J. Browne

A gas jet target for radioactive ion beam experiments

New radioactive ion beam (RIB) facilities, like FRIB in the US or FAIR in Europe, will push further away from stability and enable the next generation of nuclear physics experiments. Thus, the need for improved RIB targets is more crucial than ever: developments in exotic beams should coincide with developments in targets for use with those beams, in order for nuclear physics to remain on the cutting edge. Of great importance to the future of RIB physics are scattering, transfer and capture reaction measurements of rare, exotic, and unstable nuclei on light targets such as hydrogen and helium. These measurements require targets that are dense, highly localized, and pure, and conventional targets often suffer too many drawbacks to allow for such experimental designs. Targets must also accommodate the use of large area, highly-segmented silicon detector arrays, high-efficiency gamma arrays, and novel heavy ion detectors to efficiently measure the reaction products. To address this issue, the Jet Experiments...

Low-lying level structure of Cu 56 and its implications for the rp process

The low-lying energy levels of proton-rich Cu56 have been extracted using in-beam γ-ray spectroscopy with the state-of-the-art γ-ray tracking array GRETINA in conjunction with the S800 spectrograph at the National Superconducting Cyclotron Laboratory at Michigan State University. Excited states in Cu56 serve as resonances in the Ni55(p,γ)Cu56 reaction, which is a part of the rp process in type-I x-ray bursts. To resolve existing ambiguities in the reaction Q value, a more localized isobaric multiplet mass equation (IMME) fit is used, resulting in Q=639±82 keV. We derive the first experimentally constrained thermonuclear reaction rate for Ni55(p,γ)Cu56. We find that, with this new rate, the rp process may bypass the Ni56 waiting point via the Ni55(p,γ) reaction for typical x-ray burst conditions with a branching of up to ∼40%. We also identify additional nuclear physics uncertainties that need to be addressed before drawing final conclusions about the rp-process reaction flow in the Ni56 region.

Time-of-flight mass measurement of neutron-rich nuclei

Zach Meisel∗bd f , S. Georgec, S. Ahnb f , J. Brownebd f , D. Bazind f , F. Carpino j, H. Chung j, A. Estradeh, M. Famiano j, A. Gaded f , C. Langerb f , M. Matosg, W. Mittigd f , F. Montesb f , D. Morrisseyde, J. Perierab f , H. Schatzbd f , J. Schatz, M. Scottd f , D. Shapirag, K. Smithbi, J. Stevensbd f , W. Tani, O. Tarasov f , S. Towers j, K. Wimmera f , J. Winkelbauerd f , J. Yurkon f , and R.G.T. Zegersbd f a Department of Physics, Central Michigan University, Mt. Pleasant, MI, USA b Joint Institute for Nuclear Astrophysics, East Lansing, MI, USA c Max-Planck-Institut fur Kernphysik, Heidelberg, Germany d Department of Physics and Astronomy, Michigan State University, East Lansing, MI, USA e Department of Chemistry, Michigan State University, East Lansing, MI, USA f National Superconducting Cyclotron Laboratory, East Lansing, MI, USA g Oak Ridge National Laboratory, Oak Ridge, TN, USA h School of Physics and Astronomy, The University of Edinburgh, Edinburgh, UK i Department of Physics, University of Notre Dame, South Bend, IN, USA j Department of Physics, Western Michigan University, Kalamazoo, MI, USA