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Particle Detection
Published in Walter Fox Smith, Experimental Physics, 2020
There are other, rarer forms of radioactive emission as well. For example, some isotopes undergo spontaneous neutron emission, and neutrons can be emitted in spontaneous or induced fission processes such as in nuclear reactors. Neutrons are extremely penetrating and require a substantial amount of concrete or water, often doped with a neutron absorber like 10B, to stop them. However, since spontaneous neutron emission is a very rare process, it will not be considered in this chapter.
Application Specific Integrated Circuits for Direct X-Ray and Gamma-Ray Conversion in Security Applications
Published in Choi Jung Han, Iniewski Krzysztof, High-Speed and Lower Power Technologies, 2018
Krzysztof Iniewski, Chris Siu, Adam Grosser
Radioactive radiation takes several forms: Alpha particles: Alpha particles (α) consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus. They are generally produced in the process of alpha decay (α-decay) where an atomic nucleus emits an alpha particle (helium nucleus) and thereby transforms or ‘decays’ into an atom with a mass number that is reduced by four and an atomic number that is reduced by two. Because they are massive by subatomic standards, alpha particles must carry off a considerable amount of energy to escape the nucleus; at the same time, because of their mass they can only travel few centimeters in air. They are stopped by a sheet of paper or the dead outer layers of skin.Beta particles: A beta particle (β), is a high-energy, high-speed electron or positron emitted in the radioactive decay of an atomic nucleus, such as a potassium-40 nucleus, in the process of beta decay. Two forms of beta decay, β− and β+, respectively produce electrons and positrons. Beta particles are much less massive than alpha particles, so they can travel up to a meter in air, but are less energetic than alpha particles. Some are stopped by outer layers of skin, while others can penetrate a few millimeters.Neutrons: Some radionuclides decay by emitting a neutron. Neutron emission is a mode of radioactive decay in which one or more neutrons are ejected from a nucleus. It occurs in the most neutron-rich/proton-deficient nuclides, and also from excited states of other nuclides. As only a neutron is lost by this process the number of protons remains unchanged, and an atom does not become an atom of a different element, but a different isotope of the same element. Neutrons are lighter than alpha particles but much heavier than beta particles. They can travel tens of meters in air. Neutrons are typically stopped by hydrogen-containing material, such as water or plastic. Energetic neutrons can penetrate the human body.Gamma rays: Gamma rays (γ) are highly energetic photons released during radioactive decay arising from the radioactive decay of atomic nuclei. French chemist Paul Villard discovered gamma radiation in 1900 while studying radiation emitted by radium, a radioactive material discovered by Polish scientist Marie Curie-Skłodowska. Gamma rays have a wide range of energies, can travel kilometers in air and can penetrate the human body. causing biological damage. They can be stopped by dense material like lead.
Improved Disposition of Surplus Weapons-Grade Plutonium Using a Metallic Pu-Zr Fuel Design
Published in Nuclear Technology, 2023
Braden Goddard, Aaron Totemeier
Equations (2) and (3) were used on three different plutonium isotopic compositions to determine FOM values using the Bathke et al. material attractiveness methodology. The three compositions consisted of weapons-grade plutonium, plutonium from used MOX (5% Pu) fuel, and plutonium from used PDR (16% Pu) fuel. The bare critical masses of the plutonium isotopic compositions were determined though k-code MCNP simulations. These values were 16.3 kg for weapons grade, 21.9 kg for MOX (5% Pu), and 35.4 kg for PDR (16% Pu). The heat generation and spontaneous fission neutron emission rates were determined by combining the plutonium isotopic composition with known nuclear data.27,48 The radiation dose rate attribute was estimated to be negligible based on previous studies of plutonium compositions.49 The FOM1 and FOM2 values are shown in Table IV for the three fuel rods analyzed.
Examination of (α,n) Signatures as a Means of Plutonium Quantification in Electrochemical Reprocessing
Published in Nuclear Science and Engineering, 2021
Stephen N. Gilliam, Jamie B. Coble, Steven E. Skutnik
The simulation of neutron emission rates was done in MATLAB and accomplished via calculations provided in the SOURCES-4C manual and parsing the necessary parameters from ORIGEN (Ref. 11). This was done for spontaneous fission and (α,n) neutrons; the summation of the two gives the total neutron emission rate. This method of simulation allows the emitted neutrons to be traced back to a specific reaction. To verify that the equations provided within the SOURCES-4C manual were implemented correctly, validation runs were completed by comparing the results of the MATLAB code to that of ORIGEN-generated outputs. The results of validation testing can be seen in Figs. 3 and 4. The MATLAB simulations reproduced the ORIGEN results to sufficient fidelity, within 0.5% for the spontaneous fission emissions and 3.5% for the (α,n) emissions.
Energy dependent calculations of fission product, prompt, and delayed neutron yields for neutron induced fission on 235U, 238U, and 239Pu
Published in Journal of Nuclear Science and Technology, 2022
Shin Okumura, Toshihiko Kawano, Amy Elizabeth Lovell, Tadashi Yoshida
When a decay branch includes a neutron emission mode, this nuclide is identified as a -delayed neutron precursor. The delayed neutron yield from this -th precursor is calculated as , where is the branching ratio to the neutron-decay mode, and is usually one unless multiple neutron emission is allowed. The total delayed neutron yield is .