The spherical-to-deformed phase transition in cerium isotopes recently suggested to occur between... more The spherical-to-deformed phase transition in cerium isotopes recently suggested to occur between 146 Ce and 148 Ce has been examined in the framework of the macroscopic algebraic collective model and two microscopic approaches, namely Skyrme-Hartree-Fock + Bardeen-Cooper-Schrieffer (BCS) calculations and the symmetry conserving configuration mixing method with Gogny energy density functionals applied also to the neighboring nuclei along the cerium isotopic chain. Possible spectral signatures of the phase transition are discussed in more details. The microscopic calculations predict octupole softness manifested by rather flat potential energy curves as a function of the octupole deformation parameter β 3 for 146 Ce and 148 Ce and shape coexistence characterized by axially symmetric 0 + states, triaxial 2 + bands, and octupole deformation for the lowest 1 − states.
We reanalysed the role of superparamagnetic magnetite clusters observed in a pigeon’s upper beak ... more We reanalysed the role of superparamagnetic magnetite clusters observed in a pigeon’s upper beak to decide if this matter can be a component of some sort of pigeon magnetometer for Earth-orientation. We investigated the mutual interaction of the magnetite clusters induced by the geomagnetic field. The force sensitivity of the hypothetical magnetometer in a pigeon’s upper beak was estimated considering the previously presented threshold magnetic sensitivity of pigeons, measured in electrophysiological and behavioural investigations. The typical intercluster magnetic force seems to be 10 −19 N well above the threshold magnetic sensitivity. To strengthen our results, we measured the magnetic susceptibility of superparamagnetic magnetite using a vibrating sample magnetometer. Finally we performed theoretical kinematic analysis of the motion of magnetite clusters in cell plasma. The results indicate that magnetite clusters, constituted by superparamagnetic nanoparticles and observed in a...
Atmospheric activity concentration of 7 Be in the air was monitored during the period of one year... more Atmospheric activity concentration of 7 Be in the air was monitored during the period of one year from September 2015 to September 2016 at Ostrava, Czech Republic, with a two-day frequency that is shorter compared to a standard 7-day frequency of routine 7 Be measurements. Simultaneously, relevant meteorological data (temperature, rainfall amount, precipitation particle size and speed, tropopause height, and PM 10 concentrations) and the sunspot number were accumulated. Weighted linear regression analysis applied to the 7 Be atmospheric activity concentration, the measured meteorological explanatory variables and the sunspot number revealed temperature as the most statistically significant explanatory variable. The tree model proved temperature as the most important explanatory variable and predicted the threshold value separating low and high temperature behavior of 7 Be at about 13 • C (2-day average). A simple local two-layer (stratosphere and troposphere) atmospheric model was then applied to the data analysis. The model is able to fit the data for a larger accumulation period (6 days).
Delayed γ-ray and conversion-electron spectroscopy is performed on A = 152 fission fragments, at ... more Delayed γ-ray and conversion-electron spectroscopy is performed on A = 152 fission fragments, at the Lohengrin spectrometer of the Institut Laue-Langevin, providing a new decay scheme for 152 Pr. The quasiparticle phonon model, combined with the particle-rotor model, which allows octupole correlations and Coriolis mixing to be taken into account, is applied to analyze its low-energy structure. The main configurations are found to be (π 3/2[422] ⊗ ν5/2[642])1 + for the isomer and (π 3/2[541] ⊗ ν3/2[521])3 + for the ground state.
Algebraic collective model calculations for even-even xenon isotopes 128,130Xe have been performe... more Algebraic collective model calculations for even-even xenon isotopes 128,130Xe have been performed to describe collective properties of these two nuclei, considered to be candidates for an E(5) transition from spherical to γ-soft, O(6)-like nuclei. The shape transitional point and the E(5) symmetry are characterised by large fluctuations in the triaxiality parameter γ reflected by a very flat potential in the γ direction resulting in two symmetric prolate and oblate minima in the potential energy curves. This has been studied using the Skyrme-Hartree-Fock calculations with different parametrisations of the Skyrme interaction.
Acta Physica Polonica B Proceedings Supplement, 2019
The research in the field of superheavy elements started in the sixties of the last century trigg... more The research in the field of superheavy elements started in the sixties of the last century triggered by the prediction of a region of enhanced nuclear stability at the next closed proton and neutron shells beyond 208 Pb. Adam Sobiczewski was one of the first predicting proton and neutron numbers for these shell closures at Z = 114 and N = 184, respectively. In the following decades, extensive efforts led to the synthesis of isotopes of elements up to Z = 118 in a fruitful competition of the leading laboratories in the field with FLNR/JINR in Dubna, Russia, LBNL in Berkeley, USA, GSI in Darmstadt, Germany and most recently RIKEN in Wako (Tokyo), Japan. Beyond the synthesis of new elements and isotopes, substantial activities were dedicated to nuclear structure studies, laying the basis for the understanding of this exotic nuclear matter. In-beam spectroscopy as well as decay spectroscopy after separation (DSAS) together with the support by theory have the potential to lay the basis for a successful approach of the so-called island of stability, the firm grounds, the creation of which had been started by pioneers like Adam Sobiczewski in the beginning of the second half of last century. In this paper, some of the achievements mainly of DSAS will be presented, with an emphasis on the guidance by theory and the work of Adam Sobiczewski, to whom this paper is dedicated.
Algebraic collective model (ACM) calculations for the even-even selenium isotopes 86,88 Se have b... more Algebraic collective model (ACM) calculations for the even-even selenium isotopes 86,88 Se have been performed to describe collective properties of these two transitional nuclei with only two and four valence neutrons, respectively. From the perspective of the ACM the nuclei turn out to be only weakly deformed, described by a very γ-soft potential. This is confirmed by Skyrme and Gogny energy density functional calculations. Additionally, the fully microscopic symmetry conserving configuration mixing method with the Gogny interaction has been applied to the study of these isotopes. The results show the transitional character of 86 Se and the relevant role of the triaxial degree of freedom in the structure of these nuclei.
The symmetry properties of reflection-asymmetric nuclei are discussed in the framework of the Har... more The symmetry properties of reflection-asymmetric nuclei are discussed in the framework of the Hartree-Fock-Bogoliubov method. A comparison of reflection-symmetric and reflection-asymmetric approaches is made.
The signature inversion is explained within the microscopic model as a competition between rotati... more The signature inversion is explained within the microscopic model as a competition between rotational alignment and the residual n-p interaction of odd particles coupled to core vibrations. .
The level structure of 185 W has been studied using the prompt and delayed gamma-gamma coincidenc... more The level structure of 185 W has been studied using the prompt and delayed gamma-gamma coincidences from thermal neutron capture in 184 W accompanied with the one-nucleon transfer reactions (d, p) and (d, t) with polarized beams. From these data and those of previous studies a total of 183 levels has been established for energies below 3 MeV. Many of these states have been grouped into rotational bands built on 28 intrinsic states of quasiparticle and quasiparticle-plus-phonon character. Although the DWBA analysis permitted definite spin-parity assignments for most of states a large number of particle transitions have 'anomalous' angular and asymmetry shapes with respect to the DWBA which indicate an influence of strong mixing between particle and hole states. The extra exchange of phonons and the significance of configurational N = ±2 mixing across the Fermi surface lead to a fine structure in the fragmentation of most single-particle strengths and at the same time has the effect of breakdown of the individual properties of Nilsson states. The accumulated l = 1 (d, p) sum is about a factor two smaller than the equivalent (d, t) strength. Thus, the previously observed loss of the (d, p) strength in the W nuclei with A = 184, 185 is presumably because of their redistribution amongst particle-and hole-type states. The observed states below 2 MeV are compared with predictions of the quasiparticle-phonon nuclear model.
A total of 74 levels from 21 multiplets of the nuclei 206 Tl , 208 Tl , 208 Bi , and 210 Bi have ... more A total of 74 levels from 21 multiplets of the nuclei 206 Tl , 208 Tl , 208 Bi , and 210 Bi have been calculated with a Generalized Intermediate Coupling Model, with Gaussian and delta potentials with and without an interaction between octupole phonon and odd nucleons. The goodness of fit is compared with that of other calculations of Molinari et al. and Schiffer and True. It is quite clear that the calculations work well in spite of the fact that they are required to fit simultaneously odd-odd nuclei with neutron and proton shells which differ by principal harmonic oscillator quantum numbers Δ N = +1.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2013
Compact deuterium-tritium neutron generators emit fast neutrons (14.2 MeV) that have to be therma... more Compact deuterium-tritium neutron generators emit fast neutrons (14.2 MeV) that have to be thermalized for neutron activation analysis experiments. To maximize thermal neutron flux and minimize epithermal and fast neutron fluxes across the output surface of the neutron generator facility, Monte Carlo calculations (MCNP5; Los Alamos National Laboratory) for different moderator types and widths and collimator and reflector designs have been performed. A thin lead layer close to the neutron generator as neutron multiplier followed by polyethylene moderator and surrounded by a massive lead and nickel collimator and reflector was obtained as the optimum setup.
Journal of Radioanalytical and Nuclear Chemistry, 2014
Weighted multiple regression analysis was used to study the relationship between 7 Be wet deposit... more Weighted multiple regression analysis was used to study the relationship between 7 Be wet deposition and selected characteristics of rainfall events and concentrations of pollutants and 7 Be in air for the first time. We sampled 24 individual rain events (September 2013-March 2014) and simultaneously collected relevant meteorological data. 7 Be content in the collected water was determined by gamma spectrometry. A dominant negative correlation was observed between 7 Be volume activity and rainfall amount. The influence of PM 10 and PM 2.5 concentrations and weekly values of 7 Be volume activity in aerosols on 7 Be volume activity in rainwater was found to be statistically insignificant.
Capture Gamma-Ray Spectroscopy and Related Topics, 2003
Abstract: Tissue samples (skin of mice, normal and tumor, skin of a woman, normal and tumor) were... more Abstract: Tissue samples (skin of mice, normal and tumor, skin of a woman, normal and tumor) were irradiated by protons from the Munich tandem accelerator. The samples were analysed using Raman spectroscopy at the Institute of Chemical Technology in Prague by ...
Journal of Scientific Conference Proceedings, 2010
Abstract: In the paper two new experimental setups at the Institute of Physics of the V??B???Tech... more Abstract: In the paper two new experimental setups at the Institute of Physics of the V??B???Technical University of Ostrava for measurements of solid and liquid samples using the excitation surface plasmon resonance (SPR) method are described. Preliminary results of ...
Brownian motion of magnetic nanoparticles in a low-density gas can induce random voltage pulses i... more Brownian motion of magnetic nanoparticles in a low-density gas can induce random voltage pulses in a microscopic electric circuit containing a high-number-of-turns coil and a classical diode rectifier. The amplitude of the voltage pulses is estimated and the rectification condition examined. We have shown that in our toy-model nanogenerator where the motion of the magnetic nanoparticle is restricted to one-dimensional rotation around its vertical axis and the nanoparticle is inserted into a very low number-density gas (3 × 10 16 m-3) one can generate voltage pulses of the amplitude of 3 × 10-8 V in one coil turn. The total number of 10 6 turns is then necessary to reach the rectifying region.
ABSTRACT Collective structures in 180Ta built on the meta-stable Kπ=9− high-spin isomer were inve... more ABSTRACT Collective structures in 180Ta built on the meta-stable Kπ=9− high-spin isomer were investigated using two types of Coulomb excitation experiments. In-beam studies identify γ-vibrational bands with typical bandhead E2 excitation strengths of 6 Weisskopf units (W.u.). Coulomb activation of the 180Ta ground state was measured with 36S and 64Ni projectiles using thin targets. The excitation functions and the 180Ta recoil angular distributions favor a Kπ=7+ octupole vibration at Ex=1155(40) keV as intermediate state in the population of the ground state.
The spherical-to-deformed phase transition in cerium isotopes recently suggested to occur between... more The spherical-to-deformed phase transition in cerium isotopes recently suggested to occur between 146 Ce and 148 Ce has been examined in the framework of the macroscopic algebraic collective model and two microscopic approaches, namely Skyrme-Hartree-Fock + Bardeen-Cooper-Schrieffer (BCS) calculations and the symmetry conserving configuration mixing method with Gogny energy density functionals applied also to the neighboring nuclei along the cerium isotopic chain. Possible spectral signatures of the phase transition are discussed in more details. The microscopic calculations predict octupole softness manifested by rather flat potential energy curves as a function of the octupole deformation parameter β 3 for 146 Ce and 148 Ce and shape coexistence characterized by axially symmetric 0 + states, triaxial 2 + bands, and octupole deformation for the lowest 1 − states.
We reanalysed the role of superparamagnetic magnetite clusters observed in a pigeon’s upper beak ... more We reanalysed the role of superparamagnetic magnetite clusters observed in a pigeon’s upper beak to decide if this matter can be a component of some sort of pigeon magnetometer for Earth-orientation. We investigated the mutual interaction of the magnetite clusters induced by the geomagnetic field. The force sensitivity of the hypothetical magnetometer in a pigeon’s upper beak was estimated considering the previously presented threshold magnetic sensitivity of pigeons, measured in electrophysiological and behavioural investigations. The typical intercluster magnetic force seems to be 10 −19 N well above the threshold magnetic sensitivity. To strengthen our results, we measured the magnetic susceptibility of superparamagnetic magnetite using a vibrating sample magnetometer. Finally we performed theoretical kinematic analysis of the motion of magnetite clusters in cell plasma. The results indicate that magnetite clusters, constituted by superparamagnetic nanoparticles and observed in a...
Atmospheric activity concentration of 7 Be in the air was monitored during the period of one year... more Atmospheric activity concentration of 7 Be in the air was monitored during the period of one year from September 2015 to September 2016 at Ostrava, Czech Republic, with a two-day frequency that is shorter compared to a standard 7-day frequency of routine 7 Be measurements. Simultaneously, relevant meteorological data (temperature, rainfall amount, precipitation particle size and speed, tropopause height, and PM 10 concentrations) and the sunspot number were accumulated. Weighted linear regression analysis applied to the 7 Be atmospheric activity concentration, the measured meteorological explanatory variables and the sunspot number revealed temperature as the most statistically significant explanatory variable. The tree model proved temperature as the most important explanatory variable and predicted the threshold value separating low and high temperature behavior of 7 Be at about 13 • C (2-day average). A simple local two-layer (stratosphere and troposphere) atmospheric model was then applied to the data analysis. The model is able to fit the data for a larger accumulation period (6 days).
Delayed γ-ray and conversion-electron spectroscopy is performed on A = 152 fission fragments, at ... more Delayed γ-ray and conversion-electron spectroscopy is performed on A = 152 fission fragments, at the Lohengrin spectrometer of the Institut Laue-Langevin, providing a new decay scheme for 152 Pr. The quasiparticle phonon model, combined with the particle-rotor model, which allows octupole correlations and Coriolis mixing to be taken into account, is applied to analyze its low-energy structure. The main configurations are found to be (π 3/2[422] ⊗ ν5/2[642])1 + for the isomer and (π 3/2[541] ⊗ ν3/2[521])3 + for the ground state.
Algebraic collective model calculations for even-even xenon isotopes 128,130Xe have been performe... more Algebraic collective model calculations for even-even xenon isotopes 128,130Xe have been performed to describe collective properties of these two nuclei, considered to be candidates for an E(5) transition from spherical to γ-soft, O(6)-like nuclei. The shape transitional point and the E(5) symmetry are characterised by large fluctuations in the triaxiality parameter γ reflected by a very flat potential in the γ direction resulting in two symmetric prolate and oblate minima in the potential energy curves. This has been studied using the Skyrme-Hartree-Fock calculations with different parametrisations of the Skyrme interaction.
Acta Physica Polonica B Proceedings Supplement, 2019
The research in the field of superheavy elements started in the sixties of the last century trigg... more The research in the field of superheavy elements started in the sixties of the last century triggered by the prediction of a region of enhanced nuclear stability at the next closed proton and neutron shells beyond 208 Pb. Adam Sobiczewski was one of the first predicting proton and neutron numbers for these shell closures at Z = 114 and N = 184, respectively. In the following decades, extensive efforts led to the synthesis of isotopes of elements up to Z = 118 in a fruitful competition of the leading laboratories in the field with FLNR/JINR in Dubna, Russia, LBNL in Berkeley, USA, GSI in Darmstadt, Germany and most recently RIKEN in Wako (Tokyo), Japan. Beyond the synthesis of new elements and isotopes, substantial activities were dedicated to nuclear structure studies, laying the basis for the understanding of this exotic nuclear matter. In-beam spectroscopy as well as decay spectroscopy after separation (DSAS) together with the support by theory have the potential to lay the basis for a successful approach of the so-called island of stability, the firm grounds, the creation of which had been started by pioneers like Adam Sobiczewski in the beginning of the second half of last century. In this paper, some of the achievements mainly of DSAS will be presented, with an emphasis on the guidance by theory and the work of Adam Sobiczewski, to whom this paper is dedicated.
Algebraic collective model (ACM) calculations for the even-even selenium isotopes 86,88 Se have b... more Algebraic collective model (ACM) calculations for the even-even selenium isotopes 86,88 Se have been performed to describe collective properties of these two transitional nuclei with only two and four valence neutrons, respectively. From the perspective of the ACM the nuclei turn out to be only weakly deformed, described by a very γ-soft potential. This is confirmed by Skyrme and Gogny energy density functional calculations. Additionally, the fully microscopic symmetry conserving configuration mixing method with the Gogny interaction has been applied to the study of these isotopes. The results show the transitional character of 86 Se and the relevant role of the triaxial degree of freedom in the structure of these nuclei.
The symmetry properties of reflection-asymmetric nuclei are discussed in the framework of the Har... more The symmetry properties of reflection-asymmetric nuclei are discussed in the framework of the Hartree-Fock-Bogoliubov method. A comparison of reflection-symmetric and reflection-asymmetric approaches is made.
The signature inversion is explained within the microscopic model as a competition between rotati... more The signature inversion is explained within the microscopic model as a competition between rotational alignment and the residual n-p interaction of odd particles coupled to core vibrations. .
The level structure of 185 W has been studied using the prompt and delayed gamma-gamma coincidenc... more The level structure of 185 W has been studied using the prompt and delayed gamma-gamma coincidences from thermal neutron capture in 184 W accompanied with the one-nucleon transfer reactions (d, p) and (d, t) with polarized beams. From these data and those of previous studies a total of 183 levels has been established for energies below 3 MeV. Many of these states have been grouped into rotational bands built on 28 intrinsic states of quasiparticle and quasiparticle-plus-phonon character. Although the DWBA analysis permitted definite spin-parity assignments for most of states a large number of particle transitions have 'anomalous' angular and asymmetry shapes with respect to the DWBA which indicate an influence of strong mixing between particle and hole states. The extra exchange of phonons and the significance of configurational N = ±2 mixing across the Fermi surface lead to a fine structure in the fragmentation of most single-particle strengths and at the same time has the effect of breakdown of the individual properties of Nilsson states. The accumulated l = 1 (d, p) sum is about a factor two smaller than the equivalent (d, t) strength. Thus, the previously observed loss of the (d, p) strength in the W nuclei with A = 184, 185 is presumably because of their redistribution amongst particle-and hole-type states. The observed states below 2 MeV are compared with predictions of the quasiparticle-phonon nuclear model.
A total of 74 levels from 21 multiplets of the nuclei 206 Tl , 208 Tl , 208 Bi , and 210 Bi have ... more A total of 74 levels from 21 multiplets of the nuclei 206 Tl , 208 Tl , 208 Bi , and 210 Bi have been calculated with a Generalized Intermediate Coupling Model, with Gaussian and delta potentials with and without an interaction between octupole phonon and odd nucleons. The goodness of fit is compared with that of other calculations of Molinari et al. and Schiffer and True. It is quite clear that the calculations work well in spite of the fact that they are required to fit simultaneously odd-odd nuclei with neutron and proton shells which differ by principal harmonic oscillator quantum numbers Δ N = +1.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2013
Compact deuterium-tritium neutron generators emit fast neutrons (14.2 MeV) that have to be therma... more Compact deuterium-tritium neutron generators emit fast neutrons (14.2 MeV) that have to be thermalized for neutron activation analysis experiments. To maximize thermal neutron flux and minimize epithermal and fast neutron fluxes across the output surface of the neutron generator facility, Monte Carlo calculations (MCNP5; Los Alamos National Laboratory) for different moderator types and widths and collimator and reflector designs have been performed. A thin lead layer close to the neutron generator as neutron multiplier followed by polyethylene moderator and surrounded by a massive lead and nickel collimator and reflector was obtained as the optimum setup.
Journal of Radioanalytical and Nuclear Chemistry, 2014
Weighted multiple regression analysis was used to study the relationship between 7 Be wet deposit... more Weighted multiple regression analysis was used to study the relationship between 7 Be wet deposition and selected characteristics of rainfall events and concentrations of pollutants and 7 Be in air for the first time. We sampled 24 individual rain events (September 2013-March 2014) and simultaneously collected relevant meteorological data. 7 Be content in the collected water was determined by gamma spectrometry. A dominant negative correlation was observed between 7 Be volume activity and rainfall amount. The influence of PM 10 and PM 2.5 concentrations and weekly values of 7 Be volume activity in aerosols on 7 Be volume activity in rainwater was found to be statistically insignificant.
Capture Gamma-Ray Spectroscopy and Related Topics, 2003
Abstract: Tissue samples (skin of mice, normal and tumor, skin of a woman, normal and tumor) were... more Abstract: Tissue samples (skin of mice, normal and tumor, skin of a woman, normal and tumor) were irradiated by protons from the Munich tandem accelerator. The samples were analysed using Raman spectroscopy at the Institute of Chemical Technology in Prague by ...
Journal of Scientific Conference Proceedings, 2010
Abstract: In the paper two new experimental setups at the Institute of Physics of the V??B???Tech... more Abstract: In the paper two new experimental setups at the Institute of Physics of the V??B???Technical University of Ostrava for measurements of solid and liquid samples using the excitation surface plasmon resonance (SPR) method are described. Preliminary results of ...
Brownian motion of magnetic nanoparticles in a low-density gas can induce random voltage pulses i... more Brownian motion of magnetic nanoparticles in a low-density gas can induce random voltage pulses in a microscopic electric circuit containing a high-number-of-turns coil and a classical diode rectifier. The amplitude of the voltage pulses is estimated and the rectification condition examined. We have shown that in our toy-model nanogenerator where the motion of the magnetic nanoparticle is restricted to one-dimensional rotation around its vertical axis and the nanoparticle is inserted into a very low number-density gas (3 × 10 16 m-3) one can generate voltage pulses of the amplitude of 3 × 10-8 V in one coil turn. The total number of 10 6 turns is then necessary to reach the rectifying region.
ABSTRACT Collective structures in 180Ta built on the meta-stable Kπ=9− high-spin isomer were inve... more ABSTRACT Collective structures in 180Ta built on the meta-stable Kπ=9− high-spin isomer were investigated using two types of Coulomb excitation experiments. In-beam studies identify γ-vibrational bands with typical bandhead E2 excitation strengths of 6 Weisskopf units (W.u.). Coulomb activation of the 180Ta ground state was measured with 36S and 64Ni projectiles using thin targets. The excitation functions and the 180Ta recoil angular distributions favor a Kπ=7+ octupole vibration at Ex=1155(40) keV as intermediate state in the population of the ground state.
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