While many of his classmates remain on campus to do their research, Daniel Campbell '08 (Pittsford, N.Y.) is working off-campus this summer, at the National Institute of Standards and Technology (NIST). Campbell is working on several projects, but his main one deals with improving the accuracy of the results of a previous neutron experiment. He is trying to simulate the effects of redesigning two pieces of his apparatus in the hopes of reducing neutron collision.
Campbell's research deals with free neutrons, unstable neutrons which exist outside of atomic nuclei decay into other atomic particles. All particles that decay into charged particles give off photons; Campbell works on an experiment called Radiative Decay (RDK) which detects the radiation of neutrons when they decay. RDK also detects how often the photon is released, and the typical energy of that particle; it marks the first time that scientists attempted to measure the radioactive decay from neutrons. The first time it was run, RDK conclusively detected neutron radiation.
In the apparatus, neutrons rarely give off gamma radiation in decay, but they always give off gamma rays when they collide with something. Jeff Nico of the NIST, who is acting as one of Campbell's two advisors (the other is Hamilton Associate Professor of Physics Gordon Jones), suspects that some of the high background radiation of the first RDK experiment was due to stray neutrons impacting with the apparatus; Campbell, then, has the job of redesigning the apparatus to keep the neutrons from straying.
He does this by analyzing the data from a computer program called a Monte Carlo simulation. The program "runs a particle through all the events which it would be subjected to in reality and compute[s] the position and probability of survival for that particle every step of the way." He also adjusted the parameters of the Monte Carlo with the goal of collimating the neutron beam ("make it narrow with no stray electrons"), which required some adjustment to the guide tube and the collimator.
The guide tube is a tube with a "reflective coating that allow[s] neutrons from the nuclear reactor…to bounce along to the experiment." Campbell modified the length of the guide tube and the coating. The collimator is "a 2.57 meter evacuated tube that absorbs any neutrons that stray from the center of the tube."
Campbell has been quite successful with his modeling. He explains, "as of this point…I have effectively modeled all the nuances of the guide tube and collimator that affect beam collimation and have provided some suggestions for changes that can improve collimation to a degree necessary to prevent neutrons from hitting the apparatus while still keeping neutron flux at about the same level." He is also working on an "unofficial" project which deals with neutron polarization and requires him to design pieces of apparatus for a 3He neutron polarization experiment.
Campbell, a physics major, is based at the NIST for the summer. He has done summer research at Hamilton before (sol-gel research with Professor Silversmith) but decided on this option instead of staying at Hamilton. He explains that one experience he cannot get at Hamilton is "science on a large scale and research as part of a research group." It has given him "an idea of the skills that I will need for physics research in the future," which for Campbell includes a doctoral degree and a career in either teaching or research. The largest difference between his work at NIST and at Hamilton is the project size. "I'm working on just a piece of a larger project and working in collaboration with a number of researchers on a project that required years even to set up."
-- Lisbeth Redfield
