April 4, 2013
Every three years, the international nuclear data community holds a meeting to network and exchange information about issues and developments in the field. The 2013 meeting, held in early March in New York City, was organized by the National Nuclear Data Center (NNDC), headquartered at the U.S. Department of Energy's (DOE) Brookhaven National Lab for the past 50 years.
The NNDC collects, evaluates, archives and disseminates nuclear physics data for basic nuclear research and for applied nuclear technologies. The information contained in the NNDC's databases is of interest to scientists involved in pure research, as well as to applied researchers in areas such as nuclear medicine and nuclear power. The databases are increasingly consulted by astrophysicists and other researchers who are discovering their usefulness in other fields. Nuclear data also continue to be important for national security applications such as nonproliferation, homeland security, and stockpile stewardship.
DOE Program Manager for Nuclear Data and Nuclear Theory Computing Ted Barnes was among those attending the conference.
"The Nuclear Data Program is very important to us in DOE in part because it's an area that's of immediate relevance to the outside world," he said. "This program insures that the public has access to the most accurate experimental data currently available relating to nuclear physics. This is especially important for industrial applications of nuclear physics, for example in nuclear reactor safety and design. In computer studies of the operation of a nuclear reactor, it's obviously very important to use accurate physics, such as the absorption probabilities of neutrons and production rates of radioactive isotopes; these numbers are provided by our databases. Industries that use applications of nuclear physics typically consult the databases provided by the Nuclear Data Program to find the most accurate experimental results of relevance to their application.
"The nuclear data effort also encourages and supports improved measurements when the existing numbers are no longer sufficiently accurate, or do not provide the specific information needed," he said. "This meeting is also a point-of-contact for the worldwide nuclear data community, in which they assess the status of nuclear physics databases, determine which areas need additional work, and identify nuclear data needs in new areas that often represent some very interesting and unusual spinoffs."
Los Alamos National Laboratory (LANL) registered 23 conference participants, many of them speakers, the largest contingent from any single organization. Mark Chadwick, leader of LANL's Computational Physics Division, was on the international organizing committee, and LANL also provided financial support for the conference.
"Nuclear science is one of our major capabilities at Los Alamos, so it's an important opportunity for us," he said. "Like all conferences, this one is important because it allows us to share our results with the broader community. It's very important to have scientists interacting with leaders from other countries and Labs to get feedback on issues that we might be facing or need to be aware of. That's part of the very rigorous peer review that's very important for us. In addition, we like to ensure that we're aware of all the breakthroughs that have been made in everything from experiment to simulation to theory. Typically, at conferences like this I find that I know of a number of things going on but I'm always surprised at the additional things that I wasn't aware of. This is an efficient way to find new data that I wasn't aware of, see how that validates or invalidates some of the capabilities that we have at Los Alamos, and essentially make sure that we're at the cutting edge of the nuclear science that's going on."
Robin Forrest, Nuclear Data Section head for the International Atomic Energy Agency (IAEA), gave a talk at the conference on possible new database formats.
"There are a lot of people wanting to take things significantly forward with new data formats, and I think that's going to be very important," he said. "People are realizing that this is an important area of work and there is a shrinking community of people who are experts, so international collaboration is extremely important."
In addition to networking and learning about new uses of nuclear data, participants were also mindful of the need to recruit young and diverse researchers into the field. Of the nearly 450 participants, 69 were women. There were 71 students and 35 postdocs, many of them responsible for presentations.
Caroline Nesaraja from Oak Ridge National Laboratory (ORNL) chaired a session on Neutron Cross Section Measurements. She is a nuclear structure evaluator who represents ORNL on the evaluation of nuclear structure and decay data for known nuclei that is included in the ENSDF (Evaluated Nuclear Structure and Decay Data File) database at NNDC.
"It's a database containing experimental nuclear physics structure information that is needed by researchers and is of vital importance for a large number of nuclear applications," she said. "We take published results from experiments and adopt a particular value or what we call 'best value' that can be used as a standard for others. If every person is using a different value, then you can't compare results. For doing calculations, you have to standardize."
Nesaraja said she and her fellow nuclear structure evaluators are a small community, considering the amount of work that needs to be done.
"We have to read a lot of scientific publications," she explained. "Sometimes one mass chain can contain more than 500 different papers. We make critical assessments and extract the nuclear physics data out of it, then adopt the 'best value' for the particular nuclear level.
"Not too many people are getting into this field because it can be very tedious," Nesaraja said. "We see a lot of talented young people at data conferences such as this one who are either experimentalists or theorists and we would like to encourage these younger scientists to get involved in the evaluation process as well. There are much more precise nuclear data measurements published now due to better experimental capabilities and sophisticated detectors and we need more evaluators to handle this ever increasing amount of nuclear data."
Chadwick pointed out that 2013 marks 75 years since the discovery of nuclear fission.
"Even after 75 years, there's a tremendous renaissance going on in the science of fission," he said. "Many labs have new capabilities in very high precision work that wasn't possible before. They're building upon advances and investments by the DOE in this country, and in other countries as well. We're seeing some exciting results from some European Labs including CERN and IRMM in Belgium. Japan has some new facilities coming online so we're seeing some measurements of quantities such as neutron capture that are changing our current understanding. If they are right, they will be important for long term advances in the field."
Paolo Gondolo, a professor of physics and astronomy at the University of Utah and director of the Astrophysics Institute, researches the nature of dark matter. His talk was titled "Wanted! Nuclear Data for Dark Matter Astrophysics."
"A few years ago I became interested in nuclear aspects of dark matter searches," he said. "There were claims that dark matter would produce the positron signals in the PAMELA detector in excess of some expected background. I asked myself how well do we know that background? It turns out that there are very few nuclear data in the relevant energy region. Other claims of dark matter detection are based on collisions of dark matter with nuclei in the laboratory, sometimes interacting with the nucleons spin. We need to know where the spin is located inside the nucleus, and there seem to be only theories, but no data. My collaborator convinced me that I should come to this meeting because we couldn't find any data, so I'm here to ask for it."
Barnes was surprised to hear of Gondolo's request.
"Dark matter! That's a new one," he said. "But one of things we're doing here is looking for future applications of nuclear data, things that hadn't even been imagined yet. "
The online NNDC libraries are often used by the general public, as well as by scientists. There was a noticeable uptick in use of the Center's website after the case of the Russian spy poisoned by polonium hit the newspapers some years ago.
Conference co-chair Alejandro Sonzogni from BNL said it was the best-attended nuclear data conference in the past 10 years.
"People were happy to come and I believe the reason is the location," he said. "These
conferences are rare in NYC and we had a very diverse program."
Brookhaven Nuclear Science and Technology Department Chair Bill Horak said, "Hosting an international conference like this is a tremendous challenge and the staff of the NNDC and the Global and Regional Solutions Directorate really worked hard to make it a success."
2013-3759 | INT/EXT | Media & Communications Office