The proposed research uses photon scattering and meson production to investigate the properties of the nucleon and nucleon resonances using polarized beams and targets. The experimental program is located at the High Intensity Gamma Source (HIGS) facility at the Duke Free Electron Laser Laboratory laboratory at Duke University, Jefferson Laboratory (JLab) in Newport News, VA and the National Institute for Standards and Techonology (NIST) in Gaithersburg, MD.
The HIGS facility opens a new window to the study of nucleon structure through elastic scattering of gamma-rays from both polarized and unpolarized nucleon and nuclear targets. This program will measure quantities that chacterize the response of the nucleon to the fluctuating electric and magnetic fields of the gamma-rays. This data will allow for precision tests of effective field theories, numerical calculations of the strong interaction as well as calculations and predictions of the standard model of particle physics. JMU is working with HIGS collaborators to build an active polarized proton target ideal for photon scattering experiments at low energies.
Although approved experiments at JLab using a polarized butanol target now under development will constrain fits to meson photoproduction, these experiments alone are insufficient. A collaboration has been assembled to measure beam-target asymmetries for five meson production channels simultaneously with polarized neutrons in the Strongly Polarized HD Ice (SPHICE) target using the CEBAF Large Acceptance Spectrometer (CLAS). This will provide the first (over-)determination of a pseudoscalar meson photo-production amplitude and will be free of the ambiguities that have plagued this field for decades. This experiment, E06-101, was reviewed in August 2006, was approved with an ``A'' rating and alloted the entire beam-time request.
Although the frozen spin HD target, SPHICE, is ideal for use in secondary beams, to use the target in a primary beam either the depolarizing effects of beam must be demonstrated to be small or new methods of operation must be found. The JMU group will, with collaborators from UVA, investigate the possibility of operating a dynamically polarized HD target. Target irradiation will be done at NIST using the Medical-Industrial Radiation Facility on high purity HD distilled at JMU. A dynamically polarized HD target with a high polarization would represent a significant advance in polarized target technology.
JMU undergraduate students will be involved in both on- and -off campus activities. The on-campus activities will include distillation of HD for SPHICE targets, polarizable scintillator target material fabrication and NaI detector assembly and testing, and for the more senior students, data analysis. These activities foster connections among the various research groups in the department, form the basis for the continued development of a new nuclear physics lab at JMU and allow the expansion of new outreach initiatives. The off-campus work will introduce the students to ``large'' physics done at state-of-the-art facilities and expose them to the experts in photonuclear physics that are attracted to these facilities. The College of Science and Mathematics at JMU currently has four NSF REU programs funded (Materials, Chemistry, Biology and Mathematics). These programs cooperatively produce a vibrant summer research community spanning the college. The program outlined here will bring off-campus experiences back to enrich the experience of not only the more junior students in this group but also those in the other REU programs. Research and teaching at JMU are recognized as two facets of the same process. This integration of research and education continues to be one of the hallmarks of the highly rated undergraduate experience at JMU.
