The Experts below are selected from a list of 192 Experts worldwide ranked by ideXlab platform
Kouichi Hagino - One of the best experts on this subject based on the ideXlab platform.
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Systematic study of the surface diffuseness of Nuclear Potential with high precision large-angle quasi-elastic scattering
Nuclear Physics, 2010Co-Authors: H.m. Jia, Cheng-jian Lin, H.q. Zhang, F. Yang, Z.h. Liu, F. Jia, S.t. Zhang, Kouichi HaginoAbstract:Abstract The excitation functions of quasi-elastic scattering at a backward angle have been measured for the systems of 16O + 208Pb, 196Pt, 184W, and 154,152Sm at energies well below the Coulomb barrier. The surface diffuseness parameters of the Nuclear Potentials have been extracted from both single-channel and coupled-channels calculations. Considering the coupling effects, the extracted diffuseness parameters are a = 0.64 – 0.69 fm , which are close to the values extracted from the systematic analysis of elastic and inelastic scattering data. On the other hand, single-channel calculations give somewhat larger values in the range from 0.68 to 0.77 fm, especially for systems with deformed targets.
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Systematic study of the Nuclear Potential through high precision back-angle quasi-elastic scattering measurements
Physical Review C, 2007Co-Authors: Leandro Gasques, Maurits Evers, David Hinde, Mahananda Dasgupta, P. R. S. Gomes, Roberto Meigikos Dos Anjos, M. L. Brown, Matias Rodriguez, R. G. Thomas, Kouichi HaginoAbstract:High precision quasi-elastic scattering excitation functions have been measured at energies well below the Coulomb barrier for the reactions of $^{32}\mathrm{S}$ with $^{208}\mathrm{Pb}$, $^{197}\mathrm{Au}$, $^{186}\mathrm{W}$, and $^{170}\mathrm{Er}$. Single-channel and coupled-channels calculations have been performed to extract the diffuseness parameter of the Nuclear Potential. For the reactions involving near-spherical targets, both theoretical analyses give the same diffuseness parameter. On the other hand, for deformed systems, couplings are important even at deep sub-barrier energies. In general, the effect of couplings is to reduce the diffuseness parameter value extracted from a single-channel Potential. Single-channel fits to quasi-elastic scattering data result in $a=0.72\text{\ensuremath{-}}0.82$ fm, whereas coupled-channels calculations give diffuseness parameters in the range 0.58--0.75 fm.
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Systematic Failure of the Woods-Saxon Nuclear Potential to Describe Both Fusion and Elastic Scattering: Possible Need for a New Dynamical Approach to Fusion
Physical Review C, 2004Co-Authors: John Newton, David Hinde, Mahananda Dasgupta, Igor Gontchar, Rachel D Butt, Clyde Morton, Kouichi HaginoAbstract:A large number of precision fusion excitation functions, at energies above the average fusion barriers, have been fitted using the Woods-Saxon form for the Nuclear Potential in a barrier passing model of fusion. They give values for the empirical diffuseness parameter $a$ ranging between 0.75 and $1.5\phantom{\rule{0.3em}{0ex}}\mathrm{fm}$, compared with values of about $0.65\phantom{\rule{0.3em}{0ex}}\mathrm{fm}$ which generally reproduce elastic scattering data. There is a clear tendency for the deduced $a$ to increase strongly with the reaction charge product ${Z}_{1}{Z}_{2}$, and some evidence for the effect of Nuclear structure on the value of $a$, particularly with regard to the degree of neutron richness of the fusing nuclei, and possibly with regard to deformation. The measured fusion-barrier energies are always lower than those of the bare Potentials used, which is expected as a result of adiabatic coupling to high energy collective states. This difference increases with increasing ${Z}_{1}{Z}_{2}$ and calculations show that about $1∕3$ of it may be attributed to coupling to the isoscalar giant-quadrupole resonances in the target and projectile. Coupling to all giant resonances may account for a significant part. Fluctuations about the trend line may be due to systematic errors in the data and/or structure effects such as coupling to collective octupole states. Previously suggested reasons for the large values of $a$ have been related to departures from the Woods-Saxon Potential and to dissipative effects. This work suggests that the apparently large values of $a$ may be an artifact of trying to describe the dynamical fusion process by use of a static Potential. Another partial explaination might reside in fusion inhibition, due for example to deep-inelastic scattering, again a process requiring dynamical calculations.
Indu Sukumaran - One of the best experts on this subject based on the ideXlab platform.
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Comparative study of the alpha decay of Hg isotopes using different forms of Nuclear Potentials
Comptes Rendus Physique, 2018Co-Authors: K. P. Santhosh, Indu SukumaranAbstract:Abstract The alpha decay half-lives of Hg isotopes within the range A = 171 – 212 have been studied using 25 different versions of Nuclear Potentials to select the suitable form of Nuclear Potential for alpha decay studies. The computed standard deviations suggested that the apt Potential is BW 91 with a deviation 0.133. The next low deviation is shown by Proximity 1966, Proximity 1984, and Proximity 2003-I, II with deviations less than 0.2. Concerning other Potentials, the fact we observed is that almost all the Potentials possess a standard deviation less than one. The universal curve studied for alpha decay is observed to show straight line behavior irrespective of the Nuclear Potential used. Since the predicted alpha half-lives match well the experimental values, the half-lives of certain new Hg alpha emitters have been predicted by the present method.
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Alpha decay studies on Po isotopes using different versions of Nuclear Potentials
The European Physical Journal A, 2017Co-Authors: K. P. Santhosh, Indu SukumaranAbstract:The alpha decays from 186-224Po isotopes have been studied using 25 different versions of Nuclear Potentials so as to select a suitable Nuclear Potential for alpha decay studies. The computed standard deviation of the calculated half-lives in comparison with the experimental data suggested that proximity 2003-I is the apt form of Nuclear Potential for alpha decay studies as it possesses the least standard deviation, $ \sigma =0.620$ . Among the different proximity Potentials, proximity 1966 ( $ \sigma =0.630$ and proximity 1977 ( $ \sigma =0.636$ , are also found to work well in alpha decay studies with low deviation. Among other versions of Nuclear Potentials (other than proximity Potentials), Bass 1980 is suggested to be a significant form of Nuclear Potential because of its good predictive power. However, while the other forms of Potentials are able to reproduce the experimental data to some extent, these Potentials cannot be considered as apposite Potentials for alpha decay studies in their present form. Since the experimental correlation of the models is noticed to be satisfying, the alpha decay half-lives of certain Po isotopes that are not detected experimentally yet have been predicted.
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Heavy particle decay studies using different versions of Nuclear Potentials
The European Physical Journal Plus, 2017Co-Authors: K. P. Santhosh, Indu SukumaranAbstract:The heavy particle decay from 212-240Pa , 219-245Np , 228-246Pu , 230-249Am , and 232-252Cm leading to doubly magic 208Pb and its neighboring nuclei have been studied using fourteen versions of Nuclear Potentials. The study has shown that the barrier penetrability as well as the decay half-lives are found to vary with the Nuclear Potential used. The investigated decay events of the emission of the clusters 22Ne , 24Ne , 26Mg , 28Mg , 32Si and 33Si are not experimentally detected yet but may be detectable in the future. As most of the half-lives predicted are found to lie within the experimental upper limit, T 1/2 < 1030 s, our predictions will be a guide to future experimental design. The GN plots studied are linear for different cluster emissions from different parents with varying slopes and intercepts. Also, it is to be noted that the linearity of the GN plots is unaltered using different Nuclear Potentials. The universal curve studied ( log10 T 1/2 vs. -ln P for various clusters emitted from various parents shows a linear behavior with the same slope and intercept irrespective of the Nuclear Potential used.
U. Van Kolck - One of the best experts on this subject based on the ideXlab platform.
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The time-reversal- and parity-violating Nuclear Potential in chiral effective theory
Nuclear Physics A, 2011Co-Authors: C. M. Maekawa, E. Mereghetti, J. De Vries, U. Van KolckAbstract:We derive the parity- and time-reversal-violating Nuclear interactions stemming from the QCD (theta) over bar term and quark/gluon operators of effective dimension 6: quark electric dipole moments, quark and gluon chromo-electric dipole moments, and two four-quark operators. We work in the framework of two-flavor chiral perturbation theory, where a systematic expansion is possible. The different chiral-transformation properties of the sources of time-reversal violation lead to different hadronic interactions. For all sources considered the leading-order Potential involves known one-pion exchange, but its specific form and the relative importance of short-range interactions depend on the source. For the (theta) over bar term, the leading Potential is solely given by one-pion exchange, which does not contribute to the deuteron electric dipole moment. In subleading order, a new two-pion-exchange Potential is obtained. Its short-range component is indistinguishable from one of two undetermined contact interactions that appear at the same order and represent effects of heavier mesons and other short-range QCD dynamics. One-pion-exchange corrections at this order are discussed as well. Published by Elsevier B.V
K. P. Santhosh - One of the best experts on this subject based on the ideXlab platform.
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Comparative study of the alpha decay of Hg isotopes using different forms of Nuclear Potentials
Comptes Rendus Physique, 2018Co-Authors: K. P. Santhosh, Indu SukumaranAbstract:Abstract The alpha decay half-lives of Hg isotopes within the range A = 171 – 212 have been studied using 25 different versions of Nuclear Potentials to select the suitable form of Nuclear Potential for alpha decay studies. The computed standard deviations suggested that the apt Potential is BW 91 with a deviation 0.133. The next low deviation is shown by Proximity 1966, Proximity 1984, and Proximity 2003-I, II with deviations less than 0.2. Concerning other Potentials, the fact we observed is that almost all the Potentials possess a standard deviation less than one. The universal curve studied for alpha decay is observed to show straight line behavior irrespective of the Nuclear Potential used. Since the predicted alpha half-lives match well the experimental values, the half-lives of certain new Hg alpha emitters have been predicted by the present method.
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Alpha decay studies on Po isotopes using different versions of Nuclear Potentials
The European Physical Journal A, 2017Co-Authors: K. P. Santhosh, Indu SukumaranAbstract:The alpha decays from 186-224Po isotopes have been studied using 25 different versions of Nuclear Potentials so as to select a suitable Nuclear Potential for alpha decay studies. The computed standard deviation of the calculated half-lives in comparison with the experimental data suggested that proximity 2003-I is the apt form of Nuclear Potential for alpha decay studies as it possesses the least standard deviation, $ \sigma =0.620$ . Among the different proximity Potentials, proximity 1966 ( $ \sigma =0.630$ and proximity 1977 ( $ \sigma =0.636$ , are also found to work well in alpha decay studies with low deviation. Among other versions of Nuclear Potentials (other than proximity Potentials), Bass 1980 is suggested to be a significant form of Nuclear Potential because of its good predictive power. However, while the other forms of Potentials are able to reproduce the experimental data to some extent, these Potentials cannot be considered as apposite Potentials for alpha decay studies in their present form. Since the experimental correlation of the models is noticed to be satisfying, the alpha decay half-lives of certain Po isotopes that are not detected experimentally yet have been predicted.
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Heavy particle decay studies using different versions of Nuclear Potentials
The European Physical Journal Plus, 2017Co-Authors: K. P. Santhosh, Indu SukumaranAbstract:The heavy particle decay from 212-240Pa , 219-245Np , 228-246Pu , 230-249Am , and 232-252Cm leading to doubly magic 208Pb and its neighboring nuclei have been studied using fourteen versions of Nuclear Potentials. The study has shown that the barrier penetrability as well as the decay half-lives are found to vary with the Nuclear Potential used. The investigated decay events of the emission of the clusters 22Ne , 24Ne , 26Mg , 28Mg , 32Si and 33Si are not experimentally detected yet but may be detectable in the future. As most of the half-lives predicted are found to lie within the experimental upper limit, T 1/2 < 1030 s, our predictions will be a guide to future experimental design. The GN plots studied are linear for different cluster emissions from different parents with varying slopes and intercepts. Also, it is to be noted that the linearity of the GN plots is unaltered using different Nuclear Potentials. The universal curve studied ( log10 T 1/2 vs. -ln P for various clusters emitted from various parents shows a linear behavior with the same slope and intercept irrespective of the Nuclear Potential used.
David Hinde - One of the best experts on this subject based on the ideXlab platform.
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Coulomb Nuclear interference as a tool to investigate the Nuclear Potential
Physical Review C, 2010Co-Authors: Maurits Evers, David Hinde, Mahananda Dasgupta, Duc Huy Luong, R. Rafiei, R. Du RietzAbstract:The sub-barrier excitation function of the octupole vibrational state at 2.615 MeV in {sup 208}Pb is analyzed within the coupled-channels framework. It is shown that the position of the minimum in the excitation function, which is due to the destructive interference of the Coulomb and Nuclear scattering amplitudes, is very sensitive to the Nuclear Potential for both the ground state and the octupole state. A different Nuclear Potential for the 3{sup -} state may arise from changes in the matter distribution of {sup 208}Pb due to the particle-hole excitations. The present analysis places a strong limit on the 3{sup -} Nuclear Potential diffuseness, giving a difference of only {Delta}a{sub 0}=0.011+-0.004 fm between the ground state and 3{sup -} state diffuseness.
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Systematic study of the Nuclear Potential through high precision back-angle quasi-elastic scattering measurements of 16 O and 32 S on various targets
AIP Conference Proceedings, 2009Co-Authors: Maurits Evers, David Hinde, Mahananda Dasgupta, Leandro GasquesAbstract:Elastic and inelastic scattering have proven an excellent method to probe the Nuclear Potential in the surface region [1]. A surface diffuseness parameter of around 0.63 fm is accepted as describing elastic and inelastic scattering data. A new method to determine the diffuseness was proposed [2] using high precision quasi‐elastic excitation functions at sub‐barrier energies, and at backward angles. In response to this proposal, we have made measurements for 32S+170Er, 186W, 197Au, 208Pb [3], and more recently for the reactions 16O+144,154Sm, 186W, 197Au, 208Pb [4].Both single channel and coupled‐channels calculations have been performed to extract the diffuseness parameter of the Nuclear Potential, assuming a Woods‐Saxon shape. For the reactions involving near‐spherical targets, both theoretical analyses give the same diffuseness parameter, as had been hoped, showing that the effect of couplings to intrinsic excited states in the target and projectile is negligible. On the other hand, for deformed systems...
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Systematic study of the Nuclear Potential through high precision back-angle quasi-elastic scattering measurements
Physical Review C, 2007Co-Authors: Leandro Gasques, Maurits Evers, David Hinde, Mahananda Dasgupta, P. R. S. Gomes, Roberto Meigikos Dos Anjos, M. L. Brown, Matias Rodriguez, R. G. Thomas, Kouichi HaginoAbstract:High precision quasi-elastic scattering excitation functions have been measured at energies well below the Coulomb barrier for the reactions of $^{32}\mathrm{S}$ with $^{208}\mathrm{Pb}$, $^{197}\mathrm{Au}$, $^{186}\mathrm{W}$, and $^{170}\mathrm{Er}$. Single-channel and coupled-channels calculations have been performed to extract the diffuseness parameter of the Nuclear Potential. For the reactions involving near-spherical targets, both theoretical analyses give the same diffuseness parameter. On the other hand, for deformed systems, couplings are important even at deep sub-barrier energies. In general, the effect of couplings is to reduce the diffuseness parameter value extracted from a single-channel Potential. Single-channel fits to quasi-elastic scattering data result in $a=0.72\text{\ensuremath{-}}0.82$ fm, whereas coupled-channels calculations give diffuseness parameters in the range 0.58--0.75 fm.
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Systematic Failure of the Woods-Saxon Nuclear Potential to Describe Both Fusion and Elastic Scattering: Possible Need for a New Dynamical Approach to Fusion
Physical Review C, 2004Co-Authors: John Newton, David Hinde, Mahananda Dasgupta, Igor Gontchar, Rachel D Butt, Clyde Morton, Kouichi HaginoAbstract:A large number of precision fusion excitation functions, at energies above the average fusion barriers, have been fitted using the Woods-Saxon form for the Nuclear Potential in a barrier passing model of fusion. They give values for the empirical diffuseness parameter $a$ ranging between 0.75 and $1.5\phantom{\rule{0.3em}{0ex}}\mathrm{fm}$, compared with values of about $0.65\phantom{\rule{0.3em}{0ex}}\mathrm{fm}$ which generally reproduce elastic scattering data. There is a clear tendency for the deduced $a$ to increase strongly with the reaction charge product ${Z}_{1}{Z}_{2}$, and some evidence for the effect of Nuclear structure on the value of $a$, particularly with regard to the degree of neutron richness of the fusing nuclei, and possibly with regard to deformation. The measured fusion-barrier energies are always lower than those of the bare Potentials used, which is expected as a result of adiabatic coupling to high energy collective states. This difference increases with increasing ${Z}_{1}{Z}_{2}$ and calculations show that about $1∕3$ of it may be attributed to coupling to the isoscalar giant-quadrupole resonances in the target and projectile. Coupling to all giant resonances may account for a significant part. Fluctuations about the trend line may be due to systematic errors in the data and/or structure effects such as coupling to collective octupole states. Previously suggested reasons for the large values of $a$ have been related to departures from the Woods-Saxon Potential and to dissipative effects. This work suggests that the apparently large values of $a$ may be an artifact of trying to describe the dynamical fusion process by use of a static Potential. Another partial explaination might reside in fusion inhibition, due for example to deep-inelastic scattering, again a process requiring dynamical calculations.
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Surface diffuseness of Nuclear Potential from heavy-ion fusion reactions
Nuclear Physics A, 2003Co-Authors: Igor Gontchar, David Hinde, Mahananda Dasgupta, John NewtonAbstract:Abstract Fits to high precision fusion cross sections at above-barrier energies require values of ≈1 fm for the diffuseness parameter of the Woods-Saxon Potential. This is large compared with the values deduced from elastic scattering. Double folding model calculations of the bare nucleus-nucleus Potential have been carried out to predict the fusion barrier energies and Nuclear Potential diffusenesses. Both the calculated barrier energies, and equivalent Potential diffusenesses at the barrier raddi, are generally lower than those found experimentally. These discrepancies raise questions about both the determination of the bare nucleus-nucleus Potential with the folding model, and the boundary of the effects of friction on the fusion process.
