37 research outputs found
Probing the nature of the conjectured low-spin wobbling bands in atomic nuclei
The precession of an atomic nucleus can be approximately described as wobbling motion, arising from the coupling of a rotation and a harmonic vibration. Recently, a number of wobbling bands were reported at low spin, which violate the wobbling approximation that can be valid only at high spin. In the present work, we explore the nature of the reported low-spin wobbling bands. Via a new experiment including both angular correlation and linear polarization measurements, we demonstrate that one such band in 187Au is generated by dominant single-particle excitation rather than by the excitation of a wobbling phonon. Assessing the experimental proofs and discussions to assign the reported low-spin wobbling bands, we further point out that the imperfect research paradigm used previously would lead to unreliable identification of low-spin wobbling bands
Fine structure in the α decay of 223U
Fine structure in the α decay of 223U was observed in the fusion-evaporation reaction 187Re(40Ar, p3n) by using fast digital pulse processing technique. Two α-decay branches of 223U feeding the ground state and 244 keV excited state of 219Th were identified by establishing the decay chain 223U →α1 219Th →α2 215Ra →α3 211Rn. The α-particle energy for the ground-state to ground-state transition of 223U was determined to be 8993(17) keV, 213 keV higher than the previous value, the half-life was updated to be 62−10+14 μs. Evolution of nuclear structure for N = 131 even-Z isotones from Po to U was discussed in the frameworks of nuclear mass and reduced α-decay width, a weakening octupole deformation in the ground state of 223U relative to its lighter isotones 219Ra and 221Th was suggested
Decay of the very neutron-deficient isotope Pm
The decay of Pm has been investigated by means of -ray
spectroscopy. The Pm nuclei were produced by fusion-evaporation
reaction of Cd(S,3p4n) at the beam energy of 170 MeV. A
helium-jet technique and a tape transport system were used to collect the
activities and transfer them to a detecting position for X and
rays measurement. Two rays of 185.0 and 220.0 keV were
unambiguously identified to follow the decay of Pm by
results of X- and - coincidence. A growth-decay
feature of the decay curve for 87.8 keV -ray of Nd
confirmed the production of Pm nuclei. The half-life of Pm
was measured to be 6.30.8 s. A partial decay scheme of Pm is
proposed on the basis of X- and - coincidence
data in this experiment and the known structure information deduced from
in-beam experiments of the daughter nucleus Nd
A new alpha-particle-emitting isotope
An isotope of the element 105 with mass number 259 has been
produced via the reaction Am(Ne, 4n)Db at MeV. The reaction products were transported and collected using the
helium-jet technique and the rotating wheel apparatus. The -decays
of the products and their daughter nuclides were detected by a set of Si(Au)
detectors arranged ingeniously. The and of the nuclide have been
unambiguously identified by the genetic relationship between the new
activity and the known nuclide Lr established by -recoiled
milking measurement. The new nuclide Db has a half-life of s and decays by alpha-particle emission of MeV.
Furthermore, the nuclide Db and its daughter Lr have also
been clearly observed using the same projectile-target combination. Their
half-lives and -particle energies determined in this work are in
agreement with previous known data, thus also proving the reliability of our
assignment of Db
New yrast excited states of the \mth{N=84} nucleus \chem{^{142}Ce} observed in deep inelastic reactions
Excited states of Ce, populated in deep inelastic reactions of Se projectiles bombarding La target, have been studied up to
medium spins using in-beam spectroscopy techniques. Three new
levels have been identified at 2625, 2995, 3834 keV, and assigned as 8
, 9 and 11, respectively. These new yrast states follow
closely the level systematics of the even mass isotones. Their
strctures have been discussed with the help of empirical shell model
calculations