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An accurate measurement of the intensity and energy spectra of Cosmic Ray electrons and positrons represents a major experimental challenge. Long exposure times and excellent particle identification capabilities are needed in order to cope with the low intensity of the electron and positron fluxes and the overwhelming background from protons and nuclei in cosmic rays. The motivations for such an experimental effort will be briefly discussed and the most recent results revieweved together with the perspectives of future experiments.

In a solid, transport of electricity can occur via negative electrons or via positive holes. In the normal state of superconducting materials experiments show that transport is usually dominated by dressed positive hole carriers. Instead, in the superconducting state experiments show that the supercurrent is always carried by undressed negative electron carriers. These experimental facts indicate that electron-hole asymmetry plays a fundamental role in superconductivity, as proposed by the theory of hole superconductivity.

By using a Hamiltonian based on the coupling through flux lines between electrons and bosons, we have calculated the electron–phonon interaction energy and the electron–electron interaction energy via bosons in an isotropic medium and in a lattice. We have calculated the correction energy to the electron energy due to the electron interaction with acoustic phonons and we have found that in covalent crystals it is of the order of 0.1 eV. Also, we have presented the results for the weak coupling and strong coupling polarons in ionic crystals. By applying this Hamiltonian to electron–electron interaction via mass less bosons we have found an equivalent expression for Coulomb's law, αℏc/R, where α is the fine structure constant.

The work is dedicated to the development of the electron-lattice energy exchange theory in metal particles, including dependence on particle size and electron temperature. We compared, for infinite metal, the expressions for the constants of the electron-lattice energy exchange by using the quantum-kinetic approach, with the classical kinetic approach. Both methods give the same result. But as we show, a quantum-kinetic approach in its standard form, for the metal particles smaller than the mean free path of electrons, cannot be applied, while the classical approach can be easily adjusted for such particle.

We found a new peculiarity of the electron-lattice energy exchange. This exchange essentially depends on temperature if a particle size is in the range near a certain "magic size". The change of the electron temperature can alter (around the "magic size") the number of the acoustic modes, which are involved in energy transfer. As a result, the constant of the electron–phonon interaction in nanoparticles can be either much higher or much lower than the corresponding constant for infinite metal.

Transient phonon transport across cross-planes of aluminum–silicon–aluminum combined films is investigated and the Boltzmann transport equation is incorporated to formulate the energy transport in the combined films. Since electrons and phonons thermally separate in the thin aluminum film during heating, the Boltzmann equation is used separately in the electron and lattice subsystems to account for the energy transport in the aluminum film. Electron–phonon coupling is incorporated for the energy exchange between electron and lattice subsystems in the film. Thermal boundary resistance (TBR) is introduced at the interfaces of the silicon–aluminum films. In order to examine the ballistic contribution of phonons on the phonon intensity distribution in the silicon film, frequency-dependent solution of the Boltzmann equation is used in the silicon film and the film thickness is varied to investigate the size effect on the thermal conductivity in the film. It is found that equivalent equilibrium temperature of phonons remains high at silicon–aluminum interface because of the ballistic contribution of the phonons. Equivalent equilibrium temperature for the electron subsystem becomes higher than that corresponding to phonon temperature at the aluminum–silicon interface.

From femtosecond spectroscopy (fs-spectroscopy) of metals, electrons and phonons reequilibrate nearly independently, which contrasts with models of heat transfer at ordinary temperatures ($T>100$ K). These electronic transfer models only agree with thermal conductivity $(k)$ data at a single temperature, but do not agree with thermal diffusivity $(D)$ data. To address the discrepancies, which are important to problems in solid state physics, we separately measured electronic (ele) and phononic (lat) components of $D$ in many metals and alloys over $\sim$290–1100 K by varying measurement duration and sample length in laser-flash experiments. These mechanisms produce distinct diffusive responses in temperature versus time acquisitions because carrier speeds $(u)$ and heat capacities $(C)$ differ greatly. Electronic transport of heat only operates for a brief time after heat is applied because $u$ is high. High $D_{\mathrm{\text{ele}}}$ is associated with moderate $T$, long lengths, low electrical resistivity, and loss of ferromagnetism. Relationships of $D_{\mathrm{\text{ele}}}$ and $D_{\mathrm{\text{lat}}}$ with physical properties support our assignments. Although $k_{\mathrm{\text{ele}}}$ reaches $\sim 20\times k_{\mathrm{\text{lat}}}$ near 470 K, it is transient. Combining previous data on $u$ with each $D$ provides mean free paths and lifetimes that are consistent with $\sim 298$ K fs-spectroscopy, and new values at high $T$. Our findings are consistent with nearly-free electrons absorbing and transmitting a small fraction of the incoming heat, whereas phonons absorb and transmit the majority. We model time-dependent, parallel heat transfer under adiabatic conditions which is one-dimensional in solids, as required by thermodynamic law. For noninteracting mechanisms, $k\cong \mathrm{\Sigma }{C}_i{k}_i\mathrm{\Sigma }{C}_i/(\mathrm{\Sigma }{C}_i^2)$. For metals, this reduces to $k=k_{\mathrm{\text{lat}}}$ above $\sim$20 K, consistent with our measurements, and shows that Meissner’s equation $(k\cong k_{\mathrm{\text{lat}}}+k_{\mathrm{\text{ele}}})$ is invalid above $\sim$20 K. For one mechanism with multiple, interacting carriers, $k\cong \mathrm{\Sigma }{C}_i{k}_i/(\mathrm{\Sigma }{C}_i)$. Thus, certain dynamic behaviors of electrons and phonons in metals have been misunderstood. Implications for theoretical models and technological advancements are briefly discussed.

Presented are the conclusions drawn from experimental investigations of the Landau–Pomeranchuk–Migdal (LPM) effect in amorphous and crystalline targets as well as the preceding and ensuing theoretical activities. In amorphous targets the phenomenon is by now well studied both experimentally and theoretically and is at a mature stage where extrapolations to other energies or materials are well founded. In crystalline targets, the effect is not as well studied as it is harder to deconvolute from other effects like e.g. multiple photon emission. Even in this case, though, a seemingly consistent picture of the suppression mechanism that alters the effective radiation length emerges. Due to the increased scattering, crystals might be used to explore hitherto untested regimes of the LPM effect.

Recent results on the semiclassical dynamics of an electron in a solid are explained using techniques developed for "exotic" Galilean dynamics. The system is indeed Hamiltonian and Liouville's theorem holds for the symplectic volume form. Suitably defined quantities satisfy hydrodynamic equations.

By using a Hamiltonian of interaction between fermions via bosons¹ we derive some properties of the electro-phonon and electron-photon interaction and also of the electron-electron interaction. We have obtained that in a degenerate electron gas there is an attraction between two electrons via acoustical phonons. Also, in certain conditions, there may be an attraction between two electrons via longitudinal optical phonons. Although our expressions for the polaron energy in both cases of the acoustical and longitudinal optical phonons are different from that obtained in the standard theory, their magnitudes are the same with these and they are in good agreement with experimental data. The total emission rate of an electron against a phonon system at absolute zero is directly proportional to the electron momentum. Also, an attraction between two electrons may appear via photons.

Recent research of physical properties of materials have shown that low-dimensional systems have more emphasized characteristics than bulk ones, due to quantum size effects. Superconductive films with higher critical parameters than the bulk ones are especially interesting. The basic characteristic of dispersion law of electrons in superconductive films is the presence of energy gaps. The gap size depends strongly on film thickness. Thermodynamic behavior of this system is strongly influenced by gap presence. Electron contribution in specific heat and entropy of superconductive thin film were analyzed on the basis of electron dispersion law in long-wave approximation, as well as their behavior in low temperature (T<T_C). It has been shown that both of them linearly depend on temperature, similarly as in bulk structures, but with different slope coefficient (film heat capacity is lower and entropy is higher than in the bulk at the same temperature). Due to poor heat (as well as electric) conducting properties, films are better superconductors (which is experimentally proved). Films are also less ordered systems and closer to the equilibrium state. The explanation of high temperature superconductivity can be found by studying spatially-bounded systems.

Electron subsystem of ultrathin films was analyzed using Green's function method including quantum size effect and effect of boundaries on Hamiltonian parameters. We have calculated basic physical properties of electrons in crystalline films: energy spectra, possible states, space distribution of electrons and the position of Fermi level, which enabled the complete insight into the thermodynamic or conducting characteristics of observed film-structure. The comparison with crystal bulk have shown that electronic properties of the materials are strongly influenced by both the sample dimensions and boundary conditions. The numerical calculations performed for very thin crystalline metallic-like films show that localized states and spatial distribution of the (quasi)free electrons might be manipulated by varying the surface parameters which is significant for operation of devices based on thin films.

Particle beam radiography, which uses a variety of particle probes (neutrons, protons, electrons, gammas and potentially other particles) to study the structure of materials and objects noninvasively, is reviewed, largely from an accelerator perspective, although the use of cosmic rays (mainly muons but potentially also high-energy neutrinos) is briefly reviewed. Tomography is a form of radiography which uses multiple views to reconstruct a three-dimensional density map of an object. There is a very wide range of applications of radiography and tomography, from medicine to engineering and security, and advances in instrumentation, specifically the development of electronic detectors, allow rapid analysis of the resultant radiographs. Flash radiography is a diagnostic technique for large high-explosive-driven hydrodynamic experiments that is used at many laboratories. The bremsstrahlung radiation pulse from an intense relativistic electron beam incident onto a high-Z target is the source of these radiographs. The challenge is to provide radiation sources intense enough to penetrate hundreds of g/cm² of material, in pulses short enough to stop the motion of high-speed hydrodynamic shocks, and with source spots small enough to resolve fine details. The challenge has been met with a wide variety of accelerator technologies, including pulsed-power-driven diodes, air-core pulsed betatrons and high-current linear induction accelerators. Accelerator technology has also evolved to accommodate the experimenters' continuing quest for multiple images in time and space. Linear induction accelerators have had a major role in these advances, especially in providing multiple-time radiographs of the largest hydrodynamic experiments.

It has been shown that when electrons are transferred through chiral molecules, the efficiency of the transfer depends on the electron’s spin and on the handedness of the chiral potential. Hence, chiral molecules serve as spin filters. This effect is termed chiral-induced spin selectivity (CISS). The dependence of the CISS effect on the molecular properties is discussed here as well as some implications of the effect such as in bio-recognition and in the interaction of chiral molecules with ferromagnetic substrates. The role of the CISS effect in various fields is also reviewed.

An accurate measurement of the intensity and energy spectra of Cosmic Ray electrons and positrons represents a major experimental challenge. Long exposure times and excellent particle identification capabilities are needed in order to cope with the low intensity of the electron and positron fluxes and the overwhelming background from protons and nuclei in cosmic rays. The motivations for such an experimental effort will be briefly discussed and the most recent results revieweved together with the perspectives of future experiments.

The CALorimetric Electron Telescope, CALET, is a new Space Observatory being developed for the Japanese Experiment Module Exposed Facility, JEM-EF, of the International Space Station. Major scientific objectives are to search for nearby cosmic ray sources and dark matter by carrying out a precise measurement of the electron spectrum from 10's of GeV - 10 TeV and of gamma rays in the range 20 MeV - several TeV. CALET has a unique capability to observe electrons and γ-rays over 1 TeV, with a hadron rejection power better than 10⁵ and an energy resolution of a few % beyond 100 GeV. Moreover, CALET will follow PAMELA, GLAST and other experiments and can both extend and refine the observations made by those missions. The main instrument, to be described, consists of an imaging calorimeter combined with a total absorption calorimeter. With auxiliary detectors, the CALET Observatory will also monitor solar activity and study γ-ray bursts. The phase A/B study is underway for a proposed 2013 launch on the H-II Transfer Vehicle (HTV) for 3-5 years of observation on JEM-EF.

Dirac fermions and electromagnetic fields are considered as the source of gravitation in the framework of standard Friedmann-Lemaître-Robertson-Walker (FLRW) cosmology. It is shown that all solutions for the scale-factor a(t) are non-singular, provided the cosmological constant Λ is set to be less than the positive inverse of a quantum scale.

Electron phase microscopy based on the Aharonov-Bohm (AB) effect principle has been used to illuminate fundamental phenomena concerning superconductivity and magnetism by revealing the microscopic distributions of magnetic flux. These phenomena include the unconventional behaviors of interlayer Josephson vortices in anisotropic layered high-Tc superconducting YBa₂Cu₃O_7-δ (YBCO) thin films, which show various behaviors, especially when the applied magnetic field is greatly tilted to the layer plane, and the magnetization of tiny magnetic heads for perpendicular recording.

Particle beam radiography, which uses a variety of particle probes (neutrons, protons, electrons, gammas and potentially other particles) to study the structure of materials and objects noninvasively, is reviewed, largely from an accelerator perspective, although the use of cosmic rays (mainly muons but potentially also high-energy neutrinos) is briefly reviewed. Tomography is a form of radiography which uses multiple views to reconstruct a three-dimensional density map of an object. There is a very wide range of applications of radiography and tomography, from medicine to engineering and security, and advances in instrumentation, specifically the development of electronic detectors, allow rapid analysis of the resultant radiographs. Flash radiography is a diagnostic technique for large high-explosive-driven hydrodynamic experiments that is used at many laboratories. The bremsstrahlung radiation pulse from an intense relativistic electron beam incident onto a high-Z target is the source of these radiographs. The challenge is to provide radiation sources intense enough to penetrate hundreds of g/cm² of material, in pulses short enough to stop the motion of high-speed hydrodynamic shocks, and with source spots small enough to resolve fine details. The challenge has been met with a wide variety of accelerator technologies, including pulsed-power-driven diodes, air-core pulsed betatrons and high-current linear induction accelerators. Accelerator technology has also evolved to accommodate the experimenters' continuing quest for multiple images in time and space. Linear induction accelerators have had a major role in these advances, especially in providing multiple-time radiographs of the largest hydrodynamic experiments.

I provide references to the latest AMS publications on cosmic-ray electron and positron fluxes.