A full quantal theory of one-neutron halo breakup reactions

We present a theory of one-neutron halo breakup reactions within the framework of post-form distorted wave Born approximation wherein pure Coulomb, pure nuclear and their interference terms are treated consistently in a single setup. This formalism is used to study the breakup of one-neutron halo nucleus 11Be on several targets of different masses. We investigate the role played by the pure Coulomb, pure nuclear and the Coulomb-nuclear interference terms by calculating several reaction observables. The Coulomb-nuclear interference terms are found to be important for more exclusive observables.Comment: 22 pages latex, 9 figures, submitted to Phy. Rev.

Preteatment of iron for steel production in the Durgapur steel project

PRETREATMENT, as the term implies, is the treatment or conditioning of molten pig iron before it is charged into a steelmaking furnace with a view to improve the speed and quality of steel production. Steelmaking is funda-mentally an oxidation process followed by varying degrees of reduction (deoxidation) of the over-oxidized metal. The metallurgical load during steelmaking in the openhearth furnace can be appreciably reduced and hence the speed of production appreciably increased if some of the elements in the iron puticulnly Si and P, could be partially remo-ved. The oxidation cf a large part of Si and to some ext-ent of P in the molten pig iron, before it is charged into a basic OH furnace has therefore engaged the attention of many steelmakers

Development of Creep-Resistant Alloy Steels

THE' major part of the industrial uses of high creep-resistant alloys at elevated temperatures and fairly high stresses has been due to the development of the gas turbine and the jet-propulsion engines. Although Howe1 as far back as 1885 made investigation on the extension of metals as function of time , and creep data were reported by Andrade2 in 1911, there was very little technical interest in the phenomena of creep or i n creep-resistant metals and alloys until shortly after World War I, when better materials were required for aero-engine parts, for the petroleum and chemical industries at fairly high temperatures 400°- 600°C.) and sometimes under severely corrosive conditions, for parts of industrial furnaces at high temperatures and for steam turbines. The demand of mate-rials resistant to creep steadily increased during World War II. But the greatest resistance to creep at high temperatures and fairly high stresses have been due to the development of gas turbine and jet-propul- sion engines. An attempt has been made in this paper to indicate briefly some of the metallurgical factors involved in the development of high creep-resistant alloy steels with particular reference to turbine materials

Some Recent Trends on Iron and Steel Research and Control Methods

Investigations on raw-materials and sintering charact-eristics : Although in recent years a considerable amount of work has been done towards beneficiation and treatment of blast furnace raw materials leading to increased production in a given furnace, there is considerable scope for further investigation in this field with reference to indigenous materials and particularly sintering of ore blended with other Materials. Scientific definition and standardisation of so-called ''Sintering characteris-tics" "Reducibility of Sinter", need further studies and the effects of different constituents and sizes on the rate of sinter production and allied activities may very well lead to fruitful results. Some of the. recent trends in this connection are : (i) quick analysis of constituents in the sintered material by X-ray fluoroxopy--particularly the FeO, Fe_03 and Fe30a contents by diffraction before and after a given treatment. (i i) effects of injection of oxygen on the one hand and reducing gases ova the other during sintering. It has been found for example that injection of 02 instead of raising the maximum temperature T Max and narrowing the zone of combustion, lowers the Tinax value and widens the zone of combustion. This is because the surface activity of coke increases with oxygen pressure and hence the ignition temperature is low- ered with the result that combustion starts before the charge is preheated to a higher temperature.This results in a, widening of the combustion zone and lowering of Tmax. (iii) Investigations on "Reducibility of Sinter" either by varying the CO concentration at definite time intervals and measuring the amount of oxygen removal or preferably by the SCICE method -developed rece- ntly by the British Iron and Steel Research Assoc- iation. (1v) Blending of CaO in sinter is helpful in reducing the thermal requirements and hence coke consumption and therefore helpful for reducing S in pig iron

Generalized Hawking-Page Phase Transition

The issue of radiant spherical black holes being in stable thermal equilibrium with their radiation bath is reconsidered. Using a simple equilibrium statistical mechanical analysis incorporating Gaussian thermal fluctuations in a canonical ensemble of isolated horizons, the heat capacity is shown to diverge at a critical value of the classical mass of the isolated horizon, given (in Planckian units) by the {\it microcanonical} entropy calculated using Loop Quantum Gravity. The analysis reproduces the Hawking-Page phase transition discerned for anti-de Sitter black holes and generalizes it in the sense that nowhere is any classical metric made use of.Comment: 9 Pages, Latex with 2 eps figure

Low carbon high chromium alloy without low carbon ferro-chrome

As an alloying element, chromium is a component of numerous grades of steels and special alloys. It is well known that steel alloyed with chromium acquires valuable physical properties. Due to the beneficial effects on mechanical & chem- ical properties of steel , chromium is widely used in the manufacture of structural, tool and special steel. Because of the useful properties of chromium steel it plays an important part in the construction of many machine parts and equipment for handling and production in a modern steel plant

Some Studies on Recovery & Oxidation Characteristics of Copper by Thermoelectric Phenomenon

It is well known that the junction of two dissimilar metals is the seat of thermoelectric force which can be used for the measurement of temperature.For this purpose usually dissimilar metals and/or alloys are used . In such cases the metals or alloys invariably differ in chemical composition.Although some work has been done to investigate the changes in the thermoelectric properties of the same metal or alloy due to some physical changes ( without any change in chemical composition ),not much of work has been , done to study minute changes occurring in metals and alloys which do not appreciably affect either the microstructure or the mechanical properties. For example, neither the microstructure nor such mechanical properties as hardness, tensile strength and ductility undergo any appreciable change during the so-called ' recovery stages' of cold-worked metals and alloys or the so-called ' pre -precipitation stages'during ageing, tempering and other thermal treatments of metals and alloys.An attempt has been made in this investigation to show that changes in the thermoelectric properties of metals and alloys may well be taken advantage of to detect minute changes in metals and alloys -be it on the surface or inside the volume. In a pure specimen of copper wire it has been shown that (i) there are detectable and continuous changes in the thermoelectric properties throughout the recovery stage of the cold-worked specimen,and (ii) there are very sharp discontinuities in the e.m.f. temperature plot in the initial stages of film formation during heating in air. Further work is in progress to detect the changes in the initial stages of ageing, tempering and other transformations -isothermal or otherwise-in other metals and alloys

Dynamics of Fluctuation Dominated Phase Ordering: Hard-core Passive Sliders on a Fluctuating Surface

We study the dynamics of a system of hard-core particles sliding downwards on a one dimensional fluctuating interface, which in a special case can be mapped to the problem of a passive scalar advected by a Burgers fluid. Driven by the surface fluctuations, the particles show a tendency to cluster, but the hard-core interaction prevents collapse. We use numerical simulations to measure the auto-correlation function in steady state and in the aging regime, and space-time correlation functions in steady state. We have also calculated these quantities analytically in a related surface model. The steady state auto-correlation is a scaling function of t/L^z, where L is the system size and z the dynamic exponent. Starting from a finite intercept, the scaling function decays with a cusp, in the small argument limit. The finite value of the intercept indicates the existence of long range order in the system. The space-time correlation, which is a function of r/L and t/L^z, is non-monotonic in t for fixed r. The aging auto-correlation is a scaling function of t_1 and t_2 where t_1 is the waiting time and t_2 the time difference. This scaling function decays as a power law for t_2 \gg t_1; for t_1 \gg t_2, it decays with a cusp as in steady state. To reconcile the occurrence of strong fluctuations in the steady state with the fact of an ordered state, we measured the distribution function of the length of the largest cluster. This shows that fluctuations never destroy ordering, but rather the system meanders from one ordered configuration to another on a relatively rapid time scale