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V. A. Lebedev

Publications and source records attributed to V. A. Lebedev.

13 recordsLinked to original sources
arXiv2020

A Single-pass Cr:ZnSe Amplifier for Broadband Infared Undulator Radiation

An amplifier based on a highly-doped Chromium Zinc-Selenide (Cr:ZnSe) crystal is proposed to increase the pulse energy emitted by an electron bunch after it passes through an undulator magnet. The primary motivation is a possible use of the amplified undulator radiation emitted by a beam circulating in a particle accelerator storage ring to increase the particle beam's phase-space density---a technique dubbed Optical Stochastic Cooling (OSC). This paper uses a simple four energy level model to estimate the single-pass gain of Cr:ZnSe and presents numerical calculations combined with wave-optics simulations of undulator radiation to estimate the expected properties of the amplified undulator wave-packet.

physics.acc-ph↗
arXiv2020

Damping rate limitations for transverse dampers in large hadron colliders

The paper focuses on two issues important for design and operation of bunch-by-bunch transverse damper in a very large hadron collider, where fast damping is required to suppress beam instabilities and noise induced emittance growth. The first issue is associated with kick variation along a bunch which affects the damping of head-tail modes. The second issue is associated with affect of damper noise on the instability threshold.

physics.acc-ph↗
arXiv2017

Wave-Optics Modeling of the Optical-Transport Line for Passive Optical Stochastic Cooling

Optical stochastic cooling (OSC) is expected to enable fast cooling of dense particle beams. Transition from microwave to optical frequencies enables an achievement of stochastic cooling rates which are orders of magnitude higher than ones achievable with the classical microwave based stochastic cooling systems. A subsytem critical to the OSC scheme is the focusing optics used to image radiation from the upstream "pickup" undulator to the downstream "kicker" undulator. In this paper, we present simulation results using wave-optics calculation carried out with the {\sc Synchrotron Radiation Workshop} (SRW). Our simulations are performed in support to a proof-of-principle experiment planned at the Integrable Optics Test Accelerator (IOTA) at Fermilab. The calculations provide an estimate of the energy kick received by a 100-MeV electron as it propagates in the kicker undulator and interacts with the electromagnetic pulse it radiated at an earlier time while traveling through the pickup undulator.

physics.acc-ph↗
arXiv2014

Test of Optical Stochastic Cooling in the IOTA Ring

A new 150 MeV electron storage ring is being built at Fermilab. The construction of a new machine pursues two goals: A test of highly non-linear integrable optics and a test of optical stochastic cooling. This paper discusses details of OSC arrangements, choice of major parameters of the cooling scheme and incoming experimental tests of the optical amplifier prototype which uses highly doped Ti-sapphire crystal as amplification medium.

physics.acc-ph↗
arXiv2013

PXIE: Project X Injector Experiment

A multi-MW proton facility, Project X has been proposed and is currently under development at Fermilab. As part of this development program, we are constructing a prototype of the front end of the Project X linac at Fermilab. The construction and successful operations of this facility will validate the concept for the Project X front end, thereby minimizing the primary technical risk element within the Project. The Project X Injector Experiment (PXIE) can be constructed over the period FY12-16 and will include an H- ion source, a CW 2.1-MeV RFQ and two SC cryomodules providing up to 30 MeV energy gain at an average beam current of 1 mA. Successful operations of the facility will demonstrate the viability of novel front end technologies that will find applications beyond Project X in the longer term.

physics.acc-ph↗
arXiv2013

PXIE Optics and Layout

The Project X Injector Experiment (PXIE) will serve as a prototype for the Project X front end. The aim is to validate the Project-X design and to decrease technical risks, known to be mainly related to the front end. PXIE will accelerate a 1 mA CW beam to about 25 MeV. It will consist of an ion source, LEBT, CW RFQ, MEBT, two SC cryomodules, a diagnostic section and a beam dump. A bunch-by-bunch chopper located in the MEBT section will allow formation of an arbitrary bunch structure. PXIE deviates somewhat from the current Project-X front end concept in that it provides additional instrumentation and relies on a reduced number of kickers for bunch chopping; the diagnostic section also include an RF separator to allow studying extinction of removed bunches. The paper discusses the main requirements and constraints motivating the facility layout and optics. Final adjustments to the Project X front end design, if needed, will be based on operational experience gained with PXIE.

physics.acc-ph↗
arXiv2013

Fermilab PXIE Beam Diagnostics Development and Testing at the HINS Beam Facility

Fermilab is planning the construction of a prototype front end of the Project X linac. The Project X Injector Experiment (PXIE) is expected to accelerate 1 mA cw H- beam up to 30 MeV. Some of the major goals of the project are to test a cw RFQ and H- source, a broadband bunch-by-bunch beam chopper and a low-energy superconducting linac. The successful characterization and operation of such an accelerator places stringent requirements on beam line diagnostics. These crucial beam measurements include bunch currents, beam orbit, beam phase, bunch length, transverse profile and emittance, beam halo and tails, as well as the extinction performance of the broadband chopper. This paper presents PXIE beam measurement requirements and instrumentation development plans. Also presented are plans to test many of these instruments at the Fermilab High Intensity Neutrino Source (HINS) beam facility. Since HINS is already an operational accelerator, utilizing HINS for instrumentation testing allows for quicker development of the required PXIE diagnostics.

physics.acc-ph↗
arXiv2012

Betatron motion with coupling of horizontal and vertical degrees of freedom

Presently, there are two most frequently used parameterizations of linear x-y coupled motion used in the accelerator physics. They are the Edwards-Teng and Mais-Ripken parameterizations. The article is devoted to an analysis of close relationship between the two representations, thus adding a clarity to their physical meaning. It also discusses the relationship between the Eigen-vectors, the beta-functions, second order moments and the bi-linear form representing the particle ellipsoid in the 4D phase space. Then, it considers a further development of Mais-Ripken parameterization where the particle motion is described by 10 parameters: four beta-functions, four alpha-functions and two betatron phase advances. In comparison with Edwards-Teng parameterization the chosen parameterization has an advantage that it works equally well for analysis of coupled betatron motion in circular accelerators and in transfer lines. Considered relationship between second order moments, Eigen-vectors and beta-functions can be useful in interpreting tracking results and experimental data. As an example, the developed formalism is applied to the FNAL electron cooler and Derbenev's vertex-to-plane adapter.

physics.acc-ph↗
arXiv2012

Search for Heavy Neutrino in K->mu nu_h(nu_h-> nu gamma) Decay at ISTRA+ Setup

Heavy neutrino nu_h with m_h < 300MeV/c^2 can be effectively searched for in kaon decays. We put upper limits on mixing matrix element |U_mu_h}|^2 for radiatively decaying nu_h from K->mu nu_h (nu_h -> nu gamma) decay chain in the following parameter region: 30MeV/c^2 < m_h < 80MeV/c^2; 10^{-11}sec < tau_h < 10^{-9}sec. For the whole region |U_{mu h}|^2 < 5 x 10^{-5} for Majorana type of nu_h and | U_{μh}|^2 < 8 x 10^{-5} for the Dirac case.

hep-ex↗
arXiv2000

Measuring and Controlling the Energy Spread in CEBAF

As compared to electron storage rings, one advantage of recirculating linear accelerators is that the beam properties at target are no longer dominated by the equilibrium between quantum radiative diffusion and radiation damping because new beam is continually injected into the accelerator. This allows the energy spread from a CEBAF-type machine to be relatively small; the measured energy spread from CEBAF at 4 GeV is less than 100 parts per million accumulated over times of order several days. In this paper, the various subsystems contributing to the energy spread of a CEBAF-type accelerator are reviewed, as well as the machine diagnostics and controls that are used in CEBAF to ensure that a small energy spread is provided during routine running. Examples of relevant developments are (1) stable short bunches emerging from the injector, (2) precision timing and phasing of the linacs with respect to the centroid of the beam bunches on all passes, (3) implementing 2 kHz sampling rate feedback systems for final energy stabilization, and (4) continuous beam energy spread monitoring with optical transition radiation devices. We present measurement results showing that small energy spreads are achieved over extended periods.

physics.acc-ph↗