Investigation of the {sup 208}Pb({sup 18}O, f) fission reaction: Mass-energy distributions of fission fragments and their correlation with the gamma-ray multiplicity

• Published in: Physics of atomic nuclei Vol. 71; no. 6
• Main Authors: Rusanov, A. Ya, Itkis, M. G., Kondratiev, N. A., Pashkevich, V. V., Pokrovsky, I. V., Salamatin, V. S., Chubarian, G. G.
• Format: Journal Article
• Language: English
• Published: United States 15.06.2008
• Subjects: ACTINIDE NUCLEI; ALPHA DECAY RADIOISOTOPES; ANGULAR MOMENTUM; ASYMMETRY; CHARGED PARTICLES; COLD FISSION; COMPOUND NUCLEI; DISTRIBUTION; ELECTROMAGNETIC RADIATION; ENERGY; ENERGY BALANCE; ENERGY RANGE; ENERGY SPECTRA; EVEN-EVEN NUCLEI; FISSION; FISSION FRAGMENTS; GAMMA RADIATION; HEAVY NUCLEI; INTERACTIONS; IONIZING RADIATIONS; IONS; ISOTOPES; KINETIC ENERGY; LEAD 208; LEAD ISOTOPES; LIGHT NUCLEI; MASS DISTRIBUTION; MEV RANGE; MINUTES LIVING RADIOISOTOPES; MULTIPLICITY; NUCLEAR FRAGMENTS; NUCLEAR PHYSICS AND RADIATION PHYSICS; NUCLEAR REACTIONS; NUCLEI; ORBITAL ANGULAR MOMENTUM; OXYGEN 18; OXYGEN IONS; OXYGEN ISOTOPES; PARTIAL WAVES; PARTICLE INTERACTIONS; RADIATIONS; RADIOISOTOPES; SPATIAL DISTRIBUTION; SPECTRA; STABLE ISOTOPES; SYMMETRY; THORIUM 226; THORIUM ISOTOPES
• ISSN: 1063-7788; 1562-692X
• DOI: 10.1134/S1063778808060021

The mass-energy distributions of fragments originating from the fission of the compound nucleus {sup 226}Th and their correlations with the multiplicity of gamma rays emitted from these fragments are measured and analyzed in {sup 18}O + {sup 208}Pb interaction induced by projectile oxygen ions of energy in the range E{sub lab} = 78-198.5 MeV. Manifestations of an asymmetric fission mode, which is damped exponentially with increasing E{sub lab}, are demonstrated. Theoretical calculations of fission valleys reveal that only two independent valleys, symmetric and asymmetric, exist in the vicinity of the scission point. The dependence of the multiplicity of gamma rays emitted from both fission fragments on their mass, M{sub {gamma}}(M), has a complicated structure and is highly sensitive to shell effects in both primary and final fragments. A two-component analysis of the dependence M{sub {gamma}}(M) shows that the asymmetric mode survives in fission only at low partial-wave orbital angular momenta of compound nuclei. It is found that, for all E{sub lab}, the gamma-ray multiplicity M{sub {gamma}}as a function of the total kinetic energy (TKE) of fragments, M{sub {gamma}}(TKE), decreases linearly with increasing TKE. An analysis of the energy balance in the fission process at the laboratory energy of E{sub lab} = 78 MeV revealed the region of cold fission of fragments whose total kinetic energy is TKE {approx}Q{sub max}.