Study of inelastic nuclear interactions of 400 GeV/c protons in bent silicon crystals for beam steering purposes

Abstract

Inelastic nuclear interaction probability of 400 GeV/c protons interacting with bent silicon crystals was investigated, in particular for both types of crystals installed at the CERN Large Hadron Collider for beam collimation purposes. In comparison to amorphous scattering interaction, in planar channeling this probability is ∼ 36% for the quasimosaic type (planes (111)), and ∼ 27% for the strip type (planes (110)). Moreover, the absolute inelastic nuclear interaction probability in the axial channeling orientation, along the 110 axis, was estimated for the first time, finding a value of 0.6% for a crystal 2 mm long along the beam direction, with a bending angle of 55 µrad. This value is more than two times lower with respect to the planar channeling orientation of the same crystal, and increases with the vertical angular misalignment. Finally, the correlation between the inelastic nuclear interaction probability in the planar channeling and the silicon crystal curvature is reported.

Silicon crystals for steering high-intensity particle beams at ultrahigh-energy accelerators

“…Assuming that a sufficiently robust absorber to dispose the extract beam is available, with respect to the classical collimation schemes, a scheme based on crystals might deliver two potential advantages: 1) As a crystal is aligned to channel particle beams between its bent atomic planes, the crystal acts as a low-loss waveguide for the beam [74,75], resulting in a strong suppression of fragmentation [76,77] and nuclear interactions with respect to the case of non-alignment and with respect to the case of traditional schemes.…”

“…The orientation of the largest faces of the wafer determines the orientation of the crystalline planes that will interact with the particle beam. Channeling efficiency and the rate of inelastic interactions [75] are mainly influenced by the distance between atomic planes and their atomic density, as a result the most performing planes are the (110) and the (111) [5]. The average distance between (111) planes (1.568 Å) is smaller than for (110) planes (1.92 Å), consequently the steering efficiency of the latter is higher and the rate of inelastic interaction with the lattice is lower.…”

Layouts for fixed-target experiments and dipole moment measurements of short-lived baryons using bent crystals at the LHC

“…The treatment of interactions between protons and bent crystals is carried out using a dedicated routine implemented in SixTrack. The details of this implementation and the physics models used can be found in [32][33][34], while its benchmarking in the energy range from 180 GeV/c to 6.5 TeV/c is reported in [33,[35][36][37][38]. This simulation setup allows estimation of the density of protons lost per metre with a resolution of 10 cm along the entire ring circumference.…”

Angular asymmetry of the nuclear interaction probability of high energy particles in short bent crystals

“…The detector, built in the framework of the UA9 Collaboration to investigate crystal-particle interactions in the North Experimental Area of the CERN-SPS, is based on a two-arm telescope able to reconstruct single tracks before and after the crystal traversal. The experimental procedure is described in details in [8]. It involves two additional fast plastic scintillators [12] symmetrically located downstream of the crystal position, on both sides of the beam line, the acquisition of whose data is integrated in the telescope DAQ.…”

“…Planar channeling and volume reflection are used for beam collimation, extraction and splitting in particle accelerators [5]. The inelastic nuclear interaction (INI) rate in short bent crystals has been experimentally investigated in [6][7][8]. For high-energy channeled protons, INI event rate considerably smaller than for the amorphous case was reported, while an increase of the rate was preliminarily observed for volume reflection orientations.…”