From Calcium to Cadmium: Testing the Pairing Functional through Charge Radii Measurements of 100−130Cd

Differences in mean-square nuclear charge radii of 100–130Cd are extracted from high-resolution collinear laser spectroscopy of the 5s 2S1/2→5p 2P3/2 transition of the ion and from the 5s5p3P2→5s6s3S1 transition in atomic Cd. The radii show a smooth parabolic behavior on top of a linear trend and a regular odd-even staggering across the almost complete sdgh shell. They serve as a first test for a recently established new Fayans functional and show a remarkably good agreement in the trend as well as in the total nuclear charge radius

<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>β</mml:mi></mml:math> -delayed neutron emissions from <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>N</mml:mi><mml:mo>&gt;</mml:mo><mml:mn>50</mml:mn></mml:mrow></mml:math> gallium isotopes

β-delayed γ-neutron spectroscopy has been performed on the decay of A=84 to 87 gallium isotopes at the RI-beam Factory at the RIKEN Nishina Center using a high-efficiency array of He3 neutron counters (BRIKEN). β-2n-γ events were measured in the decays of all of the four isotopes for the first time, which is direct evidence for populating the excited states of two-neutron daughter nuclei. Detailed decay schemes with the γ branching ratios were obtained for these isotopes, and the neutron emission probabilities (Pxn) were updated from the previous study. Hauser-Feshbach statistical model calculations were performed to understand the experimental branching ratios. We found that the P1n and P2n values are sensitive to the nuclear level densities of 1n daughter nuclei and showed that the statistical model reproduced the P2n/P1n ratio better when experimental levels plus shell-model level densities fit by the Gilbert-Cameron formula were used as the level-density input. We also showed the neutron and γ branching ratios are sensitive to the ground-state spin of the parent nucleus. Our statistical model analysis suggested J≤3 for the unknown ground-state spin of the odd-odd nucleus Ga86, from the Iγ(4+→2+)/Iγ(2+→0+) ratio of Ga84 and the P2n/P1n ratio. These results show the necessity of detailed understanding of the decay scheme, including data from neutron spectroscopy, in addition to γ measurements of the multineutron emitters

Nuclear charge radii of potassium isotopes beyond N = 28

We report on the measurement of optical isotope shifts for 38,39,42,44,46–51K relative to 47K from which changes in the nuclear mean square charge radii across the N = 28 shell closure are deduced. The investigation was carried out by bunched-beam collinear laser spectroscopy at the CERN-ISOLDE radioactive ion-beam facility. Mean square charge radii are now known from 37K to 51K, covering all νf7/2-shell as well as all νp3/2-shell nuclei. These measurements, in conjunction with those of Ca, Cr, Mn and Fe, provide a first insight into the Z dependence of the evolution of nuclear size above the shell closure at N = 28.publisher: Elsevier articletitle: Nuclear charge radii of potassium isotopes beyond journaltitle: Physics Letters B articlelink: http://dx.doi.org/10.1016/j.physletb.2014.02.012 content_type: article copyright: Copyright © 2014 The Authors. Published by Elsevier B.V.status: publishe

Spins and Magnetic Moments of 49K and 51K: Establishing the 1/2+ and 3/2+ Level Ordering Beyond N=28

The ground-state spins and magnetic moments of 49,51K have been measured using bunched-beam high-resolution collinear laser spectroscopy at ISOLDE CERN. For 49K a ground-state spin I=1/2 was firmly established. The observed hyperfine structure of 51K requires a spin I>1/2 and strongly suggests I=3/2. From its magnetic moment mm(51K)=0,5129(22)mN a spin-parity I=3/2+ with a dominant 1d1 3=2 hole configuration was deduced. This establishes for the first time the reinversion of the single-particle levels and illustrates the prominent role of the residual monopole interaction for single-particle levels and shell evolution.5 pages, 3 figuresstatus: publishe

Shell structure of potassium isotopes deduced from their magnetic moments

Background: Ground-state spins and magnetic moments are sensitive to the nuclear wave function, thus they are powerful probes to study the nuclear structure of isotopes far from stability. Purpose: Extend our knowledge about the evolution of the 1/2+ and 3/2+ states for K isotopes beyond the N=28 shell gap. Method: High-resolution collinear laser spectroscopy on bunched atomic beams. Results: From measured hyperfine structure spectra of K isotopes, nuclear spins, and magnetic moments of the ground states were obtained for isotopes from N=19 up to N=32. In order to draw conclusions about the composition of the wave functions and the occupation of the levels, the experimental data were compared to shell-model calculations using SDPF-NR and SDPF-U effective interactions. In addition, a detailed discussion about the evolution of the gap between proton 1d3/2 and 2s1/2 in the shell model and ab initio framework is also presented. Conclusions: The dominant component of the wave function for the odd-A isotopes up to K45 is a π1d3/2-1 hole. For K47,49, the main component originates from a π2s1/2-1 hole configuration and it inverts back to the π1d3/2-1 in K51. For all even-A isotopes, the dominant configuration arises from a π1d3/2-1 hole coupled to a neutron in the ν1f7/2 or ν2p3/2 orbitals. Only for K48, a significant amount of mixing with π2s1/2-1 - ν(pf) is observed leading to a Iπ=1- ground state. For K50, the ground-state spin-parity is 0- with leading configuration π1d3/2-1 - ν2p3/2-1

Beta decay of the proton-f5/2 ground state of 77Cu studied with 255 MeV and 0.2 MeV purified radioactive beams

Isobarically purified beams of 77Cu with energies of 225 and 0.2 MeV were used at the Holifield Radioactive Ion Beam Facility of Oak Ridge National Laboratory to study beta decay into states in 77Zn. Data taken at 225 MeV allowed the determination of absolute branching ratios relative to the decay of 77Cu for this beta decay as well as its daughters. From these we obtained a refined beta-delayed neutron emission probability of 30.3(22)% and a probability that the decay proceeds through 77Zn(g) of 49.1(26)%. A total of 64 gamma rays were placed in a level scheme for 77Zn containing 35 excited states including one state above the neutron separation energy, whereas two gamma rays were observed for the βn branch to states in 76Zn. The growth and decay curves of some prominent gamma rays indicate a single beta-decaying state with a half-life of 480(9) ms. The decay pattern for 77Cu, with observed feeding of 8(3)% to 7/2+ 77Zn(g) and 6(3)% to 1/2− 77Zn(m), in contrast to the large feeding observed for decay of proton-p3/2 73Cu(g) to 1/2− 73Zn(g), strongly suggests a proton-f5/2 ground state for the studied 77Cu activity.status: publishe