Papers by Keyword: Heavy Ion

Abstract: We studied DNA damages in heavy ion irradiation for its radiotherapy using molecular dynamics (MD) method. We adopted semi-empirical hybrid quantum mechanics/molecular mechanics (QM/MM) method of Amber in order to investigate the cleavage of chemical bond by heavy ion in our simulation. We found the cleavage of chemical bond, although the simulated energy of heavy ion turned out to be slightly higher than the one determined by experiment.

Abstract: Heavy ion tracks recorded in dielectric materials were found to have a width of 5-10 nm using SEM. Heavy ion beams were used for irradiation of Polymers and Muscovite mica to create Ion Track Filters (ITFs) using UNILAC facility at Darmstadt, Germany. The electrochemically etched pores of ITFs used would act as a template. The simple principle of electroplating is used to create heterostructures. The rate of deposition of metallic film depends upon current density, inter-electrode distance, cell voltage, electrolyte concentration and temperature etc. The use of ITFs looks quite promising in the fabrication of micro and nanostructures. The morphology of such structures produced through electrochemical methods and replicas of etched tracks in ITFs have been investigated in detail. The efficacy of the technique was tested for growth of quantum dots, fibers, cones, whiskers, micro and nano wires. A 3-dimensional ensemble of Cu-Se was grown electrochemically using ITF of Makrofol-KG. Replication of etched pores in ITFs has been used to develop microtubules. Presently, we are engaged to develop quantum dots, nanorods and nanowires of copper, iron and bismuth using Anodic Alumina Membranes (AAM), Polycarbonate ITFs and Reverse Micelle technique. The preliminary results of our investigations will be presented at NADPA-2008.

Abstract: In order to investigate the effect of stepwise change of irradiation temperature on pure copper, heavy ion irradiations under constant temperature and varying temperature conditions were performed. Specimens were irradiated up to 10dpa. In the temperature region of 473K ~ 673K, one-step temperature variation and periodic temperature variations were performed during irradiation. The resulting microstructures were compared with those induced by the irradiation at the constant temperature of 673K.