CERN is the large particle physics laboratory that straddles the French-Swiss border just outside Geneva. Arguably, the most newsworthy discoveries that come from CERN involve the Large Hadron Collider; however, there are other, lower-energy experiments performed at CERN as well. Dr. Zacate has been participating in such experiments at CERN’s On-Line Isotope Mass Separator Facility (ISOLDE) on and off for the past 21 years.
In June of 2015, he and NKU student Nathan Dasenbrock-Gammon, who is majoring in physics and mathematics, spent 8 days there to use the exotic, short-lived radioactive isotope 111mCd to study site-occupation and diffusion effects in Pd3Ga7 via a method called perturbed angular correlation spectroscopy. This work was motivated in part by exploratory measurements made back in 2011 during Dr. Zacate’s last trip to CERN with two former NKU physics majors, James Castle and Alex Leduc. It is part of an international collaboration with Gary Collins and students at Washington State University, who produced the Pd3Ga7 samples; Manfred Deicher and Herbert Wolf of the Universität des Saarlandes in Saarbrücken, Germany, who provided the on-site spectrometers and assisted with experiments; and Karl Johnston and other members of the ISOLDE Collaboration. The 2015 trip was made possible by funds provided through a NKU College of Arts and Sciences Collaborative Faculty Student Project Award.
At the time this newsletter is being put together, it is too early to say conclusively what the results of the measurements mean. In short, the 2015 series of measurements confirms the existence of two unexpected signals observed in 2011 and helps define the experimental conditions needed to produce the signals. It is anticipated that follow-up computer simulations based upon density functional theory, to be carried out at NKU during the fall semester, and additional measurements to further characterize the samples via, for example, x-ray diffraction will bring clarity to the interpretation.