Determination of the effective quadrupole moment in 181Ta with pionic X-rays

Abstract

From the hyperfine splitting of the 5g → 4f and the 6g → 4f pionic X-rays in 181Ta, an effective quadrupole moment of Q eff = 3.58±0.03 b was determined. The strong interaction monopole shift ε 0 and the width Γ 0 of the 4f level were measured to be ε 0 = 540±100 eV and Γ 0 = 225±57 eV. in good agreement with the values obtained with the standard optical potential description of the pion-nucleus interaction. Estimating the influence of the finite nuclear size, the deformation induced through the strong interaction between the pion and the finite nucleus, and the relative magnitude between the strong and the electromagnetic quadrupole coupling constants, we arrive at a value for the spectroscopic quadrupole moment of Q = 3.30±0.06 b, and for the intrinsic quadrupole moment of Q 0 = 7.06±0.12 b. This result is in good agreement with earlier values and with recent results reported from kaonic and muonic atoms as well as with the value obtained from Nilsson model calculations.