Thermodynamic database of the phase diagrams in copper base alloy systems

通讯作者地址: Ishida, K (通讯作者), Tohoku Univ, Grad Sch Engn, Dept Mat Sci, Aoba Yama 02, Sendai, Miyagi 9808579 Japan 地址: 1. Tohoku Univ, Grad Sch Engn, Dept Mat Sci, Sendai, Miyagi 9808579 Japan 2. Xiamen Univ, Dept Mat Sci & Engn, Xiamen 361005, Peoples R China 电子邮件地址: [email protected] thermodynamic database on the phase equilibria of the copper base alloys, including Cu-X binary system and Cu-Fe, Cu-Ni, Cu-Cr base ternary systems has been developed by the Calculation of Phase Diagrams (CALPHAD) method. The thermodynamic parameters describing Gibbs energies of the different phases have been evaluated by optimizing experimental data of phase equilibria and thermodynamic properties. The present thermodynamic database can provide much information such as stable and metastable phase equilibria, phase fraction, liquidus projection and various thermodynamic quantities and so on, which is expected to play an important role in the design of copper base alloys. (c) 2004 Elsevier Ltd. All rights reserved

Thermodynamic calculation of phase equilibria in the Cu-Ni-Zn system

通讯作者地址: Jiang, M (通讯作者), Tohoku Univ, Grad Sch Engn, Dept Mat Sci, Sendai, Miyagi 9808579 Japan 地址: 1. Tohoku Univ, Grad Sch Engn, Dept Mat Sci, Sendai, Miyagi 9808579 Japan 2. Xiamen Univ, Dept Mat Sci & Engn, Xiamen 361005, Peoples R China 3. Univ Sofia, Fac Chem, Sofia 1164, Bulgaria 电子邮件地址: [email protected] ternary system of Cu-Ni-Zn has been thermodynamically analyzed based on extensive experimental information and reasonable thermodynamic modeling work by using the CALPHAD approach. A self-consistent set of thermodynamic parameters has been obtained, and the experimentally determined phase equilibria in the whole composition range except for the Zn-rich portion have been critically reproduced. The thermodynamic description established in this work can be used in predicting the phase relationships and thermodynamic properties in the Cu-Ni-Zn system. (c) 2004 Elsevier Ltd. All rights reserved

Experimental determination and thermodynamic calculation of the phase equilibria in the Cu-Cr-Nb and Cu-Cr-Co systems

通讯作者地址: Wang, CP (通讯作者), Xiamen Univ, Coll Mat, Dept Mat Sci & Engn, 422 Siming S Rd, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, Coll Mat, Dept Mat Sci & Engn, Xiamen 361005, Peoples R China 2. Xiamen Univ, Res Ctr Mat Design & Applicat, Xiamen 361005, Peoples R China 3. Tohoku Univ, Grad Sch Engn, Dept Mat Sci, Sendai, Miyagi 9808579 Japan 电子邮件地址: [email protected] equilibria in the Cu-Cr-Nb and Cu-Cr-Co systems were, respectively, determined by metallography, X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive X-ray (SEM-EDX) techniques. The thermodynamic assessments of the Cu-Cr-Nb and Cu-Cr-Co systems were carried out by using CALPHAD (CALculation of PHAse Diagrams) method on the basis of the experimental data measured by the present and previous works. The Gibbs free energies of the liquid and solid solution phases were described by the subregular solution model, and those of intermetallic compounds were described by the sublattice model. A consistent set of the thermodynamic parameters has been obtained, and the evaluated thermodynamic parameters lead to a better fit between calculated results and experimental data in both the Cu-Cr-Nb and Cu-Cr-Co systems. (C) 2008 Elsevier B.V. All rights reserved.National Natural Science Foundation of China 50425101 50771088 Ministry of Education, PR China 20050384003 707037 Core Research for Evolutional Science, and Technology (CREST) Japan Science and Technology Agency (JST

BEAM BACKGROUND SIMULATION FOR SUPERKEKB / BELLE-II

Abstract The Belle experiment is now being upgraded to the Belle II experiment designed for a 40 times higher luminosity. Such a high luminosity is realized by the SuperKEKB collider where beam-induced background rates are expected to be much higher than those of KEKB. This poses a serious challenge for the design of the machine-detector interface. We have thus carried out a GEANT4-based beam background simulation for Touschek effect. We describe the method of generating background particles and present the result of simulation. SUPERKEKB AND BELLE-II SuperKEKB, an upgraded of the KEKB collider, will provide a prove to search for new physics beyond the Standard Model, thanks to much larger data sample. The target luminosity of SuperKEKB, 80 × 10 34 cm −1 s −1 , is 40 times higher than that of KEKB. The upgrade is based on so-called "Nano-beam scheme". The basic idea of this scheme is to squeeze the vertical beta function at the interaction point (IP). The vertical beta function at IP is 20 times smaller than KEKB. In addition, the total beam currents will be doubled to achieve 40 times higher luminosity. The basic parameter of SuperKEKB is summarized in TOUSCHEK EFFECT Touschek effect is the most dangerous background at SuperKEKB with "Nano-beam" scheme. The effect is an intra-bunch scattering. Elastic scattering between two particles in a same beam bunch changes their energy to deviate from the beam bunch, one with too much and the other with too little energy. The scattering rate of the Touschek effect is proportional to the inverse beam size, inverse third power of the beam energy, the number of bunches and second power of the bunch current. Since the beam size of SuperKEKB is much smaller than that of KEKB, background from the Touschek effect will become much higher. The contribution from the LER is higher than the HER due to asymmetric beam energy. As shown in At SuperKEKB, simple extrapolation using the machine parameters predicts that Touschek background will increase by factor of ∼20 compared to that of KEKB. However, Touschek background is reduced than this prediction because we introduce improved countermeasures to cope with the background. Touschek-scattered particles are lost by hitting the beam pipe inner wall while they propagate around the ring. If their loss position is close to the detector, generated shower might reach the detector. Fake hits generated by the background shower particles deteriorate the detector's physics resolution. Radiation dose by gammas or neutrons in the background shower damage the Silicon devices used in the detector. To cope with Touschek background, there are two countermeasures: movable collimators and heavy-metal shield. The movable collimators located along the ring can stop the deviated particles before they reach close to the detector. Touschek background can be reduced effectively by collimating the beam horizontally from both inner and outer sides, since Touschek-scattered particles have too much or too little energy. At KEKB, we had horizontal collimation only from inner side. The heavy-metal shield is located outside the detector acceptance, between the beam pipe and inner detectors. The shield is made of Tungstenalloy whose radiation length is short, and effectively stops the background showers before they reach the inner detectors

Challenges and concepts for design of an interaction region with push-pull arrangement of detectors - an interface document

Two experimental detectors working in a push-pull mode has been considered for the Interaction Region of the International Linear Collider [1]. The push-pull mode of operation sets specific requirements and challenges for many systems of detector and machine, in particular for the IR magnets, for the cryogenics and alignment system, for beamline shielding, for detector design and overall integration, and so on. These challenges and the identified conceptual solutions discussed in the paper intend to form a draft of the Interface Document which will be developed further in the nearest future. The authors of the present paper include the organizers and conveners of working groups of the workshop on engineering design of interaction region IRENG07 [2], the leaders of the IR Integration within Global Design Effort Beam Delivery System, and the representatives from each detector concept submitting the Letters Of Intent