ICEPP, Tokyo
KEK, Ibaraki
University of Tokyo, Tokyo
In this paper, we describe a system design and current status of Shintake beam size monitor. Shintake monitor is a laser-based beam diagnostics tool, which provides a non-invasive measurement of transverse beam sizes. The interaction target probing the electron beam is interference fringes build up by the two coherent lasers that have narrow bandwidth and long coherent length. A scale of the target structure corresponds to approximately one fourth of the laser wave length, and the smallest measurable size reaches down to several tens of nanometers. The monitor we described here is installed at the virtual interaction point of the ATF2 beam line, which is built to confirm the proposed final focus system for Future Linear Colliders. We adopt second harmonics of Nd:YAG laser of 532 nm wavelength, and phase stabilization feedback system to allow to measure the designed beam size of about 37 nm. To widen a measurable range up to about 5 microns (wire scanner's range), we also prepare three crossing modes that change an effective wavelength for the fringes. The monitor is used to measure a focus size during the tuning process. The system is based on the Shintake monitor for FFTB.
University of Tokyo, Tokyo
KEK, Ibaraki
ICEPP, Tokyo
ATF2 is the final focus test facility for ILC to realize and demonstrate nanometer focusing. One of the goals of the ATF2 is a demonstration of a compact final focus system based on the local chromaticity correction. A designed beam size at the focal point is to be 37 nm in vertical. To achieve the goal, a beam size monitor capable of nanometer beam size measurement is inevitably needed. Shintake monitor satisfies the demands, and is installed at the virtual interaction point of the ATF2. Shintake monitor is a beam size monitor which uses laser interference fringe pattern to measure beam size. The beam test for the Shintake monitor was successful in measurement of signal modulation with the laser interference fringe pattern in November 2009. In April 2010, beam size of less than 1 micron was achieved. We have studied the error sources, and evaluated the total error to be less than 10% for 1 minute measurement. This paper is about the evaluation of the Shintake monitor performance by analyzing beam tests data. Most systematic error sources are well understood, so that we can estimate accuracy of beam size measurement when the beam size reaches 37nm.
SLAC, Menlo Park, California
IHEP Beijing, Beijing
LAL, Orsay
IN2P3-LAPP, Annecy-le-Vieux
ICEPP, Tokyo
University of Tokyo, Tokyo
KEK, Ibaraki
CERN, Geneva
The primary aim of the ATF2 research accelerator is to test a scaled version of the final focus optics planned for use in next-generation linear lepton colliders. ATF2 consists of a 1.3 GeV linac, damping ring providing low-emittance electron beams (<12pm in the vertical plane), extraction line and final focus optics. The design details of the final focus optics and implementation at ATF2 are presented elsewhere* . The ATF2 accelerator is currently being commissioned, with a staged approach to achieving the design IP spot size. It is expected that as we implement more demanding optics and reduce the vertical beta function at the IP, the tuning becomes more difficult and takes longer. We present here a description of the implementation of the overall tuning algorithm and describe operational experiences and performances
* Beam-Based Alignment, Tuning and Beam Dynamics Studies for the ATF2 Extraction Line and Final Focus System. Glen R. White , S. Molloy, M. Woodley, (SLAC). EPAC08-MOPP039, SLAC-PUB-13303.
