Paper |
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TUCC04 |
Measurement of Nanometer Electron Beam Sizes with Laser Interference using IPBSM |
310 |
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- J.N. Yan, S. Komamiya, M. Oroku, T.S. Suehara, Y. Yamaguchi, T. Yamanaka
University of Tokyo, Tokyo, Japan
- S. Araki, T. Okugi, T. Tauchi, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
- Y. Kamiya
ICEPP, Tokyo, Japan
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At ATF2, the Local Chromaticity Correction focusing scheme is to be verified through realizing its design vertical e- beam size (σy ) of 37 nm. The 'IPBSM', installed at ATF2's virtual IP, is the only existing beam size monitor capable of measuring σy < 100 nm, making it indispensable for ATF's goals and R&D at future LCs. This owes to a novel technique of colliding e- beam against laser interference fringes. σy is derived from the modulation depth of resulting Compton photons, which is large for small σy. The measurable range from O(10) nm ~ a few μm, is controlled by switching between laser crossing angles θ = 174° , 30°, and 2° - 8° . In early 2011, measuring σy < 300 nm was hindered by an immense earthquake and heavy signal jitters. The ensuing recovery and upgrades stabilized the laser system and improved resolution to 5%. In spring 2012, we commissioned advanced crossing angle modes by consistently measuring σy ≥ 150 nm. Our goals for the autumn 2012 run is to stably measure σy < 50 nm. Major hardware upgrades during the summer aim at more reliable alignment and optimization of specialized functions to suppress bias factors.
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Slides TUCC04 [10.535 MB]
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