This award provides funds for continuing support of research at the University of Notre Dame Nuclear Science Laboratory. The laboratory presently operates three accelerators and maintains an active research program in nuclear astrophysics and nuclear structure physics. While interdisciplinary research opportunities have introduced new user groups with different objectives to the laboratory, the nuclear group itself has maintained strong focus on its core program in low energy nuclear physics.
Nuclear astrophysics has emerged as the main research direction, taking advantage of all three accelerators. New equipment has been developed which will provide new opportunities to investigate very low energy cross sections of reactions relevant for stellar burning. Studies range from the direct measurement of nuclear reactions during stellar thermonuclear burning to the experimental and theoretical investigation of nuclear processes far from stability which are relevant for the study of nucleosynthesis in explosive stellar scenarios such as core collapse supernovae to cataclysmic binary stars.
The nuclear structure program has focused on aspects closely correlated to nuclear astrophysics questions such as the determination of nuclear masses and decay times for far off stability isotopes, the nuclear properties of weakly bound systems, the measurement of nuclear incompressibility, and the study of rare nucleosynthesis processes using accelerator mass spectroscopy (AMS). An increasingly important initiative is the study of the fate of nuclear matter at high densities, ranging from pycnonuclear burning to the determination of the incompressibility of nuclear matter.
Parallel to these efforts new applied programs such as PIXE and AMS have been developed which are presently being utilized for applications in Art, Archaeology, and Anthropology, in Oceanography, and in the search of new forms of matter (Weakly Interacting Massive Particles). The laboratory provides an ideal recruitment and training environment for undergraduate and graduate students. In addition, the lab involves RET teachers and REU students in various research projects over the summer.
This is the final report on the NSF grant period from 2008 to 2011 for the Nuclear Science Laboratory (NSL) at the University of Notre Dame. The NSL is a mid-sized accelerator laboratory serving the local nuclear physics group including 5 faculty members, 6 post-doctoral research scientists, 28 graduate students, and a large number of undergraduate students. The NSL also serves a large national and international user community. During the 2008-2011 funding period, the NSL continued its experimental program in nuclear astrophysics and nuclear structure physics. Parallel to that the group also broadened it program by adding a new research component in nuclear physics applications using accelerator based X-ray analysis and isotope dating techniques. The main research focus was the understanding of the chemical evolution of our universe from the production of primordial elements in the Big Bang and the origins of the observed elemental abundance distributions in first generation stars, to the elemental and isotopic abundance distribution in our present universe. With this perspective in mind the group developed a successful program in studying key nuclear processes guiding and controlling the sequence of quiescent burning stages of stellar evolution as well as nuclear reactions and decay processes which trigger or drive stellar explosions. Theoretical simulations were performed to identify these reactions, which were studied using new technologies and instrumentation developed at the laboratory. The measurement of reactions in hydrogen-, helium-, and carbon burning were primarily made at the NSL facilities, but included also experiments at underground laboratories protected from cosmic ray background. Primary goal was the determination of stellar nucleosynthesis and the identification of new observables such as neutrino and gravitational wave emission. The understanding of nucleosynthesis studies in explosive environments requires measurements of short-lived radioactive nuclei. These studies were performed at the NSL TwinSol facility but also at other radioactive beam facilities in the US and Europe to investigate the origin of the heavy elements, determine the sources of the observed galactic radioactivity distribution, and probe the nature of extremely dense matter in neutron stars. Nuclear Structure research is carried out in our laboratory and at other institutions to study nuclear vibrations reflected in giant resonances and other excitation modes depending on the deformed shape of the nucleus. Exotic nuclear rotation modes were explored using techniques of g-ray spectroscopy. Special attention was given to the question of nuclear chirality, or the left- and right-handed nature of nuclei. Other research efforts addressed the evolution of nuclear structure in nuclei with only a limited number of protons and neutrons towards the limits of stability to test the quality of new approaches in ab-initio calculations of the quantum behavior of few body systems. In addition to the basic research program, the NSL group has developed a new program in nuclear applications in connection with other research groups at the campus of Notre Dame. This included material studies using Particle Induced X-ray Emission (PIXE) as well as material dating using Accelerator Mass Spectrometry (AMS) at newly developed NSL facilities. These developments introduced a large number of new users from physics, engineering, and the liberal arts communities to the laboratory.
