6: Biological Effects of Radiation
- 21.8: Key Equations

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Example and Directions
Words (or words that have the same definition)	The definition is case sensitive	(Optional) Image to display with the definition [Not displayed in Glossary, only in pop-up on pages]	(Optional) Caption for Image	(Optional) External or Internal Link	(Optional) Source for Definition
(Eg. "Genetic, Hereditary, DNA ...")	(Eg. "Relating to genes or heredity")		The infamous double helix	https://bio.libretexts.org/	CC-BY-SA; Delmar Larsen

Glossary Entries
Word(s)	Definition	Image	Caption	Link	Source
alpha (α) decay	loss of an alpha particle during radioactive decay
alpha particle	(α or or high-energy helium nucleus; a helium atom that has lost two electrons and contains two protons and two neutrons
antimatter	particles with the same mass but opposite properties (such as charge) of ordinary particles
band of stability	(also, belt of stability, zone of stability, or valley of stability) region of graph of number of protons versus number of neutrons containing stable (nonradioactive) nuclides
becquerel (Bq)	SI unit for rate of radioactive decay; 1 Bq = 1 disintegration/s
beta (β) decay	breakdown of a neutron into a proton, which remains in the nucleus, and an electron, which is emitted as a beta particle
beta particle	or or high-energy electron
binding energy per nucleon	total binding energy for the nucleus divided by the number of nucleons in the nucleus
chain reaction	repeated fission caused when the neutrons released in fission bombard other atoms
chemotherapy	similar to internal radiation therapy, but chemical rather than radioactive substances are introduced into the body to kill cancer cells
containment system	(also, shield) a three-part structure of materials that protects the exterior of a nuclear fission reactor and operating personnel from the high temperatures, pressures, and radiation levels inside the reactor
control rod	material inserted into the fuel assembly that absorbs neutrons and can be raised or lowered to adjust the rate of a fission reaction
critical mass	amount of fissionable material that will support a self-sustaining (nuclear fission) chain reaction
curie (Ci)	larger unit for rate of radioactive decay frequently used in medicine; 1 Ci = 3.7 10¹⁰ disintegrations/s
daughter nuclide	nuclide produced by the radioactive decay of another nuclide; may be stable or may decay further
electron capture	combination of a core electron with a proton to yield a neutron within the nucleus
electron volt (eV)	measurement unit of nuclear binding energies, with 1 eV equaling the amount energy due to the moving an electron across an electric potential difference of 1 volt
external beam radiation therapy	radiation delivered by a machine outside the body
fissile (or fissionable)	when a material is capable of sustaining a nuclear fission reaction
fission	splitting of a heavier nucleus into two or more lighter nuclei, usually accompanied by the conversion of mass into large amounts of energy
fusion	combination of very light nuclei into heavier nuclei, accompanied by the conversion of mass into large amounts of energy
fusion reactor	nuclear reactor in which fusion reactions of light nuclei are controlled
gamma (γ) emission	decay of an excited-state nuclide accompanied by emission of a gamma ray
gamma ray	(γ or short wavelength, high-energy electromagnetic radiation that exhibits wave-particle duality
Geiger counter	instrument that detects and measures radiation via the ionization produced in a Geiger-Müller tube
gray (Gy)	SI unit for measuring radiation dose; 1 Gy = 1 J absorbed/kg tissue
half-life (t_1/2)	time required for half of the atoms in a radioactive sample to decay
internal radiation therapy	(also, brachytherapy) radiation from a radioactive substance introduced into the body to kill cancer cells
ionizing radiation	radiation that can cause a molecule to lose an electron and form an ion
magic number	nuclei with specific numbers of nucleons that are within the band of stability
mass defect	difference between the mass of an atom and the summed mass of its constituent subatomic particles (or the mass “lost” when nucleons are brought together to form a nucleus)
mass-energy equivalence equation	Albert Einstein’s relationship showing that mass and energy are equivalent
millicurie (mCi)	larger unit for rate of radioactive decay frequently used in medicine; 1 Ci = 3.7 10¹⁰ disintegrations/s
nonionizing radiation	radiation that speeds up the movement of atoms and molecules; it is equivalent to heating a sample, but is not energetic enough to cause the ionization of molecules
nuclear binding energy	energy lost when an atom’s nucleons are bound together (or the energy needed to break a nucleus into its constituent protons and neutrons)
nuclear chemistry	study of the structure of atomic nuclei and processes that change nuclear structure
nuclear fuel	fissionable isotope present in sufficient quantities to provide a self-sustaining chain reaction in a nuclear reactor
nuclear moderator	substance that slows neutrons to a speed low enough to cause fission
nuclear reaction	change to a nucleus resulting in changes in the atomic number, mass number, or energy state
nuclear reactor	environment that produces energy via nuclear fission in which the chain reaction is controlled and sustained without explosion
nuclear transmutation	conversion of one nuclide into another nuclide
nucleon	collective term for protons and neutrons in a nucleus
nuclide	nucleus of a particular isotope
parent nuclide	unstable nuclide that changes spontaneously into another (daughter) nuclide
particle accelerator	device that uses electric and magnetic fields to increase the kinetic energy of nuclei used in transmutation reactions
positron or	antiparticle to the electron; it has identical properties to an electron, except for having the opposite (positive) charge
positron emission	(also, β⁺ decay) conversion of a proton into a neutron, which remains in the nucleus, and a positron, which is emitted
radiation absorbed dose (rad)	SI unit for measuring radiation dose, frequently used in medical applications; 1 rad = 0.01 Gy
radiation dosimeter	device that measures ionizing radiation and is used to determine personal radiation exposure
radiation therapy	use of high-energy radiation to damage the DNA of cancer cells, which kills them or keeps them from dividing
radioactive decay	spontaneous decay of an unstable nuclide into another nuclide
radioactive decay series	chains of successive disintegrations (radioactive decays) that ultimately lead to a stable end-product
radioactive tracer	(also, radioactive label) radioisotope used to track or follow a substance by monitoring its radioactive emissions
radioactivity	phenomenon exhibited by an unstable nucleon that spontaneously undergoes change into a nucleon that is more stable; an unstable nucleon is said to be radioactive
radiocarbon dating	highly accurate means of dating objects 30,000–50,000 years old that were derived from once-living matter; achieved by calculating the ratio of in the object vs. the ratio of in the present-day atmosphere
radioisotope	isotope that is unstable and undergoes conversion into a different, more stable isotope
radiometric dating	use of radioisotopes and their properties to date the formation of objects such as archeological artifacts, formerly living organisms, or geological formations
reactor coolant	assembly used to carry the heat produced by fission in a reactor to an external boiler and turbine where it is transformed into electricity
relative biological effectiveness (RBE)	measure of the relative damage done by radiation
roentgen equivalent man (rem)	unit for radiation damage, frequently used in medicine; 100 rem = 1 Sv
scintillation counter	instrument that uses a scintillator—a material that emits light when excited by ionizing radiation—to detect and measure radiation
sievert (Sv)	SI unit measuring tissue damage caused by radiation; takes into account energy and biological effects of radiation
strong nuclear force	force of attraction between nucleons that holds a nucleus together
subcritical mass	amount of fissionable material that cannot sustain a chain reaction; less than a critical mass
supercritical mass	amount of material in which there is an increasing rate of fission
transmutation reaction	bombardment of one type of nuclei with other nuclei or neutrons
transuranium element	element with an atomic number greater than 92; these elements do not occur in nature

alpha (α) decay | loss of an alpha particle during radioactive decay

alpha particle | (α or or high-energy helium nucleus; a helium atom that has lost two electrons and contains two protons and two neutrons

antimatter | particles with the same mass but opposite properties (such as charge) of ordinary particles

band of stability | (also, belt of stability, zone of stability, or valley of stability) region of graph of number of protons versus number of neutrons containing stable (nonradioactive) nuclides

becquerel (Bq) | SI unit for rate of radioactive decay; 1 Bq = 1 disintegration/s

beta (β) decay | breakdown of a neutron into a proton, which remains in the nucleus, and an electron, which is emitted as a beta particle

beta particle | or or high-energy electron

binding energy per nucleon | total binding energy for the nucleus divided by the number of nucleons in the nucleus

chain reaction | repeated fission caused when the neutrons released in fission bombard other atoms

chemotherapy | similar to internal radiation therapy, but chemical rather than radioactive substances are introduced into the body to kill cancer cells

containment system | (also, shield) a three-part structure of materials that protects the exterior of a nuclear fission reactor and operating personnel from the high temperatures, pressures, and radiation levels inside the reactor

control rod | material inserted into the fuel assembly that absorbs neutrons and can be raised or lowered to adjust the rate of a fission reaction

critical mass | amount of fissionable material that will support a self-sustaining (nuclear fission) chain reaction

curie (Ci) | larger unit for rate of radioactive decay frequently used in medicine; 1 Ci = 3.7 10¹⁰ disintegrations/s

daughter nuclide | nuclide produced by the radioactive decay of another nuclide; may be stable or may decay further

electron capture | combination of a core electron with a proton to yield a neutron within the nucleus

electron volt (eV) | measurement unit of nuclear binding energies, with 1 eV equaling the amount energy due to the moving an electron across an electric potential difference of 1 volt

external beam radiation therapy | radiation delivered by a machine outside the body

fissile (or fissionable) | when a material is capable of sustaining a nuclear fission reaction

fission | splitting of a heavier nucleus into two or more lighter nuclei, usually accompanied by the conversion of mass into large amounts of energy

fusion | combination of very light nuclei into heavier nuclei, accompanied by the conversion of mass into large amounts of energy

fusion reactor | nuclear reactor in which fusion reactions of light nuclei are controlled

gamma (γ) emission | decay of an excited-state nuclide accompanied by emission of a gamma ray

gamma ray | (γ or short wavelength, high-energy electromagnetic radiation that exhibits wave-particle duality

Geiger counter | instrument that detects and measures radiation via the ionization produced in a Geiger-Müller tube

gray (Gy) | SI unit for measuring radiation dose; 1 Gy = 1 J absorbed/kg tissue

half-life (t_1/2) | time required for half of the atoms in a radioactive sample to decay

internal radiation therapy | (also, brachytherapy) radiation from a radioactive substance introduced into the body to kill cancer cells

ionizing radiation | radiation that can cause a molecule to lose an electron and form an ion

magic number | nuclei with specific numbers of nucleons that are within the band of stability

mass defect | difference between the mass of an atom and the summed mass of its constituent subatomic particles (or the mass “lost” when nucleons are brought together to form a nucleus)

mass-energy equivalence equation | Albert Einstein’s relationship showing that mass and energy are equivalent

millicurie (mCi) | larger unit for rate of radioactive decay frequently used in medicine; 1 Ci = 3.7 10¹⁰ disintegrations/s

nonionizing radiation | radiation that speeds up the movement of atoms and molecules; it is equivalent to heating a sample, but is not energetic enough to cause the ionization of molecules

nuclear binding energy | energy lost when an atom’s nucleons are bound together (or the energy needed to break a nucleus into its constituent protons and neutrons)

nuclear chemistry | study of the structure of atomic nuclei and processes that change nuclear structure

nuclear fuel | fissionable isotope present in sufficient quantities to provide a self-sustaining chain reaction in a nuclear reactor

nuclear moderator | substance that slows neutrons to a speed low enough to cause fission

nuclear reaction | change to a nucleus resulting in changes in the atomic number, mass number, or energy state

nuclear reactor | environment that produces energy via nuclear fission in which the chain reaction is controlled and sustained without explosion

nuclear transmutation | conversion of one nuclide into another nuclide

nucleon | collective term for protons and neutrons in a nucleus

nuclide | nucleus of a particular isotope

parent nuclide | unstable nuclide that changes spontaneously into another (daughter) nuclide

particle accelerator | device that uses electric and magnetic fields to increase the kinetic energy of nuclei used in transmutation reactions

positron or | antiparticle to the electron; it has identical properties to an electron, except for having the opposite (positive) charge

positron emission | (also, β⁺ decay) conversion of a proton into a neutron, which remains in the nucleus, and a positron, which is emitted

radiation absorbed dose (rad) | SI unit for measuring radiation dose, frequently used in medical applications; 1 rad = 0.01 Gy

radiation dosimeter | device that measures ionizing radiation and is used to determine personal radiation exposure

radiation therapy | use of high-energy radiation to damage the DNA of cancer cells, which kills them or keeps them from dividing

radioactive decay | spontaneous decay of an unstable nuclide into another nuclide

radioactive decay series | chains of successive disintegrations (radioactive decays) that ultimately lead to a stable end-product

radioactive tracer | (also, radioactive label) radioisotope used to track or follow a substance by monitoring its radioactive emissions

radioactivity | phenomenon exhibited by an unstable nucleon that spontaneously undergoes change into a nucleon that is more stable; an unstable nucleon is said to be radioactive

radiocarbon dating | highly accurate means of dating objects 30,000–50,000 years old that were derived from once-living matter; achieved by calculating the ratio of in the object vs. the ratio of in the present-day atmosphere

radioisotope | isotope that is unstable and undergoes conversion into a different, more stable isotope

radiometric dating | use of radioisotopes and their properties to date the formation of objects such as archeological artifacts, formerly living organisms, or geological formations

reactor coolant | assembly used to carry the heat produced by fission in a reactor to an external boiler and turbine where it is transformed into electricity

relative biological effectiveness (RBE) | measure of the relative damage done by radiation

roentgen equivalent man (rem) | unit for radiation damage, frequently used in medicine; 100 rem = 1 Sv

scintillation counter | instrument that uses a scintillator—a material that emits light when excited by ionizing radiation—to detect and measure radiation

sievert (Sv) | SI unit measuring tissue damage caused by radiation; takes into account energy and biological effects of radiation

strong nuclear force | force of attraction between nucleons that holds a nucleus together

subcritical mass | amount of fissionable material that cannot sustain a chain reaction; less than a critical mass

supercritical mass | amount of material in which there is an increasing rate of fission

transmutation reaction | bombardment of one type of nuclei with other nuclei or neutrons

transuranium element | element with an atomic number greater than 92; these elements do not occur in nature

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