Оценка оптимальных параметров многоэлементных твердотельных детекторов для сцинтилляционного атомно-эмиссионного спектрального анализа

Abstract

Introduction. In recent years, there has been an increased use of atomic emission spectral ( AES ) scintillation analysis with multi-element solid-state detectors ( SSD ) recording sequences of spectra for the rapid determination of trace impurities in powdered geological samples. The objectives of this study were to evaluate the optimal exposure time that provides the maximum signal-to-noise ratio ( SNR ) of the recorded spectral scintillations and, hence, the lowest detection limits of elements, and to estimate the effect of the SSD performance on this ratio. Derivation of the formula of the SNR. The time variation of the spectral line intensity is represented by a Gaussian function with the following parameters: the scintillation time and the number of photoelectrons generated by the scintillation. The SNR as a function of the scintillation intensity and time, spectral background intensity, exposure time, readout noise, and SSD area and dark current was determined for the two cases where the scintillation peak occurs at the beginning and middle of the exposure period. Analysis of the effect of the exposure time and SSD parameters on the SNR. The analysis was performed using three SSDs: BLPP-369M1 and BLPP-4000 photodiode arrays produced by VMK-Optoelektronika and a TCD1304DG charge-coupled device array produced by Toshiba. The experimentally obtained parameters of a 1 ms duration gold spectral line scintillation, during powder samples excitation on the spill injection method realizing equipment “Potok”, have been used in analysis. Results. It has been found that for achieving the maximum SNR for a 1 ms duration scintillation, the optimal exposure time is 0.8 ms for BLPP-4000, 1.1 ms for BLPP-369M1, and 1.2 ms for TCD1304DG. The expected reduction of the detection limits in the AES scintillation method compared to the conventional AES techniques is a factor of 30 for TCD1304DG, a factor of 50 for BSSA-369M1, and a factor of 110 for BSSA-4000. To obtain the AES method lowest detection limits, the intrinsic noise of the SSD (readout noise and dark current noise) should be less than the spectral background shot noise, the exposure time should be optimal, and the height of the photocell should be equal to the spectral line height. Keywords: time-resolved spectroscopy, atomic emission spectral analysis, scintillation, multi-element solid-state detectors, optimal exposure time. (Russian) DOI: http://dx.doi.org/10.15826/analitika.2014.18.1.004 S. A. Babin 1, 2 and Labusov 1, 2, 3 1 Institute of Automation and Electrometry, SB RAS, Novosibirsk, Russian Federation 2 VMK-Optoelektronika, Novosibirsk, Russian Federation 3 Novosibirsk State Technical University, Novosibirsk, Russian Federation