Chen-Shiung Hsue

Planar classical Heisenberg model with biquadratic interactions

Seven coefficients in the high temperature series expansions for the zero-field susceptibility and the specific heat are derived for the planar classical Heisenberg model with biquadratic interactions. The critical temperatures and the susceptibility exponents are determined for cubic lattices.

Lattice design of the SRRC 1.3 GeV storage rings

The magnet lattice of the SRRC (Synchrotron Radiation Research Center) 1.3 GeV low-emittance synchrotron light source is presented. The lattice consists of six identical cells. Each cell has a triple-bend-achromat arc and a 6-m dispersion-free long straight section. Quadrupole triplets between the achromat arc and long straight section are employed for tune and beta matching. The ring circumference is 120 m. Bending magnets in the arc are with vertically focusing gradient components. Such combined function magnets can reduce vertical beta function and hence the vertical aperture is small. The emittance is 1.92*10/sup -8/ mrad at 1.3 GeV. Two families of sextupoles are used for chromaticity correction and good dynamic aperture can be achieved.<<ETX>>

Compromize orbital calculations by an improved MC-GBT approach. Core excited states of HF

Abstract An improved MC-GBT formalism, which accounts for the coupling between the MO and Cl coefficients, is derived for the determination of compromize orbitals aiming at an unbiased description of a number of states. The method is applied to the core-excited states of HF. The experimental spectrum is reassigned. The core excitations of HF can be understood within the equivalent-core model. The excited states of the second- and third-row hydrides XH& (k = 1, 2, 3, 4) are compared and their differences are pointed out and explained. In the case of the second row they can be interpreted as Rydberg states, the lowest k states being perturbed due to some σ* antibonding valence character. In the case of the third row, however, some of the lowest core-excited states 1 to 3 are better interpreted as additional σ* valence-type states.

Beam dynamics of the SRRC 1.3 GeV storage ring

The authors present the single particle dynamics of the Synchrotron Radiation Research Center (SRRC) 1.3 GeV storage ring in the presence of nonlinear field errors, closed orbit errors, and insertion devices, and also examine the collective effect of the bunched beam. Using a proposed correction scheme the closed orbit distortion due to typical closed orbit errors can be corrected to 0.1 mm rms. With nonlinear field errors, residual closed orbit distortions, and insertion devices, the dynamic aperture is acceptable. The collective effects such as beam bunch lengthening, growth time of longitudinal and transverse instabilities, intrabeam scattering, and beam lifetime were calculated. The results show that good performance of the ring is achievable.<<ETX>>

The booster to storage ring transport line for SRRC

A 70-m-long booster to storage ring (BTS) transport line has been designed for the SRRC to transport the beam extracted from the booster to the storage ring at 1.3 GeV. The booster is outside the main ring and has a vertical level difference of 4.15 m relative to the ring. The design has been optimized to reach small beam size and to reduce the effects of magnet errors. In total, two families of bending magnets and 17 quadrupoles are used in the BTS line. Diagnostic instruments and correctors are equipped to measure the beam intensity, position, emittance, and energy spread and to steer the beam. A method of injection into the storage ring is also presented.<<ETX>>

Hyperfine structure in the muonic 3He atom

In order to examine the recoil effect, the authors calculate the ground-state hyperfine structure of the muonic 3He by the variational approach, employing an improved set of Hylleraas-type basis functions to deal with the non-relativistic three-body wavefunctions of the muon, electron and 3He nucleus. The convergence of the series is very fast, thus eliminating the problem with the propagation of the truncation errors of the computer machine. Using the recoil correction, delta rec= Delta nu F(3 alpha / pi )(me/mmu ) ln(mmu /m

Quadrupole phase transition of a planar classical Heisenberg model

0 they arrive at the value Delta nu =4166.56+or-0.05 MHz for the total hyperfine-structure splitting of the ground state of the muonic 3He atom. But if they follow the treatment of Borie (1979) for the recoil corrections by treating the ( mu -3He)+ system as a pseudonucleus, they will arrive instead at the value Delta nu =4165.91+or-0.05 MHz. The former seems to be in slightly better agreement with the only experimental result, 4166.3+or-0.2 MHz.

Electronic structures of quasi-one-dimensional ferrimagnetic insulator Ca3Co2O6

The quadrupole phase transition of a planar classical Heisenberg model with biquadratic interactions is investigated by the high-temperature series expansion method. From the quadrupole susceptibility series the critical temperatures and the critical exponents are determined for cubic lattices.

Integral dipole field calibration of the SRRC storage ring combined function bending magnets

Abstract The electronic structures of quasi-one-dimensional ferrimagnetic Ca 3 Co 2 O 6 are investigated using the generalized gradient approximation (GGA) as well as the GGA plus on-site Coulomb interaction ( GGA + U ) scheme. GGA + U calculations reveal that the interchain ferrimagnetic Ca 3 Co 2 O 6 is a Mott–Hubbard insulator rather than a metal given from GGA. In addition, we found an on-site U induced 3 z 2 − r 2 orbital ordering on Co pri sublattice which drives the intrachain ferromagnetic coupling along c -axis. Our findings suggest that strong electron-electron correlation plays an important role in Ca 3 Co 2 O 6 .

Adaptive method of closed orbit correction

Due to the presence of the fringe field on both magnet edges, the real trajectory traced out by the beam will deviate from expectation. The integral dipole strength seen by the beam will then have a discrepancy to design value. The beam tracing method is employed to correct the fringe field effect and to calibrate the integral dipole strength of the bending magnets by tuning magnet current. The final correction factor was achieved in the condition of simulated results met to design requirements. During machine commissioning, the measured betatron tunes were found different from modeling and a correction factor was applied to correct this tune difference. This factor is in well agreement with that predicted by the beam tracing method.