Figure 1

The MWPC-vetoed $\alpha$-particle energy spectrum obtained using the ${}^{40}$Ar $+$ ${}^{169}$Tm reaction.Reuse & Permissions

Figure 2

(a) The spectrum of the delayed $\gamma$ rays detected in the GREAT clover detector, associated with a recoil implantation in the DSSD. (b) The corresponding conversion electrons detected in the PIN-detector array. A correlation time of 100 ns was used between the recoil implantation and the isomeric decay to get optimal visibility of the peaks.Reuse & Permissions

Figure 3

Energy spectra of electrons detected in the horizontal strips of the DSSD. (a) The spectrum obtained by tagging with the ${}^{205}$Fr $\alpha$ decay, using a correlation time of 8 ms between the recoil and the isomeric decay. The spectrum consists of events from a cascade of electrons. [(b)–(d)] The conversion-electron spectra obtained by tagging with the $\alpha$ decays of ${}^{204}$Fr and ${}^{200}$At [38], using a correlation time of 5 s between the $\alpha$ decay and the subsequent electron in panel (b), 3 s between the recoil implantation and the electron in panel (c), and 5 s between the $\alpha$ decay and the subsequent electron in panel (d). See text for further details.Reuse & Permissions

Figure 4

Time distribution between ${}^{205}$Fr recoil implantation and the subsequent de-excitation of the 1/2${}^{+}$ isomer detected in the PIN-detector array. See Ref. [40] for method details. A time window between 50 $\mu$s and 8 ms was used, with the lower limit set to eliminate noise effects.Reuse & Permissions

Figure 5

Spectrum of delayed $\gamma$ rays tagged with the ${}^{205}$Fr $\alpha$ decay, detected in the GREAT planar and clover detector, in coincidence with electrons associated with the 1.15(4)-ms isomer. (Inset) The spectrum of prompt $\gamma$ rays detected in the JUROGAM array and associated with the isomeric decay. A correlation time of 8 ms was used between the recoil implantation and the isomeric decay. Note the broad peaks close to 600 and 840 keV originated from the $(n,n^{\prime }\gamma )$ reaction in the detector material.Reuse & Permissions

Figure 6

The proposed level scheme. The intensity of the 544-keV isomeric transition and transitions associated with the 1/2${}^{+}$ isomer are not to scale. $\Delta$ $=$ 165(5) keV; see text for details.Reuse & Permissions

Figure 7

Simulated electron spectra for three different scenarios in the de-excitation of the 1/2${}^{+}$ isomer. (a) The scenario of a 165(5)-keV $M2$ transition followed by a 235-keV and a 209-keV $M1$ transition, with a 35(10)$\%$ branching to a parallel 444-keV $E2$ transition. (b) The same scenario without the parallel $E2$ transition. (c) A scenario with the isomer depopulated by a 235-keV $E3$ transition followed by a 209-keV $M1$ transition. See text for further details.Reuse & Permissions

Figure 8

(a) Spectrum of singles prompt $\gamma$ rays obtained by requiring a recoil implantation in the DSSD. Peaks belonging to ${}^{205}$Fr are indicated by circles and those belonging to ${}^{205}$Rn [45] by diamonds. (b) Spectrum of singles prompt $\gamma$ rays tagged with the $\alpha$ decay of ${}^{205}$Fr. Transitions belonging to ${}^{169}$Tm [46] are indicated by open circles. [(c) and (d)] Spectra of transitions in coincidence with the 517- and the 477-keV transition, respectively. The two spectra include $\gamma$ rays tagged with escaped $\alpha$ particles. The intensity scale of the high-energy end of panel (c) has been expanded threefold. (e) Spectrum of prompt singles $\gamma$ rays tagged with the $\alpha$ decay of ${}^{206}$Fr. Note the broad peaks close to 600 and 840 keV, visible in each panel, originated from the $(n,n^{\prime }\gamma )$ reaction in the detector material.Reuse & Permissions

Figure 9

Level energies of negative-parity states in odd-mass francium nuclei compared with yrast and near-yrast positive-parity states in their even-mass radon isotones. ${}^{205}$Fr has a neutron number of 118. For the radon data, denoted by open symbols, see the studies in Refs. [5, 8, 9, 10, 51]. The data for the heavier francium nuclei are taken from the studies in Refs. [13, 14, 15]. The lines connect yrast states without specifying the configuration of the states.Reuse & Permissions

Figure 10

Experimental kinematic moments of inertia of the rotational band feeding the 13/2${}^{+}$ isomer in ${}^{205}$Fr compared with neighboring oblate deformed nuclei. The data for the astatine nuclei are taken from Ref. [37] and the bismuth data from Ref. [52].Reuse & Permissions