Electric Quadrupole Excitation Strengths of Sn 112,116,120 From Nuclear Resonance Fluorescence

Abstract

Electric quadrupole ground-state excitation strengths B(E2)↑ of the first 2+ states of midshell Sn isotopes were measured with the nuclear resonance fluorescence method to investigate the systematic disagreement between available experimental data from different techniques. Also, model calculations show conflicting trends of B(E2;01+→21+) values around Sn116. Three experiments on Sn112,116,120 were carried out at the superconducting Darmstadt linear accelerator with beams of bremsstrahlung. A consistent analysis including systematic effects for all experiments yields a decrease in excitation strength from B(E2)↑=0.234(13)e2b2 for Sn112 to B(E2)↑=0.195(13)e2b2 for Sn116, followed by a slight decline to B(E2)↑=0.188(14)e2b2 in Sn120. Reduced collectivity around Sn116, as measured with the Doppler-shift attenuation method and predicted by latest Monte Carlo shell model calculations, can thus not be confirmed by our results; whereas satisfactory agreement is found with available Coulomb excitation data. © 2024 American Physical Society.