A. Huck

Level structure of light even xenon nuclei populated in the decays of isomeric and ground states of 118,120,122Cs

Abstract Gamma and conversion electron lines following the β-decay of 118,120,122Cs nuclei have been investigated at the ISOLDE facility. Evidence has been found for two isomeric states with similar half-lives in 118,120Cs. Level schemes of 118,120,122Xe including levels of the quasiground state, gamma and beta bands have been established. The structure of these nucle is discussed in the framework of the rotational model and the vibrational limit of the interacting boson approximation (IBA) approach.

Laser ionization in β decay studies of Zn and Mn nuclei

Resonance ionization laser ion source (RILIS) technique has been used in the β-decay studies of 59Mn and 58Zn. The importance of the RILIS for production of these elements is discussed. The properties of the low-lying levels of the studied nuclei are discussed.

Beta-decay half-lives of 70Kr and 74Rb

Abstract Beta-decay half-lives of two nuclei close to N = Z line, 70 Kr and 74 Rb, have been measured at the ISOLDE mass-separator facility at CERN. Importance of these half-lives on two ingredients explaining existence and development of the Universe, the astrophysical nucleosynthesis and the Standard Model, are discussed.

Production of isomeric44V and42Sc in high energy heavy ion reactions

Beta-coincidentγ-rays were measured from implanted44V and42Sc nuclei. These were selected after58Ni+nickel reactions by means of the LISE3 spectrometer at GANIL. The production of the isomeric states was identified by detecting their typicalβ-delayedγ-ray cascades. From the intensities of the detectedγ-lines the ratio between isomer and ground-state production of44V follows to be 1 to 3.0(4).

RES-ISOLDE - Post-accelerated radioactive beams at CERN-ISOLDE

The ISOLDE RIB-facility at CERN has today been producing a vast range of radioactive beams since more than 30 years. The low-energy beams of ISOLDE will be complemented by a post-accelerator, REX-ISOLDE, currently being assembled. In order to convert the pseudo-DC, singly-charged beam from the ISOLDE mass separators into a cooled and bunched beam at higher charge states, a novel scheme of trapping, cooling, and charge-state breeding has been devised, using a linear Penning trap and an Electron Beam Ion Source (EBIS). This allows for subsequent acceleration by a short, cost-effective LINAC consisting of an RFQ, an IH-structure and three seven-gap resonators, reaching 0.8–2.2 MeV/u. The installation of REX-ISOLDE is well underway and the first post-accelerated radioactive beams are expected to be obtained during late 2000.

TheN=83 nucleus149Dy from Gamow-Teller decay of its 11/2− and 1/2+149Ho parents

A high-sensitivityγ-spectroscopic study of the149Hoπh11/2 andπs1/2β-decays using mass separated sources has located dominant 0+ → 1+ GT decay strength associated with decay of pairedh11/2 protons, leading to 3п-states in the149Dy daughter nucleus. In theirγ-decay low-lying149Dy levels characteristic of anN=83 nucleus are excited. They include theνf7/2,νp3/2,νh9/2 andνp1/2 single particle- and theνs12/−1 andνd32/−1 two-particle one-hole states, as well as the νf7/2 × 3− andνf7/2 × 2+ particle-phonon multiplets. A synopsis is given of these excitations in theN=83 isotones from149Nd to153Yb. The149Dy GT decay strength is discussed in terms of the147Tb82 and148Dy82 decays. The strength function results are also compared with independent149Ho 11/2− decay data from the literature based on totalγ-ray absorption measurements.

Gamow-teller strength and particle-phonon states in149Dy from decay of its 11/2− and l/2+149Ho parents

Studies of the149Ho 11/2− and 1/2+ GT-decays using on-line mass separation have established in the N=83149Dy nucleus the single neutron excitations below 1.8 MeV and members of the νf7/2×3− and νf7/2×2+ particle-phonon multiplets. Quantitative analysis of the GT-decay strength to149Dy 1qp- and 3qp-states is made in terms of the strength values measured in149Dy0 and147Tb11/2− decay.

Gamow-teller transitions in β-decay of 66 146 Dy80

The β-decay of146Dy80 was studied by γ-ray and conversion electron spectroscopy following on-line mass separation. 58 % of the β-decay proceeding to a group of levels close to 2 MeV excitation is attributed to GT-decay of (πh112/2)0+ pairs populating (πh11/2νh9/2νj0−2)1+ states in146Tb81. The total decay strength is significantly higher than found in148Dy82 decay, which arises from GT-transitions involving the ν-holes.

Single-Neutron States inS133n

The location of several single-neutron states in Sn-133 has been identified. The P-3/2, h(9/2), and f(5/2) states were found at 853.7, 1560.9, and 2004.6 keV, respectively, by measuring gamma rays in coincidence with delayed neutrons following the decay o