arXiv subjects

Andriy Ushakov

Publications and source records attributed to Andriy Ushakov.

15 recordsLinked to original sources

arXiv2026

KIND: A Kalman-Inspired Adaptive Estimator for SRF Cavity Detuning

Superconducting radio frequency cavities with a high quality factor enable energy-efficient accelerator operation but are very sensitive to mechanical disturbances that detune their resonance. Accurate detuning estimation is therefore essential for efficient resonance control and stable beam conditions. This paper introduces Kalman-Inspired Neural Decomposition (KIND), a data-driven estimator that fuses a Dynamic Mode Decomposition model for stationary modal behavior with a Transformer-based predictor for transient dynamics. KIND further outputs learned uncertainty signals that indicate regime changes, enabling anomaly detection. Using operational cavity data, we compare KIND with a classical Kalman filtering baseline and discuss its potential as a foundation for future uncertainty-aware, forecast-based control.

eess.SY↗

arXiv2024

Characterization and optimization of polarized and unpolarized positron production

The electron induced production of positrons is a multi-parameter problem which combines elementary physics processes with complex collection systems. The optimization of this technique for 120~MeV and 1000~MeV electron beam kinetic energies is here discussed considering a tungsten target. A strong correlation between the optimum target thickness and the angular acceptance ($\Delta \theta$) of the collection system is observed, as well as sizeable differences between the optimum unpolarized and polarized operational modes. These also extend to the positron momentum and the positron polarization at the optimum, as well as the benefit of high electron beam energies for a high duty cycle positron source.

physics.acc-ph↗

arXiv2021

Photon Masks for the ILC Positron Source with 175 and 250 GeV Electron Drive Beam

In the future the International Linear Collider (ILC), a helical undulator-based polarized positron source, is expected to be chosen. A high energy electron beam passes through a superconducting helical undulator in order to create circularly polarized photons which will be directed to a conversion target, resulting in electron-positron pairs. The resulting positron beam is longitudinally polarized. Since the photons are produced with an opening angle and pass through a long superconducting helical undulator, some of these photons will strike the undulator walls. Therefore photon masks must be placed along the undulator line in order to keep the power deposited in the undulator walls below the acceptable limit of 1W/m. The baseline design of the ILC is focused on 250 GeV center-of-mass energy and upgrade to center-of-mass energies of 350 and 500 GeV is foreseen. This paper shows a detailed study of the ideal power deposited along the masks for both 350 and 500 GeV center-of-mass energies.

physics.acc-ph↗

arXiv2020

Plasma Lenses: Possible alternative OMD at the ILC

In the baseline design of the International Linear Collider (ILC) an undulator-based source is foreseen for the positron source in order to match the physics requirements. The recently chosen first energy stage with sqrt(s)=250 GeV requires high luminosity and imposes an effort for all positron source designs at high-energy colliders. In this paper we perform a simulation study and adopt the new technology of plasma lenses to capture the positrons generated by the undulator photons and to create the required high luminosity positron beam.

physics.acc-ph↗

arXiv2020

Updated status of the undulator-based ILC positron source

The design of the positron source for the International Linear Collider (ILC) is still under discussion. The baseline design plans to use the high-energy electron beam for the positron production before it goes to the IP. The electrons pass a long helical undulator and generate an intense circularly polarized photon beam which hits a thin conversion target to produce $e^+e^-$ pairs. The resulting positron beam is longitudinally polarized which provides an important benefit for precision physics analyses at the ILC. In this paper the status of the positron target design studies is presented. Focus is the positron yield for center-of-mass energies of 250 GeV and also the Z peak. Possibilities to improve the positron collection system and thus to increase the positron yield are discussed.

physics.acc-ph↗

arXiv2020

Energy Deposition due to Secondary Particles in The Helical Undulator Wall at ILC-250GeV

In the future, International Linear Collider (ILC), a helical undulator based polarized positron source is expected to be chosen. A high energy electron beam passes through a superconducting helical undulator in order to create circularly polarized photons which will be directed to a conversion target, the result of which, will be electron-positron pairs. The resulting positron beam is longitudinally polarized. In order to produce the required number of positrons in ILC250 the full undulator length is needed. Since the photons are created with an opening angle and traveling through a 320 m long undulator, it is expected that the superconducting undulator vacuum will be hit by the photons. Photon masks are needed to be inserted in the undulator line to keep the power deposition in the vacuum below the acceptable limit which is 1W/m. A detailed study of the power deposition in the vacuum and masks is needed in order to design the photon masks. This paper describes the power deposition in the undulator vacuum due to secondary particles assuming an ideal undulator. In addition, the mask model is proposed.

physics.acc-ph↗

arXiv2019

Status of the undulator-based ILC positron source

The design of the positron source for the International Linear Collider (ILC) is still under consideration. The baseline design plans to use the electron beam for the positron production before it goes to the IP. The high-energy electrons pass a long helical undulator and generate an intense circularly polarized photon beam which hits a thin conversion target to produce $e^+e^-$ pairs. The resulting positron beam is longitudinally polarized which provides an important benefit for precision physics analyses. In this paper the status of the design studies is presented with focus on ILC250. In particular, the target design and cooling as well as issues of the optical matching device are important for the positron yield. Some possibilities to optimize the system are discussed.

physics.acc-ph↗

arXiv2019

Optimization of Undulator Parameters for 125 GeV Drive Beam

In the baseline design of the International Linear Collider (ILC) an undulator-based source is foreseen for the positron source in order to match the physics requirements. The baseline parameters are optimized for the ILC at sqrt(s)=500 GeV, that means an electron drive beam of 250 GeV. Precision measurements in the Higgs sector, however, require measurements at sqrt(s)=250 GeV, i.e. running with the electron drive beam only at 125 GeV, which imposes a challenge for achieving a high yield. Therefore the baseline undulator parameters have to be optimized as much as possible within their technical performances. In this bachelor thesis we therefore present a theoretical study on the radiation spectra of a helical undulator, based on the equation for the radiated synchrotron energy spectral density per solid angle per electron in the relativistic, far-field and point-like charge approximation. From this starting point the following undulator properties are examined: the deposited power in the undulator vessel, which can disrupt the functionality of the undulator magnets, the protective property of a mask on this disturbances and the number of positrons produced by the synchrotron radiation in a Ti6Al4V target. Those quantities were evaluated for various values for parameters as undulator period, undulator length and magnetic flux in order to find optimal baseline parameter sets for sqrt(s)=250 GeV.

physics.acc-ph↗

arXiv2018

The ILC positron target cooled by thermal radiation

The design of the conversion target for the undulator-based ILC positron source is still under development. One important issue is the cooling of the target. Here, the status of the design studies for cooling by thermal radiation is presented.

physics.acc-ph↗

arXiv2018

Undulator-Based Positron Source at 250 GeV CM Energy with Different Optical Matching Devices: Pulsed Flux Concentrator and Quarter Wave Transformer

In the baseline design of the International Linear Collider (ILC) an undulator-based source is foreseen for the positron source. In this study the energy deposition in the pulsed flux concentrator (FC) of positron source is calculated for the ILC at 250 GeV center-of-mass energy. The peak energy of 33 J/g deposited by one beam pulse in the current design of the FC is above the limit for copper material. Several promising options were considered to solve the issue of overheating the FC: the quarter wave transformer (QWT) has a significantly bigger aperture and is considered as an valuable and safe alternative for the FC. Since the positron source with a QWT is expected to lead to a lower positron capture efficiency, also the expected positron yield was calculated in addition to the energy deposition in QWT.

physics.acc-ph↗

arXiv2013

Positron Source Simulations for ILC 1 TeV Upgrade

The generation and capture of polarized positrons at a source with a superconducting helical undulator having 4.3 cm period and 500 GeV electron drive beam have been simulated. The positron polarization has been calculated for the different undulator K values (up to K = 2.5). Without applying a photon collimator, the maximal polarization of positrons is about 25% for 231 meters active magnet length of undulator with K = 0.7. Using an undulator with K = 2.5 and a collimator with an aperture radius of 0.9 mm results in increase of positron polarization to 54%. The energy deposition, temperature rise and stress induced by high intense photon beam in the rotated titanium-alloy target have been estimated. The maximal thermal stress in the target is about 224 MPa for the source with photon collimation to achieve a positron polarization of 54%.

physics.acc-ph↗

arXiv2012

Depolarization in the ILC Linac-to-Ring Positron Beamline

To achieve the physics goals of future Linear Colliders, it is important that electron and positron beams are polarized. The positron source planned for the International Linear Collider (ILC) is based on a helical undulator system and can deliver a polarised beam with positron polarization of 60%. To ensure that no significant polarization is lost during the transport of the electron and positron beams from the source to the interaction region, spin tracking has to be included in all transport elements which can contribute to a loss of polarization. These are the positron source, the damping ring, the spin rotators, the main linac and the beam delivery system. In particular, the dynamics of the polarized positron beam is required to be investigated. The results of positron spin tracking and depolarization study at the Positron-Linac-To-Ring (PLTR) beamline are presented.

physics.acc-ph↗

arXiv2011

A conventional positron source for International Linear Collider

A possible solution to realize a conventional positron source driven by a several-GeV electron beam for the International Linear Collider is proposed. A 300 Hz electron linac is employed to create positrons with stretching pulse length in order to cure target thermal load. ILC requires about 2600 bunches in a train which pulse length is 1 ms. Each pulse of the 300 Hz linac creates about 130 bunches, then 2600 bunches are created in 63 ms. Optimized parameters such as drive beam energy, beam size, and target thickness, are discussed assuming a L-band capture system to maximize the capture efficiency and to mitigate the target thermal load. A slow rotating tungsten disk is employed as positron generation target.

physics.acc-ph↗

arXiv2009

Frequency of Positron Helicity Reversal

The ILC baseline design for the positron source is based on a helical undulator and will deliver a positron beam with a polarization of 30% or more. In this contribution the need for fast reversal of the positron helicity is discussed.

physics.ins-det↗

arXiv2007

Radiation damage of the ILC positron source target

The radiation damage of the positron source target for the International Linear Collider (ILC) has been studied. The displacement damage in target material due to multi-MeV photons has been calculated by combining FLUKA simulations for secondary particle production, SPECTER data for neutron displacement cross-sections and the Lindhard model for estimations of displacement damage by ions. The radiation damage of a stationary Ti6Al4V target in units of displacements per atom (dpa) has been estimated for photons from an undulator with strength 0.92 and period 1.15 cm. The calculated damage is 7 dpa. Approximately 12.5% of displacement damage result from neutrons.

physics.acc-ph↗