- 标题
- 摘要
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- 实验方案
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Design and commissioning of an ion guide system for In-Gas Laser Ionization and Spectroscopy experiments
摘要： Radio-frequency (RF) ion guides, also known as Linear Paul Traps, are powerful devices to efficiently transport ion beams from high to low pressure regions while keeping good ion optical properties. A set of ion guides comprising three different RF quadrupole (RFQ) structures has been designed using ion-trajectory simulations to improve the performance of the In-Gas Laser Ionizations and Spectroscopy (IGLIS) technique currently under development at KU Leuven. Results of the commissioning tests for the total transport efficiency and transient time through the ion guides as well as the longitudinal energy spread and transverse emittance are found to be in agreement with ion trajectory simulations considering a realistic ion-atom interaction potential.
关键词： Radioactive ion beams,Ion transport,Radiofrequency quadrupole,Nuclear physics,Ion guide,Laser spectroscopy,Exotic nuclei
更新于2025-09-16 10:30:52
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Design of Neutron Imaging Aperture for Inertial Confinement Fusion in Laser Fusion Research Center
摘要： Neutron Imaging System (NIS) has been used to image the burn volume and cold fuel volume of imploding fusion capsules. In this work, we present a design of neutron imaging aperture for inertial con?nement fusion in Laser Fusion Research Center. Since the total neutron yield should be less than 1014, the penumbral aperture has been chosen. A geometric model has been developed to assess the performance of the neutron imaging system, including the spatial resolution, the ?eld of view and the signal-to-noise ratio. This model reproduces the performances of neutron image systems on OMEGA. The spatial resolution of designed NIS is about 22 μm for a ?eld of view of 250 μm. The signal-to-noise ratio can be better than 10, if the neutron yield is higher than 1013.
关键词： Nuclear instruments and methods for hot plasma diagnostics,Plasma diagnostics - interferometry, spectroscopy and imaging
更新于2025-09-16 10:30:52
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Table-top nuclear magnetic resonance system for high-pressure studies with <i>in situ</i> laser heating
摘要： High pressure Nuclear Magnetic Resonance (NMR) is known to reveal the behavior of matter under extreme conditions. However, until now, significant maintenance demands, space requirements, and high costs of superconducting magnets render its application unfeasible for regular modern high pressure laboratories. Here, we present a table-top NMR system based on permanent Halbach magnet arrays with a diameter of 25 cm and height of 4 cm. At the highest field of 1013 mT, 1H-NMR spectra of ice VII have been recorded at 25 GPa and ambient temperature. The table-top NMR system can be used together with double sided laser heating setups. Feasibility of high-pressure high-temperature NMR was demonstrated by collecting 1H-NMR spectra of H2O at 25 GPa and 1063(50) K. The change in the signal intensity in a laser-heated NMR diamond anvil cell has been found to yield a convenient way for temperature measurements.
关键词： diamond anvil cell,laser heating,Halbach magnet,Nuclear Magnetic Resonance,high-pressure
更新于2025-09-16 10:30:52
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Radiology, Lasers, Nanoparticles and Prosthetics || 7. Positron emission tomography
摘要： Positron emission tomography (PET) is a nuclear imaging modality used in clinics for cardiologic, neurologic, and oncologic studies. The PET method is based on the annihilation of positrons and electrons via converting their rest mass into two γ-photons flying in opposite directions. These two γ-photons are detected in a fashion similar to SPE or SPECT. Positron annihilation spectroscopy (PAS) is also used in condensed matter physics for determining the density and diffusivity of defects in solids. PAS is the opposite effect to pair production, which occurs when photons interact with nuclei at photon energies beyond 1 MeV. Pair production is important for cancer treatment with very hard x-rays, discussed in Chapter 9. However in this chapter we consider PET as an analytic tool.
关键词： nuclear imaging,PET,positron annihilation spectroscopy,γ-photons,Positron emission tomography,PAS
更新于2025-09-16 10:30:52
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Laser detection of nuclear spin isomers of ethylene molecules
摘要： We report the making of a double-beam laser spectrometer to measure absorption spectra in the n5 + n9 combination vibrational band of ethylene in the region of l = 1.6 mm. The spectrometer is used to find a portion of the spectrum that has well-resolved absorption lines of all four nuclear spin isomers of ethylene molecules. The rotational quantum numbers of these absorption lines and the nuclear spin isomers of ethylene molecules responsible for them are identified.
关键词： spectroscopy of ethylene molecules,nuclear spin isomers of molecules,laser spectroscopy
更新于2025-09-16 10:30:52
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Laser-Ablative Synthesis of Isotope-Enriched Samarium Oxide Nanoparticles for Nuclear Nanomedicine
摘要： Nuclear nanomedicine is an emerging field, which utilizes nanoformulations of nuclear agents to increase their local concentration at targeted sites for a more effective nuclear therapy at a considerably reduced radiation dosage. This field needs the development of methods for controlled fabrication of nuclear agents carrying nanoparticles with low polydispersity and with high colloidal stability in aqueous dispersions. In this paper, we apply methods of femtosecond (fs) laser ablation in deionized water to fabricate stable aqueous dispersion of 152Sm-enriched samarium oxide nanoparticles (NPs), which can capture neutrons to become 153Sm beta-emitters for nuclear therapy. We show that direct ablation of a 152Sm-enriched samarium oxide target leads to widely size- and shape-dispersed populations of NPs with low colloidal stability. However, by applying a second fs laser fragmentation step to the dispersion of initially formed colloids, we achieve full homogenization of NPs size characteristics, while keeping the same composition. We also demonstrate the possibility for wide-range tuning of the mean size of Sm-based NPs by varying laser energy during the ablation or fragmentation step. The final product presents dispersed solutions of samarium oxide NPs with relatively narrow size distribution, having spherical shape, a controlled mean size between 7 and 70 nm and high colloidal stability. The formed NPs can also be of importance for catalytic and biomedical applications.
关键词： nuclear nanomedicine,samarium (Sm) oxide nanoparticles,pulsed laser ablation in liquids,femtosecond laser ablation and fragmentation
更新于2025-09-16 10:30:52
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Polarization of high-order harmonic generation in oriented molecules with intense ultrashort laser pulses
摘要： Using numerical solutions of the time-dependent Schr?dinger equation we show that in oriented molecules one can control the polarization of molecular high-order harmonic generation (MHOHG) by intense linearly polarized pulses. For oriented triangular molecules, H3+/H32+, one obtains even-order harmonics perpendicular to the laser polarization, whereas all odd-order harmonics have the same polarization as the laser polarization. For H2+/H2 we show that only odd-order harmonics are generated for any orientation and their polarization is nearly parallel to the molecular axis. We describe these phenomena based on perturbation theory. Redshifts of the MHOHG spectra occur due to laser induced electron localization in non-Born-Oppenheimer dissociating molecules, reflecting the effect of nuclear dynamics. The numerical results illustrate the sensitivity of harmonic polarization to molecular geometry and nuclear dynamics.
关键词： oriented molecules,ultrashort laser pulses,perturbation theory,nuclear dynamics,high-order harmonic generation,polarization
更新于2025-09-16 10:30:52
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In situ gas monitoring by fiber-coupled Raman spectrometry for H2-risk management in nuclear containment during a severe nuclear accident
摘要： An underground nuclear explosion (UNE) can generate a shock wave that lofts surface material, resulting in surface changes that might be detectable. The Comprehensive Nuclear Test-Ban Treaty (CTBT) allows ground and airborne spectral and thermal imaging to help locate such events. Landsat 5 data on the 1998 Indian and Pakistani tests are used here to demonstrate that there are detectable changes in surface features which might be used to localize an underground nuclear test and to develop change detection techniques speci?c to the use of satellite data to support a CTBT on-site inspection. Landsat 5 has been active for over 20 years providing repeat coverage of the Earth’s surface every 16 days. Most locations have Landsat data available for a variety of dates, allowing for statistical analysis of the data to understand temporal trends and data variability on a pixel-by-pixel basis. Given the right conditions, these usual patterns of change (such as seasonal changes or weathering) can be discerned from unusual patterns of change, such as features relating to a UNE. This paper extends known change detection techniques to a temporal series of data and shows that multispectral change detection can be used to help localize a UNE.
关键词： multispectral change detection,Comprehensive Nuclear Test-Ban Treaty (CTBT),covariance matrix Landsat 5,Mahalanobis distance
更新于2025-09-16 10:30:52
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Nuclear Astrophysics with Lasers
摘要： A systematic program of investigations of nuclear reactions in laser-produced plasmas is addressed. Such reactions provide an important diagnostic tool for probing the dynamics and thermodynamics in the plasma and understanding laser ion acceleration and neutron production mechanisms. The goal will be to reach the level of knowledge that allows the measurement of fundamental nuclear cross-sections at low and high particle densities. The quantitative measurement of fusion probabilities in hot and dense plasmas will contribute significantly to our comprehension of stellar composition and evolution and will provide important information for development of fusion energy production and applications such as medical isotope production and compact neutron source development. All of these are some of the main goals of the European Extreme Light Infrastructure (ELI), the Shanghai Superintense Ultrafast Laser Facility, and the Station of Extreme Light in China and similar projects in other countries.
关键词： Fusion Reactions,Nuclear Astrophysics,Lasers,Cross-sections,Plasma
更新于2025-09-16 10:30:52
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MELISSA: Laser ion source setup at CERN-MEDICIS facility. Blueprint
摘要： The Resonance Ionization Laser Ion Source (RILIS) has become an essential feature of many radioactive ion beam facilities worldwide since it offers an unmatched combination of efficiency and selectivity in the production of ion beams of many different chemical elements. In 2019, the laser ion source setup MELISSA is going to be established at the CERN-MEDICIS facility, based on the experience of the workgroup LARISSA of the University Mainz and CERN ISOLDE RILIS team. The purpose is to enhance the capability of the radioactive ion beam supply for end users by optimizing the yield and the purity of the final product. In this article, the blueprint of the laser ion source, as well as the key aspects of its development and operation are presented.
关键词： Laser resonance ionization,Lanthanides,Ti:sapphire,MELISSA,Isotope separation,Nuclear medicine,CERN-MEDICIS
更新于2025-09-16 10:30:52