arXiv subjects

D. Almehed

Publications and source records attributed to D. Almehed.

7 recordsLinked to original sources

arXiv2007

Level Structure of 103Ag at high spins

High spin states in $^{103}$Ag were investigated with the Gammasphere array, using the $^{72}$Ge($^{35}$Cl,$2p2n$)$^{103}$Ag reaction at an incident beam energy of 135 MeV. A $ΔJ$=1 sequence with predominantly magnetic transitions and two nearly-degenerate $ΔJ=1$ doublet bands have been observed. The dipole band shows a decreasing trend in the $B(M1)$ strength as function of spin, a well established feature of magnetic bands. The nearly-degenerate band structures satisfy the three experimental signatures of chirality in the nuclei; however microscopic calculations are indicative of a magnetic phenomenon

nucl-ex↗

arXiv2007

From chiral vibration to static chirality in ^{135}Nd

Electromagnetic transition probabilities have been measured for the intra- and inter-band transitions in the two sequences in the nucleus ^{135}Nd that were previously identified as a composite chiral pair of rotational bands. The measurements are in good agreement with results of a new combination of TAC and RPA calculations. The chiral character of the bands is affirmed and it is shown that their behavior is associated with a transition from a vibrational into a static chiral regime.

nucl-ex↗

arXiv2003

Quadrupole correlations and inertial properties of rotating nuclei

The contribution of quantum shape fluctuations to inertial properties of rotating nuclei has been analyzed for QQ-nuclear interaction using the random phase approximation (RPA). The different recipes to treat the cranking mean field plus RPA problem are considered. The effects of the dN=2 quadrupole matrix elements and the role of the volume conservation condition are discussed.

nucl-th↗

arXiv2001

Dynamical moment of inertia and quadrupole vibrations in rotating nuclei

The contribution of quantum shape fluctuations to inertial properties of rotating nuclei has been analysed within the self-consistent one-dimensional cranking oscillator model. It is shown that in even-even nuclei the dynamical moment of inertia calculated in the mean field approximation is equivalent to the Thouless-Valatin moment of inertia calculated in the random phase approximation if and only if the self-consistent conditions for the mean field are fulfilled.

nucl-th↗

arXiv2001

Quadrupole moments of high-spin isomers: test of the tilted-axis cranking model

We report the results of recent measurements of the spectroscopic quadrupole moments of high-spin isomers. For the K=35/2- five-quasiparticle isomer in 179W we measured Q_s=4.00(+0.83)(-1.06)eb. It corresponds to a smaller deformation compared to the ground states of the W isotopes and is in disagreement with the current theoretical predictions. We also measured the quadrupole moment of the I=11- isomer in 196Pb, Q_s=(-)3.41(66)eb. It has the same proton s(-2)1/2 h9/2 i13/2 configuration as the one suggested for the I=16- magnetic bandhead which allows to deduce the quadrupole moment of the 16- state as Q_s=-0.316(97)eb. This small value proves the near sphericity of the bandhead.

nucl-ex↗

arXiv2000

Pair correlations in high-K bands

The tilted axis cranking model is used in combination with the random phase approximation and particle number projection to analyze the influence of dynamical pair correlations in the high-K bands of 178-W and their effect on relative energy and angular momentum. The calculations show the importance of dynamical pair correlations to describe the experiment as well as advantages and problems with the different models in the superfluid and normal state regions.

nucl-th↗

arXiv1999

Integral representation of the RPA correlation energy

Using the spectral function F'(z)/F(z) the RPA correlation energy and other properties of a finite system can be written as a contour integral in a compact way. This yields a transparent expression and reduces drastically the numerical efforts for obtaining reliable values. The method applied to pairing vibrations in rotating nuclei as an illustrative example.

nucl-th↗