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The problem of high-energy charged particle motion in the field of atomic planes of oriented crystals, essential for particle beam manipulation, intensive gamma-radiation generation and prepared measurements of short-living elementary particle properties, such as magnetic and electric dipole momenta, is considered. A rigorously evaluated instant change of transverse channeling motion energy under the scattering by an atomic core is applied to deduce an expression for the average transverse energy growth rate, which takes into consideration both the quantum effects and sharp particle density variation inside an inter-plane channel. The latter makes it possible for the first time to describe numerically the key limitations of multiple applications of the channeling effects in high-energy physics, not involving the parameters, introduces earlier through the arbitrary qualitative considerations. Also, the expressions of both the large angle scattering cross section and average square of small scattering angles are obtained, making possible to formulate a consistent simulation method of both positively and negatively charged particles propagation both in and out of the channeling conditions, taking into consideration both quantum nature of incoherent and classical one of the coherent scattering of ultra-relativistic particles by crystal plane atoms.

Electromagnetic dipole moments of short-lived particles are sensitive to physics within and beyond the Standard Model of particle physics but have not been accessible experimentally to date. To perform such measurements it has been proposed to exploit the spin precession of channeled particles in bent crystals at the LHC. Progress that enables the first measurement of charm baryon dipole moments is reported. In particular, the design and characterization on beam of silicon and germanium bent crystal prototypes, the optimization of the experimental setup, and advanced analysis techniques are discussed. Sensitivity studies show that first measurements of $\Lambda_c^+$ and $\Xi_c^+$ baryon dipole moments can be performed in two years of data taking with an experimental setup positioned upstream of the LHCb detector., Comment: 15 pages, 12 figures, aligned with published version

Experimental results show that the strong crystalline field of a single-element crystal, e.g. Si or W, may lead to a huge decrease in the electromagnetic shower length, if the beam direction is aligned with the crystal axes. The same effect has been recently investigated in a high-Z crystal scintillator, i.e., a lead tungstate ( PbWO 4 ). The effect of shower length reduction can be exploited to develop an innovative type of electromagnetic calorimeter based on oriented scintillator crystals with the key feature of a reduced volume w.r.t. the state of the art. Here we present a Geant4 simulation study of e.m. shower length decreasing when a e ± ∕ γ beam is aligned with respect the PWO main crystal axes. The presented work opens the way for a variety of applications in high-energy physics and astrophysics. Such applications span from forward calorimeters/preshowers, to compact active beam dumps for light dark matter search, to pointing-strategy in satellite-borne gamma-ray telescope to decrease the required size to fully contain the e.m. shower generated by GeV to TeV particles for a point like source.

The development of high-energy electromagnetic showers in long oriented lead tungstate crystals, accelerated by the effects induced by the strong field of atomic strings, is simulated for the first time. For that the characteristics of pair production and gamma-radiation by electrons or positrons were first simulated by the direct application of Baier-Katkov formulae in a thin PWO crystal to derive the scaling coefficients of the corresponding Bethe-Heitler cross sections to be incorporated into GEANT4 for the simulation of the electromagnetic shower development in a long crystal. Simulation results demonstrate the significant influence of the crystal structure on the e± and gamma-quanta registration processes in the existing homogeneous electromagnetic calorimeters and gamma-telescopes as well as wide possibilities of improving their performance in future developments.

In this Erratum, an improved simulation of the channeling efficiency of protons and antiprotons as a function of the particle momentum is shown in for different configurations

We present the crystalrad simulation code, combining all the features of the crystal simulation code for simulations of charged particles trajectories in a bent crystal and the radcharm++ code for calculation of the radiation spectrum. The crystalrad code is based on Monte Carlo simulations of trajectories in the planar and axial electric field either in a straight, bent, or periodically bent crystal taking into account multiple and single Coulomb scattering on nuclei and electrons, nuclear scattering and ionization energy losses. The trajectories simulated are used for calculation of radiation spectra by the Baier-Katkov method. We compare our simulations with experimental data taken at MAMI (MAinzer MIkrotron) as well as give an example for a possible future study with sub-GeV electrons interacting with Si bent crystals.

Short-period crystalline undulators have the potential to enable intense and monochromatic sources of hard X and $\ensuremath{\gamma}$ radiation. Three crystalline undulators were manufactured and their structural properties were characterized at the ESRF x-ray light source. In particular, a crystalline undulator consists in a periodically bent crystal in which channeled electrons or positrons follow the bending of the crystalline planes, thus generating electromagnetic radiation in analogy with standard magnetic undulators. State-of-the-art magnetic undulators can be built with a period of no less than a few cm. On the other hand, a crystalline undulator could be built with a period down to the sub-mm range. Thus, a crystalline undulator would allow generating harder photons. Since the radiator consists of a small crystal, a crystalline undulator is a valid and low-cost alternative for intense hard radiation production at electron accelerator facilities. The three samples were realized at the INFN laboratory of Ferrara, Italy, through the grooving method, namely a method developed to induce a self-standing and adjustable deformation to a crystal. The samples showed a uniform and sinusoidal curvature, thus proving that the grooving method is suitable for building crystalline undulators.

We measured a considerable increase of the emitted radiation by 120 GeV/c electrons in an axially oriented lead tungstate scintillator crystal, if compared to the case in which the sample was not aligned with the beam direction. This enhancement resulted from the interaction of particles with the strong crystalline electromagnetic field. The data collected at the external lines of the CERN Super Proton Synchrotron were critically compared to Monte Carlo simulations based on the Baier-Katkov quasiclassical method, highlighting a reduction of the scintillator radiation length by a factor of 5 in the case of beam alignment with the [001] crystal axes. The observed effect opens the way to the realization of compact electromagnetic calorimeters or detectors based on oriented scintillator crystals in which the amount of material can be strongly reduced with respect to the state of the art. These devices could have relevant applications in fixed-target experiments, as well as in satellite-borne γ telescopes. We measured a considerable increase of the emitted radiation by 120 GeV/c electrons in an axially oriented lead tungstate scintillator crystal, if compared to the case in which the sample was not aligned with the beam direction. This enhancement resulted from the interaction of particles with the strong crystalline electromagnetic field. The data collected at the external lines of CERN SPS were critically compared to Monte Carlo simulations based on the Baier Katkov quasiclassical method, highlighting a reduction of the scintillator radiation length by a factor of five in case of beam alignment with the [001] crystal axes. The observed effect opens the way to the realization of compact electromagnetic calorimeters/detectors based on oriented scintillator crystals in which the amount of material can be strongly reduced with respect to the state of the art. These devices could have relevant applications in fixed-target experiments as well as in satellite-borne gamma-telescopes.

A CRYSTAL simulation code for particle tracking in crystals is introduced. Its essence consists in both adequate and fast sampling of proton trajectories in crystals which is crucial for both correct description of experiments and quantitative prediction of new effects. The H8 single-pass experiment at the CERN SPS as well as 7 TeV proton deflection by a bent crystal at the LHC are simulated. We predict the existence of dechanneling peaks corresponding to the planar channeling oscillations as well as describe the possibility of their observation at high energies, specifically at the LHC energy. An effect of excess over the amorphous level of ionization losses in the channeling mode was also found at 7 TeV.

Crystalline collimators can potentially considerably improve the cleaning performance of the presently used collimator systems using amorphous collimators. A crystal-based collimation scheme which relies on the channeling particle deflection in bent crystals has been proposed and extensively studied both theoretically and experimentally. However, since the efficiency of particle capture into the channeling regime does not exceed ninety percent, this collimation scheme partly suffers from the same leakage problems as the schemes using amorphous collimators. To improve further the cleaning efficiency of the crystal-based collimation system to meet the requirements of the FCC, we suggest here a double crystal-based collimation scheme, to which the second crystal is introduced to enhance the deflection of the particles escaping the capture to the channeling regime in its first crystal. The application of the effect of multiple volume reflection in one bent crystal and of the same in a sequence of crystals is simulated and compared for different crystal numbers and materials at the energy of 50 TeV. To enhance also the efficiency of use of the first crystal of the suggested double crystal-based scheme, we propose: the method of increase of the probability of particle capture into the channeling regime at the first crystal passage by means of fabrication of a crystal cut and the method of the amplification of nonchanneled particle deflection through the multiple volume reflection in one bent crystal, accompanying the particle channeling by a skew plane. We simulate both of these methods for the 50 TeV FCC energy.

Effective fields of atomic strings and planes, which govern fast particle motion in oriented crystals, hundreds and thousands times exceed that of superconducting magnets. These fields naturally find unique applications in high energy physics. Channeling effect of oscillatory particle motion in the field of crystal planes can be used for both high energy beam deflection and collimation. Strong crystal fields also can enhance both the gamma-radiation by electrons and electron-positron pair production by gamma-quanta. We consider possible crystal applications for the beam collimation of the Large Hadron Collider and Future Circular Collider and acceleration of electromagnetic shower development in lead tungstate crystals of the Compact Muon Solenoid of the Large Hadron Collider.

A method to calculate both the bent crystal angle of alignment and radius of curvature by using only one distribution of deflection angles has been developed. The method is based on measuring of the angular position of recently predicted and observed quasichanneling oscillations in the deflection angle distribution and consequent fitting of both the radius and angular alignment by analytic formulae. In this paper this method is applied on the example of simulated angular distributions over a wide range of values of both radius and alignment for electrons. It is carried out through the example of (111) nonequidistant planes though this technique is general and could be applied to any kind of planes. In addition, the method application constraints are also discussed. It is shown by simulations that this method, being in fact a sort of beam diagnostics, allows one in a certain case to increase the crystal alignment accuracy as well as to control precisely the radius of curvature inside an accelerator tube without vacuum breaking. In addition, it speeds up the procedure of crystal alignment in channeling experiments, reducing beamtime consuming.

The three-dimensional stressed state in the neighbourhood of the tip of a plane semi-infinite crack located at the interface between two different kinds of transversely isotropic materials is investigated. Its exact analytic solution is constructed by reducing the problem to a Wiener-Hopf matrix equation, the singularity index of the elastic field is found and the stress intensity factors are determined.

A new computational procedure is developed which uses the fast Fourier transform algorithm and allows one to describe the processes of photon emission and pair production at arbitrary angles of high-energy electron, positron and photon propagation relative to the crystal planes.

It is shown that bent crystals can be effectively used for separating multi-TeV protons scattered at microradian angles and, as a result, can be applied to measuring proton beam polarization at the SSC not employing long straight sections. The possibility of using a bent crystal for faster separation of polarized beam halves at high-energy proton, antiproton or ion accelerators.

Primordial black holes (PBHs) of microscopical size can completely absorb neutron stars (NSs) and white dwarfs (WDs) for less than the Hubble time. NS absorption is accompanied by inverse URCA process giving rise to emission of antineutrino. However considerable part of these antineutrino fails to escape NS being drawn into the growing black hole by accreting NS matter. The final stage of dense WD absorption is accompanied by 1051erg neutrino burst able to ignite nuclear burning giving rise to supernova-like WD explosion.

The γ-quantum multiplicity and the peak value of the energy loss spectrum of 150 GeV electrons in the field of an 0.185 mm Ge 〈110〉 crystal are interpreted simultaneously on the basis of a synchrotron-like mechanism of hard γ-quantum emission. It is shown that both the radiation cooling and the transverse electron energy fluctuations due to multiple scattering have an effect on the formation of the hard region of the electron energy loss spectrum.

It is shown that while detecting positronium 3 gamma -decay quanta in a magnetic field one may observe counting rate oscillations at a frequency of triplet positronium level splitting. The oscillations may be observed in detecting the decay quanta by both three or one (two) counters. Based on this phenomenon it is possible to realise a novel matter research method, similar to the well known muonium spin rotation method.

The numerical analysis of pair production (PP) by γ-quanta intersecting the crystal axis with a small angle is given on the basis of the formulae describing the PP in a slightly inhomogeneous electric field.

We have experimentally detected time oscillations of the γ-quantum angular distribution under positronium annihilation in a magnetic field. Based on this phenomenon it is possible to realize a new method for studying matter with the use of positrons.

IN manufactur ing alkyd linoleum using waste material from caprolactam production, containing a mixture of succinic, ghitaric and adipic acids, it became necessary to evaluate the reactivities of the acids involved towards glycerine. Many authors [1-10] have studied the reaction mechanism of dibasic acids with glycerine. The studies were mainly carried out with phthalic anhydride only; as far as saturated aliphatic dibasic acids are concerned, particularly succinic, ghitaric and adipic acids, only a few studies are known. Kienle [2-4] studied the reaction of succinic and adipic acids with glycerine at 190 °. The reaction of succinic acid with this alcohol was examined by Hauschild [10] at 200 and 250 °. His results give some idea about the behaviour of these acids under restricted temperature conditions. The content of unreacted dicarboxylic acids in reaction end products has not been elucidated, neither have the kinetics of formation of a three-dimensional polymer been investigated. There is no information in the li terature concerning the reaction of glutaric acid with glycerine. I t is also known that dibasic acids with even and odd numbers of carbon atoms, as a consequence of different steric structure, form polyesters with different properties [11]. We examined the reactions of succinic, ghitaric aud adipic acids and their mixtures with glycerine over a wide range of temperature. By using the chromatographic method of determining free dicarboxylic acids [121 we were able to examine polyesterification in greater detail. This paper reports the results of examining the reaction of glutaric acid with glycerine.

THE problem of the approximate solution of a convolution-type linear integral equation of the first kind with errors on the right side and in the kernel in multidimensional space, is considered by the regularization method.

We report on the measurements of the spectra of gamma radiation generated by 855 MeV electrons in bent silicon and germanium crystals at MAMI (MAinzer MIkrotron). The crystals were 15 $$\upmu \text {m}$$ μ m thick along the beam direction to ensure high deflection efficiency. Their (111) crystalline planes were bent by means of a piezo-actuated mechanical holder, which allowed to remotely change the crystal curvature. In such a way it was possible to investigate the radiation emitted under planar channeling and volume reflection as a function of the curvature of the crystalline planes. We showed that, using volume reflection, intense gamma radiation can be produced – with intensity comparable to that obtained in channeling but with higher angular acceptance. We studied the trade-off between radiation intensity and angular acceptance at different values of the crystal curvature. The measurements of radiation spectra have been carried out for the first time in bent germanium crystals. In particular, the intensity of radiation in the germanium crystal is higher than in the silicon one due to the higher atomic number, which is important for the development of the X-ray and gamma radiation sources based on higher-Z deformed crystals, such as crystalline undulators.

Vladimir Afanas'evich Obruchev, who was born on October 10, 1863 in the village of Klepenino in the upper Volga region, was an outstanding natural scientist, who made great contributions to the exploration of Asia. His father was in the military service and often transferred with his family from one province to another. For some time they lived in Lithuania where Obruchev completed his high school education in Vilnius in 1881 and then passed the entrance examinations of both the Mining and the Technological institutes in Petersburg. He chose the Mining Institute and completed his studies there in 1886. ... For his great achievements the Academy of Sciences of the USSR named Obruchev a corresponding member of the Academy in 1921, and an active member in 1929. From this time on he was working in the Academy of Sciences and for 3 years, beginning in 1929, he was director of the Geological Institute. During World War II he was Academician-secretary of the Department of Geological and Geographical Sciences and as such led the scientific research of all academic institutes in this field. Obruchev was among the first to advocate the organization of a special committee for the study of permafrost. He was president of this committee from 1930 to 1939. In this year he became director of the Permafrost Institute, which now bears his name, and held that position for the rest of his life. ... He was also deeply involved in the exploration of northern regions. While analysing the geology of the greater part of Asia north of the Arctic Circle he concluded that during Quaternary times two glacial periods had occurred there, and that a thick ice sheet had covered not only the arctic zone but had extended south to 60°N. He established that at the beginning of the Quaternary dry land occupied the present Kara Sea area and that glaciers extended from there to the south between the Urals and the Taymyr Peninsula, which were also covered by a continental ice sheet at that time. Obruchev thought that the present Greenland ice cap and other glaciers of the North American islands, the glaciers of Spitsbergen, Zemlya Frantsa Iosifa, Novaya Zemlya, and Severnaya Zemlya are the remnants of ice caps and glaciers of the Ice Ages. Further evidence for the glaciations is the existence of fossil ice, which Obruchev discussed in detail in several of his works. His research concerning the Ice Ages helped to establish the southern limits of glaciation and the present distribution of permafrost. The very large amount of geological and geographical information collected by Obruchev in northern Asia has very great value in permafrost research, especially in the preparation of long-term climatic predictions and in the determination of the degree of climatic amelioration in the Arctic. He did not isolate permafrost from other natural phenomena but studied it in relation to the geology of the region. ... Obruchev died on June 19, 1956 and was buried in the Novodevich' cemetery in Moscow.