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Basic Atomic and Nuclear Physics
Published in Douglas S. McGregor, J. Kenneth Shultis, Radiation Detection, 2020
Douglas S. McGregor, J. Kenneth Shultis
In all nuclear interactions, including radioactive decay, there are several quantities that are always conserved or unchanged by the nuclear transmutation. The most important of these conservation laws include: Conservation of charge, i.e., the number of elementary positive and negative charges in the reactants must be the same as in the products.Conservation of the number of nucleons, i.e., A is always constant. With the exception of EC and β± radioactive decay, in which a neutron (proton) transmutes into a proton (neutron), the number of protons and neutrons is also generally conserved.Conservation of mass/energy (total energy). Although, neither rest mass nor kinetic energy is generally conserved, the total (rest-mass energy equivalent plus kinetic energy) is conserved.Conservation of linear momentum. This quantity must be conserved in all inertial frames of reference.Conservation of angular momentum. The total angular momentum (or the spin) of the reacting particles must always be conserved.
The Nature of Light
Published in Abdul Al-Azzawi, Photonics, 2017
A crucial difference between particles such as electrons and neutrons and particles like photons is that the photons have zero rest mass. Equation (1.3) through Equation (1.5) then take the simpler form for photons: M=Ecλ=hM=hcEv=Mc2E=c
Silicon Radiation Sensors
Published in Cinzia Da Vià, Gian-Franco Dalla Betta, Sherwood Parker, Radiation Sensors with Three-Dimensional Electrodes, 2019
Cinzia Da Vià, Gian-Franco Dalla Betta, Sherwood Parker
Photons are the particles associated to the quantum description of the electromagnetic field, which are generated during the relaxation of an atom or a nucleus that have absorbed energy. Photons have zero rest mass, and they travel at the speed of light (c) in vacuum. They can be described either as particles carrying a certain energy (Eph) or as waves of a certain frequency (ν) or wavelength (λ). These parameters are strictly related by Eqn. 2.3: Eph=hυ=hcλ
Investigation of Neutron Cross Section for Iron in the ENDF Library with Pulsed Sphere Measurements
Published in Nuclear Science and Engineering, 2019
Sushil Dhakal, Carl R. Brune, Thomas N. Massey, Steven M. Grimes, Alexander V. Voinov, Shamim Akhtar, Anthony P. D. Ramirez, Andrea L. Richard
where =kinetic energy of the neutron =distance from the point where neutron is produced to the detector =speed of light =TOF of the neutron =rest mass of the neutron.
Tantalum, Titanium, and Zirconium Neutron Total Cross-Section Measurements from 0.4 to 25 MeV
Published in Nuclear Science and Engineering, 2019
M. J. Rapp, D. P. Barry, G. Leinweber, R. C. Block, B. E. Epping, T. H. Trumbull, Y. Danon
where =energy for TOF =rest mass energy of a neutron =flight path distance =neutron TOF =speed of light in vacuum.
Vacuum friction
Published in Journal of Modern Optics, 2018
Stephen M. Barnett, Matthias Sonnleitner
where m is the mass of the atom. This effect is certainly small: it is proportional to the ratio of the photon energy to the rest mass energy of the atom and this ratio is typically of the order . There is an important point of principle, however, in that if the deceleration exists, whatever its value, then we have a conflict with relativity, both of the Einsteinian and Galilean forms. To emphasize this point we can integrate this equation to find the net change in the velocity of the atom: