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

MRI：开发用于测量核结构和基本对称性的高精度激光系统

• 批准号: 1228489
• 负责人: Paul Mantica
• 金额: $ 22.3万
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1228489&HistoricalAwards=false
• 关键词: MRI; Development; Accuracy; Precision; Laser

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.

环形染料激光器将被添加到密歇根州立大学（MSU）国家超导回旋加速器实验室（NSCL）现有的光束冷却和激光光谱（BECOLA）设施的激光基础设施中。环形染料激光器将提供现有BECOLA Ti:Sapphire激光系统无法获得的光，其可见波长范围为550 nm至780 nm，线宽小于250 kHz。环形染料激光器发出的光也可以与现有的倍频器相结合，产生波长从275纳米到390纳米的深紫外到近紫外光。环形染料激光器的加入将极大地扩大BECOLA激光光谱和光泵浦所能接触到的元素和同位素的范围。升级后的BECOLA激光系统将提供一种手段，将关键元素的电荷半径和核矩测量扩展到核图中非常奇特的区域。在短寿命放射性核素Ni-78和Sn-100附近的原子核，目前还不能用于在线激光光谱研究，是专门针对的。Ni-78和Sn-100都具有闭壳质子和中子构型，这些原子核是完善当今核结构理论的重要基石。还将研究放射性Na-21和Mg-23衰变中的奇异耦合，以测试弱相互作用的基本原理。这些测量将需要高核偏振光束，这将通过新型环形染料激光器的圆偏振光光泵浦产生。非放射性（稳定）离子也可以从BECOLA的离线离子源每天提供，用于学生培训，系统改进和识别新的光学跃迁，以增加用激光作为稀有同位素光束探针的发现潜力。该项目涵盖原子物理、亚原子核物理、核化学和基础对称性等领域，为研究前沿科学的学生和博士后研究人员提供独特的教育体验。研究计划中实现的技术进步大大提高了核极化的幅度和保持时间，这可能有利于基础研究和成像应用。激光光泵浦方法与高偏振惰性气体在肺功能成像中的应用等前沿研究有很强的重叠。