Probing Nuclear Structure with Fast Neutrons

Overview: The research program at the University of Kentucky Accelerator Laboratory (UKAL) is focused on timely, related topics in nuclear structure and other areas of nuclear science for which the UKAL facilities are uniquely suited. Experimental innovations in our laboratory, coupled with the unique capabilities for the production of high quality, time-bunched monoenergetic neutrons, permit us to continue to address important questions and have played a key role in our success. Our detailed investigations of stable nuclei complement advances in nuclear structure achieved in studies of nuclei at extreme conditions of temperature and angular momentum or in regions far from stability. Collaborative research with colleagues from other institutions is emphasized. Intellectual Merit: We continue exploiting the advantages afforded by the inelastic scattering reaction with fast neutrons to investigate low-energy collective modes in nuclei and other nuclear properties. With this reaction, we are able to obtain information, such as level lifetimes and transition multipole mixing ratios for non-yrast states, which is inaccessible with other reactions or at other facilities. This broad-based research program includes selected studies in several forefront areas: nuclear structure relevant to double-beta decay; nuclei undergoing shape transitions; deformed structures and shape coexistence; nuclear structure contributions in support of searches for fundamental symmetries. Nuclear level lifetime measurements with the Doppler-shift attenuation method (DSAM), for which the methodology has been developed over many years in our laboratory, provide crucial information in many of these investigations. Additional projects that are particularly appropriate to the facilities at UKAL will be pursued. Broader Impacts : Education at the undergraduate, graduate, and post-graduate levels continues as the focus of the activities in our laboratory. Graduates of this research program receive hands-on experience with instrumentation, accelerator operation, data acquisition, and nuclear radiation detection, and they emerge as well-trained nuclear scientists who are capable of important contributions to our national needs. Providing a supportive professional experience for students and postdoctoral scholars in nuclear science is an ongoing, vital component of our program, and the participants enthusiastically take part in national and international scientific conferences and the activities of professional societies. Women continue to make major contributions to our research program; five of the last six doctoral graduates from our group are women. In addition, research at a small accelerator laboratory, such as ours, permits the mentoring of young scientists on a daily basis. For many years, the research facilities of our laboratory have been made available to students and faculty from undergraduate institutions, as well as scientists from other research universities, national laboratories, and nuclear-related industry. Research collaborations have been encouraged and developed. Our University of Kentucky colleagues and those from other institutions frequently take advantage of our laboratory facilities to obtain information that may be crucial for the design of experiments at larger facilities, e.g., TRIUMF, LANSCE, and JLAB, or in other areas of physics. Research performed in our laboratory has contributed to our national interests, such as homeland security, and will continue to do so. These applications are well represented by the activities of government and industrial partners who utilize our accelerator and research equipment. For example, collaborative studies with colleagues from industry have led to improved neutron-detection-based methods for the inspection of luggage for explosives and illegal drugs. Data obtained in our laboratory has been used to evaluate direct energy-storage devices, and our facilities have been utilized by a local elemental analysis company for a variety of applications. In many cases, the unique fast-neutron production and detection capabilities of UKAL are important considerations in the selection of our facility for this work.