138183455
COMPARISON BETWEEN HEXABORIDE MATERIALS FOR THERMIONIC CATHODE RF GUN
Thermionic RF guns are widely used as highly brilliant electron source for linac-driven oscillator FEL (free electron laser). They can potentially produce an electron beam with high energy, small emittance, inexpensive and compact configuration in comparison with other high brightness electron sources. The most critical issue of the thermionic RF gun is the transient cathode heating problem due to the electron backbombardment when the gun is used for an FEL driver. The heating property of cathode not only depends on the emission properties of the cathode material, but also the physical properties such as electron stopping power and range. We investigated the heating property of six hexaboride materials against the backbombarding electrons by numerical calculation of the stopping power and range. In this investigation, the emission property of the cathode was taken into account, since high electron emission is required for generation of high brightness electron beam. As a result, cerium hexaboride material has best properties for thermionic RF gun cathode material in the backbombardment effect point of view.
54014117
END FIELD TERMINATION FOR BULK HTSC STAGGERED ARRAY UNDULATOR
Aiming at realizing a short period undulator with strong magnetic field, we have proposed a Bulk HTSC (High Temperature SuperConductor) Staggered Array Undulator which consists of Bulk HTSC magnets with a staggered array configuration [1]. The experiment with the prototype undulator at 77 K shows this configuration can be applicable to real device [2, 3]. We also estimated the magnetic performance of real devices by calculations with a loop current model based on Bean model of type II superconductor [4]. In these experiments, the magnetic field in the ends of the prototype were larger than the field in the center area. End field termination is required for practical use. To suppress the larger magnetic field for end field termination, we performed the calculations and the prototype experiments with the large end gap method. We concluded that the method is effective for Bulk HTSC Staggered Array Undulator.
138747704
Status of the MIR FEL Facility in Kyoto University
A mid-infrared free electron laser (MIR-FEL) facility (KU-FEL: Kyoto University Free Electron Laser) has been constructed for developing energy materials in Institute of Advanced Energy (IAE), Kyoto University. FEL gain saturation at 13.2 μm has been achieved for the first time in May 2008. A beam loading compensation method with feedforward RF phase control has been developed to supply the required quality of electron beam. The FEL beam characterization has been performed. The macro pulse energy of 5 mJ/pulse and the peak power of about 3 MW has been measured. The FEL transport system of wavelength range from 5 to 20 μm has been constructed to the application room. Applications of the MIR-FEL in the renewable energy research at Kyoto University will be started within this financial year.
27880839
On the classical equivalence of monodromy matrices in squashed sigma model
A bstractWe proceed to study the hybrid integrable structure in two-dimensional non-linear sigma models with target space three-dimensional squashed spheres. A quantum affine algebra and a pair of Yangian algebras are realized in the sigma models and, according to them, there are two descriptions to describe the classical dynamics 1) the trigonometric description and 2) the rational description, respectively. For every description, a Lax pair is constructed and the associated monodromy matrix is also constructed. In this paper we show the gauge-equivalence of the monodromy matrices in the trigonometric and rational description under a certain relation between spectral parameters and the rescalings of sl(2) generators.
120173213
Cathode image readout in the BELLE central drift chamber
Abstract We report on the design and construction of the cathode image readout section of the BELLE detector's central drift chamber. The cathode information is used for measurements of charged particle trajectory coordinates along the beam axis and the charged-track trigger. The performance is evaluated with cosmic rays using the BELLE standard readout electronics and software. The detection efficiency in nominal conditions is found to exceed 98% and the position resolution for normal incidence is about 350 μm, which satisfies the design goals of the BELLE detector.
2744251
BPS conditions of supermembrane on the pp-wave
Abstract We study the BPS conditions in the closed supermembranes on the maximally supersymmetric pp-wave background. In particular, the 1/2 and 1/4 BPS states are discussed in detail. Moreover, we comment on the zero-modes in the invariant mass formulae of the theory.
15711173
Non-relativistic string and D-branes on AdS5 × S5 from semiclassical approximation
We show that non-relativistic actions of string and D-branes on AdS5???S5 can be reproduced as a semiclassical approximation of the string and D-brane actions around static 1/2 BPS configurations. This is contrastive to the Penrose limit. For example, the pp-wave string can be recaptured as a semiclassical approximation around a 1/2 BPS particle rotating at the velocity of light. We argue that small deformation of a straight Wilson line would give a composite operator in the gauge-theory side that corresponds to a semiclassical state of the non-relativistic string, according to the semiclassical interpretation.
7387924
Deconfining Phase Transition in QCD_4 and QED_4 at Finite Temperature
We investigate the deconfining phase transition in QCD_4 and QED_4 at finite temperature using a perturbative deformation of topological quantum field theory (TQFT). A modified maximal abelian gauge (MAG) is utilized in the analysis. In this case, we can derive the linear potential studying the 2D theory through Parisi-Sourlas (PS) dimensional reduction. The mechanism of deconfining phase transition is proposed. It is geometrical to discuss the thermal effect on the linear potential. All we have to do is to investigate the behavior of topological objects as such instantons and vortices on a cylinder. This is the great advantage of our scenario. This mechanism is also applied in the case of QED_4. The phase structure at the high temperature of QED is investigated using the Coulomb potential on a cylinder. It coincides with the result in the lattice compact U(1) gauge theory. Also, QCD with MAG has the property called the abelian dominance, which enables us to discuss the deconfinement of QCD_4.