Search results for "Nuclear Structure"
showing 10 items of 401 documents
The origin of the Ca–Ti–Cr–Fe–Ni isotopic anomalies in the inclusion EK-1-4-1 of the Allende meteorite
2003
The origin of the correlated Ca-Ti-Cr-Fe-Ni isotopic anomalies in the Ca-Al-rich inclusion of the EK-1-4-1 of the Allende is a longstanding puzzle. The search for a stellar environment which could explain the enrichment of neutron-rich stable Ca-...-Ni isotopes in a self-consistent way requires nuclear physics data far from stability. Recent experimental data have been obtained in the region of the shell closures N = 28 and N = 40, where the possible progenitors of these nuclei are found. Astrophysical network calculations have been updated by including the new beta-decay properties and microscopic predictions of neutron-capture cross sections. Interplay between nuclear structure far from s…
Elastic and inelastic LSP-nucleus scattering on medium-heavy nuclei
2010
Elastic and inelastic scattering rates of the lightest supersymmetric particle (LSP) off nuclei are derived for the stable iodine, xenon and cesium detectors. The parameters of the supersymmetric theory are decoupled from the nuclear structure. The involved nuclear wave functions are calculated in the nuclear shell model by using a realistic effective two-nucleon interaction in a realistic valence space. By using fitted nuclear gyromagnetic factors we successfully reproduce the relevant spectroscopic data in the discussed nuclei.
0+-0+transition in charged photopion reactions
1991
In the near-threshold region for the (\ensuremath{\gamma},${\mathrm{\ensuremath{\pi}}}^{\ifmmode\pm\else\textpm\fi{}}$) reaction the spin-flip (Kroll-Ruderman) term dominates most nuclear reactions. The smaller non-spin-flip term is of considerable interest because it is very sensitive to the reaction dynamics and in particular to the \ensuremath{\Delta} channel, even in the near-threshold region. We propose to study the non-spin-flip term via the ${0}^{+}$\ensuremath{\rightarrow}${0}^{+}$ transition in the $^{14}\mathrm{C}$(\ensuremath{\gamma},${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$${)}^{14}$N reaction; the cross section is shown to be insensitive to the details of nuclear …
Transfer and neutron capture reactions toIr194as a test of Uν(6/12)⊗Uπ(6/4)supersymmetry
2008
The structure of $^{194}\mathrm{Ir}$ is investigated via ($n,\ensuremath{\gamma}),(n,{e}^{\ensuremath{-}}),(d,p)$, and ($\stackrel{\ensuremath{\rightarrow}}{d},\ensuremath{\alpha}$) spectroscopy. The use of different methods leads to an almost complete level scheme up to high excitation energies including \ensuremath{\gamma}-decay and spin-parity assignments. A reanalysis of the formerly published ($n,\ensuremath{\gamma}$) data was triggered by our new ($d,p$) and ($\stackrel{\ensuremath{\rightarrow}}{d},\ensuremath{\alpha}$) transfer reactions. The experimental level scheme is compared to predictions using extended supersymmetry. Herein, the classification of states was done according to q…
Interplay of quasiparticle and phonon excitations in 181Hf observed through (n,γ) and reactions
2002
Abstract Nuclear levels of 181 Hf were investigated in the range up to 3 MeV excitation energy by (n, γ ) and (d,p) reactions. Over 170 levels and about 390 γ -transitions were established most of them for the first time. 25 rotational bands were identified. Comparison of the results of the two reactions yields information on the fine structure in the fragmentation of Nilsson strength. The states below 2 MeV with the most complete spectroscopic information were interpreted in terms of the Quasiparticle Phonon Model (QPM). Excitation energies, electromagnetic transition rates, γ -branchings and spectroscopic factors are discussed in connection with their possible structure.
Nuclear structure of 187W studied with (n,γ) and (d,p) reactions
2008
Abstract The level structure of 187 W has been studied using prompt and delayed gamma–gamma coincidences from thermal neutron capture in 186 W and also measuring the ( d , p ) reaction. From these data and those of previous studies a total of 170 levels (121 connected by γ transitions) have been established for energies below 2.35 MeV. Some of these levels have been grouped into rotational bands built on 14 intrinsic states of quasi-particle and quasi-particle plus phonon character. Of particular interest has been the identification of “quasi bands” with inverse spin sequence based on the newly established isomeric 11 / 2 + state at 410.1 keV. Although the DWBA analysis permitted definite s…
Development and applications of the IGISOL technique
2001
Abstract The development and present status of the Ion Guide Isotope Separator On-Line technique is presented. Applications to nuclear physics research include decay spectroscopy of proton- and neutron-rich nuclei of refractory elements and studies of their ground-state properties by collinear laser spectroscopy. Future developments, including ion-beam manipulations by linear RFQ and Penning traps, are discussed together with high-energy applications of the IGISOL technique.
Nuclear structure of 157Gd
2003
Abstract The energy levels of 157 Gd have been investigated using the (n, γ ) and (n, n′ γ ) reactions. As a result of the analysis of the γ -ray spectra from 16 isolated neutron resonances, a level scheme with a complete set of levels with spins J =1/2, 3/2 has been established up to 1.86 MeV excitation energy. A part of the level scheme is interpreted in more detail on the basis of Coriolis and Δ N =2 coupled Nilsson configurations. Slightly different sets of shape parameters are deduced for negative- and positive-parity levels. A large excess of unassigned 1/2 and 3/2 levels evidently requires an explanation in terms of inclusion of new additional degrees of freedom.
Out-of-plane measurements of the fifth response function of the exclusive electronuclear response
1999
The first measurements of f{sub LT}{sup '}, known as the fifth response function, have been made for the {sup 2}H(e(vector sign),e{sup '}p) and {sup 12}C(e(vector sign),e{sup '}p) reactions. This response is directly related to the imaginary part of the interference between the transverse and longitudinal nuclear electromagnetic currents. Its observation requires longitudinally polarized electron beams and out-of-plane detection, the latter made possible by the newly developed out-of-plane spectrometer system. The initial measurements were made by using a 560-MeV polarized electron beam and quasielastic kinematics at Q{sup 2}=3.3 fm{sup -2}. The development of the methodology for out-of-pla…
rp-process nucleosynthesis at extreme temperature and density conditions
1998
We present nuclear reaction network calculations to investigate the influence of nuclear structure on the rp-process between Ge and Sn in various scenarios. Due to the lack of experimental data for neutron-deficient nuclei in this region, we discuss currently available model predictions for nuclear masses and deformations as well as methods of calculating reaction rates (Hauser-Feshbach) and beta-decay rates (QRPA and shell model). In addition, we apply a valence nucleon (NpNn) correlation scheme for the prediction of masses and deformations. We also describe the calculations of 2p-capture reactions, which had not been considered before in this mass region. We find that in X-ray bursts 2p-c…