Description
Channeling radiation is emitted whenever a charged particle crosses a crystal along the direction of a major crystal axis or plane (axial and planar channeling respectively), with the incident angle less than the critical angle defined by Lindhard. The charged particle are trapped in the potential wells originated by the crystal lattice, resulting in a strong steering effect and in the emission of coherent radiation.
The total emitted energy is proportional to γ2, where γ is the Lorentz factor of the incident particle, while the average photon energy is proportional to γ3/2. Due to its features, the channeling effect can be applied to discriminate in high energy unseparated beams between light radiating particles and heavy non radiating ones. Since a detectable channeling photon yield can be obtained from a reduced thickness crystal, the advantage of this particle identification technique is that small amounts of materials have to be disposed along the beam lines. On the other hand, since the Lindhard angle is of the order of 100 μ-rad in the 1 - 10 GeV energy region, highly collimated beams are needed.
To study this application of the channeling radiation, we have performed a beam test campaign at the CERN PS-T9 and SPS-H4 facilities using a 500μm thick <110> silicon crystal. A NaI calorimeter has been used to detect the channeling γ-rays produced in the crystal. The electron (positron) – pion identification performance has been studied. The preliminary results will be shown and the perspectives will be discussed.
