High spin spectroscopy in Ra219 : Search for the lower mass boundary of the region of statically octupole-deformed nuclei

Abstract

We report the results of a study of rotational bands in 219 Ra via the 208 Pb( 14 C,3n) reaction to look for evidence that this nucleus is statically octupole deformed. We add 19 γ rays not previously observed to the level scheme and extend the two most strongly populated alternating parity bands to J=51/2 and 45/2. The magnitude of the energy splitting between the spin-parity doublets in the two bands appears to exclude the possibility that 219 Ra has a static octupole deformation.PACS numbers: May be entered using the \pacs{#1} command.

Excited states in Ra217 populated in the α decay of Th221

“…[45]. However, the possible reflection asymmetry of the 219 Ra and 221 Th ground states is still an open question [46,47].…”

Evolution of quadrupole-octupole collectivity in the even–even 54 ≤ Z ≤ 58 nuclei

“…Although the subject of octupole (reflection-asymmetric) deformations in atomic nuclei dates from the early fifties [1][2][3][4][5] nowadays it gains actuality due to the massive appearance of new data on octupole collectivity [6][7][8][9][10][11][12][13][14][15] and, especially, proofs for the presence of axial octupole (pear) shapes in the ground states of light actinide nuclei (such as 222,224 Ra [16][17][18]) and nuclei in the region of Ba and Ce ( 144,146 Ba [19]) isotopes (see recent reviews [17,20]). A number of theoretical models aiming to describe different aspects of collective and microscopic dynamics in nuclei with reflection-asymmetric degrees of freedom [21] have been gradually developing over the years .…”