Fundamental Research in Nuclear Physics

Fundamental Research in Nuclear Physics Fundamental Research in Nuclear Physics This proposal requests NSF support for the renewal of the NSF grant No. PHY-0969654. The request will support the activities of the Arizona State University (ASU) group consisting of the PI, three graduate students and two undergraduate students, and will continue the consistently constant level of effort implemented during the original grant. The graduate students have recently passed their Ph.D. qualifying exams and have been deeply involved in experiments addressing fundamental issues of nuclear physics through state-of-the-art experimental techniques: the measurement of the parity-violating asymmetry in the capture of polarized neutrons by protons to determine the strength of the hadronic weak interaction; the measurement of electron and positron elastic scattering from hydrogen to determine the contribution of multiple-photon exchange in elastic lepton-nucleon scattering and address the present puzzle of the proton form factor ratio; and the reactor experiments with ultra-cold neutrons as part of a search for the neutron electric dipole moment. The undergraduate students get research experience at ASU in a detector laboratory and in supporting the on-going experiments. The scientific merit of the proposed program is the advancement of nuclear physics through the design, construction, and execution of state-of-the-art experiments. The on-going experiment using cold neutrons on a liquid hydrogen target uniquely addresses studies of the weak interaction among quarks and can settle the question of the pion contribution in the weak interaction between nucleons. After the construction of a novel spectrometer the following cold neutron measurements of the parameters governing the free neutron beta decay can have an important impact on our understanding of both nuclear physics and astrophysics. The proposed experiment with ultra-cold neutrons is uniquely designed to search for a non-zero electric dipole moment of the neutron, whose possible existence is of fundamental interest and would significantly challenge the theoretical extensions of the Standard Model. Most of our understanding on the structure of the proton and atomic nuclei is based upon lepton scattering analyzed in terms of the single photon approximation. As such, the on-going experiment measuring the elastic scattering from hydrogen using simultaneously positrons and electrons is essential to definitively verify the contribution of multiple photon exchange. The new initiative to look for evidence of dark forces at low energy is a unique type of electron scattering experiment with the potential to answer fundamental questions about the origin of dark matter. The broader impacts of this research are the training of graduate students and postdoctoral researchers, and the education of undergraduate students. The proposed activities produce three new scientists at the Ph.D. level, give research experience to various undergraduate students and provide them with guidance towards a graduate career in nuclear physics. The activities continue to produce partnerships within the field to develop new detector technologies. They also contribute to the ascent of a large state university as a premier research institution and to new university initiatives like proton therapy research. The advancement of the careers of women and ethnic minorities is an integral part of this process. Furthermore, the demand for state-of-the-art equipment utilizes the ASU research support services and the technical workforce of the society at large. Fundamental Research in Nuclear Physics Student Lauren Ice will be finishing up the analysis of the OLYMPUS experiment, which measured elastic electron and positron scattering from the proton. The analysis will be used to extract the possible two-photon contribution to elastic lepton-proton scattering. The motivation is to address the discrepancy on the ratio of the electric to magnetic proton form factor coming from Rosenbluth and polarization techniques. Student Adam Dipert will finish geometric phase measurements of polarized 3He as a way to address one of main systematics in the nEDM experiment, which seeks an upper limit of the neutron electric dipole moment. The results of the geometric phase 3He experiment will constitute the core of his Ph.D. thesis.