31 research outputs found
Direct observation of long-lived isomers in Bi
Long-lived isomers in 212Bi have been studied following 238U projectile
fragmentation at 670 MeV per nucleon. The fragmentation products were injected
as highly charged ions into the GSI storage ring, giving access to masses and
half-lives. While the excitation energy of the first isomer of 212Bi was
confirmed, the second isomer was observed at 1478(30) keV, in contrast to the
previously accepted value of >1910 keV. It was also found to have an extended
Lorentz-corrected in-ring halflife >30 min, compared to 7.0(3) min for the
neutral atom. Both the energy and half-life differences can be understood as
being due a substantial, though previously unrecognised, internal decay branch
for neutral atoms. Earlier shell-model calculations are now found to give good
agreement with the isomer excitation energy. Furthermore, these and new
calculations predict the existence of states at slightly higher energy that
could facilitate isomer de-excitation studies.Comment: published in PRL 110, 12250
Reinvestigation of the excited states in the proton emitter Lu 151 : Particle-hole excitations across the N=Z=64 subshell
The excited states of the proton emitter Lu151 were reinvestigated in a recoil-decay tagging experiment at the Accelerator Laboratory of the University of Jyväskylä (JYFL). The level scheme built on the ground state of Lu151 was updated with five new γ-ray transitions. Large-scale shell model calculations were carried out in the model space consisting of the neutron and proton orbitals 0g7/2, 1d5/2, 1d3/2, 2s1/2, and 0h11/2 with the optimized monopole interaction in order to interpret the experimental level scheme of Lu151. It is found that the excitation energies of states above the 27/2- and 23/2+ isomeric levels in Lu151 can be sensitive to excitations from g7/2 and d5/2 to single-particle orbitals above N=Z=64
Spectroscopic factor and proton formation probability for the d3/2 proton emitter 151mLu
The quenching of the experimental spectroscopic factor for proton emission from the short-lived d3/2 isomeric state in 151mLu was a long-standing problem. In the present work, proton emission from this isomer has been reinvestigated in an experiment at the Accelerator Laboratory of the University of Jyväskylä. The proton-decay energy and half-life of this isomer were measured to be 1295(5) keV and 15.4(8) μs, respectively, in agreement with another recent study. These new experimental data can resolve the discrepancy in the spectroscopic factor calculated using the spherical WKB approximation. Using the R-matrix approach it is found that the proton formation probability indicates no significant hindrance for the proton decay of 151mLu