arXiv subjects

E. Adli

Publications and source records attributed to E. Adli.

At least 19 recordsLinked to original sources

arXiv2026

Report on the Advanced Linear Collider Study Group (ALEGRO) Workshop 2026

The 7th ALEGRO workshop, hosted by INFN Frascati National Laboratories from 3rd to 5th March 2026, brought together the international Advanced Novel Accelerators (ANA) community to discuss the role of advanced wakefield accelerators (AWA) in particle and high-energy physics. Organized under the ICFA-ANA panel, the workshop highlighted recent progress in plasma- and structure-based wakefield acceleration and strengthened international collaboration toward future energy-frontier colliders. A major focus was the ongoing 10 TeV linear collider design study, launched in 2025 following the US P5 recommendations. A dedicated session covered accelerator concepts, enabling technologies, and the associated physics case, while recognizing that future priorities will depend on the outcome of the European Strategy for Particle Physics Update. The workshop also reviewed nearer-term applications of advanced accelerators, including fixed-target experiments, injectors for future colliders and light sources, plasma-based Higgs factory concepts, and proton-driven plasma wakefield acceleration. Beyond high-energy physics, sessions covered free-electron lasers, synchrotron light sources, and strong-field QED. Recent demonstrations of FEL lasing with plasma-accelerated electron beams highlighted significant progress in beam quality and accelerator performance. Operational challenges for reliable user facilities, including high-availability laser and electron-beam systems, were discussed alongside the growing role of artificial intelligence and machine learning for accelerator optimization and control. This report summarizes the workshop discussions and conclusions from the chairs, together with short contributions from the presenters, providing an overview of the current status and future prospects of advanced wakefield accelerators.

physics.acc-ph↗

arXiv2026

Achromatic optics using nonlinear plasma lenses for beam-quality preservation between plasma-accelerator stages

Plasma acceleration promises to deliver high-energy particle beams by combining, or staging, several low- or medium-energy accelerator stages. However, chromatic aberrations from the combination of high divergence and energy spread make it nontrivial to transport beams between plasma-accelerator stages. This paper describes a compact and achromatic lattice optimized for staging, based on a new beam-optics element; a nonlinear plasma lens. The lattice preserves emittance for energy spreads up to several percent and has a tunable $R_{56}$ that enables bunch-length preservation or a longitudinal self-correction mechanism. The performance and limitations of the plasma-lens-based solution are modeled analytically and numerically, and compared to a more conventional yet novel solution based on quadrupole and sextupole magnets. While functional, the latter is double the length, has about twice the number of elements and a narrower energy bandwidth. Lastly, a solution for scaling to TeV energies is described, in which all lengths scale with the square root of the energy and the deleterious effects of coherent and incoherent synchrotron radiation are mitigated.

physics.acc-ph↗

arXiv2026

First results from the E302 efficiency$\unicode{x2013}$instability experiment at the FACET-II facility

The beam-breakup (BBU) instability in plasma accelerators is seeded by a transverse offset between the driver and a trailing bunch. The BBU instability induces oscillations in the trailing bunch, which are detrimental to its beam quality. When the instability is large, assuming little mitigation from ion motion and energy spread, the beam suffers emittance growth, and charge can be kicked transversely out of the plasma channel. The detrimental effect on beam quality is substantially worse at high efficiencies, which places constraints on the achievable power efficiency in applications such as linear colliders, where maintaining the beam quality is required. In this paper, we present the first experimental signatures of the BBU instability in data taken in the E302 experiment at the FACET-II facility at SLAC National Accelerator Laboratory. We use a specific beam-optical setup and a novel method to probe for transverse instabilities on diagnostic screens downstream of a magnetic dipole spectrometer. We complement the analysis with full 3D particle-in-cell (PIC) simulations of the plasma interaction using similar driver and trailing bunch parameters on a simulated FACET-II spectrometer.

physics.acc-ph↗

arXiv2026

Driver-delay chicanes for a multistage plasma-based accelerator facility

The SPARTA project aims to design a medium-sized accelerator facility that facilitates new experiments in strong-field quantum electrodynamics using plasma-based accelerators. For this, we need several plasma stages and, therefore, several drivers. Drivers can be either an ultra-relativistic charged particle beam or a high-intensity laser beam. In case we use particle beams, we need a method of distributing these beams from a radio-frequency accelerator to the different plasma stages. A central part of this is a delay scheme that ensures temporal synchronization of the drivers. In this paper, we demonstrate how to achieve a 2 ns delay in $\sim$12 m, while keeping the first-order beam parameters periodic.

physics.acc-ph↗

arXiv2025

The Linear Collider Facility (LCF) at CERN

In this paper we outline a proposal for a Linear Collider Facility as the next flagship project for CERN. It offers the opportunity for a timely, cost-effective and staged construction of a new collider that will be able to comprehensively map the Higgs boson's properties, including the Higgs field potential, thanks to a large span in centre-of-mass energies and polarised beams. A comprehensive programme to study the Higgs boson and its closest relatives with high precision requires data at centre-of-mass energies from the Z pole to at least 1 TeV. It should include measurements of the Higgs boson in both major production mechanisms, ee -> ZH and ee -> vvH, precision measurements of gauge boson interactions as well as of the W boson, Higgs boson and top-quark masses, measurement of the top-quark Yukawa coupling through ee ->ttH, measurement of the Higgs boson self-coupling through HH production, and precision measurements of the electroweak couplings of the top quark. In addition, ee collisions offer discovery potential for new particles complementary to HL-LHC.

hep-ex↗

arXiv2025

ABEL: The Adaptable Beginning-to-End Linac simulation framework

We introduce ABEL, the Adaptable Beginning-to-End Linac simulation framework developed for agile design studies of plasma-based accelerators and colliders. ABEL's modular architecture allows users to simulate particle acceleration across various beamline components. The framework supports specialised codes such as HiPACE++, Wake-T, ELEGANT, GUINEA-PIG, CLICopti and ImpactX, which facilitate precise modelling of complex machine components. Key features include simplified models for addressing transverse instabilities, radiation reactions, and ion motion, alongside comprehensive diagnostics and optimisation capabilities. Our simulation studies focus on the HALHF plasma linac, examining tolerances for drive beam jitter, including effects of self-correction mechanisms. Simulation results demonstrate ABEL's ability to model emittance growth due to transverse instability and ion motion, highlighting the framework's adaptability in balancing simulation fidelity with computational efficiency. The findings point towards ABEL's potential for advancing compact accelerator designs and contribute to the broader goals of enhancing control and precision in plasma-based acceleration.

physics.acc-ph↗

arXiv2025

Updated baseline design for HALHF: the hybrid, asymmetric, linear Higgs factory

Particle physicists aim to construct a electron-positron Higgs factory as the next major particle collider. However, the high associated costs motivate the development of more affordable collider designs. Plasma-wakefield acceleration is a promising technology to this end. HALHF is a proposal for a Higgs factory that utilizes beam-driven plasma-wakefield acceleration to accelerate electrons to high energy with high gradient, while using radio-frequency acceleration to accelerate positrons to a lower energy. This asymmetry sidesteps a major difficulty in plasma acceleration: that of accelerating positrons with high efficiency and quality. Since publication, several challenges were identified in the original baseline design. We summarize the updated baseline design, which addresses these challenges, and describe the parameter- and cost-optimization process used to arrive at this design.

physics.acc-ph↗

arXiv2025

Preliminary results from the CLEAR nonlinear plasma lens experiment

Plasma lensing provides compact focusing of electron beams, since they offer strong focusing fields (kT/m) in both planes simultaneously. This becomes particularly important for highly diverging beams with a large energy spread such as those typically originating from plasma accelerators. The lens presented here is a nonlinear active plasma lens, with a controlled focusing-strength variation purposely introduced in one transverse direction. This lens is a key element of a larger transport lattice, core of the ERC project SPARTA, which aims to provide a solution for achromatic transport between plasma-accelerator stages. We report on preliminary experimental results from the CLEAR facility at CERN, which aims to probe the magnetic field structure of the lens using an electron beam, in search of the desired nonlinearity, together with 2D plasma simulation results.

physics.acc-ph↗

arXiv2025

Parametric mapping of the efficiency$\unicode{x2013}$instability relation in plasma-wakefield accelerators

High efficiency is essential for plasma-wakefield accelerators to be a cost-effective alternative in high-power applications, such as a linear collider. However, in a plasma-wakefield accelerator the beam-breakup instability can be seeded by a transverse offset between the driver and trailing bunch. This instability, which rapidly increases the oscillation amplitude of the trailing bunch, grows with higher power-transfer efficiency from the driver to the trailing bunch [V. Lebedev et al., Phys. Rev. Accel. Beams 21, 059901 (2018)]. In this paper, we use particle-in-cell simulations to investigate the efficiency$\unicode{x2013}$instability relation that constrains the driver-to-trailing-bunch power-transfer efficiency in beam-driven plasma accelerators. We test the relation using a grid of simulations across all parameters that affect the beam-breakup instability, assuming a uniform accelerating field (optimal beam loading) and no ion motion. We find that the previously proposed efficiency$\unicode{x2013}$instability relation represents a lower limit on the strength of the instability for a given efficiency. For each normalized wake radius, only a certain accelerating field reaches this lowest value of the transverse instability; deviating from this point can increase the growth rate by several orders of magnitude. Lastly, we highlight how the oscillation-amplitude growth of the trailing bunch can be reduced or damped with an initial uncorrelated energy spread and the presence of ion motion.

physics.acc-ph↗

arXiv2025

The SPARTA project: toward a demonstrator facility for multistage plasma acceleration

Plasma accelerators promise greatly reduced size and cost for future particle-accelerator facilities. However, several challenges remain to be solved; in particular that of coupling beams between plasma stages (i.e., staging) without beam-quality degradation, and that of ensuring a stable acceleration process. In order to mature the technology, it is also key to identify an application that requires staging and high stability but is not overly challenging in other parameters such as energy efficiency, beam quality and repetition rate. The goal of the ERC-funded project SPARTA is to solve the staging and stability problems of plasma acceleration, and to combine the solutions into a medium-scale multistage plasma-accelerator facility for such an application: experiments in strong-field quantum electrodynamics. Here, we discuss the three main objectives of the SPARTA project: developing a nonlinear plasma lens for staging, developing self-stabilization mechanisms, and providing a conceptual design for a multistage demonstrator facility.

physics.acc-ph↗

arXiv2025

Development of an achromatic spectrometer for a laser-wakefield-accelerator experiment

The large gradients of plasma-wakefield accelerators promise to shorten accelerators and reduce their financial and environmental costs. For such accelerators, a key challenge is the transport of beams with high divergence and energy spread. Achromatic optics is a potential solution that would allow staging of plasma accelerators without beam-quality degradation. For this, a nonlinear plasma lens is being developed within the SPARTA project. As a first application of this lens, we aim to implement an achromatic spectrometer for electron bunches produced by a laser-wakefield accelerator. This will greatly improve the resolution across the typically one to tens of percent energy spread bunches and therefore help diagnosis and optimization of the plasma interaction. We report on progress in designing such an experiment.

physics.acc-ph↗

arXiv2025

A Linear Collider Vision for the Future of Particle Physics

In this paper we review the physics opportunities at linear $e^+e^-$ colliders with a special focus on high centre-of-mass energies and beam polarisation, take a fresh look at the various accelerator technologies available or under development and, for the first time, discuss how a facility first equipped with a technology mature today could be upgraded with technologies of tomorrow to reach much higher energies and/or luminosities. In addition, we will discuss detectors and alternative collider modes, as well as opportunities for beyond-collider experiments and R\&D facilities as part of a linear collider facility (LCF). The material of this paper will support all plans for $e^+e^-$ linear colliders and additional opportunities they offer, independently of technology choice or proposed site, as well as R\&D for advanced accelerator technologies. This joint perspective on the physics goals, early technologies and upgrade strategies has been developed by the LCVision team based on an initial discussion at LCWS2024 in Tokyo and a follow-up at the LCVision Community Event at CERN in January 2025. It heavily builds on decades of achievements of the global linear collider community, in particular in the context of CLIC and ILC.

hep-ex↗

arXiv2024

Development of a nonlinear plasma lens for achromatic beam transport

We introduce the new idea of a nonlinear active plasma lens, as part of a larger transport lattice for achromatic electron beam transport. The proposed implementation is based on using the Hall effect in a plasma and is motivated by 1D-hydrodynamic simulations. The manufactured design is presented, including its undergoing experimental characterisation on the CLEAR beam-line at CERN.

physics.acc-ph↗

arXiv2024

Positron Acceleration in Plasma Wakefields

Plasma acceleration has emerged as a promising technology for future particle accelerators, particularly linear colliders. Significant progress has been made in recent decades toward high-efficiency and high-quality acceleration of electrons in plasmas. However, this progress does not generalize to acceleration of positrons, as plasmas are inherently charge asymmetric. Here, we present a comprehensive review of historical and current efforts to accelerate positrons using plasma wakefields. Proposed schemes that aim to increase the energy efficiency and beam quality are summarised and quantitatively compared. A dimensionless metric that scales with the luminosity-per-beam power is introduced, indicating that positron-acceleration schemes are currently below the ultimate requirement for colliders. The primary issue is electron motion; the high mobility of plasma electrons compared to plasma ions, which leads to non-uniform accelerating and focusing fields that degrade the beam quality of the positron bunch, particularly for high efficiency acceleration. Finally, we discuss possible mitigation strategies and directions for future research.

physics.acc-ph↗

arXiv2024

The E302 instability-versus-efficiency experiment at FACET-II

We discuss plans for the E302 instability-efficiency experiment, starting in 2024 at the recently upgraded FACET-II facility at SLAC National Accelerator Laboratory. The beam-breakup instability will be the main area of study for the E302 experiment. With the imaging spectrometer at FACET-II, we introduce a novel technique for observing and quantifying the amplitude growth of the trailing bunch due to the transverse instability. Using the transverse position on the spectrometer screen and the transfer matrix of the magnetic lattice used for the spectrometer, we aim to extract a $x'$-$E$ charge distribution that can be used to quantify the amplitude of the beam. By varying the trailing bunch's charge and, hence, the beam loading of the accelerating field, we aim to adjust the wake-to-beam power transfer efficiency in the E302 experiment. We plan to quantify the amplitude for different configurations of the beam charge and, hence, investigate the relationship between the beam-breakup instability and efficiency. We use a combination of particle-in-cell (PIC) codes to simulate a beam-driven plasma wakefield accelerator from start-to-end with a FACET-II-like spectrometer and demonstrate the methodology that will be used for the instability studies at the E302 experiment.

physics.acc-ph↗

arXiv2023

Wakefield Generation in Hydrogen and Lithium Plasmas at FACET-II: Diagnostics and First Beam-Plasma Interaction Results

Plasma Wakefield Acceleration (PWFA) provides ultrahigh acceleration gradients of 10s of GeV/m, providing a novel path towards efficient, compact, TeV-scale linear colliders and high brightness free electron lasers. Critical to the success of these applications is demonstrating simultaneously high gradient acceleration, high energy transfer efficiency, and preservation of emittance, charge, and energy spread. Experiments at the FACET-II National User Facility at SLAC National Accelerator Laboratory aim to achieve all of these milestones in a single stage plasma wakefield accelerator, providing a 10 GeV energy gain in a <1 m plasma with high energy transfer efficiency. Such a demonstration depends critically on diagnostics able to measure emittance with mm-mrad accuracy, energy spectra to determine both %-level energy spread and broadband energy gain and loss, incoming longitudinal phase space, and matching dynamics. This paper discusses the experimental setup at FACET-II, including the incoming beam parameters from the FACET-II linac, plasma sources, and diagnostics developed to meet this challenge. Initial progress on the generation of beam ionized wakes in meter-scale hydrogen gas is discussed, as well as commissioning of the plasma sources and diagnostics.

physics.acc-ph↗

arXiv2023

Generation of meter-scale hydrogen plasmas and efficient, pump-depletion-limited wakefield excitation using 10 GeV electron bunches

High repetition rates and efficient energy transfer to the accelerating beam are important for a future linear collider based on the beam-driven plasma wakefield acceleration scheme (PWFA-LC). This paper reports the first results from the Plasma Wakefield Acceleration Collaboration (E300) that are beginning to address both of these issues using the recently commissioned FACET-II facility at SLAC. We have generated meter-scale hydrogen plasmas using time-structured 10 GeV electron bunches from FACET-II, which hold the promise of dramatically increasing the repetition rate of PWFA by rapidly replenishing the gas between each shot compared to the hitherto used lithium plasmas that operate at 1-10 Hz. Furthermore, we have excited wakes in such plasmas that are suitable for high gradient particle acceleration with high drive-bunch to wake energy transfer efficiency -- a first step in achieving a high overall energy transfer efficiency. We have done this by using time-structured electron drive bunches that typically have one or more ultra-high current (>30 kA) femtosecond spike(s) superimposed on a longer (~0.4 ps) lower current (<10 kA) bunch structure. The first spike effectively field-ionizes the gas and produces a meter-scale (30-160 cm) plasma, whereas the subsequent beam charge creates a wake. The length and amplitude of the wake depends on the longitudinal current profile of the bunch and plasma density. We find that the onset of pump depletion, when some of the drive beam electrons are nearly fully depleted of their energy, occurs for hydrogen pressure >1.5 Torr. We also show that some electrons in the rear of the bunch can gain several GeV energies from the wake. These results are reproduced by particle-in-cell simulations using the QPAD code. At a pressure of ~2 Torr, simulations results and experimental data show that the beam transfers about 60% of its energy to the wake.

physics.acc-ph↗

arXiv2021

Witness electron beam injection using an active plasma lens for a proton beam-driven plasma wakefield accelerator

An active plasma lens focuses the beam in both the horizontal and vertical planes simultaneously using a magnetic field generated by a discharge current through the plasma. A beam size of 5--10 $μ$m can be achieved within a short distance using a focusing gradient on the order of 100 T/m. The active plasma lens is therefore an attractive element for plasma wakefield acceleration, because an ultra-small size of the witness electron beam is required for injection into the plasma wakefield to minimize emittance growth and to enhance the capturing efficiency. When the drive beam and witness electron beam co-propagate through the active plasma lens, interactions between the drive and witness beams, and the plasma must be considered. In this paper, through particle-in-cell simulations, we discuss the possibility of using an active plasma lens for the final focusing of the electron beam for the AWAKE RUN 2 experiments. It is confirmed that the amplitude of the plasma wakefield excited by proton bunches remains the same even after propagation through the active plasma lens. The emittance of the witness electron beam increases rapidly in the plasma density ramp regions of the lens. Nevertheless, when the witness electron beam has a charge of 100 pC, emittance of 10 mm mrad, and bunch length of 60 $μ$m, its emittance growth is not significant along the active plasma lens. For small emittance, such as 2 mm mrad, the emittance growth is found to be strongly dependent on the RMS beam size, plasma density, and multiple Coulomb scattering.

physics.acc-ph↗