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Applied Chemistry and Physics
Published in Robert A. Burke, Applied Chemistry and Physics, 2020
Symbols and names of elements are derived from a number of sources. They may have been named after the person who discovered the element. For example, W which is the symbol for tungsten is named after Wolfram, the discoverer. Other elements are named after famous scientists, universities, cities and states. Es is the symbol for einsteinium, named after Albert Einstein. Cm is the symbol for curium, named after Madam Curie. Bk is the symbol for berkelium, named after the city of Berkeley, California. Cf is the symbol for the element californium, named after the state of California. Other element names come from Latin, German, Greek and English languages. In the case of sodium, Na comes from the Latin word for natrium. Au, the symbol for gold, comes from aurum, meaning “shining down” in Latin. Cu (copper) comes from the Latin cuprum or cyprium because the Roman source for copper was the island of Cyprus. Fe (iron) comes from the Latin ferrum. Bromine means “stinch” in Greek. Rubidium means red in color. Mercury is sometimes referred to as quick silver. Sulfur is referred to as brimstone in the Bible.
Neutron Optics: Fundamentals
Published in Maria L. Calvo, Ramón Fernandez Álvarez-Estrada, Advances in Neutron Optics, 2019
Ramón F. Álvarez-Estrada, Maria L. Calvo
Californium (98252Cf) is a source of neutrons. 98252Cf suffers spontaneous nuclear fission, which gives rise to fast neutrons. The half-life of 98252Cf is 2.6 years; his implies that, as a neutron source emitting in the beginning 107 to 109 neutrons per second, it may require a relatively frequent replacement. We shall comment later in Subsection 1.2.6 on one recent application of this type of source.
Neutron Waveguides and Applications
Published in María L. Calvo, Vasudevan Lakshminarayanan, Optical Waveguides, 2018
Ramón F. Alvarez-Estrada, María L. Calvo
Californium (98252Cf) is a source of neutrons. 98252Cf suffers spontaneous nuclear fission, which gives rise to fast neutrons. The half-life of 98252Cf is 2.6 years, which implies that, as a neutron source, it may require a relatively frequent replacement. We shall comment later in Subsection 9.2.5 on one recent application of this type of source.
Gamma ray and fast neutron shielding of ZrSiO4-Al2O3 ceramic refractor
Published in Particulate Science and Technology, 2023
Mahmoud Gharieb, Sayed H. Kenawy, Gehan T. El-Bassyouni, Esmat M. A. Hamzawy
Fast neutron attenuation is described by an additional parameter named the removal cross-section [ΣR (cm−1)], which has a fraction of the total macroscopic cross-section. [ΣR (cm−1)] is the removal cross-section of the fast neutrons was sustained using identifier target detector as shown in Figure 2. [ΣR (cm−1)] is the chance that a fast or fission energy neutron undergoes at first collision which eliminates it from penetrating group of un-collided neutrons (Duderstadt and Hamilton 1976). The radiation-shielding tests were performed using californium radioisotope (Cf252) as the source. Californium (Cf) is a metallic chemical element with atomic number of 98. Many isotopes of this element exist; however, the most relevant of them is the Cf−252 isotope. It was nominated because it is a very good source of neutrons, with a single microgram capable of emitting millions of neutrons/min. Therefore, small volume of this isotope is required, to be encapsulated and used as a neutron source. Its average energy of neutrons is 2.35 MeV (Malidarre and Akkurt 2021; Malidarre, Akkurt, and Kavas 2021). In fact, the fast neutrons are not directly absorbed during their passage through the shielding hydrogenated, but they slow primarily by successive elastic collisions with the nuclei of light elements. The effective removal cross-section [ΣR (cm−1)] for homogeneous mixtures, concretes, composites, and compounds may be calculated by the following formula as in Equation (8): (Kaplan 1989; El-Khayatt and El-Sayed Abdo 2009; El-Khayatt 2010).
Solvent extraction systems for mutual separation of Am(III) and Cm(III) from nitric acid solutions. A review of recent state-of-the-art
Published in Solvent Extraction and Ion Exchange, 2021
Petr Matveev, Prasanta K. Mohapatra, Stepan N. Kalmykov, Vladimir Petrov
The americium isolation stage can be performed during sequential extraction processes (for example, a series of PUREX-DIAMEX-LUCA processes[20]) or directly from PUREX-raffinate (for example, the EXAm process[21]), which requires selectivity to americium against the background of all elements presented in the HLW. While actinide partitioning extractants viz. CMPO (carbamoylmethylphosphine oxide), malonamides, diglycolamides, etc. can extract the trivalent actinides, the trivalent lanthanides present in the HLW are co-extracted. The most difficult task is the separation of trivalent actinides from the lanthanides and even more challenging is the separation of Am and Cm. This separation is necessary for the following reasons: Lanthanides are neutron poisons – some isotopes have high neutron capture cross sections (see Table 1). Their presence in the fuel (or irradiated target) together with the minor actinides will inhibit the transmutation of americium[20,25]The involvement of curium-242,244 in the closed fuel cycle is problematic because it has a high neutron and heat emission (Table 2). For this reason, the presence of curium will complicate the fabrication and operation of nuclear fuel (or targets for irradiation). In addition, curium-244 can be used as the starting material for the production of californium-252,[27–29] a radionuclide that is used as a neutron source in many applications including in nuclear medicine. Thus, curium must be isolated in the individual form.