28 results on '"S. Appannababu"'
Search Results
2. Study of incomplete fusion reaction dynamics for the system 14N + 169Tm using the forward Recoil Range distribution technique
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S Kumar, Pankaj K Giri, R Kumar, Abhishek Yadav, Rahbar Ali, S Appannababu, Avinash Agarwal, S Mukherjee, Pushpendra P Singh, Vijay R Sharma, B P Singh, and Sunil Dutt
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Nuclear and High Energy Physics - Abstract
Studies in the past have demonstrated that complete fusion and incomplete fusion (ICF) dynamics are both significant just above the Coulomb barrier, yet the dynamics of ICF are elusive since they are so complex below 10 MeV/nucleon. In order to investigate low-energy ICF dynamics, we measured the forward recoil range distribution (FRRD) of evaporation residues (ERs) populated in the system 14N + 169Tm at energy ≈5.9 MeV/nucleon. A stack target-catcher activation technique followed by offline-γ-spectroscopy was used to estimate the FRRD of the ERs. In order to investigate a new parameter for describing ICF dynamics, the ICF fraction (F ICF(%)) for the present system was estimated from the range-integrated cross-sections and compared with other systems in the literature. The FRRD and range integrated cross-sections of seven ERs have been estimated experimentally. These cross-section results agree well with the experimental results obtained from the excitation functions. On re-investigation of entrance channel systematics for Q α -value of projectile, mass-asymmetry (μ MA), and Coulomb factor (Z P Z T), it has been found that the Q α -value systematic for 14N is not valid at all projectile energies. The FRRD measurement is one of the direct methods available to probe the complete and ICF contributions in ERs at low projectile energy. It has also been observed that the dynamics of ICF are not only dependent on the parameters of one entrance channel but on multiple entrance channels. We have also introduced the entrance channel parameter zeta (ζ) for the first time in ICF reactions to see the combined effect of mass-asymmetry (μ MA) and Z P Z T, as this parameter is better suited than μ MA and Z P Z T individually and has a linear dependency on F ICF(%).
- Published
- 2022
3. Fission fragment mass distribution studies inSi30+Hf180reaction
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G. Mohanto, C. Yadav, S. Nath, R. G. Thomas, Akhil Jhingan, B. R. S. Babu, K. M. Varier, A. Shamlath, P. Sugathan, S. Appannababu, M. Shareef, Ish Mukul, Avazbek Nasirov, A. M. Vinodkumar, S. Kailas, Devendra Singh, and E.V. Prasad
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Physics ,Nuclear and High Energy Physics ,Range (particle radiation) ,Mass distribution ,010308 nuclear & particles physics ,Fragment (computer graphics) ,Fission ,Mass ratio ,01 natural sciences ,medicine.anatomical_structure ,Saddle point ,0103 physical sciences ,medicine ,Atomic physics ,Nuclear Experiment ,010306 general physics ,Nucleus ,Bond cleavage - Abstract
Fission fragment mass–angle and mass ratio distributions have been measured for the 30Si + 180Hf reaction in the beam energy range 128–148 MeV. Quasifission signature is observed in this reaction, forming the compound system 210Rn. The results are compared with a very asymmetric reaction 16O + 194Pt, forming the same compound nucleus. Calculations assuming saddle point, scission point and DNS models have been performed to interpret the experimental results. The results strongly suggest the entrance channel dependence of quasifission in heavy ion collisions.
- Published
- 2016
4. Non-statistical decay and $\alpha$-correlations in the $^{12}$C+$^{12}$C fusion-evaporation reaction at 95 MeV
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L Morelli, G Baiocco, M D’Agostino, F Gulminelli, M Bruno, U Abbondanno, S Appannababu, S Barlini, M Bini, G Casini, M Cinausero, M Degerlier, D Fabris, N Gelli, F Gramegna, V L Kravchuk, T Marchi, A Olmi, G Pasquali, S Piantelli, S Valdré, Ad R Raduta, Istituto Nazionale di Fisica Nucleare, Sezione di Bologna (INFN, Sezione di Bologna), Istituto Nazionale di Fisica Nucleare (INFN), Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Laboratori Nazionali di Legnaro (LNL), Istituto Nazionale di Fisica Nucleare, Sezione di Padova (INFN, Sezione di Padova), PRIN 2010-2011, L Morelli, G Baiocco, M D’Agostino, F Gulminelli, M Bruno, U Abbondanno, S Appannababu, S Barlini, M Bini, G Casini, M Cinausero, M Degerlier, D Fabri, N Gelli, F Gramegna, V L Kravchuk, T Marchi, A Olmi, G Pasquali, S Piantelli, S Valdré, and Ad R Raduta
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Nuclear and High Energy Physics ,chemistry.chemical_element ,E = 95 Amev ,fusion evaporation reactions ,12C(12C ,[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex] ,01 natural sciences ,Oxygen ,Coincidence ,Observed deviation from statistical behaviour ,0103 physical sciences ,Neutron ,25.70.z, 24.60.Dr, 27.30.+t, 24.10.Pa ,010306 general physics ,Nuclear Experiment ,X) ,Physics ,NUCLEAR REACTIONS ,Measured Fusion-evaporation reactions ,Fusion ,010308 nuclear & particles physics ,3. Good health ,chemistry ,Phase space ,Excited state ,Alpha decay ,Atomic physics ,Excitation - Abstract
Multiple alpha coincidence and correlations are studied in the reaction $^{12}$C+$^{12}$C at 95 MeV for fusion-evaporation events completely detected in charge. Two specific channels with Carbon and Oxygen residues in coincidence with $\alpha$-particles are addressed, which are associated with anomalously high branching ratios with respect the predictions by Hauser-Feshbach calculations. Triple alpha emission appears kinematically compatible with a sequential emission from a highly excited Mg. The phase space distribution of $\alpha$-$\alpha$ coincidences suggests a correlated emission from a Mg compound, leaving an Oxygen residue excited above the threshold for neutron decay. These observations indicate a preferential $\alpha$ emission of $^{24}$Mg at excitation energies well above the threshold for $6-\alpha$ decay., Comment: 21 pages, 17 figures, second paper of a series of two
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- 2014
5. Thermal properties of light nuclei from12C +12C fusion–evaporation reactions
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L Morelli, G Baiocco, M D’Agostino, F Gulminelli, M Bruno, U Abbondanno, S Appannababu, S Barlini, M Bini, G Casini, M Cinausero, M Degerlier, D Fabris, N Gelli, F Gramegna, V L Kravchuk, T Marchi, A Olmi, G Pasquali, S Piantelli, S Valdré, Ad R Raduta, L Morelli, G Baiocco, M D’Agostino, F Gulminelli, M Bruno, U Abbondanno, S Appannababu, S Barlini, M Bini, G Casini, M Cinausero, M Degerlier, D Fabri, N Gelli, F Gramegna, V L Kravchuk, T Marchi, A Olmi, G Pasquali, S Piantelli, S Valdré, Ad R Raduta, Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), and Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)
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Physics ,NUCLEAR REACTIONS ,Nuclear and High Energy Physics ,Fusion ,010308 nuclear & particles physics ,Evaporation ,FOS: Physical sciences ,Charge (physics) ,deviation from statistical behaviour ,[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex] ,01 natural sciences ,Coincidence ,3. Good health ,Excited state ,0103 physical sciences ,Thermal ,Dissipative system ,Nuclear Experiment (nucl-ex) ,Atomic physics ,fusion evaporation reaction ,010306 general physics ,Nuclear Experiment ,Excitation - Abstract
The $^{12}$C+$^{12}$C reaction at 95 MeV has been studied through the complete charge identification of its products by means of the GARFIELD+RCo experimental set-up at INFN Laboratori Nazionali di Legnaro (LNL). In this paper, the first of a series of two, a comparison to a dedicated Hauser-Feshbach calculation allows to select a set of dissipative events which corresponds, to a large extent, to the statistical evaporation of highly excited $^{24}$Mg. Information on the isotopic distribution of the evaporation residues in coincidence with their complete evaporation chain is also extracted. The set of data puts strong constraints on the behaviour of the level density of light nuclei above the threshold for particle emission. In particular, a fast increase of the level density parameter with excitation energy is supported by the data. Residual deviations from a statistical behaviour are seen in two specific channels, and tentatively associated with a contamination from direct reactions and/or $\alpha$-clustering effects. These channels are studied in further details in the second paper of the series., Comment: 24 pages, 15 figures, first paper of a series of two
- Published
- 2014
6. Fission fragment angular distribution measurements for 16O +194Pt reaction at energies near the Coulomb barrier
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S. Appannababu, P. Sugathan, E.V. Prasad, B. R. S. Babu, S. Kailas, K. S. Golda, K. M. Varier, A. K. Saxena, R. G. Thomas, A. M. Vinodkumar, Bency John, and K. Mahata
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Physics ,Nuclear reaction ,Nuclear physics ,Nuclear and High Energy Physics ,Angular momentum ,Cluster decay ,Fission ,Saddle point ,Statistical parameter ,Coulomb barrier ,Moment of inertia ,Atomic physics ,Nuclear Experiment - Abstract
Fission fragment angular distributions have been measured for 16O + 194Pt reaction forming the compound system 210Rn, in the laboratory energy range from 79 to 90 MeV. The measured fission fragment anisotropies as a function of E c . m . / V B are compared with the predictions of standard saddle point statistical model ( sspm ). Anisotropies calculated using the average excitation energy and angular momentum values could not reasonably fit the experimental data. Statistical model calculations were performed using the pace with modified fission barrier and level density parameters. Fission probability, evaporation residue cross section and neutron multiplicity were simultaneously used to fix the statistical parameters. Model calculations incorporating the chance nature of fission decay and scaled values of the rotating finite range model (RFRM) moment of inertia could reasonably fit the fragment angular anisotropies.
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- 2012
7. Total reaction cross-sections for light weakly bound systems
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M. C. Morais, Adriana Barioni, J. M. B. Shorto, S. Appannababu, R. Pampa Condori, K. C. C. Pires, A. Lépine-Szily, P. N. de Faria, P. R. S. Gomes, J. Lubian, E. N. Cardozo, E Crema, D. S. Monteiro, Valdir Guimaraes, N. N. Deshmukh, Rubens Lichtenthäler, V. Morcelle, Carla Cristina Lopes, and Swagata Mukherjee
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Nuclear physics ,Physics ,Elastic scattering ,Nuclear and High Energy Physics ,Hadron ,Nuclear fusion ,Atomic physics ,Reduction methods - Abstract
We have measured the elastic scattering cross-section for 8Li + 9Be and 8Li + 51V systems at 19.6MeV and 18.5MeV, respectively. We have also extracted total reaction cross sections from the elastic scattering analysis for several light weakly bound systems using the optical model with Woods-Saxon and double-folding-type potentials. Different reduction methods for the total reaction cross-sections have been applied to analyze and compare simultaneously all the systems.
- Published
- 2010
8. Effect of projectile breakup on fission-fragment mass distributions in theLi6,7 + U238reactions
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S. Kailas, E.V. Prasad, P. K. Rath, P. Sugathan, Neelam Singh, Akhil Jhingan, B. R. Behera, A. Pal, D. Chattopadhyay, S. Santra, S. Appannababu, Suparna Sodaye, K. S. Golda, Varinderjit Singh, and B. K. Nayak
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Physics ,Nuclear and High Energy Physics ,Full width at half maximum ,Mass distribution ,Proton ,Fission ,Projectile ,Nuclear Theory ,Coulomb barrier ,Atomic physics ,Nuclear Experiment ,Threshold energy ,Breakup - Abstract
Background: Detailed studies on the effect of the breakup of weakly bound projectile on fission are scarce. Distinguishing the events of compound nuclear (CN) fission from the breakup or transfer induced fission to understand the properties of measured fission fragments is difficult but desirable.Purpose: To investigate the effect of projectile breakup and its breakup threshold energy on fission-fragment (FF) mass distributions and folding angle distributions for $^{6,7}\mathrm{Li} + ^{238}\mathrm{U}$ reactions and find out the differences in the properties of the fission events produced by complete fusion (CF) from the total fusion (TF).Methods: The FF mass and folding angle distributions have been measured at energies around the Coulomb barrier using gas detectors by time-of-flight technique. The results are compared with the ones involving tightly bound projectiles as well as predictions from systematics to bring out the effect of the breakup.Results: A sharp increase in the peak to valley (P:V) ratio of FF mass distribution with the decrease in bombarding energy for $^{6,7}\mathrm{Li} + ^{238}\mathrm{U}$ reactions is observed when all events are assumed to be CN fission. As the beam energy falls through the fusion barrier, the full width half maximum (FWHM) of the FF folding angle distribution is found to increase at sub-barrier energies, unlike the reactions involving tightly bound projectiles where a linear decrease in FWHM is expected. By selecting pure CN events from the scatter plot of the velocity components of the composite nuclei, the energy dependence of the deduced FWHM is found to be consistent with the ones involving tightly bound projectiles. Similarly, the P:V ratio obtained for the selected CN events is consistent with the theoretical calculations as well as the experimental data for the proton induced reaction forming similar CN.Conclusions: The presence of projectile breakup induced fission and a relatively low breakup threshold for $^{6}\mathrm{Li}$ compared to $^{7}\mathrm{Li}$ explains the observed differences in the energy dependence of the P:V ratio and the FWHM of FF folding angle distributions for CF and TF fission in the present reactions.
- Published
- 2014
9. A new study of 25Mg $(\alpha, n)$ 28Si angular distributions at $E_{\alpha} =3-5$ MeV
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Rosanna Depalo, M. Cinausero, R. Menegazzo, N. Blasi, C. Rossi Alvarez, Tommaso Marchi, O. Wieland, D. Fabris, S. Appannababu, P. F. Mastinu, Antonio Caciolli, G. Montagnoli, G. Collazuol, M. Degerlier, V. Rigato, F. Gramegna, Carlo Broggini, and Mario Leone
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Physics ,Nuclear and High Energy Physics ,Milky Way ,Hadron ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Galaxy ,Neutron spectroscopy ,law.invention ,Nuclear physics ,Astrophysics - Solar and Stellar Astrophysics ,law ,Nucleosynthesis ,Van de Graaff generator ,Nuclear fusion ,Neutron ,Nuclear Experiment - Abstract
The observation of $^{26}$Al gives us the proof of active nucleosynthesis in the Milky Way. However the identification of the main producers of $^{26}$Al is still a matter of debate. Many sites have been proposed, but our poor knowledge of the nuclear processes involved introduces high uncertainties. In particular, the limited accuracy on the $^{25}$Mg($\alpha$,n)$^{28}$Si reaction cross section has been identified as the main source of nuclear uncertainty in the production of $^{26}$Al in C/Ne explosive burning in massive stars, which has been suggested to be the main source of $^{26}$Al in the Galaxy. We studied this reaction through neutron spectroscopy at the CN Van de Graaff accelerator of the Legnaro National Laboratories. Thanks to this technique we are able to discriminate the ($\alpha$,n) events from possible contamination arising from parasitic reactions. In particular, we measured the neutron angular distributions at 5 different beam energies (between 3 and 5 MeV) in the \ang{17.5}-\ang{106} laboratory system angular range. The presented results disagree with the assumptions introduced in the analysis of a previous experiment., Comment: 9 pages, 9 figures - accepted by EPJA
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- 2014
10. Anomalous deviations from statistical evaporation spectra for the decay of the73Br and77Rb compound systems
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Rohit Sandal, P. Sugathan, B. R. Behera, Gurpreet Singh, A. Kumar, K. P. Singh, S. Nath, N. Madhavan, Varinderjit Singh, E.V. Prasad, Akhil Jhingan, H B Singh, Maninder Kaur, Gulzar Singh, S. Appannababu, Sunil Kalkal, J. Gehlot, K. S. Golda, and Davinder Siwal
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Physics ,Nuclear and High Energy Physics ,Proton ,Neutron emission ,Nuclear Theory ,Binding energy ,Neutron ,Atomic physics ,Proton emission ,Nuclear Experiment ,Charged particle ,Excitation ,Spectral line - Abstract
Background: Several inclusive and few exclusive [evaporation residue (ER) gated] measurements for symmetric systems reported in the literature describe the anomalous deviations of light particle evaporation spectra from the statistical model predictions. However, no consistent description exists for these deviations.Purpose: To establish the consistent interpretation of reported anomalous deviations.Method: The inclusive and exclusive measurements of $\ensuremath{\alpha}$-particle, proton, and neutron spectra were carried out for the fusion of two relatively symmetric systems ${}^{28}$Si + ${}^{45}$Sc (E${}_{\mathrm{lab}}$ = 125 MeV and l${}_{\mathrm{max}}$ = 47$\ensuremath{\hbar}$) and ${}^{32}$S + ${}^{45}$Sc (E${}_{\mathrm{lab}}$ = 125 MeV and l${}_{\mathrm{max}}$ = 43$\ensuremath{\hbar}$) leading to the compound nuclei ${}^{73}$Br and ${}^{77}$Rb with excitation energies 78 MeV and 71 MeV, respectively.Results: The experimental light particle spectra for both the reactions show anomalous deviations from the statistical model predictions. The charged particles spectra are found to be suppressed, whereas the neutron spectra exhibit a bump at the higher energy tail. These spectra are investigated in terms of the modification of the important ingredients of the statistical model viz. the level density parameter, rescaling of the yrast line, and the use of $l$ value suggested by the dynamical models.Conclusions: It is conjectured that the higher partial waves do not fuse, but result in the formation of a deformed dinuclear system. The binding energy of neutrons is reduced while those for protons and $\ensuremath{\alpha}$ particles are enhanced in the deformed dinuclear system as compared to those in the shape-equilibrated system. Hence, the higher partial waves inhibit their contributions to the $\ensuremath{\alpha}$-particle spectra and lead to the preshape equilibrium of neutrons and protons, with the neutron emission dominating over the proton emission.
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- 2014
11. Lifetime measurement of high spin states in 75Kr
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S. C. Pancholi, S. Appannababu, R. Kumar, S. Muralithar, G. Mahanto, R. Palit, Z. Naik, I. Mehrotra, K. Maurya, D. Choudhury, Yang Sun, R. P. Singh, J. A. Sheikh, A. K. Jain, S. Kumar, Dinesh Negi, R. K. Bhowmik, H. C. Jain, T. Trivedi, A. Dhal, M. K. Raju, and Yunqi Yang
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Nuclear physics ,Physics ,Nuclear and High Energy Physics ,Spin states ,Attenuation ,SHELL model ,Quadrupole ,Parity (physics) ,Atomic physics - Abstract
The lifetimes of high spin states of 75 Kr have been determined via 50 Cr ( 28 Si, 2pn) 75 Kr reaction in positive parity band using the Doppler-shift attenuation method. The transition quadrupole moments Q t deduced from lifetime measurements have been compared with 75 Br. Experimental results obtained from lifetime measurement are interpreted in the framework of projected shell model.
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- 2010
12. Complete fusion in7Li+144,152Sm reactions
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S. K. Pandit, A. Pal, P. K. Rath, S. Appannababu, Sushil K. Sharma, B. K. Nayak, S. Kailas, K. Ramachandran, D. Patel, R. Palit, Neelam Singh, K. Mahata, S. Santra, and A. Parihari
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Physics ,Nuclear and High Energy Physics ,Fusion ,Coulomb barrier ,Coulomb excitation ,Atomic physics ,Coupling (probability) - Abstract
Complete fusion cross sections for ${}^{7}$Li+${}^{144,152}$Sm reactions have been measured at energies around the Coulomb barrier by offline $\ensuremath{\gamma}$-counting technique. Measured cross sections for the above two reactions are found to be similar at energies well above the Coulomb barrier, however, at sub-barrier energies the cross sections for the ${}^{7}$Li+${}^{152}$Sm system are much higher compared to the ${}^{7}$Li+${}^{144}$Sm system, manifesting the effect of target deformation. Cross sections for the present reactions at above-barrier energies are found to be larger than previously measured reactions involving ${}^{6}$Li projectile with the same targets, possibly due to smaller breakup probability of ${}^{7}$Li than ${}^{6}$Li. Coupled-channels calculations show that the experimental fusion cross sections for both the systems are enhanced at subbarrier energies and suppressed at above-barrier energies compared to the respective one-dimensional barrier penetration model predictions. The calculations by different models show that the measured complete fusion cross sections at above-barrier energies are suppressed up to $\ensuremath{\sim}$25% compared to the theoretical predictions. It also reveals that a large part of the suppression could be due to inelastic and transfer coupling.
- Published
- 2013
13. Evidence of quasifission in asymmetric reactions forming the250Cf compound system
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H. J. Wollersheim, Devendra Singh, K. S. Golda, R. G. Thomas, E.V. Prasad, J. Gehlot, Ish Mukul, P. Sugathan, S. Appannababu, Akhil Jhingan, C. Yadav, and R. K. Choudhury
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Physics ,Nuclear and High Energy Physics ,Computational chemistry ,Compound system - Published
- 2012
14. Shears mechanism in109In
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Devendra Singh, Rakesh Kumar Sinha, T. Trivedi, Santosh Roy, S. Kumar, S. Appannababu, Dinesh Negi, A. K. Bhati, Vikas Kumar, G. Mohanto, D. Choudhury, S. C. Pancholi, Jatinder Kaur, R. Kumar, A. Dhal, M. K. Raju, S. Muralithar, Rajeev Singh, and R. K. Bhowmik
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Physics ,Nuclear and High Energy Physics ,Spin states ,Atomic physics ,Beam energy - Abstract
High spin states of ${}^{109}$In were investigated using the reaction ${}^{96}$Zr(${}^{19}$F, 6n)${}^{109}$In at a beam energy of 105 MeV. New level sequences have been found in this nucleus. In an earlier known band, the ordering of some of the transitions have been changed and assigned a three-quasiparticle $\ensuremath{\pi}$(g${}_{9/2}$)${}^{\ensuremath{-}1}$ $\ensuremath{\bigotimes}$ $\ensuremath{\nu}$[h${}_{11/2}$(d${}_{5/2}$/g${}_{7/2}$)] configuration. Similar three-quasiparticle bands have also been found earlier in lighter mass ${}^{105}$In and ${}^{107}$In nuclei. Systematics of these bands in ${}^{105}$In, ${}^{107}$In, and ${}^{109}$In nuclei are discussed in the present work within the framework of the tilted axis cranking model.
- Published
- 2012
15. Investigation of the threshold anomaly in the near-barrier elastic scattering of 7Li on 116Sn
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D. Patel, A. K. Saxena, E. T. Mirgule, S. Santra, R. K. Choudhury, N. N. Deshmukh, B. K. Nayak, J. Lubian, S. Appannababu, Dwaipayan Biswas, Swagata Mukherjee, and P. R. S. Gomes
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Physics ,Elastic scattering ,Nuclear and High Energy Physics ,Work (thermodynamics) ,Projectile ,Nuclear Theory ,Hadron ,Nuclear fusion ,Atomic physics ,Anomaly (physics) ,Nuclear Experiment ,Breakup ,Energy (signal processing) - Abstract
Elastic-scattering angular distributions of 7Li on 116Sn have been measured at different bombarding energies between 18 to 35 MeV. The effects of the weakly bound projectile breakup channel on the bombarding energy dependence of the interaction potential have been investigated. In this work we present the experimental results, along with the theoretical analysis using Woods-Saxon potential to investigate the energy dependence of the interacting polarizing potentials. Total reaction cross-sections are also presented and discussed.
- Published
- 2011
16. Publisher’s Note: Fission fragment angular distributions in theBe9+Th232reaction [Phys. Rev. C83, 067601 (2011)]
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P. K. Rath, Swagata Mukherjee, L. S. Danu, S. Appannababu, R. Thomas, A. Saxena, Dwaipayan Biswas, B. V. John, R. K. Choudhury, B. K. Nayak, and Y. K. Gupta
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Nuclear physics ,Nuclear reaction ,Physics ,Nuclear and High Energy Physics ,Angular distribution ,Fragment (logic) ,Fission ,Total angular momentum quantum number ,Angular momentum coupling ,Rotational transition ,Atomic physics ,Spin (physics) - Published
- 2011
17. Fission fragment angular distributions in theBe9+Th232reaction
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Dwaipayan Biswas, L. S. Danu, R. K. Choudhury, P. K. Rath, A. K. Saxena, Y. K. Gupta, S. Appannababu, Bency John, Swagata Mukherjee, R. G. Thomas, and B. K. Nayak
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Physics ,Nuclear reaction ,Nuclear and High Energy Physics ,Cluster decay ,Fission ,Projectile ,Nuclear Theory ,Coulomb barrier ,Nuclear physics ,Electric field ,Atomic physics ,Nuclear Experiment ,Spin (physics) ,Anisotropy - Abstract
Fission fragment angular distributions have been measured for a $^{9}\mathrm{Be}$ $+$ $^{232}\mathrm{Th}$ system at four different beam energies around the Coulomb barrier. The experimental results on fission fragment anisotropies have been compared with predictions of the standard statistical saddle-point model (SSPM) and the preequilibrium fission (PEQ) model including projectile ground-state spin. It is observed that both SSPM and the PEQ model fail to reproduce the experimental results, indicating that projectile breakup may affect the fission fragment anisotropies.
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- 2011
18. Fission fragment mass distributions in reactions forming theFr213compound nucleus
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R. K. Choudhury, Dinesh Negi, R. G. Thomas, Swagata Mukherjee, N. N. Deshmukh, B. K. Nayak, E.V. Prasad, P. Sugathan, Akhil Jhingan, N. L. Singh, S. Appannababu, and P. K. Rath
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Nuclear reaction ,Physics ,Nuclear and High Energy Physics ,Angular momentum ,Isotope ,Mass distribution ,Fission ,Nuclear fission ,Nuclear Theory ,Coulomb barrier ,Atomic physics ,Mass ratio ,Nuclear Experiment - Abstract
The fission fragment mass angle correlations and mass ratio distributions have been investigated for the two systems $^{16}\mathrm{O}+^{197}\mathrm{Au}$ and $^{27}\mathrm{Al}+^{186}\mathrm{W}$, leading to the same compound nucleus $^{213}\mathrm{Fr}$ around the Coulomb barrier energies. Systematic analysis of the variance of the mass distributions as a function of temperature and angular momentum suggests true compound nuclear fission for both the reactions, indicating the absence of nonequilibrium fission processes.
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- 2011
19. Band structure and shape coexistence in56135Ba79
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T. Trivedi, L. Chaturvedi, R. K. Bhowmik, Sham S. Malik, H. C. Jain, A. Dhal, Z. Naik, S. Muralithar, R. P. Singh, R. Palit, Arvind K. Jain, S. Appannababu, R. Kumar, I. Mehrotra, Suresh Kumar, I. Mazumdar, S. C. Pancholi, V. Kumar, P. K. Joshi, Dinesh Negi, and Alpana Goel
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Physics ,Nuclear reaction ,Nuclear and High Energy Physics ,Angular momentum ,Condensed matter physics ,Spins ,media_common.quotation_subject ,Parity (physics) ,Asymmetry ,Excited state ,Atomic physics ,Electronic band structure ,Excitation ,media_common - Abstract
Excited states of ${}_{56}^{135}{\mathrm{Ba}}_{79}$ at high spins are studied using the reaction $^{130}\mathrm{Te}$($^{9}\mathrm{Be}$,$4n$)${}_{56}^{135}{\mathrm{Ba}}_{79}$ at $42.5$-MeV beam energy. The earlier known level scheme is extended up to $6.4$-MeV excitation energy and ($37/2$)$\ensuremath{\hbar}$ spin with the addition of several transitions. We have performed polarization asymmetry measurements for some of the strong transitions by using a Clover detector to assign the parity. A comparison of experimental data with the results of tilted axis cranking calculations based on various configurations indicates the coexistence of multiple minima in the triaxial deformation ($\ensuremath{\gamma}$), whereas axial symmetric deformation (${\ensuremath{\epsilon}}_{2}$) remains constant around $0.09$.
- Published
- 2010
20. High spin spectroscopy and shears mechanism inIn107
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Dinesh Negi, Jatinder Kaur, R. Kumar, S. C. Pancholi, S. Kumar, T. Trivedi, A. Dhal, M. K. Raju, Santosh Roy, A. K. Bhati, S. Muralithar, S. Appannababu, Vikas Kumar, Rajeev Singh, R. K. Bhowmik, Rakesh Kumar Sinha, and G. Mohanto
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Physics ,Nuclear and High Energy Physics ,Particle properties ,Spin states ,Neutron emission ,Atomic physics ,Spin (physics) ,Spectroscopy ,Beam energy ,Radioactive decay - Abstract
High spin states of $^{107}\mathrm{In}$ have been investigated using the reaction $^{94}\mathrm{Mo}$($^{16}\mathrm{O}$,$p2n$)$^{107}\mathrm{In}$ at a beam energy of $70$ MeV. A total of $62$ new $\ensuremath{\gamma}$ transitions have been placed in the level scheme and several $\ensuremath{\Delta}I=1$ sequences and one $\ensuremath{\Delta}I=2$ sequence have been found. Lifetime measurements using the Doppler-shift attenuation method (DSAM) have been carried out for band states of $\ensuremath{\Delta}I=1$ and $\ensuremath{\Delta}I=2$. A decreasing trend of $B(M1)$ strengths with increasing spin deduced for the $\ensuremath{\Delta}I=1$ band indicates the presence of a shears mechanism. The experimental data for this band are compared with the tilted axis cranking (TAC) calculations. The $\ensuremath{\Delta}I=2$ band has been found to be a deformed band with ${\ensuremath{\beta}}_{2}~0.2$.
- Published
- 2010
21. Conclusive evidence of quasifission in reactions forming theRn210compound nucleus
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E.V. Prasad, S. Appannababu, S. Nath, P. Sugathan, Gayatri Mohanto, K. S. Golda, A. M. Vinodkumar, S. Kailas, M. M. Musthafa, N. Madhavan, B. P. Ajith Kumar, Rohit Sandal, K. M. Varier, B. R. S. Babu, A. K. Sinha, Reeshu Singh, Bency John, Sunil Kalkal, R. G. Thomas, J. Gehlot, and Akhil Jhingan
- Subjects
Physics ,Nuclear reaction ,Nuclear and High Energy Physics ,Isotope ,Fission ,Conclusive evidence ,Mass ratio ,Nuclear physics ,Crystallography ,medicine.anatomical_structure ,medicine ,Nuclear Experiment ,Nucleus ,Isotopes of magnesium ,Oxygen-16 - Abstract
Fission fragment mass ratio distributions have been measured for the reactions $^{16}\mathrm{O}+^{194}\mathrm{Pt}$ and $^{24}\mathrm{Mg}+^{186}\mathrm{W}$, both leading to the same compound nucleus, $^{210}\mathrm{Rn}$, at near-barrier energies. The measured fission fragment mass ratio variances for $^{16}\mathrm{O}+^{194}\mathrm{Pt}$ and $^{24}\mathrm{Mg}+^{186}\mathrm{W}$ are compared with the calculations assuming compound nucleus formation. Mass variances of fragments from the $^{24}\mathrm{Mg}+^{186}\mathrm{W}$ reaction show a dramatic deviation from the compound nucleus behavior. This suggests strong evidence for onset of the quasifission process in this reaction.
- Published
- 2010
22. Enhanced0g.s.+→21+E2transition strength inSn112
- Author
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R. B. Garg, M. Górska, S. Muralithar, R. Kumar, S. Mandal, H. J. Wollersheim, R. K. Bhowmik, I. Kojouharov, Akhil Jhingan, S. Mukherjee, S. Appannababu, A K Sharma, R. P. Singh, J. Gerl, Jasmeet Kaur, Davinder Siwal, Pushpendra Singh, and P. Doornenbal
- Subjects
Physics ,Nuclear and High Energy Physics ,Theoretical physics - Published
- 2010
23. Publisher’s Note: Shape evolution of the highly deformedKr75nucleus examined with the Doppler-shift attenuation method [Phys. Rev. C80, 047302 (2009)]
- Author
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Dinesh Negi, G. Mahanto, Yang Sun, I. Mehrotra, R. Kumar, S. C. Pancholi, S. Appannababu, K. Maurya, A.K. Jain, Ying-Chun Yang, R. K. Bhowmik, J. A. Sheikh, Trupti H Trivedi, D. Choudhury, R. Palit, A. Dhal, S. Muralithar, M. K. Raju, R. P. Singh, Z. Naik, H. C. Jain, and S. Kumar
- Subjects
Physics ,Nuclear physics ,Nuclear and High Energy Physics ,symbols.namesake ,medicine.anatomical_structure ,Attenuation ,SHELL model ,symbols ,medicine ,Doppler effect ,Nucleus - Published
- 2009
24. Shape evolution of the highly deformedKr75nucleus examined with the Doppler-shift attenuation method
- Author
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D. Choudhury, Ying-Chun Yang, S. Appannababu, K. Maurya, R. Palit, S. Kumar, S. C. Pancholi, R. Kumar, G. Mahanto, H. C. Jain, Dinesh Negi, Yang Sun, I. Mehrotra, J. A. Sheikh, Rajeev Singh, R. K. Bhowmik, T. Trivedi, A. Dhal, M. K. Raju, S. Muralithar, Z. Naik, and Arvind K. Jain
- Subjects
Physics ,Nuclear and High Energy Physics ,Attenuation ,Parity (physics) ,symbols.namesake ,medicine.anatomical_structure ,Quadrupole ,symbols ,medicine ,Incident beam ,Neutron ,Isotopes of silicon ,Atomic physics ,Doppler effect ,Nucleus - Abstract
High-spin states of the $^{75}\mathrm{Kr}$ nucleus have been populated via the $^{50}\mathrm{Cr}$$($$^{28}\mathrm{Si}$,$2\mathit{pn})$$^{75}\mathrm{Kr}$ reaction at an incident beam energy of $90$ MeV. Lifetimes of nine states up to spin $I=33/2$ for the positive-parity band and seven states up to $I=27/2$ for the negative-parity band have been measured using the Doppler-shift attenuation method. The deduced transition quadrupole moments ${Q}_{t}$ of these bands have been compared to the projected shell-model calculations to gain insight into the evolution of collectivity for the two experimentally studied bands in $^{75}\mathrm{Kr}$.
- Published
- 2009
25. Absence of entrance channel effects in fission fragment anisotropies of theFr215compound nucleus
- Author
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S. Appannababu, Swadeshmukul Santra, N. L. Singh, R. G. Thomas, K. S. Golda, P. Sugathan, Swagata Mukherjee, B. K. Nayak, Akhil Jhingan, A. Saxena, G. Kiran Kumar, Hardev Singh, R. Kumar, R. K. Choudhury, and P. K. Rath
- Subjects
Physics ,Nuclear and High Energy Physics ,Cluster decay ,Fission ,media_common.quotation_subject ,Nuclear Theory ,Asymmetry ,medicine.anatomical_structure ,Fragment (logic) ,Critical mass ,Saddle point ,medicine ,Atomic physics ,Nuclear Experiment ,Anisotropy ,Nucleus ,media_common - Abstract
Fission fragment angular distributions have been measured for the reactions {sup 11}B+{sup 204}Pb and {sup 18}O+{sup 197}Au, both leading to the same compound nucleus {sup 215}Fr at near barrier energies. The measured fission fragment anisotropies as a function of E{sub c.m.}/V{sub B} are found to be consistent with the predictions of the standard saddle point statistical model (SSPM) for both the systems, suggesting the absence of entrance channel effects on fission fragment anisotropies even though the entrance channel mass asymmetries for both these systems fall on either side of the Bussinaro-Gallone critical mass asymmetry. The consistency of the present results with SSPM predictions can be understood within the framework of the pre-equilibrium fission model where fission before K equilibration is severely inhibited by the high values of ratios of fission barrier height to nuclear temperature.
- Published
- 2009
26. Quasi-elastic scattering in theLi6+Th232reaction
- Author
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D. S. Monteiro, P. R. S. Gomes, S. Appannababu, Swagata Mukherjee, B. K. Nayak, R. K. Choudhury, and J. Lubian
- Subjects
Excitation function ,Elastic scattering ,Physics ,Nuclear and High Energy Physics ,Distribution (mathematics) ,Scattering ,Projectile ,Coulomb barrier ,Atomic physics ,Breakup ,Isotopes of thorium - Abstract
Quasi-elastic scattering measurements at large backward angles have been carried out for the {sup 6}Li+{sup 232}Th system at energies around the Coulomb barrier. Barrier distribution has been obtained from the excitation function data. Coupled channel calculations using a double-folding potential as the bare potential have been performed. The disagreement between data and theoretical predictions shows a large breakup effect in the quasi-elastic scattering of a weakly bound projectile on a deformed target.
- Published
- 2009
27. Suppression of complete fusion in theLi6+Sm144reaction
- Author
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K. Mahata, Suresh Kumar, S. Appannababu, Swagata Mukherjee, S. Santra, R. K. Choudhury, Neelam Singh, V. V. Parkar, R. Palit, R.M. Tripathi, P. K. Rath, and B. K. Nayak
- Subjects
Excitation function ,Physics ,Nuclear reaction ,Nuclear and High Energy Physics ,Fusion ,Isotopes of lithium ,Electric field ,Coulomb barrier ,Atomic number ,Coulomb excitation ,Atomic physics - 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.
- Published
- 2009
28. Fusion measurements for the ${}^{18}$O+${}^{194}\mathrm{Pt}$ reaction and search for neutron shell closure effects
- Author
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S. K. Pal, K. S. Golda, Jhilam Sadhukhan, P. V. Laveen, S. Nath, B. R. S. Babu, A. Saxena, K. M. Varier, B. R. Behera, E.V. Prasad, S. Kailas, S. Appannababu, P. Sugathan, A. Shamlath, Rohit Sandal, A. M. Vinodkumar, N. Madhavan, J. Gehlot, R. G. Thomas, Varinderjit Singh, Bency John, Akhil Jhingan, and T. Varughese
- Subjects
Physics ,Nuclear and High Energy Physics ,Fusion ,Fission ,Nuclear Theory ,Dissipation ,medicine.anatomical_structure ,Saddle point ,Physics::Atomic and Molecular Clusters ,medicine ,Dissipative system ,Neutron ,Atomic physics ,Nuclear Experiment ,Anisotropy ,Nucleus - Abstract
Evaporation residue (ER) and fission cross sections were measured for the reaction O+ forming the compound nucleus 212Rn. Fission fragment angular distributions and anisotropies are consistent with the saddle point model predictions. Measured ER cross sections were fitted with statistical model calculations assuming shell-corrected free energy fission barrier height. The non-zero dissipation strength required to fit the ER cross section supports the dissipative nature of fission dynamics in heavy ion fusion. In the present study shell closure effects are not observed in the dissipation strength.
- Published
- 2015
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