The experimental and theoretical evidence for intrinsic reflection-asymmetric shapes in nuclei is reviewed. The theoretical methods discussed cover a wide spectrum, from mean-field theory and its extensions to algebraic and cluster approaches. The experimental data for nuclear ground states and at low and high spin, cited as evidence for reflection asymmetry, are collected and categorized. The extensive data on electric dipole transition moments and their theoretical interpretation are surveyed, along with available data on electric octupole moments. The evidence for reflection-asymmetric molecular states in light nuclei is summarized. The application of reflection-asymmetric theories to descriptions of the fission barrier, bimodal fission, superdeformation, and hyperdeformations is reviewed, and some other perspectives in the wider context of nuclear physics are also given. [S0034-6861(96)00102-X]

Intrinsic reflection asymmetry in atomic nuclei

Investigation of nuclear structure by resonance fluorescence scattering

Experimental studies of the Pygmy Dipole Resonance

The nucleus is one of the most multifaceted many-body systems in the Universe. It exhibits a multitude of responses depending on the way one ''probes'' it. With increasing technical advancements of beams at the various accelerators and of detection systems the nucleus has, over and over again, surprised us by expressing always new ways of ''organized'' structures and layers of complexity. Nuclear magnetism is one of those fascinating faces of the atomic nucleus discussed in the present review. We shall not just limit ourselves to presenting the by now large data set that has been obtained in the past two decades using various probes, electromagnetic and hadronic alike and that presents ample evidence for a low-lying orbital scissors mode around 3 MeV, albeit fragmented over an energy interval of the order of 1.5 MeV, and higher-lying spin-flip strength in the energy region 5-9 MeV in deformed nuclei nor to the presently discovered evidence for low-lying proton-neutron isovector quadrupole excitations in spherical nuclei. To the contrary, the experimental evidence is put in the perspectives of understanding the atomic nucleus and its various structures of well-organized modes of motion and thus enlarges the discussion to more general fermion and bosonic many-body systems.

/pdf/magnetic-dipole-excitations-in-nuclei-elementary-modes-of-1lz9bk3at0.pdf

Magnetic dipole excitations in nuclei: Elementary modes of nucleonic motion

Nuclear Data Sheets for A=132

Photoexcitation of dipole modes in 160,162,164Dy

High resolution photon scattering experiments on various Nd-, Gd-, Dy-, Er- and Yb-isotopes yielded new information about the energy and absolute ΔK=0 groundstate transition strengths ofJ=1 levels with excitation energies between 1.5 and 4 MeV. The lowest of theseJ
π=1− states are suggested to be the bandheads of aK
π=0
− octupole vibrational band, whereas the origin of the higher lying states is unknown.

A survey ofΔK=0 dipole transitions from low lyingJ=1 states in rare earth nuclei

Observation of low-lying collective dipole transitions in the rare-earth nuclei 172,174,176Yb☆

Nuclear resonance fluorescence experiments using unpolarised as well as off-axis linearly polarised bremsstrahlung represent an outstanding tool to determine in a completely model independent way transition probabilities, multipole orders and parities of electromagnetic transitions to bound states in nuclei. A new polarised bremsstrahlung facility has been constructed at the 15 MeV linac in Gent. The experimental arrangement is discussed and first results are presented.

Polarised bremsstrahlung nuclear resonance fluorescence set-up at the 15 MeV linac in Gent

http://crunch.ikp.physik.tu-darmstadt.de/~ponomare/papers.dir/PLB-335-113.pdf

S. Lindenstruth

Papers

Photoexcitation of dipole modes in 160,162,164Dy

A survey ofΔK=0 dipole transitions from low lyingJ=1 states in rare earth nuclei

Observation of low-lying collective dipole transitions in the rare-earth nuclei 172,174,176Yb☆

Polarised bremsstrahlung nuclear resonance fluorescence set-up at the 15 MeV linac in Gent

Observation of a 1− two phonon 2+ ⊗ 3− excitation in 116Sn and 124Sn