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The experimental verification of compound nucleus theory has successfully been performed for light ion induced reactions using proton and α -particle beams on different targets. However, such studies using the heavy ion beams are scarce due to the complex nature of heavy ion interaction process. The present work is an attempt to validate the Bohr's independent hypothesis using heavy ion beam of 18O beam on 159Tb targets and 12C on 165Ho targets, forming the same compound nucleus 177Ta. A channel wise analysis of cross section data for evaporation residues produced in 18O+159Tb and 12C+165Ho systems has been performed within the framework of statistical model code PACE4 and found to reasonably agree with the experimental data. Further, a comparison of reaction cross section data for the same evaporation residues produced in the two different systems has been found to follow Bohr's compound nucleus hypothesis at relatively higher excitation energies. However, at relatively lower excitation energies, a significant deviation in the measured cross section data of the same residues in the above mentioned systems have been observed and is attributed to the discrepancies in angular momentum values. Such discrepancies are well explained on the basis of input angular momentum involved in the reactions. [ABSTRACT FROM AUTHOR]

Abstract We present detailed results of a theoretical investigation on the production of evaporation residue nuclei obtained in a heavy ion reaction when charged particles (proton and α -particle) are also emitted with the neutron evaporation along the deexcitation cascade of the formed compound nucleus. The almost mass symmetric 82Se+138Ba reaction has been studied since there are many experimental results on individual evaporation residue (ER) cross sections after few light particle emissions along the cascade of the 220Th compound nucleus (CN) covering the wide 12–70 MeV excitation energy range. Our specific theoretical results on the ER cross sections for the 82Se+138Ba are in good agreement with the available experimental measurements, but our overall theoretical results concerning all possible relevant contributions of evaporation residues are several times greater than the ERs measured in experiment. The discrepancy could be due to the experimental difficulties in the identification of ER nuclei after the emission of multiple neutral and charged particles, nevertheless the analysis of ER data is very important to test the reliability of the model and to stress the importance on the investigation of ER nuclei also obtained after charged particle emissions. [ABSTRACT FROM AUTHOR]

The experiments were performed to study excitation functions (EFs) of evaporation residues (ERs), i.e. 103,102,101Ag, 101,100,99Pd, 101,100Rh, 97Ru, 96Tc, 95Tc, 94Tc, 93Mom, 92Nbm populated in the reactions induced by 12C on 93Nb for exploring the reaction dynamics involved at energies ≈ 47-75 MeV. The activation technique followed by offline γ-ray spectrometry has been employed to measure EFs. These measurements were simulated with other reported values available in literature as well as with theoretical predictions based on computer code PACE-2. The effect of variation of level density parameter involved in this code has also been studied. An excellent agreement was found between theoretical and experimental values in some of the fusion evaporation channels. However, significant enhancement of cross-section as observed in α-emission channels may be due to incomplete fusion (ICF) process and/or direct reaction process. To confirm the aforesaid reaction mechanism, Recoil Range Distributions (RRDs) of various ERs have been measured at ≈ 80 MeV. Moreover, an attempt is made to separate the percentage relative contributions of complete and incomplete fusion components from the analysis of the measured RRDs data. Further, the relative percentage ICF fraction, also estimated from EFs data, was found to be sensitive with the projectile energy. [ABSTRACT FROM AUTHOR]

Abstract: The role of the entrance channel has been studied to ascertain a cause of the observed difference between the evaporation residue cross sections normalized to the fusion cross sections in the 19F+ 181Ta and 16O+ 184W reactions at high excitation energies. The theoretical analysis performed in the framework of the dinuclear system and advanced statistical models showed that the more intense yield of evaporation residues in the 16O+ 184W reaction in comparison with that in the 19F+ 181Ta reaction was explained by the large capture and fusion cross sections in the former reaction, which is in agreement with the experimental data. The observed decrease in the evaporation residue cross section normalized to the fusion cross section in the 19F+ 181Ta reaction, in comparison with one in the 16O+ 184W reaction at large excitation energies, is caused by the unintentional inclusion of the quasifission and fast fission contributions in the fissionlike fragment yields that were used in reconstructing the experimental fusion cross section in the normalizing procedure. The range of the angular momentum distribution for both systems was similar, but the partial cross sections are different, showing the presence of a difference in the hindrance to complete fusion in both reactions. [Copyright &y& Elsevier]

The breakup of the 9Be projectile on the 209Bi target at bombarding energies above and near the Coulomb barrier is studied in the adiabatic two-center shell model approach. The effect of 9Be→n+2α breakup channel on complete fusion, elastic and inelastic cross sections is investigated. Results show that the breakup of the projectile 9Be could be due to a molecular single-particle effect shortly before the colliding nuclei reach the Coulomb barrier. [Copyright &y& Elsevier]