Search

Post-neutron mass yield distribution in the epi-cadmium neutron-induced fission of 233U has been carried out by measuring the cumulative yields of various fission products within the mass ranges of 77 to 117 and 123 to 153 using an off-line gamma-ray spectrometric technique. Independent yields of a few fission products were also measured by using the same technique. Charge distribution correction has been applied on cumulative yields to obtain the post-neutron mass yields. The mass yield distribution parameters such as full-width at tenth-maximum of light and heavy mass wings, the average light mass and heavy mass , and the average number of neutrons <ν> were obtained. The spectrum average neutron energy is 1.9 MeV. Thus, the role of excitation energy on the nuclear structure effect was examined by comparing the mass yield data in between the epi-cadmium and thermal neutron–induced fission of 233U. [ABSTRACT FROM AUTHOR]

One of the fundamental processes in nuclear physics is nuclear excitation by electron capture (NEEC). Having been proposed theoretically for almost 50 years, the experimental confirmation of NEEC is still missing, making it imperative to validate this process. In this paper, we propose a new experimental method based on the anti-coincidence principle to search for the long-anticipated NEEC phenomenon, which involve heavy-ion storage rings. Our calculations indicate that the proposed experimental setup, storage ring, have the potential to surmount background noise, particularly Radiative Recombination (RR) and Coulomb Excitation (CE), and offer a high likelihood of discovering the long- awaited NEEC process. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV) photolysis of nitrite ions (NO2−) in aqueous solutions produces a suite of radicals, viz., NO·, O−, ·OH, and ·NO2. The O− and NO· radicals are initially formed from the dissociation of photoexcited NO2−. The O− radical undergoes reversible proton transfer with water to generate ·OH. Both ·OH and O− oxidize the NO2− to ·NO2 radicals. The reactions of ·OH occur at solution diffusion limits, which are influenced by the nature of the dissolved cations and anions. Here, we systematically varied the alkali metal cation, spanning the range from strongly to weakly hydrating ions, and measured the production of NO·, ·OH, and ·NO2 radicals during UV photolysis of alkaline nitrite solutions using electron paramagnetic resonance spectroscopy with nitromethane spin trapping. Comparing the data for the different alkali cations revealed that the nature of the cation had a significant effect on production of all three radical species. Radical production was inhibited in solutions with high charge density cations, e.g., lithium, and promoted in solutions containing low charge density cations, e.g., cesium. Through complementary investigations with multinuclear single pulse direct excitation nuclear magnetic resonance (NMR) spectroscopy and pulsed field gradient NMR diffusometry, cation-controlled solution structures and extent of NO2− solvation were determined to alter the initial yields of ·NO and ·OH radicals as well as alter the reactivity of NO2− toward ·OH, impacting the production of ·NO2. The implications of these results for the retrieval and processing of low-water, highly alkaline solutions that comprise legacy radioactive waste are discussed. [ABSTRACT FROM AUTHOR]

Nuclear photonics is a emerging field of science which combines research with new generation γ -ray sources based on traditional and laser-based electron accelerators. Here, we discuss isomeric studies carried out with γ -ray beams having either continuous, or quasi-monochromatic photon spectra. In experiments with high-power lasers, intense secondary radiation sources are generated. Such experiments explore isomer population or de-excitation in plasma environments. Laser-accelerated particle beams with high charge also facilitate high-energy nuclear excitations, leading to efficient production of nuclear isomers with higher lying isomeric state (reaching MeV energy level) within very-short time scales. The population of isomeric states is a sensitive diagnostic method for characterization of the laser-driven secondary radiation sources. [ABSTRACT FROM AUTHOR]

Today's most precise timekeeping is based on optical atomic clocks. However, those could potentially be outperformed by a nuclear clock, based on a nuclear transition instead of an atomic shell transition. Such a nuclear clock promises intriguing applications in applied as well as fundamental physics, ranging from geodesy and seismology to the investigation of possible time variations of fundamental constants and the search for dark matter. Only one nuclear state is known so far that could drive a nuclear clock: the "Thorium Isomer" 229 m Th, i.e., the isomeric first excited state of 229 Th, representing the lowest nuclear excitation so far reported in the landscape of nuclear isotopes. Indirectly conjectured to exist already in 1976, decades of experimental efforts were dedicated to unambiguously identify this elusive nuclear state and to characterize its properties. However, for 40 years, these efforts remained inconclusive. The turning point was marked by the first direct detection of 229 m Th via its internal conversion decay branch in 2016. Since then, remarkable progress could be achieved in characterizing the properties and decay parameters. The half-life of the neutral isomer was determined, the hyperfine structure was measured via collinear laser spectroscopy, providing information on nuclear moments and the nuclear charge radius and also the excitation energy of the isomer could be directly determined with different techniques. In a recent experiment at CERN's ISOLDE facility, the long-sought radiative decay of the Thorium isomer could be observed for the first time via implantation of (β -decaying) 229 Ac into a vacuum-ultraviolet (VUV) transparent crystal and subsequent fluorescence detection in a VUV spectrometer. Thus, the excitation energy of 229 m Th could be determined with unprecedented precision to 8.338(24) eV, corresponding to a wavelength of 148.71(42) nm. These achievements, together with ongoing laser developments for the required VUV wavelength, open the door toward a laser-driven control of the isomeric transition and thus to the development of an ultra-precise nuclear frequency standard. [ABSTRACT FROM AUTHOR]

In seismic nuclear monitoring, attenuation models are important prerequisites for reliably estimating the explosive yield in an uncalibrated region without the occurrence of standard events. The seismic moment obtained by fitting source spectra is related to the source energy. This approach is appropriate for estimating yield, as the attenuation effects on the propagation path can be accurately considered. In this study, we collected 2022 vertical component waveforms in and around the Korean Peninsula from May 2010 to May 2022 to construct a high-resolution broadband Lg-wave attenuation model and inverted the Lg-wave source excitation spectra of the nuclear explosion simultaneously with attenuation correction. We obtained the scalar seismic moments by fitting the theoretical source spectra based on the Brune (J. Geophys. Res., 1970, 75, 4997-5009) model. Under the given emplacement conditions and burial depths, the seismic moments can be used to estimate yields of the North Korean nuclear tests, which are 4.6, 8.5, 19.9, 20.9, 24.7, and 337.4 kt for six nuclear explosions that occurred between 2006 and 2017. Our results are consistent with those obtained from previous teleseismic observations. [ABSTRACT FROM AUTHOR]

The cumulative and independent yields of various fission products within the mass range of 78 to 157 have been measured in the epi-cadmium neutron–induced fission of 238Pu by using an off-line γ-ray spectrometric technique. The lower yield of 136I than the usual trend indicates the formation of delayed neutron emitter 137I. From the cumulative yields, post-neutron mass chain yields were obtained by using the charge distribution correction. From the mass yield data, the peak-to-valley (P/V) ratio, the full-width at tenth-maximum of light and heavy mass wings, the average light mass and heavy mass as well as the average number of neutrons <ν> emitted were obtained. The mass chain yield data in the 238Pu(n,f) reaction were compared with similar data of the 238Pu(nth,f) reaction to examine the role of excitation energy on the nuclear structure effect and P/V ratio. [ABSTRACT FROM AUTHOR]

One of the fundamental processes in nuclear physics is nuclear excitation by electron capture (NEEC). Having been proposed theoretically for almost 50 years, the experimental confirmation of NEEC is still missing, making it imperative to validate this process. In this paper, we propose a new experimental method based on the anti-coincidence principle to search for the long-anticipated NEEC phenomenon, which involve heavy-ion storage rings. Our calculations indicate that the proposed experimental setup, storage ring, have the potential to surmount background noise, particularly Radiative Recombination (RR) and Coulomb Excitation (CE), and offer a high likelihood of discovering the long-awaited NEEC process.

Coupled pairs of spin-1/2 nuclei support one singlet state and three triplet states. In many circumstances, the nuclear singlet order, defined as the difference between the singlet population and the mean of the triplet populations, is a long-lived state that persists for a relatively long time in solution. Various methods have been proposed for generating singlet order, starting from nuclear magnetization. This requires the stimulation of singlet-to-triplet transitions by modulated radiofrequency fields. We show that a recently described pulse sequence, known as PulsePol [Schwartz et al., Sci. Adv., 4, eaat8978 (2018)], is an efficient technique for converting magnetization into long-lived singlet order. We show that the operation of this pulse sequence may be understood by adapting the theory of symmetry-based recoupling sequences in magic-angle-spinning solid-state nuclear magnetic resonance (NMR). The concept of riffling allows PulsePol to be interpreted by using the theory of symmetry-based pulse sequences and explains its robustness. This theory is used to derive a range of new pulse sequences for performing singlet–triplet excitation and conversion in solution NMR. Schemes for further enhancing the robustness of the transformations are demonstrated. [ABSTRACT FROM AUTHOR]

Collective nuclear spin excitations, called nuclear spin waves or magnons, are enabled in strongly magnetic materials by the hyperfine coupling of the nuclear and electronic spins in an atom and the exchange interaction between electronic spins of neighboring atoms. Nuclear spin waves attracted the interest of theoretical and experimental researchers worldwide about four to five decades ago and then waned. Very recently, two experimental reports of nuclear spintronic effects in the canted antiferromagnet MnCO3 have shown that spin currents can be generated using nuclear spin states, bridging two quite separate worlds, one of nuclear spin excitations and the other of spintronics. In this Tutorial, we briefly review the basic concepts and properties of nuclear spin waves in ferro- and antiferromagnetic (AF) materials and present a few significant experimental results obtained some time ago with the uniaxial anisotropy AF MnF2 and the cubic anisotropy AF RbMnF3 and compare them with theory. We also briefly present the recent experimental observations of the nuclear spin pumping effect and the nuclear spin Seebeck effect in the canted antiferromagnet MnCO3. Other possible AF candidates for studies of nuclear spintronic effects are discussed. [ABSTRACT FROM AUTHOR]

Nuclear-pumped lasers (NPL) are lasers in which excited active laser environment caused by nuclear reaction. Such lasers need ionizing radiation shielding for mixed neutron and gamma fields. In this work, a shielding system for NPL was designed for an NPL that uses 10B(n,α)7Li. In fact, we have used MCNPX 2.6.0 Monte Carlo code and the thermal neutron flux as 1 × 1016 n.cm-2.s-1 for excitation reaction. Such a large neutron flux can be obtained from a reactor source or a heavy ion accelerator. For this work, 10B fuel is covered on the surface of a rectangular cube aluminum shell by using the Monte Carlo method. In the design of the shielding, combinations with different materials have been used with various arrangements in three layers. According to the simulation, the arrangement of Fe2B-BPE-Pb is a suitable protection compound for such lasers. [ABSTRACT FROM AUTHOR]

The cumulative and independent yields of various fission products within the mass range of 83 to 117 and 123 to 157 have been measured in the epi-cadmium neutron–induced fission of 241Pu using an off-line γ-ray spectrometric technique. From the cumulative yields, post-neutron mass yields were obtained using the charge distribution correction. The full-width at tenth maximum of the light and heavy mass wings and the average light mass and heavy mass , as well as the average number of neutrons <ν>, were obtained. The mass yields in the epi-cadmium– and thermal neutron–induced fission of 241Pu were compared to examine the role of excitation energy on the nuclear structure effect. [ABSTRACT FROM AUTHOR]

Strong octupole correlations have been observed in the low-lying states of atomic nuclei across various mass regions. In this paper, we provide an overview of Beyond Mean-Field (BMF) studies of nuclear octupole collective motions with Generator Coordinate Method (GCM) in combination with quantum-number projections that are implemented to restore the broken symmetries in nuclear mean-field states. We highlight recent developments within this framework and their applications to excitation spectra and electromagnetic transition rates in octupole-shaped nuclei and hypernuclei. We discuss the novel phenomena of nucleon clustering in light nuclei. Additionally, we explore the phase transition from octupole vibrations to rotational motions as spin increases in heavy nuclei. Lastly, we examine the status and future prospects of studies on octupole deformation effects in nuclear Schiff moments. These studies, along with the upper limits of atomic Electric Dipole Moment (EDM), impose stringent constraints on beyond-standard-model time-reversal-violating nucleon–nucleon interactions. [ABSTRACT FROM AUTHOR]

We present a near-infrared spectroscopic atlas of nearby, bright early-type galaxies with radio emission, containing 163 galaxies observed by the Palomar 200″ TripleSpec instrument, measuring the emission line fluxes for H, He, [Fe  ii ], and H2 and determined the nuclear excitation mechanisms. By stacking spectra, we deduced the H2 excitation temperature (1957 ± 182 K) and dominant excitation mechanism (thermal and shock heating combined) from the K -band emission line sequence. Stacking also produces an 'average' spectrum of absorption features and spectral indices from the literature; the CO12 absorption line index versus J − K colour shows a trend of stronger nuclear activity producing a weaker CO12 index and a redder (flatter) continuum. The correlations between the radio and the emission-line luminosities finds a trend with radio power; however, the large scatter in the upper limits shows that the two are not directly coupled and the duty cycles of SF and AGN activity are not synchronized. [ABSTRACT FROM AUTHOR]

Integral cross sections of the reactions 84Sr(n,p)84Rb, 86Sr(n,p)86Rb and 87Sr(n,n′)87mSr, over the fast neutron spectrum of a TRIGA reactor above 0.5 MeV, were measured for the first time. The results were used for integral tests of the evaluated excitation functions in the data libraries, ENDF/B-VIII.0, ROSFOND-2010, JEFF-3.3, JENDL-5 and TENDL-2021. The integral measurements are generally consistent with the integrated values within 12 %, except for a few cases. The two data libraries ENDF/B-VIII.0 and ROSFOND-2010 appear to need some improvement with regard to the reactions investigated in this work. [ABSTRACT FROM AUTHOR]

Results of numerical simulations for acceleration of proton beams at the irradiation of Al target by a superintense laser pulse are presented. There is a good agreement with the experimental data in a broad range of laser intensities from W/cm to W/cm at the fixed laser pulse duration. The obtained parameters of proton beams were used for calculation of the total yield of particles and neutrons for the nuclear reactions B() and B() C at the collisions of proton beams with boron targets. It is shown that the number of particles escaping boron target and arriving at track detectors is less than 5 of the total amount of particles, because the majority of these particles remain inside the target owing to ionization losses. The derived values of the yield of particles' which arrive at detectors are in good agreement with the experimental data. We also calculate the total yield of neutrons in the reaction B() C. It is found that, at the intensity W/cm of the picosecond laser pulse, the yield is equal to , this value is approximately of 3 of the total yield of particles. [ABSTRACT FROM AUTHOR]

The cumulative and independent yields of various fission products within the mass ranges of 83 to 117 and 123 to 161 have been measured in the epi-cadmium neutron-induced fission of 245Cm by using an off-line gamma-ray spectrometric technique. Charge distribution correction was applied on the cumulative yields to obtain the post-neutron mass yield distribution. From the mass yield distribution data, the full-width at tenth-maximum of light and heavy mass wings, average light mass and heavy mass , average neutron number <ν>, and peak-to-valley ratio were obtained for the first time. Comparison of mass yield distributions was made between the epi-cadmium and thermal neutron–induced fission of 245Cm to examine the role of excitation energy on the nuclear structure effect and P/V ratio. [ABSTRACT FROM AUTHOR]

The Brink–Axel hypothesis, which states that the photoabsorption cross section is independent of the excitation energy of a nuclear system, is an assumption used in nuclear structure studies and calculations of neutron-capture cross section for astrophysical applications. In the present work, using microscopic Configuration Interaction method, it is demonstrated that the dipole photoabsorption cross section at low energy is dependent on the excitation energy and deviations from the Brink-Axel hypothesis are particularily large for the ground state of an even-even system. It is also shown that the low-lying E1-strength, known as pygmy dipole resonance, is redistributed with the excitation energy of the initial state and strongly dependent on its structure. The consequences of these findings on the calculated neutron-capture cross sections are discussed. [ABSTRACT FROM AUTHOR]

Reflection spectra of cerium dioxide sintered samples were measured in the UV-visible range after irradiation with various heavy ions (2.4-MeV Cu, 5-MeV W, 10-MeV W, 36-MeV W, 100-MeV Kr, and 200-MeV Xe). Differential reflectance spectra of irradiated samples after subtraction of the reference sample spectrum are fit with six broad Gaussian bands centered at about 1.2, 2.2, 2.8, 4.0, 4.8, and 6.2 eV. The growth curves of most bands show a saturation behavior vs ion fluence. Reflection spectra are consistent with the UV-visible absorption spectra of electron-irradiated ceria single crystals for photon energies lower than 3.2 eV, corresponding to the optical gap. The spectra are tentatively analyzed on the basis of charge transfer bands and the 4f-5d transitions related to the Ce3+ ions in the distorted environment formed by irradiation. More insight into defect formation is given by the reflection spectra rather than the absorption ones due to the limitation in the absorption of the optical gap. These data are also discussed with reference to the radiation damage processes by electronic excitations and nuclear collisions in ceria. [ABSTRACT FROM AUTHOR]

The solid‐state nuclear optical clock based on 229Th‐doped crystal has great advantages in frequency stability, excitation and detection of nuclear transition, miniaturization, commercialization, and spaceborne ability of nuclear optical clock. Here, the potential of LiF crystal as a host for Th ions is predicted by theoretical calculation, and on this basis, the Th:LiF crystal is successfully grown experimentally for the first time. The theoretical results demonstrate that although the challenges of charge nonconservation and ion radius mismatch between Li+ and Th4+ ions exist, effective doping of thorium can still be achieved via energetically favorable charge compensation mechanisms in an F‐rich environment, and the transmittance of Th:LiF crystal in nuclear transition band will only have a slight decrease, smaller than that of pure LiF crystal. The experimental results prove that the doping concentration of Th:LiF crystal can reach about 8.3 × 1018 cm−3 and the transmittances of 1 mm thick Th:LiF and pure LiF crystal samples grown in similar conditions are ≈68% and 72% at 152.7 nm, respectively. The Th:LiF crystal with high doping concentration, high transmittance, and low background luminescence is expected to be a promising candidate for solid‐state nuclear optical clock materials. [ABSTRACT FROM AUTHOR]

With the aim of providing the complete demography of galaxies in the local Universe, including their nuclear properties, we present SPRING, a complete census of local galaxies limited to the spring quarter of the northern sky (10h < RA < 16h; 0° < Dec < 65°). The SPRING catalogue is a flux- and volume-limited sample (r < 17.7 mag, cz < 10 000 km s−1) of 30 597 galaxies, including the Virgo, Coma, and A1367 clusters. Images and spectra were individually examined to clear the sample from unwanted entries. To inspect possible secular and environmental dependencies of the various nuclear excitation properties (star-forming versus active nuclei), we performed a multi-dimensional analysis by dividing the total sample according to: (i) their position in the (NUV − i) versus Mstar diagram, (ii) the local galaxy density, (iii) the stellar mass, (iv) the halo mass of the group to which galaxies belong, and (v) the neutral hydrogen content. We present a new calibration of the optical diameter-based H I-deficiency parameter H Idef, employing a reference sample of isolated galaxies extracted from SPRING. At intermediate distances between Virgo and Coma, we identify a ring-like structure of galaxies constituted by three large filaments, each with a length of approximately 20h−1 Mpc, mostly composed of blue-cloud galaxies with stellar masses Mstar ≲ 1010 M⊙. The fraction of H I-deficient galaxies within the filament (∼30%) suggests that filaments are a transitioning environment between lower- and higher-overdensity environments in terms of H I content, as we find a clear progression from field galaxies to the filament and cluster galaxies for an increasing H Idef parameter. We classify the nuclear spectra according to the four-line Baldwin-Phillips-Terlevich (BPT) and the two-line EWHα versus [NII]/Hα (WHAN) diagnostic diagrams, and investigate the variation in the fraction of active nuclei hosts with stellar mass, as well as their colours and environments. We observe that the fraction of low-ionisation nuclear emitting regions (LINERs) is a steep function of stellar mass, for example, it is consistent with zero up to Mstar ≲ 109.5 M⊙ and becomes ∼40% for Mstar ≳ 1010.5 M⊙, whereas, for Mstar ≲ 109 − 9.5 M⊙, almost the entire spectroscopic sample is constituted of galaxies with star-forming nuclei. We investigate whether the nuclear-excitation fractions depend predominantly on the stellar mass or, conversely, on the galaxy environment. In general, we observe that the mass dependence of the fraction of Seyfert nuclei is not very sensitive to the galaxy environment, whereas the fraction of star-forming nuclei is a steeper function of stellar mass in lower-density environments and in blue-cloud galaxies. We find that the fraction of LINERs depends on galaxy colour and, for Mstar ≳ 109.5 − 10 M⊙, increases in galaxies belonging to the green valley. [ABSTRACT FROM AUTHOR]

We celebrate the legacies of our friend and mentor Professor Lianshou Liu who was one of the pioneers for the phenomenology of multi-particle interactions and initiated the physics of relativistic heavy-ion collisions in China. In this article, we discuss some of the recent exciting experimental observations on the collective phenomena including collectivity, chirality, criticality, strangeness production, and thermal equilibrium in high-energy nuclear collisions. Future directions, especially the physics at high baryon density, will be discussed with a focus on the first-order phase boundary and hyperon–nucleon interactions. [ABSTRACT FROM AUTHOR]

The excitation functions of nuclear reactions natBa(α,xn)132, 133m, 134, 135, 137m,g, 139, 141Ce, natBa(α,x)135, 140La and natBa(α,x)131, 133m, 135mBa were measured for the first time in the energy range of 60 → 20 MeV using stack foil technique combined with γ-ray spectrometry. A comparative analysis of the experimental results with TENDL-2021 data was carried out. The thick target yields of radioisotopes Ba, La, and Ce were calculated by integrating the values of the cross sections. The feasibility of practical use of the studied reactions for the production of medical radioisotopes 134Ce and 135La is discussed. [ABSTRACT FROM AUTHOR]

In the solid effect of dynamic nuclear polarization (DNP), the concerted flips of the electronic and nuclear spins, which are needed for polarization transfer, are induced by the microwaves. Commonly, the effect of the microwaves is modeled by a rate process whose rate constant is determined perturbatively. According to quantum mechanics, however, the coherent microwave excitation leads to Rabi nutation, which corresponds to a rotation rather than a rate process. Here we reconcile the coherent effect of the microwaves with the description by rate equations by focusing only on the steady state of the spin dynamics. We show that the phenomenological rate constants describing the synchronous excitation of the electronic and nuclear spins can be selected such that the description by rate equations yields the same steady state as the exact quantum-mechanical treatment. The resulting non-perturbative rates differ from the classical, perturbative ones and remain valid also at the high microwave powers used in modern-day DNP. Our treatment of the solid effect highlights the role of the coherences in the mechanistic steps of polarization transfer and reveals the importance of the dispersive (i.e., out-of-phase) component of the EPR line. Interestingly, the multiplicative dependence of the DNP enhancement on the dispersive EPR component was intuited in the very first report of the solid effect in liquids. The time-domain description of the solid effect developed here is extendable to liquids, where the dipolar interaction changes randomly in time due to molecular diffusion. [ABSTRACT FROM AUTHOR]

A unified theoretical framework is presented for the isomeric excitation of the 229Th nucleus via electronic processes. These processes include nuclear excitation by electron transition (NEET), nuclear excitation by electron capture (NEEC), and nuclear excitation by inelastic electron scattering (NEIES). Detailed calculation results on the excitation rate and the excitation cross section are presented.

The multicomponent extension of time-dependent density functional theory (TDDFT) within the nuclear-electronic orbital (NEO) framework enables the calculation of both electronic and vibrational excitations simultaneously. In this NEO-TDDFT approach, all electrons and select nuclei, typically protons, are treated quantum mechanically on the same level. Herein, the dependence of the proton vibrational excitation energies on the nuclear and electronic basis sets is examined. Protonic basis sets that include f basis functions in conjunction with substantial electronic basis sets for the quantum hydrogen are found to produce accurate proton vibrational excitation energies that are mostly within ∼30 cm−1 of reference values for the molecules studied. The NEO-TDDFT approach is shown to be effective for open-shell as well as closed-shell systems. Additionally, an approach for computing and visualizing the nuclear transition densities associated with the proton vibrational excitations is implemented. These nuclear transition densities are important for characterizing the proton vibrational excitations and determining the spatial orientations of the corresponding vibrational modes. These capabilities are essential for a variety of applications, including the incorporation of anharmonic effects into molecular vibrational frequency calculations. [ABSTRACT FROM AUTHOR]

Obtaining stronger photothermal response of optical materials is of great interest in the measurement of optical losses using the photothermal tools, in particular the thermal mirror. In our previous work, we experimentally demonstrated a more effective method of thermal mirror detection employing the spatial modulation (SM) of a continuous wave Gaussian beam excitation instead of the conventional temporal modulation (TM). A complete analytical model is presented to describe the laser-induced three-dimensional dynamic thermal fields in a semi-infinite sample and the time-dependent thermal mirror due to the thermoelastic response of the material as well as the evolution of the intensity distribution of a probe beam after interacting with the thermal mirror, in both the SM and TM schemes under the low absorption and exponentially-decaying absorption cases. With the model, we obtained the variations of temperature, surface displacement, and diffraction intensity giving rise to the photothermal response of the material. The results of the comparison between the two schemes reveal that the SM scheme is more sensitive than the TM scheme originating from a large variation range of the temperature in the SM scheme. We also explained the complex relation between the surface displacement and the diffraction intensity of the probe beam at the center of the detection plane on the basis of the phase shift caused by the thermal mirror. The presented model and the results of comparison are of great importance to gain a deeper insight into the photothermal characterization in both the SM and TM schemes. [ABSTRACT FROM AUTHOR]

We study the dynamics of a two-electron system undergoing resonant excitation and inter-Coulombic decay (ICD) in a pair of quantum dots. The influence of the focus of the exciting laser on the ICD process is investigated for a π-pulse with a close look on competing processes, i.e., direct ionization and multi-photon excitations. We scan through the field strength up to six Rabi cycles to show that ICD is still verifiable after several population inversions. With novel analyses, we determine for the first time populations of the different continuum states and thus conclude on the importance of several multi-photon excitation channels. Finally, we look into the influence of complex absorbing potentials on the dynamics. [ABSTRACT FROM AUTHOR]

A series of (4-(1,2,4-oxadiazol-5-yl) phenyl)-2-aminoacetamide derivatives showed good anti-neuroinflammation in our previous study. Some studies have proven that the anti-inflammatory compounds effective for some specific diseases could also be used to treat other inflammatory diseases. In this study, the effects of these compounds on arthritis were further analyzed. First, in-vitro anti-inflammatory activity assessment indicated that these compounds have good anti-inflammatory activity. Among them, compound f15 showed the most prominent performance, it could significantly inhibit the production of relevant inflammatory factors in lipopolysaccharide (LPS)-induced RAW264.7 cells, with IC50 values of 1.55 ± 0.33, 3.83 ± 0.19, and 7.03 ± 0.24 μM against NO, IL-1β, and TNF-α production, respectively. Preliminary mechanism studies indicated that f15 blocked the excitation of nuclear factor κB (NF-кB) signaling pathway in a concentration-dependent manner. Furthermore, in-vivo experiment showed that f15 reduced secondary foot swelling and arthritic index in adjuvant-induced arthritis (AIA) rats and inhibited the production of TNF-α and IL-1β in serum. Histopathological analysis revealed that f15 alleviated inflammatory cell infiltration and synovial hyperplasia in rats with AIA. Thus, compound f15 could be considered to have the potential to be developed as a treatment for arthritis. [ABSTRACT FROM AUTHOR]

In this work, we obtain new solutions of the Bohr Hamiltonian model appropriate for triaxial nuclei, with screened Kratzer potential in the framework of conformable fractional derivative. The analytical solutions for energy spectra are obtained using the conformable fractional Nikiforov–Uvarov method. We discuss the link between the present model and other relevant related models such as Z(5) model, classical screened Kratzer model and conformable fractional Kratzer model. The effect of the fractional-order parameter is investigated on the variations of the interaction potential. The normalized eigen-energies are calculated as well as normalized B(E2) transitions probabilities at different values of the fractional-order parameter. Our results reproduced well the experimental data for 1 2 6 Xe, 1 2 8 Xe, 1 3 0 Xe, 1 9 2 Pt, 1 9 4 Pt and 1 9 6 Pt atomic nuclei, and are found to be improved in comparison with other related theoretical models. [ABSTRACT FROM AUTHOR]

The large band gap insulator LiCaAlF6 (LiCAF) has been proposed as a possible host crystal for future realizations of a solid‐state based thorium‐229 nuclear clock, due to its excellent optical transmission in the vacuum ultraviolet range. To enable direct optical manipulation of the thorium isomeric state, the band gap has to remain larger than the nuclear excitation energy upon crystal doping. Here, a systematic search for possible charge compensation mechanisms, defect locations, and the emergence of other compounds, using density functional theory, is presented. Out of 535 optimized structures, the energetically most favorable arrangement is ThAl•+VLi′${\mathrm{Th}}_{\mathrm{Al}}^{\bullet}+{\mathrm{V}}_{\mathrm{Li}}^{\prime}$ with an estimated band gap of 11.4 eV. Evaluating relevant uncertainties of the used methods suggests that the doped material remains transparent at the 229Th isomer energy for all investigated configurations. [ABSTRACT FROM AUTHOR]

Measurement of independent isomeric yield ratios (IR) of 128,130,132Sb, 131,133Te, 132.134,136I, 135Xe and 138Cs have been carried out for the first time in the epi-cadmium neutron induced fission of 239Pu by using an off-line gamma-ray spectrometric technique. The average neutron energy () of the epi-cadmium reactor neutron spectrum is 1.9 MeV. From the IR values, root mean square fragment angular momenta (J RMS) were deduced by using spin dependent statistical model analysis. Effect of nuclear structure on J RMS values was examined. The present data in the epi-cadmium neutron induced fission of 239Pu were compared with the similar data in the thermal neutron induced fission of 239Pu to examine the role of excitation energy on J RMS values. • In the epi-cadmium neutron induced fission of 239Pu, IR of 128,130,132Sb, 131,133Te, 132,134,136I, 135Xe and 138Cs. • Off-line γ-ray spectrometry was used for the measurement of activity of fission products. • From the IR values, J RMS values of the fission products were deduced using spin dependent statistical model analysis. • The effect of nuclear structure and excitation energy on J RMS values were examined. [ABSTRACT FROM AUTHOR]

The 12C(p,2p)11B reaction at E p =98.7 MeV proton beam energy is analyzed using a rigorous three-particle scattering formalism extended to include the internal excitation of the nuclear core or residual nucleus. The excitation proceeds via the core interaction with any of the external nucleons. We assume the 11B ground and low-lying excited states [ 3 2 − (0.0 MeV), 5 2 − (4.45 MeV), 7 2 − (6.74 MeV)] and the excited states [ 1 2 − (2.12 MeV), 3 2 − (5.02 MeV)] to be members of K = 3 2 − and K = 1 2 − rotational bands, respectively. The dynamical core excitation results in a significant cross section for the reaction leading to the 5 2 − (4.45 MeV) excited state of 11B that cannot be populated through the single-particle excitation mechanism. The detailed agreement between the theoretical calculations and data depends on the used optical model parametrizations and the kinematical configuration of the detected nucleons. [ABSTRACT FROM AUTHOR]

Bright, short-pulsed neutron beams from laser-driven neutron sources (LANSs) provide a new perspective on material screening via fast neutron activation analysis (FNAA). FNAA is a nondestructive technique for determining material elemental composition based on nuclear excitation by fast neutron bombardment and subsequent spectral analysis of prompt γ-rays emitted by the active nuclei. Our recent experiments and simulations have shown that activation analysis can be used in practice with modest neutron fluences on the order of 105 n/cm2, which is available with current laser technology. In addition, time-resolved γ-ray measurements combined with picosecond neutron probes from LANSs are effective in mitigating the issue of spectral interference between elements, enabling highly accurate screening of complex samples containing many elements. This paper describes the predictive capability of LANS-based activation analysis based on experimental demonstrations and spectral calculations with Monte Carlo simulations. [ABSTRACT FROM AUTHOR]

In this paper, the optical properties of lead-thorium (Pb-Th), lead-uranium (Pb-U), and lead-cobalt (Pb-Co) nuclear nanoparticles in a container filled with water are simulated and modeled employing finite element analysis (FEA) for diverse particle sizes. The simulated absorption maxima of electronic excitations of nuclear nanoparticles such as Pb-U are red-shifted from 375 to 380 nm for the first peak, from 595 to 600 nm for the second peak, and from 730 to 740 nm for the third peak with increasing particle sizes from core U: 7 nm and shell Pb: 2 nm to core U: 9 nm and shell Pb: 2 nm. Moreover, the absorption peak of the Pb-Th and Pb-Co nanoparticles is red-shifted by increasing the particle size. The FEA-simulated optical band gap energies of Pb-Th, Pb-U, and Pb-Co nanoparticles were also obtained, and the data decreased with increasing the particle size. FEA-based simulations have disclosed restrictions intended for Pb-Th and Pb-Co nanoparticles size greater than 9 nm and for Pb-U nanoparticles size larger than 11 nm. The simulation method in this research enables the prediction of optical properties and contributes to the understanding and design of Pb-Th, Pb-U, and Pb-Co nanoparticles in the water container before manufacturing and functionalizing them. The work here is of particular interest in the nuclear security domain and in the nondestructive, remote detection of special nuclear materials (SNM) in water-filled cargo containers, whose manual inspection imposes physical and financial challenges. [ABSTRACT FROM AUTHOR]

Mass yield distribution has been carried out in the epi-cadmium neutron-induced fission of 241Am by measuring the cumulative yields of fission products within the mass ranges of 80 to 119 and 123 to 161. An off-line gamma-ray spectrometric technique was used for the measurement. From the cumulative yields of the fission products, mass chain yields were obtained by applying the charge distribution correction. From the mass yield distribution, the full-width at tenth-maximum of the light and heavy mass wings, the peak-to-valley (P/V) ratio, the average light mass and heavy mass , and the average number of neutrons <ν> were obtained. The mass yield data in the epi-cadmium neutron fission of 241Am were compared with similar data of thermal and 14.8-MeV neutron-induced fission to examine the role of excitation energy on the nuclear structure effect and P/V ratio. [ABSTRACT FROM AUTHOR]

In the present study we have measured the excitation functions for the nuclear reactions nat Mo(α ,x) 103 Ru, nat Mo(α ,x) 97 Ru, nat Mo(α ,x) 95 Ru, nat Mo(α ,x) 96 g Tc, nat Mo(α ,x) 95 g Tc and nat Mo(α ,x) 94 g Tc in the energy range 9–32 MeV. We have used the stacked foil activation technique followed by the offline gamma-ray spectroscopy technique to measure the excitation functions. In this study we have also documented detailed uncertainty analysis for these nuclear reactions and their corresponding covariance matrix are also presented. The excitation functions are compared with the available experimental data from EXFOR data library and the theoretical prediction from TALYS nuclear reaction code. [ABSTRACT FROM AUTHOR]

While the phenomenon of one- and two-neutron ground-state halo nuclei is well established, the effects of weak binding on nuclear excitation properties remain largely unexplored. Motivated by this question and by recent data in 40 Mg we investigate the coupling of weakly bound (halo) valence neutrons to a core using the known properties of 40 Mg to explore and illustrate possible particle-core coupling schemes and their impact on the low-lying excitation spectrum. [ABSTRACT FROM AUTHOR]

Monte Carlo method allowing to account for the effect of Pauli Exclusion Principle in the case of spin polarized electron gas is demonstrated. Modeling requires calculation of electron states occupancy accounting for the direction of the spin of the scattered electron. As an example of application, calculations for the case of spin and energy relaxation of initially polarized electrons in monolayer graphene have been performed. Model includes D’yakonov-Perel’ and Elliot-Yafet relaxation mechanisms. It is demonstrated that electron distribution function and energy relaxation follow the spin polarization relaxation and they are mainly governed by spin related scattering processes. [ABSTRACT FROM AUTHOR]

A relativistic study of spectroscopic properties of the endohedral fullerenes Ng@C60q (where Ng = He, Ne and q=0,±1,±2 are the charges) associated with the C60 molecule has been done using the equation of motion coupled cluster (EOM-CC) methodology. Specific properties estimated are the transition energies, dipole oscillator strengths, and transition probabilities for the low-lying excitations 1s²(1S0) → 1snp (¹P1) (n = 2, 3, 4) for He@C60q and 1s²2s²2p6 (1S0) → 1s²2s²2p5ns/nd (¹P1) (n = 3, 4) for Ne@C60q, which have been compared with those for the isolated atom to depict the confinement effect of the host molecule on the encapsulated atom. This is accomplished by introducing an effective potential to the atomic Hamiltonian induced by the fullerene moiety and its charge. The EOM-CC results have been compared with those estimated with the random phase approximation (and configuration interaction singles) to understand the effect of electron correlation under such confinement. The systematic and interesting behavior of the properties is highlighted indicating the effect of fullerene cage potential on the redistribution of electron density of the guest atom. [ABSTRACT FROM AUTHOR]

Excitation energy plays an important role in energy conversion, biological processes, and optical devices. In this work, we apply the Tao-Mo (TM) nonempirical meta-generalized gradient approximation and the combination TMTPSS (TMx + TPSSc), with TPSSc being the correlation part of the original TPSS (Tao-Perdew-Staroverov-Scuseria) to study excitation energies of small molecules and oligomers. Our test set consists of 17 molecules with 134 total excited states, including singlet, triplet, valence, and Rydberg excited states. Our calculation shows that both the TMTPSS and TM functionals yield good overall performance, with mean absolute errors (MAEs) of 0.37 eV and 0.42 eV, respectively, outperforming commonly used semilocal functionals LSDA (MAE = 0.55 eV), PBE (MAE = 0.58 eV), and TPSS (MAE = 0.47 eV). In particular, TMTPSS can yield nearly the same accuracy of B3LYP (MAE = 0.36 eV), with lower computational cost. The accuracy for semilocal density functional theory continues to hold for conjugated oligomers, but they become less accurate than hybrid functionals, due to the insufficient nonlocality. [ABSTRACT FROM AUTHOR]

In this work, the behavior of a Complementary Split Ring Resonator (CSRR) operating within the quasi-static resonance regime and embedded in a composite stratified Substrate Integrated Waveguide (SIW) with two different dielectric layers is analyzed. In these conditions, the propagating modes within the SIW combined with the imposed non-symmetrical structure lead to the excitation of the CSRR elements inside the SIW at difference with conventional excitation. Several cases of CSRR loaded SIW are proposed, and their electromagnetic field components as well as their frequency response are analyzed, providing insight into the CSRR resonance excitation. A test prototype has been designed, fabricated, and measured, showing a good agreement with simulation results and providing a new alternative for the implementation of compact frequency selective devices compatible with planar technology and without undesired radiation loss. [ABSTRACT FROM AUTHOR]

We propose two broadband pulse schemes for 14N solid-state magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) that achieves (i) complete population inversion and (ii) efficient excitation of the double-quantum spectrum using low-power single-sideband-selective pulses. We give a comprehensive theoretical description of both schemes using a common framework that is based on the jolting-frame formalism of Caravatti et al. [J. Magn. Reson. 55, 88 (1983)]. This formalism is used to determine for the first time that we can obtain complete population inversion of 14N under low-power conditions, which we do here using single-sideband-selective adiabatic pulses. It is then used to predict that double-quantum coherences can be excited using low-power single-sideband-selective pulses. We then proceed to design a new experimental scheme for double-quantum excitation. The final double-quantum excitation pulse scheme is easily incorporated into other NMR experiments, as demonstrated here for double quantum-single quantum 14N correlation spectroscopy, and ¹H-14N dipolar heteronuclear multiple-quantum correlation experiments. These pulses and irradiation schemes are evaluated numerically using simulations on single crystals and full powders, as well as experimentally on ammonium oxalate ((NH4)2C2O4) at moderate MAS and glycine at ultrafast MAS. The performance of these new NMR methods is found to be very high, with population inversion efficiencies of 100% and double-quantum excitation efficiencies of 30%-50%, which are hitherto unprecedented for the low radiofrequency field amplitudes, up to the spinning frequency, that are used here. [ABSTRACT FROM AUTHOR]