J. Wiederhold
A5050913365- Nuclear physics research studies
- Nuclear Physics and Applications
- Atomic and Molecular Physics
- Astronomical and nuclear sciences
- Quantum Chromodynamics and Particle Interactions
- Nuclear reactor physics and engineering
- Rare-earth and actinide compounds
- Radiopharmaceutical Chemistry and Applications
- Advanced Chemical Physics Studies
- Particle physics theoretical and experimental studies
- Advanced NMR Techniques and Applications
- Particle accelerators and beam dynamics
- Radioactive contamination and transfer
- X-ray Spectroscopy and Fluorescence Analysis
- Atomic and Subatomic Physics Research
- Lanthanide and Transition Metal Complexes
- Magnetic Properties of Alloys
- Distributed and Parallel Computing Systems
- Radioactivity and Radon Measurements
- Radiation Detection and Scintillator Technologies
- Nuclear Materials and Properties
Technical University of Darmstadt
2012-2024
Saha Institute of Nuclear Physics
2024
Universitat de València
2022
Instituto de Física Corpuscular
2022
Institute for Nuclear Research and Nuclear Energy
2020
Florida State University
2019
Direct lifetime measurements via $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ coincidences using a fast timing detector array consisting of ${\mathrm{LaBr}}_{3}(\mathrm{Ce})$ scintillators has been applied to determine the low-lying states in semimagic $(N=50)$ nucleus $^{94}\mathrm{Ru}$. The experiment was carried out as first series ``FAIR-0'' experiments with DESPEC experimental setup at Facility for Antiproton and Ion Research (FAIR). Excited $^{94}\mathrm{Ru}$ were...
Lifetime measurements of low-lying excited states in the semimagic (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:mi>N</a:mi><a:mo>=</a:mo><a:mn>50</a:mn></a:mrow></a:math>) nucleus <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mmultiscripts><b:mi>Rh</b:mi><b:mprescripts/><b:none/><b:mn>95</b:mn></b:mmultiscripts></b:math> have been performed by means fast-timing technique. The experiment was carried out using <c:math...
We report on spectroscopic information and lifetime measurements of even-even neutron-rich Te isotopes. Excited states were populated in fast-neutron induced fission $^{238}\mathrm{U}$ at the ALTO facility IJCLab with LICORNE neutron source detected using hybrid $\ensuremath{\nu}$-ball spectrometer. provide first results lifetimes ${6}_{1}^{+}$ state $^{136}\mathrm{Te}$ (${6}_{1}^{+}$), (${4}_{1}^{+}$), (${2}_{1}^{+}$) $^{138}\mathrm{Te}$ discuss context large-scale shell-model calculations....
Low-lying yrast states of $^{204}\mathrm{Po}$ and $^{206}\mathrm{Po}$ were investigated by the $\ensuremath{\gamma}--\ensuremath{\gamma}$ fast timing technique with ${\mathrm{LaBr}}_{3}$(Ce) detectors. Excited these nuclei populated in $^{197}\mathrm{Au}(^{11}\mathrm{B},4n)^{204}\mathrm{Po}$ $^{198}\mathrm{Pt}(^{12}\mathrm{C},4n)^{206}\mathrm{Po}$ fusion-evaporation reactions, respectively. The beams delivered FN-Tandem accelerator at University Cologne. lifetimes ${4}_{1}^{+}$ both...
Background: Shape coexistence in the $Z\ensuremath{\approx}82$ region has been established mercury, lead, and polonium isotopes. For even-even mercury isotopes with $100\ensuremath{\le}N\ensuremath{\le}106$ multiple fingerprints of this phenomenon are observed, which seems to be no longer present for $N\ensuremath{\ge}110$. According a number theoretical calculations, shape is predicted $^{188}\mathrm{Hg}$ isotope.Purpose: The aim work was measure lifetimes excited states infer their...
The population of isomeric states in the prompt decay fission fragments---so-called yield ratios (IYRs)---is known to be sensitive angular momentum $J$ that fragment emerged with, and may therefore contain valuable information on mechanism behind process. In this work, we investigate how changes fissioning system impact measured IYRs fragments learn more about what parameters affect generation. To enable this, a new technique for measuring is first demonstrated. It based time arrival...
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Mean lifetimes of yrast states the isotopes $^{174,176,178,180}\mathrm{Hf}$ have been measured using fast-electronic scintillation timing. Excited $^{174,176,178}\mathrm{Hf}$ were populated via $\ensuremath{\beta}$ decay, while $^{180}\mathrm{Hf}$ was Coulomb excitation. The ${2}_{1}^{+}$ and ${4}_{1}^{+}$ all ${6}_{1}^{+}$ $^{174,178}\mathrm{Hf}$ measured, slope centroid shift methods. mean lifetime, $\ensuremath{\tau}({4}_{1}^{+})=85(13)\phantom{\rule{0.28em}{0ex}}\mathrm{ps}$,...
The lifetime $\ensuremath{\tau}({0}_{2}^{+})$ of $^{152}\mathrm{Gd}$ has been measured using fast electronic scintillation timing (FEST) with an array high-purity germanium (HPGe) and cerium-doped lanthanum bromide (${\mathrm{LaBr}}_{3}$) detectors. was produced via $(\ensuremath{\alpha},n)$ reaction on a gold backed $^{149}\mathrm{Sm}$ target. $\ensuremath{\tau}({0}_{2}^{+})=96(6)\phantom{\rule{4pt}{0ex}}\mathrm{ps}$ corresponds to reduced transition strength...
Prompt and delayed $\ensuremath{\gamma}$-ray spectroscopy of the neutron-rich $^{94}\mathrm{Kr}$ was performed, as part fission campaign at ALTO facility IPN Orsay, using fast-neutron-induced reaction $^{238}\mathrm{U}(n,f)$ in combination with $\ensuremath{\nu}$-Ball array, a novel hybrid $\ensuremath{\gamma}$ spectrometer for energy lifetime measurements. Several new yrast nonyrast transitions were observed first time, extending previously known level scheme. Additionally, we report on...
Isomeric states of the neutron-rich isotope 189 73 Ta 116 were populated via fragmentation a primary beam 208 Pb ions at 1 GeV/u impinging on 9 Be target GSI, Darmstadt, Germany. The isotopes interest separated, identified and delivered to DESPEC setup. Two isomers deduced in their lifetimes measured based γ-ray time distributions.
Electric quadrupole ground-state excitation strengths $B(E2)\ensuremath{\uparrow}$ of the first ${2}^{+}$ states midshell Sn isotopes were measured with nuclear resonance fluorescence method to investigate systematic disagreement between available experimental data from different techniques. Also, model calculations show conflicting trends $B(E2;{0}_{1}^{+}\ensuremath{\rightarrow}{2}_{1}^{+})$ values around $^{116}\mathrm{Sn}$. Three experiments on $^{112,116,120}\mathrm{Sn}$ carried out at...
We report on spectroscopic information and lifetime measurements in the neutron-rich $^{135,137,139}\mathrm{I}$ isotopes. This is first data iodine isotopes beyond $N=82$. Excited states were populated fast neutron-induced fission of $^{238}\mathrm{U}$ at ALTO facility IJCLab with LICORNE neutron source detected using hybrid $\ensuremath{\nu}$-ball spectrometer. The level schemes are revised terms excited up to maximum spin-parity $(33/{2}^{+})$, for time fission. provide results lifetimes...
The chain of Barium isotopes enables us to study experimentally the evolution nuclear quadrupole collectivity from shell closure at N = 82 towards neutron-deficient or neutron-rich deformed nuclei. TU Darmstadt group has investigated several nuclei stable 130,132Ba up radioactive 140,142Ba with projectile-Coulomb excitation technique including use Doppler-shift attenuation method (DSAM). Lifetimes quadrupole-collective states 132Ba and 140Ba were obtained for first time as well static...
The $E2/M1$ multipole mixing ratio of the ${1}_{\text{sc}}^{+}\ensuremath{\rightarrow}{2}_{1}^{+}\phantom{\rule{4pt}{0ex}}\ensuremath{\gamma}$-ray transition and therefore $F$-vector $E2$ decay scissors mode shape-phase transitional nucleus $^{152}\mathrm{Sm}$ have been measured with nuclear resonance fluorescence method at High-Intensity $\ensuremath{\gamma}$-ray Source ($\mathrm{HI}\ensuremath{\gamma}\mathrm{S}$). Furthermore, parity quantum numbers several dipole-excited states...
Projectile Coulomb excitation experiments were performed at HIE-ISOLDE CERN with the radioactive ion beams of 140 Nd and 142 Sm. Ions an energy 4:62 MeV/A impinging on a 1.45 mg/cm 2 thick 208 Pb target. The γ-rays depopulating Coulomb-excited states recorded by HPGe-array MINIBALL scattered particles detected double-sided silicon strip detector. Experimental intensities used for determination electromagnetic transition matrix elements. A preliminary result B(M1; + 3 → 1 ) upper limit case...
Low-lying yrast states in 204 Po and 206 have been investigated by the γ-γ fast timing technique with LaBr 3 (Ce) detectors. Excited of these nuclei were populated 197 Au( 11 B,4n) 198 Pt( 12 C,4n) fusion-evaporation reactions, respectively, at FN-Tandem Facility University Cologne. The lifetimes 4 + 1 both measured, along an upper limit for 2 state Po. preliminary results are discussed scope systematic behavior transition strengths between polonium isotopes.
The Zirconium isotopes across the N=56,58 neutron subshell closures have been of special interest since years, sparked by near doubly-magic features 96 Zr and subsequent rapid onset collectivity with a deformed ground-state structure already in 100 Zr. Recent state-of-the-art shell model approaches did not only correctly describe this shape-phase transition isotopic chain, but alsothe coexistence non-collective structures pronounced especially 96,98 Theisotope 98 is located on from...
A projectile Coulomb-excitation experiment was performed at the radioactive-ion beam facility HIE-ISOLDE CERN to obtain E2 and M1 transition matrix elements of Nd140 using multistep code gosia. The absolute strengths, B(M1;22+→21+)=0.033(8)μN2,B(M1;23+→21+)=0.26−0.10+0.11μN2, B(M1;24+→21+)<0.04μN2, identify 23+ state as main fragment one-quadrupole-phonon proton-neutron mixed-symmetry Nd140. degree F-spin mixing in quantified with determination element VF−mix<7−7+13keV.Received 7 August...
Nuclei are complex quantum objects due to nucleon-nucleon interactions. They can undergo rather rapid changes in structure as a function of nucleon number. A well known region such shape transition is the rare-earth around N = 90, where accessible nuclei range from spherical at closed neutron shell 82 deformed nuclei. For better understanding this phenomenon, it interest study empirical signatures like E2 strength or E0 excitation . The nuclide 152Gd with 88 neutrons located close phase 90....