Searcharxiv⌕ Search

arXiv subjects

V. M. Biryukov

Publications and source records attributed to V. M. Biryukov.

At least 19 recordsLinked to original sources
arXiv2022

Improved experimental layout for dipole moment measurements at the LHC

The electric and magnetic dipole moment of charm and bottom baryons can be measured for the first time by using bent crystal technology at the LHC. The experimental method, proposed in recent years, suffers from limited statistics, which dominates the uncertainty of the measurement. In this work, we present an alternative experimental layout, based on the use of crystal lenses, that improves the trapping efficiency by about a factor 15 (35) for a 2-cm (5-mm) target with respect to the nominal layout, with plain crystal faces. The efficiencies are evaluated taking into account the constraints from the LHC machine, and the technical challenges to realize this novel experimental method are discussed.

hep-ex↗
arXiv2022

On the scaling of electron dechanneling length in bent crystals

We suggest a way to compare the experiments and simulations of electron dechanneling length in bent crystals performed at different energies and different radii. As an example, we compare the SLAC experiment at 3-14 GeV with earlier published predictions of two different Monte Carlo codes for 855 MeV and 50 GeV, and with MAMI experiment at 855 MeV.

physics.acc-ph↗
arXiv2021

Upper limit on efficiency of electron deflection in bent crystals

Basing on experiments at SLAC, MAMI, CERN, and on Monte Carlo simulations, we assess the physical limits on efficiency and reachable angles of electron deflection in bent crystals in the energy range from sub-GeV to sub-TeV. We find that applications of electron channeling for beam deflection are possible, limited by maximal deflection angle of 2-3 mrad at sub-GeV, 1-2 mrad at multi-GeV, and 0.5-1 mrad at sub-TeV energy. This opens opportunities for crystal-assisted electron beam extraction from accelerator rings.

physics.acc-ph↗
arXiv2021

Possibility to make a beam of tau-leptons and charmed particles by a channeling crystal

We suggest a way to capture by a focusing crystal the short-lived particles (tau leptons, charmed baryons) produced in the decays downstream of a target hit by primary protons. The beam of captured short-lived particles can be extracted from the debris produced in the target and bent onto experimental setup over a distance of centimetres. The debris is rejected by the crystal, i.e. it remains nonchannelled. The technique can handle the particles with decay length cτ down to 1 micron.

physics.ins-det↗
arXiv2009

The limits of volume reflection in bent crystals

We show that theory predictions for volume reflection in bent crystals agree with recent experimental data. This makes possible to predict volume reflection angle and efficiency in a broad range of energy for various crystals. A simple formula is proposed for volume reflection efficiency. We derive the physical limits for application of crystal reflection at high-energy accelerators where it may help beam collimation.

physics.acc-ph↗
arXiv2007

Comment on "Feasibility of an electron-based crystalline undulator"

Tabrizi et al. [physics/0701342] discuss the feasibility of an electron-based crystal undulator (e-CU) by planar channeling of 50 GeV electrons through a periodically bent crystal. We show that their scheme is not feasible. First, their undulator parameter is K >> 1 always, which destroys photon interference. Second, they overestimate the electron dechanneling length in e-CU by an order of magnitude, which shortens the number N of e-CU periods from 5-15 (as they hope) to just 1-2. This kills their e-CU concept again. We made first simulation of electron channeling in undulated crystal and conclude that an electron-based crystal wiggler is feasible with wiggler strength K=10 and number of periods N=2.

physics.acc-ph↗
arXiv2007

Crystal channeling of LHC forward protons with preserved distribution in phase space

We show that crystal can trap a broad (x, x', y, y', E) distribution of particles and channel it preserved with a high precision. This sampled-and-hold distribution can be steered by a bent crystal for analysis downstream. In simulations for the 7 TeV Large Hadron Collider, a crystal adapted to the accelerator lattice traps 90% of diffractively scattered protons emerging from the interaction point with a divergence 100 times the critical angle. We set the criterion for crystal adaptation improving efficiency ~100-fold. Proton angles are preserved in crystal transmission with accuracy down to 0.1 microrad. This makes feasible a crystal application for measuring very forward protons at the LHC.

hep-ph↗
arXiv2007

Scattering in crystals with effective radiation length in the micron range

In computer simulations we find that particles can scatter in bent crystal lattices with effective radiation length down to a few micron or 300-700 times shorter than in the corresponding amorphous materials. We derive a theoretical estimate independent of energy for the effective radiation length that is in agreement with our simulations for C, Si, Ge, and W crystal lattices. We show that in the ongoing collimation experiment at the Tevatron a crystal-based smart scattering material could outperform a channeling crystal in efficiency of collimation reducing the local background rate by a factor of 40.

physics.acc-ph↗
arXiv2006

Coherent effects in crystal collimation

We present theory for coherent effects observed in crystal collimation experiments that is in good quantitative agreement with RHIC and Tevatron data. We show that coherent scattering in a bent crystal strongly amplifies beam diffusion, with an effective radiation length shortened by orders of magnitude compared to amorphous material. This coherent scattering could replace the traditional amorphous scattering in accelerator collimation systems. We predict that crystal collimation for negative particles can be as strong as for positives, unlike with channeling effect. This opens a principle way for efficient crystal steering of negative particles at accelerators. It can be demonstrated with antiproton crystal collimation at the Tevatron. We predict strong effects for the upcoming Tevatron experiment, for protons and antiprotons.

physics.acc-ph↗
arXiv2006

Verification of crystal collimation model in experiment

The studies of crystal collimation in the experiments at Relativistic Heavy Ion Collider and Tevatron and in computer simulations reveal strong coherent effects observed in a very broad angular range. Our theory explains the effects by coherent scattering on the potential of bent crystal atomic planes, which amplifies beam diffusion in accelerator by orders of magnitude. This coherent scattering in bent crystal is being studied in a CERN SPS experiment. We present Monte Carlo predictions for the SPS and Tevatron experiments, and show the implications of the coherent scattering effect for crystal collimation in the Large Hadron Collider.

physics.acc-ph↗
arXiv2006

Crystal Channelling in Accelerators

Crystal lattice can trap and channel particle beams along major crystallographic directions. In a bent crystal, the channelled particles follow the bend. This makes a basis for an elegant technique of beam steering by means of bent channelling crystals, experimentally demonstrated from 3 MeV to 1 TeV. This technique was strongly developed in recent studies at CERN, FNAL, IHEP, and BNL, and can lead to interesting applications also at the LHC, such as crystal collimation making a collider cleaner by an order of magnitude. We review recent developments in the field and show outlook for the future.

physics.acc-ph↗
arXiv2006

Observation of "volume reflection" effect in crystal collimation experiments

Strong effect of beam coherent scattering ("reflection") in a field of bent crystal is observed in crystal collimation experiments performed with heavy ions and protons at RHIC and started at Tevatron collider. Detailed simulation using Monte Carlo code CATCH is done in order to understand the observations and relate them to the physics of beam coherent scattering in crystal. A.M. Taratin and S.A. Vorobiev predicted the effect of beam "volume reflection" in bent crystals in 1987. The presented data is the first manifestation of this new physical phenomenon in experiment.

physics.acc-ph↗
arXiv2005

Extraction of the Proton Beam from the 70 GeV IHEP Accelerator

This paper presents the physical background for particle extraction from IHEP accelerator using short bent silicon crystals, analyses the results of the studies, considers in detail the regime of simultaneous work of crystal extraction and several internal targets. It is experimentally shown that the use of short crystals allows the extraction of beams with intensity of 10e12 proton/cycle with efficiency of 85%.

physics.acc-ph↗
arXiv2005

Crystal simulations: the road from the SPS to the LHC

The understanding of the crystal collimation and extraction experiments performed in the recent decade at CERN SPS, FNAL Tevatron, IHEP U-70 and RHIC is reviewed from the standpoint of Monte Carlo simulations. The expectations for the LHC - the crystal efficiency and the requirements to a crystal - are outlined basing on the same computer model verified in the above experiments. Finally, we discuss key issues for the future experiments at CERN SPS and Tevatron aiming to reach the most efficient channeling and to bring these tests to the future LHC as close as possible.

physics.acc-ph↗
arXiv2005

In-situ calibration of forward hadron calorimeters of CMS at LHC

Physical possibility for bending the LHC protons (or ions) a huge angle of 1-20 degrees in the energy range of 0.45 to 7 TeV by means of a bent channeling crystal of Silicon or Germanium is demonstrated. Such an application can be useful for calibration of CMS (or ATLAS) calorimeters in situ by the LHC beam of precisely known energy. We show by simulations that such an application would be feasible at the LHC, and report the experience of IHEP Protvino in bending 70 GeV protons by 9 degrees (150 mrad) during 10 years in 1994-2004 experiments.

hep-ex↗
arXiv2005

Channeling as a method of making nanosized beams of particles

Particle channeling in a bent crystal lattice has led to an efficient instrument for beam steering at accelerators, demonstrated from MeV to TeV energies. In particular, crystal focusing of high energy protons to micron size has been demonstrated at IHEP with the results well in match with Lindhard (critical angle) prediction. Channeling in crystal microstructures has been proposed as a unique source of a microbeam of high-energy particles. Channeling in nanostructures (single-wall and multi-wall nanotubes) offers the opportunities to produce ion beams on nanoscale. Particles channeled in a nanotube (with typical diameter of about 1 nanometer) are trapped in two dimensions and can be steered (deflected, focused) with the efficiency similar to that of crystal channeling or better. This technique has been a subject of computer simulations, with experimental efforts under way in several high energy labs, including IHEP. We present the theoretical outlook for making channeling-based nanoscale ion beams and report the experience with crystal-focused microscale proton beams.

physics.acc-ph↗
arXiv2005

Studies of Nanotube Channeling for Efficient Beam Scraping at Accelerators

While particle beam steering (and in particular, "scraping") in accelerators by bent channeling crystals is an established technique extensively tested at IHEP Protvino and other major high-energy labs, an interesting question is how one could improve channeling capabilities by applying modern nanotechnology. Theoretical research of nanotube channeling was in progress over recent years. In this work, we assess potential benefits from nanotube channeling for real accelerator systems. We report simulation studies of channeling in nanostructured material (carbon SWNT and MWNT) tested for possible serving as a primary scraper for the collimation systems of hadron colliders. The advantages of nanostructured material as a potential choice for a primary scraper in a high-energy accelerator such as LHC or the Tevatron are discussed in comparison to crystal lattices and amorphous material. We evaluate physical processes relevant to this application and reveal nanotechnology requirements.

physics.acc-ph↗