Spectroscopic study of ${}^{40}\mathrm{K}$

High spin states of ${}^{40}\mathrm{K}$ populated through the ${}^{27}\mathrm{Al}({}^{19}\mathrm{F},\alpha np){}^{40}\mathrm{K}$ reaction at 68 MeV beam energy were studied using the Indian National Gamma Array (INGA) facility. Six new levels and fourteen new transitions were added to the existing level scheme. The spins and parities of most of the levels were assigned, modified, or confirmed from $R_{\mathrm{DCO}}$, $R_{\mathrm{ADO}}$, and linear polarization measurements. The multipole mixing ratios $\left(\delta \right)$ for most of the transitions were measured. Large-basis shell-model calculations were performed to understand the microscopic origin of the levels. Different particle restrictions in $sd$ and $pf$ shell orbitals were used to explain the experimental results.

Figure 1

A total projection spectrum of $\gamma$ rays emitted from different nuclei populated in the present experiment.

Figure 2

Background subtracted coincidence spectrum obtained by putting a gate on the 891 keV transition. Newly observed transitions are shown by red color. Transitions marked with $⧫$ are from contaminants.

Figure 3

A schematic representation of (a) DCO and (b) ADO spectra in ${}^{40}\mathrm{K}$. These spectra (a) and (b) are generated by putting gate on 891 keV $(\mathrm{\Delta }J=1)$ transition. The ${90}^{\circ }$ spectra have been artificially shifted by 5 keV for a clear view.

Figure 4

Spectra generated from perpendicular and parallel matrices indicating the electric (magnetic) nature of 2332.7 keV (1651.5 keV) transition. These spectra are generated by putting gates on 891 keV. The parallel spectrum have been artificially shifted by 5 keV for a clear view.

Figure 5

Partial level scheme of ${}^{40}\mathrm{K}$. Energies are given in keV. Newly assigned $\gamma$ transitions (red) and those already observed in light-ion-induced reactions (magenta) are indicated by * and #, respectively. New levels are indicated by blue lines.

Figure 6

Background subtracted coincidence spectra obtained by putting gates on (a) 492.8 keV, (b) 985 keV, (c) 4014 keV, (d) 609 keV, (e) 916.6 keV, and (f) 1671.8 keV transitions. In panel (e) the transitions marked with $\mathbf{\$}$ are from ${}^{42}\mathrm{Ca}$ [27].

Figure 7

Background subtracted coincidence spectra obtained by putting gates on (a) 558.7 keV, (b) 2269.2 keV, and (c) 2790.2 keV transitions. The position of 1142 keV transition in panels (a)–(c) is marked by a dotted line. The position for the 2220 keV transition in (c) is marked by a solid line.

Figure 8

Comparison of theoretical and experimental level schemes for negative parity states in ${}^{40}\mathrm{K}$. All these energies are plotted with respect to the ground state energy ($-272.871$ MeV) as 0.

Figure 9

Comparison of theoretical and experimental level schemes for positive parity states in ${}^{40}\mathrm{K}$. All these energies are plotted considering the ground state energy ($-272.871$ MeV) as 0.

Figure 10

Comparison of theoretical and experimental positive parity levels in ${}^{42}\mathrm{Ca}$. Only the levels of interest are shown in this figure.

Figure 11

Comparison of theoretical and experimental positive parity levels in ${}^{42}\mathrm{Sc}$. Only the levels of interest are shown in this figure.

Figure 12

Calculated spectroscopic factors for the positive-parity states in ${}^{40}\mathrm{K}$ to estimate the contribution of the low-lying positive-parity states of the core nucleus, ${}^{42}\mathrm{Ca}$.

Figure 13

Calculated spectroscopic factors for the positive-parity states in ${}^{40}\mathrm{K}$ to estimate the contribution of the low-lying positive-parity states of the core nucleus, ${}^{42}\mathrm{Sc}$.