Direct Lifetime Measurements of the Excited States in (72)Ni

• Published in: Physical review letters Vol. 116; no. 12; p. 122502
• Main Authors: Kolos, K, Miller, D, Grzywacz, R, Iwasaki, H, Al-Shudifat, M, Bazin, D, Bingham, C R, Braunroth, T, Cerizza, G, Gade, A, Lemasson, A, Liddick, S N, Madurga, M, Morse, C, Portillo, M, Rajabali, M M, Recchia, F, Riedinger, L L, Voss, P, Walters, W B, Weisshaar, D, Whitmore, K, Wimmer, K, Tostevin, J A
• Format: Journal Article
• Language: English
• Published: United States 25.03.2016
• ISSN: 1079-7114
• DOI: 10.1103/PhysRevLett.116.122502

The lifetimes of the first excited 2^{+} and 4^{+} states in ^{72}Ni were measured at the National Superconducting Cyclotron Laboratory with the recoil-distance Doppler-shift method, a model-independent probe to obtain the reduced transition probability. Excited states in ^{72}Ni were populated by the one-proton knockout reaction of an intermediate energy ^{73}Cu beam. γ-ray-recoil coincidences were detected with the γ-ray tracking array GRETINA and the S800 spectrograph. Our results provide evidence of enhanced transition probability B(E2;2^{+}→0^{+}) as compared to ^{68}Ni, but do not confirm the trend of large B(E2) values reported in the neighboring isotope ^{70}Ni obtained from Coulomb excitation measurement. The results are compared to shell model calculations. The lifetime obtained for the excited 4_{1}^{+} state is consistent with models showing decay of a seniority ν=4, 4^{+} state, which is consistent with the disappearance of the 8^{+} isomer in ^{72}Ni.