C.-B. Moon

Experimental study of 8He + p elastic and inelastic scattering

Abstract An experimental study of 8He + p elastic scattering and a search for 8He∗ as observed in two independent experimental methods. The obtained parameters of the excited state are E 8 He ∗ = 3.57±0.12 MeV , Γ =0.5±0.35 MeV, Γ 4 He+4n /Γ 6 He+n+n ⩽ 5% . Angular distributions for elastic and inelastic scattering are measured. The inelastic angular distribution is consistent with Jπ = 2+ for 8He3.55∗.

Measurements of 11Li+p and 9Li+p elastic scatterings at 60 MeV

Abstract Proton elastic scatterings of neutron rich nuclei 9 Li and 11 Li have been measured for the first time at E lab / A =60 and 62 MeV, respectively, under the inverse kinematical conditions. While the angular distribution of 9 Li scattering follows the systematic trend from those of 6 Li and 7 Li scatterings, the 11 Li cross section is smaller by about a factor of two. Optical model calculations show that considerable changes in both real and imaginary potentials are necessary to reproduce the 11 Li data.

94β -Decay Half-Lives of Neutron-Rich Cs55 to Ho67 : Experimental Feedback and Evaluation of the r -Process Rare-Earth Peak Formation

The β-decay half-lives of 94 neutron-rich nuclei ^{144-151}Cs, ^{146-154}Ba, ^{148-156}La, ^{150-158}Ce, ^{153-160}Pr, ^{156-162}Nd, ^{159-163}Pm, ^{160-166}Sm, ^{161-168}Eu, ^{165-170}Gd, ^{166-172}Tb, ^{169-173}Dy, ^{172-175}Ho, and two isomeric states ^{174m}Er, ^{172m}Dy 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 _{58}Ce, _{59}Pr, _{60}Nd, and _{62}Sm, and N=105 for _{63}Eu, _{64}Gd, _{65}Tb, and _{66}Dy. Features in the data mirror the interplay between pairing effects and microscopic structure. 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.

Experimental studies of light neutron rich nuclei

Abstract Experimental studies of neutron rich nuclei 8 He, 10 He, 12 Be and 13 Be have been performed using radioactive beams.

Rotational bands in 122 Cs

Abstract Excited states of the 122 Cs nucleus have been studied by in-beam γ -ray spectroscopy with the 109 Ag( 16 O ,3 n) 122 Cs fusion-evaporation reaction at a beam energy of 80 MeV. γ – γ coincidence and γ – γ angular correlation analyses were employed for determining the level scheme of 122 Cs. We have determined the spin of the πh 11/2 ⊗νh 11/2 quasiparticle band with spin inversion structure and the negative-parity band with strongly coupled structure. These two rotational bands are found to be built on the same high-spin isomeric 8 − state at 500 keV. In addition, three rotational bands have been newly identified in the present work.

Nuclear structure and β -decay schemes for Te nuclides beyond N=82

We study for the first time the internal structure of 140Te through the beta-delayed gamma-ray spectroscopy of 140Sb. The very neutron-rich 140Sb, Z = 51 and N = 89, ions were produced by the in-flight fission of 238U beam on a 9Be target at 345 MeV per nucleon at the Radioactive Ion Beam Factory, RIKEN. The half-life and spin-parity of 140Sb are reported as 124(30) ms and (4-), respectively. In addition to the excited states of 140Te produced by the beta-decay branch, the beta-delayed one-neutron and two-neutron emission branches were also established. By identifying the first 2+ and 4+ excited states of 140Te, we found that Te isotopes persist their vibrator character with E(4+)/E(2+) = 2. We discuss the distinctive features manifest in this region, such as valence neutron symmetry and asymmetry, revealed in pairs of isotopes with the same neutron holes and particles with respect to N = 82.

Collective and noncollective states in 117Te

Abstract High-spin states of the 117 Te nucleus were studied by in-beam γ-ray spectroscopy with the 103 Rh( 18 O ,p3n) fusion-evaporation reaction at a beam energy of 85 MeV. γ-γ coincidence and γ-γ angular correlation analyses were employed for determining the level scheme of 117 Te. The previously known states based on the ν h 11 2 orbital have been widely extended and some states have been corrected. Based on the TRS calculations, many unusually low-lying states in their excitation energies have been assigned to noncollective oblate states built on various quasiparticle configurations with β 2 ≈ 0.17 and γ = 60°. Meanwhile, in the positive-parity states built on the ν g 7 2 [413] 5 2 + and the ν d 5 2 [402] 5 2 + configurations, the vibrational- and the rotational structures have been found to coexist.

Heavy rotation – evolution of quadrupole collectivity centred at the neutron-rich doubly mid-shell nucleus 170Dy

In this contribution the low-excitation structural properties of the doubly mid-shell nucleus 170Dy are discussed, with a special empasis on the evolution of the ground state rotational band within the dysprosium isotopic chain. Recent results from an experiment with the EURICA setup at RIKEN are shown in the context of previous measurements at the PRISMA+CLARA as well as the PRISMA+AGATA setups at Laboratori Nazionali di Legnaro. A brief outlook on future planned measurements is also given.

Collective And Single-particle Structures In The Neutron-rich Doubly Mid-shell Nucleus 170Dy

One of the most successful descriptions of the structure of atomic nuclei is the spherical shell model. It, however, becomes impractical when moving away from closed-shell nuclei. Instead, it is the interplay between the macroscopic shape degrees of freedom and the microscopic nature of the underlying single-particle structure in a deformed basis that determines the nuclear structure. Being the heaviest nucleus precisely in the middle of, known, closed proton and neutron shells,

Are the nuclei beyond 132Sn very exotic

^{170}