Precise study of the first deflecting magnet of ＂Rhodotron＂ （TT200） using transfer matrices and ANSYS11

The beam trajectory in the first deflecting magnet of ＂Rhodotron＂ TT200 has been analyzed precisely by both optical and simulation methods. We found discrepancies between these two methods at the order of （10-3） for the slit distance and deflecting radius and at the order of （10-4） for the magnetic flux density. The main goal of the paper is beam focusing, considering the angular and momentum dispersion of the particles for the magnet designed by ANSYS.     

Sm2Co17 magnet blocks for the in-vacuum undulators (IVU20) at the SSRF

The design and development status of Sm<,2>Co<,17> magnet blocks for two in-vacuum undulators (IVU20) at the SSRF with the same hybrid design has been described. By the technological improvement of some processes and comparison with the experimental Sm<,2>Co<,17> magnet blocks for the IVU25A, magnetic properties such as the intrinsic coercive force H<,ci> and the average magnetic moment M are increased, the bend point magnetic field H<,k> value and pass rate are significantly increased, and the magnetic field uniformity of the magnet blocks are significantly improved. The basic developmental method of high uniformity Sm<,2>Co<,17> magnet blocks for IVU20 is presented. The magnetic field qualities of the magnet blocks, including the magnetic property, the magnetic moment distribution, the magnetization deviation angle and the magnetic field uniformity, basically satisfy the specifications of the two IVU20 in-vacuum undulators.     

光泵磁共振法测量地磁场水平分量BE11

采用与示波器同步的扫描场探测光磁共振,使光磁共振信号稳定;选择扫场的同一点(最好选在峰点或谷点)作参考点。有利于结合实际情况测地磁场水平分量BE11。     

Nd(Fe,Si)11Cx化合物的全电子计算(x=0,2)

采用基于第一原理的全势能线性缀加平面波加局域轨道((L)APW lo)方法对Nd(Fe,Si)11Cx化合物(x=0,2)的电子结构进行了计算,得到了化合物态密度和磁矩等信息.计算结果表明NdFe9Si2化合物中Si原子主要与4b和32i位Fe原子产生杂化,导致Fe原子磁矩减小.NdFe9Si2C2化合物C原子使32i位Fe原子磁矩进一步降低,同时减弱了Si原子的影响,使得4b位Fe原子磁矩增大.     

Effect of composition on texture and magnetic the crystallographic properties of the Sm（Co,Fe,Cu,Zr）z ribbons prepared by simple processing

Sm(Co_balFe_yCu_xZr_w)_z ribbons have been prepared by melt spinning at a low wheel velocity followed by short-time aging and slow cooling the as-spun ribbons from 850 to 400℃. It is found that the composition can significantly influence the degree of crystallographic texture of the ribbons. The 1:7 phase of the as-spun ribbons is segregated into 1:5 and 2:17 phases by the simple processing procedure. However, the crystallographic texture is still preserved in the ribbons after precipitation hardening. (BH)_{\rm max} about 86kJ/m^{3} can be obtained in the Sm(Co, Fe, Cu, Zr)_{z} ribbons by the adjustment of composition.     

A design of novel type superconducting magnet for super—high field functional magnetic resonance imaging by using the harmonic analysis method of magnetic vector potentials

The approach of expanding the magnetic scalar potential in a series of Legendre polynomials is suitable for designing a conventional superconducting magnetic resonance imaging magnet of distributed solenoidal configuration. Whereas the approach of expanding the magnetic vector potential in associated Legendre harmonics is suitable for designing a single-solenoid magnet that has multiple tiers, in which each tier may have multiple layers with different winding lengths. A set of three equations to suppress some of the lowest higher-order harmonics is found. As an example, a 4T single-solenoid magnetic resonance imaging magnet with 4×6 layers of superconducting wires is designed. The degree of homogeneity in the 0.5m diameter sphere volume is better than 5.8 ppm. The same degree of homogeneity is retained after optimal integralization of turns in each correction layer. The ratio B_m/B₀ in the single-solenoid magnet is 30% lower than that in the conventional six-solenoid magnet. This tolerates higher rated superconducting current in the coil. The Lorentz force of the coil in the single-solenoid system is also much lower than in the six-solenoid system. This novel type of magnet possesses significant advantage over conventional magnets, especially when used as a super-high field functional magnetic resonance imaging magnet.     

Design of magnet and control of the beam emittance for Penning H^- ion source

The design requirement and principle of the deflection magnet for Magnetron and Penning H- ion source are discussed. It is proved that there exists a maximum emittance for the beam that may be transformed by the magnet into a state with equal Twiss parameters of αr =αy and βr =βy, which is the requisite condition to get a minimum emittance at the entrance of RFQ after transporting by a LEBT with solenoids. For this maximum emittance, the corresponding magnetic field gradient index is 1.     

Design of magnet and control of the beam emittance for Penning H- ion source

The design requirement and principle of the deflection magnet for Magnetron and Penning H- ion source are discussed.It is proved that there exists a maximum emittance for the beam that may be transformed by the magnet into a state with equal Twiss parameters of αr=αy and βr =βy,which is the requisite condition to get a minimum emittance at the entrance of RFQ after transporting by a LEBT with solenoids.For this maximum emittance,the corresponding magnetic field gradient index is 1.     

Mössbauer Investigation of the Itinerant Magnets U(Ga0.98Sn0.02)3 and CeFe2

The theoretical predictions that UGa₃ and CeFe₂ should be regarded as itinerant magnets stimulated new investigations. In this paper we focus on Mössbauer measurements aimed to characterize their magnetic properties. We show that the analysis of the transferred hyperfine interactions at the ¹¹⁹Sn nuclei in U(Ga_0.98Sn_0.02)₃, a type II antiferromagnet, provides direct information on the f-p hybridization and allows to determine the orientation of the U moments. The study of CeFe₂ demonstrates that the intrinsic ferromagnetism coexists with short range antiferromagnetic correlations. The instability of the ferromagnetic state is illustrated by doping CeFe₂ with a small amount of Co and by application of pressure on pure CeFe₂. Our results will be discussed in connection with neutron and synchrotron experiments.     

(GaMn)As体系中Mn无序对其电子结构及磁性影响的第一性原理研究

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Effects of ultra-strong magnetic field on electron capture rates of~(55)Co and ~(56)Ni in the magnetar surrounding

The electron capture rates of~(55)Co and~(56)Ni in the ultra-strong magnetic field at four typical temperaturedensity points have been calculated using the nuclear shell model and Landau energy levels quantized approximate correction.The results show that the electron capture rates of~(55)Co and~(56)Ni are increased greatly in the ultra-strong magnetic field,and even exceed two orders of magnitude in the range from 4.414×10~(13)G to 2.207×l0~(17)G.The change rate of electron abundance,Y_e,of~(55)Co and~(56)Ni under the condition of B=4.414×l0~(15)G in the magnetar surrounding has been calculated and discussed,the proportions of Y_e of~(55)Co and~(56)Ni in the total Y_e have been reduced by 50percent in all more than the condition without a magnetic field.     

Surface tension calculations of the cationic (CTAB) and the zwitterionic (SB3-12) surfactants using new force field models: a computational study

Actual CTAB and SB3-12 surfactant force field models fail to reproduce one of the most important thermodynamic property of those molecules, the surface tension. Molecular dynamics simulations were conducted to construct new force fields of the cationic surfactant, Cetyl Trimethyl Ammonium Bromide (CTAB), and the non-ionic, cocoamidopropyl betaine, surfactants using united atom models. By scaling the Lennard Jones parameters, the well depth potential (ε) and the intermolecular distance (σ), we constructed an united atom model of the cationic and the betaine surfactants. The new models were tested with actual experiments reported in the literature. With the correct parameters, surface tensions of both surfactants were calculated at different temperatures and different areas per molecule. Electrostatic properties and micelle structures were also calculated with the new set of parameters and radius of gyrations, i.e. micelle radius, were evaluated showing good affinity with experimental data. The new force fields were proved with two different water models, TIP4P/ε and SPC/E, having good agreement with actual experiments     

CoAlN(N=2-11)团簇基态结构的稳定性和磁性

采用密度泛函理论中的广义梯度近似(GGA),对CoAlN(N=2-11)团簇进行构型优化和磁性计算.在考虑自旋多重度的情况下得到了团簇的平衡构型及基态结构,并重点讨论了Co原子的sp-d杂化效应对体系稳定性和磁性的影响.结果表明:N为偶数时,团簇的基态为自旋双重态,Co原子磁矩随N增加整体上呈减小趋势;N为奇数时(除N=5为自旋三重态外),团簇的基态为自旋单重态,Co原子磁矩为零.N≥8时,Co原子陷入主团簇内部,体系的对称性降低,稳定性增强;轨道杂化增强了体系的稳定性,但减小了双重态和三重态体系中Co原子的磁矩;N=3,8,10是团簇CoAlN(N=2.11)的幻数.     

Study of local magnetic fields and magnetic ordering in fluid and solid matrices containing magnetite nanoparticles using TEMPOL stable radical

The stable nitroxide radical 2,2,6,6-tetramethyl-4-hydroxy-piperidin-1-oxyl (TEMPOL) has been applied as a sensor to study magnetite nanoparticles both in water suspension and in dried gelatin films. g-values and line widths of ESR spectra of the probe were found to be sensitive to the local magnetic fields of magnetic nanoparticles. Calculated on the basis of the sensor ESR spectra, local magnetic fields are stipulated by linear aggregates of magnetite nanoparticles formed in applied outer magnetic fields and are significantly lower than local magnetic fields estimated from the static magnetic measurements data.     

Crystal field analysis of the magnetic properties of RFe11Ti and RFe11TiH （R=Sm, Tb, Ho）

The crystalline-electric-field parameters Anm for RFe11Ti and RFe11TiH （R=Sm, Tb, Ho） are evaluated by fitting calculations to the magnetization curves measured on the single crystals or on magnetically aligned powder samples at 4.2K and higher temperatures. Interstitial hydrogen atom in RFe11Ti has been found to have a significant effect on crystalline-electric-field parameters Anm. By using the parameters of exchange field 2μBHex estimated from inelastic neutron scattering experiments and the fitted Anm, the calculations can reproduce the experimental curves well.     

SrCoO3电子结构和磁学性质的第一性原理研究

通过基于密度泛函理论的广义梯度近似GGA+U方法对铁磁相SrCoO₃的电子结构和磁学性质进行了系统研究.结果表明:随着U值的增大,对于Co离子,主自旋方向的t_2g和e_g态向低能级移动,而次自旋方向的t_2g和e_g态向高能级移动;O2p电子态的分布基本不随U变化.能带结构表明,U大约在7-8eV之间时,SrCoO₃由金属性转变为半金属性.U值小于7eV时,Co离子的磁矩随着U值的增大几乎成线性增大,而当U大于7eV后基本保持不变.结合实验结果,本文认为U取8eV时得到的计算结果更为合理,Co离子的磁矩为3.19μв,且SrCoO₃表现出半金属特性.     

Binding energy of the donor impurities in GaAs-Ga_(1-x)Al_xAs quantum well wires with Morse potential in the presence of electric and magnetic fields

The behavior of a donor in the GaAs–Ga_(1-x)Al_xAs quantum well wire represented by the Morse potential is examined within the framework of the effective-mass approximation. The donor binding energies are numerically calculated for with and without the electric and magnetic fields in order to show their influence on the binding energies. Moreover, how the donor binding energies change for the constant potential parameters(De, re, and a) as well as with the different values of the electric and magnetic field strengths is determined. It is found that the donor binding energy is highly dependent on the external electric and magnetic fields as well as parameters of the Morse potential.     

A novel technique for measurement of self-generated magnetic fields and the plasma density in laser produced plasmas from the Faraday rotation using two color probes

Diagnostic information about the self-generated magnetic fields (SGMF) generated in laser produced plasmas is normally obtained by measuring the Faraday rotation angle (FRA) of a linearly polarized laser probe beam passing through the plasma. Simultaneous recording of the corresponding interferogram is required to get the density information necessary for estimating the magnetic field. The problem with this method is that the visibility of the fringes in the interferogram can be poor, and the SGMF cannot be calculated in the regions where the interference fringes are not observable. In this paper, we propose a new method to obtain the density distribution and the SGMF from two simultaneous measurements of FRA using two probe beams of different colors, which allows one to calculate the SGMF without the need of interferometry.     

B$lt;sub$gt;$lt;i$gt;n$lt;/i$gt;$lt;/sub$gt;Y($lt;i$gt;n$lt;/i$gt;=1–11)团簇的结构和电子性质

利用密度泛函理论TPSSh方法对B采用6-311+G(d), 对Y采用Lanl2dz相对论有效势基组, 研究了B_nY (n=1–11)团簇的平均结合能、二阶能量差分、最高分子占据轨道和最低空轨道之间的能级间隙、极化率和第一静态超极化率等物理化学性质. 结果表明, 随着尺寸的增大, B_nY (n=1–11)团簇的最低能量结构从平面逐步演变为立体结构. 随硼原子数n的增加, 团簇的平均结合能表明了较好的热力学稳定性, 有利于Y掺杂B团簇形成较大的块体材料.二阶能量差分表明基态B₃Y, B₅Y和B₇Y团簇较相邻团簇稳定. 能隙表明了基态B₃Y, B₅Y, B₇Y和B₉Y的化学稳定性较高. 综合说明B_nY (n=1–11)硼团簇中, 基态B₃Y, B₅Y和B₇Y具有较好的稳定性. 极化率表明基态B_nY团簇的电子结构随B原子的增加趋于紧凑, 第一静态超极化率表明基态B₅Y, B₄Y, B₃Y和B₆Y平面结构的团簇具有明显的非线性光学性质, 为寻找性能优异的非线性光学材料提供了一定的参考. 关键词： 密度泛函TPSSh方法 nY (n=1–')" href="#">B_nY (n=1– 11)团簇 几何结构 电子性质