Eur. Phys. J. A (2010) 46: 59-67
https://doi.org/10.1140/epja/i2010-11026-9

Regular Article - Experimental Physics

The new isotope ²³⁶Cm and new data on ²³³Cm and ^{237, 238, 240}Cf

¹ GSI Helmholtzzentrum für Schwerionenforschung, 64291, Darmstadt, Germany
² Institut für Physik, Goethe-Universität Frankfurt, 60054, Frankfurt, Germany
³ Japan Atomic Energy Agency (JAEA), 319-1184, Ibaraki, Japan
⁴ Institut für Radiochemie, Technische Universität München, 85748, Garching, Germany

Received: 5 July 2010
Accepted: 17 August 2010
Published online: 11 September 2010

Abstract

The isotopes ^{237, 238, 240}Cf were produced in irradiations of ^{204, 206, 207}Pb targets with ³⁶S ions. At bombarding energies close to the Coulomb barrier two or three neutrons were evaporated from the compound nuclei ^{240, 242, 243}Cf . Cross-sections were on the order of a few hundred nanobarns. For the isotope ²⁴⁰Cf a spontaneous fission branching of 0.015±0.002 was determined. The new isotope ²³⁶Cm was produced by decay of ²⁴⁰Cf and identified by - correlations. It decays with an -decay energy of (6954± 20)keV and a half-life of (410±50 s. For the first time, the decay of ²³⁷Cf was observed having an energy of (8081±20 keV. For the isotope ²³³Cm a half-life of ( 23⁺¹³ _-6 s was measured for first time. Spontaneous fission of ^{237, 238}Cf was confirmed and mass-excess values of the nuclei ²³⁶Cm and ^{237, 240}Cf were determined.