NanoAc Workshop 2025

6 Nov 2025, 08:00 → 7 Nov 2025, 19:10 Europe/London

Letitia Obeng (Novotel Paddington Village, University of Liverpool/Cockcroft Institute, UK)

Carsten Welsch (University of Liverpool), Guoxing Xia (University of Manchester), Javier Resta López (Universitat de Valencia), Alexandre Bonatto (Universidade Federal de Ciências da Saúde de Porto Alegre), Bifeng Lei (University of Liverpool)

 

The 3rd NanoAc Workshop on Applications of Nanostructures in the Field of Accelerator Physics will be hosted by the QUASAR Group at the University of Liverpool and the Cockcroft Institute. The event will take place on 6–7 November 2025 in Liverpool, UK.

Nanomaterials present unique opportunities for supporting ultrahigh gradients in particle acceleration and radiation generation. When driven by high-intensity lasers or particle beams, these materials can potentially sustain electromagnetic fields reaching hundreds of teravolts per meter (TV/m). This remarkable capability opens a new frontier for the development of next-generation accelerators and broadens their potential applications across a wide range of scientific and industrial fields.

To explore this emerging area, the workshop will bring together experts from diverse disciplines—including plasma physics, accelerator physics, solid-state physics, materials science, computer science, engineering, industrial nanotechnology, spectroscopy and more. This multidisciplinary approach is essential for addressing the complex challenges and opportunities that nanostructured materials present in accelerator science.

In addition to advancing scientific understanding, the event will provide an excellent platform for networking, exchanging ideas, and fostering new collaborations.

The main conference topics will include:

• Relativistic laser-nanomaterials interaction
• Nanomaterials-based particle acceleration and applications
• Nanomaterials-based radiation sources and applications
• High field surface plasmonics
• Particle channelling in nanomaterials and crystals
• Nanomaterials, nanofabrication and targetry
• Beam diagnostics for nano accelerators
• Simulation technologies for plasmas and nanomaterials

 

The workshop will be available for online participation. You can access it with the following links:

• Day 1 on 6 November: Zoom Link and agenda​
• Day 2 on 7 November: Zoom Link and agenda​

 

 

                         

nanoAc_2025_Poster.pdf

NanoAc 2025 - Practical info.pdf

Thursday, 6 November

09:00 → 09:45 Registration

09:45 → 10:00 Welcome

Speaker: Prof. Carsten Welsch (University of Liverpool)

10:00 → 10:50 State-of-the-art of channeling of charged particles in crystals and nanostructures: Beam Channelling for Accelerator and Radiation Physics

Channeling is the phenomenon well-known in the physics world mostly related to the
propagation of the beams of charged particles in aligned crystals. Since the discovery,
channeling of high-energy leptons (electrons/positrons of several MeV up to hundred of
GeV energies) and hadrons (protons/ions of tens GeV up to several TeV energies) has been applied at various famous world research centres within different national/international projects related to the phenomenon utilisation to shape the beams as well as to produce high power x-ray and gamma radiation sources.

However, recent studies have shown the feasibility of channeling phenomenology applica-
tion for description of other various mechanisms of interaction of charged as well as neutral particles beams in solids, plasmas and electromagnetic fields covering the research fields from crystal/laser/plasma based undulators and collimators to capillary based x-ray and neutron optical elements.

This talk is devoted to actual channeling related projects that have been realising since
so-called renaissance of channeling studies started in the end of last century, as well as to
the future possible developments in channeling (bulk and surface) physics that has been
extended from the crystals to the external structured electromagnetic fields.

Speaker: Prof. Sultan Dabagov (INFN Lab Naz Frascati)

abs-nanoAc2025_dabagov.pdf

10:50 → 11:20 40 years of development of plasma wakefield acceleration

Speaker: Prof. Guoxing Xia (University of Mancester)

11:20 → 11:40 Coffee break

11:40 → 12:10 Interaction of high-intensity beam with structured solid surface plasma in relativistic regime

Recent research into the interaction between high-intensity beams (e.g. laser or charged particle beams) and surface plasmas has revealed significant potential for generating extremely strong fields for particle acceleration and radiation production. This new approach has emerged by overcoming several challenges in beam-solid interactions. It therefore holds great promise for reforming the research direction of large-scale facilities pursuing the energy frontier and micro-scale facilities demanding great flexibility. At the same time, this research can provide new insights into the extremely complex nonlinear dynamics of surface plasmons in the strong fields, a new unexplored regime.
In this talk, I will present our recent theoretical work on the interaction between high-intensity lasers or beams and structured solid surfaces made of nanomaterials, such as well-aligned carbon nanotube (CNT) forests. It aims to achieve a TeV/m-level accelerating gradient for ultra-compact particle acceleration, as well as pushing the energy frontier [1,2,3]. Thanks to the excellent properties of relativistic surface plasmons (RSPs) on these structured nanomaterials, we can also expect to produce high-quality radiation [4]. A brief discussion of future research activities will be given, with potential facilities that could support our experimental demonstrations.

References:
[1] Bifeng Lei et al. 2025 Plasma Phys. Control. Fusion 67 065036
[2] Bifeng Lei et al. 2025 New J. Phys. 27 084301
[3] Cristian Bonţoiu et al. eprint: arXiv:2502.00183v2, 11 Feb 2025. In the preview process of Sci. Rep.
[4] Bifeng Lei et al. eprint: arXiv:2507.04561v1, 06 Jul 2025. In the preview process of PRL.

Speaker: Dr Bifeng Lei (UOL/CI)

12:10 → 12:40 Oriented crystals and nanostructures and their applications

Speaker: Dr Sytov Alexei (INFN Ferrara Division)

12:40 → 14:00 Lunch

14:00 → 14:20 Bright Radiation Sources Driven by Ultrafast High-Intensity Lasers and Applications

With the ongoing miniaturization and stabilization of laser wakefield accelerators (LWFA), tabletop X-ray sources based on such accelerators have shown great potential. Among them, Betatron radiation sources driven by ultrafast, high-intensity lasers feature micrometer-scale source size, femtosecond pulse duration, milliradian-scale divergence, and broadband spectra extending to tens of keV. These characteristics make them highly suitable for high-contrast imaging of microstructures, diagnostics of high-energy-density states in inertial confinement fusion (ICF), and ultrafast dynamic studies in multidisciplinary research. This presentation will showcase the recent development of a high-brightness Betatron hard X-ray source platform at the Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences. In particular, we report on Betatron sources driven by two high-power laser systems—a 1 PW/0.1Hz laser system at Shanghai Superintense Ultrafast Laser Facility (SULF) and a 200 TW/1 Hz laser—achieving critical energies in the range of 15–86 keV and photon yields exceeding 1010 photons per shot. We further demonstrate their application in X-ray phase-contrast imaging.

Speaker: Prof. Song Li (SIOM)

14:20 → 14:40 Wakefield Excitation in Carbon Nanotubes and Graphene Layers: Hydrodynamic Approach and PIC Simulations

Charged particles traversing carbon-based nanostructures can trigger electromagnetic (plasmonic) modes through the collective excitation of surface electron gases. This phenomenon presents a promising avenue for achieving ultra-high particle acceleration gradients. Plasmonic excitations can be explored using both analytical models and particle-based simulations. In this work, we first revisit the theoretical framework based on a linearized hydrodynamic model describing a point charge moving along carbon nanotubes and graphene layers. Within this model, surface-confined electrons are treated as a two-dimensional plasma, with additional momentum contributions arising from the solid-state characteristics of the electron gas. We then compare the plasmonic responses predicted by the hydrodynamic model with those obtained via Particle-in-Cell (PIC) simulations. Finally, we conduct a detailed analysis to assess the similarities, differences, and limitations of both approaches.

Speaker: Dr Pablo Martín-Luna (IFIC( CSIC-UV))

14:40 → 15:00 Fine-tuning objective functions for Bayesian optimization of LWFA-accelerated electrons in nanostructured CNT targets

Nanostructured materials composed of alternating layers of two-dimensional carbon structures and empty or low-density regions have emerged as promising targets for compact, ultra-high gradient electron acceleration via LWFA. As an intense laser pulse propagates through these gaps, the carbon atoms at their boundaries are ionized, filling the voids with high-density electron plasmas capable of sustaining accelerating gradients on the order of TeV/m. Consequently, few-micrometer-long targets can generate electron bunches carrying charges of hundreds of pico-coulombs and energies of several tens of MeV. The performance of such accelerators -- in terms of beam energy, charge, and quality -- depends sensitively on multiple parameters, including laser intensity, pulse duration, and target geometry. In this work, Bayesian optimization is applied to particle-in-cell simulations of concentric cylindrical-shell targets separated by vacuum gaps, aiming to identify configurations that favor edge and bubble-like self-injection of electrons for LWFA acceleration. The simulations are conducted with the FBPIC code, and Optimas is employed as the Bayesian optimization framework. Different formulations of multi-objective functions are evaluated and compared, and preliminary results reveal how these formulations affect the acceleration process and the resulting beam properties.

Speaker: Prof. Alexandre Bonatto (Universidade Federal de Ciências da Saúde de Porto Alegre)

15:00 → 15:30 Coffee break

15:30 → 16:30 Round table discussion: Theoretical, numerical and experimental potentials and opportunities

Convener: Prof. Guoxing Xia (University of Manchester)

16:30 → 17:00 Coffee break

17:00 → 17:50 Invited talk

Speaker: Prof. Toshiki Tajima (UCI)

19:00 → 21:00 Dinner

Friday, 7 November

09:30 → 10:00 The NanoAc Collaboration: Toward a Proof-of-Principle for Laser Wakefield Acceleration in Nanostructured Solid-State Plasma

Solid-state plasma wakefield acceleration has recently attracted attention as a novel method for achieving unprecedented ultra-high acceleration gradients on the order of 1 TV/m or beyond. In this context, recent advancements in nanofabrication techniques have opened up the possibility of creating structured plasmas with tailored properties. For instance, the utilization of carbon nanotube (CNT) bundles holds great potential for generating stable plasmas with electron densities reaching as high as 10^24 cm-3, i.e., orders of magnitude higher than conventional gaseous plasmas. As part of a new collaborative effort called NanoAc, we have conducted Particle-In-Cell (PIC) simulations to investigate laser wakefield acceleration in nanostructured solid-state plasmas based on CNT arrays. Our results confirm the attainment of wakefields at the TV/m scale. Additionally, we observed self-injection, sub-femtosecond bunch formation, and electron acceleration in micrometre-scale targets, yielding kinetic energies of ~10 MeV. These findings open up promising possibilities to design novel ultra-compact accelerators and radiation sources. In this contribution, we present a summary of the work carried out by the NanoAc collaboration to date and discuss the preparation of future experimental tests in existing laser facilities.

Speaker: Dr Javier Resta López (ICMUV-University of Valencia)

10:00 → 10:30 Current status of FEBE laser and experimental opportunities

Speaker: Dr Lewis Reid (ASTeC, STFC)

10:30 → 11:00 All-optical source size and emittance measurements of laser-accelerated electron beams

Recent developments in ultra-low emittance electron beam generation offer compact, high-quality particle sources for future high-energy physics and free-electron laser applications. Measuring such excellent emittances poses a significant challenge.

Here we present a new, laser-based technique which modulates the electron phase-space ponderomotively, achieving sub-0.1 mm mrad emittance resolution. We report the first experimental validation of this approach using a laser wakefield accelerator. Our results are in agreement with emittance and source size values of prior studies using different methods such as quadrupole scans. Additionally, we demonstrate that the "laser-grating" method provides upper limits on emittance and source size, even under conditions of low signal-to-noise ratio and uncertainties in laser-grating parameters.

Speaker: Dr Daniel Seipt (HIJ/GSI)

11:00 → 11:30 Coffee break

11:30 → 12:00 High-quality particle and radiation sources from laser peeler regime

Laser-based particle acceleration is a promising candidate for next-generation accelerators and radiation sources. However, currently, the laser-accelerated ion beams and radiations have limitations in peak energy, flux, energy spread, etc. In this talk, I shall report a novel method to overcome these limitations by irradiating the edge of a microtape with available femtosecond lasers, called laser peeler regime [1-4]. As the laser pulse sweeps along the tape, it excites a strong surface plasma wave, which accelerates tens of pC electrons to superponderomotive energies [1,5]. While acceleration, these electrons undergo transverse betatron oscillations, leading to emission of hard x-rays. On the other hand, when these high space charge electrons are injected into the accelerating region, protons are accelerated and bunched simultaneously, leading to a monoenergetic proton spectrum. Our 3D PIC simulations demonstrate that a monoenergetic proton beam with peak energy > 100 MeV and energy spread about 1% can be stably achieved [1], whilst emitting bright x-rays [4].

References:
[1] X. F. Shen, et al., Phys. Rev. X 11, 041002 (2021);
[2] X. F. Shen, et al., Quantum Electronics 51, 833 (2021);
[3] X. F. Shen, et al., Plasma Phys. Control. Fusion 65, 034005 (2023);
[4] X. F. Shen, et al., Commun. Phys. 7, 84 (2024);
[5] A. McCay, et al., Phys. Rev. Lett. 135, 145001 (2025).

Speaker: Prof. Xiaofei Shen (PKU)

NanoAc Workshop 2025-Xiaofei Shen.pdf

12:00 → 12:30 Laser-driven superior ion acceleration in relativistically transparent plasma via laser front steepening

Laser-driven ion acceleration in plasma is an active topic of research. Various acceleration mechanisms have been investigated. Recently, with the fast development of petawatt laser technology, laser ion acceleration in near-critical relativistically transparent (NCRT) plasma has attracted much attention. Nanomaterial targets offer one of the most promising approaches for generating NCRT plasma.

A petawatt laser pulse can make an initially over- but still near-critical plasma relativistically transparent and propagate in it. At the laser front, the laser radiation pressure piles up background electrons, generating a strong charge-separation field which is localized and comoving with the laser pulse. Basically, ion acceleration in the charge-separation field operates on principles analogous to electron acceleration in laser wakefield in dilute plasma [1,2].

However, as the plasma density increases, a new challenge arises. In dilute plasma, the laser plasma interaction mainly follows the linear dispersion relation and thus the phase velocity of the wakefield is dominated by the normalized plasma density. In a NCRT plasma, however, the laser-plasma interaction becomes highly nonlinear, and the propagation velocity of the laser-driven charge-separation field is governed by the balance between the electrostatic pressure and the laser radiation pressure, making it depend not only on the plasma density but also on the laser amplitude at the front [3,4]. This can result in an inertial force in the frame comoving with the charge-separation field, which can prevent the trapping of background ions or disrupt the acceleration of already trapped ions, especially when achieving high energy acceleration. In this talk we show that this can be overcome by employing a buffering underdense plasma to steepen the leading edge of the laser pulse in advance. This can lead to a superior ion acceleration process known as ion wave breaking acceleration [5] which is promising in producing quasi-mono-energetic and collimated ion beams.

[1] B. Liu, J. Meyer-ter-Vehn, and H. Ruhl, Physics of Plasmas 25, 103117 (2018).
[2] B. Liu, M. Shi, M. Zepf, B. Lei, and D. Seipt, Physical Review Letters 129, 274801 (2022).
[3] B. Liu, J. Meyer-ter-Vehn, H. Ruhl, and M. Zepf, Plasma Physics and Controlled Fusion 62, 085014 (2020).
[4] B. Liu, B. Lei, Y. Gao, M. Wen, K. Zhu, Plasma Physics and Controlled Fusion 66, 115004 (2024).
[5] B. Liu, J. Meyer-ter-Vehn, K.-U. Bamberg, W. J. Ma, J. Liu, X. T. He, X. Q. Yan, and H. Ruhl, Physical Review Accelerators and Beams 19, 073401 (2016).

Speaker: Dr Bin Liu (Guangdong Institute of Laser Plasma Accelerator Technology, Guangzhou, China)

12:30 → 12:50 Diagnostic techniques in plasma-based accelerators

Speaker: Dr Hao Zhang (UOL/CI)

12:50 → 14:10 Lunch

14:10 → 14:30 Laser wakefield acceleration in carbon nanotube bundles

Laser wakefield acceleration (LWFA) can produce gradients of tens to hundreds of GV/m, greatly reducing accelerator size and cost. Carbon nanotube (CNT) bundles, featuring high plasma density (>10
cm
), tunable effective density, and empty channels that enable laser propagation, have attracted interest as solid-state plasma sources. Previous studies have suggested that CNT-based structures can increase acceleration gradients to the TV/m range, making them promising for compact radiation sources. In this work, we model a hollow solid-state plasma channel composed of CNT bundles. A 2 PW laser from the ELI-ALPS High-Field Laser facility is injected into the channel, where self-injected electrons at the nC scale are trapped and accelerated in a TV/m gradient, as shown by particle-in-cell (PIC) simulations with WarpX. We determined the effective plasma density and laser configurations through parameter optimisation with uniform CNTs. Using CNT bundles, we then achieved unprecedented beam quality: >2 nC charge, >100 MeV mean energy, <5% energy spread, and <10 mm·mrad emittance, by tuning the filling factor, bundle diameter, and gap size. Related acceleration processes are also demonstrated.

Speaker: Jiaqi Zhang (University of Manchester)

14:30 → 14:50 Analytical, Computational, and Experimental Study of Discharge Plasma Capillaries for Laser Plasma Wakefield Acceleration

Laser Plasma Wakefield Acceleration (LPWA) is a promising way to achieve ultra-high accelerating gradients, relying on plasma channels to guide intense laser pulses over long distances. In this study, we explore discharge plasma capillaries as a potential solution for stable laser guiding and precise control of plasma density. We start by using Computational Fluid Dynamics (CFD) simulations to understand how the neutral gas distributes inside capillaries of different shapes before ionization, and then examine how plasma channels form, taking into account discharge settings, capillary geometry, and gas pressure. At the same time, we are developing an experimental setup to study the plasma directly through Stark broadening spectroscopy. By combining analytical, computational and experimental approaches, this work provides a foundation for developing optimized plasma channels for LPWA.

Speaker: Mostafa Behtouei (Centro de Láseres Pulsados (CLPU))

14:50 → 15:20 Coffee break

15:20 → 16:10 Round table discussion: Collaboration and opportunities

Convener: Dr Javier Resta López (ICMUV-University of Valencia)

15:20 Contributed talk

16:10 → 16:20 Workshop Concludes