| Paper | Title | Page |
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| TUPMN097 | A Possibility for Using an APPLE Undulator to Generate a Photon Beam with Transverse Optical Modes | 1142 |
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Funding: Work supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract DE-AC02-06CH11357.
Photons that carry orbital angular momentum are of great interest to the optics and laser communities*. This exotic property of photon beams was recently demonstrated in the x-ray regime** and may be useful to probe angular momentum in matter***. However, by comparison to the visible light regime, it is difficult to fabricate efficient achromatic optics to generate these optical modes in x-rays. In spite of these inconveniences, there has been no investigation of the possibility of using a synchrotron light source to directly generate an x-ray beam with transverse optical modes. In this paper, we investigate use of an APPLE-type undulator for generating Laguerre-Gaussian (LG) and Hermite-Gaussian (HG) mode beams. We find that the second harmonic radiation in the circular mode corresponds to an LG beam with l=1, and the second harmonic in the linear mode corresponds to an HG beam with l=1. The combination of an APPLE undulator and conventional monochromator optics may provide an opportunity for a new type of experimental research in the synchrotron radiation community. Detailed discussion will be presented in the conference. We thank C. Quitmann for insightful comments.
* M. Padgett, J. Courtial, L. Allen, Physics Today, p. 35, May, 2004.** A. G. Peele et al., Optics Letters, 27, 1752 (2002).*** M. VanVeenendaal and I. McNulty, Phys. Rev. Lett., submitted. |
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| TUPMN100 | LCLS Undulator Production | 1148 |
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Funding: Work supported by the U. S. Dept. of Energy, under contract numbers DE-AC02-06CH11357 and DE AC03-76SF00515.
Design and construction of the undulators for the Linac Coherent Light Source (LCLS) is the responsibility of Argonne National Laboratory. A prototype undulator* was constructed in-house and was extensively tested. The device was tunable to well within the LCLS requirements and was stable over a period of several years. Experience constructing the prototype undulator led us to conclude that with appropriate engineering design and detailed assembly procedures, precision undulators can be constructed by qualified vendors without previous undulator-construction experience. Our detailed technological knowledge and experience were transferred to the successful bidders who have produced outstanding undulators. Our production concept for the 40 3.4 m long, fixed-gap, planar-hybrid undulators with a 30 mm period is presented. Manufacturing, quality assurance, and acceptance testing details are also presented.
*LCLS Prototype Undulator Report, Argonne National Laboratory Report ANL/APS/TB-48, January 2004, R. Dejus, Editor. |
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| TUPMN044 | Status of R&D Efforts Toward the ERL-based Future Light Source in Japan | 1016 |
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| Energy Recovery Linacs (ERL), based on superconducting accelerators, are one of the most promising synchrotron light sources in future. The KEK and the JAEA, in collaboration with the ISSP, the UVSOR, and the SPring-8, are considering to realize together the ERL-based next-generation light source in Japan. To establish key technologies for that, active R&D efforts started. The R&D program includes the developments of ultra-low-emittance photocathode guns and of superconducting cavities, as well as experimental proofs of accelerator-physics issues at the ERL test facility, which will be built at the KEK campus. We are currently working on constructing a prototype photocathode gun, on designing superconducing cavities, and on designing a prototype ERL. The current plan of the prototype ERL comprises a full injector linac, one or two cryomodules for the main linac, and the beam return loop, which can be operated at beam energies from 60 to 160 MeV. The up-to-date R&D status will be reported. | ||
| FRPMN031 | Commissioning and Status of New BPM Electronics for COD Measurement at the SPring-8 Storage Ring | 3997 |
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| At SPring-8 storage ring, a signal processing circuit for closed orbit measurement and a part of its control system were replaced during summer shutdown period of 2006. In the new circuit, one of four beam signals at the frequency of 508.58 MHz, which is the acceleration frequency of the SPring-8, is selected by a multiplexer and down-converted to IF frequency. The IF signal is sampled by 2 MSPS 16-bit ADC and detected with DSP. On the DSP, spurious frequencies are eliminated by digital filter and effective band-width can be changed by averaging. During the commissioning of the new circuit after the summer shutdown, DSP parameters such as number of averaging were decided to measure beam positions at all BPMs in 3 seconds, although the new circuit was designed with a target repetition of a few 10 Hz or around 100 Hz with resolution of sub-microns. With the DSP parameters, position resolution of less than 0.5 micron is achieved. In this paper, we also describe long term stability, current dependence and beam filling pattern dependence of the new circuit compared with the old one in addition to the position resolution and measurement repetition. |