0000000000223960
AUTHOR
H. Gietz
On the nuclear structure of 229Ra
14 pages, 3 tables, 6 figures.
The decay scheme of the 3-s Isomer of100Nb and the properties of levels in100Mo
Theβ− decay of the longer-lived isomer in100Nb has been studied at the fission-product separator JOSEF. Measurements ofγ-ray singles spectra, ofγ-γ coincidences and ofγ-γ angular correlations have been performed. A value oft1/2=2.99(11)s has been determined for the isomer which probably hasIπ=4+ or 5+. A scheme of the levels of100Mo which are populated in the decay of this isomer has been established. Information on the spins of several states of100Mo has been obtained. Thus,I=0 levels have been identified at 1,505, 2,038 and 2,087 keV. The mixing ratios have been determined for the 22+→21+ and 23+→21+ transitions. The results provide evidence for a vibrational structure of100Mo with separa…
The nuclear structure of $^{223}$Fr
Abstract The γ-rays following the β− decay of 223Rn have been investigated by means of γ-ray singles including multispectrum analysis, and γγ-coincidence measurements using Ge detectors. Multipolarities of 38 transitions in 223Fr have been established by measuring conversion electrons with a mini-orange electron spectrometer. Most of the observed transitions could be placed in a level scheme comprising 53 excited states of 223Fr. The level structure is interpreted in terms of K π = 3 2 ± and 1 2 ± parity doublet bands, and a second K π = 3 2 ± higher-lying parity doublet. The experimental data are compared with the theoretical predictions of the reflection-asymmetric rotor model.
Search for stable octupole deformation in $^{225}$Fr
Levels in $^{225}$Fr have been studied by $\gamma$-ray and conversion-electron spectroscopy following the $\beta$-decay of $^{225}$Rn, and by the $^{226}$Ra(t,$\alpha$)$^{225}$Fr single-proton-pickup reaction. Multipolarities were obtained for $\sim$ 50 $\gamma$-transitions, and a level scheme was established in which definite spin-parity values were determined for over 20 of the 48 levels. Although low-lying rotational bands of both parities exist for $K=1/2$ and $K=3/2$, there is no experimental evidence to claim these are parity doublets. E1 strengths connecting the $K^\pi=3/2^\pm$ bands are intermediate between those for nuclides which are reflection symmetric and those claimed to be oc…
Quadrupole deformed and octupole collective bands in 228Ra
Spins and parities for collective states in $^{228}$Ra have been determined from conversion electron measurements with a mini-orange $\beta$-spectrometer. The fast-timing $\beta\gamma\gamma(t)$ method has been used to measure lifetimes of T$_{1/2}$=550(20) ps and 181(3) ps for the $2^{+}_{1}$ and $4^{+}_{1}$ members of the K=0$^{+}$ band, and T$_{1/2} \leqslant$ 7 ps and $\leqslant$ 6 ps for the $1^{-}_{1}$ and $3^{-}_1$ members of the K = $0^{-}$ band, respectively The quadrupole moments, $Q_{0}$ deduced from the B (E2; 2$_{1}^{+} \rightarrow 0_{1}^{+}$) and B (E2; 4$_{1}^{+} \rightarrow 2_1^{+}$) rates are in good agreement with the previously measured value and the systematics of the reg…