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    20 November 2016 Volume 35 Issue 11
      
    Theoretical description of neutrino oscillations and CP violation
    XU Xinping,WANG Yue,TANG Shenli,LI Jing wen
    College Physics. 2016, 35(11):  2-4.  doi:10.16854/j.cnki.1000-0712.2016.0154
    Abstract ( 1483 )   PDF (543KB) ( 713 )  
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    The Nobel Prize in physics 2015 was awarded jointly to Takaaki Kajita and Arthur B. McDonald "for the discovery of neutrino oscillations,which shows that neutrinos have mass". One month later,seven physicists including Takaaki Kajita and Arthur B. McDonald,who make significant contribution in the research of neutrino oscillations, obtain the 2016 Breakthrough Prize in fundamental physics. Neutrino oscillation has become the focus of fundamental physics research. In this paper,using the principle of quantum mechanics,we simply describe the theory of neutrino oscillations and CP violation,and introduce several important scientific problems in the future neutrino research.
    The main channel in the course teaching of optics———Path difference
    LI Duo,LIU Da he
    College Physics. 2016, 35(11):  5-8.  doi:10.16854/j.cnki.1000-0712.2016.0155
    Abstract ( 1690 )   PDF (607KB) ( 4272 )  
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    The important significance of the path and path difference in course teaching of optics is discussed.  Through analysis and discussion,it is pointed out that the path difference is the main channel for teaching optics.  To address this main channel from the beginning to the end in teaching optics is very important and necessary.
    The generalized parallel-axes theorem for the magnetic moment of a rotational charged body
    ZHOU Guo quan
    College Physics. 2016, 35(11):  9-12.  doi:10.16854/j.cnki.1000-0712.2016.0157
    Abstract ( 1434 )   PDF (520KB) ( 524 )  
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    The most general expression of the axis-translation theorem (parallel-axis theorem)for the 2-order scalar charge moment of a charge system around any two parallel axes is deduced. The generalized axis-translation theorem of the magnetic moment of a rotational charged body around any two parallel axes is derived through the simple proportionate relation between the fixed-axis magnetic moment and the 2-order scalar charge moment for the same charge system. The specific conclusions of axis translation theorem are demonstrated and discussed under three cases:1)the total charge (0-order charge moment)is zero;2)the electric dipole moment (1-order charge moment)is zero;3)both the total charge and electric dipole moment are zero. The ambiguities are clarified and the mistakes in some references are corrected.
    Numerical study of electronic states in finite multiple potential wells
    JIANG Junqin,SHEN Huajia
    College Physics. 2016, 35(11):  13-17.  doi:10.16854/j.cnki.1000-0712.2016.0158
    Abstract ( 1387 )   PDF (619KB) ( 629 )  
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    The electronic states in the symmetric N - potential wells are studied. Based on the Schrdinger equation,the linear equations determined by the standard conditions in the case of N = 1,2,3 and 4 are solved,the energy level and wave function are accurately calculated by using Mathematica. The mechanism of the energy level splitting into energy band is exhibited.
    Wave velocity of transverse wave in vertical suspended string
    KE Hongwei,GAO Lei,ZHOU Jiahui
    College Physics. 2016, 35(11):  18-19.  doi:10.16854/j.cnki.1000-0712.2016.0159
    Abstract ( 1992 )   PDF (658KB) ( 629 )  
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    The wave velocity of transverse wave in vertical suspended string is calculated analytically.The result  can be also obtained by using the formula of wave velocity in a spring with uniform tension,which means that the  formula can be applied for a spring with uneven tension.
    Conceptual discussion for approximate equations of a type and coherent superposition of states of single particle
    ZENG Tian hai
    College Physics. 2016, 35(11):  20-23.  doi:10.16854/j.cnki.1000-0712.2016.0160
    Abstract ( 1223 )   PDF (545KB) ( 1414 )  
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    The definition of entangled state is that it cannot be expressed in a product state,however,in some quantum systems,the entangled states which are used to describe them could be approximately equal to the product states. Conceptual discussion for the approximate equations of such type can be used to explain that this is a source of producing coherent superposition of states of single particle,and it is very possibly the only source.
    Measurement of spin relaxation time of protons using earth′s field NMR
    YANG Nan,TANG Miangang
    College Physics. 2016, 35(11):  24-28.  doi:10.16854/j.cnki.1000-0712.2016.0161
    Abstract ( 1310 )   PDF (722KB) ( 643 )  
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    Earth′s field nuclear magnetic resonance (EF NMR)approach is used to study the spin relaxation process of protons in water. Two different spin relaxation times,T1 and T2,are measured to be (2.46±0.16)s and (0.83±0.02)s,which are in well agreement with the results T1 = 2.3±0.1 s from the reference [1]. Besides,the experimental results also confirm the Curie Law. The measurements on copper sulphate solution imply that the existence of ions in solution will accelerate the spin relaxation process. This work provides a way to study spin relaxation process in seconds scale by EF NMR.
    Highly efficient concentration system of solar pumped laser
    FANG Dan,GU Kaihui,XING Shuzhi,QI Xiaoyu,LIANG Ming,LI Han,LIU Lu
    College Physics. 2016, 35(11):  29-32.  doi:10.16854/j.cnki.1000-0712.2016.0162
    Abstract ( 1519 )   PDF (712KB) ( 514 )  
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    A direct conversion of concentrated solar radiation into a coherent laser beam can be used to improve the conversion efficiency because of the design simplicity on structure. To surpass the lasing threshold,the solar radiation needs to be highly concentrated. The high efficient concentration system is composed by the Fresnel lens and the cone-channel condenser. The solar concentrated by the concentrator system is coupled into the chamber pumping Nd ∶ YAG laser media. The concentrator ratio is 104,improving the output of laser.
    Exploring curved space-time ———In memory of Professor LIU Liao
    ZHAO Zheng
    College Physics. 2016, 35(11):  33-39.  doi:10.16854/j.cnki.1000-0712.2016.0163
    Abstract ( 1762 )   PDF (1069KB) ( 1618 )  
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    Professor LIU Liao′s major milestones in his personal and academic life are introduced.Professor LIU had devoted himself to the research on the theory of general relativity and had contributed enormously to introducing this great theory into China and to its thriving in China. He had trained a lot of students in the field of general relativity and had published many books and papers on general relativity and its subfields,among them are curved spacetime, black hole,cosmology,wormhole,time-machine,gravitational wave,and so on.
    An ultrasonic location system for indoor moving target using multi-source and separated T/ R structure
    ZHANG Qinyan,HAN Yi,WANG Sihai
    College Physics. 2016, 35(11):  40-44.  doi:10.16854/j.cnki.1000-0712.2016.0165
    Abstract ( 1367 )   PDF (744KB) ( 490 )  
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    A high performance ultrasonic location system is proposed. Both infrared and radio signals are applied as synchronizing signals,forming a locating structure with separated transmitter and receiver. Pseudo random M sequence is utilized as spread spectrum carrier to form a CDMA-based multi-station mechanism. Wide-angle probes are designed for expanding the detecting area. In addition, a temperature compensation circuit is designed to improve the   measurement accuracy. This system can achieve 10 Hz sample rate and centimeter level measurement accuracy,and is verified to be effective for locating moving indoor targets.
    Numerical simulation of spherical polyelectrolyte brushes by self-consistent filed theory
    SU Zhi cheng,HU Wei
    College Physics. 2016, 35(11):  45-51.  doi:10.16854/j.cnki.1000-0712.2016.0166
    Abstract ( 1130 )   PDF (759KB) ( 405 )  
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    A spherical polyelectrolyte brush is studied by self-consistent field theory (SCFT)and the results are compared with predictions from scaling theory.It is shown that the SCFT results give the general trends as well as insight into the crossover regions between different regimes. The density profiles of the polyions and small ions indicate that the systems are locally electroneutral.The salted brush bears characteristics similar to those of a neutral brush.Counter-intuitively,the chains are not uniformly stretched in the osmotic regime.The free-end monomers shift to the outer region and an exclusion zone appears and grows with decreasing of salt concentration.
    The abnormal phenomenon of measuring refractive index with Michelson interferometer
    NAN Yang,XIONG Chang,TANG Fang,LI Chaorong
    College Physics. 2016, 35(11):  52-56.  doi:10.16854/j.cnki.1000-0712.2016.0167
    Abstract ( 1374 )   PDF (648KB) ( 846 )  
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    While Michelson interferometer and laser are used to measure the refractive index of glass pane,there is an abnormal phenomenon. When we put a glass pane into one side of the light path,we observe an abnormal phenomenon of equal inclination inference rings puff. In this letter,we analyze the phenomenon in terms of geometrical optics and make clear the relationship between the turning point of interference fringe,zero light path difference and the relative location of virtual light sources. We also perform comparative analysis with experimental data.
    Max Born and experimental proofs on de Broglie wave
    HOU Yude
    College Physics. 2016, 35(11):  57-62.  doi:10.16854/j.cnki.1000-0712.2016.0168
    Abstract ( 1764 )   PDF (556KB) ( 894 )  
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    The research works of the theoretical physicists and experimental physicists are not synchronous and not seamless. In 1920s,before the hypothesis of de Broglie wave,Davisson and Kunsman had done the diffraction experiment of electron. Franck was one of the people who first knew the meaning of the experiment. Elsasser,one of Franck’s students,grasped it himself,and he wanted to do further experiment research,but did not get any result. He seeked help from Franck,but also failed. Elsasser published a note paper,presented that we could got the pictures of electrons diffraction when electrons go through crystals. Two years later,Born in a report in Oxford mentioned the paper of Elsasser again. Born’s words attracted the attention of Davisson and G.Thomson. Quickly they got good result and won the Nobel Price in 1937. Franck did not value the idea of Elsasser and made him lost a good chance to be one of the Nobel Price winners.