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V. V. Parkar

Bio: V. V. Parkar is an academic researcher from Bhabha Atomic Research Centre. The author has contributed to research in topics: Coulomb barrier & Elastic scattering. The author has an hindex of 20, co-authored 84 publications receiving 1029 citations. Previous affiliations of V. V. Parkar include Homi Bhabha National Institute & Tata Institute of Fundamental Research.


Papers
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Journal ArticleDOI
TL;DR: In this article, a detailed analysis of the angular distribution using coupled channels Born approximation calculations has provided clear evidence that the observed α + d events arise from a two-step process, i.e., direct transfer to the 2.186 MeV (3 + ) resonance in the α+ d continuum of 6Li followed by breakup, and are not due to final state interaction effects.

84 citations

Journal ArticleDOI
TL;DR: In this article, the effect of coupling of both the projectile and target excitations on the above quantities has been investigated, and the complete fusion cross sections, especially at above-barrier energies, have been found to be suppressed by ($20.5$) compared to the ones predicted by the coupled-channels calculations that do not include the couplings to the projectile continuum, indicating the loss of flux from the entrance channel before fusion.
Abstract: The excitation function for the complete fusion of $^{9}\mathrm{Be}$$+$$^{89}\mathrm{Y}$ has been measured at near-barrier energies, and the barrier distribution has been extracted from the fusion data. Coupled-channels calculations have been carried out to understand the effect of coupling of both the projectile and target excitations on the above quantities. The complete fusion cross sections, especially at above-barrier energies, have been found to be suppressed by ($20\ifmmode\pm\else\textpm\fi{}5$)% compared to the ones predicted by the coupled-channels calculations that do not include the couplings to the projectile continuum, indicating the loss of flux from the entrance channel before fusion. This conclusion is also supported by a considerable incomplete fusion cross section observed for this system. Fusion measurements for two more systems have been carried out, namely, for $^{4}\mathrm{He}$$+$$^{93}\mathrm{Nb}$ and $^{12}\mathrm{C}$$+$$^{89}\mathrm{Y}$, which involve tightly bound projectiles and form compound nuclei nearby to that formed in $^{9}\mathrm{Be}$$+$$^{89}\mathrm{Y}$ fusion. Comparison of the fusion data obtained for all three systems further confirms the suppression of complete fusion in the $^{9}\mathrm{Be}$$+$$^{89}\mathrm{Y}$ system. Systematics of the suppression factor observed for $^{9}\mathrm{Be}$ induced fusion in different mass targets is discussed.

57 citations

Journal ArticleDOI
TL;DR: In this article, the authors showed that the complete fusion excitation function at near barrier energies can be suppressed by 32% in the case of the Coulomb barrier penetration model with strongly bound projectiles forming a similar compound nucleus.
Abstract: Complete fusion excitation function for the $^{6}\mathrm{Li}+^{144}\mathrm{Sm}$ reaction has been measured at near barrier energies by the activation technique Coupled-channel calculations show an enhancement in fusion cross section at energies below the barrier compared to the one-dimensional barrier penetration model calculation, but they overpredict it in the entire energy range compared to the experimental data Reduced fusion cross sections for the present system at energies normalized to the Coulomb barrier were also found to be systematically lower than those with strongly bound projectiles forming a similar compound nucleus These two observations conclusively show that the complete fusion cross section, at above barrier energies, is suppressed by $~32%$ in the $^{6}\mathrm{Li}+^{144}\mathrm{Sm}$ reaction Reanalyses of existing fusion data for $^{7}\mathrm{Li}+^{165}\mathrm{Ho}$ and $^{7}\mathrm{Li}+^{159}\mathrm{Tb}$ also show a suppression compared to those with strongly bound projectiles, which contradicts earlier conclusions The fusion suppression factor seems to exhibit a systematic behavior with respect to the breakup threshold of the projectile and the atomic number of the target nucleus

57 citations

Journal ArticleDOI
TL;DR: In this article, the role played by the cluster structures of 7Li in understanding the reaction dynamics at energies around the Coulomb barrier was demonstrated, and it was inferred that massive transfer was the dominant mechanism for He 6 + p and He 5 + d configurations.

55 citations

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

49 citations


Cited by
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01 Apr 2001
TL;DR: In this paper, the reduced electric quadrupole transition probability, B(E2)↑, from the ground state to the first-excited 2+ state of even-even nuclides are given in Table I.
Abstract: Adopted values for the reduced electric quadrupole transition probability, B(E2)↑, from the ground state to the first-excited 2+ state of even–even nuclides are given in Table I. Values of τ, the mean life of the 2+ state; E, the energy; and β, the quadrupole deformation parameter, are also listed there. The ratio of β to the value expected from the single-particle model is presented. The intrinsic quadrupole moment, Q0, is deduced from the B(E2)↑ value. The product E×B(E2)↑ is expressed as a percentage of the energy-weighted total and isoscalar E2 sum-rule strengths. Table II presents the data on which Table I is based, namely the experimental results for B(E2)↑ values with quoted uncertainties. Information is also given on the quantity measured and the method used. The literature has been covered to November 2000. The adopted B(E2)↑ values are compared in Table III with the values given by systematics and by various theoretical models. Predictions of unmeasured B(E2)↑ values are also given in Table III.

955 citations

Journal ArticleDOI
TL;DR: In this paper, Belitz et al. presented a survey of the state-of-the-art in condensed-matter physics, focusing on the following papers: Condensed Matter Physics (Theoretical) J. IGNACIO CIRAC, Max-Planck-Institut für Quantenoptik Quantum Information RAYMOND E. GOLDSTEIN, University of Cambridge Biological Physics ARTHUR F. HEBARD and DAVID D. KAMIEN.
Abstract: Associate DIETRICH BELITZ, University of Oregon Editors: Condensed Matter Physics (Theoretical) J. IGNACIO CIRAC, Max-Planck-Institut für Quantenoptik Quantum Information RAYMOND E. GOLDSTEIN, University of Cambridge Biological Physics ARTHUR F. HEBARD, University of Florida Condensed Matter Physics (Experimental) RANDALL D. KAMIEN, University of Pennsylvania Soft Condensed Matter DANIEL KLEPPNER, Massachusetts Institute of Technology Atomic, Molecular, and Optical Physics (Experimental) PAUL G. LANGACKER, Institute for Advanced Study, Princeton University Particle Physics (Theoretical) VERA LÜTH, Stanford University Particle Physics (Experimental) DAVID D. MEYERHOFER, University of Rochester Physics of Plasmas and Matter at High-Energy Density WITOLD NAZAREWICZ, University of Tennessee, Oak Ridge National Laboratory Nuclear Physics JOHN H. SCHWARZ, California Institute of Technology Mathematical Physics FRIEDRICH-KARL THIELEMANN, Universität Basel Astrophysics Senior Assistant Editor: DEBBIE BRODBAR, APS Editorial Office American Physical Society

774 citations

Book
01 Dec 1984
TL;DR: In a recent review as mentioned in this paper, the authors reflect some of the shifts of emphasis that are occurring among the fields of astrophysics, nuclear physics, and elementary particle physics and discuss the role of rotational degrees of freedom in heavy-ion collisions at low and moderate energies.
Abstract: The contents of this review reflect some of the shifts of emphasis that are occurring among the fields of astrophysics, nuclear physics, and elementary particle physics. Particle physics has made great advances in the unification of the fundamental forces of nature. Discussions and planning for a next big step in accelerator-colliders are presented. The technology of superconducting magnet systems as well as the fundamental physical principles of particle accelerators are discussed. Also presented are: high-resolution electronic particle detectors; nuclear physics changes such as pion interactions within nuclei; discussion of future relativistic heavy-ion colliders; the role of rotational degrees of freedom in heavy-ion collisions at low and moderate energies; hyperon beta decays; and the analysis of materials via nuclear reaction techniques. Neutrinos, their interactions and possible masses, have an important bearing on cosmology and the matter density of the universe in addition to their inherent interest in the microscopic world and this is also examined.

676 citations

Journal ArticleDOI
TL;DR: In this paper, the authors give a balanced account of the experimental and theoretical advances acquired over the last decade in the field of near-barrier fusion reactions induced by weakly bound stable and unstable nuclei.

235 citations