Alexey Vorozhtsov | Lund University (original) (raw)

Papers by Alexey Vorozhtsov

$Research paper thumbnail of Design Study of the High Gradient Magnets for a Future Diffraction-Limited Light Source at MAX IV$

The highly advanced plan of the RIKEN AVF cyclotron (Japan) is under way. The intensity of the 14... more The highly advanced plan of the RIKEN AVF cyclotron (Japan) is under way. The intensity of the 14 N 5+ ion beam more than 10 p A is required to obtain a sufficient yield of secondary particles. The computer model of the AVF electromagnetic field has been prepared and successfully checked against the measurements. The focus of the present study is on the 2 nd RF harmonic regime. The intermediate goal of the upgrade is improvement of the transmission efficiency and the beam quality of the regime. Measured Hyper ECR output emittances were 64 and 135 mm mrad, from which the emittance of 100 mm mrad was assumed for both transverse oscillations in the simulation. The detailed account of the transmission efficiency and incremental losses are given. The optimization of the starting beam parameters for the existing electrode structure was considered first. The goal is to obtain a sufficiently small axial angle at the exit from the inflector to decrease axial losses in the initial turns. To t...

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2016

The AWAKE project at CERN is planned to study proton driven plasma wakefield acceleration with an... more The AWAKE project at CERN is planned to study proton driven plasma wakefield acceleration with an externally injected electron beam. Therefore two transfer lines are being designed in order to provide the proton beam from the SPS and the electron beam from an RF gun to the plasma cell. The commissioning of the proton line will take place in 2016 for the first phase of the experiment, which is focused on the self-modulation of a 12 cm long proton bunch in the plasma. The electron line will be added for the second phase of AWAKE in 2017, when the wakefield will be probed with an electron beam of 10-20 MeV/c. The challenge for these transfer lines lies in the parallel operation of the proton, electron and laser beam used to ionize the plasma and seed the self-modulation. These beams, of different characteristics, need to be synchronized and positioned for optimized injection conditions into the wakefield. This task requires great flexibility in the transfer line optics. The status of these designs will be presented in this paper.

Radiation Measurements, 1995

Inhalation of radon and its daughter products makes the major contribution to the total exposure ... more Inhalation of radon and its daughter products makes the major contribution to the total exposure of the population to natural radiations. In implementing a complex ecological survey, concentrations of radon and its daughter products were measured in different regions of Russia, namely, in the St Petersburg Region, the Central Territories and the Altay Territory. Two suitable low price versions of the dosimeters for measuring environmental radon concentrations based on track-etch and activated-charcoal detectors were used. The radon daughter product activity and the effective dose equivalents were calculated with an equilibrium factor of 0.5 and a recommended effective dose equivalent factor of 0.061 mSv (Bq m-J)-t. Indoor measurements were taken in more than 1000 dwellings and public and industrial buildings of 21 towns and villages. The track chambers were exposed for about 2-3 months and the charcoal detectors for 6-10 days, mainly during the summer. The actual radon and daughter product concentration levels and effective dose equivalents (EDE) are presented and analyzed.

Nuclear Physics B - Proceedings Supplements, 2008

ATLAS is a general-purpose detector at the 14 TeV proton-proton Large Hadron Collider at CERN. Th... more ATLAS is a general-purpose detector at the 14 TeV proton-proton Large Hadron Collider at CERN. The muon spectrometer will operate in the magnetic field provided by a large, eight-coil barrel toroid magnet bracketed by two smaller toroidal end-caps. The toroidal field is non-uniform, with an average value of about 0.5 T in the barrel region, and is monitored using three-dimensional Hall sensors which must be accurate to ∼ 1 mT. The barrel coils were installed in the cavern from 2004 to 2006, and recently powered up to their nominal current. The Hall-sensor measurements are compared with calculations to validate the magnetic models, and used to reconstruct the position and shape of the coil windings. Field perturbations by the magnetic materials surrounding the muon spectrometer are found in reasonable agreement with finite-element magnetic-field simulations.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2019

A magnetic spectrometer has been developed for the AWAKE experiment at CERN in order to measure t... more A magnetic spectrometer has been developed for the AWAKE experiment at CERN in order to measure the energy distribution of bunches of electrons accelerated in wakefields generated by proton bunches in plasma. AWAKE is a proof-of-principle experiment for proton-driven plasma wakefield acceleration, using proton bunches from the SPS. Electron bunches are accelerated to O(1 GeV) in a rubidium plasma cell and then separated from the proton bunches via a dipole magnet. The dipole magnet also induces an energy-dependent spatial horizontal spread on the electron bunch which then impacts on a scintillator screen. The scintillation photons emitted are transported via three highly-reflective mirrors to an intensified CCD camera, housed in a dark room, which passes the images to the CERN controls system for storage and further analysis. Given the known magnetic field and determination of the efficiencies of the system, the spatial spread of the scintillation photons can be converted to an electron energy distribution. A lamp attached on a rail in front of the scintillator is used to calibrate the optical system, with calibration of the scintillator screen's response to electrons carried out at the CLEAR facility at CERN. In this article, the design of the AWAKE spectrometer is presented, along with the calibrations carried out and expected performance such that the energy distribution of accelerated electrons can be measured.

Cornell University - arXiv, Feb 28, 2012

Two high field quality quadrupole magnets QF1FF and QD0FF are required for the final focus system... more Two high field quality quadrupole magnets QF1FF and QD0FF are required for the final focus system of the ATF3. In this paper we focus on the design of the QF1FF magnet. The proposed design is a permanent magnet quadrupole (PMQ) with adjustable strength. Alternative solutions such as conventional electromagnetic quadrupole (EMQ) and a hybrid quadrupole (combination of permanent magnet and electromagnet) are also presented and briefly discussed.

Applied research at the NICA accelerator complex include the following areas that are under const... more Applied research at the NICA accelerator complex include the following areas that are under construction: single event effects testing on capsulated microchips (energy range of 150-500 MeV/n) at the Irradiation Setup for Components of Radioelectronic Apparature (ISCRA) and on decapsulated microchips (ion energy up to 3,2 MeV/n) at the Station of CHip Irradiation (SOCHI), space radiobiological research and modelling of influence of heavy charged particles on cognitive functions of the brain of small laboratory animals and primates (energy range 500-1000 MeV/n) at the Setup for Investigation of Medical Biological Objects (SIMBO). Description of main systems and beam parameters at the ISCRA, SOCHI and SIMBO applied research stations is presented. The new beam transfer lines from the Nuclotron to ISCRA and SIMBO stations, and from HILAC to SOCHI station are being constructed. Description of the transfer lines layout, the magnets and diagnostic detectors, results of the beam dynamics simulations are described given.

Nowadays space exploration has faced the issue of radiation risk to microelectronics and biologic... more Nowadays space exploration has faced the issue of radiation risk to microelectronics and biological objects. The new beamlines and irradiation stations of the Nuclotron-based Ion Collider fAcility (NICA) at JINR are currently under construction to study this issue. The beamline parameters, different methods for homogeneous irradiation of targets such as scanning, and beam profile shaping by octupole magnets are discussed. A short description of the building infrastructure, magnet elements, and detectors for these beamlines is also given.

The SXL (Soft X-ray Laser) project developed a conceptual design for a soft X-ray Free Electron L... more The SXL (Soft X-ray Laser) project developed a conceptual design for a soft X-ray Free Electron Laser in the 1–5 nm wavelength range, driven by the existing MAX IV 3 GeV linac. In this contribution we will focus on the FEL operation modes developed for the first phase of the project based on two different linac modes. The design work was supported by the Knut and Alice Wallenberg foundation and by several Swedish universities and organizations (Stockholm, Uppsala, KTH Royal Institute of Technology, Stockholm-Uppsala FEL center, MAX IV laboratory and Lund University).

Journal of Synchrotron Radiation, 2021

In this paper the design of the free-electron laser (FEL) in the SXL (Soft X-ray Laser) project a... more In this paper the design of the free-electron laser (FEL) in the SXL (Soft X-ray Laser) project at the MAX IV Laboratory is presented. The target performance parameters originate in a science case put forward by Swedish users and the SXL FEL is foreseen to be driven by the existing MAX IV 3 GeV linac. The SXL project is planned to be realized in different stages and in this paper the focus is on Phase 1, where the basic operation mode for the FEL will be SASE (self-amplified spontaneous emission), with an emphasis on short pulses. Simulation results for two linac bunches (high and low charge) with different pulse duration are illustrated, as well as the performance for two-color/two-pulses mode and power enhancement through tapering. Besides standard SASE and optical klystron configurations, the FEL setup is also tailored to allow for advanced seeding schemes operations. Finally possible upgrades that will be implemented in a second phase of the project are discussed.

The AWAKE project at CERN is planned to study proton driven plasma wakefield acceleration. The pr... more The AWAKE project at CERN is planned to study proton driven plasma wakefield acceleration. The proton beam from the SPS will be used in order to drive wakefields in a 10 m long Rubidium plasma cell. In the first phase of this experiment, scheduled in 2016, the self-modulation of the proton beam in the plasma will be studied in detail, while in the second phase an external electron beam will be injected into the plasma wakefield to probe the acceleration process. The installation of AWAKE in the former CNGS experimental area and the required optics flexibility define the tight boundary conditions to be fulfilled by the electron beam line design. The transport of low energy (10-20 MeV) bunches of 1.25·10 electrons and the synchronous copropagation with much higher intensity proton bunches (3·10) determines several technological and operational challenges for the magnets and the beam diagnostics. The current status of the electron line layout and the associated equipment are presented ...

Since 2009 the CERN Magnet Group (CERN-TEMSC) started R&D activities in order to focalize the mos... more Since 2009 the CERN Magnet Group (CERN-TEMSC) started R&D activities in order to focalize the most challenging and interesting cases to be studied among the magnets needed for CLIC the Compact Linear Collider. In the last four years several theoretical studies, models and prototypes were realized mainly in two domains: magnets for the modules, the modular elements that are composing the backbone of the two-beam linac structure of CLIC, and for the Machine Detector Interface (MDI) including the final focus elements and the anti-solenoid. In this paper we revise the status for the procured magnets. Among them the Drive Beam Quadrupoles, Main Beam Quadrupoles, Steering Correctors all challenging for the required compactness, performances and production size, and the QD0 final quadrupole and the SD0 sextupole, challenging for the high performances required in terms of gradients and stability.

Frontiers in Medicine, 2021

CERN-MEDICIS is an off-line isotope separator facility for the extraction of radioisotopes from i... more CERN-MEDICIS is an off-line isotope separator facility for the extraction of radioisotopes from irradiated targets of interest to medical applications. The beamline, between the ion source and the collection chamber, consists of ion extraction and focusing elements, and a dipole magnet mass spectrometer recovered from the LISOL facility in Louvain-la-Neuve. The latter has been modified for compatibility with MEDICIS, including the installation of a window for injecting laser light into the ion source for resonance photo-ionization. Ion beam optics and magnetic field modeling using SIMION and OPERA respectively were performed for the design and characterization of the beamline. The individual components and their optimal configuration in terms of ion beam extraction, mass separation, and ion transport efficiency is described, along with details of the commissioning and initial performance assessment with stable ion beams.

Journal of synchrotron radiation, 2018

The MAX IV 3 GeV electron storage ring in Lund, Sweden, is the first of a new generation of light... more The MAX IV 3 GeV electron storage ring in Lund, Sweden, is the first of a new generation of light sources to make use of the multibend-achromat lattice (MBA) to achieve ultralow emitance and hence ultrahigh brightness and transverse coherence. The conceptual basis of the MAX IV 3 GeV ring project combines a robust lattice design with a number of innovative engineering choices: compact, multifunctional magnet blocks, narrow low-conductance NEG-coated copper vacuum chambers and a 100 MHz radio-frequency system with passively operated third-harmonic cavities for bunch lengthening. In this paper, commissioning and first-year operational results of the MAX IV 3 GeV ring are presented, highlighting those aspects that are believed to be most relevant for future MBA-based storage rings. The commissioning experience of the MAX IV 3 GeV ring offers in this way an opportunity for validation of concepts that are likely to be essential ingredients of future diffraction-limited light sources.

This document describes the preliminary electromagnetic design of the warm magnets required for t... more This document describes the preliminary electromagnetic design of the warm magnets required for the CLIC Main Beam (Beam Transport)

IEEE Transactions on Applied Superconductivity, 2016

A new watt balance experiment is under development at the Federal Institute of Metrology (METAS, ... more A new watt balance experiment is under development at the Federal Institute of Metrology (METAS, Switzerland). Its scope is to link the mass unit to the Plank constant in order to set a new definition of the kilogram, no longer based on the international prototype (IPK). The experiment is performed in two steps with the same setup , and requires that the magnetic field produced in the two steps by the magnet fitted in the setup remains stable within few parts per 10 8. The paper describes the design, manufacture and characterization of this magnet, performed through a collaboration between METAS and CERN.

A highly advanced upgrade plan of the RIKEN AVF cyclotron is underway. The present study is to ex... more A highly advanced upgrade plan of the RIKEN AVF cyclotron is underway. The present study is to expand the region of its available acceleration energies as well as to increase the beam intensity with the help of detailed orbit simulations. The computer model of the AVF 3D electromagnetic fields was prepared and successfully checked against the measurements. Electric and magnetic field distributions and mechanical structures were transmitted to the beam dynamics code for simulations, and particle losses during the injection, acceleration and extraction were estimated. Some experiments already conducted with the beams confirmed the selection of the machine parameters based on the beam dynamics simulations. The new inflector geometry and the optimized central electrode structure have been formulated for the upgrade.