Orientational Coherent Effects of High-Energy Particles in aLiNbO3Crystal

Abstract

A bent lithium niobate strip was exposed to a 400-GeV/c proton beam at the external lines of CERN Super Proton Synchrotron to probe its capabilities versus coherent interactions of the particles with the crystal such as channeling and volume reflection. Lithium niobate (LiNbO3) exhibits an interplanar electric field comparable to that of Silicon (Si) and remarkable piezoelectric properties, which could be exploited for the realization of piezo-actuated devices for the control of high-energy particle beams. In contrast to Si and germanium (Ge), LiNbO3 shows an intriguing effect; in spite of a low channeling efficiency (3%), the volume reflection maintains a high deflection efficiency (83%). Such discrepancy was ascribed to the high concentration (10(4) per cm2) of dislocations in our sample, which was obtained from a commercial wafer. Indeed, it has been theoretically shown that a channeling efficiency comparable with that of Si or Ge would be attained with a crystal at low defect concentration (less than ten per cm2). To better understand the role of dislocations on volume reflection, we have worked out computer simulation via dynecharm++ Monte Carlo code to study the effect of dislocations on volume reflection. The results of the simulations agree with experimental records, demonstrating that volume reflection is more robust than channeling in the presence of dislocations.

Electromagnetic dipole moments of charged baryons with bent crystals at the LHC

“…The channeling process is implemented by including Dynecharm++ [37] and Echarm [38] into the Geant4 channeling package [39]. Such model was validated against experimental data for negative pions [30], protons [40,41,42,43,44,45,46], electrons [47,48,49,50,31] and positrons [31] in a range of energies spanning from 855 MeV (electrons at MAMI) to 400 GeV (protons at CERN). Dynecharm++ allows the tracking of a relativistic charged particle inside a crystalline medium via the numerical integration of the T-BMT classical equations of motion [1,2,3].…”

A method to align a bent crystal for channeling experiments by using quasichanneling oscillations

“…As was proposed by E. Tsyganov [2], channeling in a bent crystal can deflect a charged particle beam, flowing along bent crystal planes. This effect was observed in a number of experiments for both positively and negatively charged particles, for instance [3][4][5][6][7][8][9][10][11].…”

Bent crystals for efficient beam steering of multi TeV-particle beams

“…Indeed, the need for a crystal free from dislocation is especially relevant for the LHC. In particular, it is important that the crystal is free from dislocation, while point defects contribute less to dechanneling [ 55 , 62 , 65 ].…”