Final Report Summary - CRYSBEAM (Crystal channeling to extract a high energy hadron beam from an accelerator)
Particle accelerators are complex machines able to increase the velocity of electrically charged elementary particles (like protons) up to a value very close to the speed of light. The Large Hadron Collider (LHC) at CERN is the most powerful machine in operation today, able to accelerate beams of protons up to an energy of 6.5 TeV (that is equivalent to a velocity 99.9999991% times the speed of light !).
Such accelerated particles are usually handled with very special and big magnets. Instead, by using small and thin bent crystals a novel way to manipulate these high energy beams has been studied by the CRYSBEAM team in the context of the UA9 experiment at CERN. Protons (or charged ions) are in fact trapped within the crystal lattice planes by the effective electric field of all the ordered atoms in the crystal. Since the macroscopic bending of the crystal also causes a bending of the lattice planes, the trapped particles are emerging deflected at a well-defined angle. The CRYSBEAM team built and tested a number of crystals at the CERN beam test facilities. One crystal installed on the LHC was successfully proved to be able to deflect the LHC beam by 50 microrad at the end of 2015. In the following year the bent crystal technology was sharpened to produce crystals with larger bending angles (up to 1 mrad) but still efficient in deflecting the beam. This had a large impact for future projects at CERN including new experiments and new experimental facilities to manipulate high energy beam. In future bent crystal will be employed for instance to extract high intensity beam for dark matter searches or to study the properties of heavy baryons.
At the same time detector prototypes able to monitor the deflected beam inside the ultra-high vacuum beam pipe of the accelerator and to absorb it to measure inclusive inelastic cross sections were developed. They were designed, built, calibrated and installed on the SPS accelerator at CERN thanks to the work of the CRYSBEAM team. Recently a detector based on the production of light due to the ultra-relativistic Cherenkov effect was a key technology to measure the flux of the deflected particles by a bent crystal in various dedicated data-taking periods, showing a sub-ns timing resolution and sub-mm position resolution. A massive smart absorber of particles was also employed to study how particles similar to protons and neutrons (called hadrons) were interacting with light materials as carbon, mimicking what they do in the Earth’s atmosphere when they are coming from the sky in the form of cosmic rays.
Such accelerated particles are usually handled with very special and big magnets. Instead, by using small and thin bent crystals a novel way to manipulate these high energy beams has been studied by the CRYSBEAM team in the context of the UA9 experiment at CERN. Protons (or charged ions) are in fact trapped within the crystal lattice planes by the effective electric field of all the ordered atoms in the crystal. Since the macroscopic bending of the crystal also causes a bending of the lattice planes, the trapped particles are emerging deflected at a well-defined angle. The CRYSBEAM team built and tested a number of crystals at the CERN beam test facilities. One crystal installed on the LHC was successfully proved to be able to deflect the LHC beam by 50 microrad at the end of 2015. In the following year the bent crystal technology was sharpened to produce crystals with larger bending angles (up to 1 mrad) but still efficient in deflecting the beam. This had a large impact for future projects at CERN including new experiments and new experimental facilities to manipulate high energy beam. In future bent crystal will be employed for instance to extract high intensity beam for dark matter searches or to study the properties of heavy baryons.
At the same time detector prototypes able to monitor the deflected beam inside the ultra-high vacuum beam pipe of the accelerator and to absorb it to measure inclusive inelastic cross sections were developed. They were designed, built, calibrated and installed on the SPS accelerator at CERN thanks to the work of the CRYSBEAM team. Recently a detector based on the production of light due to the ultra-relativistic Cherenkov effect was a key technology to measure the flux of the deflected particles by a bent crystal in various dedicated data-taking periods, showing a sub-ns timing resolution and sub-mm position resolution. A massive smart absorber of particles was also employed to study how particles similar to protons and neutrons (called hadrons) were interacting with light materials as carbon, mimicking what they do in the Earth’s atmosphere when they are coming from the sky in the form of cosmic rays.