TheN=47 shell model nucleus90Tc

Abstract

Lifetimes of high spin states in the nucleus 9~ have been measured via the fusion evaporation reactions 58Ni(36Ar, 3pn)9~ at 140 MeV and SSNi(35C1, 2pn)9~ at 120 MeV beam energy. The OSIRIS spectrometer as well as a new neutron-y-coincidence setup were used to measure lifetimes in the 10-12_ 10-9 s range by the recoil distance Doppler-shift method. By means of 7-multiplicity and neutron-gated spectra fifteen lifetimes were deduced. The experimental branching ratios and transition probabilities are compared to predictions of shell model calculations in a restricted re(p1/2), 7c(g9/2) , v(pl/2) , and v(g9/2) configuration space. In most cases the agreement with the calculations using the Gross-Frenkel parameters is striking but the results for several yrare states very sensitively depend on the residual interaction used.

Electromagnetic decay strengths in the isobars89Nb,89Mo and89Tc

“…All of these impedi- The singles, neutron-gated and two neutron-gated 7-ray spectra of the eight detectors were summed up individually in order to obtain maximum statistics. In addition, "pure" neutron-gated and "pure" charged particle-gated spectra were obtained either by subtracting the contribution of the charged particle or the neutron reaction channels from the neutron-gated spectra in the fashion described in [12]. However, these spectra were only used for otherwise contaminated lines, and the main part Of the analysis was performed with the raw multiplicity-gated and neutron-gated spectra.…”

“…The experimental setup consisted of a ring of eight HPGe detectors mounted at 138 ~ relative to the beam axis, an eight-element BGO y-ray multiplicity filter and a foursegment NE213 neutron detector. Detailed information on the setup is given in a paper by Rudolph et al [12]. In addition to the multiplicity-and neutron-gated 2/-ray spectra, 'y'y-coincidences were recorded for 22 distances between the 0.8 mg/cm 2 stretched 58Ni target foil and the 9.5 mg/cm 2 stretched gold stopper foil.…”