Beck B R, Becker J A, Beiersdorfer P, Brown G V, Moody K J, Wilhelmy J B, Porter F S, Kilbourne C A, Kelley R L
Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
Phys Rev Lett. 2007 Apr 6;98(14):142501. doi: 10.1103/PhysRevLett.98.142501. Epub 2007 Apr 5.
The energy splitting of the 229Th ground-state doublet is measured to be 7.6+/-0.5 eV, significantly greater than earlier measurements. Gamma rays produced following the alpha decay of 233U (105 muCi) were counted in the NASA/electron beam ion trap x-ray microcalorimeter spectrometer with an experimental energy resolution of 26 eV (FWHM). A difference technique was applied to the gamma-ray decay of the 71.82 keV level that populates both members of the doublet. A positive correction amounting to 0.6 eV was made for the unobserved interband decay of the 29.19 keV state (29.19-->0 keV).
测量得到229Th基态双重态的能量分裂为7.6±0.5电子伏特，显著大于早期测量结果。利用美国国家航空航天局/电子束离子阱X射线微量热计光谱仪对233U（105微居里）α衰变产生的γ射线进行计数，实验能量分辨率为26电子伏特（半高宽）。对填充双重态两个成员的71.82千电子伏特能级的γ射线衰变应用了一种差值技术。对29.19千电子伏特态（29.19→0千电子伏特）未观测到的带间衰变进行了0.6电子伏特的正修正。
