Eur. Phys. J. A (2005) 25: 589-594
https://doi.org/10.1140/epjad/i2005-06-134-9

ENAM 2004

New elements from Dubna

¹ Joint Institute for Nuclear Research, 141980, Dubna, Russian Federation
² Lawrence Livermore National Laboratory, University of California, 94551, Livermore, CA, USA

^* e-mail: utyonkov@sungns.jinr.ru

Received: 19 October 2004
Accepted: 19 March 2005
Published online: 29 June 2005

Abstract

We have studied the dependence of the production cross-sections of the isotopes ^{282, 283}112 and ^286-288114 on the excitation energy of the compound nuclei ²⁸⁶112 and ²⁹⁰114. The maximum cross-sections of the xn-evaporation channels for the reaction ²³⁸ U(⁴⁸ Ca, xn)^286-x112 were measured to be: σ_3n = 2.5^+1.8 _-1.1pb and σ_4n = 0.6^+1.6 _-0.5pb; for the reaction ²⁴² Pu(⁴⁸ Ca, xn)^290-x114: σ_2n ∼ 0.5pb, σ_3n = 3.6^+3.4 _-1.7pb and σ_4n = 4.5^+3.6 _-1.9pb. In the reaction ²³³ U(⁴⁸ Ca, 2-4n)^277-279112 we measured an upper cross-section limit of σ_xn≤0.6pb. An increase of σ_ER in the reactions of actinide targets with ⁴⁸Ca can be due to the expected increase of the survivability of the excited compound nucleus upon closer approach to the closed neutron shell N = 184. The observed nuclear decay properties of the nuclides with Z = 104-118 are compared with theoretical nuclear mass calculations and the systematic trends of α-decay properties. As a whole, they give a consistent pattern of decay of the 18 even-Z neutron-rich nuclides with Z = 104-118 and N = 163-177.