38 research outputs found
Role of cross-shell excitations in the reaction 54Fe(d_pol,p)55Fe
The reaction 54Fe(d_pol,p)55Fe was studied at the Munich Q3D spectrograph
with a 14 MeV polarized deuteron beam. Excitation energies, angular
distributions and analyzing powers were measured for 39 states up to 4.5 MeV
excitation energy. Spin and parity assignments were made and spectroscopic
factors deduced by comparison to DWBA calculations. The results were compared
to predictions by large scale shell model calculations in the full pf-shell and
it was found that reasonable agreement for energies and spectroscopic factors
below 2.5 MeV could only be obtained if up to 6 particles were allowed to be
excited from the f_7/2 orbital into p_3/2, f_5/2, and p_1/2 orbitals across the
N=28 gap. For levels above 2.5 MeV the experimental strength distribution was
found to be significantly more fragmented than predicted by the shell model
calculations.Comment: 9 pages, 12 figures, 3 tables, submitted to European Physical Journal
Clustering in 18O - absolute determination of branching ratios via high-resolution particle spectroscopy
The determination of absolute branching ratios for high-energy states in light nuclei is an important and useful tool for probing the underlying nuclear structure of individual resonances: for example, in establishing the tendency of an excited state towards
α
-cluster structure. Difficulty arises in measuring these branching ratios due to similarities in available decay channels, such as (
18
O,
n
) and (
18
O,
2
n
), as well as differences in geometric efficiencies due to population of bound excited levels in daughter nuclei. Methods are presented using Monte Carlo techniques to overcome these issues
High-resolution measurement of the time-modulated orbital electron capture and of the decay of hydrogen-like Pm ions
The periodic time modulations, found recently in the two-body orbital
electron-capture (EC) decay of both, hydrogen-like Pr and
Pm ions, with periods near to 7s and amplitudes of about 20%,
were re-investigated for the case of Pm by using a 245 MHz
resonator cavity with a much improved sensitivity and time resolution. We
observed that the exponential EC decay is modulated with a period s, in accordance with a modulation period s as obtained
from simultaneous observations with a capacitive pick-up, employed also in the
previous experiments. The modulation amplitudes amount to and
for the 245 MHz resonator and the capacitive pick-up,
respectively. These new results corroborate for both detectors {\it exactly}
our previous findings of modulation periods near to 7s, though with {\it
distinctly smaller} amplitudes. Also the three-body decays have been
analyzed. For a supposed modulation period near to 7s we found an amplitude , compatible with and in agreement with the preliminary
result of our previous experiment. These observations could
point at weak interaction as origin of the observed 7s-modulation of the EC
decay. Furthermore, the data suggest that interference terms occur in the
two-body EC decay, although the neutrinos are not directly observed.Comment: In memoriam of Prof. Paul Kienle, 9 pages, 1 table, 5 figures Phys.
Lett. B (2013) onlin
Precision branching-ratio measurements in 18 O
Abstract: An experiment has been performed utilising the 12C(7Li,p)18O reaction to populate high-energy states in 18O. Using the Munich Q3D magnetic spectrograph in conjunction with the Birmingham large-angular-coverage DSSD array, branching ratios have been measured for over fifty states in 18O, investigating the α-decay, n-decay, 2n-decay and γ-decay branches. In tandem, Monte-Carlo techniques have been used to identify and separate features
Study of the onset of deformation and shape coexistence in Ar via the inverse kinematics () reaction
New test of modulated electron capture decay of hydrogen-like 142Pm ions: Precision measurement of purely exponential decay
An experiment addressing electron capture (EC) decay of hydrogen-like 142Pm60+ions has been conducted at the experimental storage ring (ESR) at GSI. The decay appears to be purely exponential and no modulations were observed. Decay times for about 9000 individual EC decays have been measured by applying the single-ion decay spectroscopy method. Both visually and automatically analysed data can be described by a single exponential decay with decay constants of 0.0126(7)sâ1for automatic analysis and 0.0141(7)sâ1for manual analysis. If a modulation superimposed on the exponential decay curve is assumed, the best fit gives a modulation amplitude of merely 0.019(15), which is compatible with zero and by 4.9 standard deviations smaller than in the original observation which had an amplitude of 0.23(4)