Spectroscopy of low spin states in 157Dy: Search for evidence of enhanced octupole correlations

直接测量^{148}Dy中增强的八极集体性

Direct measurement of Enhanced octupole collectivity in 148Dy

通过测量^{148}Dy的$B(E3)$跃迁强度，发现其为$N=82$壳层最大值，直接证实了$Z=64$以外增强的八极集体性，并扩展了八极集体性的边界。

铀-238中八极集体性在相对论重离子流可观测量上的印记

Imprints of octupole collectivity in uranium-238 on relativistic heavy-ion flow observables

研究铀-238中八极集体性在相对论重离子流可观测量上的印记，通过先进流体动力学计算，证明对初始几何结构中八极诱导特征的定量敏感性，表明有适度八极集体性，为奇阶核集体性提供补充探测并约束夸克-胶子等离子体初始条件。

High-resolution $(p,t)$ study of low-spin states in $^{240}$Pu: Octupole excitations, $α$ clustering, and other structure features

A high-resolution $(p,t)$ experiment at $E_{p}$= 24 MeV was performed to populate low-spin states in the actinide nucleus ${}^{240}$Pu. The Q3D magnetic spectrograph of the Maier-Leibnitz Laboratory (MLL) in Munich (Germany) was used to identify the ejected tritons via $dE/E$ particle identification with its focal-plane detection system. Angular distributions were measured at nine different Q3D angles to assign spin and parity to the excited states based on a comparison with coupled-channels DWBA calculations. In total, 209 states have been excited in $^{240}$Pu up to an excitation energy of 3…

八极声子的价壳层二阶构建块

Seniority-two valence-shell building blocks of the octupole phonon

通过简化壳模型和谐振子波函数，研究双体激发多重态中$J^-$能级顺序，揭示$Δj=3, Δl=3$子壳层组合在粒子-粒子通道的能量增益偏好，并解释八极软核中3$^-_1$激发能较低的原因。

Octupole strength in the neutron-rich calcium isotopes

Low-lying excited states of the neutron-rich calcium isotopes $^{48-52}$Ca have been studied via $γ$-ray spectroscopy following inverse-kinematics proton scattering on a liquid hydrogen target using the GRETINA $γ$-ray tracking array. The energies and strengths of the octupole states in these isotopes are remarkably constant, indicating that these states are dominated by proton excitations.

Direct Evidence for Octupole Deformation in $^{146}$Ba and the Origin of Large $E1$ Moment Variations in Reflection-Asymmetric Nuclei

Despite the more than one order of magnitude difference between the measured dipole moments in $^{144}$Ba and $^{146}$Ba, the strength of the octupole correlations in $^{146}$Ba are found to be as strong as those in $^{144}$Ba with a similarly large value of $B(E3;3^- \rightarrow 0^+)$ determined as 48($^{+21}_{-29}$) W.u. The new results not only establish unambiguously the presence of a region of octupole deformation centered on these neutron-rich Ba isotopes, but also manifest the dependence of the electric dipole moments on the occupancy of different neutron orbitals in nuclei with enhance…

116Sn中八极关联的存在性

Existance of octupole correlation in 116Sn

本文利用INGA装置通过114Cd(α,2n)116Sn反应研究116Sn的负宇称态，新观测到三条γ跃迁及带间跃迁，B(E1)/B(E2)比值和增强的E1、E3跃迁速率证实了该核中存在八极关联。

Direct Evidence of Octupole Deformation in Neutron-Rich $^{144}$Ba

The neutron-rich nucleus $^{144}$Ba ($t_{1/2}$=11.5 s) is expected to exhibit some of the strongest octupole correlations among nuclei with mass numbers $A$ less than 200. Until now, indirect evidence for such strong correlations has been inferred from observations such as enhanced $E1$ transitions and interleaving positive- and negative-parity levels in the ground-state band. In this experiment, the octupole strength was measured directly by sub-barrier, multi-step Coulomb excitation of a post-accelerated 650-MeV $^{144}$Ba beam on a 1.0-mg/cm$^2$ $^{208}$Pb target. The measured value of the …

Lifetimes and moments measurements to investigate the structure of midheavy nuclei

Mid-heavy nuclei offer unique opportunities to study the collective and single-particle aspects of nuclear structure. This mass regime is a dynamic area where protons and neutrons generally occupy different orbitals, giving rise to complex structures with a wide variety of shapes, shape evolution and shape coexistence. To that end, measurements of nuclear lifetimes and electromagnetic moments ($μ$,$Q$) can be invaluable. Recent experimental activities of the NuSTRAP group in Athens have focused on $γ$-spectroscopy studies employing the RoSPHERE array in Magurele, Romania. In recent studies [1,…

通过低激发负宇称态寿命测量独立验证镭-224中的八极集体性

Independent Validation of Octupole Collectivity in radium-224 through lifetime measurements of low-lying negative-parity states

通过测量$^{224}$Ra低激发负宇称态寿命，独立验证了其八极集体性，并确认了强烈抑制的内禀偶极矩，为核结构模型提供了精确基准。

寻找CP破坏的新途径：227-Ac的Mössbauer光谱学

A new avenue in the search for CP violation: Moessbauer spectroscopy of 227-Ac

本研究提出利用227-Ac的27.4-keV E1跃迁开展Mössbauer光谱测量，以探测CP破坏核矩，并给出能量分辨率下限及四极分裂、核Zeeman效应中的预期特征。

直接证明$^{88}$Sr的$J^π = 1_{4742~\mathrm{keV}}^{-}$态的双声子结构

Direct demonstration of the two-phonon structure of the $J^π = 1_{4742~\mathrm{keV}}^{-}$ state of $^{88}$Sr

本研究通过$^{88}$Rb β衰变后的γ谱学测量$^{88}$Sr中4742 keV的$1^-$态衰变，依据相等的$B(E2)$强度直接证实其四极-八极耦合双声子结构。

Ac-231的原子核结构

Nuclear structure of Ac-231

用γ射线能谱研究了231 Ac的低能结构。用小型橙电子能谱仪测量转换电子，确定了28个跃迁的多极性。首次建立了~（231）Ra → ~（231）Ac的衰变图。高级延时β-γ-γ（t）法已用于测量五种浓度的半衰期。中快的B（E1）跃迁率表明，八极效应，虽然很弱，仍然存在于这个奇异的核。