arXiv subjects

A. R. Rossi

Publications and source records attributed to A. R. Rossi.

18 recordsLinked to original sources

arXiv2026

A numerical study on plasma acceleration processes with ion dynamics at the sub-nanosecond timescale

Plasma wakefield acceleration is a groundbreaking technique for accelerating particles, capable of sustaining gigavolt-per-meter accelerating fields. Understanding the physical mechanisms governing the recovery of plasma accelerating properties over time is essential for successfully achieving high-repetition-rate plasma acceleration, a key requirement for applicability in both research and commercial settings. In this paper, we present numerical simulations of the early-stage plasma evolution based on the parameters of the SPARC_LAB hydrogen plasma recovery time experiment (Pompili et al., Comm. Phys. 7, 241 (2024)), employing spatially resolved Particle-in-Cell and fluid models. The experiment reports on a non-monotonic dependence of the plasma recovery time on the initial plasma density, an effect for which ion motion has been invoked as a contributing factor. The simulations presented here provide further insight into the role of ion dynamics in shaping this behavior. Furthermore, comparing Particle-in-Cell and fluid approaches allows us to assess the quality of fluid models for describing this class of plasma dynamics.

physics.plasm-ph↗

arXiv2026

A note on thermal effects in non-linear models for plasma-based acceleration

We investigate the impact of a non-negligible background temperature on relativistic plasma wake-fields generated when a beam of charged particles passes through a neutral plasma at rest. We focus on the blowout regime, wherein the plasma response is highly non-linear: plasma electrons are radially blown out and expelled away from the propagation axis of the beam particles, creating a region (bubble) of ions without electrons. Our study builds upon earlier investigations for non-linear models of plasma wakefields developed in the limit of zero background temperature (Lu et al., Phys. Rev. Lett. 96, 165002 (2006)). In the presence of a non-zero background temperature, we characterize the model and focus on its predictions for the bubble size and the electromagnetic fields inside the bubble. Model predictions are studied in combination with PIC simulations.

physics.plasm-ph↗

arXiv2026

Active interrogation of underground piezoelectric fabrics using high energy muon beams propagating across seismogenic faults

In this paper we extend a previous analysis of a newly conceived technique based on active interrogation of tectonic stress evolution in regions hosting active seismogenic faults. The aim is to monitor and detect stable and reliable precursor signals on an adequate time scale, well before an earthquake event, that can play a crucial role in activating alarms for civil protection systems. The precursor signal relies on continuous measurements of the time evolution of tectonic stress, obtained by interrogating underground, with a high energy collimated muon beam, the piezoelectric fabrics present in quartz rich granite like rocks surrounding a known seismogenic fault in the Earth crust. Beam propagation through the rock across the active fault conveys to a detector at the exit of the traversal information on the amplitude of the piezoelectric field, which scales with the tectonic stress applied to quartz crystals embedded in the rock. The system, named ERMES (Earthquake Reconnaissance using Muon beam Evolution in Silicon dioxide), differs from other techniques under study detecting electromagnetic signals generated by piezoelectricity outside the Earth crust, as it probes piezoelectric effects directly inside the source region of the associated electromagnetic field, namely the near field within quartz crystals rather than the far field in open space. We present a focused analysis of muon beam manipulation after rock traversal and before detection using a newly conceived muonic lens, and we explore the maximum rock penetration capability of a high energy muon beam, reaching about 3 km of rock thickness for a 10 TeV beam. Owing to the peculiarity of muon propagation through such kilometer scale targets, we cross checked previous FLUKA Monte Carlo simulations with Geant4 to clarify the secondary muons role generated by primary muon interactions in solid matter over long propagation lengths.

physics.acc-ph↗

arXiv2025

Remote sensing of tectonic induced stress across faults using high energy muon beams

We illustrate a theoretical study of a newly conceived technique using high-energy muon beams (TeV-class) propagating through thick (km-long) crystalline rock layers subject to tectonic-induced stress, potentially capable of actively monitoring the temporal evolution of the pressure rise in seismic fault zones associated with earthquake triggering when the induced tectonic pressure reaches and overcomes the rock elasto-plastic deformation limit. This technique could contribute to improving earthquake forecasting statistics in seismically active regions, offering support for seismic hazard assessment and prevention strategies. Active monitoring of the induced tectonic stress and its time evolution is achieved by remote sensing of the electric field generated in quartz crystals embedded in crystalline rocks by piezoelectric effects. In this context, tectonic pressure refers to the time-dependent stress field acting on the rock body due to tectonic forces, which adds to the time-independent lithostatic pressure resulting from the weight of overlying materials. High-energy muon beams transmitted through a rock layer subject to tectonic pressure will be affected in their transverse phase space distributions by the piezoelectric fields, therefore transferring to a detector the information on the applied tectonic stress. Finally, we illustrate the design of a proof-of-principle experiment to be conducted in a standard accelerator laboratory, using moderate-energy muons (GeV-class) propagating through granite slabs subject to a press-induced stress reaching the rupture limit. A zero-generation proof-of-principle test can also be performed using 20-150\,MeV electron beams transmitted through single quartz crystals subject to variable pressure.

physics.acc-ph↗

arXiv2024

Extreme radiation emission regime for electron beams in strong focusing ion channels and undulators

A fundamental comparison between undulator and ion channel radiation is presented. Conventional theory for both devices fails to describe high $k$ and $K/γ$ regimes accurately, providing an underestimation of particle trajectory amplitude and period. This may lead to incorrect estimation of radiation emission in many setups of practical interest, such as the ion column. A redefinition of plasma density and undulator strength expressions leads to a more reliable prediction of particle behaviour, reproducing the closest possible conditions in the two devices and correctly matching expected betatron oscillation amplitude and wavelength for a wide range of $K/γ$ values. Differences in spectral features of the two devices can then be addressed via numerical simulations of single particle and beam dynamics. In this paper we outline a theoretical framework and compare its results with numerical simulation applied to setups eligible for possible radiation sources.

physics.acc-ph↗

arXiv2023

Intrinsic mono-chromatic emission of x and gamma-rays in symmetric electron-photon beam collisions

This paper explores the transition between Compton Scattering and Inverse Compton Scattering (ICS), which is characterized by an equal exchange of energy and momentum between the colliding particles (electrons and photons). This regime has been called Symmetric Compton Scattering (SCS) and has the unique property of cancelling the energy-angle correlation of scattered photons, and, when the electron recoil is large, transferring mono-chromaticity from one colliding beam to the other, resulting in back-scattered photon beams that are intrinsically monochromatic. The paper suggests that large-recoil SCS or quasi-SCS can be used to design compact intrinsic monochromatic gamma-ray sources based on compact linacs, thus avoiding the use of GeV-class electron beams together with powerful laser/optical systems as those typically required for ICS sources.

physics.acc-ph↗

arXiv2021

First emittance measurement of the beam-driven plasma wakefield accelerated electron beam

Next-generation plasma-based accelerators can push electron beams to GeV energies within centimetre distances. The plasma, excited by a driver pulse, is indeed able to sustain huge electric fields that can efficiently accelerate a trailing witness bunch, which was experimentally demonstrated on multiple occasions. Thus, the main focus of the current research is being shifted towards achieving a high quality of the beam after the plasma acceleration. In this letter we present beam-driven plasma wakefield acceleration experiment, where initially preformed high-quality witness beam was accelerated inside the plasma and characterized. In this experiment the witness beam quality after the acceleration was maintained on high level, with $0.2\%$ final energy spread and $3.8~μm$ resulting normalized transverse emittance after the acceleration. In this article, for the first time to our knowledge, the emittance of the PWFA beam was directly measured.

physics.acc-ph↗

arXiv2020

Energy spread minimization in a beam-driven plasma wakefield accelerator

Next-generation plasma-based accelerators can push electron bunches to gigaelectronvolt energies within centimetre distances. The plasma, excited by a driver pulse, generates large electric fields that can efficiently accelerate a trailing witness bunch making possible the realization of laboratory-scale applications ranging from high-energy colliders to ultra-bright light sources. So far several experiments have demonstrated a significant acceleration but the resulting beam quality, especially the energy spread, is still far from state of the art conventional accelerators. Here we show the results of a beam-driven plasma acceleration experiment where we used an electron bunch as a driver followed by an ultra-short witness. The experiment demonstrates, for the first time, an innovative method to achieve an ultra-low energy spread of the accelerated witness of about 0.1%. This is an order of magnitude smaller than what has been obtained so far. The result can lead to a major breakthrough toward the optimization of the plasma acceleration process and its implementation in forthcoming compact machines for user-oriented applications.

physics.acc-ph↗

arXiv2018

Electron beam transfer line design for plasma driven Free Electron Lasers

Plasma driven particle accelerators represent the future of compact accelerating machines and Free Electron Lasers are going to benefit from these new technologies. One of the main issue of this new approach to FEL machines is the design of the transfer line needed to match of the electron-beam with the magnetic undulators. Despite the reduction of the chromaticity of plasma beams is one of the main goals, the target of this line is to be effective even in cases of beams with a considerable value of chromaticity. The method here explained is based on the code GIOTTO [1] that works using a homemade genetic algorithm and that is capable of finding optimal matching line layouts directly using a full 3D tracking code.

physics.acc-ph↗

arXiv2018

EuPRAXIA@SPARC_LAB: the high-brightness RF photo-injector layout proposal

At EuPRAXIA@SPARC_LAB, the unique combination of an advanced high-brightness RF injector and a plasma-based accelerator will drive a new multi-disciplinary user-facility. The facility, that is currently under study at INFN-LNF Laboratories (Frascati, Italy) in synergy with the EuPRAXIA collaboration, will operate the plasma-based accelerator in the external injection configuration. Since in this configuration the stability and reproducibility of the acceleration process in the plasma stage is strongly influenced by the RF-generated electron beam, the main challenge for the RF injector design is related to generating and handling high quality electron beams. In the last decades of R&D activity, the crucial role of high-brightness RF photo-injectors in the fields of radiation generation and advanced acceleration schemes has been largely established, making them effective candidates to drive plasma-based accelerators as pilots for user facilities. An RF injector consisting in a high-brightness S-band photo-injector followed by an advanced X-band linac has been proposed for the EuPRAXIA@SPARC_LAB project. The electron beam dynamics in the photo-injector has been explored by means of simulations, resulting in high-brightness, ultra-short bunches with up to 3 kA peak current at the entrance of the advanced X-band linac booster. The EuPRAXIA@SPARC_LAB high-brightness photo-injector is described here together with performance optimisation and sensitivity studies aiming to actual check the robustness and reliability of the desired working point.

physics.acc-ph↗

arXiv2018

Plasma boosted electron beams for driving Free Electron Lasers

In this paper, we report results of simulations, in the framework of both EuPRAXIA \cite{Walk2017} and EuPRAXIA@SPARC\_LAB \cite{Ferr2017} projects, aimed at delivering a high brightness electron bunch for driving a Free Electron Laser (FEL) by employing a plasma post acceleration scheme. The boosting plasma wave is driven by a tens of \SI{}{\tera\watt} class laser and doubles the energy of an externally injected beam up to \GeV{1}. The injected bunch is simulated starting from a photoinjector, matched to plasma, boosted and finally matched to an undulator, where its ability to produce FEL radiation is verified to yield $O(\num{e11})$ photons per shot at \nm{2.7}.

physics.acc-ph↗

arXiv2018

Plasma acceleration limitations due to betatron radiation

High energy spread caused by the longitudinal size of the beam is well known in wake-field acceleration. Usually this issue can be solved with beam loading effect that allows to keep accelerating field nearly constant, along the whole duration of the beam. In this work, however, we would like to address another source of energy spread that arises at high energy, due to betatron radiation.

physics.acc-ph↗

arXiv2018

Overview of Plasma Lens Experiments and Recent Results at SPARC_LAB

Beam injection and extraction from a plasma module is still one of the crucial aspects to solve in order to produce high quality electron beams with a plasma accelerator. Proper matching conditions require to focus the incoming high brightness beam down to few microns size and to capture a high divergent beam at the exit without loss of beam quality. Plasma-based lenses have proven to provide focusing gradients of the order of kT/m with radially symmetric focusing thus promising compact and affordable alternative to permanent magnets in the design of transport lines. In this paper an overview of recent experiments and future perspectives of plasma lenses is reported.

physics.acc-ph↗

arXiv2018

EUPRAXIA@SPARC_LAB: Beam Dynamics studies for the X-band Linac

In the framework of the Eupraxia Design Study an advanced accelerator facility EUPRAXIA@SPARC_LAB has been proposed to be realized at Frascati (Italy) Laboratories of INFN. Two advanced acceleration schemes will be applied, namely an ultimate high gradient 1 GeV X-band linac together with a plasma acceleration stage to provide accelerating gradients of the GeV/m order. A FEL scheme is foreseen to produce X-ray beams within 3-10 nm range. A 500-TW Laser system is also foreseen for electron and ion production experiments and a Compton backscattering Interaction is planned together with extraction beamlines at intermediate electron beam energy for neutron beams and THz radiation production. The electron beam dynamics studies in the linac are here presented together with the preliminary machine layout.

physics.acc-ph↗

arXiv2018

EuPRAXIA@SPARC_LAB Design study towards a compact FEL facility at LNF

On the wake of the results obtained so far at the SPARC\_LAB test-facility at the Laboratori Nazionali di Frascati (Italy), we are currently investigating the possibility to design and build a new multi-disciplinary user-facility, equipped with a soft X-ray Free Electron Laser (FEL) driven by a $\sim$1 GeV high brightness linac based on plasma accelerator modules. This design study is performed in synergy with the EuPRAXIA design study. In this paper we report about the recent progresses in the on going design study of the new facility.

physics.acc-ph↗

arXiv2018

RF injector design studies for the trailing witness bunch for a plasma-based user facility

The interest in plasma-based accelerators as drivers of user facilities is growing worldwide thanks to its compactness and reduced costs. In this context the EuPRAXIA collaboration is preparing a conceptual design report for a multi-GeV plasma-based accelerator with outstanding electron beam quality to pilot, among several applications, the operation of an X-ray FEL, the most demanding in terms of beam brightness. Intense beam dynamics studies have been performed to provide a reliable working point for the RF injector to generate a high-brightness trailing witness bunch suitable in external injection schemes, both in particle beam and laser driven plasma wakefield acceleration. A case of interest is the generation of a witness beam with 1 GeV energy, less than 1 mm-mrad slice emittance and 30 pC in 10 fs FWHM bunch length, which turns into 3 kA peak current at the undulator entrance. The witness beam has been successfully compressed down to 10 fs in a conventional SPARC-like photo-injector and boosted up to 500 MeV in an advanced high-gradient X-band linac reaching the plasma entrance with 3 kA peak current and the following RMS values: 0.06% energy spread, 0.5 mm-mrad transverse normalised emittance and a focal spot down to 1 $μm$. RF injector studies are here presented with the aim to satisfy the EuPRAXIA requests for the Design Study of a plasma-based user facility.

physics.acc-ph↗

arXiv2011

Coupling of Laser-Generated Electrons with Conventional Accelerator Devices

Laser-based electron acceleration is attracting strong interest from the conventional accelerator community due to its outstanding characteristics in terms of high initial energy, low emittance and high beam current. Unfortunately, such beams are currently not comparable to those of conventional accelerators, limiting their use for the manifold applications that a traditional accelerator can have. Besides working on the plasma source itself, a promising approach to shape the laser-generated beams is coupling them with conventional accelerator elements in order to benefit from both, a versatile electron source and a controllable beam. In this paper we show that some parameters commonly used by the particle accelerator community must be reconsidered when dealing with laser-plasma beams. Starting from the parameters of laser-generated electrons which can be obtained nowadays by conventional multi hundred TW laser systems, we compare different conventional magnetic lattices able to capture and transport those GeV electrons. From this comparison we highlight some important limit of the state-of-the-art plasma generated electrons with respect to conventional accelerator ones. Eventually we discuss an application of such beams in undulators for Free Electron Lasers (FELs), which is one of the most demanding applications in terms of beam quality.

physics.acc-ph↗

arXiv2006

Measuring the photon distribution by ON/OFF photodectors

Reconstruction of photon statistics of optical states provide fundamental information on the nature of any optical field and find various relevant applications. Nevertheless, no detector that can reliably discriminate the number of incident photons is available. On the other hand the alternative of reconstructing density matrix by quantum tomography leads to various technical difficulties that are particular severe in the pulsed regime (where mode matching between signal an local oscillator is very challenging). Even if on/off detectors, as usual avalanche PhotoDiodes operating in Geiger mode, seem useless as photocounters, recently it was shown how reconstruction of photon statistics is possible by considering a variable quantum efficiency. Here we present experimental reconstructions of photon number distributions of both continuous-wave and pulsed light beams in a scheme based on on/off avalanche photodetection assisted by maximum-likelihood estimation. Reconstructions of the distribution for both semiclassical and quantum states of light (as single photon, coherent, pseudothermal and multithermal states) are reported for single-mode as well as for multimode beams. The stability and good accuracy obtained in the reconstruction of these states clearly demonstrate the interesting potentialities of this simple technique.

quant-ph↗