Browsing by Author "Hardev Singh"

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Erratum to "Pre-compound neutron evaporation in low energy heavy ion fusion reactions" [Nucl. Phys. A 798 (2008) 1-15] (DOI:10.1016/j.nuclphysa.2007.10.007)
(2009) Ajay Kumar; Hardev Singh; Rajesh Kumar; Gulzar Singh; I.M. Govil; R.P. Singh; Rakesh Kumar; B.K. Yogi; K.S. Golda; S.K. Datta; G. Viesti
[No abstract available]
Level density parameter: A tool to study the particle spectra
(2010) Ajay Kumar; A. Kumar; G. Singh; Hardev Singh; R.P. Singh; Rakesh Kumar; K.S. Golda; I.M. Govil
The compound nucleus76Kr*is formed in the heavy-ion fusion reactions by an asymmetric entrance channel 12C+64Zn and the symmetric entrance channel 31P+45Sc at theexcitation energy of 75 MeV and angular momentum of 39 η. Neutron energy spectra of the asymmetric system (12C+64Zn) at different angles are well described by the statistical model predictions using the normal value of the level density parameter a = A/8 MeV-1. However,in the case of the symmetric system (31P+45Sc), the statistical model interpretation of the data requires the change in the value of a = A/10 MeV -1. The delayed evolution of thecompound system in case of the symmetric 31P+45Sc system may lead to the formation of a temperature equilibrated dinuclear complex, which may be responsible for the neutron emission at higher temperature, while the protons and alpha particles are evaporated afterneutron emission when the system is sufficiently cooled down and the higher λ-values do not contribute in the formation of the compound nucleus for the symmetric entrance channel in case of charged particle emission. © 2010 American Institute of Physics.
Pre-compound neutron evaporation in low energy heavy ion fusion reactions
(Elsevier, 2008) Ajay Kumar; Hardev Singh; Rajesh Kumar; I.M. Govil; R.P. Singh; Rakesh Kumar; B.K. Yogi; K.S. Golda; S.K. Datta; G. Viesti
Inclusive and exclusive neutron evaporation spectra have been studied from the fusion reactions at 80 MeV 12C on 46Ti and 131 MeV 31P on 27Al, populating the compound nucleus 58Ni at the excitation energy of 79.5 MeV but in different angular momentum ranges. The evaporation residues 53Fe, 55Fe and 56Co were identified by their characteristic γ-rays. The measured energy spectra of evaporated neutrons were compared with the predictions from statistical-model calculations. In case of the asymmetric system 12C + 46Ti, the neutron spectra are well reproduced, when compared with the results from statistical-model calculations with level density parameter a = A / 8 MeV-1. On the contrary, the experimental spectra for the symmetric system 31P + 27Al are found to be harder than the theoretical predictions with a = A / 8 MeV-1. In this case, a lower value of the level density parameter a = A / 10 MeV-1 seems to be required to reproduce the experimental results. The dependence of the energy spectra on the entrance channel is taken as an indication that, in case of the symmetric system, the neutrons are in part emitted from a temperature equilibrated di-nuclear complex at a higher temperature before the formation of the compound nucleus. © 2007 Elsevier B.V. All rights reserved.
Role of nuclear dissipation and entrance channel mass asymmetry in pre-scission neutron multiplicity enhancement in fusion-fission reactions
(American Physical Society, 2008) Hardev Singh; K.S. Golda; Santanu Pal; Ranjeet; Rohit Sandal; Bivash R. Behera; Gulzar Singh; Akhil Jhingan; R.P. Singh; P. Sugathan; M.B. Chatterjee; S.K. Datta; Ajay Kumar; G. Viesti; I.M. Govil
Pre-scission neutron multiplicities are measured for 12C+204Pb and 19F+197Au reactions at laboratory energies of 75-95 MeV for the C12 beam and 98-118 MeV for the F19 beam. The chosen projectile-target combinations in the present study lie on either side of the Businaro-Gallone mass asymmetry (αBG) and populate the Ra216 compound nucleus. The dissipation strength is deduced after comparing the experimentally measured neutron yield with the statistical model predictions which contains the nuclear viscosity as a free parameter. Present results demonstrate the combined effects of entrance channel mass asymmetry and the dissipative property of nuclear matter on the pre-scission neutron multiplicity in fusion-fission reactions. © 2008 The American Physical Society.
Study of angular momentum hindrance in heavy ion fusion reactions
(EDP Sciences, 2015) Ajay Kumar; A. Kumar; B.R. Behra; Hardev Singh; R.P. Singh; R. Kumar; K.S. Golda
The systematic study of the properties of hot nuclei by detecting the emitted charged particles and neutrons in coincidence with residual nuclei provides very critical information about its nuclear level density. These emitted particles capable to explain the behavior of the nucleus at various stages of the de-excitation cascade process. So, we have studied, a set of four compound nuclei, which were populated by mass-symmetric and mass-asymmetric channels, leading to the same compound nuclei, namely 80Sr∗, 79Se∗, 76Kr∗ and 58Ni∗at same excitation energies, respectively and found that the experimental neutron and charged particle spectra for symmetric channel show deviations at higher energies in comparison to the statistical model calculations. © Owned by the authors, published by EDP Sciences, 2014.
Study of nuclear reaction dynamics through particle evaporation
(2013) Ajay Kumar; A. Kumar; G. Singh; Hardev Singh; R.P. Singh; Rakesh Kumar; K.S. Golda; I.M. Govil
The compound nucleus 76Kr* is formed in the heavy-ion fusion reactions by an asymmetric entrance channel 12C+ 64Zn and the symmetric entrance channel 31P+ 45Sc at the excitation energy of 75 MeV and angular momentum of 39 ℏ. Neutron energy spectra of the asymmetric system (12C+ 64Zn) at different angles are well described by the statistical model predictions using the normal value of the level density parameter a = A/8 MeV -1. However, in the case of the symmetric system ( 31P+45Sc), the statistical model interpretation of the data requires the change in the value of a = A/10 MeV-1. The delayed evolution of the compound system in case of the symmetric 31P+ 45Sc system may lead to the formation of a temperature equilibrated dinuclear complex, which may be responsible for the neutron emission at higher temperature, while the protons and alpha particles are evaporated after neutron emission when the system is sufficiently cooled down and the higher ℓ-values do not contribute in the formation of the compound nucleus for the symmetric entrance channel in case of charged particle emission. © 2013 AIP Publishing LLC.