Фізико-математична модель визначення напрямку у просторі на точкові джерела гамма-випромінювання з використанням кульового поглинача

Physico-mathematical model for determining the direction in space to point sources of gamma radiation using a spherical absorber was developed. CdTe detectors of appropriate sizes are placed in the regular pyramid tops under absorber. The physico-mathematical model allowed, taking into account the exponential attenuation of gamma radiation by the absorber, to find the distance from the location of any CdTe sensor to the surface of sphere in any direction in space. Calculated information and signal received from the detectors, correlate to each other. The ratios found depend on the angle to the source of gamma radiation and represent the ratio of transmittance coefficients for four sensors. A methodology for locating the developed device in space, which allowed to obtain dependence of the calculated ratios from the angle in space for θ = 90° and φ from 0 to 360° in increments of 15° was proposed. Each direction in space corresponds to a set of six respective ratios.Розроблено фізико-математичну модель визначення напрямку на точкові джерела гамма-випромінювання у просторі з використанням кульового поглинача. Детектори з CdTe необхідного розміру розміщують у вершинах правильної піраміди під поглиначем. Фізико-математична модель дозволила з зрахуванням експоненційного ослаблення гамма-випромінювання поглиначем знаходити відстань від розташування будь-якого CdTe датчика до поверхні кулі у будь-якому напрямі у просторі. Розраховану інформацію-сигнал, що отримано від детекторів, співвідносять один до одного. Знайдені співвідношення залежать від кута на джерело гамма-випромінювання та являють собою відношення коефіцієнтів пропускання для чотирьох датчиків. Запропоновано методику розташування розробленого засобу у просторі, що дозволила отримати залежність розрахованих співвідношень від кута в просторі для θ = 90° та φ від 0° до 360° з кроком 15°. Кожному напрямку у просторі відповідає набір з шістьох відповідних співвідношень

Schottky diodes based on the zinc selenide semiconductor crystals

The problems of raw materials obtaining for UV detectors such as crystalline elements based on zinc selenide(ZnSe) have been discussed. Electrical parameters of these elements have been determined. Method of Schottky diodes based on ZnSe manufacturing with various metal contacts (Ni, Pt, Pd, Al) has been presented. From the current-voltage characteristics of these diodes their main characteristics have been identified: range of work, dark currents and range of light sensitivity. The comparative characteristics of the diodes have been shown. It was defined that sensitivity of the diodes with platinum contacts under ultraviolet radiation exposure in 2–3 times higher than of the diodes that have contacts from nickel and palladium. The spectral characteristics confirm the efficiency of using the Schottky diodes on the base of A₂B₆ semiconductors, particularly ZnSe, for detection of ultraviolet radiation

Scintillation panels based on zinc selenide for detection of alpha radiation

The possibility of obtaining dispersed scintillation panels based on zinc selenide for alpha radiation registration has been demonstrated. Thanks to the good energy resolution Rα ~ 30 % of the panel it can be used for the registration of alpha radiation in radiometric and spectrometric modes. In this work the optimal particle size and the effective thickness of the composite layer of powder scintillator have been determined that provides high quantum yield of the panels. Experimental data of the dependence of light output from the panels on the size of the scintillator’s particles at the influence of X-ray and alpha radiation have been presented

Resolving power of scintillation panels based on zinc selenide

This work presents some characteristics of experimental samples of flexible scintillation panels made on the basis of fine-powders of zinc selenide scintillator. The purpose of the work was to determine the resolving power of dispersed scintillation panels based on ZnSe(Te) and to clarify the field of their application in X-ray technique. In the course of studying the dependences of the resolving power of scintillation panels based on ZnSe(Te) on the powder particles size and thickness of the panels were discovered. The data on the dependences of the light output on the panel thickness and particle size of the scintillator in the samples in the thickness range of 0.1-1 mm are presented. X-ray images of different test objects obtained using scintillation panels based on zinc selenide are shown. Three ranges of the particles dispersion were investigated: the first — 25-40 µm, the second — 40-120 µm, and the third — 120-200 µm. It was revealed that the resolving power was 5, 3 and 2.5 lp/mm for the each range of dispersion

Alpha-, beta-, gamma-radiometric measurements using semiconductor detectors

Referring to shortcomings of modern radiation detection and monitoring devices, an operable prototype of the device for determination of the gamma radiation exposure dose rate within the range from 10 μ R/h to 1000 R/h, with the energy γ -radiation sensitivity range from 50 keV to 3 MeV, has been offered. The prototype is able to register the α-radiation and β-radiation flux density. The device operates using two detection units and a two-channel counting unit. Registration of the exposure dose rate is provided by using CdTe detector, and registration of the α-radiation and β-radiation flux density is provided by using Si detector

Small-sized UV radiometer on the basis of schottky diodes

In this work, main characteristics are considered of photosensitive Schottky diode structures – n-type ZnSe(Te,X)/Ni, where Х = O or Al, which are promising as ultraviolet radiation detectors in the 200–480 nm range. The Schottky barrier-based sensors show good sensitivity in the short-wave regions of the ultraviolet range, are practically insensitive to solar radiation at wavelengths above ∼460 nm, have rather short response time (∼1 ns) and quantum efficiency of up to 70%. Typical values of the monochromatic current sensitivity Sλ in the 420–440 nm range is 0.1–0.15 А/W. Characteristics were studied of detectors using glass and interference light filters for singling out biologically active regions of A, B and C of ultraviolet spectrum. Testing results of our ultraviolet radiometer have shown that the developed experimental sample meets the requirements to the instruments of this class