正弦平方势与沟道辐射谱线的自然展宽

指出了非线性效应、多普勒效应、晶格热振动、电子多重散射和偶极效应等对沟道辐射谱线宽度的影响;强调了辐射反作用对谱线宽度的影响是不可避免的。比较了不同的粒子-晶体相互作用势,并从正弦平方势出发,在小振幅近似下讨论了沟道粒子的运动行为;用摄动法求解了系统的特征方程,计算了沟道辐射谱线的自然展宽和频率漂移。最后,以正电子的Si(110)面沟道辐射为例,计算了它的辐射频率。结果表明,对于能量为E=56MeV的正电子,沟道辐射能量E=ω=36.0keV。

Sine-squared Potential and Intrinsical Width for Channelling Radiations

The motion behaviours of the channelling particles have been controlled by an interaction potential of a particle with a crystal. Assuming to the interaction potential is the sine-squared potential, then the channelling effects and the channeling radiation are described analytically. In a harmoric approximation only one line is discovered in the channelling radiation spectra. The width of spectrum line is effected by Doppler effect, thermal vibration of lattice, electron multi-scattering and double-pole effect, besides the non-linearity of the system. Thus width of the spectra line has expanded almost. However, these factors may be decreased to minimum by effort, but the intrinsical extended width of the spectrum line by the radiation is not overcomed. Various interaction potentials were compared, sine-squared potential is introduced to describte the interaction of the particle with the crystal. In a harmoric approximation of the sine-squared potential one disscused the intrinsical width and the frequency shift of the spectrum line for channelling radiations. Of course, the intrinsical width and the frequency shift of the spectrum line are very small in a classical approximation, However, this effect is obvious in a quantum mechanic frame, the shift magnitude is almost the same to the line width, this is so-called Lamb shift discovered by Soviet Physicist Lamb. In addition, in this paper the motion equation is derived in a classical mechanic frame, the solution of the equation is found by using pertubation method. The channelling radiation energy is calculated by a classical electro-dynamics. As example, the radiation energy for 1st order harmonic is for a positron with energy 56.0 MeV. It shows that the intrinsical width and the frequency shift of the spectra line are very small in all truth.