Nuclear Physics Data Research Articles

The center of nuclear physics data at the All-Russia Research Institute of Experimental Physics

The Center of Nuclear Physics Data (All-Russia Research Institute of Experimental Physics) is a member of the International Nuclear Reaction Data Center Network, operating under the aegis of the International Atomic Energy Agency and founded to coordinate the collection, compilation, and dissemination of data among the world community. The Center of Nuclear Physics Data (CNPD) focuses on the compilation of experimental data on the interaction of charged particles with nuclei for the EXFOR international library. The center’s personnel are currently developing a software package that will make it possible to enter, edit, and record the data in the EXFOR format. The package includes all of the procedures for processing experimental data and ensuring compliance with the specified format.

Thesprocess: Nuclear physics, stellar models, and observations

Nucleosynthesis in the s process takes place in the He burning layers of low mass AGB stars and during the He and C burning phases of massive stars. The s process contributes about half of the element abundances between Cu and Bi in solar system material. Depending on stellar mass and metallicity the resulting s-abundance patterns exhibit characteristic features, which provide comprehensive information for our understanding of the stellar life cycle and for the chemical evolution of galaxies. The rapidly growing body of detailed abundance observations, in particular for AGB and post-AGB stars, for objects in binary systems, and for the very faint metal-poor population represents exciting challenges and constraints for stellar model calculations. Based on updated and improved nuclear physics data for the s-process reaction network, current models are aiming at ab initio solution for the stellar physics related to convection and mixing processes. Progress in the intimately related areas of observations, nuclear and atomic physics, and stellar modeling is reviewed and the corresponding interplay is illustrated by the general abundance patterns of the elements beyond iron and by the effect of sensitive branching points along the s-process path. The strong variations of the s-process efficiency with metallicity bear also interesting consequences for Galactic chemical evolution.

The Effects of Nuclear Fragmentation Models on Single Event Effect Prediction

There is a need for improved physics models to correctly predict single event effects (SEEs) caused by nuclear reaction products from heavy ion radiation. Previous validations for nuclear fragmentation simulations are shown to be insufficient to support SEE analysis applications. A comparison of different physics models with experimental nuclear physics data coupled with energy deposition predictions is presented.

Opacity and radiative power losses calculations

In this contribution we present results on opacity and radiative power losses in laser-produced plasmas. We focus our attention on the inner shell transition array 1 s–2 p in an aluminum plasma. At high densities, electron, Doppler and ion Stark broadening play a role in line merging. This is why the PPP line-shape code developed at Université de Provence was adapted to calculate opacity and radiative power losses in Al and Ge ions. Atomic physics data required in PPP calculations is provided by an MCDF code. Comparison with experiments is discussed.

Spectroscopy of highly charged tungsten ions relevant to fusion plasmas

The Berlin electron beam ion trap (EBIT) has been established by the Max-Planck-Institut für Plasmaphysik to generate atomic physics data in support of research in the field of controlled nuclear fusion by measuring the radiation from highly charged ions, particularly tungsten ions, in the x-ray, extreme ultraviolet and visible spectral ranges. With EBIT a selected ensemble of ions in specific charge states can be produced, stored and excited for spectroscopic investigations. Employing this technique, we have investigated the soft x-ray lines at 0.56 nm from Cu-like W45+ to V-like W50+ ions originating from 3d–4f transitions, which also are observed in the high-temperature core plasma of the ASDEX Upgrade tokamak. A further study focuses on Si-like W60+ to Ne-like W64+ tungsten ions predicted to dominate the core plasma of the International Thermonuclear Experimental Reactor (ITER) and radiate strongly at 0.13 nm from n=3–2 transitions.

Integrated simulation of plasma surface interaction during edge localized modes and disruptions: Self-consistent approach

Edge-localized modes (ELMs) and disruptions remain a major concern to divertor plasma-facing components (PFCs) during normal and abnormal operation of future tokamaks. Of particular concern are the pulses of energy and particles that are transported during ELMs to the divertor surface. ELMs, therefore, can result in excessive divertor erosion and plasma contamination. A two-fluid model is enhanced to include detail atomic physics data for tungsten, lithium, and neon in multidimensional geometry to integrate core, SOL parameters, and divertor surface evolution (melting, vaporization, vapor cloud dynamics, etc.) using the HEIGHTS numerical simulation package. ELM mitigation using liquid Li surface and neon gas puffing are also simulated. Initial results indicate that a thin layer of Li (<1 mm) can fully protect the divertor surface from giant ELMs. Significant amount of neon gas puff (nL > 10 17 cm −2) is needed to prevent tungsten surface from melting during giant ELMs. Vapor impurity diffusion through the private flux region can be major source of plasma contamination during ELMs and could terminate the plasma in a disruption.

Design of Highly Directive Ni-Like Ag X-Ray Laser at 13.9 nm

We theoretically investigate a 13.9 nm Ni-like Ag x-ray laser using a one-dimensional hydrodynamic code coupled with an atomic physics data package. The population inversion is transiently pumped by a grazing incident 0.5ps main pulse irradiating into an optimized plasma, which is generated by a normal incidence 300ps pulse and a subsequent grazing incidence 300ps pulse. The effect of the grazing-incidence angle on the source position of the output x-ray laser is investigated. Near zero deflecting angle is found for the peak output intensity of the Ni-like Ag x-ray lasers, with a small FWHM divergence of 5mrad. It is predicted that saturation can be achieved with a total pump energy of 165 mJ.

Numerical study of the Ne-like Cr x-ray laser at 28.6 nm

We investigate the Ne-like Cr x-ray laser at 28.6nm by using a modified 1D lagrangian hydrodynamic code MED103 coupled with an atomic physics data package and a 2D ray tracing code as a post-processor. The laser pumping configuration includes two prepulses and one main pulse. The first prepulse normally irradiates the target, while the second prepulse and the main pulse irradiate the target at grazing-incident angles. We predict that saturation can be achieved for the Ne-like Cr x-ray lasers with a total pumping energy of 125mJ. Good beam qualities with no deflecting angle and a small divergence angle of 5mrad are observed.

The lasing temporal characteristics of Ni-like Mo x-ray lasers at 18.9 nm driven by a grazing incidence pumping scheme

We numerically investigate the effects of the time delay between prepulse and main pulse on the lasing characteristics of the Ni-like Mo soft x-ray lasers (XRL) at 18.9 nm driven in a grazing incidence pumping (GRIP) geometry by using a modified 1D hydrodynamic code MED103 coupled with an atomic physics data package and a 2D Ray-tracing code. Typical XRL experiments with lasing action in a broad temporal window for the delay are simulated and analyzed. Investigations show a well-performed preplasma together with the proper main pulse is the key to achieve lasing over a broad range of time delay.

Nuclear Physics of thesProcess

AbstractStarting from a sketch of thes-process concept formulated 50 years ago, the nuclear physics data fors-process calculations are briefly reviewed with emphasis on the status of neutron capture cross sections and beta decay rates. Accurate and comprehensive experimental data are mandatory as direct input fors-process calculations as well as for improving the complementary information from nuclear theory. The current challenges of the field are discussed in the light of new or optimized methods and state-of-the-art facilities, indicating the potential for accurate measurements and the possibility to study cross sections of radioactive isotopes. These opportunities will be considerably enriched by the enormous improvements provided by new facilities.

Extended pool of electron-capture rates for core-collapse supernovae simulations

The mechanism behind core-collapse supernova explosions is not yet fully understood. As computers get faster, more complex processes can be included in supernova models and the modelling can be performed in greater detail. Improved nuclear physics data play a role in improving the understanding of processes taking place during the core-collapse phase of this phenomenon. Large-scale shell model (LSSM) and shell model Monte Carlo (SMMC) calculations combined with the random phase approximation (RPA) have yielded two complementary pools of electron-capture and neutrino-nucleus reaction rates for iron group nuclei and beyond. Recently, the electron-capture SMMC+RPA pool was extended by including more neutron-rich nuclei to improve its predictions. At present the average rate is built from data on more than 250 nuclei. This presentation is focused on the features of this new, enlarged pool of electron-capture rates. The accuracy of predictions made with this extended pool is estimated.

Nuclear physics far from stability and r-process nucleosynthesis

Nucleosynthesis theory predicts that half of the chemical elements above Fe are formed in explosive stellar scenarios by the r-process. A correct modelling of this process requires knowledge of nuclear properties very far from stability and a detailed description of the astrophysical environments. Using updated experimental and theoretical nuclear-physics data, we have performed detailed r-process calculations within the classical, site-independent “waiting-point” approximation and the “neutrino-wind” scenario of core-collapse type II supernovae (SNII). Nuclear and astrophysical constraints on the reproduction of the available r-process observables will be reviewed.

Simulations of the output of the Ne-like Ti x-ray laser at32.6nmdriven by the grazing-incidence pumping scheme

Numerical simulations are presented for the output of a Ne-like Ti soft x-ray laser at $32.6\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ driven by the grazing-incidence pumping (GRIP) scheme, using a modified one-dimensional (1D) lagrangian hydrodynamic code MED103 coupled with an atomic physics data package and a 2D RAYTRACE code as a postprocessor. We predict that saturation can be achieved at a plasma length of $0.2\phantom{\rule{0.3em}{0ex}}\mathrm{cm}$ by an optimized driving configuration with an energy of only $200\phantom{\rule{0.3em}{0ex}}\mathrm{mJ}$. We also compare the output beam quality of the Ne-like Ti soft x-ray laser generated by an optimized pump energy of $200\phantom{\rule{0.3em}{0ex}}\mathrm{mJ}$ and a higher energy of $385\phantom{\rule{0.3em}{0ex}}\mathrm{mJ}$. Better spatial coherence is expected for a higher pump energy.

DaqProVis, a toolkit for acquisition, interactive analysis, processing and visualization of multidimensional data

Multidimensional data acquisition, processing and visualization system to analyze experimental data in nuclear physics is described. It includes a large number of sophisticated algorithms of the multidimensional spectra processing, including background elimination, deconvolution, peak searching and fitting.

Nuclear reaction and structure data services of the National Nuclear Data Center

The mission of the National Nuclear Data Center (NNDC) includes collection, evaluation, and dissemination of nuclear physics data for basic nuclear research and applied nuclear technologies. In 2004, to answer the needs of nuclear data users, NNDC completed a project to modernize storage and management of its databases and began offering new nuclear data Web services. The principles of database and Web application development used at NNDC are described. Examples of nuclear structure, nuclear reaction and bibliographical database applications along with a number of nuclear science tools and codes are presented.

Next-generation Nuclear Data Web Services

The National Nuclear Data Center collects, evaluates, and disseminates nuclear physics data for basic nuclear research and applied nuclear technologies. We have recently produced a nuclear data portal featuring modern and powerful servers, relational database software, Linux operating system, and Java programming language. The portal includes nuclear structure, decay and reaction data, as well as literature information. Data can be searched for using optimized query forms; results are presented in tables and interactive plots. Additionally, a number of nuclear science tools, codes, applications, and links are provided. A brief tutorial of the different databases and products will be provided.

Nuclear input for the s process: progress with experiments and theory

Models for neutron capture nucleosynthesis by the slow neutron capture ( s) process are approaching a state where a parameter-free description of the respective stellar sites appears within reach. However, conclusive results can only be expected if the underlying nuclear physics data are reliable and complete. Starting from a brief summary of the status and the remaining quests, the prospects of the field are discussed by presenting recent achievements in experimental techniques, new facilities, and theoretical concepts.

Cassini UVIS observations of the Io plasma torus: II. Radial variations

On January 14, 2001, shortly after the Cassini spacecraft's closest approach to Jupiter, the Ultraviolet Imaging Spectrometer (UVIS) made a radial scan through the midnight sector of Io plasma torus. The Io torus has not been previously observed at this local time. The UVIS data consist of 2-D spectrally dispersed images of the Io plasma torus in the wavelength range of 561–1912 Å. We developed a spectral emissions model that incorporates the latest atomic physics data contained in the CHIANTI database in order to derive the composition of the torus plasma as a function of radial distance. Electron temperatures derived from the UVIS torus spectra are generally less than those observed during the Voyager era. We find the torus ion composition derived from the UVIS spectra to be significantly different from the composition during the Voyager era. Notably, the torus contains substantially less oxygen, with a total oxygen-to-sulfur ion ratio of 0.9. The average ion charge state has increased to 1.7. We detect S(V) in the Io torus at the 3 σ level. S(V) has a mixing ratio of 0.5%. The spectral emission model used can approximate the effects of a nonthermal distribution of electrons. The ion composition derived using a kappa distribution of electrons is identical to that derived using a Maxwellian electron distribution; however, the kappa distribution model requires a higher electron column density to match the observed brightness of the spectra. The derived value of the kappa parameter decreases with radial distance and is consistent with the value of κ=2.4 at 8 R J derived by the Ulysses URAP instrument (Meyer-Vernet et al., 1995). The observed radial profile of electron column density is consistent with a flux tube content, NL 2, that is proportional to r −2.

Modelling of Ne-like Copper X-ray laser driven by 1.2 ps short pulse and 280 ps background pulse configuration

Detailed simulations of Ne-like Cu x-ray laser are undertaken using the EHYBRID code. The atomic physics data are obtained using the Cowan code. The optimization calculations are performed in terms of the intensity of background and the time separation between the background and the short pulse. The optimum value is obtained for the conditions of a Nd: glass laser with 1.2 ps pulse at 4.4 × 1015 W cm−2 irradiance pumping a plasma pre-formed by a 280 ps duration pulse at 5.4 × 1012 W cm−2 with peak-to-peak pulse separation set at 300 ps. X-ray resonance lines between 6 A and 15 A emitted from copper plasmas have been simulated. Free-free and free-bound emission from the Si−, Al−, Mg−, Na−, Ne− and F−like ions is calculated in the simulation.

Numerical optimization of a picosecond pulse driven Ni-like Nb x-ray laser at 20.3 nm

Detailed simulations of a Ni-like Nb x-ray laser pumped by a nanosecond prepulse followed by a picosecond main pulse are presented. The atomic physics data are obtained using the Cowan code [R. D. Cowan, The Theory of Atomic Structure and Spectra (University of California Press, Berkeley, CA, 1981)]. The optimization calculations are performed in terms of the intensity of prepulse and the time delay between the prepulse and the main pulse. A high gain over 150 cm−1 is obtained for the optimized drive pulse configuration. The ray-tracing calculations suggest that the total pump energy for a saturated x-ray laser can be reduced to less than 1 J.