Welcome talk from ECT* director: U. van Kolck Room: Aula Renzo Leonardi

Advances in Laser-driven Neutron Sources and Applications at Osaka University

• Akifumi Yogo

Room: Aula Renzo Leonardi

High yield fast neutron generation with 1kHz repetition rate few cycle lasers

• Karoly Osvay

Room: Aula Renzo Leonardi

Positron and photo-neutron creation using a petawatt laser to irradiate high-Z solid targets

• Edison Liang

Room: Aula Renzo Leonardi Over the past decade, using the Texas Petawatt Laser (TPW, 130 J, 130 fs) at Austin, Texas to irradiate high-Z thick targets(Au, Pt, Re...) at intensities up to 5x10^21 W/cm^2, we have created copious amounts of positrons and photo-neutrons, resulting in super-high densities of emergent positrons and neutrons. We are still in the early stages of exploring potential applications of such high-density positrons and neutrons. A unique feature of TPW-irradiated high-Z dense metal targets is the production of excess high-energy gamma-rays > 8 MeV with a yield many times that expected from hot electron bremsstrahlung. These high energy gamma-rays appear to be concentrated near the giant-dipole resonance (GDR) of high-Z elements (8-20 MeV). They are ideal for photo-neutron and photo-fission reactions. This talk will summarize the large volume of data we have obtained and discuss plans for future research. Work supported by US DOE DE-SC0024874.

Photon-induced interactions in relativistic heavy ion collisions

• Carlos Bertulani (Department of Physics Texas A&M University-Commerce)

Room: Aula Renzo Leonardi Heavy ions provide strong electromagnetic fields that can be used to probe properties of interest in nuclear structure, nuclear astrophysics and particle physics. In this talk I will discuss new developments in understanding the role of the symmetry energy in the equation of state of nuclear matter, nuclear collective phenomena, QED and QCD processes, and other physics phenomena induced by photon-photon and photo-nuclear interactions in reactions with heavy ions.

Nuclear astrophysics with gamma-ray/neutron provided from high peak power laser

• Takehito Hayakawa (National Institutes for Quantum Science and Technology)

Room: Aula Renzo Leonardi High peak power laser has been developed quickly, which leads to generation of radiations such as gamma-rays and neutrons with energies higher than 1 MeV. These laser-driven radiations have unique features of high flux, ultra-short pulse, and continues energy distribution. These features are suitable for study of nuclear reactions in the universe, such as nuclear photoreactions with high energy gamma-rays in supernova explosions (gamma-process) and nuclear reactions with high-energy neutrons generated by spallation reaction with high energy cosmic-rays. In general, the energy spectrum of particles in stars and cosmic-rays have continues energy distribution, which may be similar to that generated by high peak power laser, and its event may occur in short time scale from ms to s. Neutrons have also important roles for stellar nucleosynesis for production of elements heavier iron. Furthermore, gamma-rays and neutrons may contribute to isotopic abundance anomalies observed in some elements in primitive meteorites. They may be caused by irradiations in parent bodies of meteorites in the solar system. T. Hayakawa et al. have theoretically proposed the experiments using laser-driven gamma-rays to study the nuclear photoreactions in supernovae [1]. Recently, high flux neutron pulses have been generated by the secondary reactions with ion pulses from laser-plasma interactions [2]. Such neutrons can also play an important role for the study of decay acceleration of long-lived radioisotopes which may have been considered by cosmic-ray irradiation in the early solar system [3]. Nuclear isomers are one of key for such studies. We discuss the possibility of experiments in nuclear astrophysics using laser-driven gamma-rays and neutrons. [1] T. Hayakawa, et al. Quantum Beam Science, 1(1), 3 (2017). [2] T. Mori, et al. Phys. Rev. C 104, 015808 (2021). [3] T. Hayakawa, et al. Comm. Phys. 6, 299 (2023).

Nuclear Isomers in Nucleosynthesis

• Bradley Meyer

Room: Aula Renzo Leonardi

Discussion (neutron source and astrophysics) Room: Aula Renzo Leonardi Host: Klaus Spohr & Vojtech Horny

Nuclear excitation by electron capture perspectives for laser-generated plasmas and electronic vortex beams

• Adriana Palffy

Room: Aula Renzo Leonardi online

Nuclear excitation by electron capture in electron-ion collisions

• Yuanbin Wu

Room: Aula Renzo Leonardi online

New opportunities in nuclear physics with high-power lasers and multi-photon absorption

• Chieh-Jen Yang (ELI-NP)

Room: Aula Renzo Leonardi I will present some new possibilities, which are very unique for high-power laser systems, to advance nuclear photonics. The main focus will be to show that the multi-photon mechanism could pave a way to circumvent the very challenging problem of isomer pumping/depletion and gamma-ray laser, provided that an intense gamma-flash for laser-plasma interaction is available. The same mechanism might be applied to other high-intensity beams (such as neutron/proton) in the future to gain crucial knowledge of the nuclear man-body forces. By all means, a synergy between nuclear and laser-plasma physics is highly demanded.

What is Modern Nuclear Theory, and What are some of the pressing questions?

• Harald Griesshammer

Room: Aula Renzo Leonardi

Developments in laser-driven ion acceleration relevant to nuclear physics with lasers

• Paul McKenna

Room: Aula Renzo Leonardi

Nuclear isomers at the interface

• Philip Walker

Room: Aula Renzo Leonardi online

Discussion (nuclear excitation and isomers) Room: Aula Renzo Leonardi Host by: Jerry & Klaus

Flying focus beams as a tool to investigate strong-field physics

• Antonino Di Piazza (Department of Physics and Astronomy, University of Rochester and Laboratory for Laser Energetics, University of Rochester)

Room: Aula Renzo Leonardi In a flying focus beam (FFB) the velocity of the focus can be "programmed" and it is independent of the group and the phase velocity of the beam itself. Recent experiments have demonstrated a moving focus over centimeter lengths, i.e., much longer than the Rayleigh length [1]. Scaling this technology to higher power laser pulses would allow one to employ FFBs as a tool for fundamental high-field physics, especially to investigate effects that accumulate with the interaction length. Specifically, by considering an ultrarelativistic electron beam counterpropagating with respect to a FFB, whose focus copropagates with the electrons at the speed of light, we show that the effects of the so-called transverse formation length of radiation on the radiation itself can be enhanced as compared to the case of a conventional Gaussian beam [2]. Analogously, radiation-reaction effects can be rendered measurable at much lower intensities than conventionally required in a similar setup [3]. Finally, we show how FF beams with angular momentum can be an efficient tool to transport ultrarelativistic electron beams over macroscopic distances without significantly spreading on the transverse plane [4]. [1] D. H. Froula, D. Turnbull, A. S. Davies, T. J. Kessler, D. Haberberger, J. P. Palastro, S.-W. Bahk, I. A. Begishev, R. Boni, S. Bucht, J. Katz, and J. L. Shaw, Nat. Photonics **12**, 262 (2018). [2] A. Di Piazza, Phys. Rev. A **103**, 012215 (2021). [3] M. Formanek, D. Ramsey, J. P. Palastro, D. Froula, and A. Di Piazza, Phys. Rev. A **105**, L020203 (2022). [4] M. Formanek, J. P. Palastro, M. Vranic, D. Ramsey, and A. Di Piazza, Phys. Rev. E **107**, 055213 (2023).

Two Laser-Driven Nuclear Physics (LDNP) flagship experiments have been identified for the NSF OPAL Laser Facility

• Chad Forrest (University of Rochester)

Room: Aula Renzo Leonardi Laser-ion acceleration mechanisms provide a unique opportunity for generating radioactive tritium beams, which are currently not available at accelerator facilities. Few datasets exist of tritium-induced reactions involving light, neutron rich nuclei like 6He, 8Li and 11Be. However, these nuclei are of high interest for nuclear science because influence the r-process as “seed nuclei” [Ter01] and are also predicted to exhibit exotic structure [Qua18, Coc12, For05]. A new platform at the OMEGA-EP laser system at the University of Rochester (UR) Laboratory for Laser Energetics (LLE) is now in a position to support nuclear science experimentation [Sch22]. In a pilot study, 10x^13 tritons were accelerated to several MeV and directed onto a deuterated target, producing 108 fusion neutrons. Follow-up experiments using lithium and beryllium targets to measure the cross sections of di-neutron transfer reactions on these light nuclei will be discussed. This material is based upon work supported by the Department of Energy [National Nuclear Security Administration] University of Rochester “National Inertial Confinement Fusion Program” under Award Number(s) DE-NA0004144. [Coc12] Cockrell et al: “Lithium isotopes within the ab-initio no-core full configuration approach” Physical Review C 86 (2012) [For05] Forssen et al: “Large basis ab initio shell model investigation of 9Be and 11Be”, Physical Review C 71 (2005) [Qua18] Quaglioni et al: “Three cluster dynamics within the ab initio no-core shell model with continuum: How many-body correlations and a clustering shape 6He”, Physical Review C 97 (2018) [Sch22] A. Schwemmlein et al: “First Demonstration of a Triton Beam Using Target Normal Sheath Acceleration”, Nuclear Inst. and Methods in Physics Research B 522 (2022) [Ter01] M. Terasawa et al: “New nuclear reaction flow during r-process nucleosynthesis in supernovae: Critical role of light, neutron-rich nuclei’, The Astrophysical Journal, 562 (2001)

TBA (review of where we're at with Apollon)

• Julien Fuchs

Room: Aula Renzo Leonardi

Recent Progress on Heavy-Ion Acceleration: Towards the Fission-Fusion Nuclear Reaction Scheme

• Peter Thirolf (LMU Munich)

Room: Aula Renzo Leonardi The generation of heavy elements in the universe via the rapid neutron-capture process (r-process) lacks direct experimental probing, as the relevant nuclides lie far-off the last known isotopes near the ‘Waiting Point’ at N=126. The proposed ‘fission-fusion’ reaction mechanism aims at investigating this region by using laser-accelerated fissile ions in a two-stage (fission, fusion) scenario, exploiting their unprecedented high bunch density [1]. In a first development step, the acceleration of gold ions is investigated, as recently achieved in our measurement at the PHELIX laser with 500 fs long pulses [2]. In this experiment, the laser-based acceleration of Au ions to kinetic energies above 7 MeV/u was demonstrated. Additionally, individual Au charge states were resolved with unprecedent resolution. This allowed to investigate the role of collisional ionization using a developmental branch of the particle-in-cell simulation code EPOCH [3], showing a much better agreement of the simulated charge state distributions with the experimental ones than when only considering field ionization. This work is presently continued at the Centre for Advanced Laser Applications (CALA), using the ATLAS 3000 laser (800 nm central wavelength, 25 fs pulse length). The laser is focused with an f/2 parabola on Au foils with thicknesses from 200 nm to 500 nm. To analyze the accelerated ion bunch, a Thomson-Parabola Spectrometer was designed to resolve heavy ions in high charge states. Spectroscopically controlled radiative target heating is integrated into the setup in order to facilitate the acceleration of gold ions by removing carbo-hydrate surface contaminations. An integrated IR spectrometer allows for in-situ measurements of the heated foil temperature, while allowing for a simultaneous monitoring with a transmission screen camera to detect possible foil damage [4]. Recent results on Au ion acceleration at CALA will be presented together with preparations for the next stage of the fission-fusion process, i.e. laser-driven fission. Ultimately, these exploratory experimental campaigns aim at preparing for studies at the 10 PW laser facility at ELI-NP with optimum pulse energy and focused intensity. [1] D. Habs et al., “Introducing the fission–fusion reaction process: using a laser-accelerated Th beam to produce neutron-rich nuclei towards the N=126 waiting point of the r-process”, Appl. Phys. B 103, 471-484 (2011) [2] F.H. Lindner et al., “Charge-state resolved laser acceleration of gold ions to beyond 7 MeV/u”, Sci. Rep. 12, 4784 (2022) [3] M. Afshari et al., “The role of collisional ionization in heavy ion acceleration by high intensity laser pulses”, Sci. Rep. 12, 18260 (2022) [4] M. Weiser, “Development of a Spectroscopic Real Time Temperature Diagnostic for Laser Heated Thin Gold Foils”, Master Thesis, LMU Munich, 2021

TBA

• Ishay Pomerantz

Room: Aula Renzo Leonardi

On feasibility of sequential neutron captures studies with intense lasers

• Vojtech Horny

Room: Aula Renzo Leonardi

discussion (strong QED, fission-fusion, neutron application) Room: Aula Renzo Leonardi Host: Leo Gizzi and Yuji Fukuda

Coherent radiation from nonlinear plasma wakefields in the blowout regime

• Jorge Vieira

Room: Aula Renzo Leonardi Coherent light sources, such as free electron lasers, provide bright beams for biology, chemistry, physics and advanced technological applications. As their brightness increases, these sources are also becoming progressively larger, with the longest being several km long (e.g. LCLS). Can we miniaturise these sources and bring them into university, hospital, and industrial-scale laboratories? Plasmas accelerator sources are an attractive solution to this question, but only if their brightness increases several orders of magnitude. Here, we re-examine the fundamentals of superradiance and temporal coherence by exploring the radiation emitted by collective excitations, such as plasma waves. We show that the trajectory of a collective excitation defines the radiation as if it were a single, finite-sized super-charged particle. By applying this principle to nonlinear plasma waves in the nonlinear blowout regime, we identify new conditions leading to superradiance and temporal coherence in plasma-based accelerators [1]. We find that the plasma density can control the radiation frequency over a wide range, from THz to soft x-ray emission, and possibly beyond. We explore these concepts in theory and through particle-in-cell simulations complemented by the Radiation Diagnostic for Osiris (RaDiO) [2,3]. [1] B. Malaca et al, Nature Photonics 18 (1), 39-45 (2024) [2] R.A. Fonseca et al, Plasma Physics and Controlled Fusion 55 (12), 124011 (2013) [3] M. Pardal et al., Computer Physics Communications 285, 108634 (2023)

Path towards a high-flux neutron source at ELI-NP

• Siegfried Glenzer

Room: Aula Renzo Leonardi

Realizing isotopic temperature profiling by using laser-driven neutron source

• Zechen Lan (Institute of laser engineering, Osaka Univ.)

Room: Aula Renzo Leonardi Non-contact thermometry, including phase-contrast imaging thermography, is one of the key technologies for modern science and industry. However, it is challenging to instantaneously measure the temperature of a specific element inside an object. As a possible solution, we propose Neutron Resonance Absorption (NRA) analysis using a Laser-driven Neutron Source (LDNS). Here, fast neutrons generated from the LDNS are decelerated down to a few eV in energy and pass through a sample consisting of tantalum (Ta) and silver (Ag) plates as a simplified model of a composite object. We measured NRA signals distinctive for the Ta and Ag. We demonstrate that the temporal structure of the NRA signal for Ta is broadened by a Doppler effect when the plate of Ta is heated. We measured the NRA signal as a function of the temperature and found that the Doppler width increases according to the free gas model by Bethe. It should be emphasized that the NRA measurement was performed by a single pulse of neutrons, the temporal duration of which is in an order of 100 ns at the sample. In other words, the NRA signal allow us to obtain the temperature during the 100 ns. This fact indicates that our method enables element (isotope)-sensitive and non-destructive thermometry to monitor the instantaneous temperature rise in dynamical processes.

Electron screening in nuclear reactions

• Matej Lipoglavsek

Room: Aula Renzo Leonardi

Nuclear spallation by irradiating an atomic thin graphene target with an intense laser

• Yasuhiro Kuramitsu

Room: Aula Renzo Leonardi

Plasma-Induced Modification of Nuclear β-Decays and Application to Nucleosynthesis

• Bharat Mishra

Room: Aula Renzo Leonardi The talk will be focused on the theory behind the interaction of a plasma with a nucleus, and the consequent modification of decay rates through leptonic and hadronic channels. The former will involve a description of the electron contribution to the decay rate, while the latter will focus on nuclear excited and isomeric states. The talk will include some slides on experimental measurement of the process in stable magnetoplasma, and as promised, the last slides will be left open to discuss possible extension of these studies to laser generated plasmas. These studies will improve current models used for r- and s-process nucleosynthesis.

Nuclear physics measurements with a laser-induced plasma: potential experimental issues and open questions

• Silvia Pisano

Room: Aula Renzo Leonardi

discussion (laser-driven sources, reaction, etc.) Room: Aula Renzo Leonardi host: Yuji Fukuda & Klaus Spohr

On the possibility of a laser assisted nuclear fusion in micron-scale 14N clusters

• Yuji Fukuda

Room: Aula Renzo Leonardi

TBA

• tba tba

Room: Aula Renzo Leonardi

discussion (all topics, future collaborations, etc) Room: Aula Renzo Leonardi host: Jerry, Vojtech, Leo.