Search results for "Excitation"
showing 10 items of 1290 documents
Identification of sub- μs isomeric states in the odd-odd nucleus Au178
2021
The neutron-deficient gold (Z=79) isotopes in the vicinity of the neutron midshell N=104 provide prolific examples of shape coexistence and isomerism at low excitation energy. They can be probed via a number of different experimental techniques. In this study, two new isomeric states with half-lives of 294(7) and 373(9) ns have been observed in the neutron-deficient odd-odd nuclide Au178 (N=99) in an experiment at the RITU gas-filled separator at JYFL, Jyvaskyla. This result was achieved due to the use of a segmented planar germanium detector with a high efficiency at low energies. By applying the recoil-decay tagging technique, they were assigned to decay to two different long-lived α-deca…
Experimental Setup with Chaotic and Periodic Excitations for Cell Growth Studies
2020
The paper presents circuits used for excitation living cells to increase their growth rate. The main novelty is the proposal of using chaotic oscillations for the electromagnetic excitation. The research is in a preliminary phase and no conclusions have been yet derived for applications in biotechnology.
Investigation of the reaction 64Ni+238U being an option of synthesizing element 120
2010
This study is concerned with the search for entrance channels suitable to synthesize elements with Z > 118. Mass-energy distributions as well as capture cross-sections of fission-like fragments have been measured for the reactions 64Ni + 238U → 302120 and 48Ca + 238U → 286112 at energies near the Coulomb barrier. Compound nucleus fission cross-sections were estimated from the analysis of mass and total kinetic energy distributions. The cross-section drops three orders of magnitude for the formation of the compound nucleus with Z = 120 obtained in the reaction 64Ni + 238U compared to the formation of the compound nucleus with Z = 112 obtained in the reaction 48Ca + 238U at an excitation ener…
Subharmonic excitation of the eigenmodes of charged particles in a Penning trap
2004
When parametrically excited, a harmonic system reveals a nonlinear dynamical behaviour which is common to non-deterministic phenomena. The ion motion in a Penning trap -- which can be regarded as a system of harmonic oscillators -- offers the possibility to study anharmonic characteristics when perturbed by an external periodical driving force. In our experiment we excited an electron cloud stored in a Penning trap by applying an additional quadrupole r.f. field to the endcaps. We observed phenomena such as individual and center-of-mass oscillations of an electron cloud and fractional frequencies, so-called subharmonics, to the axial oscillation. The latter show a characteristic threshold b…
Electric-field-induced Raman scattering in GaAs: Franz-Keldysh oscillations
1995
We have studied the influence of strong electric fields on the Raman scattering intensity from LO phonons in GaAs (100) at room temperature using laser excitation energies above the fundamental ${\mathit{E}}_{0}$ gap. Striking oscillations are found in the scattering intensity for configurations where either the deformation potential or Fr\"ohlich electron-phonon interaction contribute. The oscillations in the deformation-potential-mediated scattering intensity can be related to Franz-Keldysh oscillations derived from the ${\mathit{E}}_{0}$ gap, whereas a more complicated mechanism has to be invoked for processes where Fr\"ohlich interaction is responsible.
Exploring the stability of super heavy elements: First Measurement of the Fission Barrier of $^{254} $No
2013
The gamma-ray multiplicity and total energy emitted by the heavy nucleus 254No have been measured at 2 different beam energies. From these measurements, the initial distributions of spin I and excitation energy E * of 254No were constructed. The distributions display a saturation in excitation energy, which allows a direct determination of the fission barrier. 254No is the heaviest shell-stabilized nucleus with a measured fission barrier. © Owned by the authors, published by EDP Sciences, 2014.
Cluster rotational bands in 11B
2016
Differential cross-sections of 11B+α inelastic scattering at E(α) = 65 MeV leading to most of the known 11B states at excitation energies up to 14 MeV were measured [1]. The data analysis was done using Modified diffraction model (MDM) [2] allowing determining radii of excited states. Radii of the states with excitation energies less than ∼ 7 MeV coincide with the radius of the ground state with an accuracy not less than 0.1 - 0.15 fm. This result is consistent with traditional view on shell structure of low-lying states in 11B. Most of the observed high-energy excited states are distributed among four rotational bands. Moments of inertia of band states are close to the moment of inertia of…
Excited states in the proton-unbound nuclide Ta-158
2016
Excited states in the neutron-deficient odd-odd proton-unbound nuclide $^{158}\mathrm{Ta}$ have been investigated in two separate experiments. In the first experiment, $^{166}\mathrm{Ir}$ nuclei were produced in the reactions of 380 MeV $^{78}\mathrm{Kr}$ ions with an isotopically enriched $^{92}\mathrm{Mo}$ target. The $\ensuremath{\alpha}$-decay chain of the ${9}^{+}$ state in $^{166}\mathrm{Ir}$ was analyzed. Fine structure in the $\ensuremath{\alpha}$ decay of the ${9}^{+}$ state in $^{162}\mathrm{Re}$ established a 66 keV difference in excitation energy between the lowest-lying ${9}^{+}$ and ${10}^{+}$ states in $^{158}\mathrm{Ta}$. Higher-lying states in $^{158}\mathrm{Ta}$ were popul…
Verhulst model with Lévy white noise excitation
2008
The transient dynamics of the Verhulst model perturbed by arbitrary non-Gaussian white noise is investigated. Based on the infinitely divisible distribution of the Levy process we study the nonlinear relaxation of the population density for three cases of white non-Gaussian noise: (i) shot noise, (ii) noise with a probability density of increments expressed in terms of Gamma function, and (iii) Cauchy stable noise. We obtain exact results for the probability distribution of the population density in all cases, and for Cauchy stable noise the exact expression of the nonlinear relaxation time is derived. Moreover starting from an initial delta function distribution, we find a transition induc…
Acceptor Concentration Dependence of Förster Resonance Energy Transfer Dynamics in Dye–Quantum Dot Complexes
2014
The dynamics of the photoinduced Forster resonance energy transfer (FRET) in a perylene diimide–quantum dot organic–inorganic hybrid system has been investigated by femtosecond time-resolved absorption spectroscopy. The bidentate binding of the dye acceptor molecules to the surface of CdSe/CdS/ZnS multishell quantum dots provides a well-defined dye-QD geometry for which the efficiency of the energy transfer reaction can be easily tuned by the acceptor concentration. In the experiments, the spectral characteristics of the chosen FRET pair facilitate a selective photoexcitation of the quantum dot donor. Moreover, the acceptor related transient absorption change that occurs solely after energy…