839 research outputs found
Microscopic approach to large-amplitude deformation dynamics with local QRPA inertial masses
We have developed a new method for determining microscopically the
fivedimensional quadrupole collective Hamiltonian, on the basis of the
adiabatic self-consistent collective coordinate method. This method consists of
the constrained Hartree-Fock-Bogoliubov (HFB) equation and the local QRPA
(LQRPA) equations, which are an extension of the usual QRPA (quasiparticle
random phase approximation) to non-HFB-equilibrium points, on top of the CHFB
states. One of the advantages of our method is that the inertial functions
calculated with this method contain the contributions of the time-odd
components of the mean field, which are ignored in the widely-used cranking
formula. We illustrate usefulness of our method by applying to oblate-prolate
shape coexistence in 72Kr and shape phase transition in neutron-rich Cr
isotopes around N=40.Comment: 6pages, talk given at Rutherford Centennial Conference on Nuclear
Physics, 8 - 12 August 2011, The University of Mancheste
Coulomb and nuclear breakup of a halo nucleus 11Be
Breakup reactions of the one-neutron halo nucleus 11Be on Pb and C targets at
about 70 MeV/u have been investigated by measuring the momentum vectors of the
incident 11Be, outgoing 10Be, and neutron in coincidence. The relative energy
spectra as well as the angular distributions of the 10Be+n center of mass have
been extracted for both targets. For the breakup on Pb target, the selection of
forward scattering angles is found to be effective to extract almost purely the
first-order E1 Coulomb breakup component, and to exclude the nuclear
contribution and higher-order Coulomb breakup components. This angle-selected
energy spectrum is thus used to deduce the spectroscopic factor for the
10Be(0+) 2s_1/2 configuration in 11Be which is found to be 0.72+-0.04 with
B(E1) up to Ex=4 MeV of 1.05+-0.06 e2fm2. The energy weighted E1 strength up to
Ex=4 MeV explains 70+-10% of the cluster sum rule, consistent with the obtained
spectroscopic factor. The non-energy weighted sum rule is used to extract the
root mean square distance of the halo neutron to be 5.77(16) fm, consistent
with previously known values. In the breakup with C target, we have observed
the excitations to the known unbound states in 11Be at Ex=1.78 MeV and 3.41
MeV. Angular distributions for these states show the diffraction pattern
characteristic of L=2 transitions, resulting in J^pi =(3/2,5/2)+ assignment for
these states. We finally find that even for the C target the E1 Coulomb direct
breakup mechanism becomes dominant at very forward angles.Comment: 14 pages, 7 figures, accepted for publication on Physical Review
Projectile fragmentation reactions and production of nuclei near the neutron drip-line
The reaction mechanism of projectile fragmentation at intermediate energies
has been investigated observing the target dependence of the production cross
sections of very neutron-rich nuclei. Measurement of longitudinal momentum
distributions of projectile-like fragments within a wide range of fragment mass
and its charge was performed using a hundred-MeV/n Ar beam incident on
Be and Ta targets. By measurement of fragment momentum distribution, a
parabolic mass dependence of momentum peak shift was observed in the results of
both targets, and a phenomenon of light-fragment acceleration was found only in
the Be-target data. The analysis of production cross sections revealed an
obvious enhancement of the target dependence except target size effect when the
neutron excess is increased. This result implies the breakdown of factorization
(BOF) of production cross sections for very neutron-rich nuclei near the drip
line.Comment: 16 pages, 18 figures, submitted to Phys. Rev.
Responsive glyco-poly(2-oxazoline)s: synthesis, cloud point tuning, and lectin binding
A new sugar-substituted 2-oxazoline monomer was prepared using the copper-catalyzed alkyne-azide cycloaddition (CuAAC) reaction. Its copolymerization with 2-ethyl-2-oxazoline as well as 2-(dec-9-enyl)-2-oxazoline, yielding well-defined copolymers with the possibility to tune the properties by thiol-ene "click" reactions, is described. Extensive solubility studies on the corresponding glycocopolymers demonstrated that the lower critical solution temperature behavior and pH-responsiveness of these copolymers can be adjusted in water and phosphate-buffered saline (PBS) depending on the choice of the thiol. By conjugation of 2,3,4,6-tetra-O-acetyl-1-thio-beta-D-glucopyranose and subsequent deprotection of the sugar moieties, the hydrophilicity of the copolymer could be increased significantly, allowing a cloud-point tuning in the physiological range. Furthermore, the binding capability of the glycosylated copoly(2-oxazoline) to concanavalin A was investigated
Investigating neutron-proton pairing in sd -shell nuclei via (p, He 3) and (He 3,p) transfer reactions
Neutron-proton pairing correlations are investigated in detail via np transfer reactions in N = Z sd-shell
nuclei. In particular, we study the cross-section ratio of the lowest 0+ and 1+ states as an observable to
quantify the interplay between T = 0 (isoscalar) and T = 1 (isovector) pairing strengths. The experimental
results are compared to second-order distorted-wave Born approximation calculations with proton-neutron
amplitudes obtained in the shell-model formalism using the universal sd-shell interaction B. Our results suggest
underestimation of the nonneglible isoscalar pairing strength in the shell-model descriptions at the expense of
the isovector channel.Séptimo Programa Marco de la Comisión Europea-FP7/2007-2013 00376National Science Foundation (NSF) de los Estados Unidos-PHY-1404442US Department of Energy, Office of Science, Office of Nuclear Physics-DE-AC02-05CH1123
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