Alignment processes and shape variations in 184Pt

Carpenter, M. P.; Bingham, C. R.; Courtney, L.H.; Janzen, V. P.; Larabee, A. J.; Liu, Z.-M.; Riedinger, L. L.; Schmitz, W.; Bengtsson, R.; Bengtsson, T.; Nazarewicz, W.; Zhang, J.-Y.; Johansson, J. K.; Popescu, D.; Waddington, J. C.; Baktash, C.; Halbert, M.L.; Johnson, Noah R.; Lee, I.Y.; Schutz, Y.; Nyberg, J.; Johnson, A.; Wyss, R.; Dubuc, J.; Kajrys, G.; Monaro, S.; Pilotte, S.; Honkanen, K.; Sarantites, D. G.; Haenni, D.R.

doi:10.1016/0375-9474(90)90346-n

Cited by 62 publications

(8 citation statements)

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“…Occurrence of triaxiality at low spins has been established in this mass region by observation of chiral band pairs in several nuclei [13][14][15] and suggested by large-scale, mean-field calculations (see, for example, Refs. [16][17][18]). Also, earlier studies of the coupling of an odd number of particles to a rotor had revealed substantial deviations from an axial shape [19,20].To populate the levels of interest in 187 Au, a 19 F beam was used with an enriched 174 Yb target (13 mg/cm 2 -thick foil with a 33 mg/cm 2 208 Pb backing) at the ATLAS facility of the Argonne National Laboratory.…”

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Longitudinal Wobbling Motion in Au187

et al. 2020

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The rare phenomenon of nuclear wobbling motion has been investigated for the nucleus 187 Au. A longitudinal wobbling-bands pair has been identified and clearly distinguished from the associated signature-partner band on the basis of angular distribution measurements. Theoretical calculations in the framework of the Particle Rotor Model (PRM) are found to agree well with the experimental observations. This is the first experimental evidence for longitudinal wobbling bands where the expected signature partner band has also been identified, and establishes this exotic collective mode as a general phenomenon over the nuclear chart.Wobbling is a collective mode that may appear when the moments of inertia of all three principal axes of the nuclear density distribution are unequal. The mode is well known in classical mechanics and its occurrence is a clear signal for a triaxial nuclear shape. For a given angular momentum, uniform rotation about the axis with the largest moment of inertia corresponds to minimal energy. At a somewhat larger energy, this axis precesses (wobbles) about the space-fixed angular momentum axis. In a quantal system such as the nucleus (or a molecule), the mode manifests itself in the appearance of rotational bands that correspond to successive excitations of wobbling phonons, n ω , and alternating signature α = α 0 + n ω , which determines the spin sequence I = α + even number. Adjacent wobbling bands n ω+1 and n ω are connected by collectively-enhanced ∆I = 1 transitions of predominantly E2 character, which are generated by the wobbling motion of the entire charged body. This is in contrast with the signature-partner bands, which represent another type of excitation involving a partial dealignment of the odd particle with respect to its preferred axis; for those, the connecting ∆I = 1 transitions are of predominantly M1 character, with very little, if any, E2 admixtures.Although predicted quite sometime ago [1], this exotic nuclear motion has been observed only rarely in experiments so far, and the list of nuclei exhibiting it is quite short: 105 Pd [2], 135 Pr [3, 4] (and, possibly, 133 La [5]), 161 Lu [6], 163 Lu [7, 8], 165 Lu [9], 167 Lu [10] and 167 Ta [11]-a total of only 7(8) nuclei across the entire nuclear chart.All the aforementioned nuclei have an odd proton occu-pying a high-j orbital, which modifies the wobbling mode. Frauendorf and Dönau [12] classified this coupled mode as "longitudinal wobbling" (LW) and "transverse wobbling" (TW) when, respectively, the odd particle aligns its angular momentum along the medium axis (the axis with the largest moment of inertia), or along one of the perpendicular axes. The wobbling energy, E wobb [see Eq.(1) below], increases with increasing angular momentum for LW while it decreases for TW [12]. In all of the cases mentioned above (except, possibly, 133 La[5]), the wobbling bands have been identified as corresponding to TW because E wobb decreases with increasing angular momentum. We report on the observation of bands structures corresponding to...

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Longitudinal Wobbling Motion in Au187

et al. 2020

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“…For the 798-keV and 956-keV transitions the fitted values are σ/I = 0.32 (5) and σ/I = 0.30 (6), respectively. A value of σ/I ≈ 0.3 is common for heavyion fusion-evaporation reactions [26,[29][30][31]. The σ/I parameter determines the anisotropy of the angular distri- bution depopulating the I π = 11 2 − isomer, and has an impact on the amplitude of the R(t) functions described in the following subsection.…”

Section: A Angular Distributionsmentioning

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Perturbed angular distributions with LaBr$_3$ detectors: the $g$ factor of the first ${10^+}$ state in $^{110}$Cd revisited

Gray,

Stuchbery,

Reed

et al. 2017

Preprint

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The Time Differential Perturbed Angular Distribution technique with LaBr3 detectors has been applied to the I π = 11 2 − isomeric state (Ex = 846 keV, τ = 107 ns) in 107 Cd, which was populated and recoil-implanted into a gadolinium host following the 98 Mo( 12 C, 3n) 107 Cd reaction. The static hyperfine field strength of Cd recoil implanted into gadolinium was thus measured, together with the fraction of nuclei implanted into field-free sites, under similar conditions as pertained for a previous implantation perturbed angular distribution g-factor measurement on the I π = 10 + state in 110 Cd. The 110 Cd g(10 + ) value was thereby re-evaluated, bringing it into agreement with the value expected for a seniority-two νh11 /2 configuration.

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“…In a very systematic study of the alignment process in a number of isotopes in this region [24], on the contrary, it was discussed that an i 13/2 quasineutron alignment could be responsible for the crossing in all three cases, N = 104, 106, and 108, with the variation in crossing frequency being caused by shape changes. More recently the h 9/2 band in 187 Ir was observed up to spin (45/2 − ) [22], showing a band crossing at the same frequency as the one observed in 185 Ir.…”

Section: A Backbending In the Rotation-aligned H 9/2 Bandmentioning

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New high-spin isomer and quasiparticle-vibration coupling inIr187

et al. 2010

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The high-spin structure of the Z = 77 nucleus 187 Ir has been studied using the fusion-evaporation reaction 186 W( 7 Li,6n) at a beam energy of 59 MeV. The excitation scheme of this nucleus has been extended by more than 110 new states, including extensions of all previously established rotational bands. The band crossing region of the h 9/2 negative-parity yrast band has been revised and new intrinsic high-K states have been identified. In particular, a 29/2 − isomeric state [T 1/2 = 1.8(5)µs] at an excitation energy of 2487 keV has been observed for the first time, and on top of it, a rich level scheme reaching up to spin (59/2 − ) and excitation energies around 7 MeV has been established.

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Alignment processes and shape variations in 184Pt

Cited by 62 publications

References 28 publications

Longitudinal Wobbling Motion in Au187

Longitudinal Wobbling Motion in Au187

Perturbed angular distributions with LaBr$_3$ detectors: the $g$ factor of the first ${10^+}$ state in $^{110}$Cd revisited

New high-spin isomer and quasiparticle-vibration coupling inIr187

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