Caleb Sword – 2016

Sword_3Determining the Nuclear Structure of an Unstable 25O Isotope

Research Advisor: Dr. Paul DeYoung

One of the primary goals of nuclear physics research is to better understand the force that binds nucleons. This can be accomplished by studying the structure of neutron-rich isotopes. For this experiment, excited 25O nuclei were formed by a collision between a 101.3 MeV/u 27Ne ion beam and a liquid deuterium target at the National Superconducting Cyclotron Laboratory. One resulting reaction involved two-proton removal from 27Ne particles, which created excited  25O nuclei that decayed into three neutrons and an 22O fragment. The four-vectors for the neutrons and 22O fragments were determined, allowing the calculation of the decay energy for this process on an event-by-event basis. However, another reaction would also take place, in which an alpha particle was stripped from the beam, creating 23O nuclei that decayed into an 22O fragment and a single neutron. In order to distinguish between 22O fragments and neutrons from both 25O and 23O isotopes, members of the MoNA collaboration are conducting GEANT4 simulations of each decay process in order to uncover their distinguishing characteristics. By successfully correlating simulated decay processes to experimental data, the relative cross sections of the two decay processes will be determined, and their decay energies will reveal more about their nuclear structures.

This work is supported by the National Science Foundation under grants No. PHY-1306074 and No. DUE-1153600; and by the Hope College Division of Natural and Applied Sciences and the Hope College Department of Physics.

Elizabeth Lindquist – 2016

Lindquist_1PIXE-NRA Analysis to Determine Metalloprotein Stoichiometry

Research Advisor: Dr. Paul DeYoung

An Ion Beam Analysis (IBA) technique of simultaneous Particle-Induced X-ray Emission (PIXE) and Nuclear Reaction Analysis (NRA) is being developed to determine the complete stoichiometry of metalloproteins. Even though approximately one third of all proteins are metalloproteins, the stoichiometric ratios of the metalloproteins are still largely unknown. Current elemental analysis procedures are capable of characterizing which metals are in a protein, but it is difficult to determine the absolute quantity of metal atoms per protein. To address this, an IBA method is being developed which incorporates coupled PIXE and NRA.  PIXE characterizes the areal density of the metal elements in the sample, while NRA uses Rutherford scattering cross-sections to determine the areal density of the proteins. This combination allows for an accurate determination of the desired metal-to-protein ratio. The method is being validated with the Cyanocobalamin (B12) and Cytochrome C Equine proteins which have known metal-to-protein stoichiometries. After the method has been validated, the IBA technique will be extended to new metalloproteins. This methodology will allow for future characterization of metalloproteins with unknown stoichiometry.

This work is supported by the National Science Foundation under grant 1306074.

Jason Gombas – 2016

GombasRefining the r-process Described by Theoretical Models

Research Advisor: Dr. Paul DeYoung

Where did all of the heavy elements originate? The rapid neutron capture process (r-process), currently only characterized by theoretical calculations, model the nuclear reactions that lead to heavier nuclei in intense astrophysical locations such as supernovas. Experimenting with the few reactions reproducible on Earth can refine the theoretical calculations of reactions currently impossible to replicate. A cocktail beam of heavy nuclei associated with the r-process around 104Nb with a magnetic rigidity of 3.2097Tm was produced at the National Superconducting Cyclotron Laboratory. The beam implanted in an energy and position detector located inside an efficient gamma detector called the Summing NaI(Tl) detector (SuN). Beta-decay events were correlated to implantation events to identify the A and Z of the decayed nucleus. Using the correlated gamma-ray energies measured in SuN, values such as the beta-decay intensity distribution will then be calculated and compared to values predicted by models that are used to calculate the abundance distribution of the various nuclei observed today.

This material is based upon work supported by the National Science Foundation under grant No. PHY-1306074

Grant to Nuclear Group Continues Three Decades of NSF Support

A new major research grant from the National Science Foundation (NSF) to the Nuclear Group at Hope College continues three decades of support from the agency, a long-time run which if not unique is at the very least rare, reflecting the quality of the work being conducted.

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