Based on the theory of multiple scattering of positively charged particles channeled in the planes of a single crystal of silicon, calculations of the rms angle of scattering have been made for ...particles in the range of momenta 100–7000 GeV/c. As a result of the analysis, we find that the rms angle of multiple particle scattering can be represented by in the form of (Cl)1/w/ph, where p is the particle momentum, l is the crystal thickness and C,w,h are the constant coefficients. We show that these calculation results can be represented in a unified way using the found universal function. This function is shown to be in a good agreement with the experimental data. Furthermore, our analysis is consistent with the effect (predicted by Luboshits and Podgoretsky) of reducing multiple scattering of above-barrier particles moving at small angles to the planes of the crystal. In general, the obtained results give a simple and clear description of the scattering process under consideration.
A fast algorithm of calculating the passage of particles through a chain of bent single crystals is proposed based on the phenomenon of reflection of a relativistic-particle beam from crystal atomic ...planes. The results of calculating the passage of particles through a sequence of eight bent crystals are compared with the experimental data.
The problem of creation of high energy neutrino beams on the basis of modern and future circular proton accelerators with the help of traditional technology seems to be expensive and difficult. In ...our previous article we proposed a new method for generation of neutrino beams for 6.5 TeV protons at the LHC based on the use of focusing bent single crystals. However, in last years there have been publications devoted to proton colliders with an energy of 50 TeV. This encouraged us to study the possibility of applying of the proposed method to generate neutrino beams at these colliders. In addition, we present some new information for proton energy 6.5 TeV.
Annotation. The use of channeling in crystals is quite effective for controlling the primary proton beam, but to manipulate secondary beams π, K, etc., it is necessary not only to deflect them, but ...also to focus them, since here the beam divergences are much higher. Focusing devices created to date are suitable for applications at TeV-class accelerators because they have small transverse dimensions. To increase the angular acceptance, a device consisting of several crystals assembled into an array is proposed. In this case, two problems are solved: a large bending angle and acceptable angular acceptance of the device are ensured, which makes it possible to use it at a beam energy of 50 GeV on the domestic U-70 accelerator. The paper presents the results of testing a new device on the U-70 beam.
We studied the dechanneling length of 150 GeV/cπ− interacting with a short bent silicon crystal. Dechanneling length measures the rate and the strength of incoherent interactions of channeled ...particles in a crystal. The mechanism of dechanneling of negatively charged particles has been elucidated through simulation and experiment. It was found that the dechanneling length for negative particles is comparable to the nuclear dechanneling length for positive charges. Indeed, dechanneling of negative particles occurs as a result of incoherent interactions with the nuclei because the trajectories of such particles always intersect atomic planes, explaining the lower channeling efficiency for such particles. Obtained results can be useful for the design of crystals for manipulating high-energy negative particle beams through channeling.
The UA9 setup for the double-crystal experiment in CERN-SPS Scandale, W.; Cerutti, F.; Esposito, L.S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2020, Letnik:
975
Journal Article
Recenzirano
Experiments to measure the electric and the magnetic moments of short-lived baryons using an internal target and two bent crystals in the vicinity of one of the existing LHC detectors were recently ...proposed, in the frame of the Physics Beyond Colliders Working Group at CERN. Investigating fixed-target physics in the LHC with in-vacuum solid targets is an unprecedented challenge. As a preparatory step, the layout of the UA9 experiment, installed in the CERN SPS to explore beam manipulations assisted by bent crystals, has been modified to study the feasibility of the double-crystal scenario in a circular accelerator. Ideally, the first crystal should capture halo protons in channeling states directing them onto the internal target to produce rare baryons, whilst the second crystal, located just downstream of the target, should channel the baryons, rotate their polarization vector and deflect them towards the detector area. The upgraded UA9 layout is presented. Preliminary measurements providing an insight of the beam behavior are reported.
In this report, the continuation of studies (Afonin et al., 2003, 2012; Scandale et al., 2014) of focusing properties of bent single crystals is presented. Recently, the possibility of transforming a ...parallel beam into the point-like one has been demonstrated theoretically and experimentally (Scandale et al., 2014). Here we study an inverse problem of conversion of a point-like beam into the parallel one. It is shown that, by exploiting such a capability, the significantly more intensive secondary particle beams could be generated compared to usage of other conventional method.
An analytical description of volume reflection of charged ultrarelativistic particles in bent single crystals is considered. The relation describing the angle of volume reflection as a function of ...the transversal energy is obtained. Different angle distributions of the scattered protons in single crystals are found. Results of calculations for 400 GeV protons scattered by the silicon single crystal are presented.
Channeling efficiency in a target-crystal assembly Scandale, W.; Cerutti, F.; Esposito, L.S. ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
03/2020, Letnik:
467
Journal Article
Recenzirano
In view of possible future fixed target experiments requiring precisely steered charged particle beams, the UA9 Collaboration has undertaken experimental studies of the use of bent silicon crystals ...for this purpose. The channeling efficiency of positively charged particles inside the crystalline lattice has been investigated in detail for a setup with a tungsten target installed in front of the crystal. Due to multiple Coulomb scattering inside the target, the channeling efficiency was observed to be reduced by a factor of about 6.1 for a 180 GeV/c quasi-parallel hadron beam. The yield of nuclear interaction secondaries as an estimation of the additional machine background is also discussed.
The article proposes an analytical model to describe a recently discovered phenomenon of reduction of multiple scattering of positively charged particles during channeling in (111) crystallographic ...silicon planes. The phenomenon represents a strong suppression of the mean square angle of multiple scattering of such particles in a plane perpendicular to the channeling plane (in comparing with the non channeling particles). The proposed model is based on the development of our previously considered approximate description of the diffusion process in short crystals. Using successive reductions, we extended this description to fairly long crystals. Our analytical model explains the phenomenon observed in the experiments and allows us to calculate the behavior of the root-mean-square angle of channeling particles as a function of the crystal thickness.
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