Kiran Kumar

Chemical equilibration and thermal dilepton production from the quark gluon plasma at finite baryon density

The chemical equilibration of a highly unsaturated quark-gluon plasma has been studied at finite baryon density. It is found that in the presence of a small amount of baryon density, the chemical equilibration for gluon becomes slower and the temperature decreases less steeply as compared to the baryon free plasma. As a result, the space time integrated yield of dilepton is enhanced if the initial temperature of the plasma is held fixed. Even at a fixed initial energy density, the suppression of the dilepton yields at higher baryochemical potential is compensated, to a large extent, by the slow cooling of the plasma.

Hard photon production from unsaturated quark gluon plasma at two loop level

Abstract The hard photon production from bremsstrahlung and annihilation with scattering that arise at two-loop level are estimated for a chemically non-equilibrated quark–gluon plasma in the framework of Hard Thermal Loop (HTL) resummed effective field theory. The rate of photon production is found to be suppressed due to unsaturated phase space compared to equilibrated plasma. For an unsaturated plasma, unlike the effective one-loop case, the reduction in the effective two-loop processes is found to be independent of gluon fugacity, due to an additional collinear enhancement arising from the decrease in thermal quark mass but strongly depends on quark and antiquark fugacities. It is also found that the photon production is dominated by bremsstrahlung mechanism, since the phase space suppression is higher for annihilation with scattering, in contrast to the equilibrated plasma where annihilation with scattering dominates the photon production.

Mass asymmetry dependence of fusion time-scales in11B+237Np and12C,16O,19F+232Th reactions in a dynamical trajectory model

Dynamical trajectory calculations were carried out for the reactions of11B+237Np and12C,16O and19F+232Th, having mass asymmetries on either side of the Businaro-Gallone critical mass asymmetry αBG, in order to examine the mass asymmetry dependence of fusion reactions in these systems. The compound nucleus formation times were calculated as a function of the partial wave of the reaction for all the systems. This study brings out that for systems with ααBG, which is caused by the dynamical effects involved in the large scale shape changes taking place in the fusion process as well as due to the interplay between the thermal and the collective motion during the collision process. The calculated time scales are comparable to the experimental values derived from the pre-fission neutron multiplicity measurements.

Prompt neutron emission spectra and multiplicities in the thermal neutron induced fission of235U

The emission spectra of prompt fission neutrons from mass and kinetic energy selected fission fragments have been measured in235U(nth,f). Neutron energies were determined from the measurement of the neutron time of flight using a NE213 scintillation detector. The fragment energies were measured by a pair of surface barrier detectors in one set of measurements and by a back-to-back gridded ionization chamber in the second set of measurements. The data were analysed event by event to deduce neutron energy in the rest frame of the emitting fragment for the determination of neutron emission spectra and multiplicities as a function of the fragment mass and total kinetic energy. The results are compared with statistical model calculations using shell and excitation energy dependent level density formulations to deduce the level density parameters of the neutron rich fragment nuclei over a large range of fragment masses.

Investigation of arsenic accumulation and biochemical response of in vitro developed Vetiveria zizanoides plants

Vetiver grass (Vetiveria zizanoides L. Nash) is found to be a suitable candidate for the phytoremediation of heavy metals. An investigation of arsenic (As) accumulation, translocation and tolerance was conducted in V. zizanoides plantlets upon exposure to different concentrations of arsenic (10, 50, 100 and 200µM) for 7 and 14 d. V. zizanoides plants were found effective in remediation of As, maximum being at 200µM after 14 d of exposure. The results of TBARS and photosynthetic pigments demonstrated that plants did not experience significant toxicity at all the concentrations of As after 7 days, however an increase in their level was found after 14 d. The up-regulation of antioxidant enzyme activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), catalase (CAT) and glutathione s-transferase (GST) in a coordinated and complementary manner enhanced tolerance to plants against arsenic induced oxidative stress. Taken together, the results indicated that in vitro developed plants of V. zizanoides have the potential to remediate and tolerate varying levels of As.

Effect of baryon density on parton production, chemical equilibration, and thermal photon emission from the quark gluon plasma

The effect of baryon density on parton production processes of

Photon production from quark gluon plasma at finite baryon density

gg\rightleftharpoons ggg

Dissipative phenomena in a chemically nonequilibrated quark gluon plasma

and

Enhanced proteasomal activity is essential for long term survival and recurrence of innately radiation resistant residual glioblastoma cells

gg\rightleftharpoons q{\bar q}

A case study on application of HAZOP for intermediate level radioactive liquid waste treatment facility

is studied using full phase space distribution function and also with inclusion of quantum statistics i.e. Pauli blocking and Bose enhancement factors, in the case of both saturated and unsaturated quark gluon plasma. The rate for the process