Considering collective degrees of freedom in the β decay of odd nuclei

The β decay of around 30 odd nuclei was calculated within the dynamic collective model using expressions for the reduced matrix elements of the weak-interaction Hamiltonian for U-type and V-type β decay obtained earlier by the authors. All of the many-phonon states of the yrast band of an even-even core contributing to the formation of the excited states of nuclei were taken into account. For β transitions with an intensity of >1%, the calculated logft values differ from the experimental values by no more than 0.2.     

Phonon–particle coupling effects in odd–even mass differences of semi-magic nuclei

A method to evaluate the particle–phonon coupling (PC) corrections to the single-particle energies in semi-magic nuclei, based on a direct solving the Dyson equation with PC corrected mass operator, is used for finding the odd–even mass difference between 18 even Pb isotopes and their odd-proton neighbors. The Fayans energy density functional (EDF) DF3-a is used which gives rather high accuracy of the predictions for these mass differences already on the mean-field level, with the average deviation from the existing experimental data equal to 0.389 MeV. It is only a bit worse than the corresponding value of 0.333 MeV for the Skyrme EDF HFB-17, which belongs to a family of Skyrme EDFs with the highest overall accuracy in describing the nuclear masses. Account for the PC corrections induced by the low-laying phonons 2 ₁ ⁺ and 3 ₁ ^- significantly diminishes the deviation of the theory from the data till 0.218 MeV.     

Shape phase transition in the odd Sm nuclei: effective order parameter and odd–even effect

Some binding energy related quantities serving as effective order parameters have been used to analyze the shape phase transition in the odd Sm nuclei. It is found that the signals of phase transition in the odd Sm nuclei are greatly enhanced in contrast to the even Sm nuclei. A further analysis shows that the transitional behaviors related to pairing in the Sm nuclei can be well described by the mean field plus pairing interaction model, with a monotonic decrease in the pairing strength G.     

Phonon–particle coupling effects in odd–even double mass differences of magic nuclei

It has been proposed to use the formation of a magnetized plasma of laser-accelerated ions and electrons at the irradiation of the curved surface of the inner cavity of the target by a petawatt laser pulse to initiate a neutronless nuclear reaction of protons with boron nuclei. The possibility of an additional increase in the intensity of the reaction owing to the compression of the plasma at the irradiation of the outer surface of the target by a second terawatt laser pulse synchronized in time with the plasma-forming pulse has been discussed. The parameters of laser pulses and a target have been determined at which the ignition of a pB plasma occurs; i.e., the energy released in reactions is equal to the energy of the plasma.     

Phonon–particle coupling effects in odd–even double mass differences of semi-magic nuclei

A method is developed to consider the particle–phonon coupling (PC) effects in the calculation of the odd–even double mass differences (DMD) in semi-magic nuclei starting from the free NN potential. The PC correction δΣ^PC to the mass operator Σ is found in g _L ²-approximation, g _L being the vertex of creating the L-phonon. The tadpole term of the operator δΣ^PC is taken into account. The method is based on a direct, without any use of the perturbation theory, solution of the Dyson equation with the mass operator Σ(ε) = Σ₀ + δΣ^PC(ε) for finding the single-particle energies and Z-factors. In its turn, they are used as an input for finding different PC corrections to the DMD values. Results for a chain of even semi-magic nuclei ^200?206Pb show that the inclusion of the PC corrections makes agreement with the experimental data significantly better.     

A mini transmissionγ-ray Compton polarimeter and measurements of the sign of magnetic moments of radioactive nuclei

A mini transmission-ray Compton polarimeter was developed for the measurement of the sign of magnetic moments of radioactive nuclei with low-temperature nuclear orientation. The signs of the magnetic moments of the following isotopes were determined:¹⁹³Os [=+0.7297(16) _N];^191m Ir [=+6.20(9) _N];¹⁹²Ir [=+1.924(10) _N];¹⁹⁴Ir [=+0.39(1) _N];^195m Pt [=–0.605(15) _N].Dedicated to Prof. Dr. P. Kienle on the occasion of his 60th birthday     

Formation and ordering of local magnetic moments in Fe–Al alloys

The density functional theory is used to study the local magnetic moments in Fe–Al alloys depending on concentration (from 29 to 44 at% Al) and the Fe nearest environment. We have found three different solutions for the system: a spin-spiral wave (SSW) which has a minimum energy and two collinear states, a ferromagnetic one and a state with both positive and negative Fe magnetic moments (the Fe atoms with many neighboring Al atoms around them have negative magnetic moments, while the other Fe atoms—positive). Both the SSW and the negative Fe moments agree with the experiments. Magnetization curves taken from the literature are analyzed. The assumption of percolation character of the size distribution of magnetic clusters describes well the experimental superparamagnetic behavior above 150 K.     

The even–odd effect in the dependence of optical anisotropy on the number of protons in complexing agent ions of liquid-crystal coordination compounds of lanthanides

The values of optical anisotropy of two series of thermotropic nematic liquid crystalline complexes based on the ions Eu⁺³, Gd⁺³, Tb⁺³, and Dy⁺³ have been determined. Even–odd alternation of optical anisotropy with an increasing number of protons in ions of lanthanides has been observed. It is established that, in the considered series of lanthanidomesogens, optical anisotropy is more sensitive to changes in the ligand structure of complexes than to the variation of the complexing agent.     

Time dependence of hysteresis loop displacement in hard–soft magnetic systems

Time dependence of the hysteresis loop asymmetry observed in partially crystallized _{Co66Si16B12Fe4Mo2}${\mathrm{Co}}_{66}{\mathrm{Si}}_{16}{\mathrm{B}}_{12}{\mathrm{Fe}}_4{\mathrm{Mo}}_2$ is here analyzed at room temperature. The results are related to a magnetic aftereffect occurring in the hard crystallites embedded in the residual soft matrix. The coercive field is found to be constant with time, which is explained in terms of the dipolar interaction theory.     

Anomaly in the field dependence of the anisotropic magnetic susceptiblity of a single-grained α-Mn

A kink was observed near 20 kOe in the field dependence of the magnetization in a single-grained α-Mn without a magnetic hysteresis below the Neel temperature in an accurate magnetization measurement below 80 kOe. It was observed along [1 0 0], [1 1 0] and [1 1 1] crystallographic directions. The field dependence of the magnetization above 40 kOe extrapolates to positive finite magnetization at null field. The kink suggests a weak metamagnetism induced by the external magnetic field. A small but clear anisotropy was observed between the weak-field susceptibilities along [1 0 0] and [1 1 0]/[1 1 1] directions. A previously reported large susceptibility anomaly was not affirmed between 90 and 270 kOe.     

Isoscalar magnetic moments and the role of the δ-hole excitation

Expectation values of the total spinS of nucleons in nuclei are very quenched. This quenching is shown to be hardly explained by the mixture of-hole states. The quenching thus provides the best evidence for the role of non-central parts of the nucleon-nucleon interaction, especially the tensor interaction.     

Structure of negative parity yrast bands in odd mass <Superscript>125–131</Superscript>Ce nuclei

The negative parity yrast bands of neutron-deficient ^125–131Ce nuclei are studied by using the projected shell model approach. Energy levels, transition energies and B(M1)/B(E2) ratios are calculated and compared with the available experimental data. The calculations reproduce the band-head spins of negative parity yrast bands and indicate the multi-quasiparticle structure for these bands.     

Oscillatory thickness dependence of magnetic moments and interface-induced changes of the exchange coupling in Co/Cu and CoNi/Cu multilayers

We perform first-principles calculations for the three multilayer systems (100)-Co₁/Cu_n, NiCo₂Ni/Cu_n and Co₄Cu_n, and find from a comparison of the results for system 2 and 3 that amplitude and phase of the exchange coupling are sensitive to the magnetic-slab/nonmagnetic-spacer interface. Moreover, we observe that for the system 1 the averaged magnetic moment of the magnetic slab oscillates with the spacer thickness similarly as the exchange coupling.     

Relation between signature splitting in rotational bands of odd nuclei and the amplitude of the Ω=1/2 component

The relation between signature splitting in the spectra of rotational bands of odd nuclei and the structure of wave functions of these states is investigated. Rotational bands are considered both in axisymmetric nuclei and in nuclei that do not possess axial symmetry. A simple formula is obtained that makes it possible to extract the amplitude of the Ω=1/2 wave-function component from experimental data on energy spectra.     

Phonon–particle coupling effects in the single-particle energies of semi-magic nuclei

A method is presented to evaluate the particle–phonon coupling (PC) corrections to the single-particle energies in semi-magic nuclei. In such nuclei, always there is a collective low-lying 2⁺ phonon, and a strong mixture of single-particle and particle–phonon states often occurs. As in magic nuclei the so-called g _L ² approximation, where g _L is the vertex of the L-phonon creation, can be used for finding the PC correction δΣ^PC(ε) to the initial mass operator Σ₀. In addition to the usual pole diagram, the phonon “tadpole” diagram is also taken into account. In semi-magic nuclei, the perturbation theory in δΣ^PC(ε) with respect to Σ₀ is often invalid for finding the PC-corrected single-particle energies. Instead, the Dyson equation with the mass operator Σ(ε) = Σ₀ + δΣ^PC(ε) is solved directly, without any use of the perturbation theory. Results for a chain of semi-magic Pb isotopes are presented.