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141.
基于LED光源痕量二氧化氮气体的检测 总被引:3,自引:0,他引:3
随着现代化工业的发展,大气污染越来越严重,吸收光谱法是检测大气污染的重要手段.NO2是大气污染的主要污染物之一,文章将发光二极管作为光源,选择发光光谱范围处于NO2强吸收峰位置的发光二极管,通过测虽含有NO2污染物的吸收光谱,利用最小二乘法,将实验得到的吸收光谱与标准谱作拟合运算,反演计算出污染物浓度.分析了检测的幕本原理,研究了光谱分析过程,包括实验光谱与标准光谱的拟合、浓度的反演计算等数据处理过程.具体利用NO2在300~500 nm光谱范围内有强吸收的特点,测量了样品中NO2的浓度.实验使用发光二极管作为光源,使检测变得方便快捷,实验装置便于携带,可以随时对待测场所实现高精度的实时在线检测. 相似文献
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143.
Virkus T Thomsen HD Uggerhøj E Uggerhøj UI Ballestrero S Sona P Mangiarotti A Ketel TJ Dizdar A Kartal S Pagliarone C;CERN NA Collaboration 《Physical review letters》2008,100(16):164802
Experimental results for the restricted energy loss of pairs created from 1-178 GeV photons in a thin Au target and subsequently passing a CCD detector are presented. It is shown that pairs--when detected close to the creation vertex--suffer a reduced energy loss due to the internal screening of the charges constituting the pair. Furthermore, the ability to measure directly the energy of the pair by calorimetry enables a comparison with theory as a function of energy. The observed phenomenon is in good qualitative agreement with general expectations from the Chudakov effect but indicates a quantitative disagreement with either of two mutually disagreeing theories. 相似文献
144.
J. Badier C. Bemporad J. Boucrot O. Callot P. Charpentier A. M. Cnops M. Crozon P. Delpierre J. F. Detoeuf G. R. Giannini R. Hammarstr?m P. Lariccia R. Lorenzi J. Mas A. Michelini A. Tilquin J. K. Walker NA Collaboration 《Zeitschrift fur Physik C Particles and Fields》1986,31(1):21-32
A sensitive search has been done for the production of new long-lived and penetrating particles by 300 GeV/c negative pions. No new state —decaying into at least two charged known particles —has been detected with mass above 1 GeV/c2 and lifetime in the range 5·10?11 s to 5·10?7s. We give upper limits on production cross sections, and consequences on the existence of heavy “axion-like” particles, heavy neutrinos and supersymmetric particles. In particular, this experiment excludes the existence of light gluinos with lifetime in the range 5·10?11 to 10?8s: this closes the last “window of opportunity” for gluinos withM<2 GeV/c2 and lifetime measurable in particle physics experiments. 相似文献
145.
Adamová D Agakichiev G Appelshäuser H Belaga V Braun-Munzinger P Cherlin A Damjanović S Dietel T Dietrich L Drees A Esumi SI Filimonov K Fomenko K Fraenkel Z Garabatos C Glässel P Hering G Holeczek J Kushpil V Lenkeit B Maas A Marín A Milosević J Milov A Miśkowiec D Panebrattsev Y Petchenova O Petrácek V Pfeiffer A Rak J Ravinovich I Rehak P Richter M Sako H Schmitz W Sedykh S Seipp W Sharma A Shimansky S Slívová J Specht HJ Stachel J Sumbera M Tilsner H Tserruya I Wessels JP Wienold T 《Physical review letters》2003,91(4):042301
We report on first measurements of low-mass electron-positron pairs in Pb-Au collisions at the CERN SPS beam energy of 40 AGeV. The observed pair yield integrated over the range of invariant masses 0.2e(+)e(-) annihilation with a modified rho propagator. They may be linked to chiral symmetry restoration and support the notion that the in-medium modifications of the rho are more driven by baryon density than by temperature. 相似文献
146.
J. Badier M. Bardadin-Otwinowska C. Bemporad U. Berthon H. Bienvenu J. Boucrot J. Bourotte O. Callot P. Charpentier A. M. Cnops M. Cohen F. Costantini M. Crozon D. Décamp P. Delpierre J. F. Detoeuf P. Espigat G. R. Giannini Y. Karyotakis P. Lariccia J. Mas A. Michelini G. C. Moneti M. Moniez E. Paré G. Rahal-Callot M. Rumpf A. Tilquin NA Collaboration 《Zeitschrift fur Physik C Particles and Fields》1986,30(1):45-50
We have measured the inclusive cross-section for π0 production at large transverse momentum by 200 GeV/c positive and negative hadron beams on Carbon targets (2.9<P T <6 GeV/c; ?0.4<y *<1.2). We used the NA3 spectrometer at the CERNSPS. 相似文献
147.
The NA50 experiment at CERN SPS studies charmonia and Drell-Yan production in the μ+ μ? decay channel at 158A GeV. The data collected in Pb?Pb collisions during 1995, 1996 and 1998 run periods show that the J/ψ is anomalously suppressed in central collisions. This observed suppression pattern can be considered as a strong indication of the production of Quark-Gluon Plasma. 相似文献
148.
149.
WANG De-Wu SHEN Gui-Lin NA Shu-Zhen LI Yun-Shan LI Cheng-Ze LI Zhi-Gang CHEN Kun CHEN Yuan-Bo CHEN Zhi-Ping MA Mei SHEN Miao-He ZHAO Mei LOU Jia-Shu XU Rong-Fen 《中国物理C(英文版)》1988,12(3):289-297
A positron CT camera system using multiwire proportional chambers as detectors is reported.This system is composed of two high density MWPC γ-ray detectors,an electronic readout system and a computer for data processing.The tomography of three dimensions is obtained.The imaging matrix 64×64×16. 相似文献
150.
The algebras of meromorphic vector fields and the bases of meromorphic λ-differentials with multipoles are constructed explicitly on general genus Riemann surfaces. For Riemann sphere the central extension of the algebra is also given. 相似文献