Related Research Articles
A Geiger counter is an instrument used for detecting and measuring ionizing radiation. Also known as a Geiger–Muller counter, it is widely used in applications such as radiation dosimetry, radiological protection, experimental physics, and the nuclear industry.
Neutron activation analysis (NAA) is the nuclear process used for determining the concentrations of elements in a vast amount of materials. NAA allows discrete sampling of elements as it disregards the chemical form of a sample, and focuses solely on its nucleus. The method is based on neutron activation and therefore requires a source of neutrons. The sample is bombarded with neutrons, causing the elements to form radioactive isotopes. The radioactive emissions and radioactive decay paths for each element are well known. Using this information, it is possible to study spectra of the emissions of the radioactive sample, and determine the concentrations of the elements within it. A particular advantage of this technique is that it does not destroy the sample, and thus has been used for analysis of works of art and historical artifacts. NAA can also be used to determine the activity of a radioactive sample.
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes:
A beta particle, also called beta ray or beta radiation, is a high-energy, high-speed electron or positron emitted by the radioactive decay of an atomic nucleus during the process of beta decay. There are two forms of beta decay, β− decay and β+ decay, which produce electrons and positrons respectively.
Ionizing radiation consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. The particles generally travel over 1% of the speed of light, and the electromagnetic waves are on the high-energy portion of the electromagnetic spectrum.
A scintillation counter is an instrument for detecting and measuring ionizing radiation by using the excitation effect of incident radiation on a scintillating material, and detecting the resultant light pulses.
A radioactive tracer, radiotracer, or radioactive label, is a chemical compound in which one or more atoms have been replaced by a radionuclide so by virtue of its radioactive decay it can be used to explore the mechanism of chemical reactions by tracing the path that the radioisotope follows from reactants to products. Radiolabeling or radiotracing is thus the radioactive form of isotopic labeling.
A scintillator is a material that exhibits scintillation, the property of luminescence, when excited by ionizing radiation. Luminescent materials, when struck by an incoming particle, absorb its energy and scintillate. Sometimes, the excited state is metastable, so the relaxation back down from the excited state to lower states is delayed. The process then corresponds to one of two phenomena: delayed fluorescence or phosphorescence. The correspondence depends on the type of transition and hence the wavelength of the emitted optical photon.
Liquid scintillation counting is the measurement of radioactive activity of a sample material which uses the technique of mixing the active material with a liquid scintillator, and counting the resultant photon emissions. The purpose is to allow more efficient counting due to the intimate contact of the activity with the scintillator. It is generally used for alpha and beta particle detection.
Tritium radioluminescence is the use of gaseous tritium, a radioactive isotope of hydrogen, to create visible light. Tritium emits electrons through beta decay and, when they interact with a phosphor material, light is emitted through the process of phosphorescence. The overall process of using a radioactive material to excite a phosphor and ultimately generate light is called radioluminescence. As tritium illumination requires no electrical energy, it has found wide use in applications such as emergency exit signs, illumination of wristwatches, and portable yet very reliable sources of low intensity light which won't degrade human night vision. Gun sights for night use and small lights used mostly by military personnel fall under the latter application.
An atomic battery, nuclear battery, radioisotope battery or radioisotope generator is a device which uses energy from the decay of a radioactive isotope to generate electricity. Like nuclear reactors, they generate electricity from nuclear energy, but differ in that they do not use a chain reaction. Although commonly called batteries, they are technically not electrochemical and cannot be charged or recharged. In comparison they are very costly, but have an extremely long life and high energy density, and so they are mainly used as power sources for equipment that must operate unattended for long periods of time, such as spacecraft, pacemakers, underwater systems and automated scientific stations in remote parts of the world.
Gamma-ray spectroscopy is the quantitative study of the energy spectra of gamma-ray sources, such as in the nuclear industry, geochemical investigation, and astrophysics.
Radioluminescence is the phenomenon by which light is produced in a material by bombardment with ionizing radiation such as alpha particles, beta particles, or gamma rays. Radioluminescence is used as a low level light source for night illumination of instruments or signage. Radioluminescent paint used to be used for clock hands and instrument dials, enabling them to be read in the dark. Radioluminescence is also sometimes seen around high-power radiation sources, such as nuclear reactors and radioisotopes.
An optoelectric nuclear battery is a type of nuclear battery in which nuclear energy is converted into light, which is then used to generate electrical energy. This is accomplished by letting the ionizing radiation emitted by the radioactive isotopes hit a luminescent material, which in turn emits photons that generate electricity upon striking a photovoltaic cell.
One method for testing of many alpha emitters is to use alpha-particle spectroscopy. For methods of gamma rays and beta particles, please see gamma spectroscopy and liquid scintillation counting respectively.
Radioactivity is generally used in life sciences for highly sensitive and direct measurements of biological phenomena, and for visualizing the location of biomolecules radiolabelled with a radioisotope.
In health physics, whole-body counting refers to the measurement of radioactivity within the human body. The technique is primarily applicable to radioactive material that emits gamma rays. Alpha particle decays can also be detected indirectly by their coincident gamma radiation. In certain circumstances, beta emitters can be measured, but with degraded sensitivity. The instrument used is normally referred to as a whole body counter.
Nuclear MASINT is one of the six major subdisciplines generally accepted to make up Measurement and Signature Intelligence (MASINT), which covers measurement and characterization of information derived from nuclear radiation and other physical phenomena associated with nuclear weapons, reactors, processes, materials, devices, and facilities. Nuclear monitoring can be done remotely or during onsite inspections of nuclear facilities. Data exploitation results in characterization of nuclear weapons, reactors, and materials. A number of systems detect and monitor the world for nuclear explosions, as well as nuclear materials production.
Fluorescence is used in the life sciences generally as a non-destructive way of tracking or analysing biological molecules by means of fluorescence. Some proteins or small molecules in cells are naturally fluorescent, which is called intrinsic fluorescence or autofluorescence. Alternatively, specific or general proteins, nucleic acids, lipids or small molecules can be "labelled" with an extrinsic fluorophore, a fluorescent dye which can be a small molecule, protein or quantum dot. Several techniques exist to exploit additional properties of fluorophores, such as fluorescence resonance energy transfer, where the energy is passed non-radiatively to a particular neighbouring dye, allowing proximity or protein activation to be detected; another is the change in properties, such as intensity, of certain dyes depending on their environment allowing their use in structural studies.
A ligand binding assay (LBA) is an assay, or an analytic procedure, which relies on the binding of ligand molecules to receptors, antibodies or other macromolecules. A detection method is used to determine the presence and extent of the ligand-receptor complexes formed, and this is usually determined electrochemically or through a fluorescence detection method. This type of analytic test can be used to test for the presence of target molecules in a sample that are known to bind to the receptor.
References
- ↑ Homogeneous Proximity Tyrosine Kinase Assays: Scintillation Proximity Assay versus Homogeneous Time-Resolved Fluorescence. Analytical Biochemistry Volume 269, Issue 1, 10 April 1999, Pages 94-104.