1. Coulomb and nuclear excitations of $^{70}$Zn and $^{68}$Ni at intermediate energy
- Author
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Calinescu, S., Sorlin, O., Matea, I., Carstoiu, F., Dao, D., Nowacki, F., de Angelis, G., Astabatyan, R., Bagchi, S., Borcea, C., Borcea, R., Cáceres, L., Ciemála, M., Clément, E., Dombrádi, Z., Franchoo, S., Gottardo, A., Grévy, S., Guerin, H., Harakeh, M. N., Harca, I. M., Kamalou, O., Kmiecik, M., Krasznahorkay, A., Krzysiek, M., Kuti, I., Lepailleur, A., Lukyanov, S., Maj, A., Maslov, V., Mazurek, K., Morfouace, P., Mrazek, J., Negoita, F., Niikura, M., Olivier, L., Penionzhkevich, Y., Perrot, L., Petrone, C., Podolyák, Z., Rigollet, C, Roger, T., Rotaru, F., Sohler, D., Stanoiu, M., Stefan, I., Stuhl, L., Thomas, J. C., Vajta, Z., Vandebrouck, M., and Wieland, O.
- Subjects
Nuclear Experiment ,Nuclear Theory - Abstract
The reduced transition probabilities $B(E2; 0^+_{g.s.}\rightarrow2_1^+,2^+_2)$ in $^{70}$Zn and the full $B(E2; 0^+_{g.s.}\rightarrow2^+)$ strength up to S$_n$=7.79 MeV in $^{68}$Ni have been determined at the LISE/GANIL facility using the Coulomb-excitation technique at intermediate beam energy on a $^{208}$Pb target. The $\gamma$ rays emitted in-flight were detected with an array of 46 BaF$_2$ crystals. The angles of the deflected nuclei were determined in order to disentangle and extract the Coulomb and nuclear contributions to the excitation of the 2$^+$ states. The measured $B(E2; 0^+_{g.s.}\rightarrow2_1^+)$ of 1432(124) e$^2$fm$^4$ for $^{70}$Zn falls in the lower part of the published values which clustered either around 1600 or above 2000 e$^2$fm$^4$, while the $B(E2; 0^+_{g.s.}\rightarrow2^+_2)$ of 53(7) e$^2$fm$^4$ agrees very well with the two published values. The relatively low $B(E2; 0^+_{g.s.}\rightarrow2_1^+)$ of 301(38) e$^2$fm$^4$ for $^{68}$Ni agrees with previous studies and confirms a local magicity at $Z=28, N=40$. Combining the results of the low-energy spectra of $^{68}$Ni and $^{70}$Zn and their shell-model interpretations, it is interesting to notice that four different shapes (spherical, oblate, prolate and triaxial) are present. Finally, a summed $E2$ strength of only about 150 e$^2$fm$^4$ has been found experimentally at high excitation energy, likely due to proton excitations across the $Z=28$ gap. The experimental distribution of this high-energy $E2$ excitation agrees with SM calculations, but its strength is about two times weaker.
- Published
- 2021