Low-lying octupole isovector excitation in Nd-144

International audienceThe nature of low-lying 3− levels in Nd144 was investigated in the Nd143(n,γγ) cold neutron-capture reaction. The combination of the high neutron flux from the research reactor at the Institut Laue-Langevin and the high γ-ray detection efficiency of the EXILL setup allowed the recording of γγ coincidences. From the coincidence data precise branching ratios were extracted. Furthermore, the octagonal symmetry of the setup allowed angular-distribution measurements to determine multipole-mixing ratios. Additionally, in a second measurement the ultra-high resolution spectrometer GAMS6 was employed to conduct lifetime measurements using the gamma-ray induced Doppler-shift technique (GRID). The confirmed strong M1 component in the 33−→31− decay strongly supports the assignment of the 33− level at 2779keV as low-lying isovector octupole excitation. Microscopic calculations within the quasiparticle phonon model confirm an isovector component in the wave function of the 33− level, firmly establishing this fundamental mode of nuclear excitation in near-spherical nuclei

Identification of low-energy isovector octupole states in 144^{144}Nd

International audienceRecently, first candidates for low-lying isovector states in the octupole sector were suggested. The unambiguous identification of those states will contribute to the decomposition of the octupole-octupole residual interaction in an isoscalar and isovector part. This will help us understand the octupole degree of freedom. In 144Nd the 3− state at 2778 keV is a good candidate for such a "mixed-symmetry'' octupole state. In order to clarify the nature of this state, a 143Nd(n, γ)-experiment was conducted with the EXILL-setup. Following neutron capture the 3− states are populated and EXILL provides the opportunity to determine the multipole-mixing ratios of the 3i −→31 - transitions. For the transition from the "mixed-symmetry" octupole state to the symmetric 31 − state we expect a strong M1 component

Substrate-Initiated Synthesis of Cell-Penetrating Poly(disulfide)s

Lessons from surface-initiated polymerization are applied to grow cell-penetrating poly(disulfide)s directly on substrates of free choice. Reductive depolymerization after cellular uptake should then release the native substrates and minimize toxicity. In the presence of thiolated substrates, propagators containing a strained disulfide from asparagusic or, preferably, lipoic acid and a guanidinium cation polymerize into poly(disulfide)s in less than 5 min at room temperature at pH 7. Substrate-initiated polymerization of cationic poly(disulfide)s and their depolymerization with dithiothreitol causes the appearance and disappearance of transport activity in fluorogenic vesicles. The same process is further characterized by gel-permeation chromatography and fluorescence resonance energy transfer

Identification of low-energy isovector octupole states in 144

Recently, first candidates for low-lying isovector states in the octupole sector were suggested. The unambiguous identification of those states will contribute to the decomposition of the octupole-octupole residual interaction in an isoscalar and isovector part. This will help us understand the octupole degree of freedom. In 144Nd the 3− state at 2778 keV is a good candidate for such a "mixed-symmetry'' octupole state. In order to clarify the nature of this state, a 143Nd(n, γ)-experiment was conducted with the EXILL-setup. Following neutron capture the 3− states are populated and EXILL provides the opportunity to determine the multipole-mixing ratios of the 3i −→31 - transitions. For the transition from the "mixed-symmetry" octupole state to the symmetric 31 − state we expect a strong M1 component