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- Bhagwat, A., et al.
(författare)
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Investigation of band termination in the lower fp shell within the cranked relativistic mean field model
- 2013
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Ingår i: International Conference on Recent Trends in Nuclear Physics-2012 (ICRTNP 2012). - : AIP. - 9780735411470 ; , s. 105-108
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Konferensbidrag (refereegranskat)abstract
- The excitation energy difference (ΔE) between the terminating states built on the f7/2 n and d3/2 -1f 7/2 n+1 configurations (here, 'n' denotes the number of valence particles outside the 40Ca core and the particle hole excitation across the magic gap 20 is of proton type) in the lower fp shell are studied systematically within the framework of the cranked relativistic mean field model. The ΔE thus defined, depends predominantly on the f 7/2 - d3/2 shell gap, and its evolution as a function of neutron - proton asymmetry. The latter, in turn, depends on the isoscalar - isovector balance in the spin - orbit potential. Therefore, a systematic investigation of the difference ΔE is expected to test quantitatively the predicted shell gaps as a function of isospin. We find that: 1) the conventional NL3 parameter set over estimates the ΔE values, implying that the said shell gap is over - estimated in this parametrization and 2) the largest deviation between the calculated and the experimental values of ΔE is obtained for the nucleus with the smallest asymmetry value in the set of nuclei considered, and that the deviation decreases with increasing asymmetry, indicating that the in RMF parametrization considered, the isoscalar - isovector balance in the spin - orbit potential requires improvement. We carry out a re - fit of the RMF parameters to attempt a remedy to these two problems. We find that in addition to the binding energies and charge radii, if a constraint is put on the f7/2 - d3/2 shell gap in the fit to the Lagrangian parameters, the overall agreement of ΔE with the experiment improves significantly, without disturbing the agreement already achieved for the bulk properties of the nuclei spanning the entire periodic table. At a finer level, however, it is found that the isoscalar - isovector balance in the spin orbit interaction is required to be improved further. A detailed work in this direction is in progress.
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- Bhagwat, Ameeya, et al.
(författare)
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Microscopic description of measured reaction cross sections at low projectile energies
- 2006
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 73:2, s. 024604-
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Tidskriftsartikel (refereegranskat)abstract
- Systematic and consistent microscopic description of measured reaction cross sections at low projectile en-ergies is presented. Finite-range Glauber model (GM-F) along with the Coulomb modification is used. The required inputs, namely the neutron and proton density distributions of the relevant projectiles and the targets, are calculated in the relativistic mean field framework. The GM-F reproduces the experiment well. At high projectile energies both the GM-F and the zero-range Glauber model in the optical limit (GM-Z) yield almost identical results; however, the GM-F in general is superior at low projectile energies, as expected.
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| 6. |
- Bhagwat, Ameeya, et al.
(författare)
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Microscopic description of recently measured reaction cross sections of neutron-rich nuclei in the vicinity of the N=20 and N=28 closed shells
- 2008
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 77:2, s. 027602-
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Tidskriftsartikel (refereegranskat)abstract
- The reaction cross sections for neutron-rich nuclei with 7 <= Z <= 18 on a Si-28 target at intermediate energies (30-65A MeV) are calculated and are compared with the corresponding recently reported new measurements. A finite-range Glauber model along with a Coulomb modification is used. The required nucleon density distributions of the relevant projectiles and the targets are obtained in the relativistic mean field framework. The calculations reproduce the experiment well. A simple phenomenological modification of the zero-range Glauber model is proposed to incorporate the finite-range effects. This one-parameter expression is found to reproduce the experimental reaction cross sections quite well.
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| 7. |
- Bhagwat, Ameeya, et al.
(författare)
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Recently measured reaction cross sections with low energy fp-shell nuclei as projectiles : Microscopic description
- 2006
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 73:5, s. 054601-
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Tidskriftsartikel (refereegranskat)abstract
- The finite range Glauber model along with the Coulomb modification is used to analyze recently measured reaction cross sections with neutron-deficient Ga, Ge, As, Se, and Br isotopes as low-energy projectiles incident on Si-28 target. The required input, namely the neutron and proton density distributions of the relevant projectiles and the target, are calculated in the relativistic mean-field framework. Though the calculations qualitatively agree with the experiment, on the average, slightly overestimate the cross sections. A phenomenological expression with a single parameter is proposed that consistently improves the agreement with the experiment.
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- Bhagwat, Ameeya, et al.
(författare)
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Systematics of strong absorption radii and its relevance to the calculation of reaction cross sections
- 2009
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Ingår i: Journal of Physics G. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 36:2, s. 025105-
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Tidskriftsartikel (refereegranskat)abstract
- Based on the detailed analysis of the reaction cross sections obtained using the finite range Glauber model, a systematic study of strong absorption radii is carried out. A simple phenomenological expression is proposed to calculate reaction cross sections directly using the average nucleon-nucleon cross section for a given target-projectile combination at given energy. Reliability of the model expression is demonstrated through a variety of illustrative examples.
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| 9. |
- Bhagwat, Ameeya, et al.
(författare)
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The alpha-nucleus potential for fusion and decay
- 2008
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Ingår i: Journal of Physics G. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 35:6, s. 065109-
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Tidskriftsartikel (refereegranskat)abstract
- The alpha-nucleus fusion cross sections at energies around and below the barrier and the alpha-decay half lives are calculated in the semi-classical WKB approach using the same microscopic as well as empirical alpha-nucleus potentials. The microscopic potential is generated within the double-folding framework using M3Y nucleon-nucleon interaction along with the required neutron and proton density distributions calculated in the relativistic mean field theory. It is found that in spite of the excellent results for the half lives the fusion cross sections are underestimated by almost a factor of 3. However, the experimental fusion cross sections can be reproduced by introducing a norm factor (overall multiplicative factor to the potential) 1.3 but this then worsens the agreement for half lives. To verify this observation and for comparison the calculations are repeated using some of the representative empirical potentials available in the literature. The same conclusion emerged. The present study thus indicates that the same alpha-nucleus potential may yield accurate description for both the alpha-nucleus fusion cross sections and alpha-decay half lives only with the introduction of additional parameter(s).
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| 10. |
- Gambhir, Y. K., et al.
(författare)
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The superheavy elements : overview
- 2009
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Ingår i: INDIAN JOURNAL OF PHYSICS AND PROCEEDINGS OF THE INDIAN ASSOCIATION FOR THE CULTIVATION OF SCIENCE. - : Springer Science and Business Media LLC. - 0973-1458. ; 83:5, s. 661-669
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Tidskriftsartikel (refereegranskat)abstract
- Superheavy Elements (SHE) up to Z = 118 have been produced and studied. The Relativistic Mean Field (RMF) theory provides a reasonably good description of the ground state properties (binding energies, Q-values, deformation, radii, densities etc.) of these elements. Shell closures revealed by the vanishing/minimum pairing energy, are predicted for specific combination of neutron number N and proton number Z, specifically at N = 38, 164, 172, 184 and 198. Some of these have been confirmed experimentally. Future experiments are expected to validate the remaining predictions. Microscopic alpha-nucleus potential generated in the frame work of double folding model, employing the RMF densities for the daughter nucleus and the experimental densities for the alpha, along with the density dependent M3Y nucleon - nucleon interaction, qualitatively reproduce the experimental half lives for alpha - decay, calculated in the WKB approximation.
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| 11. |
- Prema, P., et al.
(författare)
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Study of alpha decay of super heavy elements using S-MATRIX and wkb methods
- 2008
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Ingår i: International Journal of Modern Physics E. - 0218-3013. ; 17:4, s. 611-629
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Tidskriftsartikel (refereegranskat)abstract
- A comparative study of the S-matrix and the WKB methods for the calculation of the half widths of alpha decay of super heavy elements is presented. The extent of the reliability of the WKB methods is demonstrated through simple illustrative examples. Detailed calculations have been carried out using the microscopic alpha-daughter potentials generated in the framework of the double-folding model using densities obtained in the relativistic mean field theories. We consider alpha-nucleus systems appearing in the decay chains of super heavy parent elements having A = 277, Z = 112 and A = 269, Z = 110. For negative and small positive log T-1/2 values the results from both methods are similar even though the S-matrix results should be considered to be more accurate. However, when log inverted perpendicular(1/2) values are large and positive, the width associated with such state is infinitesimally small and hence calculation of such width by the S-matrix pole search method becomes a numerically difficult problem. We find that overall, the WKB method is reliable for the calculation of half lives of alpha decay from heavy nuclei.
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