Lattice of the KEKB colliding rings Koiso, Haruyo; Morita, Akio; Ohnishi, Yukiyoshi ...
Progress of theoretical and experimental physics,
03/2013, Letnik:
2013, Številka:
3
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This paper describes a few outstanding features of the beam-optical lattice of the KEKB colliding rings. A chromaticity correction scheme with non-interleaved sextupole pairs, a new cell structure ...with 2.5π betatron phase advances, etc. have been introduced. The lattice successfully squeezed the vertical beta functions at the interaction point, which greatly contributed to the achievement of the world's highest luminosity.
The KEKB injector linac Akemoto, Mitsuo; Arakawa, Dai; Enomoto, Atsushi ...
Progress of theoretical and experimental physics,
03/2013, Letnik:
2013, Številka:
3
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The KEKB injector linac has been continuously improved to enhance the stability of many devices and the efficiency of beam operation. These improvements include the development of the new C-band ...accelerating structure, pulse compressor, klystron, rf window, compact modulator, and the new positron production target using crystalline tungsten. We have also achieved two-bunch beam acceleration, the development of an energy spread monitor, a safety system upgrade, and an event-based timing and control system. These developments and practical applications for advanced linac beam handling result in the success of the simultaneous top-up injection among the three independent storage rings. This result greatly improves the integrated luminosity and the operation stability of the KEKB rings. In this paper, we present the progress of the KEKB injector linac in this decade.
The KEK Accelerator Test Facility (KEK-ATF) was constructed to develop technologies for producing a low-emittance beam which will be required by future linear colliders. The KEK-ATF consists of an ...injector linac, a damping ring, and a beam extraction line. The basic optical structure of the damping ring is a FOBO lattice, which reduces the horizontal dispersion at the center of the bending magnets and, as a consequence, can produce an extremely small emittance beam. To verify the performance of such a unique, low-emittance lattice, it is crucial to measure the horizontal emittance. The horizontal emittance was measured using wire scanners in the beam extraction line. Since the horizontal beam position was not stable, we established a method to correct the measured beam size for position fluctuation (“jitter”) and we succeeded in the observation of the so far smallest horizontal emittance in any accelerator. The measured horizontal emittance was 1.37±0.03nm at a beam energy of 1.285 GeV and a bunch population of \(3–5\)×10^{9}, in agreement with the design value of 1.27–1.34 nm at the beam energy and the bunch population.
The usual formulas for the resistive-wall wake field are derived considering ultrarelativistic beams, traveling at the speed of light. This simplifies the calculation, and it leads to a cancellation ...between electric and magnetic fields. However, for proton beams below 10 GeV and for many heavy-ion beams, the velocities may significantly differ from the speed of light. In this paper, we compute the longitudinal and transverse wake fields for velocities smaller than c and examine under which conditions nonrelativistic effects become important. We illustrate our results by a few examples.
A calculation method of emittance growth of an electron beam due to intrabeam scattering is described. The 3 degrees of freedom are equally treated in the beam rest frame, and the couplings between ...them are included in a natural way. This formalism is suitable for the calculation of the emittance growth with the beam-envelope method.
Commissioning of KEKB Abe, Tetsuo; Akai, Kazunori; Cai, Yunhai ...
Progress of theoretical and experimental physics,
03/2013, Letnik:
2013, Številka:
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The machine commissioning of KEKB started in December 1998 and its operation was terminated at the end of June 2010 to upgrade KEKB to SuperKEKB. In this paper, we describe the commissioning ...procedure of KEKB from 2002 to 2010.
Unilateral ureteral obstruction (UUO) of kidneys causes acute generation of carbonyl stress. By electrospray ionization/liquid chromatography/ mass spectrometry (ESI/LC/MS) we measured the content of ...methyl glyoxal, glyoxal, and 3-deoxyglucosone in mouse kidney extracts following UUO. UUO resulted in elevation of these dicarbonyls in the obstructed kidneys. Furthermore, the accumulation of 3-deoxyglucosone was significantly reduced in the kidneys of mice transgenic for alpha-dicarbonyl/L-xylulose reductase (DCXR) as compared to their wild-type littermates, demonstrating 4.91 +- 2.04 vs. 6.45 +- 1.85 ng/mg protein (P = 0.044) for the obstructed kidneys, and 3.68 +- 1.95 vs. 5.20 +- 1.39 ng/mg protein (P = 0.026) for the contralateral kidneys. On the other hand, collagen III content in kidneys showed no difference as monitored by in situ hybridization. Collectively, DCXR may function in the removal of renal alpha-dicarbonyl compounds under oxidative circumstances, but it was not sufficient to suppress acute renal fibrosis during 7 d of UUO by itself.
Elastic stability theory is applied to description of tensile strength variation in steel members due to variation of initial imperfections, despite criticism on the occurrence of unloading due to ...plastic instability. In numerical simulation of such members, the maximum load is attained at a limit point or a hilltop bifurcation point. This load is not much different for either type of point; hence, little attention has been paid to the type of points up to now. Yet it is noteworthy that these two types of points follow different imperfection sensitivity laws within the framework of elastic stability theory. Numerical experiments on steel members undergoing plastic deformation are conducted to ensure that empirical imperfection sensitivities for these members agree well with those sensitivity laws. This assesses applicability of elastic stability theory to description of plastic instability behaviors of steel members. Moreover, empirical histograms of steel members obtained through Monte-Carlo simulations are compared with theoretical probabilities of maximum loads, which are a normal distribution for the limit point and a Weibull-like one for the hilltop point. Therefore, elastic stability theory is useful to describe tensile strength variation of steel members.
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