Discovery of New Isotopes Os160 and W156</mml:…

Using the fusion-evaporation reaction ¹⁰⁶Cd(⁵⁸Ni,4n)¹⁶⁰Os and the gas-filled recoil separator SHANS, two new isotopes ₇₆¹⁶⁰Os and ₇₄¹⁵⁶W have been identified. The α decay of ¹⁶⁰Os, measured with an α-particle energy of 7080(26) keV and a half-life of 201₋₃₇⁺⁵⁸ μs, is assigned to originate from the ground state. The daughter nucleus ¹⁵⁶W is a β⁺ emitter with a half-life of 291₋₆₁⁺⁸⁶ ms. The newly measured α-decay data allow us to derive α-decay reduced widths (δ²) for the N=84 isotones up to osmium (Z=76), which are found to decrease with increasing atomic number above Z=68. The reduction of δ² is interpreted as evidence for the strengthening of the N=82 shell closure toward the proton drip line, supported by the increase of the neutron-shell gaps predicted in theoretical models.