Universality of the saturation scale and the initial eccentricity in heavy ion collisions

Recent estimates that Color Glass Condensate initial conditions may generate a larger initial eccentricity for noncentral relativistic heavy ion collisions (relative to the initial eccentricity assumed in earlier hydrodynamic calculations) have raised the possibility of a higher bound on the viscosity of the Quark Gluon Plasma. We show that this large initial eccentricity results in part from a definition of the saturation scale as proportional to the number of nucleons participating in the collision. A saturation scale proportional to the nuclear thickness function (and therefore independent of the probe) leads to a smaller eccentricity, albeit still larger than the value used in hydrodynamic models. Our results suggest that the early elliptic flow in heavy ion collisions (unlike multiplicity distributions) is sensitive to the universality of the saturation scale in high energy QCD.Comment: 5 pages, 3 figures, RevTE

Pesticide induced physiological and behavioural changes in an estuarine teleost Therapon jarbua (Forsk)

Static bioassays were conducted with pesticides like PP'-DDT, Dimethoate (Rogor) and Carbaryl (Sevin) to determine the median lethal concentrations (LC sub(50)) on an estuarine teleost Therapon jarbua (Forsk). The respiration rates of fishes exposed to pesticides, as well as those of controls were determined. Respiration abnormalities were noticed in treated fishes. The metabolic rates are generally higher in treated fishes than in the controls. The behaviour of fishes exposed to LC sub(25) (96h) concentrations of pesticides is discussed. Estuarine fishes appear to be more sensitive and susceptible to pesticides than fresh water fishes. The pesticides affect the locomotory and swimming behaviour of fishes. Loss in weight of fishes exposed to LC sub(50) (96 h) concentration of pesticides was also estimated. The present report gives a comprehensive account of the toxic nature of these pesticides to fishes

Testing saturation with diffractive jet production in deep inelastic scattering

We analyse the dissociation of a photon in diffractive deep inelastic scattering in the kinematic regime where the diffractive mass is much bigger than the photon virtuality. We consider the dominant q\bar{q}g component keeping track of the transverse momentum of the gluon which can be measured as a final-state jet. We show that the diffractive gluon-jet production cross-section is strongly sensitive to unitarity constraints. In particular, in a model with parton saturation, this cross-section is sensitive to the scale at which unitarity effects become important, the saturation scale. We argue that the measurement of diffractive jets at HERA in the limit of high diffractive mass can provide useful information on the saturation regime of QCD.Comment: 12 pages, 5 figures, misprints corrected, published versio

Need of Improved Non-Destructive Technique for the Surface Condition Monitoring of High Speed Steel (HSS) Work Rolls

Over the last few years, the use of work rolls for hot rolling of flat steel has changed from clear chill rolls to indefinite chill, then came high chrome steel and now High Speed tool Steel (HSS). The hardness of HSS roll reaches 80/85 ShC, hence it becomes very much crack-sensitive and the developed crack is usually oriented parallel to the roll axis and propagates in a non-radial direction. In the next phase, a fatigue “cat’s tongue” like fracture band propagates progressively in a circumferential direction running more or less parallel to the barrel surface. The direction of propagation is opposite to that of the direction of roll rotation. Crack propagation develops within the working surface of the roll, gradually increasing in depth and width followed by a large surface spall of the overlying barrel surface. Hence it is highly recommended to eliminate all kinds of surface cracks, whenever these rolls are reground, otherwise these `cats – tongue’ band type spalls may lead to abnormal failure. This paper presents the necessity of development of improved non-destructive technique for the crack detection of HSS rolls and also highlights the recent attempts at Tata Steel in collaboration with CSIR-National Metallurgical Laboratory, Jamshedpur to develop surface wave based ultrasonic technique to detect fine cracks on the barrel surface of HSS rolls to optimise the grinding procedure for having crack free roll surface

High energy factorization in nucleus-nucleus collisions II - Multigluon correlations

We extend previous results (arXiv:0804.2630 [hep-ph]) on factorization in high-energy nucleus-nucleus collisions by computing the inclusive multigluon spectrum to next-to-leading order. The factorization formula is strictly valid for multigluon emission in a slice of rapidity of width \Delta Y< 1/\alpha_s. Our results show that often neglected disconnected graphs dominate the inclusive multigluon spectrum and are essential to prove factorization for this quantity. These results provide a dynamical framework for the Glasma flux tube picture of the striking "ridge"-like correlation seen in heavy ion collisions.Comment: 29 page

Sintering characteristics and kinetics of acidic haematite ore pellets with and without mill scale addition

Haematite ore pellets require very high induration temperature (>1573 K) while, magnetite ore pellets require much lower temperature due to the oxidation of magnetite during induration. Mixing of some magnetite in haematite ore can improve the sintering property of pellets during induration. Mill scale is a waste material of steel plant which contains mainly FeO and Fe3O4. It can also be blended in haematite ore pellet mix which can enhance diffusion bonding and recrystallisation bonding and facilitate sintering at the lower temperature like magnetite ore. The extent of improvement in sintering property, sintering mechanism and its kinetics in the presence of mill scale is very imperative to study. In current study, the sintering characteristics of acidic iron ore pellet with 15% mill scale and without mill scale has been studied separately through microstructure observation, apparent porosity measurement and volume change. The volume changes due to heating at varying temperature and time has been measured by mercury displacement method and the data has been exploited for sintering kinetics study, wherein,extent of sintering α has a power relation with time. Several kinetics parameters such as time exponent (n), rate constant (k) and activation energies have been estimated for above two pellets and compared. While acidic pellet without mill scale requires 385 k cal mol−1, acidic pellet with 15% mill scale requires only 310 k cal mol−1 activation energy

Mill scale as a potential additive to improve the quality of hematite ore pellet

Hematite pellet is required to be indurated at very high temperature to achieve its good strength as there is no exothermic heat of oxidation unlike magnetite. As mill scale contains mainly FeO and Fe3O4, any minor amount of its addition in pellet can provide in situ heat and enhance diffusion bonding and sintering. In this study, the mill scale generated in steel plant is added asmagnetite input in hematite pellet both in acidic and in basic condition. It has been found that in fluxed pellet, mill scale can improve the properties of pellet. In acidic pellet, the induration temperature has been reduced to a great extent (1250–1275°C) and all properties have been found to be improved due to the addition of 15%mill scale. Mill scale shows enough potential to eliminate the flux addition in producing blast furnace quality pellet from hematite ore. Thus, the flux free acidic pellet has been developed even at very low temperature (1275°C) of induration