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Nuclear Data Sheets for A = 87
The evaluated experimental data are presented for 14 known nuclides of mass 87 (Ga, Ge, As, Se, Br, Kr, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru). New datasets have been added for {sup 87}Ga, {sup 87}Se, {sup 87}Kr, {sup 87}Rb, {sup 87}Sr, {sup 87}Nb, and {sup 87}Tc. The observation of and new lifetime measurements for {sup 87}As at the NSCL Coupled Cyclotron Facility and the Oak Ridge Isochronous Cyclotron at the HRIBF–ORNL Facility are included in the adopted levels for this isotope. The new evaluation also includes an isomeric level at unknown energy for {sup 87}Tc, changes to the adopted levels for {sup 87}Nb based on newly published data including an extension of the high spin levels and new lifetime measurements, and new heavy ion data for {sup 87}Kr. New high spin levels for {sup 87}Rb were observed, indicating possible neutron core excitations. In addition, the ground state lifetime of {sup 87}Rb has been revised and a new lifetime measurement for an excited level in {sup 87}Rb indicates a possible proton spin flip. New excitation levels have been observed for the first time in {sup 87}Se. New direct and precise measurement of atomic masses of {sup 87}Tc, {sup 87}Mo, {sup 87}Nb, {sup 87}Zr, {sup 87}Mo and {sup 87}Tc have greatly improved the Q value landscape in this mass region. This work supersedes the previous A=87 evaluation published in 2002He09, and Q values for all isotopes were updated to incorporate the mass evaluation in 2012Wa38.
Nuclear Data Sheets for A = 43
The experimental data are evaluated for known nuclides of mass number A = 43 (Al,Si,P,S,Cl,Ar,K,Ca,Sc,Ti,V,Cr). Detailed evaluated level properties and related information are presented, including adopted values of level and γ–ray energies, decay data (energies, intensities and placement of radiations), and other spectroscopic data. Here, this work supersedes earlier full evaluations of A = 43 published by 2001Ca24 and 1990En08 (also 1978En04, and 1998En04 update).
Nuclear Data Sheets for A = 41
Available information pertaining to the nuclear structure of all nuclei with mass numbers A=41 ranging from Al (Z=13) to Ti (Z=22) are presented. The experimental reaction and decay data are evaluated and any inconsistencies or discrepancies are noted. The adopted values for various level properties (such as the spin, parity and and halflife) and gamma properties (energy, intensity and multipole character) are given. Since the prior evaluation several new measurements have expanded our knowledge of A=41 nuclides. The half-life of the ground state of {sup 41}Si has been determined and a single excited state identified. Excited levels in {sup 41}P have been observed for the first time. In {sup 41}Cl, seven new excited states have been identified in deep inelastic and heavy ion transfer reactions. Half-lifes for four states in {sup 41}Ar have been updated and additional levels with gammas have been included from a new measurement using the multiple ion transfer reaction. In {sup 41}Ca via charge-exchange reaction measurements, several new excited states were observed. A number of new resonances in {sup 41}K have been identified via the (p,γ) reaction. There remains a significant discrepancy in the half-life of the first excited state (980 keV) in {sup 41}K, with measurements differing by more than an order of magnitude. Transfer reactions suggest that this M1 transition should be l-forbidden, however, several measurements yield a lifetime which suggests a sizable M1 strength. Further measurements to resolve the current conflicts would be beneficial.
Nuclear Data Sheets for A=218
The evaluated data are presented for 11 known A=218 nulcides (Pb, Bi, Po, At, Rn, Fr, Ra, Ac, Th, Pa and U). For {sup 218}Pb, {sup 218}Bi, {sup 218}At and {sup 218}Pa, data are available only for the ground states. For {sup 218}U, only the g.s. and a high-spin isomer are known, with no data on γ-ray transitions available. For {sup 218}Po, ten excited states are known from {sup 218}Bi decay, with no knowledge on the multipolarities of gamma-ray transitions. For {sup 218}Th, five excited states in the g.s. band are known from an in-beam γ-ray study. Data on level half-lives, multipolarities and mixing ratios of gamma transitions is generally lacking for A=218 nuclei. The static magnetic dipole moment has been measured for only an isomer in {sup 218}Fr. With the exception of a new nuclide, {sup 218}Pb, and measurements of half-lives of ground states of a few nuclides of A=218 and A=222, no substantial structure information has become available since the previous evaluation in 2006. Q values are adopted from 2017Wa10 (AME-2016). The present evaluation supersedes the previous A=218 ENSDF evaluations, 2006Ja03, 1995El08, 1987El12 and 1977To13. This evaluation was carried out as part of a joint IAEA-ICTP workshop for Nuclear Structure and Decay Data, organized and hosted by the IAEA, Vienna, and ICTP, Trieste, October 15–26, 2018.
Nuclear Data Sheets for A=217
The evaluated spectroscopic data are presented in this paper for 12 known nuclides with A=217 (Tl, Pb, Bi, Po, At, Rn, Fr, Ra, Ac, Th, Pa, U). For 217Tl, 217Pb, 217Pa, and 217U nuclei, only information on the ground state is available. Levels in 217 Bi are known only from isomer decay following fragmentation reaction and those in 217 At and 217 Rn only from the α decay of 221 Fr and 221 Ra, respectively. High spin levels in 217 Ra are mainly from 1987SuZY and 2011MuZZ which are a lab report and thesis, respectively. Due to differences between these studies, further experimental study is needed to firmly establish the level scheme. This evaluation was carried out as part of a joint IAEA-ICTP workshop for Nuclear Structure and Decay Data, organized and hosted by the IAEA, Vienna and ICTP, Trieste, Aug 22 to Sept 2 2016. The evaluation work was coordinated by E.A. McCutchan (BNL). Finally, this work supersedes the previous previous A=217 evaluation (2003Ak06) by Y.A. Akovali.
Analysis of NCERC Critical Experiments with ENDF/B Nuclear Data Libraries
Nuclear data (ND) libraries are the backbone of the nuclear industry, as they are the collections of tabulated probabilities that define sub-atomic particle interactions with matter. In the areas of criticality safety and experiments, no evaluated nuclear data files (ENDF) are more important than those containing neutron cross section data. It is upon these files, and accompanying radiation transport codes, that practitioners are enabled to safely design both subcritical and critical systems. Likewise, in a symbiotic fashion, it is the same critical assemblies which are used primarily to validate that the cross sections are correct. The ENDF/B library, the United States’ national library maintained by the National Nuclear Data Center (NNDC) at Brookhaven National Laboratory (BNL), is soon releasing a new version, ENDF/B-VIII.1. Prior to the official release, several beta versions of the library were prepared and tested in simulation suites. The work presented here are results comparing the newest ENDF/B beta release (ENDF/B-VIII.1b3) and ENDF/B-VIII.0 with recent experiments done at the National Criticality Experiments Research Center (NCERC) as well as correlated experiments from the Los Alamos Critical Experiments Facility (LACEF). These NCERC and LACEF experiments were performed in part to provide validation for various cross sections that were identified as insufficient in the ENDF/B-VIII.0. In particular, lead, copper, fluorine, and chlorine, as well as the major actinides, were targeted from the last decade of critical experiments.
Nuclear Data Sheets for A=82☆
The evaluators present in this publication spectroscopic data and level schemes from radioactive decay and nuclear reactions studies for all isobars, Z=28(Ni) to Z=42(Mo), with mass number A=82. For {sup 82}Ni not much is known other than its identification. Most of the new data, i.e., after the last NDS (2003Tu03), are based on compilations included in XUNDL. Contributions of the various compilers in XUNDL are gratefully acknowledged.
Scattering Angular Distributions in the ENDF/B Nuclear Data Library
Nuclear reactors function by controlling the chain reaction of fission events in a fissile material. Understanding the gain and loss of neutrons is crucial for controlling this chain reaction. The role of fission in liberating neutrons from nuclei is well known. The fact that neutrons can scatter out of a reactor and therefore be lost is less well appreciated. Scattering can happen within fissile fuel or off of any number of the non-fissile structural components holding a reactor together. The scattering angular distributions for reactor material are the quantity that give the probability for a particle (usually a neutron) to scatter off a nucleus into a given angle. The Evaluated Nuclear Data File/B (ENDF/B) nuclear data library is the most complete and authoritative reference for neutron scattering data, containing reaction cross sections and outgoing particle distributions (including scattering angular distributions). In this project, we will compare the scattering angular distributions given in these ENDF/B data sets with those that can be derived using the Blatt-Biedenharn formalism and the resolved resonance data also in the ENDF/B files. More comparisons between the scattering angular distributions of relevant isotopes will help identify and correct any errors in the ENDF/B files. The results of this study will be an important component of the next major release of the ENDF/B library.
Nuclear Data Sheets for A = 227
The evaluated spectroscopic data are presented for ten known nuclides of mass 227 (Po, At, Rn, Fr, Ra, Ac, Th, Pa, U, Np). For {sup 227}Po, {sup 227}At, {sup 227}Rn, {sup 227}Pa, {sup 227}U and {sup 227}Np nuclei, only the ground-state information is available. Their decay characteristics are mostly unknown. Levels in {sup 227}Fr are known only from the decay of {sup 227}Rn to {sup 227}Fr. This decay scheme at present cannot be normalized to deduce γ intensities per 100 decays due to lack of knowledge about multipolarities of many low-energy transitions. The levels in {sup 227}Ra, {sup 227}Ac and {sup 227}Th are known from several decays and reactions, including particle-transfer data for {sup 227}Ra and {sup 227}Ac. The decay scheme of {sup 227}Ra to {sup 227}Ac was last studied in 1971 using small Ge detectors. Improved γ-ray intensity data need to be obtained with a better γ-detection system. The datasets for {sup 227}Ac have undergone extensive revisions, including detailed data for 231Pa α decay from 1986BaYK report, and single-proton transfer data from 1986MaYU thesis. High-spin (J>13/2 or so) structures are known only for 227Th. Level lifetime data are quite scarce for all the nuclides in this mass chain, thus limiting the knowledge of reduced transition probabilities. Band structures for {sup 227}Fr, {sup 227}Ra, {sup 227}Ac and {sup 227}Th are known in detail, together with evidence of weak octupole deformation and consequent parity-doublet structures. This evaluation was carried out as part of a joint IAEA-ICTP workshop for Nuclear Structure and Decay Data, organized and hosted by the IAEA, Vienna and ICTP, Trieste, March 24–28, 2014. The evaluation work was coordinated by B. Singh (McMaster). This work supersedes previous A=227 evaluation (2001Br31) published by E. Browne which covered literature before May 2001.
Nuclear Data Sheets for A=59☆
-- Abstract: Evaluated spectroscopic data and level schemes from radioactive decay and nuclear reaction studies are presented for {sup 59}Sc, {sup 59}Ti, {sup 59}V, {sup 59}Cr, {sup 59}Mn, {sup 59}Fe, {sup 59}Co, {sup 59}Ni, {sup 59}Cu, {sup 59}Zn, {sup 59}Ga, and {sup 59}Ge. This evaluation for A=59 supersedes the earlier one by C. M. Baglin (2002Ba42) and updates for some nuclides in the ENSDF database. Highlights: of this evaluation are the following: In {sup 59}Fe, a new level at 568.45 keV (3/2{sup −}) has been added. This resolves a doublet at 570 keV, which was reflected in earlier evaluations (1983An22, 1993Ba85, 2002Ba42) and literature as well. Conflicting spin assignments for 2153.62 keV level of {sup 59}Co [9/2,13/2 in (α,pγ); (13/2) in ({sup 15}N,4nγ); 15/2 in (p,p′γ), (7/2{sup −}) in (n,n′γ)] exist in the literature and additional experimental work is needed to resolve the issue.
Format requirements of thermal neutron scattering data in a nuclear data format to succeed the ENDF format
In November 2012, the Working Party on Evaluation Cooperation Subgroup 38 (WPEC-SG38) began with the task of developing a nuclear data format and supporting infrastructure to replace the now nearly 50 year old ENDF format. The first step in this process is to develop requirements for the new format and infrastructure. In this talk, I will review the status of ENDF's Thermal Scattering Law (TSL) formats as well as support for this data in the GND format (from which the new format is expected to evolve). Finally, I hope to begin a dialog with members of the thermal neutron scattering community so that their data needs can be accurately and easily accommodated by the new format and tools, as captured by the requirements document. During this discussion, we must keep in mind that the new tools and format must; Support what is in existing data files; Support new things we want to put in data files; and Be flexible enough for us to adapt it to future unanticipated challenges.
Unrecognized Sources of Uncertainties ( USU ) in Experimental Nuclear Data
Evaluated nuclear data uncertainties reported in the literature or archived in data libraries are often perceived as unrealistic, most often because they are thought to be too small. The impact of this issue in applied nuclear science has been discussed widely in recent years. Commonly suggested causes are: poor estimates of specific error components, neglect of uncertainty correlations, and overlooked known error sources. However, instances have been reported where very careful, objective assessments of all known error sources have been made with realistic error magnitudes and correlations provided, yet the resulting evaluated uncertainties still appear to be inconsistent with observed scatter of predicted mean values. These discrepancies might be attributed to significant unrecognized sources of uncertainty ( USU ) that limit the accuracy to which these physical quantities can be determined. The objective of our work reported herein has been to develop qualitative and quantitative procedures for revealing and including USU estimates in nuclear data evaluations involving experimental input data. This paper identifies several specific clues that can be explored by evaluators in identifying the existence of USU . It then describes numerical procedures we have introduced to generate quantitative estimates of USU magnitudes. Key requirements for these procedures to be viable are that sufficient numbers of data points be available, for statistical reasons, and that additional supporting information about the measurements be provided by the experimenters. Several realistic examples are described here to illustrate these procedures and demonstrate their outcomes and limitations. Our work strongly supports the view that USU is an important issue in nuclear data evaluation, with significant consequences for applications, and that this topic warrants further investigation by the nuclear science community.
ENDFtk: A robust tool for reading and writing ENDF-formatted nuclear data
ENDFtk is a recently developed C++ and Python interface to interact with ENDF-6 formatted nuclear data files. It provides a robust and complete interface, allowing the reading and writing of all formats currently part of the ENDF-6 formats manual, as well as some non-ENDF formats used by the NJOY processing code. It provides an interface that mimics the names in the ENDF-6 formats manual as well as an equivalent interface using human-readable attribute names. It is robust and powerful enogh for nuclear data experts to develop complex applications, while also simple enough to be used non-experts to retrieve and manipulate evaluated nuclear data. ENDFtk offers the ability to easily interrogate and manipulate data either in large-scale code projects or in simple Python scripts. Here, in this paper, a brief overview of the interface is given, as well as more substantial examples demonstrating plotting simple data, interacting with more complex data, and writing new data to files. ENDFtk is open source and available for download via GitHub (https://github.com/njoy/ENDFtk).
WPEC SG44 Subgroup Report: Investigation of Covariance Data in General Purpose Nuclear Data Libraries [Slides]
Presentations were as follows: Progress on the Development of Thermal Scattering Covariance Formats, New Paradigm for Nuclear Data Evaluation, The Role of Fission Yield Correlations to Obtain Realistic Uncertainty Values in the Summation Method, ENDF/B-VIII.0 Augmented Covariance Data: The First Iteration, Status and Requirements of Nuclear Data Variance-Covariance Matrices for the Neutronic Assessment of Fast Reactor Cores, The Identification and Treatment of Unrecognized Uncertainties and the Impact on Evaluated Uncertainties– SG44, Improved Calibration of Nuclear Resonance Parameters, Report on the CSEWG Covariance and Measurement Session Initiative on Creating Templates of Expected Measurement Uncertainties, The Nuclear Data Belief Network, Investigation of Covariance Data in General Purpose Nuclear Data Libraries, and Computational Benchmark Proposal.
Hierarchical Data Format for Nuclear Data Sensitivities
The SCALE code system includes capabilities for sensitivity and uncertainty (S/U) analysis as part of its TSUNAMI code suite. The sensitivity of a quantity of interest (for example, an application’s $k_{eff}$) to nuclear data is stored as a profile in a text-based file, which is known as a sensitivity data file (SDF). The sensitivity profile can be used to calculate uncertainties, correlation coefficients, and similarity indices. One of the goals of the present work was to seek general performance improvements in the TSUNAMI code suite, starting with the TSUNAMI-IP code for calculating similarity indices. Through profiling, it was found that reading the text-based sensitivity files was a performance bottleneck in the TSUNAMI-IP code. In a typical TSUNAMI-IP calculation, an application might be compared to thousands of benchmarks, thus requiring the reading of thousands of SDFs. Reading of binary-based data is generally faster than reading text-based data. Hierarchical Data Format 5 (HDF5) is a binary-based format that also benefits from being portable, and it can be inspected with nonproprietary tools. This paper describes an HDF5-based file format that has been introduced for SDFs.
Nuclear Data Sheets for A=258☆
Spectroscopic data for A=258 nuclides have been updated and re-evaluated, superseding the data presented in the previous evaluation 2001Ak11 published by Y.A. Akovali. The excited state data for A=258 nuclei are largely unknown. With the exception of three low-energy gamma rays in {sup 258}Db from {sup 262}Bh α decay, no other gamma-ray data are available for A=258 nuclei.
Application of Artificial Neural Networks to Reliable Nuclear Data for Nonproliferation Modeling and Simulation
Detection and identification of special nuclear materials (SNMs) are an essential part of the US nonproliferation effort. Modern cutting-edge SNM detection methodologies rely more and more on modeling and simulation techniques. Experiments with radiological samples in realistic configurations, is the ultimate tool that establishes the minimum detection limits of SNMs in a host of different geometries. Modern modeling and simulation approaches have the potential to significantly reduce the number of experiments with radioactive sources needed to determine these detection limits and reduce the financial barrier to SNM detection. Unreliable nuclear data is one of the principal causes of uncertainty in modeling and simulating nuclear systems. In particular, nuclear cross sections introduce a significant uncertainty in the nuclear data. The goal of this research is to develop a methodology that will autonomously extract the correct nuclear resonance characteristics of experimental data in a reliable way, a task previously left to expert judgement. Accurate nuclear data will in turn allow contemporary modeling and simulation to become far more reliable, de-escalating the extent of experimental testing. Modeling and simulation techniques reduce the use and distribution of radiological sources, while at the same time increase the reliability of the currently used methods for the detection and identification of SNMs.