MRI: Development of a High Accuracy, High Precision Laser System for Measurements of Nuclear Structure and Fundamental Symmetries

Michigan State University, East Lansing MI

Investigators

Abstract

A ring-dye laser will be added to the laser infrastructure of the existing BEam COoling and LAser spectroscopy (BECOLA) facility at National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU). The ring-dye laser will provide light that cannot be obtained from the existing BECOLA Ti:Sapphire laser system over the visible wavelength range from 550 nm to 780 nm, with a line width of less than 250 kHz. The light from the ring-dye laser can also be combined with the existing frequency doubler to produce deep to near ultra-violet light in the wavelength range from 275 nm to 390 nm. The addition of the ring-dye laser will greatly expand the reach of elements and isotopes accessible to laser spectroscopy and optical pumping with BECOLA. The upgraded BECOLA laser system will provide a means to extend charge radii and nuclear moments measurements of key elements to extremely exotic areas in the nuclear chart. Nuclei in the vicinity of the short-lived radionuclides Ni-78 and Sn-100, which are not accessible for on-line laser spectroscopy studies at present, are specifically targeted. Both Ni-78 and Sn-100 have closed-shell proton and neutron configurations, and such nuclei serve as important cornerstones for refining present-day nuclear structure theories. The study of exotic couplings in the beta decays of radioactive Na-21 and Mg-23, to test the fundamental principles underlying weak interactions, will also be pursued. These measurements will require highly nuclear-polarized beams, that will be produced via optical pumping with circularly-polarized light from the new ring-dye laser. Non-radioactive (stable) ions can be also provided on a daily basis from the off-line ion source of BECOLA for student training, system improvements, and identifying new optical transitions to increase the discovery potential with lasers as a probe of rare isotope beams. The research activities proposed within the scope of this project span the fields of atomic physics, sub-atomic nuclear physics, nuclear chemistry, and fundamental symmetries, providing a unique educational experience for students and post-doctoral research associates at the forefront of the cutting-edge science. Technical advances realized in research plan that greatly enhance both the magnitude and retention times for nuclear polarization may benefit both basic research and imaging applications. The laser optical pumping methods have strong overlap with, e.g., the cutting-edge research on the application of highly-polarized noble gases for lung function imaging.