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

JUNO Conceptual Design Report

The Jiangmen Underground Neutrino Observatory (JUNO) is proposed to determine the neutrino mass hierarchy using an underground liquid scintillator detector. It is located 53 km away from both Yangjiang and Taishan Nuclear Power Plants in Guangdong, China. The experimental hall, spanning more than 50 meters, is under a granite mountain of over 700 m overburden. Within six years of running, the detection of reactor antineutrinos can resolve the neutrino mass hierarchy at a confidence level of 3-4$\sigma$, and determine neutrino oscillation parameters $\sin^2\theta_{12}$, $\Delta m^2_{21}$, and $|\Delta m^2_{ee}|$ to an accuracy of better than 1%. The JUNO detector can be also used to study terrestrial and extra-terrestrial neutrinos and new physics beyond the Standard Model. The central detector contains 20,000 tons liquid scintillator with an acrylic sphere of 35 m in diameter. $\sim$17,000 508-mm diameter PMTs with high quantum efficiency provide $\sim$75% optical coverage. The current choice of the liquid scintillator is: linear alkyl benzene (LAB) as the solvent, plus PPO as the scintillation fluor and a wavelength-shifter (Bis-MSB). The number of detected photoelectrons per MeV is larger than 1,100 and the energy resolution is expected to be 3% at 1 MeV. The calibration system is designed to deploy multiple sources to cover the entire energy range of reactor antineutrinos, and to achieve a full-volume position coverage inside the detector. The veto system is used for muon detection, muon induced background study and reduction. It consists of a Water Cherenkov detector and a Top Tracker system. The readout system, the detector control system and the offline system insure efficient and stable data acquisition and processing.Comment: 328 pages, 211 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

Grain Surface Models and Data for Astrochemistry

AbstractThe cross-disciplinary field of astrochemistry exists to understand the formation, destruction, and survival of molecules in astrophysical environments. Molecules in space are synthesized via a large variety of gas-phase reactions, and reactions on dust-grain surfaces, where the surface acts as a catalyst. A broad consensus has been reached in the astrochemistry community on how to suitably treat gas-phase processes in models, and also on how to present the necessary reaction data in databases; however, no such consensus has yet been reached for grain-surface processes. A team of ∼25 experts covering observational, laboratory and theoretical (astro)chemistry met in summer of 2014 at the Lorentz Center in Leiden with the aim to provide solutions for this problem and to review the current state-of-the-art of grain surface models, both in terms of technical implementation into models as well as the most up-to-date information available from experiments and chemical computations. This review builds on the results of this workshop and gives an outlook for future directions

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

Study of Silicon Photomultiplier External Cross-Talk

Optical cross-talk is a critical characteristic of Silicon Photomultipliers (SiPMs) and represents a significant source of the excess noise factor, exerting a substantial influence on detector performance. During the avalanche process of SiPMs, photons generated can give rise to both internal cross-talk within the same SiPM and external cross-talk when photons escape from one SiPM and trigger avalanches in others. In scenarios where SiPMs are arranged in a compact configuration and positioned facing each other, the external cross-talk could even dominate the cross-talk phenomenon. This paper investigates two distinct methods for measuring external cross-talk: the counting method, which involves operating SiPMs face-to-face and measuring their coincident signals, and the reflection method, which employs a highly reflective film attached to the surface of the SiPMs. External cross-talk measurements have been conducted on several types of SiPMs, including Vacuum Ultra-Violet (VUV) sensitive SiPMs that Fondazione Bruno Kessler (FBK) and Hamamatsu Photonics Inc (HPK) produced for nEXO as well as visible-sensitive SiPMs provided by FBK, HPK and SensL Technologies Ltd (SenSL) for JUNO-TAO. The results reveal a significant presence of external cross-talk in all tested SiPMs, with HPK's SiPMs exhibiting a dominant external cross-talk component due to the implementation of optical trenches that effectively suppress internal cross-talk. Furthermore, we found that the number of fired pixels resulting from internal cross-talk can be described by combining Geometric and Borel models for all tested SiPMs, while the external cross-talk can be predicted using a pure Borel model. These distinct probability distributions lead to different excess noise factors, thereby impacting the detector performance in varying ways

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

Laboratory astrophysics and astrochemistr