Tata Institute of Fundamental Research

About: Tata Institute of Fundamental Research is a education organization based out in Mumbai, Maharashtra, India. It is known for research contribution in the topics: Magnetization & Large Hadron Collider. The organization has 7786 authors who have published 21742 publications receiving 622368 citations. The organization is also known as: TIFR.

Synthesis and Characterization of ReS2 and ReSe2 Layered Chalcogenide Single Crystals

Abstract: We report the synthesis of high-quality single crystals of ReS2 and ReSe2 transition metal dichalcogenides using a modified Bridgman method that avoids the use of a halogen transport agent. Comprehensive structural characterization using X-ray diffraction and electron microscopy confirm a distorted triclinic 1T′ structure for both crystals and reveal a lack of Bernal stacking in ReS2. Photoluminescence (PL) measurements on ReS2 show a layer-independent bandgap of 1.51 eV, with increased PL intensity from thicker flakes, confirming interlayer coupling to be negligible in this material. For ReSe2, the bandgap is weakly layer-dependent and decreases from 1.31 eV for thin layers to 1.29 eV in thick flakes. Both chalcogenides show feature-rich Raman spectra whose excitation energy dependence was studied. The lower background doping inherent to our crystal growth process results in high field-effect mobility values of 79 and 0.8 cm2/(V s) for ReS2 and ReSe2, respectively, as extracted from FET structures fabric...

Shock acceleration as origin of the radio relic in A 521

Abstract: Aims. We present new high sensitivity observations of the radio relic in A521 carried out with the Giant Metrewave Radio Telescope at 327 MHz and with the Very Large Array at 4.9 and 8.5 GHz. Methods. We imaged the relic at these frequencies and carried out a detailed spectral analysis, based on the integrated radio spectrum between 235 MHz and 4.9 GHz, and on the spectral index image in the frequency range 327–610 MHz. To this aim we used the new GMRT observations and other proprietary as well as archival data. We also searched for a possible shock front co–located with the relic on a short archival Chandra X–ray observation of the cluster. Results. The integrated spectrum of the relic is consistent with a single power law; the spectral index image shows a clear trend of steepening going from the outer portion of the relic toward the cluster centre. We discuss the origin of the source in the light of the theoretical models for the formation of cluster radio relics. Our results on the spectral properties of the relic are consistent with acceleration of relativistic electrons by a shock in the intracluster medium. This scenario is further supported by our finding of an X–ray surface brightness edge coincident with the outer border of the radio relic. This edge is likely a shock front.

Quarkonium production in hadronic collisions

Abstract: We summarize the theoretical description of charmonium and bottonium production in hadronic collisions and compare it to the available data from hadron-nucleon interactions. With the parameters of the theory established by these data, we obtain predictions for quarkonium production at RHIC and LHC energies.