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Measuring the difference in nuclear charge radius of Xe isotopes by EUV spectroscopy of highly charged Na-like ions
摘要： The difference in the mean-square nuclear charge radius of xenon isotopes was measured utilizing a method based on extreme ultraviolet spectroscopy of highly charged Na-like ions. The isotope shift of the Na-like D1 (3s 2S1/2 ? 3p 2P 1/2) transition between the 124Xe and 136Xe isotopes was experimentally determined using the electron-beam ion-trap facility at the National Institute of Standards and Technology. The mass-shift and the ?eld-shift coef?cients were calculated with enhanced precision by the relativistic many-body perturbation theory and multicon?guration Dirac-Hartree-Fock method. The mean-square nuclear charge radius difference was found to be δ(cid:2)r 2(cid:3)136,124 = 0.269(42) fm2. Our result has smaller uncertainty than previous experimental results and agrees with the literature values.
关键词： Na-like ions,EUV spectroscopy,xenon isotopes,isotope shift,nuclear charge radius
更新于2025-09-23 15:21:01
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High-precision collinear laser spectroscopy at the Collinear Apparatus for Laser Spectroscopy and Applied Physics (COALA)
摘要： COALA is a new offline collinear laser spectroscopy setup for high-precision measurements and development work at TU Darmstadt, Germany. An introduction to the technique and the experimental setup is given and an overview of current projects with recent results is presented. The idea of a novel all-optical absolute charge radius determination is discussed.
关键词： Nuclear charge radii,High voltage evaluation,High precision spectroscopy,Collinear laser spectroscopy
更新于2025-09-23 15:21:01
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Numerical simulations on laser absorption enhancement in hybrid metallo-dielectric nanostructured targets for future nuclear astrophysics experiments
摘要： The linear electromagnetic interaction between innovative hybrid metallo-dielectric nanostructured targets and laser in visible and IR range is investigated through numerical simulations. The obtained results rely on the optimization of a target based on metallic nanowires (NWs) to enhance light absorption in the visible range of the electromagnetic spectrum. The NWs are grown within the ordered nanoholes of an alumina substrate, thus, forming a plasmonic lattice with triangular symmetry. The remaining volume of the nanoholes on top of the NWs is sealed with a transparent layer of aluminum oxide that is suitable to be chemically modified for containing about 25% of deuterium atoms. The study presented here is carried out within the framework of a scientific program named PLANETA (Plasmonic Laser Absorption on Nano-Engineered Targets) aiming at investigating new laser–matter interaction schemes in the ns domain and for nuclear fusion purposes, involving especially the D–D reaction.
关键词： D–D reaction,metallo-dielectric nanostructured targets,nuclear astrophysics,laser absorption,plasmonic lattice
更新于2025-09-23 15:21:01
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Ultrafast molecular clock with subcycle resolution from correlated electron-nuclear spectra
摘要： To probe ultrafast molecular dynamics, a high spatial-temporal resolution is of crucial importance. Different from the usual pump-probe method, here we present a probing scheme to clock the molecular dynamics with subcycle precision by investigating the correlated electron-nuclear energy spectra in a multicycle laser pulse. The molecular dynamics in the tunneling ionization regime are numerically simulated in a two-dimensional H+2 non-Born-Oppenheimer model. It is found that the asymmetry between the yields of electrons ionized in opposite directions along the laser polarization axis shows peaks and valleys alternately as a function of the nuclear energy. Our results show that the temporally resolved asymmetry of the ionization of electrons can be used as a clock to probe the nuclear Coulomb explosion channel with subcycle resolution and extract the corresponding molecular dynamics accurately. This method can be used even when the intensity averaging of the focused laser beam is considered.
关键词： tunneling ionization regime,subcycle resolution,non-Born-Oppenheimer model,correlated electron-nuclear spectra,ultrafast molecular dynamics
更新于2025-09-23 15:21:01
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Note: Complementary approach for radiation dosimetry with Ag <sup>+</sup> -activated phosphate glass
摘要： Silver ion-activated phosphate glass (Ag+-glass) has a good potential for application to radiation dosimetry in various radiation fields due to its multifunctional properties as a detector. The Ag+-glass provides three independent signals of radiophotoluminescence, optical absorption, and nuclear track. The combination of these signals allows the dynamic range of the measured dose (10 μGy–10 kGy) and linear energy transfer (<10 keV/μm and >1 MeV/μm) to be widened.
关键词： optical absorption,radiophotoluminescence,Ag+-activated phosphate glass,radiation dosimetry,nuclear track
更新于2025-09-23 15:21:01
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A pump-probe scheme with a single chirped pulse to image electron and nuclear dynamics in molecules
摘要： A single chirped few-femtosecond pulse can be used to control and image coupled electron-nuclear dynamics. Using full ab initio simulations of the simplest molecule, H+2, as a prototype target, we show that for intermediate values of the chirp, interference between sequential and direct contributions enables significant control over ionization yields, even when taking into account the effective decoherence introduced by nuclear motion and the presence of an electronic continuum. For larger values of the chirp, the single chirped pulse reproduces a classical pump-probe setup, with the chirp parameter mapping an effective time delay between the pumping and probing frequencies of the pulse. After demonstrating this numerically, we present a full analytical solution for the two-photon ionization amplitudes that provides an intuitive analogy between the molecular dynamics induced by a single chirped pulse and a traditional pump-probe setup.
关键词： pump-probe scheme,attosecond science,chirped pulse,molecular ionization,electron-nuclear dynamics
更新于2025-09-23 15:21:01
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MeV photon imaging with robotic sample positioning at a research reactor
摘要： This paper summarizes the development and demonstration of an X-ray and gamma-ray radiography capability using a TRIGA MARK-II reactor. Photons are a combination of Bremsstrahlung X-rays and gamma rays from fission and radioactive decay. The energy spectrum of the facility was analyzed with a NaI(Tl) scintillator detector. A digital X-ray camera for use with MeV-range photons images a duplex wire-type penetrameter to analyze unsharpness and spatial resolution. An industrial manipulator precisely positions the sample, which allows objects to have larger dimensions than the detector’s field-of-view. Future work includes performing computed tomography to create 3-dimensional representations of objects.
关键词： Nuclear research reactor,Gamma,X-ray,Non-destructive testing,Radiation imaging,Robotics
更新于2025-09-23 15:21:01
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Laser-induced acceleration of Helium ions from unpolarized gas jets
摘要： In order to develop a laser-driven spin-polarized 3He-ion beam source available for nuclear-physics experiments as well as for the investigation of polarized nuclear fusion, several challenges have to be overcome. Apart from the provision of a properly polarized 3He gas-jet target, one of the biggest milestones is the demonstration of the general feasibility of laser-induced ion acceleration out of gas-jet targets. Of particular importance is the knowledge about the main ion-emission angles as well as the achievable ion-energy spectra (dependent on the optimal set of laser and target parameters). We report on the results of such a feasibility study performed at PHELIX, GSI Darmstadt. Both 3He- and 4He-gas jets (ngas ～ 1019 cm?3) were illuminated with high-intensity laser pulses, ). The main ion-emission angles could be identi?ed (±90° with respect to the laser-propagation direction) and the ion-energy spectra for all ion species could be extracted: for the ions were 4.65 MeV (with a optimal laser and target parameters, the high-energy cut-offs for He + + 2 ,1 ), respectively. ) and 3.27 MeV (D normalized energy uncertainty of D ( 10 W cm =-? ? 1 =-? ? 1 0.055 0.033 ? ~ 19
关键词： laser-driven He-ion acceleration,spin-polarized ion source,polarized nuclear fusion
更新于2025-09-23 15:19:57
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Nonadiabatic Dynamics in a Laser Field: Using Floquet Fewest Switches Surface Hopping To Calculate Electronic Populations for Slow Nuclear Velocities
摘要： We investigate two well-known approaches for extending the fewest switches surface hopping (FSSH) algorithm to periodic time-dependent couplings. The first formalism acts as if the instantaneous adiabatic electronic states were standard adiabatic states, which just happen to evolve in time. The second formalism replaces the role of the usual adiabatic states by the time-independent adiabatic Floquet states. For a set of modified Tully model problems, the Floquet FSSH (F-FSSH) formalism gives a better estimate for both transmission and reflection probabilities than the instantaneous adiabatic FSSH (IA-FSSH) formalism, especially for slow nuclear velocities. More importantly, only F-FSSH predicts the correct final scattering momentum. Finally, in order to use Floquet theory accurately, we find that it is crucial to account for the interference between wavepackets on different Floquet states. Our results should be of interest to all those interested in laser-induced molecular dynamics.
关键词： Electronic Populations,Nonadiabatic Dynamics,Floquet Fewest Switches Surface Hopping,Slow Nuclear Velocities,Laser Field
更新于2025-09-23 15:19:57
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P1217Zirconium-89 labelled probe for molecular imaging of inflammation in experimental atherosclerosis
摘要： Early detection of in?amed atherosclerotic lesions by molecular imaging might improve risk assessment beyond that of vascular stenosis and plaque morphology imaging, and improve the clinical management of high-risk patients. To target the key features of unstable atherosclerotic lesions, we studied the feasibility of our radiotracer, based on modi?ed human serum albumin (HSA), to identify in?amed atherosclerotic lesions by in vivo molecular imaging. We applied a maleylated HSA (Mal-HSA) probe, recognised by scavenger receptors on macrophages, in an experimental imaging study of atherosclerosis. Mal-HSA was coupled with a positron-emitting metal ion, Zirconium-89 (89Zr). The targeting potential of this probe was evaluated and compared with unspeci?c 89Zr-HSA and 18F-FDG in a mouse model of atherosclerosis (Apoe?/?, n=22) and compared with wild-type (WT) mice (C57BL/6, n=21) as controls. Radiotracer accumulation in the aortic arch was analysed in vivo by the fusion of positron emission tomography–magnetic resonance imaging (PET-MRI), radiotracer bio-distribution was measured ex vivo by gamma counter, and plaque uptake was evaluated by phosphor imaging (PI) autoradiography (ARG). PET-MRI, gamma counter measurements, and PI-ARG showed the accumulation of 89Zr-Mal-HSA in the atherosclerotic lesions of Apoe?/? mice. The maximum standardised uptake value (SUVmax) for 89Zr-Mal-HSA at 16 and 20 weeks were 26% and 20% higher (P<0.05) in Apoe?/? mice than control WT mice, whereas no difference in SUVmax was found for 18F-FDG in the same animals. 89Zr-Mal-HSA uptake in the aorta as evaluated by gamma counter 48 h post-injection was 32% higher (P<0.01) for Apoe?/? mice compared to WT mice, and the aorta-to-blood ratio was 10-fold higher (P<0.001) for 89Zr-Mal-HSA compared with unspeci?c 89Zr-HSA. HSA probes were mainly distributed to the liver, spleen, kidneys, bone and lymph nodes. The PI-ARG results corroborated the PET and gamma counter measurements, showing higher accumulation of 89Zr-Mal-HSA in the aortas of Apoe?/? mice compared to WT mice; 9.4±1.4 vs 0.8±0.3% (P<0.001). The modi?ed HSA-based radiotracer showed in vivo targeting of in?amed atherosclerotic lesions of mouse aorta, which could also be veri?ed ex vivo. 89Zr-Mal-HSA seems to be a promising diagnostic tool for the identi?cation of vascular in?ammation. Further methodological studies are needed to verify its applicability for detecting rupture-prone plaques.
关键词： atherosclerosis,inflammation,Zirconium-89,PET-MRI,molecular imaging,Nuclear cardiology
更新于2025-09-23 15:19:57