P. C. Srivastava

Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India

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Publications (30)51.26 Total impact

  • P. C. Srivastava, R. Sahu, V. K. B. Kota
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    ABSTRACT: In the present work we have interpreted recently available experimental data [H.M. David et al., Phys. Lett. B {\bf 726}, 665 (2013)] for low-lying $T=0$ and $T=1$ states in the odd-odd $N=Z$ nucleus $^{62}$Ga using large shell-model calculations within the full $f_{5/2}pg_{9/2}$ model space and deformed shell model based on Hartee-Fock intrinsic states in the same space. The calculations have been performed using jj44b effective interaction developed by B.A. Brown and A.F. Lisetskiy for this model space. The results obtained with the two models are similar and they are in good agreement with experimental data.
    09/2014;
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    ABSTRACT: Yrast and near-yrast states in odd-A Nb89 were investigated using the Cu65(Si28,2p2n) reaction at a beam energy of 105 MeV. The γ-ray coincidence events were recorded with the Indian National Gamma Array spectrometer. About 30 new transitions have been observed extending the level structure of this nucleus up to spin 45/2ℏ and excitation energy of 10.5 MeV. Large-scale shell model calculations were performed using the effective interactions JUN45 and jj44b to understand the structure of the observed states. Reasonable agreement between the experimental observation and shell model calculations suggests that no cross-shell excitations are important up to the maximum spin observed in the current experiment
    Physical Review C 07/2014; 90(1):014306. · 3.72 Impact Factor
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    ABSTRACT: High spin states of Zr88 were populated with Se80(C13, 5n) fusion evaporation reaction. A thin target as well as Au backed target were used in two different experiments for the present study. Excited levels of Zr88 have been observed up to spin ̃20ℏ and an excitation energy of ̃10 MeV. Spin and parity of most of the states have been determined from directional correlation and polarization measurements. The level scheme was substantially extended with the addition of a number of high spin states and transitions. The comparison of the measured levels of Zr88 with large shell model calculations based on the full unrestricted f5/2pg9/2 model space established the dominance of shell-model excitation up to the highest observed spin.
    Physical Review C 04/2014; 89(4):044315. · 3.72 Impact Factor
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    P. C. Srivastava, Vikas Kumar, M. J. Ermamatov
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    ABSTRACT: In this work nuclear structure properties of $^{86,87,88,89}$Y isotopes have been investigated using large-scale shell-model calculations within the full $f_{5/2}pg_{9/2}$ model space. The calculations have been performed with JUN45 and jj44b effective interactions that have been proposed for use in the $f_{5/2}$, $p_{3/2}$, $p_{1/2}$, $g_{9/2}$ model space for both protons and neutrons. Reasonable agreement between experimental and calculated values are obtained. This work will add more information to previous study by projected shell model [Eur. Phys. J. A 48, 138 (2012)] where full-fledged shell model calculations proposed for these nuclei.
    01/2014;
  • R Sahu, P C Srivastava, V K B Kota
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    ABSTRACT: Nuclear transition matrix elements (NTME) for neutrinoless positron double beta decay (0νβ+β+ and 0νβ+EC) of 64Zn, 74Se, 78Kr and 84Sr nuclei, which are in the A = 60–90 region, are calculated within the framework of the deformed shell model (DSM) based on Hartree–Fock states. For 64Zn, GXPF1A interaction in 1f7/2, 2p3/2, 1f5/2 and 2p1/2 space with 40Ca as the core is employed. Similarly for 74Se, 78Kr and 84Sr nuclei, 56Ni is taken as the inert core employing a modified Kuo interaction in 2p3/2, 1f5/2, 2p1/2 and 1g9/2 space. After ensuring that the DSM gives a good description of the spectroscopic properties of low-lying levels in the four nuclei considered, the NTME are calculated. The half-lives deduced with these NTME, assuming the neutrino mass is 1 eV, are smallest for 78Kr with the half-life for β+EC decay being ~1027 yr. For all others, the half-lives are in the range of ~1028–1029 yr.
    Journal of Physics G Nuclear and Particle Physics 08/2013; 40(9):095107. · 5.33 Impact Factor
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    P. C. Srivastava, M. J. Ermamatov
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    ABSTRACT: Comprehensive set of shell model calculations for $^{78-84}$Se isotopes have been performed with recently derived interactions, namely JUN45 and jj44b for ${f_{5/2}pg_{9/2}}$ space. To study the importance of the proton excitations across Z=28 shell in this region mentioned by Cheal {\it et al.} [Phys. Rev. Lett. {\bf104}, 252502 (2010)], calculation for ${fpg_{9/2}}$ valence space using an ${fpg}$ effective interaction with $^{48}$Ca as core and imposing a truncation has also been performed. Comparison of the calculations with experimental data show that the predicted results of jj44b interaction are in good agreement with experimental data.
    Physica Scripta 04/2013; 88(4). · 1.03 Impact Factor
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    P C Srivastava, M J Ermamatov, Irving O Morales
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    ABSTRACT: In the present work recently available experimental data (Astier et al 2012 Phys. Rev. C 85 064316) for the high-spin states of five N = 82 isotones, 136 54Xe, 137 55Cs, 138 56Ba, 139 57La and 140 58Ce have been interpreted with shell model calculations. The calculations have been performed in the 50–82 valence shell composed of 1g7/2, 2d5/2, 1h11/2, 3s1/2 and 2d3/2 orbitals. We have compared our results with the available experimental data for excitation energies including high-spin states, occupancy numbers and transition probabilities. As expected the structure of these isotones are due to proton excitations across the Z = 50 shell. The structure of the positive-parity states are mainly from (πg7/2πd5/2)n and (πg7/2πd5/2)n − 2(πh11/2)2 configurations, while the negative-parity states have a (πg7/2πd5/2)n(πh11/2)1 configuration. Additionally, for the 136 54Xe, 137 55Cs and 138 56Ba isotones the excitation of the neutrons across the N = 82 gap is important.
    Journal of Physics G Nuclear and Particle Physics 01/2013; 40(3):035106. · 5.33 Impact Factor
  • DAE Nuclear Physics symposium 2012; 12/2012
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    P. C. Srivastava, M. J. Ermamatov
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    ABSTRACT: We have interpreted recently measured experimental data of $^{77}$Ge, and also for $^{73,75,79,81}$Ge isotopes in terms of state-of-the-art shell model calculations. Excitation energies, B(2) values, quadrupole moments and magnetic moments are compared with experimental data when available. The calculations have been performed with the recently derived interactions, namely with JUN45 and jj44b for ${f_{5/2}pg_{9/2}}$ space. We have also performed calculation for ${fpg_{9/2}}$ valence space using an ${fpg}$ effective interaction with $^{48}$Ca core and imposing a truncation to study the importance of the proton excitations across the Z=28 shell in this region. The predicted results of jj44b interaction are in good agreement with experimental data.
    Physics of Atomic Nuclei 10/2012; 76(6). · 0.54 Impact Factor
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    ABSTRACT: In this work, the structure of 32-39P isotopes is described in the framework of stateof-the-art large-scale shell-model calculations, employing the code ANTOINE with three modern effective interactions: SDPF-U, SDPF-NR and the extended pairing plus quadrupole-quadrupoletype forces with inclusion of monopole interaction (EPQQM). Protons are restricted to fill the sd shell, while neutrons are active in the sd - pf valence space. Results for positive and negative level energies and electromagnetic observables are compared with the available experimental data.
    10/2012;
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    ABSTRACT: Near yrast states in 89Zr were investigated up to high spin using the fusion evaporation reaction 80Se(13C, 4n) at an incident beam energy of 50 MeV. Excited levels of 89Zr have been observed up to ∼10 MeV excitation energy and spin ∼37/2ℏ using the prompt gamma spectroscopy technique with the Indian National Gamma Array (INGA). The angular distribution, directional correlation, and polarization measurements were carried out to assign the spin and parity of the newly reported states. The structures of both the positive and negative parity states up to highest spin observed in the present experiment have been compared with shell-model calculations using two recently developed residual interactions, JUN45 and jj44b. The role of proton excitations from p3/2 and f5/2 orbitals to the g9/2 orbital for the higher spin states has been discussed.
    Physical Review C 09/2012; 86(3). · 3.72 Impact Factor
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    ABSTRACT: The low energy structure of $^{35,37,39,41}$S isotopes is described performing shell model calculations with the recently devised SDPF-U interaction. Protons and neutrons are restricted to the $sd$-shell for $N < 20$, neutrons start filling the $fp$-shell for $N > 20$. Natural parity states are described with only in-shell mixing, opposite parity states with 1p-1h inter-shell neutron excitations. Energy levels and intensities of electromagnetic transitions are compared with experimental data when available.
    07/2012;
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    T. Trivedi, P. C. Srivastava, D. Negi, I. Mehrotra
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    ABSTRACT: We have performed shell model calculations for neutron deficient even 102-108Sn and odd 103-107Sn isotopes in sdg7/2h11/2 model space using two different interactions. The first set of interaction is due to Brown et al. and second is due to Hoska et al. The calculations have been performed using doubly magic 100Sn as core and valence neutrons are distributed over the single particle orbits 1g7/2, 2d5/2, 2d3/2, 3s1/2 and 1h11/2. In more recent experimental work for 101Sn [I. G. Darby et al., Phys. Rev. Lett. 105 (2010) 162502], the g.s. is predicted as 5/2+ with excited 7/2+ at 172 keV. We have also performed another two set of calculations by taking difference in single particle energies of 2d5/2 and 1g7/2 orbitals by 172 keV. The present state-of-the-art shell model calculations predict fair agreement with the experimental data. These calculations serve as a test of nuclear shell model in the region far from stability for unstable Sn isotopes near the doubly magic 100Sn core.
    International Journal of Modern Physics E 05/2012; 21(04):50049-. · 0.63 Impact Factor
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    J. G. Hirsch, P. C. Srivastava
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    ABSTRACT: A shell model study of the low energy region of the spectra in Ge isotopes for $38\leq N\leq 50$ is presented, analyzing the excitation energies, quadrupole moments, $B(E2)$ values and occupation numbers. The theoretical results have been compared with the available experimental data. The shell model calculations have been performed employing three different effective interactions and valence spaces.We have used two effective shell model interactions, JUN45 and jj44b, for the valence space $f_{5/2} \, p \,g_{9/2}$ without truncation. To include the proton subshell $f_{7/2}$ in valence space we have employed the $fpg$ effective interaction due to Sorlin {\it et al.}, with $^{48}$Ca as a core and a truncation in the number of excited particles.
    Journal of Physics Conference Series 04/2012; 387(1).
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    P. C. Srivastava
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    ABSTRACT: Shell model calculations for Ni, Cu and Zn isotopes by modifying fpg interaction due to Sorlin et al. [Phys. Rev. Lett. 88, 092501 (2002)] have been reported. In the present work, 28 two-body matrix elements of the earlier interaction have been modified. Present interaction is able to explain new experimental results for this region.
    Modern Physics Letters A 01/2012; 27(13):50061-. · 1.11 Impact Factor
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    ABSTRACT: The use of different mass parameters for the rotation and two vibrations in the Bohr Hamiltonian is important for describing properties of nuclei, especially interband E2 transition probabilities. For odd nuclei, the Coriolis interaction of the angular momentum of an odd nucleon with that of a nucleus can affect results noticeably. Excited-state energies and E2 transition probabilities have been calculated for the 163Dy and 173Yb nuclei, by using three different mass parameters and taking into account the Coriolis interaction, once shell-model calculations have been performed to determine the single-particle ground-state properties of 163Dy and 173Yb.
    Physical Review C 01/2012; 85(3):034307. · 3.72 Impact Factor
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    P. C. Srivastava, I. Mehrotra
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    ABSTRACT: Yrast levels of Ni, Cu and Zn isotopes for $40 \leq N \leq50$ have been described by state-of-the-art shell model calculations with three recently available interactions using $^{56}$Ni as a core in the $f_{5/2}pg_{9/2}$ model space. The results are unsatisfactory viz. large $E(2^+)$ for very neutron rich nuclei, small B(E2) values in comparison to experimental values. These results indicate an importance of inclusion of $\pi f_{7/2}$ and $\nu d_{5/2}$ orbitals in the model space to reproduce collectivity in this region.
    International Journal of Modern Physics E 12/2011; 21(01). · 0.63 Impact Factor
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    P C Srivastava
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    ABSTRACT: We have performed a comprehensive set of shell-model calculations for Ga isotopes including high-spin states with three different effective interactions. This work will add more information to the earlier work by Cheal et al (2010 Phys. Rev. Lett. http://dx.doi.org/10.1103/PhysRevLett.104.252502) for odd–even Ga isotopes and Mané et al (2011 Phys. Rev. C http://dx.doi.org/10.1103/PhysRevC.84.024303) for odd–odd Ga isotopes, where only a few excited states are studied in the f5/2pg9/2 space. For lighter isotopes, the fpg interaction is better and for heavier isotopes, jj44b is quantitatively better than JUN45. These results show the limitation of existing interactions and calling for further improvements to predict the nuclear structure properties of Ga isotopes.
    Journal of Physics G Nuclear and Particle Physics 11/2011; 39(1):015102. · 5.33 Impact Factor
  • R. Sahu, P.C. Srivastava, V.K.B. Kota
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    ABSTRACT: The half-life for two-neutrino double-beta decay has been calculated for 82Se, within the framework of the deformed shell model (DSM) based on Hartree–Fock states employing a modified Kuo interaction in 2p3/2, 1f5/2, 2p1/2, and 1g9/2 space with single particle energies (relative to a 56Ni core) for the four orbitals taken as 0.0, 0.78, 1.08, and 4.25 MeV, respectively. A reasonable description is obtained for the spectroscopic properties of yrast levels in 82Se, and similarly in the past 82Kr was studied successfully using DSM. The half-life calculated using DSM is 3.56 × 1020 a compared to the experimental value (0.92 ± 0.07) × 1020 a. We have also recalculated the half-life by including the 1f7/2 orbit in the preceding model space using the fpg interaction introduced by Sorlin et al. (Phys. Rev. Lett. 88, 092501 (2002)). The calculated half-life is 2.05 × 1019 a (0.58 × 1020 a if we include the quenching factor of 0.77).
    Canadian Journal of Physics 10/2011; 89(11):1101-1105. · 0.90 Impact Factor
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    P. C. Srivastava, V. K. B. Kota
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    ABSTRACT: Low-lying spectra and several high-spin states of odd-even {sup 61,63,65}Co isotopes are calculated in two different shell-model spaces. First set of calculations have been carried out in fp-shell valence space (full fp space for {sup 63,65}Co and a truncated one for {sup 61}Co) using two recently derived fp-shell interactions, namely GXPF1A and KB3G, with {sup 40}Ca as core. Similarly, the second set of calculations have been performed in fpg{sub 9/2} valence space using an fpg effective interaction due to Sorlin et al., with {sup 48}Ca as core and imposing a truncation. It is seen that the results of GXPF1A and KB3G are reasonable for {sup 61,63}Co. For {sup 65}Co, shell-model results show that the fpg interaction adopted in the study is inadequate and also points out that it is necessary to include orbitals higher than 1g{sub 9/2} for neutron-rich Co isotopes.
    Physics of Atomic Nuclei 07/2011; 74(7). · 0.54 Impact Factor

Publication Stats

44 Citations
51.26 Total Impact Points

Institutions

  • 2013–2014
    • Indian Institute of Technology Roorkee
      • Department of Physics
      Roorkee, Uttarakhand, India
  • 2011–2012
    • National Autonomous University of Mexico
      • Institute of Nuclear Science
      Ciudad de México, The Federal District, Mexico
  • 2010
    • Grand Accélérateur National d'Ions Lourds
      Caen, Lower Normandy, France
  • 2009–2010
    • University of Allahabad
      • Department of Physics
      Prayāg, Uttar Pradesh, India