Automated radon radiometers family of RRA

We present two automated radiometers of RRA family designed for radon concentration measurements. Measurements are based on the method of electrostatic precipitation of charged radon decay daughters onto the surface of the passivated semiconductive Si(Au) a-particle detector. Radon 222Rn and thoron 220Rn concentrations are determined from the quantity of registered a-particles at RaA (218Po) and TnA (216Po) decays. Radon concentration, temperature, relative humidity and pressure are measured simultaneously so that radon concentration can be followed with time and correlation dependences between the parameters can be obtained. Principal performance specifications and promising applications of the radiometers are presented

A technique for localizing and identifying concealed objects in terahertz images based on mutual information maximization

Предлагается новый алгоритм локализации и идентификации объектов на изображениях, полученных на пассивном терагерцовом комплексе обнаружения скрытно проносимых запрещённых предметов. Предлагаемый алгоритм основан на методе максимизации взаимной информации, применяемом в задачах совмещения изображений. Для сокращения вычислительных затрат предлагается анализировать критерий в точках локальных максимумов функции взаимной корреляции изображений, вычисляемой в частотной области. Предлагаемый алгоритм не требует настройки параметров. Вычислительный эксперимент показал эффективность алгоритма и возможность его применения в системах безопасности для обнаружения скрытых объектов. In this paper, a new technique for localizing and identifying concealed objects in images acquired by passive THz imaging system is proposed. The technique is based on known method for mutual information maximization successfully used for image matching. For reducing computational expenses, we propose to analyse mutual information at local maxima of cross-correlation function computed in Fourier domain. The proposed technique does not require parameter tuning. Computing experiment approved the efficiency of the proposed technique and possibility of its implementation in security systems.Авторы выражают благодарность компаниям ЗАО «Астрон» и ООО «АСофт» за предоставленное оборудование для регистрации терагерцового излучения THERZ-7A. Исследование выполнено при частичной поддержке РФФИ, проекты № 18-07-01295 и № 16-29-09626

Preparation of NZP-type Ca0.75+0.5xZr1.5Fe0.5(PO4)3-x(SiO4)x powders and ceramic, thermal expansion behavior

Ca0.75+0.5xZr1.5Fe0.5(PO4)3–x(SiO4)x (x = 0–0.5) solid solutions have been synthesized by a sol–gel process and characterized by X-ray diffraction, IR spectroscopy, and differential scanning calorimetry. As expected, the synthesized phosphatosilicates crystallize in a NaZr2(PO4)3-type structure (trigonal symmetry, sp. gr. R c). The thermal expansion of the solid solutions has been studied by high-temperature X-ray diffraction in the temperature range from 25 to 800°C. Their thermal expansion parameters have been calculated and analyzed as functions of composition. High-density ceramics based on the Ca0.875Zr1.5Fe0.5(PO4)2.75(SiO4)0.25 phosphatosilicate have been produced by spark plasma sintering and their structure and properties have been studied in detail

Optical complex for the study of pulsating aurora with sub-millisecond time resolution on the basis of the Verkhnetulomsky observatory

International audienceA new telescope-spectrometer was installed at Verkhnetulomsky observatory (68?36'N, 31?47'E) to supplement the data from all-sky cameras with measurements of the fine space-time structure of the auroral luminescence. The telescope uses 5 cm ultraviolet (UV) transparent lens as an optical system and a matrix of multi-anode photomultiplier tubes as a photo detector. The angular resolution of the telescope is 1.2? and the temporal resolution is 0.3 ms. The telescope observes a central part (20?) of the all-sky camera field of view (FOV). Description of both optical instruments and results of the first joint measurements are presented

Effect of chemical modification on the structure and dielectric and magnetic properties of multiferroic (1 – x)BiFeO 3-xDyFeO 3 solid solution

61.05.Cp X-ray diffraction, 75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects, 77.22.Ch Permittivity, 77.80.Bh Phase transitions and Curie point,