Infrared scintillation yield in gaseous and liquid argon

The study of primary and secondary scintillations in noble gases and liquids is of paramount importance to rare-event experiments using noble gas media. In the present work, the scintillation yield in gaseous and liquid Ar has for the first time been measured in the near infrared (NIR) and visible region, both for primary and secondary (proportional) scintillations, using Geiger-mode avalanche photodiodes (G-APDs) and pulsed X-ray irradiation. The primary scintillation yield of the fast component was measured to be 17000 photon/MeV in gaseous Ar in the NIR, in the range of 690-1000 nm, and 510 photon/MeV in liquid Ar, in the range of 400-1000 nm. Proportional NIR scintillations (electroluminescence) in gaseous Ar have been also observed; their amplification parameter at 163 K was measured to be 13 photons per drifting electron per kV. Possible applications of NIR scintillations in high energy physics experiments are discussed.Comment: 6 pages, 5 figures. Submitted to Europhysics Letter. Revised Figs. 3 and

Study of infrared scintillations in gaseous and liquid argon - Part I: methodology and time measurements

A methodology to measure Near Infrared (NIR) scintillations in gaseous and liquid Ar, using Geiger-mode APDs (GAPDs) sensitive in the NIR and pulsed X-ray irradiation, is described. This study has been triggered by the development of Cryogenic Avalanche Detectors (CRADs) with optical readout in the NIR using combined THGEM/GAPD multiplier, which may come to be in demand in coherent neutrino-nucleus scattering and dark matter search experiments. A new approach to measure the NIR scintillation yield at cryogenic temperatures has been developed, namely using GAPDs in single photoelectron counting mode with time resolution. The time structure of NIR scintillations and their light yield were measured both for primary scintillations and that of secondary at moderate electric fields (electroluminescence), in gaseous and liquid Ar.Comment: 17 pages, 15 figures. Submitted to JINS

Phase diagram of YBa2_2Cu3_3O7−y_{7-y} at T<<Tc_c based on Cu(2) transverse nuclear relaxation

Two maxima in transverse relaxation rate of Cu(2) nuclei in YBa$_2$Cu$_3$O$_{7-y}$ are observed, at T = 35 K and T = 47 K. Comparison of the $^{63}$Cu(2) and $^{65}$Cu(2) rates at T = 47 K indicates the magnetic character of relaxation. The enhancement at T = 47 K of fluctuating local magnetic fields perpendicular to the CuO$_2$ planes is connected with the critical fluctuations of orbital currents. Maximum at T = 35 K is connected with the appearance of inhomogeneous supeconducting phase. Together with data published to date, our experimental results allow to suggest a qualitatively new phase diagram of the superconducting phase.Comment: 4 LaTEX pages + 3 figures in *.ps forma

Possible interpretation of the ZbZ_b(10610) and ZbZ_b(10650) in a chiral quark model

Motivated by the two charged bottomonium-like resonances $Z_b$(10610) and $Z_b$(10650) newly observed by the Belle collaboration, the possible molecular states composed of a pair of heavy mesons, $B\bar{B}, B\bar{B}^*, B^*\bar{B}^*, B_s\bar{B}$, etc (in S-wave), are investigated in the framework of chiral quark models by the Gaussian expansion method. The bound states $B\bar{B}^*$ and $B^*\bar{B}^*$ with quantum numbers $I(J^{PC})=1(1^{+-})$, which are good candidates for the $Z_b(10610)$ and $Z_b(10650)$ respectively, are obtained. Other three bound states $B\bar{B}^*$ with $I(J^{PC})=0(1^{++})$, $B^*\bar{B}^*$ with $I(J^{PC})=1(0^{++}), 0(2^{++})$ are predicted. These states may be observed in open-bottom or hidden-bottom decay channel of highly excited $\Upsilon$. When extending directly the quark model to the hidden color channel of the multi-quark system, more deeply bound states are found. Future experimental search of those states will cast doubt on the validity of applying the chiral constituent quark model to the hidden color channel directly.Comment: 13 pages, 1 figure, title and some arguments in the abstract and section 5 are revised, results unchange

Study of infrared scintillations in gaseous and liquid argon - Part II: light yield and possible applications

We present here a comprehensive study of the light yield of primary and secondary scintillations produced in gaseous and liquid Ar in the near infrared (NIR) and visible region, at cryogenic temperatures. The measurements were performed using Geiger-mode avalanche photodiodes (GAPDs) and pulsed X-ray irradiation. The primary scintillation yield of the fast emission component in gaseous Ar was found to be independent of temperature in the range of 87-160 K; it amounted to 17000+/-3000 photon/MeV in the NIR in the range of 690-1000 nm. In liquid Ar at 87 K, the primary scintillation yield of the fast component was considerably reduced, amounting to 510+/-90 photon/MeV, in the range of 400-1000 nm. Proportional NIR scintillations (electroluminescence) in gaseous Ar were also observed; their amplification parameter at 160 K was measured to be 13 photons per drifting electron per kV. No proportional scintillations were observed in liquid Ar up to the electric fields of 30 kV/cm. The applications of NIR scintillations in dark matter search and coherent neutrino-nucleus scattering experiments and in ion beam radiotherapy are considered.Comment: 20 pages, 11 figures. Submitted to JINS

Оценка динамических параметров составного резонатора волнового твердотельного гироскопа

В роботі проведено дослідження впливу неідеальності виготовлення окремих частин складеного резонатора та їх з’єднання на зміну власних частот коливань резонатора хвильового твердотільного гіроскопа (ХТГ). Отримані залежності, що визначають основні та допоміжні частини власних частот коливань для створення віброзахищеної конструкції резонатора ХТГ.In the paper to conduct the investigation of influence imperfection manufacturing of separate parts of the compound resonator and their joint on change of natural frequencies of oscillations of the resonator of wave solid-state gyro (WSG) is conducted. Relations which determine the main and accessories of natural frequencies of oscillations for making vibroprotective designs of resonator WSG are received.В работе проведено исследование влияния неидеальности изготовления отдельных частей составного резонатора и их соединения на изменение собственных частот колебаний резонатора волнового твердотельного гироскопа (ВТГ). Получены зависимости, копределяющие основные и вспомогательные части собственных частот колебаний для создания виброзащищенной конструкции резонатора ВТГ

Robust Free-Space Optical Communication Utilizing Polarization

Free-space optical (FSO) communication can be subject to various types of distortion and loss as the signal propagates through non-uniform media. In experiment and simulation, we demonstrate that the state of polarization and degree of polarization of light passed though underwater bubbles, causing turbulence, is preserved. Our experimental setup serves as an efficient, low cost alternative approach to long distance atmospheric or underwater testing. We compare our experimental results with those of simulations, in which we model underwater bubbles, and separately, atmospheric turbulence. Our findings suggest potential improvements in polarization based FSO communication schemes.Comment: 13 pages, 5 figure

Напряжённо-деформированное состояние железобетонного путепровода под нагрузкой

Beam spans are the most vulnerable elements of the bridge system, as they are exposed to direct effects of mobile load, environmental and climatic factors (temperature and humidity effects, including freezing and thawing, shrinkage, humidity, etc.). Appearance of defects of the structure is inevitable; the refore civil engineers face a topical problem of strengthening of damaged structures of bridges. The article discusses some results of calculated values and instrumental measurements of stress-strain state (SSS) of reinforced concrete beam span structures of railway overpass under operational load caused by different rolling stock units. The objective of this study is to control stress-strain state of railway overpass for identification and elimination of defects at early stages. The calculation results obtained, carried out by finite-element method (FEM) in the program ABAQUS/Standard correlate well with experimental data. These results can be used for monitoring the state of artificial structures on main lines of JSC NC KTZ.Балочные пролётные строения являются наиболее уязвимыми элементами мостовой системы, так как они подвергаются прямым воздействиям: подвижной нагрузки, природно-климатическим факторам (температурным и влажностным воздействиям, включая замораживание и оттаивание, усадку, влажность и др.). Появление дефектов конструкций моста в процессе эксплуатации неизбежно, поэтому перед инженерами-строителями вопрос усиления повреждённых конструкций мостов является актуальным и в настоящее время. В статье рассмотрены некоторые результаты расчётных значений и инструментальных измерений напряжённо-деформированного состояния (НДС) железобетонных балочных пролётных строений железнодорожного путепровода под эксплуатационными нагрузками, при проходе различных единиц подвижного состава. Целью данных исследований является контроль напряжённо-деформированного состояния железнодорожного путепровода для выявления и устранения дефектов на ранних стадиях. Полученные результаты расчёта, выполненные методом конечных элементов (МКЭ) в программе ABAQUS/Standard, хорошо коррелируют с экспериментальными данными. Эти результаты могут использоваться при мониторинге состояния искусственных сооружений на магистральных линиях АО «НК «ҚТЖ»

THGEM operation in Ne and Ne/CH4

The operation of Thick Gaseous Electron Multipliers (THGEM) in Ne and Ne/CH4 mixtures, features high multiplication factors at relatively low operation potentials, in both single- and double-THGEM configurations. We present some systematic data measured with UV-photons and soft x-rays, in various Ne mixtures. It includes gain dependence on hole diameter and gas purity, photoelectron extraction efficiency from CsI photocathodes into the gas, long-term gain stability and pulse rise-time. Position resolution of a 100x100 mm^2 X-rays imaging detector is presented. Possible applications are discussed.Comment: Submitted to JINST, 25 pages, 33 figure