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Generating narrow energy spread beams from laser wakefield accelerators with minimal dark current is important for many applications. We present an automated experiment using Bayesian optimization to control the laser spectral phase and focal position, achieving significant enhancement of the beam quality. Starting from a broadband spectrum, the optimized configuration achieved low-energy spread w
The total potential energy surfaces of several thallium, gold, iridium and rhenium odd-mass isotones are calculated microscopically as functions of the quadrupole deformation epsilon 2, when the odd protons occupy definite orbitals. The nuclear shapes and the static equilibrium deformations of these nuclei are deduced from the results of these calculations for the proton orbitals nearest to the Fe
Nilsson-Strutinsky cranking calculations on A ≥ 100 Ru and Pd nuclei suggest that, contrary to other mass regions, it should be possible to follow the ground state rotational bands to their termination at spins just above I = 30ℏ and then also to observe other bands which terminate at higher spins.
A semi-empirical method inspired by Blomqvist's (1969) previous calculations of the excitation energy of the lowest 9/2- state of 201Tl is applied to similar calculations in different Tl, Au and Ir isotopes. These semi-empirical estimates agree well with the experimental values of the excitation energies as well as with the energy differences deduced from the analysis of the total potential energy
Levels and transitions in 107In and 109In have been studied in in-beam spectroscopy on the reactions 106Cd(d, nγ)107In and 108Cd(d, nγ)109In. Low-lying 1 2+ and 3 2+ states resembling the possible rotational bands observed in the heavier In isotopes are seen in both nuclei. The potential energy has been calculated for 107-121In with the odd proton in different orbitals, using the Strutinsky normal
A broad discussion of the ground-state potential-energy surfaces of doubly even deformed and transitional nuclei with Z = 50-82 is presented. The surfaces are calculated microscopically as functions of the quadrupole axial ε and non-axial γ and the axial hexadecapole ε4 deformations. A correlation between the form of the surfaces and the experimental spectroscopic trends is extensively discussed.
The effects of the simultaneous presence of monopole and quadrupole pairing interactions on the fission barriers for heavy and superheavy elements are considered. The first barrier for light Thisotopes is found to be raised by 1 MeV, while heavier actinide nuclei seem to be less affected by the inclusion of quadrupole pairing. For the superheavy elements, the inclusion of quadrupole pairing tends
Ground state moments of inertia and collective gyromagnetic ratios of deformed even nuclei with 50 < Z, N < 82 are calculated in the cranking-model approximation. Rather good agreement with experimental values of the moments of inertia is obtained. The dependence of the moment of inertia on the quadrupole (axial ε and non-axial γ) and on the hexadecapole ε4 deformations is investigated. Special co
Relations between different core-particle coupling models based on the Bohr Hamiltonian are discussed, and in particular the γ-unstable and rigid 30° triaxial cores are compared quantitatively. A new formulation is developed employing a rigid triaxial rotor core and the strong-coupling basis. Within the limitations imposed by this model core, it is equally applicable in the limits of small and ext
A detailed analysis of the positive parity levels in odd gold isotopes is carried out with an extended version of the Hecht and Satchler model (1962). A satisfactory description of 193-199Au positive parity levels and their electromagnetic properties is obtained by coupling several Nilsson particle configurations to an asymmetric rotor.
The strong shell effects observed experimentally and theoretically at high spins and moderate deformations are explained in terms of the interference between two effects. Thus, the effect of the quadrupole deformation to destroy the spherical shell degeneracy can be largely compensated by the orbital separation due to rotational motion. In the resulting coupling scheme, the subshell degeneracy of
A detailed analysis of all the available experimental data concerning the h11/2 system of levels in 189,193,195Au is made with the generalised particle-asymmetric rotor model applied previously to the description of the positive-parity states. The influence of several Nilsson orbitals on such h11/2 systems is also investigated in detail.
A detailed analysis of the positive parity levels in odd iridium isotopes is carried out with an extended version of the Hecht and Satchler model. A satisfactory description of187-193Ir positive parity states and their electromagnetic properties is obtained by coupling several Nilsson particle configurations to an asymmetric rotor.
Two γ-rays of 129.2 and 288.4 keV observed in the β-decay of 55 ms 100Rb are interpreted as representing the two lowest transitions in the 100Sr ground-state rotational band. The energy ratio of the two levels, 3.23, approaches the value for a rigid rotator. The half-life of the 2+ state is 5.15 ± 0.20 ns corresponding to a deformation parameter ε{lunate} of 0.29. The theoretical implications of t
The negative parity states of Ag105-109 are interpreted according to the generalized particle asymmetric-rotor model. In particular, the influence of the different Nilsson proton orbitals (lying near the Fermi level) on the theoretical level spectra and electromagnetic properties is investigated in detail. Furthermore, the analysis of the wave functions of the theoretical levels, and the contribut
Hyperfine structure measurements have been performed in some neutron-deficient gold isotopes, using on-line atomic-beam magnetic resonance (ABMR) techniques at the ISOLDE facility, CERN. The following results have been obtained: 185Au, I = 5/2; 187Au, Δv = 44.35(60) GHz, μ = 0.72(7) n.m. and 188Au, Δv = ± 2992(30) MHz. A discussion of the influence of the hyperfine anomaly is included. With due re
We introduce a method which makes possible to consider individual rotational bands in the high-spin region where pairing is unimportant. For each band, an independent energy minimisation with respect to quadrupole and hexadecapole deformation is performed. Bandcrossings at and above the yrast line are discussed in the light of recent experimental results.
Negative-parity excited states of doubly even nuclei have earlier been attributed to vibrational excitations. This paper shows that an interpretation starting from a reflection asymmetric intrinsic state is more appropriate for certain nuclei in the radium region. Theoretical evidence for stable octupole deformation comes from a deformed shell-model calculation in which we use a single-particle po
The very high spin behaviour of nuclei with ∼ 10 particles outside the 146Gd core are studied. Our method of calculation, which is based on the cranked Nilsson-Strutinsky formalism, makes possible to follow individual configurations as functions of spin. We concentrate on 158Er and 154Dy which nuclei become oblate with rotation around the symmetry axes for I = 40-50. It is found that most such obl
First, nuclear shapes are considered with focus on the γ degree of freedom and the unexplored high-spin regions of negative γ. Next, the role of approximate quantum numbers for very high-spin spectroscopy is examined, using as an example a calculation for 160Er which is related to available quasicontinuum data. The trend from regular to chaotic behavior is discussed in the broader context of theor
