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Coherent effects of ultra-relativistic particles in crystals is an area of science under development. DYNECHARM + + is a toolkit for the simulation of coherent interactions between high-energy charged particles and complex crystal structures. The particle trajectory in a crystal is computed through numerical integration of the equation of motion. The code was revised and improved in order to exploit parallelization on multi-cores and vectorization of single instructions on multiple data. An Intel Xeon Phi card was adopted for the performance measurements. The computation time was proved to scale linearly as a function of the number of physical and virtual cores. By enabling the auto-vectorization flag of the compiler a three time speedup was obtained. The performances of the card were compared to the Dual Xeon ones.

Charged particles interacting with a bent crystal can be trapped in channeling states and deflected by the atomic planes of the crystal lattice. The use of bent crystals for beam manipulation in particle accelerators is a well assessed concept rapidly evolving into practical applications. In the last three decades, a large number of experimental findings have contributed to clarify our knowledge and to improve our control of crystal–particle interactions. Bent crystals can impart angular deflections to the incoming particles, through channeling or volume reflection mechanisms. The efficiency of the latter mechanism has been found to be intrinsically very large, whilst the channeling efficiency has been improved by the increased technological expertize in crystal cutting and bending. In this paper, we review the recent milestones of the worldwide effort to propose a routine use of bent crystals in particle accelerators, with a specific attention to the proposals of promoting the use of bent crystals as primary element in beam halo collimation systems.

2008 accomplished the 100^th anniversary from the birth of L.D. Landau (Nobel Prize 1962). In the paper a short description of Kharkov period of Landau's work from 1932 to 1937 is given. One of areas of his work is connected with investigation of bremsstrahlung by ultra relativistic electrons in matter. In this paper a short review of the results obtained studying both Landau-Pomeranchuk-Migdal effect and coherent radiation by high-energy electrons and positrons in crystals, is given. The main attention is paid to the general properties and difference of radiation processes in amorphous media and in a crystal and to advances in the coherent bremsstrahlung studies.

The energy and momentum conservation laws prohibit positron–electron single-photon annihilation in vacuum. It is shown that the situation is different in a single crystal with one of the leptons (e.g. positron) moving in the channeling (or in the quasi-channeling) mode. The transverse motion of an oriented or channeled particle may sharply increase the probability of the single-photon annihilation process.

The process of radiation of 120 GeV positrons moving in a channeling regime in (011) plane of a single crystal was considered. At the beginning on the basis of the theory of nonlinear oscillations, the trajectory of moving positrons at different initial conditions was derived. Then taking into account the nonlinearity of motion, the distribution function over oscillation amplitudes of channeling particles was found. After this, the intensity of radiation at different initial conditions was calculated with the help of two various methods. These results may be useful for comparison with experimental data at positron energies from 100 and more GeV.

Aspirations of modern high energy particle physics call for compact and cost efficient lepton and hadron colliders with energy reach and luminosity significantly beyond the modern HEP facilities. Strong interplanar fields in crystals of the order of 10–100 V/Å can effectively guide and collimate high energy particles. Besides continuous focusing crystals plasma, if properly excited, can be used for particle acceleration with exceptionally high gradients $O$(TeV/m). However, the angstrom-scale size of channels in crystals might be too small to accept and accelerate significant number of particles. Carbon-based nano-structures such as carbon-nanotubes (CNTs) and graphenes have a large degree of dimensional flexibility and thermo-mechanical strength and thus could be more suitable for channeling acceleration of high intensity beams. Nano-channels of the synthetic crystals can accept a few orders of magnitude larger phase-space volume of channeled particles with much higher thermal tolerance than natural crystals.

This paper presents conceptual foundations of the CNT acceleration, including underlying theory, practical outline and technical challenges of the proof-of-principle experiment. Also, an analytic description of the plasmon-assisted laser acceleration is detailed with practical acceleration parameters, in particular with specifications of a typical tabletop femtosecond laser system. The maximally achievable acceleration gradients and energy gains within dephasing lengths and CNT lengths are discussed with respect to laser-incident angles and the CNT-filling ratios.

The electromagnetic radiation generated by ultra-relativistic positrons channeling in a crystalline undulator is discussed. The crystalline undulator is a crystal whose planes are bent periodically with the amplitude much larger than the interplanar spacing. Various conditions and criteria to be fulfilled for the crystalline undulator operation are established. Different methods of crystal bending are described. We present the results of numeric calculations of spectral distributions of the spontaneous radiation emitted in the crystalline undulator and discuss the possibility to create the stimulated emission in such a system in analogy with the free electron laser. A careful literature survey covering the formulation of all essential ideas in this field is given. Our investigation shows that the proposed mechanism provides an efficient source for high energy photons, which is worth studying experimentally.

We report here on total and partial charge changing cross-sections of 158A GeV lead projectiles on Al, Cu, Pb and Bi stationary targets using CR-39 detectors. Present results are compared with relevant published results. Deep discussion of nuclear fragmentation processes is provided. Stacks of CR-39 Track Detectors with above-mentioned targets were exposed to 158A GeV²⁰⁷Pb projectiles at the CERN-SPS beam facility at normal incidence with a fluence of about 1500 ions/cm². Lengths of etched cones on one face of the CR-39 detectors before and after the target were measured for each stack. These measurements were used for determination of total and partial charge changing cross-sections of 158A GeV Pb⁸²⁺ projectiles on these targets in the charge region 63 < Z < 82. The charge resolution (σ_Z) achieved in the present experiment is ~0.18e. Mass changing cross-sections are derived from the measured charge changing cross-sections using hyper-geometric relationship. A new method is proposed for separate measurements of electromagnetic and nuclear parts of fragmentation cross-sections using ion channeling and blocking conditions of projectiles in crystalline targets.

The interaction of accelerated helium atoms with the atomic-smooth surface of tun+gsten single crystals was investigated using the low-temperature field-ion microscope, equipped with the source of helium atoms with an energy of 5 keV together with the techniques of molecular dynamics. It was observed the effect of the surface channeling of fast atoms of a target along the surface steps which occurs as a result of the collision cascade induced by the incident projectile. A substantial part of these displaced atoms in the target gains momentum oriented along the < 111 > close-packed crystallographic directions. The fine morphology of the trajectory of an excited tungsten atom reveals the transverse oscillations of the W atom normally to the < 111 > surface atomic step. The rate of the kinetic energy loss during the surface channeling of fast tungsten atoms does not exceed 0.4 eV/Å. This provides relatively large displaced surface atom ranges along the close-packed atomic steps. The found out results can be regarded as a special case of the correlation mechanism of the radiation-induced surface mass transfer.

We develop sampling expansion formulas on the shift invariant closed subspace V(ϕ) of L²ℝ generated by a frame or a Riesz generator ϕ(t). We find necessary and sufficient conditions under which a regular shifted sampling expansion to hold on V(ϕ) and also introduce a single channel sampling on V(ϕ) together with some illustrating examples.

Ordered structures such as crystalline materials may help to enhance the nuclear interaction yield. Indeed, the aligned atoms act as a single entity on impinging charged particles, causing the trajectory to pass from its random motion to a deterministic one. In fact, Monte Carlo simulations suggested that specific crystal alignments allow for the enhancement of the production rate of nuclear inelastic reactions, because particles are forced to pass by the atomic nuclei more frequently than would happen in an amorphous material. Recent measurements we carried out at the AN2000 accelerator of the National Institute for Nuclear Physics Legnaro National Laboratories showed the experimental evidence of such an effect. A 643.5 keV collimated proton beam was used to induce the ${}^{\mathrm{\text{18}}}$O(p,$\alpha {)}^{\mathrm{\text{15}}}$N reaction in an Al${}_{\mathrm{\text{2}}}$O${}_{\mathrm{\text{3}}}$ substrate oriented along the <0001> axis. The capability of manipulating such an effect paves the way to studying innovative targets for the enhancement of the nuclear interaction yield with a constant density.

Aspirations of modern high energy particle physics call for compact and cost efficient lepton and hadron colliders with energy reach and luminosity significantly beyond the modern HEP facilities. Strong interplanar fields in crystals of the order of 10−100 V/Å can effectively guide and collimate high energy particles. Besides continuous focusing crystals plasma, if properly excited, can be used for particle acceleration with exceptionally high gradients O(TeV/m). However, the angstrom-scale size of channels in crystals might be too small to accept and accelerate significant number of particles. Carbon-based nano-structures such as carbon-nanotubes (CNTs) and graphenes have a large degree of dimensional flexibility and thermo-mechanical strength and thus could be more suitable for channeling acceleration of high intensity beams. Nano-channels of the synthetic crystals can accept a few orders of magnitude larger phase-space volume of channeled particles with much higher thermal tolerance than natural crystals.

This paper presents conceptual foundations of the CNT acceleration, including underlying theory, practical outline and technical challenges of the proof-of-principle experiment. Also, an analytic description of the plasmon-assisted laser acceleration is detailed with practical acceleration parameters, in particular with specifications of a typical tabletop femtosecond laser system. The maximally achievable acceleration gradients and energy gains within dephasing lengths and CNT lengths are discussed with respect to laser-incident angles and the CNT-filling ratios.

A focused ion beam (FIB) was successfully applied to prepare cross-sectional samples for transmission electron microscopy (TEM), scanning TEM (STEM), scanning electron microscopy (SEM), and scanning ion microscopy (SIM). The FIB milling has been prospectively applied also to nanofabrication. The FIB allows to mill with high accuracy in positioning, being in contrast with a broad ion beam with poor accuracy. Controlling beam conditions of ion pixel-dose (or pixel dwell time) and FIB scanning direction/velocity, and sample tilt/rotation, we can extend the FIB milling from cross-sectioning to three-dimensional (3D) fabrication. We review inherent characteristics of the FIB milling such as positioning accuracy, milling speed, uniformity of cross-section, beam damage, and secondary electron emission. Discussions are mainly held from a viewpoint of interaction of ion beam with solids.

Several detector types have been designed and assembled in order to monitor charged particle beams in a wide range of intensities: silicon microstrip detectors for high precision tracking (spatial resolution better than 5 μm), a scintillating fiber tracker with multianode photomultiplier readout for coarse but fast monitoring, a microstrip silicon detector readout by a counting ASIC to monitor very high intensity beams.

These detectors and their readout electronics have been characterized at the BTF (Beam Test Facility) of the INFN National Laboratories of Frascati and used on the H8 line at the CERN SPS as tracking media for the data taking of the H8RD22 collaboration.

The paper describes the results obtained in terms of spatial resolution and maximum counting rates.

Cuspate topography provides a variation in the beachface slope, which can be used as a natural laboratory to study the influence of slope and downwash convergence on each swash cycle. The steeper-sloped cusp horns are likely to be characterized by smaller, faster swash cycles than the bays. The longer swash cycles in bays are more likely to collide with subsequent uprushes, and be influenced by increased downwash mass-flux caused by channeling. Here we use non-linear forecasting techniques for detecting non-linearities to determine the main controls on longshore swash variability. The outcome is a measure of the degree of localness in the timeseries, where local timeseries are governed by non-linear processes leading to non-stationarity whereas global timeseries are generally linear (or noise-dominated). The results of the forecasting analysis indicate that the swash from the day with generally greater beach slope, lower wave and longer period conditions was more local then the swash from the day with smaller average beach slope, higher wave conditions and shorter wave periods. Moreover, the alongshore variation in topography associated with beach cusps was associated with a longshore variability in the forecasting results, with the timeseries from the bay being better forecast with a more local model then the timeseries from the horn. These results are consistent with interactions between swash events causing the variability in forecasting results. Tests indicate that it is not one simple characteristic of the timeseries that varies locally, but some combination of magnitude, period, shape and absolute location on the beachface. Results may explain why variations in infragravity energy are observed to occur on cuspate beaches.

2008 accomplished the 100^th anniversary from the birth of L.D. Landau (Nobel Prize 1962). In the paper a short description of Kharkov period of Landau's work from 1932 to 1937 is given. One of areas of his work is connected with investigation of bremsstrahlung by ultra relativistic electrons in matter. In this paper a short review of the results obtained studying both Landau-Pomeranchuk-Migdal effect and coherent radiation by high-energy electrons and positrons in crystals, is given. The main attention is paid to the general properties and difference of radiation processes in amorphous media and in a crystal and to advances in the coherent bremsstrahlung studies.

The particle flux redistribution in oriented crystals leads to arising of various orientation effects in the yields of processes connected to small impact parameters (nuclear reactions, knocking out δ-electrons etc). Orientation effects of that type in the incoherent bremsstrahlung were discussed earlier in several experimental and theoretical articles. In this paper we present some improved and new results obtained using numerical simulation.

The newly predicted effect of multiple volume reflection in one crystal as well as the effects of axial proton channeling and both the axial and planar channeling of negative particles in bent crystals are simulated. Some possibilities of experimental condition optimization are discussed.

We suggest. to use a buried oxide layer to increase the efficiency of particle capture into the regime of stable channeling motion. Available SIMOX structures can be used t.o considerably increase the probability of capture of protons and positrons with energies from 5 MeV to about 1 GeV. The number of non-channeled particles can be decreased down to 2% at energies of several hundred MeV. Rutherford back scattering as well as both transmitted energy or angular distributions can be used to observe the channeling efficiency increase.

The CUP experiment is a first important step of a more ambitious project that investigates the possibility to create new powerful sources of high-frequency monochromatic electromagnetic radiation: crystal undulator and γ-laser based on channeling of positrons in crystals. Moreover, within the CUP project we are going to design a new experimental facility based on positron source. In this work the main goal of the CUP experiment and the first measurements at the DAΦNE BTF facility will be presented.