Estimation of radon concentration in groundwater in the mining zone of Haryana, India, for lungs and stomach annual effective dose.

The groundwater is being used for drinking and irrigation purposes in vast swathes of the Aravalli Mountain range. Since the radioisotope presence in groundwater is affected by the local mining processes, the radiation monitoring in groundwater of mining regions is of paramount importance. In the present work, we have estimated the 222Rn presence in the mining region of Aravalli in the southern part of Haryana. We measured the Radon concentration in 51 water samples from the intended area using the RAD7 alpha detector. The measured radon concentration in some of the water samples collected from the vicinity of the mining zone is higher than that of the United Nations Scientific Committee on the Effects of Atomic Radiation recommended value. Furthermore, we have estimated the annual effective doses for the lungs and stomach contributed by ingestion and inhalation. Though the calculated dose values in collected samples are not in the critical range, further monitoring of background radiation in the Aravalli region is required.

Nucleon-nucleon correlations inside atomic nuclei: synergies, observations and theoretical models.

While the main features of atomic nuclei are well described by nuclear mean-field models, there is a large and growing body of evidence which indicates an important additional role played by spatially-correlated nucleon-nucleon structures. The role of nucleonic structures was first suggested by Heidmann in 1950 to explain the pick-up reactions of energetic nucleons. Since then, a steady flux of new experimental evidence has confirmed the presence of similar structures inside atomic nuclei, dominated by correlations between pairs of nucleons. The role of these internal nucleon-nucleon correlations has been established using various energetic probes like photons, pions, leptons and hadrons. These correlated structures are essential for understanding the interaction of particles with nuclei and their presence provides an explanation of many specific nuclear phenomena, including backscattered protons, copious deuteron production, sub-threshold particle production, neutrino interactions with nuclei and the European Muon Collaboration effect. On the theoretical side, these measurements have stimulated a large number of phenomenological models specifically devised to address these enigmatic observations. While reviews exist for specific interactions, there is currently no published commentary which systematically encompasses the wide range of experimental signatures and theoretical frameworks developed thus far. The present review draws together the synergies between a wide range of different experimental and theoretical studies, summarizes progress in this area and highlights outstanding issues for further study.

Tuning the properties of graphene quantum dots by passivation.

The electronic and optical properties of graphene quantum dots (GQDs) of size less than 10 nm are different from those of graphene sheets due to quantum confinement effects. For analyzing their use in optoelectronic applications, it is very crucial to optimally tune the bandgap and engineer the controlling parameters. In the present work, a systematic investigation of the band gap of hexagonal GQDs has been carried out by examining their HOMO and LUMO energies. Passivation of dangling bonds of these GQDs has been carried out with the help of electron-withdrawing substituents in order to tune the band gap and engineer their optical properties such as absorption and emission spectra by carrying out the simulation with Density Functional Theory formalism using Gaussian 09 software. Carrying out passivation with electronegative element fluorine (F) effectively decreases the band gap of these QDs resulting in a redshift in the absorption spectra. The HOMO and LUMO topographical surfaces have been used to understand the absorption spectra. These surfaces show some σ-bond characteristics along with π-bond properties on passivating GQDs with the F-atom which further results in alteration of their energies and a corresponding decrease in their band gap. Here, the absorption is found to be dependent on the size of GQDs and the type of passivating atoms (H or F). The results thus obtained are found to be in good consonance with those reported in the literature engaging different methods. The present analysis may prove to be useful in improving the working of solar cells and other optoelectronic devices.