The CPLEAR detector at CERN

The CPLEAR collaboration has constructed a detector at CERN for an extensive programme of CP-, T- and CPT-symmetry studies using ${\rm K}^0$ and $\bar{\rm K}^0$ produced by the annihilation of $\bar{\rm p}$'s in a hydrogen gas target. The ${\rm K}^0$ and $\bar{\rm K}^0$ are identified by their companion products of the annihilation ${\rm K}^{\pm} \pi^{\mp}$ which are tracked with multiwire proportional chambers, drift chambers and streamer tubes. Particle identification is carried out with a liquid Cherenkov detector for fast separation of pions and kaons and with scintillators which allow the measurement of time of flight and energy loss. Photons are measured with a lead/gas sampling electromagnetic calorimeter. The required antiproton annihilation modes are selected by fast online processors using the tracking chamber and particle identification information. All the detectors are mounted in a 0.44 T uniform field of an axial solenoid of diameter 2 m and length 3.6 m to form a magnetic spectrometer capable of full on-line reconstruction and selection of events. The design, operating parameters and performance of the sub-detectors are described.

Effects of solidification kinetics on microstructure formation in binary Sn-Cu solder alloys

Three binary Sn-Cu solder alloys of near-eutectic composition have been directionally solidified at different growth rates. The competition between primary tetragonal Sn cells/dendrites and eutectic is interpreted with the coupled zone concept. It is also found that Sn-Cu is a weakly irregular eutectic system with CuSn leading the eutectic, but two different eutectic morphologies (coarse and fine) form simultaneously during eutectic growth. At higher growth rates, the eutectic interface breaks down into a cellular eutectic with the fine eutectic in the centre of the cells and the coarse one at the cell boundaries. This is explained by the segregation of Pb impurities ahead of the eutectic interface

Mixed mode fracture behavior of welded wood joints investigated with the Arcan test

Friction welding of wood is an assembly method that is still under investigation and development. A possible application for welded wood joints is the fabrication of multi-layered panels (i.e., cross-laminated panels). In an effort to model the behavior of such products, work is needed to characterize the mechanical strength and fracture properties of welded joints produced with parallel and crossgrain orientations. The present work addresses combined experimental and numerical investigations into the strength and fracture characterization of welded wood joints. The Arcan test setup is used for the experimental mechanical characterization. Numerical and experimental strength analyses are carried out to investigate the effect of the wood’s fiber orientation and in-plane loading direction on the joint strength and fracture toughness. The results show that the orientation of the fibers does not affect the tensile and shear strength (2.3 and 7 MPa, respectively). In the case of fracture, the virtual crack closure technique is used in a finite element model to determine the critical values of energy release rate in pure and mixed modes. A mixed mode fracture criterion of the welded joint is determined

Effects of Growth Rates and Compositions on Dendrite Arm Spacings in Directionally Solidified Al-Zn Alloys

Dendritic spacing can affect microsegregation profiles and also the formation of secondary phases within interdendritic regions, which influences the mechanical properties of cast structures. To understand dendritic spacings, it is important to understand the effects of growth rate and composition on primary dendrite arm spacing (lambda(1)) and secondary dendrite arm spacing (lambda(2)). In this study, aluminum alloys with concentrations of (1, 3, and 5 wt pct) Zn were directionally solidified upwards using a Bridgman-type directional solidification apparatus under a constant temperature gradient (10.3 K/mm), resulting in a wide range of growth rates (8.3-165.0 mu m/s). Microstructural parameters, lambda(1) and lambda(2) were measured and expressed as functions of growth rate and composition using a linear regression analysis method. The values of lambda(1) and lambda(2) decreased with increasing growth rates. However, the values of lambda(1) increased with increasing concentration of Zn in the Al-Zn alloy, but the values of lambda(2) decreased systematically with an increased Zn concentration. In addition, a transition from a cellular to a dendritic structure was observed at a relatively low growth rate (16.5 mu m/s) in this study of binary alloys. The experimental results were compared with predictive theoretical models as well as experimental works for dendritic spacing. (C) The Minerals, Metals & Materials Society and ASM International 201

The CPLEAR detector at CERN

The CPLEAR collaboration has constructed a detector at CERN for an extensive programme of CP-, T- and CPT-symmetry studies using K-0 and <(K)over bar (0)> produced by the annihilation of <(p)over bar ‘s> in a hydrogen gas target. The K-0 and <(K)over bar (0)> are identified by their companion products of the annihilation K(+/-)pi(-/+) which are tracked with multiwire proportional chambers, drift chambers and streamer tubes. Particle identification is carried out with a liquid Cherenkov detector for fast separation of pions and kaons and with scintillators which allow the measurement of time of flight and energy loss. Photons are measured with a lead/gas sampling electromagnetic calorimeter. The required antiproton annihilation modes are selected by fast online processors using the tracking chamber and particle identification information. All the detectors are mounted in a 0.44 T uniform field of an axial solenoid of diameter 2 m and length 3.6 m to form a magnetic spectrometer capable of full on-line reconstruction and selection of events. The design, operating parameters and performance of the subdetectors are described