Scintillation characteristics of thin-film calcium iodide crystal x-ray detectors

A container design for fabricating low-energy x-ray scintillation detectors is proposed. CaI₂ and CaI₂:Eu crystal detectors are fabricated and their characteristics are investigated. It is shown that on account of their layered structure, perfect cleavage, and high light output, calcium iodide scintillators can be used to fabricate thin-film detectors for long-wavelength x rays. Zh. Tekh. Fiz. 68, 87–90 (August 1998)     

X射线激发荧光光谱仪的建立及闪烁晶体发光表征

利用X射线作为激发光源,自行组装并实现计算机控制的X射线激发荧光光谱仪.介绍了X射线激发荧光光谱仪的建立及其结构特性.该仪器具有时间分辨率高、测量动态范围大、使用方便等优点,可应用于晶体、粉末和液体等各种样品的测量,该仪器同时还具有很强的扩展性.     

Study of response of scintillation detector based on BaF2 crystals and nanoceramics

Fast and slow components of responses of scintillation detectors based on BaF₂ crystals and nanoceramics with various activators are studied by the registration of annihilation gamma-quanta with an energy of 511 keV. A comparative analysis of the obtained results for the determination of promising scintillators for the development of detectors with high time and pulse height resolution is carried out.     

X-ray detectors based on CdZnTe crystals grown from the vapor phase

X-ray detectors on the basis of vapor-phase-grown Cd_0.92Zn_0.08Te crystals are fabricated. The main characteristics of the detectors are investigated. It is shown that vapor-phase-grown CdZnTe crystals can be successfully used for making X-ray detectors.     

Luminescence and scintillation characteristics of YAG:Ce single crystalline films and single crystals

The detailed comparative analysis of luminescent and scintillation properties of the single crystalline films (SCF) of YAG:Ce garnet grown from melt-solutions based on the traditional PbO-based and novel BaO-based fluxes, and of a YAG:Ce bulk single crystal grown from the melt by the Czochralski method, was performed in this work. Using the ²⁴¹Am (α-particle, 5.49 MeV) excitation we show that scintillation yield and energy resolution of the optimized YAG:Ce SCF is fully comparable with that of the YAG:Ce single crystal analogue.     

Array of scintillation detectors for the MONICA spectrometer

An array of scintillation detectors of the MONICA Spectrometer, whis is aimed at investigating fluxes of cosmic-ray ions (from H to Ni) in the extraterrestrial space within the energy range from 10 to 300 MeV per nucleon, is considered. The basic goal of the MONICA experiment is the measurement of the ionic and isotopic composition of cosmic rays of the galactic and solar origin, as well as the measurement of their energy spectrum. This problem was intensely studied by numerous investigators [1–10]; nevertheless, a lot of questions remain unsolved up to now, in this field of science. The array of scintillation detectors plays the important role in achieving the goals of the MONICA experiment. The composition of the array, tuning procedure, and characteristics of scintillation detectors are discussed in detail.     

Luminescence of mercuric iodide crystals

Low-temperature (4.2–130 K) photoluminescence spectra of HgI₂ crystals have been measured in the 540–700 nm region. An analysis of the characteristics (intensity vs temperature and excitation power relations, afterglow times, excitation spectra) of the 560, 620, and 635 nm emission bands suggests the following assignments: the 560 nm band is due to radiative annihilation of excitons bound to mercury vacancies, and the “red” emission originates from recombination of free (620 nm) and donor-localized (635 nm) electrons with a hole-filled acceptor level. The energies of the corresponding donor and acceptor levels have been estimated. New emission bands at 540, 545, and 575 nm have been discovered, and their origin discussed. Fiz. Tverd. Tela (St. Petersburg) 39, 67–73 (January 1997)     

Energy response of the TL detectors based on YAlO3:Mn crystals

This study demonstrates the energy response of thermoluminescent (TL) detectors based on YAlO₃:Mn crystals. Experimental results of the relative sensitivity of YAlO₃:Mn²⁺ detectors to various kinds of photon radiation (from ⁶⁰Со, ¹³¹Cs, ¹⁹²Ir, and ¹³⁷Cs isotopes; X-ray from 220 kVp; and photon radiation from a linear accelerator (LINAC) at 5, 10, and 15 MV) agree with the theoretical energy response from Monte Carlo simulation. In addition to YAlO₃ (YAP), energy response was calculated for other yttrium-containing oxides such as Y₂O₃, Y₃Al₅O₁₂ (YAG), and Y₄Al₂O₉ (YAM). A possibility of filtering (modification) of the energy response of high atomic number (Z) materials by the metallic filters was shown.     

Optical detectors on GaSe and InSe layered crystals

Fast uncooled GaSe and InSe detectors that can record ultrashort (10^?12–10^?9 s) laser pulses in the visual and near-IR ranges are developed. The quick response of the detectors is due to rapid recombination channels with a high capture cross section present in the crystals.     

基于外电场作用氟氯碳酰的光谱特性和解离特性

采用密度泛函方法(DFT)在B3LYP/6-31G(d)水平上优化计算了在不同外电场作用下氟氯碳酰分子的物理性质,包括键长、键角、分子体系总能量、偶极矩、能隙、红外光谱、拉曼光谱以及解离特性.研究表明在外电场(-0.02—0.07 a.u.)作用下,氟氯碳酰分子结构有明显的变化,随着外电场的增强,分子C-O键长、C-Cl键长逐渐增大,C-F键长逐渐减小,分子体系总能量、能隙先增大后减小,偶极矩先减小后增大;分子红外光谱的O p-deform、CCl stretch(str)、CF str振动发生了蓝移,CO str振动发生了红移,CO deform振动先红移后蓝移,分子拉曼光谱的O p-deform、CCl str、CF str、CO str振动移动情况与红外光谱相同,当外电场强度为0.03 a.u.时,分子C-Cl势垒消失,分子发生解离,当外电场强度为-0.005 a.u.时,分子两个键断裂,发生逐步解离.研究工作为进一步研究氟氯碳酰分子的解离特性及臭氧层的保护提供理论依据.     

Spectral-kinetic characteristics of transient absorption in calcium fluoride crystals

The method of absorption spectroscopy with nanosecond resolution is used to study transient absorption in nominally pure crystals of CaF₂ irradiated by a pulse of fast electrons. Optical absorption caused by self-trapped excitons appears in the form of a superposition of bands with half-widths of no more than 0.2 eV in both the electron and hole components. These groups of bands are assigned to absorption of F, H pairs in various configurations. We observe a regular change in the spectral-kinetic characteristics depending on the distance between the components of the pair. Fiz. Tverd. Tela (St. Petersburg) 39, 1197–1201 (July 1997)