Eur. Phys. J. A 16, 447-456 (2003)
DOI: 10.1140/epja/i2002-10109-6

Spontaneous-fission decay properties and production cross-sections for the neutron-deficient nobelium isotopes formed in the reactions

A.V. Belozerov¹, M.L. Chelnokov¹, V.I. Chepigin¹, T.P. Drobina¹, V.A. Gorshkov¹, A.P. Kabachenko¹, O.N. Malyshev¹, I.M. Merkin¹, Yu.Ts. Oganessian¹, A.G. Popeko¹, R.N. Sagaidak¹, A.I. Svirikhin¹, A.V. Yeremin¹, G. Berek², I. Brida² and S. Sáro<sup>2

1</sup>  Flerov Laboratory of Nuclear Reactions, JINR, 141980 Dubna, Russia
²  Comenius University, SK-84215 Bratislava, Slovakia

eremin@sunvas.jinr.ru

(Received: 26 July 2002 / Revised version: 16 October 2002 / Published online: 18 March 2003)

Abstract
Heavy-ion fusion reactions ⁴⁸Ca + ²⁰⁴Pb and ⁴⁴Ca + ²⁰⁸Pb leading to the same compound nucleus ²⁵²No ^* were run in attempts to produce new neutron-deficient spontaneous-fission isotopes of ^249,250No using the electrostatic separator VASSILISSA. Production cross-sections for the spontaneous-fission activities with the half-lives 5.6 and 54 s observed in these reactions are compared with the measured ones for the well-known isotopes of ^{251 - 255}No formed in the heavy-ion fusion reactions ⁴⁸Ca + ²⁰⁶Pb and ⁴⁸Ca + ²⁰⁸Pb. The obtained excitation functions for the reaction products formed after the evaporation of 1-4 neutrons from the corresponding compound No nuclei have been compared with similar data obtained earlier and results of statistical model calculations.

PACS
21.10.Dr - Binding energies and masses.
23.60.+e - Alpha decay.
25.70.-z - Low and intermediate energy heavy-ion reactions.
25.85.Ca - Spontaneous fission.

© Società Italiana di Fisica, Springer-Verlag 2003