Collimation of the circulating beam in the U-70 synchrotron by means of the reflection of particles in crystals with axial orientation

Abstract

The possibilities of the extraction and collimation of a circulating beam by a new method due to the reflection of particles in crystals with axial orientation were experimentally investigated in the Fall-2010 run at the U_70 synchrotron. Such crystals have positive features, because the axial potential is five times larger than the planar potential. It has been shown that the collimation efficiency can reach 90% due to axial effects in the crystal. Losses of the circulating beam on a collimator have been reduced by several times; this makes it possible to suppress the muon jet near the steel collimator of the circulating beam.

Planar channeling and quasichanneling oscillations in a bent crystal

“…The model implemented in this program [4,30,31,35] was also successfully applied to the explanation of different experiments on channeling radiation [24,25,35]. The effect of multiple volume reflection in a single-piece bent crystal was also predicted in the frame of this model [36][37][38] and demonstrated in several experiments [39][40][41]. The code is based on charged particles trajectory Monte Carlo simulation in a continuum potential of crystal planes or axes.…”

Radiation generated by single and multiple volume reflection of ultrarelativistic electrons and positrons in bent crystals

“…Both analytical consideration [14], extensive simulations [14,15], and experiments [16][17][18] demonstrated a fivefold increase in deflection angle with respect to an individual VR onto the vertical plane, irrespective of particle's charge. Since the nondipole radiation nature manifests itself in proximity of each reflection point, its role will be naturally increased as a result of multiple reflection.…”

“…In this case, both methods (FTPR and DIBK) can be used. However, since multiple reflections onto crystal planes occur when particles move in the field of crystal axes [14][15][16][17][18], we also have to take into account the scattering of particles by the latter. In general, as a particle moves nearly aligned with an axis, the radiation generated by the particle is influenced by both the axial and planar motion effects.…”

“…In the last years the effects of volume reflection (VR) [4,[11][12][13] and multiple volume reflection in one crystal (MVROC) [14][15][16][17][18] were observed and widely studied, mainly in connection with the problem of halo cleaning in the large hadron collider (LHC). However, both effects are also interesting from the point of view of radiation emission.…”

“…MVROC [14][15][16][17][18] is realized when particles move at relatively small angles with respect to one of the major crystal axes, so that their trajectories become tangential at some point to most of the crystal planes sharing the same axis. Both analytical consideration [14], extensive simulations [14,15], and experiments [16][17][18] demonstrated a fivefold increase in deflection angle with respect to an individual VR onto the vertical plane, irrespective of particle's charge.…”