Network Analysis of Nuclear Databases

representation of the connections in EXFOR, similar to graphs of social networks, authorship networks, etc. By analyzing this abstract graph, we are able to address very specific questions such as 1) what observables are being used as reference measurements by the experimental nuclear science community? 2) are these observables given the attention needed by various nuclear data evaluation projects? 3) are there classes of observables that are not connected to these reference measurements? In addressing these questions, we propose several (mostly cross section) observables that should be evaluated and made into reaction reference standards. I. PROBLEM AND MOTIVATION In the early 1950’s, the Department of Energy’s Brookhaven National Laboratory began compiling and archiving nuclear reaction experimental data in the SCISRS database [1]. Over the years, this project has grown and evolved into the EXFOR project [2]. EXFOR is an international experimental nuclear data collection and dissemination project now led by the IAEA nuclear data section, coordinating the experimental nuclear data compilation and archival work of several nations. The EXFOR nuclear experimental database provides the data which underpins nearly all evaluated neutron and charged particle evaluations in ENDF-formatted nuclear data libraries (e.g. ENDF/B, JEFF, JENDL, .). Therefore, EXFOR is in many ways the “mother library” which leads to the nuclear data used in all applications in nuclear power, security, nuclear medicine, etc. The EXFOR database includes a complete compilation of experimental neutron-induced, a selected compilation of charged-particle-induced, a selected compilation of photon-induced, and assorted high-energy and heavy-ion reaction data. The EXFOR library is the most comprehensive collection of experimental nuclear data available. Therefore, it is the best place to look for an overview of what the applied and basic experimental nuclear science communities feel are valuable experimental reactions and quantities [1, 2]. In this work, we take an abstract view of the EXFOR database and generate an undirected graph describing all the connections between reactions/quantities in the EXFOR database. From just these connections, we can infer what reactions/quantities the nuclear science community collectively (and somewhat unconsciously) views as important. The basic unit of EXFOR is an ENTRY. An ENTRY corresponds to one experiment and contains the numerical data, the related bibliographic information and a brief description of the experimental method. What an EXFOR ENTRY really represents is the results of work that was performed at a given laboratory at a given time. An ENTRY does not necessarily correspond to one particular publication, but very often corresponds to several publications. The EXFOR compiler takes the essential information from all available sources, and if needed, contacts the author for more information. Our goal is to be able to view the EXFOR database in a way previously unseen. We wish to take the data, compiled by experimental physicists and analyzed by theoretical physicists and draw mathematical connections between the two groups. We will utilize Python to transform the database into our graph and run data analysis using our network theory metrics. We intend to compare our graph to other real life networks and look for similarities and differences that may be able to help us draw upon patterns and graph motifs in our analysis. It is our hope that we will be able to either verify existing nuclear data measurements or draw conclusions for future data measurements. II. BACKGROUND AND RELATED WORK An entry is typically divided in several SUBENTs containing the data tables resulting from the experiment. Each SUBENT contains a REACTION field which encodes what reaction was studied (e.g. H(n,el)) and what quantity was measured (e.g. cross-section or angular distribution). A SUBENT may also contain a MONITOR field which encodes one or more well characterized reactions and quantities used to reduce or eliminate systematic experimental errors. Thus, reaction monitors are an important part of experimental data reduction. Often the measured data encoded in the REACTION field is measured relative to the reaction/quantity encoded in the MONITOR field. There is usually a straightforward mapping between the reactions/quantities measured in EXFOR and the evaluated reactions/quantities stored in the ENDF libraries. Several specific reaction/quantities are important enough, usually because of one or more specific applications, that the nuclear data community has elevated them