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PeV gamma rays from interactions of ultra high energy cosmic rays in the Milky Way
No full textRestricted Access. An open-access version is available at arXiv.org (one of the alternative locations)The PeV gamma ray background produced in the interactions of ultra high energy cosmic rays with the ambient matter and radiations during their propagation in the Milky Way has been calculated in this paper. If the primary ultra high energy cosmic rays are produced from Galactic point sources then those point sources are also emitting PeV gamma rays. We discuss that the detection of galactocentric PeV gamma rays in the future would be a signature of the presence of EeV cosmic accelerators in the Milky Way
Simple and low-cost ultramicroelectrode fabrication and characterization method for undergraduate students
No full textRestricted AccessA laboratory experiment is described in which students fabricate disk-shaped gold and platinum microelectrodes with diameters of 10–50 μm by sealing sodalime glass with metal microwires. The electrodes are characterized by performing cyclic voltammetry in aqueous and acetonitrile solution. Commercial microelectrodes are expensive (cost depends on the diameter of electrode) and may deter introduction of voltammetric experiments into laboratory classes at the undergraduate level. The students also fabricate a simple operational amplifier (op amp)-based potentiostat along with a low-current measuring device. This low-cost fabrication helps the students understand the details of instrumentation of a potentiostat with special knowledge in analog electronics. This experiment can be included in the electrochemistry laboratory course for undergraduate students. This experiment can also be incorporated into various undergraduate laboratory courses such as analytical chemistry, general chemistry, biochemistry, physical chemistry, and instrumentational methods of analysis
Digital information services and resources at the Raman Research Instititute (RRI) library: a case study
No full textRestricted AccessToday we live in an information age, where knowledge is power. Ever changing software tools and along with it the advancement in information technology and the World Wide Web have given rise to the electronic libraries and digital libraries. The advent of computer and information technology tools, have helped us for better organizing of information resources and effective rendering of service, thus increasing
the quality and quantity of value-added services in libraries and to fulfill the goal of library and information center to serve its community with well balanced, accessible and resourceful information faster. An attempt has been made to describe the digital information resources and services at the Raman Research Institute
(RRI) library
Energy deposition pro les and entropy in galaxy clusters
No full textOpen-accessWe report the results of our study of fractional entropy enhancement in the intra-cluster medium (ICM) of the clusters from the representative XMM-Newton cluster structure survey (REXCESS). We compare the observed entropy profile of these clusters with that expected for the ICM without any feedback, as well as with the introduction of preheating and entropy change due to gas cooling. We make the first estimate of the total, as well as radial, non-gravitational energy deposition up to r500 for a large, nearly flux-limited, sample of clusters. We find that the total energy deposition corresponding to the entropy enhancement is proportional to the cluster temperature (and hence mass), and that the energy deposition per particle as a function of gas mass shows a similar profile in all clusters, with its being more pronounced in the central region than in the outer region. Our results support models of entropy enhancement through AGN feedbac
