ANL, Argonne, USA
Recently, a grazing-incidence insertion device x-ray beam position monitor (GRID-XBPM) was proposed for the intense x-ray beam from the future APS undulators [*]. By combining the function of limiting aperture with the XBPM, it increases the power-bearing capacity of the XBPM and, at the same time, eliminates the problem of relative alignment of the two critical components in the beamline. Furthermore, by imaging the hard x-ray fluorescence footprint on the collimator, the XBPM is immune to the soft x-ray background, and its accuracy is improved at larger gap settings. In addition to these advantages, the GRID-XBPM can also be implemented to measure center-of-mass of the x-ray fluorescence footprint when pinhole-camera-like optics are used for position readout*. This offers a solution for long-standing XBPM design issues for elliptical undulators, which have a donut-shaped power distribution. In this work, we report design progress for the GRID-XBPM for the high-power elliptically polarized undulator planned for the APS intermediate energy x-ray (IEX) beamline. Computer simulation of its performance and experimental tests from a scale model system will also be presented.
* B.X. Yang, G. Decker, S. H. Lee, and P. Den Hartog, Beam Instrumentation Workshop, Santa Fe, 2010, to be published.
ANL, Argonne, USA
SLAC, Menlo Park, California, USA
Electrons scattered by alumina ceramic transverse beam profile monitors inserted in the Advanced Photon Source (APS) booster-to-storage ring (BTS) transfer line are used to generate C ̆erenkov light for calibration of beam loss monitors (BLMs) installed in the Linac Coherent Light Source (LCLS) undulator beamline. In addition, gas bremsstrahlung (GB) photons generated by 7-GeV electrons in the APS sector 35 storage ring straight section are used to create pair-production electrons for measurement and calibration purposes. Both cases are modeled with the particle-matter interaction program MARS. The realized tuning fork geometry of the BLM exhibits regions of greater sensitivity in the radiator. Transverse GB beam scans have provided uniformity and sensitivity data throughout the volume of the radiator. Comparisons between predicted and measured signal strengths and thermoluminescent dosimeter readings are given and shown to be in reasonable agreement.
ANL, Argonne, USA
LBNL, Berkeley, California, USA
JLAB, Newport News, Virginia, USA
The Advanced Photon Source Upgrade project (APS-U) at Argonne includes implementation of Zholents’* deflecting cavity scheme for production of short x-ray pulses. This is a joint project between Argonne National Laboratory, Thomas Jefferson National Laboratory, and Lawrence Berkeley National Laboratory. This paper describes performance characteristics of the proposed source and technical issues related to its realization. Ensuring stable APS storage ring operation requires reducing quality factors of these modes by many orders of magnitude. These challenges reduce to those of the design of a single-cell SC cavity that can achieve the desired operating deflecting fields while providing needed damping of all these modes. The project team is currently prototyping and testing several promising designs for single-cell cavities with the goal of deciding on a winning design in the near future.
*A. Zholents et al., NIM A 425, 385 (1999).
