Nuclear Data Center Research Articles

TROPIC: A program for calculating reduced transition probabilities

Measurements of level lifetimes and the extracted transition probabilities are one of the cornerstones of nuclear structure physics. The reduced transition probabilities, B(πλ;Ji→Jf) yield information about the structure, wavefunctions, and matrix elements of excited states connected by electromagnetic transitions in a given nucleus. The arsenal of techniques for measuring lifetimes continues to expand and presently includes a wide range of values from femtoseconds to microseconds. While lifetime measurement techniques vary, the extraction of transition probabilities remains the same. RULER is the program used by the National Nuclear Data Center (NNDC) and ENDSF evaluations, while TRANSNUCLEAR was developed at the University of Cologne and modified by a variety of groups. This paper presents a new program TROPIC (TRansitiOn ProbabIlity Calculator), which is the most modern and efficient way to extract transition probabilities B(πλ). TROPIC is a program written in Python 3 with the NumPy and SciPy libraries. This is in line with the advances that ENSDF and NNDC are making in moving away from the 80-character card punch input formats. Several design features were implemented to provide a streamlined process for the user and mitigate drawbacks that were present in other programs. The results from TROPIC have been compared with TRANSNUCLEAR and RULER. The answers are as expected identical, but the investment of input to output time is significantly reduced. TROPIC will be made available for public domain use, along with a user guide and example files. Program summaryProgram Title: TROPICCPC Library link to program files:https://doi.org/10.17632/958ygp2sb4.1Developer's repository link:https://github.com/ND-fIREBall/TROPICLicensing provisions: GPLv3Programming language: Python 3Nature of problem: An efficient way to calculate multiple reduced transition probabilities with minimal effort invested from the user.Solution method: A Python 3 script has been developed to read in a CSV file containing all necessary input parameters, calculate the transition probabilities listed in the CSV file, and export the results in three different output formats.

Impact of a novel emergency cooling system on data center environment under long-term power failure

Nuclear power plant data centers (NPPDCs) are in charge of regulating nuclear reactors. For nuclear safety, the cooling system should provide a stable operating environment for the NPPDC. A novel emergency cooling system with ultralow-temperature heat exchangers could enhance interior radiant cooling. Liquid nitrogen (LN2) flows into the indoor finned tube heat exchangers (FTHEs) under the pressure of the storage tank. In this paper, the impacts of the FTHE layout and connection and the LN2 flow rate on server cooling and interior temperature distribution were explored through experiments. The results indicated that the position and quantity of the LN2 inflow section had a major impact on the cooling effect of the cabinet. Changing the LN2 flow rate can adjust the cooling. A massive flow of LN2 was suitable for rapid emergency cooling while degrading the temperature stratification. In parallel, the FHTEs provided the best cooling effect and temperature uniformity. The Parallel 1 scheme cooled the interior of the cabinet 20% faster than the Parallel 2 scheme, and it had 11.3% less temperature stratification near the cabinet (Line 2).

STUDY MAGNETIC ELECTRON SCATTERING FORM FACTOR OF 24Mg ISOTOPE

The magnetic form factor of 24Mg isotope under inelastic electron scattering was subjected to computational scrutiny via the utilization of the Oxbash code. The endeavor involved elucidating energy levels intrinsic to this nucleus through the application of the shell model, wherein the model space encompassed zbm, psd, spsdpf, and sd configurations. In the context of the sd model, the investigation harnessed two pioneering USD-type Hamiltonians, denoted as USDC and USDI, in conjunction with tailored amendments to these interaction potentials, referred to as USDCm and USDIm. This study culminated in comprehensively juxtaposing all computational outputs with empirical data sources, including information extracted from the National Nuclear Data Center (NNDC) repository. Significantly, this systematic examination underscored a notable congruence between the derived computational outcomes and the empirical observations. This alignment became conspicuously pronounced subsequent to judicious adjustments made to the g-factors, specifying values of = 1.060 and = -0.060. The profound unity between the findings of this study and experimental data manifests as compelling evidence, substantiating the efficacy and precision of the employed interaction models. It implies a reliable capacity of these models in the precise computation of magnetic form factors M1, M2, and M3

Three-dimensional potential energy surface for fission of 236U within covariant density functional theory* *Supported by the National Natural Science Foundation of China (11875225, 11790325, 11790320), the Special Fund from the China Nuclear Data Center, the Fundamental Research Funds for the Central Universities, and the Fok Ying-Tong Education Foundation

We calculate the three-dimensional potential energy surface (PES) for the fission of the compound nucleus U using covariant density functional theory with constraints on the axial quadrupole and octupole deformations as well as the nucleon number in the neck . By considering the additional degree of freedom , the coexistence of the elongated and compact fission modes is predicted for . Remarkably, the PES becomes shallow across a large range of quadrupole and octupole deformations for small , and consequently, the scission line in the plane extends to a shallow band, leading to fluctuations of several to ten MeV in the estimated total kinetic energies and of several to approximately ten nucleons in the fragment masses.

75 Years of Experimental Nuclear Reaction Data Compilations

The comprehensive experimental nuclear reaction data compilations were pioneered at the Metallurgical Laboratory, University of Chicago, and Los Alamos National Laboratory [1, 2] for the Manhattan Project needs. In 1947 many Manhattan Project alumni moved to a newly created Brookhaven National Laboratory (BNL) to work on nuclear physics research and data compilations [3–6] in support of nuclear science and reactor research activities. Since the beginning, the data project has relied heavily on computer technologies available at the time, and Brookhaven compilations have been stored in the Sigma Center Information Storage and Retrieval System (SCISRS) that predated the Exchange Format (EXFOR) database. In the following years, the reaction compilations evolved and gained an international component. Currently, the compilation efforts are coordinated by the Nuclear Reaction Data Centers network (NRDC) worldwide, which was founded in 1979 and operates under the auspices of the International Atomic Energy Agency (IAEA). The data compilations in the USA are coordinated by the National Nuclear Data Center (NNDC), Brookhaven National Laboratory for the United States Nuclear Data Program (USNDP). The database compilations represent one of the oldest continuously-operated scientific collaborations that continue to archive and disseminate nuclear data for nuclear science and technology.

X4Pro – universal, fully relational EXFOR database

EXFOR library contains experimental reaction data compiled by the Nuclear Reaction Data Centers (NRDC) since 1970 and presenting data from more than 25,000 experiments in the EXFOR format with associated dictionaries and documentation. The IAEA-NDS provides nuclear data services primarily through computer systems built on relational databases and retrieval software. X4Pro is an extended EXFOR relational database designed for programmatic access to whole EXFOR content and distributed as local SQLite database with demo-codes in Python and Fortran.

Overview of the dissemination of n_TOF experimental data and resonance parameters

The n_TOF neutron time-of-flight facility at CERN is used for nuclear data measurements. The n_TOF Collaboration works closely with the Nuclear Reaction Data Centres (NRDC) network to disseminate the experimental data through the international EXFOR library. In addition, the Collaboration helps integrate the results in the evaluated library projects. The present contribution describes the dissemination status of n_TOF results, their impact on evaluated libraries and ongoing efforts to provide n_TOF resonance parameters in ENDF-6 format for further use by evaluation projects.

Ongoing Updates to NNDC Web Services

The National Nuclear Data Center (NNDC) provides nuclear data through 40 websites, many of which are being updated to make data easier to find. The most visible change is a site-wide navigation menu that links to the NNDC’s most-visited databases. The Evaluated Nuclear Structure Data File (ENSDF) front page now also has a chart interface for visual exploration of its data. NuDat 3.0 provides a faster, smoother, and feature-rich interactive Chart of Nuclides. The Medical Internal Radiation Dose (MIRD) website has been updated with improved response times and decay diagrams. More recently, the NNDC has focused on standardizing its web development process. Through the use of Git version control and Gradle Build Tool, the NNDC intends to improve existing websites and guide the creation of new ones.

EXFOR-NSR PDF database: a system for nuclear knowledge preservation and data curation

Current needs of nuclear science and technology include complete, well-documented, and easily verifiable nuclear data. The complete data records require supporting nuclear bibliography, presently stored in dedicated libraries, in addition, to actual data. Experimental nuclear reaction data (EXFOR) and Nuclear Science References (NSR) databases contain compilations based on primary (journals) and secondary (conference proceedings, theses, preprints, etc.) publications, and data received from authors via private communications. The secondary library materials and private communications often represent a bottleneck for nuclear data verification, compilation, evaluation, and dissemination activities. To address this issue, bibliographic materials were scanned into PDF (Portable Document Format) files and uploaded in a relational database.The traditional scope of nuclear databases that includes meta-data and numbers derived from data in specialized formats was broadened to accommodate the large volumes of original nuclear data publications. The complete PDF publication files were stored in a relational database as Binary Large OBjects (BLOB). This unique collection of nuclear data compilations and supporting publications generate many opportunities for machine learning applications.The Web interfaces for authorized and public access to the EXFOR-NSR nuclear publications database were implemented at the U.S. National Nuclear Data Center, https://www.nndc.bnl.gov/ and IAEA Nuclear Data Section, https://www-nds.iaea.org/. The current system is complementary to major nuclear libraries and narrowly focused on nuclear data compilation and evaluation procedures. The contents of the PDF database, details of implementation, and Web interface are described. New capabilities for data curation, knowledge preservation, worldwide dissemination, and natural language processing (NLP) applications are given.

Cross-section measurements for the 58,60,61Ni(n, α)55,57,58Fe reactions at 8.50, 9.50 and 10.50 MeV neutron energies * *Supported by the National Natural Science Foundation of China (11775006) and China Nuclear Data Center and the Science and Technology on Nuclear Data Laboratory

Cross sections of the 58,60,61Ni(n, α)55,57,58Fe reactions were measured at 8.50, 9.50 and 10.50 MeV neutron energies based on the HI-13 tandem accelerator of China Institute of Atomic Energy (CIAE) with enriched 58Ni, 60Ni, and 61Ni foil samples with backings. A twin gridded ionization chamber (GIC) was used as the charged particle detector, and an EJ-309 liquid scintillator was used to obtain the neutron energy spectra. The relative and absolute neutron fluxes were determined via three highly enriched 238U3O8 samples inside the GIC. The uncertainty of the present data of the 58Ni(n, α)55Fe reaction is smaller than most existing measurements. The present data of 60Ni(n, α)57Fe and 61Ni(n, α)58Fe reactions are the first measurement results above 8 MeV. The present experimental data could be reasonably reproduced by calculations with TALYS-1.9 by adjusting several default values of theoretical model parameters.

Determination of Energy Spectra By Using Proper Quantization Rule of Woods-Saxon Potential

In this study, the energy spectra of Schrodinger equation for non-zero l values considering Woods Saxon potential (WSP) is calculated using proper quantization rule, then the binding energies (BE) of random light nuclei is obtained and the optimized potential parameters such as potential depth (V0) and surface thickness (a) are found. In order to calculate the energy levels of the nuclei with WSP, the PQR method was used, which has not been considered before. In quantum mechanics, the exact solution of energy systems, momentum, and quantum states can be found using the proper quantization rule(PQR) method.Using the Matlab calculation program, we have achieved numerical values of the energy spectrum for random light nuclei and compared the result with the experimental Nuclear Data Center (NDC) values. In addition, we found potential depth and surface thickness for four light nuclei. Correlations between the light nuclei show the facts about the nuclear structure characteristics, origin, and energies of these nuclei. Pearson’s correlation coefficient is accepted as the most common correlation coefficient. According to the values of Pearson correlation coefficients, it is observed that there is a significant positive correlation between the nucleons examined. Finally, we plot the E-V0-a diagrams for those values to optimize and provide the appropriate coefficients. It is shown that there is a good agreement between the results of this work and experimental values.

The Experimental Nuclear Reaction Data(EXFOR)

The EXchange FORmat (EXFOR) experimental nuclear reaction database and the retrieval system provide access to the wealth of low- and intermediate-energy nuclear reaction physics data, and become the most comprehensive compilation of experimental nuclear reaction data. Currently, there are 13 participants (nuclear data centers) of the International Network of Nuclear Reaction Data Centers(NRDC) which has been organized under the auspices of the International Atomic Energy Agency(IAEA) to coordinate the collection, compilation, and dissemination of nuclear data on an international scale. As the participant of NRDC, China Nuclear Data Center(CNDC) does its best for measurement of nuclear reaction quantities induced by neutron and charged-particle and research on the technique of database construction. The formation, development and current situation of EXFOR library, and its format, compilation and retrieval system were introduced. The work on compilation of experimental nuclear reaction data and study of the database construction technique in China was briefly summarized, such as scanning Chinese journals, compiling EXFOR entries, developing software, providing nuclear data service in China, collaborating with NRDC and so on.

Power-Law Intensity Distribution of γ-Decay Cascades: Nuclear Structure as a Scale-Free Random Network.

By modeling the transition paths of the nuclear γ-decay cascade using a scale-free random network, we uncover a universal power-law distribution of γ-ray intensity ρ_{I}(I)∝I^{-2}, with I the γ-ray intensity of each transition. This property is consistently observed for all datasets with a sufficient number of γ-ray intensity entries in the National Nuclear Data Center database, regardless of the reaction type or nuclei involved. In addition, we perform numerical simulations that support the model's predictions of level population density.

Application of a Simple, Spiking, Locally Competitive Algorithm to Radionuclide Identification

Many radionuclide identification algorithms use statistical inference to collect a variety of features from gamma-ray spectra to deduce the presence of particular radionuclides. More modern algorithms require large amounts of data to learn and use latent features from spectra for classification. Both approaches are computationally expensive, which is reflected in their power consumption, and require large amounts of user intervention to prepare. In this article, we introduce a low-power, neuromorphic algorithm for the real-time identification of radionuclides which simultaneously considers the entire shape of a gamma-ray spectrum. Utilizing the output of a traditional gamma-ray detector, our spiking, locally competitive algorithm uses sparse coding optimization to compare global patterns in a gamma-ray spectrum with a dictionary of radionuclide templates. This approach allows us to model informative global features resulting from both photoelectric absorption and Compton scattering. For the purpose of radiation threat reduction, the dictionary consists of data from the Nuclear Wallet Cards, a list of radionuclides and their properties compiled by the National Nuclear Data Center. To test our algorithm, we use a variety of gamma-ray spectra created using radionuclides measured under laboratory conditions with varying durations, distances, activity levels, and backgrounds, resulting in a wide range of signal-to-noise ratios. We have created test sets for three different gamma-ray detector types, with <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">57</sup> Co, <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">137</sup> Cs, <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">152</sup> Eu, <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">60</sup> Co, <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">239</sup> Pu, and <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">235</sup> U sources, to quantify the effect of resolution, efficiency, and background on the accuracy of the algorithm. We demonstrate a true positive accuracy of 91% with a high-resolution detector and 89% with a low-resolution detector on the corresponding test sets. Experimenting with the same radionuclides included in the test sets in a variety of special nuclear material (SNM) masking configurations, we show that our algorithm is capable of correctly identifying both SNM and mask even when the activity level of the mask is several times higher than that of the SNM. We also determine that our algorithm achieves over a 99% reduction in power consumption over other radionuclide identification software applications, which is critical for long-term, independent monitoring and is the goal of this research.

Texas A&amp;M US Nuclear DATA Program

Nuclear data evaluation is an independent century-long expert activity accompanying the development of the nuclear physics science. Its goal is to produce periodic surveys of the world literature in order to recommend and maintain the set of the best nuclear data parameters of common use in all basic and applied sciences. After WWII the effort extended and while it became more international it continued to be supported mainly by the US for the benefit of the whole world. The Evaluated Nuclear Structure Data File (ENSDF) is the most comprehensive nuclear structure database worldwide maintained by the United States National Nuclear Data Center(NNDC)at Brookhaven National Laboratory(BNL)and echoed by the IAEA Vienna Nuclear Data Services. Part of the US Nuclear Data Program since 2005 the Cyclotron Institute is one of the important contributors to ENSDF. Since 2018 we became an international evaluation center working in a consortium of peers hosted traditionally by prestigious national institutes as well as universities. In this paper the main stages of the evaluation work are presented in order to facilitate a basic understanding of the process as a guide for our potential users. Our goals are to maintain a good productivity vs. quality performance assuring the currency of the data and participating in the effort of modernizing the structure of ENSDF databases in order to make them compatible with the data-centric paradigms of the future.

THERMAL SCATTERING LAW ENDF LIBRARIES FOR LIQUID FLIBE

Several advanced nuclear reactor concepts have been proposed in the past few years where FLiBe molten salt represents a major constituent of the core. In this case, neutrons produced in fission slow down and moderate in FLiBe (a eutectic with a mixture of 2:1 ratio of LiF and BeF2) until they reach low energies (i.e, below 1 eV). At that stage, the thermalization process becomes dominant and the neutrons achieve a quasi-equilibrium energy state that is dependent on the temperature of the moderator. In neutronic simulations, the description of neutron thermalization is captured using the thermal scattering law (TSL), i.e., S(α,β), of the material in which low energy neutrons are interacting. S(α,β) defines the energy-momentum phase space that is available for an incoming low energy neutron. In addition, it is directly proportional to the double differential thermal neutron scattering cross section. In this work, the TSL of molten salt FLiBe is developed based on a generalized density of excitation states (GDOS) derived from atomic trajectories generated using classical molecular dynamics (MD) simulations that were performed with the LAMMPS code. The MD simulations utilized a Born-Mayer type atomic potential function that was verified to reproduce the properties of FLiBe including density and viscosity. The FLASSH code was used to evaluate the TSL’s ENDF File 7 in a temperature range extending from 773 K to 1673 K. In addition, ACE type cross section libraries are produced and tested with the objective of contributing the data to the National Nuclear Data Center for inclusion in the ENDF/B-VIII database.

Description of Superdeformed Bands of the Isotones $$\boldsymbol{N=113}$$ for Nuclear Mass Region $$\boldsymbol{A\sim 190}$$

Electric quadrupole $$\gamma$$ -ray transition energies $$E_{\gamma}$$ , rotational frequencies $$\hbar\omega$$ and dynamic $$J^{(2)}$$ and kinematic $$J^{(1)}$$ moments of inertia have been calculated for yrast and excited superdeformed (SD) bands in Hg, Tl, Pb isotonic ( $$N=113$$ ) nuclei by using two-parameter power-law formula. The model parameters and the bandhead spins were determined using a $$\chi^{2}$$ fit by random minimization via Monte Carlo simulation technique with a uniform distribution of random numbers. The calculated results of $$E_{\gamma}$$ agreed with the experimental data published in National Nuclear Data Center (nndc) very well, and present assigned spins of the studied superdeformed rotational bands (SDRB’s) are consistent with the spins suggested by other previous formulae. The majority of the studied SD bands displayed the same large, smooth increase in $$J^{(2)}$$ by increasing $$\hbar\omega$$ . A saturation of $$J^{(2)}$$ at higher values of $$\hbar\omega$$ was observed for the two bands (1, 2) in $${}^{195}$$ Pb due to the Pauli blocking of the quasineutron alignment in the presence of quasiproton alignment. The studied SD bands exhibited staggering in their transition energies. Five pairs of signature partner SDRBs exhibited an $$\Delta I=1$$ staggering effect in their transition energies, namely $${}^{193}$$ Hg (SD1, SD2), $${}^{193}$$ Hg (SD3, SD4), $${}^{194}$$ Tl (SD1, SD2), $${}^{195}$$ Pb (SD1, SD2), and $${}^{195}$$ Pb (SD3, SD4). To investigate this $$\Delta I=1$$ staggering, we extracted the difference between the average transition $$I+2\to I$$ and $$I\to I-2$$ energies in one band and the transition $$I+1\to I-1$$ energies in the signature partner. Also, a $$\Delta I=2$$ staggering exists in three SD bands of odd–odd $${}^{194}$$ Tl. This $$\Delta I=2$$ staggering effect was determined by calculating the energy difference between two consecutive $$\gamma$$ -ray transitions as a function of rotational frequency after subtracting a smooth reference expressed in the notation of Cederwall.

Cross-section measurements for 58,60,61Ni(n, α)55,57,58Fe reactions in the 4.50 – 5.50 MeV neutron energy region * * Supported by the National Natural Science Foundation of China (11775006) and China Nuclear Data Center and the Science and Technology on Nuclear Data Laboratory

The cross sections at 5 energy points of the 58Ni(n, α)55Fe reaction were measured in the 4.50 MeV ≤ En ≤ 5.50 MeV region while those for the 60Ni(n, α)57Fe and 61Ni(n, α)58Fe reactions were measured at En = 5.00 and 5.50 MeV using the 4.5 MV Van de Graaff accelerator at Peking University. A gridded twin ionization chamber (GIC) was used as the detector, and enriched 58Ni, 60Ni, and 61Ni foil samples were prepared and mounted at the sample changer of the GIC. Three highly enriched 238U3O8 samples inside the GIC were used to determine the relative and absolute neutron fluxes. The neutron energy spectra were obtained through unfolding the pulse height spectra measured by the EJ-309 liquid scintillator. The interference from the low-energy neutrons and impurities in the samples has been corrected. The present data of the 60Ni(n, α)57Fe reaction are the first measurement results below 6.0 MeV, and those of the 61Ni(n, α)58Fe reactions are the first measurement results in the MeV region. The present results have been compared with existing measurements, evaluations, and TALYS-1.9 calculations.

Nuclear radius parameters (r0) for even-even nuclei from alpha decay

The decay data for 186 even-even alpha emitters have been analyzed, and used as input in the ALPHAD code to extract nuclear radius parameters (r0) for the daughter nuclides. The ALPHAD code employs Preston's spin-independent formalism to calculate alpha decay probabilities. A suite of databases available at the website of the National Nuclear Data Center (NNDC), Brookhaven National Laboratory was consulted to ensure the completeness and reliability of available experimental data pertaining to alpha decays of all the even-even nuclides in the entire nuclear landscape. The literature available up to June 2020 has been consulted. In addition to updating Qα values, half-lives, and other relevant quantities for all the even-even alpha emitters, 26 new even-even alpha emitters, and 164 references published since 1997, mostly in primary nuclear physics journals, have been added to the previous evaluation by Y.A. Akovali [1] in 1998, with a literature cutoff date of January 1997. We also present systematics of r0 parameters for even-even nuclides, and find that the radius parameters in an isotopic chain exhibit a regular pattern as a function of parent neutron number, showing a minimum at major closed shells, e.g. at N=126, increasing sharply above the closed shells, followed by a smoothly decreasing trend towards the next shell closure. The r0 parameters for even-even nuclides can be used as input parameters to calculate hindrance factors for the alpha decay of odd-A and odd-odd nuclides. We have also modified the original ALPHAD code so that the r0 parameters for the odd-A and the odd-odd nuclei can be automatically calculated using the present data file for r0 parameters of even-even daughter nuclides.

Measurement of neutron induced reaction cross sections of palladium isotopes at the neutron energy of 14.54 ± 0.24 MeV with covariance analysis

The 110Pd(n,2n)109Pd, 102Pd(n,2n)101Pd, 105Pd(n,p)105Rh and 106Pd(n,p)106mRh reaction cross sections have been measured with respect to the 197Au(n,2n)196Au monitor reaction at the neutron energy of 14.54 ± 0.24 MeV by using the method of activation and off-line γ-ray spectrometry. The mono-energetic neutron beam was generated from the D–T reaction. The uncertainties in the various basic nuclear parameters in the measured reactions and their correlations were estimated by using covariance analysis. The present data were compared with the EXFOR based literature data, evaluated data of various libraries available in national nuclear data center and with the calculated values from TALYS-1.9 code.