Calculation of The Lifetimes of Thin Stripper Targets Under Bombardment of Intense Pulsed Ions

The problems of stripper target behavior in the nonstationary intense particle beams are considered. The historical sketch of studying of radiation damage failure of carbon targets under ion bombardment is presented. The simple model of evaporation of a target by an intensive pulsing beam is supposed. Stripper foils lifetimes in the nonstationary intense particle can be described by two failure mechanisms: radiation damage accumulation and evaporation of target. At the maximal temperatures less than 2500K the radiation damage are dominated; at temperatures above 2500K the mechanism of evaporation of a foil prevails. The proposed approach has been applied to the discription of behaviour of stripper foils in the BNL linac and SNS conditions.Comment: 12 pages, 5 figure

КРИЗИС ДВОРЯНСКОГО ЗЕМЛЕВЛАДЕНИЯ ВО ВТОРОЙ ПОЛОВИНЕ XIX – НАЧАЛЕ XX ВЕКА (ПО МАТЕРИАЛАМ СРЕДНЕГО ПОВОЛЖЬЯ)

The article analyzes the situation in the field of noble land tenure of the Middle Volga region. The study was carried out on the basis of a combination of methods of various sciences: historical, economic and statistical. Such methods as comparative historical, systemic, quantitative, problem-chronological were used in the process of research. The main causes of negative dynamics in this area were identified; Numerous figures confirm the conclusion that almost all the studied indicators had a pronounced negative trend. The activity of the State Noble Land Bank is shown; its role in the processes of mobilization of noble land ownership is considered. The analysis of the dynamics of the main operations carried out by the bank noted significant fluctuations in the number and volume of loans granted, which was caused, first and foremost, by reasons of a socio-political nature.El artículo analiza la situación en el campo de la tenencia de la tierra noble de la región del Volga Medio. El estudio se llevó a cabo sobre la base de una combinación de métodos de diversas ciencias: histórico, económico y estadístico. Métodos como el comparativo histórico, sistémico, cuantitativo, problema cronológico se utilizaron en el proceso de investigación. Se identificaron las principales causas de la dinámica negativa en esta área; Numerosas cifras confirman la conclusión de que casi todos los indicadores estudiados tuvieron una tendencia negativa pronunciada. Se muestra la actividad del Banco Estatal de Tierras Nobles; Se considera su papel en los procesos de movilización de la noble propiedad de la tierra. El análisis de la dinámica de las principales operaciones llevadas a cabo por el banco observó fluctuaciones significativas en el número y volumen de préstamos otorgados, que se debieron, en primer lugar, a razones de carácter sociopolítico.В статье проанализирована ситуация, сложившаяся в сфере дворянского землевладения Среднего Поволжья. Исследование осуществлено на основе сочетания методов различных наук: исторических, экономических и статистических. В процессе исследования применялись такие методы, как сравнительно-исторический, системный, количественный, проблемно-хронологический. Были продемонстрированы основные причины, негативной динамики в указанной сфере, приведены многочисленные цифровые данные подтверждающие вывод о том, что практически все исследуемые показатели имели ярко выраженную отрицательную тенденцию. Показана деятельность Государственного дворянского земельного банка, рассмотрена его роль в процессах мобилизации дворянского землевладения. Анализируя динамику основных операций, производимых банком, отмечаются значительные колебания в количестве и объемах предоставленных ссуд, что было вызвано, в первую очередь, причинами социально-политического характера

Effect of local Coulomb interaction on Majorana corner modes: weak and strong correlation limits

Here we present an analysis of the evolution of Majorana corner modes realizing in a higher-order topological superconductor (HOTSC) on a square lattice under the influence of local Coulomb repulsion. The HOTSC spectral properties were considered in two regimes: when the intensities of many-body interactions are either weak or strong. The weak regime was studied using the mean-field approximation with self-consistent solutions carried out both in the uniform case and taking into account of the boundary of the finite square-shaped system. It is shown that in the uniform case the topologically nontrivial phase on the phase diagram is widened by the Coulomb repulsion. The boundary effect, resulting in an inhomogeneous spatial distribution of the correlators, leads to the appearance of the crossover from the symmetric spin-independent solution to the spin-dependent one characterized by a spontaneously broken symmetry. In the former the corner states have energies that are determined by the overlap of the excitation wave functions localized at the different corners. In the latter the corner excitation energy is defined by the Coulomb repulsion intensity with a quadratic law. The crossover is a finite size effect, i.e. the larger the system the lesser the critical value of the Coulomb repulsion. In the strong repulsion regime we derive the effective HOTSC Hamiltonian in the atomic representation and found a rich variety of interactions induced by virtual processes between the lower and upper Hubbard subbands. It is shown that Majorana corner modes still can be realized in the limit of the infinite repulsion. Although the boundaries of the topologically nontrivial phase are strongly renormalized by Hubbard corrections.Comment: 13 pages, 6 figure

Photolysis of Acetonitrile in a Water-rich Ice as a Source of Complex Organic Molecules: CH3CN and H2O:CH3CN Ices

Context. Many C-, O-, and H-containing complex organic molecules (COMs) have been observed in the interstellar medium (ISM) and their formation has been investigated in laboratory experiments. An increasing number of recent detections of large N-bearing COMs motivates our experimental investigation of their chemical origin. Aims. We investigate the potential role of acetonitrile (CH3CN) as a parent molecule to N-bearing COMs, motivated by its omnipresence in the ISM and structural similarity to another well-known precursor species, CH3OH. The aim of the present work is to characterize the chemical complexity that can result from vacuum UV photolysis of a pure CH3CN ice and a more realistic mixture of H2O:CH3CN. Methods. The CH3CN ice and H2O:CH3CN ice mixtures were UV irradiated at 20 K. Laser desorption post ionization time-of-flight mass spectrometry was used to detect the newly formed COMs in situ. We examined the role of water in the chemistry of interstellar ices through an analysis of two different ratios of H2O:CH3CN (1:1 and 20:1). Results. We find that CH3CN is an excellent precursor to the formation of larger nitrogen-containing COMs, including CH3CH2CN, NCCN/CNCN, and NCCH2CH2CN. During the UV photolysis of H2O:CH3CN ice, the water derivatives play a key role in the formation of molecules with functional groups of: imines, amines, amides, large nitriles, carboxylic acids, and alcohols. We discuss possible formation pathways for molecules recently detected in the ISM. © ESO 2021.Acknowledgements. M.B. and H.L. acknowledge the European Union (EU) and Horizon 2020 funding awarded under the Marie Skłodowska-Curie action to the EUROPAH consortium (grant number 722346) as well as NOVA 5 funding. Additional funding has been realized through a NWO-VICI grant. This work has been supported by the Danish National Research Foundation through the Center of Excellence “InterCat” (Grant agreement no.: DNRF150). We thank N. F. W. Ligterink, A. G. G. M. Tielens, J. Terwischa van Scheltinga, J. Bouwman and T. Lamberts for helpful discussions

Low-temperature surface formation of NH3 and HNCO: hydrogenation of nitrogen atoms in CO-rich interstellar ice analogues

Laboratory astrophysics and astrochemistr

A non-energetic mechanism for glycine formation in the interstellar medium

The detection of the amino acid glycine and its amine precursor methylamine on the comet 67P/Churyumov-Gerasimenko by the Rosetta mission provides strong evidence for a cosmic origin of amino acids on Earth. How and when such molecules form along the process of star formation remains debated. Here we report the laboratory detection of glycine formed in the solid phase through atom and radical–radical addition surface reactions under dark interstellar cloud conditions. Our experiments, supported by astrochemical models, suggest that glycine forms without the need for ‘energetic’ irradiation (such as ultraviolet photons and cosmic rays) in interstellar water-rich ices, where it remains preserved, during a much earlier star-formation stage than previously assumed. We also confirm that solid methylamine is an important side-reaction product. A prestellar formation of glycine on ice grains provides the basis for a complex and ubiquitous prebiotic chemistry in space enriching the chemical content of planet-forming material

Realignment-free cryogenic macroscopic optical cavity coupled to an optical fiber

Quantum Matter and Optic

Infrared spectra of complex organic molecules in astronomically relevant ice mixtures: IV. Methylamine

Laboratory astrophysics and astrochemistr