P. Basu

Fusion ofLi6withTb159at near-barrier energies

Complete and incomplete fusion cross sections for {sup 6}Li + {sup 159}Tb have been measured at energies around the Coulomb barrier by the {gamma}-ray method. The measurements show that the complete fusion cross sections at above-barrier energies are suppressed by {approx}34% compared to coupled-channel calculations. A comparison of the complete fusion cross sections at above-barrier energies with the existing data for {sup 11,10}B + {sup 159}Tb and {sup 7}Li + {sup 159}Tb shows that the extent of suppression is correlated with the {alpha} separation energies of the projectiles. It has been argued that the Dy isotopes produced in the reaction {sup 6}Li + {sup 159}Tb at below-barrier energies are primarily due to the d transfer to unbound states of {sup 159}Tb, while both transfer and incomplete fusion processes contribute at above-barrier energies.

7Li+12C and 7Li+13C fusion reactions at subbarrier energies

Abstract The 7Li+12C and 7Li+13C reactions have been studied at incident energies below and around the Coulomb barrier, by the measurement of cross sections for the characteristic γ-rays emitted from the residual nuclei. Statistical model calculations of the decay of the compound nucleus have been used to deduce the absolute cross sections for different channels and to obtain the total fusion cross sections. There is no evidence for fusion cross section limitations for these systems at energies near the Coulomb barrier as observed in an earlier experiment.

Influence of projectile α-breakup threshold on complete fusion

Abstract Complete fusion excitation functions for B 11 , 10 + Tb 159 have been measured at energies around the respective Coulomb barriers, and the existing complete fusion measurements for Li 7 + Tb 159 have been extended to higher energies. The measurements show significant reduction of complete fusion cross sections at above-barrier energies for both the reactions, B 10 + Tb 159 and Li 7 + Tb 159 , when compared to those for B 11 + Tb 159 . The comparison shows that the extent of suppression of complete fusion cross sections is correlated with the α-separation energies of the projectiles. Also, the two reactions, B 10 + Tb 159 and Li 7 + Tb 159 were found to produce incomplete fusion products at energies near the respective Coulomb barriers, with the α-particle emitting channel being the favoured incomplete fusion process in both the cases.

Inverstigation of 6Li+16O and 7Li+16O reactions at low energies

Abstract The cross sections for the characteristic γ-rays of the residual nuclei following 6 Li+ 16 O and 7 Li+ 16 O reactions have been measured at low energies with HPGe detectors. The fusion cross sections obtained from these γ-ray cross sections for both the systems are found to be in excellent agreement with the total reaction cross sections and this indicates that there is no inhibition of fusion cross sections for these systems at low energies, which is in contradiction to the results obtained from the measurement of evaporation residues and light particles. These cross sections also show good agreement with the IWBC (Incoming Wave Boundary Condition) model and the 1-D BPM (One-Dimensional Barrier Penetration Model) calculations. The critical angular momenta (lcr) dediced from the fusion cross sections are also found to have an energy dependence similar to other Li-induced reactions.

Fusion cross sections for 6Li+12C and 6Li+13C reactions at low energies

Abstract The partial cross sections for the 6Li+12C and 6Li+13C reactions below and above the Coulomb barrier energy have been determined from the cross sections of the characteristic γ-rays measured with HPGe detectors and using the branching factor σ γ σ ch obtained from the statistical model calculations. The fusion cross sections obtained from the sum of these partial cross sections are found to be equal to the total reaction cross sections upto an energy well above the Coulomb barrier energy and there appears to be no evidence for limitation of fusion cross sections for these systems at such energies contrary to the evaporation residue measurements. The measured cross sections are also found to agree nicely with the IWBC (Incoming Wave Boundary Condition) and one-dimensional BPM (Barrier Penetration Model) calculation.

Sub- and above-barrier fusion of loosely bound 6Li with 28Si

Fusion excitation functions are measured for the system 6Li + 28Si using the characteristic

Oblate bands in doubly odd 134La

\gamma

Importance of the1n-stripping process in the6Li + 159Tb reaction

-ray method, encompassing both the sub-barrier and above-barrier regions, viz, Elab = 7-24 MeV. Two separate experiments were performed, one for the above-barrier region ( Elab = 11-24 MeV) and another for the below-barrier region ( Elab = 7-10 MeV). The results were compared with our previously measured fusion cross-section for the 7Li + 28Si system. We observed the enhancement of the fusion cross-section at sub-barrier regions for both 6Li and 7Li , but the yield was substantially larger for 6Li . However, for well-above-barrier regions, a similar type of suppression was identified for both the systems.

Performance of an Axial Gas Ionization Detector

Abstract The band structures of the doubly odd 134La nucleus have been investigated using the 133Cs(α, 3n) 134La reaction at a beam energy of 40 MeV. Altogether six bands have been established, of which details of the yrast band were only known from earlier works. A negative parity oblate band has also been observed in this nucleus. The observed level properties of the members of the yrast band have been compared with theoretical calculations performed within the Particle Rotor Model (PRM) with axially symmetric core. The experimental branching ratios, B (M1) B (E2) values and mixing ratios of the transitions in the yrast band are well reproduced by PRM, assuming an axial oblate core. A cranked shell model calculation has been carried out for the proposed bands.

Performance of a position-sensitive multistep parallel-plate avalanche chamber

The inclusive cross sections of the