| 1. |
- Anderson, D., et al.
(author)
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A variational approach to nonlinear evolution equations in optics
- 2001
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In: Pramana (Bangalore). - : Indian Academy of Sciences. - 0304-4289 .- 0973-7111. ; 57:5-6, s. 917-936
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Journal article (peer-reviewed)abstract
- The use of direct variational methods based on Rayleigh-Ritz optimization for finding approximate solutions to various nonlinear evolution equations was presented. The main advantage of the approach is that it provides simple and explicit expressions for physically relevant quantities where exact analytical solutions are not available. It is found that the given method is flexible and can be applied to stationary and dynamical problems.
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| 2. |
- Blomgren, Jan
(author)
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Neutron cross-sections above 20 MeV for design and modeling of accelerator driven systems
- 2007
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In: Pramana (Bangalore). - : Springer Science and Business Media LLC. - 0304-4289 .- 0973-7111. ; 68:2, s. 269-278
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Journal article (peer-reviewed)abstract
- One of the outstanding new developments in the field of partitioning and transmutation (P&T) concerns accelerator-driven systems (ADS) which consist of a combination of a high-power, high-energy accelerator, a spallation target for neutron production and a sub-critical reactor core. The development of the commercial critical reactors of today motivated a large effort on nuclear data up to about 20 MeV, and presently several million data points can be found in various data libraries. At higher energies, data are scarce or even non-existent. With the development of nuclear techniques based on neutrons at higher energies, nowadays there is a need also for higher-energy nuclear data. To provide alternative to this lack of data, a wide program on neutron-induced data related to ADS for P&T is running at the 20-180 MeV neutron beam facility at 'The Svedberg Laboratory' (TSL), Uppsala. The programme encompasses studies of elastic scattering, inelastic neutron production, i.e., (n, xn') reactions, light-ion production, fission and production of heavy residues. Recent results are presented and future program of development is outlined.
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| 3. |
- Brandenburg, Axel
(author)
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Chandrasekhar-Kendall functions in astrophysical dynamos
- 2011
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In: Pramana (Bangalore). - 0304-4289 .- 0973-7111. ; 77:1, s. 67-76
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Journal article (peer-reviewed)abstract
- Some of the contributions of Chandrasekhar to the field of magnetohydrodynamics are highlighted. Particular emphasis is placed on the Chandrasekhar-Kendall functions that allow a decomposition of a vector field into right- and left-handed contributions. Magnetic energy spectra of both contributions are shown for a new set of helically forced simulations at resolutions higher than what has been available so far. For a forcing function with positive helicity, these simulations show a forward cascade of the right-handed contributions to the magnetic field and nonlocal inverse transfer for the left-handed contributions. The speed of inverse transfer is shown to decrease with increasing value of the magnetic Reynolds number.
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| 4. |
- Coniavitis, Elias, et al.
(author)
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Study of charged and neutral minimal supersymmetric standard model Higgs boson decays and measurement of tan beta at the compact linear collider
- 2007
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In: Pramana (Bangalore). - 0304-4289 .- 0973-7111. ; 69:6, s. 1141-1145
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Journal article (peer-reviewed)abstract
- The minimal supersymmetric extension of the standard model (MSSM) predicts the existence of new charged and neutral Higgs bosons. The pair creation of these new particles at the multi-TeV e(+)e(-) compact linear collider (CLIC), followed by decays into standard model particles, were simulated along with the corresponding background. High-energy beam-beam effects such as ISR, beamstrahlung and hadronic background were included. We have investigated the possibility of using the ratio between the number of events found in various decay channels to determine the MSSM parameter tan 0 and we have derived the corresponding statistical error from the uncertainties on the measured cross-sections and Higgs boson masses.
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| 5. |
- Ferrari, Arnaud, et al.
(author)
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Power losses in the international linear collider 20 mrad extraction line at 1 TeV
- 2007
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In: Pramana (Bangalore). - : Springer Science and Business Media LLC. - 0304-4289 .- 0973-7111. ; 69:5, s. 765-769
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Journal article (peer-reviewed)abstract
- We have performed a detailed study of the power losses in the post-collision extraction line of a TeV e(+)e(-) collider with a crossing angle of 20 mrad at the interaction point. Five cases were considered: four luminosity configurations for ILC and one for CLIC. For all of them, the strong beam-beam effects at the interaction point lead to an emittance growth for the outgoing beam, as well as to the production of beamstrahlung photons and e(+)e(-) coherent pairs. The power losses along the extraction line, which axe due to energy deposition by a fraction of the disrupted beam, of the beamstrahlung photons and of the coherent pairs, were estimated in the case of ideal collisions, as well as with a vertical position or angular offset at the interaction point.
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| 6. |
- Ghosh, Monojit, et al.
(author)
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Evidence for leptonic CP phase from NO nu A, T2K and ICAL
- 2016
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In: Pramana (Bangalore). - : Springer. - 0304-4289 .- 0973-7111. ; 86:2, s. 387-393
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Journal article (peer-reviewed)abstract
- The phenomenon of neutrino oscillation is now well understood from the solar, atmospheric, reactor and accelerator neutrino experiments. This oscillation is characterized by a unitary PMNS matrix which is parametrized by three mixing angles (oee integral (12), oee integral (23) and oee integral (13)) and one phase (delta (CP)) known as the leptonic CP phase. Neutrino oscillation also involves two mass squared differences: the solar mass square difference () and the atmospheric mass square difference (). Though there is already significant amount of information about the three mixing angles, the CP phase is still unknown. Apart from the CP phase, one should also know what is the true nature of the neutrino mass hierarchy, i.e., normal (m (3)> m (1): NH) or inverted (m (1)> m (3): IH) and what is the true octant of oee integral (23), i.e., lower (oee integral (23)< 45(a similar to): LO) or higher (oee integral (23)> 45(a similar to): HO). The long-baseline experiments (LBL) have CP sensitivity coming from the appearance channel (). On the other hand, atmospheric neutrinos are known to have negligible CP sensitivity. In this work, we study the synergy between the LBL experiment NO nu A, T2K and the atmospheric neutrino experiment ICAL@INO for obtaining the first hint of CP violation in the lepton sector. We find that due to the lack of knowledge of hierarchy and octant, CP sensitivity of NO nu A/T2K is poorer for some parameter ranges. Addition of ICAL data to T2K and NO nu A can exclude these spurious wrong-hierarchy and /or wrong-octant solutions and cause a significant increase in the range of delta (CP) values for which a hint of CP violation can be achieved. Similarly, the precision with which delta (CP) can be measured also improves with the inclusion of ICAL data.
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| 7. |
- Gupta, A., et al.
(author)
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Synthetic magnetic opals
- 2002
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In: Pramana (Bangalore). - : Springer Science and Business Media LLC. - 0304-4289 .- 0973-7111. ; 58:06-maj, s. 1051-1059
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Journal article (peer-reviewed)abstract
- We present studies of novel nanocomposites of BiNi impregnated into the structure of opals as well as inverse opals. Atomic force microscopy and high resolution elemental analyses show a highly ordered structure and uniform distribution of the BiNi filler in the matrix. These BiNi-based nanocomposites are found to exhibit distinct ferromagnetic-like ordering with transition temperature of about 675 K. As far as we know there exists no report in literature on any BiNi compound which is magnetic.
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| 8. |
- Hellborg, Ragnar, et al.
(author)
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Mechanical design of the recirculating, terminal pumping in the Lund Pelletron, and experimental experience
- 2002
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In: Pramana - Journal of Physics. - 0304-4289 .- 0973-7111. ; 59:5, s. 725-737
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Conference paper (peer-reviewed)abstract
- A recirculating terminal pumping system has been installed in the 3 MV Pelletron tandem accelerator in Lund. An extremly limited space in the high voltage terminal and the absence of electrical power in the terminal, forced us to provide a unique design for the installation and powering of the new pumps. Details of the technical design, as well as experience of the use of the new system for accelerator mass Spectrometry, will be given.
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| 9. |
- Palodhi, Lopamudra, et al.
(author)
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Counterstreaming beams in magnetized Vlasov plasma
- 2019
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In: Pramana (Bangalore). - Bangalore, India : Indian Academy of Sciences. - 0304-4289 .- 0973-7111. ; 93, s. 1-10
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Journal article (peer-reviewed)abstract
- In this paper, we investigate nonrelativistic, kinetic, linear phase of the filamentation instability when an external magnetic field is present in the direction of the counterstreaming electron beams using Vlasov simulations in 1D-3V space. We first investigate the growth rate of instability. In the linear growth regime, our results correspond to the previous conclusions that with the increase in strength of the ambient magnetic field, there is a suppression of instability. Interestingly, we established that at a critical / threshold magnetic field, Vlasov simulations and particle-in-cell (PIC) simulations differ in their instability behaviour. At this particular magnetic field, there is a complete suppression of the growth of instability in Vlasov results compared to PIC simulations, where a strong growth of instability is shown. It is believed that thermal noise in the PIC leads to the growth. However, Vlasov simulations show wave–wave coupling which stabilises the modes. In this work, our focus is to demonstrate the difference in this behaviour and to thoroughly analyse the spectra and wave generation for the same.
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| 10. |
- Pattabiraman, M., et al.
(author)
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Annealing effect on transport properties of Nd0.67Sr0.33MnO3 thin films
- 2000
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In: Pramana (Bangalore). - : Springer Science and Business Media LLC. - 0304-4289 .- 0973-7111. ; 55:3, s. 455-469
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Journal article (peer-reviewed)abstract
- Annealing dependence of the lattice parameter, resistivity, magnetoresistance and thermopower have been studied on Nd0.87Sr0.33MnO3 thin films deposited on LaAlO3 and alumina substrates by pulsed laser ablation. Upon annealing at 800 degrees C and 1000 degrees C the lattice constant of the LaAlO3 film tends toward that of the bulk target due to reduction in oxygen vacancies. This results in a metal-insulator transition at temperatures which increase with progressive annealing along with a decrease in the observed low temperature MR. Using a magnon scattering model we estimate the e(g) bandwidth of the film annealed at 1000 degrees C and show that the magnon contribution to the resistivity is suppressed in a highly oxygen deficient film and gains prominence only upon subsequent annealing. We also show that upon annealing, the polaron concentration and the spin cluster size increases in the paramagnetic phase, using an adiabatic polaron hopping model which takes into account an exchange dependent activation energy above the resistivity peak.
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