Searcharxiv⌕ Search

arXiv subjects

Sergei Nagaitsev

Publications and source records attributed to Sergei Nagaitsev.

53 records · Page 3Linked to original sources
arXiv2017

Single-Particle Dynamics in a Nonlinear Accelerator Lattice: Attaining a Large Tune Spread with Octupoles in IOTA

Fermilab is constructing the Integrable Optics Test Accelerator (IOTA) as the centerpiece of the Accelerator R&D Program towards high-intensity circular machines. One of the factors limiting the beam intensity in present circular accelerators is collective instabilities, which can be suppressed by a spread of betatron frequencies (tunes) through the Landau damping mechanism or by an external damper, if the instability is slow enough. The spread is usually created by octupole magnets, which introduce the tune dependence on the amplitude and, in some cases, by a chromatic spread (tune dependence on particle's momentum). The introduction of octupoles usually has both the beneficial (improved Landau damping) and harmful properties, such as a resonant behavior and a reduction of the dynamic aperture. One of the research goals at the IOTA ring is to achieve a large betatron tune spread, while retaining a large dynamic aperture, using conventional octupole magnets in a special but realistic accelerator configuration. In this paper, we present results of computer simulations of an electron beam in the IOTA by particle tracking and the Frequency Map Analysis. The results show that the ring's octupole magnets can be configured to provide a betatron tune shift of 0.08 (for particles at large amplitudes) with the dynamical aperture of over 20 beam sigma for a 150-MeV electron beam. The influence of the synchrotron motion, lattice errors, and magnet imperfections is insignificant for the parameters and levels of tolerances set by the design of the ring. The described octupole insert could be beneficial for enhancing Landau damping in high intensity machines.

physics.acc-ph↗
arXiv2017

Luminosity Limitations in Linear Colliders Based on Plasma Acceleration

Particle acceleration in plasma creates a possibility of exceptionally high accelerating gradients and appears as a very attractive option for future linear electron-positron and/or photon-photon colliders. These high accelerating gradients were already demonstrated in a number of experiments. However, a linear collider requires exceptionally high beam brightness which still needs to be demonstrated. In this article we discuss major phenomena which limit the beam brightness of accelerated beam and, consequently, the collider luminosity.

physics.acc-ph↗
arXiv2016

IOTA (Integrable Optics Test Accelerator): Facility and Experimental Beam Physics Program

The Integrable Optics Test Accelerator (IOTA) is a storage ring for advanced beam physics research currently being built and commissioned at Fermilab. It will operate with protons and electrons using injectors with momenta of 70 and 150 MeV/c, respectively. The research program includes the study of nonlinear focusing integrable optical beam lattices based on special magnets and electron lenses, beam dynamics of space-charge effects and their compensation, optical stochastic cooling, and several other experiments. In this article, we present the design and main parameters of the facility, outline progress to date and provide the timeline of the construction, commissioning and research. The physical principles, design, and hardware implementation plans for the major IOTA experiments are also discussed.

physics.acc-ph↗
arXiv2014

Fermilab 4.3-MeV Electron Cooler

The Recycler Electron Cooler (REC) was the first cooler working at a relativistic energy (gamma = 9.5). It was successfully developed in 1995-2004 and was in operation at Fermilab in 2005-2011, providing cooling of antiprotons in the Recycler ring. After introducing the physics of electron cooling and the REC system, this paper describes measurements carried out to tune the electron beam and optimize its cooling properties. In particular, we discuss the cooling strategy adopted for maximizing the collider integrated luminosity.

physics.acc-ph↗
arXiv2014

Fermilab Antiproton Source, Recycler Ring, and Main Injector

At the end of its operations in 2011, the Fermilab antiproton production complex consisted of a sophisticated target system, three 8-GeV storage rings (namely the Debuncher, the Accumulator and the Recycler), 25 independent multi-GHz stochastic cooling systems, the world's only relativistic electron cooling system and a team of technical experts equal to none. The accelerator complex at Fermilab supported a broad physics program including the Tevatron Collider Run II, neutrino experiments using 8-GeV and 120-GeV proton beams, as well as a test beam facility and other fixed target experiments using 120-GeV primary proton beams. This paper provides a brief description of Fermilab accelerators as they operated at the end of the Collider Run II (2011).

physics.acc-ph↗
arXiv2014

High-power magnetron transmitter as an RF source for superconducting linear accelerators

A concept of a high-power magnetron transmitter for operation within a wideband control feedback loop in phase and amplitude is presented. This transmitter is proposed to drive Superconducting RF (SRF) cavities for intensity-frontier GeV-scale proton/ion linacs. The transmitter performance at the dynamic control was verified in experiments with CW, S-Band, 1 kW magnetrons. The wideband control of magnetrons, required for the superconducting linacs, was realized using the magnetrons, injection-locked by the phase-modulated signals. The capabilities of the magnetrons injection-locked by the phase-modulated signals and adequateness for feeding of SRF cavities were verified by measurements of the transfer function magnitude characteristics of single and 2-cascade magnetrons, by measurements the magnetrons phase performance and by measurements of spectra of the carrier frequency. At the ratio of power of locking signal to output power less than -13 dB (in 2-cascade scheme per magnetron, respectively) we demonstrated a phase modulation bandwidth of over 1.0 MHz. The carrier frequency spectrum width about of 1 Hz at the level less than -60 dBc did not demonstrate broadening at wide range of magnitude and frequency of the phase modulation of the injection-locking signal. The wideband dynamic control of output power of the transmitter model was first experimentally demonstrated using two magnetrons, combined in power and injection-locked by the phase-modulated signals. The experiments with the injection-locked magnetrons adequately emulated the wideband dynamic control with a feedback control system, which will allow suppressing all known parasitic modulation of the accelerating field in the SRF cavities. The magnetron transmitter concept, tests of the setups and injection-locking of magnetrons by phase-modulated signals are discussed in this work.

physics.acc-ph↗
arXiv2013

High Intensity Secondary Beams Driven by Protons

As part of the Intensity Frontier effort within the 2013 Community Summer Study, a workshop on the proton machine capabilities was held (High Intensity Secondary Beams Driven by Proton Beams) April 17-20, 2013 at Brookhaven National Laboratory in Upton, NY. Primary aims of the workshop were to understand: 1) the beam requirements for proposed high intensity proton beam based measurements; 2) the capabilities of existing world-wide high power proton machines; 3) proton facility upgrade plans and proposals for new facilities; 4) and to document the R&D needs for proton accelerators and target systems needed to support proposed intensity frontier measurements. These questions are addressed in this summary.

physics.acc-ph↗
arXiv2013

Effects of Nonlinear Decoherence on Halo Formation

High intensity proton linacs and storage rings are central for the development of advanced neutron sources, extending the intensity frontier in high energy physics, as drivers for the production of pions in neutrino factories or muon colliders, and for the transmutation of radioactive waste. Such high intensity beams are not attainable using conventional linear lattices. It has been shown in the single particle limit that integrable nonlinear lattices permit much larger tune spreads than conventional linear lattices, which would mitigate many of the space charge restrictions that limit intensity. In this paper, we present numerical studies of space charge effects on a trial nonlinear lattice with intense bunches. We observe that these nonlinear lattices and their accompanying tune spreads strongly mitigate halo formation using a result from the particle-core model known to cause halo formation in linear lattices.

physics.acc-ph↗
arXiv2013

The Case for a Muon Collider Higgs Factory

We propose the construction of a compact Muon Collider Higgs Factory. Such a machine can produce up to \sim 14,000 at 8\times 10^{31} cm^-2 sec^-1 clean Higgs events per year, enabling the most precise possible measurement of the mass, width and Higgs-Yukawa coupling constants.

hep-ph↗
arXiv2013

Comment on "Physics considerations for laser-plasma linear colliders" and on "Beamstrahlung considerations in laser-plasma-accelerator-based linear colliders"

C. B. Schroeder, E. Esarey, C. Benedetti, and W. P. Leemans {Phys. Rev. ST Accel. Beams 13, 101301 (2010) and 15, 051301 (2012)} have proposed a set of parameters for a TeV-scale collider based on plasma wake field accelerator principles. In particular, it is suggested that the luminosities greater than 10^34 cm-2s-1 are attainable for an electron-positron collider. In this comment we dispute this set of parameters on the basis of first principles. The interactions of accelerating beam with plasma impose fundamental limitations on beam properties and, thus, on attainable luminosity values.

physics.acc-ph↗
arXiv2013

Project X: A Flexible High Power Proton Facility

Project X is a high intensity proton facility that will support a world-leading Intensity Frontier research program over the next several decades at Fermilab. When compared to other facilities in the planning stages elsewhere in the world Project X is completely unique in its ability to deliver, simultaneously, up to 6 MW of site-wide beam power to multiple experiments, at multiple energies, and with flexible beam formats. Project X will support a wide range of experiments based on neutrinos, muons, kaons, nucleons, and nuclei. In addition, Project X will lay the foundation for the long-term development of a Neutrino Factory and/or Muon Collider. A complete concept for Project X has been developed and is documented in the Project X Reference Design Report.

physics.acc-ph↗
arXiv2013

A High-power 650 MHz CW Magnetron Transmitter for Intensity Frontier Superconducting Accelerators

A concept of a 650 MHz CW magnetron transmitter with fast control in phase and power, based on two-stage injection-locked CW magnetrons, has been proposed to drive Superconducting Cavities (SC) for intensity-frontier accelerators. The concept is based on a theoretical model considering a magnetron as a forced oscillator and experimentally verified with a 2.5 MW pulsed magnetron. To fulfill fast control of phase and output power requirements of SC accelerators, both two-stage injection-locked CW magnetrons are combined with a 3-dB hybrid. Fast control in output power is achieved by varying the input phase of one of the magnetrons. For output power up to 250 kW we expect the output/input power ratio to be about 35 to 40 dB in CW or quasi-CW mode with long pulse duration. All magnetrons of the transmitter should be based on commercially available models to decrease the cost of the system. An experimental model using 1 kW, CW, S-band, injection-locked magnetrons with a 3-dB hybrid combiner has been developed and built for study. A description of the model, simulations, and experimental results are presented and discussed in this work.

physics.acc-ph↗
arXiv2012

Nonlinear optics as a path to high-intensity circular machines

What prevents us from building super-high intensity accelerators? The answer is case-specific, but it often points to one of the following phenomena: machine resonances, various tune shifts (and spreads), and instabilities. These three phenomena are interdependent in all present machines. In this paper we propose a path toward alleviating these phenomena by making accelerators nonlinear. This idea is not new: Orlov (1963) and McMillan (1967) have proposed initial ideas on nonlinear focusing systems for accelerators. However, practical implementations of such ideas proved elusive, until recently.

physics.acc-ph↗
arXiv2012

On Quantum Integrable Systems

Many quantum integrable systems are obtained using an accelerator physics technique known as Ermakov (or normalized variables) transformation. This technique was used to create classical nonlinear integrable lattices for accelerators and nonlinear integrable plasma traps. Now, all classical results are carried over to a nonrelativistic quantum case.

quant-ph↗