Part 2 of 2 Parts (Please read Part 1 first)
      Sometimes the shape of resonances cannot be determined, and the cross section cannot be modeled accurately. However, much can still be learned about the resonances if a statistical analysis of their energies is conducted. Rodriguez has been attempting to take advantage of this approach with machine learning techniques and what is called random matrix theory.
    He starts with the range of energy resonances from the isotope under examination, then he sorts them by assigning a combination of quantum numbers to each. This can be explained by comparison to sorting marbles in a bucket because these resonances fall into groups. Rodriguez said, “Let’s imagine there are red, blue, and green marbles in a bag. You have to sort the marbles into buckets by color, and you’re not allowed to look. All you can do is see what the average color of each bucket is when you put all the marbles in together. So, at first, you end up with three buckets that, from a distance, look brown because all the colors are mixed.” These mixtures are similar to the resonances being random or incorrect quantum number assignments.
      Brown said, “But now we can take out one marble and put it in one of the other buckets, and then see if the average color of that bucket changed. Again, we’re only allowed to look at the average color of each bucket.” Rodriguez said, “Then we start reclassifying those marbles, or energy resonances, using the statistics provided by the theory. We keep repeating this until we get a blue bucket, a green bucket, and a red bucket – a clear separation of the resonances.”
    Rodriguez has been studying uranium-238 due to the large amount of data that is available for this isotope. Researchers have been trying to understand this isotope for seventy years. In spite of the fact the nuclear reactors obviously work, assigning the correct quantum numbers to sequences of resonances is still somewhat slow.
    Brown and Rodriguez are hoping that the use of random matrix theory to assign neutron resonances may improve the process. Brown said, “It’s kind of amazing that with the right statistical mindset, we can do this so quickly and so easily.” Rodriguez said, “From what David told me.no one has tried this stuff before—the path we’re taking, it is kind of new.” Brown added, “Having the fresh eyes on the problem brings a lot of energy and it brings new ideas. And honestly, Pedro’s poking around in ways that I didn’t think to poke around, and it has definitely helped dramatically.”
     David Brown manages a library of nuclear data files at the NNDC. He is interested in finding ways to simplify the correct modeling of nuclear fission reactors.    
     Rodriguez decided that he wanted to study physics at a young age. He will graduate next spring with his bachelor’s degree in theoretical physics from the University of Puerto Rico Mayaguez Campus. After graduation, he wans to pursue a Ph.D. in experimental physics but has not yet chosen a particular university.