H. Majumdar

The study of threshold behaviour of effective potential for Li6+Ni58,64 systems

Abstract The elastic scattering for 6 Lixa0+xa0 64 Ni system was measured in the bombarding energy range of 13 MeV ⩽ E lab ⩽ 26 MeV . A phenomenological optical model analysis was performed and the behaviour of the surface strengths of the potential components with decreasing energy was extracted. A further analysis of the measured angular distributions, along with the existing data for 6 Lixa0+xa0 58 Ni, was performed with two different model potentials—one with the folded potential normalized with a complex factor (OMP1) and the other with a hybrid potential composed of a renormalized folded real and a phenomenological imaginary (OMP2) potential components. All the model potentials predict similar energy dependent behaviour for the interaction potential around the barrier. The observed energy dependence of the strengths of the real and imaginary potentials corroborate with the dispersion relation prediction for both the 6 Lixa0+xa0 64 Ni and 6 Lixa0+xa0 58 Ni systems. Though the evidence of breakup is distinct in the energy variation of the potential strengths, close to the barrier the variation is more in the line of conventional threshold anomaly. Also the threshold behaviour of the interaction potential does not indicate any distinct isotopic dependence.

Elastic scattering and fusion cross sections for Be7,Li7+Al27 systems

Quasi-elastic-scattering and transfer reaction cross-section measurements were made for the {sup 7}Be+{sup 27}Al system at E{sub lab}=17, 19, and 21 MeV in the angular range {theta}{sub c.m.}=12 deg. An optical model (OM) analysis of the quasi-elastic scattering data was carried out. The fusion cross sections were derived at these energies by subtraction of the integrated transfer cross sections from the reaction cross sections obtained from the fits to quasi-elastic-scattering data. These fusion cross sections were found to be consistent with those obtained from the coupled-channels calculations. Elastic scattering and fusion cross sections were measured for the {sup 7}Li+{sup 27}Al system at E{sub lab}=10, 13, 16, 19, and 24 MeV. For elastic scattering the angular coverages were in the {theta}{sub lab}=12 deg. - 72 deg. range and for fusion the {alpha}-evaporation spectra from the compound nucleus were measured in the angular range {theta}{sub lab}=52 deg. - 132 deg. (142 deg. at 10 MeV). The elastic-scattering angular distributions were subjected to OM analysis. The {alpha}-evaporation spectra were reproduced with the statistical model calculations, and the fusion cross sections were extracted from them. The fusion cross sections were also extracted by subtraction of the integrated inelastic-scattering cross sections from the reaction cross sectionsmorexa0» obtained from the OM fits to the elastic-scattering data, and these fusion data were found to be consistent. The CCDEF calculations describe these data quite well. A comparison of the fusion data for the {sup 7}Be+{sup 27}Al and {sup 7}Li+{sup 27}Al systems shows a similar and consistent behavior.«xa0less

Coupled channel description of 16O+142,144,146Nd scattering around the Coulomb barrier using a complex microscopic potential

Abstract Angular distributions of elastic scattering and inelastic scattering from 2 + 1 state are measured for 16 O+ 142,144,146 Nd systems at several energies in the vicinity of the Coulomb barrier. The angular distributions are systematically analyzed in coupled channel framework. Renormalized double folded real optical and coupling potentials with DDM3Y interaction have been used in the calculation. Relevant nuclear densities needed to generate the potentials are derived from shell model wavefunctions. A truncated shell model calculation has been performed and the calculated energy levels are compared with the experimental ones. To simulate the absorption, a ‘hybrid’ approach is adopted. The contribution to the imaginary potential of couplings to the inelastic channels, other than the 2 + 1 target excitation channel, is calculated in the Feshbach formalism. This calculated imaginary potential along with a short ranged volume Woods–Saxon potential to simulate the absorption in fusion channel reproduces the angular distributions for 16 O+ 146 Nd quite well. But for 16 O+ 142,144 Nd systems additional surface absorption is found to be necessary to fit the angular distribution data. The variations of this additional absorption term with incident energy and the mass of the target are explored.

Sub-barrier fusion excitation for the system 7 Li+ 28 Si

Exploring the structure and reaction mechanism withloosely bound stable projectiles or with radioactive ionbeams (e.g. halo/skin nuclei), at sub- and near-barrierenergies, appears to be an interesting and challengingproblem at the present time. Recent theoretical studies[1, 2, 3, 4, 5, 6] have yielded new insights into the fusionreaction dynamics leading to enhancement/suppressionof fusion, weakening of usual threshold anomaly foundwith tightly bound projectiles and appearance of newtype of break-up threshold anomaly around the barrierenergy. The interplay among fusion, loose structure,breakup to the continuum, and transfer channels are con-sidered to be responsible for the above phenomena.Precise measurements exist for the fusion of looselybound stable projectiles with heavy targets like

Performance of a position sensitive low-pressure wire chamber (LPWC) having position readout from a separate sense wire plane: a critical analysis

Abstract The paper describes the operation of a simple one-dimensional LPWC from a completely different standpoint. The position output is derived from a separate position plane, where discrete resistances are soldered between two adjacent wires. Theoretical formulations for the position extraction are derived where the role of various detector parameters are dealt with. Position spectrum is shown for various choices of resistances varying from 50 Ω to 220 kΩ . Best position resolution and linearity is obtained for 33 kΩ though it violates the existing hypothesis.

Elastic scattering and fusion cross sections forBe7,Li7+Al27systems

Quasi-elastic-scattering and transfer reaction cross-section measurements were made for the {sup 7}Be+{sup 27}Al system at E{sub lab}=17, 19, and 21 MeV in the angular range {theta}{sub c.m.}=12 deg. An optical model (OM) analysis of the quasi-elastic scattering data was carried out. The fusion cross sections were derived at these energies by subtraction of the integrated transfer cross sections from the reaction cross sections obtained from the fits to quasi-elastic-scattering data. These fusion cross sections were found to be consistent with those obtained from the coupled-channels calculations. Elastic scattering and fusion cross sections were measured for the {sup 7}Li+{sup 27}Al system at E{sub lab}=10, 13, 16, 19, and 24 MeV. For elastic scattering the angular coverages were in the {theta}{sub lab}=12 deg. - 72 deg. range and for fusion the {alpha}-evaporation spectra from the compound nucleus were measured in the angular range {theta}{sub lab}=52 deg. - 132 deg. (142 deg. at 10 MeV). The elastic-scattering angular distributions were subjected to OM analysis. The {alpha}-evaporation spectra were reproduced with the statistical model calculations, and the fusion cross sections were extracted from them. The fusion cross sections were also extracted by subtraction of the integrated inelastic-scattering cross sections from the reaction cross sectionsmorexa0» obtained from the OM fits to the elastic-scattering data, and these fusion data were found to be consistent. The CCDEF calculations describe these data quite well. A comparison of the fusion data for the {sup 7}Be+{sup 27}Al and {sup 7}Li+{sup 27}Al systems shows a similar and consistent behavior.«xa0less

Elastic scattering and fusion cross sections for {sup 7}Be,{sup 7}Li+{sup 27}Al systems

Quasi-elastic-scattering and transfer reaction cross-section measurements were made for the {sup 7}Be+{sup 27}Al system at E{sub lab}=17, 19, and 21 MeV in the angular range {theta}{sub c.m.}=12 deg. An optical model (OM) analysis of the quasi-elastic scattering data was carried out. The fusion cross sections were derived at these energies by subtraction of the integrated transfer cross sections from the reaction cross sections obtained from the fits to quasi-elastic-scattering data. These fusion cross sections were found to be consistent with those obtained from the coupled-channels calculations. Elastic scattering and fusion cross sections were measured for the {sup 7}Li+{sup 27}Al system at E{sub lab}=10, 13, 16, 19, and 24 MeV. For elastic scattering the angular coverages were in the {theta}{sub lab}=12 deg. - 72 deg. range and for fusion the {alpha}-evaporation spectra from the compound nucleus were measured in the angular range {theta}{sub lab}=52 deg. - 132 deg. (142 deg. at 10 MeV). The elastic-scattering angular distributions were subjected to OM analysis. The {alpha}-evaporation spectra were reproduced with the statistical model calculations, and the fusion cross sections were extracted from them. The fusion cross sections were also extracted by subtraction of the integrated inelastic-scattering cross sections from the reaction cross sectionsmorexa0» obtained from the OM fits to the elastic-scattering data, and these fusion data were found to be consistent. The CCDEF calculations describe these data quite well. A comparison of the fusion data for the {sup 7}Be+{sup 27}Al and {sup 7}Li+{sup 27}Al systems shows a similar and consistent behavior.«xa0less