Rotational-vibrational band structure in 155Sm

doi:10.1016/0375-9474(82)90058-6

Nuclear Physics A

Volume 376, Issue 2, 1 March 1982, Pages 149-182

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Abstract

The nuclear structure of ¹⁵⁵Sm has been studied via primary and secondary γ-rays and by internal conversion electrons following thermal neutron capture. Furthermore average resonance neutron capture spectra for various neutron energy ranges were recorded. A detailed level scheme with a complete set of levels with spin < $72$ has been well established up to 1400 keV excitation energy. The neutron binding energy has been determined to be 5807.2(3) keV. The scheme is interpreted in a basis of Coriolis and ΔN = 2 coupled Nilsson states and compared with the less deformed Sm isotopes. A possible additional band coupling via the octupole vibrational mode is discussed.

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Nuclear data sheets for A = 155
2005, Nuclear Data Sheets
This work represents an update of the previous evaluation of the nuclear data on the A = 155 nuclides (Nucl. Data Sheets 71 (1994) 709). The experimental data from reaction and decay studies leading to these nuclides have been reviewed. The elements included range from Ce (Z = 58) through Ta (Z = 73). These data are summarized and presented, together with the adopted level schemes and properties. In addition, data on the g. s. properties of those A = 159 nuclides whose α decays lead to final states in the A = 155 nuclides have been reconsidered.
Nuclear structure of 157Gd
2003, Nuclear Physics A
The energy levels of ¹⁵⁷Gd have been investigated using the (n, γ) and (n, n′γ) reactions. As a result of the analysis of the γ-ray spectra from 16 isolated neutron resonances, a level scheme with a complete set of levels with spins J=1/2, 3/2 has been established up to 1.86 MeV excitation energy. A part of the level scheme is interpreted in more detail on the basis of Coriolis and ΔN=2 coupled Nilsson configurations. Slightly different sets of shape parameters are deduced for negative- and positive-parity levels. A large excess of unassigned 1/2 and 3/2 levels evidently requires an explanation in terms of inclusion of new additional degrees of freedom.
Nuclear data sheets for A = 155
1994, Nuclear Data Sheets
Level structure of the odd-odd nucleus 156Eu
1991, Nuclear Physics, Section A
The reaction chain ¹⁵³Eu(n, γ)¹⁵⁴Eu(n, γ)¹⁵⁵Eu(n, γ)¹⁵⁶Eu was studied using ¹⁵³Eu targets. The γ-ray and internal conversion electron spectra were measured with high resolution spectrometers. Using several subsequent measurement series, as well as the radiation spectra from the reaction-decay chain ¹⁵⁴Sm(n, γ)¹⁵⁵Sm
¹⁵⁵Eu(n, γ)¹⁵⁶Eu, we assigned 95 transitions to ¹⁵⁶Eu, and 70 multipolarities were determined for them. 31 levels with spin values from 0 to 5 were found up to 515 keV. These levels are assigned to 13 rotational bands interpreted using proton orbits $p 52^{+} [413]↓, p 52^{−} [532]↑, p 32^{+} [411]↑$ and neutron orbits $n 52^{+} [642]↑, n 32^{−} [521]↑, n 52^{−} [523]↓, n 112^{−} [505]↑$ . Comparison with the decay of ¹⁵⁶Sm to ¹⁵⁶Eu indicates a 0.7% β-branch to the 1⁻ level at 266.95 keV, and log $ƒt = 7.1$ . The 434.230(2) keV energy is proposed for the level $448 ± 15 keV, 3^{−}, p 52^{+} [413]↓− n$ $112^{−} [505]↑$ , earlier known from the ¹⁵⁴Eu(t, p) measurements. Model calculations are in agreement with the Gallagher-Moszkowski rule for four doublets $Ω_{p} ±Ω_{n}$ . The calculated mixing amplitudes explain origin of some two-particle transitions. Comparatively intense E1 transitions between levels of bands with ΔK = 0 and opposite parities allow to propose existence of octupole deformation in ¹⁵⁶Eu which results in observation of parity doublets. It can be estimated that the ¹⁵⁶Eu level scheme is complete up to about 240 keV excitation energy for all spin values.
Nuclear structure of 163Dy studied with (n, γ), (n, n'γ), (d, p) and (d, t) reactions
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Neutron-capture gamma rays below 40 keV
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A review of neutron-capture gamma ray measurements below 40 keV is given and experimental methods are discussed. New experiments with a Si(Li) detector have been performed. Energies and absolute intensities of low energy (n, γ) transitions in ²⁸Al, ⁴⁰K, ⁵²V, ¹²⁸I, ¹³⁴Cs, ¹⁶⁰Tb, ¹⁶⁶Ho, ¹⁷⁰Tm, ¹⁷⁶Lu, ¹⁸²Ta, ¹⁹²Ir, ¹⁹⁸Au and ²³³Th are presented. These new results can serve calibration purposes and provide nuclear structure information.

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^☆: Research has been performed in part under contract DE-ACO2-76CH00016 with the US Department of Energy.

^∗: Present address: Naval Research Laboratory, Washington DC, USA.

^∗∗: Present address: National Research Council, Ottawa, Canada.

^∗∗∗: Present address : Physik Department, TU München, W.-Germany.

^††: Present address : Centre d'Etudes Nucléaires de Grenoble, CPN, Grenoble, France.

^†††: Present address : Los Alamos National Laboratory, Los Alamos, USA.

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Nuclear Physics A

Abstract

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Nuclear data sheets for A = 155

Nuclear structure of <sup>157</sup>Gd

Nuclear data sheets for A = 155

Level structure of the odd-odd nucleus <sup>156</sup>Eu

Nuclear structure of <sup>163</sup>Dy studied with (n, γ), (n, n'γ), (d, p) and (d, t) reactions

Neutron-capture gamma rays below 40 keV

Rotational-vibrational band structure in 155Sm☆

Abstract

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Rotational-vibrational band structure in ¹⁵⁵Sm☆