arXiv subjects

Tong-Pu Yu

Publications and source records attributed to Tong-Pu Yu.

At least 19 recordsLinked to original sources

arXiv2025

Generation of Polarization-Tunable Hybrid Cylindrical Vector gamma Rays

Cylindrical vector (CV) gamma rays can introduce spatially structured polarization as a new degree of freedom for fundamental research and practical applications. However, their generation and control remain largely unexplored. Here, we put forward a novel method to generate CV gamma rays with tunable hybrid polarization via a rotating electron beam interacting with a solid foil. In this process, the beam generates a coherent transition radiation field and subsequently emits gamma rays through nonlinear Compton scattering. By manipulating the initial azimuthal momentum of the beam, the polarization angle of gamma rays relative to the transverse momentum can be controlled, yielding tunable hybrid CV polarization states. Three-dimensional spin-resolved particle-in-cell simulations demonstrate continuous tuning of the polarization angle across (-90{\deg}, 90{\deg}) with a high polarization degree exceeding 60%. Our work contributes to the development of structured gamma rays, potentially opening new avenues in high-energy physics, nuclear science, and laboratory astrophysics.

physics.plasm-ph↗

arXiv2025

Laser-assisted {\alpha} decay of actinide nuclei in bichromatic fields

Actinide nuclei provide a suitable platform for studying the laser-assisted nuclear $\alpha$ decay, with potential applications in nuclear transmutation, nuclear radiotherapy, and nuclear battery regulation. In the present work, we develop a deformed one-parameter model to quantitatively study the influence of ultra-intense laser fields on the $\alpha$ decay of actinide nuclei. Our calculations show that the $\alpha$-decay half-lives of these nuclei can be altered to some finite extent under laser intensities anticipated at near-future laser facilities. Furthermore, we found that, from the perspective of the nucleus, the laser field's effect on $\alpha$ decay is governed by the nuclear shell structure and decay energy. The $\alpha$-emitting nuclei with lower decay energies and located farther from neutron shell closures are more susceptible to the laser fields. From the perspective of the laser driver, we proposed a bichromatic laser scheme to enhance the effects of laser fields on $\alpha$ tunneling of actinide nuclei. With appropriate phase conditions and amplitude ratios, it is shown that a fundamental-second-harmonic ($\omega$-$2\omega$) bichromatic field can increase the time-averaged modification by one to two orders of magnitude.

nucl-th↗

arXiv2025

Charge state regulation of nuclear excitation by electron capture in $^{229}$Th ions

Nuclear excitation by electron capture (NEEC) in $^{229}$Th holds significant potential for precise nuclear state manipulation. In this study, we thoroughly investigate NEEC in $^{229}\text{Th}^{q+}$ ions by integrating quantum numbers ($n, l, j$) effects and analyzing key parameters (e.g., resonance energy $E_r$, cross section $\sigma$, resonance strength $S$, and NEEC transition width $\Gamma_{\text{NEEC}}$) influences across charge state from $q=1^+$ to $90^+$. Especially, we focus on the charge-state regulation of the isomeric state (IS, 8.36 eV) and second-excited state (SE, 29.19 keV). Our calculations uncover critical charge-state-dependent behaviors of NEEC in $^{229}\text{Th}$ ions: (1) For the IS, valid NEEC channels exhibit threshold migration, where the dominant principal quantum number $n$ increases linearly with $q$ following the relation $n \approx 1.28q + 4.23$; meanwhile, single-$n$-channel $S$ stabilizes between $10^{-2}$ to $10^0$ barn eV via compensatory nucleus-electron coupling, ensuring the total resonance $S$ constant. (2) For the SE, its excitation energy far exceeds nearly all electron binding energies, leading to negligible channel screening and causing the total $S$ to increase monotonically with $q$. This research clarifies the intrinsic mechanisms of charge-state-driven nuclear-electronic interactions in $^{229}\text{Th}^{q+}$ NEEC and provides a critical reference for future experimental efforts to manipulate $^{229}\text{Th}$ nuclear states, particularly via indirect regulation of the SE.

nucl-th↗

arXiv2025

Generating Cylindrical Vector {\gamma} Rays via Beam-Target Interactions: Towards Structured Light at High Energies

Structured {\gamma} rays, particularly cylindrical vector {\gamma} rays, offer promising tools for sub-nuclear imaging and polarization-sensitive probes in fundamental research and applications, but conventional optical methods face great challenges at such photon energy. Here, we put forward a novel method generating such {\gamma} rays through relativistic beam-target interactions. For instance, radially polarized {\gamma} rays can be generated by using a dense electron beam striking a multifoil target. We find that the radial polarization is transferred from the generated coherent transition radiation (CTR) fields to $\gamma$ photons through nonlinear Compton scattering, with the high polarization preserved by phase matching. Three-dimensional spin-resolved simulations demonstrate radial polarization degrees approaching 60\%. Furthermore, these {\gamma} rays can decay into azimuthally spin-polarized positrons via the nonlinear Breit-Wheeler process, with their spins aligning along the CTR magnetic field. Our work extends the concept of structured light into the {\gamma}-ray regime, offering new prospects for broad fields such as nuclear structure probing, fundamental symmetries tests, polarization-sensitive studies in extreme conditions, and laboratory astrophysical observations.

physics.optics↗

arXiv2025

Laguerre-Gaussian pulses for spin-polarized ion beam acceleration

Polarized particle sources have a plethora of applications, ranging from deep-inelastic scattering to nuclear fusion. One crucial challenge in laser-plasma interaction is maintaining the initial polarization of the target. Here, we propose the acceleration of spin-polarized Helium-3 from near-critical density targets using high-intensity Laguerre-Gaussian laser pulses. Three-dimensional particle-in-cell simulations show that Magnetic Vortex Acceleration with these modes yields higher polarization on the 90%-level compared to conventional Gaussian laser pulses, while also providing low-divergence beams.

physics.plasm-ph↗

arXiv2024

Generation and Acceleration of Isolated-Attosecond Electron Bunch in a Hollow-Channel Plasma Wakefield

We propose a novel scheme for generating and accelerating simultaneously a dozen-GeV isolated attosecond electron bunch from an electron beam-driven hollow-channel plasma target. During the beam-target interaction, transverse oscillations of plasma electrons are induced, and subsequently, a radiative wakefield is generated. Meanwhile, a large number of plasma electrons of close to the speed of light are injected transversely from the position of the weaker radiative wakefield (e.g., the half-periodic node of the radiative wakefield) and converge towards the center of the hollow channel, forming an isolated attosecond electron bunch. Then, the attosecond electron bunch is significantly accelerated to high energies by the radiative wakefield. It is demonstrated theoretically and numerically that this scheme can efficiently generate an isolated attosecond electron bunch with a charge of more than 2 nC, a peak energy up to 13 GeV of more than 2 times that of the driving electron beam, a peak divergence angle of less than 5 mmrad, a duration of 276 as, and an energy conversion efficiency of 36.7% as well as a high stability as compared with the laser-beam drive case. Such an isolated attosecond electron bunch in the range of GeV would provide critical applications in ultrafast physics and high energy physics, etc.

physics.plasm-ph↗

arXiv2024

Inelastic electron scattering-induced nuclear excitation rates and dynamics in $^{229}$Th

In the present work, we investigate the excitation rates and population dynamics of $^{229}$Th nuclei induced by inelastic electron scattering, focusing on how electron energy, flux, and ionic charge state influence the excitation process of the nuclei. Using the Dirac Hartree-Fock-Slater method, we calculate cross sections for both the isomeric state (8.36 eV) and the second-excited state (29.19 keV) of $^{229}$Th over a wide range of ionic charge states and electron energies. Our results demonstrate that these factors significantly impact the nuclear excitation efficiency. The effect of indirect excitation through the second-excited state on enhancing the accumulation of nuclei in the isomeric state cannot be ignored. By applying rate equations to model the temporal evolution of nuclear populations, we show that under optimal conditions, up to 10\% of $^{229}$Th$^{4+}$ ions can be accumulated in the isomeric state. These findings provide important insights for optimizing electron-nucleus interactions, contributing to the development of $^{229}$Th-based nuclear clocks and relevant precision measurement applications.

nucl-th↗

arXiv2024

Compact Efficient Polarizers for Relativistic Electron Beams

Relativistic spin-polarized electron beams are important for fundamental research and the industry, but their generation currently requires conventional accelerators or ultrastrong laser facilities, limiting their accessibility and broad applications. Here, we put forward a novel method for constructing a compact efficient "polarizer" that achieves direct ultrafast conversion of relativistic dense electron beams into polarized ones, based on the beam "self-polarization" mechanism via simple beam-target interactions. In this scheme, as the electron beam grazes through the polarizer (a double-layer solid target), it ionizes the target and excites an asymmetric plasma field due to the plasma backflows. This field then reacts on the beam itself, triggering spontaneous radiative polarization and reflection of the beam, and ultimately yielding a dense polarized electron beam. Moreover, the double-layer target setup induces a plasma bubble that focuses the polarized beam and reshapes its polarization distribution. Our method is robust with respect to the beam and target parameters, and opens a new avenue for relativistic beam polarization with compact accessible devices, which would facilitate their broad applications and the development of related experiments, such as in strong-field QED studies, and polarized electron-positron and electron-ion colliders.

physics.plasm-ph↗

arXiv2023

Dense polarized positrons from beam-solid interactions

Relativistic positron sources with high spin polarization have important applications in nuclear and particle physics and many frontier fields. However, it is challenging to produce dense polarized positrons. Here we present a simple and effective method to achieve such a positron source by directly impinging a relativistic high-density electron beam on the surface of a solid target. During the interaction, a strong return current of plasma electrons is induced and subsequently asymmetric quasistatic magnetic fields as high as megatesla are generated along the target surface. This gives rise to strong radiative spin flips and multiphoton processes, thus leading to efficient generation of copious polarized positrons. With three-dimensional particle-in-cell simulations, we demonstrate the production of a dense highly-polarized multi-GeV positron beam with an average spin polarization above 40% and nC-scale charge per shot. This offers a novel route for the studies of laserless strong-field quantum electrodynamics physics and for the development of high-energy polarized positron sources.

physics.plasm-ph↗

arXiv2023

Laser-assisted deformed $\alpha$ decay of the ground state even-even nuclei

In the present work, the influence of ultra-intense laser fields on the $\alpha$ decay half-life of the deformed ground state even-even nucleus with the mass number $52 \leq Z \leq 118$ is systematically studied. The calculations show that the laser field changes the $\alpha$ decay half-life by varying the $\alpha$ decay penetration probability in a small range. Moreover, the analytical formulas for the rate of change of the $\alpha$ decay penetration probability in the ultra-intense laser fields have been derived by the spherical approximation, which agrees well with the numerical solutions for nuclei with more significant proton numbers. This provides a fast way to estimate the rate of change of the $\alpha$ decay penetration probability for superheavy nuclei. Furthermore, the relationship between laser properties and the average rate of change of the $\alpha$ decay penetration probability is investigated. The calculations indicate that the shorter the wavelength of the laser pulse is, the larger the average rate of change of the penetration probability.

nucl-th↗

arXiv2022

Half-lives for proton emission and {\alpha} decay within the deformed Gamow-like model

In the present work, we study {\alpha} decay and proton emission half-lives within the modified Gamow-like model, which introduces the effects of the nucleus's deformation. The calculations show that it is necessary to consider the deformation in the calculation for nuclei far from the shell. Moreover, we use the improved model to predict the proton emission half-lives of the nuclei far from the shell. The calculation results indicate that our model is in good agreement with most models. Furthermore, the deformed Gamow-like model is used to find the following neutron magic number. This work is meaningful for future research on superheavy nuclei.

nucl-th↗

arXiv2021

Generation of quasi-monoenergetic proton beams via quantum radiative compression

Dense high-energy monoenergetic proton beams are vital for wide applications, thus modern laser-plasma-based ion acceleration methods are aiming to obtain high-energy proton beams with energy spread as low as possible. In this work, we put forward a quantum radiative compression method to post-compress a highly accelerated proton beam and convert it to a dense quasi-monoenergetic one. We find that when the relativistic plasma produced by radiation pressure acceleration collides head-on with an ultraintense laser beam, large-amplitude plasma oscillations are excited due to quantum radiation-reaction and the ponderomotive force, which induce compression of the phase space of protons located in its acceleration phase with negative gradient. Our three-dimensional spin-resolved QED particle-in-cell simulations show that hollow-structure proton beams with a peak energy $\sim$ GeV, relative energy spread of few percents and number $N_p\sim10^{10}$ (or $N_p\sim 10^9$ with a $1\%$ energy spread) can be produced in near future laser facilities, which may fulfill the requirements of important applications, such as, for radiography of ultra-thick dense materials, or as injectors of hadron colliders.

physics.plasm-ph↗

arXiv2021

Prompt Acceleration of a Short-Lifetime Low-Energy Muon Beam

An energetic muon beam is an attractive key to unlock new physics beyond the Standard Model: the lepton flavor violation or the anomalous magnetic moment, and also is a competitive candidate for the expected neutrino factory. Lots of the muon scientific applications are limited by low flux cosmic-ray muons, low energy muon sources or extremely expensive muon accelerators. An prompt acceleration of the low-energy muon beam is found in the beam-driven plasma wakefield up to $\mathrm{TV/m}$. The muon beam is accelerated from $275\mathrm{MeV}$ to more than $10\mathrm{GeV}$ within $22.5\mathrm{ps}$. Choosing the injection time of the muon beam in a proper range, the longitudinal spatial distribution and the energy distribution of the accelerated muon beam are compressed. The efficiency of the energy transfer from the driven electron beam to the muon beam can reach $20\%$. The prompt acceleration scheme is a promising avenue to bring the expected neutrino factory and the muon collider into reality and to catch new physics beyond the Standard Model.

physics.acc-ph↗

arXiv2020

Generation of highly-polarized high-energy brilliant $\gamma$-rays via laser-plasma interaction

Generation of highly-polarized high-energy brilliant $\gamma$-rays via laser-plasma interaction has been investigated in the quantum radiation-reaction regime. We employ a quantum-electrodynamics particle-in-cell code to describe spin-resolved electron dynamics semiclassically and photon emission and polarization quantum mechanically in the local constant field approximation. As an ultrastrong linearly-polarized (LP) laser pulse irradiates on a near-critical-density (NCD) plasma followed by an ultrathin planar aluminum target, the electrons in NCD plasma are first accelerated by the driving laser to ultrarelativistic energies, and then head-on collide with reflected laser pulse by the aluminum target, emitting brilliant LP $\gamma$-rays due to nonlinear Compton scattering with an average polarization of about 70\% and energy up to hundreds of MeV. By comparison, as a conical gold target filled with NCD plasma is employed, the linear polarization degree, collimation and brilliance of emitted $\gamma$-ray beam are all significantly improved due to the enhanced strong laser-driven quasi-static magnetic field in plasmas. Such $\gamma$-rays can be produced with currently achievable laser facilities and find various applications in high-energy physics and astrophysics.

physics.plasm-ph↗

arXiv2018

Collimated GeV attosecond electron-positron bunches from a plasma channel driven by 10 PW lasers

High-energy positrons and bright {\gamma}-ray sources are unique both for fundamental research and practical applications. However, GeV electron-positron pair jets and {\gamma}-ray flashes are still hardly produced in laboratories. Here we demonstrate that, by irradiating two 10 PW-scale laser pulses onto a near-critical density plasma channel, highly-directional GeV electron-positron pairs and bright {\gamma}-ray beams can be efficiently generated. Three-dimensional particle-in-cell simulations show that GeV positron jets show high density (8*10^21/cm^3), attosecond duration (400 as) and a divergence angle of 14{\deg}. Additionally, ultrabright (2*10^25 photons/s/mm2/mrad2/0.1%BW) collimated attosecond (370 as) {\gamma}-ray flashes with a laser energy conversion efficiency of 5.6% are emitted. Once realized in experiment, it may open up new possibilities for a wide variety of applications.

physics.plasm-ph↗

arXiv2018

Generation of GeV positron and {\gamma}-photon beams with controllable angular momentum by intense lasers

Although several laser-plasma-based methods have been proposed for generating energetic electrons, positrons and {\gamma}-photons, manipulation of their microstructures is still challenging, and their angular momentum control has not yet been achieved. Here, we present and numerically demonstrate an all-optical scheme to generate bright GeV {\gamma}-photon and positron beams with controllable angular momentum by use of two counter-propagating circularly-polarized lasers in a near-critical-density plasma. The plasma acts as a "switching medium", where the trapped electrons first obtain angular momentum from the drive laser pulse and then transfer it to the {\gamma}-photons via nonlinear Compton scattering. Further through the multiphoton Breit-Wheeler process, dense energetic positron beams are efficiently generated, whose angular momentum can be well controlled by laser-plasma interactions. This opens up a promising and feasible way to produce ultra-bright GeV {\gamma}-photons and positron beams with desirable angular momentum for a wide range of scientific research and applications.

physics.plasm-ph↗

arXiv2018

Stable attosecond electron bunches from a nanofiber driven by Laguerre-Gaussian lasers

Generation of attosecond bunches of energetic electrons offers significant potential from ultrafast physics to novel radiation sources. However, it is still a great challenge to stably produce such electron beams with lasers, since the typical sub-femtosecond electron bunches from laser-plasma interactions either carry low beam charge, or propagate for only several tens of femtoseconds. Here we propose an all-optical scheme for generating dense attosecond electron bunches via the interaction of an intense Laguerre-Gaussian (LG) laser pulse with a nanofiber. The stable bunch train results from the unique field structure of a circularly polarized LG laser pulse, enabling each bunch to be phase-locked and accelerated forward with low divergence, high beam charge and large beam-angular-momentum. This paves the way for wide applications in various fields, e.g., ultrabrilliant attosecond x/$\gamma$-ray emission.

physics.plasm-ph↗

arXiv2009

Radiation reaction effects on ion acceleration in laser foil interaction

Radiation reaction effects on ion acceleration in laser foil interaction are investigated via analytical modeling and multi-dimensional particle-in-cell simulations. We find the radiation effects are important in the area where some electrons move backwards due to static charge separation field at the laser intensity of 1022 W=cm2. Radiation reaction tends to impede these backwards motion. In the optical transparency region ion acceleration is enhanced when the radiation effects are considered.

physics.plasm-ph↗