A nuclear spectroscopy experiment was conducted to study α-decay chains stemming from isotopes of flerovium (element Z=114). An upgraded TASISpec decay station was placed behind the gas-filled ...separator TASCA at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. The fusion-evaporation reactions ^{48}Ca+^{242}Pu and ^{48}Ca+^{244}Pu provided a total of 32 flerovium-candidate decay chains, of which two and eleven were firmly assigned to ^{286}Fl and ^{288}Fl, respectively. A prompt coincidence between a 9.60(1)-MeV α particle event and a 0.36(1)-MeV conversion electron marked the first observation of an excited state in an even-even isotope of the heaviest man-made elements, namely ^{282}Cn. Spectroscopy of ^{288}Fl decay chains fixed Q_{α}=10.06(1) MeV. In one case, a Q_{α}=9.46(1)-MeV decay from ^{284}Cn into ^{280}Ds was observed, with ^{280}Ds fissioning after only 518 μs. The impact of these findings, aggregated with existing data on decay chains of ^{286,288}Fl, on the size of an anticipated shell gap at proton number Z=114 is discussed in light of predictions from two beyond-mean-field calculations, which take into account triaxial deformation.
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An upgraded TASISpec setup, with the addition of a veto DSSD and the new Compex detector-germanium array, has been employed with the gas-filled recoil separator TASCA at the GSI Helmholtzzentrum für ...Schwerionenforschung Darmstadt, to study flerovium (element 114) decay chains. The detector upgrades along with development of new analytical techniques have improved the sensitivity of the TASISpec setup for measuring α-photon coincidences. These improvements have been assessed with test reactions. The reaction 48Ca+206,207Pb was used for verification of experimental parameters such as transmission to implantation DSSD and target-segment to α-decay correlations. The reaction 48Ca+natHf was used to produce several short-lived nuclei with multiple-α decay chains to investigate pile-up event deconvolution.
Lifetime measurements in
178
Pt with excited states de-exciting through
γ
-ray transitions and internal electron conversions have been performed. Ionic charges were selected by the in-flight mass ...separator MARA and measured at the focal plane in coincidence with the
4
1
+
→
2
1
+
257
keV
γ
-ray transition detected using the JUROGAM 3 spectrometer. The resulting charge-state distributions were analysed using the differential decay curve method (DDCM) framework to obtain a lifetime value of 430(20) ps for the
2
1
+
state. This work builds on a method that combines the charge plunger technique with the DDCM analysis. As an alternative analysis, ions were selected in coincidence with the
178
Pt alpha decay (
E
alpha
=
5.458
(
5
)
MeV) at the focal plane. Lifetime information was obtained by fitting a two-state Bateman equation to the decay curve with the lifetime of individual states defined by a single quadrupole moment. This yielded a lifetime value of 430(50) ps for the
2
1
+
state, and 54(6) ps for the
4
1
+
state. An analysis method based around the Bateman equation will become especially important when using the charge plunger method for the cases where utilising coincidences between prompt
γ
rays and recoils is not feasible.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Lying between 16O and 40Ca, the sd shell is well described by robust phenomenological and ab initio nuclear theories. In this work, however, we highlight an unexplained reduction in ...electric-quadrupole strength in the rare isotope 32Si, studied through sub-barrier Coulomb excitation. It is found that the oblate nature of the deformation is well reproduced, while the absolute scale of quadrupole deformation, however, is inhibited by approximately a factor of 2 compared to theoretical predictions. Through comparison with shell-model and ab initio calculations, we present a number of possible explanations for this inhibited E2 strength. By comparing the results of these calculations to multiple observables, we conclude that there is a reduced role for out-of-space excitations in 32Si, resulting in a reduction in the corrections normally applied to both models.
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Oxidative modification of lipoproteins is believed to be important in the genesis of atherosclerosis. We established cultures of smooth muscle cells (SMC) and exposed them to native LDL or oxidized ...LDL. Oxidized LDL, but not native LDL, was mitogenic as measured by incorporation of 3H-thymidine into DNA. This effect was concentration dependent, averaged 288% of control, and was blocked by a platelet-activating factor (PAF) receptor antagonist. We hypothesized that phospholipids with PAF-like activity were generated during the oxidation of LDL. To test this hypothesis we extracted phospholipids from copper-oxidized LDL and assayed for PAF-like activity. Phospholipids extracted from oxidized LDL and purified by HPLC induced neutrophil adhesion equivalent to PAF (10 nM) and were mitogenic for smooth muscle cells. These effects were not seen with phospholipids extracted from native LDL and were blocked by two structurally different, competitive antagonists of the PAF receptor. The effects of these lipids were also abolished by pretreating them with PAF acetylhydrolase. Finally, we used Chinese hamster ovary cells that had seen stably transfected with a cDNA for the PAF receptor to confirm that phospholipids from oxidized LDL act via this receptor. We found that PAF (control) and the oxidized phospholipids each induced release of arachidonic acid from the transfected cells, but had no effect on wildtype Chinese hamster ovary cells, which lack the PAF receptor. This effect was also blocked by a PAF receptor antagonist. Thus, phospholipids generated during oxidative modification of LDL may participate in atherosclerosis by stimulating SMC proliferation and leukocyte activation.
The neutron-rich strontium, zirconium and molybdenum nuclei have been observed to undergo a dramatic evolution, becoming strongly deformed around N = 60, sometimes interpreted as a quantum phase ...transition between “normal” and intruder configurations. Key to understanding this evolution is to understand the configurations in isolation, in regions where interference can be neglected. A deformed coexisting configuration is inferred from the presence of a $0$$^{+}_{2}$ state which decreases in excitation energy with increasing neutron number, becoming the first-excited state at 98Mo. We present here the results of a low-energy Coulomb-excitation measurement of the nucleus 96Mo, extracting B(E2) values and quadrupole moments. It is found that, while the B(E2) values agree with those found in the literature, there is a significant disagreement with literature spectroscopic quadrupole moments. The results are compared with shell-model calculations using a 88Sr core with good agreement found, likely indicating that intruder structures do not significantly impact the ground-state structure, in contrast with the heavier molybdenum isotopes.
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8.
Coulomb excitation of Mo 96 Russell, R.; Heery, J.; Henderson, J. ...
Physical review. C,
12/2023, Volume:
108, Issue:
6
Journal Article
Peer reviewed
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Maximal ground-state deformation should occur when both proton and neutron Fermi surfaces are located at midshell. However, subshell gaps that stabilize large deformation can exist at proton or ...neutron values other than midshell. One such gap may occur at Z = 60 in the rare-earth region, as the energy of the first 2+ states in even-even nuclei are often lowest in an isotonic chain for neodymium (Z = 60) rather than the midshell isotopes of dysprosium (Z = 66). Further evidence of this deformed gap has now been observed by investigating the signature splitting systematics of the νi13/2 bands found in the odd-N, rare-earth nuclei. Furthermore, these were aided by the present observation of the νi13/2 band in 159Gd and the confirmation of the same structure in 155Sm via the transfer of a neutron from a 160Gd beam to a 154Sm target.
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