【作者】 刘珺；

【导师】 黄庆；

【作者基本信息】 西南交通大学 ， 理论物理， 2004， 硕士

【摘要】 宇宙线强度随时间的变化，是宇宙线物理、太阳地球物理和天体物理等交叉学科中的重要问题之一。通过宇宙线变化可以研究宇宙线的起源、传播以及受太阳的调制等等。但由于受到观测阈能和观测设备技术水平的限制，TeV到10TeV能区宇宙线变化的研究尚处于空白。 羊八井宇宙线观测站Tibet ASγ阵列海拔高度处于超高能宇宙线空气簇射发展极大附近，使在该处探测的簇射粒子密度高，阵列的观测阈能低，特别适合于研究1-10TeV能量的宇宙线变化。 本论文将小波变换与传统统计折叠法相结合作为数据分析方法，利用仿真实验信号检验了其有效性和优越性，发现这种方法可以更有效地从高噪声信号中提取弱周期信号，并给出周期变化的相位分布。且首次将该方法应用于羊八井宇宙线观测站Tibet AS γ阵列1997年11月到1998年6月的实验记录数据的周期分析，对1-10TeV宇宙线流强的时间变化及其气象影响进行了研究。 研究发现TeV和10TeV宇宙线流强中存在着太阳日和半太阳日周期变化。TeV宇宙线流强1d和0.5d周期变化的信噪比分别为9.8和12.9，其变化幅度分别为0.4±0.26％和0.3±0.18％，最大变化处的相位分别在约0.8(18h)和0.9(11h)。10TeV宇宙线流强1d和0.5d周期变化的信噪比分别为10.1和12.9，其变化幅度分别约为0.5±0.34％和0.35±0.23％，最大变化处的相位分别在约0.8(18h)和0.9(11h)。 应用上述方法分析了气象参量，包括观测面处大气压和室外温度的日变化和半日变化，接下来的关联分析和拟合计算表明：宇宙线流强的周期变化与气压和温度的周期变化显著相关。利用二元回归分析对小波变换后的宇宙线流强数据进行气象效应修正，并进行了修正检验，证明修正是有效的。 对气象效应修正后的宇宙线流强数据进行周期分析，发现TeV和10TeV宇宙线数据中存在半日、0.996和1.002日周期变化。10TeV宇宙线1.002日、0.996日和半日周期变化的信噪比分别为6.4、5.6和8.1，其变化幅度分别约为0.15±0.095％、0.15±0.087％和0.08±0.04％，最大值处的相位分别在约0.3(7h)、0.7(17h)和0.1(1h)。TeV宇宙线1.002日、0.996 西南交通大学硕士研究生学位论文第n页日和半日周期变化的信噪比分别为6.1、5.1和7.1，其变化幅度分别约为0.125士0.078%、0.1士0.068%和0.05士0.031%，最大值处的相位分别在约0.3(7h)、0.7(17h)和0.9(11h).这些周期变化是如何引起的，还需要进一步深入研究。 宇宙线的恒星日变化紧密联系于宇宙线的起源、其传播途径的性质，以及宇宙线的加速机制等宇宙线物理中最基本的重大问题。通过对气象效应修正后的宇宙线流强数据进行周期分析，发现了10TeV宇宙线流强的恒星日(T== 0.997日)变化，其信噪比为5.0，变化幅度约为0.125士0.079%，最大值处的相位约在0.45(11h)。相位基本与其它观测结果相符，而变化幅度大1倍，我们的结果更接近于理论估计结果(0.17%)。TeV宇宙线恒星日变化的信噪比为4.5，变化幅度约为0.1士0.062%，最大值处的相位约为0 .45(1 lh)。 本论文采用信号处理中逐渐成熟且被大量采用的小波分析方法，并将其与传统统计周期分析方法相结合，第一次来处理著名的羊八井宇宙线观测站AS丫阵列的观测数据，具有重要的实际意义，可以为将来AS丫阵列和ARGO实验的数据处理及分析打下良好的基础。更多还原

【Abstract】 The time variation of the cosmic ray flux is one of crucial problems in the field of cosmic ray physics, solar geophysics and astrophysics, etc. The origin, propagation and modulation of cosmic ray can be studied through its variation. However, there is no information on the variation of 1-l0TeV cosmic ray because of the limit of the observation threshold energy and equipments.The development of EAS with ultrahigh energy reaches about its maximum at the altitude of the Yangbajing Cosmic Ray Observation Station Tibet ASy array where the density of shower particles is high, and the threshold energy is low. Therefore, it is propitious to study the variation of 1-lOTeV cosmic ray.In this thesis, wavelet transform combining with epoch folding methods is used as the data analysis method, and its validity and superiority is proved by the simulated experiments. It shows that this method is able to detect low-power level periodic signals in data with low signal-noise ratio more effectively, and give the distribution of phase. It is the first time that the method is used to search for the periodic signals of 1-l0TeV cosmic ray in the data obtained with Tibet II /HD AS Array for December of 1997 to June of 1998 and study its meteorological effect.Solar time semi-diurnal and diurnal variations have been detected with about signal-noise ratio 12.9 and 10 for the TeV and l0TeV cosmic ray flux respectively. The semi-diurnal variations are of an amplitude 0.3 ?.1 8%, a phase 0.9(llh) for TeV cosmic ray and 0.35?.23%, 0.9(llh) for lOTeV. The diurnal variations are of amplitude 0.4 ?.26%, 0.5 ?.34%, and phase 0.8(18h) for TeV and lOTeV cosmic ray respectively.Using the method above, solar time semi-diurnal and diurnal variations of meteorological parameters, including the atmospheric pressure and the temperature out of the room are analyzed. The following correlation analysis and data fit show that the obvious correlation exist between the periodic variations of trigger rate and record rate of the cosmic ray observation experiment and of the atmospheric pressure and the temperature out of theroom at the level of observation. The meteorological effect of cosmic ray is corrected by using binary regression analysis. And the correction is proved to be effective by correction inspection.The periodic analysis for the data of cosmic ray flux after meteorological effect inspection shows that solar time semi-diurnal, 0.996 and 1.002 diurnal variations exit in the data of TeV and lOTeV cosmic ray. These periodic variations have been detected with about signal-noise ratio 8.1, 5.6 and 6.4, with amplitude 0.08?.04%, 0.15 ?.087% and 0.150.095%, and phase O.l(lh), 0.7(17h) and 0.3(7h) for lOTeV cosmic ray flux respectively, and with signal-noise ratio 7.1, 5.1 and 6.1, with amplitude 0.05 + 0.031%, 0.1 0.068% and 0.125 + 0.078%, and phase 0.9(1 Ih), 0.7(17h) and 0.3(7h) for TeV cosmic ray flux respectively. The origin of these periodic variations needs more investigation.The sidereal diurnal variation of cosmic ray ties up with the most basic and important problem in cosmic ray physics such as the origin, propagation and the acceleration mechanisms of cosmic ray. The sidereal diurnal variation (T=0.997d) for lOTeV cosmic ray has been detected with about signal-noise ratio 5.0, with amplitude 0.125 + 0.079% and phase 0.45(llh) by analyzing the data of cosmic ray flux after meteorological effect corrected. The phase accords with other observation results basically, while the amplitude of variation is double. Our result of the amplitude is more close to the theory value (0.17%). The sidereal diurnal variation for TeV cosmic ray has been detected with about signal-noise ratio 4.5, with amplitude 0.10.062% and phase 0.45(1Ih).It has practical significance to process the data obtained with the famous Yangbajing Cosmic Ray Observation Station ASy array for the first time using the technique of wavelet analysis which is maturing and used largely in the signal processing combining with classical epoch folding methods, and will lay the更多还原