کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1823769 | 1526450 | 2012 | 5 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Radiative spin-flip and polarization in a helical undulator Radiative spin-flip and polarization in a helical undulator](/preview/png/1823769.png)
A recent claim that spin-flip photon emission in a helical undulator can lead to significant depolarization of a high-energy polarized electron beam is shown to be erroneous. Such a claim would, if true, have serious consequences for the International Linear Collider. The critical error in the calculation is identified (omission of a key term in the interaction Hamiltonian). The resulting cancellations in the spin-flip matrix element are explained. A simple argument is also given why the equilibrium degree of radiative polarization is almost zero for ultrarelativistic electrons radiating via spin-flip transitions in a helical undulator. Fundamentally, it is because the direction of the quantization axis of the spin eigenstates is almost orthogonal to the normal to the plane of formation of the radiation.
Journal: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment - Volume 675, 21 May 2012, Pages 15–19