[en] Work has continued on the construction of the Purdue superconducting electron spectrometer to be installed at the linac. Studies of the problems associated with background in the electron spectra have been completed with a Gerholm-type normal-conducting electron-lens spectrometer on loan from Oak Ridge National Laboratory. This lens has also been used for an experiment where conversion electron-lens in the decay of isomers in ¹⁵⁰Er were measured. Meanwhile, at Purdue, the design of the superconducting spectrometer assembly has been completed and construction and final assembly are well underway. Initial tests of the system will be performed at the 6 MV tandem facility of Purdue University. The spectrometer will subsequently be installed at its final location at the linac

[en] Nuclear structure studies in the A approx. 150 region by γ-ray spectroscopy following heavy ion induced reactions are summarized. Yrast states of N = 82 nuclei close to the proton drip line have been identified as rather pure (πh/sub 11/2)/sup n/ excitations of seniority 2 and 3. The high-spin level structure of ¹⁵⁴Dy has been determined through the ¹²⁴Sn(³⁴S,4nγ) reaction. Both the structure and the level lifetimes indicate a transition at I approx. 32 from collective to few-particle character, with possible shape changes from prolate-to-triaxial-to-oblate

[en] Abstract only

[en] The β decays of ¹⁵⁰Er, ¹⁵²Yb, and ¹⁵⁶Yb nuclei are investigated using the total absorption spectroscopy technique. These nuclei can be considered possible candidates for forming the beam of a monoenergetic neutrino beam facility based on the electron capture (EC) decay of radioactive nuclei. Our measurements confirm that for the cases studied the EC decay proceeds mainly to a single state in the daughter nucleus.

[en] The decays of seniority isomers in the N=82 nuclei ¹⁵⁰Er and ¹⁵²Yb and in their respective N=81 isotopes ¹⁴⁹Er and ¹⁵¹Yb were studied following mass separation by the Argonne Fragment Mass Analyzer. Conversion electrons were detected with Si p-i-n diodes operated at room temperature. The low-energy isomeric transitions in ^151,152Yb have been observed for the first time in the electron spectra. Multipolarity assignments were made for many of the decay γ rays of the four nuclei

[en] β-ray end-point energies for the decay of ¹⁵⁰Er and ¹⁵¹Er were measured using a plastic scintillator-Ge, β⁺-γ coincidence spectrometer. Mass excess values are reported for these nuclides and for members of the α-decay chain which terminates at ¹⁵¹Er. Our results are compared with predictions of mass formulas and with extrapolations based on systematic properties for other nuclei. copyright 1998 The American Physical Society

[en] The availability of a monochromatic neutrino source with adjustable energy could be an invaluable tool for the study of Charge-Parity (CP) violation in the leptonic sector in the frame of the Electroweak Theory of the Standard Model. It has been proposed to use as a neutrino source nuclei that decay by means of the electron capture (EC) process inside a storage ring. A systematic study of candidate nuclei in the ¹⁴⁶Gd region has been carried out. In this contribution we show the results of the experimental study of the beta decay of two possible candidate nuclei (¹⁵²Yb and ¹⁵⁰Er) using the Total Absortion Gamma Spectroscopy (TAGS) technique. A comparison of these results with earlier high resolution measurements is discussed.

No abstract available

No abstract available

[en] Predictions are made for the spectra associated with the (πhsub(11/2))sup(n) configuration when n = 4,5 and 6. Since ¹⁴⁶₆₄Gd₈₂ acts as if it is a closed shell, these states are expected to be low-lying in the nuclei ¹⁵⁰₆₈Er₈₂, ¹⁵¹₆₉Tm₈₂ and ¹⁵²₇₀Yb₈₂. The residual hsub(11/2) interaction is taken from the experimental spectrum of ¹⁴⁸₆₆D₈₂ and it is shown that this conserves seniority to a high degree. Arguments are given as to why configuration mixing may be hard to detect from a study of the energy levels alone. The M1 selection rule and the number dependence of the E2 transition rates within the identical nucleon hsub(11/2) configuration are discussed and it is pointed out that seniority isomers should be seen in these nuclei. This prediction provides a stringent test of the configuration assignment. Formulae are given and estimates are made for the energies of the πgsub(7/2) and πdsub(5/2)-hole states. (orig.)