Search results for "Quadrupole"
showing 10 items of 460 documents
Lifetime Measurements of Excited States in Pt172 and the Variation of Quadrupole Transition Strength with Angular Momentum
2018
Lifetimes of the first excited 2(+) and 4(+) states in the extremely neutron -deficient nuclide Pt-172 have been measured for the first time using the recoil-distance Doppler shift and recoil-decay tagging techniques. An unusually low value of the ratio B(E2: 4(1)(+) -> 2(1)(+)/B(E2: 2(1)(+) -> 0(gs)(+)) = 0.55(19) was found, similar to a handful of other such anomalous cases observed in the entire Segre chart. The observation adds to a cluster of a few extremely neutron -deficient nuclides of the heavy transition metals with neutron numbers N approximate to 90-94 featuring the effect. No theoretical model calculations reported to date have been able to explain the anomalously low B(E2: 4(1…
Shape ofAr44: Onset of deformation in neutron-rich nuclei nearCa48
2009
The development of deformation and shape coexistence in the vicinity of doubly magic $^{48}\mathrm{Ca}$, related to the weakening of the $N=28$ shell closure, was addressed in a low-energy Coulomb excitation experiment using a radioactive $^{44}\mathrm{Ar}$ beam from the SPIRAL facility at GANIL. The ${2}_{1}^{+}$ and ${2}_{2}^{+}$ states in $^{44}\mathrm{Ar}$ were excited on $^{208}\mathrm{Pb}$ and $^{109}\mathrm{Ag}$ targets at two different beam energies. $B(E2)$ values between all observed states and the spectroscopic quadrupole moment of the ${2}_{1}^{+}$ state were extracted from the differential Coulomb excitation cross sections, indicating a prolate shape of the $^{44}\mathrm{Ar}$ n…
Proposal for a permanent magnet system with a constant gradient mechanically adjustable in direction and strength
2016
A design for a permanent magnet system is proposed that generates spatially homogeneous, constant magnetic field gradients, thus creating conditions suitable for MRI without gradient coils and amplifiers. This is achieved by superimposing a weak Halbach quadrupole on a strong Halbach dipole. Rotation of either the quadrupole or the entire magnet assembly can be used to generate two-dimensional images via filtered backprojection. Additionally, the mutual rotation of two quadrupoles can be used to scale the resulting gradient. If both gradients have identical strength the gradient can even be made to vanish. The concept is demonstrated by analytical considerations and FEM simulations. However…
Progress in Atomic Physics Experiments on Nuclear Properties
1992
The measurement of nuclear properties by atomic physics methods has influenced a great deal of our present understanding of the nuclear structure. This started from the discovery of the nuclear spin and magnetic moment, the observation of isotope shifts related to nuclear radii, and the resolution of quadrupole interaction effects in the hyperfine structures. The invention and improvement of many spectroscopic techniques has led to a comprehensive knowledge of the electromagnetic ground-state properties of all stable and many radioactive nuclides. On the other hand, the atomic and thus the nuclear masses of stable isotopes were determined very precisely by electromagnetic mass spectrometry.…
Measurement of Long-Range Angular Correlation and Quadrupole Anisotropy of Pions and (Anti)Protons in Centrald+AuCollisions atsNN=200GeV
2015
We present azimuthal angular correlations between charged hadrons and energy deposited in calorimeter towers in central d+Au and minimum bias p+p collisions at sqrt[s_{NN}]=200 GeV. The charged hadron is measured at midrapidity |η| 2.75 is observed in d+Au collisions. Using the event plane method applied to the Au-going energy distribution, we extract the anisotropy strength v_{2} for inclusive charged hadrons at midrapidity up to p_{T}=4.5 GeV/c. We also present the measurement of v_{2} for identified π^{±} and (anti)protons in central d+Au collisions, and observe a mass-ordering pattern similar to that seen in heavy-ion collisions. These results are compared with viscous hydrodynamic calc…
New Information on Nuclear Structure in the Cd-In-Sn Region from Laser Spectroscopy and the Question of Core Polarization Contribution to Nuclear Rad…
1986
Nuclear spin, moments and isotope shifts of charge radii have been measured by laser spectroscopy for about 70 nuclear states in the range 48 ≦ Z ≦ 50, 54 ≦ N ≦ 78. 1/2--states in heavy In-isotopes cross the Schmidt line, indicating complex nuclear structure. Magnetic as well as spectroscopic quadrupole moments of most of the odd odd In-isotopes can be reproduced satisfactorily by coupling the respective experimental moments of odd even and even odd neighbouring nuclei. The isotope shift of all three elements exhibits a parabolic shape, which is superimposed to the almost linear droplet model expectation. The shape can be fitted quantitatively to Talmis core polarization model. The curvatur…
Isomers and high-spin structures in the N=81 isotones Xe135 and Ba137
2017
The high-spin structures of the N = 81 isotones 135Xe and 137Ba are investigated after multinucleontransfer (MNT) and fusion-evaporation reactions. Both nuclei are populated in (i) 136Xe+238U and (ii) 136Xe+208Pb MNT reactions employing the high-resolution Advanced Gamma Tracking Array (AGATA) coupled to the magnetic spectrometer PRISMA, (iii), in the 136Xe+198Pt MNT reaction employing the -ray array GAMMASPHERE in combination with the gas detector array Chico, and (iv) via a 11B+130Te fusion-evaporation reaction. The high-spin level schemes of 135Xe and 137Ba are considerably extended to higher energies. The 2058-keV (19=2 ) state in 135Xe is identified as an isomer, completing the systema…
Monte Carlo investigation of a model for a three-dimensional orientational glass with short-range gaussian interaction
1987
The analogue of the Edwards-Anderson model for isotropic vector spin glasses, but taking quadrupoles instead of unit vectors at each lattice site of the considered simple cubic lattice, is studied as a model for an orientational glass. We study both the case where the quadrupole moment can orient in a three-dimensional space (m=3) and the case where the orientation is restricted to a plane (m=2), but otherwise the Hamiltonian is fully isotropic. ℋ= $$ - \sum\limits_{\left\langle {i,j} \right\rangle } {J_{ij} } \left[ {\left( {\sum\limits_{\mu = 1}^m {S_i^\mu S_j^\mu } } \right)^2 - \frac{1}{m}} \right]$$ , whereJ ij is a random gaussian interaction between nearest neighbors, andS i μ the μ'…
Single-Particle Excitations and Collective Vibrational Modes in 96Zr
1988
New results from (n,n’γ) and (p,p’γ) reactions, as well as from β- decay confirm the double subshell closure in 96Zr and provide a detailed level scheme for this nucleus. The 1750 keV first 2+ state is described as a neutron particle-hole excitation, while the positive-parity band built on the 1582 keV excited 0+ state is characterised by quadrupole vibrational collectivity at low spins. Candidates for two-phonon octupole, quadrupole-octupole and higher multipole states are suggested on the basis of fast El and E2 decays to the 3- octupole state. The recently observed large octupole strength, its inverse relationship with the filling of the νlh11/2 orbital, and the onset of quadrupole defor…
Superdeformation in the Doubly Magic NucleusC2040a20
2001
A rotational band with seven gamma -ray transitions between states with spin 2 (h) over bar and 16 (h) over bar has been observed in the doubly magic, self-conjugate nucleus Ca-40(20)20. The measured transition quadrupole moment of 1.80(-0.29)(+0.39)eb indicates a superdeformed shape with a deformation beta (2) = 0.59(-0.07)(+0.11). The features of this band are explained by cranked relativistic mean field calculations to arise from an 8-particle 8-hole excitation.