Pilot Study of a Crystal-based Extraction for 6 GeV Electrons at DESY

• Applicant: Dr. Sergii Fomin
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 531314364

Main objective of the present project is to perform a pilot study and investigate the realization of a crystal-based extraction which allows to continue operation of the well established DESY Test Beam Facility at the new DESY IV booster synchrotron. The phenomenon of planar channeling of high-energy protons in bent crystals has been successfully used for similar problems at many accelerators, including Fermilab, SPS and LHC CERN. However, this method will not be as effective for deflecting electrons, since the planar channeling regime for negatively charged particles turns out to be very unstable. We propose to study the possibility to solve the problem by using the stochastic mechanism of fast charged particles scattering by atomic chains of a bent crystal (the Grinenko-Shul’ga mechanism), which was proposed by one of the authors of the present project. Preliminary theoretical studies, carried out at NSC KIPT, indicate that it is equally effective for both positively and negatively charged particles. Recent experiments at the CERN SPS confirmed the existence and high efficiency of a stochastic mechanism for deflecting particle beams with different signs of charge. It is also planned to compare the efficiency of the above two mechanisms of electron beam deflection for the conditions of DESY. However, the passage of relativistic electrons through matter is accompanied by intense bremsstrahlung, which can significantly affect the characteristics of the electron beam. When relativistic electrons pass through a crystal, coherent and interference effects take place in bremsstrahlung, as well as radiation suppression effects such as the Landau-Pomeranchuk-Migdal and the Ternovsky-Shul’ga-Fomin effect. The study of these effects, as well as the assessment of their influence on the electron beam dynamics in crystals, is one of the important components of this project and is of both practical importance for finding the optimal parameters of the electron beam extraction system and of fundamental importance for the physics of the interaction of charged particles with matter. In addition to determining the most efficient mechanism and optimal parameters of the electron beam extraction system for the Test Beam Facility, the project involves development and test of a new experimental method to determining the dechanneling length which is an important parameter for describing the dynamics of an electron beam in a crystal. The new idea is based on the measurement of ionization losses of electrons in various modes of motion in the crystal. The combination of numerous theoretical developments of Ukrainian scientists from the KIPT on the problem of the interaction of charged particle beams with crystals, together with extensive experience in conducting experimental studies at accelerators from DESY specialists gives confidence in the successful implementation of the project and the achievement of the defined goals.

• DFG Programme: Research Grants
• International Connection: Ukraine
• International Co-Applicant: Dr. Igor Kyryllin