A first γ -ray study of Cl47,49 spectroscopy was performed at the Radioactive Isotope Beam Factory with Ar50 projectiles at 217 MeV/nucleon, impinging on the liquid hydrogen target of the MINOS ...device. Prompt deexcitation γ rays were measured with the NaI(Tl) array DALI2 + . Through the one-proton knockout reaction Ar50(p,2p) , a spin assignment could be determined for the low-lying states of Cl49 from the momentum distribution obtained with the SAMURAI spectrometer. A spin-parity Jπ=3/2+ is deduced for the ground state of Cl49 , similar to the recently studied N=32 isotope K 51 . The evolution of the energy difference E(1/21+)-E(3/21+) is compared to state-of-the-art theoretical predictions.
The very proton-rich
71
Kr isotope was produced through the in-flight fragmentation of
78
Kr on a beryllium target at RIKEN – Nishina Center in order to study its β-decay properties. A stack of ...double-sided silicon strip detectors, called WAS3ABi, was used as the decay station, where the detection of ion implants, β-decays and β-delayed protons took place. Beta-delayed γ-rays were measured using a system of 84 HPGe detectors, called EURICA, surrounding the decay station. The main goal of the present study was the precise measurement of the half-life of
71
Kr, as in the literature there is an almost 10 σ difference between the most precise independent results. Implant–β time correlations, implant–proton time correlations and implant–β–γ time correlations were all used to derive the half-life value, followed by a thorough investigation of systematic uncertainties for each method. As these values were found to be consistent, the weighted average
t
1
/
2
= 94.40
+19
ms is reported as a new half-life value in this work. Furthermore a total of 26 previously unreported γ following the β-decay of
71
Kr were also identified in the analysis.
The cluster structure of the neutron-rich isotope ^{10}Be has been probed via the (p,pα) reaction at 150 MeV/nucleon in inverse kinematics and in quasifree conditions. The populated states of ^{6}He ...residues were investigated through missing mass spectroscopy. The triple differential cross section for the ground-state transition was extracted for quasifree angle pairs (θ_{p},θ_{α}) and compared to distorted-wave impulse approximation reaction calculations performed in a microscopic framework using successively the Tohsaki-Horiuchi-Schuck-Röpke product wave function and the wave function deduced from antisymmetrized molecular dynamics calculations. The remarkable agreement between calculated and measured cross sections in both shape and magnitude validates the molecular structure description of the ^{10}Be ground-state, configured as an α-α core with two valence neutrons occupying π-type molecular orbitals.
The β-decay half-lives of 94 neutron-rich nuclei 144 $-$ 151Cs, 146 $-$ 154Ba, 148 $-$ 156La, 150 $-$ 158Ce, 153 $-$160Pr, 156 $-$ 162 Nd, 159 $-$ 163Pm, 160 $-$ 166Sm, 161 $-$ 168Eu , 165 $-$ 170Gd, ...166 $-$ 172Tb, 169 $-$ 173Dy, 172 $-$ 175Ho, and two isomeric states 174 mEr, 172 mDy were measured at the Radioactive Isotope Beam Factory, providing a new experimental basis to test theoretical models. Strikingly large drops of β -decay half-lives are observed at neutron-number N = 97 for 58Ce, 59Pr, 60Nd , and 62Sm, and N = 105 for 63Eu, 64Gd, 65Tb, and 66Dy. Features in the data mirror the interplay between pairing effects and microscopic structure. In conclusion, $r$-process network calculations performed for a range of mass models and astrophysical conditions show that the 57 half-lives measured for the first time play an important role in shaping the abundance pattern of rare-earth elements in the solar system.
Within the SEASTAR III campaign at the Radioactive Isotope Beam Factory, at the RIKEN Nishina Center, neutron-rich isotopes in the vicinity of 53K were produced from the fragmentation of the primary ...70Zn beam on a 9Be target. After nucleon knockout reactions on the secondary liquid hydrogen MINOS target the known γ rays of the neutron-rich 55Sc isotope were observed (shown in this proceedings) and γ rays from 57,59Sc isotopes have been identified for the first time. The evolution of the occupied nucleon orbitals of these nuclei in the ground and excited state is investigated under the prism of the tensor force.
The one-neutron knockout from ^{52}Ca in inverse kinematics onto a proton target was performed at ∼230 MeV/nucleon combined with prompt γ spectroscopy. Exclusive quasifree scattering cross sections ...to bound states in ^{51}Ca and the momentum distributions corresponding to the removal of 1f_{7/2} and 2p_{3/2} neutrons were measured. The cross sections, interpreted within the distorted-wave impulse approximation reaction framework, are consistent with a shell closure at the neutron number N=32, found as strong as at N=28 and N=34 in Ca isotopes from the same observables. The analysis of the momentum distributions leads to a difference of the root-mean-square radii of the neutron 1f_{7/2} and 2p_{3/2} orbitals of 0.61(23) fm, in agreement with the modified-shell-model prediction of 0.7 fm suggesting that the large root-mean-square radius of the 2p_{3/2} orbital in neutron-rich Ca isotopes is responsible for the unexpected linear increase of the charge radius with the neutron number.
In the summer of 2016 we carried out an experiment on 6He - proton elastic scattering at RIKEN, RIBF at 200 MeV/nucleon to probe 6He spin-orbit potential. Investigating change of spin-orbit ...interaction with unstable neutron-rich nuclei is of real physical interest as it is well known that spin-orbit coupling plays an important role in nuclear structure and reactions. The data obtained from this experiment should help us to understand how an exotic structure of the neutron-rich nucleus affects spin-orbit coupling in proton-nucleus scattering. Specifically, to investigate relation between diffuse nuclear density distribution in neutron-rich 6He and predicted weakening of spin-orbit coupling.In this presentation current status of data analysis will be presented. Preliminary result on obtained p-6He elastic scattering cross-section will be given.
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