04-01-2007 At 04:00:00 PM
Speaker: Prof. P.Mukhopadhyay, Cambridge Univ.
Category: High Energy Group Seminar
Venue: Lecture Hall (Main Building)
07-01-2007 At 12:00:00 PM
Speaker: Dr. Bikash Sinha, VECC, Kolkata
Category: Seminar of General Interest
Venue: Lecture Hall (Main Building)
11-01-2007 At 04:00:00 PM
Speaker: Prof. Rajat K. Bhaduri, McMaster University, Canada
Category: Seminar of General Interest
Venue: Lecture Hall
After an elementary introduction, we focus on the density dependence of the interaction energy of the gas at Feshbach resonance. A naive perturbative approach cannot explain universality, but gives the unexpected cancellation of the first order exchange energy withthe perturbative correlation energy at resonance for short range interactions. A curious, almost shape-independent property of the attractive two-bodypotential is found at Feshbach resonance.
12-01-2007 At 04:00:00 PM
Speaker: Dr. M.A. Munoz, IFTCC, Granada, Spain
Category: Seminar of General Interest
Venue: Lecture Hall
15-01-2007 At 04:00:00 PM
Speaker: Prof. L. Sriramkumar HRI, Allahabad
Category: Colloquium
Venue: Lecture Hall
Inflation---a period of accelerated expansion is currently considered the most promising paradigm for describing the early stages of the universe. The success of the inflationary scenario rests on its ability to explain not only the homogeneity of the background, but also the characteristics of the in homogeneities superimposed upon it. The inflationary epoch magnifies the tiny fluctuations in the quantum fields present at the beginning of the epoch into classical perturbations that leave their imprints as anisotropies in the cosmic microwave background (CMB). These anisotropies in turn act as seeds for the formation of the large-scale structure that we observe at the present time as galaxies and clusters of galaxies. With anisotropies in the CMB being measured with higher and higher precision, we are currently able to test the predictions of inflation better and better. In this talk, after introducing the motivations and essential features of inflation, I provide a brief overview of cosmological perturbation theory, and discuss the constraints from the most recent WMAP data on the inflationary parameters.
19-01-2007 At 04:00:00 PM
Speaker: Dr. Frank Pollmann, Max Planck Institute, Germany
Category: Seminar of General Interest
Venue: Lecture Hall
22-01-2007 At 04:00:00 PM
Speaker: Dr. Monodeep Chakraborty, IOP,BBSR
Category: Condensed Matter Group Seminar
Venue: Lecture Hall
23-01-2007 At 04:00:00 PM
Speaker: Dr. K.Narayan, Deptt. of Theoretical Physics TIFR,Mumbai
Category: Seminar of General Interest
Venue: Lecture Hall
24-01-2007 At 04:00:00 PM
Speaker: Prof. M.P. Das, ANU, Australia
Category: Seminar of General Interest
Venue: Lecture Hall
24-01-2007 At 11:00:00 AM
Speaker: Dr. Monodeep Chakraborty, IOP,BBSR
Category: Condensed Matter Group Seminar
Venue: Lecture Hall
25-01-2007 At 04:00:00 PM
Speaker: Prof. S. Ramasesha, IISc, Bangalore
Category: Seminar of General Interest
Venue: Lecture Hall
Single molecule magnets (SMM) consist of several magnetic centers among which the exchange interactions are often frustrated. The nature of the super-exchange interaction between any pair of magnetic ions is itself sensitive to changes in the electron repulsion parameters and orbital energies. Even when all the exchange constants between pairs of magnetic centers are fixed, there are difficulties with predicting even the ground state of the spin. Approximate techniques for solving for the ground and low-lying states of such large Hilbert space system are unreliable. We have developed exact diagonalization techniques for solving such model Hamiltonians. Another important property of SMMs is the presence of a large negative magnetic anisotropy constant ‘D’ in the system. The individual ions have their own anisotropy constants oriented along their individual magnetic axis. We have developed a method of computing the molecular anisotropy constants in any given state of the SMM, using first order perturbation theory. We show that the relative orientation of the individual magnetic centers determines the sign of the anisotropy constant ‘D’ and that the molecular ‘D’ can be negative even when all the magnetic centers have a positive ‘D’. An important property of SMMs is the observation of quantum resonant tunneling (QRT). We study QRT using time-dependent quantum mechanics and show that the rates of ramping of the magnetic field as well as the presence of transverse fields determine the number and width of the magnetization plateaus in the M-H loop.
29-01-2007 At 04:00:00 PM
Speaker: Dr. Prafulla Behera, SLAC, USA
Category: Colloquium
Venue: Lecture Hall
14-02-2007 At 04:00:00 PM
Speaker: Rani Devi, Jammu University, Jammu
Category: Nuclear Physics Group Seminar
Venue: Lecture Hall
01-03-2007 At 04:00:00 PM
Speaker: Prof.S.M.Bhattacharjee
Category: Condensed Matter Group Seminar
Venue: Lecture Hall
05-03-2007 At 04:00:00 PM
Speaker: Prof. K. P. N. Murthy, School of Physics University of Hyderabad, Hyderabad
Category: Colloquium
Venue: Lecture Hall
06-03-2007 At 04:00:00 PM
Speaker: Dr. Sanjay Gupta, IACS Kolkata
Category: TPSE Seminar
Venue: Lecture Hall
07-03-2007 At 04:00:00 PM
Speaker: Dr. Arijit Bhattacharya, Univ. of Padova, Italy
Category: TPSC Seminar
Venue: Lecture Hall
07-03-2007 At 11:00:00 AM
Speaker: Dr. Pushan Majumdar, Universitat Munster, Germany
Category: High Energy Group Seminar
Venue: Lecture Hall
In this talk we will look at properties of gluonic flux tubes which are believed to be responsible for confining quarks in QCD, through simulations in lattice gauge theory. We will try to identify the length scale and type of string theory which describes the observed flux tube properties best.
08-03-2007 At 04:00:00 PM
Speaker: Professor S. D. Joglekar Department of Physics, IIT, Kanpur
Category: High Energy Physics Seminar of General Interest
Venue: Lecture Hall
09-03-2007 At 04:00:00 PM
Speaker: Dr. Vikram Tripathi, TIFR, Mumbai
Category: Condensed Matter Group Seminar
Venue: Lecture Hall
Using the Kubo formula approach, we study the effect of electron interaction on thermal transport in the vicinity of a metal-insulator transition, with a granular metal as our model. For small values of dimensionless intergrain tunneling conductance, $gll1,$ we find that the thermal conductivity surprisingly shows a phonon-like algebraic decrease, $kappa(T)sim g^{2}T^{3}/E_{c}^{2}$ even though the electrical conductivity obeys an Arrhenius law, $sigma(T)sim ge^{-E_{c}/T};$ therefore the Wiedemann-Franz (WF) law is seriously violated. This violation arises from non-magnetic bosonic excitations of low energy that transport heat but not charge. Implications for experiment are discussed
21-03-2007 At 04:00:00 PM
Speaker: Dr.Sreekantha Sil,Visva Bharati, Santiniketan
Category: TPSC Condensed Matter Physics Seminar
Venue: Lecture Hall
The application of the effect of magneto-resistance in magneto-electronics, field sensors and random access memory elements and others created a huge interest on the studies of the magnetic and transport properties of the magnetic material realized in low dimensions. The interplay between magnetization and localization is central to the behavior of many artificially tailored materials and has given rise to phenomena such as giant magneto-resistance in metallic multi-layers, spin polarons in high Tc superconductors and skyrmion in two dimensional electron gases in semiconductors. At low temperatures, transport measurements in ferromagnetic materials indicate remarkable modification of the quantum correction to the 2D magneto-conductivity in the weakly localized regime, and negative magneto-resistance (MR) at high field suggesting suppression of weak electron localization (WEL) and spin disorder scattering. Moreover, the observation of anisotropic magneto-resistance (AMR) and anomalous Hall effect in ferromagnets emphasizes the importance of spin-orbit scattering in the transport properties of the low-dimensional ferromagnetic material. In order to get a better understanding regarding the transport properties of the ferromagnetic materials we will study the magneto-conductivity of a two-dimensional ferromagnet in presence of elastic scattering as well as spin-orbit scattering. Here we will provide a general description of the electronic transport in ferro-magnets for arbitrary direction of magnetization and magnetic field. By means of the diagrammatic perturbation technique, an analytical results for the magneto-conductivity has been obtained as a function of the magnetization and characteristic relaxation times due to elastic, inelastic and spin-orbit scattering. The result shows a strong dependence of the orientation of the magnetization with respect to the plane of the system on the conductivity. Depending on the orientation and strength of the magnetization and the coupling of the electronic spin with the magnetization both negative and positive magneto-resistance has been predicted. In addition, it is shown that, in order to explain the experimental variation of the conductivity in thin ferromagnetic films [1], electron-electron interaction and domain wall scattering must be considered.
23-03-2007 At 11:00:00 AM
Speaker: Dr. David Beck, Asylum Research
Category: Experimental Condensed Matter Group Seminar
Venue: Lecture Hall
26-03-2007 At 04:00:00 PM
Speaker: Prof. M. Mukherjee , S. I. N. P. , Kolkata
Category: TPSC Condensed Matter Physics Seminar
Venue: Lecture Hall
Structure and swelling dynamics of ultra thin films of CdS-polyacrylamide nanocomposite material were studied using gravimetric techniques and x-ray reflectivity. Ultrathin films of the polymer and the nanocomposite were coated on hydrophilic Si (100) substrate using spin coating. The thickness of the composite films vary non-monotonically with spinning speed and were found to lie in discrete “bands†of thicknesses separated by “forbidden regions†unlike pure polymer films. Modified internal structure of the coils due to polymer-particle interaction was found to play a significant role in describing the novel features of the nanocomposite films. To study the mass uptake, the films were exposed to the H2O vapour and the weights of the films were recorded as functions of exposure time. The observed non-Fickian transport was explained in terms of alignment of free volume due to confinement of restricted polymer chains. To study swelling dynamics, the films were exposed to the H2O vapour and x-ray reflectivity scans were collected as functions of exposure time. The swelling dynamics of the nanocomposite films were explained in terms of a model which takes into account the polymer-particle interaction. A fraction of polymer segments that are in direct contact with the nanoparticles observed slower dynamics as compared to the free chain swelling. Larger values of excluded volume parameters corresponding to restricted segments as compared to the free segments were explained in terms of enhancement of monomer-monomer interaction through particle attachment.
27-03-2007 At 04:00:00 PM
Speaker: Dr. A. K. Pati, IOP
Category: Seminar of General Interest
Venue: Lecture Hall
It is known that classical information can be completely hidden from asubsystem in two distinct ways. The information may be moved to another location, orit may be encoded as correlations between a pair of subsystems. Most generally, theinformation will be hidden as a combination of these two. Can we hide quantuminformation in the same way? Consider a physical process which maps an arbitraryquantum state to a fixed state. If the final state is independent of the input, thenwe prove that this missing, or hidden, information is wholly encoded in theremainder of Hilbert space with no information stored in the correlations betweenthe two subsystems. We call this the "no-hiding theorem". Thus, unlike classicalinformation, quantum mechanics allows only one way to completely hide an arbitraryquantum state from one of its subsystems, i.e., by moving it to the remainingsubsystems. We will discuss various applications of this theorem in quantumteleportation, thermalisation and finally in black hole information loss paradox.
27-03-2007 At 11:00:00 AM
Speaker: Prof. M. Mukherjee , S. I. N. P. , Kolkata
Category: TPSC CONDENSED MATTER PHYSICS SEMINAR
Venue: Lecture Hall
In case of photoemission spectroscopy of an insulating material the data obtained from the charged surface are distorted. Recently a controlled surface neutralization technique has been developed and with the help of an effective model quantitative information from the apparently distorted photoemission data was extracted. It was shown that the neutralization responses of differential charging are non-linear around a critical neutralizing electron flux. Here with a new set of experiments with Poly(tetrafluoroethylene) (PTFE) and analyzing our earlier data of Polystyrene (PS) and Polyacrylamide (PAM) it was shown that the neutralization of charged surfaces are similar to avalanche breakdown process and occurs through the percolation of homogeneously dispersed surface domains.
03-04-2007 At 04:00:00 PM
Speaker: Dr. Hirendra N. Ghosh, BARC, Mumbai
Category: Condensed Matter Group Seminar
Venue: Lecture Hall
Solar energy conversion through design and development of dye-sensitizedTiO2 semiconductor solar cell has been a subject of intense research inrecent years. The most efficient cells of this type, based onRu(dcbpy)2(NCS)2 [dcbpy (4,4„S-dicarboxy-2,2„S-bipyridine)] (or Ru N3)sensitized nanocrystalline TiO2 thin films, can achieve a solar toelectric power conversion efficiency of about 10%. Recently we areinvolved in design and developing of suitable dye molecule with suitableanchoring group and useful molecular structure, and also synthesis of newtype of nanoparticles and quantum dot materials and then studyinginterfacial electron transfer dynamics of the dye-nanoparticle systems byfast and ultrafast spectroscopic techniques. It has been observed that dyemolecules with strong anchoring group helps ultrafast electron injection,however it also facilitate fast back electron transfer (BET), which isunwanted for higher conversion efficiency. It has been realized thatstrong coupling dyes not only inject electron in the conduction band butalso in to the surface states of nanoparticles. It is well known that oncethe electron injected into the surface states cannot be use energyconversion purpose. From our investigation we have shown that dyemolecules with twisted intramolecular charge transfer (TICT) state can bemore efficient electron injector to the conduction band of nanoparticlesas compared to that of dyes with no TICT states. We have also synthesizednew type of nanoparticles by modifying the surface of it with sodiumdodecyl benzene sulphonate (DBS), TOPO and benzophenone. Our measurementshave shown that in dye-nanoparticle systems BET reaction is much slower onmodified surface as compared to that on bare surface. It has been observedthat charge recombination reaction is very slow on dye-sensitized quantumdot semiconductor materials.
04-04-2007 At 04:00:00 PM
Speaker: S.N. Sarangi, IOP
Category: Seminar of General Interest
Venue: Lecture Hall
05-04-2007 At 04:00:00 PM
Speaker: Dipak Paramanik, IOP
Category: Seminar of General Interest
Venue: Lecture Hall
10-04-2007 At 04:00:00 PM
Speaker: Santosh Kumar Agarwal, North Orissa Univ.
Category: Seminar of General Interest
Venue: Lecture Hall
17-04-2007 At 04:00:00 PM
Speaker: Dr. Devashish Sanyal, SINP, Kolkata
Category: TPSC Seminar
Venue: Lecture Hall
The problem of persistence in simple diffusion with stochastic initial conditions is discussed. The calculated persistence exponent, which is at variance with that obtained by Majumdar et al [Phys Rev Lett 77, 2867, (1996)] and Derrida et al [Phys Rev Lett 77, 2871,(1996)] numerically, is discussed along with a critical analysis of accepted results. The approach is further extended to the case of advection of a passive scalar by a stochastic velocity field to show that the persistence exponent changes continuously as the velocity field is switched on.
25-04-2007 At 04:00:00 PM
Speaker: Raghunath Sahoo, IOP
Category: Seminar of General Interest
Venue: Lecture Hall
03-05-2007 At 04:00:00 PM
Speaker: Dr. Swarnali Bandopadhyay, MPIKS, Dresden, Germany
Category: TPSC Condensed Matter Physics Seminar
Venue: Lecture Hall
03-05-2007 At 11:00:00 AM
Speaker: Dr. V. Vasumathi
Category: TPSC CMP Seminar
Venue: Lecture Hall
04-05-2007 At 04:00:00 PM
Speaker: Dr. Debashish Chaudhuri, MPIKS, Dresden, Germany
Category: TPSC CMP Seminar
Venue: Lecture Hall
07-05-2007 At 04:00:00 PM
Speaker: Dr. Narendra Sahu, Physical Research Laboratory, Ahmeadabad
Category: TPSC Seminar
Venue: Lecture Hall
In recent years the most fascinating experimental result in particle physics came out in neutrino physics. The atmospheric and solar neutrino oscillation experiments give a convincing evidence that at least two of the neutrinos are massive, and are of the order of sub-eV. The smallness of neutrino masses depend on a large suppression by the lepton number violating scales. The lepton number violation in the early universe could produce a net lepton asymmetry which was then transferred to a baryon asymmetry,that is observed today, in the presence of electroweak anomalous processes. The present neutrino oscillation data imply that if neutrino masses and leptogenesis are originated from the same source of lepton number violation, then the scale of leptogenesis should be $\geq O(10^9)$ GeV which is far away from the next generation accelerators to be verified.In this talk we will discuss a particle physics model for neutrino masses and leptogenesis at the TeV scale. We ensure that the lepton number violation required for neutrino masses does not conflict with the lepton number violation required for leptogenesis. As a result the model could be extended to explain the dark matter (DM), whichis 23% of the critical energy density, and dark energy (DE), which is 73% of the critical energy density, of the present universe. The most attractive feature of this model is that itpredicts a few hundred GeV triplet Higgs scalar that can be tested at LHC or ILC.
14-05-2007 At 04:00:00 PM
Speaker: Prof. R. Shyam, SINP, Kolkata
Category: Seminar of General Interest
Venue: Lecture Hall
21-05-2007 At 04:00:00 PM
Speaker: Prof. B.N.Dev, Indian Association for the Cultivation of Science, Jadvpur,Kolkata
Category: Colloquium
Venue: Lecture Hall
A brief introduction will be given on magnetism in nanoscale systems and how size and shape affect magnetic behaviour. The importance of ion beams in the area of nanoscale magnetism will be illustrated with demonstration of dual roles of ion irradiation, namely, transformation of nonmagnetic materials into magnetic materials and vice versa. In the light of the observed phenomena, future developments in the area of nanotechnology, such as ultrahigh density magnetic storage devices, single-electron spin-valve transistors etc. will be discussed. Some nanoscale structures that can be fabricated using ion beams will offer the possibility of exploring new scientific aspects in these structures
21-05-2007 At 11:00:00 AM
Speaker: Prof. Shibiji Raha , Bose Institute, Kolkata
Category: Seminar of General Interest
Venue: Lecture Hall
22-05-2007 At 04:00:00 PM
Speaker: Prof. Parthasarathi Majumdar, SINP, Kolkata
Category: Seminar of General Interest
Venue: Lecture Hall
29-05-2007 At 04:00:00 PM
Speaker: Dr. S. Chamoli, Weizmann Institute, Isreal
Category: Seminar of General Interest
Venue: Lecture Hall
The only doubly magic region above 7828Ni accessible for detailed spectroscopic studies on the neutron rich side of nuclear landscape is 13250Sn region. High spin isomers in these nuclei have very often a rather pure single particle configuration and therefore good candidates to study details of the nuclear M1 and E2 properties. Shell model calculations can reproduce most of the high spin features of the nuclei in this mass region, but still some discrepancies remain. The g-factor measurements are therefore necessary to pinpoint the current faults in shell-model descriptions. Present measurement is the first such attempt to measure the g-factors of high spin isomers in the nuclei of the doubly magic 132Sn region, produced via relativistic energy projectile fragmentation of 136Xe at 700 MeV/A. A good degree of alignment (~ 12 %) obtained in this reaction indicates a major success of the campaign as now more neutron rich nuclei are opened for such studies.
06-06-2007 At 04:00:00 PM
Speaker: A.K. Mahapatra, IOP
Category: Experimental Condensed Matter Group Seminar
Venue: Lecture Hall
08-06-2007 At 04:00:00 PM
Speaker: Prof. Bimal P. Mahapatra, Sambalpur Univ
Category: Seminar of General Interest
Venue: Lecture Hall
A new method of approximation scheme, with potential of application to a general , interacting quantum theory is presented. The method is non-perturbative, self-consistent, systematically improvable and uniformly applicable for arbitrary strength of interaction. It thus overcomes the limitations of the existing methods, such as the perturbation theory, the variational method, the WKBJ method and other approximation schemes. The method has been successfully applied to a variety of interacting quantum systems including the anharmonic/ double well oscillators (with general quadratic-, quartic-, sextic- and octic couplings), the hydrogen atom and to the (lambda phi^4) quantum-field theory. The method yields important insight to the structure and stability of the physical vacuum. The results are shown to be consistent with the exact results predicted by supersymmetric quantum mechanics wherever applicable. Possible application to quantum statistics and finite temperature field theory is discussed.
11-06-2007 At 04:00:00 PM
Speaker: Prof. Somenath Chakrabarty, Visva Bharati, Santiniketan
Category: Seminar of General Interest
Venue: Lecture Hall
The breaking of chiral symmetry of light quarks at zero temperature in the presence of strong quantizing magnetic field is studied using Nambu-Jona-Lasinio (NJL) model with a Thomas-Fermi type semi-classical formalism. It is found that the dynamically generated light quark mass can never become zero if the Landau levels are populated and increases with the increase of magnetic field strength.
12-06-2007 At 04:00:00 PM
Speaker: Prof. S.A. Ramakrishan, I.I.T, Kanpur
Category: Seminar of General Interest
Venue: Lecture Hall
We will discuss the design of structured composite materials whose electromagnetic response can be described by effective medium parameters such as the dielectric permittivity and magnetic permeability. We will more particularly discuss metamaterials with negative material parameters and present our recent results on optical metamaterials in perspective. Extremely singular photonic systems using superstructures of metamaterials with positive and negative material parameters will be presented
13-06-2007 At 04:00:00 PM
Speaker: Prof. P.N. Ghosh, University of Calcutta
Category: Seminar of General Interest
Venue: Lecture Hall
Laser beams can be used to decelerate gas phase atoms in an ultra-high vacuum chamber. A set of six counter-propagating red-detuned circularly polarized low intensity cw laser radiations originating from a a single source and a quadrupolar magnetic field produced by coils in an anti-Helmholtz configuration can control the atomic motion in a three dimensional space. Under certain optimum conditions of laser detuning, laser intensity and the magnetic field gradient the velocity dependent optical vicous force and the position dependent harmonic force will win over the atom’s tendency to escape and lower the atomic velocity as well as push them towards the centre of the trup. We shall describe the magneto-optic trap developed in our department for confinement of Rb atoms. The trap chamber is kept at one nano-Torr pressure and Rb samples are introduced at a pressure of 10-100 Nano-Torr. The cold atom cloud has an estimated temperature of 130 micro-Kelvin and the number of confined atoms is 106 in a cloud with an approximate radius of nearly 0.1 mm.the cloud can be compressed by increasing the field current. Further work on guiding of the cold atom cloud to a second trap for achieving Bose Einstein Condensation (BEC) will be discussed.
22-06-2007 At 11:30:00 AM
Speaker: Shanta Nivedita Mahapatra & Shambhavi Shukla, Banasthali Vidyapith, Rajasthan
Category: Summer Student Seminar
Venue: Library Lecture Hall
26-06-2007 At 04:00:00 PM
Speaker: Dr. Prasanta Karmakar, University of California Riverside, USA
Category: Seminar of General Interest
Venue: Lecture Hall
Nanostructures are produced on metal and semiconductor surfaces in a controllable manner via low energy ion bombardment. The resultant materials are probed with scanning probe microscopy, x-ray photoelectron spectroscopy and low energy ion scattering. A variety of nanostructures such as ripple, dot and hole are formed and controlled their shapes and sizes by tuning the ion beam parameters and ion target geometry. The self-organized nanoclusters produced by ion bombardment display quantum size effects. Neutralization of scattered alkali-metal ions is used to probe the electronic states of the nanoclusters.The work function change accompanying oxygen adsorption on metals is not always positive, as would be expected due to the surface dipole. I shall also discuss that the low energy alkali ions could be used to investigate the contribution of the dipole to the local potential near a Ta surface atom
09-07-2007 At 04:00:00 PM
Speaker: Dr. Jagjit Nanda, Technical Staff Member: Nanotechnology , Research and Advanced Engineering , Ford
Category: Colloquium
Venue: Lecture Hall
In this talk I shall provide a brief overview of technologies where nanoscience and technology can provide value addition to both existing technologies as well as to a few emerging ones. A few specific areas of applications such as nanocomposites, nanocatalysts and energy storage shall be discussed. The second part of the talk will demonstrate how basic physics can still be a useful tool to solve a practical problem associated with quantum dot lasing. I shall discuss the physics of nanocrystal lasing and demonstrate a procedure for fabricating novel core-shell nanostructures that can eliminate the problem of non-radiative auger transition that will eventually lead to single-exciton lasing.
11-07-2007 At 04:00:00 PM
Speaker: Dr. Ramesh Chandra, PDF, IOP, Bhubaneswar
Category: Seminar of General Interest
Venue: Lecture Hall
25-07-2007 At 04:00:00 PM
Speaker: Dr. H.Nandan, CTS, IIT, Kharagpur
Category: Seminar of General Interest
Venue: Lecture Hall
20-08-2007 At 04:00:00 PM
Speaker: Dr. R.K.Choudhury, NPD, BARC, Mumbai
Category: Colloquium
Venue: Lecture Hall
Abstract Nuclei as finite quantum objects exhibit a variety of structures in their ground and excited states. Collisions between two heavy nuclei at medium bombarding energies lead to different phenomena depending on the impact parameter of the collision. Various studies have indicated that the structure of projectile and target nuclei play important role in deciding the reaction dynamics in heavy ion collisions. The present talk will provide a glimpse of certain aspects of the effect of nuclear structure in heavy ion collisions leading to fusion, transfer and fission reactions.
22-08-2007 At 04:00:00 PM
Speaker: Mr.R. Amitshreeya, Department of Environmental Science, F.M. University, Balasore
Category: Seminar of General Interest
Venue: Lecture Hall
27-08-2007 At 04:00:00 PM
Speaker: Prof. Ashok Das, University of Rochester
Category: Colloquium
Venue: Lecture Hall
Hard thermal loop effective actions are quite useful in studying properties of quark-gluon plasma. They arise from loop corrections at high temperature have very unique properties. In this talk we will try to discuss using the proper time method of Schwinger how such interesting properties arise in the structure of the hard thermal loop effective action
29-08-2007 At 04:00:00 PM
Speaker: Dr. Surajit Sengupta, SNBCBS, Kolkata
Category: Seminar of General Interest
Venue: Lecture Hall
04-09-2007 At 05:00:00 PM
Speaker: Prof. S.Bhattacharya, Professor, TIFR , Mumbai
Category: Spceial Colloquium
Venue: Lecture Hall
Development of scientific institutions in post-colonial India was driven by a patriotic conviction that science and technology will lead to prosperity for the underdeveloped and impoverished nation. At the same time, global political alignments and vivid memories of colonial exploitation led to a protectionist policy for the fledgling domestic industry. This protectionism spilled over to basic science enterprises as well and blended seamlessly with the prevailing feudal patronage system. An unintended casualty of this spillage was an uncompromising commitment to excellence, the key ingredient for developing a robust scientific culture. In such a weakened state Indian science became easy prey to political influence-peddling and what is now an institutionalized lack of accountability. Finding a national consensus to dismantle the apparatus of patronage and protectionism is an essential step towards initiating a much-needed rescue process today, when the country and its Government are able and willing to allocate vast financial resources towards the development of science and technology in the country.
07-09-2007 At 04:00:00 PM
Speaker: Dr. Colin Benjamin, Centre de Physique Théorique 13288 Marseille Cedex 09, France
Category: Seminar of General Interest
Venue: Lecture Hall
Shot noise cross-correlations in Normal metal-Superconductor-Normal metal structures are discussed at arbitrary interface transparencies. Negative crossed conductance in such set-ups does not preclude the possibility of positive noise cross correlations for almost transparent contacts, which is interpreted as the signature of processes having both features of two-electron cotunneling and of double non local electron-hole process. Further the sign of noise cross-correlations can be controlled via the interface transparencies. A phenomenological approach based on renormalization group is also attempted in order to describe qualitatively the effects of interaction in the normal electrodes. Interactions can induce sign changes in the noise crossed correlations, especially for moderate or large interface transparencies
11-09-2007 At 04:00:00 PM
Speaker: Swarnendu Sarkar, IOP
Category: Seminar of General Interest
Venue: Lecture Hall
04-10-2007 At 04:00:00 PM
Speaker: Prof.Anirban Basu, IAS, Princeton
Category: Colloquium
Venue: Lecture Hall
String theory drastically modifies general relativity at small distances, and is believed to lead to a finite theory of quantum gravity. I will discuss higher derivative corrections to the Einstein-Hilbert action, in the context of type IIB superstring theory. Supersymmetry and string dualities play a crucial role in constructing these interactions in the low energy effective action
15-10-2007 At 04:00:00 PM
Speaker: Dr.K.L. Panigrahi, IIT, Gauhati
Category: TPSC Seminar
Venue: Lecture Hall
29-10-2007 At 04:00:00 PM
Speaker: Prof. L. Satpathy
Category: Colloquium
Venue: Lecture Hall
Presently about 2000 nuclei both naturally occurring and man made are known; and different mass formulae predict the survival of another 5000 nuclei which could be synthesised in the Laboratory. Accordingly, Radioactive Ion Beam (RIB) facilities are under construction in the major laboratories around the world to explore the entire nuclear landscape. The three actinide nuclei U(233), U(235) and Pu(239) in the stability valley are thermally fissile which have been mainly used in the reactor for energy generation. The question - if other nuclei in particular heavier Uranium isotopes having such features could exist and if so what will be their fission decay properties - is of serious experimental and theoretical importance. Attempts will be made to answer these questions in the present talk. Studies reveal a number of new fission properties of such nuclei, the most prominent one being a new mode of fission decay in which along with the two heavy fragments simultaneously about 2/3 prompt neutrons will be released at the time of scission. This is termed as "Multifragmentation Fission". Its implication for r-process nucleosynthesis in stellar evolution and energy generation will be discussed
15-11-2007 At 04:00:00 PM
Speaker: Prof. Monique Combescure, Institut de Physique Nucleaire, Lyon, France
Category: Seminar of General Interest
Venue: Lecture Hall
Two orthonormal bases in dimension d are said "mutually unbiased" if the hermitian scalar products of any vector in one base with any vector in the other base are in modulus equal to the inverse square root of d. One important issue is to determine the maximum number of mutually unbiased bases (MUB) for d dimensions. If d is a prime number or a power of a prime number it is known that this maximum number is d+1. We revisit this problem in both cases using the simple notions of Discrete Fourier Transform, of unitary Hadamard matrices, and of circulant matrices (for which the successive rows are circulant permutations of each other)
16-11-2007 At 04:00:00 PM
Speaker: Prof. J.-M. Richard,LPSC and Grenoble University, Grenoble, France
Category: Seminar of General Interest
Venue: Lecture Hall
Spin observables are very useful to improve our insight into themicrosocopic dynamics of exclusive reactions, inclusive reactions andparton distributions.Each spin observable is typically normalised to vary between -1 and +1.Pairs of observables of the same reaction are often constrained to asub-domain of the square [-1,+1]^2, such as the unit disk or a triangle.For triples of observables, the domain inside the cube [-1,+1]^3 canassume a variety of shapes: sphere, cone, pyramid, tetrahedron, etc.The corresponding inequalities can be derived by purely algebraicmethods, or from the positivity of the density matrices describing theinitial or final spin states of the reaction and its crossed channels.Examples will be given for the strangeness exchange reaction antiproton+proton -> antiLambda + Lambda, the photoproduction of pseudoscalarmesons, and the Soffer inequality for transversity distributions insidethe nucleon.
19-11-2007 At 04:00:00 PM
Speaker: Prof. Sachinath Mitra, Jadavpur University, Kolkata
Category: Colloquium
Venue: Lecture Hall
23-11-2007 At 04:00:00 PM
Speaker: Prof. Mukunda P.Das, The Australian National University Canberra, Australia.
Category: Colloquium
Venue: Lecture Hall
29-11-2007 At 04:00:00 PM
Speaker: Dr. S. Bedanta, University of Deisburg
Category: Experimental Physics Group Seminar
Venue: Lecture Hall
06-12-2007 At 04:00:00 PM
Speaker: Dr. Soma Sanyal, CCMT, IISc, Bangalore
Category: Seminar of General Interest
Venue: Lecture Hall
In this talk, we discuss the importance of the clustering coefficient in evolving networks. Wepropose a model for an evolving network where the attachment probability to an existing nodedepends on the number of links of the existing node and it’s age. The age of the node is modeled bya lifetime distribution whose parameters depend on the network being studied. We focus on citationnetworks and show that if the two probabilities are independent of each other, the evolution ofthe clustering coefficient depends on the lifetime distribution of the cited articles and their averagelifetime. Beyond the average citation lifetime, the clustering coefficient increases and reaches astationary value. However, in real citation networks, the citation lifetime of a paper depends onthe number of citations it has received previously. When we incorporate this in our model, wefind that the average clustering coefficient decreases. The degree distribution is always scale freeand only the power law exponent changes when the aging distribution is changed. The clusteringcoefficient is thus more sensitive to the aging pattern of the evolving network and is a bettermeasure for studying differences in the citation patterns in different disciplines over time. Thisresult can be extended to other networks where the age of a node is an important criterion forreceiving new links.PACS numbers: 89.75.Fb, 89.65.-s, 02.70.Rr
10-12-2007 At 04:00:00 PM
Speaker: Prof. Flavio Seno, University of Padova, Italy
Category: Colloquium
Venue: Lecture Hall
Globular proteins, the work house molecules of life, are linear chains of amino-acids which fold rapidly and reproducibly into their native conformations. An important goal in the protein problem is the prediction of the native state structure given the amino acid sequence of a protein. A vast semplification arises because the number of distinct folds adopted by proteins is limited to just a few thousand. This has led to a powerful method, called threading, for predicting the native state of a sequence: one mounts the sequence on candidate structures obtained as pieces of all known folds and determines the best fit structure through a scoring function which provides a measure of the interactions among the aminoacids. Here we will present a maximum entropy approach for inferring amino-acid interactions in proteins subject to constraints pertaining to the mean numbers of various types of equilibrium contacts. We will illustrate the method on simply models where we obtained very promising results. We will also show the flexibility of the method that can work very well even when the mean numbers of contacts are not known exactly. These results are suggesting that our maxent approach has the possibilty of being successfull when applied to real proteins
10-12-2007 At 04:00:00 PM
Speaker: Prof. Lee Chow, University of Central Florida, USA
Category: Seminar of General Interest
Venue: Lecture Hall
11-12-2007 At 04:00:00 PM
Speaker: Dr. A.K. Mohanty, IBM, USA
Category: Seminar of General Interest
Venue: Lecture Hall
12-12-2007 At 11:00:00 AM
Speaker: Prof. Lee Chow, University of Central Florida, USA
Category: Seminar of General Interest
Venue: Lecture Hall
13-12-2007 At 04:00:00 PM
Speaker: Prof. B.P. Das, Indian Institute of Astrophysics, Bangalore
Category: Seminar of General Interest
Venue: Lecture Hall
27-12-2007 At 04:00:00 PM
Speaker: Prof. Sumit R. Das, University of Kentucky
Category: Colloquium
Venue: Lecture Hall
27-12-2007 At 11:00:00 AM
Speaker: A. Maharana, Cambride Univ.
Category: High Energy Group Seminar
Venue: Lecture Hall