MRI-Consortium: Development of a Neutron Detector Array by Undergraduate Research Students for Studies of Exotic Nuclei.

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Studies of exotic nuclei (those with a large excess of neutrons) are a top priority to address a number of outstanding nuclear physics questions. These include measurements to explore changes of the nuclear structure in nuclei far from stability and reaction rates to infer (gamma,n) rates for astrophysical applications. The MoNA Collaboration has been successful at measuring a number of neutron- unbound ground states and excited states of exotic nuclei, but such experiments have been restricted to cases where the decay energy associated with a resonant state was relatively low. With this project the remaining unbound nuclei as well as many unknown higher-lying unbound states in light neutron-rich nuclei (Z9) will be accessible. The MoNA Collaboration will expand on its past success and measure one- and two-neutron coincidence experiments following knock-out reactions with the new device. The group will also be able to pursue structure questions in those same nuclei via Coulomb dissociation measurements. The Large-area multi-Institutional Scintillator Array (LISA) will consist of 128 plastic scintillator bars (2 m by 10 cm by 10 cm). LISA will determine neutron energy through time-of-flight and the interaction point along the bar will be based on the time difference between the photomultiplier tubes at each end. When combined with the existing Modular Neutron Array (MoNA) and Sweeper instruments, the proposed array will facilitate exciting and important physics measurements with rare isotope beams at the National Superconducting Cyclotron Laboratory. In addition, since this collaborative proposal is entirely based at Primarily Undergraduate Institutions (PUIs), the grant will have a broad impact. Undergraduate researchers and under-represented groups will benefit from the actual construction, testing and commissioning of the array, as well as participation in future cutting-edge research. Finally, this work will have a long-term impact for the future Facility for Rare Isotope Beams (FRIB) since the proposed detector would be a Day One device there, the undergraduates involved in the proposed project can be part of the workforce at FRIB, and future undergraduates will have access to this new facility.The Division of Physics and the Directorate for Education and Human Resources have participated in the funding of this award.