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Description
Electromagnetic transition probabilities are of great interest to nuclear physicists as they provide detailed information about the nature of the wave functions of the initial and the final states. Odd-odd nuclei in the vicinity of Z = N = 20 and 28 shell closure present a unique opportunity for testing the underlying proton-neutron residual interaction. These nuclei exhibit a complex level structure due to many possible couplings of unpaired nucleons to the even-even core [1]. Hence, the investigation of their nuclear properties provides scope for understanding the single-particle energies and the residual neutron-neutron interactions in the shell model substructure [1,2]. The properties of the low and high spin states in odd-odd 54Mn (Z = 25, N = 29) have been studied [1-3] via different probes. Spectroscopic information such as -ray branching ratios, and multipole mixing ratios, were determined for transition energies, 54 keV up to 1509 keV (from J = 2+ up to 6+) [4,5]. The lifetimes of many states have been also measured [6]. In Kumar et al., [2], the excited states in 54Mn were populated using 51V(20Ne,xn,yp)54Mn reaction up to excitation energy of 5 MeV, = 15+. However, the information on the reduced transitions probabilities in 54Mn is still scarce despite numerous studies.
We shall report on the first conversion electron and electron-positron pair conversion study of 54Mn. Excited states up to 3 MeV have been populated in the 54Cr(p,n)54Mn reaction at 5.4 MeV bombarding energy, using DC beams from ANU Heavy Ion Accelerator Facility (HIAF). Internal Conversion Coefficients (ICC) for the low-lying states in 54Mn were determined in several transitions for the first time [6]. The deduced conversion coefficients allow for the assignment of multipolarities for transition energies > 1 MeV up to ~ 2.1 MeV ( = 1+ up to 4+). The results are compared with shell-model calculations as a test of agreement between theory and the experiment.
[1] S. Basu, et al., 64th DAE BRNS Symp. on Nucl. Phys. 64 66-67 (2019).
[2] G. K. Kumar, et al., Jour. Phys. G: Nucl. Part. Phys. 35 095104 (2008).
[3] A. R. Poletti, et al., Physical Review C 10 2329-2339 (1974).
[4] M. Ogawa and H. Taketani, Nucl. Phys. A 194 259-291 (1972).
[5] D.C.Radford, A.R.Poletti, J. Phys. G 5, 409 (1979).
[6] A.A. Avaa, et al., Physical Review C (in preparation)
