Speaker
Description
In the light odd-mass $^{65-69}$Ga isotopes ($Z = 31$), the excited states have several bands arising from the weak coupling of a quasi-particle occupying the $\pi f_{5/2}$, $\pi p_{3/2}$, and $\pi g_{9/2}$ orbitals [1]. In the present study, the excited states of $^{67}$Ga were populated via $^{56,57}$Fe($^{13}$C, p2n$\gamma$/pn$\gamma$) fusion-evaporation reaction at 45 MeV beam energy. The $^{13}$C beam was obtained from the 14 UD Pelletron accelerator at the Tata Institute of Fundamental Research (TIFR), Mumbai, India. The Indian National Gamma Array (INGA), equipped with 15 Compton-suppressed HPGe clover detectors (at the time of the experiment), was used to detect the de-excited $\gamma$-rays. The level scheme analysis was performed using the RADWARE package [2] and Cubix software [3].
In the present work, the low-lying $\gamma$-ray transitions were reinvestigated using two-fold and three-fold coincidences. The spin and parity of the levels were assigned based on the $R_{\text{DCO}}$ and linear polarization asymmetry ($\Delta$) values. In our measurements, the 342.5-, 416.6-, 554.4-, 712.4-, 824.0-, 888.4-, 958.0-, 1159.8-, 1202.0-, 1239.8-, 1317.9-, 1330.7-, and 1641.5 keV $\gamma$-ray transitions exhibit quadrupole character with $\Delta I = 2$ or $\Delta I = 0$. The 358.9-, 546.1-, 842.9-, 871.3-, 935.2-, and 1343.4 keV $\gamma$-ray transitions have been identified as dipole transitions. Based on polarization asymmetry ($\Delta$) measurements, the 712.4-, 824.0-, 888.4-, 958.0-, 1159.8-, and 1202.0 keV $\gamma$-ray transitions are of $E2$ character, while the 871.3 keV $\gamma$-ray transition is of $E1$ character. The 554.4 keV $\gamma$-ray transition has a negative polarization asymmetry ($\Delta$) value and exhibits $E1$ ($\Delta I = 0$) character. Other transitions, such as 358.9-, 546.1-, and 842.9 keV, have $M1/E2$ character.
The relative intensities of the measured $\gamma$-ray energies are also reported in our work. The multipolarity of the $\gamma$-rays agrees with a recently published paper; however, due to limited statistics, we did not observe the newly reported $E3$ transition [4]. To determine the mixing ratio of the $\gamma$-rays, further analysis is in progress, and more results will be presented during the conference.
Acknowledgment
We thank the INGA group and the Pelletron staff at the Tata Institute of Fundamental Research for their assistance. One of the authors, Nandini Patel, acknowledges the financial support from the University Grants Commission (UGC), India, through a research fellowship at the University of Delhi, New Delhi 110007, India.
References
[1] P. Banerjee, B. Sethi, M. B. Chatterjee and R. Goswami, Il. Nuovo. Cimento. A 110 1365 (1997).
[2] D. Radford, Nucl. Instrum. Methods Phys. Res. A 361, 297 (1995).
[3] J. Dudouet, Cubix (1.0), Zenodo 2024.
[4] Z. X. Zhou et al., Phys. Rev. C. 110, 024309 (2024).
