Atomic nuclei play an important role in the evolution of matter in our universe. For many problems in astrophysics, cosmology, and particle physics, the detailed properties of atomic nuclei provide essential inputs to the solutions.
Our group’s research focuses on studying nuclei experimentally to probe fundamental questions about our universe. For example, we measure nuclear reactions, decays, and masses in the laboratory to learn about the reactions that power exploding stars or affect their synthesis of chemical elements. Similar experiments can contribute to searches for physics beyond the standard model of particle physics. In some cases we can use these low energy nuclear physics techniques to directly measure the reactions that occur in stars or to directly search for new physics.
Our program at NSCL is currently focused on measuring the beta decays of proton-rich nuclides. With these experiments, we hope to constrain the nuclear structure details that are most influential on the explosive burning of hydrogen on the surfaces of accreting compact stars such as white dwarfs and neutron stars. Additionally, these experiments can allow us to better constrain the effects of isospin-symmetry breaking in nuclei on tests of the unitarity of the Cabibbo-Kobayashi-Maskawa matrix, a cornerstone of the standard model.
Students in our group have opportunities to propose, prepare, execute, analyze, and interpret nuclear -physics experiments at NSCL, to publish the results in leading scientific journals, and to present the results at national and international conferences.
Selected Nuclear Astrophysics Publications:
Isospin Mixing Reveals 30P(p, γ)31S Resonance Affecting Nova Nucleosynthesis, M. B. Bennett, C. Wrede, et al., accepted for publication in Phys. Rev. Lett.
Observation of Doppler broadening in beta delayed proton-gamma decay, S. B. Schwartz, C. Wrede, et al., Phys. Rev. C 92, 031302(R) (2015)
Discovery of 34g,mCl(p, γ)35Ar resonances activated at classical nova temperatures, C. Fry, C. Wrede, et al., Phys. Rev. C 91, 015803 (2015)
Shell-model studies of the astrophysical rapid-proton capture reaction 30P(p, γ)31S, B. Alex Brown, W. Richter, C. Wrede, Phys. Rev. C 89, 062801(R) (2014)
The 30P(p, γ)31S reaction in classical novae: progress and prospects, C. Wrede, AIP Advances 4, 041004 (2014)
Classical Nova Contribution to the Milky Way's 26Al abundance: Exit channel of the key 25Al(p, γ)26Si resonance, M. B. Bennett, C. Wrede et al., Phys. Rev. Lett. 111, 232503 (2013)
Evidence for the existence of the astrophysically important 6.40-MeV state of 31S, D. Irvine et al., Phys. Rev. C 88, 055803 (2013)
Constraining nova observables: Direct measurements of resonance strengths in 33S(p, γ)34Cl, J. Fallis et al., Phys. Rev. C 87, 065801 (2013)
Nuclear structure of 30S and its implications for nucleosynthesis in classical novae, K. Setoodehnia et al., Phys. Rev. C 87, 065801 (2013)
γ-ray constraints on the properties of unbound 32Cl levels, C. Wrede et al., Phys. Rev. C 86, 047305 (2012)
Production of 26Al in stellar hydrogen-burning environments: Spectroscopic properties of states in 27Si, A. Parikh et al., Phys. Rev. C 84, 065808 (2011)
Mass measurements of isotopes of Nb, Mo, Tc, Ru, and Rh along the νp- and rp-process paths using the Canadian Penning trap mass spectrometer, J. Fallis et al., Phys. Rev. C 84, 045807 (2011)
Improving the 30P(p, γ)31S rate in oxygen-neon novae: Constraints on Jπ values for proton-threshold states in 31S, A. Parikh et al., Phys. Rev. C 83, 045806 (2011)
Branches of 33S(p, γ)34Cl at oxygen-neon nova temperatures, B. M. Freeman, C. Wrede et al., Phys. Rev. C 83, 048801 (2011)
Absolute determination of the 22Na(p, γ)23Mg reaction rate in novae, A. L. Sallaska, C. Wrede et al., Phys. Rev. C 83, 034611 (2011)
Direct Measurements of 22Na(p, γ)23Mg Resonances and Consequences for 22Na Production in Classical Novae, A. L. Sallaska, C. Wrede et al., Phys. Rev. Lett. 105, 152501 (2010)
Properties of 20Na, 24Al, 28P, 32Cl, and 36K for studies of explosive hydrogen burning, C. Wrede et al., Phys. Rev. C 82, 035805 (2010)
Structure of 30S with 32S(p,t)30S and the thermonuclear 29P(p, γ)30S reaction rate, K. Setoodehnia et al., Phys. Rev. C 82, 022801(R) (2010)
First direct measurement of the 23Mg(p, γ)24Al reaction, L. Erikson et al., Phys. Rev. C 81, 045808 (2010)
Toward an experimentally determined 26Alm(p, γ)27Si reaction rate in ONe novae, C. M. Deibel et al., Phys. Rev. C 80, 035806 (2009)
Thermonuclear 30S(p, γ)31Cl reaction in type I x-ray bursts, C. Wrede et al., Phys. Rev. C 79, 045808 (2009)
Measurements of 31S energy levels and reevaluation of the thermonuclear resonant 30P(p, γ)31S reaction rate, C. Wrede et al., Phys. Rev. C 79, 045803 (2009)
Thermonuclear 25Al(p, γ)26Si reaction rate in classical novae and Galactic 26Al, C. Wrede, Phys. Rev. C 79, 035803 (2009)
Determination of the proton separation energy of 93Rh from mass measurements, J. Fallis et al., Phys. Rev. C 78, 022801(R) (2008)
Addendum to “Measurement of 23Mg(p, γ)24Al resonance energies,” D. W. Visser, C. Wrede et al., Phys. Rev. C 78, 028802 (2008)
Measurement of 23Mg(p, γ)24Al resonance energies, D. W. Visser, C. Wrede et al., Phys. Rev. C 76, 065803 (2007)
New 30P(p, γ)31S resonances and oxygen-neon nova nucleosynthesis, C. Wrede et al., Phys. Rev. C 76, 052802(R) (2007)
Experimental evidence for a natural parity state in 26Mg and its impact on the production of neutrons for the s process, C. Ugalde et al., Phys. Rev. C 76, 025802 (2007)
Measurement of the Cascade Transition via the First Excited State of 16O in the 12C(α, γ)16) Reaction, and Its S Factor in Stellar Helium Burning, C. Matei et al., Phys. Rev. Lett. 97, 242503 (2006)
Measurement of the Ec.m. = 184 keV Resonance Strength in the 26Al(p, γ)27Si Reaction, C. Ruiz et al., Phys. Rev. Lett. 96, 252501 (2006)
Mass measurements of 22Mg and 26Si via the 24Mg(p,t)22Mg and 28Si(p,t)26Si reactions, A. Parikh et al., Phys. Rev. C 71, 055804 (2005)
The 21Na(p, γ)22Mg reaction from Ec.m.=200 to 1103 keV in novae and x-ray bursts, J. M. D'Auria et al., Phys. Rev. C 69, 065803 (2004)
21Na(p, γ)22Mg Reaction and Oxygen-Neon Novae, S. Bishop et al., Phys. Rev. Lett. 90, 162501 (2003)