Energy levels of A = 21−44 nuclei (V)

Investigation of nuclear structure by resonance fluorescence scattering

Energy levels of light nuclei A = 18–19☆

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

Supplement to energy levels of a = 21-44 nuclei. (vii)

Nuclear resonance fluorescence experiments are reported to search for enhanced [ital M]1 scissors mode states in the deformed odd-mass nucleus [sup 163]Dy. A concentration of dipole strengths near 3 MeV excitation energy is found, which fits nicely into the systematics observed for [ital M]1 excitations in the neighboring even-even Dy isotopes. The observed strength distribution and the decay branching ratios are discussed in the context of the interacting boson-fermion model.

/pdf/first-observation-of-scissors-mode-states-in-an-odd-mass-1gzl4w63oa.pdf

First observation of scissors mode states in an odd-mass nucleus

Half-lives and \ensuremath{\alpha}-branching ratios for the members of the ground-state ``band'' in $^{212}\mathrm{Po}$ are deduced using an \ensuremath{\alpha}-cluster model. The \ensuremath{\alpha}-core potential is obtained from a double folding procedure and has integral values close to those obtained in elastic \ensuremath{\alpha} scattering. The preformation probability is found to be P=0.035. The long half-life of the (${18}^{+}$) isomer is explained by the prediction of the excitation energy of the ${16}^{+}$ state to lie above the (${18}^{+}$) isomer. The (${11}^{\mathrm{\ensuremath{-}}}$) and (${13}^{\mathrm{\ensuremath{-}}}$) at ${\mathit{E}}_{\mathit{x}}$=2411.3 and 2771.8 keV are tentatively assigned to the negative parity \ensuremath{\alpha}-cluster ``band.''

Alpha-cluster states of 212Po in a realistic potential model.

Determination of short lifetimes with ultra high resolution (n, γ) spectroscopy

The 112Cd laboratory: An extension. E0 strengths, multiphonon states and coupled vibrations

A substantially improved double flat crystal gamma ray spectrometer (GAMS4) has been put into operation as a joint NBS/ILL facility at the HFR, Grenoble. This facility has the capability of determining gamma ray wavelengths, in absolute units, with uncertainties on the order of 0.1 ppm in the energy range from 0.1 to approximately=5 MeV. This new facility incorporates a number of major improvements over the earlier double flat crystal spectrometer used to determine the n-p 2.2 MeV line with an error of 1 ppm (2 eV). The operation of the instrument and the nature of the improvements is discussed. Experimental results related to the direct determination of the binding energy of several light nuclei (for example D, 13C, 15N) are given. The implications of this work for the atomic mass scale and for the determination of fundamental constants is reviewed.

http://iopscience.iop.org/article/10.1088/0305-4616/14/S/017/pdf

High accuracy, absolute wavelength determination of capture gamma-ray energies for E≤5 MeV and the direct determination of binding energies in light nuclei

F. Hoyler

Papers

First observation of scissors mode states in an odd-mass nucleus

Alpha-cluster states of 212Po in a realistic potential model.

Determination of short lifetimes with ultra high resolution (n, γ) spectroscopy

The 112Cd laboratory: An extension. E0 strengths, multiphonon states and coupled vibrations

High accuracy, absolute wavelength determination of capture gamma-ray energies for E≤5 MeV and the direct determination of binding energies in light nuclei