The first experimental evidence for the (M1+E2) mixed character of the 9.2 keV transition in Th-227

The 9.2 keV nuclear transition in Th-227 was studied in the beta(-)-decay of Ac-227 by means of the internal conversion electron spectroscopy to clarify the spin-parity assignment of the ground state and the two lowest excited states of Th-227. The transition multipolarity was proved to be of mixed character M1+ E2 and the spectroscopic admixture parameter delta(2)(E2/M1) = 0.695 +/- 0.248(vertical bar delta(E2/M1)vertical bar = 0.834 +/- 0.149) was determined. Nonzero value of delta(E2/M1) questioned the present theoretical interpretation of low-lying levels of Th-227. Calculations performed prefer the 1/2(+), 3/2(+), and 3/2(+) sequence instead of the adopted 1/2(+), 5/2(+) and 3/2(+) one for the 0.0, 9.2, and 24.3keV levels, respectively.Web of Science820art. no. 13659

Improved energy of the 21.5 keV M1 + E2 nuclear transition in

Using internal conversion electron spectroscopy, improved energy 21 541.5±0.5 eV was determined for the 21.5keV M1 + E2 nuclear transition in 151Eu populated in the electron capture decay of 151Gd . This value was found to agree well with the present adopted value but is much more accurate. A value of 0.0305±0.0011 derived for the E2 admixture parameter $\vert\delta(E2/M1)\vert$ from the measured conversion electron line intensities corresponds to the present adopted value. A possible effect of nuclear structure on the multipolarity of the 21.5 keV transition was also investigated

Experimental investigation of the 9.2 and 24.3 keV nuclear transitions in

The 9.2 and 24.3 keV nuclear transitions in $$^{\mathrm {227}}$$Th were studied in the \upbeta ^{-} decay of $$^{\mathrm {227}}$$Ac employing the internal conversion electron spectroscopy. Values of $$(9244.6 \pm 0.8)$$ and $$(24343.1 \pm 1.1)$$ eV were determined for their energies. The 24.3 keV transition was found to be of the mixed (M1 $$+$$ E2) multipolarity with the spectroscopic admixture parameter $$\delta ^{\mathrm {2}}$$$$(E2/M1)$$=$$(0.0116 \pm 0.0004)$$. Energies of $$(24342.9 \pm 1.2)$$, $$(28613.3 \pm 1.7)$$, and $$(37860.2 \pm 2.0)$$ eV were obtained respectively for the 24.3, 28.6, and 37.8 keV transitions in $$^{\mathrm {227}}$$Th by means of the gamma-ray spectroscopy. Natural atomic-level widths of $$(14.1 \pm 0.5)$$, $$(11.4 \pm 0.5)$$, $$(6.9 \pm 0.4)$$, $$(11.4 \pm 1.4)$$, $$(8.6\pm 1.2)$$, and $$(6.0 \pm 0.7)$$ eV for the M$$_{\mathrm {1}}$$-, M$$_{\mathrm {2}}$$-, M$$_{\mathrm {3}}$$-, N$$_{\mathrm {1}}$$-, N$$_{\mathrm {2}}$$-, and N$$_{\mathrm {3}}$$-subshells of thorium, respectively, were derived from conversion electron lines. The cross checking of the energy values of the 9.2, 15.1, and 24.3 keV nuclear transitions obtained by the ICES method is also given

An experimental investigation of the 15.1 keV M1 + E2 nuclear transition in

Using the internal conversion electron spectroscopy, the energy of the 15.1 keV $M1+E2$ nuclear transition in 227Th populated in the $\beta^{-}$ decay of 227Ac was determined to be $15098.6 \pm 1.0$ eV. This value is more accurate than the present accepted one by a factor of 200. The present uncertainty in the transition multipolarity was removed and it was found to be $M1+E2$ with the admixture $\vert\delta (E2/M1)\vert = 0.035 \pm 0.006$

The KLM + KLN Auger electron spectrum of rubidium in different matrices

The KLM + KLN Auger electron spectrum of rubidium (Z = 37) emitted in the electron capture decay of radioactive 83Sr in a polycrystalline platinum matrix and also 85Sr in polycrystalline platinum and carbon matrices as well as in an evaporated layer onto a carbon backing were experimentally studied in detail for the first time using a combined electrostatic electron spectrometer. Energies, relative intensities, and natural widths of fifteen basic spectrum components were determined and compared with both theoretical predictions and experimental data for krypton (Z = 36). Relative spectrum line energies obtained from the semi-empirical calculations in intermediate coupling scheme were found to agree within 3σ with the measured values while disagreement with experiment exceeding 3σ was often observed for values obtained from our multiconfiguration Dirac–Hartree–Fock calculations. The absolute energy of the dominant spectrum component given by the semi-empirical approach agrees within 1σ with the measured value. Shifts of +(0.2 ± 0.2) and −(1.9 ± 0.2) eV were measured for the dominant KLM spectrum components between the 85Sr sources prepared by vacuum evaporation on and implanted into the carbon foil, respectively, relative to 85Sr implanted into the platinum foil. A value of (713 ± 2) eV was determined for the energy difference of the dominant components of the KLM + KLN Auger electron spectra of rubidium and krypton generated in the polycrystalline platinum matrix. From the detailed analysis of the measured data and available theoretical results, the general conclusion can be drawn that the proper description of the KLM + KLN Auger electron spectrum for Z around 37 should still be based on the intermediate coupling of angular momenta taking into account relativistic effects

Improved energies for the 5.2 keV M1 and 42.0 keV M2 nuclear transitions in

The low-energy electron spectrum following the decay of 83Sr was analysed at high instrumental resolution by an electrostatic spectrometer. Significantly improved energies of $5235.7\pm 0.8$ and $42078.0\pm 1.8$ eV were determined from the conversion electron spectra for the nuclear transitions depopulating the first 3/2- and the second $9/2^{+}$ excited states in 83Rb to the $5/2^{-}$ ground state, respectively. The M1 character for the 5.2keV nuclear transition was confirmed and the E2 admixture parameter $\delta^{2}(E2/M1)=(2.6\pm 0.2)\times 10^{-5}$ was obtained. Values of $2.8\pm 0.2$, $3.8\pm 0.2$, $1.4\pm 0.3$, $1.4\pm 0.4$, and $4.1\pm 0.3$ eV were determined for the K, L1, L2, L3, and M1 natural atomic level widths of rubidium, respectively