PRL

[Paper] Radii and Binding Energies in Oxygen Isotopes: A Challenge for Nuclear Forces

Radii and Binding Energies in Oxygen Isotopes: A Challenge for Nuclear Forces

V. Lapoux et al.
doi: 10.1103/PhysRevLett.117.052501

We present a systematic study of both nuclear radii and binding energies in (even) oxygen isotopes from the valley of stability to the neutron drip line. Both charge and matter radii are compared to state-of-the-art ab initio calculations along with binding energy systematics. Experimental matter radii are obtained through a complete evaluation of the available elastic proton scattering data of oxygen isotopes. We show that, in spite of a good reproduction of binding energies, ab initio calculations with conventional nuclear interactions derived within chiral effective field theory fail to provide a realistic description of charge and matter radii. A novel version of two- and three-nucleon forces leads to considerable improvement of the simultaneous description of the three observables for stable isotopes but shows deficiencies for the most neutron-rich systems. Thus, crucial challenges related to the development of nuclear interactions remain.

Jul 29, 2016 by Theo radii theory 0

[Paper] Spectroscopic Quadrupole Moments in ^96,98Sr: Evidence for Shape Coexistence in Neutron-Rich Strontium Isotopes at N=60

Spectroscopic Quadrupole Moments in Sr96,98: Evidence for Shape Coexistence in Neutron-Rich Strontium Isotopes at N=60

E. Clément et al.

doi: 10.1103/PhysRevLett.116.022701

Neutron-rich ^96,98Sr isotopes have been investigated by safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility. Reduced transition probabilities and spectroscopic quadrupole moments have been extracted from the differential Coulomb excitation cross sections. These results allow, for the first time, the drawing of definite conclusions about the shape coexistence of highly deformed prolate and spherical configurations. In particular, a very small mixing between the coexisting states is observed, contrary to other mass regions where strong mixing is present. Experimental results have been compared to beyond-mean-field calculations using the Gogny D1S interaction in a five-dimensional collective Hamiltonian formalism, which reproduce the shape change at N=60.

Jan 20, 2016 by Theo experiment quadrupole 0

[paper] Is the 7/2₁^– Isomer State of ⁴³S Spherical?

Is the 7/2₁^– Isomer State of ⁴³S Spherical?

R. Chevrier et al.

doi: 10.1103/PhysRevLett.108.162501

We report on the spectroscopic quadrupole moment measurement of the 7/2₁^– isomeric state in ⁴³₁₆S₂₇ [E^*=320.5(5) keV, T_1/2=415(3) ns], using the time dependent perturbed angular distribution technique at the RIKEN RIBF facility. Our value, ∣Q_s∣=23(3) efm², is larger than that expected for a single-particle state. Shell model calculations using the modern SDPF-U interaction for this mass region reproduce remarkably well the measured ∣Q_s∣, and show that non-negligible correlations drive the isomeric state away from a purely spherical shape.

Apr 16, 2012 by Theo g factor 0

[paper] Direct Measurement of the Proton Magnetic Moment

Direct Measurement of the Proton Magnetic Moment

J. DiSciacca and G. Gabrielse

doi: 10.1103/PhysRevLett.108.153001

The proton magnetic moment in nuclear magnetons is measured to be μ_p/μ_N≡g/2=2.792 846±0.000 007, a 2.5 parts per million uncertainty. The direct determination, using a single proton in a Penning trap, demonstrates the first method that should work as well with an antiproton (p̅ ) as with a proton (p). This opens the way to measuring the p̅ magnetic moment (whose uncertainty has essentially not been reduced for 20 years) at least 103 times more precisely.

Apr 10, 2012 by Theo g factor 0

[paper] Nuclear Charge Radii of ^21-32Mg

Nuclear Charge Radii of ^21-32Mg

D.T. Yordanov et al.

doi: 10.1103/PhysRevLett.108.042504

Charge radii of all magnesium isotopes in the sd shell have been measured, revealing evolution of the nuclear shape throughout two prominent regions of assumed deformation centered on ²⁴Mg and ³²Mg. A striking correspondence is found between the nuclear charge radius and the neutron shell structure. The importance of cluster configurations towards N=8 and collectivity near N=20 is discussed in the framework of the fermionic molecular dynamics model. These essential results have been made possible by the first application of laser-induced nuclear orientation for isotope shift measurements.

Jan 26, 2012 by Theo g factor 0

[paper] g Factor of Hydrogenlike ²⁸Si¹³⁺

g Factor of Hydrogenlike ²⁸Si¹³⁺

S. Sturm et al.

doi: 10.1103/PhysRevLett.107.023002

We determined the experimental value of the g factor of the electron bound in hydrogenlike ²⁸Si¹³⁺ by using a single ion confined in a cylindrical Penning trap. From the ratio of the ion’s cyclotron frequency and the induced spin flip frequency, we obtain g=1.995 348 958 7(5)(3)(8). It is in excellent agreement with the state-of-the-art theoretical value of 1.995 348 958 0(17), which includes QED contributions up to the two-loop level of the order of (Zα)2 and (Zα)4 and represents a stringent test of bound-state quantum electrodynamics calculations.

Jul 7, 2011 by Theo experiment g factor 0

[paper] Wigner Crystals of ²²⁹Th for Optical Excitation of the Nuclear Isomer

Wigner Crystals of ²²⁹Th for Optical Excitation of the Nuclear Isomer

C.J. Campbell et al.

doi: 10.1103/PhysRevLett.106.223001

We have produced laser-cooled Wigner crystals of ²²⁹Th³⁺ in a linear Paul trap. The magnetic dipole (A) and electric quadrupole (B) hyperfine constants for four low-lying electronic levels and the relative isotope shifts with respect to ²³²Th³⁺ for three low-lying optical transitions are measured. Using the hyperfine B constants in conjunction with prior atomic structure calculations, a new value of the spectroscopic nuclear electric quadrupole moment Q=3.11(16) eb is deduced. These results are a step towards optical excitation of the low-lying isomer level in the ²²⁹Th nucleus.

Jun 30, 2011 by Theo experiment g factor 0

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