Experiments on the synthesis of neutron-deficient kurchatovium isotopes in reactions induced by 50Ti Ions
By bombarding Pb isotopes with 50Ti ions, two new isotopes of element 104 (kurchatovium) with mass numbers 255 and 256 have been synthesized. The isotope 256Ku has been formed in the reaction 208Pb ( 50Ti, 2n) and has a spontaneous fission half-life of about 5 msec. The odd isotope 255Ku has been formed with a maximum cross section in the reaction 207Pb( 50Ti, 2n) and has a half-life of several seconds. The experimental results obtained, together with the available data on the properties of kurchatovium, substantially change the understanding of the stability of heavy nuclei with respect to spontaneous fission. In this connection the influence of the structure of the fission barrier on the properties of heavy nuclei is discussed. On the basis of the experimental data on the synthesis of Fm and Ku neutron-deficient isotopes in reactions induced by ions heavier than argon, the possibilitie s of synthesizing elements with Z≧106 are investigated.