Nuclear magnetic moment of the first excited state (I = 2+) of 238U

The 238U Moessbauer effect of UO2 has been investigated in the temperature range from 5.4 K to 280 K. Nuclear Zeeman splitting of the 238U nucleus in antiferromagnetic UO2 at 5.4 K is 59.1 ± 3.9 mm s-1 and corresponds to the value of 252.3 ± 0.5 T obtained by the 235U pulsed NMR technique. The nuclear magnetic moment of the first excited state (I = 2+) of 238U has been determined to be 0.254 ± 0.015 μN. The conversion factor of 4.27 ± 0.28 T/mm s-1 enables us to determine the hyperfine magnetic field at the 238U nucleus using 238U Moessbauer spectroscopy. The temperature dependence of the recoil-free fraction of the 238U Moessbauer effect in UO2 has been discussed. (author)