Broad angular anisotropy of multiple scattering in a Si crystal

Abstract

We observed reduction of multiple Coulomb scattering of 855 MeV electrons within a Si crystalline plate w.r.t. an amorphous plate with the same mass thickness. The reduction owed to complete or partial suppression of the coherent part of multiple scattering in a crystal vs crystal orientation with the beam. Experimental data were collected at Mainz Mikrotron and critically compared to theoretical predictions and Monte Carlo simulations. Our results highlighted maximal 7 % reduction of the r.m.s. scattering angle at certain beam alignment with the [100] crystal axes. However, partial reduction was recorded over a wide range of alignment of the electron beam with the crystal up to 15 deg. This evidence may be relevant to refine the modelling of multiple scattering in crystals for currently used software, which is interesting for detectors in nuclear, medical, high energy physics.

First design of a crystal-based extraction of 6 GeV electrons for the DESY II Booster Synchrotron

“…The CRYSTALRAD simulation code [45][46][47] is a Monte Carlo code providing fast simulations of both charged particle dynamics and radiation spectra in straight, bent and periodically bent crystal of any material and crystal lattice type with well verified experimentally models of scattering [21,25,50] and radiation [31,45] at Mainz Mikrotron MAMI for 855 MeV electrons. It exploits the following approaches.…”

“…Multiple and single Coulomb scattering on screened (Yukawa) atomic potential as well as single scattering on electrons are randomly simulated on each step of trajectory equation solution. The Coulomb scattering model includes only incoherent part of scattering [50,51], while the coherent part is simulated by trajectory calculation in the averaged atomic potential.…”

“…The performance of a bent crystal can be characterized during electron beam test, in particular by means of 855 MeV electrons at Mainz Mikrotron MAMI. The experimental setup was as in [21,31,50], namely with low angular divergence of initial beam of 21.4 µrad, being one order of magnitude less than the critical channeling angle for sub-GeV energy. The simulated angular distribution of deflected beam for the optimal crystal geometry defined above is shown in Fig.…”

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

“…An agreement at the level of few % is also present between predictions reported in [55] and in [56], where the tools used in this paper and a yet different simulation approach are used, respectively. In particular, the latter is based on solving the equation of motion for a charged particle interacting with the electric field generated by crystalline lattice accounting also for multiple scattering [57][58][59].…”

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

“…The code solves the equation of motion for a charged particle interacting with the electric field generated by atomic strings or planes accounting for multiple scattering according to Refs. [2,3]. The code accounts for a wide variety of effects, namely multiple and single Coulomb scattering on nuclei and electrons, nuclear scattering, ionization losses, crystal geometry.…”