Sensitivity of single crystals to the circular polarization of high-energy γ-quanta

Abstract

It is shown that single crystals are sensitive to the initial circular polarization of γ-quanta with energies in tens GeV and more. The possibility of measurement of γ-beam polarization is discussed. The obtained results may be useful for creation of polarimeters for high energy beams of γ-quanta.

Multiple volume reflection from different planes inside one bent crystal

“…Till now only the reflection from crystal planes normal to the bending plane was studied both theoretically and experimentally [1,2,3,4,5,6,7,8]. In particular, an explicit expression for the angle of VR from such "vertical" plane was obtained recently [10]. The stationary Cartesian coordinate system XY Z with Z axis parallel to a set of crystal axes at the crystal entrance and plane XZ parallel to the plane of crystal bending will be used to describe the particle motion outside the crystal -see Fig.…”

“…However to describe the particle motion inside the latter the comoving Cartesian coordinate system rY z (see Fig. 1) is more suitable [10]. Both the longitudinal axis z and the transverse plane rY of this coordinate system rotate synchronously with the particle radius vector r by its azimuthal angle ϕ ≃ vt/R, where R is the bending radius, t is the time equal zero at the crystal entrance and v is the particle velocity.…”

“…determines the turning point x-coordinate x t at a specified ε ⊥x value. With a view to obtain explicit expressions for the particle deflection angles both in XZ and Y Z planes we will follow [10] introducing the x-component…”

“…of the velocity of particle motion in the constant plane potential U(x t ) in the comoving coordinate system. Since the turning point is the point of symmetry of the particle trajectory, we will, as usual [1,10], consider only a first half of it. The auxiliary velocity x-component (6) allows to write the time of particle motion from the point…”

Effective dissipative dynamics for polarized photons

“…Although the most natural way of realizing this is through the use of a suitable crystal ( [3,4], see also [32,33]), many other unconventional mechanisms leading to birefringence effects have been discussed in the literature. They involve the action of external fields, [34] Chern-Simons, [35] or more in general Lorentz and CP T -violating modifications of Maxwell Lagrangian, [36] extensions of General Relativity, [37] quantum gravity phenomena.…”