Structure of the Triplet of low-lying states in101Mo

The properties of the triplet of low-lying states in101Mo have been studied through spectroscopy of theγ radiation following thermal neutron capture in100Mo and β− decay of101Nb and through a measurement of the proton angular distributions in the100Mo(d,p) reaction with 14 MeV deuteron energy. The half-lives of the 13.5 keV state and the 57.0 keV 5/2+ state have been measured as 226(7) and 133(7)ns, respectively. These values and the quadrupole/dipole mixing ratios of the 13.5 keV and 43.5 keV transitions yield spin and parity 3/2+ for the 13.5 keV level. The E2 components in the 13.5 (3/2+ →1/2+) and 43.5 keV (5/2+→3/2+) transitions are ≦ 8·10−4 and 54(9)%, respectively. The possibility of…

Abstract of the 68th Meeting (Spring Meeting) 6–9 March 1990, Heidelberg

Odd neutron nuclei near A=100: Rotational bands in103Mo and105Mo populated in the? ? decays of103Nb and105Nb

Theβ − decays of103Nb and105Nb have been studied at the fission product separators JOSEF and LOHENGRIN. Half-lives of (1.5±0.2) s and (2.95±0.06) s, respectively, have been determined for these decays. Fromγ singles andγ-γ coincidence measurements extended level schemes for103Mo and105Mo have been established for the first time. The lowest energy levels of these nuclei are consistent with the interpretation as members of rotational bands built on a 3/2+ [411] Nilsson state. Evidence is presented for the location of the 9/2+ [404] configuration.

IBMF and IBFFM Approach to Nuclei in the A≃100 Region

An overview of the calculations in IBFM and IBFFM for nuclei in the A ≃ 100 region is presented. The application to these nuclei with a complex structure including the rapid transition from spherical to deformed nuclear shapes provides a stringent test for the capacities of this theoretical approach. From the result of the studies of the heavy Yttrium isotopes and the N=59 isotones it is concluded that it can account for the basic structure and the phase transition in these nuclei.

The deformedN=60 nucleus 41 101 Nb

The β− decay of101Zr has been investigated at the fission-product separators JOSEF and LOHENGRIN. The half-life of101Zr has been determined to 2.5(1) s and a level scheme for101Nb has been established fromγ ray singles as well as X/3-γ and γ—γ coincidence measurements. Conversion coefficients for transitions in101Nb and level half-lives between 10 ps and 2 ns have been determined. Three rotational bands are identified among the low-lying levels with band heads at 0 keV, 206 keV and 208 keV. The bands are probably based on the Nilsson configurations [422 5/2+], [301 3/2−] and [303 5/2−], respectively. The deformation has been determined to βq=0.40(4) and 0.41(8) for the ground state band and…

Evidence for rotational bands in103Nb

The nucleus103Nb62 has been studied through the s− decay of the fission product103Zr at LOHENGRIN and JOSEF. The energies of the lowlying levels and the γ transitions indicate rotational bands based on the Nilsson proton configurations [422 5/2+] [303 5/2−] and [301 3/2−] at 0, 164 and 248 keV, respectively. The measured half-lives of (4.7±0.5) ns and (2.0±0.6) ns of the levels at 164 and 248 keV are consistent with the Nilsson-model estimates including pairing.

Subshell closure effects on the collectivity of 36 88 Kr52 and the beta decay of88Br to levels in88Kr

The level structure of88Kr has been investigated by measurements on chemically separated bromine samples. A total of 146γ-rays have been assigned to the decay of88Br, and a level scheme with 58 levels is proposed. The collectivity of88Kr has been investigated within the framework of the Interacting Boson Approximation (IBA-2 model). Comparison of our detailedγ-ray data and calculations have led to the establishment of a protonhole boson desciption rather than protonparticle nature. This supports recent works establishingZ=40 as a major subshell closure.

TheK=3/2 1 + side-band in99Y and its description by the IBFM/PTQM model

The K=3/21T rotational band has been identified in99Y with a band-head energy of 536 keV. This result is in contradiction with previously reported data, but is in agreement with predictions of the IBFM/PTQM model.