arXiv subjects

G. Kube

Publications and source records attributed to G. Kube.

7 recordsLinked to original sources

arXiv2024

Doppler effect in vacuum and medium in X-ray range

This paper discusses the Doppler effect for radiation emitted by a relativistic oscillator in vacuum described geometrically as an ellipsoid in momentum space. Spectral and angular properties of the Doppler X-ray radiation emitted by a relativistic oscillator moving through a homogeneous medium are considered. Additionally, we show that radiation from an elementary relativistic charged particle interacting with periodic medium can be interpreted as a manifestation of the Doppler effect. Examples include parametric X-ray radiation, coherent bremsstrahlung, undulator radiation in crystalline or vacuum undulators, transition radiation from stacked foils, and Smith-Purcell radiation.

physics.acc-ph↗

arXiv2024

Simulation model of crystal-based beam extraction using BDSim toolkit enhanced with Geant4 G4ChannelingFastSimModel

We present a simulation model for crystal-based beam extraction of lepton beams from an accelerator by using a bent crystal. This model utilizes the BDSim toolkit for particle dynamics in an accelerator in conjunction with the Geant4 G4ChannelingFastSimModel for beam deflection in a bent crystal and G4BaierKatkov for radiation losses. In order to link these codes, we designed a new BDSim accelerator component - a bent crystal compatible with G4ChannelingFastSimModel. As a demonstration, we constructed a complete simulation model of the DESY II Booster Synchrotron within BDSim, incorporating all relevant accelerator components and apertures. The model accounts for betatron and synchrotron oscillations, as well as radiation losses in an oriented crystal, using the Baier-Katkov radiation integral. Simulation results demonstrate the extraction of a primary monoenergetic 6 GeV electron beam, characterized by a charge of 23 pC, a horizontal beam emittance of 3.6 $\mu$m$\cdot$rad, a vertical beam emittance of 0.32 $\mu$m$\cdot$rad, and an energy spread of 0.008. Under the simulated conditions, (1.42 $\pm$ 0.02 %) of the initial circulating beam reaches the septum entrance. This corresponds to an extraction efficiency of (28.1 $\pm$ 0.4 %) when evaluated relative to the particles intercepted by the bent crystal. The approach provides a powerful tool to significantly accelerate R\&D for applications related to crystal-based extraction and collimation in lepton accelerators and colliders.

physics.acc-ph↗

arXiv2024

Frequency splitting in undulator radiation from solid-state crystalline undulator

The set of frequencies and angular properties of radiation emitted from a solid-state crystalline undulator based on the channeling effect are considered. High-frequency and low-frequency branches of the undulator radiation and the angular distribution of the emitted radiation are analyzed. The ranges of frequencies and angles of radiation emitted from the solid-state crystalline undulator based on the channeling effect are found. The frequency splitting and the energy threshold in the production of undulator radiation are shown and discussed.

physics.acc-ph↗

arXiv2022

Surface-barrier detector with smoothly tunable thickness of depleted layer for study of ionization loss and dechanneling length of negatively charged particles channeling in a crystal

A new method for the experimental study of ionization loss of relativistic negatively charged particles moving in a crystal in the channeling regime using a semiconductor surface-barrier detector with smoothly tunable thickness of the depleted layer is proposed. The ionization loss can only be measured in the depleted layer of the detector. The thickness of the depleted layer in a flat semiconductor detector can be smoothly regulated by the value of the bias voltage of the detector. Therefore, the energy distribution of the ionization loss of relativistic particles which cross the detector and move in the channeling regime in the detector crystal can be measured along the path of the particles at variation of the bias voltage of the detector. Ionization loss spectra should be different for channeling and nonchanneling particles, and both fractions can be determined. The application of a Si surface-barrier detector-target is considered. Measurements with such a detector would make it possible to study: the energy distribution of ionization loss of channeling negatively and positively charged particles; spatial distribution of ionization loss as a function of the path length of channeling particles; the dechanneling length of negatively charged particles; and to clear up the role of rechanneling of the particles in the crystal. Comparison of experimental data with calculations can help to develop a description of the dynamics of motion of negatively charged particles channeling in a crystal. A better understanding of the dechanneling length properties can be useful in the production of positrons and other particles such as neutrons by an electron beam in crystals, and in the development of crystalline undulators, and at a crystal-based extraction of electron beams from a synchrotron.

physics.ins-det↗

arXiv2021

First design of a crystal-based extraction of 6 GeV electrons for the DESY II Booster Synchrotron

A proof-of-principle experimental setup for the extraction of 6 GeV electrons from the DESY II Booster Synchrotron using the channeling effect in a bent crystal is elaborated. Various aspects of the experimental setup were investigated in detail, such as the particle beam dynamics during the extraction process, the manufacturing and characterization of bent crystals, and the detection of the extracted beam. In order to optimize the crystal geometry, the overall process of beam extraction was simulated, taking into account the influence of radiation energy losses. As result it is concluded that the multi-turn electron beam extraction efficiency can reach up to 16 %. In principle this crystal-based beam extraction technique can be applied at any electron synchrotron in order to provide multi-GeV electron beams in a parasitic mode. This technique will allow to supply fixed-target experiments by intense high-quality monoenergetic electron beams. Furthermore, electron/positron crystal-based extraction from future lepton colliders may provide an access to unique experimental conditions for ultra-high energy fixed-target experiments including searches for new physics beyond the Standard Model.

physics.acc-ph↗

arXiv2018

Direct Measurement of Focusing Fields in Active Plasma Lenses

Active plasma lenses have the potential to enable broad-ranging applications of plasma-based accelerators owing to their compact design and radially symmetric kT/m-level focusing fields, facilitating beam-quality preservation and compact beam transport. We report on the direct measurement of magnetic field gradients in active plasma lenses and demonstrate their impact on the emittance of a charged particle beam. This is made possible by the use of a well-characterized electron beam with 1.4 mm mrad normalized emittance from a conventional accelerator. Field gradients of up to 823 T/m are investigated. The observed emittance evolution is supported by numerical simulations, which suggest the potential for conservation of the core beam emittance in such a plasma lens setup.

physics.acc-ph↗

arXiv2000

The RF-System of the New Gsi High Current Linac Hsithe RF-System of the New Gsi High Current Linac Hsi

The RF part of the new high current injector-linac HSI consists of five cavities with the new operating frequency of 36 MHz instead of 27 MHz of the removed Wideroe type injector. The calculated power requirements of the cavities including beam load in three structures were between 110 kW for a rebuncher and 1.75 MW pulse-power for the two IH-cavities. The beam load is up to 150 kW for the RFQ and up to 750 kW for the two drift tube tanks. An additional 36 MHz debuncher in the transfer line to the Synchrotron (SIS) will need 120 kW pulse power. We decided to fulfil these demands with amplifiers of only two power classes, namely three amplifiers with 2 MW and six amplifiers with 200 kW pulse output power. The latter ones are also used as drivers for the 2 MW stages. The 200 kW amplifiers were specified in detail by GSI and ordered in the industry. The three 2 MW final amplifiers were designed, constructed and built by GSI. The paper gives an overview of the complete RF system and the operating performance of amplitude and phase control with beam load. It further describes some specialities of the new 2 MW amplifiers like the simplicity of the anode circuit, a very sophisticated socket for a cathode driven amplifier with cathode on dc ground, the parasitic mode-suppression, shielding and filtering of unallowable RF-radiation and operating experience since October 1999.

physics.acc-ph↗