New evidence for core excitation in Au197

The low-energy level structure and the electromagnetic properties of191Ir and193Ir

“…The core g-factor, gc, for the neighbouring even-even nuclei has been calculated to be around 0.57, a value which is consistent with the results of other theoretical calculations on Ir and Au nuclei [2,11] but is, inconsistent with the experimental results on the g-factors of the 2 + state in 192pt and x94pt [31]. The magnetic moment of the low-lying 5/2 + state in both the Iridium nuclei has been satisfactorily explained.…”

“…The low-lying positive parity states in 191Ir and 19air nuclei are similar to that of 197Au, whose static and transition moments can be well accounted for on the weak particle-core coupling model [1][2][3][4]. Recently the level structure and the transition rates in 19qr and ~93Ir have been investigated in detail by radioactivity [5][6][7][8] and Coulomb excitation [9][10][11] experiments.…”

“…The magnetic moment of the 15/2) state, as it involves p (5/2) s.p. [2], has been calculated e~_ free for gs -gs and g~ff=0.5 ~,strfree" Since the admixture of the single particle d5/2 state is small (Sec. 2.2 and 2.3) these approximations do not have much effect on # (5/2) (see Tables 1 and 2).…”

“…The low-lying excited states can be described as a d3/2 proton hole coupled to the quadrupole vibrations of the Platinum core. The wave functions for the various states can be written as [2] Here [4J; J) denotes a state in which the core state Jc, has been coupled to the odd particle spin j, to give a total angular momentum of J. To account for the observed M 1 transition rates of the multiplet to the ground state transitions, admixture among the 3/2 states is allowed.…”

On the spin assignment to the 268 keV state in Au197

“…The rare exception to this rule for a long time was the spin of the 286 keV state in Au 197. The Braunstein-De Shalit model [1] predicted the value 3/2, but a number of c~ K conversion coefficient measurements for the 191 keV transition to the 77 keV, I= 1/2 state, required some E0 besides the M1 conversion, suggesting the value 1/2 [2,4,6,7]. More recent measurements [8,9] indeed seemed to have settled the things down, deciding the 191 keV transition to be of the M 1 + E2 type, thus establishing the spin to the more reasonable 3/2.…”