ar X iv : h ep - p h / 01 09 09 9 v 1 1 2 Se p 20 01 Spin rotation and oscillation of high energy particles in storage ring

The phenomenon of light polarization plane rotation (e.g., the Faraday effect, the natural rotation of a light polarization plane) as well as light birefringence (e.g., in matter placed in an electric field due to the Kerr effect) are the well known optical coherent phenomena. For the first glance they distinguish pho-tons from other particles (nucleons, electrons, etc.) for which these effects for a long time have been considered nonexistent. In [1-8] a wide range of phenomena similar to the effects of light polarization plane rotation and birefringence was shown to exist for particles other than photons. In particular it has been shown that as particles (neutrons, protons, neutrinos, etc.) pass through matter with polarized nuclei, the particle spin undergoes a rotation in an effective pseudomagnetic field of the matter induced by both strong and weak interactions. This effect is kinematically analogous to the phenomenon of light polarization plane rotation due to the Faraday effect. Experimentally, the effect of neutron spin precession in polarized target has been studied for neuterons [4-6]. As it was ascertained in [5-8] the analogue of birefringence phenomenon exists for particles, too. As a matter of fact, the Faraday effect and the effect of birefringence are caused by the dependence of the coherent photon-medium interaction energy on the photon spin state. This property unites the quasioptical phenomena discovered in [1-8] for interaction of spin-particles in matter with nuclei with the phenomena existing in light optics. However, attention should be drawn to the fact that whereas the photon spin is equal to unity, the particle (atom, nucleus) spin may take on different values. For particles of spin S = 1/2 there exists only one effect-that of spin rotation, i.e. a kinematic analog of the effect of light polarization plane rotation. An effect similar to birefringence exists for spin S ≥ 1 particles. It is very interesting to mention that phenomena of rotation and oscillations of particle spin (birefringence effect) exist for particles with spin S ≥ 1 in a medium with unpolarized scatterer spins, too. The fact that these effects are described by spin-dependent part of scattering amplitude allows to use them for the measurement of this amplitude at different energies of colliding particles. 0.1 Spin rotation of high-energy particles in polarized targets. As a result of numerous studies (see, for example, [12]), a close connection between the coherent elastic scattering amplitude f (0) and the refraction index …