Examination of nuclear chirality with a magnetic moment measurement of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>I</mml:mi><mml:mo>=</mml:mo><mml:mn>9</mml:mn></mml:mrow></mml:math> isomeric state in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Cs</mml:mi><mml:mprescripts/><mml:none/><mml:mn>128</mml:mn></mml:mmultiscripts></mml:math>
E. Grodner, M. Kowalczyk, M. Kisieliński, J. Srebrny, L. Próchniak, Ch. Droste, S. G. Rohoziński, Q. B. Chen, M. Ionescu–Bujor, C. A. Ur, F. Recchia, Jie Meng, Shuangquan Zhang, P. W. Zhao, G. Georgiev, R. Lozeva, Enrico Fiori, S. Aydin, A. Nałęcz-Jawecki
Abstract
The $g$ factor of the isomeric $I={9}^{+}$ bandhead of the yrast states in $^{128}\mathrm{Cs}$ is obtained from the time differential perturbed angular distribution measurement performed with the electromagnet at IPN Orsay. An external magnetic field of 2.146 T at the target position was attained with GAMIPE reaction chamber surrounded by four high-purity germanium detectors, of which two were low-energy photon spectrometer type. The results are in accordance with $\ensuremath{\pi}{h}_{11/2}\ensuremath{\bigotimes}\ensuremath{\nu}{h}_{11/2}^{\ensuremath{-}1}\phantom{\rule{4pt}{0ex}}I={9}^{+}$ bandhead assignment and are discussed in the context of chiral interpretation of the $^{128}\mathrm{Cs}$ nucleus as a composition of the odd proton, odd neutron, and even-even core with their angular momentum vectors. The obtained $g$-factor value was compared with predictions of the particle-rotor model. The experimental $g$ factor corresponds to the nonchiral geometry of the isomeric bandhead. This observation indicates the existence of the chiral critical frequency in $^{128}\mathrm{Cs}$ and may explain the absence of the chiral doublet members for $I<13\ensuremath{\hbar}$.