Deformability Tests of Pure Niobium

research team at the University of Miskolc's Faculty of Materials Science and Technology has signed a cooperation agreement with the Geneva-based European Organization for Nuclear Research (CERN) for testing of the materials employed in the Crab Cavities will be installed in the next generation of the LHC (the so-called High Luminosity Large Hadron Collider – HL-LHC). At the University of Miskolc, high purity niobium rolling experiments were carried out in conventional (unidirectional) and cross-rolled manners in order to increase the deep drawability of the final sheet. The deformability of niobium was measured by Watts- Ford and compression tests. The microstructure and anisotropy (texture) results of the initial material and the straight-rolled products are reported

Long-lasting molecular alignment: Fact or fiction?

13 pages, 10 figures, 1 appendix.It has been suggested that appropriate periodic sequences of laser pulses can maintain molecular alignment for arbitrarily long times [J. Ortigoso, Phys. Rev. Lett. 93, 073001 (2004)]. These aligned states are found among the cyclic eigenstates of truncated matrix representations of the one-period time propagator U(T,0). However, long time localization of periodic driven systems depends on the nature of the spectrum of their exact propagator; if it is continuous, eigenstates of finite-basis propagators cease to be cyclic, in the long time limit, under the exact time evolution. We show that, for very weak laser intensities, the evolution operator of the system has a point spectrum for most laser frequencies, but for the laser powers needed to create aligned wave packets it is unknown if U(T,0) has a point spectrum or a singular continuous spectrum. For this regime, we obtain error bounds on the exact time evolution of rotational wave packets that allow us to determine that truncated aligned cyclic states do not lose their alignment for millions of rotational periods when they evolve under the action of the exact time propagator.Financial support from the Spanish Government, under Project Nos. FIS2004-02558 and FIS2007-61686 is acknowledged. The authors also thank the Hungarian Spanish Intergovernmental Science and Technology Cooperation Program for support through Project Nos. ESP-17/2006 and HH2006- 0023. M.R. is grateful to the Ministerio de Educación y Ciencia of Spain for a Ramón y Cajal grant.Peer reviewe

In-situ investigation of the decomposition process in cold-rolled Nb53Ti47 alloy

The multi-layer composite development primarily aims to develop and test the components of the next generation of hadron colliders (e.g., Large Hadron Collider - LHC) consisting of superconducting raw materials. Multilayer sheet is very similar to the commonly used NbTi wire products, a 2D version of the commercial wire. These composites consist of layers such as NbTi superconductor, Nb diffusion barrier (between NbTi and Cu) and Cu stabilizer. In β-NbTi superconducting alloys, α-Ti precipitates are primary flux pinning centers that maintain stable superconductivity. A multi-step series of heat treatments and cold-forming processes can develop the flux pinning centers. Practically, this process means three heat treatments of constant period and temperature and drawing or rolling between the heat treatments.The study aimed to describe the behavior of the cold-rolled (ε = 3.35) Nb53Ti47w% alloys during isothermal heating at 673 K as a function of heating time. The processes during the aging were investigated by the in-situ XRD method in the heating chamber. The X-ray diffraction patterns were evaluated by Rietveld refinement. The thermally activated spinodal decomposition and precipitation processes were described based on the phases identified at the individual heat treatment steps and their lattice parameters. The in-situ study also revealed an increase in α-Ti precipitation with time and decomposition that co-occurs. This is the basic study that prepares the applicability of the alloy