An intense positron sources is a demanding element in the design of future lepton colliders. A crystal-based hybrid positron source could be an alternative to a more conventional scheme based on the ...electron conversion into positron in a thick amorphous target. The conceptual idea of the hybrid source is to have two separate objects, a photon radiator and a photon-to-positron converter target. In such a scheme an electron beam crosses a thin axially oriented crystal with the emission of a channeling radiation, characterized by a considerably larger amount of photons if compared to Bremsstrahlung. The net result is an increase in the number of produced positrons at the converter target. In this paper we present the results of a beam test conducted at the DESY TB 21 with 5.6 GeV electron beam and a crystalline tungsten radiator. Experimental data clearly highlight an increased production of photons and they are critically compared with the outcomes of novel method to simulate the number of radiated photons, showing a very good agreement. Strong of this, the developed simulation tool has been exploited to design a simple scheme for a positron source based on oriented crystal, demonstrating the advantages in terms of reduction of both deposited energy and the peak energy deposition density if compared to conventional sources. The presented work opens the way for a realistic and detailed design of a hybrid crystal-based positron source for future lepton colliders.
Commissioning of the ThomX Storage Ring Kubytskyi, V.; Chaikovska, I.; Delerue, N. ...
Journal of physics. Conference series,
01/2024, Letnik:
2687, Številka:
3
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
Abstract
We will report on the ongoing ThomX ring commissioning, its status, its main challenges, our results and our planning. ThomX is a compact Compton-based X-ray source under commissioning at ...IJCLab in Orsay (France). This facility is composed of a 50-70 MeV linac, a transfer line and a storage ring whose circumference is 18 m. Compton scattering between the 50 MeV electron bunch of 1 nC and the 30 mJ laser pulses stacked in a Fabry-Perot cavity will result in the production of X-rays with energy ranging between 45 keV and 90 keV. We aim at a total flux of about 10
13
X-rays per second. The injector commissioning started in the spring of 2021. The ongoing storage ring commissioning faces many challenges due to the rings low energy, its compactness, its non-linear beam dynamics, the time-limited beam storage and the need to achieve a very accurate and stable geometry of the collision region between the laser pulses and the electron bunch. The commissioning and operational experience is of great importance for the future Compton sources.
Optimized injector schemes for FCC-ee positron production Bai, B.; Faus-Golfe, A.; Han, Y. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2021, Letnik:
1009
Journal Article
Recenzirano
Odprti dostop
Injectors and in particular the positron production systems are a crucial element in linear and circular colliders. The proposed FCC-ee injector linac accelerates both electrons and positrons up to 6 ...GeV in order to be injected into the Pre-Booster Ring (PBR) with a high intensity of 3.5 nC per bunch for the Z running mode. The current design baseline of the FCC-ee injector linac is based on the SuperKEKB scheme, in which the electron and the positron beams share the same linacs with a fixed target configuration on-axis hole for electron beam passage. One of the main drawbacks of this scheme is the positron production efficiency at the exit of the injector linac. In order to achieve a better performance and a higher positron yield, in this paper we study different bypass injection options. Start-to-end design and optimization for beam production, acceleration and transport from the feeding electron source to the positron damping ring are also being presented.
In this article the Campbell's theorem is used to evaluate the equilibrium emittance and energy spread in a Compton ring. This method allows us to have an efficient analytical approach separating the ...contributions of the Compton cross section from the luminosity factor. The consequent advantage is given by the possibility to have an easy extrapolation for the "nonclassical" cases like the polarized Compton backscattering or the evaluation of the equilibrium given by different radiation mechanisms. The effects accounting for the polarized Compton backscattering in the article are evaluated numerically. The analytical results in the nonpolarized case and in the negligible recoil effect approximation are in excellent agreement with the values obtained by matching the Compton damping rate with the quantum fluctuations, and they show that the equilibrium energy spread and emittance are independent from the luminosity.
Classical and quantum properties of scattering of ultrarelativistic electrons in ultrathin crystals are considered. A comparison is made of these two ways of study of scattering process. In classical ...consideration we remark the appearance of sharp peaks in angular distribution of scattered particles, that is treated as a manifestation of the rainbow scattering phenomenon, and in quantum case we show sharp peaks in the angular distribution that arise from the interference of single electrons on numerous crystal planes and can be expressed in terms of reciprocal lattice vectors. We show that for some parameters the quantum predictions substantially differ from the classical ones. The influence of beam divergence on the possibility of experimental observation of the studied effects is estimated.
The Future Circular e + e − Collider pre-injector chain consists of a 6 GeV S-Band linac, a damping ring at 1.54 GeV and pre-booster ring to reach 20 GeV for injection to the main booster. The ...electron and positron beams use the same accelerator chain alternatively. The e −beam is generated from a novel low level RF-gun providing 6.5 nC charge at 11 MeV with 0.5 micron geometric emittance. The e + beam is produced by the impact of a 4.46 GeV e − beam onto a hybrid target, accelerated in the linac up to 1.54 GeV, and injected to the damping ring for emittance cooling. Simulations on the performance of the DR are presented for reaching the required equilibrium emittances at the required damping time. As an alternative option, a 20 GeV linac is considered utilising C-Band cavities and simulations studies have been undertaken regarding the beam transport and transmission efficiency up to that energy.
Optimization of an hybrid positron source using channeling Chaikovska, I.; Chehab, R.; Guler, H. ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
07/2017, Letnik:
402
Journal Article
Recenzirano
The hybrid positron source made of a crystal-radiator, as a source of channeling radiation, and an amorphous converter is briefly described. Optimization of the heating effects and thermal shocks led ...to a granular converter made of small tungsten spheres. Simulation results with application to two linear collider projects CLIC and ILC are presented. A test operated with this kind of source at KEK is described and the results gathered last year, reported. Plans for the future are briefly described.
Gamma ray sources with high flux and spectral densities are the main requirements for new nuclear physics experiments to be performed in several worldwide laboratories with dedicated facilities. The ...paper is focalized on a proposal of experiment on Formula Omitted photons production using Compton collisions between the Formula Omitted electron beam and a high average power laser pulse, amplified in a Fabry-Pérot optical resonator. The calculations show that the resulting Formula Omitted beam source has extremely interesting properties in terms of spectral density, energy spread and Formula Omitted flux comparable (and even better) with the last generation Formula Omitted sources. The energy of the Formula Omitted beam depends on the adopted laser wavelength and can be tuned changing the energy of the electron ring. In particular we have analyzed the case of a Formula Omitted factory tunable in the 2-9 MeV range. The main parameters of this new facility are presented and the perturbation on the transverse and longitudinal electron beam dynamics is discussed. A preliminary accelerator layout to allow experiments with the Formula Omitted beam is presented with a first design of the accelerator optics.
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