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The Shintake Monitor is an essential beam tuning device installed at the interaction point (IP) of ATF2 [1] , the final focus test beam line of the Accelerator Test Facility (ATF) to measure its nanometer order vertical e − beam sizes ( σ y ⁎ ). The e − beam collides with a target of laser interference fringes, and σ y ⁎ is derived from the modulation depth of the resulting Compton signal photons measured by a downstream photon detector. By switching between several laser crossing angle modes, it is designed to accommodate a wide range of σ y ⁎ from 20 nm to a few micrometers with better than 10% accuracy. Owing to this ingenious technique, Shintake Monitor 1 [2] , [3] is the only existing device capable of measuring σ y ⁎ σ y ⁎ down to the design value of 37 nm. Shintake Monitor has demonstrated stable σ y ⁎ measurement with 5–10% stability. Major improvements in hardware and measurement schemes contributed to the suppression of error sources. This paper describes the design concepts and beam time performance of Shintake Monitor, as well as an extensive study of systematic errors with the aim of precisely extracting σ y ⁎ from the measured modulation.

A novel final focus system design featuring the Local Chromaticity Correction scheme has beenproposed for ILC. This is to be verified at ATF2, a test facility for ILC, through focusing an e-beam down to the design vertical beam size (“σy”) of 37 nm. Shintake Beam Size Monitor (“IPBSM”),installed at the virtual interaction point of ATF2, is the only existing device capable of measuring σy below 100 nm, making it indispensable for achieving the goals of ATF2 and a strong candidate for R&D at future linear colliders. This is attributed to its ingenious technique of scanning the phase oflaser interference fringes relative to the e-beam. Beam sizes are derived from the resulting Compton signal modulation measured by a downstream detector. Having been upgraded in a variety of ways since its first debut at FFTB, Shintake Monitor is capable of measuring a wide range of σy from 25 nm to 6 μm with better than 10% resolution. This paper describes the system's design, role in beam tuning, and various hardware upgrades to further improve its performance.

We developed an electron beam size monitor for nanometer scaled beam sizes. It uses a laser interference fringe for a scattering target with the electron beam. The target beam size for the monitor is 25–6000 nm to achieve and confirm the 37 nm design beam size of ATF2, a final focus test facility for the ILC. Resolution of less than 10% for the full range is shown to be realistic, with a precise fringe control system. We describe the overall design, implementation, and performance of the monitor.

My presentation focuses on the Shintake (Beamsize) Monitor which can measure nanometer electron beam sizes. The Shintake Monitor is installed in the Accelerator Test Facility 2 (ATF2) at KEK, Japan. ATF2 is a realistic scaled down model of the final focus system for the International Linear Collider. The final focusing scheme named the Local Chromaticity Correction will be tested for the first time in the world. The vertical design beam size at the focal point (virtual interaction point) is 37 nm. Shintake monitor has been designed to measure a beamsize down to 20 nm. It employs the interference pattern made by splitting laser beams and crossing them at the focal point of the electron beam. In their intersecting region, the electromagnetic fields of the two laser beams form a standing wave (interference fringe). The probability of the Compton scattering varies according to the phase of the standing wave where the electrons pass through. Then the total energy of photons from the Compton scattering is measured in a multi-layered ganma ray detector located downstream from the interaction point. This scheme was originally proposed by T. Shintake whose team measured a beamsize of approximately 65 nm with 10 percent resolution at FFTB, SLAC, a former test facility for the ILC. We upgraded this monitor to measure the even smaller beam sizes to be available at ATF2. The laser wavelength has been modified from 1064 nm to 532 nm using a second harmonics generator. The laser optics was newly designed and constructed by implementing a laser wire scheme to measure a larger horizontal beam size, and by enabling different crossing angles of split laser beams to measure a wide (diverse) range of vertical beam sizes. The gamma detector for Shintake monitor has also been newly developed. We evaluated the performance of Shintake monitor with a beam of several microns in size and confirmed its consistency with wire scanner measurements. The expected performance of the Shintake monitor and the current status of the electron beam at ATF, achieved a record in beam size history and near future plan for 37 nm beam size measurement will be mentioned.

A calorimetric detector for inverse-compton photons from the Shintake monitor at the ATF2 test beam facility at KEK is developed. The Shintake monitor is the precision beam size monitor based on laser interferometer, which is planned to be used at a commissioning of the ILC beam delivery system. The detector has original structure to separate the compton signal from Bremsstrahlung background using the difference in shower development. The beam test of the detector was performed at ATF in the 2007’s winter using a laser wire and a wire scanner. It was confirmed to be able to see the difference in the shower development and to separate compton photons from Bremsstrahlung photons. The beamtest plan of Shintake monitor at ATF2 on 2008’s winter is also described.