-
E Grosse,
A Balanda,
H Emling,
F Folkmann,
P Fuchs,
R B Piercey,
D Schwalm,
R S Simon,
H J Wollersheim,
D Evers,
H Ower
[show abstract]
[hide abstract]
ABSTRACT: An experimental study of the actinide nucleus 238U was performed by Coulomb excitation with 208Pb projectiles. The E2-transition matrix elements in the ground state band were measured up to spin 28 by comparing experimental Coulomb excitation yields to semiclassical calculations and by analysing Doppler broadened line shapes measured in coincidence with a gamma-ray sum spectrometer. The E2-metrix elements agree within their errors with the rigid rotor predictions. Neither an increase of the collective transition strength at high spin due to centrifugal stretching as predicted by the Rotation Vibration Model nor a cutoff in collectively as postulated by the Interacting Boson Model is observed. The excitation energies in the ground state band show the presence of an aligned angular momentum of 5 at spin 30 which can be explained by a crossing of an aligned band at ω ≈ 250 keV. The octupole band shows a constant angular momentum alignment of 3 (above spin 7) and no indication of a bandcrossing.
Physica Scripta 12/2006; 24(1B):337. · 1.20 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Coulomb excitation studies of 248Cm were carried out with 5.3 MeV u-1 208Pb projectiles from the GSI UNILAC. A rotational band built on the ground state of 248Cm has been identified to spin 28+ and a tentative 30+ assignment has been made made. The angular dependence of the yields for transitions de-exciting levels from spin 28+ to 6+ have been measured and used to support the spin and parity assignments. An anomalous level spacing, is observed above 22+ and is interpreted as the crossing of a rotation-aligned band at high spin. The E2 matrix elements connecting the states of the ground-state band up to 28+ have been determined by comparing the experimental yields to calculations based on semi-classical Coulomb excitation with subsequent gamma-ray decay. The effect of the excitation of other collective states is also considered. No strong deviation of the matrix elements from rigid-rotor behaviour has been seen.
Journal of Physics G Nuclear and Particle Physics 12/1998; 19(6):849. · 4.18 Impact Factor
-
G. Kraus,
P. Egelhof,
H. Emling, E. Grosse,
W. Henning,
R. Holzmann,
H. J. Körner,
J. V. Kratz,
R. Kulessa,
Ch. Schießl,
J. P. Schiffer,
W. Wagner,
W. Walus,
H. J. Wollersheim
[show abstract]
[hide abstract]
ABSTRACT: The one-neutron transfer reactions d(132,136
Xe, p)133,137
Xe have been investigated in inverse kinematics with xenon beams incident on deuterium loaded titanium targets. The angular distributions of the protons, measured with a detector array of 100 PIN-photodiodes, have been analyzed using standard DWBA. Generally, good agreement is obtained with results previously obtained in reactions induced by light-ion beams.
Zeitschrift für Physik A Hadrons and Nuclei 01/1991; 340(3):339-340.
-
[show abstract]
[hide abstract]
ABSTRACT: The nuclear level structure and electromagnetic properties of196Pt were investigated with-spectroscopic techniques using multiple Coulomb excitation by208Pb projectiles. Particle-, and particle-- coincidences were measured over a wide range of scattering angles.E2-transition moments and static quadrupole moments have been determined by a comparison of experimental scattering-angle dependent yields with calculated yields in a largely model-independent procedure. The results are compared with different theoretical models: the Asymmetric-Rotor Model, the Generalized Collective Model, and the Interacting Boson Model. The best agreement is obtained with the Generalized Collective Model representing a triaxial nucleus which is soft in the degree of freedom.
Zeitschrift für Physik A Hadrons and Nuclei 01/1990; 336(3):263-278.
-
Phys.Lett. 01/1989; 218B:421.
-
Proc.Intern.Conf.Nuclear Structure Through Static and Dynamic Moments; 01/1987
-
[show abstract]
[hide abstract]
ABSTRACT: In a systematic study of nucleon transfer reactions accompanied by Coulomb excitation we have bombarded152Sm,160Gd and232Th with206, 208pb beams at incident energies close to the Coulomb barrier. Particle-gamma coincidence techniques were used to identify excited states of reaction products populated through inelastic scattering and in nucleon transfer reactions. One-neutron stripping and pick-up reactions on152Sm were observed leading to known states of the rotation alignedi
13/2-bands in153Sm and151Sm. In the160Gd+206, 208Pb systems no significant population of low lying states of product nuclei was found in the nucleon-transfer channels. Large cross sections were observed for one- and two-neutron pick-up from232Th at an incident energy of 6.4 MeV/u. Around the grazing angle they are of the same order of magnitude as the cross section measured for inelastic scattering. The results are analyzed in the framework of semiclassical models.
Zeitschrift für Physik A Hadrons and Nuclei 11/1986; 325(4):457-466.
-
Nucl. Instr. and Meth. in Phys. Res. A. 01/1986; 251:119-133.
-
[show abstract]
[hide abstract]
ABSTRACT: Multiple Coulomb excitation measurements on202, 204Hg have been performed with 5 MeV/u208Pb projectiles. The ground bands are excited up to the newly discovered 6+ states and B(E2) values are derived for the 4+2+ and 6+4+ transitions. Whereas the 2+ and 4+ levels in the Hg isotopes with 196A204 have an almost constant energy, the 6+ levels increase in202Hg and204Hg, compared to the lighter isotopes, by approximately 100 and 300 keV, respectively. The relative B(E2) values in both nuclei show that the collectivity in the neutron rich Hg nuclei is of more complex origin than expected from the few proton and neutron holes with respect to the 82 and 126 major shells.
Zeitschrift für Physik A Hadrons and Nuclei 05/1985; 320(2):295-299.
-
[show abstract]
[hide abstract]
ABSTRACT: Cross sections for doubleK shell excitation and for the production of continuum x-rays in coincidence withK x-rays from 4.8 MeV/amu208Pb +208Pb collisions have been measured. A simple statistical model is presented to explain double vacancy contributions to the coincidence cross sections and the relative contributions of MO x-ray,K x-ray cascade and MO x-ray,K x-ray double vacancy coincidences are evaluated. These latter yields are found to be significant enough to make extraction of the cascade contribution to the measured coincidence yields problematic.
Zeitschrift für Physik A Hadrons and Nuclei 01/1985; 322(4):547-556.
-
[show abstract]
[hide abstract]
ABSTRACT: The ground-state band of159Tb has been Coulomb excited up to spin 23/2 by 151-MeV40Ar ions. The lifetimes of the 9/2 to 23/2 levels have been determined by combining results obtained with the RD and DSA methods, theE2/M1 mixing ratios for I=1 transitions have been measured using angular correlation techniques and the branching ratios for the levels up to spin 17/2 have been determined. The energies of the levels and the reducedM1 andE2 transition probabilities for their decay have been compared with the predictions of the rotational model, without and with K=1 admixtures. No satisfactory agreement could be achieved for all available experimental data simultaneously.
Zeitschrift für Physik A Hadrons and Nuclei 01/1984; 319(1):33-46.
-
Zeitschrift für Physik A 01/1984; 319:33-46.
-
R. Kulessa,
R. P. DeVito,
H. Emling, E. Grosse,
D. Schwalm,
R. S. Simon,
A. Lefebvre,
Ch. Briançon,
R. J. Walen,
G. Sletten,
Th. W. Elze
[show abstract]
[hide abstract]
ABSTRACT: The investigation of the odd-neutron nucleus235U and odd-proton nucleus237Np provides the possibility to study separately the alignment effects in thei
13/2 proton andj
15/2 neutron intruder states in the actinides. Using Coulomb excitation with208Pb projectiles we were able to extend the yrast bands up to the 57/2 levels in both cases. The experimental results consistently show — at least in the region of the rotational frequencies studied — the dominant role of thei
13/2 proton alignment, as well as the weakness of the interaction strength of thej
15/2 neutrons-configuration forN=144.
Zeitschrift für Physik A Hadrons and Nuclei 02/1983; 312(1):135-141.
-
W. Spreng,
F. Azgui,
H. Emling, E. Grosse,
R. Kulessa,
C. Michel,
D. Schwalm,
R. Simon,
H-J. Wollersheim,
M. Mutterer,
J.P. Theobald,
M.S. Moore,
N. Trautmann,
J.L. Egido,
P. Ring
Physical Review Letter. 01/1983;
-
01/1982;
-
C. Günther,
H. Hübel,
A. Kleinrahm,
R. Kulessa,
H. Emling,
P. Fuchs, E. Grosse,
D. Schwalm,
H. J. Wollersheim,
J. Idzko,
H. Ower
[show abstract]
[hide abstract]
ABSTRACT: Multiple Coulomb excitation measurements on198, 200Hg have been performed with 5MeV/amu208Pb projectiles andB(E2)-values are determined for transitions between states up to spin 8+. In198Hg a reduction of theB(E2)-value for the yrast transition 8+6+ by a factor of 3 as compared to the rigid rotor prediction is observed, which supports the earlier proposed idea that the ground state band is crossed between the 6+ and 8+ state by a weakly interactingvi
13
2/2
rotation aligned band. In each of the two nuclei,198Hg and200Hg, a state with a possibleI
=8+ assignment is observed, which is tentatively interpreted as the 8+ member of the ground state band.
Zeitschrift für Physik A Hadrons and Nuclei 05/1981; 301(2):119-123.
-
[show abstract]
[hide abstract]
ABSTRACT: A high-accuracy investigation of absolute γ-ray yields and angular distributions after Coulomb excitation of 203Tl, 205Tl and 209Bi allowed the determination of B(E2) and B(M1) values in these nuclei. Some of the data obtained are compared with direct lifetime measurements and internal conversion data. The influence of deorientation effects on our results is discussed. A comparison is made between the experimental transition matrix elements and shell-model and core-coupling-model calculations. The “l-forbidden” M1 transitions, which are caused by core-polarization effects, have strengths of ≈ 10−3 W.u. In 209Bi the strength of the . E2 transition is equivalent to a surprisingly large proton polarization charge of (2.8 ± 0.2)e.
Nuclear Physics A.
-
[show abstract]
[hide abstract]
ABSTRACT: Lifetimes of states with spins up to 30ħ have been measured in the nuclei 156Dy, 157Dy, and ll58Dy using the recoil-distance technique together with inverse reactions of the type . The applied method, which benefited from the high velocities of the fusion residues as well as from improvements of the recoil-distance technique, allowed us to determine lifetimes and feeding times down to 0.1 ps. Below the first backbending the resultant B(E2) values in the ground-state band of 156, 158Dy increase faster with increasing rotational frequency than expected for rigid rotors, reaching values similar to those observed for the well-deformed neutron-rich Dy isotopes. In contrast to this, the E2-transition probabilities between high-spin states are clearly retarded. The retardation gradually evolves from the rotation alignment of nucléons and indicates deformation changes most likely towards a triaxial shape. From the analysis of the side-feeding times of the high-spin yrast states it could be furthermore deduced that the E2 component of the preyrast γ-decay stems from transitions along highly collective bands.
Nuclear Physics A.
-
[show abstract]
[hide abstract]
ABSTRACT: The lead isotopes were Coulomb excited with α-particles of 15 and 18 MeV and 16O ions of 70 and 80 MeV. By measuring the absolute yields of the de-excitation γ-rays very accurately, B(Eλ) values for the first 2+ states in 204Pb and 206Pb, the 3− states in 206Pb and 208Pb and of four states in 207Pb were obtained. The E2 transition strengths to the two first excited states of 207Pb are well described by coupling these states to a quadrupole core excitation of 208Pb. The B(E3) values for the excitation of the () doublet show only slight deviations from the weak coupling value, yet the lifetimes of the two states, which were determined with the Doppler-shift attenuation method, are different from model predictions. The M1 transition rate of the − state to ground as determined from the lifetime of 0.17 ps agrees with the value obtained from the B(E2) and the mixing ratio measurement.
Nuclear Physics A.
-
H. Ower,
Th. W. Elze,
J. Idzko,
K Stelzer,
H. Emling,
P. Fuchs, E. Grosse,
D. Schwalm,
H J Wollersheim,
N. Kaffrell,
N. Trautmann
http://dx.doi.org/10.1051/jphyscol:19801011.
