Energy Loss Of Charged Particles Research Articles

A quantum theory of refractive index, Čerenkov radiation and the energy loss of a fast charged particle

A quantum theory of the three related subjects of refractive index, Čerenkov radiation, and the excitation and ionization of atoms in a polarisable medium is developed. The classical theory of the electromagnetic field in a medium of extended dipoles is first written in hamiltonian form. This makes obvious a canonical transformation related to refractive index which enables one to express the total field in the medium as a superposition of oscillators. A similar transformation is made on the quantised radiation field variables, which takes account of the modified time dependence of the field due to its interaction with the medium. The processes of Čerenkov radiation and the ionization and excitation of atoms in a polarisable medium are then treated. The partition of the total energy loss between these different primary processes is obtained directly. This is done by making a perturbation expansion on the basis of physical-photon states for processes caused by the passage of a fast charged particle through the medium. For the case in which the reaction of the medium on the particle is neglected we obtain formulae which agree with those obtained previously by other authors i.e., in the first approximation the quantum theory frequently gives the same result as the classical theory for these processes.

Density Effect in Ionization Energy Loss of Charged Particles

A more rigorous justification is given for the statement made by Aage Bohr that for an incident particle of relativistic velocity, the electrostatic effect of the surrounding electrons is negligible and the main factor in the screening is due to the electromagnetic interactions which limit the impact parameter to a value $\frac{c}{\ensuremath{\Omega}}$, where $\ensuremath{\Omega}={(\frac{4\ensuremath{\pi}n{e}^{2}}{m})}^{\frac{1}{2}}$ and $n$ is the electron density in the medium.

Plasma Oscillations and Energy Loss of Charged Particles in Solids

It is shown that the frequencies of logitudinal electric oscillations in solids satisfy the condition (ω)=0, where (ω) is the dielectric constant for the frequency ω/2π which can be obtained from the optical constants n, κ. Such longitudinal waves include so-called plasma oscillations. It is shown that energy losses of fast charged particles in discrete steps hωp (the plasma quantum) can be expected only if the quantity nκ/(n2 + κ2)2 has a sharp maximum at a frequency ωp. This holds for the alkali metals and for silver.

Ionization and Excitation Losses of Charged Particles of Intermediate Energies

A method has been outlined for determining energy losses of charged particles of intermediate energies, i.e. which do not carry bound electrons and have velocities lower than the K shell velocity of the stopping atom. The `free collisions' and the `resonance effects' have been separately evaluated.

Note on the Collision Energy Loss of Fast Charged Particle

Note on the Collision Energy Loss of Fast Charged Particle

Zur Theorie der Bremsung Schneller Geladener Teilchen in Metallischen Leitern

The theory of metals, as developed by Sommerfeld, Bloch and others, leads in the first instance to an infinite contribution of the conduction electrons to the energy losses of fast charged particles traversing a metal. In contrast to v. Weizsäcker, who showed that upon considering the energy transfer from the conduction electrons to the metallic ions the energy losses become finite, we wish to ascribe their limitation to the mutual interaction of the conduction electrons, inadequately taken into account in the theories mentioned. Treating the conduction electrons as a negatively charged fluid by hydrodynamic methods, a formula for the energy losses can be derived in harmony with experimental facts. It appears that the friction of the negative fluid with respect to the positive substratum of the metallic ions, which is the cause of Ohmic resistance, is of no importance in the discussion of these energy losses, but that they are almost entirely due to the internal friction of the negative fluid. The coefficient of internal friction is estimated from the empirical data in the case of lithium and found to agree with the theoretical expectation.

Theory of energy losses of high energy particles

We propose changes in the GHEISHA 67 code concerning the simulation of energy loss of charged particles. δ-rays, multiple scattering, negative particle absorption, light quenching in scintillators, and neutron capture. These changes have a profound theoretical motivation and are supported by comparing the resulting detector simulation with Crystal Ball data.