On the charge distribution of calcium nuclei

The mean square charge radii and the quadrupole moments of Ca nuclei are discussed in the light of theoretical predictions. The very peculiar dependence of the charge radii on the mass number between double magic⁴⁰Ca and double magic⁴⁸Ca can be ascribed to changes of the nuclear deformation, whereas the volume of the nuclear charge remains constant for all the Ca isotopes. Furthermore, correlations between nuclear charge radii and binding energies are discussed.     

Beta decay and hyperfine interactions

Experimental searches for the second-class currents and the soft pion effects in the nuclear weak axial currents are discussed. Also discussed are the hyperfine interactions of light interstitial impurities in ferromagnetic Fe and Ni, as well as in fcc and bcc non-magnetic metals. For these spin-ray correlation experiments, it is emphasized that the technical developments and improvements of the nuclear spin control by NMR and the production of polarization in the short-lived nuclear states are vital necessities.     

Surface physics with nuclear probes

A series of typical experiments using nuclear moments as microscopic probes for hyperfine fields on surfaces are discussed: Mössbauer spectroscopy, perturbed angular correlation studies, nuclear magnetic resonance, nuclear spin relaxation due to spin-lattice relaxation, and low-dimensional diffusion. Experiments are selected which deal mainly with well-characterized surfaces. Out of a wealth of data, particularly those that contribute to currently discussed topics in surface science are selected.Supported partly by the Bundesministerium für Forschung und Technologie (contract 06 MR 853 I) and the Deutsche Forschungsgemeinschaft (contract Fi 311-1 and Fi 311-1)     

Improvement of the algorithm for the analysis of Level schemes in the GTOL code

The algorithm of the GTOL code used for constructing nuclear level schemes by the measured γ spectra is discussed, and the difficulties arising in the work with complex nuclear level schemes are pointed out. The ways to improve the algorithm are shown, and the NEWGTOL code allowing large arrays of nuclear data to be properly handled is proposed.     

T-violation neutron experiment and polarized3He

An experimental scheme of the spin detailed balance in polarized neutron transmission through a polarized nuclear target is discussed for the T-violation test. The value of the spin detailed balance is estimated by using the data of the scattering amplitudes. The nuclear polarizations of proton,³He and¹³⁹La are discussed for the T-violation experiment.     

The structure of He and the neutron electric form factor from polarization observables

As there are no free neutron targets one has to resort to the nuclear targets deuterium or helium. In order to reduce nuclear effects blurring the information on nuclear form factors the technique of double polarization experiments had been developed. Recent experiments at MAMI measuring the electric form factor of the neutron are discussed. In addition, other single and double nucleon knockout experiments are described which support the buildup of a consistent interpretation of nuclear structure in ³He.     

On-line nuclear orientation of odd-odd120I

The use of Low Temperature Nuclear Orientation (LTNO) in nuclear structure studies is discussed. LTNO has been employed, together with γ-γ and e-γ spectroscopy, to study the nuclear structure of¹²⁰Te following the beta decay of¹²⁰ I ^g . The strengths and limitations of LTNO as a probe of nuclear structure are discussed with particular reference to this experiment.     

γ-Ray (and electron) induced annealing of nuclear tracks in polymeric detectors

Energy loss profiles for secondary electrons and γ-rays are discussed and the interactions of γ-rays with the activated species within the core of a nuclear track investigated. Based on an electron-hole trapping mechanism experimental values for the activation energies of annealing for nuclear tracks in the range of 0.26 to 0.5 eV have been obtained. These compare favourably with theoretical expectations. The consequences of variations in the detection sensitivities of such detectors are discussed.     

New directions in low temperature nuclear orientation

The basis of the low temperature nuclear orientation technique is summarized. The present limitations on accessible temperatures and the orders of magnitude of hyperfine interactions in the metallic systems currently studied are discussed briefly. The broad applicability to many elements and the high sensitivity of this singles counting method are emphasized. Specific recent developments are discussed in more detail. The use of a dilution refrigerator to cool to ≈ 10mK nuclei of isotopes far from stability ‘on-line’, after production in an accelerator and electromagnetic selection, is a major extension of the method. The minimum half-life is now limited by the nuclear spinlattice relaxation time, typically of order 10–100 s at 10 mK. Aspects of these experiments are considered and recent results given for Cs and I isotopes. Secondly, the extension of the related technique of nuclear magnetic resonance or oriented nuclei (NMR/ON) to antiferromagnetic insulators is described. A new cooling mechanism involving nuclear-magnon coupling gives access to much lower temperatures than previously reached in these systems. Recent precision work on MnCl₂, 4H₂O is discussed, along with its possible extension to nuclei of lanthanide elements. Finally, the use of nuclear orientation to study ordering below 10 mK of enhanced nuclear moment systems is briefly surveyed, with HoVO₄ as the test case. NMR/ON experiments at high pressure are proposed.     

Shadowing effects in nuclear parton distributions for small values ofx

The shadowing corrections to gluon and quark distributions in nuclei in the region of small values ofx are discussed. They are related to parton distributions in a pomeron which are in principle measurable in hard diffractive processes on the nucleon target. Multiple scattering corrections to shadowing are considered in a model dependent way. The perturbative QCD evolution of shadowing is also taken into account. Various possibilities of the partonic content of a pomeron are considered. It is shown in particular that the conventional parametrizations of parton distributions in a pomeron which are based on the assumption that it consists mostly of gluons imply substantial nuclear shadowing in gluon distributions in heavy nuclei. Possible phenomenological implications of shadowing corrections in nuclear parton distributions for various semi-hard processes with nuclear targets are briefly discussed.     

Electronic properties of metallic small particles

The electronic properties of very small metallic particles are reviewed. The emphasis is placed on the experimental work done by the author's group using nuclear magnetic resonance. The anomalies in the properties such as the spin susceptibility and the nuclear spin lattice relaxation arising from the discreteness of the orbital energies are discussed. For superconducting particles, the fluctuation of the order parameter and the critical magnetic field are also discussed.     

Nuclear structure studies on halo nuclei by direct reactions with radioactive beams

The investigation of direct reactions with exotic beams in inverse kinematics gives access to a wide field of nuclear structure studies in the region far off stability. The basic concept and the methods involved are briefly discussed. The present contribution will focus on the investigation of light neutron-rich halo nuclei. Such nuclei reveal a new type of nuclear structure, namely an extended neutron distribution surrounding a nuclear core. An overview on this phenomenon, and on the various methods which gave first evidence and qualitative confirmation of our present picture of halo nuclei, is given. To obtain more quantitative information on the radial shape of halo nuclei, elastic proton scattering on neutron-rich light nuclei at intermediate energies was recently investigated for the first time. This method is demonstrated to be an effective means for studying the nuclear matter distributions of such nuclei. The results on the nuclear matter radii of ⁶He and ⁸He, the deduced nuclear matter density distributions, and the significance of the data on the halo structure is discussed. The present data allow also a sensitive test of theoretical model calculations on the structure of neutron-rich helium isotopes. A few examples are presented. The investigation of few-nucleon transfer reactions in inverse kinematics may provide new and complementary information on nuclear structure, as well as astrophysical questions. The physics motivation and the experimental concept for such experiments, to be performed due to momentum matching reasons at low incident energies around 5–20 MeV/u at the new generation low energy radioactive beam facilities SPIRAL, PIAFE, etc., is briefly discussed.     

Nuclear resonant scattering of synchrotron radiation by multilayer structures

Multilayer structures form a particular class of samples employed in nuclear resonant scattering of synchrotron radiation. Their specific properties lead to unusual energy and time characteristics of nuclear resonant scattering, which differ much from those of single crystals. The analysis of these distinctions is presented. Several approaches to achieve pure nuclear reflections with multilayers are discussed. Finally, we review the studies of multilayer structures with nuclear resonant scattering of synchrotron radiation.

     

Nuclear matter in the skyrme model

The applicability of the Skyrme model to the analysis of nuclear matter is discussed. Constraints on an ansatz that describes a cubic skyrmion crystal are presented. Properties of this ansatz are studied numerically. Results are used to discuss nuclear matter in the large-N limit and at N = 3.     

Applications of progenitor sum rules in nuclear theory

The energy-weighted sum rules, obtained by taking matrix elements of double commutators with the nuclear Hamiltonian of appropriately defined densities, are didactically reviewed.Following a catalogue of applications such sum rules have found in theoretical nuclear physics, the progenitor sum rules (PSR's) are derived using standard commutator relations for second-quantized nucleon field operators. This leads to the extension of PSR's to coupled Fermi-Bose systems, and in particular, to a simple model of interacting mesons and nucleons. The effects of interactions are also discussed from the point of view of (static) exchange potentials. The relation of the dipole sum rule to nuclear photoabsorption is reviewed briefly.The application of PSR's to the calculation of longitudinal inelastic form factors, and the use of the “doorway hypothesis” is discussed in detail, together with the semiclassical collective-oscillation interpretation of these results proposed by Bertsch. Suzuki's very interesting applications of PSR to the evaluation of collective mass parameters, coupling constants, and polarization functions of the Bohr-Mottelson self-consistent mean-field theory are also given a detailed treatment. Certain miscellaneous applications of PSR to calculation of Coulombic isospin mixing, to energy shifts in isospin multiplets, and to induced moments and effective charges are collected and discussed in a unified manner. The review concludes with a discussion of the qualitative character of the nuclear photoabsorption strength below the meson production threshold, especially with regard to the question of to what extent the (γ, NN) reaction is sensitive to pair correlations in the nuclear ground state.     

Non-equilibrium nuclear abundances in superdense matter

1. The equation of state and nuclear composition are calculated for cold matter below neutron-drip density (～4×10¹¹ g/cm³) using recent nuclear data. 2. Nuclear transmutations of hot and dense matter taking care of the freezing of nuclear reactions are discussed for three types of temperature and density changes.     

Nuclear clustering aspects in astrophysics

Atomic nuclear clusters play a crucial role in nucleosynthesis in the universe, especially in the main sequence of heavy element synthesis. Cluster aspects in nucleosynthesis are briefly discussed based on a Cluster-Nucleosynthesis Diagram proposed here. Two recent topics on critical α-induced thermonuclear reactions are reviewed; the first one is the¹²C(α, γ)¹⁶O reaction for the He burning stage and the other one is the⁶ Li(α, n) ¹¹B reaction for the big bang nucleosynthesis. A new field of nuclear astrophysics using radioactive nuclear beams is also discussed.     

On the detection of nuclear spin waves by inelastic neutron scattering

The possibility of measuring nuclear spin waves (NSW) by inelastic neutron scattering is discussed. The differential cross section and scattered state polarization for the scattering of thermal neutrons from systems described by the Suhl-Nakamura Hamiltonian are developed in the Van Hove correlation function formalism; the relevant correlation functions for the Suhl-Nakamura system are computed. The implications of these calculations for the feasibility of detecting nuclear spin wave modes in neutron scattering experiments are discussed.     

重离子碰撞中的核温度

介绍了基于不同近似下的核温度的测量方法。不同测量方法给出的核温度不尽相同,这是因为它们使用的基本假设不一样。讨论了原子核系统的特殊性,这些特殊性使得核温度的提取特别困难。重点比较了动力学近似的几种温度计:使用经典Maxwell-Boltzmann 近似的,和使用量子Fermi-Dirac近似的。使用氦锂温度计对照考虑费米子属性后的斜率温度计和涨落温度计,发现考虑费米属性后提取的核温度更接近于热力学温度。仍需更多的工作,从核体系的孤立性、有限性和费米子属性等方面来研究核系统热力学温度的提取方法。Nuclear thermometers based on different approaches are reviewed. Due to the different basic assumptions of these methods, the nuclear temperatures extracted by different thermometer approaches are not consistent. Moreover,several problems which make the extraction of the nuclear temperatures even more difficult are discussed. The nuclear thermometers based on different kinetic approaches are compared. The nuclear temperatures extracted by methodsbased on quantum (Fermi-Dirac) kinetic approaches are compared to the double ratio temperatures THe; Li. Perspectives for future investigations of the thermal temperature are given.     

Neutron-induced reaction rates for the <Emphasis Type="Italic">r</Emphasis>-process

Neutron-induced reaction rates for the formation of heavy and superheavy nuclei in the astrophysical r-process are presented. Neutron-induced reactions, including fission and neutron capture, at astrophysical temperatures are treated within the framework of the statistical model and calculated for targets with the atomic number 84 < Z < 118, using different mass and fission barrier predictions. The dependence of heavy element yields from nuclear explosions on the target nuclei, nuclear reactions, and nuclear models is discussed.