Nuclear data sheets for A = 238

Fission and gamma-ray decay of the238U shape isomer

“…The possibility of unobserved transitions to other 1-and 2 + states in the first minimum of the double humped fission barrier in 238U has to be taken into account. Assuming that the reduced width of these E1 and E2 transitions are the same as for the observed E1 (1.878 MeV) and E2 (12,513 MeV) transition, we obtain an additional contribution of (80 + 30) gbarn for the possible decay to the six known 1-and 2 + states in 238U [18]. This yields a total cross section of (212 +-40) pbarn for the deexcitation of the shape isomeric state 2asu by gamma-back decay.…”

“…probability for the population of the first excited 2 + level in 238U by gamma-back decay. For the 2.513 MeV gamma transition e2+ = l. The 1.878 MeV gamma transition leads to the 1-level at 680.0 keV, which decays with a (65_+_+5)% probability to the 2 + state (e2, = 0.65_+0.05) [18]. TK = correction factor for the different deadtimes for the detection of a gamma ray and a delayed fission.…”

“…These transitions should populate mainly low-lying states in the first minimum of the double humped fission barrier. The transition energies and conversion coefficients of the succeeding transitions should be well known [18]. In the case of 2aSmu the 44.9 keV 2 + 40 + transition from the first excited rotational state to the ground state is highly converted (e=618), [18].…”

“…The transition energies and conversion coefficients of the succeeding transitions should be well known [18]. In the case of 2aSmu the 44.9 keV 2 + 40 + transition from the first excited rotational state to the ground state is highly converted (e=618), [18]. As there is a high probability for gamma transitions deexciting the shape isomer to populate either directly or indirectly the 2 + level at 44.9 keV in 238U, the measurement of coincidences between these gamma rays and conversion electrons is a very crucial and effective way to suppress delayed gamma rays from fissionproducts because of the strongly reduced probability for converted transitions of such energy to occur in nuclei of medium atomic number.…”

Pictures of quantum nuclear rotation beyond the correspondence principle

“…with a = 7.5 MeV, b = −0.004 MeV [18]. Our 'estimated' T rev , used for the figures (there is no exact revival at all), is then defined by (39) and (40) taken forĪ determined from the equation…”