It is shown that the rotating mean field of triaxial nuclei can break the chiral symmetry. Two ne... more It is shown that the rotating mean field of triaxial nuclei can break the chiral symmetry. Two nearly degenerate ∆I = 1 rotational bands originate from the left-handed and righthanded solution.
The high-spin structure of 205 Rn has been investigated for the first time following the 170 Er(4... more The high-spin structure of 205 Rn has been investigated for the first time following the 170 Er(40 Ar,5n) and 197 Au(14 N,6n) reactions at beam energies of 183 MeV and 90-110 MeV, respectively, using the Jurosphere and YRAST Ball arrays. Two new cascades have been identified which dominate the high-spin decay. One of these, consisting of ten stretched M 1 transitions with unobserved E2 crossover transitions, is interpreted as a shears structure based on the i 13/2 Ϫ1 i 13/2 2 ͑or i 13/2 Ϫ1 h 9/2 i 13/2 ͒ configuration. ͓S0556-2813͑99͒50506-2͔
The yrast states of transitional nuclei are described as quadrupole waves running over the nuclea... more The yrast states of transitional nuclei are described as quadrupole waves running over the nuclear surface, which we call tidal waves. In contrast to a rotor, which generates angular momentum by increasing the angular velocity at approximately constant deformation, a tidal wave generates angular momentum by increasing the deformation at approximately constant angular velocity. The properties of the tidal waves are calculated by means of the cranking model in a microscopic way. The calculated energies and E2 transition probabilities of the yrast states in the transitional nuclides with Z= 44, 46, 48 and N = 56, 58, ..., 66 reproduce the experiment in detail. The nonlinear response of the nucleonic orbitals results in a strong coupling between shape and single particle degrees of freedom.
The cranked relativistic Hartree+Bogoliubov theory has been applied for a systematic study of the... more The cranked relativistic Hartree+Bogoliubov theory has been applied for a systematic study of the nuclei around 254 No, the heaviest elements for which detailed spectroscopic data are available. The deformation, rotational response, pairing correlations, quasi-particle and other properties of these nuclei have been studied with different parametrizations for the effective mean-field Lagrangian. Pairing correlations are taken into account by a finite range two-body force of Gogny type. While the deformation properties are well reproduced, the calculations reveal some deficiencies of the effective forces both in the particle-hole and particle-particle channels. For the first time, the quasi-particle spectra of odd deformed nuclei have been calculated in a fully self-consistent way within the framework of the relativistic mean field (RMF) theory. The energies of the spherical subshells, from which active deformed states of these nuclei emerge, are described with an accuracy better than 0.5 MeV for most of the subshells with the NL1 and NL3 parametrizations. However, for a few subshells the discrepancies reach 0.7-1.0 MeV. In very heavy systems, where the level density is high, this level of accuracy is not sufficient for reliable predictions of the location of relatively small deformed shell gaps. The calculated moments of inertia reveal only small sensitivity to the RMF parametrization and, thus, to differences in the single-particle structure. However, in contrast to lighter systems, it is necessary to decrease the strength of the D1S Gogny force in the pairing channel in order to reproduce the moments of inertia.
High spin states in A ~ 110 neutron-rich 106Mo, 110Ru and 112Ru nuclei have been reinvestigated b... more High spin states in A ~ 110 neutron-rich 106Mo, 110Ru and 112Ru nuclei have been reinvestigated by measuring the prompt gamma-rays from the spontaneous fission of 252Cf. Two similar sets of bands are observed to high spins in each of three nuclei. Through analyzing of characters of the band structures, the chiral doublet bands are suggested in 106Mo, 110Ru and
A systematic study of the doublet bands observed in odd-odd mass ∼ 100 is performed using the mic... more A systematic study of the doublet bands observed in odd-odd mass ∼ 100 is performed using the microscopic triaxial projected shell model approach. This mass region has depicted some novel features which are not observed in other mass regions, for instance, it has been observed that two chiral bands cross diabatically in 106 Ag. It is demonstrated that this unique feature is due to crossing of the two 2-quasiparticle configurations having different intrinsic structures. Further, we provide a complete set of transition probabilities for all the six-isotopes studied in this work and it is shown that the predicted transitions are in good agreement with the available experimental data.
The quantum physics of light is a most fascinating field. Here I present a very personal viewpoin... more The quantum physics of light is a most fascinating field. Here I present a very personal viewpoint, focusing on my own path to quantum entanglement and then on to applications. I have been fascinated by quantum physics ever since I heard about it for the first time in school. The theory struck me immediately for two reasons: (1) its immense mathematical beauty, and (2) the unparalleled precision to which its predictions have been verified again and again. Particularly fascinating for me were the predictions of quantum mechanics for individual particles, individual quantum systems. Surprisingly, the experimental realization of many of these fundamental phenomena has led to novel ideas for applications. Starting from my early experiments with neutrons, I later became interested in quantum entanglement, initially focusing on multi-particle entanglement like GHZ states. This work opened the experimental possibility to do quantum teleportation and quantum hyper-dense coding. The latter became the first entanglement-based quantum experiment breaking a classical limitation. One of the most fascinating phenomena is entanglement swapping, the teleportation of an entangled state. This phenomenon is fundamentally interesting because it can entangle two pairs of particles which do not share any common past. Surprisingly, it also became an important ingredient in a number of applications, including quantum repeaters which will connect future quantum computers with each other. Another application is entanglement-based quantum cryptography where I present some recent long-distance experiments. Entanglement swapping has also been applied in very recent so-called loophole-free tests of Bell's theorem. Within the physics community such loophole-free experiments are perceived as providing nearly definitive proof that local realism is untenable. While, out of principle, local realism can never be excluded entirely, the 2015 achievements narrow down the remaining possibilities for local realistic explanations of the quantum phenomenon of entanglement in a significant way. These experiments may go down in the history books of science. Future experiments will address particularly the freedom-of-choice loophole using cosmic sources of randomness. Such experiments confirm that unconditionally secure quantum cryptography is possible, since quantum cryptography based on Bell's theorem can provide unconditional security. The fact that the experiments were loophole-free proves that an eavesdropper cannot avoid detection in an experiment that correctly follows the protocol. I finally discuss some recent experiments with single-and entangled-photon states in higher dimensions. Such experiments realized quantum entanglement between two photons, each with quantum numbers beyond 10 000 and also simultaneous entanglement of two photons where each carries more than 100 dimensions. Thus they offer the possibility of quantum communication with more than one bit or qubit per photon. The paper concludes discussing Einstein's contributions and viewpoints of quantum mechanics. Even if some of his positions are not supported by recent experiments, he has to be given credit for the fact that his analysis of fundamental issues gave rise to developments which led to a new information technology. Finally, I reflect on some of the lessons learned by the fact that Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
We have used a Tilted Axis Cranking model in combination with particle number projection to analy... more We have used a Tilted Axis Cranking model in combination with particle number projection to analyze the influence of dynamical pairing correlations in the high-K bands of 178 W and their effect on the angular momentum and the relative energy. The results show that our model is able to reproduce the values and trends of the experimental angular momentum and relative energy as a function of ω.
High-spin states in 138 Nd were investigated using the reaction 94 Zr(48 Ca,4n), detecting coinci... more High-spin states in 138 Nd were investigated using the reaction 94 Zr(48 Ca,4n), detecting coincident γ-rays with the gasp spectrometer. A rich level scheme was constructed including 4 bands of negative parity at low spins, 8 bands of dipole transitions and 8 bands of quadrupole transitions at medium spins. The Cranked Shell Model and the Tilted Axis Cranking model are used to assign configurations to the observed bands, where zero pairing is assumed. For selected configurations the case of finite pairing is also considered. A consistent notation for configuration assignment is introduced, which applies both for zero and finite pairing. The observed bands are interpreted as rotation around the short and long principal axes (quadrupole bands), as well as around a tilted axis (dipole bands). The dipole bands have an intermediate character, between magnetic and collective electric rotation. A pair of dipole bands are candidates for chiral partners, the first case this property has been identified in an even-even nucleus. The possible existence of the wobbling mode at low deformation and medium spins is discussed. The consistent interpretation of the multitude of observed bands strongly supports the existence of stable triaxial deformation at medium spins in 138 Nd.
The wobbling motion of a triaxial rotor coupled to a high-j quasiparticle is treated semiclassica... more The wobbling motion of a triaxial rotor coupled to a high-j quasiparticle is treated semiclassically. Longitudinal and transverse coupling regimes can be distinguished depending on, respectively, whether the quasiparticle angular momentum is oriented parallel or perpendicular to the rotor axis with the largest moment of inertia. Simple analytical expressions for the wobbling frequency and the electromagnetic E2 and M1 transition probabilites are derived assuming rigid alignment of the quasiparticle with one of the rotor axes and harmonic oscillations (HFA). Transverse wobbling is characterized by a decrease of the wobbling frequency with increasing angular momentum. Two examples for transverse wobbling, 163 Lu and 135 Pr, are studied in the framework of the full triaxial particle-rotor model and the HFA. The signature of transverse wobbling, decreasing wobbling frequency and enhanced E2 inter-band transitions, is found in agreement with experiment.
A detailed level scheme for 221 Th has been established in an experiment using the 18 O + 207 Pb ... more A detailed level scheme for 221 Th has been established in an experiment using the 18 O + 207 Pb reaction at 96 MeV. The evaporation residues from this fissile system were selected with the HERCULES detector array and residue-gated γ rays were measured with Gammasphere. Three band structures of interlinked, alternating-parity levels are observed, two of which are non-yrast. In addition, several high-lying excitations are found. The yrast band is seen up to spin-parity 37/2 − and 39/2 + , beyond which a high-spin feeding transition is observed. The non-yrast sequences are interpreted as parity-doublet structures, based on a configuration similar to that of the yrast band in 223 Th (K = 5/2). The key properties of even-odd nuclei in this mass region [B(E1)/B(E2) and B(M 1)/B(E2) ratios, spin alignments, parity splittings] are reviewed.
Exotic Nuclei (EXON2004) - Proceedings of the International Symposium, 2005
The structure of neutron-rich nuclei in the A=100 region have been investigated via prompt gamma-... more The structure of neutron-rich nuclei in the A=100 region have been investigated via prompt gamma-gamma-gamma coincidences in the spontaneous fission of 252Cf at Gammasphere. New levels are observed in 93,95,97Sr, 99,101Y, 101,105Nb, 104,106Mo, 105,107,109Tc, 111,113Rh and 115,117Ag. The level structures show a clear evolution from spherical single particle structures seen in Sr, to symmetric, large prolate deformation in Y, to
Two similar sets of odd-parity bands are observed in each of three even–even neighbors, 108, 110,... more Two similar sets of odd-parity bands are observed in each of three even–even neighbors, 108, 110, 112 Ru , from a study of prompt spontaneous-fission gamma rays at Gammasphere. A careful study of the odd-parity levels of these nuclei shows evidence for the features of chiral doubling. Comparisons are made with reported other candidates for chiral doubling.
New insights into the structures of ^108Mo, and ^108,110,112Ru are identified in the spontaneous ... more New insights into the structures of ^108Mo, and ^108,110,112Ru are identified in the spontaneous fission of ^252Cf. The 5.7 x 10^11 triples and higher fold prompt gamma coincidences opened up the possibility to see new weakly populated band structures in these nuclei. Two phonon gamma-bands that decay only to the one phonon gamma-band were discovered in ^108Mo and ^110,112Ru. We discovered in ^108Mo^ and^ 108,110,112Ru deltaI=1, doublet bands. Our theoretical calculations indicate ^108Ru is gamma-soft and ^110,112Ru are more rigid triaxial nuclei. The non-yrast band in ^108Ru shows an energy level staggering not seen in its yrast partner band nor in ^110,112Ru. This staggering is proposed to be related to its gamma-soft shape perturbing its chiral structure. The doublet bands in ^108Mo^ and ^110,112Ru will be shown to have all the properties expected for chiral vibrational bands. Tilted axis cranking calculations for ^110,112Ru stronly support the chiral vibrational interpretation o...
Magnetic dipole strength functions are deduced from averages of a large number of M1 transition s... more Magnetic dipole strength functions are deduced from averages of a large number of M1 transition strengths calculated within the shell model for the nuclides 90 Zr, 94 Mo, 95 Mo, and 96 Mo. An enhancement of M1 strength toward low transition energy is found for all nuclides considered. Large M1 strengths appear for transitions between close-lying states with configurations including proton as well as neutron high-j orbits that recouple their spins and add up their magnetic moments coherently. The M1 strength function deduced from the calculated M1 transition strengths is compatible with the low-energy enhancement found in (3 He, 3 He 0) and (d, p) experiments. The Letter presents an explanation of the experimental findings.
Abstract The g -factors of the yrast levels in even-even rare earth and actinide nuclei are inter... more Abstract The g -factors of the yrast levels in even-even rare earth and actinide nuclei are interpreted in terms of collective and aligned quasiparticle angular momentum extracted from the experimental spectra. A new decomposition of the total angular momentum into collective and quasiparticle parts is suggested and applied to the calculation of g -factors. The systematic analysis of low-spin levels shows a modulation of the moment of inertia, its derivative with respect to the angular frequency and of the g -factors by the position of the high-spin intruder levels. Our cranking calculations of levels and g -factors in 232 Th and 238 U reveal certain difficulties of the standard pairing description for considered examples.
High-spin states in the neutron-rich nuclei 172,173 Yb have been populated in a 170 Er(7 Li,(p,d,... more High-spin states in the neutron-rich nuclei 172,173 Yb have been populated in a 170 Er(7 Li,(p,d,t)xn) incomplete-fusion reaction and the emitted γ-radiation was detected with the GASP array. The signature partners of the 7/2 + [633] rotational band of the odd-N 173 Yb isotope have been newly established and were observed up to spin values of (45/2 +) and (43/2 +), respectively. The ground-state band of the even-even nucleus 172 Yb has been observed up to a spin value of (22 +). No band crossings were found in these bands. To explain this observation, it is proposed that the static pair field is absent, considering that the neutron odd-even mass differences reach for these nuclei very small values and that the band crossing is absent in cranked shell modell calculations without pairing. The results indicate, however, that strong dynamic correlations are still present.
A pair of transverse wobbling bands has been observed in the nucleus 135 Pr. The wobbling is char... more A pair of transverse wobbling bands has been observed in the nucleus 135 Pr. The wobbling is characterized by ∆I =1, E2 transitions between the bands, and a decrease in the wobbling energy confirms its transverse nature. Additionally, a transition from transverse wobbling to a threequasiparticle band comprised of strong magnetic dipole transitions is observed. These observations conform well to results from calculations with the Tilted Axis Cranking (TAC) model and the Quasiparticle Triaxial Rotor (QTR) Model.
Pair correlations are described in the framework of the HFB approximation applied to a uniformly ... more Pair correlations are described in the framework of the HFB approximation applied to a uniformly rotating system (Cranking model). The reduction of the moments of inertia, the classification of rotational bands as multi quasiparticle configurations, and the signatures of the rotation induced transition to the unpaired state are discussed.
It is shown that the rotating mean field of triaxial nuclei can break the chiral symmetry. Two ne... more It is shown that the rotating mean field of triaxial nuclei can break the chiral symmetry. Two nearly degenerate ∆I = 1 rotational bands originate from the left-handed and righthanded solution.
The high-spin structure of 205 Rn has been investigated for the first time following the 170 Er(4... more The high-spin structure of 205 Rn has been investigated for the first time following the 170 Er(40 Ar,5n) and 197 Au(14 N,6n) reactions at beam energies of 183 MeV and 90-110 MeV, respectively, using the Jurosphere and YRAST Ball arrays. Two new cascades have been identified which dominate the high-spin decay. One of these, consisting of ten stretched M 1 transitions with unobserved E2 crossover transitions, is interpreted as a shears structure based on the i 13/2 Ϫ1 i 13/2 2 ͑or i 13/2 Ϫ1 h 9/2 i 13/2 ͒ configuration. ͓S0556-2813͑99͒50506-2͔
The yrast states of transitional nuclei are described as quadrupole waves running over the nuclea... more The yrast states of transitional nuclei are described as quadrupole waves running over the nuclear surface, which we call tidal waves. In contrast to a rotor, which generates angular momentum by increasing the angular velocity at approximately constant deformation, a tidal wave generates angular momentum by increasing the deformation at approximately constant angular velocity. The properties of the tidal waves are calculated by means of the cranking model in a microscopic way. The calculated energies and E2 transition probabilities of the yrast states in the transitional nuclides with Z= 44, 46, 48 and N = 56, 58, ..., 66 reproduce the experiment in detail. The nonlinear response of the nucleonic orbitals results in a strong coupling between shape and single particle degrees of freedom.
The cranked relativistic Hartree+Bogoliubov theory has been applied for a systematic study of the... more The cranked relativistic Hartree+Bogoliubov theory has been applied for a systematic study of the nuclei around 254 No, the heaviest elements for which detailed spectroscopic data are available. The deformation, rotational response, pairing correlations, quasi-particle and other properties of these nuclei have been studied with different parametrizations for the effective mean-field Lagrangian. Pairing correlations are taken into account by a finite range two-body force of Gogny type. While the deformation properties are well reproduced, the calculations reveal some deficiencies of the effective forces both in the particle-hole and particle-particle channels. For the first time, the quasi-particle spectra of odd deformed nuclei have been calculated in a fully self-consistent way within the framework of the relativistic mean field (RMF) theory. The energies of the spherical subshells, from which active deformed states of these nuclei emerge, are described with an accuracy better than 0.5 MeV for most of the subshells with the NL1 and NL3 parametrizations. However, for a few subshells the discrepancies reach 0.7-1.0 MeV. In very heavy systems, where the level density is high, this level of accuracy is not sufficient for reliable predictions of the location of relatively small deformed shell gaps. The calculated moments of inertia reveal only small sensitivity to the RMF parametrization and, thus, to differences in the single-particle structure. However, in contrast to lighter systems, it is necessary to decrease the strength of the D1S Gogny force in the pairing channel in order to reproduce the moments of inertia.
High spin states in A ~ 110 neutron-rich 106Mo, 110Ru and 112Ru nuclei have been reinvestigated b... more High spin states in A ~ 110 neutron-rich 106Mo, 110Ru and 112Ru nuclei have been reinvestigated by measuring the prompt gamma-rays from the spontaneous fission of 252Cf. Two similar sets of bands are observed to high spins in each of three nuclei. Through analyzing of characters of the band structures, the chiral doublet bands are suggested in 106Mo, 110Ru and
A systematic study of the doublet bands observed in odd-odd mass ∼ 100 is performed using the mic... more A systematic study of the doublet bands observed in odd-odd mass ∼ 100 is performed using the microscopic triaxial projected shell model approach. This mass region has depicted some novel features which are not observed in other mass regions, for instance, it has been observed that two chiral bands cross diabatically in 106 Ag. It is demonstrated that this unique feature is due to crossing of the two 2-quasiparticle configurations having different intrinsic structures. Further, we provide a complete set of transition probabilities for all the six-isotopes studied in this work and it is shown that the predicted transitions are in good agreement with the available experimental data.
The quantum physics of light is a most fascinating field. Here I present a very personal viewpoin... more The quantum physics of light is a most fascinating field. Here I present a very personal viewpoint, focusing on my own path to quantum entanglement and then on to applications. I have been fascinated by quantum physics ever since I heard about it for the first time in school. The theory struck me immediately for two reasons: (1) its immense mathematical beauty, and (2) the unparalleled precision to which its predictions have been verified again and again. Particularly fascinating for me were the predictions of quantum mechanics for individual particles, individual quantum systems. Surprisingly, the experimental realization of many of these fundamental phenomena has led to novel ideas for applications. Starting from my early experiments with neutrons, I later became interested in quantum entanglement, initially focusing on multi-particle entanglement like GHZ states. This work opened the experimental possibility to do quantum teleportation and quantum hyper-dense coding. The latter became the first entanglement-based quantum experiment breaking a classical limitation. One of the most fascinating phenomena is entanglement swapping, the teleportation of an entangled state. This phenomenon is fundamentally interesting because it can entangle two pairs of particles which do not share any common past. Surprisingly, it also became an important ingredient in a number of applications, including quantum repeaters which will connect future quantum computers with each other. Another application is entanglement-based quantum cryptography where I present some recent long-distance experiments. Entanglement swapping has also been applied in very recent so-called loophole-free tests of Bell's theorem. Within the physics community such loophole-free experiments are perceived as providing nearly definitive proof that local realism is untenable. While, out of principle, local realism can never be excluded entirely, the 2015 achievements narrow down the remaining possibilities for local realistic explanations of the quantum phenomenon of entanglement in a significant way. These experiments may go down in the history books of science. Future experiments will address particularly the freedom-of-choice loophole using cosmic sources of randomness. Such experiments confirm that unconditionally secure quantum cryptography is possible, since quantum cryptography based on Bell's theorem can provide unconditional security. The fact that the experiments were loophole-free proves that an eavesdropper cannot avoid detection in an experiment that correctly follows the protocol. I finally discuss some recent experiments with single-and entangled-photon states in higher dimensions. Such experiments realized quantum entanglement between two photons, each with quantum numbers beyond 10 000 and also simultaneous entanglement of two photons where each carries more than 100 dimensions. Thus they offer the possibility of quantum communication with more than one bit or qubit per photon. The paper concludes discussing Einstein's contributions and viewpoints of quantum mechanics. Even if some of his positions are not supported by recent experiments, he has to be given credit for the fact that his analysis of fundamental issues gave rise to developments which led to a new information technology. Finally, I reflect on some of the lessons learned by the fact that Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
We have used a Tilted Axis Cranking model in combination with particle number projection to analy... more We have used a Tilted Axis Cranking model in combination with particle number projection to analyze the influence of dynamical pairing correlations in the high-K bands of 178 W and their effect on the angular momentum and the relative energy. The results show that our model is able to reproduce the values and trends of the experimental angular momentum and relative energy as a function of ω.
High-spin states in 138 Nd were investigated using the reaction 94 Zr(48 Ca,4n), detecting coinci... more High-spin states in 138 Nd were investigated using the reaction 94 Zr(48 Ca,4n), detecting coincident γ-rays with the gasp spectrometer. A rich level scheme was constructed including 4 bands of negative parity at low spins, 8 bands of dipole transitions and 8 bands of quadrupole transitions at medium spins. The Cranked Shell Model and the Tilted Axis Cranking model are used to assign configurations to the observed bands, where zero pairing is assumed. For selected configurations the case of finite pairing is also considered. A consistent notation for configuration assignment is introduced, which applies both for zero and finite pairing. The observed bands are interpreted as rotation around the short and long principal axes (quadrupole bands), as well as around a tilted axis (dipole bands). The dipole bands have an intermediate character, between magnetic and collective electric rotation. A pair of dipole bands are candidates for chiral partners, the first case this property has been identified in an even-even nucleus. The possible existence of the wobbling mode at low deformation and medium spins is discussed. The consistent interpretation of the multitude of observed bands strongly supports the existence of stable triaxial deformation at medium spins in 138 Nd.
The wobbling motion of a triaxial rotor coupled to a high-j quasiparticle is treated semiclassica... more The wobbling motion of a triaxial rotor coupled to a high-j quasiparticle is treated semiclassically. Longitudinal and transverse coupling regimes can be distinguished depending on, respectively, whether the quasiparticle angular momentum is oriented parallel or perpendicular to the rotor axis with the largest moment of inertia. Simple analytical expressions for the wobbling frequency and the electromagnetic E2 and M1 transition probabilites are derived assuming rigid alignment of the quasiparticle with one of the rotor axes and harmonic oscillations (HFA). Transverse wobbling is characterized by a decrease of the wobbling frequency with increasing angular momentum. Two examples for transverse wobbling, 163 Lu and 135 Pr, are studied in the framework of the full triaxial particle-rotor model and the HFA. The signature of transverse wobbling, decreasing wobbling frequency and enhanced E2 inter-band transitions, is found in agreement with experiment.
A detailed level scheme for 221 Th has been established in an experiment using the 18 O + 207 Pb ... more A detailed level scheme for 221 Th has been established in an experiment using the 18 O + 207 Pb reaction at 96 MeV. The evaporation residues from this fissile system were selected with the HERCULES detector array and residue-gated γ rays were measured with Gammasphere. Three band structures of interlinked, alternating-parity levels are observed, two of which are non-yrast. In addition, several high-lying excitations are found. The yrast band is seen up to spin-parity 37/2 − and 39/2 + , beyond which a high-spin feeding transition is observed. The non-yrast sequences are interpreted as parity-doublet structures, based on a configuration similar to that of the yrast band in 223 Th (K = 5/2). The key properties of even-odd nuclei in this mass region [B(E1)/B(E2) and B(M 1)/B(E2) ratios, spin alignments, parity splittings] are reviewed.
Exotic Nuclei (EXON2004) - Proceedings of the International Symposium, 2005
The structure of neutron-rich nuclei in the A=100 region have been investigated via prompt gamma-... more The structure of neutron-rich nuclei in the A=100 region have been investigated via prompt gamma-gamma-gamma coincidences in the spontaneous fission of 252Cf at Gammasphere. New levels are observed in 93,95,97Sr, 99,101Y, 101,105Nb, 104,106Mo, 105,107,109Tc, 111,113Rh and 115,117Ag. The level structures show a clear evolution from spherical single particle structures seen in Sr, to symmetric, large prolate deformation in Y, to
Two similar sets of odd-parity bands are observed in each of three even–even neighbors, 108, 110,... more Two similar sets of odd-parity bands are observed in each of three even–even neighbors, 108, 110, 112 Ru , from a study of prompt spontaneous-fission gamma rays at Gammasphere. A careful study of the odd-parity levels of these nuclei shows evidence for the features of chiral doubling. Comparisons are made with reported other candidates for chiral doubling.
New insights into the structures of ^108Mo, and ^108,110,112Ru are identified in the spontaneous ... more New insights into the structures of ^108Mo, and ^108,110,112Ru are identified in the spontaneous fission of ^252Cf. The 5.7 x 10^11 triples and higher fold prompt gamma coincidences opened up the possibility to see new weakly populated band structures in these nuclei. Two phonon gamma-bands that decay only to the one phonon gamma-band were discovered in ^108Mo and ^110,112Ru. We discovered in ^108Mo^ and^ 108,110,112Ru deltaI=1, doublet bands. Our theoretical calculations indicate ^108Ru is gamma-soft and ^110,112Ru are more rigid triaxial nuclei. The non-yrast band in ^108Ru shows an energy level staggering not seen in its yrast partner band nor in ^110,112Ru. This staggering is proposed to be related to its gamma-soft shape perturbing its chiral structure. The doublet bands in ^108Mo^ and ^110,112Ru will be shown to have all the properties expected for chiral vibrational bands. Tilted axis cranking calculations for ^110,112Ru stronly support the chiral vibrational interpretation o...
Magnetic dipole strength functions are deduced from averages of a large number of M1 transition s... more Magnetic dipole strength functions are deduced from averages of a large number of M1 transition strengths calculated within the shell model for the nuclides 90 Zr, 94 Mo, 95 Mo, and 96 Mo. An enhancement of M1 strength toward low transition energy is found for all nuclides considered. Large M1 strengths appear for transitions between close-lying states with configurations including proton as well as neutron high-j orbits that recouple their spins and add up their magnetic moments coherently. The M1 strength function deduced from the calculated M1 transition strengths is compatible with the low-energy enhancement found in (3 He, 3 He 0) and (d, p) experiments. The Letter presents an explanation of the experimental findings.
Abstract The g -factors of the yrast levels in even-even rare earth and actinide nuclei are inter... more Abstract The g -factors of the yrast levels in even-even rare earth and actinide nuclei are interpreted in terms of collective and aligned quasiparticle angular momentum extracted from the experimental spectra. A new decomposition of the total angular momentum into collective and quasiparticle parts is suggested and applied to the calculation of g -factors. The systematic analysis of low-spin levels shows a modulation of the moment of inertia, its derivative with respect to the angular frequency and of the g -factors by the position of the high-spin intruder levels. Our cranking calculations of levels and g -factors in 232 Th and 238 U reveal certain difficulties of the standard pairing description for considered examples.
High-spin states in the neutron-rich nuclei 172,173 Yb have been populated in a 170 Er(7 Li,(p,d,... more High-spin states in the neutron-rich nuclei 172,173 Yb have been populated in a 170 Er(7 Li,(p,d,t)xn) incomplete-fusion reaction and the emitted γ-radiation was detected with the GASP array. The signature partners of the 7/2 + [633] rotational band of the odd-N 173 Yb isotope have been newly established and were observed up to spin values of (45/2 +) and (43/2 +), respectively. The ground-state band of the even-even nucleus 172 Yb has been observed up to a spin value of (22 +). No band crossings were found in these bands. To explain this observation, it is proposed that the static pair field is absent, considering that the neutron odd-even mass differences reach for these nuclei very small values and that the band crossing is absent in cranked shell modell calculations without pairing. The results indicate, however, that strong dynamic correlations are still present.
A pair of transverse wobbling bands has been observed in the nucleus 135 Pr. The wobbling is char... more A pair of transverse wobbling bands has been observed in the nucleus 135 Pr. The wobbling is characterized by ∆I =1, E2 transitions between the bands, and a decrease in the wobbling energy confirms its transverse nature. Additionally, a transition from transverse wobbling to a threequasiparticle band comprised of strong magnetic dipole transitions is observed. These observations conform well to results from calculations with the Tilted Axis Cranking (TAC) model and the Quasiparticle Triaxial Rotor (QTR) Model.
Pair correlations are described in the framework of the HFB approximation applied to a uniformly ... more Pair correlations are described in the framework of the HFB approximation applied to a uniformly rotating system (Cranking model). The reduction of the moments of inertia, the classification of rotational bands as multi quasiparticle configurations, and the signatures of the rotation induced transition to the unpaired state are discussed.
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