A new alpha-particle-emitting isotope (259)Db

An isotope of the element 105 with mass number 259 has been produced via th e reaction Am-241(Ne-22, 4n)(259)Db at E-lab = 118 MeV. The reaction produc ts were transported and collected using the helium-jet technique and the ro tating wheel apparatus. The alpha -decays of the products and their daughte r nuclides were detected by a set of Si(Au) detectors arranged ingeniously. The Z and A of the nuclide have been unambiguously identified by the genet ic relationship between the new activity and the known nuclide Lr-255 estab lished by alpha -recoiled milking measurement. The new nuclide (259)Db has a half-life of 0.51 +/- 0.16 s and decays by alpha-particle emission of E-a lpha = 9.47 MeV. Furthermore. the nuclide (258)Db and its daughter Lr-254 h ave also been clearly observed using the same projectile-target combination . Their half-lives and alpha -particle energies determined in this work are in agreement with previous known data, thus also proving the reliability o f our assignment of (259)Db.