Isomeric and ground-state properties of ${}_{78}^{171}\mathrm{Pt}$, ${}_{76}^{167}\mathrm{Os}$, and ${}_{74}^{163}\mathrm{W}$

Decay paths, half-lives, and excitation energies of the $i_{13/2}$ bandheads of the neutron-deficient nuclei ${}^{171}\mathrm{Pt}$, ${}^{167}\mathrm{Os}$, and ${}^{163}\mathrm{W}$ have been established for the first time. Gamma-ray transitions, X-rays, and internal conversion electrons have been observed, allowing internal-conversion coefficients to be measured and $B(M2)$ reduced transition probabilities to be extracted. These results elucidate the low-lying single-quasiparticle structures and give the energy level spacings between the $\nu f_{7/2}$, $\nu h_{9/2}$, and $\nu i_{13/2}$ quasineutron states for all three nuclei. Moreover, ground-state spin assignments have been made for the first time, along with the measurement of the $\alpha$-decay branching ratio for ${}^{171}\mathrm{Pt}$. The decay paths of the $i_{13/2}$ bandheads were followed by favored $\alpha$ decays, indicating that all three nuclei have the same $I^{\pi }=7/2^{-}$ ground state.

Figure 1

Spectra of $\alpha$-decay energies correlated to a recoil implant within the same pixel of the DSSDs at the focal plane of RITU, within a maximum correlation time of 3 s are shown in (a) and (b) for reactions 1 and 2, respectively.

Figure 2

The decay curve of the $\alpha$ decay of ${}^{163}\mathrm{W}$, taken as the time difference between the $\alpha$ decays of ${}^{167}\mathrm{Os}$ and ${}^{163}\mathrm{W}$ subsequent to the $\alpha$ decay of ${}^{171}\mathrm{Pt}$ in reaction 5. The maximum search time between a recoil and ${}^{171}\mathrm{Pt}$ $\alpha$ decays, ${}^{171}\mathrm{Pt}$ $\alpha$ decays, and ${}^{167}\mathrm{Os}$ $\alpha$ decays were 150 ms and 3 s, respectively. The fit to the data was produced using Eq. (8) in Ref. [33] and is shown in by the solid/red line.

Figure 3

Recoil-gated and ${}^{163}\mathrm{W}$ $\alpha$-tagged $\gamma$-ray spectra taken from the clover and planar Ge detectors at the focal plane of RITU. In all cases, $\gamma$ rays were collected up to 1 $\mu$s after a recoil implant in the DSSDs. (a) A spectrum of recoil-gated $\gamma$-rays from reaction 1. (b) A recoil-gated $\gamma$-ray spectrum from reaction 2. (c) and (d) are the same as (a) and (b), respectively, with the additional requirement that the recoil implantation is followed by an $\alpha$ decay of ${}^{163}\mathrm{W}$ in the same DSSDs pixel within 3 s of the recoil.

Figure 4

(a) A summed energy spectrum of $\gamma$ rays detected in the GREAT planar and clover detectorswithin 1 $\mu$s of a recoil implantation in the DSSDs and correlated with the yrast band $\gamma$-ray transitions labeled in (b), of ${}^{163}\mathrm{W}$ detected in JUROGAM up to 2 $\mu$s before a recoil implant. (b) Spectrum showing $\gamma$ rays detected in JUROGAM in delayed coincidence with the 38 keV, 102 keV, 378 keV, and 442 keV $\gamma$ rays detected in the GREAT planar and clover detectors. The $\gamma$ rays form the yrast band of ${}^{163}\mathrm{W}$. Each spectrum reflects the combined data from reactions 1 and 2.

Figure 5

Conversion electron spectrum from the PIN diodes taken within 1 $\mu$s of recoil implant in the DSSDs from reaction 1. The labeled peaks are assigned to ${}^{163}\mathrm{W}$.

Figure 6

Spectra of transitions associated with ${}^{163}\mathrm{W}$. (a) Spectrum showing $\gamma$ rays detected in the clover detectors in coincidence with 38 keV $\gamma$ rays detected in the planar detector. Inset shows conversion electrons measured in the PIN-diodes in coincidence with 38 keV $\gamma$ rays detected in the planar detector. (b) Same as (a), but for the 102 keV transition. (c) Spectrum showing $\gamma$ rays detected in the planar in coincidence with 442 keV $\gamma$ rays detected in the clover detector. Inset shows the decay curve generated by the time difference between a recoil implant in the DSSDs and a 442 keV $\gamma$ ray in the clover or planar detectors. The solid line is an exponential fit to these data. (d) Spectrum showing $\gamma$ rays detected in the planar detector in coincidence with 378 keV $\gamma$ rays detected in the clover detector. The inset shows the decay curve of 378 keV $\gamma$ rays from the time difference between a recoil in the DSSDs and a $\gamma$ ray in either the clover or planar detectors. An exponential fit to the data is shown by the solid/red line.

Figure 7

A partial level scheme of ${}^{163}\mathrm{W}$ showing the decay path from the $13/2^{+}$ isomeric state and the ground-state $\alpha$-decay information. The $\alpha$-decay energy is taken from Ref. [4].

Figure 8

(a) An $\alpha$-decay spectrum correlated within 3 s of a recoil is shown in (a), taken from reactions 3 and 4. (b) shows the decay curve of ${}^{167}\mathrm{Os}$ correlated within 3 s of a ${}^{171}\mathrm{Pt}$ parent decay, which is correlated to a recoil, using a maximum search time of 150 ms. These data were collected during experiment 5. The fit to the data was produced using Eq. (8) in Ref. [33] and is shown in by the solid/red line.

Figure 9

(a) An energy spectrum of $\gamma$-ray transitions measured in the clover and planar detectors within 3 $\mu$s of a recoil implant in the DSSDs, correlated with the $\alpha$ decay of ${}^{167}\mathrm{Os}$ within a maximum correlation time of 3 s. These data were taken from the total run time of reaction 3 and 4. (b) A spectrum of $\gamma$ rays measured in the clover detector in coincidence with the 87 keV transition measured in the planar detector. (c) A spectrum of $\gamma$ rays measured in the planar detector in coincidence with the 348 keV transition measured in the clover detector. The inset in (c) shows time differences between the 87 keV transition in the planar detector and a recoil in the DSSD and the 348 keV transition in the clover detector and a recoil in the DSSD. The recoil implant is tagged with the $\alpha$ decay of ${}^{167}\mathrm{Os}$. An exponential fit of the form $N=N_0{e}^{-\lambda t}+N_1{e}^{-\lambda 1t}$, is shown by the solid/red and blue lines. The spectra shown in (b) and (c) are taken from reaction 4 only.

Figure 10

(a) Spectrum showing the energies of $\gamma$-ray transitions detected in the GREAT planar and clover detectors within 3 $\mu$s of a recoil implantation in the DSSDs and correlated with the yrast band [marked transitions in (b)] of ${}^{167}\mathrm{Os}$ detected in JUROGAM up to 2 $\mu$s before a recoil implant. (b) Spectrum showing $\gamma$ rays detected in JUROGAM in delayed coincidence with the 87 keV and 348 keV $\gamma$ rays detected in the GREAT planar and clover detectors. Each spectrum contains the summed data from experiments 3 and 4.

Figure 11

A partial level scheme of ${}^{167}\mathrm{Os}$ showing the decay path from the $13/2^{+}$ isomeric state and the ground-state $\alpha$-decay information. The $\alpha$-decay energy is taken from Ref. [4].

Figure 12

(a) A spectrum taken from reaction 5 of $\alpha$-decay energies correlated with a recoil implant in the DSSDs within a maximum search time of 150 ms. (b) The time differences between a recoil implant and the $\alpha$ decay of ${}^{171}\mathrm{Pt}$, correlated within 960 ms of a recoil, also correlated to the daughter decay ${}^{167}\mathrm{Os}$ and granddaughter decay ${}^{163}\mathrm{W}$, within correlation times of 2.73 s and 8 s, respectively. The fit to the data was produced using Eq. (8) in Ref. [33] and is shown in by the solid/red line.

Figure 13

A spectrum showing $\gamma$-ray energies from the clover and planar detectors, correlated with the $\alpha$ decay of ${}^{171}\mathrm{Pt}$. The $\gamma$ rays were collected within 4 $\mu$s of a recoil implant in the DSSDs.

Figure 14

(a) An energy spectrum of $\gamma$-ray transitions in the clover detector in coincidence with the 90 keV transition in the planar detector. (b) A spectrum of $\gamma$-ray energies in the planar detector in coincidence with the 323 keV $\gamma$-ray in the clover detector. (c) An energy spectrum of conversion electrons in the PIN-diodes gated by the 90 keV $\gamma$-ray transition in both the clover and planar detectors. A 4 $\mu$s time gate between either a $\gamma$ ray or conversion electron and a recoil is applied to all spectra. The inset of (b) shows the decay curve of the 90 keV $\gamma$ ray and the (red) line is an exponential fit to these data. These data are taken from reaction 5 are associated to ${}^{171}\mathrm{Pt}$.

Figure 15

(a) A $\gamma$-ray energy spectrum recorded in JUROGAM produced by gating on the 90 keV and 323 keV transitions in the clover and planar detectors, plus the 323-$L$ and 323-$K$ conversion electrons in the PIN-diodes. (b) A conversion electron spectrum produced by gating on the prompt $\gamma$-ray transitions in JUROGAM with energies of 445 keV, 605 keV, and 740 keV. (c) A delayed $\gamma$-ray spectrum from the clover plus planar detectors with the same gates as (b). All focal plane $\gamma$ rays and conversion electron’s were collected within 4 $\mu$s of a recoil implant in the DSSDs. These data are taken from reaction 5 and shows transitions associated to ${}^{171}\mathrm{Pt}$.

Figure 16

A partial level scheme of ${}^{171}\mathrm{Pt}$ showing the decay path from the $13/2^{+}$ isomeric state and the ground-state $\alpha$-decay information. The $\alpha$-decay energy is taken from Ref. [40].

Figure 17

A plot of the excitation energies of the $9/2^{-}$ state and $13/2^{+}$ state relative to the $7/2^{-}$ ground state for even-$Z$ odd-$N$ isotopes with $F_{\max }=7.5$. Values for ${}_{\hspace{0.5em}68}^{151}{\mathrm{Er}}_{83}$, ${}_{\hspace{0.5em}70}^{155}{\mathrm{Yb}}_{85}$, and ${}_{\hspace{0.5em}72}^{159}{\mathrm{Hf}}_{87}$ are taken from Refs. [30, 31, 32], respectively, ${}_{\hspace{0.5em}74}^{163}{\mathrm{W}}_{89}$, ${}_{\hspace{0.5em}76}^{167}{\mathrm{Os}}_{91}$, and ${}_{\hspace{0.5em}78}^{171}{\mathrm{Pt}}_{93}$ are from this work and ${}_{\hspace{0.5em}80}^{175}{\mathrm{Hg}}_{95}$ is taken from [7].