Principles of Instrumentation for Radiobioassay
Fuad S. Ashkar, Lelio G. Colombetti in Radiobioassays, 2019
Radioactivity can be defined as the emission of particles or photons (electromagnetic radiation) from the nucleus. There are three modes of decay: Alpha decay: the spontaneous emission of a helium nucleus from the decaying isotope; this is unimportant to the subject of this chapter and will not be discussedBeta decay: the emission of electrons or positrons from the nucleusGamma decay: the emission of electromagnetic radiation from the nucleus
Nuclear Physics Fundamentals Milorad Mladjenovic
Frank Helus, Lelio G. Colombetti in Radionuclides Production, 2019
There are two outstanding characteristics of alpha decay. First, the energy range is relatively narrow for a given element. Most of the alpha-particle energies fall within the interval of 4 to 7 MeV. Lower alpha-particle energies are rather infrequent, but may be as low as 2 MeV for lighter elements, where the barrier is smaller. In a few special cases, an alpha-particle energy of 10 MeV is encountered.
Fundamental Concepts and Quantities
Shaheen A. Dewji, Nolan E. Hertel in Advanced Radiation Protection Dosimetry, 2019
The process of alpha decay is of interest since the total potential energy acting on an alpha particle includes the nuclear force and Coulombic repulsion effects. In fact, according to classical physics models, alpha decay could not occur. The Coulombic repulsion felt by an alpha particle (with a +2 charge) that is in contact with a nucleus is
GOLD: human exposure and update on toxic risks
Published in Critical Reviews in Toxicology, 2018
Alan B. G. Lansdown
At least 70 isotopes of gold are known, some with half lives of <10 milliseconds, but only one stable isotope of gold (197Au) is known (Shuh et al. 2012). Decay modes of the 36 radioactive isotopes include proton emission, alpha decay, or electron capture. Radioactive gold nanoparticles (AuNP) (198Au or 199Au) are potentially beneficial in experimental anti-cancer therapies, radiotherapy and diagnostic medicine (Chanda et al. 2010; Chithrani et al. 2010; Haume et al. 2016). Several cases have been reported where skin cancer has been associated with “radioactivity emitted by gold rings” (Baptiste et al. 1984; Callery 1989; Miller and Aldrich 1990). Thus, Baptiste evaluated 135 individuals exposed to radioactively contaminated rings and reported nine cases of squamous cell carcinoma on the fingers. Elsewhere, Callery emphasized that the radioactivity emitted from the rings was not attributable to any radioactive isotope of gold but probably to contamination with emissions of radon gas (Callery 1989). Miller and Aldrich estimated that skin cancer in a lady who wore one such radioactive gold ring for 37 years was due to a radiation dose equivalent to 240 Gy/week and a maximum dose of 4800Gy (Miller and Aldrich 1990). In the early days of radium therapy for cancer, small hollow “gold-seeds containing radioactive radon gas were implanted into solid tumors. As discussed below, there is no evidence that stable gold (197Au) is carcinogenic in humans. (Gold beads implanted into tumors are still used widely in diagnostic medicine.)
Radiological risk assessment of the Hunters Point Naval Shipyard (HPNS)
Published in Critical Reviews in Toxicology, 2022
Dennis J. Paustenbach, Robert D. Gibbons
Pu-239 has a radioactive half-life of 24,110 years and is produced when uranium absorbs a neutron. Small amounts of plutonium occur naturally, but large quantities have been produced in nuclear reactions or released from atmospheric nuclear weapons tests. Pu-239 transitions by alpha decay. Its decay products emit alpha, beta, and gamma radiation depending upon which radionuclide is being evaluated and can pose both an internal and external radiation hazard. Pu-239 is present in most soils in the United States at various concentrations (ICRP 2008; Johnson et al. 2012). The potential for Pu-239 to be present on ships returning from nuclear weapons tests in the Pacific and Pu-239 use in calibrating radiation detection equipment were primary reasons it was identified as an ROC at HPNS (USN 2004).
Related Knowledge Centers
- Alpha Particle
- Antimony
- Atom
- Beta Decay
- Helium
- Radioactive Decay
- Thorium
- Atomic Nucleus
- Nickel
- Cluster Decay